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TEXT-BOOK OF PALEONTOLOGY

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MACMILLAN AND CO., Limited

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TEXT-BOOK

OF

PALEONTOLOGY

EDITED BY

CHAKLES R. EASTMAN, A.M., Ph.D.

PROFESSOR OF PALEONTOLOGY IN THE UNIVERSITT OF PITTSBURGH
AND CÜRATOR AT THE CARNEGIE MUSEUM, PITTSBURGH

ADAPTED FROM THE GERM AN OF

KARL A. VON ZITTEL

LATE PROFESSOR OF GEOLOGY AND PALEONTOLOGY IN THE UNIVERSITY OF MUNICH

SECOND EDITION REVISED AND ENLARGED BY THE EDITOR IN COLLABORATION
WITH THE FOLLOWING-NAMED SPECIALISTS :

R. S. BASSLER, W. T. CAL^LW, A. H. CLARK, H. L, CLARK, J. M, CLARKE,

J. A. CUSHMAN, W. H. DALL, A. HANDLIRSCH, K. T. JACKSON, A. PETRÜNKEVITCH, P. E. RAYMOND,

R. RUEDEMANN, C. SCHÜCHEBT, J. T. SMITH, F. SPRINGER, T. W. VAÜGHAN, C. D. WALCOTT

\
I

VOL. I.
WITH ABOUT 1600 ILLUSTRATIONS

MACMILLAN AND CO., LIMITED

ST. MAETIN'S STREET, LONDON

1913

COPYRIGHT

There i.s nothing good in tliis world but that wliicli is true." — Diderot.

First Edition, 1900
Second Edition, 1913

1

I

EDITOR'S PEEFACE TO THE SECOND EDITION

A NEW Eiiglish editioii of von Zittel's Text-hook of Paleontology having been
called for, advantage was taken of the opportunity to prepare a thorough-
going revision of the first volume, in order that an adequate account might
be incorporated of the new knowledge that has been gained during recent
years.

Towards this end, a number of specialists were invited to collaborate with
the Editor in preparing a fresh treatment of the leading groiips of Inverte-
brates, and the present work bears witness to the generous response that was
made to this invitation. Many parts of the work have been entirely re-
written, others have been emended, rearranged and enlarged, and the
Classification in various places has been very considerably altered. The new
work, therefore, cannot with either justice or propriety be called von
Zittel's Text-book, being in effect a composite production ; and yet in scope
nd style it is modelled after the well-known German original.

The names of the diflerent collaborators appear on the title-page, and the

ections that have been revised or rewritten are credited in the body of the

work to the specialists responsible for them. To all of his collaborators

the Editor desires to offer grateful acknowledgments, and to express the

sense of his owii joersonal indebtedness to them for the large service they have

endered, and for many individual courtesies.

To his friend and former associate at Harvard, Doctor Eobert Tracy
ackson, the Editor is under an Obligation greater than can be adequately
icknowledged ; for besides having contributed practically a fresh account of
he Echini, Dr. Jackson has carefully read the proofs of the entire work, and
as offered in many places most valuable suggestions and emendations. Like
everal of the other collaborators, also, he has furnished the Originals for a
umber of new figures. The total number of fresh illustrations has thus been
ensibly increased. It is hoped that the large amount of painstaking work
hich has been bestowed upon the present treatise will be found to yield
eturns in increased value and usefulness among students of Paleontology
generally.

CHARLES R. EASTMAN.

I

Carnegie Museum, Pittsburgh,
Pennsylvania, June 5, 1913.

Al'i'S

LIST OF COLLABORATOKS FOR THE
SECOND EDITION

Dr. Joseph Augustus Cushman, Foraminifera.

Dr. T. Wayland Yaughan, Adinozoa.

Dr. EuDOLF EuEDEMANN, GmptoUtoidea.

Mr. Frank Springer, Cystoidea, Blastoidea, Crinoidea.

Dr. Arthur Hobart Clark, Post-Paleozoic Crinoidea.

Dr. Hubert Lyman Clark, Asteroidea, Holothuroidea .

Dr. Robert Tracy Jackson, Echinoidea.

Dr. Ray S. Bassler, Bryozoa.

Prof. Charles Schuchert, Brachiopoda.

Dr. William Healy Dall, Pelecypoda, Gastropoda {jmrs).

Prof. James Perrin Smith, Ammonoidea.

Dr. Percy E. Raymond, TriloUta.

Dr. Charles D. Walcott, TriloUta {pars), Arachnida (pars).

Dr. Ray S. Bassler, Branchiopoda, Ostracoda.

Dr. William T. Calman, Cirripedia, Malacostraca.

Dr. John M. Clarke, Phyllocarida, Arachnida.

Dr. Alexander Petrunkevitch, Embolobranchiafa, Myriapoda.

Dr. Anton Handlirsch, Inseda.

ORIGINAL AUTHOß'S PEEFACE

Die englische Ausgabe meiner Grundzüge der Palaeontologie hat ein vom
deutschen Original in verschiedener Hinsicht abweichende Gestalt erhalten.
Der Herausgeber, mein Freund und ehemaliger Schüler Dr. Eastman, suchte
mit meiner Zustimmung eine Anzahl der hervorragendsten Specialisten für
die Bearbeitung einzelner Thierclassen zu gewinnen. Dadurch erfuhr das
Werk eine gründliche und sachkundige Ueberarbeitung, welche sich namentlich
im Detail vortheilhaft geltend macht und mancherlei Irrthümer der deutschen
Ausgabe beseitigte. Für diese mühevolle und aufopfernde Arbeit bin ich den
Mitarbeitern des Text-Book zu grossem Dank verpflichtet.

Allerdings wurde durch die Betheiligung einer grösseren Anzahl von
Autoren, deren Anschauungen in systematischen Fragen nicht immer unter
einander und mit denen des Autors der deutschen Ausgabe in Einklang standen,
die Einheitlichkeit des Werkes nicht unerheblich gestört und auch der ursprüng-
liche Umfang verschiedener Abschnitte bedeutend überschritten ; allein diese
Nachtheile dürften durch die sorgfältigere Durcharbeitung des eigentlichen
Stoff'es reichlich ausgeglichen sein.

Die Revision der Crinoideen hatte der verstorbene Herr Charles TFachsrmith,
jene der Asteroideen und Echinoideen Herr fF. Percy Sladeii übernommen.
Abgesehen von einigen Abänderungen, welche mehr terminologische als
chliche Fragen betreffen, wurde in diesen Abtheilungen eine weit voll-
tändigere Aufzählung und Charakterisierung der fossilen Gattungen durch-
eführt, als in der deutschen Ausgabe. Weitergehende Umgestaltung erfuhr
die Classe der Bryozoen durch Herrn E. 0. Ulrich. Die paläozoischen Formen
eind von diesem ausgezeichneten Kenner mit einer Ausführlichkeit behandelt,
welche nicht ganz mit der Darstellung anderer Abtheilungen in Einklang
steht. Auch die Transferierung der bereits bei den Korallen abgehandelten
Chaetetiden und Fistuliporiden zu den Bryozoen und die dadurch veranlasste
doppelte Darstellung derselben ist eine Incongruenz, welche sich nur durch die
Meinungsverschiedenheit über die zoologische Stellung dieser ausgestorbenen

I Organismen entschuldigen lässt.
Eine durchgreifende Umarbeitung haben die Brachiopoden durch Herrn
Charles Schuchert erfahren. Während sich die deutsche Ausgabe mehr auf die

viii TEXT-BOOK OF PALEONTOLOGY

Werke und Anschauungen von Thomas Davidson stützt, folgt die englische
Uebersetzung sowohl in der Auffassung der Gattungen und Familien, als auch
in den systematischen Principien den neusten Arbeiten von James Hall, J. M.
Clarke, und C. E. Beecher. Die systematischen Hauptgruppen sollen hier
zugleich entwicklungsgeschichtlichen Phasen entsprechen und das ganze
SjT'stem den Anforderungen des biogenetischen Grundgesetzes genügen. Von
ähnlichen Gesichtspunkten wurden auch Professor Beecher bei der Bearbeitung
der Trilobiten und Professor Hyaft bei jener der Gephalopoden geleitet. Es
ist mir zweifelhaft, ob die Zeit zu einer durchgreifenden Reform der bio-
logischen Systematik, bei welcher weniger morphologische und vergleichend-
anatomische Merkmale, als embryologische und phylogenetische Gesichtspunkte
im Vordergrund stehen, jetzt schon gekommen ist ; allein jedenfalls sucht die
in Nord Amerika gegenwärtig herrschende Strömung auf einem neuen Weg
zur Wahrheit zu gelangen und eine die genealogischen Beziehungen deutlicher
wiederspiegelnde Systematik zu erzielen.

Bei den Pelecypoden hat Herr Dr. JF. H. Dali die durch Neumayr eingeführten
und in den Grundzügen mit einigen Modificationen angenommenen Gruppen
durch seine eigene, auf langjährige Spezialuntersuchungen basirte Eintheilung
ersetzt. Die Scaphopoden, Amphineuren, Gastropoden und Pteropoden
wurden von Herrn Professor //. A. Pilsbry, die Crustaceen mit Ausnahme der
Trilobiten und einiger anderer Gruppen von Professor /. S. Kingsley, und die
übrigen Arthropoden von meinem langjährigen Mitarbeiter und Freund
Professor S. H. Scudder in sachkundigster Weise durchgesehen.

Für den wichtigen Abschnitt der Gephalopoden trägt Herr Professor
Alpheus Hyatt die Verantwortlichkeit. Hier treten die Differenzen mit der
deutschen Ausgabe am auffallendsten zu Tage, vertritt doch dieser Autor am
entschiedensten die moderne Richtung in Amerika. Obwohl meine An-
schauungen über verschiedene Grundprinzipien der Systematik, namentlich
über Abgrenzung von Familien, Gattungen und Arten von denen meines
amerikanischen Collegen abweichen, so glaubte ich doch einem so hervorra-
genden Kenner der fossilen Gephalopoden bei der Bearbeitung des von ihm
übernommen Abschnittes völlig freie Hand lassen zu müssen. Das Text-
Book ist dadurch um eine Averthvolle Originalarbeit bereichert worden, welche
viele bis jetzt noch nicht veröffentlichte Thatsachen enthält.

Zu ganz besonderem Dank bin ich dem Herausgeber der englischen'
Ausgabe Herrn Dr. C. R. Eastman verpflichtet. Er hat keine Mühe gescheut,
das Werk mit den neusten Ergebnissen der paläontologischen Forschung in
Einklang zu bringen und den Fortgang derselben zu fördern.

Dr. KARL A. von ZITTEL.

München, im Septe^yiber 1899.

EDITOK'S PREFACE TO THE FIRST EDITION

The Gnmd.ziige der Paldeontologie, which. forms the basis of the present work,
was published in the spring of 1895, only a short time after the completion
of the fifth and last vohime of Professor von Zittel's celebrated Handbuch der
Falaeontologie. Of the latter, an excellent translation exists in French by
Barrois ; but English-speaking students are without either an independent
treatise on Paleontology or translation from any foreign work, which is
comparable in scope and character to the writings of von Zittel.

With the hope of supplying this deficiency the Editor undertook the task
of rendering the Grundzüge into English. It was at first intended to bring
out a strictly literal translation, but with the Author's consent this plan was
modified in important respects which should be clearly understood by all.
The chapters on Protozoa and Coelenterata stand here essentially as in the
original, but nearly all the remaining chapters have been remodelled, enlarged,
and brought as nearly as possible up to date by a selected body of experts.

The greater part of the work is therefore a composite production, and
from the nature of the case some incongruities in style and treatment are to
be expected. For all the collaborators to have adhered to uniform limits of
alteration and expansion would have been impossible. It will be found,
therefore, that some portions of the revised text are not sensibly difFerent
from the original while others are changed very radically, and a few chapters,
notably the Molluscoidea, Mollusca, and Trilobites, are entirely rewritten. An
eftort has been made throughout to adapt the text more especially to the
needs of Anglo-American students, and the bibliographies have been enlarged
with similar intent.

For all changes in the Classification over the original tho revisers of the
different sections are responsible ; but although radical departures have been
made with the Author's sanction, one must by no means presume he is thereby
committed to all the innovations which are set forth. How far and whether
in all cases the system has been improved must be left for experience to
determine. The Author's graciousness, however, in yielding his own prefer-
ences on systematic points will be apparent on reading his annexed preface.

Due acknowledgments are rendered the collaborators in the Author's

X TEXT-BOOK OF PALEONTOLOGY

preface, and also in footnotes at the end of the several chapters. Their
names are enumerated below in the order of their respective sections, and the
Editor begs to express at this time a sense of his profound appreciation of the
Services that have been so generously rendered. For the many personal
courtesies extended, he would return to each of them his sincere and hearty
thanks.

LIST OF COLLABORATORS

Mr. Charles "Wachsmuth, Grinoidea, Blastoidea.

Mr. W. Percy Sladen, Astero^wa, Echinowa.

Dr. George Jennings Hinde, Vermes.

Mr. Edward 0. Ulrich, Bryozoa, Ostracoda.

Mr. Charles Schuchert, Brachiopoda.

])r. William H. Dall, Pelecypoda.

Prof. Henry A. Pilsbry, Gastropoda.

Prof. Alpheüs Hyatt, Gephalopoda.

Prof. Charles E. Beecher, TrUohita.

Prof. John M. Clarke, Eucrustacea (pars), Äcerata (pars).

Prof. John S. Kingsley, Eucrustacea (pars), Äcerata (pars).

Prof. Samuel H. Scudder, Insecta.

The Editor is also greatly indebted to his friend Dr. John C. Merriam,
who undertook the translation of the entire chapter on Mollusca, a very
laborious work. Dr. Merriam's assistance has been further enlisted in the
translation of the second volume, which will be devoted exclusively to the
Yertebrates. Dr. August F. Foerste Avas kind enough to furnish a transla-
tion of the chapter on Insects, and various friends have assisted in correcting
proofs. For the compilation of the index the Editor is indebted to Miss
Elizabeth B. Bryant, a former Student of his at KadclifFe College, and to
his brother, Mr. David P. Eastman.

CHARLES E. EASTMAN.

Harvard University,
SeiJtemher 15, 1899.

CONTENTS

INTRODUCTION

PHYLUM III.

Vermes (Worms) ....

PAGE

Definition and Scope of Paleon tology ..... 1

PHYLUM I.

Protozoa . . . . . . . . .17

PHYLUM IL

Coelenterata (Zoopliytes) . . . . • • .46

. 135

PHYLUM IV.

ECHINODERMATA . . . . • • • .143

PHYLUM V.

MOLLUSCOIDEA . . . • • • • .314

PHYLUM YL
Mollusca ......... 421

PHYLUM VIL

Arthropoda (Articiüates) ....... 690

INDEX 823

xi

INTßODUCTION

DEFINITION AND SCOPE OF PALEONTOLOGY

Paleontology (Aoyos row TraXatCov ovTOiv) is the Science which treats of
the life which has existed on the globe during former geological periods. It
deals with all questions concerning the structure, Classification, relationships,
descent, conditions of existence, and distribution in time and space of the
ancient inhabitants of the earth, as well as with those theories of organic and
cosmogonic evolution which result from such inquiries.

Under the term of fossils are understood all remains or traces of plants
and animals which have lived before the beginning of the present geological
period, and have become preserved in the rocks. The criterion which
determines the fossil character of organic remains is the geological age of the
formation in which they occur, whereas their mode and State of preservation,
or the fact of their belonging to extinct or to still living species, are merely
incidental considerations. Although fossils have, as a rule, undergone more
or less radical changes during the process of fossilisation, and are usually
transformed into mineral substances, nevertheless, under exceptionally
favourable conditions (as in frozen ground, amber, resin, peat, etc.), plants
and animals may be preserved through geological periods in a practically
unaltered state. Carcasses of mammoths and rhinoceroses entombed in the
frozen mud-cliffs of Siberia, and inclusions of insects, spiders and plants in
amber are none the less genuine fossils, in spite of their having sustained no
trace whatever of mineral infiltration.

A considerable number of plants and animals occurring as fossils in Tertiary
and Pleistocene formations belong to still living species ; while, on the other
hand, the remains of forms which have become extinct during historical times
(Ehijtina, Alca, Didus, Pezophaps, etc.) can no more be classed as fossils in the
true sense of the word than all such recent organisms as may chance to
become buried in deposits now forming under the present prevailing orographic
and climatal conditions.

The changes which organic bodies undergo during the process of fossilisa-
tion are partly chemical and partly mechanical in their nature.^ According
as certain portions of the original substance are removed, or are replaced atom

^ White, Charles J., Conditions of preservation of invertebrate fossils. Bull. U.S. Geol. and
Geog. Survey Territ., 1880, vol. v. , p. 133. Trahucco, G., La Petrificazione. Pavia, 1887.
VOL I. B

2 ELEMENTS OF PALEONTOLOGY

for atom by foreign matter, the result may be either carbonisation, decom-
position, total dissipation, or petrifaction.

Carbonisation is a deoxidising process taking place under water or with
limited access of air, and especially common among plants. Fossil wood and
other vegetable matter abound in peat, lignite and bituminous coal, the
leaves being transformed into a thin flake of carbon, on which often the finest
venation is still discernible. In some cases chitinous animal structures also
become carbonised, as in insects, crustaceans and graptolites.

Becomposition as a rule effectually destroys all organic carbon and nitrogen
Compounds. With few exceptions, therefore, animals without hard parts,
such as Worms, infusorians, naked mollusca, most hydrozoa, many anthozoa,
and the embryos of vertebrates, leave no traces behind in the rocks. Hörn,
hair, chitin and similar structures are likewise totally destroyed during the
fossilisation process, while only under especially favourable conditions, as
in ice or in frozen soil, muscular and epidermal tissues remain unchanged ;
or eise, through the taking up of lime phosphate in argillaceous and calcareous
deposits, undergo a sort of petrifaction, in which the finer structure is but
little altered. ^ Even the conservable hard parts of animal bodies are deprived
of their organic Compounds ; bones give up their fats and oils, and the shells
of moUusks, echinoderms and crustaceans lose their pigments and soft sub-
stratum. The hard portions, which first become more or less porous through
loss of their organic constituents, next suffer the gradual disintegration of
their inorganic Compounds, and finally undergo dissolution, reabsorption,
or petrifaction.

Petrifaction. — In this process foreign substances soluble in water (chiefly
calcium carbonate and silica, more rarely pyrites, iron oxyhydrate and other
salts) impregnate and completely fill all original cavities as well as those
formed subsequently by decay. Chemical metamorphism takes place
occasionally, when, owing to the decomposition of certain inorganic con-
stituents, the original molecules become replaced by those of other substances.
For instance, we find quartz pseudomorphs after calcareous tests and skeletal
parts, and conversely, calcite pseudomorphs after silica, as in certain sponges.

Wherever the space originally occupied by soft parts, as, for example, the
interior of a shell or other hoUow body, becomes filled up with infiltrating
ooze, while the shell itself or the enclosing wall decays, there is produced a
cast of the interior, which in most cases (especially where the shell is thin, as in
ammonites, brachiopods, certain moUusks and crustaceans) preserves an exact
copy of the original form, and is susceptible of as accurate determination as
the real object. Not infrequently fossil organisms leave molds or imprints of
their shells or skeletons — very rarely of their whole bodies — in the rocks.
Sometimes, indeed, their presence is indicated merely by tracks or footprinfs.

Fossils are often distorted by mechanical agencies, such as faulting, folding,
crushing, and other deformations of the country rock. Such cases require
especial attention, and due caution must be observed in their determination.

Paleontology and Biology. — Although the fossil remains of ancient
life-forms yield but a fragmentary record of themselves, are almost never
perfectly preserved, and are usually more or less altered in appearance, yet
on the whole, they readily fit into place in the great framework of zoological

^ Reis, Otto, Über petrificirte Muskulatur. Arch. Mikros. Anat., vols. xli. xliv. lii. , — Dean,
B., Preservation of muscle-fibres in sharks, Amer. Geol., 1902, vol. xxx.

INTRODUCTION 3

and botanical classifications. Notwithstanding all their difFerences, their
general structure is similar to that of recent organisms, and their Identification
requires the most careful comparison with nearly related plants and animals.
The methods of paleontological research do not differ from those employed
by the zoologist and botanist, excepting, of course, that the paleontologist is
restricted to those pärts which are alone capable of preservation, and must
reconstruct the missing soft parts ideally from analogy with recent forms. It
is, nevertheless, incumbent on the paleontologist to obtain all possible Informa-
tion from the material such as it is, aided by every means he can devise ; and
hence his investigations do not cease with an examination of the external,
macroscopic characters, but must be extended to the finer microscopic and
histological as well. In numerous instances paleontology has anticipated
zoology and botany by important histological discoveries ; in the brauch of
vertebrate comparative anatomy, for example, through the exhaustive study
of conservable hard parts, such as the teeth, skeleton, dermal covering, etc.,
this science has been elevated to its present high Standard chiefly by paleon-
tologists (Cuvier, Owen, Huxley, H. von Meyer, Rütimeyer, Marsh, Cope,
Osborn and others). The principle of correlation of parts, first applied with
such eminent success by Cuvier, according to which all parts of an organism
stand in certain fixed relationships to one another, so that one organ cannot
Vary without a corresponding Variation taking place in the others, is now
worked out not only for the whole group of vertebrates, but for invertebrates
as well ; and its elaboration is such that frequently a single bone, tooth,
plate, carapace, shell-fragment and the like, is sufficient for us to form a
tolerably accurate concept of the entire creature. It is therefore clear that
in so far as paleontology has to deal with the study and Classification -of fossil
organisms, it is no other than a part of zoology, comparative anatomy and
botany, and hence may be very properly divided into Paleozoology and Faleo-
lotany. Paleontology has vastly increased the subject - matter of the two
biological sciences, has filled up innumerable gaps in the system, and has
infinitely enriched our knowledge of the variety and complexity of plant and
animal Organisation. In almost every class of both kingdoms where preserva-
tion is possible, the number of fossil forms cohsiderably exceeds the recent.
A natural Classification of the Foraminifera, sponges, corals, echinoderms,
moUusks, vertebrates, and of the vascular cryptogams, cycads and conifers,
would be utterly inconceivable without taking paleontological evidence into
account, since in certain classes (brachiopods, cephalopods, reptiles, mammals)
the number of extinct fossil forms may be ten, a hundred, or even a thousand-
fold greater than the living, and this proportion is steadily increasing in
favour of paleontology, as fresh discoveries are made in various parts of the
World.

Paleontology and Geology. — Although as a biological science paleon-
tology does not differ essentially from botany and zoology, yet its connection
with geology is none the less intimate, and consequently it has been cultivated
quite as assiduously by geologists as by biologists. The material is brought
to light almost wholly by geologists or by geological collectors, who obtain it
from the stratified rocks of the earth's crust — that is to say, rocks which have
been formed by the subaqueous deposition of sediment, or have been built up
from detritus on dry land by aerial agency. The distribution of fossils
throughout stratified rocks is by no means promiscuous, neither do all rocks

4 ELEMENTS OF PALEONTOLOGY

contain the same species ; but on the contrary, each separate stratigraphical-
complex, and frequently even single beds and layers, are characterised by
certain particular assemblages of fossils. The older the rock, the-more strikingly
different from recent organisms are its fossil remains ; the younger the forma-
tion, the greater is their resemblance. Now, since experience shows that
contemporaneous deposits which have been laid down under similar conditions
(as, for example, in salt or in fresh water) contain identical or at least very
similar fossils, the latter furnish us with an infallible guide, taken together
with the local stratigraphic succession, for determining the relative age of a
given formation. Furthermore, a knowledge of the fossils occurring in homo-
taxial deposits enables us to reconstruct the various paleofaunas and paleo-
floras which have existed on our planet at different periods in its history.
Having determined the chronological succession of the clastic rocks by means
of their superimposition and their characteristic or index-fossils, they may be
divided up into still smaller series, each one of which is characterised by a
particular assemblage of organic remains. In the main, then, paleontology is
the ultimate foundation of historical geology.

Excluding the oldest metamorphic rocks (gneiss, mica schists, phyllites,
etc.) which are destitute of fossils, and concerning whose origin there is still
great difFerence of opinion, the total thickness of the sedimentary rocks
amounts to 20,000 — 30,000 metres. The building up of this prodigious
pile of rock must have extended over an inconceivably long time, whose dura-
tion cannot even approximately be estimated, since we are without data as
to the rate of deposition in former periods, and since the beginning, culmina-
tion and end of geological epochs cannot be correlated with astronomical
events.

Since, however, the earth has been inhabited in former times by very
different creatures from those now living ; since successive paleofaunas and
paleofloras follow one another everywhere in the same order ; and since,
furthermore, in certain formations the greater part or even the total number
of species appear and disappear in a body, so that one fauna or flora is
replaced almost in its entirety by the next following ; it is obvious that the
sedimentary rocks may be subdivided into a number of longer and shorter
time measures, which may be designated by particular names. The beginning
and end of such periods (group, System or formation, series or section, stage,
Zone or bed) is usually indicated by local interruptions in the deposition,
occasioned by variations in sea-level, volcanic eruptions, or by other causes ;
and such disturbances are usually accompanied by changes in the flora and
fauna. The now generally accepted subdivision of the secondary rocks is
represented in the table on page 5, in which it should be noted that only the
first three columns are of universal significance, while the last two apply only
to European countries.

The rocks of the Archaean Group amount to 40,000—60,000 metres in
thickness. They belong to the oldest and longest period in the history of
our planet, and are remarkable for their schistose and crystalline structure, as
well as for the total absence of fossils. In order of stratigraphy, gneiss com-
prises for the most part the oldest ; mica, chlorite, and talc-schists the middle ;
and phyllites (primitive schists) the youngest division of this group. The
so-called fossil organism, Eozoon, occurring in gneiss, has been proved to be of
inorganic nature.

■

INTRODUCTION 5

Eras

Periods

1

i Epochs (Etages)

P4

1

Quarternary
System

Alluvium

Recent Deposits

Diluvium
(Pleistocene)

Postglacial Series
Glacial
Preglacial ,,

Tertiary System

1

o

Pliocene

Upper or Siciliaii (öicilien)
Middle or Astiaii (Astieii)
Lower or Plaisaneiaii (Messinien)

Miocene

Pontian iSeries (Pontien)
Sarniatian ,, (Sannatien)
Tortonian ,, (Tortonien)
Helvetian „ (Helvetien)
Burdigalian Series (Burdigalien)
Aquitanian ,, (Aquitanien)

Oligocene

Upper or Rupelian (Stanipien)
Lower or Lattorfian (Tongrien)

Eocene

Bartonian Series (Bartonien)
Parisian ,, (Lutetien)
Ypresian „ (Ypresien)
Landeniau ,, (Landenien)

Mesozoic Group

Cretaceous
System

Upper Cretaceous

Danian Series (Danien)
Senonian ,, (Senonien)
Turonian ,, (Turonien)
Cenomanian Series (Cenomanien)

Lower Cretaceous

Gault Series (Albien)
Ai)tian and Urgonian Series (Aptien, Urgonien)
Barremian Series (Barremien)
Xeocomian and Wealden Series (Neocomien)

Jurassic System

Upper Jurassic
(Malm)

Tithonian and Portland Series (Portlandien)
Kinimeridgian ,, (Kimmeridgien)
Corallian ,, (Sequanien)
Oxfordian „ (Oxfordien)
Kellaway ,, (Callovien)

Middle Jurassic
(Dogger)

Bath or Great Oolite Series (Bathonien)
Bajeux or Inferior Oolite Series (Bajocien)

Lower Jurassic
(Lias)

Toarciaii Sfiies (Toarcien)
Charmouthiau Series (Charmouthien)
Sinemurian ,, (Sinemurien)
Hettangian ,, (Hettangien)
Rhaetic Stage (Rhaetien)
Noric „ (Norien)
Carinthian ,, (Carnien)

Triassic System

Upper Triassic
(Keuper)

Middle Triassic
(Muschelkalk)

Ladinian Series (Ladinlen)
Virglorian ,, (Virglorien)

Lower Triassic
(Bunter Sandstein)

Werfenian series <'äyEj°'

^^Bu

Permian System
(Dyas)

Zechstein
Rothliegendes

Thuringian Series (Thuringien)
Saxonian or Penjabian (Saxonien)
Artinsk or Autunian (Autunien)

Carboniferous
System

Coal Measures

Uralian or Steplianian (Ouralien)
Muscovian or Westphalian (Moscovien)

Lower Carboniferous
(Culm)

Dinantian Series or Culni (Dinantien)

Devonian
System

Upper Devonian

Famennian Series (Famennien)
FrasniaTi ,, (Frasnien)

Middle Devonian

Givetian ,, (Givetien)
Bifelian Series (Eifelien)

Lower Devonian

Coblenzian Series (Coblentzien)
Gedinnian ,, (Gedimiien)

Silurian System

Silurian

Ludlow Series ^

Wen lock „ WGothlandien)

Llandovery Series j

Ordovician
(Lower Silurian)

Bala or Caradoc Series )

Llandeilo „ WOrdovicien)

Arenig „ )

Cambrian
System

Upper Cambrian

is'Är'f^ (rot»"-™)

Middle Cambrian

Menevian Series (Acadien)

Lower Cambrian

Harlech Series (Georgien)

Arch-
aean
Group

Primitive Schist

System
Gneiss System

Phyllite (Primitive Schists,
Mica and Chlorite Schists,
etc.)
1 Gneiss

Precambrian Series (Algonkien)

6 ELEMENTS OF PALEONTOLOGY

The Faleozoic or Primarij Group comprises the Cambrian, Ordovician,
Silurian, Devonian, Carboniferous and Permian Systems, each of which is
made up of a great number of series, stages and zones. In the Cambrian
crustaceans, trilobites, brachiopods and worms predominate, associated with a
few echinoderms, coelenterates, sponges and poorly preserved algae. In the
Silurian system most classes of the animal kingdom are represented with the
exception of amphibians, reptiles, birds and mammals, while the flora still
consists of algae. Marine invertebrates are very abundant, especially crus-
taceans, moUusks, echinoderms and coelenterates, while only a few frag-
mentary fish-remains indicate the presence of vertebrates. All the species
and nearly all the genera have since become extinct, and belong for the most
part to extinct families and Orders. During the Devonian, Carboniferous and
Permian Systems, the same classes of animals continue as a body, but are
represented by frequently different families and genera. Fishes develop a great
variety of forms in the Devonian, amphibians (Stegocephalia) make their
appearance in the Carboniferous, and reptiles in the Permian. The flora
consists chiefly of vascular cryptogams, together with a few conifers and
cycads.

The Mesozoic Group comprises three Systems — the Triassic, Jurassic and
Cretaceous. Many of the widely distributed Paleozoic types (Tetracoralla,
graptolites, crinoids, cystids, blastoids, brachiopods, trilobites) have either wholly
or in greater part disappeared, while others (cephalopods, lamellibranchs, sea-
urchins) are replaced by very different genera and families. Vertebrates are
remarkable for the gigantic size attained by amphibians (Labyrinthodonta) and
many reptiles, as well as for the wonderful variety of the latter. Birds appear
for the first time in the Upper Jurassic (Archaeopteryx), and mammals
towards the close of the Triassic, being represented by diminutive, probably
marsupial types. During the Triassic and Jurassic periods, vascular crypto-
gams, conifers and cycads remain the dominant plant-forms, dicotyledons not
occurring until the middle Cretaceous.

The Cenozoic Group comprises the Tertiary and post-Tertiary or Quaternary
Systems. Among the invertebrates, ammonites, belemnites, Rudistae and
most of the Crinoidea have now passed away. Amphibians and reptiles have
greatly declined, and, like the invertebrates, are represented by still living
Orders. On the other band, birds, and particularly mammals, attain a
wide distribution ; the latter class branches out in such manifold variety, and
experiences such rapid development during Cenozoic time, that it alone
furnishes us with the principal index-fossils of this era. From now on the
flora consists chiefly of dicotyledonous plants.

Paleontology and Physical Geography. — Not only do fossils con-
stitute the very foundation of historical geology, but they furnish us in
addition with valuable inform'ation respecting the origin of the rocks in
which they occur, the former distribution of land and water, climatal
conditions, and the facts of geographical distribution in former periods. By
means of analogy with recent species we are able in most cases readily to
determine whether fossil forms pertain to land, fresh, brackish or salt water
species, whence it is apparent under what conditions the strata were deposited.
The distribution of marine and fresh-water formations helps us to certain
conclusions respecting the extent of former seas and land areas. Deep-sea,
shallow water, and littoral deposits are readily distinguishable by means of

INTRODUCTION 7

their fossil organisms. By fossils, also, even the climatal conditions of
former periods are indicated with great fidelity. The luxurious and uniform
development of cryptogams over the face of the globe during Carboniferous
time presupposes a warm, moist climate, little varying with latitude ; tropical
dicotyledons occurring in the Cretaceous and Tertiary deposits of Greenland,or
coral-reefs extending into high latitudes during the Paleozoic era, prove with
equal certainty the prevalence of a milder climate and higher oceanic temperature
in earlier times ; while again, the remains of reindeer, the lemming, musk-ox,
polar fox, and other arctic animals in the diluvium of Central Europe testify
to a period of glaciation with reduced mean annual temperature.

The geographical distribution of fossil organisms proves that the regions
and provinces occupied by recent plants and animals are to a certain extent
identical with those existing in the Tertiary, and that life has been subject to
the same distributional laws in the past as in the present. Nearly all recent
forms are the obvious descendants of extinct creatures which formerly
occupied the same region. For example, the fossil mammals, birds and
reptiles of Diluvial time in Europe, Asia, Australia, North and South America,
are scarcely distinguishable from forms now inhabiting the same continents.
The ancestral homes of marsupials and edentates were perpetuated in
Australia and South America until as recently as the Diluvial epoch, and
during the later Tertiary, Europe, Asia and America formed but a single
zoological province, inhabited by the ancestors of forms now living in the
northern hemisphere. An understanding of the physical conditions which
have governed the perpetuation of recent plants and animals in their respective
provinces (succession of similar types) would be utterly impossible without a
knowledge of their distribution in former times. In like manner, our know-
ledge of the distribution of land and water, of prevailing climatal conditions,
oceanic currents, etc., of earlier periods depends chiefly upon evidence derived
from fossils.

Paleontology and Embryology. — To trace the development of living
plants and animals through all stages from the one-celled egg onward to
final dissolution, is the task of Embryology and Ontogeny. At the present
moment, botanists and zoologists are devoting their most scrutinising attention
to embryological investigations, which latter accordingly exert a powerful
influence on the progress of biology, and particularly on the Classification.
The fact that every individual, species and genus of a whole group of plants
and animals passes through nearly the same course of development, at least
in the primary stages, and that all embryos belonging to a given order or
class resemble one another so closely, up to a certain stage, that they cannot
be told apart, has revealed unexpected affinities among forms differing very
considerably in the adult stage. Cirripedes, for example, which were formerly
mistaken for shell-bearing mollusks, develop from the same Nauplius-larvae
as the Copepoda, Branchiopoda and Ostracoda, although the mature individuals
belonging to these Orders of crustaceans possess but little common resemblance.
Likewise, the whole group of vertebrate embryos can hardly be distinguished
from one another in the earliest stages, and only very gradually assume the
characteristic features pertaining to class and order.

The results of embryological inquiry have a most important bearing on
paleontology. Numerous fossil forms are known, which, in comparison with
recent related organisms, exhibit embryonic, or at least larval or adolescent

8 ELEMENTS OF PALEONTOLOGY

characteristics. Examples of such primitive or emhryonic fypes are especi-
ally common in vertebrates, for the reason that here the skeleton becomes
ossified very early in life, and hence the immature stages of the recent can be
directly compared with adult fossil forms. Now, Observation has shown that
in most of the older fossil fishes and reptiles, the vertebral column never
passed beyond an embryonic stage, but remained in a cartilaginous or
incompletely ossified condition through life. The Paleozoic amphibians
(Stegocephalia) probably breathed by means of both gills and lungs through-
out life, whereas most recent amphibians lose their gills comparatively early
(Caducibranchia), and breathe wholly by lungs. Many fossil reptiles and
mammals retain certain skeletal peculiarities permanently, while allied recent
forms exhibit them only in embryonic stages. The skull in most of the older
fossil reptiles and mammals closely corresponds in form and structure with
that in embryos of recent related types. In the oldest fossil artiodactyls
the palm-bones are all completely separated, while in recent ruminants this
division continues only during the embryonic stage, being followed by a
fusion of the two median metapodals, together with a reduction of the laterals.
Among invertebrates, also, fossil embryonic types are by no means uncommon.
The Paleozoic Belinuridae find their counterpart in the larvae of the common
Limulus ; many fossil sea-urchins are characterised by linear ambulacra, while
recent related forms, although developing petaloid radii in the adult stage,
pass through the linear phase during adolescence. Many fossil crinoids re-
semble the young of the living genus Antedon ; and, according to Jackson,
recent echinoids, oysters and pectens exhibit in their nepionic stages certain
characters peculiar to the adults of Paleozoic genera.

The so-called fossil generalised or comprehensive types, which unite in one and
the same form characters which, in geologically later, or recent descendants,
have become distributed among different genera and families, are in reality
merely primitive or immature types which have stopped short of the higher
differentiation attained by their descendants. Generalised types always
precede more highly specialised ; and properties that were originally distri-
butive among older forms are never reunited in geologically younger species
or genera. Trilobites, amphibians and reptiles of the Paleozoic and Mesozoic
eras, and early Tertiary mammals belong almost exclusively to the category
of generalised types.

In certain groups of vertebrates, and especially of mammals (Ungulata,
Carnivora), the chronological succession of genera is so closely paralleled by
the successive stages of development in the life-history of their descendants,
that to a certain extent the ontogeny of the individual is a representment of
a long chronological series of fossil forms. This truth furnishes a strong
foundation for the hiogenetic law, enunciated in various terms by GeofFroy St.
Hilaire, Serres, Meckel, Fritz Müller and others, and recently more precisely
formulated by Haeckel, as follows : The developmental history or ontogeny
of an individual is merely a short and simplified repetition or recapitulation of
the slow (perhaps extending over thousands of years) process of evolution of
the species and of the whole brauch.

The biogenetic law has since been found to hold true not only for verte-
brates, but also for invertebrates, including even wholly extinct types. In
ammonites, for instance, the primary or innermost whorls always difFer frora
the outer in their greater simplicity of suture, and in their lesser ornamenta-

INTEODUCTION 9

tioii. Very ofteii a correspondence is observable with geologically older forms ;
and it is a well-known fact that all ammonites pass through early stages whicli
resemble, at least so far as chambering of the shell is concerned, Paleozoic
goniatites. A comparison of the inner whorls of an ammonite with its corre-
sponding goniatitic form, or with older ammonites, seldom fails to reveal
ties of kinship not otherwise discernible. Beecher has shown that nearly
every stage in the development of arm-supports in recent brachiopods corre-
sponds to conditions of the adult in some fossil genus ; and further, that the
chronological succession of the latter is to a certain degree identical with the
successive ontogenetic stages of recent forms.

The relation of rudimentary or degradational organs occurring in recent forms
to those of the fossil ancestors of the latter is of extreme significance. By
rudimentary organs are meant certain structures (as, for example, limbs,
parts of limbs, organs of sense, respiration, digestion, reproduction, etc.),
which are still indicated by atrophied remains, but whose physiological
functions, and hence their Utility to the organism, have wholly disappeared.
Rudimentary organs are, as a rule, either normally developed in an embryonic
stage, or at least more strongly than in the adult individual, owing to a
process of degeneration, or retrogressive development. The fossil progenitors
of forms possessing vestigial structures are almost always characterised by
a füll development of the respective parts. The lateral metacarpals and
metatarsals in the horse and most ruminants, for example, are indicated only
by rudimentary side-splints ; but in an embryonic stage they are much more
strongly developed, and in related fossil forms they occur as normal bones,
carrying toes like the other metapodals, and serving for locomotion and
Support. The wrist and metacarpal bones in birds have also sufFered degenera-
tion, as is evident from a comparison with embryos and wdth older forms
(Archaeopteryx), which exhibit a much higher development. In like manner,
the teeth of birds have also become degenerated. In only a few forms
(parrots, ostriches) are faint dental ridges discernible during embryonic stages ;
but in all known Mesozoic birds the teeth are well developed and remain
functional throughout life. Similarly, teeth are developed during embryonic
stages in the baleen whale, but subsequently become atrophied ; while in the
older fossil Cetacea teeth are always present. Other instances of this
nature are to be met with in great profusion, both among vertebrates and
invertebrates.

The biogenetic law is, however, not infrequently obscured, for the reason
that two closely related forms may not develop in exactly the same manner ;
embryos of the one type may be afFected by peculiar accelerating impulses
which are not shared by those of the other, and in consequence the first may
pass through certain stages very rapidly, or may even omit them altogether.
In this way the historical or palingenetic record contained in the development
of every individual may be to a large extent veiled, suppressed or rendered
unintelligible ; and this phenomenon of inexact parallelism (coenogenesis) is
especially common in highly differentiated types, where the embryo passes
through a multitude of phases.

Paleontology and Phylogeny. — While conceding that by means of
embryological investigations zoologists and botanists are able to trace the
gradual development and differentiation of an organism through all its various
stages, and thereupon to construct a tree of descent (phylogeny) founded upon

10 ELEMENTS OF PALEONTOLOGY

the successive phases of grovvth, nevertheless such hypothetical genealogies
can only be relied upon as truthful when they are substantiated by paleonto-
logical facts. And only in cases where the difFerent ontogenetic stages are
represented by corresponding fossil primitive or generalised types, which
appear in the same chronological order, and clothe the supposititious ancestral
tree with real forms, can the truthfulness of the latter be said to have been
established. This requirement paleontology is from the nature of things
unable to satisfy except in a few instances ; but a multitude of other facts
testifies to the blood-kinship between morphologically similar fossil and recent
organisms, and points to the direct descent of the younger from the older
forms.

Geology proves conclusively that of the numerous floras and faunas which
lie buried in the rocks, those which are most nearly of the same geological
age bear the greatest resemblance to each other. It often happens that species
and genera occurring in a given formation reappear in the next following with
scarcely any perceptible changes, so that the doctrine of the gradual trans-
formation and transmutation of older forms is irresistibly forced upon one,
while the faunas and floras of later periods assert themselves as the obvious
descendants of the more ancient. Other weighty evidence for the progressive
evolution of organisms is afforded by fossil transitional series, of which a
considerable number are known, notwithstanding the imperfection of the
paleontological record. By transitional series are meant a greater or less
number of similar forms occurring through several successive horizons, and
constituting a practically unbroken morphic chain. Often the differences
between individuals belonging to diff'erent periods are so slight that we can
hardly assign to them the value of a variety. But let a number of such
mutations occur in succession, the end-members of the series become finally
so divergent as to constitute distinct species and genera. The most striking
and most numerous examples of transitional series naturally occur in types
peculiarly well fitted for preservation, such as mollusks, brachiopods, sea-
urchins, corals and vertebrates. Particularly remarkable among mollusks
are the closely linked transitional series in ammonites. Among vertebrates
transmutation proceeded far more rapidly than among invertebrates, and
accordingly, the successive members of a series are usually so divergent as to
require their assignment to separate genera.

With increasing abundance of paleontological material, the more numerous
and more complete are the series of intermediate forms which are brought to
light. But the more extended our knowledge of transitional series the greater
is the difficulty we encounter in defining our conception of species. While the
older disciples of the Linnean and Cuvierian schools contended that each
separate species was created with a certain definite sum of fixed characters,
and remained incapable of any extensive modifications ; on the other band,
those holding to the Darwinian theory of evolution look upon varieties,
species, subgenera, genera, families, Orders, classes and phyla merely as
arbitrary yet useful and convenient distinctions, corresponding to the state of
our information at the present time ; it being assumed that by means of
gradual transmutation during the course of ages all organisms have become
evolved from a single primitive cell, or from a few primitive types.

According to the Linne-Cuvier doctrine, a species is composed of individuals
which are directly descended from one another, or from common ancestors,

INTRODUCTION 13

and which resemble their progenitors as much as they resemble each oti^es
Membeis of one and the same species interbreed, but individuals belongin^
to different species do not cross, or when they do, produce infertile or
iraperfectly fertile offspring.

According to the theory of descent no sharp specific distinctions can be
drawn, but all individuals are assigned to the same species which share a
number of essential features in common, and which are not connected with
neighbouring groups by means of intermediate types. It is piain that this
definition is open to considerable laxity of interpretation, and inasmuch as
the direct descent of individuals belonging to a given species cannot always (in
paleontology never) be determined on experimental grounds, systematists
are rarely agreed in regard to the precise limitations of species, genera and
families.

The doctrine of the invariability of species received powerful support from
the cataclysmic theory of Cuvier, which maintained that each period in the
earth's history is marked by distinctively characteristic faunas and floras ; that
no species is common to two successive periods ; that tremendous convulsions
of nature (catadysms) occurred at the close of each cycle, and annihilated the
whole organic world ; and that by means of special creative acts, the renovated
earth became time and again populated with new animals and plants which bore
absolutely no connection with either previous or subsequently introduced types.

Cuvier's cataclysmic theory raay be regarded at the present day as com-
pletely overthrown, inasmuch as the modern school of geology, following the
leadership of Sir Charles Lyell, has demonstrated conclusively that the earth
has proceeded from one stage to another during the course of its development
only with the utmost slowness ; that the same forces and laws which regulato
the World of to-day have operated likewise in primeval times ; and that
geological periods are by no means abruptly set off from one another, but are
linked together by innumerable transitional stages.

The theory of the descendant origin of organic forms, which was advanced
as early as 1802 by J. B. Lamarck and Geoffroy St. Hilaire, and was supported
by Goethe, Oken and Meckel in Germany, kept winning continually more
adherents, yet it was not until the latter half of the nineteenth Century that
its universal significance was insisted on by Charles Darwin and his school.

Paleontology, as already remarked, contributes a great deal of extremely
weighty evidence in favour of the theory of descent ; the series of intermediate
forms, often traceable through several successive formations ; the presence of
primitive and generalised types ; the parallelism between ontogeny and the
chronological succession of related fossil forms ; the similarity between floras
and faunas of approximately the same age ; the correspondence in the
geographica! distribution of recent organisms with that of their progenitors ;
and a host of other facts are explicable only by means of the theory of descent.

The causes of Variation and transformation were attributed by Lamarck
chiefly to the use and disuse of organs ; secondly, to the effect of changes in
external conditions ; and lastly, to a supposed inherent tendency toward
Variation and perfection existing in each individual. According to Lamarck,
new characters brought about by these influences are transmitted to descend-
ants through inheritance, and become permanently established in the race.
Geoffroy St. Hilaire maintained the same principles on the whole, but ascribed
the chief causes of Variation of species to the infiuence of environment.

12 ELEMENTS OF PALEONTOLOGY

The Darwinian theory of natural selectioii is based upon the property
common to all organisms of acquiring ancestral characteristics through heredity,
and of transmitting them in turn to their progeny ; and also on the adapta-
bility of organisms to particular external conditions, by means of which
variations are brought about. Since in the struggle for existence only those
individuals which are the best adapted — that is to say, those possessing the
most advantageous modifications — survive, nature is continually exercising,
according to Darwin, a most rigorous selection which operates toward the
increase and perfection of useful variations. Through the constant accumula-
tion of originally slight yet serviceable modifications, and through the perpetual
transmission of the same from one generation to another, there are produced
first of all new varieties,then species, and eventually genera, families and Orders.
The zoological and botanical classifications are, according to Darwin, merely an
expression of genealogical facts, exhibiting the remoter and closer ties of
consanguinity which exist among difFerent organic forms.

Darwin's explanation of the origin of species by the addition of the
agency of natural selection to the Lamarckian factors of Variation and
inheritance found in Wallace, Huxley, Haeckel and others, zealous and
ingenious supporters, although on other sides it encountered vehement
Opposition. Moritz Wagner regarded free intercrossing as an insurmountable
obstacle to the establishment of new modifications, and contended that the
isolation of a few individuals, a condition which w^ould occur most frequently
during migrations, was a necessary postulate in accounting for the origin of
each new variety or species. As will be stated presently, the principle of
isolation, slightly modified, has been applied by other writers. Bronn, Nägeli
and A. Braun raised the objection to Darwin's theory of natural selection
that many organs are entirely useless to the individual, and therefore natural
selection, which depends upon the principle of utility, could neither have
produced such organs nor could have modified them in any way. Nägeli
assumed that, in addition to natural selection, a certain resident tendency
toward perfection, inherent in every individual, takes part in conditioning
the growth of morphological characters. Every Variation brought about
by external or internal agencies is at once in the nature of a differentiation,
a Step forward in the division of labour, and consequently an advancement.

Weismann endeavoured in a similar manner to Supplement Darwin's theory
of selection by his hypothesis of the continuity of germ-plasm. According to
Weismann, germ-matter is of itself capable of producing all variations that
are useful to an organism. Only that which exists in the original plasm or in
the sexual elements as embryonic rudiments can be transmitted to off'spring
and become further acted upon and developed by natural selection, according
to Weismann's theory. The continuity, that is to say, the perpetual trans-
mission of a portion of the germ-plasm from parent to ofFspring, forms a
necessary postulate to the theory of descent.

Weismann originally attributed only a subordinate influence to the
action of physical environment as a cause of variations, and particularly
denied the inheritance of acquired characters. But in his later writings,
he is inclined to admit that somatic variations due to environmental influences
may be transmitted to the ofFspring, and endeavours to explain this with the
help of his germ-plasm hypothesis. Thus he approaches in a way the opinion
of his opponents, the so-called Neo-Lamarckian school (represented by Herbert

INTEODUCTION 13

Spencer, Cope, Hyatt, Osborn, Semper, Claus, Roux and others), which ranges
itself more and more on the side of Lamarckian ideas, and ascribes to the use
and disuse of Organs, and to external conditions, a very considerable influence
in effecting the transformation of organic forms. While, on the one band,
Semper, Locard and Clessin undertake to prove the direct action of environ-
ment on molhisks in a number of instances ; on the other band, Cope, Osborn,
Roux and others, emphasise the effect of use and disuse, and abundance or
scantiness of food-supply. Adequate nourishment and exercise increase the
development of a given organ, while physical conditions determine its form.
Since like causes produce like efFects in the animate as well as in the inanimate
World, it is obvious that similar organs must be developed in a variety of plant
and animal forms wherever they are subjected to similar external conditions,
and especially to the same physical agencies. A convenient explanation is
thus found for the phenomena of parallelism, or " convergence," which are
in nowise related to one another by inheritance. The analogous swimming-
organs of fishes, ichthyosaurians and whales, or the analogous limb-structure
in long-legged ruminants, the horse, elephant and Carnivora, are due to
adaptation to external conditions and to use ; the same explanation also
accounts for the like form of sternum in bats, birds and Pteivsauria, or for the
spindle-shaped body characteristic of most rapid-swimming fishes, reptiles and
aquatic mammals, or for the similar form of jaw possessed by marsupials and
varlous Orders of Placentalia. These are all instances of parallelism, in which
it often happens that two fundamentally different forms acquire the same
outward shape, or become provided with similar or analogous organs. Kineto-
genesis, or the process of a gradual transformation of parts, especially parts
belonging to the internal skeleton, skull and limbs, is very ingeniously
interpreted by Cope as having been accomplished in mammals through the
agency of mechanical conditions, use and food. The same author has also
traced the line of progressive modification in fossil genera as exemplified by
numerous series of intermediate forms.

In sharp contrast to all these opinions is the " mutation theory " of de
Vries. The latter attempts to show that new species of plants are formed
by what he calls mutations. It should be noted that this term is used in a
different sense from the same word as mentioned on p. 10, being equivalent to
saUation, used previously for the same thing. Mutations, in de Vries's sense,
are more or less strongly marked deviations from the normal type, appearing
rather suddenly ; and de Vries claims that only these are capable of being
bred true by pedigree-culture, and that they alone lead to the origin of new
species. What he actually did was to demonstrate that it is possible, by
pedigree-culture, to produce true breeding forms (species) out of mutations,
but he failed to see that the essential factor in this process is not the quality
of the material he worked with {i.e. the mutations), but that it is the pedigree-
culture, and that this corresponds to the well-known factors of selection and
Isolation.

The latter principle, originally introduced, as has already been stated, by
Moritz Wagner, has recently been put forward by other writers (Baur,
Ortmann, Gulick, etc.) as a factor which causes the differentiation of one
species into several co-existing species (" process of speciation," O. F. Cook).
While it is admitted that the Lamarckian factors of Variation and inheritance
and the Darwinian factor of natural selection, are real and actual, it is

14 ELEMENTS OF PALEONTOLOGY

evident that these are not sufficient for the understanding of the whole of the
evolutionary process. They are capable of explaining the transformation of
one existing form into one other form, but fail to account for the fact that
often tvvo or more different forms have originated from a single ancestral type.
Isolation, biological or ecological Separation, or habitudinal segregation, are
synonymous terms applied to a fourth factor, which is important for render-
ing the process of speciation more intelligible. These terms signify that
the descendants of one ancestral form living amid a definite set of ecological
(or environmental) conditions, begin to adapt themselves to different sets of
conditions, as a result of which they become ecologically separated or segregated.
Each group of descendants consequently becomes subject to different infiuences
of environment, and in responding to such develops along different lines, the
diverg'ence becoming finally so great as to be of specific value.

According to the view that has just been stated, it is necessary to
recognise that the whole process of evolution is a very complex one ; that it
is the ultimate outcome of a number of factors, each of which has its own
special efficacy, and may be sometimes antagonistic to the others ; and that of
the various factors engaged the following four are the most potent and most
essential : Variation, inheritance, natural selection and Separation. This view is
perhaps to be regarded as the most satisfactory explanation of the organic
World and its upbuilding that has yet been put forward. Nevertheless, though
it cannot be gainsaid that the four operative principles just mentioned are
actively at work, it is difhcult sometimes to trace' their causes. This is
particularly true of those factors known as Variation and inheritance. As to
the former of these factors, the rival hypotheses of the Lamarck-Darwinian
and of the Weismannian school are contradictory with reference to the cause
of inheritable Variation. With regard to the cause of inheritance, important
discoveries, such as the Mendelian law, have been made, but these are too far-
reaching to permit of a satisfactory account in limited space.

Life-Period and Extinction of Species. — Observation shows that
different organisms are by no means equally susceptible to Impulses received
from the outer world. Many fossil genera remain almost wholly unchanged
throughout a number of formations (Foraminifera, Cidaris, Nautilus, Lingula,
Terebratula, Insectivora), and hence may be designated as persistent or conservative
types, in contradistinction to variable types. The latter pass through rapid changes
at the beginning of their career, develop a great variety of forms, and send out
branches and off-shoots in all directions up to a certain point ; they may then die
out af ter a comparatively short period of ascendency (Nummulites, Graptolites,
Cystids, Blastoids, Tetracoralla, Perischoechinoida, Trilobitae, Rudistae, Ichthy o-
sauria, Pterosauria, Dinosauria, Amblypoda, Toxodontia, etc.), or in some cases
may even continue on to the present day with undiminished vitality (Spatangidae,
Clypeastridae, many land and fresh-water mollusks, crabs, lizards, snakes,
ruminants, apes). Not infrequently types that were originally variable pass
over gradually into persistent ; their power of adaptation dwindles, they grow
less plastic, become incapable of sending off new varieties, species or genera,
and as the less vigorous of their number become worsted one after another, they
finally stand out as isolated relics of antiquity {Isocrinus, Hatteria, 2'apirus,
Equus, etc.) in the midst of rehabilitated surroundings. A one-sided develop-
ment in a certain direction, excessive size, abnormal (hypertrophic) peculiarities,
or too high specialisation of organs, is as a rule injurious to the form and

INTRODUCTION 15

leads usually to its extermination. Many groups remarkable for their
extreme differentiation (Dinosauria, Pterosauria, Amblypoda, Toxodontia,
etc.) have become extinct probably for this reason, since, having advanced so
far in a single limited direction, adaptation in other directions was no longer
possible.

Persistent types seldom produce a large number of species during a single
geological period ; types that start up suddenly and proceed to vary rapidly
as a rule soon die out ; while groups that develop slowly and steadily usually
contain in their growth the promise of great longevity.

Some very ancient types have persisted to the present day in highly
saline lakes, or in salt paus, in acid, alkaline, very cold or otherwise unnatural
situations. These represent dominant types of past ages which, vigorous and
adaptable, when forced by internal specific pressure due to the enormous
increase in the numbers of individuals were able to invade and adapt them-
selves to physically and chemically unfavourable localities. The subsequent
development of other types, younger and more vigorous, has extirpated them
from all the more desirable situations, though these types have not proved
sufficiently adaptable or vigorous entirely to exterminate them.

The fauna of the ocean deeps and of biologically unfavourable situations
generally is, therefore, a curious composite of the more vigorous and adapt-
able types of animal life from the Cambrian to the present day, including
f orms which were dominant in all earlier epochs, as well as forms derived directly
from recent ancestors.

For the extinction of many plants (Sigillaria, Lepidodendron, Cordaites) and
animals (Blastoids, Tetracoralla, Trilobites, Ammonites, Rudistae, Ichthyosaurs,
etc.) of former periods no adequate explanation has as yet been found. Changes
in external conditions, especially such as regards the distribution of land and
water, climatal conditions, saltness of the water, volcanic eruptions, paucity of
food-supply, the encroachments of natural enemies, and diseases, may have
led to the extinction of certain forms, but such conjectures signally fail to
account for the disappearance of an entire species or particular groups of
organisms. Oftentimes extinction seems to have been caused merely by
superannuation. Long-lived forms belong for the most part to persistent
types whose ränge of species is limited. Their reproductive functions have
declined, and like an individual in its senescence, they evince the Symptoms of
decrepitude and old age. Darwin attributes the extinction of less well-adapted
organisms to the struggle for existence ; but since, according to the theory of
natural selection, new species arise only with extreme slowness by means of
the gradual accumulation of useful variations, and since in like manner their
less successful competitors are only very gradually crowded out, we should
expect to find in the rocks, supposing that the paleontological record were in
any degree perfect, all manner of extinct intermediate forms, and we should be
able, at least for those groups especially liable to conservation, to build up
complete ancestral trees. But as Observation shows, not only do most plants
and animals now living in a wild state adhere to their peculiar characteristics
with great tenacity, exhibiting barely appreciable changes even in the course
of hundreds or thousands of years, but, furthermore, fossil species remain
within the limits of a single geological period fairly constant. With the
beginning of a new epoch or period, however, which is usually indicated
in the section by lithologic changes, a greater or less number of species either

16 ELEMENTS OF PALEONTOLOGY

entirely disappears, or is replaced by closely related, but at the same time
more or less different forms. Obviously, therefore, there have been periods
when the process of transformation and the weeding out of organisms were
greatly accelerated, and following upon these reconstructive periods long
intervals of repose have ensued, during which intervals species have retained
their characteristic forms with but little Variation. The fact that evolution
has advanced by occasional bounds or leaps Stands, however, in nowise contra-
dictory to the theory of descent.

The whole animate Community at any point on the earth's surface rests
normally in a State of equilibrium, the balance being maintained by the com-
bined activity of all ranks and members of society. For the preservation of
this balance nature practises a most rigid domestic economy. Every plant
depends upon particular conditions of soil, food, temperature, moisture and
other requisites for its support ; and these conditions govern its distribution
and increase in the last degree. Every plant controls the destiny of all
animals subsisting upon it ; their numbers multiply with its increase, and
wane with its decrease. The fate of these creatures determines that of their
natural enemies, who stand in similar relationships to still remoter circles ;
and hence no form can overstride the bounds set for it by the general balance
without disturbing the whole general System of economy. Let the flora or fauna
of a given region become altered by the extinction of a number of species, or
by the introduction of new and more powerful competitors, the balance is
immediatöly upset. In the first instance vacant places must be filled up, and
in the second, room must be made for the newcomers at the expense of the
settled Community. Thus, wherever climatal, orographic, or other changes
are instrumental in bringing about the extermination of large numbers of
plants and animals during the lapse of a geological period, a State of inequi-
librium must necessarily result. But thereupon the struggle for existence
is waged with unwonted severity among the survivors, until finally a
readjustment is established, and a pause in the formation of new species ensues.

The whole course of evolution in the organic world during past geological
periods indicates not only definite progression in all branches of the animal
and vegetable kingdoms up to their present State, but also a more perfected
specialisation. Granting that the theory of descent is true, and that all
organisms have developed from a single primitive cell, or from a few primitive
ground-types, then every new growth and differentiation must stand for im-
provement and progress, leading gradually to the development of more or less
highly specialised organs, and to a division of labour in their physiological
functions ; the higher the degree in which this is manifested, and the more
conformably to apparent purpose and utility that each organ fulfils its
functions, the more perfect is the organism, as we conventionally term it.

Evolution in the organic world has not advanced in a simple, straightforward
direction, but its course has been exceedingly complicated and circuitous.
The biological Systems, accordingly, do not suggest to us the similitude of a
ladder with its numerous rounds, but rather that of an enormously ramifying
tree, whose topmost twigs represent the youngest, and, on the whole, the
most perfect forms of every brauch. The root, trunk, and a goodly portion
of the Upper limbs lie buried in the earth ; and only the ultimate green
shoots, the last and most highly difFerentiated members of long ancestral
lines, blossom forth in the world of to-day.

Phylum I. PROTOZOA.

Protozoa are unicellular organisms with bodies consisting of sarcode (proto-
plasm), usually very minute, frequently microscopic in size, and without
difFerentiated tissues or organs, They are water-inhabitants, take in nourish-
ing matter either at any point on the periphery of the body whatsoever, or
through a so-called moiith (cytostome), and reject the undigested portions either'
from any part of the body whatsoever, or from a definite point called the anal
aperture (cijiopijge). The contractile sarcode almost invariably contains one
or more nuclei, and exhibits considerable diversity of structure and difFerentia-
tion. Locomotion is accomplished by means of vibratile cilia, flagella, pseudo-
podia or irregulär processes of the periphery. Reproduction takes place by
means of budding or self-division, which latter process is often preceded by a
temporary conjugation of two individuals. Protozoa are divided into four
classes, only the first-named of which is known to occur in the fossil State :
Sarcodina, Flagellata, Infusoria and Gregarina.

Olassl. SARCODINA.

Protozoa with or without a test, having in fully developed individuals well
charaderised pseudopodia, either digitale, reticulate or radiale, with or without axial
filaments.

Subclass 1. RHIZOPODA.

Sarcodina either naked or with a definite test, the pseudopodia either lohose or
reticulate ; the adult form is amoeboid.

Order 1. AMOEBIDA.

The animals constituting this order do not occur as fossils. There are
found, however, in chalk and many marine limestones minute calcareous
bodies resembling coccoliths, such as are present in vast quantities in deep-sea
ooze of existing oceans.^

^ To the Amoebida were foniierly assigned by Huxley and Haeckel the so-called Bathybius, a
reticulated colloidal snbstance coniposed of anastomosing Strands, occuiring at great depths in the
Atlantic Ocean. Sir Wyville Thomson and Moebins regarded it as aprecipitate of calcium siilphate,
intermingled with decomposed organic matter. In deep-sea ooze, which consists chietly of linie
carbouate, as well as in Bathybius, great quantities of minute calcareous bodies of various shapes
are found, such as also occur as an essential constituent of chalk, marls and most marine lime-
stones belonging to older geological periods (cf. C. W. Gümbel, Neues Jahrbuch für Mineralogie,
1870, p. 7f>3). Ehrenberg termed these bodies morpholites, and regarded them as inorganic in
VOL. I 17 C

18 PROTOZOA— RHIZOPODA phylüm i

Order 2. FORAMINIFBRA d Orbigny.

Bhiso^oda usuaüy wUh a lest wJUch is typkaüy cakareous hut may be säkeous
or agghdinaled; consisting of one ar mare Chambers ; pseudopodia räiculaU.

The Foraminifera are for the most pari minnte animals varring in size
from a fraction of a mülimetre to several millimetres in length, but may
deTelop a t^t several inches across ; these, however, are rare exceptions. A
few species occur in fresh or brackisli water, but the great majoritj live in
the ocean. They are found at all depths, but are most frequent at moderate
depths in the ocean basins, where they form characteristic deposits — the
so-called "globigerina ooze." In the vicinity of tropical coral islands many
species occur in great abundance.

The animal itself is a single-celled form with one or many nuclei, as will
be later explained The test, in many cases at least^ is really an internal
structure, as the thin film of protoplasm which covere it in the perforate
forms, and probably in others, is capable of secreting the material of the test
to repair fractures and the like.

nature. Haxley (Journal Jücrosoop. SdaK«, 16&S, VUI. 2^o. Cj, oJmI Haöck^ ^JcZi^iäeiie Zeit-
schrift, 1870^ V. 3, p. 18) regarded thon st fiist as poitions of Baikgtiu*, and des%iiated
them coecolühs (Fig. 1). The simple^ dialdike varieties, eonTex <m fhe uppcr aide and eoneaxie <m
the lower, were tenned dücoUOu (Flg. 1, e) ; whfle tiiose ctNuposed (rf* tvo ckisdj applied di^ks
of diffex^oit sizes, resraiblii^ cnff-battons in pvofile, were refened to as ejfoihoUtks (Flg. 1, o, b).
Coocolitfas are only risible ander poveis of 800 to 1000 diametezs, and exhilxt, as a ruie, a namber
of »mes differing in thrär refnctire indioes, whidi are disposed aboot a än^, double <«- star-

sha^ed centnl grurale. Fre-
qaenüy laige nnmbos of eooeo-
liths beoome a^gregxted to-
gether in tiie fonn of fireel j
sospended ^icmles ar coom-
9phtres{¥ie.2). Besides cocco-
litlis, oäier minnte, rod-shaped,
cakareoos bodiesare siHnetinies
Fio.l,a,&.— Cbo(»Itas(qpadlMlifi«)ftomäieAyaatic met with, whidi are ebarac-

£we and in Profile (^DerHKel^^ ^^^ t«sriüed by a discwdal or craci-

and in i^ofile(mftera Schmidt). fem ealaigenicnt at «le aid.

FiolIT— Oieoospfeef«sframtlieAtlaiitieOeeaa(ailwHaeekeI). These are called rluMoUiks

FIO.S.— ffto&doUlftsfromacAdräticSeaCiftieraSehmidtX AUligiues (Flg. 3), and their nodular

magnifiedTOOdiametas. aggwgations HuAdmpkerrs.

WyTille ThomsoD, Gart«- and
Murray would identify ooooosidierBB as unJoeUnlar aJ^jae, or as spomigia of algse, whfle iTa^flr«»!
crestes for them a special gronp, ** Calcoeytae" and assjgns them provisionally to the Protophytes.
Acoocding to Hartlng, howevo-, the ac^icm of anunonia genetated by the deeomponlion of albnmin-
ons msttrar hdd in solutiaa in lime saifAuie or lime <^k«de|, canses the s^arstifm out ot minnte
calcareons didcs which bear a striking reaamhlanee to oooocdiths. Hcaiee it would appear that
the farmaüxm ol exxxs^vdj fine dirided paztides of lime in the sea should take place whesrerer
there are decxmiposing slbamiiHms or nitrageooos sabstaaces fwesent, and ibe calcium sol^iate
held in Solution in the water beomnes pvedpitated as cahänm csrbonateL

^ Utoature : dPOrbigmjf, A., Foraminißres fossiles du bassin tertiäre de Yienne. Fluis. 1846.
— EhrtiAerg, G. O., Mikrogeokgie, 18S4, and AUiaMlungoi der Preoss. Akad. Wisa., 1839. —
SAuUm, Max, lieber den Oiganianus der Pdythalamien. häpaäg, 1854. — Ctefpes/er, W. B.,
Introductran to the Study of the ForaminiCaa. Bay Sodety, 1862. — Rems», E. A., STumerons
Reports in Stzungsberichte da* Wveota Akadonie, from 1860 «mwazds. — Sdkwager, Comrad,
Sbggio di nna dasäficaäcme dei F<waminiferL Sollet. Condtato GeoL, 1876l — Bmdy, W. B.,
MfmograjA of Guboniferons and Pernüan F<»aniinifenL PSiaetmtagrsph. Soc, 1S76. — Bradp,
W. B., Beport on the Foruninifera^ Scümt. Besults C3ia]lengia- Exped.. Zodogy, XL, 1884. —
Skerbom^ C D., Index to the Gkmera and Spedes of the Fnsmini&n. &^th. Mise ColL.
1895, T<d. xxzriL — Egger, J. GL, Fonminiftrraii dar Seeweaer Kreädesehichteai. Sitiber. Bayer.
Akad. Wlss., 1909, No. W.—SAeOwiem^ E., Monographie der Fnsulinen. Fslaeontogr. 1908-1912,
Tols. It., Ux.

ORDER TT FORAMINIFERA 19

Comparatively little is known concerning the animal of the Foraminifera
except in certain littoral species. As single-celled animals the Foraminifera
are especially interesting, and their structures do not need explanation on the
basis of Organs or tissnes. There is much beauty in the ciirves of the test
and in its ornamentation, the patterns of the latter being often very intricate.

Throughout the group of Foraminifera there is- a nearly complete series,
from a simple gelatinous covering of the cell in some of the fresh-water forms
to the complex calcareous test of the higher groups. The fresh-water forms,
while not considered in the systematic part of this treatise, are nevertheless of
especial interest on account of their primitive characters. In Myxotheca the
simplest sort of covering is found, a gelatinous test which is flexible, so that
it takes the shape of the changing form of the cell. There is here also no
definite aperture, the pseudopodia being pushed through at any point. In
others of the fresh-water forms the test may be of flexible chitinous material,
biit has a definite shape when the animal is at rest and usually one or more
definite and permanent orifices.

In the marine species, which form the basis of the present work, there is
iisiially a definite, specific form to the test, and the aperture is permanent.
The materials used in making the test may be grouped in two classes : (1)
those derived from foreign sources, and (2) those secreted by the animal itself.
The foreign materials are derived from the bottom on which the animal lives,
and therefore even in the same species found under difFerent conditions there
is some Variation in the character of the materials used. In general, however,
there seems to be a certain amount of selective power on the part of certain
forms, and such characters have been used as of generic rank in systematic
work. The foreign material most frequently used is the mud or sand of the
ocean bottom, but certain forms use sponge spicules, either making them into
a soft f elted mass (Pilulina) or arranging them in a definite manner and firmly
cemented {Technitella). Other foraminiferal tests may be used, as may various
small bodies which come within the ränge of the animals. The cement in the
agglutinated tests may be chitinous, of iron oxide, or calcareous.

Of these calcareous tests two sorts have been recognised, one with a definite
aperture or series of apertures and with minute pores (the perforate group),
the other with a definite aperture or series of apertures but without minute
pores (the porcellanous group). By many writers the latter group, represented
by the Miliolidae, has been held to be primitive and a group which had not
developed perforations. On the other hand, certain evidence, such as the
perforate condition of the early chamber of Peneroplis and other genera, would
indicate that they are derived from the perforate group, and that the lack of
pores instead of being a primitive condition may in reality be a specialised
one derived from a condition in which pores were developed throughout the
life of the individual.

In general the test of the Foraminifera may be single-chambered or many-
chambered. Contrary to the impression given by certain works on the group,
the process of adding Chambers in the Foraminifera, while superficially like
budding or gemmation, is not necessarily or usually accompanied by nuclear
divisions. That is, instead of the new Chambers being potential individuals
they are simply integral parts of one cell, and in the uninucleate form the
>ingle nucleus is found in about numerically the middle chamber. In the
process of adding a new chamber a portion of the protoplasm is protruded

20 PROTOZOA— RHIZOPODA phylum i

from the aperture and a new Chamber wall then formed about it. In some
cases a complete wall is formed with each newly added Chamber, but in others
the adjacent parts of previous Chambers form the inner walls of the new^
Chamber, and new walls are formed only on the free i)arts of the protoplasmic
mass. In the open tubulär test, such as Astrorhiza or Hyperammina, increase
in the protoplasmic body is accompanied by addition of material at the open
end of the tube and an increase in size results. In single-chambered types,
such as Lagena, the manner of increase in size is problematical, if there be any
at all. In such forms the entire test may be made in its completed form at
once after division, as is the case in certain of the fresh-water Rhizopods.

In the tests having more than a single Chamber the apertures of the first-
formed Chambers become internal as a rule, and a complexity of relations to
the outside medium is thus brought about. One of the simplest arrangements
of the Chambers is a linear series. Such an arrangement is seen in Ileophax
and Hormosina. Another very common plan of arrangement is a planospiral,
as in Ammodiscus. This may be varied by having the revolving line in a spire
and then the whole test becomes trochoid, as in Trochammina. Another
common arrangement is a biserial one, the Chambers being on opposite sides
of the axis, as in Textularia. These four plans or some modification of them
are the characteristic arrangements for the Chambers in most of the secreted
tests. Oftentimes more than one plan of arrangement enters into the forma-
tion of the test. Dimorphism was used for this, but that term has been used
elsewhere with a very different meaning. As here viewed, this life-history
with several distinct methods of growth has a deeper significance than has
usually been attached to it. It seems to have a definite phylogenetic bearing
in each particalar group. The term " dimorphism " would hardly cover the
case in some genera, where eight or more distinct stages may be made out,
each with its characteristic form of Chamber, yet all appearing successively in
a Single test.

The number of Chambers in the complex tests varies from a few to a great
many. Where the size of the test becomes considerable and the Chambers
correspondingly large, the Chamber is often divided up in various ways into
chamberlets, as in Orbitolites. In such cases the adjoining chamberlets are
usually in free communication with one another. The walls of the chamber-
lets give additional strength in many forms in which they are developed.
Another characteristic modification in some genera is the development of
labyrinthic structures in the interior of the Chambers. Such structures are
seen in Oyclammina, Haplostiche, Fabularia, etc. In general, it seems tq be a
mark of the culmination of certain lines in development, and many of the
genera which developed such labyrinthic structures are now extinct. From
the appearance of a series of such tests of one species at different stages in
development, it would seem as though this labyrinthic condition was developed
as a secondary growth in the Chamber. One of its uses may be to give added
strength to the test, but this does not always seem to be the case, for it may
occur in tests which are characterised by thick walls.

The aperture in a given species seems to be rather constant when the
development is understood. Much has been written upon this subject ;
apertural characters have been used by some authors as a basis for systematic
work, and discarded by others as very variable. In a few specimens it may
seem at first sight as though the apertural characters were very variable, but

ORDER II FORAMINIFERA 21

with a large series showing different stages in development another phase of
the matter is presented. In certain cases there is a very decided change
in the condition of the aperture, but these changes appear at different stages
in the life-history, and all may be seen by cutting back a single full-grown
individual. In general, it has seemed from recent studies that apertural
characters, when studied in large series, are a rather dependable set for
systematic work, and this is true in the Miliolidae and Lagenidae especially.

In many species teeth of various sorts are developed in the aperture, and
these teeth are subject to various modifications. It can be demonstrated
that these modifications occur in a definite sequence, and that this sequence is
important from a phylogenetic point of view.

In a considerable number of genera a definite tubulär neck is developed,
with the aperture at its end. This neck is seen in many genera in a great
many modifications, and in Lagena the tube may be inverted and be directed
into the chamber of the test.

It is obvious that a very long slit-like aperture may be a source of weak-
ness to the test, especially when it is at the edge of a thin chamber. Usually
in such cases, as in Orhitolites, the animal changes its aperture from a single
one in each chamber to a considerable number. This is often coincident with
the development of chamberlets, but not invariably so, for multiple apertures
occur in PeneropUs where there are no chamberlets.

Many of the tests of the Foraminifera are beautifully ornamented. Eaised
costae, striations, knobs, spines and punctate areas form the main types of orna-
mentation. Several of these or combinations of them may occur in a single
species, the form of the ornamentation often changing as the Chambers of the
test are developed. Certain of the simpler forms of ornamentation may occur
as parallelisms in widely separated groups. As a rule, the proloculum'and
early Chambers are smooth and unornamented, but there are certain exceptions,
as in Nodosaria, for example, where in some species ornamentation may occur
on the first chamber. In specialised genera it is not uncommon to find certain
of the species with the early portion of the test ornamented, but the last-
formed Chambers with a loss of ornamentation and a consequent development
of smooth Chambers. On the other band, there may be a thickening of the
test from without and the covering of the Chambers already formed with a
secondary growth, often spinöse. Such a condition is seen in some species of
Bulimina.

Ordinarily the different parts of the test are connected with one another
by the previous apertures, but in some cases, notably in Polystomella, there is
a secondary canal System which is very complex and runs to all the parts.
This has been worked out by Carpenter and others in detail.

For many of the Foraminifera two distinct phases have been discovered.
One of these, the microspheric form, has a proloculum or first chamber of
much smaller size than the other — the megalospheric form. These two forms
are to be looked for in all species.

The microspheric form (Fig. 4, B) has a number of nuclei, often a larger
number than there are Chambers, scattered irregularly through the protoplasm
of the body. There seems to be a rather definite relation between the size of
the nuclei and the size of the chamber in which they occur, the larger nuclei
being in the larger Chambers and the reverse. Apparently these nuclei simply
divide in their reproduction during the growth of the test.

22

PROTOZOA— RHIZOPODA

rilYLUM I

When the animal attains its adult stage tbere is a great increase in the
number of pseudopodia, and the entire protoplasm either leaves the test and

accumulates aboiit the exterior or is
drawn into the outer Chambers.
Finally, each nucleus gathers a mass
of protoplasm about itself and secretes
the proloculum of a new test. This
newly formed proloculum is of the
larger type and is the first Chamber
of the megalospheric form, instead of
being of the same size as that of the
raicrospheric parent from which it was
derived. The megalospheric form (Fig.
4, A) differs from the microspheric form
This does not divide, but moves along as new

Fig. 4.

Biloculinabradyl Schlumb. Receiit ; Bay ofBiscay.
A, Small formwith megasphere. B, Large form with
microsphere. is/^ (after Schlumberger).

in having a single nucleus.
Chambers are added,
keeping in about the
middle Chamber nu-
merically. Nucleoli
appear in increasing
numbers as the growth
continues, and finally
the whole nucleus
breaks down and a great
number of minutenuclei
appear. These draw
aboüt themselves por-
tions of the protoplas-
mic mass and then di-
vide by mitotic division.
Finally, the mass leaves
the test in the form of
zoospores. These are
then supposed to con-
jugate and to give rise
to the small proloculum
of the microspheric
form, thus completing
the life cycle, although
the actual process of
conjugation has not de-
finitelybeen observed in
this group. The empty
tests left behirid must
form a large propor-
tion of the dredged
Foraminifera. The
two forms may be dis-
tinguished by the size
of the proloculum and, when sufficiently known, by other characters as well

Fig. 5.

Deep-sea ooze iiiagiiified 700 diameters. a, Bathyhius with Coccolitlis :
1>, Individual Discoliths and Cyatholiths ; c, Coccospheres ; d, Globigerina ;
r, Glohifierina with bursted test ; /, Texfularia ; g, g', Radiolaria ; h, i,
Diatoms ; Ic, l, Sponge spicules ; m, Mineral fragment.

ORDER II

FORAMINIFERA

23

The microspheric form is thus the result of a conjugation or sexual process,
while the megalospheric form is the result of simple division or an asexual
process. As a rule the megalospheric form is by far the most common, and
in many species the microspheric form is very rare, or even as yet unknown.
The microspheric form, while it Starts as a smaller individual, in most cases
attains a much larger size than the megalospheric, as might be suspected from
the nature of the reproductive processes by which it is formed. In species
where there are definite stages in development it is usually the microspheric
form which repeats these most fully, these stages being reduced or entirely
skipped in the megalospheric form of the species.

In some cases the megalospheric form may give rise to a group of megalo-
spheric young instead of to zoospores. On the whole, the life cycle agrees well
with the alternation of generations as seen in certain other groups of animals.

Fio. 6.

Specimen of prepared White Clialk from Meudon, as seen in
transmitted light imder power of 300 diameters, showing Texhi-
laria, Globigerina, and Rotalia.

Fio. 7.

Thin slice of Plänerkalk from Bohemia,
viewed in transmitted light under power of
50 diameters, showing sections of Nodosaria,
Rotalia, Frondicularia, and numerous iso-
lated Globigerina Chambers.

The vast majority of Foraminifera are marine in habit. They occur in
shallow water bordering the coasts, sometimes attached to algae, sometimes
creeping on the bottom. A few genera are extraordinarily abundant in the
open sea, being found at difFerent depths as free-swimming forms, and also on
the floor of the ocean. Enormous quantities of their remains are spread over
vast tracts of the sea-bottom, and down to a depth of 2300 fathoms they
remain an essential constituent of the deep-sea ooze. This is a finely divided
agglomeration of decomposed calcareous substances, such as the shells of
mollusks, corals, bryozoans, coccoliths, radiolarians, diatoms, sponges and
Foraminifera. Of the latter, certain genera are remarkable for their extra-
ordinary abundance (Globigerina, Orbulina, Pulvinulina, Biloculina) (Fig. 5).

In the Atlantic and Pacific Oceans Globigerina ooze is the prevailing deep-
sea deposit; in the North Sea, along the coast of Norway, Biloculina ooze.
Numerous limestones and marls of older geological periods exhibit great

24 PROTOZOA— EHIZOPODA phylüm i

similarity in structure and chemical composition to the now forming deep-sea
oozes. White Chalk (Fig. 6) is clearly a variety of abyssal ooze, from which
siliceous constituents have become segregated out, and in which Textularia
predominate instead of Glohigerina. Certain of the Eocene limestones of the
Paris basin are composed almost exclusively of the tests of Müiolidae, while
others are made up of Älveolinae and Nummulites. During the Carboniferous
period the chief role as rock-building organisms was played by Fusulina.
Many dense, apparently homogeneous, or even semi-crystalline limestones of
various ages, when examined microscopically in thin sections, are seen to be
composed in large part of Foraminifera and other organic bodies (Fig. 7).

Fossil Foraminifera are best preserved, being usually detachable from the
matrix, and at the same time occur most abundantly, in unconsolidated marls
and clays which are interbedded with calcareous strata, or in limestones of a
chalky or earthy character.

The tests of Foraminifera were first discovered by Janus Plancus, in 1730,
on the beach of Rimini, and in the following year they were found by Beccari
in the Pliocene of Bologna. They were long considered to be shells of
mollusks, and were described by Breyn, Soldani, Fichtel, d'Orbigny and
others as Cephalopoda foraminifera, in distinction from Cephalopoda sipfionifera.
Dujardin, in 1835, was the first to recognise their true character as belonging
to the Rhizopoda.

Family 1. Gromidae.

Test chitinous with an aperture at one or both ends for the pseudopodia.

The animals belonging to this family are mostly fresh-water species and
their occurrence as fossils is unknown.

Family 2. Astrorhizidae Brady.

Test composed of agglutinated material for the most part, occasionally with a
chitinous inner layer, consisting of a Chamber with several openings or a tubulär
test open at both ends; or in certain forms of a closed Chamber with a single
aperture. Throughout the family the test is not divided into a series of Chambers.

Becent and very abiindant at depth. Fossil in Paleozoic and later
formations.

Subfamily A. Astrorhizinae Brady.

Test consisting usually of a tube open at both ends or with several tubes entering
a central Chamber ; in some species with the tube branching.

The genera Astrorhiza, Bhabdammina, Marsipella, Bathysiphon and
Rhizammina make up this subfamily. Apparently fossil since the Upper
Jurassic and common in Recent.

Subfamily B. Saccammininae Brady.

Test consisting of a single Chamber, or group of superficially attached Chambers.
The walls made up for the most part of agglutinated material ; apertures sometirnes
numerous but usually single ; tests free or attached.

K

HÄRDER II FORAMINIFERA 25

^^H Saccammina Sars. (Fig. 8). Shell thick, with labyriiithiform interior ;
^^■pherical, pear-shaped or fusiform, with tubulär prolongations at one or both
^^pnds ; sometimes united together in chains. Ordovician (Ayrshire), Devonian

(Canada), Carboriiferous and Recent. Entire strata of Carboniferous rock

near Elfhills, Northumberland, are built up by aS". carteri Brady.

Large-sized species of Astrorhiza, Fsammosphaera, Saccariimina, Hyperammina,

and Rhabdammina are described by Häusler from the Upper Jurassic (Trans-

versarius beds) of Switzerland.

Thurammina Brady. Test free, monothalamous, irregularly spheroidal,

usually with excrescences or spiny processes. Upper Jurassic and Recent.

Siibfamily C. Hyperammininae.

Test consisting of a globular proloculum and a more or less elongated, some-
times hranching portion, but not divided iiito Chambers; free or attached wall
of various agglutinated materials.

The genera Hyperammina, Saccorhim, Tolypammina, Ammolagena, Jaculella
and Sagenina make up this subfamily. Some of these occur as fossils.

Subfamily D. Ammodiscinae Ciishman.

Test composed of a globular proloculum and long undivided tube, closely coiled,
either planospirally- or in changing planes or to form a spiral lest ; wall of fine
sand with much cement.

Ammodiscus Reuss. Test free, composed of a proloculum and long
coiled tubulär chamber. Carboniferous to Recent.

Family 3. Lituolidae Brady.

Test composed of agglutinated material foi' the most part ; consisting of two or
more Chambers ; arranged in a linear, coiled or irregulär series ; apertures usually
one to each chamber, but sometimes more.

The tests included in this family all have the wall composed of ag-
glutinated material with a varying amount of cement in the different genera.
Throughout the family as here used the tests are composed of two or more
Chambers and a definite proloculum is apparent. Usually the tests are
composed of a series of Chambers.

Subfamily A. Aschemonellinae Cushmaii.

Test composed of agglutinated material, divided irregularly into Chambers mthout
a defiyiite ptlan of arrangement.

Subfamily B. ReophäCinae Cushmaii.

Test of agglutinated material, sand grains, sponge spicides, etc., with a varying
amount of cement, Chambers in a linear series, aperture single at the distal end of
the last-formed chamber.

Reophax Montfort. Test free, composed of a lineal series of Chambers,

26

PROTOZOA— EHIZOPODA

PHYLUM I

joined end to end in iiearly a straight line, curved but not coiled, wall
coarsely arenaceous, Chambers undivided, aperture simple and terminal.
Carboniferous to Recent.

Haplostiche Reuss (Fig. 9). Test similar to Beophax but the Chambers
divided into labyrinthic cavities, aperture in adult made up of several pores
or dendritic. Jurassic to Recent.

Subfamily C. Trochammininae Brady.

Test composed of several Chambers, either in a planospiral coli, trochoid or other-
wise arranged ; wall composed of sand grains of varying degrees of coarseness
cemented with a calcareous or ferruginous cement ; free or attached.

Trochamminoides Cushm. (Trochammina Reuss, pars) (Fig. 10). Test free,
composed of several coils, each constricted into a number of Chamber -like
portions with large openings between ; wall of fine sand and yellowish-brown

A, Saccammina carteri
Brady. Carboniferous Lime-
stone ; Elf hüls, Northum-
berlaiid. 1/2. B, Fractured
test, filled with interior cal-
cite. 10/j (after Brady).

Haplostiche
horrida Schwa-
ger. Upper
Jurassic (Im-
pressa clay) ;
Gruibingen,
Württemberg.

Fig. 10.

Trochammina pro-
tcws Karrer. Vienna
sandston e (Senonian) ;
Hütteldorf, near
Vienna.

Fig. ]].

Lituola (Haplo-
phragmium) irregu-
laris Roemer. Sca-
phiten - Pläner ;
Kröndorf, Boheniia.

Fig. 12.

Placopsiliria
r od rata Quenst.
sp. Upper Jur-
assic (Inipressa
clay) ; Reichen-
bach, Württem-
berg.

cement, aperture simple at the end of the last-formed Chamber. Lias to
Recent.

Ammobaculites Cushm. {Haplophragmium Reuss, pars) (Fig. 11). Test free,
chambered, early portion close-coiled in one plane, later portion uncoiled and
made up of a more or less linear series of Chambers ; wall coarsely arenaceous,
fairly thick ; aperture single, at the centre of the terminal face of the uncoiled
portion, but in the coiled portion at the base of the apertural face.. Carboni-
ferous to Recent, particularly abundant in the Jurassic and Cretaceous.

Placopsilina d'Orb. (Fig. 12). Test rugose, arenaceous, attached, and
divided into pyriform or spherical Chambers, which are joined in chains or are
irregularly united. Lias to Recent.

Subfamily D. Neüsininae Cuslimaii.

Test arenaceous with som,e chitin, broad and flattened, of many Chambers, early
portion coiled, later Chambers broad and spreading ; sides with elbngated chitinous
ßaments.

Here is placed the single recent genus Neusina Goes.

Fig. 13.
Orhitolina concava Lam.

ORDER II FORAMINIFERA 27

Subfaniily E. Orbitolininae.

Test siliceoiis, imperforafe, crateriform and. composed of concentric annuli which
iire partitioned off into numerous Chambers.

Orhitolina Lam. (Fig. 13). Test composed of agglu-
tinated sandy particles ; bowl - shaped to depressed
conical ; upper surface convex, lower slightly concave ;
externally smooth or with concentric bands. Test
composed of multilocular rings, the Chambers com-
municating with one another on all sides by pores.
The outer portion of each Chamber is subdivided by
two secondary partitions disposed at rieht anerles to cenomanian; Urscheiau,

, ., -XT 1 i.'ii T 1 TT Bavarian Alps, a, Inferior

each other. Very abundant in the Lower and Upper surface; b, superior sur-
Cretaceous. 0. lenticularis and 0. concava Lam. (eniaIrg'edV''''''' '''*'''"

Family 4. Textulariidae Schnitze,

Test either arenaceous or calcareous, perforate, the Chambers usually nnmerous,
essentially biserial or triserial, or in some genera spirally arroMged.

The family Textulariidae is apparently the most primitive, after the
Lituolidae. A number of the genera are wholly or in part composed of
species with arenaceous tests, which is in itself a primitive character in the
group. In many species both the microspheric and megalospheric forms
are known. In the microspheric form, which repeats most completely the
phylogenetic characters, a coiled early development succeeding the proloculum
is commonly found. This stage may be compared to the entire development
of such a genus as Haplophragmoides in the Lituolidae.

Subfamily A. Spiroplectinae Cushman.

Test either coarsely arenaceous or calcareous, or even hyaline, the early Chambers
following the proloculum closely coiled, the later Chambers biserial, occasionally tending
to become uniserial in the last developed Chambers.

This subfamily includes the single genus Spiroplecta Ehrb., which in its
developmental stages connects the Textulariidae with the Lituolidae. Its de-
velopment is primitive in that the stages are seen in both the microspheric
and megalospheric forms of the species, and are of comparatively long duration.
Cretaceous and post-Tertiary.

Subfamily B. Textülarinae Brady.

Test typically biserial, early portion in microspheric form offen with a few coiled
Chambers, followed by biserial ones, later Chambers variously modified in diff'erent
genera, uniserial, broadly extended, etc. Wall either arenaceous or calcareous and
hyaline, perforate ; aperture single, or in a few cases, many present in a single
Chamber.

Textidaria Defr. (Fig. 14, A). Test usually elongated, straight, tapering,
or turbinated. Chambers biserial, altcrnating and communicating with each

28

PßOTOZOA— KHIZOPODA

PHYLUM I

other by means of slit-like apertures. Carboniferous to Recent. Extremely
abundant in the White Chalk.

Fig. 14.

A, Tbxtularia globifera Reuss. Upper Cretaceous (Senonian) ; Pattenauer Stollen, near Traunstein, Bavaria.
B, Bolivina incrassata Reuss. Upper Cretaceous ; Götzreuther Graben, near Siegsdorf, Bavaria. C, Flecanium
gihhosum d'Orb. Pliocene ; Sienna, Italy, D, Grammostomum {VidvuUna) gramen d'Orb. Recent; Cuba. E,
Gaudryina rugosa d'Orb. Upper Cretaceous. Götzreuther Graben, near Siegsdorf. F, ClavuUna communis
d'Orb. Miocene ; Baden, near Vienna.

Bolivina d'Orb. (Fig. 14, B). Test biserial throughout, aperture elongate,

Fig. 15.
^.r;t' tf^mT ^'''X'^"'"' 'i'O^.b- Miocene (Leitbakalk) ; Nussdorf, near Vienna. B, Bulimina pupoicks d'Orb.
Snal section iwXTM'^r\*'''n ^fv-^"""™'' ^*^"'"- .Carboniferous Limestone Dugno, Rus^sia. Longil

SeTsi^KenerBaTetnear^;^^^^^^^^^ ^^^^^^°' ^"^^^^^ "''^ (^^teV Möller). ' ., ^. J^^e^^in^^^^:

usually wider at one end, hyaline in young, thickened with age. Cretaceous
to Recent.

ORDER Ti FOEAMINIFERA 29

Climacammina Brady (Crihrostomum Möller), (Fig. 15, C, D). Test
arenaceous with calcareous basis. Chambers biserial, rectilinear. Oral aper-
ture porous. Abuiidaiit in Carboniferons Limestoiie (cf. Bigenerina d'Orb.).

Siibfaiuily C. Verneuilininae Cußliman.
Test cd first triserial, later biserial or even uniserial in some genera.

Gaudryina d'Orb. (Fig. 14, E). Test free, early portion triserial, later
Chambers arranged biserially, wall usually arenaceous.

Clavulina d'Orb. (Fig. 14, F). Test at first triserial, latest developed
portion uniserial. Eocene to Recent.

Valvulina d'Orb. (Fig. 15, E). Test arenaceous with calcareous basis.
Chambers in triple series arranged in screw-like spiral. Qarboniferous to
Recent.

Tetrataxis Ehrbg. (Fig. 15, F). Test calcareous, conical. Alternating
Chambers arranged in a turbinate spire. Carboniferous Limestone.

Siibfamily D. Bulimininae Brady.

Test composed of Chambers in an elongate spiral, aperture elongate, loop-shaped,
usually oblique, lest calcareous, hyaline in young.

Bulimina d'Orb. (Fig. 15, J, B). Test calcareous, the alternating
Chambers arranged in an elongated spire. Triassic to Recent.

Subfamily E. Cassidülininae Brady.

Test with the Chambers biserial but combined with a spiral or volute arrangement
making a complex lest.

EhrenberginaRenss (Fig. 15, G). Test calcareous, the alternating biserial
Segments either completely or only partially coiled. Tertiary and Recent.
Cassidulina d'Orb. Tertiary and Recent.

Family 5. Chilostoniellidae.

Test calcareous, finely perforate, composed of numerous Chambers, following each
other from the same end of the long axis, or alternately from the two ends, or
in cycles of three.

The genera Ellipsoidina Seg., Chilostomella and Allomorphina Reuss compose
this family. Cretaceous to Recent.

Family 6. Lagenidae Carpenter.

Test calcareous, vitreous, finely perforated, one or more Chambers placed in a
straight line, coiled or variously arranged.

<
Subfamily A. Lageninae Brady.

Test monothalamous, flask-like.

Lagena Walker (Fig. 16, A). Test single-chambered, spherical, ovate or
flask-shaped, with terminal oral aperture. Silurian to Recent.

30

PROTOZOA— RHIZOPODA

PHYLUM I

Subfamily ß. Nodosarinae Brady.

Test either coiled or uniserial, or a modification of one or the other.

Nodosaria Lam. (Fig. 1 6, B). Test rod-shaped ; Chambers arranged in
a linear series and set off from one another by constrictions ; oral aperture
round, terminal. Abundant and widelv distributed from Silurian to Recent.

Fig. 16.

A, Lagena semistriata Williamson. Antwerp Crag (Pliocene) ; Antwerp. B, Nodosaria spinicosta d'Orb.
Tegel (Miocene); Baden, near Vienna. (', Dentalina elegans d'Orh. Same locality. D^Cristellariarotulata'La.m.
Scapliiten- Pläner (Turonian) ; Boheniia. E, Va/jinulina recta Reuss. Neoconiian ; Salzgitter, Hanover. F,
LinguUna costata d'Orb. Tegel (Miocene) ; Baden, near Vienna.

Dentalina d'Orb, (Fig. 16, 6'). Like the preceding, but test slightly
arcuate. Carboniferous to Recent.

LinguUna d'Orb. (Fig. 1 6, F). Test rectilinear, compressed ; segments
regularly attached; aperture terminal, slit-like. Trias to Recent.

Glandulina d'Orb. (Fig. 17, A). Test abbreviate, ovate ; segments united
in rectilinear series, half embracing one another. General aperture round,
terminal, tubiform. Trias to Recent.

Faginulina d'Orb. (Fig. 16, E). Test rectilinear, laterally compressed;
segments flattened, with obliquely directed septa. Trias to Recent.

Margin ulina
d'Orb. Early portion
arched or helicoid,
later segments recti-
linear. Terminal
aperture slit - like.
Trias to Recent.

Cristellaria Lam.
(Fig. 16, D). Test
regularly planospiral,
with convolutions
completely envelop-
ing one another. Ter-
minal aperture round.
Trias to Recent.
Frondicularia Defr. (Fig. 1 7, D). Test extremely compressed and foliately
expanded in a single plane; Chambers r^flexed and laterally embracing one
another. Terminal aperture round. Trias to Recent.

Ä, Glandulina inflata Boruem. Septarienthon (Oligocene) ; Hennsdorf.
B, Polymorphina inflata Williamson. Recent ; German Ocean. C, Dimorphina
sp. Pliocene ; Sienna, Italy. D, Frondicularia goldfussi Reuss. Scaphiten-
Pläner ; Dülmen, Westphalia. E, Uvigerina p'ygmaea d'Orb. Tegel (Miocene) ;
Baden, near Vienna.

ORDER II

FORAMINIFERA

31

Subtaiiiily (J. Polymorphininae Brady.

Test composed of Chambers arranged spirally or irregularhj ahout the long axis ;
aperture usually radiale.

Polymorphina d'Orb. (Fig. 17, B). Segments irregularly helicoid, or
arranged biserially, more or less enveloping one another and variable in shape.
Terminal aperture round. Trias to Recent.

Dimorphina d'Orb. (Fig. 17, C). Early Chambers irregularly or triserially
arranged, later ones foUowing in rectilinear fashion. Cretaceous to Recent.

Subfaniily D. Uvigerininae Cnshman.

Test composed of Chambers arranged triserially ahout the long axis ; aperture
usually simple, with a deficite neck and a phialine lip.

Uvigerina d'Orb. (Fig. 17, E). Segments dissimilar, disposed in triple
series, and spirally wound like a gastropod shell. Eocene to Recent.

Subfamily E. Ramulininae Brady.

Test composed of Chambers with long tuhulariform tubes.

Ramulina Rupert Jones. Test branching, consisting of rounded Chambers
joined by stolon-like tubes. Recent, and possibly also represented in the
Cretaceous.

Family 7. Globigerinidae Carpenter.

Test free, calcareous, perforated by coarse tubules ; monothalamous or poly-
thalamous ; Chambers globular, either irregularly disposed or imperfectly spiral.

Of the tvvo principal genera belonging to this family, Orbulina d'Orb. (Fig.
18, A) is unilocular, and GloUgerina d'Orb. (Fig. 18, C) is multilocular. The
individual Chambers
usually open into a
common central
canal. In both
genera the test is
often covered with
extremely delicate
calcareous spines,
which, however, are
very easily broken
off, and are never
preserved intact in
the fossil State.
Both these genera

are excessively abundant in existing oceans (Globigerina ooze) ; they occur
sparingly in the Trias and throughout the Mesozoic, first becoming important
during the late Tertiary.

Sphaeroidina d'Orb. (Fig. 18, B). Characters few, so coiled as to form a
nearly globular test ; aperture with a valvulär lip. Cretaceous to Recent.

Fig. 18.

A, Orhulina universa Lam. Pliocene ; Sieniia, Italy, B, Sphaeroidina
austriaca d'Orb. Miocene Tegel ; Baden, near Vienna, C, Globigerina con-
glomerata Schwager. Pliocene ; Kar Nikobar Island, a, Inferior siirface ;
h, Superior surface ; c, Portion of periphery ; d, Transverse section enlarged.

32

PROTOZOA— EHIZOPODA

PHYLUM I

Family 8. Rotalidae Carpenter.
Test calcareous, perforate, free or adherent, typicalhj spiral at hast in the young.

Siibfamily A. Spirillininae Brady.

Test a flat spiral, without divisions, free or attached.

Spirillina Ehrenberg. Test a planospiral undivided tube, free or attached.
Miocene to Recent.

Subfamily B. Eotalinae Carpenter.

Test calcareous, rarely arenaceous or siliceous, finely or coarsely perforated,
frequently with intermediate skeleton, free or adherent, turbinate or discoidal in
contour. Segments usually arranged in an elongated spire, although in some forms
irregularly

Discorhina Parker and Jones (Fig. 19, A, B). Test coarsely perforated,

Fig. 19.

Ä, Discorhina (Asterigerina) planorbis d'Orb. Miocene (Leithakalk) ; Nussdorf, near Vieima. B, Discorhina
sp. Recent. a, Under side ; h, Upper side ; c, Lateral view ; (/, Median section. C, Planorhulina mediter-
ranensis d'Orb. Recent ; Mediterranean. a, Inferior surface ; h, Superior surface ; c, Transverse section.

turbinoid ; lower surface broad and flat ; umbilicus often filled with deposit
of intermediate skeleton. Cretaceous to Recent.

Fig. 20.

A, Rotalia heccari Lin. Pliocene ; Sienna, Italy. B, Pulvinulina partsiM d'Orb. Miocene (Tegel); Baden,
near Vienna. C, Endothyra panderi Möller. Carboniferous Limestone; Russia. 20/^, j)^ Endothyra parva
Möller. Lower Carboniferous ; Russia. Longitudinal section. loo/^.

Planorhulina Parker and Jones (Fig. 1 9 G). Test coarsely perforated, com-
planate, usually attached, upper and lower surfaces dissimilar : early segments

'UDER II

FORAMINIFERA

33

arranged in a depressed spire, subsequeiitly becoming cyclical. Lias to
Recent. Various subgeiiera, named by d'Orbigny Truncatulina, Anomalina,
Planulina, etc., are based upon slight modifications in form.

Rotalia Lam. (Fig. 20 Ä). Test finely perforated, with segments in turbinoid
spire. Septa composed of two slightly separated lamellae, with anastomosing
canals occupying the intermediate space. Base often thickened by supplemental
skeleton. (?) Silurian. Upper Jura to Recent.

PulvinuUna Parker and Jones (Fig. 20 B).
Rotaliform, but septa simple without being per-
forated by a canal System. Lower Lias to Recent.

Endothyra Phill. (Fig. 20 C, D). Test cal-
careous, composed of an external coarsely per-
forated and an internal compact layer, the latter
finely granulär; segments numerous, coiled in
an irregulär spiral, terminal Chamber opening by
several apertures. Abundant in Lower Carbon-
iferous, and existing at the present day, ac-
cording to Brady.

Calcarina d'Orb. (Fig. 21). Test discoidal, with dissimilar upper and lower
surfaces ; Chambers spirally coiled. Exterior encrusted with a supplemental
skeleton which fills up all depressions and forms spinous or spur-like processes
traversed by coarse canals. Upper Cretaceous to Recent ; very abundant in
Maestricht Chalk.

Fig. 21.

CalcMrina calcitrapoides Lam. Upper
Cretaceous (Tuffkreide) ; Maestricht,
Holland.

Siibfamily C. Tinoporinae Brady.

Test of irregularly massed Chambers, the early anes more or less distinctly spiral
in their arrangement, usually without a general aperture.

Tinoporus Montf. Patellina Williamson.

The Recent genera Carpenteria Gray, Rupertia Jones, etc., are distinguished
by their extremely irregulär, coarsely perforated and usually adherent tests,
which sometimes attain considerable size and often contain agglutinated,
Sandy or various other foreign particles. Thalamopora Roemer, occurring in
the Cretaceous, probably also belongs to this subfamily.

Family 9, Nummulitidae.

Test calcareous, finely tubulated, polythalamous, free, spiral, usually bilaterally
symmetrical.

Subfamily A. Fusulininae Brady.

Test fusiform or siibglobular Chambers extending from pole to pole, each convolu-
tion completely covering the preceding whorls.

Schwagerina Möller. Test spherical, finely perforated. Primary and
secondary septa simple, thin, straight ; secondary chamberlets communicating
with the next following principal chamber by means of a basal aperture.
Abundant in Lower Carboniferous rocks of Japan, China, Sumatra, North
America and Russia.

VOL. I D

34

PROTOZOA— RHIZOPODA

PHYLÜM I

Fusulina Fischer (Fig. 22). Test fusiform, laterally elongated like
Alveolina, coarsely perforated. Septa of principal Chambers undulating, and

Fig. 22.

Ä, Fxisulina cylindrica Fisch. Carboniferous Limestone ; Saranisk, Russia. Natural size. B, C, Same
species showing various cross-sections enlarged. D, Enlarged section showing Chambers communicating by
means of foramina (a, b).

united so as to form secondary chamberlets. Excessively abundant in
the Lower Carboniferous of Europe (Russia), Asia and North America.

Subfamily B. Polystomellinae Brady.

Test Ulaterally symmetrical, nautiloid, the more complex
IS8 specimens with a well-developed secondary canal System.

Fig. 23.

Polystomella crispa Lam.
Pliocene ; Sienna, Italy.
(Highly magnified.)

Polystomella Lamarck (Fig. 23). Test regulär, equi-
lateral, nautiloid, final whorl alone visible from the
exterior. Jurassic to Recent.

Subfamily C. Nummulitinae Brady.

Test lens-shaped or flattened, higher forms with complex secondary canal System.

Archaediscus Brady. Test lenticular, unsymmetrical, spirally coiled. The
Segments irregularly constricted and expanded so as to form Chambers. Septa
and canal-system wanting. Lower Carboniferous.

Fig. 24.

Ämphisteginahaueri d'Orb.
Miocene (Leithakalk) ; Nuss-
dorf, near Vieniia. a, Exterior
Views, enlarged ; h, Natural
size ; c, Median section,
greatly enlarged ; d, Trans-
verse section, greatly en-
larged.

Fig. 25

Operculina complanata (Ji&st.). Miocene; Bor-
deaux, a, Natural size ; h, c, Median and longi-
tudinal sections, greatly enlarged.

Heterostegina costata d'Orb.
Miocene (Leithakalk) ; Nuss-
dorf, near Vienna.

Amphistegina d'Orb. (Fig. 24). Test lenticular, slightly inequilateral,
spirally rolled. Whorls divided into Chambers by numerous single septa in

ORDER II FORAMINIFERA 35

which canals are not present; solid wedge-shaped deposit of intermediate

Fig. 27.

Nummulites cfr. lucctsamts Dfr. Eocene ; Kressenberg, Upper Uavaria. Several times enlarged.
a, Marginal cord with canal-system ; ?^ Septal plane with interseptal canal-system ; c, Interior of Chamber ;
d, Finely perforate periphery ; e, Small pillars of intermediate skeleton.

skeleton near the umbilicus. On one side the volutions completely enclose

one another as far as the centre, on the other they overlap

only partially by meaiis of alar proloiigations extending in-

wards. Chambers communicate with each other by means

of a slit along the basis. Miocene to Recent. Particularly

abundant in Miocene.

Operculina d'Orb. (Fig. 25). Test discoidal, complanate,
composed of three to six rapidly expanding spiral whorls,
which are polythalamous and non-involute. Septa and
marginal cord traversed by a direct canal-system, which gives
off numerous branches. Cretaceous to Recent. Particularly
abundant in Eocene.

Heterostegina d'Orb. (Fig. 26). Like Ojperculina, but with Chambers sub-
divided by secondary septa into chamberlets. Tertiary and Recent.

Fig; 28;

Nummulites (Assi-
lina) exponens

Eocene

Sow.
Pyrenees.

C 3 C' 1 2 Fig. 29.

A 1 ••i, Nummulites (jizchensis Ehrbg. Eocene ; Libyan Desert. Natural size. A -^ Specimen with eroded peri-
pheral i)ortion, showing arrangement of septa. B^^, Nximmulites laevigatus Lam. Calcaire Grossier ; Paris.
Natural size. B'i, Portion of same enlarged. C^^, Nummulites ramondl Defr. Eocene (Nunimulitic lime-
stone); Pyrenees. Natural size. C 3, Enlarged section.

Nummulites Lam. (Phacites Blumenb. ; Lenticulites Lam.) (Figs. 27-29). Test

36

PROTOZOA— EHIZOPODA

PHYLÜM I

symmetrically leiiticular or discoidal, composed of numerous spirally arranged
polythalamous volutions, and usually with columnar intermediate skeleton,
which forms small excresceiices on the periphery. The septa and marginal
cord contain a coarse, anastomosing canal-system, as in Operculina. Primordial
Chamber spherical, sometimes large, sometimes exceedingly minute in size.
The whorls either merely embrace one another {Ässilina) (Fig. 28), or they
completely envelop one another by means of alar prolongations reaching

inwards to the centre (Nummulina).
The septa are pierced in the median
plane by an oblique slit-like aper-
ture, and also extend into the saddle-
shaped alar prolongations of the
Chambers. They are directed in
the groups Badiatae and Striatae in
straight or slightly curved lines
(Figs. 27 and 29, C) ; in the
Sinuatae they follow meandering
courses (Fig. 29, A) ; and in the
Eeticulatae (Fig. 29, B) they form
an interlacing network by means
A, Nummuiitic limestone with horizontal sections of of connecting processcs. The rami-

N distans Fusch Peyrehorade, in the Pyrenees. B, fications of these lateral prOCeSSCS
Nummuiitic limestone showing sections of N. lucasanus w « wx i. v^ ^

Defr, zakophane in the Carpathians. (filet cloisomiaire) may be rcadily

Seen on fracturing a portion of the
test, and are a valuable aid in the determination of species. The oldest
Nummulites {N. pristinus Brady) occur very sparsely in the Carboniferous
limestone and Upper Jurassic, but are distinguished from the typical later
forms by the absence of an interior canal-system in the marginal cord. The
typical Nummulites which are so characteristic of the Eocene (Nummuiitic
limestone) in Europe, North Africa, Asia and Central America, often build up
massive formations. The largest species (JV. gizehensis Ehrbg., N. orUculatus
Schaf h.) attain a diameter of 60 mm. ; the smallest species does not exceed
2 mm. ; recent representatives comparatively scarce.

Subfamily D. Cycloclypeinae Brady.

Test flat with a thicJcened centre, or lens-shaped, consisting of a diso of Chambers
arranged in concentric annuli with peripheral thickenings, septa double with inter-
septal canals.

Orbitoides d'Orb. {Hymenocyclus Bronn; Lycophrys Monti.) (Fig. 31). Test
discoidal, with circular or stellate contour, often bent, exterior smooth or with
radial Striae, and composed of numerous concentric annuli disposed about a
primordial spiral of three to five whorls. The rings are divided by transverse
partitions into small rectangular Chambers, and the septa and marginal cord
are traversed by canals. Superimposed over the median series of principal
Chambers on both sides are several layers of flattened secondary chamberlets,
which are likewise disposed in concentric rings. Very abundant in the Eocene,
associated with Numm,ulites ; rare in Upper Cretaceous and Miocene.

Cycloclypeus Carp. Miocene and Recent.

»ER II

FORAMINIFERA

37

I

^^B Dawson, Carpenter and various other authors have referred the so-called

^^fozoon occurring in crystalline limestone of the Archaean (Laurentian) period

to the Foraminifera ; biit the elaborate investigations of Möbius have shown

in, liqn. deL.

Fig. 31.

A, Orbitoides papyracea Boubee. Eocene (Ferruginous sandstone) ; Kressenberg, Upper Bavaria, (Greatly
enlarged). i Median Chambers ; 2 Lateral Chambers ; « Compact pillars of intermediate skeleton. B, Portion of
median transverse seetion, highly magnified ; 2 Lateral Chambers with perforate walls ; 4 Canal - System of
cyclical marginal cord ; ^Tabules connecting adjacent Chambers. C, Periphery and profile of same, natural
size. D, Orbitoides tenella Gümbel. Eocene ; Kressenberg, (Natural size). E, Orbitoides variecostata Gümbel;
Eocene ; San Martino, near Verona. (Natural size.) F, Orbitoides ephippium Sow. Eocene ; Kressenberg.
(Natural size.)

that neither Eozoon nor Archaeosphaerina can be regarded as organic structures,
being merely mineral segregations.

Family 10. Miliolidae Carpenter.

Test of one or more Chambers, calcareous and porcellanouSj sometimes covered with
sand, usually imperforate, hut in some forms with the early Chambers distinctly
perforate.

Subfamily A. Cornuspirinae Ciishman.

Test planospiral, usually of a proloculum and long coiled
Single Chamber.

Cornuspira Schnitze (Fig. 32). Test composed of numer-
ous plano-spiral convolutions ; oral aperture simple, terminal;
monothalamous. Lias to Recent.

Fig. 32,

Cornuspira polygyra
Reuss, Oligocene ;

Hungary.

Subfamily B. Nubeculariinae Brady.

Test irregulär and asymmetrical, the apertures variously placed.

Nubecularia Defrance. Test at first coiled, later tubulär or irregulär ;
attached. Liassic to Recent.

38

PEOTOZOA— EHIZOPODA

PHYLÜM I

an\

Subfamily C. Häuerininae Brady.

First-formed part of test Cornuspii'a-like, later Chambers Spiral or otherwise
apertures Single.

Ophthalmidium Kubier. Early Chambers like Cornuspira, later ones two
or more to a convolution, Liassic to Eecent.

Ilauerina d'Orbigny. Early Chambers Milioline, later ones planospiral with
two or more Chambers to a convolution. Cretaceous to Recent.

Subfamily D. Miliolinae Brady.

Test at first spiral, then eacli whorl divided typically into two Chambers, laier
Chambers more numerous in the whorl or uniserial.

Miliola Lam. (Figs. 33, 34). Chambers disposed in coil-shaped loops
about a few spirally wound primordial Chambers. Each Chamber in the

Fig. 33.
A, Biloculina inornata d'Orb. From the Miocene Tegel ; Baden, near Vienna. B, Triloculina gibha d'Orb.
Oligocene sand from Astrupp. C, Sjnroloculina hadensii d'Orb. Miocene Tegel ; Baden, near Vienna. D, Quin-
qüeloculina saxorum d'Orb. Eocene (Calcaire Grossier) ; Grignon, near Paris.

Fig. 34

A, Longitudinal section of
Biloculina inornata d'Orb.
(enlarged). B, Transverse
section of Quinquelomlina
saxorum d'Orb. (enlarged).

adult forms a half coil. Terminal pseudopodial aperture either curving
in the form of a crescent about a tooth-like protection, or branching den-
dritically (Lacazina). Forms having all the segments disposed in a single
plane, and all externally visible, are grouped together in the genus Spirolocu-
lina d'Orbigny ; with all the segments completely enveloping one another,
Biloculina d'Orb. ; segments disposed in three or in five dilferent planes,

Miliolina AVill. ( = Trilocu-

•= ^^ lina and Quinqueloculina

d'Orb.). The great variety

and profusion of these

genera combine to make

them some of the most

important of the rock-

building Foraminifera.

Massive beds of Eocene

limestone (Paris basin,

Pyrenees) are made up of

Miliola remains ; at the

present day calcareous

deposits are being formed

by Biloculina in the North Sea west of the coast of Norway. Miliola first

makes its appearance in the Trias, and attains its maximum development

in the Tertiary and Recent periods.

Fig. 85.

Fahularia dis-
colithes Defr.
Eocene (Calcaire
Grossier) ; Paris.

Fig. 36.

Vertebralina mu-
cronata d'Orb.
Recent ; Medi-
terranean.

ORDER II

FORAMINIFERA

39

Fahularia Defr. (Fig. 35). Like Biloculina, but relatively larger. General
aperture cribriform; Chambers not an empty cavity, but filled with porcell-
anous or calcareous matter, and perforated by numerous anastomosing canals
which are directed parallel with the axis of convolution. Abundant in the
Eocene of the Paris basin.

Vertebralina d'Orb. (Fig. 36). First-formed portion of test consisting of
coil-shaped loops, the segments afterwards becoming joined in rectilinear
series. Tertiary and Eecent.

Idalina Schlumb. Last -for med Chamber completely enveloping all pre-
ceding ones. Cretaceous.

Subfamily E. Peneroplinae Brady.

Test planospiral or cycUcal, and bilaterally symmetrical ; apertures many.

Peneroplis Montf. (Fig. 37). Test discoidal, complanate, polythalamous ;
direction of growth primarily spiral, gradually becoming rectilinear, while
rapidly increasing in width. Septa perforated by numerous pores. Tertiary
and Recent.

A

^^'V^T^r<-:W

Fio. 37.

Peneroplis planatun
Montfort. Recent ;
Mediterranean.

Fig. 38.

Orhiculina nummis-
7?mWsd'Orbigny. Plio-
cene ; Sienna, Italy.

Fig. 39.

A, Orbitolites complanata Lam. Eocene (Cal-
eaire Grossier); Paris. B, Portion of same en-
larged.

Orhiculina Lam. (Fig. 38). Test discoidal, first-formed portion spiral,
afterwards becoming annular ; polythalamous ; septation regulär, Chambers
subdivided ; septa and walls of segments perforate. Tertiary and Recent.

Orbitolites Lam. (Fig. 39). Test discoidal, circular in outline, both surfaces
slightly concave in the middle, attaining comparatively large size, and com-
posed of segments which are arranged concentrically about a few spirally
coiled primordial Chambers. Septa radially disposed, and perforated by
symmetrically placed pores. In the more complicated forms the principal
segments are invested with a superficial multilocular layer, the Chambers of
which are also arranged in concentric rings and communicate with the
principal segments by means of pores. An important rock-building genus,
ranging from the Lias onward. 0. praecwsor and 0. circumvuha Gümbel are
Jurassic, 0. macropora d'Orb. Cretaceous, and 0. complanata Lam. Tertiary
species.

Subfamily F. Alveolininae Br£f9y.

Test spiral, elongated in the direction of the axis of coiling ; Chambers divided
into secondary chamberlets. ^,^- '~

Aheolina d'Orb. (Borelis Montf.) (Fig. 40). Test<fusiform, elliptical or
spherical, usually elongated in the axis of convolution, and composed of

40 PROTOZOA— RHIZOPODA phylüm i

spirally wound segments which completely envelop one another. Eacti Seg-
ment is partitioned off into long, narrow Chambers by septa arranged at right
angles to the axis, and these are subdivided into chamberlets by a second
set of septa running transversely to the first set. Each of the secondary
chamberlets communicates with the adjacent primary Chamber by means of a

Single round aperture. In
certain Eecent species the
secondary chamberlets are
also subdivided. The

genus begins in the Ceno-
manian, continues in ex-
^^*'- ^^- traordinary profusion, and

Älveolinahosci d'Orh. Eocene (Calcaire Grossier) ; Paris. ^.Frontal hppnmpc: n mnQf imnnrfnnf
aspect. B, Test laid open so as to show conformation of iuterior ; ^^^COmes a mOSt importaut

considerabiy eniarged. rock-builder in the Eoccne.

It is especially abundant
in the Calcaire Grossier of the Paris basin, the Alveolina limestone of Istria,
Dalmatia, Greece and the Libyan Desert.

Siibfamily G. Keramosphaerinae Brady,

Test spherical, Chambers arranged in concentric layers.

Keramosphaera Brady. Test spherical, Chambers more or less irregulär,
in concentric layers. Recent.

Range and Distribution of Fossil Foraminifera.

More than 2000 species of Foraminifera have been described, of which
number about two-thirds are known in a fossil State. The longevity of
certain genera and species is remarkable, many of them persisting, according
to Parker, Jones, Brady and others, throughout a number of formations of
various ages.

The earliest forms occur very sparingly in the Silurian of St. Petersburg,
Siberia and Scotland. They are for the most part poorly preserved, those
from Petersburg being recognisable only as glauconitic casts, belonging in
part to siliceous shell-bearing genera {Placopsilina, Saccamina), and in part to
vitreo-perforate genera (Nodosaria, Lagena, Glohigerina, Rotalia). The Devonian
is also very poor in Foraminifera remains ; but, on the other band, the Carboni-
ferous yields an abundant and considerabiy varied fauna ; in fact, certain
genera (FusuUna, Schwagerina, Saccamina, Endothyra) build up limestone de-
posits occasionally of great thickness. Numerous representatives of the
Lagenidae {Nodosaria, Dentalina, etc.), Textulariidae, Rotalidae, and even the
Nummulitidae accompany the rock-building forms, and continue for the most
part throughout the Permian. Except in the Alps, the Triassic is almost
destitute of Foraminifera, and even the pure limestones and dolomites of the
Alpine Trias have usually become so altered by metamorphism as to render
the recognition of tests wellnigh impossible. Notwithstanding, Globigerina
limestone lias been discovered in the Upper Triassic of the Northern Alps,
and tests of Cristellaria, Marginulina, Glohigerina, Textularia, Bilocidina, etc., are
found in the St. Cassian beds.

Certain argillaceous and calcareous strata of the Lias and Jura contain
vast quantities of minute, vitreo-perforate or siliceous Foraminifera. In the

ORDER III

RADIOLARIA

41

etaceous, Textalaria, Eotalia, Cristelläria, Globigerina, Miliola and coccoliths are
sential constituents of the AYhite Chalk. Individual beds of the Maestricht
Chalk consist almost entirely of Calcarina remains ; in the Urgo-Aptian Orhi-
tolina is the chief rock-builder ; in the Upper Cretaceous Alveolina.

The maximum development of the Foraminifera occurs in the Tertiary
period. Massive beds of the Eocene Calcaire Grossier of the Paris basin and
in the Pyrenees are composed of Miliolidae remains ; other Eocene limestones
consist of Alveolina, Operculina, Orbitolites and Orbitoides aggregations. But of
far greater geological importance are the Nummulites, which occur in incredible
abundance in the Eocene and Oligocene Nummulites-formations of the Medi-
terranean district, Asia Minor and Eastern Asia.

During the late Tertiary the Nummulites almost entirely disappear ; only
Amphistegina continues as an occasional rock-builder, and from the middle
and later Tertiary on, the Foraminifera fauna remains very nearly the same
as now.

Table showing

Geological

Eange of the Foraminifera

Families

ö
.2

Ö

3
§

ü

1

1

CO

1

1-3

1

1
1

>>

>>

.2

1

1

Gromidae

Astrorhizidae

Lituolidae

Textulariidac

Chilostomellidae

Lagenidae

Glohigerinidae

Rotalidae

Nummulitidae

Miliolidae

'

1

^ 1

[The foregoiiig chapter on Foraminifera has been revised for the preseut work by Dr.
Joseph A. Cushnian of the Boston Society of Natural History, Boston, Mass.— Editor.]

Orders. RADIOLARIA Müller.^

{Polycystina Ehrenberg.)

Marine FJiizopoda emitting fine, filiform, radially direded pseudopodia, with
central capsule and extra-capsulum, and usually with delicate siliceous skeleton.

The sarcode body of the Radiolarians is differentiated into (1) an inner
central sphere or capsule of tough gelatinous-like protoplasm containing one or

^ Literature : Ehrenberg, G., Mikrogeologie, 1854 ; also memoirs on Radiolaria from Barbados,
in Al)handl. Akad. Wiss. Berlin, 1872, 1875.— Haeckel, K, Die Radiolarien, lS62.—Jdem, Report
on the Radiolaria, in Scient. Results Cliallenger Exped., Zool., vol. xviii., 1887. — Hertwig, R., Der

42 PROTOZOA— RHIZOPODA phylum i

more nuclei, vacuoles, alveoles, granules, oil- globales and sometimes crystals
and surrounded by a capsule-membrane perforated by pores or pylae ; and
(2) an outer jelly-like extra-capsulum, the sarcode of which emits pseudopodia.
The individuals lead usually an isolated existence, and are only rarely united
in colonies.

Most Radiolarians secrete skeletons composed of either bars or spicules of
acanthine (an organic substance allied to hörn or chitin) or silica, or they build
an exceedingly delicate lattice-work composed of transparent amorphous silica.
Only the latter forms are known in a fossil State, and owing to their minute
size, are commonly indiscernible except with the aid of the microscope.

Haeckel divides the Radiolaria into four suborders, as follows : —

A. Acantharia. — Capsule-membrane uniformly perforated ; skeleton com-
posed of acanthinic spicules. Unknown in fossil State.

B. Spumellaria. — Capsule-membrane single, pores distributed all over;
skeleton siliceous, spherical or discoidal, sometimes wanting (Fig. 43).

Fig. 41.
Silurian and Devonian Radiolarians : A, Cenosphaera macropora Rüst. Ordovician ; Cabrieres, Langnedoc.
B, Staurolo)iche micropora, Rüst. Ordovician ; Cabrieres. C, Caryosphaera groddecJd Rüst. Upper Devonian ;
Schäbenholz, near Elbingerode, Harz Mountains. D, Lithocampe tschernytscJie%ni Rüst. Devonian ; Ural.
Magnifted 100 to 120 diameters (after Rüst).

C. Nasselaria. — Capsule-membrane single, perforated only about the otäl
pole ; skeleton siliceous, helmet- or cap-shaped, conformation of poles dissimilar
(Figs. 44, 45).

D. Phaeodaria. — Capsule-membrane double, perforated by one main opening
prolonged into a tubulus, and by a few smaller accessory openings. A dark
pigment body (phaeodium) constantly present in extra-capsular sarcode. Skeleton
commonly consisting of hollow siliceous spicules disposed in flask-shaped or
variously shaped frameworks. Unknown in fossil state.

Radiolarians are exclusively marine organisms, and are found at all bathy-
metric zones. They occur in vast numbers, especially in tropical seas,
swimming on the surface, as well as at medium and even abysmal depths.
Particularly between 2000 and 4000 fathoms in depth, extensive deposits of
" Radiolarian mud " have been found, the composition of which is largely silica
with a small percentage of carbonate of lime.

Organismus der Radiolarien. Jenaische Denkschr., 1879, vol. ii. — Stöhr, E., Die Eadiolarien- Fauna
von Grotte in Sicilien. Palaeoutogr., 1880, vol. xxvi, — Rüst, D., Radiolarien aus Gesteinen des
Jura. Palaeontogr., 1885, vol. xxxi. — Idem, op. cit., vols. xxxiv. xxxviii. and Iv. — Dreyer, F., Die
Tripoli von Caltanisetta. Jenaisclie Zeitsclir. f. Naturw., 1890, vol. xxiv. — Cayeux, Z., Les Preuves de
l'existence d'organismes dans le Precambrien. Bull. Soc. Geol. France, 1894, vol. xxii. — Vinassa
de Regny, P. E., Radiolarie delle flaniti titoniane di Carpena (Spezia). Palaeont. Italica, 1899, vol.
iv. — Hinde, G. J., Radiolaria in Devonian Rocks of New South Wales. Quart. Journ. Geol. Soc,
London, 1899, vol. \v.—Ideni, Radiolaria from the Triassic of the Dutch Fast India Archipelago.
Jaarb. Mijnwezen Nederl. Ooost India, 1908, vol. xxxvii. — Squinabol, S., Radiolarie cretacee degli
Euganee. Padova, 1904. — Principi, P., Contributo allo studio dei radiolari miocenici italiani.
Boll. Soc. Geol. Ital., 1910, vol. xxviii.

ORDER TU

RADIOLARIA 43

The diversity of form exhibited by Radiolarians is very remarkable, and

Fig. 42.
Carbotiiferous, Jurassic, and Cretaceous Radiolarians: A, Staur(u:ontium ina^qualeRnsit.

Carboniferous ;
C, Xiphodictyä ac\äa Rüst. In coprolite

Sicily.' B, Trochodisctis nicholsoni Rüst. Carboniferous; Harz. -, -^ . «„^-r^nA.

from Lias ; Ilsede, Hanover. D, Hymenütatnm rotvnditm Rüst. In coprolite from Cretaceous ; /Uli, öaxony.

the Identification of their microscopic siliceous skeletons is impossible without
the aid of special literature. Contrary to formerly current ideas, the geological
antiquity of the
Radiolarians is very
great ; and they also
play an important
part in the cora-
position of many
siliceous and cal-
careous-siliceous
rocks (quartzites,
hornstone, Jasper,
phyllites, Aptychen-
schiefer, etc.). Ac-
cording to Barrois
they are the oldest
known animal or-
ganisms, since the
Spumellaria (Mono-
sphaeroidae) occur
plentifully in the
bituminous quartz-
ites of Brittany,
interbedded with
pre - Cambrian
gneiss.

Although the
group is still very
imperfectly known,
yet, according to
Rüst, fossil Radio-
laria are by no
means less abundant and less diversified than the Recent

Recent and Tertiary Spumellarians : A, Adinomma astenunnthium Haeck.
Recent ; Messina. B, StylodictyamulHspina J1aec\i. Recent ; Messina. C,Helio-
discus Inimboldti Ehrbg. Barbados eartli (Miocene) ; Barbados. D, Haliomma
dixlphos Ehrbg. Miocene marl ; Caltan isetta, Sicily. E, Astromma aristotdis
Ehrbg. Miooene ; Barbados.

Only in exceptional

44

PROTOZOA— EHIZOPODA

PHYLUM I

Fig. 44.

Recent and Tertiary Nasselarians : A, Podocyrtis schcmiburgki Ehrbg.
Tertiary marl ; Barbados. B, Cyrtocalpis amphora Haeck. Recent ;
Messina. C, Bothryocampe hexathalamia Haeck. Recent ; Mediterranean.
D, Fetalospyris foveolata Ehrbg. Tertiary marl ; Barbados.

instances (Miocene of Barbados, Oran, Sicily) have the skeletons been preserved
unaltered, and still consist of amorphous silica. In the older rocks the silica
has usually become dissipated in the matrix, being replaced by lime carbonate,
iron, or some colouring agent ; in other cases the quartz has become crypto-

crystalline, or replaced by
a calcite pseudomorph.

The Cambrian Griffel-
schiefer of Sonneberg in
Thuringia contain poorly
preserved Sphaeroidea ; the
usually dark, though some-
times red or light-coloured
Ordovician strata of Lan-
genstriegis in Saxony, and
of Rehau and Stehen in
Franconia, the red Jasper
of Abington, Scotland,
and the Ordovician sili-
ceous rocks of Cabrieres
in Languedoc, are more or
less rieh in Radiolarian
remains belonging exclusively to the Spumellaria (Fig. 4:1, A, B).

From the Devonian Jasper of Siberia, the siliceous schists of Hesse and
Nassau, and the manganiferous quartzite of Elbingerode in the Harz, and
other places, Rüst has described forty-six Spumellarian species and seventeen
Nasselarian (Cyrtoidea). The Lower Carboniferous quartzites, phyllites,
adinole and Jaspers from the Harz (Culm formation), Ural district and Sicily
have yielded 155 species, of which thirty-six belong to the Nasselaria. In
general the Paleozoic Radiolarians are remarkable for their relatively large
size and excellent preservation.

The Triassic appears to be destitute of Radiolarians except in the Alps,
where they are abun-
dant in the hornstone
and siliceous lime-
stone of the Buchen-
stein beds of Hungary,
and occur less fre-
quently in the Rei-
fling limestones, in
the Wengen beds of
Storzic in Carniola,
in the marls of St.
Cassian, and in the
siliceous limestone of
the Rötheistein, near Aussee, etc. They are usually associated here with
the remains of Sponges and Foraminifera. In the silicified coprolites of
the Lias, found at Ilsede, Hanover, Radiolarians are very common; they
are somewhat less frequent in the limestones of the Lower Lias on the
Schafberg in Upper Austria. Certain hornstone beds of Middle Jurassic
age, found at Piszke, Hungary, the Upper Jurassic pudding-stones of

Fig. 45.
Tertiary Nasselarians from Barbados : Ä, AntJwcyrtis mespihis Ehrbg. B,
Lychnocanium lucerna Ehrbg. C, Dictyomitra montgolfieri Ehrbg. D, Eucyr-
tidium elegans Ehrbg. E, Pterocodon campana Ehrbg.

ORDER III RADIOLARIA 45

Cittiglio, near Laveno on Lago Maggiore, and numerous Tithoniaii jaspars, as
well as the Alpine Aptychus beds, are charged with Eadiolarians ; here the
Nasselaria are nearly as plentiful as the Spumellaria. The Lower Cretaceous
(Neocomian) of Gardenazza has yielded but few forms. On the other hand,
coprolites from the Gault, found near Zilli in Saxony, and Lower Cretaceous
clay marls in Manitoba, Canada, as well as from Upper Cretaceous marls of
Haldem in Westphalia, and Vordorf in Brunswick, contain excellently preserved
skeletons in greater or less abundance. Even the flinty concretions of the
Upper Chalk sometimes contain them, although in a poor State of preservation.
Certain Eocene hornstones in Italy, according to Pantanelli, are filled with
Radiolarian remains, while in the Flysch they are also very profuse in some
localities, although usually poorly preserved.

By far the most noted occurrence of fossil Radiolarians is in the siliceous
" Barbados earth," of Miocene age, in which Foraminifera are also very con-
spicuous ; while the " tripoli " of Grotte, Caltanisetta and Girgenti in Sicily,
of Oran, Aegina, Zante, the Nikobar Islands and other localities (Miocene and
Pliocene), is scarcely less noteworthy. Ehrenberg has described 278 species
from Barbados alone, and from Sicily Stöhr has described 118 species, most of
which belong to still extant Spumellarian, Nasselarian and Phaeodarian genera.

Phylumll. COELENTERATA.

CoELENTERATES or Zoophytes are free-swimming or attached aquatic animals
of very variable form and size. They difFer from the Protozoa in having
multicellular bodies with distinct organs ; and from all higher classes in the
absence of a definite body-cavity. In the subphylum Porifera there is a
simple or usually complex System of digestive sacs, with inhalent pores in the
body wall and one or many exhalent pores or oscula, and no stinging cells or
tentacles. The two other subphyla, Cnidaria and Ctenophora, exhibit a more
or less pronounced radial symmetry, have no inhalent pores and no special
exhalent opening in the body wall, but a large mouth opening conducts into a
gastrovascular cavity. Food is taken in and the excreta and sexual elements
are voided through the mouth opening. Stinging cells and usually tentacles
are present in the two last-named divisions.

The body consists of two layers of cells — an ectoderm and entoderm —
and usually also a third layer, the mesoderm. The ectoderm in the Cnidaria
often secretes a calcareous or horny skeleton, but in the Porifera the horny,
siliceous br calcareous skeletal elements are the product of the mesoderm.

Eeproduction is either sexual or asexual, or, in the Hydrozoa, an alterna-
tion of generations may occur. The process of budding or self-division gives
rise to polyzooid colonies, in which the zooids subsist in intimate relationships
with one another, and sometimes Institute a physiological division of labour.

R. Leuckart was the first to recognise the Coelenterates as constituting a
distinct structural type of animals and separated them from the Echinoderms,
with which the older systematists had associated them under the general term
of Radiates or Actinozoa. The Coelenterates are divided into three principal
groups or subphyla : Porifera, Cnidaria and Ctenophora. Of these only the first
two have skeletons and have left traces in the rocks.

Subphylum L Porifera Hogg.

The Porifera or Sponges are sessile, aquatic animals of extremely variable
form. The body consists of a single layer of pavement-cells forming the
ectoderm, a single layer of collared epithelial cells constituting the entoderm,
and usually a strongly developed mesoderm, which latter comprises the bulk of
the soft parts (including all the organs, muscles, sexual elements and nerves),
and almost invariably secretes a hard skeleton. The latter may consist of
horny sponge-fibres, or of regularly disposed siliceous or calcareous skeletal
elements. The whole body is ramified by a canal-system, and the outer
epithelial layer is perforated by countless minute, dermal pores for the entrance
of water laden with food-particles. The pores communicate by means of fine

46

CLASS I SPONGIAE 47

f

Hei

curreiit canals with subdermal ciliated Chambers, from which larger exciirrent
nals coiiduct the water and food or excreta through the body, and generally
en into a wide, exhalent opening called the cloaca or paragaster. Stinging
11s, tentacles and radial mesenteries are absent. The Porifera comprise but
one class, the Sponges.

Olass 1. SPONGIAE. Sponges.i

Sponges are remarkable for their extreme variability in external form
and size ; they lead either an isolated existence, or are united in colonies of
cylindrical, tubulate, pyriform, fungns-like, bulbous, spherical, compressed,
foliate, umbel-, bowl- or beaker-shaped, or of botryoidal form. They are long-
or short-stemraed, or a peduncle may be absent ; sometimes the stock is
branching, and the arms may be either separate or interlaced so as to form
networks. Nothing is less stable than the outer conformation, which varies
excessively aecording to the Situation and other physical conditions, and
whose systematic importance, accordingly, is very slight. The size is also
extremely variable, ranging from that of a pin-head to 1 J metres in diameter.

Sponges are invariably sessile in habit, being attached either by means of
a stem or a bündle of anchoring spicules, or they may be simply encrusting
at the base.

The canal-system by which the whole body is traversed, is extremely com-
plicated in thick-walled, but simple in thin-walled sponges. A distinction is
recognised between incurrent or inhalent, and excurrent or exhalent canals.
In the terminology proposed by Rauff, inhalent canals are designated as
epirrhysa, and exhalent canals as aporrhysa ; the former terminate on the
periphery in ostia (not to be confounded with the finer dermal pores), while
the latter terminate on the cloacal surface in postica (again not to be con-
founded with gastral pores). Postica are usually larger than ostia, and
differ from them in form and arrangement.

^ Literature : ^. On receut Sponges : —

Schmidt O., Die Spoiigien des Adriatischen Meeres. Leipzic, 1864-66. — Ide7)i, Die Spongien der
Küste von Algier. Leipzic, 1868. — Idem, Die Spongien des Meerbusens von Mexico. Jena, 1879-80.
— Haeckel, £., Die Kalkschwämme, 1872. — Schulze, Fr. Iß., Untersuchungen über den Bau
und die Entwicklung der Spongien. Zeitschr. f. wiss. Zool., 1876-80, vols. xxvii. - xxx. —
Report on the Hexactinellida. Scient. Results Challenger Exped., Zool,, vol. xxi., 1887. —
Vosmaer, G. C. J., Spongien {Porifera), in Bronn's Classen und Ordnungen des Tierreichs,
2nd ed., 1882-87, vol. iii. — Lendenfeld, R., A Monograph of the Horny Sponges. London, 1889.

B. On fossil Sponges : —

Ooldfuss, A., Petrefacta Germaniae, vol. i., 1826-33. — Michelin, H., Iconographie zoophyto-
logique, 1840-47. — Fromentel, E. de, Introduction ä l'etude des eponges fossiles. Mem. Soc. Linn.
Normandie, 1859, vol. xi. — Roemer, F. A., Die Spongitarien des norddeutschen Kreidegebirges.
Palaeontographica, 1864, vol. xiii. — Zittel, K. A., Ueber Coeloptychium. Abhandl. k. bayer.
Akad., 1876, vol. xiii. — Studien über fossilen Spongien, i., ii., iii., ibid., 1877, vol. xiii. (translated
by Dallas in Annais and Mag, of Nat. Hist. for 1877, 1878, 1879). — Beiträge zur Systematik der
fossilen Spongien, i,, ii,, iii., Neues Jahrb. für Mineral. 1877, 1878, l^l^.—Quenstedt F. A.,
Petrefactenkunde Deutschlands, 1877, vol. v. — Sollas, W. J., Quart. Journ. Geol. Soc. 1877-80,
vols. xxxiii. - xxxvi, — Hinde, G. J., Catalogue of fossil Sponges of British Museum, London,
1883.— Monograph of British fossil sponges ; Palaeontographical Society, 1887, 1888, 1893. —
Rmtff, H., Palaeospongiologie ; Palaeontographica, 1893-94, vols. xl., xli. (contains füll
bibliography). — Schrammen, A., Beitrag zur Kenntniss der obersenonen Tetractinelliden. Mittheil.
Roemer. Museum Hildesheim, 1899-1903, Nos. 10, 14, 15, 19.— Hall, J. and Clarke, J. M.,
A Memoir on the Palaeozoic reticulate Sponges constituting the family Dictyospongidae. N. Y.
State Mus. Mem. ii., 1898. Earlier contributions by same authors in loth and 16th Reports N. Y.
State Geologist, 1895-96. — Schrammen, A., Kieselspongien der oberen Kreide von Nord Westdeutsch-
land. Palaeontogr. 1910, Supplem. vol. v. — Kolb, R., Kieselspongien des schwäbischen weissen
Jura. Op. dt., 1911, vol. Ivii.

48 COELENTERATA— PORIFERA phylum ii

The water enters through the dermal pores, and passes through the
incurrent canals into ciliated Chambers, which are lined with epithelial cells.
From these it is conveyed through all parts of the body by means of the
frequently branching excurrent canals, which open into a sac-like, tube-like
or funnel-shaped cloaca. The exhalent opening of the latter is termed the
osculum. Extremely thin-walled sponges have no cloaca, osculum or branch-
ing canal-system, but the excurrent canals terminate directly in small openings
situated on the upper surface of the body. The cloaca when present is often
of considerable depth, although sometimes shallow, or reduced to a mere sac-like
Prolongation of the osculum. Forms with a large and deep cloaca are regarded
as Single individuals, those with numerous cloacae and oscula as colonies. But
since all the cloacae of a colony communicate by means of canals, while the
oscula are never surrounded by a crown of tentacles, it is often difficult to
distinguish between large excurrent canals and true cloaca, and hence also
between individuals and colonies.

Reproduction is either sexual or asexual. In the first process the fertilised
ova complete a tolerably regulär segmentation, develop into a gastrula, pass
out through the osculum, and attach themselves to some foreign object.
Asexual reproduction takes place by budding, the young buds remaining
attached to the parent individual, and thus giving rise to colonies. Re-
production by means of fission forming new colonies is of rare occurrence.

The great majority of sponges secrete a skeleton composed either of horny
fibres or of siliceous or calcareous spicules, or they incorporate foreign bodies
into their framework. Only a few Recent forms (Myxospongiae) are without
a skeleton. In the horny sponges (Ceratosponyiae) the skeleton consists of
anastomosing and reticulated fibres of spongin, an organic nitrogen Compound
resembling silk. The fibres are either solid, or they contain an axial canal,
which is sometimes cored with foreign bodies, such as sand-grains, fragments
of sponge-spicules, foraminifers, radiolarians, etc.

Siliceous spicules are sometimes encased in horny fibres, sometimes occur
detached in the cellular tissues, or are interlaced and Consolidated with one
another in various ways to form a supporting framework. In each genus the
skeleton is composed of but a single type, or at the most of but a few regularly
repeated varieties of siliceous bodies, which are called the skeletal elements. In
addition to these there occur more or less abundantly, especially on the outer
surface and in the cloacal and canal walls, extremely delicate flesh-spicules,
usually of small size and of great diversity of form. The flesh-spicules are as
a rule destroyed during fossilisation. All the siliceous skeletal elements are
secreted by nucleated cells, and are composed of concentric layers of colloidal
silica, deposited usually about a slender axial canal. In some spicules, notably
those having spherical or stellate contours, the axial canal is wanting. It is
very delicate in fresh spicules, but becomes enlarged by maceration, and in
fossil speciraens it is often coarsely calibrated.

The multitudinous varieties of siliceous skeletal elements (Fig. 46) may
be grouped into a few fundamental types, as follows : —

{a) Uniaxial spicules or monaxons (Fig. 46 ^'^^) and (^'^"^^). Straight or
bent, smooth, prickly or knotty, bevelled, sharpened or truncated needles,
rods, hooks, clasps, pins and anchors (amphidiscs). They invariably contain
an axial canal, which may be either entirely sealed up, or open at one or at
both ends.

}S I

SPONGIAE

49

I

^^m (b) Tetraxial spicules or tetraxons (Fig. 46 ^^). The normal form is
^Waracterised by four equal rays intersecting like the bisectrices of the plane
angles of a regulär tetrahedron. Triaxial forms result from the occasional
abortion of one of the rays. One of the rays may become elongated or other-
wise modified so as to form anchors (triaens) with three simple or furcate hooks
(Fig. 46 18-23^^ Three of the rays may be numerously divided or foliately
expanded so as to produce forms resembling thumb-tacks {trichotriaens, phyllo-
triaens) ; atrophy of the fourth ray in the last-named form reduces the spicule
to a delicate siliceous disk (Fig. 46 ^). A peculiar forking of the shaft gives
rise to candelabras or amphitriaens, while other modifications may produce
umbellate spicules (Fig. 46 ^^), etc.

Certain skeletal Clements of the Lithistids (Figs. 48-63) may be regarded
as irregulär tetraxons {desmoms), in which the extremities of the four rays are

Fio. 46.
Varlous forms of Sponge spicules from the Upper Cretaceous of Haldem, Westphalia ; magnified 25 diameters.
1-6, Uniaxial rod.s and needles. 7-9, Uniaxial siliceous elements with coarse axial canals. 10-13, Uniaxial
cylinders and spheres. 14, Microspined spicule. 15, Clasp-hook flesh-spicule. 16, Bispatulate tlesh-spicule.
17, llegular four-rayed spicule (chevauxde frise). 18-21, Trifld anclior-shaped spicules. 22-23, Anchors with
furcate head-rays. 24-25, Irregulär four-rayed skeletal elements. 26, Umbel-shaped spicule. 27, Six-rayed
spicule. 28, Polyaxial siliceous disk.

prolonged in knotty, root-like excrescences, or in which, owing to the un-
symmetrical growth, branching or atrophy of one or more of the arms,
extremely irregulär forms are produced ; for these a special terminology has
been devised by Rauff.

(c) Hexactinellid spicules (hexadins or triaxons) (Figs. 65-70). The
ground-form is an axial cross with six equal arms intersecting at right angles
like the axes of a regulär octahedron. Atrophy of one or more of the rays
may result in pentaxial, tetraxial, triaxial, or even clavate forms, without their
real character becoming entirely obliterated. Bifurcation or other modifica-
tions of a number or of all the rays produce beautifully formed siliceous
structures highly characteristic of the group IlexadineUida, which resemble
candelabras, double-headed anchors, fir-trees, pitch-forks, rosettes, etc. The
fusion of juxtaposed hexactins produces more or less symmetrical latticeworks
with cubical interstices.

VOL. I K

50 COELENTERATA— POEIFERA phylum i

{d) Anaxial or polyaxial bodies of spherical, cylindrical, stellate or
discoidal shape, which are not derivable from either of the tliree ground-forms,
occur in only a few varieties of recent and fossil siliceous sponges.

Calcareous skeletal elements are much less complicated, and are generally
smaller and more perishable than the siliceous. Their form is either triaxial
(triods), tetraxial (tetraxons), or nail-shaped (monaxons). The triaxial and
tetraxial spicules are very rarely forked or otherwise modified. Each skeletal
element behaves optically like a single calcite crystal ; axial canals are absent.

The skeletal elements in sponges are arranged chiefly with reference to the
circulation of water through the canal-systems. In thin-walled forms they are
more or less closely crowded together, and are often regularly oriented in the
soft parts ; in other forms they are encased in horny fibres, or are packed in
between the canals ; in still others they are united to form an irregulär frame-
work, or may be welded together in a regularly reticulated scaffolding.

The horny fibres are totally destroyed during fossilisation ; calcareous
spicules are often wholly or partially dissolved, or are replaced by infiltrating
lime carbonate, and assume a dense fibrous appearance (Fharetrones). Like-
wise in siliceous sponges the skeletal elements are rarely preserved unaltered ;
as a rule the originally colloidal silica becomes crystalline, or is dissolved and
removed. The cavities thus formed may subsequently become filled with
infiltrating quartz, limonite or most commonly with lime carbonate. In
this manner the skeletons of fossil siliceous sponges are converted into calcite,
and, contrariwise, spicules that were originally calcareous may become silicified.
Hence the distinction between siliceous and calcareous sponges in the fossil
State depends entirely upon morphological characters, and not at all upon the
chemical composition of the preserved parts.

Sponges are divided into four subclasses : Myxospongme, Ceratospongiae,
Silicispongiae and Calcispongiae. The latter group Stands in sharp contrast to
the other three, which are connected by intermediate forms, and constitute
together a 'group of equal value with the calcareous sponges. Skeletal
elements are absent in the Myxospongiae, whose bodies are composed entirely
of soft cellular tissues. The Ceratospongiae also lack imperishable hard parts,
the spongin fibres being entirely destroyed during fossilisation. The reputed
horny sponges from the Trias (EhizocoraUum), Jura and Cretaceous (Spongites,
Saxonicus, Paramudra, etc.) are either of inorganic nature or are zoologically
indeterminate. All fossil sponges, therefore, belong either to the Silicispongiae
or the Calcispongiae. The oldest forms are found in the Cambrian ; in the
Trias, Jura and Cretaceous they are very abundant.

Subclass 3. SILICISPONGIAE. Siliceous sponges.

Skeleton composed either exclusively of siliceous elements, or of horny fihres enclos-
ing siliceous spicules.

Order 1. MONAGTINBLLIDA Zittel.
{Monaxonia F. E. Schulze.)

All skeletal elements uniaxial.
The Monactinellida include the majority of existing marine sponges, most
of which occur at moderate de23ths ; and also the few fresh-water forms

ORDER II

SILICISPONGIAE— TETRACTINELLIDA

51

(Spongilla) that are known. The skeleton, as a rule, is composed like that
of the horny sponges, of anastomosing spongin fibres, which either encase
rod-like spicules, or coiitain quantities of iiniaxial siliceous elements ; some-
times the latter are also present in the soft parts. In each genus there are
usually either one or but few varieties of siliceous elements present, which are uni-
formly distributed throughout the body. Needles, hooks, crotchets, cylinders,
spindles, amphidiscs and the like occur in great diversity. Owing to the
decomposition of the horny fibres during fossilisation, and the fact that the
skeletal elements are never fused together, the latter become detached and
scattered in all directions. While Monactinellid spicules are very common
in certain formations, they are rarely united in the form of coherent
skeletons, and are only capable of generic determination when their form is
sufficiently characteristic, as in Eenieria, Esperia, etc. The basal beds of the
Alpine Lias often contain considerable hornstone, which is sometimes com-
pletely filled with rod-shaped spicules. In various Cretaceous and Tertiary
horizons Monactinellid spicules are also enormously abundant. Hinde has
described a Climacospongia from the Silurian of Tennessee, in which the
skeleton consists of spicules arranged in longitudinal rows, and connected by
transversely disposed elements. The spicules were probably originally
enclosed in horny fibres. The Clionidae secrete pin-shaped siliceous elements
which are also encased in horny fibres, and Recent sponges of this family
bore labyrinthic passages in the shells of mollusks. Fossil sponge-borings are
also common. Detached spicules of Eenieria, Axinella and Haplistion have
been described by Hinde from the English Carboniferous Limestone.

Order 2. TETRACTINELLIDA Marshall.

(Tetraxonia F. E. Schulze.)

Skeleton composed of regulär tetraxons which are generally combined with uni-
axial, polyaxial or heteraxial siliceous bodies. The
skeletal elements occur detached throughout the soft
parts, and are never united to form a connected frame-
work.

The most common forms of skeletal elements
are normal tetraxons, anchors with simple or
furcate prongs, spheres and stellate bodies. In
certain genera (Geodia) the large anchors and
cylinders are disposed in radiately arranged fasci-
cles, and are surrounded by a thick layer of
anaxial spheres.

Detached Tetractinellid spicules associated
with Monactinellids occur more or less abundantly
in the Carboniferous Limestone, the Alpine Infra-
Lias, the English Neocomain, the Deister Sand-
stone (Hils), the Upper Cretaceous of Haldem
and Coesfeld in Westphalia, and in the Tertiary
and Pleistocene formations. The skeletal elements are preserved in their
natural position in the genera Ophiraphidites Carter ; Tethyopsis Zittel (Fig. 47),
Pachastrella Schmidt, Stolleya and Cephaloraphidites Schrammen.

Fio. 47.

Tethyopsis steinmanni Zittel. Upper
Cretaceous ; Ahlten, Hanover. 14/^.

52

COELENTERATA— PORIFEEA

PHYLÜM II

Orders. LITHISTIDA Schmidt.

Massive, thick-walled, siliceous sponges, usually with complicated canal-system.
Skeleton composed of irregulär tetraxons or monaxons {desmoms) which develop
nodose or root-like hranches either at the extremities or all along the shaft, and are
firmly united hy zygosis. Symmetrical, tetraxial, uniaxial or polyaxial dermal and
flesh-spicules also present.

The Lithistids are closely related to the Tetractinellids, and in the
opinion of many zoologists, should be embraced in the same order with them.

The Lithistids are peculiarly well adapted for preservation, owing to the
massive stony character of their skeletons ; and their remains occasionally
form thick deposits, especially in the Jurassic and Cretaceous. Their outer
configuration is extremely variable ; most commonly it is crateriform,
cup-shaped, pyriform, globular, bulbous or plate-like; while the body is
attached either by the base or by means of a peduncle. The canal-system
varies greatly in different genera, but is usually well developed and more or
less complicated. The four-rayed skeletal elements are interlocked by means
of the root-like branching ends of the rays, and the points of intersection
(nodes) with the ends of adjacent uniaxial spicules are thickened into balls.
The usually irregulär uniaxial skeletal elements are interlaced on all sides by
means of root-like processes. Dermal and flesh-spicules are preserved only
under exceptionally favourable conditions, but are invariably present in
recent genera, and furnish valuable differential characters. The Classification
of fossil Lithistids is based wholly upon the skeletal elements and canal-
systems. Five principal groups are recognised, whose subdivision into
families need not concern us at present : — Tetracladina, Euiaxicladina, Anomo-
cladina, Megamorina, and Bhizomorina. Existing Lithistids occur most abun-
dantly at depths ranging between 100 and 400 metres, but are occasionally
found as deep as 1800 metres.

Suborder 1. TETRACLADINA Zittel.

Skeletal elements composed of four usually equal rays, each of which endoses an
axial canal, and has extremities ferminating in root-like Strands or processes ; the

spicules are intertwined
to form an open mesh-
work. Dermal spicules
either grapnel-like te-
traxons, frequently with
furcate prongs, or dis-
coidal with entire or
lohate margin; or they
are nail - shaped or
cylindrical monaxons.

Fio. 48,

Aulocopiurfi aurantium Oswald. Diluvium ; Sadowitz, Silesia. a, Example
in I/o natural size ; h, Skeleton magnified 60 diaraeters.

The skeletal ele-
ments of the Tetra-
cladina are usually
symmetrical tetrax-
ons, whose four smooth, more rarely tuberculate or knotty rays intersect ap-
proximately at an angle of 109^°. They occur in the Cambrian and Silurian,

»IIDER TU

SILICISPONGIAE— LITHISTIDA

53

are very scarce in the Upper Jurassic (Protetraclis), but abundant in the
Cretaceous, Tertiary and Eecent periods.

A'ulocopium Oswald (Fig. 48). Hemispherical or bowl-shaped with short
peduncle ; inferior surface covered with a dense, wrinkled, siliceous skin.

Fig. 49.

Callopegma acaule Zitt. Senonian ; Ahlten, Hanover ; a, Specimen in 3/^ natural size ; h, Skeleton magnified

40/j ; c, Portion of periphery, 2/j ; d, Same magnified 40/jj and showing anchors with furcate head-rays.

Cloaca central ; sponge body with numerous arched canals parallel to contour
of periphery, and with finer radial canals leading from exterior to cloaca.
Skeleton composed of irregulär smooth-rayed tetraclons with root-like branch-
ing extremities, disposed in rows parallel to the radial canals. Occurs (usually
replaced by calcite) in the Ordovician of the Kussian Baltic Sea Provinces,

Fig. 50.

Phymatella tuberosa (Quenstedt). Quadratenkreide
f'Upper Senonian); Linden, near Hanover. a, Sponge,
1/2 natural size ; b, Outer surface, 1/1 ; c, Skeletal element,
•'*Vl ; d, Spicules from stalk portion, 50/j.

Fig. 51.

Siphonia tulipa Zitt. Greensand ; Blackdown.
A, Longitudinalsection, natural size. B, Sponge
with ])eduncle and root, 1/2 natural, size (after
Sowerby).

Ordovician of Illinois, and Silurian of Gotland. Also in erratic blocks on the
plains of Northern Germany, usually chalcedonised.

Archaeoscyphia Hinde. Cambrian.

Callopegma Zittel (Fig. 49). Bowl- or funnel-shaped, short-stemmed, thick-
walled. External surface perf orated by smaller, internal by larger canal-openings

54

COELENTEEATA— PORIFERA

PHYLÜM II

(ostia and postica). Skeleton composed of smooth-rayed tetraclons, the digitate
extremities of which are inflated into balls. Dermal spicules in the form of
anchors and rods. Upper Cretaceous.

Phymatdla Zittel (Fig. 50). Upper Cretaceous.

Polymaraphinina, SoUasella, Pseudoplocoscyphia and Craterella Schrammen.
Upper Cretaceous.

Fig. 53.

Skeletal element of Jerea
quenstedti Zittel, showing
brancliing extremities of
rays. Qnadratenkreide; Lin-
den, near Hanover. ■^^/i.

Fig. 54,

PUnthosella sqiiamosa Zittel.
Skeleton magnilied 80 diameters.
Senonian ; Alilten, Hanover.

Fig. 52,

Jerea pyriformis Lamx,
Greensand ; Kelheim, Ba-
varia, 1/2 natural size.

Siphonia Park.
(Fig. 51). Fig-, pear-
or apple-shaped, with
a long or short ped-
uncle. Body with
deep cloaca, into
which arched canals
running parallel with
the periphery, to-
gether with numerous
fine radial canals, con-
duct. Skeleton com-
posed of smooth-rayed, branching dichotriders.
of monaxons and grapnels, Abundant in Middle and Upper Cretaceous,

Hallirhoa Lamx. Like the preceding, but invariably short -stemmed.
Body pyriform and lobate, owing to a number of deep constrictions.
Cenomanian.

Jerea Lamx. (Figs, 52, 53). Body pyriform, flask-shaped or cylindrical,
with truncate or depressed summit, in which a number of tube-like canals,
vertical in the central portion but arched in the peripheral, terminate. Cross-
ing the latter are finer radial canals, Skeleton composed of tetraclons and
dichotriders. Common in Middle and Upper Cretaceous.

Rhagadinia rimosa Roemer,
natural size ; b, Skeleton, 40/j
Spicule of dermal layer, 4o/j,

c, Lobate disk from dermal layer, 40/^ ;

Dermal spicules in the form

SILICISPONGIAE— LITHISTIDA

55

Folyjerea From. ; AstroclcuUa, lliecosiphonia, Colymmatina Zitt. ; Turonia Mich. ;
riinthosella Zitt. (Fig. 54). Cretaceous. Discodermia Boc. ; Rhacodiscula Zitt.,
etc. Cretaceous and Tertiary.

Rhagadinia Zittel (Fig. 55). Auricular, plate- or bowl-shaped, short-
stemmed. Both surfaces traversed by irregulär branching furrows, in which
the canalicular Ostia are situated. Skeletal elements four-rayed, sometimes
uniformly or only distally covered with tuberculous knobs, and with digitate
extremities. Dermal spicules in the form of six-lobed disks, provided with a
short shaft, and minute, multifid tetraclons. Upper Cretaceous.

Suborder2. EUTAXICLADINA Rauff.

Skeleton composed of four-rayed spimles with three equally developed simple or
hifurcate rays which terminale distally in root-like fibres ; and one abbreviate, inßated
fourth ray (ennomoclon). Axial canals probably in all of the rays. Skeletal elements
invariably arranged in either parallel or alternating rows, and unifed by zygosis into
a network with triangulär or irregulär meshes ; spicular nodes greatly inflated.

Nearly all the genera are Silurian ; a few (Mastosia, Lecanella) occur in the
Upper Jurassic.

^yCS^^

Astylospongia praemorsa (Goldf.). In erratic block from Mecklenburg, a, Sponge, partially cut into, natural
size; b, Skeleton, 12/^ ; c, Portion of same highly magnified.

Astylospongia Koem* (Figs. 56, b7a). Spherical, with shallow depression on
the summit ; base evenly rounded, unattached ; probably fastened by means
of anchoring fibres. Large-sized canals directed parallel to periphery in the
outer portion of the body, vertical in central
portions ; besides these there are numerous fine
radial canals which terminate in pores all
over the periphery. Skeletal elements with
four smooth elongated rays, one or all of
which brauch dichotomously just above the
junction with the shorter arm. Spicular
nodes thickened into large knots. Ordovician
of the Russian Baltic Sea Provinces, and
Silurian of Sweden and North America (not-

ably in Tennessee), usually chalcedonised. Also in erratics in the Diluvium
of Northern Germany.

Fig. 57.
a, Detached skeletal dement of Astylo-
fponriia, i'-^o/j ; b, Detached skeletal ele-
ment of Hindia, 80/^ (after Kauff).

56

COELENTERATA— POEIFEKA

PHYLUM II

Caryospongia, Carpospongia RaufF. Ordovician and Silurian ; Europe.

Falaeomanon Roem. {Astylomanon RaufF). Like Astylospongia, but bowl-
shaped, with shallower and wider cloacal depression. Entire . surf ace covered
with pores. Silurian ; North America. P. cratera Roem.

Caryomanon, Carpomanon RaufF. Silurian ; North America.

Hindia Duncan (Fig. 57&). Body spherical, with perforate periphery,
traces of attachment wanting. All canals radiate from the centre outward.
Skeletal elements composed of three simple rays beset with prickly tubercles,
and a reduced button-like fourth arm. All spicules regularly disposed in rows
parallel with the radial canals. Silurian ; North America.

Neohindia Schrammen. Upper Cretaceous ; Germany.

Suborder 3. ANOMOCLADINA Zittel.

{Didymmorina RaufF.)

Skeletal elements composed of short, smooth rays with spherically inflated ends
which give off three, four or more simple or digitale hranches ; the latter are united
hy zygosis with processes of adjacent rays ; axial canals simple. Dermal spicules
rod-shaped monaxons. Upper Silurian to Recent.

Anomoclonella, Pycnopegma RaufF. Silurian ; North America.
Cylindrophyma Zittel (Fig. 58). Body cylindrical, thick-walled, attached ;
cloaca wide and tube-like, receiving numerous radial canals, and extending

Cylindrophyma milleporata (Goldfuss). Upper White Jura ; Hoclisträss. A, Two specimens, 1/2 natural size.
B, Skeleton magnified 30 diameters. C, Detached siteletal element of Cylindrophyma, 60/^ (after Rauflf).

down as far as the base. External surface perforated by fine ostia. Common
in Upper Jurassic.

Melonella Zittel. Skeleton apple-shaped or hemispherical, with broad base,
or provided with very short .peduncle ; base covered with wrinkled siliceous
skin. Cloaca deep, funnel-shaped. Coarser canals arched, parallel with peri-
phery ; finer incurrent canals radially directed. Upper Jurassic. M. radiata
(Quenstedt).

ORDER III

SILICISPONGIAE— LITHISTIDA

57

Suborder 4. MEGAMORINA Zittel.

(Rhabdomorina RaufF.)

Usually large-sized, elongated, smooth, bmt, loosely interlocking, irregularhj
hranching, or only terminally forked skeletal Clements with simple axial canals ;
interspersed among which small, radiciform, numerously hranching Clements
{rhizomorins) are occasionally present. Dermal spicules uniaxial or grapnel-shapcd.
Ordovician, Silurian, Carboniferous, Jurassic, Cretaceous and Recent.

Saccospongia Rauff. Silurian. Megalithista Zittel. Upper Jurassic ;
Nattheim.

Dory derma Zittel (Fig. 59). Sponge-body cylindrical, simple or branching,
pyriform or compressed, with a number of larger canals running parallel
with the body
axis, and numer-
ous smaller radial
canals. Skeletal
Clements large,
bent and divided
into two or more
simple branches.
Dermal spicules
in the form of
three - fluked an-
chors. Upper
Cretaceous ; Nor-
thern Germany,
England and Fig. 59.

France AcCOrd- Doryderma dichotoma (Roemer). Upper Cretaceous. a, Sponge, natural size ; b,
TT- J Dermal layer, 2/^; c, Bündle of skeletal elements, lo/j ; d, Skeletal element and

ing to xlinde, also several dermal spicules with furcate, anchor-shaped head-rays, 30/^.

Carboniferous.

Gartcrclla Zittel ; Astcroderma Schrammen. Cretaceous.

Isorhaphinia Zittel. Sub - cylindrical, pedunculate, with wide cloaca
reaching nearly to the base. Skeletal elements large, slightly bent, rod-
shaped, inflated at the ends, rarely dichotomously branching. They are
associated in bundles, and so interlocked at their extremities as to form
an open meshwork. Cretaceous. /. texta (Roemer).

Suborder 5. RHIZOMORINA Zittel.

Skeletal elements small, composed of four or of three principal rays, or simple and
irregulär, with numcrous projecting spines or tubercles ; axial canal simple or branching.
Dermal spicules monaxons, tetraxons or similar to those of the skeleton. Chiefly
Jurassic, Cretaceous and Recent.

Nipterella Hinde. Cambrian.

Cnemidiastrum Zittel {Cnemidium, p. p. Goldf.) (Fig. 60). Turbinate or
bowl-shaped, with deep cloaca. Walls thick, p^rforated by numerous radial
canals disposed in tiers one over another, thus forming vertical fissures which
often divide toward the exterior. Skeletal elements irregularly branching,
entirely beset with blunt spiny processes. Abundant in the Upper Jurassic

58

COELENTERATA— PORIFEEA

PHYLUM II

Spongiteiikalk of South Germany, the skeletons being almost invariably
replaced by calcite. C. rimulosum Goldf. According to Binde also present
in the Carboniferous Limestone of Ireland.

Cnemidiastrum stellatum (Goldfuss). Upper Jiirassic Spongiten-
kalk ; Hossingen, Württemberg, a, Sponge, ^/^ natural size ; h,
Vertical tangential section, showing radial canalsin vertical clefts ;
c, Skeletal Clements, 60/j.

Fig. 61.
ökeleton of Jereica polystoma
(Roem.). Upper Cretaceous ; Ahlten,
Hanover. 60/.

Hyalotragos Zittel. Bowl-, plate- or funnel-shaped, with short peduncle.
Depression in summit perforated by the ostia of numerous short canals. Ex-
ternal surface finely perforate, or covered by a smooth or wrinkled dermal
layer. Skeletal elements irregulär, with numerous branches beset with points,
but with few spines. Very abundant in Upper Jurassic Spongitenkalk. H.
(Goldfuss).

Fig. 62.

Chenendoporafungiformis Jjamx. Senonian ;
Chatellerault, Touraine. 1/3 natural size.

.<^ -. ff "^ ^ ** iV \\^ ^ % y&2

Verruculina auriformis (Roemer). Quadratenkreide;
Linden, near Hanover. 2/3 natural size.

Platychonia Zittel. Leaf- or ear-shaped, irregularly undulating, covered on
both surfaces with fine pores. Skeletal elements resembling those of Hyalo-
tragos. Upper Jurassic. P. vagans (Quenstedt).

Jereica Zittel (Fig. 61). Sponge cylindrical, turbinate, pyriform or club-

ORDER IV SILICISPONGIAE— HEXACTINELLIDA 59

shaped, with short peduncle. Summit truncated or with shallow depression,
perforated by the postica of vertical excurreiit caiials. Exterior perforatod by
Ostia of the fiiier radial incurrent canals. Skeletal elements root-like, berit,
irregularly branching, with numerous short lateral processes. Upper
Cretaceous. /. polystoma (Roemer) ; /. punctata (Goldfuss).

Chenendopora Lamx. (Fig. 62). Goblet-, funnel- or bowl-shaped, with
peduncle. Cloaca deep, perforated by postica of fine canals. Skeletal
elements numerously branched and containing branching axial canal. Upper
Cretaceous.

Verriiculina Zitt. (Fig. 63). Foliate-, funnel-, ear- or bowl-shaped, short-
stemmed or sessile. Ostia on the upper surface surrounded by slight, collar-
like elevations. Middle (Gault) and Upper Cretaceous.

Ämphithelion Zitt. Like the preceding, but with both ostia and postica
terminating in bosses. Cretaceous.

Other genera : Scytalia, Coelocorypha, Stachyspongia, Pachinion, Seliscothon
Zittel ; Megarhiza and Leiochonia Schrammen, etc., in the ^iddle and Upper
Cretaceous.

Order 4. HEXACTINELLIDA O. Schmidt.

(Triaxonia F. E. Schulze.)

Süiceous sponges with six-rayed skeletal elements^ the rays being normally disposed
in three axes interseding at right angles, and containing axial canals ; elements either
detached or fused together so as fo form a lattice-like mesh. Dermal and flesh spicules
exceedingly variable in form, but invariably six-rayed.

Next to the Lithistida, the Hexactinellida are the most abundant of the fossil
siliceous sponges. They are extraordinarily variable in form, and are often
anchored by a tuft or "rope" of long, slender, vitreous fibres, or are attached
directly by the base. The walls are thin as a rule, and enclose usually a wide
cloaca ; the canal-system is consequently much simpler than in the Lithistida.,
being made up merely of short tubes which penetrate the walls more or less
deeply on both sides, and generally end blindly. Sometimes the sponge is
entirely composed of thin-walled tubes which twine about one another irregu-
larly and produce a System of lacunar interstices (intercanals) of greater or
less size.

The skeletal elements proper are distinguished by their considerably larger
size and simple form from the usually minute, astonishingly variable and
delicate flesh-spicules ; the latter, unfortunately, are seldom preserved in the
fossil State. The skeletal elements occur detached in the soft parts in the
Lyssacina group, or are partially or irregularly cemented together ; in the
Dictyonina group, on the other band, they are regularly united in such manner
that the rays of proximate elements are all closely applied against one another,
and are surrounded by a continuous siliceous envelope. In this way a more
or less symmetrical lattice-work with cubical meshes is produced, in which,
however, the fusion of juxtaposed elements is indicated in that each ray con-
tains two distinct axial canals. The junction of the rays at the central node
of each element is usually inflated, but is sometimes sculptured in such manner
as to enclose a hollow octahedron (lantern nodes, lychnisks). The exterior of
the skeleton is often covered by a dermal layer composed of irregulär hexactins.

60 COELENTERATA— PORIFERA phylum ii

in which the externally directed ray has become atrophied ; or a dense siliceous
envelope is secreted, in which stellate hexactins with reduced outwardly
and inwardly directed rays (stauractins) are embedded in greater or lesser
profusion.

The Hexactinellida of the present day are distributed chiefly over the greater
depths of the ocean beyond the hundred-fathom line (200 to 3000 fathoms).
They occur fossil principally in deep-sea deposits, and make their first appear-
ance in the Cambrian ; their period of greatest development coincides with
Jurassic and Cretaceous time.

Suborder 1. LYSSACINA Zittel. ^

Skeletal elements either entirely detached, or only partially and in an irregulär
fashion cemented together. Root-tufl offen present.

The Lyssacina are poorly adapted for preservation in the fossil state, since
the skeletal elements are but rarely cemented together to form a connected
framework, and the flesh-sjpicules are invariably destroyed. Notwithstanding,
complete sponges composed of large-sized detached hexactins have been found
in Paleozoic formations, and also in the Upper Jurassic of Streitberg; and,
indeed, the oldest sponges that can be determined with certainty all belong to
the Lyssacina.

Family 1. Protospongidae Hinde.

Thin-walled, sack-, tuhe-like or spherical sponges, with walls composed of a Single
layer of cruciform tetraxial spicules (stauractins), arranged so as to form quadrate
and suhquadrate meshes. Elements non-fasciculate. The reticulation formed by the
larger elements is divided into secondary Squares hy smaller spicules, so that the mesh-
work is constituted of several series of Squares. Cambrian and Ordovician.

To this family belong the genera Protospongia Salter, and Fhormosella Hinde.

Family 2. Dictyospongidae Hall.

Usually large, funnel-shaped, cylindrical or prismatic sponges, whose thin walls
are frequently diver sified by ridges and prominences. Skeletal framework very regulär,
and composed of larger and smaller quadrate meshes situated one within the other.
Framework formed by bundles of slender spicules. Chiefly in Devonian (Chemung)
and Lower Carboniferous (Keokuk) of North America, and Devonian of Europe.

Subfamily 1. Dictyospongiinae Hall and Clarke.

Hall and Clarke. Smooth, obconical or subcylindrical
sponges devoid of nodes, ridges or other ornamentation ; base furnished with
a tuft of long, straight, anchoring spicules. Silurian and Devonian.

Hydnoceras Conrad (Fig. 64). Obconical more or less rapidly expanding
sponges with eight prism-faces and nodes in horizontal and vertical rows. Base
with short tuft of anchoring spicules. Devonian and Carboniferous.

Lysactinella Grirty ; Hydriodictya, Prismodictya, Gongylospongia, Botryodictya,
Helicodictya, Rhabdosispongia, Ceratodictya, Clathrospongia, Lebedicfya Hall and
Clarke. Chemung Group ; New York.

ORDER IV SILICISPONGIAE— HEXACTINELLIDA 61

Subfamily 2, Thysanodictyinae Hall and Clarke.

Thysanodidya Hall and Clarke. Subcylindrical or tapering Dictyosponges
with prominent projecting, rectangularly reticulating spicular bands or lamellae
forming series of fenestrated quadrules upon the surface. Base with basal
disk or broad obcone. Devonian.

Phragmodicfya Hall ; Arystidida, Adoeodiäya, Griphodidya Hall and Clarke.
Upper Devonian and Lower Carboniferous.

Subfamily 3. Calathospongiinae Hall and Clarke.

Calathospongia Hall and Clarke. Stout subcylindrical cups with truncated
bases, probably attached by the basal margins ; contracted mesially and more
or less expanded at the aperture. Surface without
nodes. Carboniferous.

Clepsydrospongia Hall and Clarke. Thamnodidya,
Cleodidya Hall.

Subfamily 4. Physospongiinae Hall and Clarke.

Physospongia Hall. Keokuk group. Roemeri-
spongia Hall and Clarke. Eifel Devonian.

Subfamily 5. Hyphantaeniinae Hall and Clarke.

Hyphantaenia (Uphantaenia) Vanuxem. Large,
circular and shallow saucer-shaped cups, composed
of two series of intersecting spicular straps, one
radiating, the other concentric. Chemung Group;
New York.

Fio. 64.

Subfamily 6. Hallodtctyinae Hall and Clarke. cÄ"'''Siemung'G^^^^

. ^ N.Y. Sponge showing foiir rovv.s

Hallodidya Hall and Clarke. Admodidya, Crypto- of streng nodes and rineiy reticu-

T . -r-r 11 r^^ /-^ "NT ^T ^ lated surface, V? (after Hall and

didya Hall. Chemung Group ; New York. ciarke).

Subfamily 7. Aglithodictyinae Hall and Clarke.
Aglithodidya Hall and Clarke. Chemung Group ; New York.

Family 3. Plectospongidae RaufF.

Thin-walled tubes with skeleton composed of a regulär frameworh made up of an
ascending and approximately ring-like series of spicules ; the latter form redangular
to Quadrate, but not very symmetrical meshes. Spicular rays fasciculate. Ordovician
and Silurian.

Cyathophycus Walcott ; Falaeosaccus, Acanthodidya Hinde. Ordovician.
Pledoderma Hinde. Silurian.

62

COELENTEEATA— PORIFEKA

PHYLUM II

Genera incertae sedis.

Pattersonia Miller (Strohilospongia Beecher). In form of large botryoidal
clumps. Brachiospongia Marsh. Vase-like sponges with broad inferior margin
prolonged into a number of hollow arms. Ordovician of North America.
These, together with Ämphispongia Salter, and Astroconia Sollas, from the
Silurian of England, represent extinct families of the Lyssacina.

Pyritonema M'Coy {Acestra Roem.) Fascicles of long, stout spicules,
supposed to be root-tufts. Silurian.

Hyalostelia Zitt. (Acanthospongia Young). Skeletal elements relatively large,
in the form of regulär hexactins and stellate bodies with reduced vertical ray,
and with infiated nodes.
Root-tuft composed of elon-
gated, slightly bent fibres,
sometimes terminating in
four recurved rays. Cam-
brian to Lower Carboni-
ferous ; Great Britain.

Holasterella Carter;
Spiraäinella (Fig. 65), and
Acanthactinella Hinde, are pj^^ qq^

allied genera occurring in ThoUastereiia qracius
the Lower Carboniferous ?Sone -^S^f a7

ot Great Britain. f'">- Dermallayerwith

._-r. , ,-^. lused stellate spicules,

ThoUastereiia Hmde (r ig. 5/1 (after Hinde).

Fig. 65.

Spiractinella wrightii (Carter).
Carboniferous Limestone ; Sligo,
Ireland. A, Normal hexactin. B,
Hexactin with forked rays, 0/1
(after Hinde).

Fig. 67

Asteractinella expansa Hinde.
Carboniferous Limestone ;
Dalry, Ayrshire. Skeletal
Clement, 5/^ (after Hinde).

Astraeospongia menis(ni,s Roemer.
Silurian ; Tennessee. A, Sponge, in
proüle, 2/3 natural size. B, Upper
surface of same.

66), from the Carboniferous, has thin walls composed of a layer of robust,
irregularly amalgamated hexactins. As a rule, two of the rays lying in the
same plane divide dichotomously from the nodes outward, so as to produce
a six-armed instead of a four-armed cross. In Asteractinella Hinde (Fig. 67),
all of the rays lying in the same plane divide in two or more branches, thus
giving rise to many-rayed, extremely diverse, stellate and corolla-like bodies.
Carboniferous ; Ayrshire.

Astraeospongia Eoem. (Fig. 68). Thick-walled, depressed, bowl-shaped,
Upper surface concave, lower convex, without traces of attachment. Skeleton
composed of relatively large, homogeneous, uncemented cruciform spicules ;
six of the rays are disposed in the same plane, while the two rays projected
at right angles to these are reduced to short, button-like prominences. Common
in Silurian of Tennessee and Devonian of the Eifel.

ORDER IV

SILICISPONGIAE— HEXACTINELLIDA

63

According to Hiiide, Tholiasterella and AsteracMnella constitute a distinct
Order (Heteraäinellidae), and AstraeosjJongia is made the type of the order
Octadinellidae. These two groups may perhaps best be regarded as aberrant
Hexactinellids, in which supernumerary rays are produced by branching.

Suborder 2. DICTYONINA Zittel.

Skeletal spicules cemented to form, a continuous framework in such a way that
every arm of a „

hexaäin is applied
to the correspondiiig
arm of an adjacent
spicule, and hoth
rays hecome en-
veloped in a common
silieeous covering.
Root-tuft absent.

The Dictyonina
are probably de-
scendants of the
Lyssacina (possi-
bly from Froto-
spongia- and Dictyo-
phyton-Mke forms).
They appear first
in the Trias, and
play a prominent

role as rock-builders in the Jurassic and Cretaceous. Their lattice-like skeletons

are frequently replaced by calcite, or are dissolved away and merely indicated

a ' . h by cavities. The more important fossil

forms are divided into the foUowing
families.

Family 1. Oraticularidae Raiiff. {Eure-
tidae p. p., Zittel non Schulze.)

Cup-shaped, cylindrical, hranching or
flatternd sponges. Spicular nodes solid.
External surface without distinct dermal
layer, hut protected by a thickening of the
outer skeletal layer, and occasionally covered
with a delicate web of cemented spicules.
Canals simple, blindly terminating in the
skeleton. Jurassic.

Tremadictyon Zitt. (Fig. 69). Cup-,
plate-shaped or cylindrical, with wide
cloaca. Canal-openings on both sides in alternating rows. Base nodular;
exterior veiled over with delicate net-work of amalgamated hexactins, extend-
ing even across canal pores. Skeletal framework with more or less irregulär
cubical meshes. Very common in Upper Jurassic.

Craticularia Zitt. (Fig. 70). Funnel-shaped, cylindrical or flattened ;

Fig. 69.

Tremadictyon reticulatum (Goldf.). Upper Jurassic ; ötreitberg, Franconia. a,
Sponge, 2/5 natural size ; b, Enlarged portion of outer surface without dermal layer ;
c, Portion with well-preserved dermal layer, 3/j ; d, Skeleton, 12/^.

Fig. 70.

Upper Jurassic ;

Craticularia jmradoxa (Münster).
Muggendorf, Franconia. a, Sponge, 1/3 natural size ;
b, Latticed skeleton, 12/1 ; c, Thickened dermal layer,

64

COELENTERATA— POEIFERA

PHYLÜM II

simple or branching. Canal - openings on both surfaces either round or
elliptical, and regularly distributed in vertical and horizontal rows. Canals
short, ending blindly. Jurassic, Cretaceous and Miocene.

Sporadopyle Zitt. Cup- to funnel-shaped or conical, occasionally branching.
Canal -openings on the outer surface irregularly distributed, or arranged in
quincunx ; on the cloacal surface in vertical rows. Upper Jurassic. S. ohliqua
(Goldfuss).

Sphenaulax Zittel, Ferrucocoelia Etallon. Jurassic. Polyosepia Schrammen.
Upper Cretaceous.

Family 2. Ooscinoporidae Zittel.

Calycoid, beaJcer-like, lobate, branching or stellately convoluted sponges, with thin
walls perforated on both sides by numerous canal-openings arranged in alternating

rows; canals shori

blindly. Framework com-
pact, with fine meshes ;
dermal layer replaced by
thicJcening of the outermost
skeletal layer. Spicular
nodes solid, more rarely
perforate. Cretaceous.

Leptophragma Zitt.
Beaker - shaped, with
root - like attachment.
Walls thin, covered on
both sides with small
canal-openings arranged
in alternating rows.
Mesh-work very closely
woven, spicular nodes
solid. Middle and
Upper Cretaceous.

Pleurostoma'Roem.; Guettardia Mich. ; Balantionella Bchrsimmen. Cretaceous.

Coscinopora Goldf. (Fig. 71). Beaker-like, with branching roots. Ostia

small, round and in alternating rows. Skeletal elements in part with

perforated intersection nodes. Eoot consisting of long siliceous fibres. Dermal

layer formed by the thickening and fusion of outermost hexactins. Cretaceous.

Fig. 71.

Coscinopora infundibuliformis Goldf. Upper Cretaceous ; Coesfeld, West-
phalia. a, Complete speciinen, 1/2 natural size ; b, Outer surface, natural
size ; c, Same, 3/^ ; d, Skeleton of cup, 12/j ; e, Skeleton of root, i'-^/i.

Fainily 3. Staurodermidae Zittel.

Turbinate, funnel-shaped or cylindrical, more rarely branching or in clumps.
Ostia and postica irregularly distributed, or in alternating rows. Skeletal framework
more or less regidar ; intersection nodes thick or octahedrally excavated. The
outer or both surfaces of the wall provided with large, stellate spicules (stauractins),
which differ from those of the rest of the skeleton, and are either but loosely cemented
together or are embedded in a continuous siliceous skin. Jurassic and Cretaceous.

Cypellia Zitt. (Fig. 72). Top-shaped, bow-shaped or branching, without
root. Canals irregularly distributed, crooked, and branched. Lattice
skeleton with irregulär meshes, intersection nodes perforated. Dermal layer

011J)ER IV

SILICISPONGIAE— HEXACTINELLIDA

65

composed of large, four-rayed stauractins embedded in a thin, continuous or
perforated skin. Very common in Upper Jurassic Spongitenkalk.

Stauroderma Zitt. Funnel-shaped or plate-like, with broad and shallow
cloaca, into which the large, round postica of short canals open. Inner and
outer surfaces provided with dermal layer, in which stellate spicules are
embedded with reduced externally and internally directed rays. Upper
Jurassic.

Casearia Quenst. Cylindrical, with numerous annular constrictions.
Cloaca deep, tubiform ; dermal layer relatively thick, and made up of
cemented stellate spicules. Upper Jurassic. C. articulata (Goldfuss).

Porospongia d'Orb. (Fig. 73). Compressed and expanded, more rarely
bulbous or cylindrical. Superior surface pitted with large exhalent apertures
of short, blindly terminating cloacae, and covered over with a dense or finely
perforate siliceous skin, in which cruciform spicules and regulär hexactins are

Cypeläa rugosa (Goldfuss). Upper Jurassic ; Streit-
berg, Franconia. a, Spoiige, 1/2 natural size ; b, c,
Dermal layer, i^/j.

Porospongia impressa (Goldfuss). Upper Jurassic :
Muggendorf, Franconia. a, Fragment in natural size
b, Dermal layer, 6/^ ; c, Skeleton, 12/^.

embedded. Lattice skeleton with cubical meshes ; intersection nodes imper-
forate. Upper Jurassic.

Family 4. Ventriculitidae Toulmin Smith.

^Fall intricately convoluted ; folds radially disposed, generally vertical in direc-
tion. Radial canals ending hlindly. Longitudinal furrows developed along folds of
the wall, and either open, or partially covered over with a dermal layer, which is usually
formed hy thickening of the outer skeletal layer. Skeletal frameioork with octahedrally
perforated nodes. Boots consisting of elongated siliceous fibres united hy transverse
hridges and without axial canals. Jurassic and Cretaceous.

Pachyteichisma Zittel (Fig. 74). Turbinate or bowl-shaped, with very thick,
convoluted wall. Folds separated on outer surface by deeply incised furrows,
on inner surface by shallow furrows. Framework extremely regulär. Root
and dermal layer absent. Upper Jurassic.

Ventriculites Mantell (Fig. 75). Bowl-, plate-, beaker-, funnel-shaped, or
cylindrical, with wide cloaca. Wall thin, convoluted ; folds separated on both
sides by closely crowded longitudinal furrows. Lattice-work of skeleton more
VOL. I F

66

COELENTERATA— PORIFERA

PHYLUM II

or less regulär; outer layer thickened ; roots present. Common in Middle
and Upper Cretaceous.

Fia. 74.

PachyteicMsma carteri Zittel. Upper
Jurassic ; Hohenpölz, Franconia. a,
Sponge, 1/2 natural size ; b, Skeleton, 12/j.

Fig. 75.

VentricuUtes striatvs Smith. Qnadratenkreide ; Linden,
near Hanover. a, Sponge, 1/2 natural size ; b, Transverse
section, 1/1 ; c, Skeleton, 12/j.

Fio. 76.

CoeloptycTinim agaricoides Goldf. Upper Cretaceous ; Vordorf, near Brunswick. A, Top view. li, Profile.

C, Under surface, 2/3 natural size. D, Skeleton, 60/j,

Schizorhabdus, Bhizopoterion, PolyllasUdium Zittel ; Sporadoscinia Pomel ;

1

ER IV

SILICISPONGIAE— HEXACTINELLIDA

67

Lepidospongia Roemer; Leiostracosia, Plectodermatium, Microblastidium Schram-
men, etc. Cretaceous.

Family 5, Ooeloptychidae ZitteL

Umbel- or mushroom-shaped, with stalk. Wall thin, deeply folded. Convolutions
radialhj arranged, hecoming furcate toward periphery of umbel, and exposed on lower
surface. Marginal and ^^

Upper surface enveloped
with porous dermal layer
entirely covering thefolds.
Ostia only on under side
of umbel, situated on
backsof thefolds. Frame-
work very regulär ; inter-
sedion nodes odahedral,
perforated ; rays ofhex-
actins provided with
slender, thorny processes.

Coeloptychium
Goldf. (Fig. 76), oc-

curring in the Upper Cretaceous of Northern Germany, England, and Southern
Russia, is the solitary genus.

Fig. 77.
Flocoscyphia pertusa Gein. I Greensand (Cenomanian)
«.'Fragment in\natural size ;l&, Dermal layer, live times enlarged
of interior, 12/^1; d, Outward portion of skeleton, 12/j

Banowitz, Hungary.
Skeleton

Family 6. Maeandrospongidae ZitteL

Sponge body consisting of thin-walled, intricately labyrinthine, and partially
amalgamated tubes or foliae, which form tuberous, pyriform, beaker-shaped, or bush-

ß like branching Stocks.

Between the tubes are
cavities and interstices
of considerable size,
which constitute the so-
called intercanalicular
System. Four canals
faintly developed. Der-
mal layer absent, or re-
presented by a continuous
silicious superficial skin.
Abundant in the Cre-
taceous, and also re-
presented by numerous
recent genera.

Flocoscyphia Reuss
(Fig. 77). Clump-like
or bulbous Stocks con-
sisting of labyrinthic,
anastomosing tubes or foliae. Walls of tubes thin, perforated by numerous
small Ostia. Latticed skeleton, intersection nodes solid or perforate. Cre-
taceous.

Becksia Schlüter (Fig. 78). The thin walls of the shallow, beaker-like

Fig. 78.

Becksia sokdandi Schlüt. Quadratenkreide ; Coesfeld, Westphalia. A,
Sponge body, 1/2 natural size ; 0, Ostia of radial canals ; /, Hollow, root-like
processes of wall. B, Skeleton, 50/j.

COELENTEKATA— POEIFEKA

PHYLUM II

sponge are composed of vertical tubes having a radial disposition and fused
with one another along the sides. Between the tubes are large interstices ;
near the base the tubes develop hollow, spinous processes. Lattice skeleton very i
regulär, exactly similar to Coeloptijchium. Upper Cretaceous ; Westphalia.

Tremaholites Zitt. ; Etheridgia Täte ; Zittelisjjongia SinzofF, etc. Upper
Cretaceous.

Camerospongia d'Orb. (Fig. 79). Globular, sub-globular, or pyriform.

FlG

Camerospongia fungiformis
(Goldfuss). Plänerkalk ; Oppeln,
Silesia. Natural size.

Fig. 80.

Cystispongia hursa Quenst. Cuvieri-Pläner (Turonian); Salz-
gitter, Hanover. a, Sponge, natiiral size ; h, Dermal layer with
underlying skeletal framework ; c, Skeleton, 12/^.

Upper half of the body enveloped by smooth siliceous skin, and with large
circular depression on the summit ; lower half marked b}^ undulating ridges
and furrows, and passing gradually into a stem. Interior of sponge body
consists of thin-walled, labyrinthous tubes. Upper Cretaceous.

Cystispongia Eoem. (Fig. 80). Like the preceding, but with dense siliceous
skin punctured by large, irregularly shaped apertures, uniforraly enveloping
the whole sponge body. Body composed entirely of tubes. Cretaceous and
still living.

Subclass 4. CALCISPONGIAE. Calcareous Sponges.
Skeleton composed of calcareous spicules of three-rayed, four-rayed, or uniaxial

The external form of the Calcisponges is quite as variable as that of the
siliceous sponges, and reminds one particularly of the Lithistida. Like the
Lithistids, too, the thick-walled Leucones and Pharetrones have a canal-system
consisting of a central cavity into which radial excurrent canals conduct ;
while the numerous tributaries of the latter end in ciliated Chambers which
are fed by fine incurrent canals. In the Sycones the wall is perforated by
simple radial tubes, but in the thin-walled Ascones it is pierced by mere holes.

The calcareous skeletal Clements lie free in the soft parts, sometimes
forming but a single layer disposed in the same plane {Ascones) ; sometimes
their disposition is more or less distinctly radial, following the canal courses
(Sycones) ; sometimes they are irregularly crowded together (Leucones) ; and

ORDER I

CALCISPONGIAE— PHARETRONES

69

^^^^^^^^

sometimes they are closely opposed iii the form of solid anastomosing fibres
(Pharetrones). Regulär triaxial spicules are of the most common occurrence,
next monaxial spicules, sharpened on both sides, and
more rarely four-rayed spicules.

Ovving to the ready solubility of the skeletal Clements
in calcareous sponges, they are usually but poorly pre-
served in the fossil state, and are ill-adapted for micro-
scopical investigation. The three-rayed and rod-shaped
spicules which are united in fibres are seldom distinctly
recognisable as such, since, as a rule, they are either
wholly or partially dissolved, and are converted into
homogeneous or cry stalline fibres of calcite (Fig. 84) ; in
these minute threads of calcite may be seen radiating
in all directions from numerous centres of crystallisation. Sometimes such
calcareous skeletons afterwards become silicified. It is clear, therefore, that
the present chemical composition of a fossil sponge furnishes us no clue in
regard to its original character, since during the process of fossilisation a

Triaxial skeletal elements
of a Recent Ascon, ^/i.

Fio. 82,

Fibres of a Pharetrone, composed of three- Solid fibres of fossil calcar- Fibres of fossil calcareous
rayed spicules. Feronidella cylindrica (Gold- eous sponge with partially sponge altered by crystallisa-
fuss). Upper Jurassic, 40/j. preserved spicules, ^o/^. tion, 40/^.

siliceous skeleton may become converted into a calcareous, and a calcareous
into a siliceous.

Of the four Orders of calcareous sponges — Pharetrones, Sycones, Ascones, and
Leucones — only the first two are of practical importance to the paleontologist,
traces of the others being either wanting or extremely fragmentary.

Order 1. PHARETRONES Zittel.

^rall thick ; canal System like that of the Lithistida, though sometimes indistinct
and apparently absent. Spicules arranged in solid anastomosing fibres ; a smooth or
corrugated dermal layer frequently present. Devonian to Cretaceous ; unknown in
Tertiary and Recent.

Eudea Lamx. Cylindrical or club-shaped, usually simple, rarely branching.
Cloaca narrow, tubiform, extending to the base, and terminating above in a
round osculum. Dermal layer smooth, perforated by ostia of short canals.
Triassic and Jurassic. E, clavata Lamx.

Peronidella Zitt. (Peronella Zitt. non Gray ; Siphonocoelia, Polycoelia From.),
(Figs. 85, 86). Thick - walled, cylindrical, simple or branching. Cloaca
tubiform, extending to the base ; base sometimes covered by a dense dermal
layer. The rest of the exterior finely perforate. A distinct canal-system

70

COELENTERATA— PORIFERA

PHYLÜM II

absent. The coarse, anastomosing skeletal fibres composed of closely packed
three-rayed and one-rayed spicules. Sparse in Devonian (P. constricta Sandb.) ;
common in Trias, Jurassic, and Cretaceous.

Fig. 85.

Peronidella cylin-
drica (Münst.).
Upper Jura. ; Miig-
gendorf. x 1/2.

Fio. 86.

Peronidella diimosa (From.).
Hils ; Berklingen, Bruns-
wick. Natural size.

Fig. 87.

Corynella quenstedti Zitt. Coral-Rag; Natt-
heim. 0, Sponge, natural size ; b, Skeletal
fibres, 4/1.

Fig. 88.

Eusiphonella bronni
(Münst.). Coral-Rag ;
Nattheim. Natural
size.

Oculospongia tu-
hulifera (Goldf.).
Kreidetuflf; Mae-
stricht.
size.

Fig. 90.

Eusiphonella Zitt. (Fig. 88). Similar to preceding, but thin-walled, with

broad cloaca extending to
the base, into which con-
duct radial canals ar-
ranged in vertical rows.
External surface per-
forate. Upper Jurassic.
Corynella Zitt. (Fig.
87). Knob-like, cylindri-
cal, or top-shaped, thick-
walled, simple, or com-

Natural (Q^eSr €0?^^ P^'^*®' ^^^^^^ ^^^^^^ "

Nattheim. Natural size. shaped, shallow, terminat-
ing below ^in a series of
vertical branching tubes ; exhalent aperture often surrounded with radially
diverging furrows. Ostia
conducting into numer-
ously branching radial
canals, which unite again
in larger excurrent canals,
and open into the cloaca.
Common in Trias, Jur-
assic, and Cretaceous.

Stellispongia d'Orb.
(Fig. 90). Usually com-
posite Stocks made up of
hemispherical, or short

pear-shaped perSOnS, with Upper surface, natural size.

base enveloped by com-
pact dermal layer. Summit dome-shaped, with shallow cloaca surrounded by
radial furrows ; radial and vertical canals terminating along sides and basis of

Hils

Fig. 91.

Elasmostoma acntimargo Roem.
Berklingen, Brunswick.

Fig. 92.

RhapMdo nema farringdonense

(Sharpe). Lower Cretaceous

(Aptian) ; Farringdon, Berkshire.
2/0 natural size.

ORDER II

CALCISPONGIAE— SYCONES

71

cloaca. Skeleton constituted of short, bluiit, and bent uniaxial, and also of
three- and four-rayed spicules. Triassic and Jurassic.

Holcospongia Hinde. Jurassic and Cretaceous. Sestromostella Zittel. Trias
to Cretaceous. Synopella Zittel. Cretaceous. Oculospongia (Fig. 89) and
Diplostoma From. Cretaceous.

Elasmostoma From. (Fig. 91). Foliate-, ear-, or funnel-shaped. Upper {i.e.
inner) surface covered with smooth dermal layer, in which large shallow oscula
are situated ; under surface cribriform. Cretaceous.

Bhaphidonema Hinde (Fig. 92). Beaker-, funnel-, or twisted leaf-shaped.
Inner or upper surface smooth, with very small oscula or pores. Outer surface
rough, cribriform. Canal-system indistinct. Trias, Jurassic, Cretaceous.

Pachytylodia Zitt. Funnel-shaped, thick-walled ; base with smooth dermal
layer; oscula present here, but absent on other parts of the exterior. Skeleton
composed of very coarse, anastomosing fibres. Cretaceous. P. infmidihulifm'mis
(Goldfuss).

Order 2. SYCONES Haeckel.

Walls traversed hy simple canals disposed radially with reference to the cloaca
and opening into it. Skeletal elements very regulaiiy arranged.

Mostly small delicate forms inhabiting shallow water.

Protosycon Zitt., from the Upper Jurassic of Streitberg, is a small, cylin-
drical, or conical form agreeing with living Sycons in the arrangement of its
radial canals.

To the Sycons, Rauff assigns also the calcareous sponge Sphinctozoa described
by Steinmann (Jahrb. f. Mine- a

ralog. 1882, IL p. 139), which is
distinguished from all other
Calcisponges by having a most
remarkable segmentation, such
as occurs in the Lithistid genus
Casearia.

The oldest Sycons are
Sollasia, Amhlysiphonella and
Sebargasia Steinm., from the
Carboniferous Limestone of
Asturias. In the Triassic of
St. Cassian and Seelandalp,
near Schluderbach in Tyrol,
are found Colospongia Laube,
Thaimastocoelia and Cryptocoelia Steinmann. Thalamopora Roemer and Barroisia
Steinm., occur in the Lower and Middle Cretaceous.

Barroisia (Fentriculites Zitt. non Defr. ; Sphaerocoelia Steinm.) (Fig. 93).
Occurs sometimes as simple, cylindrical, or clavate individuals, and again in
the form of bushy Stocks. Outer surface frequently constricted, summit
arched, with osculum in the centre, cloaca tubiform. The cylindrical indi-
viduals are composed of thin-walled, hemispherical, or compressed segments,
which are so arranged that the roof of one segment serves also as the floor of
the next following. The wall is every where perforated by simple radial canals,

Fig. 93.

Barroisia anastomans (Mantell). Aptian ; Farringdon, Berk-
shire. A, ßush-like colony, one branch sliced open ; natural
size. B, Individual cut through obliquely, 5/2 ; a, Junction of
two Segments ; 6, Cloaca ; 0, Osculum ; d, Radial canals. C, D,
Three-rayed skeletal spicules, 3«/i and 72/i (after Steinmann).

72 GOELENTEKATA— POEIFERA phylum ii

and is made up of fibres composed of three-rayed spicules. B. helvetica (Lor.).
Aptian ; La Presta, Switzerland.

Appendix to Sponges.

Incertae seclis.
Family. Receptaculitidae Koemer.i

This Singular group which ranges througbout the Ordovician, Silurian,
and Devonian Systems, consists of globular, cup-, or platter - shaped bodies
containing a central cavity, and whose wall is composed of elements arranged
in quincunxial order. The substance of the wall is thought by Hinde to have
been siliceous ; calcareous according to Kauff ; aragonite according to Gümbel ;
calcite or chitinous according to Billings, either aragonite or chitinous in the
opinion of Girty. The elements lying on the outer or under side of the wall
have been usually described as consisting of small rhomboidal plates having
four transverse rays disposed crosswise, and one inwardly directed ray ; but
Girty has found evidence that the spicular summit plates are infiltrations of
the rhombic pits of the outer surface, and the radial pillars or spicules are
infiltrations filling radial tubes.

The systematic position of these problematic fossils is wholly conjectural.
Gümbel assigns them to the calcareous algae (Dadyloporidae), and others to
the Foraminifera and Sponges. Hinde has referred them to the HexadinelUda,
but the observations of Eauff and Girty as to the original calcareous and
chitinous composition of the wall disprove this inference.

BeceptacuUtes Defrance. Spherical or pyriform bodies, with a central closed
cavity. Ordovician to Carbon iferous. Europe, America and Australia.

Ischadites Murchison (Dictyocrinites Conrad ; Didyocrinus Hall). Conical or
ovate bodies, inclosing a central cavity, with a small summit aperture and
lacking an inner layer. Ordovician to Devonian; Europe and America.

Here are also referred Cydocrinus Eichwald ; Pasceolus Billings ; Polygono-
sphaerites Eoemer; Cerionites Meek and Worthen ; Lepidolites and Anomalospongia
(Anomaloides) Ulrich.

Range and Distribution of Fossil Sponges.

The phylogeny of the Myxospongiae, Ceratospongiae and a part of the Silid-
spongiae, owing to their perishable Organisation, remains involved in doubt.

1 Salter, J. TF., CanadianOrganic Remains, Dec. 1, 1859.— Hall, J., Pal. N. Y., vol. i., 1847 ;
Geological Report of Wisconsin, 1862 ; Sixteentli Rept. N. Y. State Cabinet Nat. Hist., 1863 ;
Twelfth Rept. State Geologist of Indiana, 1883 ; Palaeontology of New York, vol. iii., 1859 ;
Eleventh Rept. State Geologist of Indiana, 1882 ; Second Ann. Rep. N. Y. State Geologist, 1883 ;
Palaeontology of New York, vol. vi., 1887. — Ulrich, E. 0., Jour. Cincinnati Soc. Nat. Hist., vol. i.,
1871; vol. ii., 1879. — Owen, D. />., Geol. Report Iowa, Wisconsin and Illinois, 1844; Geol.
Survey of Wisconsin, Iowa and Minnesota, 1852. — Billings, E., Palaeozoic Fossils, vol. i., 1865 ;
Canadian Naturalist and Geologist, second ser., vol. ii., 1865 — Meek and Worthen, Geol. Survey of
Illinois, vol. iii., 1868. — Gümbel, G. W., Abhandl. der k. bayr. Akad. Wissensch., vol. xii., 1875. —
Roemer, F., Letliaea Palaeozoica, 1880. — Hinde, G. J., Quart. Jour. Geol. Soc. London, vol. xl.,
\8M.— James, J. F., Jour. Cincinnati Soc. Nat. Hist., vol. viii., 1885 ; vol. xiv., ISdl.— Walcott, C. 1).,
Mon. U. S. Geol. Surv., vol. viii., 1884:.— Whüßeld, R. P., Geology of Wisconsin, vol. iv., 1884.—
Rauff, H., Zeitschr. deutsch, geol. Gesellsch., vol. xi., 1888. — Nicholson and Lydekker, Manual of
Palaeontology, vol. ii., 1889 — Winchell and Schuchert, Geol. of Minnesota, vol. iii., pt. 1, Pal.
1895. — Ulrich, E. 0., ibid., p. 68— Girty, G. //., Fourteentli Ann. Rept. N. Y. State Geologist
for 1894, 1895. — Weller, S., Geol. Survey of New Jersey, Rept. on Pal., vol. iii., 1903.

I

RANGE OF FOSSIL SFONGES 73

Nevertheless, isolated spicules prove the existence of Monactinellids and
Tetractinellids in Paleozoic seas ; while in the Trias, Jura and Cretaceous
these forms become important rock-builders, and play an active part in the
formation of hornstone, chalcedony and flint. In the Tertiary, spicules refer-
able to existing genera are common.

The former distribution of the three best preserved sponge groups — the
Lithistids, Hexactinellids, and Calcisponges — is noteworthy. The living repre-
sentatives of the first two Orders inhabit deep or moderately deep water, while
the calcareous sponges predominate in shallow waters bordering the coast.
And hence, since fossil Calcisponges likewise occur almost entirely in marly,
clayey, or sandy strata of undoubted littoral origin, and are absent in lime-
stones where Lithistids and Hexactinellids predominate, it is piain that the
distribution of both fossil and Recent sponges has been occasioned by like
physical conditions.

In the Cambrian occur the Lithistid genera Archaeoscyphia and Nipterella,
and in the Ordovician and Silurian of Europe and North America are found
a number of Tetracladina (Aulocopium) and Eutaxidadina forms {Astylospongia,
Palaeomanon, Hindia), together with a few Rhizomorina. In the Carboniferous
ßhizomorina and Megamorina are sparsely represented ; but in the Upper
Jurassic, and especially in the Spongitenkalk of Franconia, Swabia, Switzer-
land, and the Krakau district, the Lithistids exhibit an astonishing develop-
ment, and occasionally form thick beds. They occur only sparingly in the
Lower Cretaceous, but are abundant in the Pläner, Greensand and Upper
Cretaceous of Northern Germany, Bohemia, Poland, Galicia, Southern Russia,
England and France. The Tertiary being nearly everywhere made up of
shallow-water formations, the absence of Lithistids and Hexactinellids is not
surprising. They persist locally, however, as in the Upper Miocene of Bologna
and in the Province of Oran in Northern Africa.

The ränge of the Hexadinellida is in every respect similar to that of the
Lithisiida. Beginning in the Upper Cambrian, they are represented in the
Ordovician and Silurian by peculiarly modified Lyssacina forms (Protospongia,
Phormosella, Cyathophycus, Palaeosaccus, Pledoderma, Pattersonia, Brachiospongia,
Didyophyton, Astraeospongia). The same group continues also through the
Devonian, where Didyophyton and its associates are conspicuous for their wide-
spread distribution in North America. A few aberrant Lyssacina, which Hinde
designates as Heteradinellidae, are found in the Carboniferous. During the
Mesozoic and Cenozoic eras the distribution of the Hexadinellida is nearly
identical with that of the Lithistida; although here and there beds occur
which are charged principally with Hexactinellids, and others chiefly with
Lithistids.

Very different conditions are presented by the Calcisponges, among which
only the Pharetrones and Sycons are of geological importance. The oldest
calcareous sponges occur very sparsely indeed in the Middle Devonian and
Carboniferous Limestone. They appear in considerable diversity in the Alpine
Trias (St. Cassian and Seelandalp), but outside the Alps are almost wholly
absent. In the Jurassic they occur in marly beds of the Dogger (Ranville,
Swabia), and also in certain facies of the Malm (Terrain ä Chailles, Coral-Rag
of Nattheim, Sontheim, etc.) in Southern Germany and Switzerland.

The Lower Cretaceous, particularly the Neocomian of Brunswick, the
Swiss Jura, and the Paris Basin, as well as the Aptian of La Presta, near

74 COELENTEKATA— CNIDARIA phylum ii

Neuchätel, and Farringdon, Berkshire ; and also the Middle Cretaceous (Ceno-
manian) of Essen, Le Mans, and Havre, are characterised by an abundance of
well-preserved Pharetrones, and a lesser number of Sphinctozooid Sycons. In
the Tertiary, however, both groups are wanting, although the existence of
calcareous sponges is still indicated by occasional detached triactins. The
Pharetrones apparently become extinct at the close of the Cretaceous.

SuBPHYLUM II. Cnidaria.

The Cnidaria or Nematophora have a radially symmetrical body, and a
terminal mouth-opening surrounded by fleshy tentacles. In the ectoderm
(sometimes also in the entoderm) cnidoblasts are common, from the contents
of which thread-cells (nematocysts) filled with an urticating fluid and containing
a hollow, spirally coiled thread, are developed. Each cnidoblast possesses a
fine superficial process (cnidocil), which is very sensitive to mechanical Stimuli,
The polyp wall typically consists of three layers : an outer ectoderm, an inner
endoderm, and a middle mesogloea. The mesogloea is sometimes entirely
absent, but the ectoderm and entoderm are strongly developed. The ectoderm
frequently secretes a calcareous or horny skeleton, and both ectoderm and
entoderm are concerned in the production of muscles and nerves. The sexual
Organs are the product of the entoderm.

The Cnidaria are divided into two classes : Anthozoa and Hydrozoa. The
latter are undoubtedly the more primitive group, but it will be convenient to
treat of the Anthozoa first in the present work.

Olass 1. ANTHOZOA = A0TINOZOA. Coral Polyps.i

Usually sessikj cylindrical polyps, possessing a mouth surrounded by tentacles,
Oesophagus, and gastrovascular cavity. The latter is divided by numerous vertical
partitions (mesenteric folds) into a System of radially disposed pouches. A calcareous
or horny skeleton is frequently developed. Simple or forming colonies.

The simple polyp zooids have the form of a cylindrical or conical tube
at the distal end of which is situated a muscular disk perforated centrally by

^ Literature : Milne Edwards, H., et Haime, J., Histoire naturelle des coralliaires, 3 vols. and
atlas. Paris, 1857-60. — Idem, Monographie des polypiers fossiles des terrains paleozoiques. Arch. du
Museum, Paris, vol. v., 1851. — Idem, Monograph of the British Fossil Corals. Palaeontogr. Soc,
1849-64. — Fromentel, E. de, Introduction a l'etude des polypiers fossiles. Paris, 1858-61. — Idem,
Paleontologie frangaise ; 1861 and later. — Reuss, A. E., Articles in Sitzber. Akad. Wiss. Wien, 1859,
1864, 1865, 1870 ; also Denkschr. vols. vii., xxiii., xxviii., xxix., xxxi., xxxiii. — Duncan, P. M., British
Fossil Corals, 2d ser. Palaeontogr. Soc. 1865-69, and 1872. — Idem, Revision of the Families and
Genera of the Sclerodermic Zoantharia or Madreporaria. Journ. Linn. Soc. Zoology, 1885, vol.
xviii. — Kohy, F., Monographie des polypiers jurassiques de la Suisse. Abhandl. Schweiz. Pal. Ges.,
1880-94, vols. vii.-xxii. — Pratz, E., Ueber Septalstructur. Palaeontogr. 1882, vol. xxix. — Koch,
G. von, Die ungeschlechtliche Vermehrung der paläozoischen Korallen. — Ibid., 1883, vol. xxix. —
Quenstedt, F. A., Petrefactenkunde Deutschlands, 1889, vol. vii. — Kohy, F., Monographie des poly-
piers cretaces de la Suisse. Abhandl. Schweiz. Pal. Ges. 1896-98, vols. xxii.-xxiv. — Ogüvie-Gordon,
Maria M., Korallen der Stramberger Schichten. Palaeontographica, Supp. II., 1897. — Idem,
Systematic Study of Madreporarian Types of Corals. Phil. Trans. Roy. Soc. London, 1897, ser.
B, vol. clxxxvii. — Gregory, J. W., I^he Corals, Jurassic Fauna of Cutch. Palaeontol. Indica, 1900,
ser. 2, vol. ix., pt. 2. — Vaughan, T. Wayland, Eocene and Lower Oligocene Coral Faunas of the
United States. Mon. xxxix, U.S. Geol. Survey, 1900. — Ide7n, Critical Review of the Literature on
the simple Genera of the Madreporaria Fungida. Proc. U.S. Nat. Mus., 1905, vol. xxviii. —
Buerdeii, J. E., West ludian Madreporarian polyps. Mem. Nat. Acad., 1902, vol. viii, — Idem,

5S I

ANTHOZOA

75

^^|l|e slit-like or oval fissure of the mouth. The oral disk is furnished with a ring
of tentacles round its margin, and opeiis into a membranous oesophageal tube
conducting into the gastric cavity. The outer covering of the body, the parts
of which are designated as wall, oral disk, and pedal disk, are constituted of
ectoderm and entoderm, between which is a thin layer of mesoderm (mesogloea).
Six, eight, or more radially disposed vertical partitions (mesenteries), (Figs. 94,
95), projecting inwardly from the body-wall, divide the gastric cavity into a
series of radiating compartments (mesenteric pouches). The mesenteries are
continuous upwardly with the hollow, muscular tentacles ; while the generative
Organs are attached to their faces near the lower end of the body. The
mesenteries are »covered on both sides with muscular tissues, and bear mesen-
teric filaments on their curled inner edges. On one side of the mesenteries
the muscle fibres are transversely directed, on the other longitudinally. The
longitudinal System is usually considerably folded and thickened ; and the
disposition of these
muscular portions is of
great importance from a
systematic standpoint,
since it reveals the
bilateral symmetry of
many Anthozoans, and
enables one readily to
identify the antimeres.
If a polyp individual be
cut in two by a plane
passing through the
longer axis of the
mouth-opening, then, in
the Octocoralla (Fig
94), the mesenteries of
the right half will have

all the muscular thickenings disposed on the right-hand side, and those of the
left on the left-hand side. In the Hexacoralla (Fig. 95) the mesenteries are
grouped in pairs, with the muscular thickenings of any pair facing each other.
Two pairs, however (those corresponding with the opposite extremities of the
longitudinal mouth), form often an exception to this rule, since these have the
muscular thickenings placed on opposite sides. These are called the directive
mesenteries, and serve to indicate the longitudinal axis of the body.

Only a few Anthozoa have permanently soft bodies ; the majority secreting
calcareous, horny, or partly horny and partly calcareous structures, termed the
skeleton or corallum. The simplest form of corallum is that composed of
microscopic, round, cylindrical, acerate, or tuberculated spicules of carbonate

Fig. 94.

Diagrammatic section of
the soft parts of an Octo-
coralla (Alcyoninm). x, Oeso-
phagus ; 1, 2, 3, 4, Mesen-
teries of the left side (after
R. Hertwig).

Fig. 95.

Diagrammatic section of the soft parts of
a Hexacoralla. In the upper half (above the
line a — h) the section passes through Oeso-
phagus s ; in the lower half, beneath the
same. Corallum indicated by heavy lines.
r, directive mesenteries.

Morphology of the Madreporaria. A series of papers in Ann. and Mag. Nat. Hist., ser. 7, vols. ix.,
X., xi., xvii.,xviii. (1902-1906), and Biol. Bull.,vols. vii. and ix. (1904-1905).— /rfew, Recent Results on
the Morpliology and Development of Coral Polyps. Smithsonian Miscellaneous Collections, Quart. Lss.,
1904, vol. xlvii. — Felix, J., Die Anthozoen der Gosan Schichten in den Ostalpen. Palaeontographica,
1903, vol. xlix. Nuinerous other papers, especially in Zeitsch. deutsch, geol. Gesellsch. — Caimthers,
R. G., The primary Septal Plan of the Rugosa. Ann. and Mag. Nat. Hist. 1906, ser. 7, vol. xviii. —
Gordon, O. E., Studies on early Stages in Paleozoic corals. Am. Jour. Sei., 1906, vol. xxi. — Bnrwn,
T. 0., Studies on the Morphology and Development of certain Rugose Corals. Ann. N.Y. Acad. Sei.,
1909, vol. xix.

76

COELENTERATA— CNIDARIA

PHYLÜM II

of lime, which are developed in great quantities and remain detached in the
soft parts (many .Alcijonaria). In a number of forms (Corallium, Mopsea,
Tubipora) the spicules are firmly cemented together hy means of a calcareous
or horny connective substance, in such a manner as to form tubes (Tubipora),
or, when the secretion takes place chiefly at the base, a sclerobase, or axis.
Surrounding the axis is the soft coenosarc in which the polyps of the colony
are embedded (Fig. 96). In some cases the sclerobase is composed entirely of
horny matter without admixture of calcareous secretions. In the so-called
"stone corals" (Fig. 97) a consistent calcareous skeleton is formed by the
oiiter surface of the ectoderm. At the base of the polyp between each pair
of mesenteries, the infolded ectoderm secretes small, round, cgi^al or irregulär
calcareous bodies (sderites) ; these are opposed against one another in radial
directions, and as others are successively laid down on top of them, upright

Corallium rubrum Lam. (after Lacaze-Duthiers).
Brauch of red coral of commerce laid open along the axis,
and showing three polyps in section embedded in fleshy
coenosarc.

Fig. 97.

Astroides calycularis (Lamx.). Mediterran ean
(alter Lacaze-Duthiers). Enlarged longitudinal
section of polyp with calcareous skeleton. te,
Tentacles ; oe, Oesophagus ; me, Mesentery ; loc,
Mesenteric pouches ; coe, Coenosarc ; spt, Septum ;
col, Columella.

partitions or septa are built up. Early in development also, after fixation of
the larva, the basal plate becomes calcified, owing to the secretion by the outer
surface of the ectoderm of numerous minute calcareous granules (calicoblasts).
The septa, however, grow considerably above the base, and become lodged in
the vertical interspaces between the mesenteries. In the same manner, within
the soft body-wall, a calcareous secretion may take place, binding the outer
borders of the septa together, and known as the wall or theca. Both septa and
theca are composed of minute, densely crowded calcareous bodies, in which
delicate calcareous fibres may be seen radiating in all directions from a central
dark space. And since all the calcareous bodies forming the septa have a
radial disposition, the calcification-centres as seen in transverse sections form
a dark, mostly interrupted and occasionally jagged median line, from which
bundles of minute fibres radiate outward in all directions. Similar calcification-
centres may also be found in the theca. Sometimes the median dark line is
uninterrupted and divides the septum into two separate lamellae.

i.

ANTHOZOA

77

The interstices between the sclerites forming the septa are either com-
pletely filled with carbonate of lime (Aporosa), or there remain larger or
smaller porous Spaces (Ferforata) ; in many cases, in fact, the septa are
represented by a loose network of sclerites piled up vertically, or merely by
vertically directed spines.

The number of septa and of tentacles is either equal to the number of
pairs of mesenteries (when only entocoelic septa are present), or double that
of the pairs of mesenteries (when both exocoelic and entocoelic septa and
tentacles are present), and is somewhat uniform throughout species, genera
and higher groups. The number, width and mode of formation of the
septa furnish important systematic characters. As the locus of the origin of
the septa succeeding the primaries may conform to one of several plans, this
character is used in determining the major groups. The upper edges of the
septa are sometimes smooth, sometimes
serrated or granulated ; and they extend
from the central depression to or through
the walls of the theca, either obliquely or
in a curved line. This open, central depres-
sion, formed by the superior edges of the
septa, is known as the calice or calyx.

The sides of the septa are rarely smooth,
but are commoniy granulated or furnished
with rows of small prominences ; occasion-
ally they are provided with well-marked
vertical cross-bars (carinae). When the
projections on the sides of the septa are
in the form of conical or cylindrical trans-
verse bars, they are termed synapticulae.
Frequently the synapticulae of two adjacent
septa become joined together ; sometimes
whole rows of them are fused together
to form perpendicular bars, thus greatly
strengthening the septal framework. In
some corals (athecalia) the development of
synapticulae is such as to render an outer
wall superfluous. With the upward growth of the polyp, the theca gradually
becomes elevated, and its lower portions, as their occupation by the soft parts
ceases, may be partitioned ofF by numerous horizontal or oblique calcareous
plates which bridge over the interseptal Spaces. These structures are known as
dissepiments and tabulae. The tabulae are often nothing but highly developed
dissepiments, being distinguished from the latter merely by the fact that they
extend across between the septa at the same level; sometimes they are
perfectly horizontal, sometimes they are arched or funnel-shaped (Fig. 98),
and sometimes incomplete. Dissepiments and tabulae are most strongly
developed in cylindrical forms, and frequently fill the included space within
the theca with a vesicular or cellular tissue.

When a number or when all of the septa are produced as far as the centre
of the calice, their inner edges may become twisted so as to form an axial
structure, known as a pseiidocolmnella. Sometimes, however, a true columella
is present ; this may be either a compact, styliform or foliaceous structure, or

Lithostrotion
martini B. and H.
Longitudinal sec-
tion showing
tabulae.

Fig. 99.

CaryophylUa cyathus Sol.
Corallum split open longi-
tudinally ; true columella
in the centre, surrounded
by a cycle of pali.

18 COELENTERATA— CNIDARIA phylum ii

may be composed of a bündle of styliform or twisted rods (Fig. 99), or of thin
lamellae. It extends from the floor of the visceral Chamber to the bottoni of
the calice, into which it projects for a greater or less distance. The structures
known as pali are narrow vertical plates which are inserted between the colu-
mella and the inner ends of the septa in one or more cycles (Fig. 99).

The outer wall or theca is often formed by the secretion of a particular
ring-like fold of the ectoderm, and is constituted of distinct sclerites, having
separate calcification-centres, and connecting the outer borders of the septa
(euthecalia). In many cases the peripheral edges of the septa become thickened
and laterally fused to form a spurious theca (pseudothecalia) ; and occasionally
the dissepiments lying in a certain zone become united so as to form an inner
wall within the true theca. The epitheca is a usually smooth, sometimes corru-
gated, superficial calcareous investment, which, according to Koch, is merely a
Prolongation of the basal plate, and is secreted by the outer surface of the
ectoderm, which is reflected over the top of the corallum. The epitheca is
deposited either directly upon the septa, or upon the theca, or, when the septa
are produced outwards so as to form exothecal lamellae or ribs (costae), the
theca and epitheca are separated. Exothecal lamellae, not corresponding in
Position to the septa, are called pseudocostae or rugae.

New individuals or colonies commonly originate by sexual reproduction.
Following fertilisation and segmentation of the ova, ciliated larvae are born,
which swim about for a time, become fixed, and develop into simple polyp
individuals. Vegetative or asexual increase by two sharply defined processes,
namely, hudding (or gemmation) and ^jssiow, assumes a great importance among
Anthozoans, resulting in the production of colonies or Stocks, often of large
size and exceeding complexity of form.

New corallites are produced either within or without the calice of the
parent polyp. In extra-calicinal gemmation the buds are thrown out either
from the sides of the polyp (lateral gemmation), or are formed in the common
calcareous matrix which unites the various corallites of a colony {coenenchymal
and costal gemmation). In both cases the new corallites may diverge from one
another, being attached to the parent corallum only at the base, or they may
grow up closely opposed to the latter and to one another, so that the thecae
are in contact on all sides. In this way branched, dendroid or massive and
knob-like '("astraeiform") Compound coralla are formed. A less common
mode of increase is by hasal or stolonal gemmation. In this process the wall of
the original polyp sends out creeping prolongations (stolons) or basal expansions,
from which new corallites arise. In calicinal gemmation buds are produced
within the calice of the parent corallite, according to one or the other of the
following methods : either certain particular septa become enlarged and pro-
duced so as finally to enclose a new calicinal disk {septal gemmation) ; or tabulae
are produced upwards in the form of pockets, from which new corallites are
developed (tahular gemmation). In both septal and tabular gemmation, a portion
of the parent corallite including a part of the original wall is concerned in the
formation of buds ; while the septa or modified tabulae are converted into
portions of the new thecae, from which new septa then begin to grow inwards
towards the centre.

A peculiar kind of calicinal gemmation is that known as rejuvenescence. In
this method only one bud is formed within the parent calice, but it enlarges
aintil it completelj ßlls the latter. By the indefinite repetition of this process, a

CLASS I ANTHOZOA 79

corallum is formed, consisting of a succession of cups placed one within the other,
of which only the youngest and uppermost is occupied by the living animal.

The beginning of reproduction by fission is marked by an elongation or
distortion of the parent calice, accompanied by the contraction of the wall at
opposite points along the margin. The constriction may proceed until it
divides the oral disk into two halves; or two opposite septa may unite to form
a new theca. By this method branching, massive or " astraeiform " colonies
are produced, which do not difFer essentially from those formed by budding.
Frequently, however, individuals formed by fission become only imperfectly
separated, remaining proximally more or less closely confluent. In such cases
the calices form continuous, straight, curved or labyrinthic furrows, with more
or less clearly distinguishable centres.

The Compound corallum of a polyp stock remains practically the same as in
solitary individuals, excepting that the conditions are more complicated when
the Separation of the zooids is incomplete. Dendroid and massive colonies
frequently develop a common connective matrix or tissue (coenenchyma) which
unites the various corallites into a whole; it is secreted by the common
colonial flesh, called coenosarc, which extends as a carpet between the polyps,
The coenenchyma is sometimes dense in structure {Oculinidae), or it may consist
of a vesicular or tubulär tissue. The separate corallites are often also united
by means of the septa, which are produced over and beyond the thecae, and
fused with those of neighbouring individuals. In such cases the interseptal
loculi are almost always filled with strongly developed dissepiments. All
structures developed in the included space within the theca, with the exception
of the septa and columella, are designated coUectively as endotheca ; those lying
without the theca as exotheca.

The Anthozoa are exclusively marine forms, and predominate in shallow
water. Many of the Adiniaria, Antipatharia and Madreporaria occur also at
greater depths, ranging from 50 to 300 and sometimes to over 3000 fathoms.
The so-called reef-corals inhabit depths usually not exceeding 45 metres, and
require a temperature of the water of 20° C, or higher. Hence, existing
coral-reefs are restricted to a zone exfcending about 30" on either side of the
equator ; they are distinguished according to form as fringing reefs, barrier
reefs and atolls. While the stony corals (Porifes, Acropora, Turbinaria,
Pocillopora, numerous '^ Astraeidae" and Fungidae) and the Alcyonarians
(Heliopora) are the most important, they are not the only agents concerned in
the formation of reefs, as an active part is also played by the Hydromedusae
(Milleporidae), calcareous algae (Lithothamnium, Melobesia), mollusks, echino-
derms, bryozoans and worms. Of the ancient coral-reefs which have been
formed in nearly all of the great geological periods, those of the Cenozoic and
Mesozoic periods are composed in part of genera similar to those now living ;
while those of the Paleozoic represent genera and families that are now
principally extinct, and whose relation to living forms is often quite uncertain.

The Anthozoa are divided by Haeckel into three subclasses : Tetracoralla,
Hexacoralla and Alcyonaria or Octocoralla. Of these the two first-named groups
are by some authors collectively termed Zoantharia.

80 COELENTERATA— ANTHOZOA phylüm ii

Subclass 1. TETRAOORALLA Haeckel.^

{Zoantharia Eugosa Milne Edwards ; Fterocorallia Frech.)

Extinct, Faleozoic, simple or composite sderodermic corals, with septa arranged
according to a tetrameral System, and either Ulaterally or radially symmetrical ;
wühout coenenchyma, hut with usually strongly developed endothecal tissue in the form
of tabulae or dissepiments, and with well-marked, frequently wrinkled epithecal wall.

The Tetracoralla are especially characterised by having the septa, subse-
quent to the formation of the primaries, introduced along four lines rising
from the apex of the base of the corallum. The earlier stages of the Tetra-
coralla have recently been reinvestigated by Duerden, Carruthers and others.
Duerden concluded that the observations of Ludwig and Pourtales on the
primary hexamerism of these corals were correct. According to Carruthers,
in the developing young Tetracoralla the first stage of septal formation is for
a Single septum to stretch entirely across the calice from wall to wall. This
septum, which is called the axial septum, later breaks up to form the main
(cardinal) and the counter septum of the mature coral. In the next stage a
small septum appears on each side of the main septal end of the axial septum.
These two septa form the alar septa of the mature corallum. In the third
stage two other septa appear, one on each side of the counter septal end of the
axial System. After the formation of these six septa there is a distinct pause
in the formation of new septa and any irregularity in the disposition of the
septa is corrected. Four of the six septa are called principal, and are con-
spicuous in the later septal arrangement ; these four are the main, counter,
and alar septa. Two of the first six septa, one on each side of the end of the
counter septum, are not so prominent in subsequent development.

There is a controversy as to whether the primary septa of the Tetracoralla
are four or six in number : Duerden and Carruthers holding the number to be
six, while Brown and Gordon contend that it is four. The four principal septa
are sometimes of equal proportions, when they may be either stouter and
longer than the others (Stauria), or thinner and shorter (Omphyma) ; or they
may be of unequal proportions. Of the two principal septa which lie in the
longitudinal axis of the corallum, one (called the main or cardinal septum) is
frequently situated in a depression or furrow known as the fossula (Fig. 100);
while the other or counter septum is either normally developed, or is more or
less reduced. Occasionally the counter septum is placed in a fossula, while
the cardinal septum is normally developed ; but the two laterally disposed or
alar septa are always equal in size. The remaining septa not infrequently
exhibit a well-marked radial arrangement, in which the longer and more
strongly developed usually alternate with the shorter and less strongly
developed. New septa, according to Kunth and Dybowski, are inserted in
the foUowing order. First, a new septum is given ofF on either side of the

1 Literature : Kunth, A., Beiträge zur Kenntniss fossiler Korallen. Zeitschr, deutsch, geol.
Ges., 1869-70, vols. xxi., xxii. — Dybowski, W. N., Monographie der Zoantharia Eugosa, etc. Archiv
für Naturkunde Liv-, Est-, und Kurlands, 1874, vol. v. — Roemer, F., Lethaea Palaeozoica, 1883,
pp. 324-416. — Schlüter, dem., Anthozoen des rheinischen Mittel-Devons. Abhandl. j^reuss. geol.
Landes-Anstalt, 1889, vol. viii. — Brown, T., Studies on the Morphology and Development of certain
Rugose Corals. Ann. N.Y. Acad. Sei., 1909, vol, xix. — Faurot, L., Affinites des Tetracoralliaires
et des Hexacoralliaires. Annales de Paleont., 1909, vol. iv.

i...

TETRACORALLA

81

Cardinal septum (Fig. 100, Ä), and takes up a position parallel with the alar
septum. This leaves an intermediate space between the cardinal and the
newly formed septa, which becomes filled, however, by the repeated insertion
of new septa one above the other in the same manner as the first ; and hence
they diverge from the cardinal septum, as they grow upward, in a pinnate
fashion. Likewise the two counter quadrants lying between the alar and
counter septa become occupied by lamellae which are given ofF from the alar
septa, and gradually arrange theraselves parallel with the counter septum.
The mode of growth in the Tetracoralla will be readily understood on inspect-
ing the surface of those specimens, the septa of which are visible on« the
exterior, or where the wall is readily removed by corrosion or polishing. One
may then note three distinct lines extending from the calicinal margin to the
base ; these mark the cardinal and the two alar septa, from which the other
pinnately branching septa are directed obliquely upward (Fig. 101). The
Order in which the septa are given
ofF in the four quadrants, according
to Kunth, is indicated by the
numerals in Fig. 100.

Many of the Tetracoralla multiply
only by sexual reproduction, and occur
only as single individuals ; asexual
reproduction takes place usually by
calicinal, more rarely by lateral gem-
mation, and results in dendroid or
massive colonies. '

Dissepiments are generally abund-
antly developed between the septa,
which latter are compact, and the
Upper edges of which are either
smooth or serrated. Sometimes the
dissepiments fiU the whole interior
with a vesicular tissue, and the
central visceral cavity is frequently
entirely partitioned off by horizontal,

inclined or funnel-shaped tabulae. The wall is usually composed of the
thickened and fused septal edges; sometimes it is invested with epitheca
and furnished with vertical rugae or root-like processes. A true coenenchyma
is absent. In a few genera the calice is provided with a lid or operculum,
which may be composed of one (Calceola) or of several plates (Goniophyllum),

With the exception of a few genera the systematic position of which is
uncertain, all the typical Tetracoralla are confined to the Paleozoic rocks.

Family 1. Oyathaxonidae Milne Edwards and Haime.

Turbinate or horn-shaped simple coralla. Septa with regulär radial arrange-
ment. Tabulae and dissepiments absent. Silurian to Permian.

Cyathaxonia Mich.. (Fig. 102). Acutely pointed, conical. Cardinal septum
in fossula. Septa numerous, extending inward as far as the strongly developed
styliform and considerably elevated columella. Carboniferous limestone ;
Belgium and England.

VOL. I 0

Fig. 100.

Menophyllum tenuimar-
ginatum B. and H. Car-
boniferous Limestone ;
Tournay, Belgium. 2/j.
h, Cardinal septum ; g,
Counter septum ; s, Alar
septa.

Streptelasma profundum
(Owen). Ordovician ; Cin-
cinnati, Ohio. Natural
size.

82

COELENTEEATA— ANTHOZOA

PHYLUM II

Duncanella Nich. Corallum top-shaped. Septa nearly all of uniform
length and size, forming a spurious columella in centre of the deep calice,
exsert at the base. Silurian ; North America. D, horealis Nich.

Fetraia Münst. (Fig. 103). Turbinate or conical. Septa short, reaching
to the centre only at the base of the very deep calice. Columella absent.
Ordovician to Carboniferous.

Folycoelia King (Fig. 104). Horn-shaped. Calice very deep; four prin-
cipal septa reach nearly to its centre, between which in each quadrant are
five shorter septa. Zechstein.

Kanophyllum Dyb. Ordovician and Silurian.

Fig. 102.

Cyathaxonia
cornuMich. Car-
boniferous Lime-
stone ; Tournay,
Belgiiim. Cor-
allum with
fractured theca,
showing open in-
terseptal loculi.

2/1.

Fig. 103.

Petraia radiata
Münster. Devonian;
Enkeberg, near
Brilon, i/i. a, Cor-
allum viewed from
the apex; b, Trans-
verse section below
the middle.

Fig. 104.

Folycoelia pro-
funda (Germ.).
Zech stein;
Gera. Vi(after
Roemer).

Fig. 105.

Falaeocydus porpita
(Linn.). Silurian;
Gotland. a, Top
View of calice ; h,
Profile, i/i-

Fig. 106.

Microcyclus dis-
cus Meek and
Worth. Hamil-
ton (Devonian) ;
North America.
i/j. a, Corallum
from below ;
b, from . above
(after Nicholson).

. Family 2. Palaeocyclidae Dybowski.

Coralla simple, discoidal or howl-shaped. Septa numerous, stout, approaching
radial symmetry in disposition. Tabulae and dissepiments waiiting.

Palaeocyclus E. and H. (Fig. 105). Discoidal to depressed top-shaped,
with epitheca. Septa numerous, radially disposed, the larger ones reaching
to the centre. Silurian. Type, P. porpita (Linn.).

Combophyllum, Baryphyllum E. and H. Devonian.

Hadrophyllum E. and H. Cushion-shaped, with epitheca. Calice with
three septal fossula, that of the cardinal septum being the largest, Devonian;
Eifel and North America.

Microcyclus Meek and Worth. (Fig. 106). Like the preceding, but with
only one septal fossula. Devonian ; North America.

Family 3. Zaphrentidae Milne Edwards and Haime.

turbinate, conical or cylindrical ; septa numerous, exhihiting

Theca generally formed hy fusion of

s not very ahundant in inter-

Coralla simple,
distinct bilateral symmetry in arrangement.
septal ends. Tabulae completely
se

Streptelasma Hall (Fig. 107). Turbinate, often curved. Septa numerous

rBCLASS I

TETRACORALLA

83

10-130), alternately long and short; the free edges of the longer septa are
'isted together in the centre to form a pseudo-columella. Tabulae few er
)sent. Position of the cardinal septum is recognisable on the exterior by the
System of pinnately diverging costal ridges. Common in Ordovician and
Silurian. S. pro- s a k
fundmn (Owen),
the type species,
has often been
confused with S.
corniculum and
various species of
Zaphrentis.

Zaphrentis Raf .
(Caninia Mich.
pars) (Figs. 108-
10). Simple, tur-
binate or sub-
cylindrical, fre-
quently elongated.
Calice deep, with

circular margin. Septa numerous, reaching to the centre ; cardinal septum in a
deep fossula. Tabulae numerous; somewhat irregulär, and passing from side to
side of the visceral chamber ; dissepiments sparingly developed in outer zone
of corallum. 50 to 60 species known, ranging from Silurian to Carboniferous.
Maximum development in Carboniferous.

Amplexus Sow. Simple, sub-cylindrical or elongated turbinate. Calice

Streptelasma profundum (Owen). Cincinnatian Group

(Ordovician); Cincinnati, Ohio.

Side view.

B, Transverse section, C, Longitudinal section. (h,
Cardinal septum ; g, counter septum ; s, alar septum.)

Fig. 108.

Zaphrentis cornlcxda
Lesueur. Devonian lime-
stone ; Ohio.

Fig. 109.

Zaphrentis cornucopiae
Mich. Calice enlarged.
Carboniferous Limestone ;
Tournay, Belgium.

Fig. 110.

Zaphrentis enniskilleni Nich. Carboniferous Lime-
stone ; A, B, Transverse sections through respectively
Upper and lower portions of calice. (', A long and two
Short septa united at the ends to form the wall. D,
Longitudinal section showing tabulae (after Nicholson).

shallow, usually with septal fossulae. Septa moderately numerous, short,
never produced to centre. Tabulae highly developed, horizontal. Ordovician
to Lower Carboniferous. Type, A. coralloides Sow.

Aulacophyllum E. and H. Turbinate. Septa numerous, extending to

84

COELENTERATA— ANTHOZOA

PHYLUM II

centre. Cardinal septum in deep fossula ; adjacent septa pinnately developed.
Ordovician to Devonian.

Menophyllum E. and H. (Fig. 100). Turbinate. Cardinal septum in
largest of three fossulae. Lower Carboniferous limestone.

Lophophyllum E. and H. Carboniferous limestone. Anisophyllum E. and
H. Ordovician to Devonian. Pycnophyllum Lindstr. Ordovician and Silurian.
Apasmophyllum Eoem. Metriophyllum E. and H. Thamnophyllum Penecke.
Devonian. Penfaphyllum de Koninck. Carboniferous.

Family 4. Cyathophyllidae Milne Edwards and Haime.

Simple or composite coralla. Septa numerous, radially arranged ; the four
piincipal septa rarely distinguished by greater or smaller size. Tabulae and
vesicular tissue (dissepiments) abundant.

Cyathophyllum Goldf. (Figs. 111-13). Extremely variable in form,
sometimes simple, turbinate or sub-cylindrical ; sometimes giving rise to
bushy, fasciculate or astraeiform colonies, where reproduction takes place by

Fig. 111.

Cyathophyllum caespitosum Goldf.
Devonian ; Gerolstein, Eifel. Natural
size.

Fig. 112.

Cyathophyllum hexagonum Goldf. Devonian
stein, Eifel. Natural size.

Gerol-

calicinal or lateral gemmation. Septa very numerous, strictly radial in
arrangement, and of ten alternately long and short ; the longer septa extend-
ing to the centre. Visceral Chamber filled with numerous imperfectly
developed tabulae ; vesicular dissepiments highly developed in peripheral
portion. Nearly 100 species known, ranging from Ordovician to the Lower
Carboniferous. Maximxum development in Devonian.

Campophyllum E. and H. (Fig. 1 1 4). Like the preceding, but septa not
extending to the centre. Devonian and Carboniferous Limestone.

Heliophyllum Hall. Usually simple and turbinate, more rarely forming
dendroid colonies. Septa numerous, extending to the centre, and thickened
on their sides by conspicuous vertical ridges (" carinae "). Devonian.

Diphyphyllum Lonsd. (Fig. 115). Ordovician to Carboniferous. Pholido-

lum Lindstr. Ordovician and Silurian; Eridophyllum E. and H. Silurian

FBCLASS I

TETEACORALLA

85

I

^^pd Devoniaii. Crepidophyllum Nich. Craspedophyllum Dybowski. Devonian.
^Ktoninckophyllum Nich. Chonaxis E, and H. Carboniferous. Clisiophylhm
^^Pana. Silurian to Carboniferous.
^H Oinphyma llsiL (Fig. 116). Corallum simple, conical or turbinate ; theca

I

Fig. 113.

Cyathophyllum heteropliyllum E. and H. Middle De-
vonian ; Gerolstein, Eifel. A, Transverse ; B, Longi-
tudinal section (after Nicholson).

Fig. 114. ,

Campophyllum com-
pressum Ludw. Car-
boniferous Limestone ;
Hausdorf, Silesia. a,
Longitudinal ; b, Trans-
verse section.

Fig. 115.

Diphyphyllum con-
cinnum Lonsd. Car-
boniferous Lime-
stone ; Kamensk,
Ural.

with root-like processes. Septa numerous ; the four principal septa in shallow
fossulae. Surface marked with pinnafcely branching Striae. Tabulae numerous.
Silurian.

Chonophyllum E. and H. Silurian and Devonian.

Fig. 116.

Oinphyma subturbinata B. and H. Silurian limestone
Gotland, Svveden. a, Side view ; h, Calice from above.

Fig. 117.

Lithostrotion
martini E. and H.
Lower Carbonifer-
ous ; Hausdorf,
Silesia. Sections
of individual
corallite (after
Kunth).

Ptychophyllum E. and H. Simple and turbinate, or composite. Each
stock is composed of funnel-shaped, invaginated layers, representing calicinal
buds, the marginal lips of which are more or less reflected outwards. Septa
numerous and strongly twisted in the centre to form a pseudo-columella ; their

86

COELENTERATA— ANTHOZOA

PHYLUM II

peripheral edges are thickened and are fused with one another so as to form a
wall. Silurian (P. patellatum Schlot, sp.) and Devonian.

Cyclophyllum Duncan and Thom. Simple, cylindro-conical. Septa numer-
ous, the longer ones forming a thick pseudo-columella with enclosed spongy

tissue.

Aulophyllum E. and H. ; Asjpidophyllum, Bho-
dophyllum Nich. and Thoms., etc. Carboniferous.
Lithostrotion Llwyd (Stylaxis M'Coy ; Fetalaxis
E. and H.) (Fig. 117). Fasciculate or astraei-
form Stocks composed of prismatic or cylindrical
corallites. Septa numerous, alternately long
and short. Styliform columella in the centre.
Abundant in Carboniferous limestone.

Fig. 118.

Lonsdaleia floriformis Lonsd. Car-
boniferons Limestone ; Kildare, Ire-
land. i/i. a, Two cylindrical corallites,
partially splitopen ; h, Twohexagonal
calices, seen from above.

Fig. 119.

Phillipsastrea hennaM (Lonsdale). Devonian limestone ; Ebersdorf,
Silesia. a, Upper surface ; h, Transverse section. Natural size.

Lonsdaleia M'Coy (Fig. 118). Fasciculate or astraeiform, composite
coralla. Septa well developed ; columella large, composed of vertically rolled
lamellae. Central tabulate area bounded by an interior dissepimental wall,
between which and the theca vesicular endotheca is abundantly developed.
Common in Carboniferous rocks.

Strombodes Schweigg. Astraeiform Stocks composed of small prismatic
corallites. Septa extremely numerous, very slender, extending to the centre.

Fig. 120.

Stauria astraeiformis E. and H. Silurian ; Gotland, Sweden. A, Transverse section parallel to upper
aurface. B, Enlarged transversa section of individual corallite. C, Several calices from above. Natural size
(after Nicholson).

Theca imperfectly developed. Visceral Chamber filled with infundibuliform
tabulae and vesicular tissue. Silurian (S. typus M'Coy sp.) and Devonian.

Fachyphyllum, Spongophyllum E. and H. Silurian and Devonian.

Acervularia Schweigg. Astraeiform or bushy colonies. Septa stout and

SUBCLASS I

TETRACORALLA

87

(lumerous. An iiiterior wall is present ; tabulae are developed in the central
;irea, while the peripheral zone is filled with vesicular tissue, Silurian (A.
(Dianas Linn. sp.) and Devonian.

PhiUipsastrea d'Orbigny (Fig. 119). Astraeiform colonies, with indi-
vidual corallites united by confluent septa, which are produced beyond the
theca, and obscure the same. Interseptal loculi filled with vesicular endotheca.
Devonian and Carboniferous. Type, P. hennahi (Lonsd.).

Stauria E. and H. (Fig. 120). Astraeiform or bushy composite coralla.
Septa well developed; the four principal septa characterised by larger size, and
forming a complete cross in the centre of each corallite. Silurian (Wenlock).

Columnaria Goldf. (Favistella Hall). Astraeiform Stocks, composed of
long, polygonal, thick-walled corallites. Septa radially arranged in two cycles,
alternately long and short, barely reaching the centre. Tabulae horizontal,
disposed at regulär intervals apart, and stretching across the entire visceral
Chamber. Dissepiments imperfectly developed or absent. Ordovician to
Devonian.

Ileterophyllia M'Coy. Carboniferous. Batiersbyia E. and H. Devonian.

Family 5. Oystiphyllidae Milne Edwards and Hainie.

Usually simple coralla. Septa very thin ; interseptal loculi filled with vesicular
endotheca or compact stereoplasma. Tabulae absent ; central area of visceral Chamber
either completely filled with vesi-
cular tissue or stereoplasma, or
containing the same only in the
lower portions of Chamber. Cal-
careous operculum sometim,es
present.

Cystiphyllum Lonsd. (Figs.
121, 122). Simple, very rarely
forming bushy colonies. Calice
deep; the entire visceral Cham-
ber filled with vesicular tissue,
which, as a rule, wholly
obliterates the numerous radi-
ally directed septa. Silurian
and Devonian.

Strephodes M'Coy (Fig.
123). Usually simple coralla.
Septa well developed, alter-
nately long and short, some-
times forming a pseudo-
columella. Silurian to Carbo-
niferous.

Goniophyllum E. and H.
(Fig. 124). Corallum simple, in the form of a four-sided pyramid, and
covered with thick epithecal tissue. Calice deep ; septa numerous, thick
and very short. Entire visceral Chamber filled with vesicular and stereo-
plasmic endotheca. Operculum composed of four plates symmetrically
paired. Silurian.

Fig. 121.

Fig. 122.

Cystiphyllum cylindricum

Lonsd. Silurian ; Iron Bridge,

Cystiphyllum vesiculosum England. A, B, Transverse

Goldf. Devonian ; Eifel. and longitudinal sections (after

Natural size. Nicholson).

88

COELENTERATA—ANTHOZOA

PHYLUM II

Bhizophyllum Lindst. Corallum simple, pyramidal or hemispherical,
flattened on one side ; external surface corrugated, and sending ofF hollow,
root-like epithecal processes. Calice marked with septal Striae ; internal
structure consisting of vesicular tissue and stereoplasma. Operculum in form
of semicircular plate ; inner surface traversed by median ridge and fainter,
granulated, parallel elevations. Silurian.

Calceola Lam. (Fig. 125). Corallum simple, semi-turbinate, or slipper-shaped,

Fio. 123.

Strephodes mnrchisoni Lonsd.
Showing strongly developed
dissepiments and tabulae.

Fk.. 124.

Goniophyllum pyramidale
(His.). Silurian ; Gotland.

A , Specimen with operculum.

B, Calice seen from above.
Natural size (after Lind-
ström).

Calceola
Devonian ;

Fig. 125.

sandalina Lam.
Eifel. Natural

with one side flat and triangulär. Calice very deep, extending nearly to apex,
and marked internally with fine septal Striae. Cardinal septum placed in the
centre of the vaulted side, counter septum in middle of flattened side, and alar
septa at the angles. Internal structure composed of fine vesicular tissue and
Stereoplasma. Operculum semicircular, very thick, under surface marked with
prominent median and fainter lateral septal ridges. C. sandalina Lam. Very
common in Middle Devonian of Europe, rare in Carboniferous Limestone of
Belgium.

Range and Distribution of the Tetracoralla.

The typical Tetracoralla are confined to the Paleozoic rocks. They are
unknown in the Cambrian, and make their first appearance in the Ordovician,
where they are sparsely represented in North America and in Europe. Here
the most abundant genus is Streptelasma, and next in order of importance are
Cyathophyllum, Ftychophyllum and Columnaria. The maximum development
falls in the Silurian, which contains the largest number of genera and species.
There are limestones found on the Islands of Gotland and Dago (Esthonia), as
well as at Dudley, Shropshire, at Lockport, New York and other places in
North America, which are made up of ancient coral-reef s. The principal agents
concerned in the formation of these reefs were Cyathophyllum, Heliophyllum,
Omphyma, Ptychophyllum, Sfromhodes, Acervularia, Stauria, Aulacophyllum, Cysti-
phyllum, etc., of the Tetracoralla, besides numerous Tabulata, Octocoralla,

süBCLÄSS II HEXACORALLA 89

Bryozoa, and Echinoderms. The Tetracoralla are not less conspicuous in the
Devonian, especially in the Middle and Upper Devonian of the Eifel district,
Westphalia, Nassau, Harz, Boulogne, England, and North America. ■- Particu-
larly abundant here are the genera Cyathophyllum, Campophyllum, Zaphrentis,
Cystiphyllum, Phülipsasti'ea, Calceola, etc. Zaphrentis, Amplexus, Lithostrotion,
Lonsdaleia, Cyclophyllum^ etc., predominate in the Carboniferous Limestone of
Belgium, England, Ireland, and North America ; while in the Zechstein the
solitary genus known is Polycoelia. On the other band, the Permo-Carboni-
ferous rocks of the Salt Range in India and of the island of Timor contain the
genera Zaphrentis, Amplexus, Clisiophyllum, and Lonsdaleia. According to Frech,
the genera Gigantostylis, Piriacophyllum, and Coccophyllum, occurring in the Alpine
Trias, belong to the Tetracoralla ; and to this group also have been assigned
Holocystis E. and H., from the Cretaceous, and the recent genera Haplophyllum
Pourtales, and Guynia Duncan. A number of Paleozoic Tetracoralla, such as
Baitersbyia, Heterophyllia, and Stauria, are referred by Duncan and Nicholson to
the Hexacoralla (^' Astraeidae").

Subclass 2. HEXACORALLA Haeckel.

(Zoantharia Blainville ; Hexadinia and Polyadinia Ehrenberg.)

Simple or composite polyps, with radial mesenferies arising in cydes of six, iwelve,
or multiples of six (more rarely pentameral, septameral or odameral) ; frequently with
calcareous corallum, hut sometimes fleshy or with hoo'ny axis.

To the Hexacoralla belong the calcareous reef-building and deep-sea corals
(Madreporaria) of the present day, the fleshy sea-anemones (Adiniaria), and
those forms characterised by the secretion of a horny axis (Antipatharia). Of
these three Orders, only the Madreporaria are known in a fossil State. These
forms are distinguished from the Tetracoralla by the hexameral System and
radial arrangement of mesenteries and septa ; and from the Octocoralla, in
addition to the above-named characters, by their simple tentacles.

According to Duerden, either before or shortly after extrusion of the
larva, the six primary pairs of mesenteries (protocnemes), constituting the first
cycle, make their appearance. The organs arise in bilateral pairs, in a
regulär and well-defined order, which is uniform for all the species yet
studied. The first two or three pairs arise around the oral extremity of the
larva, while the others first appear at varying distances down the wall. The
protocnemic sequence is represented by the Roman numerals in Fig. 126, and
agrees with that established for the greater number of actinians. The first
four pairs very early unite with the stomodaeum, but the fifth and sixth
pairs remain free or incomplete for a lengthened period, suggesting a diflferent
phylogenetic significance from the others.

The six pairs of second cycle mesenteries (metacnemes) arise after fixation,
but in a manner altogether difFerent from that followed by the first cycle.
They appear on the polypal wall in unilateral pairs or couples within the
six primary exocoeles, and in a succession which is from the dorsal to the
ventral side of the polyp, not the whole cycle at a time. For a long time,
as shown in Fig. 127, the six pairs present a diff"erence in size, corresponding
with their dorso-ventral or antero-posterior order of appearance.

90

COELENTERATA— ANTHOZOA

PHYLÜM II

The twelve pairs of third cycle mesenteiies are found to develop in a
succession fwhich is altogether unexpected. They follow the same dorso-
ventral order as the second cycle pairs, but in two series. A primary series
of six pairs — one pair within each sextant — appears within the exocoele on
the dorsal aspect of each of the second cycle mesenteries, one pair following
upon another, and then another series of six pairs arises on the ventral
aspect of the second cycle mesenteries in the same order (Fig. 128). In the
later stages of development the regularity of the mesenterial succession is not

IZ

IE

w

JS.

m

m

Fig. 126.

Growth stages of coral polyp in Maeandra (" Manicina") areolata. Diagrammatic flgures showing order of
appearance of the six primary pairs of mesenteries. In a only two pairs of mesenteries are present, of which one
pair (i) is imited with the stomodaeum, while the other (ii) is free ; in b the second pair of mesenteries has become
complete, and a third pair (iii) has appeared on tlie ventral border ; in c another pair (iv) is found within the dorsal
Chamber ; in d the first four pairs of mesenteries to arise have all become complete, and the fifth and sixth
pairs (v, vi) have appeared, but remain incomplete for a long period, the secondary mesenteries appearing in
the meantime (cf. Fig. 127). The actual stages given are taken from Maeandra areolata, but a like sequence is
presented by other species whose development has been foUowed (after Duerden).

always maintained ; one region may be somewhat in advance of, or may lag
behind its normal development.

The sequence thus outlined in the briefest manner is sufficient to show
that the development of the mesenteries in coral polyps is bilateral, and
takes place in stages from one extremity to the other. The radial symmetry,
characteristic of the adult polyp, is thus derived from primitively bilateral
Organs, which appear in an antero-posterior succession. Moreover, each cycle
represents a separate period of development, as compared with the successive
growth in one direction of ordinary segmented animals.

The first two cycles of tentacles (prototentacles) generally arise a cycle at
a time, either simultaneously or one following the other. The later tentacles

SlinCLASS II

HEXACORALLA

91

are developed in an order in correlation with that of the mesenteries, some-
times entocoelic and exocoelic members appearing together. In the process
of growth the exocoelic members are always relegated to the outermost
cycles, in a manner first established by Lacaze-Duthiers for actinians ; only
the entocoelic tentacles are of any ordinary value, Siderastrea radians (Pallas)
is exceptional in that the exocoelic tentacles appear in advance of the
entocoelic.

Fig. 127.

Growth stages of larval polyps in Siderastrea radians. Three diagramrnatic figures illustrating the manner
of appearance of the six mesenteries (A-C) constituting the second cycle. The mesenteries arise in unilateral
pairs witliiii corresponding exocoelie Chambers on each side of the polyp. At first (a) a ])air appears within the
dorso-lateral exocoele on each side ; shortly after (li) a similar pair arises within each middle exocoele ; then (c)
a pair within each ventro-lateral exocoele. For a long time the pairs retain a diö'erence in size, corresponding
with their order of appearance (after Duerden).

The skeleton never appears until after fixation of the larva. It makes its
first appearance in the form of minute plates or granules, as an ectoplastic pro-
duct of the ectodermal cells (calicoblasts) of the base. A flat, circular, basal
plate is formed by the union of these, and may later become produced upward
at the edge as the epitheca, while from its inner or polypal surface the septa
begin to appear as vertical upgrowths formed within invaginations of the
basal disk of the polyp. The skeletal cup first formed is known as the
prototheca.

92

COEliENTERATA— ANTHOZOA

PHYLUM II

Like the tentacles, the first two cycles of septa (protosepta) may appear
simultaneously, or the cycle of six entosepta may arise in advance of the
cycle of six exosepta. The order of appearance of the later cycles is not yet
thoroughly understood, the relative sizes in the mature corallum by no means
indicating the actual order of developnient. As in the case of the mesenteries,
the radial plan of the mature septa is derived from structures which appear
bilaterally, in a more or less definite dorso - ventral or antero - posterior

Fig. 128.

Three stages in the development of the twelve pairs of third-cycle mesenteries. All the six pairs of primary
mesenteries are now complete, and the second-cycle pairs are all equal, but free from the stoniodaevnn. In a a
pair of third-cycle mesenteries (iii) has appeared on each side, within the exocoele next the dorsal directives ; in
b a corresponding pair occurs within the dorsal of the two exocoeles of all the six Systems, the order being from
the dorsal to the ventral aspect ; in c another series of six pairs is beginning, situated within the ventral of the
two exocoeles in each system. Growth in the dorsai region is in advance of that in the ventral (after Duerden).

succession. Furthermore, as in the case of the tentacles, the exosepta remain
exosepta throughout the course of their development, always constituting the
outermost cycle. The entosepta beyond the primary six follow the same
succession of growth as the mesenteries, so that the order assigned the
secondary and tertiary mesenteries in Fig. 129 will also hold for the septa.
Eeproduction takes place either sexually, when separate individuals are pro-
duced ; or asexually, by means of lateral or basal gemmation ; or by fission.
In composite coralla, the individual corallites are sometimes united by a

suBCLASs II HEXACORALLA 93

common coenenchyma. Endothecal structures are frequently present in the
form of synapticulae, dissepiraents, and tabulae.

The Order of stone corals or Madreporaria {Zoantharia sclerodermata) was
divided by Milne Edwards and Haime into five suborders : Eugosa, Tahulata,
Tuhulosa, Perforata, and Aporosa. Of these, the Eugosa have been elevated by
Haeckel into a separate subclass under the name of Tetracoralla. The groups
Aporosa and Perforata are called Hexacoralla ; while the afiinities of the

Fig. 129.

Diagram showing the Order of appearance of all the mesenteries in a polyp having three cycles. The Roman
numerals represent the cycles to which the mesenteries belong, and the smaller Arabic numerals indicate the
Order in which the mesentery appeared within its cycle. The regularity here indicated Is constant for the
primary and secondary cycles, but departure may be encountered in the third cycle (after Duerden).

Tahulata (with which the Tuhulosa are now generally included) are still
unsatisfactorily determined. The group is certainly composed of a varied
assemblage of forms, some of which have been assigned to the Hexacoralla,
some to the Octocoralla, and some to the Hydrozoa and Bryozoa.

Order 1. MADREPORARIA Milne Edwards. ^

(Zoantharia sclerodermata E. and H.)

Eadially symmetrical sclerodermous corals with typically hexameral (rarely
pentameral, heptameral, or octameral) arrangement of septa.

^ Literature : Pratz, E. , Ueber die verwandtschaftliche Beziehungen einiger Korallengattungeu,
etc. Palaeontogr. 1882, vol. xxix. — Frech, F., Die Korallenfauna der Nordalpinen Trias. Palaeontogr.
1890, vol. xxxvii. — British Museum Cat. of Madreporarian Corals, vol. i. by George Brook, 1893,
vols. ii.-vi. by //. M. Bernard, 1896-1906.— Volz, W., Die Korallen der Schichten von St.
Cassian in Süd-Tirol. Palaeontogr. 1896, vol. xliii. Felix, J., Anthozoen der Gosauschichten
in den Ostalpen. Palaeontogr. 1903, vol. xlix. — Duerden, J. E., The Coral Siderastrea, etc.
Carnegie Inst. Wash., 1903, Pub. No. 20.— Lang, W. D., Growth-Stages in the Coral Genus Para-
smilia. Proc. Zool. Soc. London, 1909, pt. ii. — Paroim, G. F., La Fauna coralligena del Cretaceo
dei Monti d' Ocre nell' Abruzzo. Mem. Com. Geol. Ital., 1909, vol. v. (See also ante, p. 74).

94

COELENTERATA— ANTHOZOA

PHYLÜM II

Suborder 1. APOROSA Milne Edwards and Haime.

Septa and theca compact; interseptal loculi usually partitioned off hy dissepi-
ments or synapticulae, more rarely hy tabulae, seldom empty throughout. Theca

either independenÜy secreted, or formed hy fusion of the septal

or ahsent.

Family 1. Turbinolidae Milne Edwards and Haime.

Corallum simple, very seldom composite ; septa numerous, long, and with entire
margins. Interseptal loculi empty throughout. Columella usually, pali often present.
Theca comi

The Turhinolidae begin in the Jurassic, and are especially abundant in the
Tertiary and at the present day. Sexual reproduction prevails,
although a few forms multiply by gemmation ; the buds, how-
ever, become separated from the parent animal at an early
period.

Turhinolia Lam. (Fig. 130). Corallum free, conical, with
circular calice. Septa produced beyond the theca. Styliform

Fig. 130.

Turhinolia bowei--
lanJci E. and H.
Eocene ; Highgate,
England. 6/^.

Fig. 131.

Ceratotroclius duodecimocostatus (Goldf.). Miocene

Baden, near Vienna. Natural size.

Fig. 132.

Fläbelhim roissyanum E.
and H. Miocene; Baden,
near Vienna. Natural size.

columella present. Tertiary and Recent ; common in Calcaire Grossier of
the Paris Basin, and Eocene of England and southern United States.

Sphenotrochus E. and H. Free, cuneiform with elongated calice; colum-
ella lamellar. Cretaceous to Recent. Type, S. crispus (Lam.). Eocene to
Recent. Common in Calcaire Grossier of the Paris Basin, and in the Eocene
of the Gulf States.

Smilotrochus E. and H.; Stylotrochus From.; Onchotrochus Duncan. Cre-
taceous. Discotrochus E. and H. etc. Tertiary.

Ceratotrochus E. and H. (Fig. 131). Horn-shaped ; young forms attached
at the apex. Septa very numerous, produced above the theca; columella
fasciculate. Cretaceous to Recent.

Flahellum Lesson (Fig. 132). Corallum wedge-shaped, compressed, free,
or attached. Septa numerous. Wall covered with epitheca, and sometimes
furnished with spinous processes. Tertiary and Recent.

Trochocyathus E. and H. (Fig. 133). Horn-shaped, with circular calice.
Septa stout ; columella papillous and trabecular, and surrounded by several
cycles of pali. Numerous species from Lias to Recent.

;übclass II

HEXACORALLA

95

Thecocyathus E. and H. Depressed, conical, or discoidal, attached early in
life, later becoming free. Wall with thick epithecal Investment. Calice
circular, septa numerous ; columella fasciculate, and sur-
rounded by several cycles of pali. Lias, Jurassic, Cre-
taceous, and Recent.

Paracyathus, Deltocyathus E. and H. (Fig. 134).
Tertiary and Recent. Discocyathus E. and H. Jurassic.
Coenocyathus, Acanthocyathus, JBathycyathus E. and H., etc.
Tertiary and Recent.

Caryophyllia Lam. (Fig. 135). Turbinate, with broad

Fig. 133.

Fig. 134.

Trochocyathiis conulus From. Aptian ; Deltocyathus italicus E. and H. Miocene ;

Fio. 135.

Caryophyllia cyathus
Sol. Recent. Lougitudi-

Haute Marne, a, Profile, natural size ; h, Porzteich, Moravia.

Calice enlarged.

size ; b, Calice enlarged.

Profile, natural nal section, natural size
(after Milne Edwards).

base, attached. Calice, circular ; columella papillous, trabecular, and sur-
rounded by a single cycle of pali. Cretaceous to Recent.

Family 2. Oculinidae Milne Edwards and Haime.

Invariably composite coralla, increasing by lateral gemmation. Walls of corallites
thickened by a compact coenenchyma. Lower portion of visceral Chamber narrowed or
filled up by deposition of stereoplasma. Septa moderately numerous ; interseptal loculi
usually open to the base. Lias to Recent ; fossil forms not particularly numerous,

Oculina Lam. Corallites irregularly or spirally distributed over the smooth
surface of coenenchyma. Septa slightly projecting ; columella papillous,
surrounded by cycle of pali. Tertiary and Recent.

Agathelia Reuss. Like the preceding, but form-
ing tuberous or lobate colonies. Cretaceous and
Tertiary.

Synhelia E. and H. Cretaceous. Astrohelia E.
and H. Tertiary. Psammohelia, Euhelia E. and H.,
etc. Jurassic.

Ilaplohelia Reuss. Small, arborescent, with
corallites all disposed on one side of the branches.
Coenenchyma striated or granulated. Septa in
three cycles ; columella and pali present. Oligocene.

Enallhelia E. and H. (Fig. 136). Stock branch-
ing ; corallites disposed usually in alternating
sequence in two rows along the sides of branches.

Coenenchyma highly developed, striated, or granulated; columella rudi-
mentary. Jurassic. Type, E, Compressa (d'Orb.).

Fig. 136.

Enallhelia striata Quenst. Coral-
Rag ; Nattheim. a, Natural size ;
b, Calice enlarged.

96

COELENTERATA— ANTHOZOA

PHYLUM ir

Family 3. Pocilloporidae Verrill.

Composite, branchirig, lohate, or massive colonies, with small cylindrical corallites,
united hy compact coenenchyma. Sepfafew (6-24), sometimes rudimentary. Visceral
Chamber partitioned off by horizontal tabulae.

Of the two Recerit genera belonging to this family, Pocillopora and Seriato-
pora Lam., the former occurs also in the Miocene of the West Indies.

Family 4. Stylophoridae Milne Edwards and Haime.

Composüe coralla, with corallites united by vesicular or compact coenenchyma.
f^ 1, Septa well developed ; a prominent, styli-

form central columella; interseptal loculi
empty throughout. Jurassic to Eecent.
Stylophora Schweigg. (Fig. 137).
Stock branching, or depressed,
massive and tuberous. Calices

small.

Fig. 137.
Stylophora subreticulata Reuss. Miocene ; Grund, near
Vienna. a, Corallum, natural size; b, surface greatly
enlarged.

Araeacis E. and H. Eocene.

embedded in

spinous, coenenchyma.

developed, moderately

columella styliform.

Tertiary, and Recent.

Stylohelia From. Jurassic ; Europe.

abundant,

Septa well

numerous ;

Jurassic,

Family 5. Astraeidae i Milne Edwards and Haime.

Corallum composite, or more rarely simple. Theca formed by fusion of sepfal
edges. Septa numerous, usually well developed, upper edges toothed, serrated, or
lobular ; visceral Chamber partitioned off by more or less abundantly developed
dissepiments, more rarely by tabulae. Multiplication by budding or fission. Corallites
of massive colonies usually reaching considerable altitude, and united with one another
either directly by the walls or by means of septa exothecally produced (costal septa).

Very abundant from thß Trias onwards, and by far the most protean family
of all the Hexacoralla. According to the serrated or entire character of the
free septal edges, Milne Edwards and Haime divided their Astraeidae into two
subf amilies — the Astraeinae and the Eusmiliinae, the latter of which has been
elevated by Yerrill to family rank.

a. Simple coralla.

Montlivaltia Lamx. (Fig. 138). Cylindrical, conical, turbinate, or dis-
coidal, and either acutely pointed, or broadly expanded at the base. Septa
numerous, upper edges serrated. Columella absent ; epitheca thick, corrugated,

^ The family name Astraeidae is not available for use among corals, as the generic name Astraea
was applied by Bolten in 1798 to mollusks now referred to T^i7'bo and Xenophora, three years
previous to its application, in 1801, by Lamarck to corals. It is known that the Astraeidae of
Milne Edwards and Haime does not represent a natural association of corals, and, therefore, must
be dismembered and divided into a number of families. Several subdivisions have already been
proposed, but the detailed investigation of all the constituent genera has not progressed far enough
to determine their natural affinities in all cases. In view of this condition it seems better to
continue temporarily the use of the term Astraeidae until all the corals included under it have been
thoroughly studied and their systematic affinities ascertained than to propose a Substitute name
for one known to be invalid.

.SUBCLASS II

HEXACORALLA

1)7

readily becoming detached. Common in Triassic and Jurassic ; somewhat rare
in Cretaceous and Tertiary. The genus should probably be made to include
various species which have been referred to Epismilia From., and the so-called
Oppelismilia Duncan.

ß. Simple cor a IIa or composite coJonies
iiiiiUiphjing hy calicinal or marginal gem-
ination.

Sfijlophyllum Eeuss. Corallum simple,
either with or without calicinal or
marginal gemmation, or f orming massive
colonies. Septa stout, but only in-
feriorly complete, terminating above in

strong vertical spines. Dissepiments vesicular ; wall covered with epitheca.
Alpine Trias.

Stylophyllopsis Frech. Simple or imperf.ectly branching. Septa terminating
near the centre in detached vertical spines. Alpine Trias.

Fifi. 138.

MontltvdUia caryophyllata (Lamx.). Great Oolite :
Caen, Calvados. Natural size.

Stylocora exilis Reuss. Mio-
ccne ; Niederleis, Austria. a,
Corallum in natural size. h,
Calice enlarged (after Reuss).

Bushy colonies multiplying hy lateral gemmation.

Cladocora Ehrbg. Corallum composed of long
cylindrical branches, free on all sides. Calice circular ;
septa well developed ; columella papillous ; cycle of
pali present. Jurassic to Recent.

Stylocora Reuss (Fig. 139). Branches cylindrical;
septa stout, those of the first cycle with columnar
thickenings or inner edges ; columella styliform.
Cretaceous and Miocene.

Pleürocora E. and H. Cretaceous. Goniocora E.
and H. Triassic and Jurassic.

h. Composite corallites multiplying hy hasal gemmation ; huds arising from stolons

or hasal expansions.

Rhizangia E. and H. (Fig. 140). Corallites united by short, sub-cylindrical

Fig. 140.

Rhizangia michclini Reuss. Middle
Cretaceous ; Gosau Valley, Austria.
Natural size (after Reuss).

Fio, 141.

Viadang iaconferki Reuss. Miocene; Bischofs-
wart, Moravia. a, Corallum, natural size ; b,
Calice enlarged (after Reuss).

Stolons. Calices shallow, circular; columella papillous. Cretaceous and Tertiary.
Latusastrea d'Orbigny. Corallites arising from common basal expansion,
Short and strongly inclined to one side, so that the calices acquire a semi-
VOL. I H

98

COELENTERATA— ANTHOZOA

PHYLUM II

circular contour and assume the form of protruded lips. Jurassic and
Cretaceous.

Astrangia, Cryptangia, PhyUangia, Cladangia (Fig. 141), Ulangia E. and H.,
etc. Tertiary and Recent.

€. Massive coralla muUiplying hy lateral gemmation.

Orbicella Dana (Fig. 142). Cylindrical corallites united by exothecally
produced, confluent, costal septa. Columella spongy ; dissepiments numerous
between the septa both. within and exterior to the theca. Jurassic to Recent.

Plesiastraea From. Like the preceding, but with several pali in front of
all the cycles excepting the last. Tertiary and Recent.

Fig. 143.

Isastrea helianthoides (Goldf.).
Coral-Rag ; Nattheim, Swabia.
Natural size.

Fig. 145.

Favia caryophylloidcs
From. Coral-Rag; Natt-
heim. Natural size.

Fig. 142.

OrMcella conoidea (Reuss.). Mio-
cene; Enzesfeld, near Vienna. a,
Corallum, natural size ; b, Calices
enlarged.

Fig. 144.

Latomeandra seriata
Beck. Coral-Rag; Natt-
heim. Natural size (after
Becker),

Fig. 146.

CalamopJiyllia stokesi E. and H.
Coral-Rag ; Steeple Ashton, England.
Natural size.

Isastrea E. and H. (Fig. 143). Corallites prismatic, closely crowded, and
with fused walls. Calices polygonal ; columella imperf ect or absent. Trias
to Cretaceous.

Latortuandra d'Orb. (Fig. 144). Like the preceding, but with the calices
situated in short furrows. Trias to Cretaceous.

Stylastraea From. Lias ; Europe. Amphiastraea From. Upper Jurassic ;
Europe. Leptastrea, Solenastrea, Prionastrea, E. and H. etc. Tertiary and
Recent.

{■. Massive coralla multiplying hy fission.
Favia Oken (Fig. 145). Corallum massive; calices oval or distorted, and
united by confluent costal septa ; columella spongy. Jurassic to Recent.'

>UBCLASS II

HEXACORALLA

99

Goniastrea E. and H. Corallites prismatic, calices polygonal. Septa well
cleveloped ; columella spongy ; pali in front of all cycles
excepting the last. Cretaceous to Recent.

'7], Branching coralla multiplying hy fission.

Calamophyllia Blainv. (Bhabdophyllia E. and H.;
Lithodendron p. p. Mich.) (Fig. 146). Colony fasciculate
or bushy ; corallites very long, cylindrical. Wall
costate, without epitheca ; columella absent. Trias,
Jurassic and Tertiary. Especially common in Alpine
Trias. C. clathrata (Emmrich).

Thecosmilia E. and H. (Fig. 147). Colony bushy,
calices dividing by fission, and more or less free.
Epitheca corrugated, readily wearing away ; columella
absent or rudimentary. Trias to Tertiary. Accord-
ing to Frech identical with Calamophyllia. Very
common in Triassic and Jurassic.

Baryphyllia From. HymenophyUia E. and H., etc. Cretaceous.

Fig. 147.
Thecosmilia tric
(Goldf.). Coral-Rag
heim. Natural size.

hotoma
: Natt-

0. Coralla with confluent calices increasing by fission.

Leptoria E. and H. (Fig. 148). Corallum massive, composed of labyrinthic
rows of confluent corallites with fused walls. Septa closely crowded,
approaching parallelism ; columella lamellar. Jurassic to Tertiary.

Diploria E. and H. Like the preceding, but with corallites united by

produced costal septa instead
of directly by their walls.
Cretaceous to Recent.

Aspidiscus König {F\g. 149).
Corallum discoidal, circular or
elliptical, covered on lower side
with wrinkled epitheca. Cali-
cinal furrows radiating from the
centre outwards, and separated
from one another by sharply
crested ridges. In the centri-
fugally disposed corallites the
outermost septa are thickened,
Cretaceous,

Cretaceous. Symphyllia E. and

Fig. 148.
Leptoria koniiicki Reuss. Upper
Cretaceous ; Gosau Valley. Natural

Fig. 149.

Aspidiscus cristatus
König. Middle Cre-
taceous ; Batiia, Al-
geria. Natural size.

and form by their union a banded margin.

Stiboria Etall. Jurassic. Stelloria d'Orb.
H. Tertiary and Recent.

Family 6. Eusmiliidae Verrill.

Like the Astraeidae, except that upper septal edges are entire, not serrated.

a. Simple coralla.

Trochosmilia E. and H. (Fig. 150). Turbinate, base acutely pointed or
Septa numerous, extending to the centre. Without epitheca,
costae granulated. Columella absent, dissepiments numerous. Cretaceous
and Tertiary.

encrusting,

100

COELENTERATA— ANTHOZOA

THYLUM II

Coelosmilia E. and H. (Fig. 151). Like the preceding, but with dissepi-
ments sparsely developed. Cretaceous and Kecent.

Placosmilia E. and H. (Fig. 152). Cuneiform, base acutely pointed or
slightly pedunculate. Calice laterally compressed, elongated. Septa numerous ;

Fig. 150.

Trochosmilia granifera Haime. Turoiiian ; Bains-de-
Rennes, France, a, Profile ; b, Calice slightly enlarged
(after Fromentel).

Fig. 152.

Fig. 151.

Coelosmilia laxa E.

and H. White Placosmilia cuneiformis E.

Chalk ; Lüneburg, and H. Upper Cretaceous ;

Hanover. Natural St. Gilgen on Wolfgangsee,

size. Anstria. Natural size.

dissepiments abundant ; columella foliaceous. Epitheca absent ; costae granu-
lated. Cretaceous.

Diplodenium Goldf. Calice laterally compressed, greatly elongated in
transverse direction, and bent downwards at the ends so as to become crescent-
shaped. Columella and epitheca absent. Costae dichotomously or tricho-
tomously furcate. Upper Cretaceous.

Axosmüia E. and H. Jurassic. Fhyllosmilia From. Cretaceous. LopJio-
smilia E. and H. Cretaceous and Eecent.

ß. Coralla muUiplying hy lateral gemmation.

Placophyllia d'Orb. (Fig. 153). Buds originating on calicinal margin or
sides, and giving rise to bushy or massive colonies. Columella styliform
Jurassic.

Fig. 153.

Placophyllia dlanthus (Goldf.). Coral-
Rag ; Nattheim. a, Corallum, natural
size ; b, Calice enlarged.

Stylina delabechei E. and H. Coral-Rag ; Steeple
Ashton, England, a, Natural size ; b, Calices en-
larged.

Galaxea Oken. Bushy colonies with cylindrical corallites united by layers
of finely vesicular coenenchyma. Recent.

Stylina Lam. (Fig. 154). Massive colonies, with corallites united by
coalescent costae. Septa well developed, disposed in six, eight, or ten cycles.
Dissepiments numerous ; columella styliform. Multiplication by costal gemma-
tion. Profuse in Trias, Jurassic, and Cretaceous.

SUBCLASS II

HEXACORALLA

101

Cryptocoenia E. and H. Jurassic and Cretaceous.
Massive colonies, with corallites united by costae.
centre : colnmella absent. Visceral Chamber

Astrocoenia deeaphylla B. and H. Upper Cretaceous ; Gosau
Valley, Austria. «, Corallum, natural size ; b, Caiices enlarged.

Placocoenia d'Orb.

Cyathopliora Mich
Septa short, not reaching the
partitioned off by horizontal
tabulae. Jurassic . and Cre-
taceous.

Coccophyllnm Reuss. Massive
colonies, with corallites united
directly by their walls. Caiices
polygonal, septa numerous. Col-
umella absent ; visceral Cham-
ber tabulated. Alpine Trias.

Pinacophyllum Frech. Tri-
assic.

Holocystis Lonsd. Massive colonies, with corallites united by costae. Four
of the septa larger or stouter than the rest. Tabulae in visceral Chamber.
Cretaceous.

Astrocoenia E. and H. (Fig. 155). Massive colonies. Corallites polygonal,
united by their walls ; septa numerous, long. Columella styliform ; only
dissepiments present in visceral Chamber. Trias to Tertiary.

Stephanocoenia E. and H. Like the preceding, but with columella
surrounded by cycle of pali. Trias to Recent.

Phyllocoenia E. and H. {Confusastrea d'Orb. ; Adelastrea Reuss). Massive
colonies. Corallites round or oval, imperfectly united by costae. Septa
strongly developed, thickened in the middle between theca and the centre.
Columella rudimentary. Trias to Tertiary.

Convexastrea d'Orb. Trias to Cre-
^Tliaa^ taceous. Columnastrea, Stylocoenia E.

and H., etc. Cretaceous and Tertiary.

y. Coralla multiplying by fission.

Haplosmilia d'Orb. Bushy colonies.
Corallites usually with dichotomously
dividing crests. Caiices circular or
elongated ; columella styliform ; theca
with ridge-like costae. Jurassic.

Plocophyllia Reuss (Fig. 156).

Branching, foliaceous, or massive

colonies. Corallites either becoming

free or grouped into detached rows.

Columella absent. Tertiary.

Barysmilia E. and H. Corallum massive, forming a thick stem, the apex

of which is covered with short buds. Caiices oval, sometimes disposed in

series ; columella rudimentary. Cretaceous.

Stenosmilia From. Like the preceding, but with lamellar columella.
Cretaceous.

Pachygyra E. and H. Corallites arranged in winding rows, and united by
a broad mass of costal coenenchyma. Columella lamellar. Jurassic and
Cretaceous.

Fig. 156.

Plocophyllia calyculata Reuss. Oligocene ; Monte
Carlotta, near Vicenza. Natural size.

102

COELENTERATA— ANTHOZOA

PHYLUM II

Phytogyra d'Orb. Jurassic and Cretaceous ; Europe.

Bhipidogyra E. and H. (Fig. 157). Corallum fan-shaped, often corrugated,
and with but a single calicular furrow. Columella lamellar. Jurassic and
Cretaceous.

Fig. 157.
Bhipidogyra crassa From. Coral-Rag ; Gray, Haiite-Saone. 1/2 natural size.

Suborder 2. FUNGIDA Duncan.

Solitary or colonial corals. Synapticulae in tlie interseptal and mtercostal loculi.
Dissepiments present or absent. Septa lamellate and solid or slightly perforate, or
composed of a trabecidar lattice-work with numerous perforations. Basal structures
perforate or imperforate.

Family 1. Fungiidae Dana.

Embryo after becoming attached forms a trophozooid, which gives rise to buds
(anthoblasts) ; these become detached, forming free individuals (anthocyathi). Adult
corallum, simple or colonial, depressed or mitroid in form. Septa of higher cycles
perforate, those of the lower perforate or solid. Synapticula, but no dissepiments
present. Wall usually perforate in young, free individuals, subsequently more or less
compact. No epitheca.

Fungia Lamarck ; Halomiira Dana ; Polyphyllia Quoy and Gaimard ;
Zoopilus Dana ; Cryptabacia E. and H. ; Lithactinia Lesson ; Herpetolitha
Escholtz. Recent. Fungia oc-
curs also in the post-Pliocene.

Family 2. Agariciidae Verrill.

Simple or colonial Fungids
with lamellar, usually imper-
forate, septa. Wall solid in
simple genera, basal wall solid
in colonies, walls between coral-
lites solid when developed. Dis-
sepiments present or absent.

Microseris From. (Fig.
158). Corallum simple, dis-
coidal, circular ; upper side
vaulted, lower flat and granu-
lated. Cretaceous.

Trochoseris E. and H. Simple species, trochoid and fixed. Tertiary and Recent.

Cyathoseris K Sind H. (Fig. 159). Corallum turbinate, attached. Young

Fig. 158.

Microseris hemis-phaerica From. Greensand (Cenomanian) ; Le
Mans, France, a and b, Upper and lower surfaces, enlarged ; c,
Profile, natural size.

I.,.„

HEXACOKALLA

103

corallites arising from periphery by costal gemmation. Common outer wall
naked, striated. Cretaceous and Tertiary.

Leptophyllia Reuss (Fig. 1 60). Corallum simple, conical or cylindro-conicäl,
with superficial calice. Septa numerous, thin, regularly-toothed ; solid or only

Cyathoseris siCbregxdaris Keuss. Oligocene ; Monte Carlotta, near Viceiiza, Italy.
a, Top view ; h, Side view, natural size.

Fig. 160.

Leptophyllia sinuosa
From. Neocomian ; St.
Dizier, Haute - Marne.
Natural size.

partially perforate. Thin dissepiments present. Thin epitheca present.

Thamnasteria Lesauv. {Thamnastraea auct., of which T. lamourouxi is the
type.) Jura. Lophoseris E. and H. ; Agarkia Lam. ; Siderastrea Blv., etc.
Tertiary and Eecent.

Family 3. Anabaciidae Duncan.

(Pseudoasfraeinae and Pseudoagaricinae Pratz ; Microsolenidae Gregory.)

Simple coralla, or composite, hasally expanded or massive colonies. Septa
numerous, perforate, and composed of calcareous hodies (traheculae) arranged in
vertical or fan-shaped rows (trabeculate). Theca hetween individual corallites ahsent,
hut may he present on under side of corallites or on lower side of the common
stock. Interseptal loculi with synapticula and dissepiments. Abundant from Trias
to Cretaceous ; rarer in Tertiary and Recent.

Änahacia d'Orb. Simple, free, discoidal, or lenticular coralla, with flat
base. Upper side vaulted, calice slit-like. Septa very numerous, thin, and
united by synapticulae. Theca absent. Jurassic ; Europe.

Genabacia E. and H. Like the preceding but composite, the central calice
being surrounded by a row of smaller calices. Jurassic ; Europe.

Micrabacia E. and H. Cretaceous ; Europe.

Omphalophyllia Laube. Simple, turbinate or sub-cylindrical, attached,
and covered with epitheca. Septa very numerous, upper edges granulated.
Calice shallow, columella styliform. Alpine Trias.

Cyclolites Lam. (Fig. 161). Simple, free, discoidal, upper side vaulted,
lower flat and covered with corrugated epitheca. Septa very thin, extending
to the centre, extremely numerous, composed of vertical rows of traheculae,
and united by synapticulae and dissepiments. Very abundant in Cretaceous,
rare in Jurassic and Eocene.

Dimorpharaea From. (Fig. 162, A, B). Composite, laterally expanded and
pedunculate, or mushroom-shaped coralla. Common wall restricted to lower

104

COELENTERATA— ANTHOZOA

PHYLUM II

side of corallum ; individual corallites without proper walls, but united by
costal septa. Columella styliform or rudimentary. Septa well developed,
composed of fan-shaped rows of cylindrical trabeculae, and united by synapti-
culae and dissepiments. Very abundant from Trias to Oligocene.

Cyclolites undulata Lam.

Fig. IGl.

Upper Cretaceous ; Gosau Valley, Salzkainmergut.
surface ; c, Lateral aspect of septum, natural size.

(I, Side view ; h, Lower

Dimorphastrea d'Orb. Like the preceding, but with calices concentrically
arranged about a central individual. Trias to Tertiary.

Co7noseris d'Orb. (Fig. 163). Like Dimorpharaea, but with calices separated
into groups by ascending flexuous ridges. Jurassic and Tertiary.

Astraeomorpha Eeuss. Coralla composite, tuberous, basally expanded, or
branching, and covered with corrugated epitheca. Corallites small, united by
Short and stout costal septa ; columella styliform. Trias to Oligocene.

FKi. 162.

A, Dimorplmraea, Lateral surface of costal septum, enlarged
(8/1), showing ftabecular Constitution ; m, Line of junction of
two septa belonging to difterent corallites ; t, Trabeculae ;
p, Trabecular lacunae (after Pratz). B, Dimorpharaea agari-
cites (Goldfuss). Upper Cretaceous ; Gosau, Salzkainmergut.
Portion of upper surface of corallum, natural size.

Fi(i. 163.

Comoseris conferta Reuss. Oligocene ; Monte
Carlotta, near Vicenza. Twice enlarged.

Microsolena Lamx. Colony massive, polymorphous, mammiliform, conical,
with a broad base, nearly spherical, turbinate and pedunculate. Trias and
Jurassic.

Suborder 3. PERFORATA Milne Edwards and Halme.

Skeleton huilt up of small calcareous hodies (sclerites), between which are empty
interstices of greater or lesser size. Theca formed hj fusion of outer septal edges or
absent. Interseptal loculi empty throughout or traversed by synapticida or
dissepiments.

SÜBCLASS II

HEXACORALLA

10^

Family 1. Archaeocyathidae Walcott.i

Simple, turhinate, or sub-cylindrical coralla. Septa and theca porous ; inner
septal edges united hy perforated interiar wall, which encloses a hollow central space.
Synapticula present in interseptal loculi.

All biit one of the genera described up to the present time (Archaeocyathus
Bill., Ethmophyllum Meek, Spirocyathus Hinde, Protopharetra Bornem., etc.)
occur in the Cambrian rocks of North America, Spain, Sardinia and Aus-
tralia. Aükokania Walcott is known from the Lower Huronian of Ontario.
They represent possibly a distinct order of the Madreporaria.

Family 2. Eupsammidae Miliie Edwards and Haime.

Corallum simple or hecoming composite hy lateral gemmation. Septa very
numerous, sometimes united hy synapticula, and frequently witli their inner edges
fused together. Theca naked or covered with epitheca, and formed hy thickening of
the septal edges. Silurian to Recent.

Calostylis Linds. Corallum simple, sub-cylindrical, or composite and
multiplying by lateral gemmation. Septa very numerous, of spongy con-
sistency, and either fused together or united by synapticulae.
Columella thick, spongy ; wall covered with epitheca. Silurian ;
Gotland. This genus probably belongs to the Tetracoralla.

Haplaraea Milasch. Simple, cylindrical coralla, with broad

Fio. 164.

Eupsammia
t rochtformis
(Pallas). Cal-
caire Grossier ;
Chaussy, iiear
Paris. Natural
size.

I

'^^^^»sf^ist

Fig. 165.
Eahuwphyllia sinuata Reuss.
Oligocene , Waldböckelheiin,
Prussia. a, Natural size;
b, Number of septa enlarged.

Fig. 166.

Steplumophyllia elegans (Bronn). Pliocene ;
Stazzano, near Modena, Italy. a and h, Upper
and lower surfaces, enlarged ; c, Profile, natural

encrusting base. Septa numerous, extending to the centre, perforated
by large apertures, and sometimes fused together or united by synapticulae.
Dissepiments also present, but no columella. Jurassic and Cretaceous.

Eupsammia 'E. and H. (Fig. 164). Conical or turbinate, acutely pointed,
free. Septa very numerous, arranged in five cycles, those of the last cycle
stouter than the rest. Columella present or absent. Eocene to Recent.

Balanophyllia Wood (Fig. 165). Simple, sub-cylindrical, attached by
the base. Columella spongy ; septa closely crowded, partly fused together.
Eocene to Recent.

Stephanophyllia Mich. (Fig. 166). Simple, discoidal; base horizontal, calice

1 Billings E., Palaeozoic Fossils of Canada, i., 1861-65.— WWc-o^^, C. D., Bull. U.S. Geol.
Survey, No. 30, 1886.— ßor7iema?iw, /. G., Versteinerungen des Canibrischen Systems von Sardinien.
\%%Q.— Hinde, G. J., Quart. Journ. Geol. Soc, 1889, vol. x\v.—Lambe, L. M., Revision of the
Genera and Species of Canadian Palaeozoic Corals. Geol. Surv. Canada, Contrib. to Canad. Palaeont.,
1899, vol. \\.— Taylor, W. T. G., The Archaeocyathinae. Mem. R. Soc. S. Aust., 1910, vol. ii.

106

COELENTERATA— ANTHOZOA

PHYLUM II

circular. Septa numerous ; the six priiicipal septa extending to the centre,
the remainder with fused inner edges. Cretaceous and Tertiary.

^^ Dendrophyllia Blv. (Fig. 167). Corallum

branching, increasing by lateral gemmation.
Calices oval ; septa numerous and slender, those
of the last cycle extending to the spongy
columella, and fused with the converging ends
of shorter septa of preceding
cycle. Tertiary and Recent.

Lohopsammia, Stereopsammia
Edw. and H. Eocene. Astroides
E. and H. (Fig. 97). Kecent.

Family 3. Poritidae Dana.

Composite coralla composed of
porous sderenchyma. Corallites
small ; septa as a rule only moder-
Fio. 167. ately numerous, sometimes repre-

DendrophyUia elegans Duncan. Oligocene ; Brockenhurst, Seuted by TOWS of trabeculae OT
England, a, Corallum, natural size ; b, Transverse section of 7 77 m. i 1

caiice, eniarged, iameUae. I fieca aosent.

Subfamlly A. Spongiomorphinae Frech.

Corallum composed of thicJc trabeculae and strengthened by horizontal synapticulae.
Calices very imperfectly differentiated from coenenchyma, and without distinct septa.
Dissepiments usually sparsely developed.

Of the genera belonging to this subfamily, Spongiomorpha, Heptastylis and
Stromatomorpha Frech, are found in the Alpine Trias (Rhaetic and Zlambach
beds). These are all tuberous, composite coralla of extremely irregulär form.
In Spongiomorpha and Heptastylis, six septa are indicated by somewhat regularly
disposed columns of trabeculae ; and in the latter form these are bound
together by synapticulae which are projected at equal altitudes, and form
perforated horizontal storeys. In a b

Stromatomorpha no radial arrange-
ment of the trabecular septa exists.

Palaeacis E. and H. (Sphenopo-
terium Meek and Worth.), occurring
in the Lower Carboniferous limestone
of North America and Scotland, per-
haps also belongs here.

Fig. 168.
Adinacis elegans Reuss. Upper Cretaceous ; Gosau
Valley, Salzkaramergut. a, Upper surface, natural size ;
h, Transverse section, eniarged ; c, Longitudinal section,
eniarged (after Reuss).

Subfamily B. Poritinae Milne Ed-
wards and Haime.

Septa not very numerous, well developed.
Corallites united by their porous walls.

Litharaea E. and H. (Fig. 169). Massive coralla. Calices sub-polygonal,
septa generally in three cycles ; columella spongy. Eocene and Miocene.

Rhodaraea E. and H. Massive coralla. Spurious walls of corallites thick ;
pali prominent. Miocene and Recent.

SÜBCLASS II

HEXACORALLA

107

Porites Link (Fig. 170). Massive or branching coralla. Calices shallow,
polygonal ; septa irregularly reticulated, usually twelve in number ; columella

Litharaea ivehsterl (Bowerb.). Eocene ; Bracklesliam
Bay, England, a, Coralluin, natiiral size ; h, Four calices
enlarged.

Fig. 170.

Porites incrustans Reuss. Miocene ; Mo-
ravia. a, Tranverse section ; b, Longi-
tiidinal section. Both tigures highly magni-
fied.

papillous, surrounded by a single cycle of pali, the latter five or six in
number, and not very distinct from the septal ends. Endotheca exists
sparingly, and may be dissepimental or tabulate, or may be mere stereoplasm.
Cretaceous to Recent. Thegenus b c

Porites is one of the most im- a ^^^ .

portant of existing reef-builders. -^^^f^s^^ ^

Subfamily C.
Alveoporinae Verrill.

Septa composed of detached
traheculae, spines, or reticulated
lamellae, Theca perforate. Vis-
ceral Chamber with perforate tabulae.

Alveopora Quoy and Gaim.
(Fig. 171). Massive coralla.
Calices small, polygonal. Septa
represented by detached spinous processes.
remotely situated. Tertiary and Recent.

KonincUa E. and H. Cretaceous ; Europe.

Fig. 171.
a,Alveoporaspongiosa'Dm\&. Recent ; Fiji Islands. Longi-
tudinal section of corallite showing perforate vvalls and tabulae;
h, Alveopora rudis Reuss. Nummulitic liniestone ; Oberburg,
Styria, Vi ; c, Calices, greatly enlarged. (Fig. a, after Dana ;
h, after Reuss.)

Tabulae sparsely developed,

Family 4. Acroporidae Verrill.

Cor)iposite, branching, lobate, foliaceous, or massive coralla with corallites embedded
in a canaliculated and reticulated coenenchyma. Septa (6-24) compact, sometimes
imperfectly developed. Two long septa often projected from opposite sides and meeting
in the centre.

The genus Äcropova Oken (Madrepora auct., non Madrepora Linn., 1758)
(Fig. 172), is an important agent in the construction of existing coral reefs,
and builds colonies sometimes of considerable size. It occurs sparsely in the
fossil State in Tertiary strata of various regions.

Actmacis d'Orb. (Fig. 168). Massive or branching coralla. Coenenchyma
abundant, granulated ; septa stout, of nearly uniform proportions, columella
papillous ; pali in front of all the septa. Cretaceous and Tertiary.

108 COELENTERATA— ANTHOZOA phylum ii

Astreopora Blv. Massive coralla. Coenenchyma porous and on upper
surface echinulate. Septa of dissimilar proportions ; columella and pali
absent. Tertiary and Recent.

Dendracis E. and H, ; Cryptaxis Reuss. Tertiary.

Turbinaria Oken (Gemmipora Blv,). Corallum foliaceous. Coenenchyma
tolerably compact and finely echinulate. Septa of similar proportions :
columella spongy. Cretaceous to Recent.

Range and Distribution of the Hexacoralla.

The group Aporosa of the Hexacoralla begins as the Tetracoralla disappear,
and develop a great variety of forms in the Trias, from the Mesozoic onward
to the present day they have continued to play a leading part in the con-
struction of coral-reefs. Of the f amilies constituting the Aporosa, the
" Astraeidae " is by all odds the most important and most protean, in com-

parison to which the Fungida, Stylo-
phoridae, Pocilloporidae, Oculinidae and
Turhinolidae fall into greatly subordinate
rank. The other f amilies are all younger
than the "^s/raßw/ae/'not beginninguntil
the Jurassic, the Pocilloporidae, indeed, not
until the Tertiary.
Fig. 172. The Eupsammidae and Poritidae of

Jcroporo ajifirZica (Duncan). Oligocene; Brocken- the Perforata OCCUr Sporadicallv in the
hurst, England, a, Calices enlarged ; b, Longi- ^-i • t r~i ^ -r ^ •^ -. •

tudinal section, greatly enlarged. bllurian and üarboniterOUS, whllc it IS UOt

until the Trias that the Anabraciidae and
Poritidae develop a large variety of forms ; from the Trias to the Tertiary,
however, these genera continue to be important reef-builders. The Eupsam-
midae attain their greatest development in the Tertiary and Recent, while the
Acroporidae belong almost exclusively to the present period.

Occasional isolated deep-sea forms are met with in most of the several
geological periods, but the usual mode of occurrence of the Hexacoralla is
associated in masses in coral limestones ; the limestones may be of very vari-
able thicknesses, but as a rule are interstratified between deposits of distinctly
littoral character. Ancient coral-reefs most nearly resemble modern fringing
or barrier reefs, but not atolls, the origin of which is clearly dependent upon
peculiar conditions.

The St. Cassian, Zlambach and Rhaetic beds of the Alpine Trias contain
large numbers of reef-building Hexacoralla; but the pure limestones and
dolomites of the Alps, as well as the Trias outside the Alpine region, are
frequently either almost or entirely destitute of coral remains.

In the Lias, coral-reefs have been found in England, Luxemburg and
Lorraine. Certain beds of the Dogger, usually of but meagre thickness, are
occasionally charged with corals, as in Swabia, the Rhine Valley in Baden, the
Swiss Jura, Normandy and England. Coral limestones are abundantly
developed in the Upper Jurassic of the Jura Mountains in France and Switzer-
land, in Lorraine, Southern Baden, Swabia (Nattheim, Blaubeuern), Bavaria
(Kelheim), many places in France and England, as well as in the whole province
of the Alps, Carpathians, Cevennes and Apennines ; here the uppermost

I

CLAss III ALCYONARIA 109

horizon (Tithonian) is especially characterised by their development. Reef
corals are also greatly developed in the Cutch (Jurassic) series of India.

In the Lower Cretaceous (Neocomian) coral-reefs are found in France
(Haute -Marne and Yonne), Crimea and Mexico; while the Urgonian of
Switzerland and the Bavarian Alps is occasionally charged with corals. In the
Turonian and Senonian of the Alps (Gosau Beds), Pyrenees and the Provence,
numerous coral-reefs occur, usually accompanied by Budistae ; elsewhere, how-
ever, except in Holland (Maestricht) and Denmark (Faxoe), the Upper
Cretaceous contains but a limited number of reef-building Hexacoralla.

In the older Tertiary (Eocene and Oligocene) occurrences of coral-reefs are
known on the northern and southern flanks of the Alps and Pyrenees, in Arabia,
India, the West Indies, and in Georgia, Florida, Alabama, Mexico and Central
America ; outside these areas their distribution is mostly sporadic. In the
Miocene and Pliocene the true coral-reefs retreat more and more towards the
equator (Red Sea, Java, Japan, Gulf of Mexico), while the Hexacoralla which
persist in geologic formations within the temperate zone (Vienna Basin, Italy,
Touraine) constitute but an insignificant feature of the general fauna.

[Tlie foregoing sections on the Tetracorallä and Hexacoralla have been revised by Dr. T.
Wayland Vaughan, of the United States National Museum at Washington. It sliould be
observed tliat, in the present unsatisfactory state of our knowledge of these organisms, the
Classification adopted in this work, although perhaps as good as any available, is tentative in
character. — Editok.]

Subclass 3. ALCYONARIA Milne Edwards.

{Octacfinia Ehrenberg ; Oäocoralla Haeckel).

Composite colonies, rarely simple polyps, the individuals provided with eight
mesenterial folds and eight broad, pinnately fringed, or plumose tentacles, which form
a Single cyde about the mouth,

Hard skeletal elements are very generally developed in the Alcyonaria, being
absent in comparatively few forms, and are remarkable for their manifold
variety ; they occur either detached in the ectoderm and mesoderm, or are
closely packed together at the base to form a horny or calcareous axis (sclero-
basis), about which the polyps are distributed. Sometimes the calcareous
bodies (sderodermites) form compact tubes which are periodically partitioned
off into storeys with the upward growth of the animal. Reproduction is
accomplished either sexually, or asexually by basal or lateral gemmation,
rarely by fission.

Only the calcareous parts are known in the fossil state, such as the solid
axes, detached skeletal elements, tubes and composite coralla ; the horny
structures are totally destroyed during fossilisation. The Alcyonaria make
their appearance in the Ordovician, but rarely occur in great abundance.

Family 1. Alcyonidae Milne Edwards and Haime.

Fixed, fleshy, lobate, or ramose polyp Stocks (very rarely simple individuals), with
echinulate or spicular calcareous bodies (sderodermites) occurring detached in the
soft parts.

Isolated sderodermites readily escape Observation, owing to their minute

110

COELENTERATA— ANTHOZOA

PHYLUM II

size and fragile Constitution. They have been detected as yet only by Pocta
in the Upper Cretaceous strata near Laun, Bohemia.

I

Fig. 173.

Graphularia de-
sertorum Zitt.
Nummulitic lime-
stone (Bocene) ;
Farafreh, Libyan
Desert, Africa. a,
Axis, natural size ;

b, Section of same ;

c, Striated surface,
enlarged.

Family 2. Pennatulidae Milne Edwards and Haime.

Folyp Stocks with hase embedded in sand or mud, and with horny
or calcareous sclerohase ; polyps dimorphic.

Slender, round or quadrate calcareous axes referable to tbe
Pennatulidae have been detected with certainty only in the
Trias (Prographularia Frech.), Cretaceous (Pavonaria Cuv. ;
Pennatulites and Palaeosceptron Cocchi ; Glyptosceptron Böhm),
and Tertiary (Graphularia E. and H.) (Fig. 173).

Family 3. Gorgonidae Milne Edwards and Haime.

Fixed, branching or fan-skaped colonies, vnth horny or calcareous
solid sclerohase, or with jointed axis composed of alternating horny
and calcareous segments.

All the genera possessing horny, flexible axes (Gorgonia,
Rhipidogorgia, etc.) are perishable. Detached remains referable
to Primnoa, Gorgonella and Firgidaria, the axes of whicli are
composed of both horny and calcareous layers, have been
described from the Tertiary. In the genus Isis the axis con-
sists of cylindrical calcareous segments alternating with horny
connecting joints. It is found fossil in the Tertiary, and has
been reported also from the Cretaceous. The genus MoltJcia,
occurring in the Upper Cretaceous, has cylindrical joints which
are pitted with slight depressions indicating the position of
branches. In the red or gem coral (Corallium Linn.) the axis
is built up of spiniform sclerites, which are united by a fibro-
crystalline calcareous matrix impregnated with organic matter.
It occurs only rarely in the fossil state, but is known from
the Cretaceous and Tertiary.

Family 4. Tubiporidae Milne Edwards and Haime.

Coralla composed of red-coloured parallel calcareous tuhes connected
by horizontal plates.

The cylindrical tubes of the recent Organ-pipe Coral (Tubi-
pora) are composed of spiniform sclerites, which are united with one
another directly in such manner as to enclose small hollow Spaces appearing
superficially as pores. The connecting horizontal plates or floors are tra-
versed by canals which communicate with the visceral Chambers of the
tubes by means of numerous round openings. New corallites are budded
from their upper surfaces. Unknown in fossil state.

^ Poita, Philipp, Sitzimgsber. Akad. Wiss. Wien, 1885, vol. xcii.

SÜBCLASS III

ALCYONARTA

111

Family 5. Helioporidae Moseley.^

Calcareous coraMa, composed of two series of tuhiform corallites ; the larger tubes
(autopores) are embedded in a strongly developed coenenchyma made up of smaller
tubes (siphonopores). Both autopores and siphonopores are dosely tabulate ; the
autopores are provided with ridge-like pseudosepta, which, however, do not correspond
numerkally with the tentacles.

The affinities of the Helioporidae with the Alcyonaria were first pointed out
by Moseley. The larger polyps inhabit the autopores, and are furnished with
eight mesenterial folds and a crown of eight tentacles ; while the smaller
polyps, which are without either tentacles or sexual organs, are lodged in the
siphonopores. The skeleton is composed of calcareous trabeculae, the same as
in the Hexacoralla, from whose centres of calcification radial fibres extend
outwards in caespitose fashion. The siphonopores multiply by intermural
gemmation, while the autopores
are formed by the coalescence
and fusion of a number of the
siphonopores.

Heliopora Blainv. (Fig. 174,
A, B). Corallum massive or
ramose; autopores with 12-25
slightly developed pseudosepta,
and embedded in a coenen-
chyma made up of smaller
siphonopores : the latter are
more closely tabulate than
the autopores. Cretaceous to
Recent.

Polytremacis d'Orb. (Fig. 174, C). Like Heliopora, but pseudosepta much
more strongly developed, sometimes reaching nearly to the centre. Cretaceous.

Octotremacis Gregory {Polysolenia Reuss non Ehrenb.). Miocene ; Java.

Fig. 1T4.

Heliopora partschi (Reuss). Upper Cretaceous ; St. Gilgen on
Wolfgangsee, Salzkammergut. J, Corallum, natural size. iJ, Por-
tion of surface, enlarged. C, Polytremmis hlainvilleana Reuss.
Upper Cretaceous ; Gosau, Salzkammergut. Vertical section,
enlarged.

Family 6. Heliolitidae Lindström.2

Corallum. massive, more rarely ramose, varying from spheroidal to flabellate,
composed of tubulär or vesicular coenenchyma enclosing corallites in the form of large
cylindrical and numerous smaller angular cells ; both the macro- and microcorallites
with tabulae. Usually twelve septa present in the large cylindrical cells, but these
are often rudimentary. No mural pores ; basal epitheca present. Silurian and
Devonian.

The genera assigned to this family exhibit in their general appearance,
finer structure and manner of multiplication, considerable resemblance to
Heliopora, with which they were associated by Moseley, Nicholson, Bourne,

1 Moseley, IL N., The Structure and Relations of Heliopora caerulea. Pliilos. Trans. Royal
Society, 1877, vol. clxvi. — Bourne, G. C, On the Structure and Affinities of Heliopra caerulea.
Ibid., 1895, vol. clxxxvi. pt. 1.

2 Lindström, G., Reniarks on the Heliolitidae. K. Svensk. Vetensk. Akad. Handl., 1899,
vol. xxxii. — Klär, J. , Die Koralleufauna der Etage 5 des norwegischen Silursystems. Palaeontogr.
1899, vol. xlvi. — Idem, Revision der mittelsilurischen Heliolitiden, etc. Videnskabs-Selskabets
Skrift. I. Classe, No. 10, 1903.

112

COELENTERATA— ANTHOZOA

PHYLÜM II

Gregory and others. Here, as in Heliopora, the autopores are formed by
coalescence of numerous siphonopores in the coenenchyma. On the other hand
the corallites in the Heliolitidae have well-developed walls of compact homo-
geneous matter, and as a rule also tvvelve strong septa are present, sometimes
reaching nearly to the centre of the cylindrical Chambers. On account of
these differences the family has been separated from Heliopora, and some
authors have proposed to associate them with certain Hexacoralla, or with
the problematical Tabulata.

Heliolites Dana (StelliporeUa Wenzel; Nicholsonia Kiär) (Fig. 175). Corallum
massive, nodular or ramose. Autopores with twelve more or less strongly
developed pseudosepta, though occasionally represented by rows of spinules,
and frequently with central columella. Siphonopores without septa, and
multlplying by fission or intermural gemmation. Abundant from Ordovician
to Devonian.

Plasmopora E. and H. (Diploepora Quenst.). Like Heliolites, but having
walls of the siphonopores incomplete, and tabulae of contiguous tubes fused
together so as to form a vesicular tissue. Ordovician to Devonian.

iyv.

mMi"'

Heliolites porosa Goldfuss.

Devonian ;
enlarged

Fig. 175.

Eifel. ^, Corallum, natural size. iJ, Portion of outer sui 1
. C, Longitudinal section, enlarged.

Profaraea E. and H. (Stylaraea E. and H., 7ion Seebach). Low incrusting
corallites, with relatively little coenenchyma. Tabulae present in the autopores.
According to Kiär, this form and Coccoseris Eichwald are closely related, and
perhaps identical. Ordovician and Silurian ; Scandinavia and North America.

Cosmiolithes Lindstr. Corallites thin, lamelliform. Coenenchymal pores
thick-walled, not all of the same size, with concave or obliquely directed
tabulae. Autopores with well - developed septa. Silurian ; G. ornatus
Lindstr.

Plasmoporella, Palaeoporites and Trochiscolithus Kiär. Silurian ; Scandinavia.
Acantholithus, Pycnolithus Lindstr. Eelated genera having the same distri-
bution.

Appendix to the Anthozoa.

Sub Order. TABULATA Milne Edwards and Halme. ^

Invaridbly composite coralla composed of tubiform or prismatic corallites. Walls
thick, independently calcified, compact or perforated hy connecting mural pores. Septa

^ Literature : Lindström, O., Affinities of the Anthozoa Tabulata. Ann. Mag. Nat. Hist., 1876,
ser. 4, vol. xviii. — Nicholson, H. A., On the Structure and Affinities of the Tabulate Corals of the
Palaeozoic Period. London, 1879. — Roemer, F., Lethaea Palaeozoica, i., 1883, p. 416. — Waagen,

suBCLAss III TABULATA— FAVOSITIDAE 113

hut slighüy developed (usualli/ six or twelve), sometimes 7'epresented merely hy vertical
ridges or rows of spines, and sometimes entirely absent. Visceral Chamber partitioned
ojf into successive storys by tabulae. Synapiiculae and dissepiments wanting.

To the Tabulata were originally assigned by Milne Edwards and Haime
all corals having numerous tabulae and rudimentary septa. Later researches
have shown, however, that some of these forms (Focilloporidae) belong to the
Aporosa, others (Ilelioporidae) to the Alcyonaria, and still others (MiUepora) to
the Hydrozoa. The majority of the typical Tabulata (Favositidae, Syringoporidae,
Halysitidae) exhibit close relationships to the Hexacoralla ; but since they are
for the most part now extinct and are largely confined to the Paleozoic rocks,
the determination of their systematic position is a matter of much difficulty.
The ontogeny of the corallites in the Tabulata shows that the development of
mural pores is homologous with the process of gemmation. Reproduction
sometimes takes place by fission, but generally by means of buds from the
edges of the calices at various stages during the growth of the parent corallites.
Buds are given ofF early in Aulopora, producing basal corallites only ;
periodically in Romingeria, producing verticils of corallites ; periodically and
on one side in Halysites, producing linear series of adjacent corallites ; and
very frequently in Favosites, etc., producing compact coralla with numerous
mural pores representing aborted buds.

Family 1. Favositidae Milne Edwards and Haime.

Massive or branching coralla. Corallites uniformly prismatic, toll and united by
their walls, which are perforated by large-sized pores. Septa very short, usually
represented by but faintly projecting ridges or rows of spines, but seldom completely
absent. Tabulae numerous, situated at regulär intervals, complete and horizontal,
more rarely oblique or irregularly vesicular {^' cystoid").

The Favositidae are distinguished from the Poritidae, with which Verrill
associates them, by their thick solid walls, which are perforated by round,
sometimes tubiform mural pores. The corallites are usually polygonal in
contour, and their walls exhibit in transverse sections a dark, or sometimes
light-coloured median line, with thickenings of stereoplasma on either side
(Fig. 176, C). The family is exclusively Paleozoic, and plays an important
part in the formation of Silurian, Devonian and Carboniferous coralline
limestones.

Favosites Lam. {Calamopora Goldf.) (Fig. 176). Corallum massive, more
rarely branching. Corallites prismatic, polygonal, generally hexagonal.
Mural pores distributed at considerable intervals. Septa very faintly
developed, represented by longitudinal ridges or rows of spines, or occasion-
ally obsolete. Tabulae numerous. Ordovician to Carboniferous ; very
abundant in Silurian and Devonian.

W., and Wentzel, J., The Salt Range Fossils. Palaeontol. Indica, 18S7.—Beecker, C. U., The
Development of a Palaeozoic Poriferous Coral. — Symiiietrical Cell Development in the Favositidae.
Trans. Conn. Acad., 1891, vol. viii. — Wentzel, J., Zur K(3untniss der Zoantharia tabulata.
Denkschr. Akad. "Wien, 1895, vol. \xü.—Sardeso7i, F. W., Über die Beziehungen der fossilen
Tabulaten zu den Alcyonarien. Neues Jahrb. Mineral., 1896, Supplem. vol. x. — Weissermel, W.,
Sind die Tabulaten Vorläufer der Alcyonarien? Zeitschr. deutsch, geol. Ges., 1898, vol. 1. —
Vinassa de Regny, P. E., Trias-Tabulaten, etc. Res. d. wisseusch. Erforsch, des Balaton-Sees,
vol. i. pt. 1, Badapesth, 1901.

VOL. I I

114

COELENTERATA— ANTHOZOA

PHYLÜM II

Columnopora Nich. {Calapoecia Billings). Like the preceding, but with
numerous, short, well-marked septa. Mural pores large, disposed in vertical
rows between the septa. Ordovician.

Fig. 17(3.

Favosites polymorpha (Goldf.). Devonian ; Eifel. A, Coralluni, natural size. B, CoraUites enlarged, two
of them broken open and showing tabulae. C'and D, Transverse and longitudinal sections showing spiniform
septa and mural pores {p). (C and B after Nicholson.)

Emmonsia E. and
Ordovician (Trenton).

H. Ordovician to Carboniferous. Nyctopora Nich.
Syringolites Hinde. Silurian (Niagara).

Pachypora Lind. (Fig. 177). Corallum branch-

«-— «^»^ ing, composed of prismatic, polygonal corallites,
^ ySKmJIm *^® walls of which are so thickened towards their
VU/^Mf mouths by layers of stereoplasma that the calices
wMyRjfc appear to have circular contours. Septa very
minute ; mural pores scanty, but often of large size.
Abundant in Silurian and Devonian.

Trachypora E. and H. Dendroid with cylindrical
stems. Corallites polygonal ; walls so thickened by
layers of stereoplasma that the calices become round
and greatly contracted, and appear to be superficially
widely separated. Mural pores few and irregularly
distributed. Septa represented by rows of spines.
Tabulae at remote intervals. Common in Devonian.
Striatopora Hall (Fig. 178). Like the preceding, but with tubes con-
tracted by stereoplasma at a greater depth, so as to give the calices a
funnel-shaped appearance. Silurian and Devonian.

Alveolites Lam. (Fig. 179). Corallum massive or
branching, composed of small, contiguous, compressed,
thin-walled corallites, with obliquely opening triangulär
or semilunar calices. Septa very faint, represented
merely by ridges or rows of spinules, sometimes but
a Single row present. Mural pores of large size, ir-
regularly distributed. Very common in Silurian and
Devonian.

öladopora Hall ; Coenites Eichw. Silurian and Devonian.

Pleurodidyum Goldf. (Fig. 180). Corallum depressed, discoidal, circular

Fig. 177.

Fachypora nicholsoni Frech.
Middle Devonian; Eifel. A,
Transverse section. B, Longi-
tudinal section, enlarged ; p,
Mural pores (after Nicholson).

Fig. 178.

Striatopora flexnosa Hall.
Silurian (Niagara) ; New
York.

SUBCLASS III

TABULATA— FAVOSITIDAE

115

or elliptical in contour, lower surface covered with concentrically striated
epitheca, and frequently a foreign vermiform body occupying the ceiitre of the
base. Corallites small, polygonal, contracted inferiorly so as to become
funnel-shaped. Septa represented by faint marginal ridges, or obsolete.

Fig. 179.

A, Alveolites suborhicukiris L&m. Middle Devonian ; Gerolstein, Eifel.
Natural size. B and (', Alveolites lahechei E. and H. Silurian (Wenlock) ;
Ironbridge, England. Tangential and vertical sections, lo/j (after Nicholson).

Fig. 180.

Pleurodicty u m prohlemaiicum,
Goldf. Lower Devonian ; Co-
blenz. Natural size. Vermiform
foreign body in the centre.

Walls pierced by irregularly distributed mural pores ; tabulae sparse.
Devonian. P. prohlematicum Goldfuss, is rather abundant in the Lower
Devonian " Spirifera sandstone " of the Eifel, but is known only in the form
of casts. In these the walls of the corallites are represented by narrow
fissures which are bridged across by transverse rods, while the visceral Chamber
is filled up with sandstone, P. stylopora Eaton, from the Hamilton Group of
North America, is a closely related species and also possesses the vermiform
body.

Ä B C

Fig. 181.
Michelinia fuvosa de Kon. Carboniferous Limestone ; Tournay, Belgium. A, Corallum fronl above. B,
Lower surface with radiciform epithecal processes. C, Vertical section (after Gaudry).

Michelinia de Kon. (Fig. 181). Discoidal or hemispherical coralla, often
of considerable size, and covered on the under surface with concentrically
striated epitheca, which frequently develops hollow radiciform processes.
Corallites polygonal, rather large. Septa represented by numerous longi-

116

COELENTERATA— ANTHOZOA

FHYLUM II

tudinal Striae or ridges ; mural pores irregularly distribiited ; tabulae very
numerous, oblique or curved, incompletely developed, and usually filling
the visceral Chamber with loose vesicular tissue. Devonian and Carboniferous.
M. favosa de Kon., extraordinarily profuse in the Lower Carboniferous Lime-
stone of Belgium.

Family 2. Auloporidae Nicholson (Tuhulosa Milne Edwards and Haime).

Creeping, hranching or reticulated tubulo,r coralla, composed of cylindrical, leaker
or trumpet-shaped corallites, with thicJc, imperforate, wrinkled walls. Sepia repre-
sented hy faint marginal Striae ; tahulae moderately numerous
or wanting. Reprodudion by basal or lateral gemmation.
Ordovician to Carboniferous.

Aulopora Goldf. (Fig. 182). All the corallites of the
prostrate corallum are attached by the whole of the lower
surface to some foreign object (Alveolites, other corals, or
mollusks). Tabulae more or less curved ; reproduction by
basal gemmation. Ordovician to Carboniferous.

Cladochonus M'Coy (Fyrgia E. and H.). Corallum
branching, attached only at isolated points, and composed
of funnel-shaped corallites without tabulae and septa.
Reproduction by lateral gemmation. Carboniferous,

Romingeria Nich. [Quenstedtia Rom.). Spreading,
semi-erect, bushy coralla, only basally attached, and with
cylindrical corallites increasing by lateral gemmation.
Tabulae moderately numerous, horizontal. Silurian and
Devonian.

Fig. 182.

A ulopora t ubaeformis
Goldf. Devonian ; Gerol-
stein, Eifel. Natural size
(after Goldfuss).

Family 3. Syringoporidae Milne Edwards and Haime.

Fasciculate coralla composed of cylindrical corallites, unifed at intervals along the
sides by hollow connecting processes or hy horizontal expansions. Walls thicJc,
wrinkled; septa faintly developed, represented by delicate
ridges or longitudinal rows of spinules ; tabulae numerously
developed, usually irregularly funnel-shaped. Reproduction
by basal gemmation or by buds arising from the connecting
processes and horizontal expansions. Ordovician to Car-
boniferous ; maximum in Devonian and Carboniferous.

Syringopora Goldf. (Fig. 183). Fasciculate coralla,
often attaining considerable size, and composed of
cylindrical, thin-walled, somewhat flexuose corallites;
the latter communicate by means of hollow, cylindrical,
connecting processes. Septa rudimentary ; tabulae
funnel-shaped. Corallum commencing with prostrate
basal zooids similar to Aulopora. Numerous species
ranging from Silurian to Carboniferous.

Chonostegites E. and H. Corallum massive ; cylindrical corallites connected
by horizontal, hollow, laminar expansions into which the endothecal tissues are
directly continued ; tabulae oblique, cystoid. Devonian.

Fig. 183.

Syringopora ramulosa Goldf.
Carboniferous Liinestone ;
Regnitzlosau, Fichtelgebirge.
Natural size.

I

Fia. 184.,

BCLAss III TABULATA— CHAETETIDAE 117

Thecostegites E. and H. Corallum encrusting ; corallites short, cylindrical,
and connected by thick horizontal plates. Tabulae approximately horizontal ;
septa twelve in number, represented by marginal ridges. Devonian.

Family 4. Halysitidae Milne Edwards and Haime.
Chain corals.

Corallum composed of long, cylindrical, laterally compressed
corallites, which are joined to one another only along the more
restricted edges, and form free, vertical, intersecting and anas-
tomosing laminae. Wall thick, covered on free sides by wrinUed
epitheca ; tabulae numerous, horizontal or concave ; septa repre-
sented by vertical ridges or rows of spines, in cycles of twelve,
sometimes entirely absent. Increase by stolonal gemmation.

The unique genus Halysites Fischer (Catenipora Lam.)
(Fig. 184), comprises two groups of species ; those in
which the corallum is composed throughout of coral-
lites of equal size (H. escharoides Lam. sp.), and others in
which any two of the larger corallites are separated by
the intervention of a single smaller, closely tabulate tube , .

, ^-r , . ^ . \/^i-. T ri", • . Halysites catemilana

{II. catenmana L\nn. sp.) Urdovician and JSilunan ; maxi- (Linn.). Siiurian ; Got-
mum in the Siiurian. ^^"^- Natural size.

Family 5. Chaetetidae Milne Edwards and Haime.

Massive coralla, composed of fine, subequal, tubiform corallites, contiguous on all
sides. Calices rather irregulär in shape, one diameier slightly greater than the other.
Walls thoroughly amalgamated, common to adjacent corallites, imperforate, apparently
composed of closely arranged, anJcylosed vertical columns, which terminale at the
surface in hollow prominences. Septa absent, but one or two tooth-like projections
often observable in sections. Tabulae horizontal, remote or abundant.

The forms belonging to this family are extinct, and occur chiefly in the
Ordovician, Siiurian, Devonian and Carboniferous Systems ; but a few are
also found sporadically in the Trias, Jura and Cretaceous. They are largely
concerned in the formation of Paleozoic coral reefs, especially during the
Carboniferous. Milne Edwards and Haime regarded them as Anthozoans,
Rominger and Lindström as Bryozoans, while Dybowski emphasised their
affinities with the Favositidae. By Nicholson they were assigned to the Octo-
coralla, for the reason that the corallites frequently exhibit a dimorphous
character the same as in Heliolites and Heliopora, besides agreeing in their
microscopic structure with Heliolites; while in addition they possess well-
developed tabulae and imperforate walls. Many genera and species formerly
included under this family are now assigned to the Bryozoa.

Chaetetes Fischer (Figs. 184«, 1846). Corallites long, thin-walled, prismatic,
polygonal, all of one kind, and multiplying by fission. Uncompleted fission
of the tubes often indicated in section by tooth-like projection extending
into the visceral Chamber. Walls structureless, without dark median line ;
tabulae complete, remote. Very abundant in Lower Carboniferous ; found

118

COELENTERATA— HYDROZOA

PHYLUM II

also in Lias and Upper Jurassic. C. radians Fisch., is an important rock-
builder in the Russian Lower Car-
boniferous, especially near Moscow.

Dania E. and H. Silurian. Tetra-
dium Dana. Ordovician and early Sil-
urian. Pseudochaetetes Hang. Upper
Jurassic; Europe. P. pohjporus (Qaenst.).

Fig. 184a.

Chaetetes septosus Fleiii. Lower Car-
boniferous ; England. A, Transverse
section parallel to npper surface. B,
Vertical section both enlarged ; p, Pro-
jecting spines representing uncompleted
fission (after Nicholson).

Fio. 184^.

Chaetetes radians Fischer. Lower Carbon-
iferous ; Moscow, Russia. Portion of longi-
tudinally fractnred coralluni, natural size.

Geological Range of the Tabulata.

With but few exceptions the Tabulata are restricted to Paleozoic for-
mations, and from the Ordovician to the Carboniferous Systems inclusive
occur in considerable profusion, being associated with the Tetracoralla and
certain Hydrozoa (Stromatoporoids) in the building of large coral reefs. Of
the various families constituting this group, the systematic position of which is
uncertain, the Halysitidae are limited to the Ordovician and Silurian, and the
remainder, including the genus Chaetetes Fischer, are represented continuously
from the Ordovician to the Carboniferous. In the Middle Cambrian shales
of British Columbia, Walcott has recently discovered a remarkably well-
preserved actinian, named Mackenzia, which appears to belong to the family
Edwardsiidae, and to be closely related to the genus Edwardsia.

Class 2. HYDROZOA Huxley. Hydroids and Medusae.i

Sessile or free-swimming polyps or polyp Stocks, without oesophageal tube, and with
simple gastrovascular cavity not divided into radial pouches.

The Hydrozoans are organisms which rarely secrete hard parts, and hence
are ill-adapted for preservation in the fossil state. The ramifying polyp Stocks
are usually inferior in size to those of the Anthozoa, and possess always a
simpler structure ; dimorphism or polymorphism is, however, exhibited by the
difFerent individuals, some of which perform solely vegetative, and others only
reproductive or protective functions. Of great interest is the prevailing alterna-
tion of generations, in which process fixed polyp Stocks give rise to a generation
of free-swimming Medusae, the eggs of which develop in turn into polyps.

1 Huxley, T. II., The Oceanic Hydrozoa. London, 1859. — Agassiz, A., North American Aca-
lephae. 111. Cat, Museum Comp. Zool. Cambridge ii., 1865. — Ilincks, T., Natiiral History of the
British Hydroid Zoophytes. London, 1868. — Claus, C, Untersuchungen über die Organisation, etc.,
der Medusen. Leipzic, 1883.

I.^„

HYDROMEDUSAE

119

The Ilydrozoa are all aquatic, and with few excepfcions are inhabitants of
the sea. They are commonly divided into the two following sub-classes : —
Hydromedusae and Acalephae.

Subclass 1. HYDROMEDUSAE Vogt.

Sessile or free-swimming, usually hranching colonies, with dimorphic, nutritive and
reprodudive polyps ; the latter frequently become liberated in the form of small, free-
swimming Medusae, with non-lobate umbrellas composed of a hyaline, gelatinous
substance.

Six Orders af Hydromedusae are recognised : Hydrariae, Hydrocorallinae,
Tubulariae, Campanidariae, Trachymedusae and Siphonophorae. Of these only
the Hydrocorallinae, Tubulariae and Campanulariae secrete calcareous or
chitinous structures capable of preservation in the fossil State.

Order 2. HYDROCORALLINAE Moseley.i

Naked polyps secreting at the base a dense calcareous skeleton, traversed at intervals
by two series of vertical tubes, into which the dimorphic zoöids can be retracted.

The Hydrocorallinae comprise the two Recent groups Milleporidae and Stylas-
teridae, which were univereally regarded as true corals until Louis Agassiz and
Moseley proved their relation-
ship to the Hydrozoa.

Millepora Linn. (Fig. 185).
Massive, foliately expanded,
encrusting or branching poly-
paria (coenosteum), often attain-
ing considerable size. Upper
surface punctured by round
openings of the larger tubes
(gastropores), between which
are the mouths of numerous
smaller tubes (dactylopores).
The skeleton is composed of
a network of anastomosing
calcareous fibres, traversed by
a System of tortuous canals.
The gastropores lodge the larger, nutritive polyps, and the dactylopores the
smaller, food-procuring zooids ; the latter have no mouths, but are provided
with short, clavate tentacles on their sides, and their tubes communicate with
the vermiform canals. Zooidal tubes tabulate, but nonseptate. The genus
is an important reef-builder of the present day, but occurs only sparsely in
the fossil State. Earliest known forms appear in the Eocene.

1 Literature : Allman, J. G., Moiiograph of the Gymnoblastic or Tubularian Hydroids. Ray
Society, 1871-72. — Moseley, II. N.. Philosopliical Transactions Royal Society, vol. 167, 1878, —
Steinmann, G., Über fossile Hydrozoen aus der Familie der Coryniden. Palaeontographica, vol.
XXV., 1877. — Idem, Über triasische Hydrozoen vom östlichen Balkan. Sitzber. Akad. Wiss.
Wien, math. -phys. Classe, vol. cii.,1893. — Canavari, M., Idrozoi Titoniani appartenanti alla Faraiglia
delle Ellipsactinidi. Mem. Comitato Geol. vol. iv., 1893. — Vinassa de Regny, 0. A'., Studii sulle
Tdractinie fossili. Mem, Accad. dei Lincei, 1899, ser. 6, vol. iii.

Fio. 185.

Millepora nodosa Esp. Receiit. A, Upper surface of coeno-
steum, showing gastropores, k, and dactylopores c, -lo/j. B,
Vertioal section, k, gastropores with tabulae, t ; c, Vermiform
canals communicating with dactylopores, 80/j (after Steinmann).

120

COELENTERATA— HYDEOZOA

PHYLUM II

Stylaster Gray. Branching polyparia composed of a network of fibrous,
rose-coloured coenenchyma, in which are situated calicular depressions that are
provided with pseudosepta and columellae, and communicate with the zooid
tubes and vermiform canals. Recent, and occurring sparsely in the Tertiary.

Order 3. TUBULARIAB AUman.

Polyp Stocks which are either nahed or covered with chitinous outer layer (periderm).
Both the polypoid nutritive zooids, and also the medusoid reproductive animals are
without cup-shaped hydrothecae surrounding the polyp head. A chitinous or calcareous
skeleton (hydrophyton) is frequently secreted at the hase.

Hydractinia v. Bened. (Fig. 186). Hydrophyton in the form of encrusting,
chitinous, rarely calcareous expansion, frequently investing gastropod shells.
The crust consists of successive, slightly separated, horizontal laminae, which

l

^-

are supported by num-
erous vertical rods or
columns {radial pillars).
The surface is covered
with projecting hollow
spines and tubercles,
and is also traversed
by shallow, branching
grooves {astrorhizae).
Interlaminar spaces
communicating with
the surface by means
of rounded tubes.
Tertiary and Recent.

Ellipsactinia Steinm.
Hydrophyton irregu-
larly ellipsoidal, com-
posed of thick, con-
centric, slightly separ-
ated, calcareous lam-
ellae, which are united
by sparsely distributed
vertical columns.
Lamellae are formed by the anastomosis of exceedingly delicate calcareous
fibres, punctured by numerous fine radial tubes, and furnished on both sides
with pits, tubercles and branching furrows. Upper Jurassic (Tithonian) ;
Alps, Carpathians and Apennines.

Sphaeractinia Steinm. Like the preceding, but composed of thin, widely
separated lamellae, which are supported by numerous radial pillars. Centre
frequently occupied by a foreign body. Upper Jurassic (Tithonian).

Loftusia Brady (Fig. 187). Ellipsoidal or fusiform bodies, composed of
thin, concentric or spirally rolled calcareous lamellae. Interlaminar spaces
wide, intersected by numerous radial pillars, and often secondarily filled with
calcareous mud. Eocene ; Persia.

Parkeria Carp. Globular or walnut - shaped organisms with nodulated

Fig. 186.

A, Hydractinia echinata F\em. Recent; North Sea. Portion of commensal
colony, greatly enlarged ; hy, Polyps (hydranths) ; go, Generative buds (gono-
phores) ; hph, Hydrophyton adherent to shell of Buccinium undatum, and
showing reticulated structure in vertical section. B, Hydractinia calcarea
Gart. Vertical section of hydrophyton, greatly enlarged (after Carter) ; a,
Primary basal lainella ; h, Interlaminar space ; c, Second lamella ; d, Radial
pillars between the lamellae ; e, f, Tubercles and spines projecting on upper
snrface. C, Hydractinia pliocaena Allm. Pliocene ; Asti, Italy. Hydro-
phyton encrusting on Nassa shell (natural size). D, Portion of magnified
surface of the latter, showing branching grooves and wart-like tubercles.

CLASS II

TUBULARIAE

121

exterior, and composed of rather thick, concentric, calcareous lamellae. Inter-
laminar Spaces divided into chamberlets by stout radial pillars, which usually
extend continuously through a number of lamellae. Both lamellae and pillars
consistof minutely tabulated tissue, the tubules of which are radial in arrange-
ment. Centre frequently occupied by a foreign body. Cambridge Greensaiid
(Cenomanian).

The genera Parkeria and Loftusia were originally described as agglutinated
Foraminifera ; they are, however, manifestly very closely allied to Ellipsaäinia
and Sphaeractinia.

Porosphaera Steinm. (Fig. 188). Globular masses of the size of peas or
hazel-nuts frequently growing around some foreign body, and composed of
anastomosing calcareous fibres which are penetrated by
numerous radial tubules ; the latter open on the surface
in the form of large pores, around which radial or stel-
late furrows (astrorhizae) are sometimes grouped. Upper
Cretaceous.

Fio. 187.

Fig. 188.

Porosphaera glöbularis
(Phill.). Upper Cretace-
ous ; Rügen. A, Skeleton,
natural size ; l, Cavity
originally occupied by
foreign body, B, Trans-
verse section showing

Loftusia persiraBrady. Eocene ; Persia. yl, Specimen cut open to showgeneral radial tubes of gastro-
structure, natural size (after Brady). B, Section showingitwo lamellae and inter- pores, 2/j (after Stein-
laminar Alling, greatly enlarged. mann).

Stoliczkaria Duncan. Trias ; Karakoram and Balkan Mountains.

Cydoporidium, PMzoporidium Parona. Cretaceous. Poraäinia and Cyclac-
tinia (Kerunia Mayer-Eymar) Yinassa. Tertiary.

Heterastridium Reuss (Syringosphaeria Duncan). Includes spheroidal, nodular
bodies of considerable size, composed of slender, anastomosing, and more or
less distinctly radial calcareous fibres. Skeleton comparatively dense, but
perforated by two series of zooidal tubes appearing superficially as pores. The
apertures of the larger tubes are round, those of the smaller stellate, and are
surrounded by radial furrows. Alpine Trias.

Appendix to the Hydrocorallinae and Tubulariae.

Stromatoporoidea Nicholson and Murie.^

Closely allied to the Hydrocorallinae and Hydractinia are the extinct Stromato-
poroidea, which combine in many respects the characters pertaining to both of

^ Bargatzki, A., Die Stromatoporen des rheinischen Devons. Bonn, 1881. — Nicholson, H. A.,
Monograph of the British Stromatoporoids. Palaeont. Soc. 1886-92.— (Jir^y, G. H., Revision of
the Sponges andCoelenterates of the Lower Helderberg Group of New York. 14th Ann. Rept. N.Y.
State Geol., I^'d^. — Tornquist, A., Über mesozoische Stroniatoporiden. Sitzber. preuss. Akad.
Wiss., 1901, vol. xlvii. — Yabe, H., On a Mesozoic Stromatopora. Jouru. Geol, Soc. Tokyo, 1903,
vol. X. — Beninger, K., Einige neue Tabulaten und Hydrozoen aus mesozoischen Ablagerungen.
Neues Jahrb. f. Mineral, i., 190Q.—Rothpletz, A., Über Algen und Hydrozoen im Silur von

122

COELENTERATA— HYDEOZOA

PHYLUM II

the above-named groups, but whose exact position in the zoological System
remains as yet uncertain. During the Paleozoic era, to which they are con-
fined, the Stromatoporoids were important geological agents, whole beds of
limestone being often essentially constituted of their remains. In the Mesozoic
era they are replaced by very closely allied forms of Hydradinia, which in all
probability represent their immediate descendants.

The Stromatoporoids secrete hemispherical, globiüar, nodular or hori-
zontally expanded skeletons, which are sometimes encrusting, sometimes
attached by a short basal peduncle, and are covered on the under side with
concentrically wrinkled epitheca, while the apertures for the emission of the
polyps are situated on the upper surface. The general tissue of the coenosteum
is composed of numerous, concentric, undulating, calcareous layers or laminae,
which are separated by narrower or wider interlaminar Spaces, but are at the
same time connected by numerous vertical rods {radial pillars). The pillars
as well as the laminae are traversed, as a rule, by minute, irregularly directed
j ß canaliculi. In some

genera the coenosteum
is provided with verti-
cal tabulate tubes,
which most probably
served for the recep-
tion of the polyps, as
in the genus Millepora ;
but in many instances
they are wanting. The
surfaces of the laminae
typically exhibit pores
and small tubercles,
and frequently also
shallowstellate furrows
(astrorhizae), which radiate outwards from numerous centres. Sometimes the
laminae consist merely of a loose network of horizontal calcareous fibres.

Goldfuss at first held the Stromatoporoids occurring so profusely in the
Eifel for corals (Millepora), and subsequently for sponge-like zoophytes ; while
von Rosen considered them as horny sponges that had become secondarily
calcified. Sandberger and F. Roemer assigned them to the Bryozoans ;
Dawson to the Foraminifera ; Sollas to the siliceous sponges {Hexacünellida) ;
and Salter to the calcareous sponges, whose example Nicholson also followed.
Lindström, Carter and Steinmann subsequently pointed out their relations
to Hydradinia and Millepora ; and Nicholson and Murie came finally to
regard them as a group of extinct Hydrozoans allied to Hydradinia on the
one band (Actinostromidae), and Millepora on the other (Stromatoporidae
and Idiostromidae).

Adinostroma Nich. (Fig. 189). Skeleton having vertical or radial pillars
disposed at tolerably regulär intervals, and extending continuously through all

Gotland und Ösel. K. Svenslc. Vetensk. Akad. Handl., 1908, vol. xliii. — Gürich, G., Les Spongio-
stromides du Visedansle Province de Namur. Mein. Mus. Roy. d'Hist. Nat. Belg., 1906, vol. iii.
— Idem, Neues Jahrb. f. Mineral., 1907, i. — Parona, C. F., La Fauna coralligena del Cretaceo dei
Monti d' Ocre nell' Abruzzo Aquilano. Mem. Conim. Geol. Ital., 1909, vol. w.— Parks, W.^A., The
Stromatoporoids of the Guelph Formation in Ontario ; the Niagara ; the Silurian of America ; the
Ordovician. Univ. of Toronto Studies, Nos. 4-7, 1907-1910.

Fig. 189.

Actinostroma intertextum Nich. Silurian (Wenlock) ; Shropshire. A,
Tangential section showing radial pillars and reticulated structure of con-
centric laminae. B, Vertical section, showing formation of laminae from
processes given off horizontally by radial pillars, 12/1 (after Nicholson).

|^p>ASS II

STROMATOPOROIDEA

123

or at least a considerable number of laminae ; in vertical sections, accordingly,
exhibiting a quadrate meshwork. The laminae consist of an anastomosing
network of calcareous fibres, generally having a porous structure; their surfaces
are covered with projecting granules or tubercles, which represent the free
Upper ends of the vertical pillars. Rare in the Silurian, but very abundant

Fic. l'JO.

Stromatopora tuberculata Nich.
(Corniferous limestone) ; Jarvis,
Natural size (after Nicholson).

Devon ian
Ontario,

Fin. 191.

Cmmopora placenta Phill. Devonian ; Torquay,
Devonshire. A, Tangential section, natural size.

B, The same, highly magnified ; a, Vertical " Cauno-
pora tube " ; h, Canal partially cut into ; c, Calcare-
ous fibres traversed by delicate ramifying canaliculi.

C, Vertical section, highly magnified.

in Devonian of the Eifel, England and North America. A, clathratum Nich.
{ = Stromatopora concentrica p. p., Goldf.).

Clathrodidyon Nich. Like the preceding, but with radial pillars extending
only between the upper and lower surfaces of successive laminae. Character-
istic of Silurian ; rare in Devonian.

Stromatopora Goldi. emend. Nich. (Pachystroma ^ich. and Murie) (Fig. 190).
Radial pillars uniting with the thick concentric strata or latilaminae to form a
finely reticulated tissue, in which tabulate zooidal
tubes are sparsely distributed. Plentiful in Devon-
ian ; less common in Silurian.

Caunopora Lonsdale (Fig. 191), and Diapora
Bargat., are Stromatoporoids which are indis-
tinguishable from other genera except by the
presence of numerous definitely walled tubes pene-
trating the coenosteum at closer or remoter in-
tervals. The tubes are often thick-walled, are
furnished with horizontal or funnel-shaped tabulae,
and occasionally with septal spines ; in many cases
they evidently represent the corallites of Aulopora
and Syringopora colonies, which have become en-
veloped, but have continued to live commensally

within the tissues of the Stromatoporoid. In other cases, however, the tubes
appear to have been formed by true Stromatoporoid polyps. Devonian.

Hermatostroma Nich. (Fig. 192). Massive or foliaceous skeletons, composed
of thick parallel latilaminae, connected by vertical pillars ; pillars often running
continuously through several concentric laminae. Roth pillars and laminae
exhibit a dark median line when viewed in cross-section, indicating either the
presence of axial canals or composition out of two lamellae. Devonian.

Fio. 192.

Hermatostroma sp. ind. Devonian ;
Torquay, Devonshire. a, Hori-
zontal lamina composed of two
slightly separated lamellae ; b,
Interlaminar chamberlet ; c, Radial
pillar traversed by axial canal.

124 COELENTERATA— HYDROZOA phylüm ii

Idiostroma Winch. Coenosteum cylindrical or fasciculate, traversed by
axial, tabulate zoöidal tubes, which give off secondary lateral tubes. General
tissue reticulated, similar to Stromatopora. Devonian.

Labechia E. and H. Ordovician and Silurian ; North America and Europe.

Stylodidyon, Stromatoporella and Syringostroma Nich. ; Amphipora Schulze ;
Stachyodes Bargat. Devonian of Europe and North America.

A number of genera are described by Waagen and Wentzel from the
Permo-Carboniferous rocks of Farther India, such as Carterina, Disjedopora,
Circopora, etc. Probably in the same neighbourhood should be placed several
peculiar encrusting marine forms from the Carboniferous of Belgium, described
by Gürich under the names of Aphrostroma, Spongiostroma, Chondrostroma,
Malacostroma, etc. The first-named of these occurs also in the Silurian of
Gotland, and was associated by Gürich with the Foraminifera.

Order 4. CAMPANULARIAB AUman.

(Leptomedusae, Calyptohlastea Allman ; Thecaphora Hincks).

Delicate, branching, plant-like, sessile coloiiies, with chitinous periderm enveloping
the base, pedunde, and also the cup-like receptades (hydrothecae) which endose the
individual polyps. The proliferous zooids are developed within urn-shaped capsules
(gonothecae) of comparatively large size, and sometimes become separated off as free-
swimming velate Medusae.

Recent Campanularians, such as are comprised by the families Sertularidae,
Plumularidae and Campanularidae possess durable hard parts, but nevertheless
their remains have not as yet been found in the fossil State, with the exception
of a few forms from Pleistocene deposits.

Range and Distribution of the Hydromedusae.

Of those members of this group in which the preservation of structural
parts is at all possible, the Hydrocorallinae have been recognised with
certainty as early as the Upper Cretaceous. During the Tertiary they
became more widely distributed, and at the present day are important reef-
builders.

During the Upper Jura, and notably in Tithonian beds of the Mediter-
ranean region, certain genera of the Hydractinidae {Ellipsadinia, Sphaeradinia)
are abundantly represented. Contrariwise, other Tubularians, such as the
Triassic Heterastridium, and Parkeria and Porosphaera from the Cretaceous of
central Europe, occur only sparsely.

The extinct organisms known as Stromatoporoids were extremely
important rock-builders during the Paleozoic, much of the limestone of the
Silurian and Devonian Systems resulting from the destruction of the reefs
built by these fossils. Their massive Stocks sometimes attain gigantic size.
Stromatoporoid remains are profusely distributed in Ordovician and Silurian
rocks of North America, England and Russia, also in the Middle Devonian of
the Eifel and Ardennes, and in equivalent strata of Nassau, Devonshire, the
Urals, Spain, etc. Except for a few rare survivors, the group does not
Continus beyond the Paleozoic era.

CLASs II GKAPTOLITOIDEA 125

■

Appendix to the Hydromedusae.

Olass or Subclass. GRAPTOLITOIDEA Lapworth.i

{Rhabdophom Allman.)

Under the term of Graptolitoidea are included organisms which have been
considered by various authors as plant remains, horny sponges, Pennatulidae,
Cephalopods and Bryozoans. Portlock, in 1843, first pointed out their
analogy with the Sertularians and Plumularians ; and his inferences as to
their genetic relationship were afterwards confirmed by the painstaking
researches of Allman, Hall, Hopkinson, Lapworth, Nicholson, and others.
More recently, however, their kinship has been denied by Neumayr and
Wiman, who, on account of the bilateral symmetry of the sicula and thecae,
claim that Graptolites cannot be included within any of the now existing
classes of organisms.

Graptolites are generally found in an imperfect state of preservation, lying
flattened in the same plane upon the slaty laminae in which they are embedded,
and associated in large numbers. More rarely they occur in limestone, when
the internal cavities are filled with calcareous matter, and the original form
accurately preserved. Such specimens have been successfully etched out and
investigated under the microscope by Holm and Wiman.

The general skeletal tissue (periderm) was obviously flexible, and composed of

^ Literature : Hall, J., Palaeontology of New York, vols. i., iii., 1847, 1859. — Graptolites of
the Quebec Group. Cauad. Organic Remains, dec. ii. Geol. Surv. Cauad., 1865. — lutroduction to
the study of Graptolites. 20th Ann. Rept. N.Y. State Gab. Nat. Hist., 1868.— Barrande, J., Grapto-
lites de Boheme. Prague, 1850. — 8uess E., über böhmische Graptolithen. Haidinger's Naturw.
Abhandl., 1851, vol. iv. — Scharenherg, PF., Ueber Graptolithen. Breslau, 1851. — Geinitz, H. B.,
Die Versteinerungen der Grauwackenformation in Sachsen, Leipzic, 1852. — Die Graptolithen des
mineral. Museums in Dresden, 1890. — Richter, R., Thüringische Graptolithen. Zeitschr. Deutsch.
Geol, Ges., vols. v., xviii., xxiii., 1853, '66, 71. — Nicholson, II. A., Monograph of the British
Graptolitidae, 1872. — Lapworth, C, Notes on the British Graptolites. Geol. Mag., vols. x., xiii.,
1873, '76. Also various articles in Quart. Journ. Geol. Soc, 1875, '78, '81, and Ann. Mag. Nat.
Hist., 1879, '80.— On the Graptolites of County Down. Ann. Rep. Belfast Nat. Field Club, 1877,
vol. i., pt, iv, — Tullberg, S. A,, On Species of Didymograptus. Geol. För. Stockholm Förh,, 1880,
vol. v. — Spencer, J. W., Graptolites of the Upper Silurian System. Bull. Mus. Univ. Missouri, 1884.
— Tornquist, S. L., Observations on Graptolites. Acta Univ. Lund, 1890-92, vols. xxvii.-xxix. —
Holm, G., Skandinaviens Gi'aptoliter. Svensk, Vetensk. Akad. Förh., 1881, vol. xxxviii. — Gotland's
Graptoliter. Bihang Svensk. Vetensk, Akad. Handl. 1890, vol. xvi. — Barrois, C, Memoire sur la
distribution des graj)tolites en France. Annales Soc. Geol. Nord, 1892, vol. xx.— Wiman, C, Über
Monograptus und Diplograptidae. Bull. Geol. Inst. Upsala, 1893, vol. i. (English translatiou in
Journ. Geol., 1893, vol. ii.). — Tornquist, S. L., Observations on the Structure of some Diprionidae.
Fisiogr. Sällsk. Handl., 1893, '97, vols. iv., viii. — Researches into the Graptolites of the Scanian and
Vestrogothian Phyllo-Tetragraptus Beds. Lunds Univ. Arsskrift, 1901, vol. xxvii. — Ferner, J.,
liltudes sur les graptolites de Boheme. Prague, 1894-99. — Holm, G., Om Didymograptus, Tetra-
graptus och Phyllograptus. Geol. För. Förh., 1895, vol. xvii. No. 164. — Ruedemann, R., Synopsis of
the Mode of Growth and Development of the Genus Diplograptus. Amer. Journ. Sei. (3), 1895, vol.
xlix. ; Also in Ann. Rept. N.Y. State Geol. 1894, and Amer. Nat., 1897, vol. xxxii. — Graptolites of
New York, N.Y. State Museum. Memoirs vii. 1904, and xi., 1908. — Gurley, R. R., North American
Graptolites. Journ. Geol., 1896, vol. iv. — Wiman, C, Über die Graptolithen. Bull. Geol. Inst.
Up.sala, 1895, vol. ii. ; also Nat. Sei., 1896, vol. ix., and Bull. Geol. Inst. Upsala, 1897, No. 6. 1900,
No. 10. — EUes, G. L., and Wood, E. M. R., Monograph of British Graptolites, ed. by C.
Lapworth. Palaeontogr. Soc, 1901 to date. — Hall,T. S., Note on the Distribution of the Graptolitliidae
in the Rocks of Castlemaine. Rept. Austral. A.ssn. Adv. Sei., 1894 ; also Proc. Roy. Soc. Victoria
1892, '97, '98, '99 ; Geol. Mag,, 1899, vol. vi.—Roemer, F., and Frech, F., Lethaea Palaeozoica, 1897,
vol. i. — Bassler, R. S., Dendroid Graptolites of the Niagarau Dolomites at Hamilton, Ontario.
Bull. Smithson. Inst., No. 65, 1909. — Westergard, A. H., Studier öfver Dictyograptus.skiffern. Med.
fr. Lunds Geol. Fält Klub. Ser. B, No. 4, 1909.

126 COELENTERATA— HYDROZOA phylum ii

smooth or fiiiely striated chitine ; usually it has the form of a dense continuous
membrane, but in the Retiolitidae it is attenuated and supported by a latticed
network of chitinous threads. It is usually preserved as a thin bitumino-
carbonaceous film, which, however, is often infiltrated with pyrites, and is not
infrequently replaced by a glistening greenish-white Silicate (Gümbelite).

The Compound organism or rhabdosome ('^ polypary ") of the Graptolites is
usually linear, more rarely petaloid in form, undivided or branching, and is
either straight, beut, or in exceptional instances spirally enrolled. These
rhabdosomes, each of which originates from a sicula (see below) may again be
united into colonies of a higher order (synrhabdosome). Cup-shaped rhabdo-
thecae, which are usually obliquely set and more or less overlapping, are borne
on one or on both sides of the polypary, and are united by a common
coenosarcal canal enclosed in the /periderm. The polypary is in later forms
strengthened by a peculiar chitinous axis (virgula, solid axis), which in the
Monograptidae runs in a groove lying outside the coenosark on the dorsal side
of the organism {i.e. on the side opposite to the theciferous margin). But in
the biserial Graptolites the virgula is either enclosed between the laminae of
a central or sub-central septum, which is formed by the coalescence of the
flattened dorsal walls (Biprionidae) ; or it is double and the two virgula (see
text Fig. 209) are placed on opposite sides of the coenosark, and are united with
the peridermal network {Retiolitidae).

Springing from the common canal, is a series of thecae {celhles, denticles), which
are disposed in longitudinal rows along either one (Fig. 193), two (Fig. 194)
or four sides of the polypary. They usually have the form of elongated,
cylindrical, rectangular or conical sacs; their walls are in most cases applied
to those of their neighbours above and below, although occasionally they
spring out quite isolated from one another. Each theca opens directly into
the common canal, and is furnished distally with an external aperture, the
form and size of which vary extremely in difFerent species. In some forms it
is circular or quadrate or introverted or introtorted ; in others it is contracted.
Not infrequently the outer lip is ornamented with one or two slender spines,
which often subdivide and inosculate with one another. The form of the
thecae and apertures has been employed by Lapworth to define families and
subfamilies.

The polypary in most Graptolites is furnished at its proximal end with a
minute, triangulär or dagger-shaped, originally conical, body called the sicula
(Fig. 195), which represents the original embryonic skeleton and is suspended
from an originally tubulär filament, the 7iema oy nemacaulus {Fig. 196). In the
wall of the sicula is formed, in the later Graptolites, an axis or rod, the
virgula, which extends through the rhabdosome. Rhabdothecae are then
budded either uniserially along one side, or in alternate sequence along both of
the lateral margins of the sicula, originating from one theca near the major end
of the sicula. They grow either laterally away from the sicula (Axonolipa) or
along the nemacaulus (Axonophora). The sicula itself ceases to grow, as a
rule, after the first thecae are budded, and sometimes it becomes obsolete or
absorbed. Sometim^es the rhabdosome remains undivided, sometimes it forms
branches, which may diverge at various angles ; in other cases two or four
uniserial polyparies may be placed back to back with their dorsal walls
coalescing, thus giving rise to di- or tetra-serial colonies. In the latter types
the coenosarc is commonly divided by one or two median septa.

I

GRAPTOLITOIDEA

127

Graptolites commonly occur in argillaceous schists, moie rarely in limestone
formations, of the Upper Cambrian, Ordovician and Silurian Systems. They
seem to have swarmed in the muddier portions of the sea, and floated either
attached to sea-weeds, etc., or as free-swimming colonies ; or, in rarer instances,
remained stationary with the sicula or a root embedded in the mud, or attached
to foreign bodies. They are divided into two Orders : Dendroidea Nicholson
{Cladophom Hopkinson), and Graptoloidea Lapworth, or Graptolites proper. The

:^"^?-

Fig. 195.

a, Münograptus gregarius Lapw. Sil-
urian ; Dobbs, Linn, Scotland. Proxiinal
end showing sicula, enlarged ; b, Didy-
mograptus pennatulus Hall. Ordovician
(Quebec Group) ; Point L6vis, Canada.
Proximal end .showing sicula, enlarged
(after Lapworth).

Fig. 193.

A, C, Monograptus priodon
(Bronn). Silurian (Etage E);
Prague. A, Rhabdosoma,
natural size. B, Longitudinal
section, enlarged. C, Dorsal
aspect, enlarged. D, Mono-
graptus hnhemicus Barr. Same
locality. a, Virgula ; c, Com-
mon canal ; th, Thecae ; x,
External aperture (after
Barrande).

Fig. 194.

a, c, Climacograptus typicalis
Hall, Ordovician (Trenton
limestone) ; Cincinnati, Ohio.
a, Vertical section, enlarged,
showing central virgula ; b,
Individnal of the natural size ;
c, Cross-section, enlarged ; d, e,
Diplograptus palmeus Barr.
Silurian ; Prague. Rhabdo-
soma of the natural size and
several times enlarged (after
Barrande) ; /, Diplograptus
foliaceus Murch, Ordovician
(Llandeilo Group); Scotland.
natural size (after Lapworth).

Fig. 196.

Dictyonema cavernosum Wiman. Or-
dovician ; Gotland. Proximal end of
rhabdosome with adhesion disk (x), large
nourishing individnal (z), and sniall
budding individnal or gonangium (zi).
3/i (after Winian).

latter are again divided into two suborders : AxonoUpa Frech, redefined by
Ruedemann, without axis or virgula; and Jxonophai-a Frech, limited by
Ruedemann, with an axis. ^

Order 1. DENDROIDEA Nicholson.

Family. Dendrograptidae Roemer.

This family, which includes all dendroid forms, is represented during the
older Paleozoic by the genera Deiidrograptus, Dictyonema, Desmograptus, Gallo-

128

COELENTERATA— HYDROZOA

PHYLUM II

gmptus and Ftilograptus. Their polyparies are finely branching and plant-like
in appearance, sometimes furnished with a strong foot-stalk, in other cases
terminating acutely at the base. The original substance was undoubtedly
chitinous. In well-preserved specimens are seen on one or occasionally on
both sides of the branchlets numerous small cellules or thecae, in which
evidently the zooids were seated. These thecae have been shown by Wiman
to be of threefold character, some of them having lodged nourishing, others
budding and others sexual individuals or gonangia. Very often the branches
of the dendroid rhabdosome are united by numerous delicate processes or

Dendrograptus Hall. Rhabdosome consisting of a strong main stem and a
broad, spreading, shrublike, variously ramifying frond. Thecae commonly

Fig. 197.
Didyonema fläbelliforme (Eichw.). Upper Cambrian; Rensselaer County, N.Y. A, Sicula with very long
neina, x =Vi- -ß» Mature rhabdosome with adhesion stem, x ^/i (after Ruedemann).

obscure, but sometimes distinct and angular, or they may occur as round or
elliptic pits or pustules, Cambrian to Silurian.

Ftilograptus Hall. Rhabdosome with branches giving ofF branchlets
alternately on opposite sides, the general habit being suggestive of Recent
hydrozoans. Ordovician and Silurian ; eastern North America.

Didyonema Hall {Didyograptus Hopkinson) (Figs. 196, 197). Ehabdosomes
forming funnel or fan-shaped fronds, composed of numerous bifurcating
branches arising from an acute base, and united at intervals by fine dissepi-
ments. Thecae with complicated appendages, their branches supporting three
kinds of individuals, nourishing, budding and sexual. Cambrian to Car-
boniferous ; especially abundant in Ordovician of Norway, but usually com-
pressed into a basket-like network.

Desmograptus Hopkin. Differs from the preceding in the flexuous char-
acter of the branches, which coalesce at intervals ; dissepiments chiefly in
lower part of the frond. Ordovician to Devonian ; Europe and North
America.

CLASS II

HYDEOZOA— GRAPTOLITOIDEA

129

Order 2. GRAPTOLOIDEA Lapworth.
Suborder A. AXONOLIPA Frech (emend. Ruedemann).
Family 1. Dichograptidae Lapworth.
Uniserial Graptolitoidea tvith bilateral rhabdosome ; brauch es dichotomous ; thecae

simple^ sub-cylindrical.

Dichograptus Salter (Fig. 198).

Rhabdosome consisting of eight simple

Fia. 199.

Tetragraptus hryonoides Hall.
Ordovician ; Point L6vis, Canada
(after Hall).

Fig. 200

Didymograptus pennatulus Hall.
Ordovician ; Point L^vis, Canada
(after Hall).

Fig. 198.

Dichograptus octobracMatus Hall. Ordovician (Quebec
Group) ; Point L^vis, Canada (after Hall).

Fio. 202.

Didyynograp' l'hyllograjnus typv,n Hall.
t)is murchisoni Ordovician (Quebec Group);
Point L^vis, Canada. a, Several
polyparies of the natural size ;
b, Ideal cross-section, enlarged
(after HaH).

(Beck). Middle
Ordovician
(L 1 a n d e i 1 0
Group) ; Wales.

uniserial branches which are produced by repeated dichotomy, and their bases
often enveloped in a central corneous disk. Ordovician.

Tetragraptus Salter (Fig. 199). Rhabdosome consisting of four uniserial
branches which are produced by twice repeated dichotomous division.
Ordovician.

Didymograptus M'Coy (Figs. 195, J; 200; 201). Rhabdosome consisting of
two symmetrical branches diverging from a small primary cell (sicula) at
various angles. Thecae obliquely directed, having the form of flattened
rectangular prisms, and in contact with one another throughout. Ordovician.

Phyllograptus Hall (Fig. 202). Rhabdosome leaf-like, composed of four

VOL. I K

130 COELENTERATA phylum ii

uniserial rows of prismatic thecae coalescing along the whole length of their
dorsal margins ; the entire structure resembling Tetragraptus with the four
branches grown together, each two back to back and forming a cross in
transverse section. Ordovician.

Family 2. Leptograptidae Lapworth.

Uniserial, flexuous, bilateral rhabdosomes, with simple or Compound lateral
branches; thecae with a slightly sigmoid curvature,
apertures inclined, somewhat introverted.

Leptograptus Lapworth. Rhabdosome consist-
ing of two long, filiform, bilaterally symmetrical
branches. Ordovician.

Nemagraptus Emmons {Coenograptus Hall) (Fig.

203). Two primary branches originating from the

Fir.. 203. centre of a triangulär sicula, more or less flexed,

Coenograptus iiraciiis Hall. Orrio- and giving off simplc branches from the convex

cian- ""•■"'' ^"■"- ''" '■■ '■'""•- CO

Hall).

vician : Point Levis, Ciinada (after •!. '.i i-^ ^ r\ ^ ' •

sideatapproximately regulär intervals. Ordovician

Family 3. Dicellograptidae 'Lapworth.

Uniserial or uni-biserial Graptoloidea. Thecae tubulär, with conspicuous
sigmoid ventral curvature. Apertures situated in excavations and frequently intro-
verted and introtorted.

Dicellograptus Hopk. Rhabdosome bilaterally symmetrical, consisting of
two uniserial branches diverging from the sicula at angles ex-
ceeding 180 degrees. Ordovician.

Dicranograptus Hall (Fig. 204). Rhabdosome Y-shaped, com-
posed of two symmetrically developed branches which are
coalescent in the proximal and free in the distal portion of
their length. Ordovician.

Suborder B. AXONOPHORA Frech (emend. Ruedemann).
Family 1. Diplograptidae Lapworth.
Biserial Graptolitoidea with rectilinear rhabdosomes. pjo 204.

Climacograptus Hall (Fig. 205, a, c). Rhabdosome bilaterally ramZT^Tl^i.
symmetrical. Thecae tubulär, ventral walls sigmoidally curved, ^Hudson mip^v
apertural margin horizontal, situated within a well-defined ex- New York (after
cavation. Ordovician and Silurian.

Diplograptus M'Coy (Figs. 205, d-f ; 206). Rhabdosome bilaterally sym-
metrical, rectangular, concavo-convex or tabular in section. Thecae mostly
sub-prismatic, ventral walls inclined and straight. Subgenera : Orthograptus
and Glyptograptus Lapworth ; Mesograptus Elles and Wood ; Petalograptus
Suess ; Cephalograptus Hopkinson. Ordovician and Silurian.

Family 2. Glossograptidae Lapworth.

Biserial Graptoloidea with straight rhabdosomes, fest attenuated, with framework
of strengthening ßbres. Thecae of Diplograptid type, provided with spurs and other
processes which often form an external lacework.

Glossograptus Emmons (Figs. 207, 208). Rhabdosome having lingulate

CLAss n HYDROZOA— GRAPTOLITOIDEA 131

outline and rounded extremities, ornamented with two rows of isolated spurs ;

Fig. 205.

a, c, Cliiruicograptus typicalis Hall. Ordovician (Tren-
ton limestone) ; Cincinnati, Ohio ; a, Vertical section,
showing common axis in the centro, enlarged ; 5, Poly-
paiy of the natural size ; c, Cross-section, enlarged.
d, e, Di'plo(}raptus jmlmeus Barr. Silurian ; Prague ; d,
Polypary of the natural size ; e, Polypary enlarged.
/, Diplograftus foliaceus Murch. Silurian (Llandeilo
Group) ; Scotland. Natural size.

Fio. 206.

Diplograptus foliaceus Hall.iUtica shale (Ordovician);
Dolgeville, New York. Synrhabdosome showing
central organs and primary disk (hl) with funiculus
(/), to which the rhabdosomes (r) are attached by a
slender nemacaulus (n). Gonangia (f/) with young
siculae (s) are also present. x % (after Ruedeniann).

Fkj. 207.
Glofisogriiptus (luadrimiicronatus Hall var. approximatus
Rued. Utica shale (Ordovician) ; Dolgeville, New York.
Synrhabdosome. x Vi (after Ruedeinann).

Fio. 20S.

Glossograptus quadrimucronatus (Hall)
var. apjyroximatus Rued. Utica shale
(Ordovician) ; Dolgeville, New York.
Young synrhabdosome showing central
disk and siculae. x »/i (after Ruedeniann).

each theca with two long spines. Ordovician. lletiograptus Hall ; Lasiograptus
Lapworth. Ordovician.

132

COELENTERATA

PHYLUM II

Family 3. Retiolitidae Lapworth.

Biserial Graptolitoidea with straight rhahdosomes, the latter characterised hy a
neiwork of delicate chitinous tracery (reticula) which forms the outward covering of
the walls of the thecae.

RetioUtes Barr. (Fig. 209). Rhabdosome with periderm attenuated and
supported on a meshwork of fibres. Thecae arranged biserially, their apertures

opening outward. Two virgulae attached to
opposite sides, in the median plane. Ordovician
and Silurian. Subgenera : Gladiograptus Hop-
kinson and Lapworth ; Gothograptus Frech.

Family 4. Dimorphograptidae Lapworth.

Uni-biserial Graptolitoidea, in which the proximal
portion is uniserial, hearing thecae of the general
Monograptus type ; the distal portion is biserial with
thecae of the Diplograptid type.

Dimorphograptus Lapworth. Silurian.

Family 5. Monograptidae Lapworth.

Uniserial Graptolitoidea, with simple or Compound,
straight or convex rhabdosome and thecae of varied
form.

^^^- 20^- Monograptus Geinitz {Monoprion Barrande ;

RetioiitesgeinUzianusB.vv. mun^n^ Pomatograptus and Pristiograptus Jaekel) (Figs.

193, 210). Rhabdosomes with only a single
row of thecae, which are in contact, usually
overlapping, their apertures entire or contracted,
often directed downward. Form of the rhab-

A, Specimen from siliceous
Feuguerolles, Calvados ; natural size

B, C, Polyparies from Motala, Sweden.
B, Cross-section. C, Lower end, en-
larged ; calcareous matter dissolved
out by acid. v, Zigzag-shaped virgula ;
■y', Rod-like virgula ; th, Conjoined
walls of hydrothecae ; s', Crossbars

connecting the virgulae ; o, Apertures dosome may be Straight, curved or somctimes

spirally coiled. Silurian and Devonian.

Bastrites Barr. (Fig. 211). Rhabdosome simple, spirally coiled; common
canal very narrow ; distal parts of thecae more or less linear and widely
separated from one another. Silurian. The zonal distribution of species in
Thuringia and Saxony has been worked out in detail by Eisel.

Cyrtograptus Carruthers. Variously branching Monograptidae. Silurian.

Range and Distribution of Graptolites.

Graptolites are excellent index fossils of the older Paleozoic rocks, owing
to their limited vertical ränge, and wide geographical distribution. The
simpler forms, such as are derived by a succession of budding from a primary
sicula (Axonolipa), are especially characteristic of the uppermost Cambrian
and lower half of the Ordovician rocks. The group as a whole becomes extinct
at the close of the Silurian, except for a few stragglers in the Devonian and
Carboniferous. The occurrence of these organisms in rocks of the same age
in all parts of the world is explained by the fact that while some forms were

w

SUBCLASS II

HYDROZOA— ACALEPHAE

133

probably attached to seaweeds, as often in modern hydroids, others were free-
floating or planktonic creatnres.

Remains of Graptolites are profusely distributed in the siliceous schists
and alum slates of the Fichtelgebirge, Thuringia, Saxony and Bohemia.
They are plentiful also in the Harz, in Poland, Silesia, the Baltic Provinces
and the Ural district ; and again in Scandinavia, Cumberland, Wales, the
north of England, Scotland and Ireland, as well as in Normandy, Brittany,
Spain, Portugal, Sardinia and Carinthia. In America they are found ex-

a ' h c quisitely preserved in Newfoundland,

Canada, New York, Virginia, Alabama,
Ohio, Wisconsin, Iowa and Arkansas. They

Fig. 210.

a, Monograptus nilssoni Barr. Silurian (Alum
Schists) ; Gräfenwerth, near Schleitz, Germany;
h, Monograptus colonus Barr. Silurian ; Eliots-
tieid, Scotland, showing sicula (after Lap-
worth) ; c, Monograptus turriculatus Barr. Sil-
urian ; Prague (after Barrande). All figures
natural size.

Fig. 211.

Rastrites Knnaei Barr. Silurian ; Zekko-
witz, near Prague (after Barrande).

are known also in South America (Bolivia), and Australia, and are not un-
common in the drift which Covers the plains of Northern Germany.

According to Lapworth, Graptolites are distributed vertically throughout
six difFerent horizons ; 'the first of these coincides with the Upper Cambrian,
the three foUowing with the Ordovician, and the two uppermost with the
Silurian. The Monoprionidae are especially characteristic of the two Silurian
horizons.

[The discussion of tlie group Graptolitoidea in the present work has been revised by Dr.
Rudolf Riiedemann, of the New York State Geological Survey, at Albany, New York. —
Editor. 1

Subclass 2. ACALEPHAE Cuvier. Scyphomedusae.^

{Discophora Huxley).

Free-swimming, discoidal or bell-shaped Medusae, with downwardly direded mouth,
with gastro-vascular pouches and numerous radial canalSj and having, as a rule, the
margin of the umhrella lobed. Cambrian to Eecent.

The Acalephs or Lobed Jelly-fishes, though frequently of considerable
size, are entirely without hard parts, and therefore are unfitted for preservation

^ Literature : Huxley, T., Memoir on the Anatomy and Affinities of the Medusae. Phil. Trans,,
1849. — K7ier, R., Ueber eine Meduse in Feuerstein. Sitzungsber. Akad. Wiss. Wien, 1865, vol. lii. —
Haeckel, E., Ueber fossile Medusen. Zeitschr. für Wissenschaft. Zool., 1865 and 1870, vols. xv., xvii.
Neues Jahrb. für Mineral., 1866. Jenaische Zeitschr., 1874, vol. viii. System der Medusen, i. and
ii., Jena, \^^0-^\.—Nathorst, A. G., Om Aftryck af Medusor, etc. K. Svenska Vetensk. Akad.

134

COELENTERATA

PHYLUM II

in the fossil state. Nevertheless, under exceptionally favourable conditions,
as, for instance, in the Upper Jurassic Lithographie Stone of Bavaria, and in
the Middle Cambrian shales of British Columbia, impressions of these delicate
organisms are sometimes preserved, which admit of precise determination.

The best preserved and at the same time the most abundant species is
Rhizostomites admirandus Haeckel, belonging to the Acraspedote family of
Rhizostomidae (Fig. 212). Impressions also occur in flinty concretions of the
Upper Cretaceous, which are most nearly referable to the Medusae. Of a
more questionable nature are the organisms occurring in the Cambrian
sandstone of Lugnaes, Sweden, described by Thorrell under the name of

Rhizostomites admirandus Haeck. Lithographie stone ; Eichstädt, Bavaria. 1/7 natural size.
(Missing parts restored'in outline.)

Spatangopsis, but assigned by Nathorst to the Acalephs. In the same strata
also are found those peculiar fucoidal structures known as Eophyton, which are
commonly supposed to be of vegetable origin. Nathorst has brought forward
evidence, however, to show that these may really have been produced by the
trails of Jelly-fishes. Here also should be noticed the forms described by
Nathorst as Medusites, frona the Lower Cambrian of Sweden, and regarded by
this author as casts of the gastric cavity of Jelly-fishes.

In 1898 a valuable monograph on fossil Medusae was contributed by
Walcott, and in 1911 our knowledge of these organisms was increased in
important respects by the same author, as a result of his studies of remarkably
well-preserved specimens from the Cambrian of British Columbia.

Handl., 1881, vol. xix.—Ammon, L. v., Ueber jurassische Medusen. Abhandl. Bay. Akad. 1883,
vol. xvii. — Brandt, A., Ueber fossile Medusen. Mem. Acad. Imp. St-Petersb., 1871, 7tli ser.,
vol. xvi. — Pohlig, H., Altpermische Medusen. Festschrift zum 70ten Geburtstage K. Leuckarts,
U^2.- -Walcott, ö. D., Fossil Medusae. U. S. Geol. Surv. Monogr., xxx., 1898.— /c^em, Middle
Cambrian Holothurians and Medusae. Smithson. Mise. Coli., 1911, vol. lix. No. 3. — Mayer,
A. 0\, The Medusae of the World, i.-iii. Carnegie Inst. Wash,, Pub. No. 119, 1911.

Phylum III. VERMES. Worms.'

Bilaterally symmetrical animals with unsegmented or uniformly segmented, and
usually elongated bodies having a distinct body cavity. Segmented lateral appendages
wanting. A dermal muscular sysj^em and paired excretory
canals (water-vascular System) present.

Of all the larger divisions of the animal kingdom, none
is so poorly adapted for preservation in the fossil State as
the Worms, whose bodies are as a rule entirely destitute
of hard parts.

All Worms are bilaterally symmetrical, and dorsal and
ventral surfaces are clearlj^ differentiated. The unsegmented
Worms (Vermes proper) have either fiat or cylindrical bodies,
and are accordingly distinguished as Platyhelminthes or
Fiat Worms, and Nemathelminthes or Round Worms. But
with the exception of the Cambrian genus Amiskwia (Fig.
213), supposed to be allied to the Recent Sagltta, and a few
rare parasitic forms discovered in Carboniferous insects, or
in Tertiary insects enclosed in amber, neither of these classes
is represented in the fossil State.

• The segmented Worms, or Annelida, are characterised
by a division of the body into metameres, which, although
primitively alike, do not always remain homonomous.
They have a brain, a circumoesophageal ring, a ventral chain
of ganglia, and a vascular System. The body is more or less elongated, and

^ Literature : Fander, O. H., Monographie der fossilen Fische des silurischen Systems des
russisch-baltischen Gouvernements, 1851. — Ehlers, A'., Die Borstenwürmer (Annelida Chaetopoda).
Leipzic, 1864-68. — Idem, Über fossile Würmer aus dem lithographischen Schiefer in Bayern.
Palaeontogr. , 1868, vol. xvii. — Olaparede, Vi'., Recherches sur la structure des Annelitles sedentaires,
1873. — Newherry, J. *S'., Palaeontology of Ohio, vol. ii. part 2, 1875. — Ilinde, G. J.. On Conodonts
from the Chazy and Cinciunati Groups ; and on Annelid Jaws from the Cambro-Silurian, Silurian,
and Devonian Formations in Canada, and from the Lower Carboniferous in Scotland. Quar. Journ.
Geol. Soc, 1879, vol. xxxv. — Ulrich, E. 0., Journ. Cinciunati Soc. Nat. Hist., 1879, vol. i. —
Hitide, G. J., On Annelid Jaws from the Wenlock and Ludlow Formations of the West of
England. Quar, Journ. Geol. Soc, 1880, vol. xxxvi. — Etheridge, R.,jun., British Carboniferous
Tubicolar Annelida. Geol. Mag., 1880, vol. vii. — Nathorst, A. G., On the Tracks of sonie
Invertebrate Animals and their Palaeontological Significance. K. Svensk. Vetensk. Akad. Handl.,
1881-86, vols. xviii., xxi. — Ilinde, G. J., On Annelid Remains from tlie Silurian Strata of the Isle of
Gotland. Bihang tili K. Svensk. Vetensk. Akad. Handl., 1882, vol. \n.~Zittel, K. A., and
Rohon, J. V., Ueber Conodonten. Sitzber. Bay. Akad. Wiss., 1886, vol. xvi.—Clarke, J. M.,
Annelid Teeth from the Lower Portion of the Hamilton Group, New York. Sixth Annual Report,
N.Y. State Geologist, 1886. — Rovereto, G., Studi monografici sugli Annelidi fossili. Palaeont. Ital.,
1904, vol. X.— Walcott, O. D. , Middle Cambrian Annelids. Smithson. Mise. Coli. ,1911, vol. Ivii. No. 5.

135

Fig. 213.

AmislauiM sayltti-
formis Walcott. Mid-
dle Carnbrian; British
Columbia. Flatt«ned
specimen, x ^/i (after
Walcott).

136

VEEMES

PHYLUM III

sometimes flattened, sometimes cylindrical. According as the internal
Segments correspond exactly with the external, or as each internal segment
corresponds to a definite number (3, 4 or 5) of the external rings, two
classes, Chaetopoda and Hirudinea, are distinguished. A further difference is
to be noticed in the locomotive organs, the Chaetopoda having bristle-bearing,
unjointed appendages (parapodia) on each ring of the body ; and the Hirudinea
having a terminal sucker. The latter group includes only the Leeches, which
are not known with certainty in the fossil State. Fossil representatives of the
third class, the Gephyrea, Annelids with the body devoid of any appearance
of segmentation in the adult condition, are known ; but of the fourth and last
class Archiannelida, the most primitive of all living Annelids, no fossil remains
have been found.

Class 1. CHAETOPODA. (Earthworms, Annelids, etc.)

It is only with the subclass of mari>ne worms (Polychaeta) that the
paleontologist is concerned since the earthworms and their allies (Oligochaeta)
are wholly unknown as fossils. The marine Chaetopoda are divisible into
three Orders, the Miskoa, the Tubicola or Sedentary Worms, and the Nereid
or Errant Annelids.

Order 1. MISKOA Walcott.

Polychaeta with similar segments and parapodia throughout the length of the hody ;
retradile prohoscis ; straight enteric canal. Body not distinctly speciaUsed into
sections.

This Order is founded upon a remarkable series of Annelids discovered by

HP^r'^rlJ ,

Wl

ffjgKKl

|BfcL, V- i^k

1^^

^1

Fig. 214.

Wiwaxia corrvgata Walcott. Middle
Cambrian ; British Columbia. Crushed
specimen showing displaceü spines and
scales, X i/i (after Walcott).

i'Kis. zia aiid 216.

Cambrian Polychaeta from British Columbia (after
Walcott). Canadia spinosa and Aysheaia ■pedunculata
Walcott, both x ^/a-

Walcott in the Middle Cambrian of British Columbia and described by him in
1911. The Order is represented by four families, namely Miskoidae and
Aysheaidae, with the genera Mislwia and Aysheaia respectively ; Canadidae
including Canadia and Selkirkia ; and the Wiwaxidae with the three genera

LASS I CHAETOPODA 137

'iwaxia, Pollingeria and JVorthenella. Typical examples of these Annelids are
shown in Figs. 214-16. Frotoscolex and Eotrophonia Ulrich, from the Eden

Fig. 217.
Gephyrean Annelid, I'ikaia gracücns Walcott. Middlc Cambrian ; British Columbia, x 2/j (from Walcott).

shale of the Ohio Valley, are probably Ordovician representatives of this
Order.

Order 2. TUBICOLA. (Sedentaria.)

Pohjchaetous Annelids with indistindly separated head, and short, usually non-
protrusible prohoscis, witJiout jaws. Parapodia short, and never used for swirnming .
Inhabiting more or less firm tuhes, which they construd, and subsisting upon vegetable
matter.

The Tubicolous Annelids invest themselves with a protective tube of more
or less irregulär form, to which they are not organically attached, and within
which they can move freely. Sometimes the tubes are free, but more com-
monly they are attached to foreign objects, either by the apex or by one side,
and may occur either singly or in Clusters. The tubes frequently consist of
concentric layers of lime-carbonate, with vesicular cavities between the
lamellae, or the latter may be traversed by fine tubuli. In other cases the
tubes are composed of agglutinated grains of sand and other foreign particles ;
or they may be membranaceous or leathery. The materials for constructing
the tubes are procured by the tentacles or branchial filaments of the head,
and are cemented together by a glutinous secretion from large glands. Fossil
worm-tubes are by no means of infrequent occurrence, and are known from
the Ordovician onwards. Only a few of the more common examples can be
mentioned here.

Serpula Linn. (Fig. 218). ünder this head are included the majority of
fossil Tubicolous Annelids. They build firm, irregularly contorted, sometimes
spirally enrolled, free or adherent calcareous tubes, which are frequently
clustered together in large numbers. Beginning in the Silurian, they are
sparsely represented in the Paleozoic era ; but from the Jura onward, nunier-
ous forms occur, the usual condition being attached upon other fossils.
Notably in the Lower Cretaceous their gregarious masses form beds of con-
siderable thickness (Serpulitenkalk of Brunswick, and Serpulitensand of
Banne witz, near Dresden). . S. spirulaea Lam. (Fig. 218, H) is an abundant
and characteristic Eocene species. Eecent Serpulas have a world - wide
distribution.

138 VERMES phylüm iii

Terehella Cuv. (Fig. 218, I). Cylindrical, elongate, more or less beut

Fi(!. 218.

A, Serpula Umax Goldf. Middle Jura ; Franconia. ß, C, S. gurdialis Schloth. Upper Cretaceous : Banne-
witz, near Dresden. D, S. convoluta, Goldf. Middle Jura; Stuifen, Wurtembercr. E, S. socialis Goldf. Middle
Jura ; Lahr, Baden. F, Same, enlarged. G, S. septevisulmta Reich. Upper Cretaceous ; Bannewitz. H, S.
(Rot.ulariaJ)efr.)spirulaeaIjam. Eocene ; Monte Berici, near Vicenza. I, TerpheUalapilloides Münster. Upper
Jura ; Streitberjr, Franconia.

tubes, composed of cemented grains of sand, fish-debris, or other adventitious

particles. Lias to Eecent.

Spirorbis Daudin {Microconchus Murch.)
(Fig. 219). Minute, snail-like or spirally
enrolled calcareous tubes, cemented by the
flattened under side. The spiral may be
either dextral or sinistral, and is usually
ornamented externally with concentric Striae
or annulations, sometimes with tubercles or
spines. Abundant in the Paleozoic forma-
tions from the Ordovician onward, and also
at the present day ; somewhat less common
in the Mesozoic and Cenozoic eras. Kecent
species usually adherent on seaweeds.

Fig. 219.
Spirorhis omphalodes (Goldfuss).

Tubes

seated upon a Brachiopod shell {Schiichertella
umhraculnm). Devonian ; Gerolstein, Eifel.

The foUowing genera are
regarded as Annelids, but their systematic position is doubtful :

commonly

CLASS I

CHAETOPODA

139

Serpulites Mnrdh. Very long, smooth, compressed, and somewhat bent
calcareous tubes, the layers admixed with organic substance. Ordovician and
Silurian.

CornuUtes Schloth. Thick-walled, trumpet-shaped tubes, Serpula-like at the
lower end, and sometimes attaining a length of three or four inches. Exterior
annulated, and covered with very -fine longitudinal Striae. Some authors
regard the tubes as Pteropod shells. Ordovician to Devonian.

Ortonia Nich. Small, conical, slightly flexuous, thick-walled calcareous
tubes, cemented by the whole of one surface to some foreign body. Sides of
the tube ringed with imbricating annulations, the free upper surface apparently
cellular in structure. Ordovician to Carboni-
ferous.

Conchicolites Nich. Conical, slightly bent,
thin-walled tubes, growing together in Clusters,
and attached by the small lower ends to
orthoceratite or Brachiopod shells. Tubes
made up of numerous short rings, each of
which partially overlaps the subjacent one.
Ordovician.

The peculiar group Myzostomidae, which
are external parasites on Kecent Crinoids, are
thought to be related to the Chaetopoda.
Graff has shown that they also infested the
column Segments of Jurassic Crinoids.

Order 3. ERRANTIA. (Nereidae).

Free - swimming, predaceous Polychaeta, with
well-marJced liead. Proboscis capoMe of protrusion,
and armed with papillae or powerful jaws. Para-
podia 7nuch more developed than in the Tubicola,
heset with setae, and serving for locomotion.

Undoubted remains of Errant Worms have
long been known from the Lithographie Stone
(Upper Jura) of Bavaria, and include the
trails, calcified jaws and excrements of num-
erous species. The principal genus from this
horizon is Eunicites Ehlers {Geophilus Germar)
(Fig. 220), perfect impressions of which are
also found in the Upper Eocene limestone of
Monte Bolca, Italy. Archarenicola Horwood
is known from the English Rhaetic.

Uiider the designation of Lumhricaria
Münster (Lumbricites Schlotheim) (Fig. 221)

are included a variety of obscure. remains from the Lithographie Srone,
which may be best regarded as the excrements of Annelids. They occur
as irregularly contorted bands or strings, sometimes in the form of very
long labyrinthic coils.

Of peculiar interest are the minute detached jaws and denticulated plates

Fig. 220.

Eunicites avitus Ehlers. Lithographie
Stone ; Eichstädt, Bavaria. Natural size.

140

VERMES

PHYLUM III

described by Hinde in the Ordovician, Silurian, Devonian'and Carboniferous
rocks of the United States, Canada, Great Britain and Sweden (Island of Got-
land). These are very small, black, highly lustrous bodies, extremely variable

in form (Fig. 222), and mainly
composed of chitinous material
which is unafFected by acid. They
exhibit a striking resemblance to
the jaws of recent. Annelids, and
probably represent a large number
of genera.

Of less certain derivation are
the microscopic teeth first described
by Pander under the name of
"Conodonts" (Fig. 223), which
occur detached in the Cambrian
(Blue Cläy underlying the Ungulite
Grit) of St. Petersburg, and are
also very abundant in beds of
Ordovician, Silurian and Car-
boniferous age in Russia, Great
Britain, the United States and
Canada. They are usually translucent, lustrous or corneous, and are composed

Fig. 231.

Lumhricaria colon Münst. Lithograi)hic Stone ; Solen-
hofen, Bavaria. Natural size.

-3

Fig. 222.

Paleozoic Annelid-jaws. A, Lumbriconereites hasalis Hinde. Silurian ; Dundas, Ontario. lo/j. ß^ Oenonites
rostratus Hinde. Toronto. l5/i. C, Eunicites varians Grinnell. Toronto, "/i- ^, Arabellites scutellatus
Hinde. Ordovician ; Toronto, lö/j.

of carbonate and phosphate of lime. They exhibit very great variety in form.
By Pander and others these fossils have been regarded as fish-teeth. Zittel

^

Fig. 223.

Conodonts, greatly enlarged. A, B, Paltodus truncatus Pander (after Pander). C, Prioniodus elegans Pander.
Cambrian ; St. Petersburg. D, Polygnathus duUus Hinde. Devonian ; North Evans, NeAv York. 20/^.

and Rohon, however, consider that they are Annelid jaws, but their true
Position cannot yet be said to have been positively determined.

CLASS II

GEPHYREA

141

Fig. 224.

Nereites camhrensis M'Leay. Cambrian ; Llampeter, Wales.
Natural size.

Olass 2. GEPHYREA.

Marine Annelida without parajpodia and typically devoid of any trace of
segnientation in the adult condition.

The Cambrian genera referred to this class by Walcott differ in certain

respects from the Kecent members, but with our available information the

Position here assigned them

seems most advisable. Two

f amilies, (1) Ottoidae, with the

genera Ottoia and Banffia, and

(2) Pikaidae, including Pikaia

(Fig. 217) and Oesia, all from

the Middle Cambrian of British

Columbia, are recognised.

A quantity of supposed

worm-borings, trails, impres-

sions and otherobscureremains

have been described from the

older Paleozoic formations.

The burrows have the form

of straight or tortuous tunnels,

and are sometimes hollow,

but more commonly have been

filled up by solid matrix. Various names have been applied to them,

such as Scolithus, Arenicola, Histioderma, Planolifes, Diplocraterion, Spirocolex,

Scolecoderma etc., but they are obviously incapable of precise determination.

Arthrophycus Hall, originally described as a plant, Daedalus (including Vexillum

Roualt) and Taonurus Fisher-

^^'<i4. '''^!^^z^st^^^is^^^^^:^ Ooster (Spirophyton Hall), have

in recent years been interpreted
as worm burrows. •

Similarly, the Serpentine or
vermiform impressions known as
Nereites, consisting usually of a
number of windings, and often of
profuse occurrence in various
Paleozoic formations, were until
quite recently regarded as worm-
trails, or markings made by
Fucoids. These also have re-
ceived . numerous appellations,
such as Nereites (Fig. 224), N'e-
mertites, Myrianites, Nemapodia,
Crossopodia (Fig. 225), Phyllodo-
cites, Naites, etc. Nathorst, how-
ever, has brought forward ex-
perimental evidence to prove that the majority of these markings have been

produced by the movements of Crustaceans, Annelids and Gastropods. A like

origin may reasonably be ascribed to the extraordinarily abundant and variable

FifJ. 225.

CrossopoiUa (Crossochorda) scotica M'Coy. Ordovician
IJagnoles, Norniandy.

142 VERMES phylüm iii

vermiform structures known as " Hieroglyphics," which occur in the Flysch,
Carpathian Sandstone, and in the marine facies of the Cretaceous and Jurassic
formations. The trails known as Climaäichnites Logan/ from the Potsdam
sandstone (Oambrian) of New York and Wisconsin, are of uncertain origin,
but may be those of some large crustacean. Other peculiar markings have
been interpreted by B. B. Woodward (Proc. Malacol. Soc, London, 1906, vol.
vii.) as the feeding-tracks of Gastropods.

^ These tracks, known as Ölimactichnites, were first described by Logan {Can. Nat. and Geol.,
18Ö0, voL.v.) and later recorded by Hall (N.Y. State Mus. 42nd Report, 1889) from Port Henry,
Essex county, N.Y., and by Woodworth (N.Y. State Mus. Bull. 69, 1903) from the town of
Mooers, Clinton county, N.Y. In the latter locality they assume gigantic proportions, being 6 inches
Wide and 15 or more feet long, terminating in an oval Impression 16 inches long.

Various explanations have been suggested for these tracks. Besides having been referred to
trilobites, burrowing crustaceans, plants, gastropods and annelids, they have been compared with
those of the horseshoe crab, first by Dawson and recently again by Hitchcock and Patten. Sir
William Dawson {Gan. Nat. and Geol.^ 1862, vol. vii.), Avho studied Limulus on the seashore,
pointed out that when the animal creeps on quicksand, or on sand just covered with water, it uses
its ordinary Walking legs and produces a track strikingly like that described as Protichnites from
the Potsdam sandstone ; but in shallow water just covering tlie body, it uses its abdominal gill-plates
and produces a ladder-like track the exact counterpart of Ölimactichnites except that in the track of
Limulus the lateral and median lines are furrows instead of ridges. Patten (Science, 1908, vol. viii.
p, 382) " described the inovements of a modern Limulus in advancing up a sandy beach with the tide,
and the action of the abdominal gill-plates making rhythmic ridges in the sand. He compared
these with the tracks of Climactichnites, which he ascribed to forms related to the eurypterids rather
than the trilobites. The tracks showed a beginning in a hollow in the sand and where continued
on the specimen to the further end there became fainter, as if the animal rose from the bottom.
This would correspond with the habit of the Limulus^ which remains buried on recession of the tide
and upon its first return crawls and then swims away. Beside one track were seen two symmetric-
ally placed impressions attributed to the longer arms of a Eurypteroid form."

In favour of this view is the fact that Strabops is a Cambrian Eurypterid that woiild appear
competent to produce such tracks ; contrariwise, however, Woodworth has suggested that the trail
was made by a mollusk, and that the sedentary Impression is the end of the trail instead of its
beginning. The direction of the obliquely transverse marks of (ölimactichnites is always toward
the oval impressions, and eomparison with those of the Limulus tracks (Dawson, figs. 1-3, and also
fig. 157 in Cambridge Nat. Hist. vol. iv.) would indicate that tliö animal, if an Eurypterid, moved
toward the sedentary Impression and not away from it. The most recent discussion of the nature
of these and other problematical markings is to be found in a paper by Walcott {Smithson, Mise.
Coli., 1912, vol. Ivii., no. 9), where it is suggested that the Climactichnites trails may have been
formed by a largfe segmented Annelid like Pollingeria. Specimens of the latter are known from
the Cambrian which have a length of 13 cm. and width of 7 cm.

Phylum IV. ECHINODERMATA

The Echinoderms are animals with primarily a radial (usually pentamerous)
and secondarily more or less bilateral symmetry, which were formerly included
with the Coelenterates under the general category of Radiata ; but were
recognised by Leuckart as the representatives of a distinct animal type.
Recently it has been suggested by two authors, working independently, one
from a study of comparative embryology (Patten), and the other from
evidence furnished by the adult anatomy (A. H. Clark), that the Echinoderms
are derived from acraniate crustacean ancestors, through the Cirripedia.

Echinoderms possess a well-developed, usually pentamerous dermal
skeleton, which is composed of calcareous plates, or of minute, isolated,
calcareous bodies embedded in the integument, and sometimes also in the
walls of many of the internal organs. The exoskeleton may be immovable,
or more or less movable, but is very frequently provided with movable
appendages (spines, pedicellariae, etc.). The arrangement of both the
skeletal parts and the principal organs is so generally pentamerous, that
five may be regarded as the fundamental numeral pervading the phylum of
Echinoderms.

Apart from this constitutional difFerence, Echinoderms are distinguished
from Coelenterates by the presence of a true digestive canal, a distinct
body-cavity, a vascular System, and a water-vascular apparatus ; by a more
perfectly developed nervous System ; and, except in certain Starfishes, by an
exclusively sexual mode of reproduction.

The skeleton of Echinoderms is primarily composed of a series of plates
which are situated in the integument, and are covered with living dermal
tissue during life of the individual. Although lying near the surface, the
plates are strictly internal in position, and are capable of growth or resorption
throughout life. Besides skeletal plates, other hard parts may occur, such as
spines, pedicellariae, the jaws or so-called " Aristotle's lantern " of Echini, and
spicules of the kind found in the tube-feet and some of the internal organs.
Certain Crinoids also show a series of calcified convolutions supporting the
digestive tube. The calcification of the internal organs is sometimes sufficient
to form solid skeletal parts. The plates and other skeletal parts of Echino-
derms are composed of open cribriform tissue (Figs. 226, 227), which in the
cleaned test of Recent specimens is highly porous. During fossilisation the
interstices are commonly infiltrated with lime carbonate, so that the whole
striicture is transformed into calcite, exhibiting unmistakable rhombohedral
cleavage. Each plate, Joint and spine of a sea-urchin, star-fish or crinoid

143

144

ECHINODERMATA

PHYLUM IV

behaves mineralogically and optically like a single calcite crystal. The plates
forming the main skeleton of an Echinoderm may be few or numerous, and
may be polygonal with vertical sides forming a solid skeleton, or they may
be rounded, scale-like or imbricating, forming a more or less flexible test ; or
again they may be reduced to minute, dissociated bodies embedded in the
integument and forming a partial dermal skeleton, as in certain Holothurians.
All the Echinoderms are marine, and only a very few of them occur in
even very slightly freshened water. In the sy^stem proposed by Haeckel

Fi(i. 226.

a, Magnifled cross-section of an
Echinoid spine ; Fiji Islands, b, Mag-
nilied section of coronal plate of a
Recent Sea - urchin (Sj)haerechinus) ;
plane of section parallel to surface.

Fig. 227.
Pentacrinus siCbteres Goldf. Upper Jura ; Reichen-
bach, Wurtemberg. a, Vertical section of steni-joint in
plane indicated in c, 18/i. h, Transverse section of
saine, 18/i. c, Joint-face. d, Series of columnals
(natural size).

seven classes are recognised, of which the first three, namely, Cystidians,
Blastoids and Crinoids, are grouped together as a distinct subphylum called
Felmatozoa. Corresponding to this are two other subphyla, Ästerozoa and
Echinozoa, the former including the classes of Asteroids and Ophiuroids,
and the latter comprising the classes of Echinoids and Holothurians.

Subphylum A. Pelmatozoa Leuckart.

The Pelmatozoa are Echinoderms, nearly all of which, during the whole or
at least the early portion of their existence, are fixed by a jointed, flexible
stalk, or are attached by the dorsal or aboral surface of the body. The prin-
cipal viscera are enclosed in a bursiform, cup-shaped or spherical test (calysc),
which is composed of a System of calcareous plates. On the upper surface of
the test are placed both the mouth and anus, as well as the ambulacral or
food grooves conducting to the mouth. In some forms, however, the calyx is
so reduced as to form merely a small horizontal platform upon which rest the
viscera, usually protected by a covering of secondary dermal plates. As a

lSSi CYSTOIDEA IHH^V ^^^

ile, jointed flexible arms spring from the distal ends of the ambulacral
"^groGves around the margin of the calyx ; but sometimes, as in Blastoids, arms
are wanting, the ambulacral areas being extended down the sides of the calyx,
and beset on both sides with pinnules. The inferior (dorsal, aboral) portion
of the calyx is composed of a single or double series of basal plates, which
rest either directly upon the stalk, or upon a centrodorsal representing a
Single greatly enlarged columnal, or they may be grouped about a central
apical plate or centrale. Sometimes these plates are so small as to be invisible
externally, so that the calyx appears to be composed of radials only.

The Pelmatozoa comprise three classes : Cystoidea, Blastoidea and Crinoidea.
Of these, the first two are wholly extinct, being confined to the Paleozoic
rocks ; all three are found well developed in the Ordovician, and doubtless
originated in pre-Cambrian time from unknown ancestral forms. The Cystids
are the oldest, substantially ending with the Silurian, though feebly repre-
sented in the Devonian and Carboniferous. The Blastoids culminated in the
Lower Carboniferous and ended in the Permian. The Crinoids also cul-
minated in the Carboniferous, but continued to survive, nevertheless, and are
represented in existing seas by numerous genera and species, the dominant
type being the unstalked forms, or Comatulids.

Olass 1. CYSTOIDEA Leopold von Buch.^

Extinct, pedunculate, or more rarely sfemless Pelmatozoa, with calyx composed
of irwre or less irregularly arranged plates. Food brought to the mouth by a System
of ciliated grooves, either between the calyx plates, over them, or along processes from
the calyx {arms, brachioles, etc.), or subtegminal. Anus usually on the oral half of
the calyx. Calyx plates often perforate. Brachial processes usually imperfectly
developed, sometimes absent.

The calyx is globose, bursiform, ovate or ellipsoidal in form, more rarely
cylindrical or discoidal, and is composed of quadrangular, pentagonal, hexa
gonal or polygonal plates, which are united by close suture. The plates
Vary in number from thirteen to several hundreds, and only exceptionally

^ Literature : Volhorth, A, von, Ueber die Echinoencrinen. Bull. Acad. Imp. Sei. St-Petersb.,
1842, vol. X. — Volhorth, A. von, lieber die russischen Sphaeroniten. Verhandl. Mineral. Gesell.
St, Petersb., 1845-46. — Buch, L. von, Ueber Cystideen. Abhandl. Akad. Wiss. Berlin, 1844
(1845). Translated in Quart. Journ. Geol. Soc. London, 1845, vol. ii. — Forbes, E., On the
Cystidea of the Silurian Rocks of the British Islands. Meni. Geol. Survey Great Brit., 1848,
vol. ii. part 2. — Müller, J., Ueber den Bau der Echinodermen. Abhandl. Akad. Wiss. Berlin,
1853.— ^«ZZ, J., Palaeontology of New York, vol. ii., 1852, and vol. iii., 1859.— Bülings, K, On
the Cystidea of the Lower Silurian Rocks of Canada (Figures and Descriptions of Canadian Organic
Remains, Decade III.), 1858. — Hall, J., Descriptions of some new Fossils from the Niagara Group.
20th Ann. Rept. N.Y. State Cabinet of Nat. Hist., 1S67 .—Billings, K, Note.s on the Structure of
Crinoidea, Cystidea, and Blastoidea. Amer, Journ. Sei. (2nd ser.), 1869, vol. xlviii., and 1870,
vol. xlix. — Volborth, A. voti, Ueber Achradocystites und Cystoblastus. Mem. Acad. Inip. Sei. St-
Petersb., 1870, vol. xvi. — Schmidt, F., Ueber Baltisch-Silurische Petrefacten. Mein. Acad. Inip.
Sei. St-Petersb., 1874, vol. xxi. — Barrande, ./., Systeme Silurien du Centre de la Boheme, vol. vii.
Cystidees, 1887. — Carpeuter, P. H., On the Morphology of the Cystidea. Journ. Liun. Soc, 1891,
vol. xxiv. — Haeckel, E., Die Amphorideen und Cystoideen, etc. Festschr. für Gegenbaur, No. 1,
1896. — Jaekel, 0., Stammesgeschichte der Pelmatozoen, Thecoidea und Cystoidea, 1899. — Jaekel,
0., Über Carpoideen. Zeitschr. Deutsch. Geol. Gesell., 1900, vol. Iii. — Bather, F. A., Treatise
on Zoology (Lankester), part 3, Echinoderma, 1900. — Schnchert, C, Siluric and Devonic Cystidea.
Smithson. Mise. Coli., 1904, vol. xlvii. part 2. — Bather, F. A., Ordovician Cystidea from Burma.
Mem. Geol. Surv. India, 1906, n. s. vol. il—Kirk, K, Structure and relation.ships of certain
Eleutherozoic Pelmatozoa. Proc. U.S. Nat. Mus., 1911, vol. xli. No. 1846.

VOL. I L

146 ECHINODERMATA— PELMATOZOA phylüm iv

exhibit a regulär arrangement. Sharp demarcations between the acfcinal and
abactinal Systems of plates, and between radial and interradial areas, rarely
exist ; the plates of the sides of the calyx pass insensibly into those of the
ventral surface, and are disposed in regulär cycles only in a few instances.
The base, however, is composed of a distinct ring of plates, and is usually
recognisable by the presence of an articular surface for the attachment of a
stem, or by being directly adherent to some foreign object.

The mouth is indicated by a central or subcentral aperture on the upper
surface, or at the end opposite to that which is attached to the column or
stem. It is sometimes covered by five small plates corresponding to the
orals of Crinoids, and from it radiate from two to five simple or branching
ambulacral grooves. The second opening on the ventral surface is situated
eccentrically, and is frequently closed by a valvulär pyramid, consisting usually
of five or more triangulär plates ; or the covering may consist of a variable
number of smaller pieces. This aperture, which was regarded by L. von
Buch, Volborth, Forbes and Hall as a genital opening, is now generally con-
ceded to represent the anus. A third smaller opening, situated between the
mouth and the anus, is present in a few forms only. The functions of this
latter orifice are not well understood, but it is commonly regarded as the
ovarian aperture, or genital pore (Fig. 228). Yet another small, slit-like opening,
situated in the vicinity of the mouth, was detected by Barrande in the genus
Aristocystites ; but its functions are altogether unknown.

The ambulacral grooves, or food-grooves, which are present in most
Cystideans, are usually simple, although sometimes distally branching, and
are frequently roofed over by alternately arranged covering pieces. In a few
forms {Caryocrinus, Cryptocrinus, etc.) the grooves are wholly absent. The
genera Aristocystites, Pyrocystites and Calix are without exposed ambulacral
grooves ; but they have instead, as Barrande discovered, a peculiar System of
five or six covered passages on the inner surface of the calyx plates, which
converge towards the mouth, and are distally more or less branching (Fig.
229). These structures, the so-called " hydrophores palmdes," were homologised
by Barrande with the hydrospires of Blastoids ; but as Neumayr has pointed
out, they are probably the equivalent of subtegminal food-grooves in Crinoids.

The calyx or thecal plates exhibit most remarkable structural peculiarities.
As a rule they are more or less extensively perforated by pores or fissures ;
although in some forms [Cryptocrinus, Malocystites, Ateleocystites, etc.) they
appear to be imperforate, and are composed of a homogeneous calcareous
layer of greater or less thickness, the same as in Crinoids. But in Aristo-
cystites, Calix, Proteocystites, Glyptosphaerites, Echinosphaerites, etc., the plates
are uniformly covered both externally and internally with a very thin,
generally smooth, calcareous membrane, which may be perforate or imperforate.
The central layer is of varia,ble thickness, and is traversed by numerous
canals (Figs. 229, 230) which extend from the inner to the outer surface,
sometimes rectilinearly {Aristocystites, Calix, etc.) ; sometimes in slightly
sinuous lines ; and in rare instances they divide dichotomously. The canals
terminate on either surface in small round apertures or pores, which are
arranged either singly or in pairs, and may or may not penetrate the outer
calcareous membrane. The pores are commonly situated either on a tubercular
elevation, or in a slight superficial depression.

But still more frequent than the canals are the so-called pore-rhomhs (Fig.

CLASS I

CYSTOIDEA

147

231) which occur indifFerently in types possessing numerous or but few
calycine plates. The pores are arranged so as to form lozenge-shaped or
rhombic figures, in such manner that one half of each rhomb belongs to one
plate, and the other half to its contiguous neighbour ; while the line of suture
between the plates forms either the longer or the shorter diagonal of the
rhomb. The pores of opposite sides of the rhomb are united by perfectly closed,
straight ducts, which pass horizontally through the middle layer and across
the line of suture between the two plates, thus producing a transversely
striated appearance. Occasionally the connecting tubes appear on the outer
surface as elevated striate rhombs ; but as a rule they are concealed by the
above-mentioned covering layer, and are only visible in weathered or abraded
specimens. The pores of the rhombs also communicate with short canals

Fig. 229

Aristocystites. Canals
perforating the median
layer of plate.

Fig. 230.

a, Aristocystites. Inner snrfaceof two

calyx plates showing simple pores ;

b, Glyptosphaerites. Outer surface of

calyx plate showing double i)ores.

Fig. 228.

Glyptosphaerites leuchtenhergi Volborth.
Calyx showing ambulacral grooves, plated
mouth-opening, large laterally situated anus,
and small ovarian aperture between mouth
and anus.

Fig. 231.
Pore-rhombs of (a) Echinosplmerites, and (h) Caryocrinus,
enlarged. The left half of Fig. a is abraded, so that the
connecting-tubes appear as open grooves.

passing vertically through the plates, the ends of which are either covered
over by the outer calcareous layer, or appear on both surfaces as fine indepen-
dent pores. A pair of oppositely situated pores of the latter description
may sometimes receive as many as two or three fine canals, while in other
genera they are entirely wanting.

The pore-rhombs are sometimes present upon nearly all plates of the calyx,
but in other cases they are only developed on a certain number or on all of
the plates forming the side-walls of the calyx, being absent from its upper
surface. In still other instances {Pleurocijstites, Callocystites, Fig. 232), the
pore-rhombs are greatly reduced in number, and occur in the form known as
pectinated rhombs or pedino-rhombs. The component halves of the latter
stand on contiguous plates the same as the ordinary pore-rhombs, but are
always separated externally by an interval ; frequently the two parts are of
different form or size, and sometimes one of them may become obsolescent.

As regards the functions of these canals and pores (the " hydrospires " of

148

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Fig. 232.
Callocystitesjeweiti Hall. Silurian (Niagara Group); Lockport, New
York. A, Calyx from one side (natural size). B, Ambulacral grooves
and tliree pectinated rliombs (r/t), enlarged ; o, Mouth ; an, Anus ; g,
Genital pore (after Hall).

Billings), the anatomy of existing Crinoids furnishes us with no positive con-
clusions. They have been compared with the pores which are present in the
tegmen of the latter, and the rather plausible Suggestion has been ofFered that
they served to admit water into the body-cavity, and thus performed
respiratory functions. At all events, they could not have served for the pro-
A ß trusion of tube-feet, since

they are frequently covered
over by an outer calcareous
membrane, which efFectu-
ally shuts ofF communica-
tion with the exterior.

The arms or brachioles
in the Cystideans are as
a rule feebly developed,
and are sometimes either
entirely wanting, or re-
duced in number (2, 3, 6,
9-13). The pentamerous
symmetry, so generally
characteristic of Echino-
derms, pervades neither the arrangement of the calyx plates nor the number
and disposition of the arms. The latter are invariably simple, are either
uniserial or biserial, and exhibit a ventral groove protected by covering plates.
In some genera the arms attain considerable thickness, but in others they
are very diminutive, and seem to have closer affinities with pinnules than
with the arms of Crinoids. In the Callocystidae and Agelacrinidae, as well as in
the Canadian genera, Amygdalocystites and Malocystites, the arms are either
recumbent with their dorsal side facing the calyx, or they are prostrate and
incorporated into the calyx. The ventral side, in these cases, is directed out-
wardly, and the ambulacral furrow is bordered on either side by a row of
alternating, jointed pinnules, which are
attached by small articular facets running
parallel with the groove.

The stem, as a rule, is greatly abbrevi-
ated, and is frequently obsolete. Some-
times the calyx is attached by the entire
lower surface (Agelacrinus) ; or in other
cases by means of a tubulär process
(Echinosphaerites). Only in rare instances
does the stem appear to have served for
attachment, since it generally tapers dis-
tally to a point, and is invariably destitute

of cirri. The stem sometimes resembles that of the Crinoids, in being composed
of a number of short, prismatic or cylindrical joints ; these are pierced by a
wide canal, and are either united by horizontal, striated, articular surfaces, or
they overstride one another like the draw-tubes of a spy-glass. In other cases
the Upper part, and occasionally, indeed, the entire stem, is composed of vertical
rows of alternating plates. These plates, as a rule (Dendrocystites), enclose
a large central space, which may be regarded as a Prolongation of the body-
cavity.

Fig. 233.

a, Aristocystites. Subtegminal ambulacral
grooves ; b, Same of Pyrocystites. Enlarged (after
Barrande).

CLASSi CYSTOIDEA 149

The Cystideans coiistitute the oldest and least specialised group of the
Pelmatozoa. Appearing first in the Cambrian, they develop a great variety of
forms in the Ordovician and Silurian, but become extinct before the close of
the Carboniferous. While their own ancestry is obscure, it is highly probable
that from them have descended both the Crinoids and Blastoids. If, on the
one band, the families of Aristocystidae, Sphaeronitidae and Echinosphaeritidae
differ radically from Crinoids in respect to their numerously and irregularly
plated calyx, or as regards the feeble development or even total absence of
their arms ; nevertheless, the Cryptocrinidae and the imperfectly preserved
Cambrian genus, Lichenoides, evince a striking similarity, especially as concerns
the more or less regulär arrangement of the calyx plates, and a certain
approach to radiation. On the other band, forms like Porocrinus and Cleiocrinus,
along with strong pentamerous symmetry and regulär arrangement of plates
which seem to ally them with the Crinoids, have also, in the presence of
pectino-rhombs and calycine pores, characters by which they might with equal
propriety be assigned to the Cystids.

If we can explain the derivation of Crinoids from Cystideans on the
supposition that the calyx plates of the latter gradually took on a more
definite arrangement, while the loss of pores and pore-rhombs was counter-
balanced by a stronger development of the arms and the stem ; so, too, it is
possible to derive Blastoids from the same source. Although hydrospires
are clearly wanting in the Cystids, nevertheless, other characters, such as the
recumbent attitude of the arms upon the sides of the calyx, or their Insertion
in grooves on the ventral surface, predicate an intimate relationship with
the Blastoids. Probably the most notable similarities are presented by the
peculiarly modified families, Callocystidae and Agelacrinidae. Various attempts
have been made to affirm a connection between Agelacrinus and the Asteroidea,
and between Mesites and certain of the Silurian Echinoidea (Echinocystites) ;
but such hypotheses are scarcely warranted, since they proceed from an over-
valuation of purely external resemblances, which in nowise prove genetic
relationship.

The Cystids were first recognised as a distinct division of Echinoderms by
Leopold von Buch in 1844, but their more detailed Classification long remained
in an unsatisfactory condition, and is still involved in considerable difficulty.
This is largely owing to the comparative scarcity of material and its
frequently imperfect preservation, affording insufficient knowledge of the
exact structure in many forms. The Classification of Johannes Müller was
based primarily upon the structure of the calyx plates, according to which
two main groups were recognised, BJiombifera and Diploporita. To these
Roemer afterwards added a third, Aporita, and other divisions were made by
Barrande, Neumayr and Steinmann. In later years the Cystids have been
treated extensively by Haeckel, Bather, and Jaekel, who have proposed
classifications based upon phylogenetic principles. While in some general
features these are in substantial agreement they differ considerably in
details. The arrangement adopted by Bather, with some of the modifica-
tions introduced in the later editions of Zittel's Grundzüge, is in the main
here followed.

150

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Order 1. AMPHORIDBA Haeckel {pars).
No radial symmetry in food grooves or calyx plates.

Family 1. Aristocystidae Neumayr.

Calyx composed of numerous plates without regulär arrangement. No extension
a of food-grooves or brachial processes. Stern undeveloped,

or very short. Cambrian to Silurian.

Pilocystites, Lapillocystites and Acanthocystites Bar-
rande. Cambrian ; Bohemia. These are obscure genera.
Aristocystites Barr. (Fig. 234). Calyx bursiform
or ovate ; ventral surface with four apertures ; stem-
less. Ordovician ; Bohemia.

Deutocystites Barr. Ven-
tral surface with three aper-
tures. Calix Eouault (Cra-
terina Barr.). Conical, trun-
cate. Baculocysfites Barr.
Ordovician ; Bohemia.

Megacystites Hall (Holocystis
S. A. Miller). Elongate,
cylindrical or sub-cylindrical ;
short - stemmed or stemless,
with subcentral mouth. Silur-
ian ; North America, Gotland.
Said to be a sponge.

Aristocystites boJiemicus] Barr. Ordovician (Dd'^) ; Zahorzan
Bohemia. a, Side view ; b, Summit aspect (after Bariande).

? Lodanella Kayser. Devonian ; Germany.

Family 2. Anoraalocystidae Meek.

Calyx oval, more or less compressed, with dissimilarly plated hroad sides.
either imperforate or with simple pores ; pore-rhomhs ahsent.
Food-grooves extended in one or more processes. Stem short,
tapering, of polymeric columnals. Cambrian to Silurian.

Trochocystites Barr. (Trigonocystis Haeckel). Calyx
strongly compressed. Plates of the right and left sides
large, those of both the anterior and posterior small,
polygonal. All plates perforate, but without pore-
rhombs. Ventral surface with three apertures. Stem
composed of several vertical rows of plates. Cambrian ;
Bohemia, Spain, Northern France.

Mitrocy Stiles Barr (Fig. 235). Like the preceding,
except that one side of the calyx is composed of toler-
ably large, and the other of small plates. Ordovician ;
Bohemia.

Mitrocy Stella, Rhipidocystis Jaekel. Ordovician ;
Bohemia.

Änomalocy Stiles Hall (Ateleocystites Bill.; Platycystis
S. A. Miller ; Enopleura Weth.). Calyx plates smaller

Plates

Mitrocystites mitra Barr.
Ordovician ; Wosek, Bohemia.
Snpposed right side (after
Jaelcel).

and more numerous

on the convex side than on the concave. Anus situated very low down on

CLASS I

CYSTOIDEA

151

the convcx side. Arms feeble, filiform. Ordovician and Silurian ; North
America, England, Bohemia.

Balanocystites Barr. Ordovician ; Bohemia.

Belemnocystis Miller and Gurley. Ordovician ; North America.

Placocystites de Koninck (Fig. 236). Silurian ; England.

Dendrocystites Barrande. Ordovician ; Bohemia. Cigara Barrande. Cam-
brian ; Bohemia. Syringocrinus Billings. Trenton Group ; Canada.

Eocystites Billings. Cambrian ; Canada.

Protocystis Hicks. Cambrian ; England.

Ceratocystis Jaekel. Cambrian ; Bohemia.

Fig. 236.

Placocystites forhcsianus de Kon. Silurian ; Dudley,
England. A, Concave aspect, showing brachioles (br)
and proximal stem joints. B, Convex aspect. b, basals ;
m, niarginals ; v, ventrals (after Jaekel).

Fig. 237.

Amygckducystites florealis Bill. Tren-
ton Group ; Canada. 1, from side ; 2,
Single plate enlai-ged ; 3, portion of
food-groove enlarged. Br, dotted
outline of sonie brachioles ; Br', facet
for attachment of same (after Bather).

Family 3. Malocystidae Bather.

Calyx plates numerous and indefinitely arranged. Radial folds of stereom
strongly marked, hut no definite pore-rhombs or peäinated rhomhs. Brachioles borne
on processes either free or recumbent on the calyx. Stem uniserial.

Malocystis Billings. Calyx globular. Ordovician ; Canada. Canadocystis
Jaekel. Sanre horizon.

Sigmacysiis Hudson. Ambulacra S-shaped. Ordovician ; Canada.

Amygdalocystites Billings (Fig. 237). Calyx flattened and elongate. Two
unbranched ambulacra, fringed with brachioles, pass from a subcentral mouth
over the calyx. Ordovician ; Canada.

Comarocystites Billings. Ordovician ; Canada. Achradocystites Volborth.
Ordovician ; Russia.

Order 2. RHOMBIFERA Zittel (emend. Bather).

Radial symnietry affects food-grooves, and sometimes calyx plates. Food-grooves
borne on jointed processes (brachioles). Calyx plates more or less folded, and provided
with rhombs.

152

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Family 1. Echinosphaeritidae Neiimayr.

Calyx glohular or bursiforni, adherent or with short stem, and composed of
7mmerous, irregularly arranged plates, all of which are furnished with pore-rhojnhs.
Ämbulacral grooves short, unhranched ; arms two to five,free, biserial, rarely preserved.
Stem, when present, composed of several vertical series of alternately arranged plates.
Ordovician and Silurian.

Fig. 238.

Echinosphaerites aurantium (Hising). Ordovician (Vaginatenlvalk) ; Pulkowa, Russia. a, Summit view of
calyx ; h, Calyx seen from the anal side ; c, Mouth, arms, and covered ämbulacral grooves ; d, Calyx plates
enlarged, showing pore-rhombs (cf. Fig. 231).

Echinosphaerites Wahlenb. (Crystallocystis, Citrocystis, Trinemacystis Haeckel)
(Fig. 238). Globose, non-pedunculate. Mouth central, ämbulacral grooves
short. Anal opening protected by a valvulär pyramid ; arms unknown.
Very abundant in the Ordovician of Kussia and Scandinavia.
E. aurantium (Hising).

Arachnocystites Neumayi-. Like the preceding, except
that it has strong arms, usually three in number, which
sometimes attain a length of 10 cm. Stem tapering dis-
tally to a point. Ordovician ; Bohemia. A. infaustus
(Barr.).

Caryocystites v. Buch (Amorphocystis Jaekel) (Fig. 239).
Calyx plates relatively large. Pore-rhombs on external
surface elevated, prominent. Stem wanting. Ordovician ;
Eussia, Scandinavia, England. C. granatum Wahlenb.

Palaeocystites Billings. Calyx ovate or pyriform ; plates
numerous, and porif erous at the margins. Ordovician ; Canada.
Orocystites Barr. Ordovician ; Bohemia. Heliocrinus Eichwald. Ordo-
vician ; Eussia. Stichocystis Jaekel. Ordovician ; Europe.

Fig. 239.

Caryocijstiteis grana-
<ttm(Wahlb.) Ordovi-
cian ; Oeland. Plates
of the natural size
showing elevated
pore-rhombs.

Family 2. Oaryocrinidae Bernard.

Calyx composed of a moderate number of plates exhibiting a more or less definite
arrangement in cycles. Certain or all of the side plates with pore-rhombs ; those of
the ventral surface imperforate. Food-grooves primitively three, branching, and
leading to free arms in varying number. Stem constantly present, occasionally long.
Ordovician and Silurian.

Hemicosmites v. Buch {Hexalacystis Haeckel). Calyx composed of four
basal plates, two zones containing six and nine lateral plates respectively, and
a circlet of six plates forming the ventral surface. The latter carries three
short ämbulacral grooves, at the ends of which are situated small articular

CYSTOIDEA

153

facets for the attachment of arms. Pore-rhombs present on all of the side
plates. Ordovician ; Kussia. H. pyriformis v. Buch.

Caryocrinus Say (Stribalocystis S. A. Miller ; Enneacystis Haeckel) (Fig.
240). Calyx hexamerous, with dicyclic base. Infrabasals four, unequal ;
followed by a second row (basals) ,^

of six plates, alternating with the
plates of the first and third cycles.
The latter ring consists of eight
plates, six of which, according to
Carpenter, represent the radials,
and two (the interscapulars of
Hall) the interradials. Ventral
surface formed of six or more
small pieces. All plates of the
cup furnished with pore-rhombs ;
the summit plates imperforate.
Mouth and ambulacral groove
subtegminal. Anus protected
by valvulär pyramid, and situated
on the outer margin of the ventral
surface. Here also are placed
the arms, which are six to thirteen

in number, and relatively feeble. Stem long, composed of cylindrical
Segments. Ordovician ; Scandinavia. Silurian ; New York and Tennessee.

Heterocystites Hall. Silurian ; New York. Corylocrinus, Juglandocrinns
von Koenen. Upper Ordovician ; France.

Fig. 240.

Caryocrinus ornatus Say. Silurian ; Lockport, New York.
(/, Calyx from one side, with two arms attached ; b, Summit,
natural size ; c, Inner and outer surfaces of calyx plate of the
second circlet, with pore-rhombs.

Family 3. Oallocystidae Bernard.

Calyx composed of large plates arranged in three to five cycles, and exhibiting
three to five pectinated rhombs, the component halves of which stand on contiguous plates,
and are separated by an interval. Mouth forming the centre of radi-
ation for two to five brachioliferous food-grooves which are protected
by covering pieces, and either repose upon the calyx, or are sunk below
the surface in grooves. Stem well developed, tapering distally to a
point. Ordovician and Silurian.

n

Subfamily A. Callocystinak Jaekel.

Fseudocrinites Pearce (Fig. 241). Calyx ovate,
two- to four-sided, and composed of four cycles
of polygonal plates. Anus closed by valvulär
pyramid, and occupying a lateral position. Pore-
rhombs three in number; one placed above the
base, the remaining two to the right and left of
the anus. Arms two to four, reoumbent upon the
calyx, extending to the base, and beset with biserial
jointed pinules. Stem robust. Silurian ; England.

Callocystites Hall {Anthocystis Haeckel) (Fig. 242).
Calyx olive-shaped, the oral end being more attenuated and obtusely pointed.

Fig. 241.

l'seiuiocrinites quadrifasciatus
Pearce. Silurian ; Tividale, Eng-
land. A, Calyx from one side.
B, Summit, showing mouth (m),
anus (o), and three of the anns.
The foiirth arm (i;), broken away,
exposing flattened surface of calyx.

154

ECHINODERMATA— PELMATOZOA

PHYLUM IV

the base flat or truncated ; plates twenty-five in number. Arms sometimes
bifurcating. Silurian ; North America.

Apiocystites Forbes. Calyx regularly oval, elongate or slightly compressed,
and composed of nineteen plates. Silurian ; England, Sweden and North
America.

Hallicystis Jaekel. Like the preceding, except in having five deltoid
plates instead of one. Silurian.

Lepocrinites Conrad (Lepocrinus or Lepadocrinus Hall ; Staurocystis Haeckel).
Silurian ; New York and Tennessee.

Lepadocystis Carp. {Meehocystis Jaekel). Ordovician ; North America.

Sphaerocystites Hall ; Coelocystis, Jaekelocystis, Tetracystis and Trimerocystis
Schuchert. Silurian ; North America.

Strohilocystites White. Devonian ; North America. Hybocystites Wetherby
Silurian ; North America.

Fig. 242.

Calloeystites jewetti Hall. Sil-
urian (Niagara Group) ; Lock-
port, New York. Calyx seen
from one side (natural size). a,
anus ; hr, bracliioles, j-), pectino-
rhombs. x § (after J aekel).

Fio. 243.

Pleurocystites filüextus Billings. Ordovician ; Ottawa,
Canada. A, Calyx from the anterior side. B, Same
from tlie anal side ; A, anal area ; a, anus ; h, basals ;
br, bracliioles ; g, genital aperture ; l 1-2, laterals ; m,
madreporite. x | (after Jaekel).

Subfamily B. Glyptocystinae Jaekel.

Pleurocystites Billings (Fig. 243). Convex side with large plates arranged
in cycles ; flattened side covered with very minute plates. Three isolated
pore-rhombs borne on the convex side. Arms two in number, robust. Stem
round, tapering distally to a point. Ordovician ; Canada.

Glyptocystites Billings. Ordovician ; Canada and Russia.

Cheirocrinus Eichwald ; Cystoblastus Yolborth. Ordovician ; Russia.

Homocystites Barrande. Ordovician and Silurian ; Bohemia.

Subfamily C. Echinoencrininae Jaekel.

Echinoencrinus v. Meyer {Sycocystites v. Buch and Gonocrinites Eichw.) (Fig.
244, A). Calyx composed of four basal plates, and three cycles containing five
plates each. All calycine plates ornamented with costae or ridges radiating

CLÄSS I

CYSTOIDEA

155

B

outward from the ceiitre. Ventral surface with short ambulacral grooves, and
articular facets for the attachment of three small arms. Anus removed to a
iateral position between the first and
lecond circlet of side plates. Three
^pore-rhombs present ; of these, two are
situated above the base on the side
opposite the anus, and the third above
and slightly to the right of the anus.
Stem round, short, tapering distally
to a point, and composed of hollow
Segments inserted one within the other
like the draw - tubes of a spy-glass.
Ordovician; Kussia. *

ScoUocystis, Erinocystis (Fig. 244, B)
and Glaphjrocystis Jaekel. Ordovician ;
Russia.

Prunocystis Forbes.

Schizocystis Jaekel. Silurian ; England

Fig. 244.

A, Echinoencrinus senckenbergi v. Meyer. B,
Erinocystis volhorthi Jaekel. a, anus ; h, basals ; l,
laterals ; p, pectino-rhombs. x | (after Jaekel).

Order 3. DIPLOPORITA Zittel (emend. Bather).

Radial symmetry affects food-grooves, and to some extent the calyx plates connected
therewith. Food-grooves extended over the ccdyx plates themselves, and prolonged to
brachioles which line the calyx grooves. Pectinated rhombs and pore-rhomhs not
developed ; hut calyx plates may he folded, and diplopores always present.

Family 1. Sphaeronitidae Neumayr.

Calyx globular or cylindrical, short-stemmed er stemless, and composed of
numerous irregularly arranged plates with pores united in pairs. Ambulacral

grooves either open or protected by
A ß covering plates, and either short and

simple, or elongated and branching,
not extending from the mouth beyond
the adoral circlet of plates. Arms
ür«><Ss/2^Tft»r'^ . ö^s a rule exceedingly small and
primitive. Ordovician and Sil-
urian.

Sphaeronites Hising. {Pomo-
cystis Haeckel) (Fig. 245). Glo-
bose, stemless. Five short ambu-
lacral grooves radiating from the
mouth towards the arm bases.
Ordovician (Vaginatenkalk) ;
Russia, Sweden and England.
S. pomum Gyll.

Eucystis Angelin. Ordovician ; Sweden.

Trematocystis, Palmocystis, Archegocystis and Codiacystis Jaekel. Ordovician ;
Bohemia.

Allocystites S. A. Miller. Silurian ; North America.

Fig. 245.

Sjihacronites globulus Angelin. Ordovician, Sweden. A,

Theca, lateral aspect. B, Oral aspect, enlarged. an, anus ;

hr, facets for attachment of brachioles ; g, genital aperture ;

0, mouth ; x, base for flxation.

156

ECHINODERMATA— PELMATOZOA

PHYLÜM IV

Proteocystites Barrande. Lower Devonian ; Bohemia. Carpocystis Q^hlert.
Lower Devonian ; France.

Family 2. Glyptosphaeridae Bather.

Food-grooves extend over the calyx well heyond the adoral ärclet, arid irregularly
transgress the sutures between the plates. Diplopores diffuse.

Glyptosphaerites Müll. (Fig. 228). DifFers from Sphaeronites in having
long, branching, ambulacral grooves, and a short, well-developed stem. Arms
recumbent and grooves beset with small plates. Ordovician ; Eussia and
Sweden.

Fungocystiies Barrande. Clavate. Ordovician ; Bohemia.

Family 3. Protocrinidae Bather.

Food-grooves extend over the calyx almost to the adoral pole, and are regularhj
hordered hy alternating plates on which are the brachiole-facets. Diplopores diffuse,
or confined to the adamhulacrals.

Frotocrinites Eichw. (Fig. 246). Nearly hemispherical, non-pedunculate.
Ambulacral grooves long and branching ; arms un-
known. Ordovician ; Russia and Bohemia.

Proteroblastus Jaekel (Dadylocystis) (Fig. 247).
Ordovician ; Russia.

Fig. 246.

Protocrinites oviformis Bichwald. Ordovician ; Pulkowa, Russia.
a, Calyx viewed from above ; h, Same from below showing basal
plate in the centre (affcer Volborth),

Fig. 247.
Froterohlastus schmidti Jaekel.
Ordovician ; Esthonia ; anih, food-
grooves ; hr, brachioles ; iamh,
inter-ambulacrals ; o, mouth (after
Jaekel).

Mesocystis Bather (Mesites Hoflfmann ; Agelacrinus Schmidt). Ordovician ;
Russia.

Family 4. Gomphocystidae Bather.

Amhuloxra in five main grooves curving around the calyx, and not prolonged to
the brachioles.

Gomphocystites Hall. Calyx flattened above, greatly elongate below, com-
posed of many irregulär plates, pierced by diplopores. Covering plates often
developed, and grooves sunk below the thecal surface. Silurian ; North
America and Gotland.

Pyrocystites Barrande. Ordovician ; Bohemia.

CLASS I

CYSTOIDEA

157

Order 4. APORITA Zittel (emend.).

Radial symmetry affects food-grooves and calyx plates. Food-grooves hörne on
processes aroimd the oral centre. No folds, rhombs or diplopores.

This division is admittedly artificial and ill-defined, being chiefly a
receptacle for genera whose relations are imperfectly understood, or whose
systematic position is doubtful.

Family 1. Oryptocrinida© Zittel.

Calyx composed of three rings of very finely perforate or imperforate, somewhat
regularly arranged plates. Mouth central, surrounded hy articular facets for the
attachment of small arms. Anus eccentric ; stem round and
slender. Ordovician to (?) Permian. l iH

Cryptocrinus v. Buch (Fig. 248). Base composed of
three plates, and surmounted hy two zones, each con-
taining five plates of unequal sizes. Mouth and anus
enclosed within a ring of smaller pieces. Ordovician ;
St. Petersburg. G. cerasus v. Buch.

Lysocystites Miller (Echinocystites Hall non Wyv.
Thomson, Scolocystis Gregory). Silurian (Niagara
Group) ; North America.

Hypocrinus Beyrich. This a i

genus, described as a Cystid,
from the Permian in the Island
of Timor, and Coenocystis Girty,
from the same formation in
western America, are probably
Crinoids.

Family 2.

Macrocystellidae
Bather.

Fia. 248.

Crijptocrinuscerasnsw Buch.
Ordovician ; Pulkowa, Russia.
a, b, c, Calyx from one side,
from above, and from below
(nat. size); m, Mouth ; a, Anus.

Fig. 249.

Macrocystella manae Call.
A, from side x 1/1. B-D, por-
tion of a brachiole, x8/l,
from side, dorsal and ven-
tral surfaces. B, Single plate
enlarged (after Bather).

Calyx consisting of three or four
circlets of plates, displaying more
or less pentamerism. No pores ar
rhombs. Cambrian.

Macrocystella Calloway.
(Mimocystites Barr.) (Fig. 249). Three ranges of five plates each, followed
by a fourth of the same number bearing bifurcating brachioles. Radiating
folds strongly marked, dividing surface into triangles. No rhomb structure
visible. Stem rapidly tapering. Pentamerous symmetry is well marked,
and the form might be characterised as a tri-cyclic Crinoid. Cambrian ;
England.

Lichenoides Barr. (Lichenocystis Haeckel). Cambrian ; Bohemia and
Bavaria. Aethocystis S. A. Miller. Silurian ; Indiana.

Family 3. Tiaracrinidae Bather (emend.).

Calyx composed of not more tjian two circlets of plates : three (hasdls) in the first,
and four (radials) in the second ; followed hy a ränge of short plates resemhling

158 ECHINODERMATA— PELMATOZOA phylum iv

brachials surrounding the peripher^ of the tegmen, either in an almost continuous
ring, or in groups where the interoral sutures meet the radials. Whether there are
further brachials in succession is unJcnown. Stern with a small axial canal.
Silurian and Devonian. Relations doubtful, may be monocyclic Crinoids.

Zophocrinus S. A. Miller, has arm plates in Clusters of about three. Surface
smooth. Silurian ; North America.

Tiaracrinus Schnitze {Staurosoma Barrande). Arm plates eight or ten to
each radius, forming a rather continuous ring. Surface strongly marked with
folds crossing the sutures, which seem to be accompanied by pores. Devonian ;
Eifel, France, Bohemia.

Order 5. BDRIOASTEROIDBA Billings.

(Syn. : Thyroidea Chapman, 1860; Agelacrinoidea^. K.MiWqv, 1877-1883;
Gystasteroidea ^tQmm.B:im^ 1888; Bernard, 1893; Thecoidea 3 a^okeX, 1895).

The eminent Canadian paleontologist, E. Billings, as early as 1854, called
attention to the great difFerence between the forms now grouped under this
name and the typical Cystideans, and in 1858 suggested that they should be
arranged as a suborder to be called Edrioasteridae. Subsequent authors have
generally agreed to this in principle, but not as to the relative rank which the
group should have. Bather, regarding it as a class, assigns it equal rank with
the Cystids, Crinoids and Blastoids. Jaekel recognises it as one of three
Orders into which he divides the Cystidea {sensu L. von Buch), and this pro-
cedure is in principle here adopted, without, however, denying that it may be
entitled to the higher rank. Bather's definition and general characterization
of the group is substantially as follows :

Pelmatozoa in which the theca is composed of an indefinite numher of irregulär
plates, some of which are variously differentiated in different genera ; with no subvective
skeletal appendages, but with central mouth, from which there radiate through the theca
five unbranched ambulacra, composed of a double series of alternating plates {covering-
plates), sometimes supported hy an outer series of larger alternating plates {side-plates
or flooring -plates). Pores between {not through) the ambulacral elements, or between
them and the thecal plates, permitted the passage of extensions from the perradial
water-vessels. Anus in posterior interradius on oral surface, closed by valvulär
pyramid. Hydropore {usually, if not always, present) between mouth and anus.

This would represent primitively, as Bather explains, a form with flexible
sack-like calyx, composed of numerous irregulär, polygonal plates deposited
in the integument ; having a mouth in the centre of the upper surface, and
being attached by some indefinite portion of the lower surface. The struc-
ture of the ambulacra would remove it far from the earlier Amphoridea,
among Cystids, from which group it may haVe been derived.

Upon this primitive ancestral form the following characters were, to a
greater or less degree, impressed : a sessile habit ; the consequent assumption
of a circular, flattened form; the difFerentiation of the upper and under
surfaces ; the development of marginals or concentric frame-plates ; and the
tendency to increase the food-gathering surface by spiral coiling of the ambu-
lacra. According to the varying extent of these modifications, the order is
divisible into three families : Agelacrinidae, Cyathocystidae, Edrioasteridae.

The Edrioasteroidea have a somewhat greater geological ränge than the

CLASS I CYSTOIDEA 159

majority of Cystids, extending from the Cambrian to the Lower Carboniferous.
Two geriera, Agelacriniis and Edrioaster, are fairly abundant in certain localities
of North America, but the others are rare.

Family 1. Agelacrinidae Hall.

Calyx composed mostly of thin plates, flexible, attached temporarily or per-
manently hy the greater pari of the aboral surface ; ambulacra confined to the oral
surface. Cambrian to Carboniferous.

Agelacrinus Vanuxem (Fig. 250). Calyx in the form of a depressed or
convex disk, stemless, and attached by the entire under surface ; composed of
numerous, small, polygonal, usually imbricating
plates, which are perforated by fine, usually
conjugate pores. Mouth surrounded by four
oral plates ; radiating from this are five small,
more or less curved food-grooves, which are
embedded in the disk, and are protected by a
double row of covering plates. Ordovician ;
North America, Rhineland and Bohemia. Rare
in Silurian and Devonian.

Stromatocystis Pompeck j. Cambrian; Bohemia.

Cystaster Hall {Thecocystis Jaekel). Streptaster fig. 250.

Hall. Ordovician ; Ohio. 'Agelacrinus cindnnatiensis Roemer.

. Hemky Stiles Hall. Ordovician and Silurian ; SÄ'Äe SÄlieÄren'^tJ;

North America and Bohemia. ^^^t of liafinesqulna altemata (Conrad).

Haplocystis Roemer. Devonian ; Rhineland.

Lepidodiscus Meek and Worthen. Devonian to Carboniferous ; North
America. Discocystis Gregory. Carboniferous ; North America.

Family 2. Oyathocystidae Bather.

Calyx composed on the oral surface of five deltoids surrounded by margmals, hut
below of a fused solid mass of stereom, with irregulär longitudinal sutures ; ambu-
lacra confined to oral surface ; permanently attached by the aboral surface, as by an
encrusting roof. Ordovician.

Cyathocystis Schmidt. Ordovician ; Esthonia.

Family 3. Edrioasteridae Bather.

Calyx flexible, composed of thin plates ; attached, if at all, by a small central
portion of the aboral surface ; ambulacra pass on to the aboi'al surface. Ordovician
to Devonian.

Edrioaster Billings (Aesiocystis Miller and Gurley) (Fig. 251). Ordovician ;
Canada and Kentucky.

Dinocystis Bather. Devonian ; Belgium.

^ Cyclocystoides Billings and Salter. Ordovician ; North America and Great
Britain. Probably a Cystid, but not sufficiently known to be assigned to any
particular family.

160

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Family 4. Steganoblastidae Bather.

Calyx rigid, composed of plates relatively larger and thicker than in other
f amilies of this group, including elemenfs comparable to the radials and basals of
Blastoidea. Ämbulacra descend into the radials. Ä short stem present. Ordovician.

SteganoUastus Whiteaves (originally described as Astrocystites, name pre-
occupied). In all the prominent external characters resembling a Blastoid,
but careful study of the type specimens by Bather has shown the ämbulacra
to have essentially the same structure as in Edrioaster, and that brachioles are
absent. Ordovician ; Canada.

am

P anit yg gj

Fio. 251.

Edrioaster bigsbyi Bill. Ordovician ; Ottawa, Canada. 1, Oral surface with covering plates (amh) on two
of the grooves, and side- or flooring-plates {ad) on the others, x 1/1. 2, Vertical section of same, 1/1. 3, Sec-
tion across an ambulacrum, enlarged. Ad, flooring-plates ; amb, covering-plates ; as, anus ; ia, interambu-
lacrals ; M, madreporite ; m, membrane with imbricating plates, thrown into live lobes (0 ; /, frame of stouter
plates ; ps, subtegminal peristome ; 2\ pores ; vg, ventral groove (after Bather).

The following generic names have been incorrectly applied to Cystids :

Ascocystües Barrande. Probably a Camerate Crinoid.

Camarocrinus Hall. {Lobolithus Barr.). Inflated or bulboiis root of the Camerate
Crinoid, Scyphocrinus.

Cardiocystis Barrande. Indeterminable.

Orinocystis Hall. Probably a Camerate Crinoid.

Cyclocrinus Eichwald (Pasceolus Billings). Not an Echinoderm,

Dictyocrinus Conrad. A Receptaculite.

Hyponome Loven. The ejected disk of a Comatulid.

Lichenocrinus Hall. The terminal stem-plate or root of some Pelmatozoan.

Neocystites Barrande. Probably the root of a Pelmatozoan.

Forocrinus Billings. An Inadunate Crinoid.

Range and Distribution of the Cystoidea.

The Cystideans, a wholly extinct class, are the oldest known members of
the Pelmatozoa. They are represented in the Cambrian by a number of poorly
preserved forms, whose affinities are in many cases doubtful {Protocystites,
Macrocy Stella, Eocystites, Lichenoides, Trochocystites). They attain their maximum
development in the Ordovician and Silurian, whereupon they suddenly dimiiiish
in numbers, and probably disappear in the early Carboniferous. Of the 250
species that have been described, scarcely a dozen are found in strata above
the Silurian.

CLAss II BLASTOIDEA 161

Although a fcvv forms (EchinosphaeriteSj Aristocystites, Caryocystites) appear
in considerable abuudaiice in certain formations, and are locally profuse in
some beds, the majority are of comparatively rare occurrence. The brachioles
are only exceptionally preserved, owing to their fragile Constitution, and the
stem is also usually lost.

Cystideans are found most plentifully in the Ordovician rocks of St.
Petersburg, Russia, and in the Silurian localities of Oeland, Gotland, Sweden,
Wales and Bohemia (fitage D). The Bohemian specimens are usually pre-
served in the form of casts and moulds, and are contained in siliceous or
argillaceous slates. The Chazy and Trenton limestones of Canada, New York,
Ohio and Indiana also yield a large variety of forms.

Excellently preserved specimens of Fseudocrinites, Apiocystites, Echinoen-^
crinus and Anomalocystites are obtained from the Silurian limestones of Dudley
and Tividale, England ; and similar forms (Lepadocrinus, Callocystites, Caryo-
crinus) are found in the Silurian (Niagara Group) of North America. Only
scanty remains are known from the Devonian, and from the Lower Carboni-
ferous but a single genus, Lepidodiscus.

Two genera have been described from the Permian, Hypocrinus Beyrich,
and Coenocystis Girty; but their systematic position is doubtful, and until more
is known of their strukture they may be left out of consideration.

Olass 2. BLASTOIDEA Say.i

Extind, short-stemmed, or stemless Pelmatozoa with a rigid calyx resemhling a
flower-bud in shape, witK pentamerous symmetry predominant (occa^ionally modified
hy atrophy), usually composed of thirteen principal plates. Food-grooves lying in
lanceolate or linear areas {amhulacra or pseudambulacra) which radiale from a
central perisfome hetween five interradial deltoid plates and are not crossed hy sutures
hetween calyx plates ; they hear at their lateral margins pinnule-lihe appendages, and
from their inner floor hang lamellar tubes known as hydrospires. Grooves and peri-
stome protected by small, movable covering

The calyx is clavate, pyriform, ovate or globose, frequently pentangular
at its Upper face, and composed of plates which are firmly united among
themselves. The plates of the abactinal System are arranged in three suc-
cessive cycles, represented by the basals, radials and interradials or deltoids.
The plates of the actinal system comprise the summit plates and the ambulacra.

The basals consist of two plates of equal size, and a third smaller one,
which is directed invariably toward the right anterior interradius. Resting
upon the basals are five V-shaped, usually equal radials (commonly known

^ Literatiire : Say, T., Ohservations on some Species of Zoophytes, etc. Amei\ Journ. Sei., 1820,
vol. ii. — Say, T., On two Genera and several Species of Crinoids. Journ. Acad. Nat. Sei. Philad.,
1825, vol. iv. (Also in Zool. Journ., 1825, vol. ii.) — Roemei\ F., Monographie der fossilen
Crinoidenfamilie der Blastoideen. Troschel's Archiv für Naturgesch. , 1851, Jahrg. xvii., vol. i. —
Jiofe, J., Notes on Echinodermata. Geol. Mag., Dec. 1, 1865, vol. ii. — Billings, K, Notes on the
Structure of Crinoidea, Cystoidea, and Blastoidea. Amer. Journ. Sei. 2nd ser., 1869-70, vols.
xlviii.-l. — Etheridge, R., and Carpenter, P. IL, Catalogue of the Blastoidea in the Geological
Department of the British Museum, 1886. [Complete bibliogi-aphy, pp. 303-310.]— ßo^/jgr, F. A.,
Genera and Species of Blastoidea, with a list of specimens in the British Museum, 1899. [Complete
index of names with references to literature.] — Bather, F. A., Treatise on Zoology (Lankester).
Part III., Echinoderma, 1900. — Hambach, G., Revision of the Blastoidea. Trans. Acad. Sei.
St. Louis, 1903, vol. xiii. — Hitdson, G. H., Pelmatozoa from Chazy Limestone. New York State
Museum Bull. No. 107, 1907.

VOL. I M

62

ECHINODERMATA— PELMATOZOA

PHYLUM IV

as ^^forked plates "), whose superior margins are more or less deeply incised by
the radial sinuses. The term sinus is applied to the open space between the

two prorigs or limhs of the plate (Fig. 252).

Succeeding and alternating with the radials,
and resting upon their limbs, are five interradial
or deltoid plates, which vary excessively in size ;
they are considered to be homologous with the
oral plates of the Crinoids. In some species they
occupy a large part of the sides of the calyx, and
in others they are confined to the upper face.
In Nudeocrinus and certain species of Orhitremites,
the deltoids extend down so far into the calyx as
to constitute more than half, or nearly the whole
of its sides, while the radials are so short as to
be almost invisible in a side view. Only a part
of the deltoids is exposed to view, their sides
being provided with flanges which are covered
by the outer ends of the ambulacra. The name
deltoid has reference to the exposed part of the plates, which in most forms
is triangulär or rhomboidal in outline.

The radial sinuses between the limbs of the radials and the super jacent
deltoids are filled by the ambulacral fields or ambulacra (^' pseudambulacra " of
Roemer). The ambulacra vary in form from petaloid to narrow lanceolate or
linear, and extend from the summit of the calyx to the distal ends or lij)S of
the radial sinuses. The open space in which the ambulacra meet, the so-called
'* summit- opening " or peristome, is pentangular, and central in position. Ordin-
arily this space is open, but in well-preserved specimens it is covered
by a greater or less number of minute calcareous pieces (Fig. 253); these

Fig. 252
Pentremites godoni (Defr.J.
of calyx. h, Basais ;
Interradials or deltoids

Analysis
Radials ; ir,

Fig. 253.

A, Orhitremltes norwoodi (O. and S.). Upper face of perfect specimen, with inouth and anus (a) closed by
plates. Spiracles {sp) separate. B, Orophöcrinus stelliformis (O. and S.). Upper face with closed peristome and
exposed anus. Spiracles slit-like. C, FeMremites sulcatus Roem. Central mouth-opening surrounded by five
spiracles, the posterior one confluent with the anus. D, Cryptohlastus melo (O. and S.). Upper face with
central mouth-opening, large anus, and eight spiracles (after Carpenter). All specimens from Burlington
Group; Iowa.

may be either regularly or irregularly arranged, but leave at each angle of
the summit-opening a small passage-way, by means of which the ambulacra
communicate with the peristome. The mouth is invariably subtegminal.

The summit structure is rarely observed. The small plates which cover
the peristome are merely extensions of the ambulacral covering plates variously
modified in shape. In Nudeocrinus, Orophöcrinus and Schizoblastus sayi, the
central Space is occupied by five asymmetrical plates, formerly called orals,
surrounded by smaller ones toward the grooves. In Orbitremites norwoodi and

l.,

BLASTOIDEA

163

Cryptohlastus meto the plates are all small and irregularly arranged. In the
genus Pmtremites the covering plates are modified in a singularly different
way : toward the centre they become increasingly elongate and spine-like,
suiTounding not only the central opening, but also the spiracles and anal
aperture, with a fringe of tapering spines, which meet over the summit in a
tuft-like stellate pyramid, with salient angles interradial.

The summit in most Blastoids is surrounded by a cycle of five pairs of
openings ; and between the two posterior ones there is usually interposed
a Single additional aperture. The former were regarded by Roemer as con-
nected with the genital System, and were called by him " ovarian apertures " ;
but they are now known as the spiracles. The other opening which pierces
the Upper end of the posterior deltoid is the anus.

The form and arrangement of the spiracles is extremely variable ; they
may be round or slit-like ; they may consist of ten separate openings, or those
of the same pair may be con- ^ ß

fluent with one another. The J

members of the posterior pair
may be fused with each other
and with the anus, in which
case the fifth or posterior
spiracle is considerably larger
than the others. Orbitremites,
Fentremites, Pentremitidea, etc.
(Fig. 254, A), are examples of
the latter case ; Orbitremites
having five circular orifices
with tube - like projections,
while in Pentremites and Pent-
remitidea the four smaller
spiracles are divided into two
compartments by the terminal
median ridge of the deltoids.
The posterior spiracle in the
two latter genera is divided

A, Pentremi

Fig. 254.
godoni (Defr.). Lower Carboniferous ; Alabama.
Upper face with ambalacral fields in various states of preservation.
a, Ambulacrum after the removal of lancet- and side-plates ; hydro-
spires exposed ; b, Lancet-plate with upper surface denuded by
weatliering ; c, Perfectly preserved lancet-plate bordered by side-
plates ; d, The same, but with transverse markiiigs of lancet-plate
obliterated ; e, Ambulacrum covered with pinnules (after Roemer),
B, Fhaenoschisma acutum (Swhy.) Lower Carboniferous ; Lancashire.
Upper face, enlarged ; a, Ambulacrum after removal of the lancet-
and side-plates ; hydrospire slits (Jiy) cutting through radials and
deltoids ; h, c, Ambulacra in which lancet-plates (l) only are pre-
served : d, e, Ambulacra intact ; lancet-plate concealed by side-plates
(after Etheridge and Carpenter).

by a duplicate ridge into three
compartments ; of these the middle one enters the inner cavity, and the two
outer ones communicate with the hydrospires by means of the hydrospire
canal. In Troostocrinus, Schizoblastus and Cryptoblastus (Fig. 253, B) the
posterior spiracles are confluent with the anus, while those of the four regulär
sides are separated. Nudeocrhius, Mesoblastus and Acentrotremites have ten
separate spiracles, and a large, distinct anal aperture. The typical Codasteridae
(Codaster and Phaenoschisma), in which the hydrospires are exposed externally,
have no spiracles and no hydrospire canal. Orophocrinus (Fig. 253, B) has
ten elongate clefts extending along the sides of the ambulacra ; but these are
in reality the unclosed portions of the radial sinuses, and correspond to the
open hydrospire canals of Pentremites, which are apparent upon the removal of
the side-plates.

The ambulacra are usually depressed below the general level of the calyx,
but are sometimes raised above it, or they may be placed in the same plane
with it. They vary in form from narrow linear to broad petaloid, and are

164

ECHINODERMATA— PELMATOZOA

PHYLUM IV

considerably complicated in structure (Fig. 255). The centre of each ambu-
lacrum is occupied by the lancet-plate, a long, narrow piece, pointed at both
ends, which extends to the füll length of the fields. Its proximal end is
inserted between the deltoids, and takes part in the lip around the summit-
opening. The upper surface of the plate is excavated along the median line,

and forms an open, well-defined groove, which
conducts to the mouth, and in all probability
represents the food-groove. The interior of the
plate is traversed by an axial canal, which com-
municates by means of the ambulacral opening
with an oral ring belonging to the water-vascular
System. In a number of forms (Fentremites,
Orophocrinus) there is to be seen a second,
smaller, and extremely thin plate underlying
the median portion of the first ; this is called
the unde7' lancet-plate.

The lancet-plate rarely occupies the füll

width of the ambulacral field, and the spaces

'^^^'- 2''^- between its lateral edges and the sides of the

o,i^^^;^Z^1^;^i!^^S^ radial sinus are either wholly or partially

plate {}) ; median food-groove of the same covered bv a row of small, horizontally elongated

(ci) ; side-plates (s) ; oiiter side-plates (e) ; i , /cc i ^ v c -r> \ t r. ^

and marginal pores (p), 5/i, (after B. and stde-plates (" pore-plates Ol Koemer). In Feiit-

C). -B. Ambulacrum of Nuckocrinus. -j r\ i • ^ i-i n t

Lettering as in ^ (after Roemer). vemites, Orophocnnus, and other genera, an addi-

tional series of still smaller pieces, called the
outer side-plates (^^ supplementär y pore-pMes" of Roemer), are placed between
the side-plates and the walls of the radial sinus. Fentremites and Cryptoschisma
have the entire upper surface of the lancet-plate exposed to view, and the
side-plates are situated alongside of it in the a
same plane. But in other forms the lancet-plate
is wholly, or to a very large extent, concealed by
the side-plates (Fig. 255, B), so that as a rule
only a small space along the food-groove is visible.
The sutures between the side-plates are indicated
by shallow, horizontal furrows, which are con-
tinued as superficial grooves over both halves of
the lancet-plate as far as the median ambulacral
groove. These crenulations, it should be noted,
are frequently effaced in weathered specimens
(Fig. 255, ^ and B). Small, pit-like depressions,
or small tubercles, which are observable on the
side-plates, indicate the places where the append-
aeres or pinnules were f ormerlv attached. These are perfoctiy preserved pinnuies (afte/Meek

1 X- ^^ £ j ■ \. j. ^ ^ i and Worthen).

only exceptionaily lound nitact, but when pre-
served they completely conceal the ambulacral fields, and extend upward above
the summit of the calyx (Fig. 256). They difFer considerably in length, even
among species belonging to the same genus. They are jointed structures like
miniature arms, uniserial as far as observed, but with ossicles sometimes
wedge-shaped and interlocking to some extent from opposite sides, thus
simulating a biserial arrangement. Whether they performed the function of
discharging the ova, like the pinnules of Crinoids, can only be conjectured.

Fig. 256.

a, Pinnule of Fentremites, enlarged ;
Orhitremites norwoodi (O. and S.) with

l.,,

BLASTOIDEA

165

The crenulations, or file-like markings across the ambulacra in Pentremites
above iioted, are not mere surface ornamentation ; but the ridges constitute
the sides, and the depressions the floor, of a series of small ducts leading from
the pinnules, and forming lateral branches of the main ambulacral groove
into which they discharge. These lateral ducts, as well as the main median
groove of the ambulacrum, are, in well-preserved specimens, roofed over
throughout the entire field by very minute alternating covering plates extend-
ing all the way to the pinnules, and probably continuing along their ventral
side. In this respect the structure of the ambulacral area has not been
generally understood, and not heretofore correctly described. The arrange-
ment of the side ducts, their discharge by a distinct curvature into the main
groove, and their connection with the pinnules, leave no doubt that they
were the closed food-grooves serving to conduct nutriment from the pinnules
on toward the mouth.

In most Blastoids the side-plates, or the outer side-plates when such are
present, are pierced by marginal pores (or hydrospire pores), which communicate
with the hydrospires. The pores are situated at the extreme outer margins
of the plates, at the end of the lateral ridges, and
alternate in position with the sockets of the pinnules.
They are present in all forms having the hydrospires
concealed within the calyx ; but are absent in the
Codasteridae, in which the hydrospires are wholly or
in part exposed on the outer surface.

The hydrospires (Figs. 257, 258) are bundles of
flattened, lamellar tubes, extending underneath the
lancet- and side-plates, in a direction parallel with
the boundaries of the ambulacral fields. They begin
at the lower end of the ambulacra, and terminate in
the hydrospire canals, of which the spiracles form the
adoral apertures. When the spiracles are confiuent,
the canals of adjacent groups of hydrospires enter the J;

same opening. The hydrospires are suspended in the Vs^^the hdght «f^tue^^^^bi^^^^^^^
majority of forms along the walls of the body-cavity i, LaAcet-piate ; p, Pore-piates;
(Pentremites, Fig. 257), being attached either to the ^'

outer margins of the under lancet-plate or to a separate piece known as the
hydrospire plate (Orbitremites, MesoUastus and Cryptohlastus). Pentremites has

--^^..f

Pentremites sulcatusSaj. Lower
Carboniferous ; Illinois. Trans-
erse section of calyx at about

mps)^

Fig. 258.
Transverse sections through the ambulacral fields, showing various forms of hydrospires. A, Orhitremites
derhijemis. B, Orbitremites nonoooiU. C, Metablastus lineatus. D, OropTiocrinus verus. All sections enlarged
(after Etheridge and Carpenter).

from f our to nine hydrospires in each group ; Orhitremites two, or exceptionally
one ; Troostocrinus and MesoUastus generally three, and Orophocrinus from five
to seven (Fig. 258, A-D). In Phaenoschisma and Codaster (Fig. 260) the tubes

166 ECHINODERMATA— PELMATOZOA phylüm iv

open externally by slits piercing the radials and deltoids and running parallel
with the ambulacra.

The functions of the hydrospires can only be surmised, but they are sup-
posed to have served for respiration : they correspond doubtless to the pec-
tinated rhombs and calycine pores of the Cystideans and to the respiratory
pores of some Crinoids. It is probable that water was admitted to the
hydrospire sacs through the marginal pores, and was discharged through the
spiracles. Roemer and Forbes have suggested that the hydrospires may
also have performed reproductive functions. Ludwig has called attention to
the resemblance between the genital bursae of Ophiuroids and the slit-like
spiracles in Orophocrinus ; his theory is that the hydrospires served both for
purposes of respiration and for the discharge of genital products, a view
which was also shared by Carpenter.

The stem in Blastoids is preserved only in exceedingly rare instances. It
is round, provided with a small axial canal, and composed of short joints,
which apparently multiplied in a similar manner to that in the Crinoids. In
Orophocrinus and Pentremites it has been traced for a length of 15 cm. without
reaching the end; and in the latter form it has occasionally been found with a
few, comparatively heavy cirri. A f ew genera, like Eleutherocrinus, are stemless.

It has frequently been claimed, owing to the superficial resemblance of
their ambulacral areas, that the Blastoids and Echinoids are mutually related ;
but such presumptions are founded upon a total misconception of the value
of external characters. The construction of the calyx, the presence of pin-
nules, and the stemmed condition, are features which identify them unmis-
takably as Pelmatozoa ; and their nearest relatives under this group are the
Cystideans. The parallelism between the ambulacral fields of the one class
and the recumbent arms, apparently soldered on to the calyx of the other, is
self-evident. The hydrospires of Blastoids correspond to the pore-rhombs of
Cystideans, as has already been remarked ; and the position of the mouth and
anus is the same in both types. The Blastoids constitute a peculiar, but, on
the whole, a very well-defined group, which is now regarded as of equal rank
with the Crinoids and Cystids.

: The earlier forms occurring in the Ordovician are primitive, representing
transitions from ancestors of Cystid type, and having the characters of the
two groups intermingled in varying degrees. In one genus, Asterohlastus, the
presence of diplopores and lack of hydrospires are correlated with the presence
of the Blastoid ambulacrum together with its bordering pinnules, and more
strongly developed basals and radials. In another, Blastoidocrinus, the diplo-
pores are replaced by hydrospires, thus further strengthening a line of
development which becomes thoroughly established in the Silurian with the
genus Troostocrinus.

Several genera are represented in the Devonian, both of Europe and
America. But the climacteric of Blastoid development takes place in the
Lower Carboniferous of North America ; some of the beds of the Kaskaskia
Group are densely charged with their remains, which, as a rule, are excellently
preserved. They occur sparsely in the Upper Carboniferous and Permian of
western America and the island of Timor, but above this horizon no traces of
Blastoids have as yet been discovered. Nineteen genera, comprising upward
of 120 species were recognised by Etheridge and Carpenter in their mono-
graph of 1886, and a few have been added since.

OLASS II BLASTOIDEA 167

The last-named authors subdivided the Blastoids into Begulares and
Irreguläres, an arrangement representing incidental Variation rather than any
broad morphological differentiation. That presented by Bather in Part III.
of Lankester's Zoology, 1899, appears to be more logical, and is followed in
principle here. By separating the typical Blastoids, in which the character-
istic calyx plates have become fixed at a small and definite number, from the
earlier forms which have not attained that structure, two main divisions may
be recognised, viz. : ProtoUastoidea and EuUastoidea. Hudson, whose admirable
studies upon Blastoidocrinus have thoroughly elucidated that hitherto obscure
type, has suggested a third, FaraUastoidea, to express the differences shown by
his researches between it and the other Ordovician forms. As the general
division is a somewhat arbitrary one at best, it is thought that these differences
are sufficiently emphasised by the family diagnosis.

Order 1. PROTOBLASTOIDBA Bather (einend.)
Calyx plates numerous, not limited to a definite numher.

Family 1. Asteroblastidae.

Blastoidea with calyx plates indefinitely arranged ahove basals and radials, and
having, along wiih pentamerous ambulacra
ami marginal hrachioles, diplopores and
pore-plate, hut no hydrospires. Ordovician.

Asterohlastus Eichw. (Fig. 259). Calyx
gemmiform, pentagonal, pedunculate, and-
composed o£ numerous rigidly united
plates which are perforated by conjugate
pores. Upper surface marked by five fig. 259.

lircTP r»ptnlm'rl nr efpllnfp araaa wVnVli Asterohlastus stellatus Eichw&lA. Ordovician;

large petalOia Or Stellate areas Wtlicn Puikowa, Russia. Natural size (after Schmidt).

are occupied by alternating plates, and

bordered by sockets for the attachment of brachioles. Ordovician ; Russia.

Family 2. Blastoidocrinidae Bather (emend.).

Calyx plates more definitely arranged in four ciixlets, without diplopores or pore-
plate, hut with hydrospires present. Ordovician.

Blastoidocrinus Billings (emend. Hudson). Calyx pentagonal, composed of
four circlets of principal plates, viz. : (1) basals (number unknown) ; (2)
radials with angular distal face, followed by (3) two large plates called bi-
brachials, with numerous interbrachials in each interradius ; and (4) very
large triangulär deltoids, with hydrospire-slits at their lower margins
Adambulacrals, heavy covering plates, and some additional plates in the oral
portion. Ambulacra large, bordered with numerous brachioles or pinnules.
Base invaginate, with strong column occupying the concavity. Ordovician
(Chazy Group) ; Canada and New York.

Order 2. EUBLASTOIDEA Bather.

Calyx plates limited to a definite numher of ahout thirteen. Hydrospires always
present.

168

ECHINODEEMATA— PELMATOZOA

PHYLUM IV

Family 1. Oodasteridae Etheridge and Carpenter.

Base usually well developed, and sometimes very long. Amhulacra without
marginal pores. Hydrospire-folds Coming to the surface of the radial sinus.
Hydrospire-slits either wholly exposed, piercing the calyx plates along the sides of
the radial sinuses, or restrided portions of them remain open as spiracles, white
the remaining parts are concealed hy the amhulacra. Devonian and Lower
Carboniferous.

Codaster M'Coy (Codonaster Koemer; Heteroschisma WsLchsm.) (Fig. 260).
Calyx inverted, conical or pyramidal. Upper face broad, truncate or gently
convex ; section, as a rule, distinctly pentagonal. Basais forming a conical or
triangulär cup, usually deep. Kadials large, their limbs bent inward horizon-
tally, to assist in forming the truncated upper face of the calyx, and never
deeply excavated by the sinuses. Deltoids wholly confined to the upper face,
as are also the amhulacra. The latter are petaloid, or narrow and linear ;
lancet-plate, as a rule, deeply excavated for the side-plates. Spiracles absent,

Fig. 2Ü0.

Codaster acutus M'Coy. Lower Carbonifer-
ous ; Derbyshire. A, Side-view of calyx. B,
Base. C, Ventral aspect, enlarged (after
Roemer).

Fig. 261.

Oropliocrinus stelliformis (O. and S.). Lower
Carboniferous ; Burlington, Iowa. A, Calyx and
base of the natural size. B, Ventral surface en-
larged (after Meek and Worthen).

hydrospires pendent, arranged in eight groups, two in each of the four
regulär interrays, but wanting in the anal one. The tubes open externally
by a variable number of elongated slits, which are separated by intervening
ridges ; one or more of them may be partially concealed by the overlapping
side-plates. Anus large, ovate or rhombic, and piercing the posterior deltoid.
Ornament consisting of fine lines arranged parallel to the margins of the
plates. Silurian to Lower Carboniferous; Europe and North America.

Fhaenoschisma E. and C. (Fig. 254, B). Calyx resembling that of Codaster
in general form, but with ten groups of hydrospires instead of eight. Radiais
bear each three more or less distinct folds diverging from the lip; sinuses
wide and deep, generally with steep sides. Deltoids small, confined to the
truncated upper face of the calyx. Lancet-plates in all but one species
(P. caryophyllatum) concealed by the side-plates ; outer side-plates very small.
Spiracles rarely present. Hydrospires pendent, and opening externally by a
series of elongate slits with intervening ridges, distributed in sub-parallel
Order on the sloping sides of all the radial sinuses. The slits are only
partially covered by the ambulacral plates, and are sometimes visible for their
entire length. Lower Devonian ; Spain. Lower Carboniferous ; Europe and
North America.

CLASS II

BLASTOIt)EA

169

Cryptoschisma E, and C. Calyx elongated, with a broad, fiat, truncated
Upper face. Radial siiiuses wide and open, their sloping sides pierced by
hydrospire slits, which are completely concealed by broad, petaloid ambulacra.
Spiracles small, single or more rarely double ; in the latter case the posterior
pair are confluent with the anus. Represented by the solitary species C.
schultzi d'Archiac and de Vern. Lower Devonian ; Spain,

Orophocrinus v. Seebach {Dimorphocrinus d'Orb. ; Codonites M. and W.),
(Figs. 258 I), 261). Calyx balloon-shaped to truncate ob-pyramidal, with
more or less concave upper face. Section distinctly pentagonal or stellate.
Ambulacra narrow, linear to sub-petaloid. Deltoids generally visible in side-
view, the posterior one wider than the others. Spiracles ten, varying from
wide clefts along the sides of the ambulacra to narrow slits at their upper
ends ; the posterior pair separate from the anus. Hydrospire-slits almost
completely concealed, being concentrated at the bottom of the radial sinuses.
Stem round, composed of short, nearly equal joints. Pinnules extending to
nearly twice the height of the calyx, of uniform thickness throughout, and
composed gf sharply cuneate pieces interlocking from opposite sides ; ventral
furrow wide, and covered by small pieces. Lower Carboniferous ; Britain,
Belgium and North America (Kinderhook and Burlington Groups).

Family 2. Pentremitidae d'Orbigny.

Base usually convex, and often much elongated. Spiracles five, hut sometimes more
or less completely divided by a median septum, and bounded proximally by the upper-
most side-plates. Lancet-plate either entirely visible or partially covered by side-plates
which extend to the margins of the ambulacra.
Hydrospires concentrated at the lowest part of the
radial sinus. Devonian and Lower Carbon-
iferous.

Fentremites Say (Figs. 254-7, 262-3).
Calyx usually ovate or pyriform, with elon-
gate, sub-truncate base. Ambulacra broad,
sub-petaloid. Lancet-plate wholly exposed,
and resting below on an under lancet-plate.
Side-plates and outer side-plates numerous,
the former abutting against the edges of the
lancet-plates. Hydrospires three to nine;
spiracles single, or occasionally double ; the
two of the posterior side confluent with the
anus, and forming with it a single large
orifice. Oral centre surmounted by numerous
spines, placed closely against one another so
as to form a pyramid, which completely Covers
the summit and the greater portion of the Lower Carbon

• 1 1 1 • 1 T iferous ; III

spiracles. Lxcessively abundant m the Lower (Nat size).
Carboniferous of North America (Burlington
to St. Louis and Kaskaskia Groups), but not identified in Europe
Defrance, and P. pyriformis Say, are the most familiär species.

Pentremitidea d'Orb. Calyx clavate-pyramidal, with elongate, usually
conical base, and truncate or convex upper face. Aml)ulacra narrow, short ;

■ Fig. 2C2.

Pentremites
(jodoni Defr.

Fio, 263.

Pentremites svlcatus
Lower Carbon-
iferous; 111.; A, Summit
aspect. B, base.

Roemer.

P. godoni

170

ECHINODERMATA— PELMATOZOA

PHYLUM IV

lancet-plate more or less completely concealed by side-plates. Deltoids very
small, generally confined to the upper face of the calyx, and seldom visible in
a side-view. Spiracles and hydrospires as in the preceding. Lower and
Middle Devonian ; Eifel, Ardennes, Spain, Great Britain and North America
(Hamilton Group of Indiana, Michigan, Canada). P. pailletti de Vern.; F.
eifelianus Roemer ; F. davatus Schnitze.

Family 3. Troostoblastidae Etheridge and Carpenter.

Calyx elongate. Ambulacra narrow, linear, deeply impressed, descending out-
ward from the summit. Deltoids confined to the narrow upper end, rarely visible
A externally, except the posterior one in Troostocrinus. Lancet-

plate entirely concealed by side-plates. Spiracles distinct, repre-
sented by lineal slits at the sides of the deltoid ridge, and
bounded by deltoids and lancet-plates, but not by side-plates.
Silurian to Lower Carboniferous.

Troostocrinus Shum. (Clavaeblastus Hambach) (Fig.
264). Calyx narrow, elongate, somewhat fusiform, with
contracted, subtruncate, or slightly convex upper face.
Ambulacra short. The four anterior deltoids overlapped
by the radial limbs ; the posterior one much larger than
the rest, and appearing externally. Posterior spiracles
conflueht with the anus. Silurian (Niagara Group) ;
North America.

Metablastus E. and C. (Fig. 258, C). Like the preced-
ing, but all the deltoids equal, and the two posterior
spiracles not confluent with the anus. Spiracle slits ten
in number ; hydrospires four to each side of an am-
bulacrum. Devonian to Lower Carboniferous (Keokuk
Group) ; Europe and North America.

Tricoelocrinus M. and W. (Saccoblastus Hambach). Calyx

ir an+sp

Fig. 264.

Troostocrinus reinwarm pyramidal, broadest below and narrowing upwards ; when

(Troost). Silurian

nessee.^, Calyx from anal ggen from abovc or below stroudv pentaeronal in outline,

side. B, Snmmit aspect. . .. i.ii r ^

(Z, Deltoid ; ir, Deltoid of owing to the projectmg and carinated character oi the

anal side (after E. and C). j-i t\ ii. -j n i,i

radials. Deltoids small ; ambulacra
long, and extremely narrow. Spiracles ten, distinct ; anus
large. Hydrospires small, enclosed within the substance of
the forked plates. Lower Carboniferous (Warsaw Group) ;
North America.

Family 4. Eleutherocrinidae Bather.

Elongate, stemless, asymmetrical, with four narrow ambulacra ;
fifth ambulacrum shortened and widened. Hydrospires not con-
centrated. Devonian.

Eleutherocrinus Shumard and Yandell (Fig. 265).
Devonian (Hamilton Group) ; Indiana, Kentucky, New York and Canada

Fk;. 'Mb.
Eleutherocrinus casse-
dnyi (Shum. and Yand.).
Lower Devonian ; Ky.
Ventral surface, -/i
(after E. and C).

Family 5. Nucleocrinidae Bather.

Calyx usually globular or ovoidal, with flattened or concave base, and linear
ambulacra extending the whole length of the calyx. Spiracles distinctly double, and

CLASS II

BLASTOIDEA

171

chiefly formed hy the apposition of notches in the lancet-plate and deltoids. Devonian
and Carboniferous.

Nucleocrinus Conrad {Elaeacrinus Koeiner ; Olivanites Troost) (Fig. 266).
Basais small, inconspicuous, sometimes hidden within the columnar cavity.
Radiais small, with very short limbs. Deltoids
greatly enlarged and elongated, forming over
two-thirds of the entire calyx ; the posterior one
wider than the others, and divided by a large
anal-plate. Lancet-plate exceedingly long and
narrow, partly exposed. Side-plates numerous ;
hydrospires two on each side of the ambulacra.
Summit covered by comparatively large orals,
asymmetrically arranged and forming a flattened
disk which completely closes the peristome.
Devonian (Onondaga and Hamilton Groups) ;
Indiana, Michigan, New York.

Schizoblastus E. and C. (CribroUastus Ham-
bach). Calyx resembling that of Orhitremites in
form. Basais almost always confined to the
lower face of the calyx ; deltoids of variable

Size, but always Visible in a side-view. Hydro- Devonian ; Columbus, O.(afterRoemer).
. ' / ^ y ^ A, Side-view of calyx. B, Base. C,

Spn*es one to four to each ambulacrum. bpiracles ventral surface. D, Same enlarged.

small, slit-like, placed between the lancet-plates

and deltoid ridges ; the posterior pair sometimes confluent with the anus.
Lower Carboniferous ; Ireland and North America (Kinderhook to Keokuk
Groups); Permian, Timor.

Fio. 266.
Nucleocrinus verneuili (Troost). Lower

Family 6. Orbitremitidae Bather.

Calyx globular or owidal, with flattened or concave base, and long linear
ambulacra. Spiracles five, piercing the deltoids, or ten, grooving their lateral edges.
Lower Carboniferous.

Orhitremites Austin (Granatocrinus Hall ex Troost MS. ; Cidaroblastus and
Globoblastus Hambach) (Figs. 263 J, 258 A). Calyx ovate to globose. Lower
face from slightly concave to deeply funnel-shaped ; interradial areas more or
less depressed. Basais small, generally concealed in the central columnar
cavity. Radiais very variable in size, often long, and invariably turned in
below to assist in forming the base. Deltoids also variable ; usually unequally
rhombic, but sometimes triangulär ; the anal deltoid f requently difFering from
the others. Ambulacra nearly parallel-sided, always impressed within the
sinuses at their proximal ends. Lancet-plates narrow, not Alling the sinuses,
and more or less exposed throughout two-thirds of the ambulacra. Side-plates
transversely elongated ; outer side-plates generally well developed. Hydro-
spires pendent, usually but two or three folds on each side of an ambulacrum ;
the inner one forming a well-defined hydrospire-plate. Spiracles five, piercing
the apices of the deltoids. Posterior spiracle larger, including the anus.
Summit closed by minute pieces which rarely exhibit any definite arrange-
ment. Lower Carboniferous; England and North America (Burlington
Group), (?) Australia.

172 ECHINODERMATA— PELMATOZOA phylum iv

Cryptohlastus E. and C. Calyx sub-globose, with a flatteried or slightly
hollowed base. Basais and deltoids small. Lancet-plate separated from the
radials by a hydrospire-plate, which does not extend above the radio-deltoid
suture ; but above this line the lancet-plate meets the deltoids without leaving
any hydrospire-pores. Spiracles round, distinctly double at four of the sides,
but those of the posterior side confluent with each other and with the anus.
Summit covered by numerous, irregularly arranged small pieces. Lower
Carboniferous (Burlington Group) ; North America.

HeteroUastus E. and C. Eesembling the preceding in form and proportion
of its component parts. The proximal ends of the deltoids produced in short
spine-like processes, at the base of which minute lateral openings, one to each
deltoid, are visible. These openings lead into gutter-like Channels excavated
in the substance of the plates for the reception of the proximal ends of the
two hydroBpire-canals. Eadial sinuses wide, their edges sloping gently
downwards to the slightly petaloid ambulacra. Lower Carboniferous ;
England and (?) North America.

Mesoblastus E. and C. Calyx ovoid to globose, with concave to protuberant
base. Eadials long, deltoids small, short, unequally rhombic. Ambulacra
very narrow, extending to the base. Spiracles, as a rule, distinctly double,
but sometimes incompletely divided. Lancet-plate entirely, or for the most
part, concealed by side-plates. Lower Carboniferous ; Belgium, England,
(?) North America and Australia.

Acentrotremites E. and C. Calyx elliptical, with broad pentagonal lower
face. Radials large, taking up three-fourths of the height of the calyx.
Deltoids unequally rhombic, each notched by two spiracles at the ends of the
radio-deltoid suture. Anal opening situated close to the summit in the
posterior deltoid. Ambulacral edges of the deltoids without hydrospire-pores.
Lower Carboniferous ; England. '

CarpenteroUastus and Lophoblastus Rowley. Lower Carboniferous (Kinder-
hook and Burlington Croups) ; North America.

(?) NymphaeoUastus von Beetz. Lower Carboniferous ; Russia.

Family 7. Pentephyllidae Bather.

Calyx stemless and sub-pentagonal ; radials asymmetrical. Ambulacra linear,
extending dotun to the base ; one shorter than the rest. Carboniferous.

Pentephyllum Haughton. Carboniferous ; Ireland.

Family 8. Zygocrinidae Bather.

Stemless. Calyx depressed, asymmetrical, quadrilobate. Four ambulacra
between the lobes, accompanied by a single hydrospire on either side ; fifth ambulacrum
shortened and widened.

Zygocrinus Bronn (Astrocrinus Austin, non Conrad nee Münster). Lower
Carboniferous ; Great Britain.

[The text for the group Blastoidea in the present work has been revised by Mr. Frank
Springer, of Las Vegas, New Mexico, and Washington, D.C.— Epttor,]

CLAss III CRINOIDEA 173

Olass 3. ORINOIDEA Miller. Sea-lilies. '
(Brachiata Bronn ; Adinoidea F. Roemer.)

Usaally long-stalked, more rarely non-pedunculate and sessile, frequently free-
swimming Pelmatozoa, with calyx composed of regularly arranged plates, and provided
with well-developed movahle arms.

The Crinoid organism consists of three principal elements — calyx, arms
and stalk. The calyx and arms together are sometimes spoken of as the
crown, as contrasted with the column (also called stem or stalk).

1. The Calyx. — The calyx has usually the form of a cup-shaped, bowl-
shaped, or globular capsule, within which the more important organs are
enclosed. Its lower (dorsal or abactinal) surface commonly rests upon a
column (Fig. 267) ; but in some forms it is attached directly by the base,
and in rare instances it is free. The superior (ventral or actinal) surface is
either membranous or plated ; it carries the mouth and ambulacral grooves,
and hence is homologous with the under side of a star-fish or sea-urchin. As
a rule, only the inferior and lateral portions (dorsal cup) of the calyx are
visible, owing to the concealment of the summit by the arms. The cup
is constituted of two or more circlets of plates, which are uniformly oriented
with reference to the ambulacral organs.

a. By the hase is understood the one or two circlets of plates intervening
between the topmost Joint of the column and the first cycle of radially situated

1 Literatnre : Miller, J. <S., A Natural History of the Crinoidea or lily-shaped Animals, 1821. —
Müller, J., Ueber den Bau des Pentacrinus caput-medusae. Abhandl. Akad. Wiss. Berlin, 1841.
— de Koninck, L. G., et le Hon. H., Recherches sur les crinoides du terrain carbonifere de la Bel-
gique. Brüssels, 1854. (Very extensive bibliography.) — Beyrich, E., Die Crinoideen des Muschel-
kalks. Abhandl. Akad. Wiss. Berlin, 1857. — Schnitze, L., Monographie der Echinodermen des
Eifler Kalks. Denkschrift Akad. Wiss., 1867, vol. xxvi. — Shumard, B. F., Catalogue of Palaeozoic
Echinodermata of North America. Trans. St. Louis Acad. Sei., 1868, vol. ii. (Very complete
bibliography.) — Carpenter, W. B., On the Structure, Physiology, and Development of Antedon
rosaceus. Philos. Trans., 1876, vol. elvi. — Wachsmuth, C, and Springer, F., Revision of the Palaeo-
erinoidea. I.-III. Proc. Acad. Nat. Sei. Philad., 1879-86. — Idem, Discovery of the Ventral Struc-
ture of Taxocrinus and Haplocrinns, ibid., 1888. — Idem, The Perisomic Plates of Crinoids, ibid., 1890.
— Idem, The Crinoidea Camerata of North America. Mem, Mus. Comp. Zool.,1897, vols. xx., xxi.
— Loriol, P. de, Paleontologie Fran9aise. Crinoides Jurassiques, I.-II., 1882-89. — Neumayr, M.,
Die Stämme des Tierreichs, 1889. — Agassiz, A., Calamocrinus Diomedae. Memoirs Museum Comp.
Zool. 1892, vol. xvii. — Bather, F. A., British Fossil Crinoids. Ann. and Mag. Nat. Hist., 1890-92,
ser, 6, vols. v.-ix. — Idem, The Crinoidea of Gotland. K. Svenska Vetensk. Akad. Handlingar,
1893, vol. XXV. — Idem, A Treatise on Zoology (Lankester) pt. iii., Echinoderma, 1900. — Jaekel,
0., Crinoiden Deutschlands. Pal. Abhandl. Jena, neue Folge, 1895, vol. iii. — Springer, F., Uinta-
crinus, its structure and relations. Mem. Mus. Comp. Zool., 1901, vol. xxv., No. 1. — Jdem, Cleio-
crinus. Mem. Mus. Comp. Zool., 1905, vol. xxv., No. 2. — Idem, Discovery of the disk of
Ouychocrinus. Journ. Geol., 1906, vol. xiv. — Idem, A Trenton Echinoderm Fauna. Geol. Surv.
Canada, 1911, Memoir No. 15, P. — Idem, New American Fossil Crinoids. Mem. Mus. Comp. Zool.,
1911, vol. xxv., No. 3. — Ide7)i, The Crinoidea Flexibilia. (Monograph in preparation. ) — Chad-
wick, II. C, Antedon. Liverpool Marine Biol. Comm., 1907, Mem. 15. — Clark, A. H., Variouf« im-
portant papers on recent and fossil Crinoids in Proc. U.S. Nat. Mus., 1908-11, vols. xxxiv.-xl. —
Idem, On a collection of Crinoids from the Zoological Museum of Copenhagen. Vidensk. Medd.
fra den Naturhist. Forening i, K0benhavn, 1909. — The probable origin of the Crinoid al nervous
System. Amer. Nat. 1910, vol. xliv. — Remarks on the nervous System and symmetry of the
Crinoids. Journ. Wash. Acad. Sei., 1911, vol. i. — The Recent Crinoids of Australia. Memoir 4,
Australian Museum, Sydney, N.S.W., 1911.— The Crinoids of the Indian Ocean. Memoir of the
Indian Museum, Calcutta. (In press.) — The Existing Crinoids. Special Bulletin, U.S. National
Museum. (In press.) — Wood, E., A critical suminary of Troost's unpublished manuscript on the
Crinoids of Tennessee. Bull. U.S. Nat. Mus., 1909, No. 64. — Kirk, E., Structure and relationships
of certain Eleutherozoic Pelmatozoa. Proc. U.S. Nat. Mus., 1911, vol. xli.

174

ECHINODEKMATA— PELMATOZOA

PHYLUM IV

plates at the base of the ambulacra or arms. When the base is monocyclic
(Fig. 268) the position of the proximal ring of plates is interradial ; but when

Fig. 267.

Euspirocrinus spir-
alis Ang, Stalked
Crinoid with dicyclic
base and anal inter-
radius. a, Anals ; b,
Basais; ib, Infrabasals;
r, Radiais. (Right and
left sides reversed,
after Angelin.)

Fig. 268.

Cactocrinus 'probosckiialis (Hall). Prqjec-
tion of calyx sliowing the tliree basals (5),
5x3 simple radials (r), four iiaired interrays
(ir), and a tifth unpaired anal interray (a).

Fig. 26'.).

Pachylocrinus multiplex
(Traut). Calyx with dicy-
clic base, radials, costals,
and distichals.

dicyclic it is radial, and the upper ring corresponds with the basals of mono-
cyclic forms (Fig. 269).

In the nomenclature of P. Herbert Carpenter, the upper series of plates in
the dicyclic base are properly termed basals, and the lower series infrabasals
iunderbasals). The basals as thus defined are equivalent to the "parabasals"

in the older nomenclature of Johannes Müller,
and to the " subradials " of de Koninck and
other authors.

Both basals and infrabasals are primarily five
in number ; but owing to the supposed morpho-
logical (rarely if ever actual physical) fusion of
two or more of the plates, the number of basals
in the monocyclic forms may be reduced to four,
three, two, or even to a single undivided plate ;
and that of infrabasals in the dicyclic to three.
During the ontogenetic developmentof the Recent
Antedon, a more or less complete resorption of the
basals has been observed, which ultimately results
in their passage from the dorsal to the ventral
side of the so-called chambered organ, where they
are again rebuilt, becoming a curious plate-like structure known as the
rosette; and the same probably also was true for certain Mesozoic genera
(Eugeniacrinus, Phyllocrinus). In many of the non-pedunculate Crinoids
{Uintacrinus, Marsupites, Fig. 270) an additional plate known as the centrale
rests against the infrabasals, and probably represents an undeveloped stalk.
The bg,sals are united with one another and with the overlying radials by

Fig. 270.

Marsupites testudinaris (Schloth.).
Diagram of calyx. cd, Centrale ; ib,
Infrabasals ; b, Basals ; r, Radials.

3LASS III CRINOIDEA 175

ery numerous short fibres of connective tissue, which may become more or
ess calcified ; this forms an immovable Union of the type known as a close
uture, in which the plates are immovably held together by fibrous con-

ective tissue. Though usually smooth, the Joint faces are sometimes
triated, which striations are visible externally as incised lines.

b. Succeeding the base is a cycle of five (rarely four, six, or ten) plates,
which, on account of their position with reference to the rays, are called
radials. The radials form the sides (more rarely the floor) of the calyx
in nearly all Mesozoic and Recent Crinoids, and give origin directly to
the arms, which may become free immediately above the radials, or may be
incorporated for some distance in the calyx, either by means of supplementary
plates, or by lateral union among themselves.

The Upper boundary of the calyx is differently demarcated by dilFerent
authors. Many assign all the plates above the first cycle of plates in each
ray to the arms, even when they are immovably united with one another at
the sides ; while, according to Schultze and others, the arms begin invariably
at the point where they first became movable, i.e. above the first articular
facet. The latter course is open to serious objections, inasmuch as strictly
homologous parts receive different appellations in different groups.

Carpenter, Wachsmuth and Springer, and Bather restrict the term " radial "
to the lowermost circlet of radially situated plates, and consider the succeed-
ing cycles as far as and including the first axiliary plate as hrachials (dis-
tinguished as first, second, and third costals, distichals, and palmars ; or as
first, second and third primibrachs (IBr), secundibrachs (IIBr), and terti-
brachs (IIIBr) respectively), in all cases, whether the plates are free or
fixed.

In most Paleozoic Crinoids one or more interradial plates are intercalated
between two of the rays, and in line with the anal aperture ; these are called
the anal plates or anals. If a plane be passed through the latter and through
the radial situated directly opposite, the calyx will be divided into two
symmetrical halves : the parts lying to the right or left when viewed from the
posterior or anal side are so designated ; while the anterior side is that oppo-
site the anal interray. Interradial plates, however, are not confined to the
anal interray, but are frequently developed also between the other rays, when
the calyx is correspondingly expanded. If several cycles of radials and
brachials are present, an equal number of interradials may be developed, and
are distinguished in like manner as interradials and distichal interradials of
various Orders. The anal interray is frequently characterised by the peculiar
number, size and position of the anal plates.

c. The superior side of the calyx is known as the tegmen calycis. The
covering may be in the form of a coriaceous skin, in which large numbers of
thin calcareous ossicles are embedded (Figs. 271, 272), or of a plated disk
rising from the base of the arms. It frequently exhibits a more or less
central, externally visible mouth-opening, and a usually eccentric interradial
anal aperture. The mouth opens into an Oesophagus and thence into the ex-
panded visceral mass, which fills the greater portion of the inner cavity. The
intestinal canal is directed downwards at first, and after making usually one
complete circle, more rarely after numerous windings, discharges into the
anal opening. In certain fossil Crinoids (Actinocrinidae) the digestive appara-
tus is represented by an extremely thin-walled, finely perforated, convoluted

176

ECHINODERMATA—PELMATOZOA

PHYLUM IV

calcified body, wliich occupied the vertical axis of the body cavity, and was
contracted into a narrow tube toward the base (Fig. 280).

In all of the Recent Crinoids (excepting in certain species belonging to the
family Comasteridae where they may be quite absent from the arms arising from
one, two, or even three of the posterior rays) each arm, and each pinnule
which it bears, carries on its ventral surface an open ambulacral furrow lined
with ciliated epithelium. At the base of the arms these ambulacral furrows
unite and form five large furrows, which, traversing the tegmen, converge at
the central mouth, or, as in the Comasteridae, lead to a horse-shoe shaped
furrow just within the border of the tegmen in the centre of which is the
mouth. Just below the floor of these furrows runs a nerve band (absent from
ungrooved arms), and under this the genital rachis (especially developed in
ungrooved arms), and the canals of the water and blood vascular Systems ;
below these, deeply buried within the substance of the calcareous plates, lies
the large nerve cord of the dorsal nervous System. All but the last of these,
which leads to a central nervous mass in the dorsal apex of the calyx, run to

Isocrinus asteria (Linii.). Ventral
disk, protected by very thin peri-
somic plates, witli central mouth (o),
exposed anibulacra, and eccentric
anus (A).

Hyocrinus hethelianus (Wyv. Thoin.). Re-
cent. Ventral disk, enlarged. o, Orals ; p,
Mouth (peristome) ; s, Covering plates ; c,
Dorsal canals of the anus ; a?u, Ambulacral
furrows of the arms ; a», Anus (after Wyville
Thomson).

ring-like structures surrounding the Oesophagus. The circumoesophageal ring
canal of the water vascular System is in communication with the body cavity,
which in turn communicates with the exterior by means of very numerous
(five only in Ehizocrinus) interradial perforations. The margins of the
ambulacral grooves are bordered with a series of small lappets, and at the
base of each of these is a group of three tentacles ; these tentacles, which are
absent from ungrooved arms, are connected with the canal of the water
vascular system ; they also secrete a more or less poisonous fluid which serves
to paralyze the small organisms which serve as food.

In all Recent Crinoids five (occasionally four) open ambulacral furrows
lined with epithelium conduct from the mouth to the tips of the arms,
remaining either simple or subdividing as often as there are arms. Under-
neath the floor of the grooves runs an ambulacral vessel filled with water ;
and accompanying this are the blood and vascular canals and a nervous cord.
Distensible tentacles pass out from alternate sides of the ambulacra, and the
latter unite to form a circumoral ring canal From the ring canal five short
open tubes (stone or water canals) extend downwards into the body cavity and
supply the ambulacral system with water.

CLASS III

CRINOIDEA

177

In certain of the Recent stulked genera, as in Hyocrinus (Fig. 272), in
the young of all the Recent species, and in a large number of fossil Crinoids,
a triangulär oral plate is situated at each of the five angles of the mouth-open-
ing. The apices of the orals are directed towards one another, and between
them run the ambulacra. Oral plates are extremely variable in size ; and
although well-developed in the larvae of the Comatulids and in the young of
many of the stalked species, they become wholly resorbed before maturity.
In a number of Paleozoic Crinoids (Fig. 275) the summit is entirely or in
large part composed of five oral plates which may be either laterally in
contact or separated by furrows. More frequently, however, the orals occupy
only the angles of the mouth-opening, the remaining area between the
ambulacral furrows being covered with more or less regularly arranged
interamhulacral plates (Fig. 272). In most of the Paleozoic Camerata, and in all
the Recent species, the anus is placed at the upper end of a tube known as the

Fio. 273.

Lecytliocrinus eifeliatius
Müller. Crinoid with elon-
gated anal tube (alter
Schnitze).

Fig. 274.

Dorycrlnus quinquelohus (Hall).
Specimen showing plates of the teg-
nien and eccentric anus.

Fio. 275.

Coccocrinus rosaceus
Roem. Devonian ;
Bifel. Calyx with ven-
tral pavement. X 2/,
(after Schnitze).

anal tube or proboscis. In the Fistulata, however, the anal opening is situated
along the anterior side of the ventral sac, or between the sac and' the mouth.

Of the interamhulacral plates a greater or smaller number (in Calamocrinus
all in the vicinity of the mouth) are perforated by pores for the admission
of water into the body cavity. Pores evidently performing a respiratory
function occur in some of the Fistulata ; but these, instead of piercing the
body of the plates, enter only their outer angles. Other Fistulata have a
madreporite.

The ambulacra are frequently lined along their sides by more or less
rounded covering plates which are capable of being folded down over them
so as to serve as a protection ; these covering plates are, at least in the
Recent forms, perisomic plates developed in the marginal ambulacral lappets ;
they may occur alone, as in the genera Ehizocrinus, N'emasier, etc., but they are
usually separated from the pinnulars or brachials by a second series of squarish
or oblong plates known as the side plates. Both series of plates occur every-
where along the ambulacral grooves, but they become irregulär and ill-defined
011 the disk. In the Paleozoic Taxocrinus (Fig. 276), the covering pieces are
VOL. I N

178

ECHINODERMATA— PELMATOZOA

PHYLUM IV

arranged in alternate rows, with side-pieces adjoining them. The latter plates
occur also in most of the Inadunata and Flexibilia, but are rarely represented
in the Camerata. The mouth may be exposed or closed ; either being
surrounded by five oral plates {Taxocrinus, Fig. 276), or the posterior oral may
be pushed in between the four others, so as to conceal the mouth ; the latter
is then said to be suUegminal (Fig. 277).

A very remarkable modification of the ventral disk occurs in the Paleozoic
Camerata. Here the usually very numerous plates attain considerable thickness,
and fit into one another like the stones of an arch to form an extremely rigid,
more or less convex vault, which is sometimes surmounted by an equally rigid
plated proboscis. At the apex of the dome five large-sized plates are often
distinguishable, of which that lying in the anal interradius commonly difFers
from the rest in form and size, and appears to be wedged in amongst the others.
These five plates are identified by Wachsmuth and Springer as orals. The
remainder of the tegminal plates are distinguished according to their position as
ambulacrals and interambulacrals ; in most of the Batocrinidae the ambulacrals

Fig. 276.

Taxocrinus intermed-
ius W. and Sp. Ventral
disk (after Wachsmuth
and Springer).

Fig. 277.

Platycrinus Jialli Shum. Projection
of ventral disk. a, Ambulacrals ; ia, In-
terambulacral areas ; ia', Anal inter-
radius ; e, Covering pieces of the ambu-
lacrals : i, Interradials ; jj, Interior
and lateral orals ; o, Posterior (anally
situated) oral ; x, Plates of the anal
interambulacral area (after W. and Sp.).

Fig. 278.

Hexacrinus elongatus Goldf. Calyx
with tegmen. ■ a, Profile ; h, Viewed
from above.

are not arranged in alternate rows (Fig. 279), but frequently consist of
large single ' plates ' of one or more Orders, which are separated from one
another by the continuous interposition of supplementary pieces. In other
groups, notably the Platycrinidae, the ambulacrals are generally arranged in
two rows of rather large plates, which, however, lose their original character
to some extent. The interambulacrals usually meet with the interbrachials.
The tegmen of the Camerata, as a rule, is composed of large convex or nodose
plates, for the Identification of which considerable experience is required.

Most of the Paleozoic Crinoids have but a single opening in the tegmen,
which is interradial in position, or sometimes central, and represents the anus.
With the exception of the Flexibilia the mouth is subtegminal, and the food
grooves are rigidly closed. In many cases the covering pieces are pushed
inward, and the ambulacra follow the inner floor of the tegmen, forming a
skeleton of ramifying tubes ; these are conducted along open galleries from
the mouth to the arm-openings (Fig. 280, A).

2. The Arms (Brachia). — The arms of the Crinoid body form the immediate
Prolongation of the radials. The plates of the arms are termed hrachials, and

CLASS III

CRINOIDEA

179

are arranged either in single or double alternating rows ; and hence are spoken
of as uniserial (Fig. 281, A), or as biserial (Fig. 281, B). The plates of the
uniserial arms may be either rectangular or cuiieiform, the major ends being
directed alternately to the right and left. In biserial arms the smaller ends
of the plates meet midway, so as to form a zigzag suture. The arms invariably

B

Fig. 279.

Agaricocrinus americanus
Roein. Ventral disk. r, Uni-
serial ambulacrals ; i, Inter-
ambulacrals ; o, Anally situ-
ated oral ; p, Anterior and
lateral orals ; x, Posterior in-
terambulacrals (after Wach-
smuth and Springer).

Cactocrinus probosddialis (Hall). A, Plates of tegmen partially
removed in order to show the covered ambulacral passages (a)
leading from the arms to the mouth. B, Piated upper surface
of ambulacral galleries. C, Natural cast of ventral disk with
impressions of calyx ambulacra (a) leading to the mouth (o);
an, Anus.

begin uniserially, the biserial structure being gradually introduced in an upward
direction. They either remain simple, or branch in various ways ; the plates
upon which a bifurcation takes place are called axillaries.

In the Camerata, the more highly organised Inadunata, and in all Eecent

Fig. 281.
A, Carpocrinus comtus Ang., showing uni-
serial arms. B, Codlicrinus costatus Hising.,
with biserial arms (after Angeliii).

Fio. 282.
Piated ambulacral furrows of the
arms. a, b, Cyathoerinns ramo.fiui
Ang., showing covering pioces ;
c, Gissocrinus arthriticns Hising.,
with covering pieces. All figures
enlarged.

Crinoids, the arms are furnished with pinmdes, which are given off alternately
from opposite sides, usually one to each arm-plate, more rarely on alternate,
or on every third arm-plate ; sometimes they are partially or entirely absent
from the lower portion of the arms. The pinnulcs are jointed appendages,
which at least basally repeat the general structure of the arms, and in living

180 ECHINODERMATA— PELMATOZOA phylum iv

Crinoids lodge the functional portion of the genital organs. When two or
more arm-joints meet transversely by a rigid suture, and only the uj)per one is
pinnule-bearing, those joiiits form a syzygy, whether their apposed faces are
striated, dotted or smooth. The lower Joint bearing no pinnule is called the
hypozygal Joint, the upper one the epizygal ; and the two together constitute
physiologically but a single segment, as is shown by the unaltered alterna-
tion of the pinnules.

The ciliated ambulacral furrows of the arms enter by the arm-openings
into the tegmen, and all converge to the mouth. Food-particles, consisting
chiefiy of diatoms, infusorians and microscopic crustaceans, are propelled along
the furrows and into the body by the action of the cilia.

In all Recent and in numerous fossil Crinoids the brachials and pinnulars
are perforated by a single, or in some cases by a duplicate, canal {central canal)
containing the dorsal nerve cords, which give off four delicate branches
within each segment. The dorsal canal extends also into the radials and
basals, perforating the plates when they are thick, and running in a shallow
groove on the inside when thin. So far as has been observed, the axial
canals begin uniformly in the basals, where they divide dichotomously ; but
in the radials the branches generally reunite to form the so-called ring canal
(Fig. 329).

3. The Column. — The stem or column attains in some forms (Pentacrinus) a
length of a number of metres ; but in others it is much abbreviated, or
even atrophied, so that the calyx is either directly adherent by the base
(Gyathidium, Holopus), or is destitute of all means of attachment {Agassizocrinus,
Uintacrinus, Marsupites, the Comatulids). The stem is composed of usually
short Segments, having either circular^ elliptical or angular (especially penta-
gonal) cross-sections, and being sometimes of uniform and sometimes of variable
proportions. Lateral appendages, called cirri, are present in numerous forms,
being given off either singly or in whorls at regulär intervals along the
periphery. The larger and all cirrus-bearing segments are called nodals, and
those interposed between them the internodals. The distal end of the stalk
may taper gradually to an apex, in which vicinity fine radicular cirri are
commonly developed, or it may be thickened at the extremity so as to form a
bulbous or branching root, or a heavy, solid, terminal stem plate, or dorso-
central. Growth is accomplished by the insertion of new joints at the
proximal end of the stem, either just beneath the calyx, or both here and
between the earlier formed joints, the earlier segments becoming at the same
time gradually enlarged. The last-formed joints are commonly of smaller
size than those situated more remotely from the calyx.

Like the brachials and pinnulars, all the joints of the stem and cirri are
pierced by a (usually central) longitudinal canal which is circular, oval or
pentagonal in cross - section, and communicates with the peculiar dorsal
chambered organ which in the Comatulids is situated within the centrodorsal,
and in the stalked forms within the calyx just above the summit of the
stem. The outer walls of the chambered organ are composed of nervous
tissue, and form the central organ of the dorsal nervous System which
innervates all the dorsal structures ; within the chambered organ is divided
by partitions into five sections, and is continued ventrally as a thick tube
of uncertain function, known as the central plexus, to near the inner surface
of the disk, where it ends blindly.

CLASS in CRINOIDEA 181

All of the calcareous elements of which the dorsal skeletal System is com-
posed are developed within a uniform organic base ; with the growtli of the
plates this within them becomes a diftuse network, and between them forms
a mass of strong connecting fibrils which bind the plates together.

In the so-called sutures between the calyx plates, in the intercolumnar
articulations in many of the older types (Encrinus, etc.), in the syzygies between
the brachials in many forms, and just below the cirrus-bearing joints in the
stems of the Pentacrinites, these fibrils are all of uniform length and uniformly
distributed over the Joint face ; but. usually there is a diflferentiation of the
fibrils by which they become more or less segregated into radial groups, as in
the stems of Pentacrinites ; or they become elongated and differentiated into two
comparatively dense masses separated by a strong fulcral ridge, and assume a
more or less contractile function as in the stems of such genera as Bhizocrinus
and Platycrinus, in the cirri of the Pentacrinites and Comatulids, and in the
pinnules beyond the second Joint in many forms. Between the brachials they
are usually differentiated into two distinct types, one of which, occupying the
entire dorsal half of the Joint face (the dorsal ligament) is comparable to one
of the two masses in the type just described ; while the other, occupying two
more or less triangulär areas, one on either side of the central canal and just
ventral to the transverse ridge by which they are separated from the preced-
ing (the interarticular ligaments), is much more dense, and serves to bind the
brachials tightly together.

In addition to these ligamentous connections there are, between the
brachials, two muscular bundles situated on the ventral border of the Joint
face, distal (ventral) to the interarticular ligament masses. "Whereas the
ligament bundles are developed directly from the original uniform body
investment in which the calcareous elements are formed, the muscular bundles
have an entirely separate origin.

In certain of the older forms the proximal segments of the column
occasionally exhibit simple vertical clefts, which indicate an original quin-
quipartite composition. These divisions always occur alternately with those
of the basals in monocyclic, and with those of the infrabasals in dicyclic
forms. The entire crinoid stem is probably the homologue of a single apical
calyx plate, which has been reduplicated by a curious process of serial repeti-
tion common among the Echinoderms.

Ontogeny. — Although we are as yet acquainted with the life-history of but
tbree species, all belonging to the genus Antedon, and although the life-
history of but two of these (A. mediterranea and A. adriatica) is well under-
stood, the phenomena of their development are of such significance as
to shed most valuable light upon many conditions observed in fossil
Crinoids.

The eggs, extruded from the ovaries and hanging in little groups from the
genital pinnules, are fertilized externally, and the early metamorphosis of the
larva takes place within the egg membrane. At the time of the rupture of
the egg membrane and its consequent escape the embryo (a gastrula) is elongate-
oval in form, bilaterally symmetrical, bearing an anterior tuft of cilia and
encircled by five ciliated bands, resembling somewhat the larvae of certain
annelids. Internally there are to be seen the rudiments of five oral plates,
five basals, three (A. medUerranea) or five {A. adriatica) infrabasals, and about
eleven columnars ; the orals, basals, and infrabasals are arranged in horseshoe-

182

ECHINODERMATA— PELMATOZOA

PHYLUM IV

shaped bands, and the columnars are also horseshoe-shaped, not having as yet
formed complete rings.

After a free-swimming existence of a few hours the embryo attaches itself
by means of the so-called adhesive pit, a slight depression on the antero- ventral
face, the cilia disappear, and profound changes take place which result in a
rearrangement of the internal organs.

The five orals now form a pyramid over the superior (ventral) portion of
the animal, while the five basals form a similar, but inverted, pyramid, in the
wall of the proximal (dorsal) portion of the calyx ; between the apex of the
latter and the top of the column are the three or five infrabasals. The column
consists of about eleven cylindrical joints, each composed of the original central
annulus from which numerous longitudinal parallel calcareous rods are
developed, and is terminated distally, and attached, by a lobate terminal stem
plate. The larva is now said to have reached the " Cystid stage."

In the five diamond-shaped spaces which occur between the divisions of
the orals and basals the radials appear, and, increasing rapidly in size, intrude
upon the orals ; at the same time a sixth plate (the anal)
makes its appearance in the zone of the radials, but it gradu-
ally moves upward with the orals into the ventral disk. A
row of elongate cylindrical segments, bifurcating on the
second, is given ofF from each radial, and grows very rapidly
by the addition of ne\7 plates at its distal end. The column
ceases adding new segments, and the last one to be formed,
just beneath the calyx, increases in size and fuses with the
infrabasals to form the rudiment of the centrodorsal. The
larva is now said to have reached the " Pentacrinoid stage."
Simultaneously with the development of the arms and
column a resorption of the orals and the anal sets in, while
the basals begin to undergo a curious metamorphosis by
which they are transformed into a lobate ten-rayed plate
which is wholly internal, lying just above the chambered
organ. Finally the button-shaped centrodorsal, which is now
beset with numerous cirri, detaches itself from the remainder
of the stalk, and the animal becomes free.

The ontogeny of the Antedon (Fig. 283) reveals the fact
that the infrabasals, basals, orals and stem represent the
most primitive skeletal structures, while the radials and
brachials are formed at a subsequent period. Similar
evidence is afforded by numerous fossil Crinoids, in which
the basals and column are very strongly developed, while
the radials are mostly of inferior size, and the arms either
rudimentary or absent.^
Hahitat. — The existing Crinoids inhabit depths ranging from between tide
marks to 2900 fathoms, both extremes being occupied by unstalked forms

^ [Some of tlie Paleozoic Flexibilia are almost identical, in fact, with the pedunculate stages of
Antedon, Wachsmuth and Springer, from their observations on the orientation of the stem and its
caiial in fossil mouocyclic and dicyclic Crinoids, were led to infer the presence of infrabasals in the
nepionic (or larval) stages of many forms previonsly supposed to be witlioiit them. This predic-
tiou was abundantly contirmed by Mr. Bury's discovery of niinnte infrabasals in the larva of Antedon.
See especially //. Bury, Early Stages in the Development of Antedon rosaceus. Philos. Trans.,
1889, vol. clxxix.]

Larva of Antedon
roscbceus Linck. b, Ba-
sals ; r, Radials ;
0, Orals : cd, Centro-
dorsal (after Wyville
Thomson).

CLAss III CRINOIDEA 183

(Comatulids), the ränge for the stalked species being from 5 to 2325
fathoms. The great majority of the existing types are littoral and snblittoral,
oidy a few descending into'the abysses. A very large nnnib(3f of species,
many genera, and several families are confined to the East Indian region, while
all the species and genera occurring outside of that region have close relatives
within it. Most forms are highly gregarious, occurring in great numbers
together, these masses being often composed, in the East Indies, of twenty or
more different species, but a few appear to be more solitary in habit. As a
rule the Eecent forms are very local, and, though they may be found in certain
very restricted areas in large numbers, and may have a very wide geographical
ränge, it is comparatively seldom that one meets with them.

Fossil Crinoids also appear to have been gregarious in habit, and their
remains are frequently found commingled with those of reef-building corals
in Paleozoic strata. Owing to the extremely delicate Constitution of many of
the skeletal parts, and the looseness with which the plates and segments are
united, the Crinoid organism is by no means favourably adapted for preserva-
tion in the fossil state. Perfect crowns are of comparatively rare occurrence,
calices more frequent ; but, on the other hand, detached joints of the stem
and arms are often very abundant, and form beds of considerable thickness.
Orinoidal limestones of greater or lesser extent are met with in numerous
formations from the Ordovician to the Jura ; those of the Carboniferous and
Muschelkalk (Trochitenkalk) being especially characteristic.

Classification. — The first attempt to construct a Classification of the
Crinoids was that of J. S. Miller in. 1821. Four groups differing in the form
and mode of union of the calyx plates were distinguished by Miller as
follows : C. articulata, semiarticulata, inarticulata and coadunata. The Classi-
fication of Johannes Müller, in 1841, was based upon a number of difFerential
characters, such as the articular or close suture of the radials, the thick-
ness of the calyx plates, the mobility of the arms, and the plated or
cbriaceous character of the ventral disk. Two principal groups were
recognised : Articulata and Tesselata ; while a third (Costata) was constructed
for the reception of the unique genus Saccocoma. T. and T. Austin and
F. Roemer adopted the untenable divisions of Stalked and Unstalked
Crinoids.

The importance of Wachsmuth and Springer's investigations on the
structure of the calyx, especially of the tegmen, and on the orientation of
the stem and its canals in monocyclic and dicyclic forms, cannot be over-
estimated. Two groups were proposed in their Classification of 1879 :
Palaeocrinoidea and Stomatocrinoidea ( = Neocrinoidea, Carpenter) ; groups which
correspond in the main with the Tesselata and Articulata of Johannes Müller.
This Classification was subsequently abandoned, and a new one suggested for
it in 1888, afterwards more fully defined in their monograph on the North
American Crinoidea Camerata in 1897, in which three principal grand
divisions, or Orders, were recognised, which were believed to include sub-
stantially all Crinoids, fossil and recent, viz.: Camerata, Inadunata and
Articulata.

Jaekel in 1894 proposed two Orders, Cladocrinoidea and Pnitnmnmdea,
the former containing only the Camerata (W. and Sp.), and the Int t er ;ill the
rest. Bather in 1898 divided the Crinoids according to the composition of
the base into two subclasses, Monocyclica and Dicyclica, recognising for the

184 ECHINODERMATA— PELMATOZOA phylüm iv

most partj as subordinate to them, the Orders proposed by Wachsmuth and
Springer. The divisions established by Wachsmuth and Springer have been
adopted as the basis of the following systemätic arrangement, substituting,
however, for their Artioulata the preferable name Flexibilia, proposed by von
Zittel in 1895, and now adopted by Springer in his forthcoming monograph
of that group; also retaining the name Articulata in the sense of Miller and
Müller for a fourth division, including the Eecent and most of the Mesozoic
Crinoids.

Within the last few years, also, the terminology has been amended in
several important respects ; and conformably to the usage of the leading
English and American authorities, certain of these changes have been adopted
in the present edition. An explanatory note on the use of terms is therefore
given at this place, in order to facilitate reference, and to exhibit the corre-
spondence between the older terminology and the new.

The only abbreviations employed in the text are the following : —

75= Infrabasal.

^r = Brachial.

5 = B£fsal.

/5r= Primibrach or costal.

i?^ = Radianal.

/Zßr = Secundibrach or distichal.

X — First or special anal.

iBr = Interbrachial.

i2 = Radial.

Amh = Ambulacrals.

In addition to these the following are used in the figures, but are printed
in small letters : —

^=Calyx. . 6' = 0rals.

A = Arms. IE = Interradials.

St = 8tem.. Z)ts^ = Distichais.

Explanation of Terms.

Crotöti=:Crinoid minus the steni.

Calyx = Crinoid skeleton minus the stem and free arms.

Dorsal cup = All parts of the calyx below the origin of the free arms.

Tegmen — Thsit part of the calyx lying above the origin of the free arms, and embracing
the disk ambulacra, the mouth, and the anus. Inchides the terms ventral disk, vaiilt,
dorne, summit, etc.

Base~T\idit part of the dorsal cup lying next to the column. It may be composed of one
ring of plates (monocyclic), or of two rings (dicyclic), which are distinguished as basals and
infrahasals . The basals adjoin the radials and alternate with them, being interradial in
Position. The infrahasals, when present, form the proximal ring, and are radially disposed.

Badials = Th.e circlet formed by the first plate in each of the rays ; or, the radially
situated circlet of plates above the basals, and this ring only. In some of the earlier Crinoids
one or more of the radials appear as if transversely bisected, due to the presence of a
radianal or inferradials.

Brachials = k\\ plates beyond the radials in radial succession. They are called fixed
brachials so far as they take part in the calyx ; free brachials or arm-2')lates when they do
not. The brachials forming the first circlet above the radials, whether free or fixed, are
called primibrachs or costals ; those of the second order secundibrachs or distiehals ; those of
the third order tertibrachs or palmars; and so on for succeeding orders of brachials, to which
fofmerly the name post-palmars was applied.

Interradials = AM plates occupying the spaces between the rays proper, whether they
belong to the dorsal cup or the ventral disk. Those of the dorsal cup, which are inter-
posed between the brachials, are distinguished as interbracMah, and those of the tegmen,
which lie between the ambulacra, as inter ambulacrals.

Radianal = A plate disturbing the bilateral symmetry of the cup, located primitively
directly below the right posterior radial, and in later genera obliquely to the left of it.

^710.^5= Interradials of the posterior side, forming the base of the anal structures. The
special or first anal plate (npw usually designated x), when present, invariably rests upon
the truncated upper face of the posterior basal and between the radials. Higher anal plates

CLASS III CRINOIDEA 185

niay Le present, even wlien the s[»ecial anal is wanting ; tlioy are interposed betvveen tlie
iiiteibracliials, following tlie median line of the posterior area.

Urals ^The five large interradial plates which Surround the niouth or cover it. They are
Said to be symmetrical when of nearly tlie same size and form ; asymmetrical when the
posterior plate is pushed in betvveen, or is larger than, the other four.

Ambulacrals = The rows of small plates in the tegmen which are radially situated. They
consist of adamhulacrals or side-pieces, and the covering-])latcs (Saumplättchen). The former,
when present, constitute the outer, the latter the inner rows of plates. The covering plates
form a roof over the food-grooves ; they are generally represented by two alternating rows
of small plates, more or less regulär in their arrangement, which are movable upon the arms
and pinnules, but upon the disk only in those Crinoids in which the mouth is exposed.

The orientation is based upon the natural position of the Crinoid, with the arms upper-
most, and viewing the specimen from the anal side. The anal interradius will then be
posterior, the radius opposite to it anterior, while the right and left sides of it correspond
with right and left of the observer,

Primary Divisions of the Crinoidea.
I.

Crinoids in which tlie lower brachials take part niore or less in the dorsal cup.
All plates of the calyx united by close suture. Mouth and food-grooves closed. —
Order 1. Game rata.

II.

Crinoids in which the lower brachials are incorporated into the calyx either by
lateral union with each other, or by nieans of a skin studded with calcareous particles.
All plates from the radials up movable. Mouth and food-grooves exposed. Arms
non-pinnulate. The top stem Joint often fused with the infrabasals, and not always
the youngest Joint of the stem. — Order 2. Flexibilia of Zittel { = Ärticulata of W.
and Sp. non Miller and Müller).

III.

Crinoids in which the brachials are free above the radials. Plates of calyx united
by close suture. Mouth sub-tegminal. — Order 3. Inadunata.

IV.

Crinoids in which the mode of union of radials with the plates they l)ear is by
complete muscular articulation, and in which are combined the following additional
charäcters : open mouth and food grooves ; dorsal canals perforating radial and arm
plates ; uniserial arms only ; pinnules ; the general presence of a modified columnal,
or proximale ; the general absence of bilateral, and presence of pentamerous symmetry,
modified only by loss or addition of rays and not by anal structures. Brachials either
free, or more or less incorporated. — Order 4. Articülata.

The first three of these divisions are represented in the Ordovician. The Gamerata
were the most specialised, and the first to disappear, being confined to the Paleozoic,
and becoming extinct in the Lower Goal Measures. The Flexibilia were similarly
limited. The Articülata ränge from the Mesozoic to the present time. The Inadunate
type, representing the most generalised structure of the Crinoids, is in its most
essential feature, though variously modified, carried forward with the Ärticulata^ and
thus has an unbroken ränge from the earliest Ordovician to the present.

Order 1. CAMBRATA Wachsmuth and Springer.

(Sphaeroidocrinacea Neumayr.)

Crinoidea in which the lower brachials take part in the doisal cup. ylll plates of
tli£ calyx united hy close sutures, and immovahle. Mouth and food-grooves completely

186 ECHINODERMATA— PELMATOZOA phylüm- iv

covered ; the covering pieces of the latter frequently incorporated in the tegmen. Anal
opening eccentric or subcentral, frequentUj situated at the end of a prohoscis-like anal
tube. Arms uniserial or hiserial, and pinnulate. Ordovician to Carboniferous.

In some of the earlier (Ordovician) forms, as in the Reteocrinidae and
Batocrinidae, there is considerable flexibility in the tegmen, which is com-
posed of innumerable small plates ; but the mouth and food grooves in all
these are perfectly subtegminal, thus distingirishing them from the Flexibilia,
some of which, in respect to flexibility of the tegmen, they superficially
resemble.

Family 1 . Oleiocrinidae.

Dicydic. Brachials to height of several orders incorporated in calyx hy lateral
Union, those of different rays in contact except at the anal side. Calyx plates furnished
with pore-rhomhs crossing the sutures as in some Cystoidea. Arms pinnulate. Tegmen
of small undifferentiated plates. Mouth subtegminal. Ordovician,

Cleiocrinus Billings (emend.). Calyx large, pliant ; plates joined by loose
sutures, crossed by pore-rhombs. IBB five, invisible exteriorly. Basais and
radials not in typical succession, but alternating with each other in a
horizontal ring of ten plates surrounding the IBB and projecting downward
over the column like a collar. No iBr except at the anal side ; anals in
vertical series, resting on the truncate posterior basal, and extending high up
between the rays. Rays and their divisions up to the free arms contiguous
and interlocking ; brachials bifurcating several times in the calyx, giving off
fixed pinnules, which are incorporated by lateral union with adjacent brachials
and become free between the arm bases. Arms small, uniserial and
unbranched. Column obtusely pentagonal, or nearly round. Lowest
Ordovician (Chazy and Trenton) ; Canada and the United States.

This genus has the flexible calyx and loose sutures of the Flexibilia, but its innnulate
arms and subtegminal mouth place it in closer relation with early Camerata, such as
Reteocrinus. Its calycine pore-rhombs proclaim its not distant derivatiou from the Cystids.
In the remarkable disposition of the basal and radial plates, in horizontal alternation instead
of vertical succession, touching the infrabasals by their exterior surface instead of the distal
edge, this form diff"ers from all known Pelmatozoa. These intermediate and peculiar
features accord with its very early age.

Family 2. Reteocrinidae. Wachsmuth and Springer (emend.).

Dicydic. The lower plates of the rays more or less completely separated from
those of other rays, and from the primary interradials, by irregulär supplementary
pieces, without definite arrangement. Anal interradius divided by a vertical row
of conspicuous plates. Ordovician.

Reteocrinus Billings (em. W. and Sp.). Dicydic. IBB five, variable. PiR
and fixed brachials folded into a strong median ridge, which follows the
bifurcations and passes insensibly into the arms. A similar ridge of anal
plates divides the posterior interradius, extending to the anal opening.
Radials separated all around. Arms usually branching; uniserial, or with
interlocking cuneate ossicles. Interbrachial areas filled with innumerable
minute pieces forming an apparently pliant integument continuous with the
tegmen. Column round or pentagonal. Ordovician (Trenton to Cincinnatian) ;
North America.

CLASS III

CRINOIDEA

187

Family 3, Dimerocrinidae Bather. (Glyptocrinidae Zittel pars ; Glyptasteridae
Aiigelin ; Thysanocrinidae W. and Sp.)

Dimjclic. Lower hrachials and interhrachials forming an important pari of the
dorsal cup ; interbrachial s well defined. Radiais in contad except at the posterior
side, where theij are separated hy an anal plate. Ordovician to Devonian.

Ptychocrinus W. and Sp. IBB five. Arms uniserial, simple, or branching
once. Radial and brachial plates marked by well -defined median ridge.
First anal plate usually succeeded by three plates in second ränge ; iBr few.
Anus without a tube. Ordovician ; America.

Orthocrinus Jaekel. Arms stout and uniserial. Devonian ; Germany.

Bimerocrinus Phillips. (Thysanocrinus 3^nd Glyptaster Hall; Eucriiius Ang.)
(Fig. 284). IBB five. Arms biserial, simple or branching. First anal plate
followed by three in second
ränge ; iBr in several ranges.
Anus without a tube. Silurian
to Devonian ; North America,
England, Gotland.

Cyphocrinus S. A. Miller
(Hyptiocrinus W. and Sp.). Calyx
constructed as in Dimerocrinus,
but low and wide, with arms
pendent and tegmen plates spini-
ferous. Silurian; North America.

Gazacrinus S. A. Miller (Idio-
crinus W. and Sp.). iBr limited
to a Single large plate in each
interradius, that of posterior side
following an anal. Silurian ;
North America.

Lampterocrinus Roemer. Calyx
like that of Dimerocrinus, but Dinurocnnus.
asymmetrical from bulging at

anal side, and with anus at end of a tube. Anal plate followed by three
IBB, large. Rays produced into five tubulär extensions, bearing biserial,
pinnuliferous arms on each side. Silurian ; North America.

Siphonocrinus S. A. Miller. Similar to preceding, but IBB small, calyx
larger and more asymmetric, from subtegminal recurving of the rectum.
Silurian ; North America.

Fig. 284.
Analysis of calyx (after W. and Sp.).

Family 4. Rhodocrinidae Roemer.

Dicyclic. Lower hrachials and interhrachials forming an important part of the
dorsal cup. Radiais separated all around hy an interradial plate followed hy well-
defined, definitely arranged interhrachials. Infrahasals five. Anal area slightly,
and often not at all, different from those of other interrays. Ordovician to Lower
Carboniferous.

Rhaphanocrinus W. and Sp. (Coelocrinus Salter). Calyx obovate. Arms

188

ECHINODEEMATA— PELMATOZOA

PHYLÜM IV

Bliodocrinus.

Fig. 285.

Analysis of calyx (after W.
and Sp.).

uniserial ; from ten to twenty, and branching further. Otherwise similar to

Ärchaeocrinus. Ordovician ; North America and England.

Archaeocrinus W. and Sp. Calyx obovate to hemispherical ; base usually

concave or invaginate. IBB small. Brachials to at least second order in-

corporated in the calyx. Arms biserial, usually ten at their origin and

branching beyond. Anal interradius
slightly distinguished by an additional
plate in second ränge ; iBr numerous.
Anus without a tube. Ordovician; Canada
and Kentucky.

Diabolocrinus W. and Sp. Calyx de-
pressed globose. Anus at end of a tube.
First regulär interbrachial frequently
surrounded by supplementary plates.
Ordovician ; Tennessee.

Deocrinus and Hercocrinus Hudson.
Ordovician ; Canada.

Bhodocrinus J . S. Miller {Acanthocrinus
Koemer) (Fig. 285). Calyx globose,
usually small and delicate, with concave
base, and constricted at the tegmen.
Arms becoming free at the distichals, and
branching ; biserial, either directly from
the calyx up, or only from the last bi-

furcation. Anal side frequently, but not always, distinct from the regulär

interbrachial areas, by interposition of an extra plate in the second ränge.

Devonian to Lower Carbon- 4 ß

iferous (Keokuk Gr.); North

America, England, Belgium,

Germany.

Gilbert socrinus Phillips

{Goniasteroidocrinus Lyon and

Cass.; Ollacrinus Cumberland

nomen nudum). Calyx below

the arm-regions like that of

Bhodocrinus, but usually

larger, expanding at the

tegmen instead of constrict-

ing, and distinguished especi-

ally by large tubulär ap-

pendages extending outward

and downward from the

margin of the tegmen, and

overhanging the arm bases.

These appendages are f ormed

of rows of cylindrical plates,

pierced to their füll length

by a central canal ; they are

primarily ten in number, in some species free, and in some fused by their

outer margins to those of adjacent rays. Arms small, delicate, biserial, given

Fio. 286.
lihipidocrinus crenatus (Goldf.). Devonian ; Gerolstein, Eifel.
A, Perfect crown, of the natural size (after Schnitze). B, Tegmen,
with eccentric anus. C, Interior view of the base, showing the flve
IBB, two of the basals and one radial. D, Cohunn. E, Face of stem-
joint.

CLASR in CRINOIDEA 189

off in Clusters beneath the appendages. Anus subcentral, directly through
the tegmen. Devonian to Lower Carboniferous (Keokuk Gr.) ; North
America, Great Britain and Belgium.

Lyriocrinus Hall {Marsiipiocrinus Hall, non Blv. nee Phill.). Calyx depressed
hemispherical, with base rather truncate ; tegmen almost flat, composed of
numerous small, irregulär plates. Plates of dorsal cup usually smooth or
granulär. Arms ten, strong, unbranched, biserial. Interbrachials few, incor-
porating brachials to only part of the second order. Anal side usually not
distinct ; anus eccentric, at the end of a small tube. First interradials some-
times touch basals. Silurian ; North America and England.

Thylacocrinus (Ehlert. Kesembling Lyriocrinus, but calyx more elongate,
and i.Br profusely developed ; anal side slightly distinct. Arms twenty or
more, biserial, and not branching in the free State. Devonian ; France,
Germany and North America.

Änthemocrinus W. and Sp. Has one costal and few iBr. Arms biserial,
branching. Silurian ; Gotland.

Bhipidocriniis Zittel (ex Beyrich MS.) (Fig. 286). Calyx similar to that of
Lyriocrinus. Plates highly ornamented. Rays produced into two long, heavy,
uniserial trunks, giving off biserial, pinnuliferous ramules alternately on either
side. Middle Devonian ; Eifel, Germany.

Diamenocrinus (Ehlert. Arms uniserial, repeatedly branching. Devonian ;
France and Germany.

Lahuseniocrinus Tschern. ; Condylocrinus Eichw. Devonian ; Ural.

Ophiocrinus Salter {non Charlesworth, nee Semper nee Angelin). Devonian ;
South Africa.

Family 5. Melocrinidae Zittel (emend. W. and Sp.).

Monocyclic. Lower brachials, with well-defined interbrachials between them,
forming part of dorsal cup. Radiais in contact all around. Ordovician to
Devonian.

Glyptocrinus Hall (Canistrocrinus W. and Sp., Pycnocrinus S. A. Miller).
(Fig. 287.) Basals five. Dorsal cup obconical to subglobose, ornamented
with radiating Striae passing from plate to plate ; the eleva-
tions following the rays pronounced, and forming well-defined
rounded ridges, which meet imperceptibly with the free arm-
plates. Interbrachials very numerous, and enclosing supple-
mentary anals on the posterior side, which sometimes form a
continuous series. There are also numerous interdistichals,
and frequently interpalmars, which form conspicuous depres-
sions between the arm-plates. Tegmen low, composed of
minute irregulär pieces ; anus eccentric. Arms uniserial, ten

to twenty, branching in the free state, long and slender.

Column round, or exceptionally pentangular. Ordovician; pio. 287.

North AnTerica. Giyptocrmus dem-

Schizoerinus Hall. Ordovician (Trenton Group); New atici?n"'(cYnK

V^».1^ natian); Cincinnati,

JLOrK. i X T) 1 f '^hio. Natural size.

Stelidiocrinus Ang. {Harmocnnus Ang.). Basals tour.
Form of dorsal cup as in Glyptocrinus, but interbrachials fewer and much
larger, and plates generally without ornamentation. Plates of the tegmen

190

ECHINODERMATA— PELMATOZOA

PHYLUM IV

also comparatively large. Arms uniserial, sometimes interlocking. Silurian ;
Europe and North America.

Periglyptocrinus W. and Sp. Basais five. Arms biserial, dichotomous.
Ordovician (Trenton Gr.) ; Canada and Kentucky.

Scyphocrinus Zenker. Basais four. Arms uniserial, dichotomising fre-
quently. Calyx very large and elongate. Symmetry of dorsal cup slightly
disturbed by anals which are interposed between the interbrachials. Brachials
to lower part of the third order incorporated in the calyx, the upper ones free.
Interbrachials very numerous. Stem attached to a large, hollow spheroid,
strengthened by internal septa, regarded as a float by Hall ( = Camarocrinus),
as a Cystid by Barrande ( = Loholithus). Silurian and Devonian ; Europe and
North America.

Mariacrinus Hall (Zenkericrinus Waag. and Jahn). Basais four. Arms
uniserial, branching once or twice. In general aspect, construction of calyx,
and surface Ornament, resembling Glyjptocrinus. Silurian ; America, Europe.

Melocrinus Goldf. (Ctenocrinus Bronn, Astrocrinus Conrad, Turbinocrinus
Troost, Castanocrinus Eoemer, Clonocrinus Ö^hlert, Promelocrinus Jaekel).
(Figs. 288, 289). Basais four; interbrachials numerous; those of the posterior

interray enclosing one or more
supplementary anals. Anal aper-
ture eccentric, rarely extended in
a small tube. Rays produced into
two main uniserial rami, giving off
biserial, pinnule-bearing arms at
short intervals to the outside of

Fig. 288.

Melocrinus typus (Bronn). Uevoiiian (Spiriferen-Sandstein) ;
Dann, Bifel. B, Basais. C, Mould of stem-joints (the so-
called " Schranbensteine ").

Fig. 289.

Melocrinus. Analysis of calyx (after W.
and Sp.).

the bifurcation ; the rami may be separate (Silurian species), or more or
less fused by their inner margins (Devonian species). Column roun(?r Silurian
and Devonian ; Gotland, England, Germany and North America.

Cytocrinus Roemer. Like Melocrinus, but with arms borne on a single main
radial trunk from each ray. Silurian ; America.

Clonocrinus Quenstedt. {non CEhlert ; Corymhocrinus Ang. ; Polypeltes Aug.).
Basais four, hidden by column. Arms dichotomous, biserial both above and

CRINOIDEA

191

)elow the bifurcations. Base concave, forming an inverted cup. Dorsal cup
itrictly pentamerous ; no anal plate. Interbrachials large, not enclosing any
mal plates. Silurian ; England, Gotland and North America.

Tribliocrinus Geinitz (Spyridiocrinus Oihlert). Lower Devonian ; Germany
tnd France.

Technocrinus Hall. Like Melocrinus, but having ten strong, simple, biserial
'arms, which do not bifurcate in the free State. Interbrachials not enclosing
supplementary anals. Devonian (Oriskany) ; Maryland.

Macrost i/locrinus Hall. Basais three, unequal. Anal interradius much
wider than the others ; its first row consisting usually of three plates, while
that in the four other interrays consists of a single inter-
brachial. Arms ten, simple and biserial. Silurian; North
America.

Patelliocmius Ang. (Fig. 290). Basais three, unequal.
Arms biserial or of cuneate uniserial brachials. No anal
plates. Dorsal cup elongate. Silurian ; Gotland, North
America.

Allocrinus W. and Sp. Basais three, unequal. Arms
uniserial. No anal plates. Dorsal cup depressed. Inter-
brachials few, Silurian ; North America.

Briarocrinus Angelin. Silurian ; Gotland.

Centriocrinus Bather (pro Cenirocrinus W. and Sp., non
Austin, nee Worthen). Basais fused. Dorsal cup depressed.
No anals. Arms unknown. Devonian ; North America.

Dolatocrinus Lyon (Cacabocrinus Hall). Dorsal cup per-
fectly pentamerous, cup-shaped or saucer-shaped. Base u^ian ; Gotland.
usually concave. Basais primitively three, but completely ^^*^"r?\ ^^'"^^ ^^^^
anchylosed in the adult. Costals two ; iBr few, the first
ones extremely large. Tegmen comparatively flat, and composed of rather
large plates, of which the orals form the summit. Respiratory pores be-
tween arm bases frequently present. Anus at the end of a short tube.
Arms little known, sometimes branching and biserial. Column with
numerous projecting rings and buttresses. Devonian ; North America.

Stereocrinus Barris. Like the preceding, but the anchylosis of the BB
incomplete, and with only one costal. Devonian (Hamilton Group) ; North
America.

Hadrocrinus Lyon {Coronocrinus Hall ex Troost). Dorsal cup extremely
large, with concave base ; basals closely anchylosed. Brachials to the fourth
or fif th Order incorporated in the cup. Interbrachials numerous and large ;
no distinct anal plate in lower ranges. Tegmen composed of innumerable
small plates. Devonian (Onondaga) ; Falls of the Ohio, near Louisville,
Kentucky.

The type described under tliis genus has not hitherto been well understood. It falls into
two subdivisions, ditfering more strongly than Stereocrinus and Dolatocrinus ; one (/f. discus)
having few very heavy arms, and one costal ; the other {H. plenissimus) witli numerous very
slender arms, an^ two costals.

Fig. 290.

Patelliocrinus lepto-
-D„„p dactylus (Ang.). 8il-

Family 6. Calyptocrinidae Angelin.

Momcydic. Lower brachials and interbrachials forming an impmiant pari of
the dorsal cup, which above the base, is perfectly pentamerous. Plates of the calyx

192

ECHINODERMATA— PELMATOZOA

THYLUM IV

usualUj limited to a definite mimber. Radiah in contact all around. Arms resting
in compartments formed hy partitions attached to the tegmen. Silurian and
Devonian.

Eucalyptocrinus Goldf. {Hypanthocrinus Phill.) (Figs.
291, 292). Calyx with a deep concavity at the lower end,
the B forming the bottom, and the B the sides of an
inverted cup. Supplementary pieces of the calyx con-
sisting of 1 X 2 interbrachials, and one interdistichal ; the
latter of the same form as the interbrachials, and nearly
as large as the two upper ones combined. Tegmen
elongate, its upper part extended to form a tube. It is
j composed of five ranges of plates, of which the two
middle ones are the least regulär in their arrangement,
and the upper one closes the centre. Attached to the
outer walls of the tegmen, and extending to its top, are
ten partitions supported by the interbrachials and inter-
distichals, which form deep, vertical compartments for
the reception of two arms each. Arms twenty, biserial ;
composed of very narrow pieces. Column round. Sil-
urian ; Gotland, England (Wenlock Limestone), and

A Single species occurs
in the Devonian of the Eifel.

Callicrinus Ang. (Fig. 293). Calyx flask - shaped ;
concavity at the base deeper and wider than in the
preceding, sometimes involving not only the radials, but parts of the

Fig. 291.
Eucalyptocrinus regu
laris (Hising.). Silurian, -»t i a • /^-r-

Gotland. Crown with North Amcrica (Niagara Group),

arms removed from one - —

ray in order to sliow tlie
niches in whicli they
repose.

Fig. 292.

iri : ri r2 : iri
dist. dist.

FAicalyptocrinus rosaceus (Goläf.). Devonian; Gerolstein, Eifel. ^/Perfect crown. B, Ciagrammatic longi-
tudinal section of the calyx (h, Basais ; ri, Radials ; r2, First costals ; y, Lower, and ö, upper piece of the wing-
like processes). C, Tegmen. D, Dorsal cup (ri, Radials ; r'-J, First costals ; (/■, Intcrnidials ; disL, Distichais ;
int. dist., Interbrachials; r^, Palmars) (after L. Schultze).

costals as well. Partitions for the reception of the arms much shorter, ex-
tending to less than half the height of the arms. Otherwise similar to

CLASS III

CRINOIDEA

193

Eucalyptocrinus, and sharing the same distribution in the Silurian ; not known
in the Devonian.

Fig. 293.
Callicnmis rodatus (Hising.). Silurian ; Gotlaud. A, Crown. B, Calyx showing the construction of the
tegmen. V, Inner or ventral aspect of tlie ba.se. D, Outer or dor.sal aspect of the same. Natural size (after
Angelin).

Chicagocrinus Weller. Like Callicrinus, but the primibrachs (costals)
reduced to a single diminutive plate in each ray. Silurian ; North America
(Chicago area).

Family 7. Batocrinidae Waclismuth and Springer.

Monocyclic. The lower brachials forming an important part of the dorsal cup.
Radiais in contad except at the posterior side, where they are separated hy a hepta-
gonal anal plate, followed hy three plates in
the second ränge. Base hexagonal. Rays
usually hranching hy equal hifurcations.

Subfamily A. Periechocrininae.

Tegmen composed of numerous small, un-
dißerentiated plates. Ordovician to Lower
Carboniferous.

Tanaocrinus W. and Sp. Interbrachials
numerous, indefinitely arranged in de-
pressed areas passing gradually into the
tegmen, leaving brachials in ridges con-
tinuing to the free arms ; posterior area
divided by median ridge of anal plates
resembling brachials. Arms uniserial
with ossicles more or less cuneate, tend-
ing to interlock distally ; branching be-
yond the calyx. Calyx elongate. Basais
five. Column round, or sub-pentagonal.

o^o

gfib?

ÄO^N^O®^

^^^;:^^^(D^^9£ß

of

Q^

Fi(

BdtocrinHfi si

294.

Carboniferous. Analysis

of calyx ; h, Basals ; li, Radials ; ihr, Interbi-achials ;
SX, supplenieiitary anal ; X, Special anal plate
(after W. and Sp.).

Ordovician (Cincinnatian) ; Ohio.

Xenocrinus^ S. A. Miller. Basals four. Arms not branching. Column

1 Better speciraens obtained since the preparation of Wachsmuth and Springer's Monograph
show clearly not only that the interbrachials in this genus are deflnite plates with close sutures, but
VOL. I O

194

ECHINODERMATA— PELMATOZOA

PHYLÜM IV

quadrangular. Structure otherwise substantially as in the preceding.
Ordovician (Cincinnatian) ; Ohio.

Compsocrinus S. A. Miller. Basais four. Arms simple or branching.
Basais and radials more evenly rounded and less excavate laterally, but other-
wise differing little from Xenocrinus. Ordovician (Cincinnatian) ; Ohio.

Jcacocrinus W. and Sp. Interbrachials few, definitely arranged, not in
strongly depressed areas, and brachials and anals not in prominent ridges.
First primibrach (costal) quadrangular. Arms uniserial, slender, unbranched,
with cuneate ossicles tending to interlock at the tips. Calyx rather low and
rotund. Basais three. Silurian ; Indiana and Kentucky.

Carpocrinus Müller (PJioenicocrinus Austin ; Abracrimis d'Orb. ; Habro-
crinus, Pionocrinus, Lepiocrinus Ang.) (Fig. 295). Calyx as in the preceding.

.,,„,. Arms simple, heavy,

usually not exceeding
ten, with very short,
wide ossicles, slightly
cuneiform, the longer
face bearing two pin-
nules, the shorter but
one. Silurian ;Gotland,
England.

Desmidocrinus Ang.
(Fig. 296). Like the
preceding but with arms
fifteen to twenty, ossi-
cles longer and quad-
rangular, bearing one
pinnule to each side.
Silurian ; Gotland and
England.

Abacocrinus Ang.

(Carolicrinus Waag. and Jahn). Basais four. Calyx rotund. Interbrachials
rather numerous, definitely arranged, not in depressed areas ; brachials and
anals not in prominent ridges. First primibrach hexagonal. Arms branch-
ing, biserial from the calyx up. Silurian ; Gotland.
Macarocrinus Jaekel. Devonian ; Germany.

Penechocriniis Austin (Geocrinus d'Orb.; Pyxidocrinus Müller; Trochocrimis
Portlock ; Pradocrinus de Verneuil). Basais three. Calyx elongate, expanding
to arm bases ; plates thin and long, usually with narrow median ridges along
the brachial series, which bifurcate two or three times within the calyx, lead-
ing to twenty-five or thirty arms, which are biserial beyond the calyx and do
not branch after becoming free. First primibrach (costal) hexagonal. Inter-
brachials numerous, definitely arranged. Silurian ; England and Gotland.

Saccocrinus Hall. Like the preceding, but the arms branch from about
twenty openings after becoming free, and are biserial both below and above the
bifurcations. Silurian to Lower Carboniferous (Upper Burlington) ; North
America and (?) Gotland.

Fig. 295.

a, Carpocrinus comtus (Ang.). Silurian ; Got-
land. Crown viewed from the anal side, natural
size. b, H. ornatus (Ang.). Tegmen showing cover-
ing pieces of the ambulacra (after Angelin).

Fig. 296.

Desmidocrinus
heterodactylus (Ang. ).
Silurian ; Gotland.
Natural size (after
Angelin).

that they do not pass dowii to the basals in eitlier species. This leaves no character to separate it
from the Batocrinidae, and the present reviser agrees with Bather in placing it with Tanaocrinus
and Compsocrinus as the primitive forms of that faniily.

CLASS in CRINOIDEA 195

(?) Beyrichocrinus Waag. and Jahn. Silurian ; Bohemia.

Gennaeacrinus W. and Sp. Basais three. Calyx low and broad, strongly
lobed at the arm bases ; plates thin and highly ornamented. First primibrach
hexagonal ; iBr rather numerous. Arm openings twenty-five or more ; arms
unknown. Devonian ; Indiana and New York.

Megistocrinus Owen and Shum. {Tylocrinus Wood). Basais three. Calyx
usually large, hemispheric, with greatest height below the arm bases ; usually
biit little lobed ; plates heavy, smooth or ornamented. Interbrachials
numerous ; first primibrach hexagonal. Arms sixteen to twenty, branching
in the free State, biserial above and below the bifurcations. Devonian to
Lower Carboniferous (Upper Burlington) ; North America.

Subfamily B. Barrandeocrininae.

Tegmen narrow and rigid. Arms permanently directed downward enclosing the

mlyx.

A highly specialised type, represented by a single genus, which, though having a siniilar
calyx, ditfers so strongly in habitus from those of the next section that it is better kept
separate.

Barrandeocrinus Angelin (Cylicocrinus S. A. Miller). Basais three. Calyx
rather elongate, with tegmen nearly flat. Interbrachials few, definitely
arranged. Arms ten, heavy, biserial, directed downward over the calyx, with
pinnules opening outward. Silurian ; Gotland and North America.

Subfamily C. Batocrininae.

Tegmen hroad, well differentiated ; 'plaies large atid heavy, forming a rigid roof.
Arms not branching heyond the calyx; biserial. Respiratory por es fr equently present.
First primibrach (costal) usually quadrangular. Basais three in all known genera.
Devonian to Lower Carboniferous.

This section flourishes araid a remarkable local development of Crinoid life especially
characteristic of the Mississippian area of the United States. The fauna is enormously prolific
in numbers and variety in the Burlington and Keokuk limestones of the Mississippi Valley, but
alniost entirely wanting in the Lower Carboniferous of Great Britaiu and Belgiuni, and of
other parts of the United States. Only a few straggling species come from the Devonian.

§ 1. Anus at the end of a tube.

a. Interbrachials few, separated from tegmen by arch of brachials.

Batocrinus Casseday. Calyx biturbinate. Arms short, equidistant. Anal
tube very long, central, extending beyond arms. Kinderhook to St. Louis
Group; North America.

Eretmocrinus Lyon and Cass. Like Batocrinus, but arms paddle-shaped,
and anal tube short, eccentric, tending to curve. Devonian to Keokuk
Group ; North America.

Alloprosallocrinus Lyon and Cass. Calyx conical ; dorsal cup almost flat,
greatest height above the arm bases. First primibrach usually wanting.
Approaching Agaricocrinus in shape. Anal tube sub-central ; arms unknown.
Keokuk limestone ; North America.

ß. Interbrachials few, usually separated from the tegmen except at anal skle.

Macrocrinus W. and Sp. Calyx elongate, biturbinate to subovoid. Anal

196

ECHINODERMATA— PELMATOZOA

PHYLUM IV

tube rather large, extending beyond arms. Arms twelve to sixteen. Upper
Burlington and Keokuk Gr. ; America.

Dizygocrinus W. and Sp. Calyx rotundate. Anal tube rather small,
usually not extending beyond the arms. Arms single or double, from twelve
to twenty openings. Upper Burlington to St. Louis Group ; America.

Eutrochocrinus W. and Sp. Calyx wheel-shaped. Anal tube long. Arms
short, eitber single or double from twenty openings. Upper Burlington and
Keokuk Group ; America.

y. Interbrachials few, sometimes connected with tegmen all around.

Uperocrinus Meek and Worthen (Lohocrinus W. and Sp., Hyperocrinus
Bather) (Fig. 297). Calyx pyriform. Anal tube large
and often spiniferous. Arms short, single, often arranged
in groups, openings directed upward. Upper Burlington
and Keokuk ; America.

§ 2. Anus without a tube, directly through tegmen.
Interbrachials few, usually not connecting with tegmen except
at anal side.

Aorocrinus W. and Sp. Calyx small, elongate to ro-

tund or biturbinate. Arms
rather strong, onefrom each
opening, cylindrical. Teg-
men plates not spiniferous.
Devonian to Burlington ;
Europe and America.

Coelocrinus M. land W.
(Sphaerocrinus M. and W.
non Roemer). Similar to
preceding genus, but with
concave base. Burlington
Group ; America.

Dorycrinus Roemer (Fig.
298). Calyx small to'large;
posterior oral alone, or with
primary radial plates of
tegmen, spiniferous. Arms

rather small, usually two from each opening. Devonian to Keokuk ; America.
Agaricocrinus Hall (ex Troost). Calyx small to large, hemispherical, with

dorsal side usually flat or concave, and greatest height above the arm bases.

First primibrach sometimes hexagonal. Arms ten to sixteen, very heavy,

directed outwards. Burlington to Keokuk ; America.

Fig. 297.

Uperocrinus pyriformis
(Shumard). Lower Carbon -
iferous ; Burlington, Iowa.
Nat. size (after Meek and
Worthen).

Fig. 298.

Dorycrinus quinquelohus (Hall)
var. intermedius(M. and W.). Lower
Carboniferous ; Burlington, Iowa.
Calyx viewed from the anal side.
Natural size (after Meek and Wor-
then).

Family 8. Actinocrinidae.

Monocyclic. Lower brachials, with well-defined interbrachials between them,
forming an important part of the dorsal cup. Radiais in contact except at the anal
side, where they are separated by a hexagonal anal plate, followed by two plates in the
second ränge. Basais three, forming a hexagon. Arms biserial in all known genera.
Rays usually branching by alternate bifurcations. Lower Carboniferous. Kinder-
hook to Keokuk.

CLASS III CRINOIDEA 197

This family represents another line of ju-ofuse crinoidal development characteristic of the
Mississippian area iu the United States, parallel to tliat of the later Batocrinidae. It maybe
considered as a direct branch from that family, but sliarply and consistently distinguished
from it by the fact that the anal plate is followed by two plates instead of three. It was
sliort lived, being restricted to the lower part of the Lower Carboniferous, where it culrainated
in large and striking forms, not found outside of the Mississippi Valley, Only two of its genera
are certainly known to occur in the approximately äquivalent forraation of Europe.

§ 1 . Tegmen composed of well differentiated plates, mth anus at the end of a tuhe.
a. Interbrachials connecting with the tegmen.

Amphoracrinus Austin. Calyx lobed, the largest part above the arm zone ;
rays widely separated. Interbrachials few. First primibrachs usually quad-
rangular, sometimes hexagonal. Arms stout, either simple or branching,
biserial below and above the bifurcations. Anal tube short, eccentric. Oral
plates often strongly spiniferous. Anal plate exceptionally followed by three
plates in the second ränge. Lower Carboniferous ; Waverly to Lower Bur-
lington Group in the United States, and lower part of the Mountain Lime-
stone in Britain.

This genus is a transition form from the Batocrinidae, in whieh the Actinocrinoid structute
of the anal side has not become constant. In some species the middle plate of the second row
has not been entirely eliminated, but occasionally appears in diminished size, and scarcely
touching the anal plate. This is consistent with its geological position as one of the earliest
of its family, and one of the first to disappear.

Admocrinus Miller {Amphora Cumb.; Phillipsocrinus M'Coy; Blairocrinus
S. A. Miller) (Fig. 299,1)). Calyx lobed, rays widely separated; largest part
below arm zone. Interbrachials numerous. First primibrachs usually
hexagonal. Rays within the calyx bifurcating alternately from every second
or third plate above the first. Arms either simple from the calyx, or
branching, and biserial below as well as above the bifurcations. Anal tube
long, central. Lower Carboniferous; Lower Burlington to Keokuk, in the
United States, and Mountain Limestone of Britain and Belgium.

Steganocrinus M. and W. {Sampsonocrinus M. and G.). Calyx similar to that
of Admocrinus, but relatively lower, and having the rays produced into one
{S. sculptus) or two (S. pentagonus) tubulär extensions giving off pinnulate arms
alternately at the sides. Anal tube small. Lower Carboniferous (Lower and
Upper Burlington) ; North America.

ß. Interbrachials not connecting with tegmen.

Cactocrinus W. and Sp. (Fig. 299, ^, B). Calyx not lobed. Arms usually
strong, twenty to forty, unbranched, about equidistant, given off in a more or
less continuous ring, and directed upward ; bifurcations beyond the costals
from every successive brachial. Anal tube long, central. Lower Carboni-
ferous (Kinderhook to Lower Burlington); North America, (?) Belgium.

Teliocrinus W. and Sp. Similar to the last, but arms more slender and
numerous, usually sixty or more, their lower portions directed outward, and
forming a broad continuous rim. Lower Carboniferous (Upper Burlington) ;
North America.

§ 2. Tegmen of undifferentiated plates. Anus directly through the tegmen, without
a tube.

Physetocrinus W. and Sp. (Fig. 299, C). Interbrachials connecting with
tegmen. Calyx rotund, lobed, with arms in groups, stout ; tegmen rounded

198

ECHINODEKMATA— PELMATOZOA

PHYLUM IV

and elevated ; anus eccentric. All bifurcations beyond costals given off from
every alternate brachial. Lovver Carboniferous (Lower and Upper Burlington) ;
North America.

Strotocrinus M. and W. Interbrachials not connecting with tegmen.

""^-^.y

%y

\% dßo

t^

■fßS ^ -^^»

ö3;«ig

&

m

Fio. 299.

A, Cactocrinus proboscidialis (Hall). Lower Carboniferous ; Burlington, Iowa. Calyx witli fractured
tegmen, showing the subtegminal ambulacral skeleton, and the convoluted digestive organ. B, Enlarged
portion of the ambulacral skeleton, C, Natural cast of tegmen of Phy^ietocrinus, with impressions of food-
grooves (a), condncting from the arms to the mouth (o) ; an, Anus. D, Diagraui of Äctinorrinus (after W.
and Sp.).

Calyx not lobed ; rays bifurcating on alternate brachials from distichals up,
and extended into a broad, flanging rim, as in TeMocrinus, but more
pronounced. Arms very numerous and slender. Tegmen low, sometimes flat
or concave, composed of innumerable small pieces ; anus eccentric. Lower
Carboniferous (Upper Burlington) ; North America.

Family 9. Platycrinidae Roemer.

Monocydic. Brachials and interbrachials usually but slightly represented in the
dorsal citp : the lower brachials taking more or less the form of arm plates, but being
strongly connected^ either with the solid tegmen by modified covering plates and strong
interambulacrals, or with the cup by large interbrachials which are usually more or
less interambulacral in position. Radiols in contact all around, there being no
special anal plate. Basais forming a pentagon ; three, unequal, and frequenÜy
anchylosed. Silurian to Carboniferous.

CLASR TU

CRINOIDEA

199

§ 1. Rays with two or more primilrrachs (costals).

Coccocrinus Job. Müller. The simplest form of the Camerata, the calyx
consisting only of three basals, five radials, 2x5 costals, five interbrachials and
five orals. Calyx small, rotund ; basals and radials forming almost the entire
dorsal cup. Tegmen almost completely occupied by five large, triangulär,
symmetrical orals, forming a pyramid. Anal opening in the interradio-
oral suture. Arms delicate, branching once, uniserial with cuneate joints.
Column round. Silurian ; North America. Devonian ; Eifel.

Culicocrinus Joh. Müller. Transitional between Coccocrinus and Platycrinus ;
generally similar to the former. Orals asymmetrical. Arms heavy, biserial.
Column round. Middle Devonian ; Eifel.

Hapalocrinus Jaekel em. Bather {Agriocrinus, Thallocrinus and Clematocrinus
Jaekel). Orals small ; interambulacra visible. Arms uniserial, with cuneate
joints ; branching once or twice. Column round, with strong cirri. Silurian ;
England, Australia, North America. Devonian ; Germany.

Cordylocrinus Angelin. Tegmen composed of numerous plates. Arms
uniserial, or slightly interlocking. Column round, with long cirri. Silurian ;
Gotland. Devonian ; North America.

§ 2, Eays with only one primibrach (costal). Orals occupying but a small part of
the tegmen, asymmetrical ; ambulacral plates well defined.

Marsipocrinus Bather {pro Marsupiocrinus Phill., nm Blv.). (Syn. Cypellocrinus
vel Cupellaecrinus Shumard, ex Troost, non Steininger.) Brachials to axillary
distichal usually incorporated in cup. Arms biserial, ten or twenty. Column
round. Axial canal large. Silurian ; England, Gotland, North America.

Fig. 300.
Platycrinus suhspinomn (Hall). Lower Carbonifer-
ous; Burlington Group, Iowa. Analysis of dorsal
cup, omitting anal Interray. h, Basals ; R, radials ;
I, Costals; ir, Interbrachials (after Wachsmuth
and Springer).

Fio. 301.
Platycri iius triginti(lactyliu<<
(Austin). Lower Carbonifer-
ous ; Tournay, Belgiuni (re-
stored, after de Koninck).

Platycrinus Miller {Centrocrinus, Pleurocrinus Austin; Edwardsocrinus d'Orb.)
(Figs. 300, 301). Calyx rotund. Radials large with crescent-shaped facets.
First interbrachials at the level of the arm bases ; consisting of three plates
horizontally arranged, usually partly interambulacral, but sometimes succeeded
by one or more ranges incorporating the distichals ; plates of anal interradius
usually more numerous than those of the other sides. Orals usually large,
asymmetrical, occupying but a small part of the tegmen. Ambulacra rigid,

200

ECHINODERMATA— PELMATOZOA

PHYLUM XV

and incorporated into the tegmeri. Anus either eccentric, or at the end of a
thick, usually short tube. Arms branching once to three times, uniserial in
the lower parts, but becoming biserial distally. Column elliptical and twisted ;
the axes of the upper and lower surfaces of the individual segments being at
a slight angle with one another; central canal very minute; strong cirri
toward distal end. Rare in Devonian ; abundant in Lower Carbonif erous of
England, Belgium and North America (Hamilton to St. Louis Groups).

Brahmacrinus Sollas. Like Platycrinus, but radials relatively smaller, and
lower brachials larger, and incorporated in dorsal cup to the height of the
second distichals. Lower Carboniferous ; England.

Eudadocrinus M. and W. Calyx like Platycrinus, but with rays produced
into one or two main rami, roofed with rigid covering plates, forming tubulär
extensions of the calyx, giving off at alternate sides biserial, pinnuliferous
arms. An extreme development of the family type, but not the latest in
time. Lower Carboniferous (Kinderhook to Keokuk) ; North America.

Family 10. Hexacrinidae Wachsmuth and Springer.

Monocydic. Radials in contaä except at the posterior side, where they are
separated hy an anal plate. Basais three, or two, forming a hexagon. Strudure
otherwise as in the Platycrinidae. Devonian to Lower Carboniferous.

§ 1. Basais three.

Hexacrinus Austin (Fig. 302). Costals two, united by syzygy, or one.
Rays usually in two main trunks, bearing uniserial pinnulate arms on one or

Fig. 302.

Hexacrinus elongatus (Goldf.). Devonian ; Pehn, Eifel. a, Calyx seen from one side ; /;, Aspect of summit ;
c, Analysis of calyx and arms ; d, e, Column of //, spinosus (Müll.) (after L. Schnitze).

both sides at intervals. Tegmen as in Platycrinus. Column round, with small
axial opening. Devonian. Represented by numerous species in England,
Belgium, and the Eifel, but by only a few in North America.

Arthracantha Williams (Histricrinus Binde). Calyx as in Hexacrinus, but
the plates covered with movable spines borne on tubercles. Arms dichotomous,
biserial. Stern circular. Devonian : New York and Canada.

CLASS III

CRINOIDEA

201

§ 2. Basais two.

Dichocrinus Münster (Cotyledonocrinus Lyon and Cass.). Costals two,
usually united by syzygy, as are also the first two brachials of each order,
giving the appearance of a single plate. Arms biserial, branching once to
three times ; occasionally pendent. Stern round. Lower Carboniferous ;
Belgium, Great Britain, North America (Kinderhook to Kaskaskia).

Camptocrinus W. and Sp. Like Dichocrinus except in the stem, which is
concavo-convex in section, as in Herpetocrinus, tending to coil around the crown.
Lower Carboniferous (Burlington to St. Louis) ; North America.

Talarocrinus W. and Sp. Costal one, small, trigonal, sometimes hidden
by the distichals. Calyx plates massive ; anal resembling anterior radial in
form and size. Column round. Lower Carboniferous (St. Louis to Kaskaskia) ;
North America.

Pterotocrinus Lyon and Cass. (Asterocrinus Lyon non Münster). A re-
markable modification of Talarocrinus. Brachials up to third order incorporated
into dorsal cup. Anal plate much smaller than the radials. The axillary
first ambulacral produced into large wing-like processes, stretched out from
the tegmen. Lower Car-
boniferous (Kaskaskia) ;
North America.

Family 11. Acrocrinidae

Waclismutli and Si^ringer.

Monocyclic. Basais separ-
ated from radials by a large
bell of accessory pieces. Badials
in contact except at the posterior
side, where they are separated
by an anal plate, Structure
otherwise as in the Hexa-
crinidae. Lower Carboni-
ferous.

o,

Q

0
O

O 9ä<o"

oö8

8oRo

Acrocrinus Yandell (Fig.
303). Basais two, forming
a hexagon. Calyx as in
Dichocrinus with intercala-
tion of several circlets (u^)
to twenty) of supplementary
plates, those immediately
above the basals being the
smallest and latest formed.

Costals small, trigonal. Arms two to four to the ray, biserial, either erect
or pendent. Column round. Lower Carboniferous. The last survivor of
the Camerata (Burlington to Coal Measures), and known chiefly in North
America but reported recently from England.

/ R N

Fio. 303.
Acrocrinus sp. Lower Carboniferous. /), Basals; R, lladials

I, Costals ; x, Special anal plate.
ary plates (after W. and Sp.).

tVU the others are Supplement-

202 ECHINODERMATA— PELMATOZOA phylum iv

Order 2. PLBXIBILIA Zittel.

( = Articulata W. and Sp. non Müller).

Crinoidea in which the lower brachials are incorporated in the dorsal cup, either
hy lateral union, hy interhrachials, or hy a finely plated sJcin, hut never rigidly.
Tegmen flexible, with amhulacra well defined, roofed with movaole covering plates ;
mouth supra-tegminal and open. Arms non-pinnulate, with a wide and shallow
ventral groove. Base dicydic ; infrabasals three, unequal, rarely iindivided, some-
times greatly reduced or atrophied ; often fused with top columnal. Radiais and
brachials united by modified muscular articulation, usually without transverse ridge,
accompanied by loose suture between other plates, producing a flexible calyx admitting
motion between apposed faces of the plates. Orals small, posterior one much the
largest, with the food grooves passing between them to the mouth ; they are more or
less surrounded by perisome, which often passes down between the rays. Stern round ;
proximal columnals usually very short, frequently wider than the others and forming a
Gonical expansion next to the calyx. Ordovician to Carboniferous.

The calyx and arm plates in this group are usually thick and relatively short,
with a muscular or loose ligamentous articulation, which admits of much mobility
upon one another. The combination of massiveness with flexibility is a strong
distinctive character. The union between brachials is frequently marked exteriorly
by arcuate sutures, produced by a downward projection of the outer proximal edge of
the plates into a corresponding depression on the distal edge of those preceding ; this
extends but little below the surface, the sutures beneath being perfectly straight. By
contraction in fossilising the projecting processes are frequently fractured, giving rise
to an erroneous appearance of "patelloid plates."

Owing to the fact that in most of the genera the rays are more or less continuous
from the radials up, with no well-defined zone of demarcation between calyx and
arms, there is a general similarity of type which renders the subdivisions less apparent
than in the Camerata. The most prominent modification of the general type relates
to the structure of the posterior interradius, upon which two well-defined divisions
may be recognised : (1) the strong anal side, in which the anal plates, when present,
are partly or whoUy incorporated in the calyx wall ; (2) the weak anal side, in which
the anal plates are separated from adjacent brachials at one or both sides by a pliant
integument, and tend to form a flexible series supporting the anal tube, which is
a mere extrusion of the pliant perisome of the tegmen. The second of these
structures is analogous to that in the larval stage of the living Crinoids, is the most
generalised, and was the most persistent — appearing in the Ordovician, and ending
with the culmination of this group in the Kaskaskia, or possibly Goal Measures. The
first is more specialised, and ranges from the Silurian to the Warsaw. Within it modifi-
cations in the size and position of the infrabasals, and in the general habitus, afford
ground for family divisions, which shade into one another to some extent.

Among the genera of each family there may be observed a migration of the
radianal, from a primitive position directly underneath the right posterior radial (as
if the radial were transversely bisected) in the older formations (Ordovician and some
Silurian), to an oblique position to the lower left of the radial (some Silurian and
Devonian), and then to complete elimination in the Carboniferous. Modifications in
the number of primibrachs, by increase from two to three or more, were also to some
extent coincident with these changes. The structure of the base remains remarkably
constant, the proximal circlet consisting of three unequal infrabasals, which are
exceptionally fused to an undivided disk, and in certain genera tend to disappear by
resorption.

I

ci^Ass III CRINOIDEA 203

I

A. Anal plates, when present, partly or wholly incorpm'ated in the
calyx.

Suborder 1. SAGENOCRINOIDEA.

Family 1. Lecanocrinidae Springer.

Infrabasals abutting on dorsal side of basals, more or less ered, and taking
pari in the calyx wall Crown usually small, short, rotund, with arms abutting,
frequently interlocking, and closely infolding at the distal ends. Silurian to Lower
Carboniferous.

a. Rays in contact except at the posterior side, where anal x separates radials, toucliing
posterior basal. No iBr in other areas.

Lecanocrinus Hall {Cyrtidocrinus Ang.) (Fig. 304). Arms dichotomous,
flat, interlocking. RA rhombic, obliquely below r.post.R. Anal x alone.
IBr two (exceptionally one). Silurian to Devon-
ian; North America, Gotland, England.

Mespilocrinus Koninck and Lehon. No RA.
Anal X alone, or followed by a triangulär plate.
Arms dichotomous, usually rounded, with dex-
trose twist. IBr two. Lower Carboniferous
(Kinderhook to Upper Burlington) ; Belgium,
England and Mississippian area. North America.

h. Rays above radials partly or wholly separated all FiGr7o4

around, by *5r or perisome. Anal « usually between pos- ^ . , . '. .\ „., .

terior radials, touohing basal (exception, SipUroainJ). o'tSTS^^TTn Ä thTS

side, flgiire reversed (after Angelin).

Homalocrinus Ang. Infrabasals very large,
enveloping basals, and sometimes radials. Arms heterotomous, with ten
main trunks, bearing ramules. Rays abutting above interbrachials, peri-
some not exposed interradially. Anal x, and large iBr in other areas,
followed by others. RA under r.post.R. between BB. IBr two. Silurian ;
Gotland, England.

Calpiocrinus Ang. Like the preceding, but the rays have twenty main
trunks bearing ramules, and there is no RA. Silurian ; Gotland.

These two genera are remarkably specialised in the enormous overgrowth
of the infrabasals, which envelop, and sometimes entirely conceal, both basals
and radials, a fact which has made them heretofore generally misunderstood.

Cholocrinus Springer. IBB not enveloping BB. Arms heterotomous,
with ten main trunks bearing irregularly branching ramules. Rays not
abutting, divergent, not closely infolding; no regulär iBr, areas filled with
perisome. Anal x followed by perisome. RA rhombic, obliquely below
r.post.R. IBr two. Rays unequally developed, the two antero-lateral ones
being dwarfed. Type, Forbesiocrinus obesus Ang. Silurian ; Gotland.

Anisocrinus Ang. Arms dichotomous. Rays abutting above iBr, perisome
not exposed. Anal x alone, or with others following ; iBr few, one large,
alone, or followed by others. RA more or less under r.post.R, above line
of BB. IBr two. Silurian ; Gotland, and North America (Western Niagara).

Pycnosaccus Ang. (Oncocrinus Bather). Arms dichotomous. Rays not
abutting; no regulär iBr, areas wide, filled with perisome. Radial facets
much less than the width of R. Anal x alone, followed by perisome. JtA

204 ECHINODERMATA— PELMATOZOA phylum iv

rhombic, obliquely below r.post.R. IBr oiie to four. Silurian ; Gotland,
England, and North America (Niagara of western area and of New York).

Nipterocriniis Wachsmuth, in Meek and Worthen. Similar to Pycmsaccus,
but without BA or anal x, and with infrabasals fused to one. The last
survivor of this family. Lower Burlington to Keokuk ; Mississippian area,
North America.

Family 2. Sagenocrinidae Springer.

Infrabasals ahutting on dorsal side of basals, low and flat, taking Utile part in
calyx wall. Crown usually large, elongate, expaiiding above the radials. Rays
above radials partly or wJiolly separated all around. Silurian to Lower
Carboniferous.

Temnocrinus Springer. Arms dichotomous. Anals and iBr only in lower
part of interradial areas ; anals more than one abreast. BA in form of B
under r.post.R. Anal x separating BB and touching post.B. IBr two.
Type, Taxocrinus tuberculatus Miller. Silurian ; England, (?) North America.

Meristocrinus Springer. Similar to Temnocrinus, but with anal x followed
by other plates in series, and IBr three. Type, Taxocrinus loveni Angelin.
Silurian ; Gotland.

Sagenocrinus Austin. Arms dichotomous. Anal and iBr areas filled with
solid plates. BA obliquely below r.post.R, usually between BB, and not
touching r.ant.R. IBr two. Silurian ; England, Gotland, and North
America (Western Niagara).

Lithocrinus W. and Sp. (Forbesiocrinus Ang. non Kon.). No BA. Arms
heterotomous, with ten main trunks bearing branching ramules. iBr well
developed in lower part of areas. IBr two. Type, Forbesiocrinus divaricatus
Ang. Silurian; Gotland.

Forbesiocrinus Koninck and Lehon. No BA. Arms dichotomous. iBr
usually numerous, Alling the areas with solid plates. IBr three, except in
F. agassizi, which has two. The culmination of this family. Lower Carboni-
ferous (Lower Burlington to Warsaw) ; Belgium. Also Mississippian area,
North America.

Family 3. Ichthyocrinidae Wachsmuth and Springer (restr.).

Infrabasals wholly witliin the ring of basals, concealed by the column,
sometimes disappearing by resorption. Crown usually elongate,
expanding above radials, but often infolding distally. Arms
usually closely abutting or interlocking. Silurian to Lower
Carboniferous.

a. Rays in contact except between posterior radials when separated
by anal x.

Ichthyocrinus Conrad (Fig. 305). Arms dichotomous,

Fig. 305. closely interlocking, and infolding. BA in form of B under

Ichthyocrinus laevis r.post.R. No anal, üosterior basal not difFerentiated. IBr

crown. Silurian (Xia- two. Silurian ; Gotland, England and North America (New

port, New' York (after York and Western Niagara area).

^^^^^- Clidochirus Ang. Similar to Ichthyocrinus, but with

posterior basal difFerentiated, supporting anal x alone, or followed by others.

CLASS III CRINOIDEA 205

Silurian ; Gotland. Silurian to Devonian (Niagara, Manlius, Helderbergian) ;
North America.

Metichthyocrinus Springer. No RA. No anal ; posterior basal not differ-
entiated. Crown rotund. Arms dichotomous, interlocking and infolding.
IBr two. Type, Ichthyocr. tiaraeformis Hall ex Troost MS. Lower Carbon-
iferous (Kinderhook to Lower Burlington) ; Mississippian area ; North
America.

b. Rays above radials partly or wholly separated all around ; posterior radials separated
by anal x when present,

Euryocrinus Phillips. No RA. Arms dichotomous. Anal x followed by
others in a single series. iBr few, usually in single series. IBr three. Lower
Carboniferous ; England. Devonian to Lower Burlington ; North America.

Amphicrinus Springer. Similar to Euryocrinus, but with iBr numerous, in
more than one series, and primibrachs two. Lower Carboniferous ; Scotland.

Dadylocrinus Quenst. (Dimerocrinus Pacht non Phillips). No RA. Crown
elongate, expanding from RR up. Arms heterotomous, with twenty main
trunks bearing ramules. iBr few or absent. Anal x followed by others in
more than one series, suturally connected at the sides. IBr two. Devonian ;
Russia, Belgium.

Synerocrinus Jaekel {Forbesiocrinus Trautschold non de Kon.). Similar to
Dadylocrinus, but with anal x followed by others in series tending to form a
tube (transition toward Taxocrinidae). Crown more rotund in young
individuals. Lower Carboniferous ; Bergkalk near Moscow, Russia.

Wachsmutliicrinus Springer. Similar to Dadylocrinus, but with no anal
plate, posterior basal not difFerentiated. The last survivor of this family in
America. Type, Forbesiocrinus thiemei Hall. Lower Carboniferous, Kinder-
hook to Upper Burlington ; Mississippian area ; North America.

B. AU anal plates sejparated by perisome from adjacent brachials at one or both
sides, tending to form a tubulär series, from posterior basal up.

Suborder 2. TAXOCRINOIDEA.

Family 4. Taxocrinidae Bather emend. Springer.

Infrabasals usually abutting on dorsal side of basals, but low, taking Utile part
in the calyx wall. Crown usually elongate, with arms divergent, and not abutting
above interbrachial areas. Interbrachials present all around. Ordovician to Lower
Carboniferous.

Protaxocrinus Springer (Taxocrinus Ang. pars ; Lecanocrinus Billings). Arms
dichotomous. RA in form of R, below r.post.R. iBr few. IBr two. Type,
Taxocrinus ovalis Ang. Ordovician to Silurian; Gotland, Canada and the
United States. The geologically earliest known genus of the Flexibilia.

Gnorimocrinus W. and Sp. (Taxocrinus Ang. pars). RA rhombic, obliquely
below r.post.R. iBr few. IBr two (or three). Type, Taxocrinus expansus
Ang. Silurian; Gotland and North America, western Niagara area. (?)
Devonian ; Belgium.

Eutaxocrinus Springer. No RA. iBr variable. IBr two. Type, Taxo-
crinus affinis Müller. Silurian and Devonian to basal j^art of Lower Carboni-
ferous (Kinderhook) ; Gotland, Germany, North America.

206

ECHINODERMATA— PELMATOZOA

PHYLÜM IV

Taxocrinus interviedius
W. and Sp., showing
tegmen, Avith ambnlacra,
oraLs and open mouth be-
tween them (after Wachs-
muth and Springer).

Taxocrinus Phillips {Isocrinus Phill., 7ion von Meyer; Cladocrinus Austin 7ion
Ang. ; Euryalecrinus Austin). (Figs. 306, 307.) Like Eutaxocrinus, but with

primibrachs three. De-

vonian to summit of

Lower Carboniferous ;

England, Belgium and

North America.

Parichthyocrinus

Springer. No BA. iBr

few. IBr three. Eays

closely abutting above

iBr; arms interlocking

and infolding distally.

Has the habitus of

Ichthyocrinus, but with
the tube-like anal series of the Taxocrinidae
well developed. Lower Carboniferous ;
Upper Burlington and Keokuk ; (?) Goal
Measures ; Mississippian area. North Amer-
ica. Type, Ichthyocrinus nobilis (W. and Sp.).
Onychocrinus Lyon and Cass. {Oligocrinus
Springer). Arms heterotomous. Rays
widely divergent, produced into ten large,
rounded main trunks, bearing ramules. No
EA. iBr few or numerous. IBr three to
six, or more. Lower Carboniferous (Lower
Burlington to Kaskaskia) ; Mississippian
area, North America.

This is the culmination and most ex-
travagant development of the Taxocrinoid
type. With the exception of an imperfectly known species, probably of
this family, from the Lower Coal Measures, this and a depauperate species
of Taxocrinus are the last survivors of the Flexibilia.

Fig. 307.

Taxocrinus colletti White. Perfect crown.
Lower Carboniferous ; Crawfordsville, Ind.
Usually known in collections as T. meeki, or
T. multibracMahis (F. Si)ringer, original).

Incertae sedis.

Edriocrinus Hall. Superficially resembles Holopus, and its position is
doubtful. Has broad branching arms, with shallow ventral groove, short
brachials, and no pinnules. No stem ; basals fused into a rounded conical
mass, attached by a flattened surface when young, free in the adult. Radiais
five, with anal plate in same ränge. Lower Devonian (Helderbergian,
Oriskany) ; New York, Maryland, Tennessee.

Caleidocrinus Waagen and Jahn. Probably an Inadunate Crinoid, with
anal side not difFerentiated in dorsal cup. Silurian ; Bohemia.

Bhopalocrinus W. and Sp. Founded on a unique specimen described as
Taxocrinus gracilis Schnitze, but does not belong to this group. It has a
strongly plated anal tube reaching to height of the arms, and might be
described as a dicyclic Synbathocrinoid, wdth some interbrachial plates.
Middle Devonian ; Eifel.

CLASS III CRINOIDEA 207

Order 3. INADUNATA Wachsmuth and Springer.

Crinoidea in which the arms are free ahove the radials ; dorsal cup limited to
radials, hasals, in/rabasals when present, and anal plates ; no interradials oi' inier-
hrachials except at the posterior (anal) side, and brachials never normally incorporated
in the cup. All plates of the cup united hy dose suture. Mouth suh-tegminal.

Suborder 1. LARVIFORMIA Wachsmuth and Springer.

(Haplocrinacea Neumayr ; Larvata Jaekel pars).

Monocyclic {except Cupressocrinus). Calyx consisting only of hasals {with or
without infrahasals), radials, and orals, without anal plates, and usually without
visible ambulacra. All plates immovably united hy dose suture. Arms non-
pinnulate, simple and uniserial {exception, the doubtful Stephamcrinus). Silurian
to Carbon iferous.

The simplest form of the Crinoidea ; containing only plates found in the larval or very
young stage of existing types, without any supplementary plates whatever except such as
may belong to an arm-like anal tu^be. They are usually small, one genus, Allagecrinus,
alraost microscopic. Similar minute fornis may yet be found in the pre-Silurian forniations,
from which their absence thus far has been urged as an objection to the validity of the group,
considered as a phylogenetic representative of the larval stage. It must be admitted that its
limits are not very well defined, but the typical form is Haplocrinus.

Family 1. Stephanocrinidae Wachsmuth and Springer.

Monocyclic. Calyx cup-shaped, composed of three elongate hasals, five radials,
and five orals, with ambulacra. Radials deeply forked ; the pi'ongs formed hy the
margins of two contiguous radials extending upward between the arms, in spinelike
processes. First costals semilunate and resting within a horseshoe-like concavity near
the outer end of radial incisions. Tegmen consisting of the m'als, surrounding a
central space, which is roofed over by five greatly modified ambulacrals in form of
a flattened pyramid of triangulär plates ; with anchylosed covering plates extending
outward to the arm bases. Anal aperture between posterior mal and interradial
process. Arms with one short biserial trunJc to
the ray, giving off slender biserial, non-pinnulate
side arms from the outer Shoulder of each brachial.
Ordovician and Silurian.

Stephamcrinus Conrad {Bhombifera Barr.)
(Fig. 308). This unique genus is an inter-
mediate form, variously considered by different
authors as a Blastoid, a Cystid, or a Crinoid.
The presence of branching biserial arms, as fio. 308.

pointed out by Wachsmuth and Springer ^^.^^i;:;^;-^^^^^^^

makes it Unquestionably a CrinOld, althOUgh of calyx, natural size ; b, Snmmit aspect,
-, r i , • , V.;^!« ;<- enlarsred ; nroiecting upper ends of the

not normal f or the present group, m wtiicti it ^^^^^^^ ^roken away (after Haii).
is placed on account of its simple and primitive , , . ,

type of calyx. The forked radials, resemblance of the orals to the deltoids,
and the orientation of the small basal in the right anterior position instead
of the left anterior as in other Crinoids with three basals, are all characters
which indicate a close relationship to the Blastoids. Ordovician ; Bohemia.
Silurian ; North America.

208

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Family 2. Pisocrinidae Angelin.

Monocydk. Basais three to five ; radials five, very unequal, the riglit posterior
and right anterior Compound, left posterior and anterior usually
much the largest. Arms simple, uniserial and composed of long,
Silurian and Devonian.

Fisocrinus de Kon. (Fig. 309, A). Calyx small, globose.
B five, unequal, forming a triangle. Only the large an-
terior, and the left posterior radial resting upon the
basals ; one large plate, the radianal, serves as inferradial
for both right posterior and right anterior radials, and
also meets the basals. Anal or first tube-plate above line
of radials, foUowed by a tube. Articular facets of the
radials impressed between vertical partitions formed by
the lateral margins of the plates. Tegmen rarely pre-
served, but as observed by Wachsmuth and Springer in
P. pilula, consisting of five large symmetrica! orals, above
which rises a narrow anal tube. Arms long, and com-
posed of extremely elongate, cylindrical ossicles. Silurian ;
Gotland, Dudley, England and North America (Niagara
Group).

Triacrinus Münst. (Fig. 309, B). DifFers from the pre-
ceding in having but three B. Wachsmuth and Springer
have shown, however, that some of the Eifel specimens
occasionally have five B, thus leading to the inference that
the two forms are identical. Middle Devonian ; Eifel.

Calycanthocrinus Follmann. B three. Additional small
arm-bearing plates introduced between the radials. Lower
Devonian ; Germany.

Hypsocrinus Springer and Slocum. Calyx elongate.
Arm facets wide, shallow, concave, Alling a greater
part of radial margin.

Fig. 309.

A, Pisocrinus flagellifer
Ang. Silurian ; Gotland.
a, Perfect specimen, r.
posterior view ; b, Calyx
Seen from r. ant. side ; c,
From below. J/x (after
Angelin). B, Triacrinus
altus Müll. Devonian ; ß five
Gerolstein, Eifel. a
Calyx Seen from r. post
side ; b, From below i/i. -r> , t i i

K. ant. radial has in-
ferradial distinct from radianal. Middle
Devonian ; North America.

Family 3. Haplocrinidae Koemer.

MonocycUc. Calyx small, pyriform to
Basals five. Three of the radials
Compound, the others, left posterior and an-
terior, simple, and much the largest. Orals
large, triangulär to pentagonal, laterally in
contact. Arms five. Devonian.

Haplocrinus Steining. (Fig. 310).
Arm facets narrow, indented upon distal
face of radials. Arms small, simple,
uniserial, resting within deep grooves formed along the sides of the orals
Orals large, pentagonal, and laterally in contact ; the posterior one inter

H>^a

Fig. 310.

Haplocrirms inesjnliformis Goldf. Devonian ;
Gerolstein, Eifel. a, Calyx seen from one side ;
fo, öeen from above ; c, Seen from below ; d, Analysis
of calyx ; h, Basals ; x, the three unsymmetrical
plates situated between basals and radials ; r,
Radials ; br, First arm-ossicle ; o, Orals (anterior
side to the right).

CLAS« III CRINOIDEA 209

locking with the others, and pierced by a small anal opening. Mouth
subtegrainal ; column composed of thin joints. Not uncommon in the
Middle Devonian of the Eifel and Nassau ; sparse in the Upper Devonian of
North America.

Family 4. Allagecrinidae Etheridge and Carpenter.

Monocydic. Galyx very small, sometimes almost microscopic. Basais five, radials
five, of irregulär form and size. Some of the radials axillary and supporting iwo
arms ; others truncate and supporting hut one arm ; their articular facets provided
with transverse ridges and large muscle plates. Lower Carboniferous.

Allagecrinus E. and C. B completely anchylosed in the adult, and the
suture lines between the orals also disappearing with age. Stern largest next
to the calyx, rapidly tapering downward. Carboniferous (Kinderhook to
Goal Measures) ; Great Britain and North America.

Family 5. Synbathocrinidae Wachsmuth and Springer.

Monocydic. Calyx small, bowl-shaped, composed of three unequal or of five equal
basals, and five nearly equal radials. Tegmen formed by five small, asymmetrical
orals ; between these and the posterior radials arises a long anal tube, following an
anal, or first tube-plate, resting on the Shoulders of the posterior radials. Entire
Upper edges of the radials bevelled off so as to form straight articular facets, which
are furnished with well-developed transverse ridges. Arms five, simple ; column
round. Devonian and Garboniferous.

Phimocrinus Schnitze. The most primitive form of the family, having five
basals, and traces of transverse bisection of three radials as in Heterocrinus.
Devonian ; Europe.

Synbathocrinus Phill. (Lageniocrinus de Koninck). B three, unequal ; B five,
quadrangular or pentagonal. Anal tube long, slender, resting partly upon
the Shoulder of the right posterior radial ; it is composed of a longitudinal
series of strong plates with a crescentic section on the dorsal side, and small
plates re.sembling perisome on the opposite side. Arms long, uniserial, and
composed of comparatively thick ossicles with sharp angular edges. Devonian
and Garboniferous ; Great Britain and North America.

Stylocrinus Sandb. Distinguished from Synbathocrinus mainly by the
character of the radial facets, which are directed obliquely downward and
inward, instead of upward and outward. Devonian ; Europe.

Stortingocrinus Schnitze. Devonian.

Family 6. Oupressocrinidae d'Orbigiiy.

Dicyclic. Calyx large, basin-shaped, composed of five equal basals and five equal
radials ; the basals enclosing a central pentagonal plate, which represents five anchylosed
infrabasals. Upper faces of radials broad, truncate, and forming an even hoitzontal
line. Costals compressed, fiange-shaped. A peculiar annular structure, the so-called
'' consolidating apparatus" situated onthe upper interior margin of the calyx between
the arm-bases. Arms five, simple, uniserial and closely folded ; they are composed of
broad, thick plates, united by dose sutures, and are iraversed by a well-developed
VOL. I ^

210

ECHINODERMATA— PELMATOZOA

PHYLUM IV

dorsal canal. Column pierced hy a large axial and three, four or five peripheral
canals. Devonian. Eepresented hy a single genus, which probably does not

belong to this suborder, but
whose systematic affinities have
not been satisfactorily deter-
mined.

Cupressocrinns Goldf. (Fig.
311). Tegmen flat ; the greater
part of it occupied by the so-
called consolidating apparatus.
This is composed of five
petaloid, horizontally trun-
cated interradial pieces, which
are laterally in contact, and
enclose a large, central open
Space ; tliese are probably
modified orals, and served in
part for the attachment of
muscles. Five round aper-
tiires, through which the
ambulacra entered the calyx,
perforate the divisions between
the consolidating plates ; one
of the latter is pierced by the
anal opening (Fig. 311, e).
Arms provided with a wide
and deep ventral furrow, lined
on both sides with jointed,
closely abutting appendages ; of these there are several to each arm-plate,
thus showing that they are different from true pinnules. Middle Devonian ;
Eifel, Harz, Nassau and Westphalia.

Eifel.

' Fig. 311,

Cupressocrinus crassua Goldf. Devonian ; Gerolstein
a, Perfect specimen, natural size ; b, Cross-section of column ;
c, Fused infrabasals ; d, Section through the foldeil-up arms,
showing plated covering of ambulacral furrows, and dorsal canals
perforating the ossicles ; e, Interior of calyx from above, showing
the live consolidating jjlates, the lowermost containing the anal
opening ; /, Radial pierced by ambulacral opening, but with wall
covering the same partly broken away ; g, Side-view of radial in
which the ring-like covering of the ambulacral opening is pre-
served intact.

Suborder 2. FISTULATA Wachsmutli and Springer.

Tegmen composed of numerous plates, consisting either of orals with supra-tegminal
ambulacra passing over their edges, and interamhulacra, or of more or less undiffer-
entiated plates without identifiable orals or amhulacrals. Posterior interamhulacrum
usually more or less extended into a strongly plated anal tuhe or ventral sac. Arms
jpinnulate or non-pinnulate, usually uniserial, but biserial in some later genera. Base
monocyclic or dicyclic. Ordovician to Trias.

The Fistulata are characterised, in their typical genera, by a great develoj)ment of the
posterior interradius, which is extended upward in the form of an anal tube or a ventral sac. In
the forrner case the anus is at the distal end ; orals are more or less represented in the tegmen,
the posterior one being often perforated (madreporüe). In the latter the extension involves
alraost the entire tegmen ; the plates of the sac are often perforated by small, round or slit-
like pores (respiratory pores) ; all traces of orals are lost ; and a curious reversal takes place
in the position of the anal opening, which, instead of being at the distal end, or posterior, is
on the anterior side of the sac, either at the base, or part way up, sometimes through a
lateral spout.

In some of the early families the radials are transversely bisected in one, two, or three
rays, producing Compound radials, as in some Larviformia. When three radials are thus
Compound they are usually in the right posterior, and right and left anterior rays ; but when
there is only one, it is constantly that to the right of the anal area, the right posterior. The

CLASS III CRINOIDEA 211

latter condition is the longest lived, persisting to late in the Carboniferous, while the former
did not survive the Devonian, and was chiefly confined among the Fistulata to Ordovician forms.
The superradial, or ariu-bearing portion of the plate, is in sonie earlier forms nmch the
sinallest part, resting on the right Shoulder of the inferradial, or lower portion ; in others it
is nearer equal to, and directly in line with the inferradial ; in later forms it is pushed to the
right by the gradual increase in width of the posterior interradius or ventral sac.

The inferradial, because of its supporting the sac, as is usually the case among the later
forms, has received the name of radianal. Primitively, however, as was shown first by
Wachsmuth and Springer, and subsequently by Carpenter and Bather, the radianal represents
the lower portion of the right posterior radial ; and it has, therefore, nothing in common
with the anal plate, which is a specialised interradial. The phases exhibited by the radianal
in its progressive structural development furnish excellent differential characters. From its
])riniitive radial position directly und er the right posterior ray, it shifts upward to a left
oblique position, and is then eliminated in the later Carboniferous, substantially parallel to its
course in the Flexibilia.

Under the Fistulata are included the foUowing families ; Hyhocrinidac, Meter ocrinidae,
A7iomaloerinidae, Calceocrinidae, Catillocrinidae, Belemnocrinidae, comprising the monocyclic
forms ; and Dendrocrinidae, Crotalocrinidae, Cyathocrinidae, with subfamilies Carahocrininae,
Gaster ocominae and Gyathocrininae ; Botry ocrinidae ; Poieriocrinidae, with subfamilies
Poteriocrininae, Graphiocrininae and Encrininae, comprising the dicyclic forms.

Family 1. Hybocrinidae Zittel.

Monocyclic ; basals five. Eadials large ; the right posterior radial Compound ;
the inferradial almost as large as the other radials, supporting on its right Shoulder
the superradial, and on its left the first plate of the tube, or anal plate, which does not
enter the dorsal cup. Ventral tube or sac in its most- primitive form, extending hut
little above the rest of the tegmen ; superradial very small, sometimes undeveloped.
Arm facet small, round, less than width of radial; arms simple, uniserial, mm-
pinnulate. Orals large, with ambulacra resting on their adjacent edges ; posterior
one pierced by hydropore. Lower Ordovician.

Hybocystis Wetherby. Three of the rays bearing primitive arms composed
of but few joints, with ambulacral furrows passing from the ventral to the dorsal
side of the arms, and continued upon the surface of the R. The two other
rays are without arms, and the ambulacra follow the surface of the calyx, and
may pass down so far as to enter the basals. Anus through a
valvulär pyramid surrounded by integument of small plates
between posterior oral and distal edge of the anal plate. Stem
round. Ordovician (Trenton) ; Kentucky and Canada.

Hybocrinus Billings. Similar to Hybocystis, but with five
regulär arms, and no recurrent ambulacra. Anus either
through a valvulär pyramid or simple opening. Ordovician
(Trenton) ; Canada and Kentucky. ^^°' ^^^'

Hoplocrinus Grewingk (Fig. 312). Like the preceding, ^Z'^^G^ZinÜ:
but with the inferradial sloping only to the right, and sup- ordo^^ijian^^ ^^st.
porting a small, trigonal superradial. On the left it supports seen irrom the anai
small plates of the ventral sac, without the Intervention of a ^if^k).^*^^' °'"
larger plate. Ordovician ; St. Petersburg.

Baerocrinus Volborth. Like Hoplocrinus, but the right posterior and the
anterior ray without arms; apparently inferradials only are developed.
Ordovician ; St. Petersburg.

Family 2. Heterocrinidae Zittel.

Monocyclic ; basals five. Galyx usually elongate conical. One or mwe of the
radials Compound. The superradial of the right posterior ray supporting to the

212 ECHINODERMATA— PELMATOZOA phylum iv

rigU the primary brachials, and to the left an anal tube or sac ; the first plate of
this, corresponding to the anal x, may he entirely above the level of the radials, or, as
usually, may slightly indent their upper corners at the posterior interradial suture ;
but never fully enters the dorsal cup. Arms non-pinnulafe, uniserial, dichotomous or
heterotomous. Eadiäl facets usually wide and straight. Tegmen not well known.
Ordovician and Silurian.

Heterocrinus Hall (Stenocrinus W. and Sp.). Crown subcylindrical, calyx
small. Three radials transversely, more or less equally bisected, or Com-
pound ; these being, in addition to the right posterior, the right and left
anterior, or sometimes the anterior in place of the latter. Anal tube delicate
and straight; first tube-plate resting on the Shoulders of both posterior
radials, but not further entering the cup. Arms irregularly dichotomous,
somewhat divergent. Stern pentagonal, quinquepartite, with interradial
sutures. Ordovician ; North America.

Ohiocrinus W. and Sp. Calyx and stem as in Heterocrinus. Arms hetero-
tomous, having ten main branches not in close contact, and somewhat sinuous,
with ramules which usually brauch again. Ventral sac large, and usually
convoluted. Ordovician ; North America.

Eäenocrinus S. A. Miller {Heterocrinus W. and Sp., non Hall). Calyx about
as in the preceding. Arms heterotomous, with ten main branches, straight,
rather closely abutting, composed of a continuous series of syzygies of two
plates each, the epizygals giving off ramules. Stem round, tripartite.
Ordovician ; North America.

locrinus Hall. Only one radial Compound, the right posterior, the lower
part of which is of about the same size as the other radials, which are all large.
The superradial is short, resembling an axillary brachial, supporting on its
right Shoulder an arm and on the left a series of plates f orming the arm-like
dorsal ridge of a strong anal tube or sac, of complicated structure ; first tube
plate entirely above the level of radials, and not entering the dorsal cup at all.
Arms dichotomous, branching frequently. Stem pentagonal, quinquepartite,
with interradial sutures, the pentameres radially disposed. Ordovician ;
North America.

Herpetocrinus Salter (Ophiocrinus Charlesw.; Myelodactylus and (?) Brachio-
crinus Hall). A specialised form with crown of the locrinoid type, habitually
enclosed by the coiled stem, whose structure is modified accordingly. The
crown is rarely seen, being beut backward, and usually closely enveloped by
the stem, which is then coiled around it in the opposite direction. One ray is
dwarfed, either not branching or entirely aborted. The right posterior radial
alone is Compound, the superradial supporting the series of tube-plates entirely
above the level of the radials, as in locrinus. Anal tube long and narrow,
composed of a series of heavy plates resembling brachials dorsally, with
perisome on the other side. Arms more or less irregularly dichotomous. The
stem could be tightly coiled, or uncoiled exposing the crown ; but the latter
condition is rarely found in the fossils. Resulting from this the stem has lost
its cylindrical form, being more or less concave at one side, with its columnals
crescentric in section, and bearing on the horns of the crescents two longitudinal
rows of strong cirri. The remarkable resemblance of the coiled cirriferous
stem to a pinnulate arm has misled many students, for the crown is usually
concealed. Silurian ; North America and Europe.

CLASS III CRINOIDEA 213

Family 3. Anomalocrinidae Wachsmuth and Springer.
Monocyclic ; basalsfive. Calyx hroadly rotund in form. Tegmen strong, composed
chieflg of large modified amhulacrals and interamMacrals, extending posteriorly into
a large expanding anal tube or sac. Radiais very large, two of them—the right
posterior and left antero-lateral— Compound, all of them laterally in contad ; inf erradial
rarely larger tlian the superradial; the lower tuhe-plate, or anal x, resting in the
angle formed hy the superradial to the right, and the upper end of the simple radial
to the left, hut not entering the cup. Radial facets circular and very small. Arms
relatively slender, uniserial, and bifurcating several times at somewhat irregulär
intervals. Small armlets given off from each arm-joint on one side only, alter nately
in the successive dichotoms. Column strong, round, attached by an encrusting root.
Ordovician.

Anomalocrinus M. and W. (Ataxocrinus Lyon). The only genus of the
family. The Statements heretofore current that one radial is often longi-
tudinally bisected, and that the.re is a small supplementary piece within
the basal ring, are based on abnormal specimens only. Ordovician ; North
America.

Family 4. Cremacrinidae Ulrich (Galceocrinidae M. and W.).

Monocyclic Inadunata, in which a bilateral symmetry along the left anterior
radius and right posterior interradius has been superinduced in conjunction with
bending of the crown on the stem in such a way that the right posterior interray lies
along the stem ; with the left anterior, right posterior and right anterior radials Com-
pound ; with anal x (IRA) shifted over the right posterior radius, usually into the
right posterior interradius, and supporting a massive tube ; with three, rarely four,
arms, of which two are as a rule peculiarly modified and bear armlets or pinnules.
(From Bather, " The Crinoidea of Gotland.") Ordovician to Lower Carbon-
iferous.

Cremacrinus Ulr. (Castocrinus Ringueb.). B distinct, all entering into the
articular surface of the stem. The right posterior, and right anterior super-
radials joined by ill-defined close suture, each abutting with one side on the
adjacent large simple R. The lower plate of the tube supported by the
right posterior superradial only, while the right anterior superradial supports
the first brachial of the right anterior arm. The right posterior and right
anterior superradials separated from one another, and also from the ventral
tube, by the right posterior and right anterior R. Arms four. Ordovician ;
North America. Type, C. punctatus Ulr.

Euchirocrinus Meek and Worthen (Cheirocrinus Hall, wow Eichwald ; Pro-
clivocrinus Ringueb.). B unfused, or perhaps sometimes the left posterior fused
with the left anterior one. The right posterior and right anterior super-
radials fused in a T-shaped piece, which abuts with either wing on the
Corners of the large simple R. The right posterior and right anterior
inferradials separated from one another and from the tube by the T-piece ;
tube supported by the whole Upper margin of the latter. Arms three.
Silurian ; North America. Type, E. chrysalis (Hall).

Deltacrinus Ulrich {Cheirocrinus Salter, nom. nudum ; Calceocrinus Hall em.
Ringueberg). Left posterior basal fused with the left anterior one ; the

214 ECHINODEEMATA— PELMATOZOA phylum iv

fused plates very rarely entering the stem articulation. The posterior and
right anterior basals bounded for some distance by the large R. T-plate
separated from the large simple R by the right posterior and right anterior
radials ; it is low, wide, and occasionally very small. Tube supported by
the T-piece and the two inferradials to the right, but not touching the two
large simple radials. Arms three. Silurian and Devonian ; Europe and
America. Type, D. clarus (Hall).

Halysiocrinus Ulrich em. Bather. B as in the preceding, but the fused
posterior and right anterior ones never entering into the stem articulation.
T-piece either obsolete or concealed between the right posterior and right
anterior inferradials, and the two large radials in the stem articulation.
Tube supported by the inferradials to the right, which are in contact, and
abutting by its lower corners on the two large simple R. Arms three. Bur-
lington and Keokuk Groups ; Mississippi Valley. Type, H. dadylus (Hall).

Family 5. Oatillocrinidae Wachsmuth and Springer.

Base monocyclic ; dorsal cup low and broad ; general symmetry of the calyx
greatly disturbed. Basals more or less fused, their number doubtful ; radials still
more irregulär bofh in form and in size. Most of the arms given off from two of
the radials, which are sometimes five or six times larger than the other three ; they
are simple, qnadrangular, non-pinnulate, and rest within small sockets directly upon
the radials. Anal plates wanting. Anal tube heavy, composed of very long,
longitudinally arranged crescent-shaped pieces, and supported directly by the radials ;
it exhibits a wide open groove along the anterior side, which probably was covered by
small delicate plates. Devonian and Lower Carboniferous.

Mycocrinus Schultze. Dorsal cup mushroom-shaped. Plates massive,
irregulär, and without ornamentation. B two (according to Schultze), one of
them twice as large as the other, and the two forming a knob-like body. R
five, their inner edges resting upon the angular margin of the basal disk ; they
spread broadly outward from the B, extending far beyond them. The two
larger R separated at the posterior side by two equal smaller plates ; and at
the anterior side by a single plate having a quite narrow upper face. M.
boletus Schultze has apparently fif teen arms, their structure unknown. Middle
Devonian ; Eifel. ,

Catillocrinus Shumard ex Troost (Nematocrinus M. and W.). Crown, when
the arms are closed, elongate, cylindrical. Dorsal cup basin-shaped, concave at
the base, truncate at its upper margin. Basal disk small. R five; those
of the two antero-lateral rays fully six times as wide as the others, and
expanding upwards, so as to encroach upon the smaller ones. The larger R
Support each twelve to sixteen arms ; the smaller ones rarely more than one
each. Lower Carboniferous ; North America.

Family 6. Belemnocrinidae Wachsmuth and Springer.

Base monocyclic ; cylindrical to ovoid. B is composed of five large, elongate,
irregulär pieces, and is pierced by a small canal which widens slightly at the upper
end. Radials five, quadrangidar, and separated posteriorly by a narrow anal.
Ventral sac large, composed of hexagonal plates, the angles of which are perforated.

CLASS III CRINOIDEA 215

Arms long, giving off armlets alternately at intervals. Column round or pentaganal ;
in the latter case having its angles radially directed, and cirri which are interradial.
Lower Carboniferous.

Belemnocrinus White {Missouricrinus S. A. Miller). The only genus, very
rare. Burlington Group ; Mississippian area, North America.

Family 7. Dendrocrinidae Bather.

Dicydic. Strudure of tegmen not well kiiown, prohahly composed chiefly of
undifferentiated plates, more or less extended into a tube or sac, sometimes resemhling
an arm proximally, and usually with anal opening at the distal end. Arms uniserial^
either dichotomous and stridly non-pinnulate, or heteroiomous with main rami hearing
lateral ramules tending to incipient pinnulation. Loose, irregulär interhrachials
occasionally present in lower pari of interradius in some genera. Radianal in
primitive position in form of radial under the right posterior ray. Radial facets
Wide or narrow ; mode of union with proximal bradiials not well knovm, hui
prohahly Inj modified or imperfed muscidar articulation. Infrahasals five. Stem
usually round, sometimes pentagonal and quinquepartite. Ordovician and Silurian.

This assemblage of early genera raay be considered as a sort of composite family, in which
are embraced a nimiber of characters which later became fixed as valid family criteria. They
are all primitive in the position of the radianal, and therein differ from all later Fistulata.
The presence of interhrachials irregularly in some genera, e.g. Cupulocrinus and Oitawacrinus,
which are foreign to the Inadunata, indicates a close relation to the Flexibilia ; and as
Springer has shown, there are good reasons for considering the first of these genera as very
close to the ancestral type of the two orders.

Merocrinus Walcott. Arms dichotomous, branching. Radial facets wide,
shallow, nearly straight. No anal plate in line with radials. Anal tube at
the base resembling an arm branching from the left side of the axillary right
posterior superradial. The genus might be considered as a dicyclic locrinus.
Ordovician ; North America and England.

Cupulocrinus d'Orb. (Scyphocrinus Hall, non Zenker). Arms and radial
facets about as in the preceding. Large anal x in line with radials, truncate
above, supporting a large tapering anal tube, with a median row of large
plates dorsally, bordered by perisome, rising only about half the height of
the arms. Small irregulär interhrachials often present in primary axils.
Ordovician ; Canada and Kentucky.

Thenarocrinus Bather. Dorsal cup similar to the preceding, but radianal
slightly to left and touching infrabasals. Anal tube large and long, composed
of transversely folded plates, without median ridge or perisome. Silurian ;
England.

Dendrocrinus Hall. Radial facets narrow and semicircular. Arms dicho-
tomous, branching many times, and very slender. Anal x in line with radials,
angular above. Anal tube wide, long, composed of hexagonal plates in
vertical parallel columns. Ordovician and Silurian ; North America.

Ottawacrinus W. R. Billings. Arms heterotomous, with ten main branches,
bearing lateral ramules, which may subdivide, or may approach the pinnulate
stage. Anal x in line with radials ; tube wide, rising the füll height of the
arms. Radial facets wide and nearly straight. Ordovician ; Canada.

Gothocrinus Bather. Similar to preceding, but with radial facets narrow
and curved, and shorter ramules. Silurian ; Gotland.

216

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Family 8, Crotalocrinidae Angelin (emend. Wachsm. and Springer),

Dicydic. Infrahasals five. Calyx resembling that of Cyathocrinus, hut with
lower brachials more or less rigidly incorporated into dorsal cup by lateral contact
among themselves, with the radials, and with tegmen plates. Tegmen composed of
numerous rigid plates, chiefly modified ambulacrals and interambulacrals, with orals
more or less exposed, and alternating covering plates often very definitely arranged.
No interradials except at anal side. No radianal ; anal x in line with radials ;
anus directly through the tegmen or at the end of a short protuberance. Arms non-
uniserial. Axial canal in arms distind. Stem large, round. Silurian.

The systematic position of this family is uncertain. The usual rigid incorporation of the
lower brachials in the dorsal cup by inclusion within the radial facet, and by eonnection
with solid tegmen, analogous to what is seen in camerate genora like Marsipocrinus and
Pterotocrinus, points to a eonnection with the Camerata, as claimed by Wachsmuth and
Springer. This feature is subject to considerable Variation, being usually not so pronounced
in young specimens, in which the brachials are more nearly isolated. On the other band the
resemblance in habitus of calyx to the Inadunata, as Bather has suggested, is equally
striking ; while the absence of pinnules in the arms seems to this reviser a strong reason
in favour of Inadunate affinities, The structure of the tegmen would place it close to the
Cyathocrinidae.

Enallocrinus d'Orb. Infrabasals five. Anal plate one, not always
truncating the posterior basal. Radial facets wide and shallow, bearing

Fig. 313.
A, Crotalocrlnv.ii pulcTier Hising. {Anfhocrinus loveni Müller). Silurian ; Gotland. Crown with folded arms.
7>, Portion" of stem. C, Cross-section of four contiguous arm-ossicles of the network. D, Dorsal aspect of
arm-plates, showing their intimate union ; those above the two rows ttgured have been broken away so as to
expose the side-pieces and covering plates of the ambnlacral furrows. E, Tegmen of C. rugosus Miller (after
Angelin).

directly on their distal edge a triangulär primibrach and one to three further
Orders of brachials at each side. Arms long, frequently dichotomising, and
becoming free above the first few brachials. Silurian ; Gotland, England.

Crotalocrinus Austin (Anthocrinus Müller) (Fig. 313). Similar to Enallo-
crinus, but arm-branches united by lateral processes from each brachial.

CLASS III CRINOIDEA 217

forming a flexible network, which may be continuous all arouiul the crown
or be divided into five broad, reticulate, fan-like fronds. In the calyx of
some young specimens the radial facet is narrow, semicircular, evidently
beariiig the brachials in the usual succession. Axial canal distinct in arms
but not perforating radials, which are thin. Stern terminating in a thick,
branching root. Silurian ; Gotland, England and North America.

Petalocrinus Weller, from the Silurian of North America and Gotland,
with its arms united by lateral fusion into five ponderous fans, has some
resemblance to Crotalocrinus, but seems to have no anal plate. It may be
nearer to the Gasterocrinidae.

Family 9. Cyathocrinidae Roemer (emend. Wachsm. and Springer).^

DkycUc. Tegmen strong, composed of rather large orals more or less exposed^
surrounding but not covering the peristome ; rigid amhulacrals supported on their
adjacent edges, meeting dbove the oral centre and often greatly modified ; and inter-
amhulacrals, which often encroach upon and ohscure the other plates. Posterior oral
frequently a madreporite. Anus located either in the posterior interamhidacrum
directly through the tegmen, or at the distal end of a plated anal tuhe, or dorsally
through the side of the cup. Arms non-pinnulate. Radial facet s usually semi-
circular, less than the width of the radial. Union of radials with proximal brachials
usually by incomplete articulation upon undifferentiated Joint faces, with concavo-
convex surfaces, without true transverse ridge, though with occasional traces of it.
Infrabasals usually five. Stem usually round.

Subfamily A. Carabocrininae.

Arms usually dichotomous ; heterotomous in some of the later genera. Radianal
obliquely to left of right posterior radial. Anal x present. Posterior oral usually
a madreporite. Infrabasals five. Stem usually round. Ordovician to Lower
Carboniferous.

Carabocrinus Billings. RA completely separating BB, and having a
supplemental plate intercalated below it, touching IBB. Anal x large, in
line with radials. Anus directly through the teg-
men. Arms branching. Posterior oral pierced by
hydropore. Ordovician (Trenton) ; Canada and
Kentucky.

Strophocrinus Sardeson. Ordovician ; Minnesota.

Porocrinus Billings (Fig. 314). RA smaller, rhom-
boidal, not separating BB. Arms ten, unbranched.
Calyx plates deeply folded at the angles, but folds
do not cross the sutures or form true pore-rhombs. Fi«. 3i4.

Anus in a slight protuberance. Referred by some ord^^r;" mTa^t" cÄ
authors to the Cystids. Ordovician: Canada, Ken- Nat. size (aoer Biiiings) ; h,p.

, . T-- . "^ ' radiatus Beyr, Ordovician ; 8t.

tUCky and KuSSia. Petersburg. Calyx plates show-

Palaeocrinus Billings. RA as in preceding genus. i^;,*!/^^;!; ilVS'ßeyrSr
Arms branching several times ; slender, rising from
a small curved facet. Anal tube small. Ordovician ; Canada and Kentucky.

Homocrinus Hall. RA as in preceding. Arms branching, strong ; radial
facets wider than usual in the family, nearly straight. Anal tube large,

218

ECHINODERMATA— PELMATOZOA

THYLUM IV

Silurian and Devonian ; North America
Similar to Homocrinus, but with

composed of numerous small plates.

and Europe.

Bactrocrinus Schnur, in Steininger.

narrower facets. Devonian ; Germany.

Euspirocrinus Angelin (Fig. 267). Dorsal cup conical. EA small, pent-

agonal. Anal x rising above level of BB, with a plate of the anal tube

partly in the cup beside it. Anus at the end of a strong tube. Arms

dichotomous, branching. Ordovician ; Canada. Silurian ; Gotland.

Closterocrinus and Ampheristocrinus Hall. Imperfectly known. Silurian ;

North America.

Sphaerocrinus Roemer. Dorsal cup globose. BA larger ; x not rising

above BB. Anus directly through the tegmen. Axial canal separate from

ventral groove in radials and brachials. Arms
unknown. Devonian ; Germany and England.

Parisocrinus W. and Sp. (Fig. 315, which is
reversed). Dorsal cup elongate. BA large ; x not
rising above level of BB. Anal tube very broad
and long, rising to height of the arms, composed
of hexagonal plates and profusely perforated with
pores at the sides of the plates ; anus at the distal
end, surrounded by a circlet of strong plates.
Arms dichotomous, branching frequently. Devon-
ian to Lower Carboniferous (Keokuk) ; Germany,
England and North America.

from the anal side, showing ventral Vasocfinus Lyou. Calyx broad, hemispherical.

sac and one arm which is recuper- . t_ - ^ -j.!. x • • r, •

ated and abnormaiiy small (right Arms heterotomous, With teu mam rami bearmg
'^.^^^:^S^tS^^i^^. strong ramules which may brauch again ; therami

divergent, and not in contact above the axillary
Anal tube broad below, rather short and tapering.
not divided, and with very small axial canal.
Devonian to Lower Carboniferous (Keokuk) ; North America.

Barycrinus Wachsmuth. Calyx and arms as in Vasocrinus, but rami and
ramules usually heavier. Rami in contact by one or two brachials above the
axillary. BA small, quadrangular, frequently entirely wanting, in which
case a small specimen cannot certainly be distinguished from Cyathocrinus by
the calyx alone, although in general the arm facets are larger, and directed
upward more than in that genus. Anal tube broad and short. Stem un-
usually large, quinquepartite, with a very wide axial canal. Specimens
attaining a large size. Lower Carboniferous (Lower Burlington to Warsaw) ;
Mississippian area. North America.

Goniacrinus Miller and Gurley. Calyx small, elongate. Arms hetero-
tomous, with small ramules borne on ten main branches ; facets directed
upward. BA small. Anal x in line with radials, followed by others in a
prominent series between the posterior rays, passing into a tube. Lower
Carboniferous ; North America.

Atelestocrinus W. and Sp. Calyx elongate. Arms heterotomous, with
delicate ramules. BA of good size. Anterior ray is not arm-bearing.
Lower Carboniferous (Burlington) ; Mississippian area. North America.

Fig. 315.

Parisocrinus eurtus Müll
ian ; Schönecken, Eifel.

Devon -
a, Calyx

primibrach. BA small.
Stem of moderate size,

CLASs III CRINOIDEA 219

Subfamily B. Gasterocominae.

Cyathocrinidae with no radianal. Anus through the dorsal cup, below level of
rm hases. Arms strong, round; facet horse-shoe shaped, direded outward, arid
ierced hy a distinct axial canal. Infrabasals usually undivided, exceptionally three

or five. Orals largely covered hy modified ambulacrals ; posterior one a madreporite.

Stern round, with central axial canal surrounded hy three or more peripheral canals.

A strongly specialised subfamily of short life, being limited, except for
Hypocrinus, to the Middle Devonian.

Gasterocoma Goldfuss {Epactocrinus and Ceramocrinus Job. Müller) (Fig.
316). Infrabasal disk sraal], undivided. Anal opening lateral through the
dorsal cup, just above the posterior
basal, at the angle formed by that
plate and the two posterior radials,
usually fringed with a ring of small
plates ; one or more plates may lie
above it, connecting with the tegmen,
or these may be absent, leaving the
radials closely abutting. Axial open- fio. sie.

ing in infrabasal disk COmpleX, COnsist- Gasterocoma antlqua Goldf. Devonian ; Prüm,
r j. 1 j ii. r n Bifel. a, Calyx seen from one side ; h, Anal aspect ;

ing ot a central and three, f our or üve c, Tegmen. 2/j (after l. scimitze).
peripheral canals, continued down into

the column. Stem round, with strongly alternating joints, the thin proximal
columnal more or less quadrangular. Arms not certainly known, but
divergent, directed outward, probably round and simple, with short brachials.
Middle Devonian ; Eifel. The remaining genera mostly agree with this in
the essential structures of the calyx.

Schultzicrinus Springer. Arms directed upward, simple, broad, abutting,
with long brachials following one very short primibrach. Devonian
(Onondaga) ; New York.

Arachnocrinus Meek and Worthen. Arms branching" more than once.
Devonian (Onondaga) ; New York and Kentucky.

Nanocrinus Joh. Müller. Only four arm-bearing radials. Arms unknown.
Scoliocrinus Jaekel. Three arm-bearing radials. Middle Devonian ; Eifel.

Achradocrinus Schnitze. Infrabasals five, not fused. Axial canal simple,
without peripherals. Middle Devonian ; Eifel.

Hypocrinus Beyrich may belong here. Resembling Achradocrinus, but
with three infrabasals. Ciassed by authors as a Cystid. Permian ; Timor.

Myrtillocrinus Sandb. Has the general facies of this family ; undivided
infrabasal disk, a central axial with three or four peripheral canals ; round,
simple arms. But there are five large symmetrical orals in a pyramid con-
stituting almost the entire tegmen, leaving only small interoral grooves for
the ambulacra, — not preserved in any specimens. Anal opening not known,
probably minute, and obliterated by Infiltration of calcareous matter in
fossilising. Middle Devonian ; Eifel and New York.

Subfamily C. Cyathocrininae.

Cyathocrinidae with no radianal. Anus at the ventral side, usually at the end
of a strong tuhe. Anal x, when pi-esent, in line with radials. Arms usually

220

ECHINODERMATA— PELMATOZOA

PHYLUM IV

dichotomous, and freely branching. Posterior oral usually a madreporite ; other
orals often largely hidden hy encroaching tegmenal plates. Infrahasals five, excep-
tionally tliree. Stern usually round. Silurian to Lower Carbon iferous.

Gissocrinus Ang. (Fig. 317). IB three. Anal tube compressed, its plates
short, wide and folded. Distal margin of brachials usually project. Silurian ;
Gotland, England and North America.

Cyathocrinus Miller (Figs. 318, 319). Infrabasals five. Anal tube short

a, Gissocrimis arthriticus Phill. Silurian ; Got-
land. Crown of the natural size (after Angelin) ;
h, G. punctuosus Ang. Tegmen ; c, Ventral and
lateral aspect of the arms (enlarged).

m-^CT-^tTXTX:

Fio. 318.

Cyatlwcrlmis. Analysis of dorsal
cup (after Bather).

Fig. 319.

a, Cyathocrinus longimanus Ang. Silurian ;
Gotland. Crown of the natural size (after
Angelin) ; />, C. ramosus Ang. Portion of an
arm viewed from the side ; c, Ventral aspect of
same (enlarged); d, C. malvaceus Hall. Lower
Carboniferous ; Burlington, Iowa. Tegmen
perfectly preserved ; e, The same after removal
of the covering pieces and orals (after Meek
and Worthen).

and rounded, or long with a valvulär pyramid at distal end ; its plates more
or less hexagonal, not transversely elongate, nor much folded. Arms branch-
ing as many as five to seven times. Kadial facets horse-shoe shaped, directed
outward, with occasional incipient transverse ridge. Ambulacral covering
plates well developed, regularly alternating, or modified so as to resemble
budding pinnules. Stem round, streng, short, apparently without cirri. A
well-known and widely distributed genus, occurring from the Silurian to
Lower Carboniferous (Warsaw) ; Europe and America.

Mastigocrinus Bather. Like Cyathocrinus in the structure of the calyx.

CLASSjii CEINOIDEA 221

but with longer arms and anal tube, which is more like that of the Poterio-
crinidae, probably with lateral opening. Stern quinquepartite. Silurian ;
England.

Streptocrinus W. and Sp. {Ophiocrinus Ang. uon Salter), Calyx like that of
Cyathocrinus. Anal tube coiled, opening probably at the side. Arms branching,
coiled inward, with peculiar processes called " false pinnules." Not well
understood. Silurian ; Gotland.

Lecythocrinus Joh. Müller {Taxocrinus briareus Schultze) (Fig. 320). Arms
branching repeatedly. Anal tube long, with strong
plates in longitudinal columns. Stem subquadrangular,
with central and four peripheral canals. Infrabasals
small, unknown, may be undivided. Middle Devonian ;
Eifel.

Lophocrinus Meyer (Carduocrinus Koenen). Onlv
one arm to the ray, with small ramuli alternating from
every second brachial. Anal tube of delicate plates.
Upper Carboniferous ; Germany.

Codiacrinus Schultze. No anal plate in dorsal cup.
Infrabasals three. Radial facets directed obliquely
outward, and with a separate dorsal canal. Arms
dichotomous, short and slightly developed. Calyx
obconical, expanding upward. Middle Devonian ; Eifel. ^ .^

Lecythiocrinus White. Known only from the dorsal LecythocnZeman...Mnn.
cup, which has the same elements as the preceding. Devonian; Eifei. Restored
Arm facets directed upward, without dorsal canal.

Calyx bursiform, contracting at the arm bases. Upper Carboniferous ; North
America. •

Family 10. Botryocrinidae Batlier.

Dicydic. Tegmen composed of irregulär plates without definite orals or amhula-
crals, extended posteriorly into a ventral sac. Radianal oblique, not touching basals,
variable in size. Anal x in line with radials. Arms usually heterotomous, but
varying from ramuliferous to complete pinnulation. Articulation of first brachial an
radial imperfect, facets usually shallow, curved, not as wide as the radial. Silurian
and Devonian.

Botryocrinus Angelin (Sicyocrinus Ang.). EA small, quadrangular. Ventral
sac large, sometimes coiled, with anus below the coil. Arms heterotomous,
with two main rami bearing ramules which in some species reach the State of
pinnulation. Silurian and Devonian ; Gotland, England and North America.

Bhadinocrinus Jaekel. Calyx small, with very long ventral sac. Arms
relatively long and heavy, with ten main rami, bearing very small, branching
ramules at long intervals. Lower Devonian ; Germany.

Gastrocrinus Jaekel. Similar small calyx, with shorter sac, having longi-
tudinal columns of projecting plates. Arms long, with irregulär dichotomy.
Stem with whorls of cirri. Lower Devonian ; Germany.

Cosmocrinus Jaekel (Cyathocrinus ornatissimus Hall). EA large. Ventral
sac very large, reaching as high as the arms. Arms heterotomous, with ten
main trunks having several branches nearly as large, toward the inside of the
dichotom, which in turn bear regulär piiuiules. Radial facets rather wide.
Devonian (Portage) ; New York.

222

ECHINODERMATA— PELMATOZOA

PHYLÜM IV

Maragnicrinus Whijtfield. From the same locality and horizon as the
last; differing from it in having narrower arm facets, the arms regularly
dichotomous, branching once, and the rami bearing pinnules directly.

Family 11. Poteriocrinidae Eoemer (emend. Wachsm. and Springer).

Dicydic. Tegmen cornposed of undifferentiated plates, without identifiable orals
or amhulacrals ; more or less extended into a ventral sac, with anus helow the distal
end on the anterior side. Union of radials with first hrachials usualhj by
muscular articulation, upon straight facets as wide as the radial^ with fossae,
muscles and ligaments, and transverse ridge (exception in Poteriocrinus, a transition

form). Arms pinnulate, mostly dichotomous. Infra-
hasals five, exceptionally three, or coalesced into one.
Stern usually with cirri. Devonian to Permian.

Subfamily A. Poteriocrininae.

Radianal in oblique position. Anal x usually in
line with radials. Arms usually uniserial, tending to
biserial in later genera ; dichotomous or heterotomous.
Infrabasals usually five. Crown usually elongate,
expanding upward. Stern usually round, occasionally

pentagonal. Devonian to
Upper Carboniferous.

Poteriocrinus Miller.
Radial facet usually
curved, less than width
of B, with imperfect or
no transverse ridge.
Arms dichotomous,
branching frequently.
Ventral sac large and
long, usually rising be-
yond the arms. Stem
usually round, without
cirri, at least in upper
part. (?) Devonian and
Lower Carboniferous
(Keokuk) ; Europe and
North America.

Fig. 321.

Pachylocrinus unicus Hall. Lower
Carboniferous (Keokuk Group) ; Craw-
fordsville, Indiana. Natural size.

Fig. 322.

Pachylocrinus sp. Analysis of dorsal
cup. a, Anal x; ai, Riglit tube-plate ;
h, Basais ; ib, Infrabasals ; r, Right and
left posterior radials ; ra, Radianal.

The Devonian species

referred to this genus are

probably Parisocrinus ;

without the arms being

this cannot be

Fig. 323.
Pachylocrinus aequalis Hall.
Lower Carboniferous (Keokuk

Group); Crawfordsville, Ind.

Complete crown from posterior T»rp«prvprl
side, showing base of ventral sac U'^^^^y^^ ^

andmodeofarm-branching. certainly determined. The

genus lacks the complete
muscular articulation characteristic of the family, but is otherwise typical.

Pachylocrinus Wachsmuth and Springer {Scaphiocrinus auctt., non Hall =
Graphiocrinus ; Hydriocrinus Trautschold ; Abrotocrinus M. and G.) (Figs. 269,
321-3). Radial facets of this and all succeeding genera normal for the family.

CLARS III

CRINOIDEA

223

Calyx obconic to low cup-shaped. Arms branching two to four times, usually
more or less dichotomous, but in some species the inner arms of the dichotom
branch less frequently than the others, or remain simple, tending to the stage
of heterotomy seen in genera like Zeacrinus. Brachials cuneiform. Ventral
sac strong, usually enlarging distally. Stem
round or pentagonal, with cirri moderately devel-
oped. Carboniferous (Kinderhook to Upper Car-
boniferous) ; North America, Europe.

This is a widely distributed form known in collections
generally as Scaphiocrinus, a name wliich lapses because
the type species belongs to the previously established
GrapJiiocrinus. It is one of the longest lived Paleozoic
genera, represented by a large number of species, and is
highly typical for this family.

JFoodocrinus Koninck (1 Philocrinus Koninck)
(Fig. 324). Similar to preceding, but brachials
Short, quadrangular, arms usually heavier and
branching two to four times. Ventral sac stout
and apparently short. Stem short, tapering
distally, with scattered cirri. Lower Carbonifer-
ous; England.

Zeacrinus Hall. Crown more or less ovoid,
often short, rounded above and below. Arms
heterotomous, usually closely abutting and infold-
ing ; the two outer branches of each ray the
stoutest, giving off at intervals successive pin-
nulate arms of nearly equal size and reaching to
the same height, always to the inside of the
dichotom, usually unbranched, but they may
divide. Brachials short, quadrangular. Ventral
sac short, usually diminishing upward. Stem
round, bearing long cirri distally. Carboniferous
(Kinderhook) to Coal Measures ; Mississippian
area. North America.

Coeliocrinus White. Crown elongate, expand-
ing upward, with conical base. Arms as in
Zeacrinus, but not so closely abutting, and with
brachials cuneiform to interlocking. Ventral sac
inflated, balloon-shaped. Lower Carboniferous
(Burlington) ; Mississippian area. North America;
also Eussia.

Hydreionocrinus Koninck. Crown short, flat
above, with concave base. Arms branching some-
what as in Zeacrinus, but very short, not rising
above the expanded rim of the sac ; brachials
interlocking to fully biserial. Ventral sac mushroom-shaped. Upper part of
Lower Carboniferous (Kaskaskia) to Coal Measures ; Belgium, Britain and
North America.

Decadocrinus W. and Sp. Calyx depressed and base flat or concave. Arms
strictly isotomous, branching but once, giving two strong, pinnulate rami to
the ray, more or less angular or zig-zag. Brachials wedge-shaped, the longer

Fio. 324.

WocHlocrinvs macrodnc-
tylus (de Koninck). Per-
fect specinien from the
Lower CarlKiniferons of
Yorkshire (afl.-T <]>- Kon-
inck).

224

ECHINODERMATA— PELMATOZOA

PHYLüM IV

alternating sides bearing stout pinnules which are well separated, resembling
ramules. Ventral sac large, often almost as long as the arms. Stern rela-
tively small, sub-pentagonal, with rather plentiful cirri. Devonian and
Lower Carboniferous (Keokuk) ; North America and Europe.

■ Aulocrinus W. and Sp. Like the preceding, but ventral sac forked, with
anal opening from a lateral spout. Stern sharply pentagonal, with cirri.
Keokuk Limestone ; Indiana.

Scytalocrinus W. and Sp. Similar to Decadocrinus, but with calyx usually
elongate, more or less conical base, arms cylindrical, and pinnules closely
packed. Stem large, round, with cirri sparse and mostly distal. Devonian
and Carboniferous (Goal Measures) ; North America and Europe.

Agassizocrinus Shumard ex Troost MS. {Astylocrinus Roemer) (Fig. 325).

Calyx elongate, ovoid to pyriform. Arms ten, with pinnules closely packed,

a as in Scytalocrinus ; brachials quadrangular, becoming

cuneiform distally. Ventral sac unknown. Infrabasals

five, in mature specimens fusing to a rounded undivided

base. Stem entirely wanting, but probably present in

early stages. • Carboniferous (Kaskaskia to Coal Measures)

Mississippian area ; North America.

Cromyocrinus Trautsch. (Figs. 326,
327). Calyx rounded below, but not
concave. IB large, visible exteriorly.
Arms five, or ten, stout, not branching
beyond the first axillary. Brachials
quadrangular to cuneiform, tending to
become biserial. Ventral sac incon-
spicuous. Stem round. Lower Car-
boniferous ; Eussia and Mississippi
Valley area.

Ulocrinus Miller and Curley. Similar
to Cromyocrinus, but with anal x entirely
above the radials ; that is,
with radianal but no anal
in the dorsal cup. Arms
unknown. Upper Carbon-
iferous ; North America.

Eupachycrinus Meek
and Worthen. Similar to
Cromyocrinus, but calyx
low, rounded, with concave
base ; infrabasals at bot-
tom of a funnel. Arms ten to twenty. Brachials quadrangular to biserial.
Stem round, with. cirri. Kaskaskia to Upper Carboniferous ; North America
and Europe.

Tribrachiocrinus M'Coy (Pentadia Dana). Calyx globose. Infrabasals three,
large. Radials irregulär in size and form, apparently only three arm-bearing.
Arms unknown. Permo-Carboniferous ; Australia.

Fig. 326.

Cromyocrinus globulus
M. and W. Lower Car-
boniferous ; ehester, 111.
Natural size (after Meek
and Worthen).

Fig. 325.

Agassizocrinus laevis
(Roemer). Kaskaskia

Group ; Illinois, a, Com-
plete crown, after Roe-
mer in Bronn, soniewhat
restored ; b, Ventral as-
pect of the coalesced
infrabasal disk ; c, Side-
view of same, nat. size
(after M. and W.)

t>^.

Fig. 327.

Analysis of plates in the dorsal cup of
Cromyocrinus. ib, Infrabasals ; b, Basais ;
r, Radials ; ra, Radianal ; a, a', a", Anal
and lower tube plates (after Bather).

CLASS III CRINOIDEA 225

Subfaniily B. Graphiocrininae Ballier.

No radianal. Anal x more or less between radials. Arms dichotomous, uniserial
to hiserial. Infrabasals usually five, frequently minute, liidden hy the column, Stern
usually round, cirriferous. Lower Carboniferous to Upper Carboniferous.

Graj)hiocrinus Kon. (Scaphiocrinus RaW ; Phialocrinus Trautschold; Aesiocrinus
Miller and Gurley) (Fig. 328). Calyx low, turbinate or obconic to bowl-
shaped. Infrabasals minute to fair size. Arms
uniserial, usually long, slender, branching once,
sometimes unbranched in one or more rays, making
the number variable from five to ten. Bracbials
quadrangular. Ventral sac very large and con-
spicuous. Stern round, with long cirri throughout.
A genus of ereat stratierraphic ränge and wide fio. 328.

T , .^ ,. T /TT-- 11 1 \ , TT i-^ Analy8isofGra;)7aocrmtt*'. ib, In-

distribution. Lower (KindernOOk) to Upper Uar- frabasals ;&, Basais ; r, Radials ;

boniferous ; North America, Belgium and Russia. Satitr).^ ' ^'' ^'*'^'^^' ^^^^''

Bursacrinus Meek and Worthen. Calyx obconic.
Arms rather broad, closely abutting, branching twice or more, to some extent
as in Zeacrinus ; uniserial, with quadrangular brachials. Ventral sac incon-
spicuous. Very rare. Lower Carboniferous (Burlington); Mississippian area,
North America.

Delocrinus Miller and Gurley {Ceriocrinus White, non Koenig). Similar to
Graphioc7'inus, but with concave base, ventral sac inconspicuous, and heavy
biserial arms. Axillary primibrach frequently protuberant or spiniferous.
Infrabasals at bottom of a deep funnel, hidden by column. Stern rather small,
round, cirriferous. Upper Carboniferous ; North America.

Cibolocrinus Weller. Dorsal cup low, bowl-shaped. Infrabasals three.
Other parts unknown. Permian ; Western Texas.

Subfamily C. Encrininae Austin (emend).

Dorsal cup with perfed pentamerous symmefry, having no radianal or anal
plate. Arms dichotomous, biserial; usually Jieavy, and two to the ray. Ventral
sac inconspicuous or wanting. Infrabasals five, coalesced into one, or atrophied.
Calyx usually low, bowl-shaped, with rounded or more or less concave base. Stern
usually round. Lower Carboniferous to Trias.

Stemmatocrinus Trautschold. Base broadly rounded. Infrabasals coalesced
into a large fTat pentagon. No anal x nor tube-plate visible in cup. Arms
ten, thick, closely abutting, and strongly resembling those of Encrinus
liliiformis. Lower Carboniferous ; Russia and North America.

Erisocrinus White. Base rounded, with but little concavity. Infrabasals
five, fairly large, not in a fui^nel, usually visible outside of the stem. Anal
« or a tube-plate rests on the upper surface of posterior radials. A close
derivative from Delocrinus, which it resembles in the arms and general form,
difFering in the base and absence of anal plate in the cup. Upper Carbonifer-
ous ; North America.

Encrinus C. F. Schulze (Chelocrinus, Calathocrinus v. Meyer ; Flabellocrinus
Klipstein ; (?) Cassianocrinus Laube ; (?) Traumatocrinus Wöhrmann ; Porocrinus

VOL. I Q

226

ECHINODERMATA— PELMATOZOA

PHYLUM IV

Dittmar non Billings) (Figs. 329-331). No anal x nor tube-plate visible.

Calyx low, with base more or less concave.

Infrabasals five, minute, concealed in the basal

concavity, sometimes reduced to three, or atro-

phied. Arms usually ten, exceptionally twenty;

uniserial at their lower ends, but soon becoming

biserial ; separate axial canal in radials, extend-

ing into the arms. Tegmen not definitely

known. Stern round, apparently without cirri.

Abundant in the Trias, especially in the

Muschelkalk of Germany. The stem fragments

of E. UlUformis frequently form beds of marine

limestone (Trochitenkalk).

This genus was formerly associated by the majority
of European authors with the Recent Crinoids under the
Articulata. It was shown by Wachsmuth and Springer
that its relations are clearly with the later Paleozoic
Inadunata, and its position as such is recognised by
most recent writers. The type species, U. liliiformis, by reason of its striking appearance

Fig. 329.
Diagram sliowing conr.se of axial canals
in the calyx and arms of Encrinus. Canals
represented by dotted lines when pene-
trating tlie interior of tlie plates, and by
heavy lines when exposed on the inner
side of the calyx (after Beyrich).

Fig. 330.

Eflicrinus liliiformis
Miller. Muschelkalk ;
Brunswick.

Fig. 331.
Portions of the calyx and arms of Enorinus. a, Interior
of calyx ; ai, Exterior of same ; b, Basal, upper surface ;
r, Radial, inner surface ; ß, One of the uniserial, and ß*, bi-
serial arm-plates ; both of them traversed by duplicate
dorsal canals ; p, Pinnule ossicle (enlarged) ; br, First
brachial, under surface ; br^ 2, First and second brachials
joined togfether ; inside, seen from below ; br^, First brachial,
Upper surface, showing line of syzygial suture ; br"^, Second
brachial (axillary), showing articular facets.

and beautiful preservation, early attracted the attention of observers. The generic name
was first applied in 1760 ; and the form is the best known of all fossil Crinoids,

Order 4. ARTICULATA. J. S. Miller (emend. J. Müller).

Tegmen coriaceous, studded with minute calcareous partides, which may l
invisible externally, or may he entarged into well-defined plates that rarely form a
complete investment. Mouth and food grooves exposed, but often hordered with one
or two rows of side and covering plates capahle of heing closed down over them.
Orals present in the young, often also in the adult. Plates of the dorsal cup, except

CLASS III CRINOIDEA 227

in pelagic forms, massive, and, except in (he pelagic forms, much reduced in size.
Radiais and arm-plates perforated hy separate dorsal canal. Base in most cases
adually or potentially dicyclic ; the infrabasals, and sometimes also the hasals,
heilig often atrophied, radically altered hy resorption and subsequent rehuilding, or
ahsent altogether.

Proximal columnal always modified, usually enlarged, attached to the
calyx by close suture, to the columnal below it also by close suture (the
so-called stem-syzygy) ; but this pair of columnals in some forms, instead
of maintaining the original connection with the calyx, is separated from it
by varying intervals in the stem, or at least in its proximal portion. Union
between the plates of the dorsal cup is by close suture, between the radials
and the primibrachs by muscular articulation, and between the elements of
the primibrach series by non-muscular articulation. Eadials always in lateral
contact. Radianal and anal plates may be represented as such in the larval
stages, but never in the adult ; and the anal occasionally develops into a sup-
plementary radial, bearing a typical post-radial series indistinguishable from
those on the other radials. Arms uniserial and pinnulate, though the basal
pinnulation is often defective. No concavity in the apex of the dorsal cup
for the reception of the stem. Stem reduced to a single columnal in the
Comatulid division of this order. Lias to Recent.

In the earlier German and English editions of this work, following the example
of previous European authors generally, the Mesozoic and Recent Crinoids (excepting
Marsupites, Uintacrinus, and perhaps Encrinus) were treated as a distinet group from
the Paleozoic under the name Articulata, proposed by J. S. Miller for the Apiocrinidae,
Encrinidae and Pentacrinidae, and extended by Johannes Müller to include the
Comatiüids. The chief characters relied upon to distinguish the order, viz. (1) «n
open mouth and food grooves, (2) a separate axial or dorsal canal perforating the
arms, were admittedly indecisive, considering that the first belongs eqiially to the
entire Paleozoic groiip Flexibilia, and the second is shared by a Devonian family and
several genera of the Inadunata.

This evident inadequacy of the definition has led to various proposed Substitutes
for the plan, such as placing the Pentacrinidae under the Fistulate Inadunata, and
the Comatulids together with the Apiocrinidae, etc., as a subdivision (" Pinnata ")
under the Flexibilia. None of these has proved satisfactory ; least of all the last,
for the lack of any sufficiently definable connection between the so-called Pinnata and
the Paleozoic Flexibilia. The very pliant calyx of the latter recurs in the pelagic
Comatulids, Marsiqntes and Uintacrinus, and the close lateral union or partial
incorporation of lower brachials is found to some extent among the Apiocrinidae,
Pentacrinidae, and some Comatulids. But it has become increasingly evident that
the Flexibilia were a specialised group, derived from the Inadunata, and ending like
the Camerata with the Paleozoic.

The only one of the primary divisions of the Crinoids that seems to have survived
is the Inadunata, the most generalised type, from which all the post-Paleozoic forms
are evidently descended. While, therefore, there is no valid ground for any such
divisions as Paleocrinoidea and Neocrinoidea, as proposed by Wachsmuth and Springer
and by Carpenter, but afterward abandoned, yet it cannot be denied that, with the
sole exception of the Triassic Encrinus, the known Crinoids of Mesozoic to Recent
times have an assemblage of features by which they are broadly distinguished from
their Paleozoic ancestors. And it is believed that this may be expressed under the
group Articulata as enlarged by Johannes Müller, distinguished not by any single
character peculiar to itself, but by the fact that a large numljer of characters belonging

228 ECHINODERMATA— PELMATOZOA phylum iv

to different groups of Paleozoic Crinoids, and by which they were differentiated, liave
become fixed and generally constant in tliis. It is by tbe combination of a number
of well-marked cliaracters, therefore, that tbe definition of tbis group, as herein given,
becomes logically effective.

The results obtained during recent years from the study of the Crinoids coUected
by a large number of deep-sea expeditions, have thrown an entirely new light upon
the relative importance of the Recent and fossil forms, and have shown that there exists
to-day a wealth of generic and specific types hitherto quite unexpected. In order to
call attention to the relative importance of the fossil and recent types, and to bring to
the notice of paleontologists the work which has been accomplished on the latter, it
has seemed advisable to include mention herein of a considerable number of Eecent
genera. As the paleontologist is most directly concerned with the stalked genera
among living forms, short definitions of these are given ; the unstalked living genera,
which are much more numerous, are mentioned by name only.

The Pentacrinids and the Comatulids form two gi'oups which are in every way
strictly parallel, and are of substantially the same phylogenetic value, though depart-
ing in exactly opposite directions from the parent stock. The Pentacrinids are
characterised by excessive stem growth ; the larval stem is lost at a very early age,
but new columnals are continuously formed, with great rapidity, so that a stem of
enormous length results. The distal portion of this stem is continually dying away,
so that the actual length of the stem in any individual is but a fraction of the entire
length which has been formed during growth. In living Comatulids the larval stem is
similarly lost ; but after this takes place no additional columnals are formed ; stem
growth continues within the single columnal which remains attached to the calyx ;
this becomes greatly enlarged, and puts forth numerous cirri. Comatulids may
therefore be described as Pentacrinids in which the entire stem is reduced or limited to
the compass of a single columnal, and in which the cirri (when present), unable to
arrange themselves in whorls on regularly spaced nodals, are closely packed together
on a Single nodal.

. The genus Thiolliericrinus is exactly intermedia te between the Pentacrinids and
the Comatulids ; the stem is developed just to the point at which the two groups
diverge, at that point ceasing further growth, as in the Comatulids, but being retained
as in the Pentacrinids. The structure of the stem is the same as that of the larval
stem of the Pentacrinids and of the Comatulids.

The Pentacrinids and Comatulids are the dominant Crinoid forms in the modern
fauna. The latter especially are extremely numerous, and exist in a vast array of
diverse types, none of which, however, depart in any great degree from the general
structure of the group ; so that their Classification necessitates the creation of numerous
subfamilies, families and higher groups which are not systematically comparable to
similar groups in the stalked forms.

In Order that the treatment herein adopted may be more easily understood, the
foUowing comparative table is given, which shows in heavy-faced type the names
employed by P. H. Carpenter in the Challenger reports and largely used by paleon-
tologists, together with their modern equivalents.

1. Pentacrinus : Isocrinus, Cenocrinus^ Endoxocrinus, Hypalocrinus, Carpenterocrmus.

2. Extracrinus : Pentacrinus.

3. Antedon : All the genera which were known to Carpenter now included in the families
Zygometridae (excepting Eudiocrinus), Himerometridae, Stephanometridae, Pontiometridae,
Mariametridae, Colobemetridae, Tropiometridae, Calometridae, Thalassoraetridae, Charito-
metridae and Antedonidae (excepting Promachocrinus).

4. Actinometra : All genera included in the Comasteridae.

5. Eudiocrinus : The geniis EudiocriniLs of the Zygometridae, together with Pentamctro-
crinus of the Pentametroerinidae.

6. Promachocrinus : The genus Promachocrinus of the Antedonidae, together with
Decametrocrinus of the Pentametroerinidae.

CLARR III

CRINOIDEA

229

Family 1. Bourgueticrinidae de Loriol.

Column without terminal stem plate, but the distal portion of the stem bears very
numerous radicular cirri. It is slender, composed of joints which may be greatly
elongated with strongly concave sides, or about as long as broad with strongly convex
sides, or of any intermediate form ; but the articulating surfaces always consist of a
strong fulcral ridge {which may be interrupted in the centre by the central canal)
separaiing two large ligamental fossae ; one or more of the columnals immediately
Wilder the calyx may be discoidal,- mth plane surfaces. Dorsal cup small, but very
variable in size and in the relative proportions of its component plates ; composed of five
hasals (which may be solidly welded into a single plate), and {usually) five radials.
Infrabasals unknown, probably absent in the adult. Arms slender, five or ten ; if
the latter, two primibrachs are present. If there are four, six, or more radials, one
arm follows each radial. Cretaceous to Recent.

Bourgueticrinus d'Orb. (Fig. 332). Basais not fiised. Radials five ; lower
brachials laterally connected. Proximal columnal round, as wide as the calyx

Fig. 332.

Bourgueticrinus ellipti-
cus Miil. White Clialk ;
Wiltshire. a, Calyx with
stem-joints, i/i ; 5, Ventral
aspect, enlarged ; c, Stem-
joints ; d, Articular sur-
face of stem -Joint ; e,
Girr US.

Fig. 333.
Rhizocrinus pyriformis (Goldf.). Eocene ; Verona.
a, h, Calyx from one side (nat. size and enlarged);

c, Same from above, with three of the Br in place;

d, Median longitudinal section of calyx, Vi 5 e, Calyx
with slightly abraded outer surface, showing suture
lines between B and R ; f, Calyx with five rays, seen
from above (enlarged) ; g-k, Stem-joints, i/i.

at its greatest breadth, those below it diminishing for one or two joints and
becoming compressed, with elliptical Joint faces, each columnal twisted so that
one end Stands at an angle to the other. ^ Cirri present distally, or perhaps in
middle of the stem. Cretaceous ; Europe and Alabama.

Mesocrinus P. H. Carpenter. Proximale small and circular ; otherwise like
Bourgueticrinus. Cretaceous ; Sweden and Germany.

(?) Dolichocrinus de Loriol. Radials form an elongate tube. Upper Jur-
assic ; Europe.

Rhizocrinus Sars (Gonocrinus d'Orbigny, non Troost) (Fig. 333). Basais com-
pletely fused, forming a very large and elongate base ; radials very small, four
to seven (usually five or six) ; arms undivided ; column slender, composed of
greatly elongated segments of which the distal bear radicular cirri. Cretaceous ;
New Jersey. Eocene ; Europe. Recent ; north Atlantic.

Bythocrinus Döderlein. Similar to Rhizocrinus, but with the basals separated
by distinct sutures ; radials (and arms) invariably five. Recent; in tropical
Atlantic, and western Indian Oceans. ,• i • i

Democrinus Perrier. Similar to Rhizocrinus, but with the base subcylmdrical ,

230

ECHINODERMATA— PELMATOZOA

PHYLUM IV

the basals being separated by distinct sutures ; columnals very short, but
little longer than broad, more or less barrel or bead shaped ; radials (and
arms) invariably five. Recent ; tropical Atlantic and East Indies.

Bathycrinus Wy v. Thomson {Illycrinus Danielssen and Koren ; Pterocrinus
Wyv. Thomson). Essentially similar to Bhizocrinus, but with ten arms, each
post-radial series dividing on the second ossicle ; basals usually much reduced,
forming a narrow ring beneath the much larger radials. Recent, chiefly occur-
ring at great depths, cosmopolitan.

Monachocrinus A. H. Clark. Similar to the preceding, but with the basals
separated by distinct sutures, and usually nearly or quite as large as the
radials, sometimes larger. Lower Muschelkalk ; near Rovegliana. Recent ;
East Indies, Bay of Bengal, east Atlantic.

Family 2. Phrynocrinidae A. H. Clark.

Similar in general to the Bourgueticrinidae, but with the stem attaehed to a heavy
terminal stem-plate (dorsocentral) as in the Apiocrinidae. Recent.

Here are placed the two genera Naumachocrinus and Phrynocrinus Clark,
occurring at depths of from 500 to 650 fathoms in the Pacific Ocean. The
former of these has a calyx superficially resembling that of Democrinus, but
composed of very small basals and much elongated radials.

Family 3. Apiocrinidae d'Orbigny.

Column without cirri ; enlarged distally and attaehed to a heavy terminal plate,
or fixed root ; composed of short ^ discoidal columnals having their articular faces
marJced with radiating Striae without fulcral ridge ; those next below the calyx often
increasing greatly in width, forming a proximal enlargement continuous with the sides

of the calyx. In the more

Fig. 334.

specialised types the proximal colum-
nals may become penfagonal or
stellate, and may bear rudimenfary
cirri. Calyx variable, composed of
heavy plates. Infrabasals greatly
reduced, modified or fused with the
proximal columnal ; visible rarely
within the basal ring {cryptodicyclic).
Lower brachials more or less incor-
porated in the calyx by lateral union,
or by a few interbrachial plates.
Primibrachs two ; arms branching
regularly, usually more than once.
Jura, Cretaceous and Recent.

Ran-

Apiocrinus parlcinsoni Schlotheim. Great Oolite
ville, Calvados, a, Calyx and upper stem-joints, viewed froin
the side ; h, Ventral aspect ; c, Articular surface of one of the
stem-joints (natural size).

Apiocrinus Miller (Figs. 334-
336). Plates of calyx greatly
thickened, especially at the distal
border of the radials, where the typical muscular articulation is modified
by an enormous enlargement of the dorsal ligamental fossa, consequent upon
such thickening ; thh expansion afFects in addition to the calyx, a series of
the Upper columnals, and of the lower brachials. Calyx in typical forms

CLASS III

CEINOIDEA

231

pyriform, attaining a large size, with proximal columnals flush with the
curvature of its sides ; in some others globose, with little enlargement of
the column. Upper face of the proximale marked by angular ridges corre-
sponding to the iiiterbasal suture lines. Radial facets wide, curved,
occupying entire distal face of plate. Primibrachs two, united by incom-
plete syzygy, closely joined laterally by suture, or occasionally connected
by small interbrachial s ; axillary and succeeding brachials united by muscular

Fia. 335. Fig. 336.

Fig. 335.
Ainocrinus parkinsoni Scliloth. Great Oolite ; Ranville, Calvados. A, Analysis of calyx, showing conrse
of canals. These are represented by dotted lines when concealed within the plates, and by heavy lines where
visible on the inner surface of the basals. B, Median longitudinal section throngh the uppeniiost stem-joints,
showing empty Space included between them ; &, Basal, seen fromabove and from the iiiside ; h*, Lower surface
(jfsame ; ri, Radial, seen from without; ri*, Inner aspect of same ; r^!, and r'^*, Corresponding views of first
brachial ; br, Arm-plates. (Canals are invisible in plates above the basals, except where they have become
exposed by weathering or abrasion.)

Fi(i. 336.
Ainocrinus roissyanus d'Orh. Upper Jura (Coral- Rag) ; Tonnerre, Yonne. Restoration (after d'Orbigny).

articulation, and all perforated by an axial canal, Arms dichotomous,
branching two or three times, pinnules strong. The column has a large opeii
Space in the expanded portion next to the calyx, the columnals sloping to a
thin edge toward the centre. Jurassic ; England, France and Switzerland.

Millericrinus d'Orb. (Ceriocrinus and Pomatocrinus Desor, ex Koenig). Closely
allied to Apiocrinus, but the swelling of calyx plates afFects only one or two
columnals, and not any brachials, nor the distal border of the radials, which
remains narrow, so that the muscular articulation is of the usual type.
Calyx usually more or less globose or campanulate. Base occasionally with

232 ECHINODEEMATA— PELMATOZOA phylum iv

five minute infrabasals coalescedwith the top stem-joint, which is frequently
widened and those below it not usually so. Column more or less pentagona!,
with the angles directed interradially. Lias to Lower Cretaceous ; Europe.

Guettardicrinus d'Orb. DifFers from Apiocrinus only in having strong
interbrachial plates between the lower brachials, and the consequent incor-
poration in the cup of a greater number of secundibrachs. Upper Jurassic ;
Europe. This and the two preceding genera shade into one another without
any sharp differentiation.

Dadocrinus Meyer.^ Calyx conical, of small size. Column sharply
pentagona! proximally, becoming round below, without cirri ; proximal
columnal much smaller than the calyx. Primibrachs sometimes more or less
connected by small interbrachials. Arms branching once. Trias ; Europe.

Holocrinus Jaekel. Trias ; Germany.
■ Achrochordocrmus Trautschold {Cyclocrinus d'Orh., non Eichw.; Mespilocrinus
Quenst., non Koninck). Jura and Lower Cretaceous ; Europe. Columnals
only are known.

Proisocrinus A. H. Clark. Rudimentary cirri on proximal portion of the
column ; proximal columnals with crenulate edges ; division series very
broad, in lateral contact. Recent ; Philippines, 940 fathoms.

Carpenterocrinus A. H. Clark. No trace of cirri ; proximal columnals with
smooth edges ; division series narrow, exposing large perisomic areas.
Recent ; southern Japan, 565 fathoms.

Family 4. Pentacrinidae Gray (emend.).

: Column either very long, pentagonal or suhpentagonal, without any terminal plate,
and cirriferous; or represented hy a Single plate, also usually cirriferous ; in very
young stages similar to the stem of Rhizocrinus, hut later discarded ; the portion
retained in the adult of sessile forms is composed of columnals which have the upper
and lower faces 'ornamented with a more or less complex quinquelobate figure. Calyx
small, howl- or plinth-shaped, with a dicyclic base, at least in the young, hut the
infrabasals either rudimentary or completely resorbed in the adult state ; and the
basals may be also resorbed and metamorphosed into a curious rosette-shaped plate
lying entirely within the calyx. Infrabasals {where observed) three or five ; basals
five ; radials five {one, the left posterior, sometimes much smaller than the others).
Primibrachs, or costals, one to eight {usually two). Tegmen fiexible, studded with
small irregulär calcareous pa,rticles or delicate plates which may be quite invisible to
the naJced eye, or may form a solid covering. Arms pinnulate ; strong, from five
simple, to two hundred and fifty or more ultimate branches. Trias to Recent.

Section A. Pentacrinids Gray (emend.).
Column persistent throughout life.

Pentacrinus Blumenb. {Extracrinus Austin ; Polycerus Fischer pars ; 1 Chlado-
crinus Agassiz) (Fig. 337). IBB well developed. BE usually prolonged
over the proximal columnals. There are rarely more than two IBr, not bearing
pinnules. Arms heterotomous, with two to four rami, branching only toward
the inside of the dichotom, into large subordinate pinnulate ramules which
rise to the height of the main rami, until the final divisions are all about the
same size ; these divisions are very numerous, in mature specimens as many
as forty or fifty to the ray. Column more or less pentangular ; the angles

CLA.SS III

CRINOIDEA

233

of the axial canal, contrary to the general rule in dicyclic forms, directed
radially, corresponding with the outer angles of the stem. Stern of great
but unknown maximum length, having been traced for twenty feet without
reaching the end ; cirri very numerous, compressed or elliptical in section.
Lias and later Jura ; Europe.

The Crinoids of this geiius were
very gregarious, and flourished in
immense colonies. Exquisitely i)re-
served specimens are found in the
Lower Lias of Lyme Regis, Eng-
land, and in the vicinity of ßoll
and Metzingen, Würtemberg, which
have served as types of illustra-
tions in numerous works on Paleon-
tology. A slab containing no less
than twenty-seven perfect crowns
intertvvined with stems and cirri,
raay be seen in the U.S. National
Museum at Washington.

Isocrinus Meyer {Isis Linn.
pars; Encrinus hsunsirck pars ;
Cainocrinus Forbes ; Ficteto-
crinus de Loriol ; Neocrinus
Wy V. Thomson ; Pentacrinus
sensu P. H. Carpenter). IBB
so far as known, present in
the adult, but visible only
when stem is removed. BB
forming a complete circlet,
or minute and separated by
lower angles of BE. Eadials
notprojecting down ward over
proximal columnals. Arms
about regularly dichotomous.
Columnals of circular, penta-
gonal or stellate section ;
sectors of joint-face distinctly
petaloid, with coarsely crenu-
late edges. Trias and Juras-
sic; Europe and North
America. Eecent ; "West
Indies (5-531 fathoms).

Balanocrinus Agassiz in
Desor. Columnals of circular
or hexagonal section, with crenellae around the edge only, not along the
sides of the sector. Trias to Eocene ; Europe. Known from fragments only.

Austinocrinus de Loriol. Columnals have a Joint surface as in Isocrinus,
but with finer Striae radiating from the petals. Cretaceous ; Europe.

Cenocrinus Wyv. Thomson. Recent ; West Indies (5-531 fathoms).

Endoxocrinus A. H. Clark (Diplocrinus Döderlein). Infrabasals resorbed
in the adult. Arms heterotomous, in two main rami with branches to the
inside of the dichotom ; the divisions are at the outer side of the rays only,
and consist each of two joints, united by syzygy. Kecent ; West Indies.

Fig. 837.
Pentacrinus (Extracrinus) fosfdlis Blum. Lower Lias ; Lyme Regis,
England (after Goldfuss). a, Stem-joints of P. subangularü Mill.
Upper Lias ; b, Column of P. hascUtiformis Mill. Middle Lias.

234 ECHINODERMATA— PELMATOZOA phylum iv

Metacrinus P. H. Carpenter. Arms dichotomous, multibrachiate ; IBr
four to eight in number. The distal portion of the arms bears only
rudimentary pinnules. Recent ; Pacific Ocean.

Hypalocrinus A. H. Clark. Ten arms only, unbranched ; IBr two. The
distal portion of the arms bears only rudimentary pinnules. Recent; East
Indies.

Comastrocrinus A. H. Clark. Resembles the preceding, but with more
than ten arms, and with the distal edges of the brachials strongly produced.
Recent; Indian Ocean.

Section B. Thiolliericrinids A. H. Clark.

Column persistent throughout life; hut columnar development ceases after the
formation of the first nodal.

Thiolliericrinus Etallon. Column resembling that of the pentacrinoid
larvae of the Comatulids, but greatly enlarged and thickened ; calyx as in the
adult Comatulid. Jurassic and Cretaceous ; Switzerland, France, Portugal.

The genus Thiolliericrinus has been considered both as representing a primitive Comatulid,
and a transitional stage between the Apiocrinidae and the Pentacrinidae ; but neither view
is correct. The column of Thiolliericrinus is comparable to that of a Comatulid or of a
Pentacrinid at the time of the formation of the centrodorsal or of the first cirriferous nodal ;
stem development has here abruptly ceased, so that the column has retained its primitive
Bourgueticrinoid character, modified only by an increase in size ; but the calyx has continued
to develop so as to be comparable to the calyx of the Comatulids, or to the calyx of the
more advanced aniong the Pentacrinids. Thus Thiolliericrinus possesses the calyx structure
of the adult Pentacrinid or Comatulid, combined with the column structure of the larvae of
the same types. It therefore falls naturally between them.

Section C. Comatulids Fleming (emend.).i

Column either wanting entirely, or discarded after the formation of the first
nodale which remains permanently attached to the calyx.

While the Comatulids, as already explained, forin a group strictly comparable in
phylogenetic value with the Pentacrinids and Thiolliericrinids, this group is
wholly disproportionate to those in complexity and extent. Owing to their enormous
and cosmopolitan development in Recent seas, the Comatulids require for their
Classification further subdivision in a way not applicable to any of the fossil families.
The group must therefore be taken as a new unit, divisible into subgroups which are
comparable in rank only inter se, and not with subdivisions of similar grade or
terminology among the other Crinoids.

Tribe 1. Innatantes A. H. Clark.

Pelagic Comatulids in which the basals are not metamorphosed hut form an
integral part of the hody wall ; the infrahasals are not united with the central plate,
but frequently, through individual Variation, they are absent. There is no evidence of
attachment in any hnown material, so that their central apical plate probably repre-

^ Literature : Müller, J., lieber die Gattung Comatula, etc. Abhandl. Berlin. Akad. 1847. —
Ludwig, H., Beiträge zur Anatomie der Crinoidea. Zeitschr. wiss. Zool, vol. xxviii. 1877. —
Carpenter, P. H. Report on the Crinoidea. Sei. Eesults Ghali. Exped., xi. and xxvi., 1884-88. —
Jaekel, 0., Entwurf einer Morphogenie und Phylogenie der Crinoideen. Sitzber. naturf. Ges., 1894.
— Clark, A. H., See titles cited under general discussion.

CLARS III

CRINOIDEA

235

I

sents the Single columnal of Comatulids and the entire stem of the Pentacrinids.
The calyx is very large, and its plates, which are very tJiin, are strongly curved out-
wardly. Cretaceous.

Subtribe A.

Marsupitids d'Orbigny.

Column wanting, probably represented hy a large pentagonal plate called the
centrale,^ within the infrabasal circlet. Calyx large, perfedly pentamerous, composed
of large thin plates, without interradials or anals ; greatest bulk below radials. Base
dicyclic plus the centrale, one of the largest plates in the calyx. Infrabasals five,
very large. Radial facets narrow, crescentic, with a perforated transverse ridge.
Lower brachials much less than the width of
the radials, connected for a short distance
by interbrachials, but not strictly incorpor-
ated in the dorsal cup. Primibrachs two,
narrow. Arms small, apparently short,
with slender pinnules ; bifurcation on the
second primibrach, further branching un-
known. Tegmen unhiown.

The only known genus is Mar-
supites Miller (ex Mantell MS.), occur-
ring in the Upper Cretaceous (White
Chalk)of England, France and Northern
Germany, and in the Tombigbee Sand-
stone of Northern Mississippi. Its
general structure is on the Inadunate
plan, with remarkable development of
the basal portion, the infrabasals and
centrale constituting about half of the entire calyx (Fig. 338),

ii

Fig. 338.

Marsupiteji testudinarius (Schloth). Upper Cre-
taceous ; Lüneburg, Prussia. a, Calyx, natural size ;
h, Radial, and a few of the arm-plates ; <", Tips of arms.

Subtribe B. Uintacrinids Zittel.

Column wanting. Calyx large, perfedly pentamerous, greatest bulk above line
of radials, plates thin; interbrachial system greatly developed. Base dicyclic m'
monocyclic ; infrabasals present or absent in both young and adult of the saine
species ; when present, five (but sometimes by resorption reduced irregularly to three,
two, or one), very small, enclosing a small centrale, probably representing the stem ;
when absent, the centrale remains of about the same size, surrounded by the basals.
Interbrachials numerous, from the radials up, and often also in the second axil.
Primibrachs two, as large as the radials ; the second one axillary, followed by secundi-
brachs almost as large, passing gradually into free arms. Arms ten, unbranched,
very long and strohig ; composed of very short, almost circular brachials, with frequent
syzygies, Joint faces provided with transverse ridge, and pierced by an axial canal.
Pinnules stout and tapering, the lower ones incorporated into the calyx by lateral
Union. Tegmen composed of a carbonaceous skin becoming black in the fossil State,
traversed by uncalcißed ambulacra ; mouth marginal; anus subcentral, through a
sfrong, tufted tube.

^ This plate is supposed by Carpenter to represent the distal plate of the stem, and not the
proximal. A. H. Clark believes it, and the similarly situated plate in Uinfacnnns, to be the
honiologues of the distal stem-plate, plus all the columnals of young liecent Comatulids.

236 EOHINODERMATA— PELMATOZOA phylum iv

Represented by a single genus, Uinfacrinus Glrinnell (Fig. 339), occurring
in the Upper Cretaceous of Western America (especially Kansas), England

and Westphalia. In the latter
areas it is widely distributed,
accompanied by Marsupifes
and Bourgueticfinus. In the
Kansas region it is found ex-
clusively in colonies which
had been herding together in
deep water. The genus in its
calyx structure is a survival
of the Flexibilia plan ; it is
strongly in contrast with
Fig. 339. MarsupUes in this, and in the

üintacrinus westphalicns (Schlüt.). Upper Cretaceous ; Reck- length of the arms, which in
lingshausen, Westphalia. a, Calyx viewed from the slde ; h, ^ • j.^ • i

Inferior aspect. Natural size (after Schlüter). Hiature specimens attamed a

length of four feet, giving
when outstretched a spread of upwards of eight feet, the largest known
Crinoid.

Tribe 2. Oligophreata A. H. Clark.

Bottom-inhaUting Comatulids, stalked when young ; hasals metamorphosed into
a rosette ; infrahasals unknown ; cavity in the centrodorsal containing the chamhered
organ, and overlying structures very small, these being pushed up more or less within
the radial circlet ; disk more or less studded, or even completely covered, with large
calcareous concretions or plates'/ pinnules, at least the lower, wholly or in pari
prismatic, and composed of short segments ; usually more than ten in numher.

Generic names have been applied to fossil Comatulids belonging to this
division, but the specimens upon which they are based are rarely well enough
preserved to admit of correlation with generic names based upon Recent types.
The latter include a surprisingly large number of living genera, which are
grouped by A. H. Clark in nearly a dozen difTerent families. Among these
may be mentioned the Comasteridae, Zygometridae, Thalassometridae and
Charitometridae as examples.

Tribe 3. Macrophreata A. H. Clark.

Bottom-inhaUting Comatulids, stalked when young ; hasals usually metamorphosed
into a rosette ; infrahasals, three, or more usually five, in numher, have heen deteded
in the young of several species, where they fuse with the centrodorsal ; cavity in the
centrodorsal containing the chamhered organ and associated structures large ; tegmen
naked, or studded with minute plates which may hecome grouped in the interradial
angles, particularly hetween the IBr ; pinnules all cylindrical or more or less
flattened, slender, with very long Joint s ; arms five or ten in numher, except in the
genera in which there are ten radials, in which they may he twenty.

Within this category are embraced three divisions — Atelecrinidae (Bather),
Pentametracrinidae (Clark) and Antedonidae (Norman) — the last-named of
which is again divided into a number of groups having the rank of sub-
families. One of them, Antedoninae, includes the Recent genera Antedon

CLASS III

CEINOIDEA

237

Freminville {Ganymeda Gray; Hihemula Fleming; Fhytocrinus Bio) (Fic
283) ; Conipsometra, Toxometra and Iridometra A. H. Clark, etc.

Fossil Comatulid Genera.

The following genera are based wholly or in part upon fossil Comatulids :
^/W Michelotti;^5W^/,s Schlotheim; Astrocoma Blainville; Comaty.
d ürbigny ; Comatuhthes

von Schlotheim; Comaturella
Münster; DecacnemosBvonn ;
Decameros d'Orbigny, Geo-
coma 0. Fraas; Glenotremites
Goldfuss; J^er/Ä^Hagenow;
Microcrinus Emmons ; Ophi-
■urites von Schlotheim ; Ftero-
coma L. Agassiz ; Solanocrinus
Goldfuss (Fig. 340).

The specimens upon
which the type species of
these genera are founded are
rarely well enough pre-
served to admit of reference
to any one of the Eecent
genera, or even families, and
in some cases it is doubtful
whether they are Coma-
tulids at all. P. H. Car-
penter attempted to differ-
entiate the fossil types into
Antedons and Aäinometras ;
but recent discoveries have
shown that the endocyclic
and exocyclic forms are
by no means easy to dis-
tinguish, even with perfect
specimens, and with even

'vt^'M

srjki

',,^0mik

^ms:::!^-"^

W^' '<;s>^,.„

w ■='

■•»t~t

^.

# t

Fig. 340.

a, Solanocrinus costatus Goldf. Upper Jura (Diceras-Kalk); Kel-
heim, Bavada. Dorsal aspeet of crown ; centrodorsal and pinnules
not preserved (slightly reduced) ; h-d, S. scrdbicvlatus Goldf. Upper
the best preserved fossils '^"^''^ '■> Streitberg, Franconia ; b. Ventral ; c, dorsal ; and rf, lateral
. . , . aspeet of calyx ; e, Arni-plate.

the Separation of the species

on this basis is very unsatisfactory. A common method of procedura in
dealing with fossil Comatulids has been to refer them all (except those with
five arms, all of which belong to the genus Eudiocrinus of the Zygometridae)
to a Single genus, for which the name Solanocrinus is used.

Family 5. Plicatocrinidae Zittel.

Basal circlet funnel-shaped, quadrangidar, pentagonal or hexagonal, composed of
three (usitalhj), or five basals which may he solidly anchylosed. Radiais four, five,
six or eight (rarely seven), long and thin, hearing the post-radial series of brachials
on a narrow facet, which occupies only a small portion of their distal edge. Arms
long, undivided or branching one or more times ; the first branching usually on the

238

ECHINODEEMATA— PELMATOZOA

PHYLUM IV

Fig. 341.
PlicatocHmis hexagonus Müust.

first brachial, never on the second. If the arms are undivided the pinnules are
usually excessivehj long and reach to the arm Ups ; hut the length of the pinnules
decreases in proportion to the number of arm divisions ; pinnulars sometimes tending
to fuse into a solid piece. Column as in the Apiocrinidae, but never with a proximal
enlargement.

Plicatocrinus von Münster (Fig. 341). Eadials comparatively thin, their
articular facets crescent-shaped ; the outer faces longitudinally folded into
a median ridge. Arms ten, dividing on the first brachial ; composed of
wedge-shaped ossicles united by perforate muscular articulation. Pinnules
composed of a single piece, except the proximal ones, which consist of three
pieces ; they are angular or keel-shaped along the dorsal side, and deeply

furrowed on the ventral. Teg-
men unknown. Upper Jura; a
rare form, found in the Fran-
conian and Swabian Alb.

Hijocrinus Wyv. Thomson

(Fig. 342). Three basals ; five

Upper arms, bearing extremely long

Jura ; Streitberg, Franconia. a, Calyx with ■niTinnlp«! wViipVi rpnpVi fn fliP

radials and undivided base ; h, c, Dorsal and PUmUieS wnicn reacn tO tne

lateral aspects of same (slightly enlarged) ; arm tips ; brachials unitcd in
d-f, First brachial, seen from the inside, out- . -, - , ■, ^n

side, and from below respectively. Syzygial grOUpS Ol three. i eg-

men composed of five large
orals, surrounded by heavily
plated perisome. Recent ;
Antarctic Seas.

Gephyrocrinus Koehler and
Bather. Similar to Hyocrinus,
but brachials united in syzy-
gial groups of two; proximal
portion of column pentagonal.
Recent ; Canaries and Madeira.

Thalassocrinus A. H. Clark.
Similar to Gephyrocrinus, but

Hyocrinus Ijethellianus Wyv. Thomson. Recent; Atlantic prOXimal portiou of Column

Ocean. A, Individual twice the natural size. B, Tegmen several hexagOnal. Rcceut " Philip-

tiraes enlarged ; am, Ambulacral furrows of the arms ; c. Dorsal . " * •' "

canals ; an, Anus ; m, Mouth ; o, Orals (after Wyville Thomson) ; pines.

s,Coveringplatesof ambulacral grooves. PtilocrinUS A. H. Clark.

Five arms, unbranched ; each brachial, except the most proximal, bears a
pinnule ; syzygies very infrequent ; pinnules not especially long. Recent ;
Antarctic Seas and west coast of America to British Columbia.

Calamocrinus A. Ag. Five brachials ; the arms brauch several times.
Recent ; Galapagos Islands and Central America.

Fig. 342.

Family 6. Saccocomidae d'Orbigny.

Calyx small, hemispherical, non-pedunculate, composed almost exclusively of
five radials, which are very thin, elevated into prominent ridges along the median
line, and enclose an extremely small basal plate. Arms 5x2, slender, widely
separated, and giving off alternately towards the extremities simple incurving
l)ranches. Arm-plates cylindrical ; each side of the ambulacral furrow lined with

CLASS III

CRINOIDEA

239

wing-like or spiniform projeäions. TU entire skeleton exhibiting a reticulated
struäure with coarse meshes. Upper Jura.

I

The only known genus, Saccocoma Ag. (Fig. 343), occurs profusely in
;he Lithographie Stone of Eichstädt and Solenhofen, Bavaria. It is a

Saccocoma jxxtiTuita Goldf. Upper Jura (Kimmeridgian) ; Eichstadt, Bavaria. a, Individual, natural size ;
h, Side View of calyx ; c, Calyx seen from below, -/x ; d, Two of the lower arm-plates ; e, Two arm-plates of a
higher order with one of the branches ; /, The upper part of one of the arins straightened out ; g, Lower
brachials of 5. tenella Goldf. (Figs. d and g greatly, the others slightly enlarged.)

free-swimming form, whose affinities with the monocyclic Plicatocrinidae were
first clearly demonstrated by Jaekel in 1892.

Family 7. Eugreniacrinidae Zittel.

(Coadunata Miller ; Holopocrinidae p.p. Jaekel.)

Calyx composed of five (rarely three, orfour) thick, rigidly united radicdsy resting
upon a proximale composed of fused basals and top stem-joint ; basals inrnsiblCj
tegmen unknown. Costals compressed, flange-like ; united by syzygial sutwes, or
fused with one anofher. Arms robust, and incurving, usually branching on the
second brachial. Stern short, destitute of cirri, and composed of but a few long
cylindrical joints with granulated oi' striated articular faces ; terminating in a mm'e
or less lobed, encrusting root. Lias to Lower Cretaceous ; Europe.

Eugeniacrinus Miller (Symphytocrinus König ; Caryophyllites of pre-Linnaean

240

ECHINODERMATA— PELMATOZOA

PHYLUM IV

authors) (Figs. 344, 345). Dorsal cup small, saucer - shaped, and with
shallow body-cavity. Proximale covered with five radiating ridges. B
invisible when the proximale is attached, but from the course of the axial
canals (Fig. 344) it is apparent that tbey are pushed upward so as to be
completely enveloped by the R. The latter are very heavy, closely united,
and sometimes completely anchylosed. The lateral margins of their upper
faces are extended upwards so as to form conspicuous projections ; the inter-
mediate Spaces are occupied by transverse ridges and deep fossae. Costals
two, the Upper one axillary. Structure of arms
unknown. Abundant in the Upper Jura, notably
in the Spongitenkalk of Southern Germany,
Switzerland, France and the Carpathians. Less
common in the Dogger and Lower Cretaceous of
the Alps.

Tetracrinus Münst. R typically four, rarely
three or five ; apparently reposing directly upon
the column, as nx) B or IB are visible. Upper
face of the proximale marked by four (sometimes
three or five) prominent ridges which are radially

Fio. 344,

Eugenioicrinus caryophyllatios Miller. Upper Jura ;
Streitberg, Franconia. a, Calyx with centrodorsal,
Seen from one side (nat. size) ; h, c, Ventral and dorsal
aspects, 3/2 ; d, d*, First brachial, inner and upper
surface ; e, Second brachial, seen from the inside (nat.
size). f-h, E. nutans Goldf. Same locality ; /, /*, First
and second Br fused together, seen from the outside
and inside, respectively ; g, Arm-plate, figured in four
positions ; h, Dorsal and lateral aspects of an inrolled
arm.

Fig. 345.

Eugeniacrinus caryojihyllatus
Miller. Upper Jura, a, Restora-
tion, without the arms (after
Fraas) ; h, Calyx broken open to
show the siliciüed axial canals
(after Jaekel).

disposed ; lower face bearing radiating peripheral Striae, which are not con-
tinued over the median portion of the plate. R with transverse ridges and
large muscular fossae. Stem-joints barrel-shaped. Upper Jura ; Europe.

Gammarocrinus Quenst. (Sclerocrinus Jaekel). Dorsal cup massive, concave
below. Upper Jurassic ; Europe.

Gymnocrinus Loriol. First axillary remarkably developed. Upper Jura ;
Europe.

Phyllocrinus d'Orb. Dorsal cup globose ; R with narrow articular facets,
at either side of which are long, upright projections. Upper Jura and Lower
Cretaceous, notably in the Mediterranean district.

Torynocrinus Seeley (Cyrtocrinus Jaekel; (?) Hemicrinus d'Orb.). Dorsal

CLÄSS III CRINOIDEA 241

cup and proximale fused ; ventral surface bent to one side. Upper Jura and
Lower Cretaceous ; Europe.

Trigonocrinus Bather. Oxfordian ; Europe. Tormocrinus Jaekel. Small
radial facets, rounded interradial spines, and deep cup cavity ; the former has
less than five rays. Eocene ; Europe.

Eudesicrinus Loriol. Stem reduced to two short, thick segments which bear
the five R directly. Arms stout, branching on the first brachial. Lias ; Europe.

Family 8. Holopidae Zittel.

Base monocyclic ; stemless. Dorsal cup beaker-shaped, and formed of five fused
radials, hy which the hody was either directly attached, or more frequently it was
supported hy a solid mass represeniing fused, ^ ^

overgrown or absorbed basals. Tegmen com-
posed of five large triangulär orals sur-
rounded by a narrow band of perisome.
Arms five x two, unbranched, pinnulate,
strongly incurving, and composed of large
thick plates. pj^ g^^.

Of the forms belonging to this family a, h, Cotyhderma docens Deslongch. Upper Lias ;

Colylederma Quenst. (Cotylecrinus Des- & 'i1,™^rv;''.!''''rSX"S? ' tS"?;

long.) (Fig. 346) is found in the Lias: Asselfingen ; Baden, c, Centrodorsal ; </, Circlet of
n Ai • !• Ol, /-»*-• . fused basals. (All figures of the natural size).

tyathidium Steenstrup (Mtcropocnnus

Michelin), in the Cretaceous and Tertiary ; and Holopus d'Orb. occurs both in
the Tertiary of Italy, and Recent in the Caribbean Sea, where it inhabits
shallow water.

Range and Distribution of the Crinoidea.

The discoveries of recent years have brought to light an unexpected
profusion of crinoidal life in the present seas, showing that instead of being
a decadent and expiring race, as hitherto supposed, the Crinoids still con-
stitute a vigorous stock of cosmopolitan distribution. They are represented
by about 650 species, falling into 100 genera, which are distributed among
twenty families and nine additional subfamilies ; about 580 of these species,
included in eighty-five genera and in fourteen families and nine subfamilies,
are unstalked forms or Comatulids, the dominant type of the present fauna,
while about seventy species, included in fifteen genera and six families, are
stalked forms.

The stalked Crinoids attained their maximum development during the
Paleozoic era. Three of the principal Orders — the Camerata, Flexibilia and
Inadunata — are, with the exception of the genus Encrinus, wholly confined to
the Paleozoic rocks, although the characteristics of the two last-named Orders
have continued in more or less modified forms. The Articulata, on the other
band, appear first in the Trias, and are represented continuously to the
present time.

Crinoids, as a rule, have but a very local distribution, but occasional
species are common to two continents ; in certain formations detached stem-
joints and calyx plates occur so profusely as to become of considerable rock-
building importance, and strata aggregating many feet in thickness are fre-
quently met with which are almost whoUy constituted of Crinoid remains.
VOL. I R

242 ECHINODERMATA— PELMATOZOA phylüm iv

While the great majority of Recent stalked forms are deep-sea inhabitants,
the Paleozoic, on the contrary, often characterise shallow water deposits, and
are especially numerous in the vicinity of fossil coral reefs. Of the Mesozoic
Crinoids, the Eugeniacrinidae and Plicatocrinidae, whose remains are commonly
associated with those of Hexactinellid and Lithistid Sponges, probably lived
at considerable depths ; while, on the other hand, the Encrininae, Apiocri-
nidae, Saccocomidae and Holopidae, were undoubtedly shallow water forms.

Crinoidal fragments have been detected in the Cambrian, but consist of
stem-joints only. The Ordovician of England also yields a variety of stem-
joints, and well-preserved calices of Hyhocrinus and Baerocrinus occur in rocks
of the same age in the vicinity of St. Petersburg. In North America, the
Trenton and Hudson River limestones are locally very rieh in Crinoid
remains. The Silurian localities of Dudley, England, and especially the
island of Gotland, Sweden, are famous for the surprising abundance and
exquisite state of preservation of their fossil Crinoids. The Swedish
forms alone comprise forty-three genera and 176 species. The Silurian
of North America, notably the Niagara Group, likewise contains a large
variety of forms, many genera being identical with those of England and
Gotland.

The best-known Devonian localities are the Eifel, Rhineland ; Nassau,
Westphalia ; the Ardennes and Department of Mayenne, France ; the Asturias,
Spain ; and New York, Michigan, and the region about the Falls of the
Ohio River, in North America. The Lower Carboniferous Limestone of Tournay
and Vis6, Belgium, and that of England, Ireland, and the vicinity of Moscow,
Russia, are occasionally charged with exceptionally well-preserved crinoidal
remains. But the most famous of all horizons is the Lower Carboniferous
Limestone of North America, where in particular the localities of Burlington,
Iowa, and Crawfordsville, Indiana, have acquired a world-wide celebrity.

The Upper Carboniferous contains large areas of crinoidal limestone, but
well-preserved specimens occur rarely, the most notable being at Kansas City,
Missouri ; some interesting forms f rom that horizon are found in Australia.
The Permian has yielded but a few genera, and those, so far as yet known,
belong to the Inadunata. A remarkable Crinoid fauna of this age has also
been discovered in the Island of Timor.

^From the Trias only the Encrininae and a few species of Pentacrinus are
as yet known. The remaining members of the Articulata make their appear-
ance in the Jura and Cretaceous, and with the exception of the Eugenia-
crinidae and the Saccocomidae, the families are still represented in the existing
fauna.

[The text for the entire subphylum Pelmatozoa has been revised by Mr. Frank Springer
of East Las Vegas, New Mexico, and "Washington, D.C. The treatment of the classes Cystoidea
and Blastoidea is substantially the same as in the former edition of this work, but that of tlie
Crinoidea reflects the great progress in our knowledge of this group tliat has been made
during the past decade. In that part of the revision which deals with post- Paleozoic Crinoids
Mr. Springer and Mr. Austin Hobart Clark, of the United States National Museum at
Washington, have co-operated with a view toward making the new knowledge of later and
Recent Crinoids more generally available for paleontologists. Lack of space alone prevented
a more detailed discussion of Recent Comatulids, such as had been actually prepared
for the present work by Mr. Clark. The student is therefore referred to the independent
publications of these two well-known echinodermologists. — Editoh.]

CLASs III CRINOIDEA

Table showing the Vertical Range of the Crinoidea.

243

Families.

1

o

'S
o

03

m

1

'S

1

1

1

1

•-3

«

Tertiary.
Recent.

I. Camerata

1. Cleiocrinidae

2. Reteocrinidae

3. Dimerocrinidae

4. Rhodocrinidae

5. Melocrinidae

6. Calyptocrinidae

7. Batocrinidae

8. Actinocrinidae

9. Platycrinidae

10. Hexacrinidae

11. Acrocrinidae

II. Flexibilia

1. Lecanocrinidae

2. Sagenocrinidae

3. Iclithyocrinidae

4. Taxocrinidae

III. Inadun ATA
1. Larviformia

1. Stephanocrinidae

2. Pisocrinidae

3. Haplocrinidae

4. Allagecrinidae

5. Synbathocrinidae

6. Cupressocrinidae
2. Fistulata

1. Hybocrinidae

2. Heterocrinidae

3. Anomalocrinidae

4. Cremacrinidae

5. Catillocrinidae

6. Belemnocrinidae

7. Dendrocrinidae

8. Crotalocrinidae

9. Cyatliocrinidae

10. Botryocrinidae

11. Poteriocrinidae

IV. Articulata

lo Bourgueticrinidae

2. Phrynocrinidae

3. Apiocrinidae

4. Pentacrinidae
(a) Pentacrinids

(&) Thiolliericrinids
(c) Coraatulids ^

5. Plicatocrinidae

6. Saccocomidae

7. Eugeniacrinidae
1 8. Holopidae

1

1

—•

i

i

j

1

.._

'

":i

1

i

i

—

— •

1

j

—

1

i

—

»...

........

i
• 1

-

: !

!

«

!

— ..

?

1

' 1.

i

;

i

—

1

!

\

1 1

i

1

!

i

1

1

ji

1 '

1

!

_^.^

1

L.^

j

-!

Includini' Mt(rs)i

i';,ih

244 ECHINODERMATA— ASTEROZOA phylum iv

SuBPHYLUM B. Asterozoa Leuckart.^

Stemless Echinoderms with depressed, pentagonal or star-shaped body, consisting
of a central disk and five or more rays {or " arms "). Mouth inferior and central in
Position. Ambulacral tube-feet restricted to the under surfaxe of the rays. Internal
skeletal pieces of the ambulacra articulated together like vertebrae, or apposed like the
rafters of a pent-house. Integument coriaceous, strengthened by small, irregulär,
loosely or firmly united calcareous plates, some of which bear spines, protuberances or
papillae, the whole constituting a covering showing the greatest diversity in details.

The Asterozoa comprise the two classes of Asteroidea (Starfish) ; and
Ophiuroidea (Brittle Stars and Basket-fish). In both types the body consists
of a central disk containing the principal viscera, and giving ofF five or more
radiating processes or arms. The radiating ambulacral vessels are protected
by an internal skeleton consisting of a double row of calcareous bodies {ambul-
acral ossicles), the components of each pair being separated and movable to a
slight extent in the Asteroidea, but being welded together so as to form a
series of disks in the Ophiuroidea. The ambulacral grooves are open in the
Asteroidea ; but in the Ophiuroidea they are covered by dermal plates, and
the tube-feet project at the sides of the arms. The integumentary skeleton
sometimes appears leathery on the dorsal surface, but is generally strengthened
by calcareous plates or ossicles some of which usually bear spines or tubercles.

Asterozoans are known as early as the Cambrian era, and haVe a continuous
history onward to the present time. They are of rather rare occurrence as f ossils,
and are f ound chiefly in slaty, calcareous, or arenaceous strata which have been
deposited in shallow water. The Asterozoans are the most homogeneous and
most persistent type of all the Echinodermata. Both the Asteroidea and
Ophiuroidea are represented in the Ordovician and Silurian by well-difFerentiated
forms which do not difFer materially from those now living. The only notice-
able difFerence is that many of the Paleozoic Asterozoans exhibit an alternate
arrangement of the ambulacral ossicles, while in all Recent species these are in
a double row, with the ends directly apposed.

Whether this more or less disjunct and alternating condition of the

vertebral ossicles in Paleozoic Asterozoa is really a primitive feature of

fundamental importance must still be considered an open question. It is

quite possible that the apparent alternation in Paleozoic starfishes is due

to conditions of preservation, or if not, is an inconstant and insignificant

1 Literature : Müller, J., and Troschel, F. H., System der Asteriden. Brunswick, 1842. —
Forhes, E., Monograph of the Echinodermata of the British Tertiaries. Palaeont. Soc, 1852. —
Bülings, K, Figures and Descriptions of Canadian Organic Eemains. Geol. Survey Canada, Decade
iii., 1858. — Wright, T., Monograph on the British Fossil Echinodermata of the Oolitic Formations,
vol. ii., Asteroidea and Ophiuroidea. Palaeont. Soc, 1863-80. — Hall, J., Twentieth Keport on the
New York State Cabinet, 1868. — Quenstedt, F. A., Petrefactenkunde Deutschlands, vol. iv.,.1874-
1876. — Ludwig, H., Morphologische Studien an Echinodermeu. Leipzic, 1877-79. — Neumayr, M.,
Morphologische Studien über fossile Echinodermeu. Sitzungsber. Akad. Wiss. Wien, vol. Ixxxiv.
1881. — Carpenter, P. H., Minute Anatomy of the Brachiate Echinodermata. Quart. Journ. Micro-
scop. Sei., 1881. — Stürtz, B., Beiträge zur Kenntniss paläozoischer Seesterne. Palaeontographica,
vols. xxxii. and xxxvi., 1886, 1890. — Idem, über versteinerte imd lebende Seesterne. Verhandl.
d. naturhist. Vereins Eheinlande, Westphalen, etc., 5th ser. vol. x., 1892. — Sladen, W. P., and
Spencer, W. K., Monograph on British Fossil Echinodermata from the Cretaceous Formations, vol. ii.
Asteroidea and Ophiuroidea. Palaeontogr. Soc, 1891-1908. — Gregory, J. W., The Stelleroidea, in
Lankester's Treatise on Zoology, Part iii., 1900. — Jaekel, 0., Asteriden und Ophiuriden aus dem
Silur Böhmens. Zeitschr, Deutsch. Geol. Ges., 1903, vol. \v.— Bather, F. A., Guide to Fossil In-
vertebrates, etc. British Mus. Publ., 1907. — Schöndorf, F., Über einige Ophiuriden und Asteriden
des englischen Silur, etc. Jahrb. Nassauischen Ver. Naturk., Jhrg. 63, 1910.

CLASS I ASTEROIDEA 245

character, as Gregory has claimed. In Ophiurans, however, it is almost
certain that alternation is a primitive and very important character. The
ventral position of the madreporite in Paleozoic Starüshes and the absence of
mouth shields in Paleozoic Ophiuroids point to an intimate relationship
between the two groups ; and this inference is still further confirmed by our
knowledge of several recent and fossil intermediate forms {Astrophiura^ Pro-
taster ^ Ophiamhix, etc.).

If one places a Starfish or Brittle Star with the mouth uppermost, it will
be Seen that the actinal side corresponds with the tegmen, and the central
disk with the base of a Pelmatozoan. When oriented in this manner, the
Position of the principal organs (ambulacral, circulatory and nervous Systems) is
the same in both groups. The homology between the arms of an Asterozoan
and those of a Crinoid or Cystid, or the ambulacral fields of a Blastoid, can
also hardly be doubted. But efForts to interpret a homology between plates
of the dermal skeleton as developed in either group have been only partially
successful ; the reason being that these structures becanie variously modified
and specialised throughout the difFerent classes at an extremely early period.

A comparison of the ontogenetic stages passed through by the Pelmatozoa
and Asterozoa, so far as at present known, reveals nothing definite in regard
to their close relationship. The Asterozoans are most nearly comparable
with certain of the Cystideans (Agelacrinus and th« Callocystidae). But that
they are the direct descendants of the Cystoidea appears very improbable, for
both geological and morphological reasons. The«fact is, that both types
appear simultaneously and in a high State of development, each being quite
distinct from the other, as far back as the Cambrian.

While it is clear that a well-marked Separation exists between the two
classes of Asteroidea and Ophiuroidea, there is very unsatisfactory evidence
in Support of a third group of equal rank, such as Ophiocistia Sollas or Aulu-
roidea Schöndorf. The genera composing the former may better be retained
among the Ophiurans, while as for the latter, it is difficult to believe that
the characters assigned to it are real. More likely these supposed characters
rest upon a misinterpretation of the material. Fossil Asterozoans seem to
have been preserved in many cases only after the decay or removal of much
or all of the non-calcareous parts. Sometimes apparently the entire abactinal
side has been destroyed. In other cases only impressions remain, chiefly
of the harder parts, and the actual structure cannot be ascertained. It
is not surprising, therefore, that our knowledge of the Paleozoic forms
is still incomplete, and that erroneous interpretations should have been placed
upon some of their structural characters.

Olass 1. ASTEROIDEA Burmeister. Starfishes.i

Asterozoans whose simple and more or less flattened arms are prolongations of
the central disJc, and contain the hepatic appendages of the alimentary canal, as well

1 Literature : Forbes, K, British Fossil Asteriadae. Mem. Geol. Survey, vol. ii., Part ü-, and
Decade iii., 1848 and 1S50.— Salter, J. W., New Palaeozoic Star-Fishes. Ann. Mag. Nat. Hist , 1857,
vol. XX.— (ymy, J. K, Synopsis of the Species of Star- Fish in the British Miiseuni, \%Q^—Sivmio-
loitsch, S., Ueber einige Asteroiden der rheinischen Grauwacke. Sitzunpsber. Wien. Akad., 1871,
vol. Ixiil-Sars, O. 0., Researches on the Structure, etc., of the genus Brisinga. Chnstiana, 18/5.—
Perrier, E., Revision de la collection des Stellerides du Museum d Hist. Nat. de Paris. Arch. de
zool. experim., iv., v., -[ S7 5-7 6.— Agassiz, A. North American Star-Fishes. Memoirs Museum

246 ECHINODERMATA— ASTEROZOA phylum iv

as the generative organs. Ämhulacrol feet disposed in rows along deep open grooves
on the under or actinal surface of the arms.

Starfishes have typically five arms (but in some cases as many as eight,
teil, twenty, forty, or more), which are prolongations of the central disk,
usually not sharply marked off from the same. The integumentary skeleton
consists of plates which are either contiguous with one another along their
edges, overlapping or united in a reticulate fashion, and covered with a leathery
skin. The calcareous plates often bear movable spines, or they may be
tuberculated or granulated. Modified spines with a special function and
called pedicellariae are found in most Asteroidea and are often conspicuous.
They never occur in Ophiurans or Holothurians, and are not known among
Pelmatozoa, but what appear to be homologous organs occur in nearly
all Echini. The abactinal surface usually exhibits a central or sub-
central anus, and also a madreporite, which is situated in one (rarely two
or more) of the interradii. The madreporite is covered with labyrinthic
furrows, and is perforated for the admission of water into the so-called ston^
canal, whence it is conveyed into the water-vascular ring surrounding the
mouth. The protrusive caecal processes (papulae), which in the more
primitive forms are restricted to the dorsal surface, but in the more specialised
are distributed over the whole body, serve as respiratory organs, the body
fluids being brought into close contact with the oxygenated water.

The mouth occupies the centre of the ventral surface, and is pentagonal in
contour, owing to the projection of five pairs of interradially disposed oral

plates. Each of the arms is traversed on

^ ^ /k A the under or oral side by a broad and deep

»^^ J|j_.W furrow, which tapers gradually in passing

^^0 TO tii) from the mouth to the tip of the arm, where

Fig. 348. it is termiuatcd by a simple grooved plate

oJar'pils „f \^rTSä^i,rAt(^JS- im l<^i}^ät}^oeular plate. The roof
Pentago7Mster(^) irom tagonaster (?) from of each ambulacral furrow IS formed bv two

the Upper Jura of the Upper Jura of jr r^ ti ^i i j. z

Streitberg. 2/^. Streitberg. i/j. rows Ol raiter-like, rather elongate, ambu-

lacral ossicles, the inner ends of which are
held together by muscles (Figs. 348-350). Eunning along the centre of the
groove on its ventral side are placed in succession the radial water -tube,
blood-vessel and nerve cord. These are all homologous with the like-named
organs of Ophiuroids.

The form of the ambulacral ossicles difFers in diiferent genera. In all
Recent forms the ends are directly apposed against one another in the median
line of the ambulacral grooves ; but in Paleozoic forms they were apparently
arranged in alternate rows, and inclined towards one another at a very small
angle. Each pair of ambulacral plates is excavated at the sides, so as to give

Comp. Zoölogy, Cambridge, v., 1877.— Viguier, C, Anatomie comparee du squelette des Stellerides.
Arch. de zool. experim., vii., 1878.— Sladen, W. P., Eeport on the Asteroidea. Scient. Kesults,
Challenger Expedition, 1889, vol. xxx.—Fraas, E., Die Asterien des weissen Jura. Palaeonto-
graphica, 1886, vol. xxxii.— Gregory, J. W., On Lindstroemaster and the Classification of the
Palaeasterids. Geol. Mag., 1899, dec. 4, vol. vi.—Linstow, 0. v ., Zwei Asteroiden aus mär-
kischem Septarienton, etc. Jahrb. k. Preuss. Landesanst., 1909, vol. xxx. pt. 2.— Schöndorf, F.,
Die Organisation und systematische Stellung der Sphaeriten. Arch. f. Biontologie, 1906, vol. i.
— Idem, Paläozoische Seesterne Deutschlands. Palaeontogr. 1909-10, vols. Ivi., Ivii. — Ide7n, Die
fossilen Seesterne Nassaus. Jahrb. Nassauischen Ver. Naturk., Jahrg. 62, 1909.— Jludson G. ff.,
A fossil Starfish with ambulacral covering plates. Ottawa Nat., 1912, vol. xxvi.

I rise bv

ASTEROIDEA

247

rise by their apposition to a series of small apertures, through which the
distensible tube feet or pedicels are emitted. The latter are the downward

md

ad^ mir.

Fig. 349.

Astropecten aurantiacus (Linn.). Recent;
Mediterranean. Enlarged vertical section of
one of the arms. am, Ambulacral ossicles ;
ad, Adambulacral i)late ; mv, Infero-marginal
plate ; md, Supero-marginal plate ; i, Super-
ambulacral plate.

aa.

FiQ. 350.

Asterias ruhens Linnaeus, Recent ;
German Ocean. Enlarged vertical
section of one of the arms. am, Am-
bnlacral ossicles ; ad, Adambulacral
plates ; mv, Infero - marginal plates ;
a, Radiating water-tube ; b, Ampullae ;
p, Tube-feet.

prolongations of lateral branches given off by the radial ambulacral vessel ;
the upward prolongations of the same form small sacs called ampullae, by
means of which water is forced into the tube feet.

The lower ends of the ambulacral ossicles rest against a series of
adambulacral plates, and in many forms these are bounded in turn by large
marginal plates (Fig. 349). Intermediate plates are those which are inserted
between the infero-marginal plates and the adambulacral plates. By the
term dorsal plates are understood all calcareous bodies occurring on the dorsal
side of the body.

Perfectly preserved Starfishes are known only from a few localities, such as
Bundenbach in Rhenish Prussia, the usual mode of occurrence being in the form
of moulds, or detached plates. The earliest forms are found in Cambrian rocks.

There is no generally accepted Classification of the Starfishes. Not only
do specialists disagree as to the Orders and families, but tjiere is the widest
divergence of opinion as to the principles upon which the Classification should
be based. Unfortunately none of the zoologists who have in recent years
attempted to formulate a Classification for the group, except Sladen,.has taken
fossils into account, and even Sladen was inclined arbitrarily to separate
Paleozoic and Recent forms. The latest authority, Fisher, accepts three
Orders but does not consider their limits as satisfactorily determined. The
study of Recent forms has shown that the characters of the tube-feet,
reproductive organs and other soft parts are of real importance in determin-
ing family limits, and that the pedicellariae are possibly of even ordinal
importance, hence it is exceedingly difficult to intercalate fossil Starfishes in a
Classification of the living forms. As has been suggested above, Gregory is
very possibly correct in his view that the alternation of the ambulacral
ossicles cannot be considered of fundamental importance, but may often be
only a result of pressure during fossilisation. It certainly ought not to be
used to isolate all Paleozoic forms, or most of them, in a class by themselves.
One character upon which stress was first laid by Sladen has come to be
generally regarded as of fundamental importance, i.e. the size and appearance
of the marginal plates. The genera in which these plates are large and
conspicuous have the papulae confined to the space bounded by the upper
series or supero-marginals ; and this group, called Phanerozonia by Sladen, is
now quite generally accepted although its exact limits, at least among living

248

ECHINODERMATA— ASTEROZOA

PHYLUM IV

Starfishes, are still uncertain. All other Starfishes may be grouped, as was
done by Sladen, in a contrasting order, Cryptozonia ; but this is probably not
a natural group, and Fisher distinguishes two divisions. These, however, are
separated by characters not ascertainable in Paleozoic remains, and for practical
purposes, the paleontologist may well accept the Cryptozonia.

Order 1. PHANEROZONIA.

Asteroidea in which the marginal plates are large and conspicuous; papulae
nearly always confined to the dorsal surface; amhulacral ossicles not crowded, and
tube feet in two rows in each amhdacral groove.

This Order includes a large proportion of the Paleozoic and Mesozoic
Starfishes, besides numerous Eecent genera. Fisher groups the Eecent forms
in no less than a dozen families, and Gregory gives four others for Paleozoic
species alone. Many of the Recent families are not known as fossils, and
others may have one or a few extinct representatives. The most important
families and genera from a paleontological point of view are the following.

Family 1. Palaeasteridae.

The typical members of this family have the ambulacral ossicles more or

less completely alternating. The adambulacral plates are most conspicuous

B in the mouth parts. The

marginal plates and many
of the abactinal plates are
conspicuous.

The exact limits of this
family are hard to determine,
as the known forms are all
from the lower Paleozoic.
The typical genus Palaeaster
Hall (Fig. 351) is known
from both Europe and
America. Hudson has re-
cently proposed a new order
and family for an interesting
S t a r fi s h (Protopalaeaster)
from the Ordovician rocks of
Canada. It is, however,
probably allied to Palaeaster.
The plates which Hudson
calls epineurals are probably
the amhdacrals seen from within, the dorsal side of the animal being lost.

Several genera allied to Palaeaster have been described (Petraster Billings ;
Ärchasterias Müller ; Argaster Hall ; Ataxaster Jaekel, etc.), while other less
typical forms (Xenaster Simonowitsch ; Tetraster Eth. and Nich.) have been the
subject of debate as to their true position. Whether Lindstroemaster Gregory
is properly referable to this family is not certain ; it bears considerable super-
ficial resemblance to the Goniasteridae.

Fio. 351.
Palaeaster eucharis Hall. Devonian ; Hamilton, New York. A
Ventral aspect, natural size. B, Dorsal surface of one of the arnis
C, Diagrammatic view of ventral surface of the arms (after Hall).

CLASS I

ASTEROIDEA

240

Family 2. Astropectinidae.

This is one of the largest families of Recent and Mesozoic Phanerozonia,
about twenty Recent genera being known. The ambulacral ossicles are
opposite but that seems to be the only difference from the Palaeasteridae.
The type-genus, Astropecten Gray (Fig. 349), occurs in the Lias and later
Mesozoic, and is still a large and widespread genus. It is quite possible that
some Paleozoic forms are nearly related, if not actually congeneric, as for
example, Astropecten schlüteri Stürtz, from the Devonian. The lower Silurian
Siluraster Jaekel is also very probably one of this family.

Family 3. Aspidosomatidae.

This family is characterised by alternate ambulacral ossicles and large
interradial areas. The rays are more or less petaloid or tapering, and the
disk is large. All of the known ^ c;

forms are from the Paleozoic and
their structure is not only incom-
pletely known, but there is the
widest difference of opinion in inter-
preting such characters as are dis-

tinguishable. The type - genus ^'<255ig^öifc^tfQJiiMttÖ?SyMBiKI^^ i b
Aspidosoma (Fig. 352) has been
very carefully studied by Schön-
dorf. As a result of these studies,
he proposed a new class called
Auluroidea. The structure of
Aspidosoma shows, however, that
it is probably a phanerozonate Star-

fish. Allied genera are Falaeonectria ^^^^^^^^^ petaloüUs Simon. Lower Devonian; NieHler-

and PalaeOStella Stürtz, and Tricha- lahnstein, Nassau. ^, Ventral aspect natural size^ Arm

. ' viewed from the dorsal side. "^ a7„„4.™i *■ ^f „^r„

steropStS Eck. enlarged (after Simonowitsch).

C, Ventral aspect of arm,

Pentagonaster (;!)
impressns (Quenst.).
Upper Jura ; Reiohen-
bach im Thäle. A,
Supero - marginal
plate. B, Infero-
inarginal plate. C,
Plate with supposed
pedicellariae (after
Quenstedt).

Family 4. Taeniasteridae.

In this family, which is also confined to the Paleozoic,
the disk is very small and the rays are long and tapering.
The adambulacral plates are large and marginal in position.
The marginal plates bear spines on their free ends. The
principal genera are Taeniaster and Stenaster Billings, from
the Lower Silurian of Canada, and Saiteraster Stürtz, from
the Silurian of England. Perhaps Protasteracanihion Stürtz,
from the Devonian of Germany, also belongs here.

Family 5. Goniasteridae ( = Pentagonasteridae).
These Starfishes are generally recognisable by their flattened
form, Short rays, very large disk, and very conspicuous
marginal plates. The family is a large one, with more than
forty Eecent genera, and its limits are ill defined. It first appears in the
Jurassic, and it is well represented in Cretaceous strata. The genus Pentagmiaster

250

ECHINODERMATA— ASTEROZOA

PHYLÜM IV

Gray, was monotypic when described, and as now limited probably contains
no fossil forms ; but a considerable iiumber of species and frägments (Figs.
347, 348, 353) from the Mesozoic have been referred to it. An allied genus,

Fig. 354.
Lower Chalk ; Sussex. A, Ventral aspect.

B, Viewed from one side

Metofiaster parkinsoni (Forbes).
(after Forbes).

Metopaster Sladen (Fig. 354), is represented by numerous species in the
Cretaceous rocks of England. Other Cpetaceous genera are Pycinaster Spencer,
and Mitraster Sladen, while Leptaster -de Loriol is f ound in Jurassic strata.

Siihaerites scutatus Gold f.
Upper Jura ; Sontheim,
Würtemberg.

A, Oreastef Jurassims (Zitt.). Upper Jura ; Bemfeld, near Ingolstadt,
Bavaria. ^f^. B, 0. thoracifer (Gein.). Pläner ; Plauen, Saxony.
Marginal plate. C, 0. primaevus (Zitt.). Upper Jura ; Streitberg.

A, Sphaerites tahulatus
Goldf. B, Sphacr. punctatus
Goldf. Upper Jura; Streit-
berg, Franconia.

Several Recent genera, such as Calliderma Gray ; Nymphaster Sladen ;
Comptonia Gray, have been thought to have Cretaceous representatives, and
there is little reasori to doubt that many Cretaceous Starfishes of this family
were congeneric, at least in a broad sense, with those of to-day.

CLASS I ASTEROIDE A 251

I'amily 6. Oreasteridae (wrongly Pentacerotidae).
This family includes some of the largest Eecent Starfishes, characterised by
a massive skeleton, with large, though sometimes concealed, marginal plates.
Conspicuous spines or tubercles are commonly found on the abactinal plates.
The type genus Oreaster M. and T. (wrongly Fentaceros) (Fig. 355), is wide-
spread in shallow water in the tropics, while geologically it is known at least
as early as the Upper Jura. Numerous species of this genus occur in the
Cretaceous. Arthraster Forbes, and Stauranderaster Spencer, from the British
'^retaceous probably belong to this family.

Family 7. Sphaerasteridae.
Isolated plates, to which Quenstedt gave the name Sphaerites, from the
Jurassic rocks of Germany, France and Switzerland, have long puzzled
paleontologists, but Schöndorf has recently shown that they belong to certain
remarkable Starfishes, which he calls Sphaeraster, allied to the Oreasteridae.
In some cases (Fig. 356) the plates bear large spines, but in others they are
simply punctate (Fig. 357), or quite smooth. The animal was high hemi-
spherical in form, and the large ones were 25 cm. in diameter. They seem to
have been confined to Jurassic seas.

Order 2. CRYPTOZONIA.

Asteroidea in which the marginal plates are small and inconspicuous ; papulae
distrihuted on the oral surface ; amhulacral ossicles are often crowded and tube-feet
may he infour rows in each groove.

Between fifteen and twenty families of cryptozonate Starfishes are now
recognised, but the great bulk of these are Recent forms. The order is rare in
the Paleozoic, and the structure of those forms which are referred to it is im-
perfectly known. Accordingly, their systematic position is doubtful. The
genus Palasterina M'Coy (Cambrian to Devonian ; Europe and North America)
is regarded by some writers as cryptozonate and by others as phanerozonate.
It is probably related to Asterina Nardo, a widespread Recent genus, which
Sladen considered phanerozonate, other writers to the contrary notwith-
standing. The genera Palaeocoma, Bdellacoma and Bhopalocoma Salter are
probably Cryptozonia but their family position is very doubtful.

Lepidaster Forbes, of uncertain affinities, is an interesting Silurian genus
with large disk and thirteen rays. Ethendgaster Gregory, from the Carboni-
ferous of New South Wales, is considered by its describer as a related genus,
although it has only five rays and was originally regarded as a Palaeaster.
Medusaster Stürtz is notable for having fourteen rays, and Helianthaster Roemer
is another remarkable form with sixteen rays. The latter has been regarded
by some as a Starfish and by others as an Ophiuran ; it is probable that it
belongs in the Cryptozonia, but most unlikely that it is related to the Recent
South American Heliaster.

It is possible that the Recent family Linckiidae isrepresented in the Devonian
by Roemeraster Stürtz, but the relationship is very dubious. The genera
Palasteriscus and Echinasterella of Stürtz from the Devonian are said to have the
madreporite on the oral side, which would alone render them worthy of note.
Loriolaster and Cheiropteraster Stürtz, also from the wonderful Bundenbach
slates, are possibly allied to the Recent Pterasteridae. Mesozoic and Tertiary

252

ECHINODERMATA— ASTEROZOA

PHYLÜM IV

Cryptozonate Asteroids are very rare. The Recent genus Solaster Forbes is
represented by a species with numerous arms in the Great Oolite of England.
Two important families of Recent Cryptozonia are the Echinasteridae and
the Asteriidae. A species of Echinaster M. and T. has been described from
the Neocomian, and Forbes thought he found in the Red Crag of England
remains of the now common Asterias ruhens Linn. It is stränge that no good
evidence has been found of the occurrence of Asterias in Tertiary strata.

Olass 2. OPHIUROIDEA Gray. Brittle Stars.i

Asterozoans having a more or less sharply defined central disk containing a simple
digestive cavity which does not radiale into the slender rounded arms, and has no anal
opening. Reprodudive organs confined to the disk. Arms with an axis composed of
calcareous Joint s, the elements of which are usually fused to form ^^ vertebral ossicles"
encased with plates or covered with a leathery skin, and very rarely with open
ambulacral grooves. Madreporite constantly on the actinal {oral) side of the disk.

AB D

Fig. 358.
A, Vertical section of an Ophiuran arm. w, Vertebral ossicle ; a, Ambulacral vessel, witli side-branches lead-
iiig into the tube-feet ; h, Blood-vessel ; tc, Nerve-cord ; v. Ventral or lower arm-plate ; I, Side-plates ; d. Dorsal
plate. B, Vertebral ossicle, seen from the inward side, with surrounding arm-plates. C, Row of vertebral
ossicles viewed from the side, and slightly enlarged ; x, Apertures where the branches of the ambulacral vessel
enter and emerge from the arm-bones ; i/, Depressions for the Insertion of intravertebral muscles. D, Mouth-
frame of an Ophiuran, with the proximal vertebral ossicles. The heavy lines bordering the arms represent the
genital slits ; the dark pentagon in the centre marks the course of the nerve-ring.

Ophiuroids are distinguished from the typical Starfishes by their cylin-
drical flexible arms, which are sharply separated from the central disk, and

1 Literature : Lütken, C. F., Additamenta ad historiam Ophiuridarum. Köngl. dan. Vidensk.
Selskabs Skrifter, v. and viii., 1858-69. — Lyman, T., Ophiuridae and Astrophytidae. Illustr. Cat.
Mus. Comp. Zool. Cambridge, Nos. i.-iii., 1865. — Ludwig, IL, Beiträge zur Anatomie der
Ophiuren. Zeitschr. für wissensch. Zool., vols. xxxi., xxxiv., 1878-80. — Ludwig, H., Morphologische
Studien an Echinodermen. Leipzic, 1877-79.— Lyman, T., Report on the Ophiuroidea. Challenger
Expedition, Zoology, vol. v., 1882. — Picard, K., Über Ophiuren aus dem oberen Muschelkalk.
Zeitschr. deutsch, geol. Gesellsch., vol. xxxviii., 1886. — Boehm, G., Beitrag zur Kenntniss fossiler
Ophiuren. Berichte naturf. Gesellsch., Freiburg, v., 1889. — Gregory, J. W., On the Classification
ofthe Palaeozoic Echinoderms of the gTOup Ophiuroidea. Proc. Zool. Soc, London, 1896. — Sollas,
W. J., On Silurian Echinoidea and Ophiuroidea. Quart. Journ. Geol. Soc. , 1899, vol. Iv. — Hainann,
0., Die Schlangensterne. Buch iii., Abt. 3, Bd. 2, of Bronn's Klassen und Ordnungen des Tier-
reichs, 1901. — Strassen, 0. zur, Zur Morphologie des Mundskelettes der Ophiuriden. Zool. Anz.,
1901, vol. xxiv. — Jaekd, 0., Ästenden und Ophiuriden aus dem Silur Böhmens. Zeitschr. Deutsch.
Geol. Ges., 1903, vol. Iv. — Parks, W. A., Notes on the Ophiuran genus Protaster. Trans. Canad..
Inst., 1909, vol. viii. — Sollas, L B. J. and W. J., Lapworthura : A typical Brittle-star of the
Silurian Age. Phil. Trans., 1912, vol. ccii.

JLASS II

OPHIUEOIDEA

253

I

^■Üo not contain diverticula of the alimentary canal nor of the sexual organs.
The arms serve as locomotive organs, and are either elegantly plated
or protected by a coriaceous skin, in which minute granules and scales are
embedded. When plated, the covering consists typically of four rows of
calcareous plates, known as the upper, lower and side arm-plates (Fig. 358, A).
The lateral or adamhulacral plates usually carry rows of mobile spines.

The greater part of the interior of the arms is occupied by a linear series of
jointed, vertebra-like sections called the vertebral ossicles or arm bones, each of
which is made up of two, or possibly of four, ambulacral pieces soldered side
by side (Fig. 358, B, C). The halves of the first two vertebral disks are swung
laterally into the interbrachial space, being fused together to form the mouth
angle. The remainder of the arm-bones are movably articulated with one
another by means of bosses which project from the centres of both surfaces,
the interspaces being fiUed with muscles. The entire series is incised inferiorly
along the median line for the reception of the radial water-tube, beneath
which runs the radial blood-vessel and nerve cord, the whole being closed in by
the integument. The radial ambulacral vessel (water-tube) gives off a pair of
lateral branches in each arm ossicle which pierce the bone itself, and supply

Fig. 359.

Portion of central disk of Ophiura viewed
from the dorsal side. a, Radial shields ;
h. Upper arm-plates ; c, Side arm-plates.

Portion of central disk of Ophiura
viewed from the ventral side. a, Mouth
shield ; b, Side mouth shield ; c, Jaws
bearing papillae ; g, Genital slits ; h, Side
arm-plates ; %, Pores for the emission of
the tube-feet, surroimded with tentacle
scales ; k, Spines.

the tentacle-like tube-feet with water. The tube-feet are without either
arapullae or terminal suckers, and the orifice of the plates through which they
protrude is often protected by one or more minute tentacle scales (papillae
amhulacrales), which serve to cover the tentacles when they are drawn in.

On the under side of the disk is seen the central, star-shaped aperture of
the mouth (Fig. 363), which leads into a large sac-like stomach. The latter
terminates blindly, there being no intestine. The body cavity also contains
the ambulacral, blood and nerve rings, as well as the generative glands, whose
ducts open into folded pouches or bursae. The bursae are arranged in five
pairs, one to each interbrachial area, and communicate with the extenor by
means of slit-like fissures (genital slits), which skirt the arm bases mferiorly,
and are bounded by genital or bursal scales. Sometimes the fissures are
discontinuous (Ophioderma), appearing as two slits, one behind the other ; and in
some fossil forms they are represented by rows of pores. ^ ,. . , ,

The integument covering the entire upper surface of the disk and the
interbrachial area on the ventral side is frequently beset with calcareous
plates : but this scale coat may be covered in turn with a thick skin, or bear
spines or granules. A large central plate is sometimes recognisable on the
dorsal aspect of the disk, together with five pairs of plates, which, from their

254 ECHINODERMATA— ASTEEOZOA phtlum iv

Position at the points of origin of the arms, are called radial shields
(Fig. 359). On the ventral surface of the disk, the inner angle of each
interbrachial space is occupied by a single large plate termed the mouth
shield {scutum buccale) (Fig. 360), one of which serves as the madreporic body.
But in the Cladophiuroida the mouth shields are often feebly developed, or may
be wanting altogether ; and in place of them a madreporite is f ound in one or
all of the interrays. The mouth shields are bounded proximally by a pair of
somewhat smaller plates called the side mouth shields. Finally, within the
side mouth shields, and usually pressing against them, are the jaws which are
sometimes covered by the skin or by granulations (Fig. 360). Teeth are
constantly present, being attached to the jaw-plates by small muscles, and
other tooth-like processes (tooth-papillae and oral-papillae) are generally present
at the inner angle or along the sides of the jaws.

A natural Classification of the Ophiuroidea remains to be established.
Those who have worked principally on Eecent forms have not, as a rule,
proposed any completed System ; and so while our knowledge of the number
and variety of Eecent species has increased enormously, no progress has been
made toward a rational arrangement of the class. On the other band, some
valuable work by paleontologists has been vitiated by ignorance of the Eecent
forms, while the difficulties of the material with which such work must be
done has led to radical differences of Interpretation and opinion.

The proposed groups Protophiuroidea and Euophiuroidea may be natural
divisions, but as the character upon which the class is differentiated is the struc-
ture of the arm and the development of " vertebral ossicles," the Classification
proposed by Bell and elaborated by Gregory may better be adopted as a
basis for further study. Under this system four Orders may be recognised,
but family limits are uncertain and unsatisfactory. The termination of
Gregory's ordinal names is altered to end in -oida.

Order 1. LYSOPHIUROIDA.

Ophiuroidea in which the vertebral ossicles are incomplete, the two halves not
being united, but separate and alternate. There are no ventral arm-plates ^nd thus
a more or less distinct ambulacral furrow is present.

This Order includes a group of Paleozoic Asterozoans, intermediate
between Ophiurans and Starfishes. They differ from the latter only in the
general form, the arms being sharply set off from the disk, but probably the
alimentary canal and reproductive organs were confined to the disk. The
characters of the ambulacral plates are often uncertain, but they may be
either subquadrate or " boot-shaped." The character of the mouth-parts in
this Order and the next has been well worked out by the Sollases, and their
primitive character clearly shown. The principal genera are Protaster Forbes
from the Silurian, and Bundenhachia and Palaeophiura Stürtz, from the Devonian
of Europe. The Ophiurans from the Lower Silurian strata of Bohemia,
whose structure is discussed by Jaekel, are undoubtedly members of this
Order. The most important genus is Bohemura.

Order 2. STREPTOPHIUROIDA.

Ophiuroidea in which the vertebral ossicles are more or less complete, and in
any case, the two halves are opposite. The ossicles articulate with each other by ball-

CLASS II

OPHIUROIDEA

255

and-socJcet joints. The arm-plates are more or less completely developed and the side
arm-plates may carry spines. Arms may he very short with relatively enormous
tuhe-feet, as is apparently the case in Eudadia.

This Order includes a number of Paleozoic forms and not a few Recent
species. Important genera are Ophiurina Stürtz, Devonian, with separate am-
bulacral ossicles and no ventral arm- ^

plates; Lapworthura Gregory, Silurian,
with barely fused ambulacral ossicles,
and no ventral arm-plates ; Sympterura
Bather, Devonian, similar to Lap-
worthura, but with narrower rays and
spinulose disk ; and Eoluidia Stürtz,
Devonian, with fused ossicles, and with
ventral arm-plates. The genus Ony-
chaster Meek and Worthen (Fig. 361),
Lower Carboniferous, has usually been
regarded as representative of the

mndprn Enrvalid«? hnt thp oharaofpr ni OnychasterßexiUsM. and W. Lower Carboniferous ;
moaern JLUryaiiaS, DUÜ tne Cnaracter OI Crawfordsville,Ind.(after Meek and Worthen). ^,In-
the ambulacral ossicles necessitates itS dividual of the natural slze with rolled up anns ;
, . . - . , ^, 111 ^'^^ dorsal covering of the central disk is removed,

incmSIOn m tniS Order. ine remarkable exposin^ the mouth frame. B, Mouth frame enlarged,

Silurian genera Eudadia Wood ward, and ""'"'''^ ''"'" "^"^'^ ' ^^' '''''^''^"' ''''''''' ^"^"^«^•
Euthemon Sollas, are exceedingly difficult to place, and their relation to other
Ophiurans is problematical.

Fig. 361.

Order 3. CLADOPHIUROIDA.

Ophiuroidea in ivhich the vertebral ossides are complete and articulafe with each
other hy means of hoiirglass-shaped surfaces. The arms are oflen dichotomously
branched and lack regulär series of arm-plates.

This Order includes a large number of Recent forms, those with branched

FiQ. 362.
Aspidura loricata (Goldfuss). Muschelkalk ; Waschbach, Würtemberg
natural size (after Quenstedt).

A, ßroup of individuals of the
B, Ventral aspoct, enlarged (after Pohlig).

arms (Astrophyton, Gorgonocephalus, Euryale) being known as " Basket-fish " or
" Sea-spiders." Fossil forms are rare, but certain Mesozoic remains of doubt-
ful Position have been referred to the Recent genera Astrocnida and Euryale.
Onychaster, the Streptophiuran referred to above, has peculiarities that suggest

256

ECHINODERMATA -ASTEROZOA

PHYLUM IV

this Order, but the form of the ossicles certainly seems to exclude it.
Moreover, Eudadia, so far as its structure is known, is capable of very diverse
interpretations, and the possibility that it is a Starfish rather than an
Ophiuran, must not be wholly ignored.

Order 4. ZYGOPHIÜROIDA.

Ophiuroidea with simple arms, perfeäly regulär series of arm-plates and vertehral
ossicles fully developed. The movement of the ossicles on each other is greatly limited
hy the development of lateral processes and pits on their articulating surfaces.

This Order includes the great bulk of the Kecent Ophiurans as well as
^ those of the Mesozoic and Tertiary.

Indeed some of the Recent genera seem
to have been difFerentiated as far back
as the Jurassic, and Ophioderma appar-
ently occurs in the Triassic. No
Paleozoic forms can certainly be re-
ferred to this group.

The genera Aspidura (Fig. 362)
and Acrura Agassiz are occasionally
abundant in the German Muschelkalk,
and certain Liassic Ophiurans were
also, like many Recent species, notably

Ophiocten kelhevnunse Böhm. Lithographie Stone ; gregarioUS. In the Lower, Middle

Kelheim, Bavaria. A, Ventral aspect of disk. B, i TTnr^pr Tnrn nrA fminrl "Rrifflp {^fnr«

Dorsal surface of one of the arms. (Both figures en- ^^^^l Upper ÜUra are lOUnÜ i^rittlC ötarS

larged ; original in Munich Museum.) closely allied tO the RcCCnt OpMolcpis

A B

Fig. 364.

Geocoma carinata Goldf. Lithographie Stone ; Zandt, near Solenhofen, Bavaria. A, Individual of the
natural size. B, Dorsal aspect of disk, showing granulations and central depression. C, Ventral surface of one
of the arms. (Figs. B and C enlarged.)

M. and T. ; Ophiocten Ltk. (Fig. 363); Ophiura Lamk. (Figs. 359, 360); and
Ophiomusium Lyman. It is possible that some of these are really congeneric
with Recent species. The Mesozoic genus Geocoma d'Orb. (Fig. 364) is related
to the Recent Amphiura Forbes, but there can be little doubt that some of
the species referred to it are based on material which cannot be determined
so precisely. Lütken considers Ophiurella elegans Ag., from the Lithographie
Stone of Solenhofen, to be a member of the Recent genus Ophiocoma Ag., but

CLASS I ECHINOIDEA 257

it is doubtful whether it may not be quite as properly assigned to oiie of
several other genera. Other Jurassic and Cretaceous forms have been
assigned by Lütken to Ophium Lamk. (Ophioglypha Lym.), and there is good
reason to believe that the genus, in a broad sense, is one of the oldest now
living. Fossil Ophiurans, whose disk-covering or mouth parts cannot be
determined, ought not to be assigned to Recent genera, but all such and all
others which cannot be accurately characterised may well be designated by
the broad term Ophiurites.

[The text for the foregoiiig section on Asterozoa has been revised for the present work
by Dr. Hubert Lynian Clark, of the Harvard Museum of Comparative Zoology, at Cambridge,

Massachusetts. — Editor. ]

SuBPHYLüM C. Echinozoa Leuckart.

Armless and non-pedunculate Echinodermata, with glohular, cordiform, discoidal
or worm-like bodies, which are either encased in a plated fest or are invested with a
leathery integument, emhedded within which are small-sized detached calcareous bodies.

Olass 1. ECHINOIDEA Bronn. Sea-Urchin8.i

Animals possessing a wide ränge of structure, but haxing alimentaiy, reproductive,
nerve and water vascular systeins within an enclosing superficial pentamerous plated
skeleton, which bears movable spines. There are front two to twenty columns of plates
in each of the five ambulacral areas, and from. one to fourteen columns of plates in

1 Literature : Agassiz, L., and JJesor, E., Description des echinides fossiles de la Suisse, 1839-
1840. — Catalogue raisonne des familles, genres, et des especes de la classe des echinides. Aun. des
Sei. Nat., 1846-47. — cfOrUgny, A., Paläontologie fran^aise. Terrains cretacos 1853-55, vol. vi. —
Cotteau, G. H., and Triger, Echinides du departement de la Sarthe, 1857. — l)es(yr, E., Synopsis
des echinides fossiles. Paris, 1858. — Wright, T., Monograph on the British fossil Echinodermata
of the Oolitic Forniations. Palaeontograph. Soc, 1857-78.— /f^em, Cretaceous Formations. Palaeont.
Soc, 1864-82. — Cotteau, G., Paleontologie franfaise, vols. vii. , ix. and x., 1862-79. — Laube, G. C,
Echinodermen des vicentischen Tertiärgebietes. Denkschr. Akad. Wiss. Wien, vol. xxix., 1868.
— Loriol, F. de, and JJesor, E., Echinologie helvetique, vols. i.-iii. Geneva, lS%9i-%h.—Qnenstedt,
F. A., Petrefractenkunde Deutschlands (vol. iii., Echinideu), 1872-75. — Agassiz, A., Revision of
the Echiui. 111. Cat. Museum Comp. Zool. Cambridge, No. 7, 1872-74.— Reports on the Echini
of the Hassler (1874), Challenger (1881) and Blake (1883) Expeditions.— Z^^m, S., Etudes sur les
echinoidees. Svensk. Vetensk. Akad. Handl., vol. xi., 1874. — Cotteatc, Peron, and Gauthier,
Echinides fossiles de l'Algerie. Paris, 1876-91.— Loriol, P. de, Monographie paleontologique, etc.
Abhandl. Schweiz. Pal. Gesellsch., 1876-81, vols. iii., \m.— /James, W., Die Echiniden der
vicentischen und verouischen Tertiär-Ablagerungen. Palaeontographica, 1877, vol. xxv. — Agassiz,
A., Palaeontological and Embryological Development. Proc. Amer. Assoc. Adv. Sei., 1880.
—Duncan, P. M., and Sladen, W. P., Monograph of the fossil Echinoidea of Western Sind.
Palaeont. Indica, Ser. xiv., 1882-84:.— Schlüter, C, Die regulären Echiniden der norddeutschen
Kreide. Abhandl. zur geolog. Special-Karte von Preussen, vol. iv., 1883.— Jdem, Neue Folge,
Heft 5, 1892. — Loriol, P. de, Description des echinides. Commission des travaux gcol. du Portugal,
1887-88, vol. iu—Loveu, S., On Pourtalesia. Svensk. Vetensk. Akad. Handl., 1884, vol. xix.—
Pomel, jV. A., Classification mcthodique et genera des echinides Vivantes et fossiles, 1883.— Duncan,
P. M., Revision of the Genera and Great Groups of the Echinoidea. Joum. Liun. Soc, 1889,
vol. yix\\\.—Loven, S., Echinologica. Bihang tili Svensk. Vetensk. Akad. Handl., 1892, vol.
xvm.— Clark, W. B., Mesozoic Echinodermata of the United States. Bull. U.S. Geol. Survey,

No. 97, 1893. Tornqnist, A., Das fossil führende Untercarbon am östlichen Rossbergmassiv

in den Südvogesen, iii., Beschreibung der Echiniden- Fauna. Abhandl. Geol. Special-Karte Elsass-
Lothringen, 1897, vol. v. — Mortensen, T., Slam Echinoidea. Danske Vidensk. Selsk. Skrift.,
1904, vol. i. — Bather, F. A., Triassic Echinoderms of Bakony. Resultate der wiss. Erforsch. Bala-
tonsees, 1909, vol. l— Lambert, J. and ThiSry, P., Essai de nonienclature raisonne des echinides.
Chaumont, 1%Q9-Vl.-J<'cksnn, R. T., Phylogeny of the Echini. Mein. Boslon S,.r. Xat. llist.,
1912, vol. wn.—IL'wkliis, II. />., Chissification of tlie Holectyponla. itc 1»i.m-. /,„,!. >,„•.
London, 1912.

VOL. I ^

268

ECHINODERMATA— ECHINOZOA

PHYLUM IV

each interamhulacral area. New coronal plates are formed at the ventral border of
the five ocular plates, ambulacral pores pass through amhulacral plates, rarely
(Clypeastroids) in part hetween plates.

The peristome is on the under or actinal surface, and in all but the
Exocycloida bears from one to many rows of ambulacral plates with or with-
out non-ambulacral plates. There are five oculars (apparently in part or
wholly wanting in some of the Pourtalesiidae), and five genitals or fewer, the
whole being fused into a mass in certain types of Exocycloida. The genitals
typically have each one or more pores as exits of the interradiaÜy situated
reproductive glands. In addition, typically, madreporic pores exist in genital
2, but are not recognizable in most Paleozoic forms. The periproct is more
or less plated, situated within the oculogenital ring, or in irregulär types out-
side of that area in the posterior interambulacrum ; the anus is in the peri-
proct. The masticatory lantern is composed of forty pieces (or Clypeastroids
thirty pieces) ; it is wanting in adult Spatangoids. Respiratory organs consist
of Stewart's organs, peristomal, or ambulacral gills. Locomotion is eff'ected
by ambulacral feet, or by spines, or both.

The Test. — The test or main skeleton of the Echini is composed of numerous
calcareous plates, firmly united by their edges so as to form a more or less

rigid case or box and disposed in certain
regions or Systems. In some genera,
however, the plates overlap one another
in an imbricating manner so as to im-
part a certain degree of flexibility to
the test. When coronal plates are
imbricaie, the ambulacral plates overlap
adorally and the interamhulacral over-
lap aborally and from the centre out-
ward and oyer the ambulacrals on the
p^^, gg^ adradial suture (Fig. 365). When peri-

" Lepidestiies coiiettiyf\vL. Synthetic ii^ure show- stomal plates are imbricate, all overlap

ing method of iinbrication of coronal plates (after adorallv (^Fi^ 371 B^
Jackson). rm • * i ' r i

ihe main element oi the test is
termed the Corona, which is composed of five ambulacral and five interam-
hulacral areas. At the summit is situated the apical disc, or oculogenital
plates, which in regulär Echini surrounds the periproct and anal opening.
The periproct is usually plated, always carries the anal opening, and in
irregulär Echini lies outside of the apical disk in the posterior interam-
bulacrum. Yentrally is situated the peristome, a membrane which is usually
more or less completely plated, or may be naked, and extends from the
mouth opening to the base of the Corona. The peristome is either central in
Position or anterior to the centre in some of the Exocycloida.

Echini are oriented by an antero-posterior axis drawn through an ambul-
acrum and opposite interambulacrum in such a plane that the madreporite lies
in the right anterior interambulacrum. This is the axis on which bilaterality
is attained in the Exocycloida, and the same axis is indicated in regulär Echini
by the order in which ocular plates reach the periproct when such occurs.
With known axes Lovön devised a nomenclature of areas which is of very
great value in brevity and clearness of expression. He numbered the ambul-

CLA8S I ECHINOIDEA 269

acral areas from I to V, Koman, and the interambulacra from 1 to 5, Arabic.
The enumeration passes from left to rightj revolving like the hands of a
watch, the specimen beirig viewed from below and the odd anterior ambulacrum
being III (Fig. 370). When viewed from above, the order of enumeration is
necessarily reversed (Fig. 434). Lov6n showed that the size and character of
the primordial ambulacral plates give data by which a sea-urchin can be
oriented in young regulär Echini, and usually in adult Exocycloida. He
showed that of these teil plates, the la, IIa, Jllb, lYa, Yb are larger ; on the
contrary the Ib, Hb, lila, lYb, Ya are smaller (Figs. 370; 377, A).

The mouth opens into an Oesophagus which conducts into a capacious
stomach, and thence into a convoluted intestine. The digestive tract winds
around the interior of the test, being attached to the inner surface of the
latter by muscles, and terminates in the anus. Surrounding the Oesophagus
is a circular vessel filled with water, which is admitted by the so-called stone-
canal, opening externally in a madreporite. This is a porous ör sieve-like
structure, consisting of a variable number of canals, and though commonly
restricted to genital 2, madreporic pores as a Variation may extend to additional
genitals or to ocular plates.

The circular vessel gives off five branches, known as the radiating canals,
which pass along the ambulacral areas on the interior of the test, and con-
nected with it in the interambulacral areas are five distensible membraneous
reservoirs, termed the Polian vesicles. The radiating canals give off numerous
lateral branches or tube-feet (tentacles) which are extended through the
pores of the ambulacral plates. Dilation is effected by means of secondary
vesicles or ampullae which by contraction force their contained fluid^ into the
tube-feet and distend them. The ampullae, as a rule, communicate with the
tube-feet by two canals perforating the plates separately, a single tentacle
being placed pver .a pair of ambulacral pores. The tube-feet serve usually
as locomotive organs, when they are prehensile and end in a suctorial disk ;
but in many forms, especially those having petaloid ambulacra, they are
modified so as to be partly brauch ial in function. Sometimes the tentacles of
the same ambulacrum differ in shape, structure and function, as in Arbacia.

Eespiration is apparently effected by Stewart's organs in certain Echini.
These organs are internal, five in number, and situated radially, they are
given off from the periphery of the lantern membrane and beneath the com-
passes. In the Cidaroida, Stewart's organs are frondescent; in the Echino-
thuriidae, vermiform or sausage-shaped. External branchiae or gills exist in
the Centrechinoida as outward extensions of the oral integument. They exist
as ten small or larger branched fleshy organs interradially situated. Their
presence is marked by indenting cuts in the basicoronal plates so that their
presence is recognizable in fossils where they exist (Centrechinoida). In
Clypeastroids and Spatangoids, as well as partially in some of the Centre-
chinoida {Arbacia), the function of respiration is maintained by modified
dorsal ambulacral tentacles which have lost their function as locomotive
organs. For distinction these are called ambulacral gills.

The vascular System consists of a ring-like vascular plexus surrounding the
Oesophagus, and immediately underlying the circular ambulacral vessel. This
ring gives off five radial vessels, and also two others which send off branches
to the stomach and generative organs. The central nerve ring, with its five
principal nerves running down the rays, is external to the two other Systems.

260 ECHINODERMATA— ECHINOZOA phylum iv

The generative organs are superficially alike in both sexes, and are in the form
of glands (usually five, sometimes four, three, or even two), situated dorsally
and interradially on the inner surface of the test. The genital ducts terminate
in pores in the so-called genital plates, to be described presently.

Coronal Plates. — The plates of the Corona are arranged in ten meridional
areas. Five of these, the ambulacral areas, are composed of perforated plates,
and correspond in position to the radiating ambulacral vessels ; the remaining
five, the interambulacral or interradial areas, alternate with the first, and are
imperforate.

In all Recent and in the majority of fossil Echini the ambulacral areas are
each composed of two columns of alternately arranged plates, the inner
edges of which meet in a zigzag median suture, and the actinal and abactinal
edges in horizontal sutures. In some Paleozoic genera there are more than
two columns in an ambulacral area, and there may be as many as sixteen, or
even twenty, at the mid-zone (Fig. 367, o). The interambulacral areas are
each composed of from one to fourteen columns of plates, but nearly all
post-Paleozoic and all Recent types have two columns. Interambulacral plates
are usually larger than ambulacrals and meet the latter in vertical adradial
sutures. There are therefore from fifteen vertical columns of coronal plates,
Bothriocidaroida (Fig. 377, A), to twenty columns Cidaroida, Centrechinoida,
Exocycloida, or more than twenty, as in the Paleozoic Echinocystoida and
Perischoechinoida (Figs. 429, 432), and the Triassic Plesiocidaroida. One
additional case of more than twenty columns is known in the peculiar
Cretaceous Tetracidaris. The number of columns of plates is the same for an
individual in each of the ambulacral areas, and usually for each of the
interambulacral areas as well, but the two Systems are entirely independent
of one another as respects the size and number of plates in a vertical column,
also, especially in the Paleozoic, as regards the number of columns in an area.
In the Cidaridae, for example, the ambulacra are very narrow and are
composed of numerous, thirty to sixty low plates in a column ; the inter-
ambulacra are broad with few, five or six to fifteen high plates in a column.
On the other hand, in the Paleozoic Lepidesthes colletti, the ambulacra are
broad, with sixteen columns of plates in each area, and the interambulacra
are narrow with four columns in each area (Fig. 434). In the regulär or
endocyclic Echini, all of the ambulacra and all of the interambulacra are
essentially similar in the individual ; but in irregulär or exocydic Echini, the
anterior ambulacrum and the posterior interambulacrum often differ consider-
ably from the corresponding areas.

Interambulacral (interradial) plates are always simple ; ambulacral plates
may be either simple or Compound. In the latter case, they are formed of
two or of several component elements, all of which are joined by sutures and
form a more or less geometrical plate. Most simple plates, and some of the
components of Compound plates are primaries — that is, they extend from the
outer edge of an ambulacrum to the median suture of the area. Demi-plates
is a name applied to those component elements which reach the inter-
ambulacrum but do not extend to the median suture (Fig. 396). Isolated
plates are component elements which do not reach either to the interam-
bulacral or median suture. Occluded plates are component elements which
reach the median suture, but do not reach the interambulacrum. These
terms, based on Compound plate elements, can be also applied to the

CLASS I

ECHINOIDEA

261

characters seen in Paleozoic types which have many columns of simple plates
(Fig. 367, l-o).

The growth of the corona of all Echini is effected by new plates being
successively added at the dorsal termination of the ambulacra and inter-
ambulacra, and by their increasing in size. In the young, and in adults
where the ventral border of the corona has not been resorbed in the advance
of the peristome, there is a single plate, which is the primordial interambulacral,
in the basicoronal row bordering the peristome in each area (Clypeastroids,
Spatangoids, many Paleozoic genera) (Fig. 366, a, h, f-h, etc.). Excepting
the Bothriocidaroida, we find passing dorsally from the primordial inter-
ambulacral plate that new columns are progressively added until the füll
number characteristic of the order, genus or species is attained. The new
columns come in in a perfectly definite order and System, although, where a
large number of columns is attained, there is some local Variation as regards
the point of introduction and also the number of columns. As progressive
development is marked by the addition of columns, senescent or regressive
development is marked dorsally in some types by the dropping out of columns
(Figs. 429, B ; 432). The primordial interambulacral plate ventrally represents

. Fio. 366.

Characters of the base of the interambulacrinn in lepresentative Echini : a, Bothriocidaris arcMica Jackson.
Ordovician. b, Goniocidaris canaliculata A. Agassiz. Young. c, Euddaris tribuloides (Lamarck). Bahamas.
d, Melonechinus multiporus (Norwood and Owen). Lower Carboniferous. e, Archaeocidaris woHheni Hall.
Lower Carboniferous. /, Echinocyamus pusillus (Müller). Recent. g, Rotula dentata (Lamarck). Recent.
h, Perlschodomus Usericdis M'Coy. Lower Carboniferous. In figures a, b, f-h, the primordial interambulacral
plate is in the basicoronal row ; in c-e, it, with or without additional plates, has been resorbed (after Jackson).

a Single column, and may be compared with the adult of the Ordovician
Bothriocidaris which retains a single column in each area throughout life.
The ventral border may in the adult be retained intact, or it may have been
more or less extensively resorbed in the advance of the peristome. When
this occurs, the primordial interambulacral, with or without additional rows
of plates, are cut away. Such occurs in the Cidaroida, most of the Centre-
chinoida, and a number of Paleozoic genera (Fig. 366, c-e).

Ambulacra. — Each ambulacrum has two columns of simple or Compound
plates, or in some Paleozoic genera, more than two columns of simple plates.
The ambulacrum is always composed of two halves which are equal on either
side of the median suture. Ambulacral pores are typically in pairs, rarely
(some Spatangoids) unpaired. Pore-pairs usually lie nearer to the inter-
ambulacral suture than to the middle of the plate in which they occur,
therefore as a result, where there are two columns of ambulacral plates,
there is a median interporiferous area between two marginal poriferous areas.
The pores of a pair may be vertically superposed, or usually the upper pore
of a pair revolves outward, through an angle of 90" or less, and toward the
interambulacrum, so that the axis of the pair is inclined or horizontal, the
inner pore being the lower of the two. A pore-pair is typically surrounded
by an elevated rim or peripodium, and the pores of a pair may be united by
transverse furrows, when they are said to be conjugate.

ECHINODEBMATA— ECHINOZOA

PHYLUM IV

The arrangement of pore-pairs is uniserial when one pair is placed over
the other in a continuous lirie from the peristome to the apex ; hiserial when
so placed that there are two vertical rows of pore-pairs in each half-area,
and polyserial when there are three to many vertical rows of pore-pairs in a
half-area. When ambulacral plates are componnd, the pore-pairs of each
component element may be arranged in an are, when there results a biserial
or polyserial arrangement. In Paleozoic genera, where the structure of the
ambulacrum is complex with many columns of plates {Melonechinus), the
ventral portion is simpler, presenting stages of development through which
the animal has passed. In the same types the dorsal area of young last
added plates also shows simplicity as a localised stage in development. In
those types that have Compound ambulacral plates, the young plates dorsally
are simple for a short distance, as seen well in Centrechinus.

Fig. 367.

Character of the ambulacrum in representative Echini ; left half represented, The horizontal dotted line is
on the plane of the mid-zone (after Jackson), a, Bothriocidaris archaica Jackson. Ordovician. b, Goniocidaris
canaliculata A, Ag. Young. c, Eucidaris tribuloides (Lamarck). Bahamas, d, Strongylocentrotus dröbachiensis
(O. F. Müller). Young. e, The same ; Adult. York Harbor, Maine. /, Micraster cor-anguineum (Lamarck).
Cretaceous, England, g, Echinarax;hnius -parma (Lamarck). Eastport, Maine, h, Metalia pectoralis (Lamarck).
Bahamas ; showing plates of two areas. i, Palaeechinus elegans M'Coy. Lovver Carboniferous. k, Maccoya
hurlingtonensis (Meek and Worthen). Lower Carboniferous. l, Lovenechinus missouriensis (Jackson). Lower
Carboniferous. m, Oligoporus danae (Meek and Worthen). Lower Carboniferous. n, Melonechinus multiporus
(Norwood and Owen). Lower Carboniferous. o, Lepidesthes colletti White. Lower Carboniferous.

Ambulacra are usually band-shaped and continuous from the peristome
to the apical disc. Petaloid ambulacra are those which enlarge between
the apex and the circumference (ambitus), and contract again more or
less perfectly before reaching that region. Suhpetaloid ambulacra are more
elongated than the petaloid, and the series of pairs of pores do not tend to
close distally. The pores do not cease altogether at the end of the petaloid
parts, but remain traceable for some distance beyond, often as far as the
peristome. In such cases, however, the pores are greatly reduced in size, or
present other marked differences from those of the petaloid parts. The
poriferous areas are said to be discontinuous, or inferrupted, when the' pairs of
pores cease at the ends of the petals, and reappear in the vicinity of the
peristome.

Oculogenital or Apical System. — This is abactinal or dorsal, and is ordinarily
composed of ten plates, five oculars and five genitals, forming usually (ex-
cepting some Echinothuriidae, always in regulär Echini) a continuous ring.
The genitals are typically large angular plates interradially situated and
perforated by one or more pores communicating with the genital glands. One
of the genitals, the right anterior, is also perforated by madreporic pores

CLASS I

ECHINOIDEA

263

rhich serve in orienting a specimen. These madreporic pores are rarely
recognizable in Paleozoic Echini, and may have been wanting in some genera.
In the Exocycloida the posterior genital is usually imperforate or wanting,
and two or more to all genitals may be fused in a mass. Genital plates
may be in contact dorsally, forming a closed ring, or may be in part or wholly
separated by the oculars.

Ocular plates dorsally cover the ambulacra and laterally the inter-
ambulacra in part on either side. Each ocular has a single pore. In
Paleozoic forms, oculars are apparently imperforate or rarely with two pores.
The pores are related to a primitive large tentacle and not to an ocular organ.
Ocular plates may all separate the genitals, reaching the periproct, when they
are described as insert, the usual Paleozoic character (Fig. 433, ^) ; or they
may be all excluded from the periproct by the contact of the genitals, when

Fig. 368.

Typical ocular plate arraiigement in regulär Echini (after Jackson). A, Cidaris coronata Goldfuss. Upper
Jura ; Sontheim. All oculars exsert ; plates shaded. B, Salenocidaris profundi (Duncan). Eecent ; Tristan
da Cuiiha. Ocular I insert ; plates shaded. C, Acrüsaleniaspinosa A^&ssiz. Cornbrash; Chippenhani, England.
Ocular,s I, V, insert. D, Centrechinus setosus (Leske). Recent ; Bermuda. Oculars I, V, IV, insert.

they are described as exsert, the usual Mesozoic character (Fig. 368, A).
Oculars are all exsert in the young of probably all Recent and Mesozoic
regulär Echini. In adults the same character may obtain, or one or more to
all oculars may travel in with development, separating the genitals so as to
be insert. As shown by Jackson, when oculars become insert, they do so in a
definite sequence in relation to the antero-posterior axis. The first ocular to
become insert is either I, or V. If ocular I comes in first, then V follows, or
the converse, thus marking the posterior pair or the bivium ; next ocular IV
becomes insert, then II, thus marking the posterior pair of the anterior
trivium ; lastly, if at all, ocular III becomes insert (shown in part in Fig. 368,
A-D).

The apical disk is relatively large in very young Echini and in primitive
types {Bothriocidaris, Cidaroida). It decreases rapidly proportionately in size
with growth, and is relatively small in specialised regulär Echini {Echinometra,
Melonechinus, Lepidesthes, Fig. 434).

In the Exocycloida the genital plates may be in contact at their sides,
forming a compact System (Fig. 369, D) ; or they may be separated by some of
the ocular plates which meet along the median line and separate the posterior
genitals, forming an elongate System (Fig. 369, C). When the two posterior
ambulacra (bivium) do not terminate at the summit in line with the other three

264

EGHINODERMATA— ECHINOZOA

PHYLUM IV

(trivium), and are surmounted by oculars placed far posteriorly, the System is
Said to be disjimä or disconneded. The posterior oculars are then separated

from the postero-
' ^' ^ ^ lateral genitals by

a number of inter-
ambulacral plates
intercalated along
the dorsum (Fig.
369, A).

In the Clypea-
strina and many
of the Cassidulidae,
the apical System
consists of five
minute ocular
plates, and one
large, pentagonal,
central plate, which
probably represents
the fused genitals
and is usually
pierced in four or
in all of its inter-
radial angles by
genital pores (Fig.
369, E, F).
Periproä. — This structure which bears the anus is within the apical disk
in all regulär Echini, when the test is termed endocyclic ; and at a variable
distance beyond it in the median line of the posterior interambulacrum in
irregulär Echini, when the test is termed exocydic. Periproctal plates are
rarely preserved in fossil Echini. They are numerous, angular, thick, and
fill the area in Paleozoic genera and the Cidaroida ; they are numerous, or
few and dissociated, often reduced to granules in other Echini ; or the
periproct may be largely leathery (CentrecMnus). In the Saleniidae there is a
large suranal (Fig. 368, B), with additional large plates (some Acrosalenias) or
with small plates only. A suranal occurs in the young of some types as the
Echinidae and Strongylocentrotidae. The periproct is usually circular, but may
be angular, or in the Exocycloida varies from circular to elliptical or pyriform.
The Position of the periproct in the test is of great systematic importance.

Peristome. — This is actinal and central in regulär Echini, and is circular,
decagonal or pentagonal in outline. Along its margin in the basicoronal
interambulacral plates of the corona there are ten incisions for the extension
of the peristomal gills which exist in certain Echini, the Centrechinoida and
Holectypina. In the Exocycloida the peristome is variable in shape and
Position, but it is actinal and is central or more or less anterior from the
centre. The oral membrane of the peristome is attached to the lantern when
present, otherwise the inner edge is free.

The peristome may be more or less extensively plated or may be naked,
and the character of the plates is of systematic importance. In the young of
probably all regulär Echini there is one row of primordial ambulacral plates

Apical Systems of irregulär Sea-iirchiiis. A, CoUyrites. B, Holectypua.
C, Hyboclypeus. D, Micraster. E, Conodypeus. F, Clypcaster.

CLASS I

ECHINOIDEA

265

which are found in place and fill the area (Fig. 370). From this primitive

condition various departures exist. The area may be filled with two or many

rows of ambulacral plates only {Bothrioci-

daris, Fig. 377, ^ ; Hyattechinus, Fig. 429, ^ ;

Phonnosoma, Fig. 371, A). These plates

after the first row have doubtless been de-

rived by migrating down from the Corona

as shown by Loven. There may be many

rows of ambulacral with interradial non-

ambulacral plates (Cidaroida, Fig. 371, B;

Archaeocidaris, Fig. 371, C ; Melonechinus,

Fig. 371, D). There may be one row of

ten primordial ambulacral plates with more

or less solid, scaly, or isolated non-ambu-

lacral plates, or rarely no non- ambulacral

plates (most Centrechinoida). There may be

scaly non -ambulacral plates only (Spatan-

goids), or the peristome may be quite naked

of plates (Clypeastroids)

AristoÜe's Lantern
exception of Spatangoids (and possibly some
Holectypoids) are provided with a powerful
masticatory apparatus known as the Aristotle's lantern, which, with the muscles
and their points of insertion in the test are of high systematic value. The
lantern is composed of forty pieces in all Echini except Clypeastroids. * There

Fig. 370.

Goniocidaris caTUÜiculata A. Agassiz. Re-
cent ; Falkland Islands. Young, 1.45 mm. in
diameter. Primordial ambulacral plates tili

All -n T_' • 'J.I, j.1^ •tli'^ peristome, primordial interambulacral
-AU lliCnini Wltn ttie plates in the basicoronal row succeeded by

two plates in the second row in each inter-
radial area (after Jackson).

Fk!. 371.
Characters of peristome and base of the corona in representative Echini. J, Phormosoirm plucenta
Wyville Thomson. Recent ; otf Cape May to Cape Sable. On the peristome many rows of ambulacral plates.
/>', Kucidaris tnbuloides (Lamarck). Bahamas. On the peristome many rows of ambulacral and in addition
interradial non-ambulacral plates. C, Archaeocidaris tnortheni Hall. Lower Carboniferous. Partially restored.
On the peristome many rows of ambulacral and in addition interradial non-ambulacral plates. /), Melonechinus
multiporus (Norwood and Owen). Lower Carboniferous. Restored. On the peristome many rows of ambulacral
and in addition two rows of interradial non-ambulacral plates ; ambulacrals pass from two plates orally to
manv on the periphery of peristome in each area. E, Strongylocentrotus dröbachiensis (O. F. Miiller). York
Harbor, Maine. On the peristome one row of ambulacral and scattered, small, non-ambulacral plates. ±,
Krhinocardium flavescens (Müller). Recent. On the peristome many non-ambulacral plates only. In hgures
A and F the primordial interambulacral plates are in place in the basicoronal row ; in the other hgures they have
been resorbed, with or without additional plates (after Jackson).

are five teeth ; five pyramids, each composed of two halves, joined by suture ;
ten epiphyses ; five braces ; and five compasses, each composed of two parts,
joined by suture. The lantern is inclined, subtending an angle of about
90", in the young of modern and adult of Paleozoic Echini ; erect with sides
approaching the vertical in most Recent regulär Echini ; or procumbent in
most Clypeastroids. Teeth are grooved (Paleozoic genera, Cidaroida and
Aulodonta); or have a keel on the inner face (Stirodonta, Camarodonta,

266

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

B

Holectypina, Clypeastrina). Pyramids, each composed of two halyes, are
roughly triangulär in section, present a median suture, above which is a

shallow or a deep
open Space, the
foramen magnum.
On the inner face
the pyramid Sup-
ports and embraces
the tooth, and
laterally in regulär
Echini has ridges
for the attachment
of interpyramidal
Fig. 372. muscles. The

Dental apparatus of the Recent Strongylocentrotus dröbachiensis (O, F. Müller). UDDer faCC of the

A, Lantern showing teeth, pyramids, interpyramidal muscles, styloid processes of ^^ . ,

dental slides, epiphyses, crests and compasses. B, Pyramid showing on one side pyramiu, aS Seen

protractor and retractor muscles, epiphysis removed on left side. C, top of ^.'Up« ^-'Up p-nmhv

lantern, at areas 2, 3 a whole tooth in place ; at 1 pulj)y i)art of tooth removed ; at Wneil lim epipuy-

4 tooth removed. At area III compass, brace and epiphyses in place ; at V com- gjg jg remOVed is

pass removed ; at IV brace also removed ; at I the epiphysis of one side is removed '

to show pits in top of pyramid. 2/^ (after Jackson). a smOOth IlOOr

(Paleozoic genera,
Cidaroida) ; or is pitted (Centrechinoida). An epiphysis caps each half-
pyramid, to which it is joined by close suture, it presents a glenoid
cavity and tubercles for interlocking with the
brace. The epiphyses are narrow in all Echini
except the Camarodonta in which they are wide
and meet in suture over the foramen magnum ;
here also they bear crests which support the teeth
dorsally. The brace is a block-shaped plate which
rests on and interlocks with the epiphyses. The
compass rests on the brace and consists of an inner
and an outer part, joined by suture; the outer
part is usually bifid but may be rounded. The
angle of 'inclination of the lantern, the teeth

grooved or keeled, the depth of the foramen mag- py,^^id „f Recent strongyiocen-
num, absence or presence of pits in the top of the ^™^«*' dröbacUensis. a, in sid« view

., ^ ^ .^ . 11« showing corrugations for attachment

pyramids, and narrow or wide epiphyses and their of interpyramidal muscie, epiphysis

.^^^-,- .,• , • i. 2. £ j. •!• with crest, glenoid cavity, external

meetmg in suture are important f eatures in classi- and internal tubercles. b; Pyramid

fication from centre showing dental slide and

* , other parts as in A (after Jackson).

The ]aws of the Holectypoids are similar to
those just described, but in the Clypeastroids they are low, often asym-
metrical, and the teeth are aslant or even nearly horizontal (Fig. 374).
Compasses are absent, and the braces are rudimentary. The pyramids are
solid almost to their upper part, more or less concave, or re-entering on the
outer side, and are not always of the same size in each area. Jaws of
Echini are rarely preserved in the fossil State.

The muscles of the lantern are numerous and complex, and their insertion
in the test is of systematic importance. There are sixty lantern muscles in
regulär Echini which in brief are, ten protractors inserted on the outer face
of the pyramids and base of the test ; they extend the lantern ; ten retractors
similar ly situated which open the jaws (Fig. 372, B) ; five interpyramidal

Fig. 373.

CLASS I

ECHINOIDEA

267

Fia. 374.

A, Clypeaster reticulatus Loven. Kecent. The dental System entire, seen from
above. The braceß are placed upon the sutures of adjoiiiing pyramids, with an
epiphysis on either side. Teeth in line with the mesial sutures of half-pyramids,
and within the ring formed by the supra- alveolar crests (after Loven). B, a, Front
View of a Single pyramid ; b, side view of one of the half-pyramids.

muscles (Fig. 372, A) which contract the jaws ; teri internal and ten external
brace muscles, which are tiny and extend from the brace to the epiphyses ;
live circular compass muscles which dorsally connect the com passes ; ten radial
compass muscles
which extend
from the com-
pass to the base
of the test.
These last are
wanting in Cly-
peastroids as in
that group com-
passes are ab-
sent.

Perignathic
Girdle. — Cer-
tain muscles of

the lantern, namely, the retractor, protractor and radial compass, pass to and
are inserted on the base of the test, and certain important processes, the
perignathic girdle, may be built for insertion of these muscles. Lov6n showed
that in young Goniocidaris the lantern muscles are all attached directly on the
base of the interambulacra, and the same method probably existed in the
Perischoechinoida, as in that order no perignathic processes have been seen.
In adult Cidaroida elevated processes, the apophyses exist as strong internal
upgrowths of the ventral border of the basicoronal interambulacral plates ; to
these apophyses in this order alone are attached the retractor, protractor and
radial compass muscles. In the order Centrechinoida the apophyses or up-
growths of the interambulacral plates m-ay be feebly or strongly developed, and
to them are attached the protractor and radial compass muscles. In this order
a new structure appears consisting of two separate calcareous plates, the
auricles, which are united by close suture to the basicoronal ambulacral plates.
The auricles exist as separate styles or in some genera in development may
grow into large plates which arch and join in suture over the ambulacral area.
Auricles give insertion to the retractor muscles, which combination of
apophyses and auricles is known in this order only. In the Holectypoids
low apophyses and auricles, or auricles alone may exist ; as this group
occurs fossil only, the muscles can only be inferred. In Clypeastroids
apophyses are wanting, but low or high auricles exist on the ambulacral
plates, or even may be transferred to the basicoronal interambulacral plates
as seen in Echinarachnius. In Clypeastroids retractor and protractor muscles
are both inserted on the auricles, a condition peculiar to the group.

Tubercles and Spines. — The plates of Echini bear more or less numerous
tubercles and granules of various sizes which bear larger or smaller spines.
The larger and completely developed tubercles are called primaries; those
of a smaller size are secondaries; and very small tubercles, sometimes
incomplete in their development, are miliaries. Granules are irregulär or
nodular projections of the test; they may be large and widely separated,
or very numerous and of various sizes. The base of a tubercle is termed
the boss, and its upper part may be either piain or crenulated. The boss
Supports a rounded mamelon, which is said to be perf<yrated when pierced by a

268

ECHINODERMATA— ECHINOZOA

PHYLUM IV

Cidarid Spines. A, B, Cidaris. D, Acrocidaris.
E, Porocidaris (natural size).

central foramen for a slight distance, or imperforate when it is not. A piain
or sunken space surrounding the base of the tubercle is called the scrobicule,
or areola ; its outer limit, the scrohicular circle, is generally marked by a ring

^ oi granules, but in many cases the
scrobicules of the same meridian are
continuous. Secondary tubercles may
or may not be scrobiculate.

All the tubercles of Echini bear
movable spines, which differ greatly in
dimensions, and in the shape and
nature of their cross-sections. They
are usually cylindrical, acicular, clavate
or spatulate in form, and consist of
the following parts : A more or less
elongate distal portion or shaft ; a base,
to which ligaments are attached for
keeping the spine in place ; and an
articulating Joint or condyle (acetabulum),
forming a ball -and -socket Joint with
the tubercle proper. When the base
of the mamelon is crenulated, the base
of the spine is incised in the same
manner, and above the latter is usually a milled ring or collar, the indenta-
tions of which are continuous with the Striae of the shaft. The function of
spines is to support the test, to aid in locomotion, and for defence. In rare
cases some of the spines are fixed, and arise directly from the test (Recent
Podocidaris).

Fascioles are narrow bands of close granulär ornamentation which
support rudimentary spinules and pedicellariae. They occur only in the
Spatangoids, and are restricted to certain parts of the test. The peripetalous
fasciole follows the margin of the petaloid parts of the ambulacra. The
anal fasciole surrounds the anus, and the subanal fasciole encloses a space or
plastron beneath the anus, but may send anal branches upward. The internal
fasciole crosses the ambulacra at a variable distance from the apical System,
and the marginal fasciole encircles the test above the ambitus. For those
Spatangoids with subanal fascioles, Loven has proposed the name Prymno-
desmia ; genera without them, and with other fascioles, are Prymnadetes, and
those without any fascioles are Adetes.

Pedicellariae are small specialised organs articulated upon granules and
scattered between the spines over the whole test. At the end of the stem
is a head consisting of two or more pincer-like valves which function as
grasping and cleansing organs. Pedicellariae are very rarely preserved in
the fossil State.

Sphaeridia are opalescent spheroidal bodies which may be partially or
entirely covered by the test. They exist singly near the ventral border of
the ambulacra, or if more than one, the series extends dorsally, even to the
ocular plate. Morphologically, sphaeridia may be considered as modified
spines having sensory functions. They are known only in the Centrechinoida
and Exocycloida.

-The early larval stages of Echini are similar in many respects

CLASS I ECHINOIDEA 269

to those of Ophiurans and Starfishes, but have little in common with the
larvae of Crinoids. The later stages in development are of great morpho-
logical and phylogenetic interest. Stages in development can, of course, be
best obtained by studying young individuals, but, as shown by Jackson,
they can also in a measure be obtained from a study of adults. The plates
at the ventral portion of the test are the oldest and first formed, excepting
as some may have been resorbed in the advance of the peristome. Ventrally,
therefore, stages in development are often observable in both the ambulacra
and interambulacra, this condition being especially marked in the Perischo-
echinoida. Dorsally are found the youngest plates of the test, and it is here
that we observe localised stages in development. For, as we pass ventrally
to the progressively older plates, it is found that characters are taken on
in regulär sequence which present stages directly comparable to those seen
in the youthful development of the individual. Dorsal localised stages are
especially marked in the ambulacra of those types where a complex structure
is attained, as in the Palaeechinidae and the Centrechinoida. The apical disk,
periproct, peristome, lantern and perignathic girdle all show stages in
development with suitable material, which stages are directly comparable
to adult conditions of simpler members of the group, and therefore are of
great phylogenetic significance.

Among Echinoids, as elsewhere in invertebrate groups, evidence is accumu-
lating that evolutionary Variation is not radial in all directions, but rather is
in definite directions, or orthogenetic. It would appear that the majority of
variations are either arrested, in which cases the variant retains characters
displayed in its own youthful stages and typical of the adults of more primi-
tive allies ; or progressive, when the variant has characters not typical of the
species, but which are further evolved in the direct line of difFerential develop-
ment. These latter are seen typically in more highly evolved closely related
species or genera. In order to study Variation intelligently it is of prime
importance to be familiär not only with the characters of the associated
species and genera when considering any given case, but also with the develop-
mental characters of the same. Variation needs to be especially considered in
undertaking phylogenetic studies.

Homologies. — The Echinoidea differ radically from the Pelmatozoa and
Asterozoa in that arms are completely wanting. They differ from Crinoids in
that reproductive glands are within the test and interradial, that ambulacral
and interambulacral plates originate on the ventral border of a fixed plate, the
ocular, and in the possession of a lantern. Echinoids differ from Starfishes
essentially in that radial water, nerve and blood canals are on the proximal not
distal side of the ambulacral plates ; that ambulacral pores pass through, not
between the plates ; and in the possession of a lantern.

Habits. — Echini are exclusively marine, and are more or less gregarious.
Many species occur in littoral zones, and from that region various species and
genera extend to continental and abyssal depths. Echini commonly live on
the surface of the sea floor, or cling to rocks. Some Echini burrow in sand,
others (Strongylocentrotus, Echinometra) along the coast occur in cavities which
they bore in solid rocks. The same species does not excavate in sheltered
places.

- About 500 recent species are known, as compared with fully 2500 fossil.
The earliest types appear in Ordovician rocks (Bothriocidaris), and continue to

270 ECHINODERMATA— ECHINOZOA phylum iv

be represented sparsely throughout the Paleozoic era. They multiply enor-
mously in the Mesozoic, and certain families reach their climacteric in that
period ; other families attain their maximum in the Recent. As a rule, the
species have a very limited vertical ränge, and hence serve admirably as index
fossils. The test is often perfectly preserved, but even small fragments are
capable of accurate determination, owing to the regulär radial repetition
of parts.

The Classification here followed is based on that given in Jackson's
Phylogeny of the Echini; no subclasses are recognised, but the group is
divided into seven Orders. The generic descriptions of the Cidaroida and
Centrechinoida and the generic and family descriptions of the Exocycloida are
essentially those as given in the earlier edition of this work, or in Duncan's
Revision of the Genera and Great Groups of the Echinoidea.

Order 1. BOTHRIOCIDAROIDA Duncan.

Test regulär, more or less spherical. Interamhidacra with one, and ambulacra
with two vertical columns of plates, which do not imbricate. Feriproä within the
apical System.

Family 1. Bothriocidaridae Klem.

JFith characters of the order.

The solitary known genus is Bothriocidaris Eichwald (Figs. 366, a; 367,
a; 376; 377), from the Ordovician of Esthonia. The test is small, and the

Fig. 376.

Bothriocidaris pahleni Schmidt. Ordovician; Nömmis, Esthonia. ^, Test of the natural size. J5, Apical
System, enlarged. C, Peristome, enlarged (after F. Schmidt).

apical System consists of five large ocular and five small genital plates ;
periproct plated, peristome with ambulacral plates only.

Of this important genus, the oldest of known Echini, there are three species, B. archaica,
pahleni and globulus. The ambulacra have two columns of high hexagonal plates in each
area with pore-pairs superposed in a central peripodium. Interambulacra with one column
of plates only in each area. Ocular plates relatively large and meeting in a continuous ring
{£. archaica), or partially or wholly separated by the small genitals. Genitals in £. archaica
dorsal to the oculars (Fig. 377, B) or in other species partially or wholly separating them and
reaching the interambulacra, Bothriocidaris is structurally important because in its high
ambulacral plates, with pores superposed, its single column of interambulacral plates, its
simple peristome and its large oculars, it presents features like the young of later Echini. All
other Echini start with a single interambulacral plate ventrally, representing a single column,
and later add one or more columns. Those types with only two columns of plates in an inter-
ambulacral area show no evidence of beiug derived from types with many columns, and are
therefore considered as next related to the Bothriocidaroida.

CLASS I

ECHINOIDEA

271

Order 2 CIDAROIDA Duncan.

Test regulär, endocycUc, two columns of plates in each ambulacral area, ambula-
cral plates low, simple; ftvo (in one genus, Tetracidaris, partly föur) columns of

A, Bothriocidaris archaica Jackson. Ordovician ; Island of Dago, Russia. Height, 12 mm. Two rows of
peristomal plates. Two columns of hexagonal plates in each ambulacrum. One column of plates in each inter-
ambulacrum. x 3/j. B, the same, apical disk, oculars meeting in a ring, genitals small, dorsal to the oculars, peri-
proctal plates. x ^/i (after Jackson).

plates in each interamhulacral area. Coronal plates rarely imbricate (Miocidaris).
Primordial interamhulacral plates resorhed. Peristome with many rows of ambulacral
and interradial non-ambulacral plates, or rarely ambulacral plates only. Lantern
erect, teeth grooved, foramen magnum very shallow ; epiphyses narrow. No pits in
the top of pyramids. Perignathic girdle consisting of apophyses only. Stewarts
Organs ptresent, but no peristomal gills. Primary spines with a cortical layer.
Primary tubercles perforate. Sphaeridia absent.

272

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

Family 1. Cidaridae Gray.

With charaders of the order.

The apical disk is rare in fossil Cidarids (Fig. 368, A) ; when preserved, the
ocular plates are typically all exsert. The same conditiori exists in the young
of Recent species and often in adults. When oculars reach the periproct,
they do so in the sequence V, I, IV, II, III, or V, I, IV, III, II. Young
Cidarids approach Bothriocidaris closely in many structural details. De-
vonian (?), Lower Carboniferous to Recent ; maximum in Jura and Cretaceous.

Section A. Ambulacral pore-pairs uniserial.

Miocidaris Döderlein. Ambulacral and interambulacral plates imbricating.
Two Paleozoic species, M. keijserUngi (Geinitz), from the Permian of Europe,

Fig. 378.

Cidaris coronata Goläit Upper Jura (y); Hossingen, Wurtemberg. A, Dorsal aspect of test with perfectly
preserved apical System. B, Profile. C, Portion of Amh, magnified. Z), Partially restored view with spines
attached.

and M. cannoni Jackson, from the Lower Carboniferous of America, are the
only certain Paleozoic representatives of the order. Several species in the
Trias and Jura of Europe.

Cidaris Leske, ex Klein (Figs. 368, A ; 378-380). Amb undulating or nearly
straight, the pores variable in their distance, and united by a groove or not.
lAmb coronal plates five to fifteen in each column. Apical system large.
Primary spines very variable, even in the same species. Trias to Recent ;
chiefiy Jurassic and Cretaceous.

Of this genus more than 200 species have been described. These are grouped into seven
or eight artificial divisions, whicli are regarded by some as of sub-generic, or even generic
importance. Some of the groups may be briefly noticed as follows : —

CLASS I

ECHINOIDEA

273

(a) Rhabdocidaris Desor (Figs. 381, 382). Test large and swollen. Poriferous areas wider
than in Cidaris, tlie two pores of a pair being distant and conjugated. Amb in general
straight. Tiibercles large, strongly crenulated, and more nunierous than in Cidaris. Spines
very stout, some cylindrieal or prismatic, often spiniferons. Chiefly Jura and Cretaeeous ;
less common in Tertiary and Recent.

Fio. 379,

Eucidaris tribuloides (Lam.). Receiit. Erilarged vievv of base of the
test and peristome, showing plated coveriug of the latter.

Plf!. 380.

Cidarid spines. A
C. alata Ag. ß, C
dorsata Braun. Trias
St. Cassian, Tyrol
C, C. florigemma Phill
Coral llag ; Wiltshire.

Fig. 381.

Rhaf}docldaris orUgnyana Desor. Upper
Jura; Kelheim- Winzer, Bavaria, ^.Frag-
ment of test, i/i. B, Amb plates enlarged.

Fio. 382.

Rhabdocidaris horrida
Morian. Middle Jura.
Spine, i/i.

{b) Leiocidaris Desor. Like the preceding, but with uncrenulated tubercles. Spines
large, smooth, cylindrieal. Cretaeeous to Recent.

(c) Stephanocidaris A. Ag. Test thin ; apical System larger than the peristome, the
plates feebly united. Recent.

{d) Pliyllacanthus Brandt. Test large, swollen, and witheight to eleven lAmb plates
in a column. Amb broad, pores conjugated. Primary tubercles large, smooth. Recent.

(e) Porocidaris Desor (Fig. 383). Amb broad and straight ; pores wide apart, conjugated.
Primary tubercles perforate and crenulate. Scrobicules transversely oval, with shallow
grooves radiating from the periphery toward the centre, with or without pores at the outer
extremity of the grooves. Tertiary and Recent.

(/) Goniocidaris- Desor. Töst high, with nunierous coronal plates, and narrow Amb.
The median sutural regions of both areas are sunken, forming with the horizontal sutures
a zigzag, with pit-like depressions at the angles. Recent.

VOL. I T

274

ECHINODERMATA— ECHINOZOA

PHYLUM IV

Orthocidaris Cotteau. Apical System small, pentagona!. Amb narrow,
straight ; pore-pairs in simple straight series, the pores separater! by a
granule. lAmb very broad, numerously plated. Primary
tubercles small, piain, perforate and distant. Lower Creta-
ceous ; Europe.

Temnocidaris Cotteau. Upper Cretaceous. Polycidaris
Quenst. Upper Jura.

Section B. Amhulacral Pore-pairs Biserial.

Diplocidaris Desor. Test large, spheroidal. Amb narrow,
straight. Pore-pairs very numerous, close, alternating more
or less. lAmb broad, with seven to eight plates in each
column. Primary tubercles large, perforate, scrobiculate.
Upper Jura ; Europe.

Tetracidaris Cotteau (Fig. 384). Remarkable in having
four columns of plates in each lAmb at the ambitus, but
diminishing to two at the apex. Amb straight, moderately
broad. Poriferous areas depressed, pairs incompletely
biserial ; interporiferous areas narrow, granulär, with a row
of piain small tubercles, placed near the borders of the
poriferous zone. lAmb primary tubercles very large,

crenulate and perforate. Spines narrow, elongate. Lower Cretaceous (Bar-

remien); Europe.

Fig. 383.

Forocidaris schmiedeli
Goldf. Numraulitic
Liniestone; Mokkatain,
nearCairo. lAmb -plate
and spine.

Fi(i. 384.

Tetracidaris reynesi Cotteau. Neocomian ; Vergans, near Castellane, Basses Alpes. A, Test reduced
one-half. B, Portion of Amh, enlarged (after Cottean).

Xenocidaris Schnitze. Founded upon clavate, fusiform spines from the
Devonian of the Eifel. Incompletely known, possibly belongs in this family.

Order 3. CENTRBCHINOIDA i Jackson.

Test regulär, endocyclic, two columns of plates in each ambulacral area,
ambulacral plates Compound, rarely simple; two columns of plates in each inter-

^ This name is based on Gentrechinus, a new narae for Diadema which was preoccupied for a
Crustaceaii.

CLASS I ECHINOIDEA 275

amhulacral area. Primordial amhulacral plates arouml the mouth in tlie peristome.
Primordial inter amhulacral plates in the basi-coronal row, or usually resorhed.
Peristome lüith ten primordial amhulacral^ also non-amhulacral plates, or in one
family many rows of amhulacral plates only. Lantern erect or rarely inclined ;
teeth grooved, or keeled : foramen magnum deep. Pits in the top of pyramids.
Perignathic girdle consisting of low or high apophyses, and auricles. Peristomal gills,
rarely with Stewarts organs in addition. Primary spines without a cortical layer.
Sphaeridia present.

Compound amhulacral plates are the most striking feature of this order ;
such plates are composed of from two to ten elements, each of which has
a pore-pair. The young of the Centrechinoida present stages in development
which closely resemble the Cidaroida and also Bothriocidaris. The Centre-
chinoida are divisible into three suborders on the basis of the structure of the
lantern, which is in brief, teeth grooved, epiphyses narrow, Aulodonta ; teeth
keeled, epiphyses narrow, Stirodonta ; teeth keeled, epiphyses wide, meeting in
suture over the foramen magnum, Camarodonta. Trias to Recent.

Suborder A. AULODONTA Jackson.

Teeth grooved. Epiphyses narrow, not meeting in suture over the foramen
magnum. Amhulacral plates simple or Compound. Oculars all exsert, or hecoming
insert in the sequence /, V, IV, II, III. Periproct with many plates or granules,
or largely leathery. Lantern erect or inclined. Primary tubercles usually perforate.
Trias to Recent.

Family 1. Hemicidaridae Wright.

Amhulacral plates Compound ventrally, simple above the mid-zone, or in sonie
genera Compound throughout. Coronal plates thick, not imbricating. Base of
Corona resorhed, Oculars all exsert, or one, or two may he insert. Periproct
unknown. Peristome unknown. Lantern erect. Trias
to Tertiary.

Hemicidaris Agassiz (Fig. 385). Amh narrow ;
plates near the apical system very numerous, small,
low primaries, succeeded by plates formed of from
two to four components, together with additional
primary or demi-plates. Tubercles in two vertical
rows, perforate and crenulate. lAmh broad, with
two vertical rows of tubercles similar to those of p^^. gg^

t\vQ Amh, but much larger. Oculars all exsert or hemicidaris crenuiaris (Lam.).

I, or I, V insert. Peristome large, with well- Coral Rag; ChätelCensoire, Tonne.

developed branchial incisions. Trias to Cretaceous. ^ ^'
The following subgenera are recognised : —

(a) Hemidiadema Ag. Amh tubercles large, and few in number below the ambitus,
alternating distinetlj. Jura and Cretaceous. H. stramonium Ag.

{h) Hypodiadema Desor. Amh narrow, straight ; their tubercles of nearly the same size
througliout. Peristome and branchial incisions small. Trias to Cretaceous.

(c) Pscudocidaris Etall. Amh very undulating abactinally, with primary tubercles near
the peristome, granules elsewhere. Jura and Cretaceous.

Acrocidaris Ag. (Fig. 386). Test large, spheroidal dorsally, flat actinally.

276

ECHINODERMATA— ECHINOZOA

PHYLUM IV

Amb straight, broad at the ambitus ; pore-pairs uniserial and in simple series
near the apex, in arcs of from four to seven pairs near the larger tubercles,
crowded and polyserial actinally. lAmb with two vertical rows of primary

Äcrocidaris nobilis Ag. Upper Jura ; St. Sulpice, near Locle, Neuchätel. .1, Dorsal view, B, Ventral view.
C, Spina, i/i. D, Three Compound Amb plates, enlarged.

tubercles ; only the largest are perforate and crenulate. Spines cyclindrical,

often tricarinate. Upper Jura and Cretaceous.

Goniopygus Agassiz. Apical disk large, plates more or less ornamented ;
oculars insert, genital plates punctured on adoral margin.
Peristome very large, with small branchial incisions.
Cretaceous and Eocene.

Glypticus Ag. (Fig. 387). Amb straight, and narrow
except at the peristome, where the poriferous areas are
expanded ; with two vertical rows of small, smooth, primary
tubercles. lAmb tubercles replaced abactinally by warty
or irregulär elongate elevations. Epistroma much developed.
Abundant in Upper Jura.

Fia 387.

Family 2. Aspidodiadematidae Duncan.

Glypticus hieroglyph-
ims Goldf. Coral Rag
(Glyptician) ; Fringeli,
Switzerland. l/i-

Ambulacral plates simple. Coronal plates thin, not imbri-
cating. Base of Corona resorbed. Oculars all exsert, or all may
be insert. Peristome with ten large primordial ambulacral
Lantern erect. Lias to Kecent.

Orthopsis Cotteau. Amb much narrower than the lAmb, straight, and with
numerous pairs of pores in straight series. Amb with two, lAmb with several
vertical rows of small, piain, perforate tubercles. Jura and Cretaceous.

Eodiadema BuncB^n. Lias; England. E chinopsis Ag. Eocene ; Europe and
Egypt. Aspidodiadema A. Ag. Apical disk very large, oculars insert. Recent.

Family 3. Oentrechinidae Jackson (IJiadematidae Peters).

Ambulacral plates Compound. Coronal plates not imbricate (Mesozoic), or more
or less imbricate {Recent). Base of corona resorbed. Oculars exsert, or one to all
insert. Periproct more or less plated, to nearly leathery. Peristome with ten

CLASS I

ECHINOIDEA

27'

primordial ambulacral, also non-amhulacral plates. Lantern
indined. Stewarts organs slight, or absent. Lias to Recent.

Centreehinus Jackson {Diadema Schynvoet) (Fig. 368,
narrow, often projecting; two vertical
rows of small, primary, crenulate and
perforate tubercles extending from
peristome to apex. IAr)ih with two
or more vertical rows of primary
tubercles resembling those of the
Amb, but larger. Secondary tubercles
and granules surrounding the scrobi-
cules. Spines long, hollow, longitu-
dinally striated. Lias to Recent.

Hemipedina AVright. Jura, Creta-
ceous and Recent. Differs from Centre-
ehinus in having simple Amb plates
near the apex, and perforate, but
not crenulate tubercles.

Pseudodiadema Desor (Fig. 388).
Includes small species having wide
Amb, tubercles of uniform size in
Amb and lAmb areas, and oculars
typically all exsert. Jura to Ter-
tiary.

Heterodiadema Cotteau. Like
Centreehinus, but with the apical
System greatly extended into the depressed posterior
H. libycum Cotteau.

erect, or (Astropijga)
D). The Amh are

Pseudodiaclenm neglectum
Jura. A, B, Profile and
C, Ambulacrum, enlarged.'

Thurm. Froin the Bernese
ventral aspect of test, Vi-
D, Spine, V-i-

lAmb. Cretaceous.

Codiopsis Ag. (Fig. 389). Primary tubercles of both areas small, smooth.

Fig. 389.

Codiopsis dovia (Desin.). Cenonianian (Tourtia) ; Tournay, Belgium. A, Sirle-view of test, Vi- -R, Ventral

aspect of sanie. C, Apical systein, enlarged.

nearly equal in size, and only occurring actinally and for a short distance
toward the ambitus. Pore-pairs uniserial. Cretaceous.

Cottaldia Desor. Cretaceous and (?) Recent. Fleurodiadema de Loriol.
Jura. Magnosia Michelin. Jura and Cretaceous.

Diplopodia M'Coy. Amb narrow, with two vertical rows of perforate and
crenulate primary tubercles. Pore-pairs in double vertical series near the
])oles, uniserial at the ambitus. Jura and Cretaceous.

Fedinopsis Cotteau. Cretaceous. Phi/mechinus Desor. Jura.

278

ECHINODERMATA— ECHINOZOA

PHYLUM IV

Pedina Ag. Amh narrow, poriferous areas wide. Both areas with two
vertical rows of small, perforate, primary tubercles. Upper Jura.

Pseudopedina Cotteau. Like the preceding, but with larger primary
tubercles, which are present in the Ämb near the ambitus only. Upper Jura.

Micropedina Cotteau. Amb with several, and lAmb with numerous vertical
rows of very small primary tubercles. Cretaceous.

Leiopedina Cotteau (Chrysomelon Laube). Test large, melon-shaped. Amb
long, straight, very broad. Poriferous areas broad, pore-pairs triserial, and
almost horizontal. Plates very numerous, low, broad, Compound. Tubercles
small, piain, finely perforate, in two distant vertical rows. lAmh broad, with

Pio. 390..

Stomechinus lineatus (Goldf.). Coral Rag; Sontheim, Würtemberg. A, Side-view of test, i/j. B, Portion

of Retinal surface.

two rows of tubercles similar to the ambulacral, and with intermediate
granules. Eocene.

Stomechinus Desor (Fig. 390). Distinguished from Pedina by its wider
Amb, and imperforate, non - crenulate primary tubercles. Secondary
tubercles and granules often present. Jura and Cretaceous.

Codechinns Desor. Tubercles very small, piain, irregularly distributed.
Cretaceous.

Polycyplms Agassiz. Jura. Astropyga Gray. Recent.

Family 4. Echinothuriidae Wyville Thomson.

Ambulacral plates Compound. Coronal plates very thin, imbricate. Primordial
interambulacral plates in basicoronal row. Base of Corona not resorbed. Oculars
insert, often separated from the genitals by interspaces. Genitals more or less split
by secondary sutures. Periproct leathery but partially plated. Peristome with many
rows of ambulacral plates only. Lantern inclined. Radial peristomal and somatic
muscles. Stewarts organs present. Jurassic to Recent.

This family is represented by several living and two extinct genera, the
latter being known only by fragmentary specimens. Pelanechinus Keeping
is found in the Upper Jura, and Echinothuria Wood ward in the Upper
Cretaceous of England. Phormosoma Wyv. Thomson (Fig. 371, A) and
Asthenosoma Grube. Recent, occurring chiefly in depths below 1 00 fathoms.

CLASS I ECHINOIDEA 279

Suborder B. STIRODONTA Jackson.

Teetli keeled. Epiplujses narrow, not meeting in suture over the foramen
magniim. Amhulacral plates Compound or largely simple. Coronal plates not
imbricate. Primordial interambulacral plates resorhed or retained in the basicoronal
row. Base of corona resorbed or not. Oculars all exsert or becoming insert in the
sequence I, V, or V, I, IF, II, III. Periproct with prominent suranal, o?' mth
many small plates, or foiir, or five large plates only. Peristome with ten primordial
ambulacral, also non-ambulacral plates. Lantern erect. Primary tuber des
imperforate, or exceptionally perforate. Jurassic to Recent.

Family 1. Saleniidae Desor.

Ambulacral plates Compound, or largely simple. Primordial interambulacral
plates resorbed, Base of corona resorbed. Oculars exsert or becoming insert in the
sequence I, V, IV, II, III. Periproct with a permanent large suranal, or more
large plates, with small anal plates. Primary tubercles imperfm^ate, or perforate.
No spurs from pyramids supporting teeth dorsally. Jura to Recent.

Peltastes Ag. (Fig. 391). Amb straight or slightly flexuous, with simple

Fig. 391.

Peltastes, apical System ;

m, madreporite. ^ '^IBSSF^ Fio 392

Salenia fcutigera Gray. White Clialk ; Charente
(after Cotteau). A, Lateral and dorsal aspects of
tests, Vi- ^> Apical System, enlarged.

plates abactinally and with small primary tubercles near the poriferous
areas. lAmb broad, with large, imperforate primary tubercles, diminishing
in size toward the poles. The suranal plate is small, in contact with the
lateral genitals, but not touching the posterior one. Upper Jura and
Cretaceous.

Salenia Gray (Fig. 392). Test small, globose, or depressed. Amb plates
Compound or largely simple. The suranal plate is in contact with all the
genitals ; oculars all exsert or ocular I reaching the periproct, perforated at
the adoral edge. Cretaceous to Recent.

Goniophorus Agassiz. Upper Greensand ; Europe. Heterosalenia
Cotteau. Cretaceous ; Europe.

Acrosalenia Ag. (Figs. 368, C; 393). Test depressed. Amb plates simple
primaries near the apical system, Compound near the ambitus and actinally.
lAmb tubercles large, perforate, and crenulate ; those of the Arnb much smaller,
and in two vertical rows. Periproct large, bounded anteriorly by the suranal
plate, which is in contact with the four large anterior genitals, or more

280 ECHINODERMATA— ECHINOZOA phylum iv

than one large periproctal plate. Oculars all .exsert or one to all insert,

Acrosalenia hemicidaroides Wright. Middle Jura ; Stanton, Wiltshii

of test, Vi (fifter Wright).

Dorsal, lateral and ventral aspeets

commonly I, Y insert. Spines cylindrical, striated or piain. Represented
by numerous species from the Lias to the Lower Cretaceous.

Family 2. Phymosomatidae Meissner.

Ämbulacral plates Compound. Primordial interambulacral plates resorbed.
Oculars becoming insert in the sequence I, F, IV, II, III. Periproct with
numerous small plates only. Primary tubercles imperforate. Spurs from pyramids
Support the teeth dorsally. Jura to Recent.

Cyphosoma Agassi z (Fig. 394).

Fig. 394.

Cyphosoma hoeniui Mantell. White Chalk
Sussex. Ventral aspect, '/i-

Test depressed, with few coronal plates.
Amb with well-developed poriferous areas
undulating. Pore-pairs biserial at the
apex, crowded at the peristome. lAmb
broader than the Amb, with two or more
vertical rows of primary tubercles, which
are imperforate and crenulate, like those
of the Amb. Apical systcm encroaching
upon the posterior lAmb. Jura to Ter-
tiary.

Glyptocidaris A. Agassiz. Recent. This
genus shows the character of pyramidal
spurs given as a family character.

Micropsis Cotteau. Amh with three to
five elements to a Compound plate, and
two or more vertical rows of small primary
tubercles, which are perforate and crenu-
late. Cretaceous and Eocene.

Family 3. Stomopneustidae Mortensen.

Ambidacral plates Compound, composed of three elements each, at the mid-zone
every four or five ämbulacral plates are boand together and grown over by one
primary tubercle. Primordial interambulacral plates and base of corona resorbed.
Oculars becoming insert in the sequence 1, V, IV. Periproct with many small plates
only. Primary tubercles imperforate. Spurs from pyramids support the teeth
dorsally.

CLASS I

ECHINOIDEA

281

Stomopneustes Ag. Am,h straight, with pores in arcs of three pairs dorsally
crowded and triserial below the ambitiis. Both aieas with two vertical rows
of piain tubercles. Formerly classed with the Echinometridae, from which it
diifers radically, especially in structure of the lantern. Tertiary and Recent.

Family 4. Arbaciidae Gray.

Ambulacral plates Compound,
coronal row. Base of Corona not

Primordial interambulacral plates in the basi-
resorhed. Oculars all exsert or becoming insert

IV. Periproct with four or five large plates only.
No spurs from pyramids supporting teeth dorsally.

Primary
Tertiary

With three elements in an ambulacral plate. Tertiary

Recent.

in the sequence V, I,
tubercles imperforate.
to Kecent.

Arbacia Gray,
and Recent.

Tetrapygiis Agassiz. With five elements in an ambulacral plate

Coelopleurus Ag. (Fig. 395). Amb with two vertical
rows of piain, primary tubercles placed on flat scrobi-
cules, diminishing in size toward the apex, and some-
times replaced there by granules. lAmb with a large
bare median area abactinally ; the tubercles largest at
the ambitus, sometimes disappearing toward the apical
System. Tertiary and Recent.

Podocidaris A. Agassiz. Recent ; Caribbean Sea and
Philippines.

Suborder C. CAMARODONTA Jackson.

Teeth keeled. Epiphyses wide, meeting in suture over
the foramen magnum. Ambulacral plates Compound. Coronal
plates not imbricate. The ambitus is circular, or elliptical
through a sidewise axis. Primordial interambulacral plates
resorbed. Base of Corona resorbed. Oculars all exsert or

becoming insert in the sequence V, I or I, F, IF, II, III. Periproct usnally plated
with many small plates {in one genus, Parasalenia, with four large plates).
Peristome with ten {in one species five) primordial ambulacral plates and rnore or
fewer non-ambulacral plates ; rarely the latter are absent. Lantern erect. Primary
tubercles imperforate. Cretaceous to Recent.

Fig. 395.

Coeloplewus equis Ag.
Eocene ; Biarritz, France.

Family 1. Eohinidae Agassiz.

Ambitus circular. A^o pits or sculpturing in the coronal plates dorsally.
Ambulacral plates at mid-zone composed of three elements each, rarely darsally of
two elements. Oculars all exsert, or becoming insert in the sequence I, F, IF, II,
III. Cretaceous to Recent.

Echinus Linn. Amb straight, with narrow poriferous zones ; pore-pairs in
more or less vertical arcs of triplets. Interporiferous areas with two vertical
rows of small, piain, primary tubercles with or without irregularly placed
secondary tubercles and primaries. lAmb with two vertical rows of primaries,
and few or numerous rows of secondary tubercles and miliaries. Peristome
small, circular. Cretaceous to Recent.

282 ECHINODEEMATA— ECHINOZOA phylum iv

Stirechinus Desor. Both areas with two rows of large, piain, primary
tubercles situated on raised keel-like projections. Pliocene ; Europe.

Glyptechinus de Loriol. Cretaceous. Tripneustes Agassiz. Miocene and
Recent.

Hypechinus Desor. Tertiary. Toxopneustes Agassiz. Recent. Boletia
Desor. Recent.

Family 2. Temnopleuridae Desor.

AmUtus circular. Pits, or sculpturing in coronal plates dorsally. Ambulacral
plates at the mid-zone composed of three elements each. Oculars usually all exsert.
Cretaceous to Recent.

Glyphocyphus Haime. Test small, depressed spheroidal. Amb narrow,
straight, with two vertical rows of small, perforate, crenulate, primary
tubercles, and numerous miliaries. lAmb broad, with two rows of primaries
somewhat larger than those of the Amb. Transvörse and median sutures
grooved. Oculars all insert. Cretaceous and Eocene.

Didyopleurus Duncan and Sladen. Eoncene ; Asia, Europe and Egypt.
Paradoxechinus Laube. Miocene ; Australia. Echinocyphus Cotteau, and Zeuglo-
pleurus Gregory. Cretaceous ; Europe.

Temnopleiirus Ag. Trans verse sutures of all plates grooved and pitted.
Apical System small, compact, slightly projecting. Tertiary and Recent.

Temnechinus Forbes. Test small, subglobose, depressed abactinally.
Both areas with two vertical rows of piain primaries. Apical System
prominent, compact, the sutures between the plates more or less grooved.
Late Tertiary and Recent.

Salmacis Ag. Eocene, Pliocene and Recent. Älicrocyphus, Amblypneustes,
and Holopneustes Agassiz. Recent.

Family 3. Strongylocentrotidae Gregory.

Ambitus circular. No pits or sculpturing in the coronal plates. Ambulacral

plates at the mid-zone composed of from four to ten elements each, rarely (some

Echinostrephus) of three elements each. Oculars all exsert or becoming insert in the
I, F, IF, II. Tertiary to Recent.

Strongylocentrotus Brandt (Figs. 371, E ; 372-3,

396). Test symmetrical and polyporous. ^m& straight,

broad at the ambitus and peristome, and with broad

poriferous areas. Pore-pairs in oblique arcs or almost

transverse series of from four to ten pairs, and crowded

actinally. Interporiferous areas with two vertical

Flu. 396. rows of piain imperforate primary tubercles; secondaries

strongylocentrotus dröbach- and miliarics also present. lAmb with two rows of

po^^uM Sm4iat?!'^^'''^" ^''"" primary, and four or more of secondary tubercles.

Late Tertiary and Recent.

Sphaerechinus Desor. Amb straight, wide. Pore-pairs in arcs or oblique

lines of four to eight pairs, polyserial actinally. Interporiferous areas with

two to six vertical rows of piain, imperforate primaries, and horizontal rows

of secondary tubercles and miliaries. lAmb with two to twelve vertical rows

of primaries. Pliocene and Recent.

Eurypneustes and Aeolopneustes Duncan and Sladen. Eocene ; Asia.

CLASS I ECHINOIDEA 283

Family 4. Echinometridae Gray.

Ambitus elliptical in a sidewise axis. No püs or sculpturing in coronal plates
'hrsalhj. Ambulacral plates at mid-zone composed of four or more elements each,
rarely (Parasalenia) of three elements each. Oculars all exsert, or becoming insert
in the sequence V, I, IV. Recent.

Echinometra Gray ; Heterocentrotns and Colobocentrotus Brandt ; with highly
specialised spines. Recent.

Order 4. EXOCYCLOIDA Jackson.

Test irregulär, exocyclic, periproct outside of oculogenital ring in interambulacrum
-7. Two columns of plates in each ambulacral area and two columns of plates in
each interambulacral area. Regulär in form, or more freguently more or less
markedly bilaterally symmetrical through the axis III, 5. Slight or no resorption
of base of Corona by the advance of the peristome, Lantern present or absent.
Peristomal gills, or ambulacral gills only. Sphaeridia present. Jura to Recent.

This Order includes all exocyclic Echini excepting the Paleozoic
Echinocystoida. The order shows structural characters associating it with
the Arbaciidae.

SuborderA. HOLECTYPINA Gregory.

Ambulacral plates Compound, or largely simple, areas not petaloid dorsally.
Primordial ambulacral plates unknown. Primordial interambulacral plates in basi-
coronal row, or in part resorbed. Base of Corona slightly resorbed. Oculars and
genitals all present and distinct, or fused, or genital 5 absent ; when present it is
imperforate. Periproct unknown. Peristome central, structure unknown. Lantern
inclined so far as known. Teeth keeled, epiphyses narrow. Foramen magnum
moderately deep. Pyramids with ridges on lateral wings. Perignathic girdle con-
sisting of apophyses and auricles, or auricles only. Peristomal gills present. Jura
to Tertiary.

Family 1. Discoidiidae Gregory.

Perignathic girdle consisting of apophyses and auricles.

Discoidea Gray (Fig. 397). Test hemispherical above the margin, flat

Discoiiha cylindrica Agassiz. Upper Cretaceous ; Lüneburg. A, Side-view. B, Test broken open to show

the inner partitions, i/i.

actinally. Amb narrow, with some Compound plates near the ambitus and
a>ctinally ; pore-pairs very numerous, small. lAmb with distinct median

284

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

sutures, and small, perforate and crenulate tubercles. Plates within the
actinal surface with radiating ribs, ten in all, extending as far as the peri-
stome ; appearing on casts as deep depressions. Periproct small, infra-
marginal. Cretaceous.

Conuhis Leske (Galerites Lam.). Amh flush or sligTitly raised, apetalous,
straight ; some of the plates Compound. Peristome sunken, slightly decagonal.

Fio. 398.
Conoclypeus conoideus (Goldf.). Eoceiie ; Kresseiiberg, Bavaria (^^ natural size).

symmetrical. Perignathic girdle indicated by a thickening of the lAmb as a
low false ridge. Abundant in the Lower and Middle Cretaceous.

Lanieria Duncan. Cretaceous or Eocene ; Cuba.

Conoclypeus Ag. (Figs. 369, B ; 398). Test large, thick ; conical or vaulted
dorsally, flat actinally. Amb long, open, with broad poriferous areas nearly to
ambitus, narrowing thence to peristome. Pores wide apart and in pairs where
the areas are broad ; the pairs separated by costae. Pores continued in single
series over the ambitus as far as the central, pentagonal peristome. Periproct
infra-marginal, oval (?), Cretaceous and Eocene ; Europe.

Family 2. Pygasteridae Gregory.
Perignathic girdle ^pparently consisting of aurides only.
Holeäypus Desor (Figs. 369, B ; 399). Ar)ih narrow, straight, widest at

Fig. 399.

A,B, Holectypusorificatua^c\\\oi\\. Upper Jura ; Streitber<^, Franconia. (', ]), JL depresmf: (Jjeske). Mlddh
Jura ; France. Apical System and ventral surface (after Cotteau).

CLASS I

ECHINOIDEA

285

ambitus ; some of the plates Compound. lAmb with rather large plates, and
many rovvs of tubercles. Peristome large, decagonal, with well-marked branchial
incisions, jaws, and feeble perignathic girdle.
Periproct large, pyriform, situated between the
peristome and posterior edge of the test. Apical
System small, central. Jura and Cretaceous.

Pileus Desor. Test large, sub-hemispherical
dorsally, flat actinally. Tubercles small, ir-
regularly arranged. Periproct supra- marginal,
small, broadly ovoid. Upper Jura.

Pi/r/aster Ag. (Fig. 400). Test large, de-
pressed dorsally, concave actinally. Amb straight,
similar, flush or slightly raised, widest at the
ambitus. Poriferous areas straight, simple,
narrow ; tubercles of interporiferous areas in
two or four vertical rows ; those of the lAmh in
horizontal rows. Peristome large, decagonal,
with jaws and feeble perignathic girdle. Peri-
proct immediately beyond the apical System.
Jura and Cretaceous.

Galeropijgus Cotteau; Pachyclypeus Desor.
Upper Jura ; Europe.

Fig. 400.

Pyqaster umhclla Agassiz. Oxfordian ;
Chätillon-snr-Seine. Young individual,
Vi (after Cotteau).

Suborder B. CLYPEASTRINA Gregory.

Ambulacral plates simple, areas petaloid dorsally. Ventrally amhulacral pores
are minute and specialised. Primordial ambulacral plates in basicoronal row.
Primordial interambulacral plates in basicoronal row, or exceptionally (Arachnoides)
pushed dorsally and in pari resorbed by intracoronal resorption. Base of Corona not
resorbed. Ocular and genital plates fused in a mass, usually no genital pore in area
5. Genital pores within the fused mass or outside in interambulacra 1, 2, 3, Jf..
Periproct plated. Peristome central, leathery, Lantern procumbent, highly modified,
teeth keeled, foramen magnum very shallow, small epiphyses and braces, but no com-
passes. Pyramids usually without ridges on lateral wings. Perignathic girdle con-
sisting of auricles only, on ambulacral, or on interambulacral plates. No peristomal,
but ambulacral gills only. Cretaceous to Recent.

Family 1. Olypeastridae Agassiz.

:■■ Test small to very large, depressed, flat or high. Petaloid parts of the ambulacra
highly developed, usually unequal ; the actinal furrows straight. Interambulacra
actinally discontinuous ; one peristomal plate in each area. Perignathic processes
tall, narrow, two on each ambulacrum, fitting in below the large jaws. Peristome
central, pentagonal ; periproct small, marginal or infra-marginal. Internal structure
with needles, pillars, and other processes extending fromfloor to roof, especially near
the edge of the test ; sometimes these are fused to form concentric partitions, and the
ambulacra may also be protected by an inner wall. Tertiary and Recent.

Clypeaster L3.m. (Figs. 369, F; 374, 401, 402). Actinal surface flat, with the
peristome deeply sunken ; edge thin, undulating in contour, with or without

286

ECHINODERMATA— ECHINOZOA

PHYLUM IV

re-entering angles. Petals long, broad, tumid ; pores wide apart, unequal,
conjugated. Periproct near or at the edge. Internal structure not forming

a double wall covering the
Amb. This genus includes
some of the largest known
Echinoids. Eecent species
are littoral, or shallow-
water inhabitants. Tertiary
and Recent.

Anomalanthus Bell. Re-

>if^ Cent. Laganum Gray. Be-

longs properly to a separate

rj'l family or subfamily. Ter-

'^*'' tiary and Recent.

Family 2. Pibulariidae
Gray.

Flu. 401.

Clypeaster cbegypticus Mich. Pliocene ; Gizeh, near Cairo. Fragment
showing internal calcareous deposlts. au, Auricles.

Test small, with rudi-
mmtary, widely open, few-
pored petals. Interambulacra
small, with a single apical and a single peristomal plate. Jmhulacra limited
adinally on the interior of the test hy low vertical partitions at their sides, radiating

Fig. 402.
c?' grandifiorus Bronn. Miocene ; Boutonnet, near Montpellier, i/o natural size (after Desor).

toward the peristome. Perignathic processes broad, low, situated on each inter-
ambulacrum. Periproct usually actinal. Cretaceous to Recent.

Echinocyamus Leske (Fig. 403). Test thick, depressed, pyriform or sub-
circular in outline, concave actinally. Amb broader than the lAmb, short

CLASS I

ECHINOIDEA

287

where slightly petaloid, widely open distally : pore-pairs few and iiicreasingly
far apart. Peristome central, pentagonal, with small
jaws. Periproct between the peristome and posterior
edge of the test. Cretaceous to Recent.

Subgenus Scutellina Ag. Periproct small, marginal or more
or less supra- or infra-marginal. Tertiary. „

Sismondia Desor. Test sub -pentagonal or ovoid, Echinoeyamus piuccutus
depressed, inflated at the margin. Petaloid parts of mocei •%ciiy'''y^ ^^'^'
the Jmh usually long, more or less open ; pore-pairs
not continued actinally. Tubercles minute. Eocene
and Miocene.

Fibularia Lam. (Fig. 404). Test thin, ovoid, tumid
dorsally and at the side. ^mb short ; pore-pairs very
few, continued wide apart to * the margin, non-con-
jugated. Peristome and periproct small, sunken, close
together. Upper Cretaceous and Recent.

Buna Ag. Tertiary ; Europe.

Fig. 404.

Fibularia suhglobosa (Goldf. ).
Upper Cretaceous ; Maest-
richt, Belgium. i/j.

Family 3. Scutellidae Agassiz.

Test very flat, with entire or incised margin ; limules or slits in the areas or
not. Ambulacral furrows bifurcating and branching. Peristome flush ; jaws flat,

Fi(i. 405.
Scutella auhrotundata Lam. Miocene ; Bordeaux. .4, B, Ventral and dorsal aspects ; r, Öectioii, Vi-

teeth superior. Eadiating partitions between the floors internally. Tertiary and
Recent.

Scutella Lam. (Fig. 405). Test circular or sub-circular in outline, some-
times undulating or notched, broadest behind. Petaloid parts of the Amb

288 ECHINODERMATA— ECHINOZOA phylum iv

uneqiial, well-developed, nearly closed. Peristome small, central, sub-circular.
Periproct very small, infra-marginal. Apical System central, more or less
pentagonal. Tertiary.

Subgenus Ediinarachnius Leske {Dendraster Ag.). Apical system eccentric in front or
behind. Periproct actinal or marginal. Recent.

Echinodiscus Leske. Like Scutella, but truncated posteriorly, and with two
round or «longate lunules or slits, one in each of the median lines of the
postero-lateral Amh. Tertiary and Eecent.

Encope Ag. Test with a broad notch or a lunule in the median line of
each Amb, and a lunule in the posterior lAmh. Miocene and Recent.

Mellita Agassiz. Test very tlat, with five or six usually closed lunules,
more rarely cuts ; one in the median line of the posterior lAmb, the others
in the Amb. Amb petaloid dorsally, the post^erior pair the longest. Pliocene
and Recent.

Lenita Desor. Eocene. Ilotula Ag. (Fig. 366, g). Recent. Arachnoides
Leske. Pliocene and Recent.

Suborder C. SPATANGINA Jackson.

Ambulacral plates simple, areas commonly petaloid dorsally ; in some types pores
are absent in pari of the plates. Ambulacrum III often differs markedly in charader
from other areas. Ambulacral plates often highly specialised in form and size.
Primordial ambulacral plates in the basicoronal row, or (Fourtalesia) in part pushed
dorsally. The basicoronal plates la, IIa, Illb, IVa, Vb, are larger and with two
pairs of pores or two separate single pores, whereas the Ib, IIb, Illa, IVb, Va are
smaller with one pore-pair or one single pore. Primordial interambulacral plates in
the basicoronal row or (Lovenia, Pourtalesia) pushed dorsally. Base of Corona not
resorbed. Oculars and genitals separate, or genitals partially fused. Oculars
apparently absent in some Pourtalesias. Genital 5 absent, and some additional
genitals rarely absent. Periproct plated. Peristome eccentric, plated with non-
ambulacral plates only. Lantern and perignathic girdle absent (present in the young
of Echinoneus, A. Agassiz, 1909). No peristomal, but ambulacral gills only.

Tribe A. CASSIDULOIDEA Duncan.

Ambulacra abactinally petaloid or sub-petaloid, usually similar. Some or all
of the interambulacra with a single peristomal plafe ; the postero-lateral areas
symmetrical actinally, without any fusion of plates; no plastrons. Peristome
variously shaped, with or without floscelles.

Family 1. Bchinoneidae Wright.

Test toll, or low and tumid dorsally ; turaid and rarely fiat actinally. Apical
System central, compact, with four perforated genitals. Ambulacra similar, dorsally
apetalous or sub-petaloid. Pores in simple pairs or in oblique triplets actinally ; no
floscelle. Peristome oblique or transversely elliptical, rarely symmetrical. Periproct
actinal, marginal or supra-marginal. Cretaceous to Recent.

• Subfamily A. Echinoneinae Desor.

Test low, tumid, and more or less pulvinate actinally ; peristome central or sub-
central and oblique.

CLASS I

ECHINOIDEA

289

Echinoneus Leske. Amh narrow, actinally uiiequally broad, owing to the
obliquity of the large, triangulär peristome. Miocene to Recerit.
Caratomus Ag. Cretaceous. Amhlypygus Ag. Tertiary.
Pyijaulus Ag. (Fig. 406). Test small, thick ; apical System slightly

Fk;. 406,

Pyriaulus desmoulinsi Ag. Urgonian
(Sclirattenkalk) ; Säntis, Switzerland. i/i.

Fig. 407.

Pyr ina inscia (Ag.). Neoconiian (Hils) ; Berklingen,

Brunswick. Vi-

Amh narrow, widest at the ambitus ; pore-pairs in simple
the pores of a pair sometimes differently shaped. Cre-

eccentric in front,
series, conjugated
taceous.

Pyrina Desm. (Fig. 407). Like the preceding, but pores non-conjugated,
and the pairs separated by costae. Cretaceous and Eocene.

Subfamily B. Echinobrissinae Duncan.

Test depressed, elongate, tumid. Ambulacra sub-petaloid. Apical System and
peristome eccentric ; floscelle ahsent or rudimentary. Interamhulacra entering the
peristomal margin witli a single plate. Periproct supra-marginal.

Nudeolites Lam. (Echinobrissus Breyn.) (Fig. 408). Test ovate, rounded in
front, broadest and more or less truncated behind; or rectangular, with the

Fig. 40d

A, B, Nudeolites dunieularis (Llhwyd). Cornbrash ; Egg, Aargau. Vi- C, D, N. scutatus (Lam.). Upper
Oxfordian ; Trouville, Cahados. C, Ventral aspect of large individual. D, Apical systeni, enlarged (after
Cotteau).

angles rounded ; or sub-circular ; concave actinally. Amb unequal, open at
the end of the sub-petaloid parts ; pore-pairs in simple series, more or less
unequal in shape and size, the outer ones elongate ; below the sub-petaloid
parts the pores are in small oblique pairs, conjugate or not. Periproct at
Upper end of a groove situated on the abactinal area of the test. Abundant
in Upper Jura and Cretaceous ; present also in Eocene and late Tertiary.
VOL. I U

290

ECHINODERMATA—ECHINOZOA

PHYLUM IV

üuhgenus Bochmostoma Duncsin {Trematopygus d'Orb.). Like the preceding, but with
oblique peristome. Cretaceous ; Europe and Nortli America.

Botriopygus d'Orb. Cretaceous. Ilariona Dames. Eocene.

Family 2. Cassidulidae Agassiz.

Test variable in shape. Ämhulacra petaloid, sub-petaloid or apetalous dorsally,
and with crowded doubling of the pairs of pores dose to the peristomal margin,
forming with the single, swollen and ornamented interamhulacral peristomal plates a
floscelle. Jura to Recent.

Test small, oblong, depressed, convex
dorsally, flat actinally. Amh narrow,
sub-petaloid, not closing ; pores con-
tinued from the middle part to the
well-developed floscelle. Peristome
eccentric in front ; periproct supra-
marginal, longitudinally elongated.
Cretaceous and Eocene.

Subgenus Rhyncopygus d'Orb. Periproct
transversely eloiigate, with overhanging
rostrum. Cretaceous to Recent.

Subgenus Pygorhynchus Ag. Test con-
cave actinally, with long petals. Peris-
tome and periproct longest transversely.
Cretaceous to Miocene.

Cassididus Lam. (Fig. 409).

Fig. 409.

Cassidulus lapis-cancri Lam. A, Test in three positions.
B, Floscelle, enlarged.

Stigmatopygus d'Orb. Cretaceous. Eurhodia d'Arch. and Haime. Eocene.
Paralampas and Neocatopygus Duncan and Sladen. Eocene. Catopygus Ag.
Cretaceous. Studeria Duncan. Tertiary and Recent. Phyllohrissus Cotteau.
Jura and Cretaceous.

Clypeus Agassiz. Test large, low, nearly flat actinally. Amb wide,
petaloid, not closing dorsally, narrow at the ambitus and actinally. Pore-

Pygurus royerianus Cotteau. Klinmeridgian ; Tönnjesberg, near Hanover. A, B, Dorsal and ventral views
of test, 3/4 natural size. C, Apical System, enlarged. D, Ambulacral plates, magnified.

pairs in the petaloid parts with the inner pore small and circular, the outer

CLASÖ I

ECHINOIDEA

291

transversely elongate, and in a long groove. Periproct high up, usually in a
groove along the median line of the posterior lAmb. Upper Jura.

Pygurus Ag. (Fig. 410). Test large, angular, rounded or cordiform in
marginal contour ; depressed or rather tall and sub-conical dorsally. Amh

Fig. 411.
Echinolampas kleini Goldf. Oligocene ; Doberg, near Bünde, i/i.

flush dorsally, unequal, wide ; the petaloid parts contracting but not closing
marginally, and expanding again actinally, where the Amb are grooved. Peri-
proct infra-marginal, pyriform or ovoid, in a special area, or rostrum, close to
the posterior edge of the test. Upper Jura and Cretaceous.

JEchinolampas Gray (Fig. 411). Test variable in size and shape, more
or less ovoid or circular at the tumid
marginal outline; tall and conical or
depressed dorsally. Amb petaloid for
a variable distance; pores of the petals
difFering in shape, conjugated and con-
tinued beyond in simple series. Peri-
stome slightly in front, or sometimes
central. Periproct transversely ellip-
tical, infra-marginal. Widespread in
Tertiary and Recent.

Conolampas and Neolampas A. Ag.
Recent. Plesiolampas Duncan and
Sladen. Eocene. Palaeolampas Bell.
•Upper Cretaceous to Recent.

Family 3. Oollyritidae d'Orbigny
{Dysasterinae Gray).

Apical System disconneäed, either
elongate or sub- compact. Ambulacra
similar ; bivium widely separated from fio. 4i2.

the trivium; ßoSCelle absent. Jura to Cü%rite5 e^^ii>^ica pesm CaUovian ; Mamers, Sarthe.
-* •' A, B, Test in proüle and froui above, Vi- C'» Apical

Cretaceous. system, enlarged.

292

ECHINODERMATA— ECHINOZOA

PHYLUM IV

CoUyrites Desm. (Fig. 412). Test ovoid, tumid, more or less truncated
posteriorly. Amh disjunct, the anterior one soraetimes in a slight groove.
Width of the Amh increasing towards the ambitus ; pore-pairs in low primary
plates. Periproct posterior, supra-marginal, placed in a groove. Apical
System elongate, separated by numerous small plates belonging to the
postero-lateral lAmb. Yery abundant in the Middle and Upper Jura and
Cretaceous.

Dysaster Ag. Differs from CoUyrites in details of the apical systeni, the
genitals not being separated by the antero-lateral ocular plates. Upper Jura
and Lower Cretaceous.

Hyhodypeus Agassiz (Fig. 413). Jura. Infradypeus Gauthier. Upper
Cretaceous. Grasia Mich. Jura.

Fig. 413.

Hyboclypeus gibberulus Ag, Middle Jura ; Soleure, Switzerland. A, B, Dorsal and ventral views.
C, Profile. D, Apical System, enlarged.

Metaporhinus Mich. Test very tall, slightly longer than broad, sub-cordi-
form, projecting upwards anteriorly, grooved and oblique behind. Anterior
Amb in a groove, with small, simple, distant pairs of pores ; the other Amb
flexuous, with comma-shaped pores placed obliquely to one another. Periproct
supra-marginal. Upper Jura and Lower Cretaceous.

Tribe B. SPATANGOIDEA Duncan.

Peristome eccentric in front, rarely pentagonal in the adult, usually with a
labrum, behind which is a long plasfron bounded laterally by the posterior
ambulacra. Ambulacra dissimilar. Inferambulacra with a single plate at the
peristomal margin; the postero-lateral areas usually unsymmetrical actinally.
Fascioles present or absenf.

Family 4. Ananchytidae Desor.

Test ovoid or sub-cordiform in marginal outline, fall or depressed, and with large
plates. Ambulacra in a bivium and trivium, nearly similar, flush, apetalous ; pore-
pairs largest near the apex and at the peristome, may be uniporous. Periproct
variable in position. Cretaceous to Recent.

Ananchytes Lam. {Echinocorys Breyn.) (Fig. 4 1 4). Test large, oval in marginal
outline ; high, rounded or keeled apically, flat actinally. Amb biporous, the
pore-pairs well developed abactinally, but becoming smaller, closer and

CLASS I

ECHINOIDEA

293

Posterior Amb
Peristome oval.

oblique toward the ambitus, where they are more distant.
actinally long and broad, the pairs small, and pores oblique,
broader than long. Periproct
infra- marginal, posterior, oval.
Apical System elongate. Very
abundant in the Upper Cretac-
eous. A. ovata (Leske) often
attains a very large size.

Holaster Ag. (Fig. 415). Test
ovoid in marginal outline, flat
actinally, tumid and high abac-
tinally. Anterior Amb in a shal-
low groove. Peristome elliptical,
broadest transversely. Periproct
supra-marginal, and oval. Apical
System elongate. Cretaceous
and Miocene.

Offaster Desor. Test small,
tumid. Anterior Amb sometimes
in a shallow groove. Peristome
oval, broadest transversely. Peri-
proct supra-marginal, circular or
ovoid. Apical system elongate.
Cretaceous. 0. pilula (Ag.).

Hemipneustes Ag. Test large,
ovoid in marginal outline, high
and tumid dorsally, flat actinally.
Anterior Amb in a deep, narrow
groove extending to the elongate apical System, its pairs of pores numerous

Fig. 414.

Ananchytes ovata (Leske). White chalk ; Haldem, West-
phalia. Ä, B, Profile and ventral view. 1/3. C, Apical system,
enlarged. D, Portion of Amb and lAmb areas. 1/1.

Fio. 415.
A, B, Ilolaster suhglobosus Ag. Cenomanian ; Ronen, l/i- C, H. mhorbiciilaris Defr. Apical system, enlarged.

and small, the vertical rows wide apart. Paired Amb more or less curved,
open distally, with dissimilar pores. Peristome much sunken, crescent-

294

ECHINODERMATA— ECHINOZOA

PHYLUM IV

shaped, broad. Periproct supramarginal. Upper Cretaceous. H. radiatus
(Lam.).

Cardiaster Forbes. Similar to Holaster, but anterior groove deeper and
with angular margin. Periproct oval, placed in a depression in the truncated
posterior face. A more or less complete marginal fasciole passing below the
periproct. Cretaceous.

Subgenus Infulaster Hagw. Test high in front, narrow ; anterior groove deep and with
strong lateral keels. Fasciole absent. Upper Cretaceous.

Urechinus and Cystechinus A. Agassiz. Late Tertiary and Eecent. Calymne
Wyv. Thomson. Eecent. Enichaster de Loriol. Oligocene. All with uni-
porous Amb.

Stenonia Desor. Like Ananchytes, except that the apical System is com-
pact, and the Amb equal. The solitary species, S. tuherculata (Defr.), is
abundant in the Upper Cretaceous (Scaglia) of the Southern Alps and the
Apennines.

Family 5. Spatangidae Wright.

Test ovoid or cordiform, longer than broad, with numerous jplates, and usually
with an anterior groove. Ambulacra in a bivium and trivium, the anterior differing
from the others in shape and construction. Pore-pairs of the petaloid parts differing
from the others. Fascioles present or absent. Cretaceous to Eecent.

Section A. Adetes. All fascioles absent.

Isaster Desor. Petals not closed.
labrum. Cretaceous.

Epiasier d'Orb. {Macraster Eoemer).

Peristome large, with a posterior

Anterior Ainb in a groove ; paired
Amb petaloid dorsally, with
elongate, unequal pores. lAmb
tumid dorsally. Peristome trans-
verse, tumid in front, and usu-
ally with a projecting labrum.
Periproct longitudinal, supra-
marginal. Cretaceous.

Toxäster Ag. {Echinospatagus
Breyn.) (Fig. 416). Anterior
Amb in a broad shallow groove,
with unequal pore-pairs. Paired
Amb sub-petaloid, flexuous, with
unequal poriferous areas and

unequal pore - pairs. Peristome transverse, sub - circular or pentagonal.

Tubercles small, perf orate and crenulate. Abundant in Lower and Middle

Cretaceous.

Ennalaster d'Orb. (Heteraster d'Orb. ). Petaloid parts of antero-lateral Amb

divergent, flexuous, tending to close, and with very unequal poriferous areas,

of which the posterior are the largest; pore-pairs oblique. Postero-lateral

Amb Short, divergent. Peristome labiate, wide, arched in front. Periproct

in posterior truncation. Cretaceous.

Hemipatagus Desor (Fig. 417). Test small, cordiform. Anterior Amb

Toxäster complanatus Ag

Fig. 416.
Neocomian ; Auxerre, Yonne.

Vi.

CLARS I

ECHINOIDEA

295

with small pores in a shallow furrow. Paired Amh long, petaloid, nearly

A C

Hemipatagiis hofmanni Goldf. Oligocene ;
Doberg, near Bünde. A, Dorsal view.
B, Profile. C, Ventral aspect. i/i (after
Goldfuss).

flush. The lateral lÄmh with a few large perforate and crenulate tubercles
in deep scrobicules. Periproct supra-marginal. Tertiary.

Platyhrissus Grube. Recent. Palaeopneustes A. Ag. Recent, and perhaps
Eocene.

Section B. Prymnadetes. Suhanal fasciole ahsent, other fascioles present.
Hemiaster Desor (Fig. 418). Anterior Amb in a shallow groove, the pores

Fio. 418.

Hemiaster orbignyanus Desor. Upper Cretaceous ; Martigues, Provence (after d'Orbigny). A-C, Ventral, dorsal
and side views of test, Vi- ^. Pores of the anterior Amb. E, Peres of the paired Amb, enlarged.

Fio. 419.
Linthia heberti Cotteau. Eocene ; Lonigo, near Vicenza. 3/^ natural size (after Dames).

oblique, and in pairs on either side. Antero-lateral Amh petaloid dorsally,
sunken, diverging, and much longer than the postero-lateral. Pores of the

ECHINODERMATA— ECHINOZOA

PHYLUM IV

petaloid pärts conjugated, the outer ones usually the largest. Peripetalous
fasciole present.

Subgenus Tripylus Pliill. {Ahatus Troschel). Recent.

Faorina Gray. Recent. Pericosmus Ag. Cretaceous and Tertiary.
Linthia Merian (Besoria Gray) (Fig. 419). Anterior Amb in a deep
groove, the pores round and small, in pairs on either side. Antero-lateral
Ami) longer and more divergent than the others, with petals sunk in grooves.
Pores conjugated. A peripetalous and lateral fasciole present. Cretaceous
to Recent.

Schizaster Ag. (Figs. 420, 421). Resembling Linthia, but the apical System
is posteriorly eccentric, and the Amb very diverse.
Tertiary and Eecent.

Prenaster Desor; Ornithaster and Coraster Cotteau.
Eocene.

Agassizia Val. ; Moira A. Ag. Tertiary and Recent.
Hs A. Ag. Recent.

Fig. 420.

Schizaster arcMaci Gott.
Eocene ; San Giovanni Ila-
rione, near Vicenza.

Fig. 421.

Schizaster fragilis Ag. Apical Sys-
tem, greatly enlarged (after Loven).

i« Fig. 422.

Micraster coranganius
(Ijam.). Apical System.

Section C. Prymnodesmia. Subanal fasciole present.

Micraster Ag. (Figs. 422, 423). Test cordiform, tumid, rather depressed.
Anterior Amb apetaloid, in a shallow depression ; antero-lateral Amb sub-
petaloid dorsally, diverging ; postero-lateral shorter than the others, with

Fin. 423.
Micraster cortestiulinarius Goldf. White Chalk ; Meudon, near Paris. Natural size.

CLASR I ECHINOIDEA 297

elongate, conjugated pores. Periproct supra-marginal ; apical System eccentric
in front. Broad subanal fasciole. Abundant in Middle and Upper Cretaceous ;
less common in Eocene and Miocene.

JBrissus Gray {Brissomorpha Laube) ; Meoma and Metalia Gray. Tertiary
and Recent. Bhinobrissus A. Ag. Recent.

Brissopsis Ag. (DeaJcia Pavay) (Fig. 424). Amb unequal, bare and large
near the peristome. Anterior Amb slightly sunken, with
small pairs of close pores. Paired Amb sunken, the
antero- lateral pair sub-petaloid, equal to or larger than
the postero-lateral, straight or curved. A subanal and
peripetalous fasciole. Tertiary and Recent.

Subgenus Cydastcr Cotteau. Antero - lateral Amh divergent.
Eocene.

Brissopatagus Cotteau. AUied to Brissopsis. Eocene.

Spatangus Lam. Anterior Amb in a broad, deep groove, ^^^ ^2^

with distant pairs of small pores. Paired Amb petaloid, Brisso2J:sis lyHfera
with broad, sunken poriferous areas. Periproct large, J^jar^ed f^terLovIn?"'
supra-marginal, transverse. lAmb with large crenulate
and perforate primary tubercles, and fine granulation. Subanal fasciole only.
Tertiary and Recent.

Maretia Gray. Tertiary and Recent.

Eupatagus Ag. Anterior Amb in a shallow, abactinal depression, narrow,
and with small, distant pore-pairs. The paired Amb petaloid dorsally, long,
wide, closed ; poriferous areas broad, more or less sunken ; pores dissimilar.
Peripetalous and subanal fasciole. Tertiary and Recent.

Subgenus Macropneustes Ag. {Peripneustes Cott.) (Fig. 425). Test large, thick, cordiform.
Petals elongate or broad, grooved or semi-flush, open or imperfectly closed. Poriferous areas
of equal widtli witli the interporiferous. Eocene and Recent.

GuaUieria Desor; Eocene. Echinocardium Gray (Fig. 371, F) ; Breynia
Desor ; Lovenia Ag. and Desor. Tertiary and Recent.

Section D. Apetala.

Ambulacra flush, apetalous, generally uniporous, and either similar or diverse;
plates high, few, oflen hexagonal. Fascioles usually present

Under this head are included the following Recent genera, all but the first
two of which have fascioles : Genicopatagus and Palaeobrissus A. Ag. ; Aceste
Wy V. Thomson ; Aeropsis Mortensen ; Palaeotropus Lov6n ; Homolampas,
Argopatagus A. Ag. ; and Cleistechinus de Loriol. Miocene.

Family 6. Palaeostomatidae Mortensen.

Test thin, ovoid. Apical System with three genital plates fused into one.
Peristome eccentric in front, pentagonal, with five angular plates.

Palaeostoma Lov6n (Leskia Gray). Recent ; China, East Indian Islands.

Family 7. Pourtalesiidae Loven.

Test very elongate, sub-cylindrical or obconical, truncated anterimiy, flat actinally.
Peristome in a deep anterior recess ; periproct actinal, or above the pyrojecting posterior

298

rostrum wlien such

ECHINODERMATA— ECHINOZOA

PHYLüM IV

Amhulacra flush, apetalous, sometimes discontinuous ;
pores Single or slit-Uke.

Pourtalesia, Spatagocystis
and Echinocrepis A. Agassiz.
Recent.

Order 5. PLESIOCIDA-
ROIDA Duncan.

Test regulär, endocyclic.
Genitals largely covering the
dorsal surface. Two columns of
low simple plates in each am-
bulacral area and three columns
of plates in each interamhulacral
area. Plates not imbricate.
Primordial interamhulacral
plates in basicoronal row. Base
of Corona not resorhed. Oculars
small, strongly exsert hy the con-
tact of large genitals. Peri-
proct central, structure unknown.
Peristome central, structure un-
known. Lantern and perigna-
thic girdle unknown.

Family 1. Tiarechinidae

Zittel.

The Single primordial plate
of the interambulacra followed
hy three elongated plates only,
one on either side of a narrow
median plate. Trias.
Tiarechinus Neumayr (Fig. 426). The test of this unique genus is very

small, flat actinally, and sub-hemispherical dorsally. Below the ambitus and

actinally the Ornament consists of a piain

primary tubercle to each plate ; elsewhere the

test is coarsely granulär, including the very

large apical System. The solitary species,

T. princeps (Laube), occurs in the Trias of St.

Cassian, Tyrol.

Our knowledge of this genus and family is

based largely on Lov6n's study of a single

minute specimen. As it has three columns

of plates in an interamhulacral area, it is

considered a further remove from the primi-
tive than those types with two columns. Three plates, representing three

columns, immediately succeeding the primordial interamhulacral plate, is a

unique character in Echini.

Fig. 425.

Macropneustes meneghinii Desor. Eocene ; Monte Spiado, near
Vicenza.

Fio. 426.

Tiarechinus %ii-inceps (Laube). Upper Trias ;
St. Cassian, Tyrol. Ventral and lateral
aspects, mncli enlarged (after Loven).

CLASR I ECHINOIDEA 299

Order 6. ECHINOCYSTOIDA Jackson.

Test irregulär, periproct apparently in 'an interamhulacrum. Two to four
columns of plates in an ambulacral area, and eight to nine columns of plates in an
interamlmlacral area. Plates thin, imbricating. Oculars and genitals doubtful.
Silurian.

Members of this order have been considered primitive, but structural
evidence is opposed to this view. This order includes the only exocyclic
Echini excepting that of the Exocycloida. The species are incompletely
known.

Family 1. Palaeodiscidae Gregory.

Two columns of plates in an ambulacral area and eight to nine columns of plates
in an interambulacral area. Primordial interambulacral plates in basicoronal row.
Base of corona not resorbed, Peristome with ambulacral plates only. Lantern
inclined, typically echinoid. Numerous fine spines.

Palaeodiscus Salter. With characters of the family. The only genus
known, many rows of ambulacral plates on the peristome. Silurian ;
England.

Family 2. Echinocystidae Gregory.

Four columns of plates in an ambulacral area, and eight columns of plates in an
interambulacral area. Small primary spines and tubercles. Jaws.

Echinocystites Wyv. Thomson (Cystocidaris Zittel). With characters of the
family. The only genus known. Silurian ; England.

Order?. PERISCHOEOHINOIDA M'Coy.

Test regulär, periproct within the oculogenital ring. Two to twenty columns of
simple plates in each ambulacral area, and three to fourteen columns of plates in each
interambulacral area. Plates imbricate or not. Primordial ambulacral plates on
peristome. Primordial interambulacral plates in basicoronal row, or resorbed. Base
of Corona not resorbed or resorbed. Oculars usually all insert. Genitals small,
typically with more than one pore each ; rarely (Lepidechinus) with one pore each.
Madreporite usually not recognisable. Periproct covered with many thick plates.
Peristome with many rows of ambulacral plates only, oi' in addition with interradial
non-ambulacral plates. Lantern inclined, composed of forty pieces, teeth grooved,
foramen magnum moderately deep, epiphyses narrow, no pits in top of pyramids.
Spines primary and secondary, or the latter only. Primary tubercles perfm'ate,
secondary tubercles imperforate. Silurian to Permian.

This Order includes the majority of Paleozoic Echini. All are specialised
in having multiple columns of interambulacral plates, and in many genera
multiple columns of simple ambulacral plates as well ; the order is therefore
considered a further remove from the primitive than are those Orders
with two columns of both interambulacral and ambulacral plates.

300

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

Family 1. Archaeocidaridae M'Coy.

Two columns of plates in an ambulacral area. Four to eight columns of plates
in an interambulacral area, imbricating . Primordial and additional interambulacral
plates are resorhed in the advance of peristome. Oculars, genitals and periproä
imperfeäly known. Peristome with many rows of ambulacral and interradial non-
ambidacral plates. Spines large primaries with perforate tubercles in the cenire of
each inferambidacral plate, also secondary spines and imperforate tubercles. Devonian
to Permian.

Eocidaris Desor. Known from fragmentary interambulacral plates and
spines, primary tubercles of plates without a basal terrace. Only one species
is recognised, E. laevispina (Sandb.). Devonian; Germany.

Archaeocidaris M'Coy. Ambulacral plates all alike, of equal height. Four
columns of plates in an interambulacral area. Primary spines large, tapering
or inflated, smooth or with lateral spinules. Primary tubercles with basal
terrace and scrobicular ring. Many species fragmentarily known. The most
completely known are A. wortheni Hall (Figs. 366, e; 371, Cy 427, Ä-C\
A. rossica (Buch), A. urii (Flem.). Lower Carboniferous and Carboniferous ;
Europe and North America. Permian ; North America and India.

Fio. 427.

Archaeocidaris wortheni Hall. Lower Carboniferous; Burlington, Iowa. A, Portion of ventral rogion,
showing jaws, i/i., B, An lArab plate viewed from above and from the side. C, Portion of Amh, enlarged.
D, Spina of A. keokuk Hall. Lower Carboniferous ; Warsaw, Illinois (after Hall),

Lepidocidaris Meek and Worthen. Ambulacral plates low, with also higher,
wider and wedge-shaped plates. Six to eight columns of plates in an inter-
ambulacral area. Primary spines cylindrical. Primary tubercles with no
basal terrace, but with a scrobicular ring. Lower Carboniferous ; North
America.

Family 2, Lepidocentridae Loven.

Two columns of plates in each ambulacral area. Five to fourteen columns of
plates in an interambulacral area. Primordial interambulacral plates in basicoronal
row. Base of Corona not resorbed. Oculars insert. Genitals with many pores each.
Peristome with many rows of ambulacral plates only. Spines small eccentrically

CLASS

ECHINOIDEA

301

placed primaries with secondaries, or the latter only. Siluriari to Lower.
Carboniferous.

Koninckocidaris Dollo and Buisseret. Test high, probably spheroidal ;
ambulacral plates high, two or three equalling the height of an adambulacral

Fig. 428.

A, Lepidmentrus rhenanus (Beyr.). üevonian ; Wipperfürth, Eifel. Gast of the interior of test showing
jaws, l/i (after J. Müller). B-D, Lejüdocentrus mülleri Schultze. Devonian ; Gerolstein, Eifel. B, Portion of
Amh, enlarged. C, Several lAmb plates, l/i ». D, Two detached lAmb plates, showing oblique edges, i/j.

plate, pore-pairs uniserial. Seven to eight columns of nearly rhombic plates
in an interambulacral area. K. silimca Jackson. Silurian ; North America.
K. cotteaui Dollo and Buiss. Lower Carboniferous ; Belgium.

Lepidocentrus Müller (Fig. 428). Test high, spheroidal, ambulacral areas
narrow throughout ; ambulacral plates low, about eight equalling the height

0«2 4 «

Fig.

A, Hyattecliinus pentagonus Jackson. External sandstone moulds. Lower Carboniferous; Meadville,
Pennsylvania. Ventral view showing introduction of columns and accelerated development of interanibulacra.
B, The same, dorsal view, showing fourteen columns in each interambulacral area and the dropping out
of soine columns dorsally. Both figures ^/lo natural size (after Jackson).

of an adambulacral plate, pore-pairs uniserial. Five to eleven columns of
plates in an interambulacral area. Small primary spines and tubercles with
secondaries on interambulacral plates. Devonian ; Germany and North
America. Lower Carboniferous ; North America.

Hyattechinus Jackson (Fig. 429). Test depressed to flattened ; through
the ambitus circular, pentagonal or clypeastriform. Ambulacral areas broad,

302

ECHINODERMATA— ECHINOZOA

PHYLUM IV

petaloid ventrally, narrow dorsally, pore-pairs uniserial. Eleven to fourteen
columns of plates in an interambulacral area. Small primary and secondary
tubercles on interambulacral plates. This genus is highly specialised,
particularly as regards the interambulacra which attain the greatest number
of columns of plates and the most accelerated development of the same known

A, Palaeechinus quadriserialis Wright. Lower Carboniferous ; Rathkeale, County Liinerick, Ireland, i/^.
B, Apical disk of same, 2/j. Restorations indicated by dotted lines. C, Same species, Middleton, County
Cork, Ireland. Ambulacral detail, enlarged (after Jackson).

in Echini. H. rarispinus (Hall) is a greatly flattened species, H. pentagonus
Jackson is pentagonal in outline, and H. beecheri Jackson is ventrally
flattened and bilaterally symmetrical. Lower Carboniferous ; North America.
Fholidechinus Jackson. Test high, spheroidal, ambulacral areas narrow
throughout, pore-pairs moderately biserial. Nine to ten columns of plates in
an interambulacral area. Secondary spines and tubercles only. Lower
Carboniferous ; North America.

CLASS I ECHINOIDEA 303

Family 3. Palaeechinidae M'Coy.

Test elliptical, ohovate, spherical or suhspheroidal. Two to twelve columns of
plafes in each amhulacral area, ihree to eleven columns of plates in each inter-
ambulacral area. Plates not imhricate, hut amhulacral plates hevel over the
interambulacral on adradial sutures. Primordial interambulacral plates resorhed.
One row only of interambulacral plates resorbed in advance of the peristome. Oculars
usually all insert, genitals usually with three to five pores each. Peristome with
many rows of amhulacral and some interradial non-amhulacral plates (Fig. 371, D).
Secondary spines and imperforate tuhercles only. Silurian (?), Lower Carboniferous.

Tliis family includes more species than any other in the Paleozoic. It
contains genera with complex ambulacra composed of more than two columns
of simple plates in an area, and the species in development pass throngh
stages like those of adults in all lower species or genera in the family. The
interambulacral plates are very definite in form, and the incoming of columns
indicate stages in development.

Palaeechinus M'Coy (Figs. 367, ^; 430: 431). Two columns of plates in

Fia. 431.

Palaeechinus elecjans M'Coy. Lower Carboniferous Limestxjne ; Ireland. A, Test, Vi (after M'Coy).
7i, Apical System, more than twice enlarged (after Jackson).

each amhulacral area, consisting of plates which are all primaries ; pore-pairs
uniserial. Four to six columns of plates in each interambulacral area. In
this lowest genus the amhulacral detail is like that seen as a developing stage
in the higher genera of the family. The test is elliptical, P. quadriserialis^
or nearly spherical, P. elegans. Lower Carboniferous ; Europe and North
America.

Maccoya Pomel (Fig. 367, k). Two columns of plates in each amhulacral
area, consisting of plates which are alternately primaries and partially or
completely occluded ; pore-pairs biserial. Four to eight or nine columns of
plates in each interambulacral area. In this genus, ventrally and dorsally,
amhulacral plates as stages in development are all primaries as in Palaeechinus.
M. phillipsiae Forbes is attributed to the Silurian (?) of England, other species
Lower Carboniferous ; Europe and North America.

Lovenechinus Jackson (Figs. 367, /; 432). Four columns of plates in each
amhulacral area, consisting of demi- and occluded plates ; pore-pairs biserial.
Four to seven columns of plates in each interambulacral area. While in this
genus there are four columns of amhulacral plates at the mid-zone, primary
plates as a stage occur ventrally and dorsally, L. septies. In L. missiouriensis
(Jackson) primary with occluded plates exist both ventrally and dorsally as a

304

ECHINODERMATA— ECHINOZOA

PHYLUM IV

second developmental stage. Lower Carboniferous ; Europe and North
America.

Oligoporiis Meek and Worthen (Fig. 367, m). Four columns of plates in
each ambulacral area, consisting of demi-, occluded, and in addition scattered
isolated plates ; pore-pairs multiserial. Four to nine columns of plates in each

J

Fig. 432.

Lovenechinus septies Jackson. Lower Carboniferous ; Boonville, Missouri. A, In the centre, spread out to
show structure and development, dotted lines indicate restorations. B, Lower left-hand figure, developing
ambulacrum ventrally, C, Lower right-hand ligure, ambulacrum near mid-zone. D, Upper riglit, developing
ambulacrum dorsally. E, Upper left, apical disl< with coronal contact. A, Natural size ; other ligures three
times enlarged (after Jackson).

interambulacral area. This genus differs from Lovenechinus in that it has
isolated plates in addition to the four columns of ambulacral plates. Lower
Carboniferous ; North America.

Melonechimis Meek and Worthen (Melonifes Norwood and Owen). (Figs.
366, d; 367, n; 371, D; 433). Six to twelve columns of plates in each
ambulacral area, consisting of demi-, occluded and one to four irregulär

CLASR I

ECHINOIDEA

305

columns of isolated plates in each half-area at the mid-zone ; pore-pairs
multiserial. Three to eleven columns of plates in each interambulacral area.
This genus has fourteen species with a wide ränge of characters. The lowest
species, M. dispar (Fischer von Waldheim) has six columns of ambulacral
plates, and is thus only one remove from Oligoporus. The highest species,
M. giganteus (Jackson) has twelve columns of ambulacral plates. At the
ventral border of the ambulacra there are typically four columns of plates
like the adult of Lovenechinus. From this stage passing dorsally isolated
plates first appear like Oligoporus, then additional columns, until the number

Fio. 433.

MdonecMnus viultiporuf^ (Norwood and Owen). Lower Carboniferous ; St. Lonis, Missouri.
1/2 natural size. B, Apical System, slightly enlarged (after Meek and Worthen).

A, Test,

characteristic of the species is attained. Dorsally some primary plates occur
next the oculars. Each species of Melonechinus presents developmental stages
in the ambulacrum like the adults of all lower genera, and lower species in
the family. The interambulacrum may have as few as three columns of
plates, as in AI. obovatus Jack., which is the least known in the family, though
this species has ten columns of ambulacral plates ; or there may be eleven
columns of plates as in the extreme form, M. giganteus (Jackson). Between
the extremes every step is represented in the genus by developmental or
adult characters, or both. Plates of the test are often very thick, and usually
more or less strongly elevated melon-like ribs occur in both ambulacra and
interambulacra, though these may be obsolescent or wanting, M. etheridgii
(Keeping). The peristome is known only in this genus for the family
(Fig. 371, D). Lower Carboniferous; Europe and North America.

Lepidesthidae Jackson.

Test elliptical, ohovate, spherical m' subspheroidal. Two to twenty columns of
plates in each ambidacral area. Three to thirteen columns of plates in each inter-
ambulacral area. Plates imbricate. Primordial interambulacral plates in basicoi'onal
row. Base of Corona not resorbed. Oculars usually all insert, genitals with one to
many pores each. Periproct plated wit\ many thick plates. Peristome with many
rows of ambulacral plates only. Primary spines with perfoi'ate tubercles^ usually

VOL. I X

306 ECHINODEEMATA— ECHINOZOA phylum iv

eccentric and irregularly distributed on interamhulacral plates, with secondary spines
and tubercles, or the latter only. Devonian to Permian.

This family presents a wide ränge of characters, and includes species with
very specialised features, particularly as regards an extreme development of
ambulacral areas.

Lepidechinus Hall (Ehoechinus Keeping). Two columns of plates in each
ambulacral area. Four to eight columns of plates in each interamhulacral
area. Plates quite thick, imbricating moderately. Secondary tubercles only.
Genital plates as far as known with only one pore each, the only instance
known in the Paleozoic. This genus, the lowest of the family, difFers from
Palaeechinus which it approaches, principally in the fact that the plates are
imbricate. The genus has been misunderstood because Hall referred to
it the species rarispinus, which is now referred to Hyattechinus. Lower
Carboniferous ; Europe and North America.

Perischodomus M'Coy (Fig. 366, h). Two columns of plates in each am-
bulacral area. Five columns of plates in each interamhulacral area. Plates
imbricating strongly. Eccentric perforate primary with secondary tubercles
on interamhulacral plates. Genital plates with many pores. The most
completely known species is P. biserialis M'Coy, Lower Carboniferous of Great
Britain ; a second imperfectly known is P. iUinoisensis Worthen and Miller,
Lower Carboniferous ; North America.

Perischocidaris Neumayr. Six columns of plates in each ambulacral area.
Five columns of plates in each interamhulacral area. Plates apparently
imbricating moderately. Eccentric primary tubercles on certain adradial
plates, with secondary tubercles on the same and usually alone on other
interamhulacral plates. Lower Carboniferous ; Ireland.

Proterocidaris Koninck. Four columns of plates in each ambulacral area.
T.welve to thirteen columns of plates in each interamhulacral area. Plates
strongly imbricating. Small primary with secondary spines and tubercles on
interamhulacral plates. Lower Carboniferous ; Belgium.

Lepidesthes Meek and Worthen {Eyboechinus Worthen and Miller) (Figs.
365, 367, 0 ; 434). Eight to sixteen columns of plates in each ambulacral
area. Three to seven columns of plates in each interamhulacral area. Plates
are strongly imbricating and are all of uniform size. Secondary spines and
tubercles only, Test elliptical, obovate or spherical. This genus has more
species and a wider geological ränge than any other of the family. Ambulacral
plates are very regulär in form, either rhombic or hexagonal. There may be
as many as sixteen columns of ambulacral plates in an area, e.g. L. colletti
White, in which species with an extreme ambulacral development there are
only four columns of interamhulacral plates (Fig. 434). In one species,
L. wortheni Jackson, there are eight columns of ambulacral plates with only
three columns of interamhulacral at the mid-zone, but there are four columns
ventrally as a youthful stage. Devonian ; Great Britain. Lower Car-
boniferous ; Russia, Great Britain, North America. Carboniferous ; North
America.

Pholidocidaris Meek and Worthen (Protocidaris Whidborne). Four to six
columns of plates in each ambulacral area. Five to six columns of plates in
each interamhulacral area. Plates strongly imbricating. Ambulacral plates
large ventrally, small dorsally ; interamhulacral plates dorsally very large in

ECHINOIDEA

307

adambulacral columns, smaller within. Eccentric primary spines and tubercles
with secondaries on dorsal adambulacral plates, and secondaries only on
interambulacral plates of dorsal median columns. This peculiar and specialised
genus is known best from the type species P. irregularis (Meek and Worthen).
Devonian ; Great Britain. Lower Carboniferous ; Europe, North America.

N

Fig. 434.

Lepidesthes colletti White. Lower Carboniferous ; Montgomery County, Indiana, x 2^/2.
Madreporite and periproctal plates distinet (after Jackson).

Meekechinus Jackson (Fig. 435). Twenty columns of plates in each
ambulacral area. Three columns of plates in each interambulacral area.
Plates of uniform size, imbricating strongly. Small central primary spines
and tubercles with secondary spines and tubercles on ambulacral and inter-
ambulacral plates. Teeth distally serrate, a unique character. This genus
with a Single species is one of the most specialised of known Echini, also it
is the geologically latest representative of its family. The twenty columns
of ambulacral plates occur only near the mid-zone, as further dorsally less
columns exist. This is the only Echinoid from the Paleozoic in which
pedicellariae have yet been found. Permian ; North America.

308

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

Geological Range and Distribution of the Bchinoidea.

Fossil Echini make their first appearance in the Ordovician, but are then
represented by but a single genus, Bothriocidaris, which on structural grounds
is a highly primitive type. In the Silurian of Great Britain occurs
the Order Echinocystoida, and in the American Silurian, Koninckocidaris, first
of the Lepidocentridae. In the Devonian one possible Cidarid occurs in
Europe and a number of genera of the Perischoechinoida in Europe and North

Fig. 435.
Meehechinus elegans Jackson. Permian ; Grand Summit, Kansas. Dorsal view of test with a distinct
madreporite and otherapical plates, enlarged, 2/^. Lower left-hand flgure, ambulacral plates with spines more
enlarged. Lower right-hand ügure Segment of interambulacrum with spines still more enlarged. Upper left-
hand figüre, pedicellaria much enlarged, 45/j (after Jackson).

America. In the Lower Carboniferous the Cidarids are represented by one
species of Miocidaris ; otherwise the whole Echinoid fauna is composed of the
Perischoechinoida, which order finds here its greatest development in genera
and species.

CLÄSS I ECHINOIDEA 309

In the Carboniferous very few Echini are known, and these belong to the
Perischoechinoida. The same order is represented by a few types in the
Permian which, with a single species of Miocidaris representing the Cidaroida,
are the only Echini known.

In the Trias, Cidarids occur and also the earliest representatives of the
Centrechinoida. In the same horizon also occurs Tiarechinus, representing
the peculiar order Plesiocidaroida.

Especially rieh in regulär Sea-urchins, as well as in members of the
Echinoneidae, Cassidulidae and Collyritidae are the Middle and Upper Jura
of England, France, Germany, Switzerland, the Alps and Northern Africa.
The Lower Cretaceous of the same region exhibits no essential change in
the Echinoid fauna ; but the advent of large numbers of the Ananchytidae
and Spatangidae in the Middle and Upper Cretaceous of Europe, Northern
Africa, Asia and North America imparts to these horizons a characteristic
appearance.

During the Tertiary the Cidaridae notably decline, the Echinoconinae
become entirely extinct, and the Clypeastroids and Spatangoids advance con-
spicuously into the foreground, taking on more and more the semblance of
Recent species. Tertiary Echinoids are of world-wide distribution and are
particularly plentiful in the Nummulitic Limestone of Europe, Northern
Africa, Asia Minor and India.

As to phylogenetic relationships, it is believed that strueture and develop-
ment should be the basis for such studies. While it is earnestly desired that
we should find fossils in the proper geological horizons representing every
Step in a genealogical sequence, it must be remembered that in the older
Paleozoic formations (Silurian and Devonian) Echini are extremely rare.
Eecent studies have yielded many new Paleozoic forms and have considerably
extended the geological ränge of genera, families and Orders, so that it is not
too much to expect that future discoveries will yield material of first
importance to a knowledge of the group. Echini are an essentially circum-
scribed group and no known type presents a close approach to any other class
of Echinoderms. Though the ancestor of the class is unknown, it seems that
it might fairly be sought among the Cystids.

The most primitive known Echinoid structurally is the Ordovician
Bothriocidaris, sole representative of its order, which in the adult has
characters that appear as stages in development in all other Orders of Echini.
Bothriocidaris, with ten columns of ambulacral and five columns of inter-
ambulacral plates, in these characters represents the simplest known type.

The next step structurally is ten columns of ambulacral and ten of inter-
ambulacral plates. This strueture is the character of the Cidaroida,
Centrechinoida and Exocycloida. Of these Orders the Cidaroida with simple
ambulacral plates is certainly the most primitive as well as geologically the
oldest. The Centrechinoida typically have Compound plates formed by the
coalescence of simple plates. Of this order the Aulodonta are the most
primitive group, make the nearest approach to the Cidaroida structurally, and
also geologically are the oldest of the order. The Stirodonta as regards the
strueture of the lantern (keeled teeth) are further removed from the primitive
than the Aulodonta. The Camarodonta are the last expression of differentia-
tion of the Centrechinoida in regard to the strueture of the lantern (keeled
teeth with wide epiphyses joining in suture over the foramen) and also in

310 ECHINODERMATA— ECHINOZOA phylum iv

ambulacral differentiation. This group appears last geologically and has its
füllest expression at the present time, The Exocycloida with an eccentric
periproct is a homogeneous group. The structure of the lantern (keeled
teeth) with other characters affiliate the basal members with the Stirodonta.
Of this Order the Holectypina on the basis of the lantern structure, perignathic
girdle and ambulacral detail, make the nearest approach to the Stirodonta.
The Clypeastrina, by the characters of the lantern, perignathic girdle and
petaloid ambulacra composed of simple plates, are further removed from the
primitive than the Holectypina. The Spatangina, which have lost the lantern
in adults and have attained an extreme of differentiation in ambulacral
structure, bilaterality and an eccentric peristome, may well be considered the
most specialised group of the Exocycloida, and therefore the furthest removed
from the primitive.

Up to this point each order is characterised by having two columns of
ambulacral plates, and either one or two columns of plates in each inter-
ambulacral area. The next step in structural differentiation is two columns
of ambulacral and three columns of interambulacral plates. This is the
character of the Plesiocidaroida which is further marked by an exceptionally
large apical disc which is a primitive feature.

The next step structurally is types with two or more columns of simple
ambulacral plates and three or more columns of interambulacral plates, with
a small apical disk which is a progressive character. The Echinocystoida
with eight or more columns of interambulacral plates fall in this group.
This Order is incompletely known, especially as regards the apical disk and
the periproct, which last appears to be eccentric in an interambulacrum,
separating it radically from all of the Perischoechinoida. The Palaeodiscidae
is the more primitive family, with two columns of ambulacral plates ; the
l^chinocystidae is the more specialised family with four columns of ambulacral
plates.

The Perischoechinoida include all remaining Echini ; primitive as regards
the lantern, they are specialised in the interambulacrum, frequently in the
ambulacrum, and also in having a small apical disk. The Archaeocidaridae
have two columns of ambulacral plates and in so far are primitive, but they
have from four to eight columns of interambulacral plates ; very large spines
(for the Paleozoic) ; ambulacral and non-ambulacral plates on the peristome
and much resorption of the base of the corona, specialised. *rhe Lepido-
centridae have also two columns of ambulacral plates. The family attains
many (5 to 14) columns of interambulacral plates, progressive ; ambulacral
plates only on the peristome and no resorption of the base of the corona,
primitive. The Palaeechinidae may have two columns of ambulacral plates
only, but typically more (up to twelve) with three to eleven columns of
interambulacral plates ; plates not imbricate, secondary spines only, ambu-
lacral with non-ambulacral plates on the peristome, slight resorption of the
base of the corona. The Lepidesthidae may have two columns of ambulacral
plates only, but typically more (up to sixteen or twenty) with three to
thirteen columns of interambulacral plates, plates imbricate, primary and
secondary spines, or the latter only, ambulacral plates alone on the peristome,
no resorption of the base of the corona as far as known.

In almost all of the above Orders and families by the study of stages in
development, characters have been found in which the individual repeats the

CLASS I

ECHINOIDEA

311

characters seen in the adults of the preceding series, or lower members of its
own series.

Geological Range of the Echini

Orders and Faniilies of Echini.

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Order 1. Bothriocidaroida
Order 2. Cidaroida
Order 3, Centrechinoida
Suborder A. Aulodonta

1. Hemicidaridae

2. Aspidodiadeniatidae

3. Centrechinidae

4. Echinothuriidae
Suborder B. Stirodonta

1. Saleniidae

2. Pliymosomatidae

3. Storaopneustidae

4. Arbaciidae
Suborder C. Camarodonta

1. Echinidae

2. Temnopleuridae

3. Strongylocentrotidae

4. Echinometridae
Order 4. Exocycloida

Suborder A. Holectypina
Suborder B. Clypeastrina

1. Clypeastridae

2. Fibulariidae

3. Scutellidae
Suborder C. Spatangina

1. Echinoneidae

2. Cassidulidae

3. Collyritidae

4. Anancliytidae

5. Spatangidae

6. Palaeostomatidae

7. Pourtalesiidae
Order 5. Plesiocidaroida
Order 6. Echinocystoida
Order 7. Perischoechinoida

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[To Dr. Robert Tracy Jackson, of the Boston Society of Natural History, acknowledgments
are due for having revised the preceding chapter on Echinoidea. A number of new illustra-
tions have been reproduced from this author's recently published monograph on the Phylogeny
of the Echini. — Editou.]

312

ECHINODERMATA— ECHINOZOA

PHYLÜM IV

Olass 2. HOLOTHURIOIDEA von Siebold.i

The Holothurians, or Sea-cucumbers, difFer markedly from all other
Echinoderms in their elongated bodies with little or no skeleton. The mouth
and anus are with rare exceptions more or less nearly terminal at opposite
poles, and the former is always surrounded by a circle of tentacles, 8-30 in
number. The skeleton is represented by calcareous particles in the body
wall, which are commonly microscopic and dissociated, but are sometimes
several millimetres across, and in rare cases may even be closely united with
each other to form a rigid body wall. In some species skeletal particles are
nearly or quite wanting.

The paleontological evidence bearing on the history of Holothurians is
very slight. Fossils occur in two forms, either as impressions or casts of the

Fkj. 435 Ms.

Eldonia ludwigi Walcott. Middle Cambrian (Burgess shale formation) ; British Columbia. Specimen
flattened in the shale and showing traces of internal organs. er and rc, Central ring and radial canals of
vascular System ; i, Intestine ; o, Oral aperture ; oc, Oral Chamber ; oe, Oesoijhagus ; s, Stomach ; t,
Tentacles ; ul, Umbrella lobes, crushed and macerated ; x-x, Junction - point of i stomach and intestine ;
a, Position of anus. Natural size (after Walcott).

whole animal, or as dissociated skeletal particles preserved in very fine
limestones or shales. Of impressions or casts, the earliest described are

^ Literature : Giebel, G., Zur Fauna des lithographischen Schiefers von Solenhofen. Holothu-
rienreste. Zeits. f. gesammt. Naturw., 1857, vol. ix. — Schlumherger, G., Note sur les Holothuridees
fossiles du Calcaire Grossier. Bull. Soc. Geol. France (3), 1888, vol. xvi. — Idem, Second Note
sur les Holothuridees fossiles. Bull. Soc. Geol. France (3), 1890, vol. xviii. — Ludwig, H., Die
Seewalzen. Bronn's Klassen und Ordnungen des Thierreichs, vol. ii., part 3, 1889-92. — Spandel,
E., Die Echinodermen des deutschen Zechsteins. Abh. Ges. Nürnberg, 1898, vol. xi. — Idem, Eine
fossile Holothurie. Dp. cit., 1900, vol. "xiii. — Wcdcott, G. D., Middle Canibrian Holothurians
and Medusae. Smiths. Mise. Coli., 1911, vol. Ivii., no. 3. — Glark, H. L., Fossil Holothurians.
Science, 1912, n.s. vol. xxxv. — Glark, A. H., Restoration of Eldonia. Zool. Anz., 1912, vol. xxxix.

CLASS II HOLOTHURIOIDEA 313

those made known by Giebel from the Lithographie limestone of Solenhofen.
These he called Protholoturia, and though the material does not permit of exact
generic determination, it bears a resemblance to certain Recent species of
Holothuria and Pseudosiichopus. The impression formed by the general appear-
ance of these specimens that they really represent Holothurians is confirmed
by the presence of characteristic calcareous particles on their surface.

Recently, in the remarkably well - preserved fauna from the Middle
Cambrian shales of British Columbia, Walcott has discovered some complete
specimens of typical Holothurians, preserving many details of the original
animals. Most of these species are referred by A. H. Clark to the family Elpi-
diidae (a group of very remarkable Holothurians at the present time confined to
the deep sea),"but one of them, Eldonia (Fig. 435 bis), representing the new family
Eldoniidae, was free-swimming like the Recent Pelagothuria, though structurally
entirely difFerent from that type, being most nearly related to the Elpidiidae.

Dissociated calcareous particles referred to Holothurians have been
described by a number of writers from the British Carboniferous rocks, the
Zechsbein of Germany, the Lias and Dogger of Lorraine, the Upper Jura of
Franconia, the Cretaceous of Bohemia, the Eocene of Paris, the Oligocene of
Offenbach, the Pliocene of Italy and the post-Tertiary of Scotland. A very
large majority of these cannot be assigned to any particular genus or even
family of Holothurians, and it is probable that many if not most are of other
than Holothurian origin. There can be no question, however, that a part
of this material is of real paleontological value. In particular the forms
described by Schlumberger and by Spandel are worthy of attention.

Spandel's discovery of what seem to be unquestionable Holothurian
spicules, like those characteristic of the genus Chiridota, in the Zechstein of
Germany, is noteworthy. These spicules are distinctly wheel-shaped, but
differ noticeably from those of Recent Chiridota in having 10-14 spokes instead
of six. They thus show a certain resemblance to the wheels of Trochoderma
and the first formed calcareous deposits of the larvae of Chiridota rotifera and
certain Auricularias. Spandel's later discovery of an Oligocene Synapta, and
Schlumberger's studies on the Eocene Holothurian spicules of the Calcaire
Grossier, show that during the Tertiary period the Synaptidae were already
difFerentiated into the three Recent subfamilies, Synaptinae, Chiridotinae and
Myriotrochinae. Beyond this grouping we cannot speak with any certainty.

Our actual knowledge of fossil Holothurians may be summed up as follows :

1. Holothurians allied to living members of the class existed in the Jurassic
seas of Europe, and, according to Walcott's Interpretation, there is evidence
that the typical expression of the group was already differentiated as early
as the Cambrian.

2. Holothurians of the family Synaptidae, allied to Chiridota or Trochoderma
occurred in the Permian seas of Europe ; and at least as early as the Eocene,
all three of the Recent subfamilies of Synaptidae were differentiated.

3. The Permian Holothurian spicules are wheel-shaped but have numerous

spokes as in Trochoderma, and resemble those of the larval Chiridota, not those

of the adult.

[The account here given of Holothurians, with the exception of the paragraph in regard
to Cambrian repräsentatives of the class, has been contributed by Dr. H. L. Clark of the
Harvard Museum of Comparative Zoology.— Editor.]

Phylum V. MOLLUSCOIDEA.

Under the term Molluscoidea, Milne Edwards included the Bryozoa and
Tunicata, of which the first had been previously regarded as Zoophytes, and
the second as Molluscs. Huxley afterwards assigned the Brachiopoda to the
same phylum. The Tunicata have more recently been regarded as an in-
dependent animal type, and as possible progenitors of the Vertebrate phylum.
Their remains, however, are unknown in the fossil state. Bryozoans, also
called Polyzoa, are by some authors regarded as constituting a distinct phylum
of invertebrates, but are here retained in association with Brachiopods.

The typical Molluscoidea either secrete a calcareous shell, or are invested
with a membranaceous or corneous covering. The respiratory organs lie
anterior to the mouth, and are in the form of tentacles or fleshy spiral
appendages. The mouth conducts into a closed alimentary canal. The
nervous system is highly organised, and proceeds from a central ganglion,
situated in most cases between the mouth and the anus. Reproduction is
either sexual or, in Bryozoa, also takes place by budding. The ontogeny of
the Molluscoidea is most nearly comparable with that of the Annelids.

All of the Molluscoidea are water inhabitants ; the Bryozoans are largely,
and the Brachiopods exclusively, marine forms.

Olass 1. BRYOZOA Ehrenberg.i

Small, almost always composite animals forming by gemmation variously shaped
colonies, each zooid of which is enclosed in a membranaceous or calcareous double-

^ Literature : d'Orhigny, A., Paleontologie francaise ; Terrain cretace, vol. v., 1850-51. — Hagenow,
F., Die Bryozoen der Maestricher Kreidebildung. Cassel, 1851. — Haime, J., Description des
brjozoaires fossiles de la formation jurassique. Mem. Soc. Geol. de France, 2nd ser. vol. v., 1854.
• — Bush, O., Catalogue of Marine Polyzoa in the Collection of the British Museum (Parts i. and ii.,
Cheilostomata), 1852-54. (Part iii., Cyclostomata), 1875. — Bush, G., Monograph of the fossil
Polyzoa of the Crag. Palaeont. Soc, 1859. — Oahh, W. M., and Hörn, G. H., Monograph of the
fossil Polyzoa of the Secondary and Tertiary Formations of North America. Journ, Acad. Nat. Sei.
Philad., 2nd .ser., vol. v., 1862. — Beissel, /., Ueber die Bryozoen der Aachener Kreidebildung.
Haarlem, 1865. — Reuss, A. E:, Several important papers in Denkschr. Akad. Wiss. Wien, vols.
xxiii., xxxiv., 1863-74 ; and Palaeontographica, vol. xx., 1872-74. — Manzoni, A., Several im-
portant contributions on Tertiary Bryozoans in Denkschr. Akad. Wiss. Wien, 1869-78, vols,
xxix.-xxxviii. — Waters, W. A., Numerous papers on Tertiary and Recent Bryozoa in Ann. and
Mag. Nat. Hist. and Quar. Journ. Geol. Soc, 1879-92. — Hincks, T., History of the British Marine
Polyzoa, 2 vols., 1880. — Vine, G. R., Reports on fossil Polyzoa. British Assoc. Reports, 1881-85.
— Ulrich, E. 0., American Palaeozoic Bryozoa. Journ. Cincinnati Soc. Nat. Hist., v.-vii., 1882-84.
— Busk, G., Report on Polyzoa. Scient. Results Challenger Exped., Zoology, vols. x. and xvii.,
1884-86. — Hall, J., Lower Helderberg, Corniferous, and Hamilton Bryozoa (Palaeont. N.Y., vol.
vi.), 1886. — Ulrich, E. 0., Palaeozoic Bryozoa. Geol. Survey Illinois, vol. viii., 1890. — Ulrich,
E. 0., Lower Silurian Bryozoa. Geol. Survey Minnesota, Final Report, vol. iii., 1892. — Gami, F.,

314

CLASS I BRYOZOA 315

walled sac {zocedum), and possesses typically a freely suspended alimentary canal
with mouth and anns. Mouth surrounded by a crown of hollow, slender, ciliated
tentacles arranged in the form of a circle or crescent. Usually hermaphroditic.

Tlie Biyozoa resemble certain Corals (Tabulata) and Hydrozoans in their
external configuration, but differ from tbem radically in the possession of a distinct
body cavity, a closed alimentary canal, a highly developed nervous System, and
delicate respiratory tentacles siirroimding tbe moutb. With the exception of the
solitary geniis Loxosoma, all Bryozoans live associated in colonies or zoaria, of greater or
less extent, and of either calcareoiis, corneous or membranaceous composition. These
colonies, which are formed by frequently repeated gemmation, present a multitudinous
variety of form, habit and structure. Sometimes they grow into plant-like tufts,
composed of a series of cells variously linked together ; very commonly they spread
over Shells and other foreign bodies, forming delicate interwoven threads, crusts of
exquisite pattern, or hemispherical, globular or nodular masses of considerable size ;
often they rise into branching stems, and fronds of varying width ; and at other times
the cell-bearing branches form most regulär and beautiful open-meshed lace-work.

Each zooid or polypide is enclosed in a separate Chamber (zooscium) of either
utricular or more or less tubulär form. Occasionally the zooecia are quite distinct
from their neighboui's ; more commonly, however, intercommunication is effected,
either by means of niinute " connecting foramina " piercing the Chamber walls, or
by a common canal to which all the zooids are attached. A true coenenchyma,
such as is found among the Coelenterates, never occurs, and coenenchymal gemmation
is accordingly unknown ; but a somewhat similar " vesicular tissue " not infrequently
occupies the interzooecial spaces which have resulted from the erection of the zocecial
tubes.

Such vesicular tissue occurs constantly in the Fistuliporidae and Cystodictyonidae, and in
the latter the primary, or even the prostrate cells, are not entirely contiguous. The upper
walls of the vesicles, at least, are abundantly perforated ; and when with increasing age the
vesicles beconie fiUed with a secondary deposit, these pores are not obliterated, but continue to
pass through such deposits in the form of minute vertical tubes. Precisely the same kind of
tissue occurs in other Bryozoans, notably among adult colonies of certain Fenestellidae, in
which the expanded base of the colony is largely vesicular, and the fenestrules and spaces
between the carinae of the branches are filled with vesicles for some distance up. The real
purpose of this tissue is to support the zooecia and to strengthen the zoarium.

However diverse the external aspect of the composite structure, the small animals
themselves conform to a simple and quite definite type. Briefly, the soft parts consist
of an alimentary canal, in which three distinct regions, an Oesophagus, stomach and
intestine, are recognisable. This is enclosed in a sac, and so beut upon itself that its
two extremities, or openings, approximate ; one of them, the oral, being either entirely
or partially surrounded by a row of slender, hollow and ciliated tentacles, which serve
for respiration and for sweeping food toward the mouth. In most cases the anal
opening is situated without the ring of tentacles (Ectoprocta), rarely within the same
(Entoprocta). Heart and vascular system are wanting, but a nervous ganglion, sending

Nunierous papers on Mesozoic and Cenozoic Bryozoa in the Bull. See. Gi^ol., France, 1897-1910. —
Ulrich, E. 0., Eocene Bryozoa. Eocene volume, Md. Geol. Surv., 1901.— Ulrich, E. 0. and Bassler,
R. S., Miocene Bryozoa. Miocene volume, Md. Geol. Surv., 190\.— Ulrich, E. 0. and Bassler, R. S.,
Revision of tlie Paleozoic Bryozoa. Smith. Mise. Coli., vols. xlv.-xlvii., 190i.—Nickles, J. M. and
Bassler, R. S., Synopsis of American fossil Bryozoa. Bull. 173, U.S. Geol. Surv., 1901. (Contains
a list of all bryozoan literature and a bibliograpliy of fossil forms.) — Bassler, R. S., Bryozoan Fauna
of the Rochester Shale. Bull. 292, U.S. Geol. Surv., 1906.— Gregor]/, J. W., Cat. Cretaceous
Bryozoa in British Museum, 2 vols., 1899 and 1909.— Levinsen, G. M. R., Cheilostomatous
Bryozoa (Recent). Copenhagen, 1909.— Bassler, R. S., Early Paleozoic Bryozoa of the Baltic
Provinces. Bull. 77, U.S. Nat. Mus., 1911.— Ilennig, A., Gotlands Silurische Bryozoen. Arkiv
Zool., 1908, vol. iv. — Canu, F., Iconographie des bryozoaires fossiles de I'Argentine. Anal. Mus.
Nac. Buenos Ayres, 1909-11, ser. 3, vol. x.—Lee, O. W., British Carboniferous Trepostomata.
London, 1912.

316 MOLLUSCOIDEA phylum v

out delicate nerve filaments to the tentacles and Oesophagus, lies between tlie mouth
and anus. The upper or anterior part of the sac is generally flexible and admits of
being invaginated by the action of numerous, longitudinal and transverse muscles,
which traverse the fluid -filled visceral cavity.

Eeproductive organs are developed in various parts of the cavity, the spermatozoa
usually in the lower, the ova in the upper portion. The ova may be develoj)ed in a
special receptacle (marswpium) attached to the zooecium, or in an inflation of the
surface of the zoarium (gonocyst) ; in other cases, a modified zocecium (gonoecium) is set
apart for reproductive functions. The general term omcium or ovicell is applicable to
all of these structures.

Many Bryozoans are provided with appendicular organs known as avicularia and
vibracula (Fig. 436). Their functions are somewhat doubtful, some authors regarding
them as food-procuring agents, and others as organs of defence.
The avicularia may be immovably attached to the zocecium ;
but, as a rule, especially among Recent forms, they are peduncu-
late, and capable of considerable swaying motion. Often, as in
Bugula and Bicellaria, they resemble the head of a bird, con-
sisting of a helmet-shaped upper piece, with a formidable hooked
beak, and a mandible worked by powerful muscles. The jaws
open and close with a perpetual snapping motion, and small
organisms or other foreign particles hapj^ening in their way are
seized and held with a tenacious grasp. The vibracula are
flexible, bristle-like appendages, generally set in the excavated
summit of a knob-like elevation, or on a blunt spine.

The avicularia and vibracula are themselves incapable of

Fig. 436. preservation, but their former presence on fossil specimens may

Selenaria maculata be generally determined by the slight pore-like excavations in

portL^o7up%f See which they were lodged. The tubulär spines, or acanthopores,

showing a vibracuium which are of such common occurrence in Paleozoic Bryozoans,

and ovicell (after Busk). . ..i. it_i.i , n • -i . .

were, m part at least, probably the supports of similar structures.

The term lunarium is applied to a more or less thickened portion of the posterior
wall in many Paleozoic Bryozoans, which is curved to a shorter radius and usually
projects above the plane of the zooecial aperture. Mesopores are angular or irregulär
cells occupying interzocecial Spaces in certain Paleozoic genera.

Most Bryozoans are attached, either by the greater part of their surface, or only
basally, to extraneous objects ; or they are moored to the bottom by root-like appen-
dages. In many forms the zoarium is regularly jointed. The majori ty of genera
inhabit the sea, and occur in all zones and at all depths ; only a few genera live in
fresh water. The animals subsist chiefly on Diatoms, Infusorians and larvae.

Classification. — The Classification of the Bryozoans remains as yet in an unsatis-
factory condition. D'Orbigny's comprehensive System is largely artificial, and
although numerous modifications and improvements have been suggested by later
authors, further revision has still to be undertaken.

Lankester divides the class into two very unequal subclasses as foUows : (1)
Holobranchia, in which the lophophore or row of tentacles is unbroken, and either
circular or horse-shoe shaped ; and (2) Pterobranchia, containing the single genus
Rhahdopleura, which has the lophophore produced on either side into a plume-like
process, so that the tentacles form a discontinuous series.

A more modern System is to regard Bryozoans as a primary group or phylum,
which is divided into two unequal classes, named by Nitsche, Ectoprocta and Ento-
procta, according as the lophophore surrounds the mouth only, or encloses both the
oral and anal orifices. The first of these classes contains the bulk of the known
Bryozoa. Furthermore, the marine forms, and practically all genera capable of pre-
servation in the fossil State, are included in the subclass Gymnolaemata Allman.

CLASS I

BEYOZOA

317

Tliis is distinguished from the remaining subclass, Phylactolaemata AUman (which
includes tlie freshwater forms), by the complete abortion of tlie foot, and ]jy the
cii'ciüar arrangement of tlie tentacles.

The Mesozoic and Recent marine Gymnolaeniata are almost universally divided
into the three Orders proposed by Busk : the Cyclostomata, Cheüostomata and Cteno-
stomata. To these Vine has added a fourth, the Cryptostomata, and Ulrich a fifth,
the Trepostomata ; both of which serve mainly for the reception of Paleozoic forms.

The detailed Classification of the Mesozoic and Cenozoic Bryozoa, especially of the
Cheilostomata, is less settled than that of the ancient types. This nonconformity is
due in part to the widely different views prevailing among authors as to the relative
value of the various characters upon which the groups are founded ; and partly
because the mode of growth and zoarial characters in general are much less constant,
and, therefore, less reliable than is the case among Paleozoic representatives of the
group.

Subclass 1. GYMNOLAEMATA AUman.
Order 1. CTENOSTOMATA Busk.

Zoüßcia usually isolated and developed hy hudding from the internodes of a distinct
tubulär stolon or stem. Orifice terminal, with an operculum of setce. Zoarium horny or
memhranaceous. Marsupia wanting.

All of the known Paleozoic Ctenostomata have been described by Ulrich and Bassler in their
Revision of the Paleozoic Bryozoa, to which the student is referred for a discussion of these
peculiar fossils. Mesozoic and Cenozoic Ctenostomatous Bryozoa are apparently rare and little
study has been put upon tliem. In the Recent seas, the order Ctenostomata is specifically the
least represented group of Bryozoa, although some of the species are quite abundant and
widespread.

/) ^
Family 1. Rhopalonariidae

Nickles and Bassler.

Fusiform segments arranged
in a more or less pinnate
manner, impressed or almost
emhedded in the host.

Rhopalonaria Ulr. (Fig.
437, G). Ordovician to Lower
Carboniferous.

? Terebripora d'Orb. Ter-
tiary and Recent.

Family 2. Vinellidae
Ulrich and Bassler.

Creeping hase of zoarium
of simple or locally jointed,
delicate, tubulär threads ar-

Fio. 437.
Allonema fusiforme (N. and E.), 6/1.

_ _ _ B,C, Vlnella repens Ulr., 2/3

ranged' either without order or ^^^^'""Ti-^Ki^^^^

^ ,. . , and B., 6/1. F, Hcteronema capiUareJJ. and B., ^/i. G, RhojKilonana

proceeding from more or less «enuis U. and ß., 6/i(after Ulrich and Bassler).

deßnitely marked centres. In-
ternodes with a Single row of pores or, in one genus, closely punctate ; zooecia unknown.

Vinella Ulrich (Fig. 437, 5, 0). Zoarium of very slender parasitic tubulär threads

318 MOLLUSCOIDEA— BRYOZOA phylüm v

or stolons arranged radially ; surface with a single row of pores. Ordovician to
Lower Carboniferous.

Heteronema Ulr. and B, (Fig. 437, F). Zoaria as in Vinella but threads are with-
out radial arrangement. Ordovician to Upper Carboniferous,

Allonema Ulr. and B. (Fig. 437, A). Zoaria composed of distinct, minutely
punctate vesicles or connected internodes. Silurian to Lower Carboniferous.

? Ptychocladia Ulr. and B. Upper Carboniferous.

Family 3. Ascodictyonidae Ulrich.

Zoaria parasitic, of pyriform porous vesicles arranged in radial Clusters, or isolated
and connected hy delicate hollow threads.

Ascodictyon Nich. and Etil. (Fig. 437, D, E). Silurian to Lower Carboniferous.

Order 2. CYCLOSTOMATA Busk.

{Bryozoaires centrifugine's d'Orbigny p.p.)

Zocecia very simple, cylin^rical, calcareous, tubulär, usually without transverse parti-
tions ; the orifices piain, inoperculate, not contracted, occasionally expanded ; walls thin,
minutely porous; apertural portion- of zooecial tuhes more or less raised, hent outwards,
free or in bundles ; the interspaces with or without solid or tubulär strengthening deposits.
Marsupia and appendicular organs wanting. Ocecium a large cell set apart for repro-
ductive functions, or a mere inßation of the zoarial surface.

The families and genera of tliis order are founded almost entirely upon the form of the
zoarium, and the arrangement of the zocecia. The presence or absence of interstitial or
accessory cells and vesicular tissue (all strengthening deposits) is also an iiiiportant character,

For many years it was customary to regard all Paleozoic Bryozoans as Cyclostomata, but
the labours of Ulrich and Vine have clearly demonstrated the fallacy of such an assumption.
The families Ceramoporidae and Fistuliporidae, often regarded as Trepostomata or ^'Ifonticuli-
poroids," aivereferred tothe Cyclostomata because they agree with its most typical members in
having amalgamated and minutely porous walls. In 1890 Ulrich discovered ovicells in certain
genera of the Fistuliporidae, while more recently Bassler lias shown the occurrence of the
same structures in the more primitive Ceramoporidae.

Suborder A. TUBULIPORINA Hagenow. (Tubulata Gregory).

Zocecia monomorphic, of elongated, cylindrical tubes grouped into bundles, sheets or
linear series. The Tubuliporina comprise the typical Cyclostomata and in all probability
give rise to the other suborders.

Family 1. Orisiidae Busk.

Zoaria dendroid, attached by radical tubes and composed of segments united by corneous
joints. Zocecia tubulär, disposed in single or double series.

Grisia Lamx. {Grisidia Jolinst. ; Filicrisia d'Orb.). Zoaria more or less distinctly
articulated, the zooecia in a single or in two alternating series. Cretaceous to Recent.
? Unicrisia d'Orb. Cretaceous.

Family 2. Diastoporidae Busk (emend.).

Zoaria adnate, adhering by the entire base or only at the centre, at other times rising
into bifoliate leaves or hollow stems. Zooecia tubulär, the aperture salient, rounded, never
clustered. Interstitial cells wanting. Ovicells mere irregulär inflations of the surface of
the zoarium, with one or more openings. Ordovician to Recent.

ORDER II

CYCLOSTOMATA

319

Stomatopora Bronn {Alecto Lamx. non Leach) (Fig. 438). Zoaria delicate, adnate,
dicliotomously brancliing. Zooccia sub-tubular or elongate-ovate, arranged in a single

Fio. 438.

Stomatopora dichotoma (Lamx.).
GreatOolite; Ranville, Calvados.
A, Zoarium, i/i. B, same, en-
larged.

Fig. 439.

A, Corynotrypa delicatula (James). Utica Group ; Ciiicinnati, Ohio.
Zooecia, lö/i. B, C. inflata (Hall). Lorraine Group ; Cincinnati, ö/j.
C, Prohoscina frondosa Nich. Lorraine Group ; Cincinnati, Ohio. Portion
of a large zoarium, i2/j (after Ulrich).

series ; apertures siib-terminal, iisually smaller than the width of the cell. Ordovician,
Jura, Cretaceous, Tertiary and Recent.

Corynotrypa Bassler {ßtomatopora in part, auct.) (Fig. 439, A, B). Zoarium
unilinear, adnate, witb short to elongate, clavate zooecia. Ordovician to Devonian.

Prohoscina Audouin (Fig. 439, C). Like Stomatopora but zocecia arranged in two
or more series. Ordovician, Mesozoic to iRecent.

Berenicea Lamx, {Diastopora Busk, non Lamx.) (Fig. 440). Zoaria forming tbin,
discoid, flabellate or irregulär crusts upon foreign bodies. Zooecia arranged in
irregularly alternating lines. Rare in Ordovician and Silurian, very abundant in
Jura and Cretaceous, less frequent in Tertiary and Recent,

Berenicea diluviana Lamx. Great Oolite ;
Ranville, Calvados. A, Young expansiou,
Vi. B, same, enlarged (after Haime).

Fig. 441,

Diastopora foUticea (Lamx.). Great Oolite ;
Ranville, Calvados. A, Fragment of zoarium,
Vi- B, Enlarged portion of same.

Discosparsa d'Orb. Differs from Berenicea in having obconical or cup-shaped
zoaria, attaclied by centre of the base only. Cretaceous and Tertiary.

Filisparsa d'Orb. Zoarium ramose, brancbes compressed dorso-frontally; apertures
irregularly disposed, Cretaceous to Recent.

Diastopora Lamx. {Mesenteripora Blv.) (Fig. 441). Like Berenicea^ except that
the zoarium rises into broad, simple or convoluted leaves, composed of two layers of

320

MOLLUSCOIDEA— BRYOZOA

PHYLÜM V

zocßcia grown back to back. Very abundant in the Jura, less common in Cretaceous
and Tertiaiy.

Bidiastopora d'Orb. Like Diastopora, but the zoaria forming only narrow, parallel-
edged brancbes. Cretaceous.

ReptomuUisparsa, Cellulipora and Filicrisina d'Orb. Cretaceous.

Diastoporina Ulrich. Ordovician. Heder ella and Hernodia Hall ; and Reptaria
Rolle. Devonian.

Family 3. Idmoneidae Busk.

Zoaria forming free or adnate, variously compressed hranches. Zocßcial apertures
rounded, more or less elevated, usually arranged in transverse rows on two faces of the
hranches ; sometimes the two faces are confluent. Dorsal surface of the hranches without
zooecia, hut often occupied hy numerous small tubulär pores, which may also occur near
the apertures. Sac-like ovicells with hut a single opening. Ordovician to Recent.

Idmonea Lamx. Zoarium adnate with apertures opening in transverse series.
Jurassic to Recent.

Grisina d'Orb. (Fig. 442). Zoarium erect, simple or branching. Brauches
usually triangulär, two of the faces carrying the zooecial apertures, which are generally
arranged in alternating transverse series. Jurassic to Recent.

Bisidmonea d'Orb. Quadrate,
simple or branching stems, bear-
ing zooecial apertures on all faces.
Cretaceous,

Retecava d'Orb. Zoaria reti-
culated ; branches greatly com-
pressed laterally ; reverse side
occupied by an axial rod. Cre-
taceous.

Bicrisina, Bituhigera, Repto-
fascigera, Semiclausa, Sulcocava
{Laterocava) d'Orb. ; and Pergen-
sella Gregory. Cretaceous.

Phalangella Gray. Creta-
ceous to Recent.

Protocrisina Ulr. (Fig. 443).
Narrow, bifurcating branches, celluliferous on one side only. Zocecia sub- tubulär,
with prominent circular apertures arranged in intersecting diagonal series. Small
pores, apparently communicating with interior of the zocecia, irregularly distributed
over both faces of the branches. Ordovician and Silurian.

Fig. 442.

Grisina dorsata Hagenow,
Cretaceous; Maastricht. J, Brauch, nat.
size. B, Upper, and C, Lower side, highly
magnifled.

Uppermost

Fig. 443.

Protocrisina exigua
Ulrich. Trenton
Group; Trenton,
N.Y. Branches of a
large expansion, i^^/i.

Family 4. Entalophoridae Reuss.

Zoaria ramöse ; hranches free, suh-cylindrical, with
rounded and more or less prominently exserted zooecial
apertures opening on all sides. (?) Without accessory or
interstitial pores of any kind. Ordovician to Recent,

Entalophora Lamx. {Glavisparsa d'Orb. ; Pergensia
Walford) (Fig. 444). Zooecial tubes disposed about an
imaginary axis, and with rounded, more or less prom-
inent apertures. Jurassic to Recent.

Spiropora Lamx. (Pustulopora and Gricopora Blain-
ville) (Fig. 445). Like the preceding, but apertures Plauen ,^SaxJny

Fig. 444.

Entalophora vir-
gula Hagenow.
Plänerkalk;

Fig. 445.

Spiropora vcr-
ticillata Goldf.
Upper Cretace-
ous ; Maestricht
(after Hagenow).

ORDER II

CYCLOSTOMATA

321

arranged in regulär, spiral or transverse linear series, and closely situated. Zooecial
tubes disposed about a definite central axis or axial tube. Jurassic to Kecent.

Diploclema Ulr, Similar to Entalophora, but witli branches spreading in the
same plane, slightly conipressed, and divided into two equal parts by a wavy mesial
lamina, Silurian.

Haplooßcia Gregory. Like Spiropora, but distal ends of zooccia are angular.
Jurassic and Cretaceous.

Mitoclema Ulrich. Ordovician. Clonopora Hall. Devonian. Peripora d'Orb.
Cretaceous.

Rhipidopora and Glinopora Marsson ; Siphoniotyphlus Lonsdale ; Clypeina Michelin ;
Umhrellina Roemer. Cretaceous and Tertiary.

Family 5. Fasciporidae d'Orbiguy (emend.).

Zooßcia tubulär^ opening in Clusters at the
(jrowing extremities^ and in linear or quincuncial
series on the sides of the lamelliform, or ohconical
zoaria. Äccessory pores wanting. Cretaceous.

Fascipora d'Orl». (Fasciporina d'Orb.). Zoaria
conipressed, sub-rainose to lanielliforni. Aper-
tures arranged quincuncially or somewliat ir-
regularly on both sides, and on the more or less
expanded growing extremities of the branches
and laniellae. The lanielliform species resemble
Diastopora, but are without a mesial lamina.

Semifascipora d'Orb. (Fig. 446). Zoaria cup
or funnel-shaped, with only the outer surface
poriferous, the inner covered by an epitheca.
Poriferous face thrown into vertical ridges
bearing the salient tubulär mouths of one or
more rows of zooecia. At the upper edge the ridges pass into large Clusters of apertures.

Conotuhigera and Serietuhigera d'Orb. Closely related to the preceding.

Fia. 446.

Semifasci'pora variabilis d'Orb. Cretaceous ;
France. Side view of zoarium, lO/j.

Fig. 447.

Fascirulijwra incrassata d'Orb. Upper
('retaceous ; Meudon, near Pari.s. Terminal
tVagnient, mt. size and enlarged (after
d'Orbigny).

Family 6. Fascigeridae d'Orbigny.

Zoarium composed of bundles of long, parallel
zooecia free for most of their length, with the aper-
tures in groups at the ends of the bundles.

Fasciculipora d'Orb. (Fig. 447). Zoarium of
long, simple or divided branches. Jurassic to
Tertiary.

Corymbopora Michelin. Like Fasciculipora
but sides of branches marked by numerous pores.
Cretaceous.

Apsendesia Lamx. Zooecial bundles arise from
a small cup-shaped disk. Jurassic and Cretaceous.

Discofascigera d'Orb. Cretaceous and Ter-
tiary.

Family 7. Theonoidae Busk.

Zoarium adnate or erect ; zooecia simple, short, open tubes with apertures confined to
crowded bands along raised ridges or on the edge of the fronds.

VOL. I Y

322 MOLLUSCOIDEA— BRYOZOA phylum v

Actino'pora d'Orb, (Pavotuhigera, etc., d'Orb.) (Figs. 448, 449). Zoariiiin an

Fig. 448.

Actinopora diadema (Goldfuss). Upper
Cretaceous ; Maestricht. A, Zoarium, ^|■^. B,
Profile of same. C, Upper surface, enlarged.

Fig. 449.

Actinopora disticha (Hag.).
Upper Cretaceous ; France.
Upper surface, 8/j.

Theonoa (?)i>aurantiuni M. Edw.
broken open in a vertical plane, Vi-
surface.

adnate disk with apertiires opeiiing on ridges radiating from a central depression.
Cretaceous to Recent.

MuUituhigera d'Orb. Zoarium Compound, tlie eleraents structurally resembling
confluent Actinoporae. Cretaceous.

llieonoa Lamx. {Tilesia Lanix. ; Phyllofrancia Marsson) (Fig. 450). Zoarium

massive or frondose ; surface
crossed by broad ridges bear-
ing the apertures. Jurassic
to Tertiary.

Patenaria, Locularia
Hamm ; Retenoa Gregory.
Cretaceous.

Family 8. Osculiporidae
Marsson.

Zoarium ramose, cylindri-
Crag; Sussex. A, Zoariurn cal or adnate : zooßcia Simple,

B, Enlarged portion of upper , ■ j. ji -n \i.

^^ long, m bundles with the
apertures opening in Clusters
on the surface or sides of the
zoarium..

Filifascigera d'Orb, (Fig.
451). Zoarium of simple or
])ranclied, creeping stolons.
Cretaceous and Tertiary.

Lopholepis Hagw. Zoar-
ium a broad incrusting
sheet. Cretaceous.

Cyrtopora Hagw. Semi-
cylindrical stems with pro-
minent Clusters of four or
more zooecial apertures open-
ing on all sides. Cretaceous
to Recent.

Osculipora d'Orb. (Fig.

452). Ramose, with Clusters

obverse face of the branches.

Fig. 451.

Filifascigera megaera
Lonsd. Upper Cretace-
ous ; Vincentown, N.J.
Specimen seen from above
and from the side, i2/j
(after Ulrich).

of zooecia opening
Cretaceous.

Fig. 45-2

Osculipora trun-
cata Hagw. Up-
per Cretaceous ;
Maestricht, Hol-
land. Fragment
i/i, and enlarged
(after Ulrich).

Fig. 4öb,

Truncatula repens
Hagw. Upper Cretace-
ous ; Maestricht. Lower
and Upper sides of zoa-
rium, enlarged (after
Hagenow).

alternately on the sides of the

ORDER II

CYCLOSTOMATA

323

Truncatula Hagw. (Fig. 453). Like Osculipora, biit convex sides exliibiting
iiuiuerons pores longitudinally arranged. Cretaceous.

Homoeosolen Loiisdale {Supercytis, Unicytis d'Orb.). Cretaceous.

Discocytis d'Orb. (Pelagia Mich., non Lam.) (Fig. 454). Zoarium cupuliform ;

Fig. 454.

Discocytis eucksü d'Orb. Upper Cretaceous'; France. Zoarium, 3/^, and three views of
same enlarged (after d'Orbigny).

iil)per surface concave with radiating ridges having apertures at their outer ends ;
ander surface poriferous. Cretaceous.

Gytis, Badiofascigera, Bicavea d'Orb. Cretaceous.

Family 9. Oeidae d'Orbigny

Zoaria ramose, bifoliate or uni-lamellate. Zocecia tubulär, sub-equal, their walls
at first, hut thickening gradually toward the periphery, where the cavity suddenly
dilates in such manner that the rounded or elliptical aperture lies at the hottom of an
hexagonal depression. Interstitial cells wanting. Cretaceous.

The systematic position of this family is highly problematical. It appears to have certain
affinities with the Trepostomata, but its removal to that vicinity is hardly feasible until a
thorough comparison of Paleozoic and Mesozoic Bryozoans shall have been made.

Semicea d'Orb. (Reptocea d'Orb. p.p.) ; Discocea Pergens.

Fig. 455.

Filiceavelata(E.agw.). Upper Cretaceous; Maestri cht, Holland. ^, Branch, Vi« -B, Surface

of sanie enlarged. C, Vertical section (after d'Orbigny).

Gea d'Orl). Zoaria forming flattened branches or broad lamellae, celhiliferous on
both sides.

Filicea d'Orb. {Laterocea d'Orb.) (Fig. 455). Zoaria erect, with sub-cylindrical
branches bearing apertures on all sides.

324 MOLLUSCOIDEA— BRYOZOA phylum v

Family 10. Eleidae d'Orbigny.

Zoaria ramose^ bifoliate or uni-lamellate. Zooecial tuhes dilating outvjardly, with
perforated loalls. Äpertures lateral and siih-terminal^ many of them closed hy ihin
calcareous films. Vicarious avicularia and seines scattered among the zooecia in some of
the genera. Cretaceous.

The members of this family difFer widely from the true Cyclostomata, and the presence of
avicularia indicates strong affinities with the Chilostomata, The Eleidae undoubtedly
represent connecting links between the Cyclostomata and Chilostomata. The simplest type
of Eleid structure is found in the Jurassic geniis Haploceeia Gregory, now placed in the
Entalophoridae, in which the aperture is subterminal, instead of terminal, and is constricted
laterally.

Reptelea d'Orb. Zoarium adnate, no avicularia.
Elea d'Orb. Zoarium erect, bifoliate ; no avicularia.

Meliceritites Roemer {Inversaria Hagenow ; Escharites Roemer). Cylindrical
branching stems ; avicularia present.

Foricula d'Orb. Like Meliceritites but has walls pierced by pores.
Semielea, Nodelea d'Orb. ; Reptoceritites Gregory.

Suborder B. CANCELLATA Gregory.

Zooßcia monomorphic with walls perforated hy cancelli, that is, hy roimded or elongate
pore-like cavities different from the usual interspaces or mesopores.

This suborder which is more convenient than natural, developed in early Cretaceous
times from certain specialised species of the Idmoneidae.

Family 11. Horneridae Hincks.

Zoarium erect and hranched ; zooecial äpertures only on the ohverse side and irregulär
or arranged in simple lines. Walls of zoarium traversed hy fine canals luhich appear
at the surface as minute pores. Cretaceous to Recent.

Hornera Lamx. ; Siphodictyum Lonsdale ; Hemicellaria d'Orb. ; Phormopora Marsson.

Family 12. Petaloporidae Gregory.

Bamose Cyclostomata with zooßcia opening on all sides of the branches and walls
perforated by numerous mural pore structures, somewhat resembling mesopores.

Petalopora Lonsdale {Gavea d'Orb.) ; Sparsicavea d'Orb. ; Gavaria Hagenow ;
Reptocavea d'Orb. Cretaceous and Tertiary.

Suborder C. DACTYLETHRATA Gregory.

Cyclostomata with long cylindrical zomcia separated hy dactylethra, that is, by short
aborted zocecia closed externally. No cancelli, mesopores or avicularia.

Family 13. Olausidae d'Orbigny.

Zoarium adnate or erect with the zocecia distributed uniformly and separated by
circles of shallow interstitial cells (dactylethrae) closed at the surface.

Clausa d'Orb. {Claviclausa d'Orb.). Zoarium erect and dendroid. Cretaceous and
Tertiary.

ORDER II

CYCLOSTOMATA

325

Gryptoglena Marsson. Zoariuin adnate, thick and unilaminar. Cretaceous.

Ditaxia Hagvv. {Polytaxia Hamm). Zoarium erect, lamellar and frondose.
Cretaceous and Tertiary.

Reticulipora d'Orb. {Retelea d'Orb,). Zoarium reticulated ; branches greatly
compressed laterally. Cretaceous to Recent.

BeptomiUticlausa, Multiclausa d'Orb. Cretaceous.

Terehellaria Lamx. Jurassic. Zonopora d'Orl). {Spiroclausa d'Orb.). Cretaceous.

Suborder D. CERIOPORINA Hagenow (emend.).

Von Hagenow in 1851 maintained the Cerioporina for Ceriopora and allied genera but

included a few other Cyclostomata. Hamm in 1881 recognised the same name, limiting the
group, hovvever, to the families Cerioporidae and Radioporidae.
The name is thns available for the post-Paleozoic Bryozoa

agreeing with the Trepostomata in having well - developed >JW3;.*^«.\a^^»f *J'i^*"r--"'1i

imniature and niatiire regions but differing in the amalgamated, *' "* * ' * * *•-*■-*
minutely porous structure of their walls.

Family 14. Radioporidae Gregory.

Zoaria simple or composite, discoid or massive, adhering
hy more or less of the under surface. Zooecial apertures on
the Upper surface, arranged in radial series separated hy
mesopores.

Discocavea d'Orb. (Fig. 456). Zoarium of simple
discoid groups, witli apertures in radial uniserial lines.
Cretaceous to Recent.

Lichenopora Defrance (Figs. 457, 458) {Tecticavea and
Badiocavea d'Orb.). Like Discocavea but apertures ar-
ranged in elliptical groups. Jurassic to Recent.

Fio. 456.

Discocavea pocillum d'Orb. Cre-
taceous ; France (after d'Orbigny).

Fio. 457.

Lichenopora (?) tubulifera (Roemer).
Oligocene ; Astrupp, Westphalia.
A, Zoarium, Vi- J^^ Cluster of
zoa'cial ai)ertures, enlarged.

Lichenopora stdlata (Goldf.). Pläner; Plauen, Saxony. A,
Zoarium, Vi- ß> Same, enlarged. C, Vertical section of specimen
from Greensand of Essen,

Stellocavea d'Orb. {Garinifer Hamm). Zoaria discoidal, the upper surface
exhibiting tlie salient edges of uumerous radially arranged plates, few of them

326

MOLLUSCOIDEA— BEYOZOA

PHYLUM V

reaching tlie centre. Zooecial tubes opening on tlie two opposite sides of plates.
Depressed interspaces occupied by interstitial cells. Cretaceous.

Radiopora d'Orb, Zoariuni massive witli zooecia arranged in radial series separated
by wide areas of mesopores. Cretaceous.

Actinotaxia Hamm ; Trochüiopora, Tholopora Gregory ; SemimuUicavea, Multi-
cavea, Pyricavea d'Orb. Cretaceous.

Family 15. Cerioporidae Busk.

Zoaria multiform^ encriisting, lamellar, hulbous, lohate, digitate or ramose, composed
of closely arranged thin-iualled tubes. The lauer sometimes completely separated hy
angular interstitial cells. Walls of neighhouring tubes tJioroughly amalgamated and
pierced by numerous pores. Trias to Recent.

Under this family are grouped the genera referred by Gregory to the Cerioporidae in
which mesopores are absent, the Heteroporidae with numerous mesopores, and the Zonatulidae
with mesopores grouped in spiral bands or rings. The internal and other features of these
three families are identical, and it is believed that the distribution of the mesopores is in
this case not of family importance. Gregory assigns these three families, as well as the
Radioporidae, to the Trepostomata, but, although it is triie that they resemble the earlier
Order in some features, the complete amalgamation and porous nature of their walls is
exactly the same as in typical Cyclostomata.

omulticava d'Orh. {Semicava d'Orb.; Reptocea Keeping) (Fig. 459). Zoarium

massive or branched, multi-
lamellar ; zooecia sliort, meso-
pores absent. Cretaceous.

Defranciopora Hamm.
Zoarium of superposed, discoid
colonies ; mesopores wanting.
Cretaceous.

Ceriopora Goldfuss (Oerio-
cava d'Orb.). Zoarium massive
or branched, witli long zooecia
and no mesopores. Trias to
Recent.

Heteropora BlainvlUe (Fig.
460). (Polytrema, Grescis,
Nodicrescis d'Orb.). Like Ceriopora but with numerous mesopores. Jurassic to
Recent.

Biflabellaria Pergens. Like Hetero-
pora but zoarium bifoliate. Cretaceous.

Zonatula Hamm. Zoarium dendroid
with spiral or annular constrictions
composed of mesopores. Cretaceous.

Plethopora Hagw. Like Zonatula but
zooecia open in knob-like elevations.
Cretaceous.

Ghilopora Haime. Jurassic. Multi-
zonopora d'Orb. ; Bivestis Hamm ; Spar-
sicytis Filliozat. Cretaceous.

Fio. 459.

ReptomuUicava spongites Goldf. Greensand ; Essen. A, Zoarixim, i/i
B, C, Upper and lower sides, enlarged.

Suborder E.

CERAMOPOROIDEA,

nom. nov.

wmWmWsm

Fig. 460.

This new suborder is proposed for the ^aiS^SfaTeÄS "Ä z'LaHu^T 'clveSi

PaleOZOic Bryozoans included in tlie two section. D, Upper siuface, enlarj^ed.

ORDER IT

CYCLOSTOMATA

327

families Ceiamopoi idae and Fistuliporidae, which were fornierly assigned to tlie
Trepostouiata and latterly to tlie Cyclostoniata. Tliey agree witli tlie Trepostoniata
in liaving well-delined ininiature and niature zones bnt their niinntely poious walls
of irregniarly laniinated tissiie, large mural communication pores and fmally, ooccia
typical of the Cyclostoniata seem to ally tliem more closely witli tlie latter order.
Tills suborder is possibly the Paleozoic representative of the Cerioporina.

Family 16. Oeramoporidae Ulrich.

Zoaria variable; maculae or Clusters of mesopores and of zocecia, larger than the
average, occur at regulär intervals. Zocecial apertures usually oblique, of sub-triangular,
ovate or polygonal form; lunarium present, appearing at the surface as a prominent
overarching hood, or as a slightly elevated portion of the margin, of crescentic form
with the ends projecting more or less into the aperture. Mesopores or interstitial cells

I Hi

Fio. 461.
a, Ceramopora spongiosa Bass. Tangential section, 20/j,
showing mural pores, 2oyj. d, Crepipora incra.tsata Bass.
(after Bassler).

h, c, Anolotichia rhombiai Bass. Vertical sections
Vertical section with ovicell-like structures, '^^/i

generally present, always irregulär, and usually without diaphragms. A few horizontal
diaphragms often present in the zocecial tubes. Walls minutely porous, composed of
intimately connected and irregularly laminated tissue. Large mural communication
pores sometimes present. Ordovician to Devonian.

This is one of the largest and most iinportant of the families of Paleozoic Bryozoans, and
is especially common in the Middle and Upper Ordovician. The

earliest forms resemble Berenicea and Apsendesia; while Ceramo- -^Si^^SÄi^^Sli^l^ *
porella, Chiloporella, and especially Favositella, may be regarded fWmamiWnl^im'i
with reasonable confidence as the progenitors of the Fistuliporidae.
At any rate the connection between the two families is so intimate
as to forbid any wide Separation.

Ceramopora Hall (Fig. 461, a). Discoidal, free, lamellate,
massive or parasitic. When free, under surface with one or
more layers of sniall irregulär cells. Zooecia opening on the
Upper surface, large, irregulär, oblique, imbricating, and radially
arranged about the depressed centre. Mesopores irregulär, short,
numerous. Large communication pores in walls of both zooecia
and mesopores. Ordovician to Devonian.

Ceramoporella Ulr. (Fig. 462). Zoaria encrusting. Zocecial
tubes short, walls thin, apertures more or less oblique, hooded,
commonly of oval sliape. Mesopores abundant, often completely isolating the zocecia,
Ordovician and Silurian.

Fl(i. 4C2.
Ceramoporella dislincta
Ulrich. Lowor Trenton,
Minnesota. Surface of para-
sitic expansion, i'-'/i (after
Ulrich).

328

MOLLUSCOIDEA— BRYOZOA

PHYLÜM V

Goeloclema Ulr. (Fig. 463). Hollow branclies, lined internally with a striated
epitheca. Zoojcia as in Geramoporella, biit witli thicker walls. Ordovician and
Silurian.

Grejpi'pora Ulr. (Figs. 461, d; 464). Mesopores almost entirely restricted to tlie

FiC!. 463.

Goeloclema tren-
tonensis Ulr,
Trentou ; Minne-
sota. Two frag-
ments, ^/s, and
one 6/j.

Fig. 464.

Crepipora perampla Ulrich. Lower Trenton ; Minnesota. A, Vertical
section. B, Transverse section, 7/j. c, Same, i'i/x, showing lunaria. D, Sur-
face of C..-simulans Ulrich, 9/i (after Ulrich).

maculae, wliich are distributed over the surface as niinutely poroiis elevations or
depressions. Apertiires very slightly oblique, angiilar or sub-pyriform. Liinarium
well-defined in perfect specimens, best shown in tangential sections. Ovicell-like
bodies known in one species. Ordovician and Silurian. *

Anolotichia Ulr. (Figs. 461, &, c; 465). Zoaria large, ramose or digitale. Lunarium

AnoloticMaimpolita Ulr. Black River Shales ; Minnesota. A, Surface,
6/i. B, Vertical section, 6/j. c, Tangential section, 12/^^ showing tiibes
of lunarium. IJ, Tangential section of A. jmiderom Ulr., from the
Richmond formation at Wilmington, Hl., showing numerous lunarial
tubes (after Ulrich).

sligbtly elevated at tlie surface, traversed internally l:)y
two to six minute, vertical, closely tabulated tubes.
Mural communication j)ores present. Ordovician and
Silurian.

Ceramophylla Ulr. (Fig. 466). Like Ceranioporella
but zoarium is bifoliate, Ordovician.

Favositella Ether. and Foord {Bythotrypa Ulr.) (Fig.
open at the surface, forming interiorly a very loose vesicular tissue.
by communication pores. Ordovician and Silurian.

Ghiloporella Ulr. Ordovician.

Scenellopora Ulr. Zoaria simple, pedunculate ; under surface witli an epitheca
the Upper slightly concave and celluliferous. Zocccia with slightly ol)lique, sub-
circular apertures, radially arranged on the summits of low ridges. Ordovician.

Fig. 466.

Ceramophylla frondosa Ulr. Black
River Shales; Minnesota. A, Zoa-
rium, 2/3. B^ Surface of same, ß/j.
6', Two zowcia of a tangential sec-
tion, 12/1. D, Right half of a verti-
cal section, 12/j (after Ulrich).

467).

Mesopores numerous,
Walls pierced

ORDER II

CYCLOSTOMATA

329

Spatürpora Ulr. (Fig. 468).
Apertures irregulär ;
luiiariuni scarcely per-
ceptible. Mesoporen,
wlieii present, cliiefly
in iiiaciilae. Inter-
spaces often witli large
bliint spines (? acan-
thopores). Ordovician
and Silurian.

Family 17. Pistuli-
poridae Ulricli.

Zoaria massive,
laminar or ramose, the
siirface exhihiting at regulär intervals
" maculae " or " monticules " com^
of Clusters of vesicles and of zooßcia
slightly larger than the average. Luna-
rium more or less developed. Zooecial
tubes never angular, thin-ivalled, and
ivith horizontal diaphragrifis ; apertures
closed by perforated operculum. Inter-
spaces occupied by vesicular tissue. Gell
walls minutely porous. Ordovician to
Perinian ; cliniax in Devonian.

Zoaria Ibrniing thin crusts, especially on Orthoceras.

Fig. 468.

Spatiopora aspera Ulr. Cincinnati Group ; Hamilton, O.
A, Surface. B, Vertical section. C, Tangential section ; all
i-«/i (after Ulrich).

Waagen, Wentzel and otliers have
referred certain merabers of tbis family to the Corals, but tbe reasons for doing so rest
obviously upon insufiicient Observation. Not only are the members of this family
derived from the Ceramoporidae, as noted above, which are undoubted Bryozoans,
but some of them possess ovicells, tlius" abundantly proving their Bryozoan nature.

Fistulipora M'Coy (Didymopora Ulr. ; Dybowskiella Waag. and W.) (Fig. 469).
Zoaria massive, lamellate, more
rarely ramose, parasitic or free ;
under surface with wrinkled epi-
theca. Zooecia sub-radially arranged
about the surface maculae ; aper-
tures ovoid, sub-triangular or
pyriform, according to the degree
in which the lunarium is developed ;
interiorly with thin walls, and a

small number of com plete horizontal . ,. ,. .j, . ,

^ Fistuhpora astnca Ulrich,

diapliragms. Interspaces smooth or Devonian (Hamilton Group);

granulär, occupied internally by So?" »/i?' ^''''^' '^^""'"''^^

one or more series of vesicles. Rare

in the Ordovician. Common from Silmian to Lower Car-

boniferous less frequent in Goal Measures and Permian.

Cyclotrypa Ulr. (Fig. 470). Like Fistulipora, but the
lunarium obsolete, and zocecial tubes circular in transversa
section. Devonian .

Eridopora Ulr. (Pileotrypa Hall). Zoaria thin, parasitic.
Zooecia with oblique, sub-triangular or ovoid apertures.
Lunarium very prominent. Silurian to Goal Measures.

Fit;. 470.
Cyclotrypa communis Ul-
rich. Hamilton ; New Buf-
falo, Iowa. Vertical and
tangential sections, i*/i
(alter Ulrich).

330

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

Ghilotrypa Ulr. Zoaria small, ramose, witli a narrow, irregularly contracting and
expanding axial tnbe. Silurian to Lower Carboniferous.

2 Ulr. (Fig. 471). Zoaria bifoliate. Oblique apertures all directed

Meekopora eximia Ulr.
from the side and edge,
ovicell, 14/j (after Ulrich).

Fio. 471.

ehester Group ; Monroe Co.
=^4- B, Surface of same, 7/j.

, 111. A, Specimen
C, Portion showinjj;

Strotopora foveolata Ulr.
Keoknk Group ; Bentons-
port, Iowa. Part of ex-
pansion, 3/^, and surläce of
same, 7/^, showing zocecial
apertures and broken ovi-
cells (after Ulrich).

toward the distal margin of the zoarium or branch. Liinarium moderate or obsolete ;
diaphragms numerous and often recurved. Ovicell rather large, showing at the
surface as a convex space with a small apical opening,
Silurian to Goal Measures.

Strotopora Vir. (Fig. 4.1 2). Zoaria ramose. Large, abruptly
spreading cells (regarded as broken ovicells), distributed
among the zooecia on ordinary specimens; when perfectly jDre-
served they appear as strongly convex elevations with a small
opening on one side. Devonian and Lower Carboniferous.

Lichenotrypa Ulr. First stages like Fistulipora, after
which large spines and irregulär thin walls are thrown up
about the apertures. Devonian.

Biiskopora Ulr. (Odontotrypa, Glossotrypa Hall) (Fig.
473). Like Fistulipora, but lunarium remarkably de-
veloped, projecting ae a strong, bidenticulate process nearly
half across the aperture. Devonian.

Pinacotrypa Ulr. ; (?) Botryllopora Nich. ; Selenopora
and Favicella Hall. Devonian ; Hexagonella W. and W.
Devonian and Carboniferous.

Fig. 473.

Buskopora dentata Ulr.
Devonian (Onondaga Group) ;
Falls of the Ohio. Portions
of surface, 7/ and 14/, (after
Ulrich).

Order 3. TREPOSTOMATA Ulrich. ^

Zocecia directly superimposed upon one another so as to form long tubes intersected
hy straight or curved partitions (diaphragms and cystiphragms) representing the Covers

^ Two regions of the zocecial tubes are distinguishable, an axial or " immature " region, in
which the diaphragms are remote, the walls thin, and the tubes prismatic through contact ; and a
peripheral or "mature" region, in which the tubes bend outward, the walls are thickened and
otherwise modified, the transverse partitions rnore abundant, and interzooecial elements (acanthopores,
raesopores, or mere strengtheuing tissue) are developed.

Waagen and Wentzel aud others erroneously assert that the raesopores and acanthopores,
occurring so commonly in the Trepostomata, are young zocecia or " corallites. " With very few
exceptions, these really very different elements are not developed until the zoarium has reached the
niature stage, in which new zocecia cease to be given off. The origiu of raesopores {i.e. all cells
occupying interzocecial spaces, whether invested with separate walls or not) is due to the same
necessity which leads to the distal thickening of tlie zocecial tubes, namely, that of filling up space
occasioned by the growth of tubes at the periphery, and by the change in the direction of the tubes,

Sonic of the tubes provisionally included under the terra raesopores, like some of the acantho-

I^y ORDER III

TREPOSTOMATA

331

and floors of successive layers. Zooecial Covers with a small, usually sub-central orifice.
Monticules or maculae (containing cells differing from the average in size, or in hxiving
their apertures elevoAed) regiilarly distributed over the snrface.

The Trepostomata include the greater j^ortion of the " Monticuliporoids " which
by some writers, particularly Milne Edwards and Haime, were regarded as Anthozoans.
Nicholson assigned them to the Octocoralla becaiise the corallites apparently agreed
with Heliolites in their microscopic structure, and in addition were snpposed to have
iniperforate walls and to increase by intermural gemmation or by fission. Ulrich
has insisted upon the bryozoan natiire of these organisms, and has published niany
facts militating against Nicholson's views. Bassler has added a number of points
confirmatory of their bryozoan affinities, and recently Cumings has worked out the
primitive budding stages of at least six characteristic genera. He finds that the
budding plan of Prasopora and allied genera is precisely the same as in typical recent
Bryozoa, namely that it consists of (1) a protoecium, or minute circular disk ; (2) the
ancestrula^ a tubulär zooGcium of the type seen in the Cyclostomata ; and (3) several
primary buds arising from and adjacent to the ancestrula. These primitive structures
are separated from the rest of the colony by a considerable thickening of their
posterior walls. In the Corals, development from the planula is direct, the moment
it becomes sedentary and therefore the presence of the protcecium alone is practically
conclusive as to the systematic position of the Trepostomata with the Bryozoa.

Suborder A. AMALGAMATA Ulrich and Bassler.

Trepostomata in which the houndaries of adjacent zooecia are ohscured by the more or
less complete amalgamation of their walls.

Family 1. Monticuliporidae Nicholson (emend, Ulrich).

Zoaria multiform. Zooecial apertures polygonal, rounded or irregularly petaloid.
Mesopores occasionally wanting, in other cases numerous, angular and crossed by
crowded diaphragms. Acanthopores A B

always present in the mature region.
Ordovician to Devonian.

The incomplete, curved, transverse
partitions, termed cystiphragms by
Ulrich, are the principal peculiarity of
this family. It is possible that tliey
represent ovicells, but their significance
can only be conjeetured.

Monticulipora d'Orb. (Fig. 474).
Zoaria incrusting to massive. Zooecia

Fig. 474.

T 1 -^1 • ^ 1 1 MoniicuXipwaarhoreamT. Trenton ; Minnesota. Vertical

polygonal, with mmutely granulöse ^^^ ^n^ tangential (ß) sections, i-«/i (after Ulrich).

walls. Cystiphragms lining both

mature and immature regions. Mesopores very few or absent. Acanthopores small,

granulöse, more or less numerous. Ordovician and Silurian.

Orbignyella U. and B. Ordovician to Devonian.

Ätactoporella Ulr. (Fig. 475). Zoaria generally encrusting. Zooecia with veiy

pores, were doubtless occupied by specially niodified polypides, which probably find tlieir
homologues in the avicularia and vibracula of recent Chilostomata. But niany of the mesopores
wliich are not invested by separate walls are to be regarded as mere iuterspaces between the
zooecial tubes, and the purpose of their transverse partitions is to support the walls of the latter, as
well as to assist intercomniunication by nieans of the zoarial parenchynial cord.

332

MOLLUSCOIDEA— BRYOZOA

PHYLÜM V

thin inflected walk, the apertiires irregularly petaloid. Mesopores niimerous, frequently
isolating the zooecia, largely filled by a secondary deposit. Acanthopores small and
very niimerous. Ordovician and Silurian.

c

Fio. 475.

Atactaporella typicalis Ulr. Black River Group ; Minnesota. Surface (.1), tangential (11),
and vertical (C) sections, ^% (after Ulrich).

Peronopora Nicli.

A

Similar to the preceding but zoaria bifoliate, and zoa3cial walls
B c thicker, not inflected by the acan-

thopores, and more ring-like in
transverse section. Ordovician
and Silurian.

Homotrypa Ulr. (Figs. 476,

477). Generally raniose, some-

times frondescent. Zooecial tiibes

with very thin and finely crenii-

lated walls, and remote diaphragms

in the axial region. Cystiphragms,

isolated or in series, developed in

peripheral region only. Apertures

polygonal or sub - circiilar. Mesopores

iisually few and restricted to the maciilae.

Acanthopores generally present. Ordovician

and Silurian.

Homotrypella Ulr. Like Homotrypa but
mesopores niimerous and cystiphragms
usually confined to the early part of the
mature region. Ordovician and Silurian.
Prasopora Nich. and Eth. (Fig. 478).
Zoariiim massive, free. Zooecial tiibes
prismatic or cylindrical, thin - walled,

A B

Structure of walls and parenchymal cord in {A), Homotrypa
callosa Ulr., 35/j ; (B), Stictoporella frondifera Ulr., »ö/^ ; and (C),
Retepora columnifera Busk. Recent, 60/^.

Fig. 477.

Homotrypa subramosa Ulr. Black River ; Minnesota.
A, Surface. ' B, Tangential section. C, Vertical sec-
tion, 14/j. X», H. sejxtrata Ulr. Tangential section,
X 17.

Fx(i. 478.

Prasopora simulatrix Ulr. Trenton ; Ken-
tucky. A, Transverse, and B, Vertical section,
i4/i (after Ulrich).

ORDP]R III

TREPOSTOMATA

333

separated froni one aiiother by smaller angiüar mesopores, and contaiiiing cystiphgrams.
Acantliopores usiially pre-
sent. Ordovician and
Silurian.

Mesotnjpa Ulr. (Fig.
479). Äspidopora Ulricli.
Ordovician and Silurian.

Family 2. Heterotry-
pidae Ulrich.

Zoaria frondescent,
ramose, massive or jjara-
sitic. Zocecia polygonal,
lüith moderately thin lualls.
Äcanthoporespresent, some-
times of large size. Diaphragma numerous, horizontal. Cystiphragms ivanting. Ordo-
vician to Devonian.

Dekayella Ulr, (Fig. 480). Zoarium always frondescent, mesopores numerous,

Fig. 479.

Mesotrypa infida Ulr. Black River Group ; Minnesota. A, Transverse
section. B, C, Vertical sections, i4/j (after Ulrich).

! I T / > '■ ■''

!/ 1/ / ,■'/

Fig. 480.

Dehiyella ohscura (Ulr.). Ordovician ; Cincinnati, Ohio.
Tangential and vertical sections, i'i/i (after Ulrich).

Fig. 481.

Dekayia aspera Edw.
and H. Ordovician ; Cin-
cinnati, Ohio. Tangential
section, ^■^/i.

and acantliopores of two sizes, the smaller ones tlie more abundant, and present
only in the peripheral region. Ordovician and Silurian.

Heterotrypa Nich. Zoarium frondescent, and acantliopores all of uniform size.
Ordovician and Silurian.

Dekayia E. and H, (Fig. 481). Distinguished from Heterotrypa by the absence of

Fig. 482.

Stigmatella foordi (Nich.). Ordovician ; Es-
thonia. A, Tangential section, i^i. B, Vertical
section, 22/j (after Bassler).

K^'i'Kj'^'pi'^^

•^/?iS^lÄÄ

Fig. 4S3.

Ätactopora maculata Ulr. Ordovician ; Cincinnati,
Ohio. Transverse and vertical sections, n/i, showing
greater part of a solid macula (after Ulrich).

the smaller set of acanthopores, and lesser number of mesopores and diaphragms.
Ordovician.

Petigopora Ulrich. Stigmatella Ulr. and B, (Fig. 482, ^, ^). Ordovician and
Silurian.

334

MOLLUSCOIDEA— BRYOZOA

PHYLÜM V

Ätactopora Ulr. (Fig. 483). Zoaria thiii, growing on Orthoceras. Zococial apertures
iiideiited or floriform, accordiiig to position of the veiy niimerous acanthopores. Ratber
large, solid elevations, composed of abortive cells, and completely filled by calcareoiis
deposit, stud tbe surface at regulär iiitervals. Ordovician and Silurian.

Leptotrypa Ulr. Ordovician. Gyphotrypa U. and B. Ordovician to Devonian.

Family 3. Oonstellariidae Ulrich.

Zoaria rawose, frondescent, laminar or encrusting. Zooecial tuhes thin-walled and
prismatic in the axial region, thicker and suh-cylindrical in the peripheral ; apertures
rounded, the peristomes slightly elevated. Meso'pores angular, ahundant, generally
isolating the ^ocecia, at intervals gathered into usually stellate Clusters ; closed at the
surface, the closure with numerous perforations. True acanthopores wanting, hut small
hollow spines or granules often very ahundant. Diaphragms straight and complete in
both sets of tuhes. Ordovician and Silurian.

Gonstellaria Dana (Fig. 484). Zoaria growing erect from

basal

Fig. 484.

Gonstellaria florida Vir. Cincinnati, Ohio. J, Vertical section. i>, Tangential, showing aged condition.
C, Average tangential section, all 14/^, j)^ Branch of the natural size (after Ulrich).

expansion. Surface with depressed stellate maculae, the Spaces between the rays
elevated and occupied by two or three short rows or Clusters of closely approximated
zooecial apertures. Mesopores aggregated in the maculae, internally with gradually
crowding diaphragms. Ordovician.

Stellipora Hall (non Hagw. nee Haime). Differs from the above in its encrusting
or lamellate habit, and in having only mesopores in interspaces between the raised
zooecial Clusters. Ordovician.

Nicholsonella Ulr. (Fig. 485, A-G). Laminar expansions, sometimes giving off

Fio. 485.
Nicholsonella pulchra Ulr. Stones River; Tennessee. A, Surface, 7/j. ß, Vertical section, i4/^. C, Tan-
gential sections at different levels, K/i (after Ulrich). D, Dianulites fastigiatus Bichw. Silurian ; Baltic
Provinces. Tangential section, 14/^ (after Bassler).

flattened, intertwining branches or fronds. Interzooecial spaces wide, and with
numerous mesopores, which have thicker and more numerous diaphragms than the

ORDER III

TBEPOSTOMATA

335

zooecial tul)es ; tlie spaces becoiiie filled up with ag(', l^y a calcareous dei)osit, rendfring
walls of inesopores unrecognisable. Ordovician.

Dianulites Eicliwald (Fig. 485, D). Zoaria massive ; zooccia and mesopores pris-
matic, tliin walled ; walls and spines with miniite granulöse stnictures as in
Nicholsonella. Ordovician and Silurian.

Tdiotrypa Ulr. Silurian ; North America.

Family 4. Batostomellidae Ulrich. ^

Zoaria usually ramose, occasionally suh-lobate, massive^ laminar or paradtic, often
consisting of superimposed layers. Zocecia tvith thick walls in the mature region^ usually
appearing here as fused. Diaphragms horizontal, those in peripheral region with central
Perforation. Acanthopores and mesopores usually present; the latter small, often
intermittent. Ordovician to Permian. ,

The amalgamate nature of the zooecial walls is most marked in this family.

Bythopora Miller and Dyer. Small branching stems. Apertures oblique,
attenuate above. Interspaces canaliculate, with an occasional mesopore or none.
Ordovician and Silurian.

Gallotrypa Hall. Silurian and Devonian. Eridotrypa Ulrich. Ordovician to
Devonian.

Batostomella Ulr. {Geinitzella W. and W. ; Trematella Hall) (Fig. 486).

Slender

Fi(i, 486,

Batostomella splnulusa Mir. ehester Group ; Kentucky. A, B, Vertical sections, one with and the other
without diaphragms, i'i/i. C, Tangential section, l^/j. j)^ Surface, i^/^. On either side of C are branches of the
natural size (after Ulrich).

branches, without monticules. Apertures small, circular or oval. Interspaces
rounded or canaliculate, spinulose, the acanthopores small and usually very numerous.
Mesopores small, sub-circular. Diaphragms few. Silurian to Permian.

Stenopora Lonsd. (Fig. 487). Zoaria ramose, sub-lobate, massive, laminar or
parasitic. Zooecial walls periodically thickened in the mature region. Large
acanthopores at many of the
angles between the zooecia.
Mesopores never very numerous,
irreglüarly distributed. Dia-
phragms sometimes very scarce,
but in most American species
abundant in the peripheral
region, and with a large central
Perforation. Lower Carboni-
ferous to Permian,

Anisotrypa Ulr, Divisional
line between adjoining tubes
niorP «bnmlv rlpfiiipd and Ste.nopora ame^^ana V\r. Keokiik Group ; Illinois. Vertical (X)
more snarply aennea, ana ^^^ tangential (B) sections showing moniliform walls and perforated
periodic SWellingS of the walls diaphragms, l-»/^ (after Ulrich),

Fi.i. 487.

336

MOLLUSOOIDEA— BRYOZOA

PHYLUM V

mucli less distinct than in Stenopora. Acaiitliopores and mesopores absent ; perforated
diaphragms numerous. Lower Carboniferous.

Lioclema Ulr. (Fig. 488). Ordovician to Goal Measures. Lioclemella Foerste.
Ordovician and Silurian. Orbipora Eichwald (Fig. 489, a, b). Ordovician.

Fig. 488.

Lioclema foliata Ulr. Keokuk Group ; Illinois. A, Vertical section, 2i/j. ß^ Tangential section, '•^o/i.
C, Portion of wall and acanthopore, 38/^. D, Interstitial cell,|2^Vl (alter Ulrich).

Fig. 489.

a, Orhipora distincta Eichw. Section, 14/^. i,^ o. acanthopora Bass. i-^/i. c, cl, Edhoniopora communis Bass.
Ordovician ; Baltic Provinces. 5/j (alter Bassler).

Esthoniopora- Bassler (Fig. 489, c, d). Zoariiim massive ; zooccia with senii-
diaphragms ; no mesopores or acanthopores. Ordovician ; Esthonia.

Suborder B. INTEGRATA Ulrich and Bassler.

Trepostomata in which the boundaries of adjoining zooßcia are sharphj defined by a

Family 5. Amplexoporidae Ulrich.

Zoaria ramose, discoidal, massive or bifoliate. Zocßcial tubes comjoaratively simple,
prismatic, with a well-marked divisional line between adjoining tubes. Mesopores
practically absent, but small abortive cells sometimes found among the large zomcia
forming the monticules. Acanthopores generally abundant, sometimes wanting. Ordovician
to Devonian.

Amplexopora Ulr. Zoaria ramose. Acanthopores always present, varying m size
and number. Diaphragms complete, horizontal. Ordovician and Silurian.

Monotrypella Ulr. Like the above, but without acanthopores. Ordovician to
Devonian.

lORDER III

TREPOSTOMATA

337

Rhombotrypa U. aiid B. Siluriaii. Petalotrypa and IHscoirypa Ulr. Ordovician
to Devon iaii.

Family 6. Halloporidae Bassler {Galloporidae Ulricli).

Zoaria ramose, suh-frondescent, massive or discoidal. Zooßcial apertures generally
sub-circular and separated more or less completely hy angular mesopores ; at other times
polygonal, when fhe mesopores are few or wanting. Zocecial tuhes thin-walled, attaining
their füll size sloivly. Acanthopores wanting. Ordovician to Devonian.

In this faniily the proximal ends of thetubes arising in the axial or "immature" region
liave the character of mesopores. The diaphragms are rather closely arranged in the taperiiig

Fig. 49U.

HaZlopora ramosa (E. and H.). Ordovician (Cincinnati Group); Cincinnati, Ohio. A, Zoarium, natural
size. B, Surface slightly magnified. C, Tangential .section, parallel to external surface, 20/j. j)^ Vertical
section, 20/^. ((^,< and D alter Nicholson.)

proximal end, then few or wanting for a considerable distance, and finally become crowded in
the peripheral or mature region.

Hallopora Bassler {Gallopora Hall preoccupied) (Figs. 490, 491). Zoaria usually
ramose and biisliy, tlie branclies often anastomosing. Apertures closed in tlie perfect
State by perforated, often ornainented, Covers, which are left behind, as growtli proceeds,

Fi(i. 491.
A, B, Hallopora eleqantula (KaU). Niagara ; Indiana. Vertical and tangential seetions, "/j. C, D, H. imdti-
tabulata Ulr. Lower Trenton ; Minnesota. C, Vertical section, v/i. D, Surface having zooecia open (7/i), and
preserving zoo?cial covers (i-*/i).

to form floors (diaphragms) of succeeding layers. Zocecial tubes of two sizes in the axial
region, the larger ones with six to eight sides, the smaller set four- or five-sided.
Ordovician to Devonian.

Halloporina, nom. nov. (proposed for Calloporina Ulrich and Bassler, preoccupied
by Neviani in 1895). Like Hallopora but diaphragms wanting and walls strongly
crenulated. Ordovician.

Calloporella Ulr. Silurian ; North America.
VOL. I Z

338

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

Family 7. Trematoporidae Ulrich.

Zoaria ramose or encrusting. Zocecial tuhes irregulär in the axial region, their
proximal ends with diaphragms, and usually constricted where the latter occur ; walls

Fio. 492.

Tangential sections of Batostoma from the Black River Group of Minnesota, A, B. fcrtile Ulr., H/j.
B, Same, var. circulare, l-J/j. C, B. tvinchelli var. spinulosum Ulr., 38/^ (after Ulrich).

thickened in the mature region, lines of contact distinct. Mesopores generally ahundant,
usually of large size, their apertures closed. Äcanthopores more or less ahundant.

This faraily is principally distinguislied from the Halloporidae by the presence of äcantho-
pores and closed mesopores. The Trematoporidae, moreover, have a general looseness and
obscurity of structure quite unlike that of any otlier Trepostomata.

Batostoma

492).

Branches. irregulär, springing from a large basal
expansion. Zooocial walls of varying
thickness, in contact only at limited
points, and of two sizes in the axial
region. Diaphragms strong, horizon-
tal, complete. Species numerous and
mostly very abundant. Ordovician
and Silurian.

Hemiphragma Ulr. (Fig. 493).
but diaphragms in
tubes incomplete.
Ordovician and Silurian.

Diplotrypa Nich., emend. Ulr.

Hemiphragma irrasum mr. Lower Trenton ; Minnesota. /Tri:„ ACkA\ ^r^^r.\n w,or,.,;,.^ ^^ ^^.,n,r

A, Vertical section, 1^. B, Tangential, H/^ (after Ulrich). (^ ^^' ^^V' /f^Oaria massive, generally

free. Zooccial tubes comparatively

AV* ^^~^^^ ^.^«Ä^W'" ' ■'-'ik^ Batostoma, bi
W^ kit^'M"\C^^ peripheral part of

Fig. 493.

Fig. 494.

Diplotrypa westoni Ulr. Richmond Group ; Manitoba.
Tangential and vertical sections, i4/j (after Ulrich).

Fig. 495.

Monotrypa magna Ulr. Lower Trenton ; Illinois,
Transverse and ^'ertical sections, 7/j (after Ulrich).

ORDER IV CRYPTOSTOMATA 339

large, prismatic, witli horizontal diapliragms. Mesoporcs few to niiineroiis, varying
in size. Ordovician and Siliirian.

Monotrypa Nicli. {Phjchonema Hall) (Fig. 495). Distin-
gaislied from tlie preceding by the absence of mesopores and
fewer diapliragms. Ordovician to Devonian.

Anaphragma U. and B. Ordovician and Silurian. Ditto-
pora Dybowski (Fig. 496). Ordovician.

Trematopora Hall (emend. Ulr.) ; Stromatotrypa Ulr. Or-
dovician and Silurian. Fig. 49(5.

Dittopora colliculata

^ , . ^.^^....^«™^^,^^.. _ . . Eichw. Ordovician ; Es-

Order 4. CRYPTOSTOMATA Vine. thonia. Tangential sections

with two sets of acantho-

Primitive zooßcium short^ pyriform to oblong, quadrate or P^""*^^' /i ^^ ^^^' *^^ ^^^'

hexagonal, sometimes tubulär, the aperture anterior. In the

mature colony the aperture is concealed, occurring at the hottom of a tubulär shaft

(" Vestibüle "), which may be intersected by straight diaphragms or hemisepta, owing

to the direct super-imposition of layers of polypides. Vestibulär shaft surrounded by

vesicular tissue, or by a solid calcareous deposit ; the external orifice rounded. Mar-

supia and avicularia wanting.

The Cryptostomata diifer from the Trepostomata chiefly in that the " immature "
region (primitive cell) is usually much sliorter and the passage to the mature region
more abrupt.

Some of the Cryptostomata are ramose, and have long, thin-walled prismatic
tubes in the axial region, with or without diaphragms, precisely as in the ramose
Trepostomata and Cyclostomata ; but they are distinguished from the latter by the
presence of hemisepta, similar to those occurring in the vestibule of E schar opora and
Phaenopora, two of the most typical genera of the Cryptostomata. That these axial
tubes are not of primary importance is shown by individuals of such genera as
Goeloconus, Bhombopora, etc., in which a second layer of zooecia has grown over the
first. This is a rare condition, and is probably to be attributed to an accidental
Interruption of growth. But, where observable, it is to be noticed that the inner
extremities of the zocecia of the second layer are not drawn out into tubes like
those of the primary set, but are short, and in all essential respects like those of
E schar opora.^

The Cryptostomata are probably nothing more than Paleozoic Cheilostomata,
dlffering, however, from the typical members of the latter, (1) in having neither
marsupia nor avicularia ; (2) in the much greater deposit of calcareous matter upon
the front of the zooecia, thns producing the vestibule ; (3) in that successive layers of
polypides are often developed, one directly over the other, in a continuous tube ; and
(4) in that whenever a zoarium attains an uninterrupted width of more than 8 mm.,
it exhibits Clusters of cells differing more or less, either in size or elevation, from the
average zooecia. The last two distinctions are suggestive of the Trepostomata ; and
the presence of a vestibule reminds us of certain Mesozoic and Recent Cheilostomata,
which have the same tubulär Prolongation of the aperture. Thus, the Recent
Adeonella atlantica Busk, has not only a vestibule, but hemisepta as weil Hemisepta
are never found in the Cyclostomata and Trepostomata, but are a very common
feature of the Cryptostomata. They occur at the bottom of the vestibule, and doubt-
less served as supports for the movable operculum.

^ The almost universal practice has been to accept the presence of tubulär zooecia as fully
demonstrating the Cyclostoniatous affinities of the species producing tliem. luvestigations, how-
ever, show that the mere form of the zofficium cannot be relied upon as a subordinal cliai-acter any
more than is the presence of tabulae in a tubulär organism a certain indication of an Anthozoan.

340

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

Family 1. Phylloporinidae Ulrich.

Zoaria branching, celluliferous on one side only, the other side striated ; hranches
free or anastomosing. Zocßcia more or less tubulär, often with diaphragms. Hemisepfä
wanting.' Ordovician to Goal Measures.

a, h, Chasinatopora suhlaxa (Ulr.). ö/j.

Fio, 497.
(', d, Traiisvers'e aiid longitudiiial sections, i^/^ (after Ulrich).

Ghasmatopora Eicliwald {Phylloporina Ulr.) (Fig. 497). Brauches irregularly
anastomosing, with two to eight ranges of zooecia on the celluliferous side. Tabulated
interstitial spaces generally present, closed at the surface. Ordovician and Silurian.

Pseudohornera Roemer {Drymotrypa Ulr.). Ordovician to Devonian. Chaino-
dictyon Foerste. Goal Measures.

Family 2. Fenestellidae King.

Zoaria forming reticulate expansions, celluliferous on one side only. TJiey are com-
posed of rigid branches united by regulär non-poriferous bars (dissepiments) ; or may be
sinuous and anastomose at regulär intervals ; or may remain free. Zocecia enclosed in
a calcareous crust, which is minutely porous, especially on the non-celluliferous side.
Primitive porlions of zocecia oblong, quadrate or hexagonal in outline. Superior hemi-
septum usually present, the inferior one less frequently. Primary orifice anterior, semi-
elliptical, truncated behind. External apertures rounded, with peristome, and covered,
when perfect, by centrally perforated closures. Silurian to Permian.

The zoarial characters of the Fenestellidae are extremely constaiit, and are of the greatest
systematic importance. The zooecial cavity in this faniily is very siniilar to that of the
Ptilodictyonidae and Rhinidictyonidae ; and the same is also true of both tlie primary and
external orifices.

Fic. 498.

Fenestrlld /r///u;-//(/s Scliloth. Permian Dolomite ; Pcissniick, Tlinrinj;ia. .1, Fra-inciiL of/oarium, natural size.

Ji, Portion Ol' external surface, sH^'htly enlarged. C, Magnilied iK)rtion of iiiterioi' (teüuliferous surface.

ORDER IV

CRYPTOSTOMATA

341

Fenestella Lonsd. (Fenestrella d'Orb. ; Actinostoma Youiig) (Fig. 498). Zoaria
Üabellate or fimnel-shaped, poriferous on the inner side. Branches connected at
regulär intervals by dissepiments. Zooecia in two rows, separated by a piain or
tuberculose median keel. Silurian to Permian.

Semicoscinium Front {Garinopora Nich. ; Cryptopora ^ich.; Gycloporina Simpson).
(Fig. 499, e). Zoaria fimnel-shaped, poriferous on the outer side. Dissepiments
Wide, very short, the branches appearing to anastomose on the non-poriferous face,
vvhere the fenestrules are sub-rhomboidal or rounded. ZocEcia in two ranges, median
keel very high and expanded at the summit. Silurian and Devonian.

Fenestrapora Hall. Like the preceding, except that the reverse of the zoarium
and the expanded summits of the carinae bear large, scattered pores, or pits.
Devonian.

(i, Archimedes dlstans Ulr.
d, Unitrypa acaulis Hall, ö/

(afLer Ulrich, Hall, and Simpson).

Fig. 499.

l/l. h, Polypora simulatrix Ulr. i/i and y/j.
e, Semicoscinium interruptum H. and S. "/i.

:, Hemitrypa proutana Ulr. S/j.
/, FenestraZia compacta Ulr. ö/j

Helicopora Claypole ; Isotrypa, Loculipora, Unitrypa Hall (Fig. 499, d). Silurian
and Devonian.

Hemünjpa Phill. (Fig. 499, c). Differs from Fenestella in having a reticulated
superstructure, wliose meshes correspond in position and number with the zooecial
apertures in the branches beneath. Silurian to Lower Carboniferous.

Archimedes Lesueur (Fig. 499, a). Distinguished from Helicopora by its solid
central axis. As a rule, the fenestrated expansion is broken away, leaving only the
screw-like axis. Lower Carboniferous.

Lyropora Hall. Zoaria flabellate, the fenestrated portion spread between the
arms of a non-celluliferous U- or V-shaped support ; free or pedunculate at the base.
Zooecia in from two to five rows. Lower Carboniferous.

Fenestralia (Prout F'ig. 499, /). Having a median keel as in Fenestella^ but with
four ranges of zooecia instead of two. Lower Carboniferous (St. Louis Group).

Polypora M'Coy {Protoretepora Koninck) (Fig. 499, h). Differs from Fenestella
in having two to eight rows of cells on a brauch, and in wanting a median keel.
The latter is sometimes represented by a row of strong tubercles. Silurian to
Permian.

Thamniscus King. Like Polypora, but branches bifurcating more freely, and with
only a few dissepiments or none. Silurian to Permian.

Phyllopora King. Zoaria funnel-shaped, celluliferous on the outer side, and con-

l

342 MOLLUSCOIDEA— BRYOZOA phylüm v

sisting of anastomosing branches, which form a regulär, roimd-meshed network.
Zooccia in two or more rows. Devonian to Permian.

Ptüoporella, Ptüoporina Hall. Siliirian and Devonian. Eeteporina d'Orb.
Devonian and Lower Carboniferous. Anastomopora Simpson. Devonian.

Family 3. Acanthocladiidae Zittel.

Zoaria poriferous on one side only, pinnate or forminy fenestrated expansions ; con-
sisting of sträng, central stems which give off numerous, smaller, lateral hranches fr am
their opposite margins. The lateral hranches are free or unite with those of the next
stem. Non-poriferous dissepiments ahsent Zooßcial characters mostly as in the Fene-
stellidae. Silurian to Permian.

Pinnatopora Vine. {Glauconome auct., non Goldfuss) (Fig. 500, b, c). Zoaria

small, delicate, with short, free, lateral

^ FSW^ branches given off frequently at regulär

Aji '-.\ ,, ^A^*i^r intervals. Cells in two rows, one on

<^''^ M-'r >'-,''- Z ' ^*^ ^^^^ ^^^^ ^^ ^ moderate median keel.

pp'^ Silurian to Permian.

/^^•|^p.....l Septopora Vroiit. Zoaria fenestrated,

-i ^(^lM yr\ flabellate or leaf-like. Primary branches

^ t> \^^^ numerous, increasiug by bifurcation or

j ' :^\^ j^.^ ^ f Interpolation ; the lateral branches

^^^p^ ^ M/Q uniting with those of adjacent stems.

^^^^ rj.'^m^ Reverse usually with fine Striae and

^ %ti„-»r scattered dimorphic pores. Celluliferous

Fig. 500. side with two rows of zooecia arranged

a, Acanthociadia fruticosa uir. i/i. I&, Pinnatopora as in Pinnatopora. Chester Group and

tenuiramosa Ulr. V^. c, P. vinei Ulr. i/i and 9/i (after q^^^ Measures.

Acanthociadia King (Fig. 500, a).
Like Pinnatopora, but larger, stronger, and with three or more ranges of cells. Goal
Measures and Permian.

Synocladia King. Differs from Septopora in the same manner as the preceding
differs from Pinnatopora. Permian.

Ptilopora M'Coy {Dendricopora Koninck). Zoaria pinnate, the central brauch
much stronger than the oblique lateral branches, which are united by dissepiments.
Zooecia in two ranges. Devonian and Lower Carboniferous.

Diploporaria N. and B. {Diplopora Young). Essentially a Pinnatopora without
lateral branchlets. Garboniferous.

Family 4. Arthrostylidae Ulrich.

Zoaria articulated, consisting of numerous suh-cylindrical segments united into small
pinnate or bushy colonies, or of continuous, dichotomously divided hranches. Zooecia suh-
tuhular, more or less oblique, radially arranged ahout a central axis, and opening on all
sides of the segments ; or one side may he non-celluliferous and longitudinally striated.
Ordovician and Silurian.

Arthrostylus Ulr. (Fig. 501, d, e). Zooecia bushy, dichotomously branching, the
whole consisting of numerous exceedingly slender, equal, subquadrate segments,
united by terminal articulation. Zooecia usually arranged in three rows between
longitudinal ridges ; the fourth face with lougitudinal Striae only. Ordovician.

Helopora Hall (Figs. 501,/; 502). Like the precediug, but the segments are
larger, and have zooecial apertures on all sides. Ordovician and Silurian.

ORDER IV

CRYPTOSTOMATA

343

Sceptro^wra Ulr. Segments short, greatly expanded above, celluliferous all aroimd.
Ordovician and Silurian.

U^

f.- 7\

m

W-J

a, Arthroclema bülingsi Ulr. 2/3. ^^

Fig. 501.
A. armatum Ulr. Segment, 12/j.

c, Nematojwra conferta Ulr. 6/^,

d, e, Ärthrostylus conjunctus Ulr. 12/j. /^ Helopora harrisi Ulr. 12/j (after Ulrich).

Arthroclema Bill. (Fig. 501, a, b). Segments sub-cylindrical, celluliferous on all
sides, arranged pinnately. Articulation both terminal and lateral. Ordovician.

Nematopora Ulr. (Fig. 501, c). Zoaria very slender,
ramose, continiious above the pointed basal extremity. Zooecia
sub-tubular, arranged radially about one or two minute axial
tubes. Ordovician and Silurian.

Glauconome Goldf. (Penniretepora d'Orb.). Zoarium branch-
ing continuously ; reverse side non-celluliferous ; zooecia as in
Nematopora. Ordovician and Silurian.

Family 5. Rhabdomesontidae Vine.

Zoaria ramose or simple, not articulated, sometimes with a
large or small axial tube, and generally solid. In the latter
case the axial region is occupied by thin-walled primitive tubes,
with or without diaphragms. Hemisepta usually present, but
never conspicuous. External zooßcial apertures oval or circular,
regularly arranged, and usually at the bottom of a rhombic or
hexagonal sloping area, or between longitudinal ridges. Mesopores absent. Ordovician
to Permian.

Rhombopora Meek (Fig. 503, b). Zoaria slender, ramose, solid. Zooccial tubes
witb tbe outer or vestibulär region thick-walled, apertures arranged in diagonal
or longitudinal lines. Strong acanthopores and smaller spines generally present.
Ordovician to Permian.

Bactropora Hall. Zoaria simple or only slightly brancbed, the lower extremity
pointed. Lower Carboniferous-.

Rhabdomeson Young. Differs from Rhombopora only in having a slender axial
tube, to wbich the proximal ends of the zocEcia are attached. Goal Measures and
Permian.

Goeloconus Ulr. (Fig. 503, a). Zoaria simple, hollow, expanding gradually from
the striated base ; substance thin. Primitive portion of zooecia short, with well-
developed hemisepta. Lower Carboniferous.

Fig. 502.
Helopora spiniformis Ulr.
Stones River ; Tennessee.

A, Vertical section, l^/i.

B, Segment, l/i and l4/l
(aft«r Ulrich).

344

MOLLÜSCOIDEA— BEYOZOA

PHYLUM V

Nemataxis Hall.

a

Devoiiian. Nematotrypa Bassler. Ordoviciaii. Orthopora Hall.

f

Fig. 603.

a, Coeloconus rliomhicu» Ulr. Vi and surface i^/i. h, Rhoinbopom incrassata Ulr. i/^ and ]«/i. c, StreUotrypa
major Ulr. i/j and 18/^. d, Acanthodema conflucns Ulr. i/i and 24/j (after Ulrich).

Silurian and Devonian. Hyphasmopora Etlieridge. Carboniteroiis. Acanthodema
Hall (Fig. 503, d). Silurian to Lower Carboniferous.

Tropidopora Hall. Devonian. Strehlotrypa Ulricli (Fig. 503, c). Devonian and
Lower Carboniferous.

Family 6. Ptilodictyonidae Ulrich.

Zoaria hifoliate, composed of two layers of zomcia grown together back to back, usualhj
joined at hast at the base, and forming leaf-like expansions, or compressed, branching
or inosculating stems. Mesial plates ivühout median tubuli ; hemisepta usually present.
Inner orifice generally semi-elliptical, the outer more rounded, usually ovate, and
surrounded by either a sloping area or a ring-like peristome. Vestibules separated by
thick walls. Ordovician to Devonian.

Ptilodictya Lonsd. (Heterodictya Nich.). Zoaria lanceolate or falciform, witli a
small basal expansion. In tlie young condition the zoariuni consists of longitudinally
arranged, narrow, oblong-quadrate zocecia, new zooccia, of different width and arrange-

Fig. 504.

a, Esckaropora angularis Ulr. Vi and surface s/j. h, E. subrecta Ulr. »/j. c, d, Stirtoporella cribrosa Ulr. Vi
and surface i8/i. Black River of Minnesota (after Ulrich).

ment, being added subsequently on each side. In the vestibulär or outer region the
walls are more or less thickened, solid, and with a double row of exceedingly minute
dots. Silurian and Devonian.

ORDER If

CRYPTOSTOMATA

'A 1 5

Escharopora Hall (Nicholsonia Waag. and Wentz) (Fig. 504, a, h). Like Ptilodictya
biit apertiires are in diagonally intersecting series. Ordovician.

Phaenopora Hall. Zoaria as in Ptilodictya^ except that tliere are two mesopores in
eacli interspace between tlie ends of tlie zoa3cial apertures. Ordovician and Silurian.

Ärthropora Ulr. Zoaria bushy, spreading in a plane, composed of numeroiis
equal segments. Zooecial apertures elliptical, surrounded by a delicate peristome.
Interspaces witb one or more threadlike ridges, varioiisly disposed, and with a row of
minute papillae. Ordovician and Silurian.

Graptodictya Ulr. Ordovician. Clathropora Hall. Silurian. Stictoporina Hall.
Devonian.

Family 7. Stictoporellidae Nickles and Bassler.

This family differs froni tlie Ptilodictyonidae mainly in that tlie zoarium is not
articulated, but grows upward from, and is continuous with, a spreading base.

Stictoporella Ulr. (Fig. 504, c, d). Zoaria variously formed, wdth elliptical
apertures placed at the bottom of a sloping area. Thick-walled intabulated mesopores
occur between the zocEcial a])ertures and line the zoarial margins. Ordovician and
Silurian.

Stictopora Hall. Ordovician. Ptilotrypa Ulrich. Silurian. Intrapora Hall.
Devonian and Lovver Carboniferous. Coscinella Hall. Devonian. Taeniodictya Ulrich.
Devonian and Lower Carboniferous. Heliotrypa Ulrich. Lower Carboniferous.

Family

Rhinidictyonidae Ulrich.

Zoaria bifoliate, continuous or jointed, forming compressed hranches or leaf-like
expansions; occasionally trifoliate. Primitive celU sub-quadrate, arranged longitudinally.
Both primitive and superficial apertures elliptical or sub-circular, sometimes a little
truncated posteriorly. Inferior hemiseptum and lunarium ivanting. Median tubuli
present between the median laminae, and between the longitudinal rows of zooecial tubes.
Mesopores absent, but vesicular tissue often present. Chiefly Ordovician.

Rhinidictya Ulr. {Stictopora Ulr., non Hall) (Fig. 505, et, c). Zoaria composed of

Fig. 505.

a-c, Rhinidictya mutaUlis Ulr. i/i »nfi surface 9/i. c, Several zooecia »5/j. d, c, Cystalictya gübcrti Meek.

Surface l8/i and tangential section i8/j (after Ulrich).

narrow, compressed, dichotomously dividing, straight-edged branches, attached to
foreign bodies by a continuous expanded base. Ordovician and Silurian.

Eurydictya, Dicranopora, Goniotrypa Ulr. Ordovician and Silurian.

Euspilopora Ulr. Small, irregularly divided branches, with serrated or wavy
edges. Devonian.

346

MOLLUSCOIDEA— BRYOZÖA

PHYLUM V

Phyllodictya Ulr. Zoa3cial tubes long, with complete diaphragms, biit no
hemisepta. Ordovician.
W^ß^Jl^'^J. PcLchydidya (Fig. 506), Trigonodictya Ulr. Ordovician and

Siliirian.

Family 9. Oystodictyonidae Ulrich.

Fig. 506.
Pachydictya foliata

Zoaria consisting of two or three layers of cells grown together
hack to hack, forming hranching, perforated or entire leaf-like ex-
pansions, or triangulär hranches. Primitive cells semi-cordate or
ohovate-acuminate in outline, arranged longitudinally. Primitive
aperture suh-circular, hut hecoming draivn out into a tuhular
vestihule as growth proceeds. Superficial aperture ivith peristome,
and more or less ivell-developed lunarium. Interzooecial Spaces

^esota ^'^^ n^entiai^ec' ^^^^P'^*^^ ^V vesicular tissue, often filled with a calcareous deposit

tion, i4/i (after Ulrich), near the surface. Silurian to Permian.

Cystodictya Ulr. {Arcanopora Vine ; Stictocella Simpson) (Fig. 505, d, e). Zoaria
ramose, branches sharply elliptical, with siib-parallel, non-poriferoiis margins. Inter-
apertural space finely striated, granulöse or smooth ; pits and cells showing only in
a worn condition. Silurian to Permian.

Coscinium Keyserling (Goscinotrypa Hall) ; Dichotrypa Ulr. Silurian to Permian.

Taeniopora Nich. {Pteropora Hall ; Stictoporidra Simpson). Distinguished from
Cystodictya by having a longitudinal ridge or keel, which divides each face into two
equal parts. Devonian.

Thamnotrypa, Semiopora, Äcrogenia, Geramella, Phractopora, Prismopora, Scalaripora
Hall ; Goniocladia Etheridge ; Ptilocella Simpson. Devonian and Lower Carboniferous.

Evactinopora Meek and Worth. (Fig. 507, &, c). Zoaria free, consisting of four or
more vertical leaves arranged in a stellate or cruciform fashion. Lower Carboniferous.

Fig. 507.

a, Glyptopora sagenella-lata Ulr. i/^. b, Evactinopora quinque radiata Ulr. i/j. c, d, E. radiata
Meek and Worthen i/i (after Ulrich).

Glyptopora Ulr. (Fig. 507, a). Zoaria consisting of thin expansions traversed on
both surfaces by salient ridges, or of uni-laminate bases on which the coalescing ridges
of the Upper surface are greatly developed and form large leaves. These ridges or

ORDER V CHEILOSTOMATA 347

leaves are coniposed of two layers of cells growing in opposite directions froin a niesial
laniina. Upper surface with solid maculae or "diinjdes." Lower Carboniferous.

Family 10. Rhinoporidae Ulrich.

Zocecia simple, oblong or rhomboidal, prone along the basal membrane ; vestibules
direct, hemisepta ivanting ; front of zocecia below vestibule usually strengthened with solid
or vesicular tissue. Silurian.

Rhinopora Hall. Zoarium of imdulating, bifoliate expansions ; surface smooth
and traversed by slender bifurcating ridges. Silurian.

Lichenalia Hall. Like Rhinopora but unilaminar. Silurian.
Diamesopora Hall ; Stictotrypa Ulrich. Silurian.

Family 11. Oycloporidae (provisional).

The following genera, all from the Lower Carboniferous, and of doubtfiil affinities,
are placed in this family : Cyclopora Prout ; Cycloporella Ulr. ; Proutella Ulr. ;
Worthenopora Ulr.

Order 5. CHEILOSTOMATA Busk.

(Bryozoaires cellulines, d'Orbigny).

Zocecia oval, turbinate, urceolate, quadrate or hexagonal, arranged usually side by
side. Orißce more or less anterior, of smaller diameter than the zocecium, closed by a
movable cover. Ova commonly matured in external marsupia. Appendicular organs
frequently present.

The earliest Cheilostomata appear sparsely in the Jura of Normandy, but their
progenitors are undoubtedly to be looked for in the Paleozoic Cryptostomata. They
attain an astonishing development in the Upper Cretaceous, and in the Tertiaries and
existing seas they greatly surpass the Cyclostomata in number and variety of species.

Not all of the Cheilostomata have a completely calcified zoarium, some being
corneous and flexible (Flustridae), and others having the front wall of the zocecia
more or less membraneous and the rest calcareous (Membraniporidae). Consequently,
in fossil examples of the latter, the zocecia are entirely open on the upper or front
side (Fig. 477). Avicularia and vibracula are very commonly present, and are
indicated in fossils by the " special pores " in which they were lodged. External
ovicells are more commonly developed than in the Cyclostomata, and usually occur as
rounded, blister-like cavities in front of the zocecial apertures. Reproduction by
gemmation takes place at the growing edge of the colony, the young cells arising
from the anterior end or from either side of the parent cell ; and repeated gemmation
almost always results in a more or less regulär arrangement in series. Direct
communication between adjoining zooecia is effected by means of small perforated
plates (communication plates, Rosettenplatten), set in corresponding positions in the
side walls of each zocecium.

In the Classification of the Cheilostomata, the presence or absence of the compensa-
tion sac is of great importance. This is a thin-walled sac opening outward through
a pore, the ascopore, and provided with muscles whose contraction distends the sac
with the result that the polypide is extended.

Although much work has been done in recent years upon the morphological and
systematic study of the Cheilostomata, their Classification, particularly the genera of
the fossil forms, is still in an unsettled condition. The older Systems of d'Orbigny
and Busk were highly artificial, undue promincnce having lieen given to zoarial
modifications ; but through the labours of Smitt, Hincks and Waters, who have

348

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

demoiistrated tlie inucli greater importance of zocccial cliaracters, a decided advance
was made, Levinsen's stiidies lipon tlie recent Clieilostoiiiata liave resiüted in a
splendid, detailed Classification which nnfortunately depends upon cliaracters making
it difRcult of application to the fossil forms. Only brief descriptions of tlie more
iinportant genera, or those liaving niimerous fossil representatives, can be introduced
liere.

Suborder A. ANASCA Levinsen.

Gompensation sac wanting ; frontal löall membraneous or calcareoiis, d&pressed and
surrounded by raised margins ; opercular and subopercular areas not separated by a
calcareous bar.

Family 1. Aeteidae Hincks.

Zoarium miilinear, adnate ; zooßcia partially erect^ with membraneous apertures.
Aetea Lam. Tertiary and Recent ; Europe.

Family 2. Eucrateidae Hincks.

Zoaria branching, erect and free, or recumbent. Zooecia uniserial or biserial,
pyriform, with a sub-terminal and usually oblique aperture. Avicularian and

vibracular appendages ivanting. Cre-
taceous to Recent.

Eucratea Lamx. (Fig. 508).

Zoaria entirely deciimbent, or com-

posed of a creeping adlierent base

and erect braiicliing slioots. Zooecia

calcareous or siib-calcareoiis, rising

oiie from anotlier so as to form

Single series. Brauches springing

froin tlie front of a zooeciiim Ijelow

Fig. 508. the aperture. Cretaceoiis to Recent.

Eucratea lahmta (Novak). Cenomanian ; Velim, Bohemia. Gemellaria Savigliy ; Notamia

A, Zoarium, i/^. B, Zooecia, tliree of them with fractured -^^^ • m x- i -d +

waiis, highiy magnified (after Novak). Fleming, lei'tiary aiid Recent.

Family 3. Scrupocellariidae Biisk.

Zoarium erect, usually jointed, dichotomously branching, phytoid. Zooecia in two
or more series, closely united and arranged in the same plane. Sessile avicularia and
vibracula generally present. Tertiary and Recent.

Menipea, Caberea Lamx. ; Scrupocellaria Van Beiied. Eocene and Recent.

Family 4. Oellulariidae Levinsen. {Salicornariadae Biisk).

Zoarium erect, sub-cylindrical, dichotomously branching, usually jointed. Zooicia
rhomboidal or hexagonal, each corresponding to an area, and disposed in series about an
imaginary axis. Front depressed, usually concave. Orifice crescentic or semicircular,
situated slightly above the centre of the cell. Ocecia inconspicuous, opening at or near
the summit of the area above the orifice. Avicularia usually present. Cretaceoiis to
Recent.

Gellularia Pallas {Cellaria Lam,; Salicornaria Cuv.) (Fig. 509). Zoarium jointed.

ORDER V

CHEILOSTOMATA

349

tlie Segments sul)-cylindrical and coinicctcd l)y (Icxilde, lioiny tiil)c<. Z^dvia
inimerscd, siiii-omidcd hy a laiscd Ix.fder, di.^po^c'd in (juincLinx.

Aviciilaiia iriegu-
larly distiilnited,
sitiiated above a cell,
or occiipying tlie
place of one.

Fio. 509.

Cellularia rhombiferu
(Goldfuss). Oligocene ;
Kanfiingen, near Cassel.
Enlarged (after Reuss).

Encnisting zoarium of Memtranipora, with
non-calcifled zocecial walls. Magnified.

Fig. 511.

Memhranipora plebeia
(G. and H.). Cretaceous ;
N. J. Several cells highly
magnified (after Gabb and
Hörn).

Family 5. Membraniporidae Busk.

Zoarium calcareous or membrano-calcareous, encrusting or erect, in the latter case
bifoUate, or suh-cylindrical. Zocecia placed side hy side, and forming an irregulär
continuous exjpansion, or in linear series. Margins raised, the depressed front more or
less memhranous.

Memhranipora Blainv. (? Marginaria Roemer ; (?) Dermatopora Hagw.) (Figs.
510-511). Zoaria encrusting, calcareous or sub-calcareous. Zooecia arranged
irregularly or in rows, without a calcareous lamina on the front, or only partially
covered by one, leaving a variously sliaped aperture. Jurassic to Recent.

Tremopora Ortmann. Like Memhranipora, but has a large avicularium and
bifurcated spine on tlie border. Tertiary to Recent.

Hagenoiüinella Canu. Cretaceous.

Family 6. Selenariidae Busk.

Zoaria circular or irregulär in outline^ the celluliferous side convex, the lower concave
or ßat, prohahly free in the mature condition. Upper surface areolated, the zooecia

Fig. 512.

ll;i-w.

l'l'l'

CrctacH'ous
I', ciilargt'd.

Ijünt'lutru;.

350

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

immersed, their horders elevated. Orifice rounded or semi-elli'ptical^ situated more or less
in advance of the depressed front. Small vihracular cells usually present. Cretaceoiis
to Becent.

LunuUtes Lamx. (Fig. 512). Zooecia arranged in series radiating from the
centre and bifiircating as they advance toward tlie border. Vibracular cells usually
elongate, lying in linear series between the rows of zooecia. Very abundant in the
Upper Cretaceoiis and Tertiary ; also Recent.

Vibracular cells wanting. Zoojcia equal,
hexagonal, not arranged in radiating series.
Cretaceous.

Selenaria Busk. Cretaceous to Recent.

Stichopora Hagw. emend. Busk.

Fig. 513.
Memhraniporella
ahbotti (G, and H.).
Cretaceous ; N.J.
Zooecia highly mag-
nified (after Gabb
and Hörn).

Fig. 514.

Cribrilina heermanni
(G. and H.). Post-Plio-
cene ; Santa Barbara
Co.,Cal. Zooecia highly
magnifled (after Gabb
and Hern).

Family 7. Oribrilinidae Hincks.

Zoaria encrusting or erect. Zooecia having
the front wall more or less fissured, or traversed
by radiating furrows. Cretaceous to Recent.

Memhraniporella Smitt (Fig. 513). Zoaria
encrusting or rising into free foliaceous ex-
pansions, sometimes consisting of superim-
posed layers. Zocecia closed in front by a
number of flattened calcareous ribs more or less Consolidated centrally. Cretaceous
to Recent.

Grihrilina Gray (Fig. 514). Zoaria usually encrusting. Zooecia having the
front more or less occupied by radiating or transverse rows of punctures, each row in
a furrow ; orifice semicircular or sub-orbicular, Cretaceous to Recent.

Family 8. Onyohocellidae JuUien (emend.).

Zoaria encrusting or erect, ramose, continuous, the hranches more or less compressed
and hilaminar ; surface areolated. Zooecia usually hexagonal, their margins raised,
the front not entirely calci-
fied. Opesial aperture of
moderate size, generally semi-
elliptical, sometimes spread-
ing helow, in other cases suh-
circular. Oral opening
small, usually crescentic or
semicircular. Ooecia in-
conspicuous ; intercalated
vicarious avicularia gener-
ally present; special pores
wanting. Jurassic to Re-
cent ; chiefly Cretaceous.

Fig. 515,

Onychocella angu-
Zosa(Reuss). Upper
Eocene ; Northern
Italy. Surface, 20/^
(after Waters).

Fig. 516.

Vincularia virgo Hagw. Upper Cretaceous ;
Rügen. a, Portion of zoarium, i/^. h, Cross-
section. c, Vertical section, enlarged.

Onychocella JuUien {Es-
chara, Flustrellaria, p.p.,
d'Orb. ; Cellepora, Mem-
hranipora, Vincularia, etc.
auct.) (Figs. 515, 516). Zoaria encrusting or erect. Oral opening semicircular or
crescentic. Avicularian openings simple, oval ; the area in which they are situated
drawn out above. Jura of Normandy, and Cretaceous to Recent.

ORDER V

CHEILOSTOMATA

351

Vibracella Waters (Flustrellaria^ p.p., d'Orb.). Difters from Onychocella in liaving
a larger apeiture, wliich is often somewhat expanded below, and liaving vibracular
cells instead of avicularia. Cretaceons and Tertiary.

(?) CumuUpora Münst. (Fig. 517). Zoaria irregularly massive. Zocecia partly

CumuUpora angulata Münst, Oligocene ; Doberg, near Bünde. A, Zoarium, natural size. B, Upper
surface, enlarged. C, Vertical section, enlarged (after Reuss).

recumbent, partly erect, and placed one above tbe other, so tliat tliey appear to form
tabulated tubes. Tertiary.

Floridina Jullien. Like Onychocella but opesium trifoliate. Cretaceoiis to
Recent.

SmitUpora Jullien ; Euritina Cann. Cretaceous to Recent.

Family 9. Microporidae Smitt.

Zooßcia liaving the front wall entirely calcareous ; usually with sharply elevated
margins, fissures or perforations. Cretaceous to Recent.

Micropora Gray (Fig. 518). Zoaria encrusting. Zooecia witli
prominent raised margins : the front depressed, witli a Perforation
at each upper angle below the semicircular or rounded orifice.
Cretaceous to Recent.

Steganoporella Smitt ; Setosella Hincks ; Rhagasostoma Kos-
chinski ; Gupularia Lam. ; Gargantua Jullien. Tertiary to Recent.

Suborder B. ASOOPHORA Levinsen.

■ '-^^

Fig. 518.
Micropora disparilis

Compensation sac present, opening most often on the proximal side ^jo^g'jfg ;^anta^ari

of the operculum, more rarely further bara Co.,'cai. Zocecia

back through a median pore (ascopore). (af^J ^ Gabb"'and

A calcified transverse har hetween the Hörn).
opercular and suh-opercular areas.

Family 10. Microporellidae Hincks.

Zoaria encrusting or erect^ foliated or dendroid.
Zooecial orifice more or less semicircular^ with the lower
margin entire ; a crescentic or circular pore on the front
wall usually just beneath the orifice. Cretaceous to Recent.

Microporella Hincks (Fig. 519). Zoarium encrusting
or erect, bilaminar. Margin of zooecia not elevated.

Fig. 519.
Microporella rudis (Reuss).

Oli-

SgJi.^''^'"°'"- ^l^P^^^"^f""«' Orifice with a straight, entire lower border, frequently

352

MOLLUSCOIDEA— BRYOZOA

PHYLÜM V

with oral spiiies, Usually one seini-lunate or circular pore beneatli tlie orifice,
occasionally two or tliree. Tertiary and Recent.

Family 11. Porinidae d'Orbigny.

Zoaria encrusting, or erect and ramified. Zooßcia with a raised tubulär or sub-tubular
orifice, and frequently with a special pore on the front wall. Cretaceous to Recent.

Porina d'Orb. Zoaria consisting of flattened or snb-cylindrical branclies, celluli-
ferous on botli sides, or encrusting. Witli age tlie sj)aces between the raised apertures
becoine filled with a porous calcareous deposit. Avicularia and oa3cia occasionally
distinguishable. Cretaceous to Recent.

Family 12. Smittinidae Levinsen.

For this and the next foUowing family only provisional diagnoses can be given at
the present time, and for that reason none is attempted here.

Smittina Norman (ßmittia Hincks). Zoaria encrusting, or erect and foliaceous.
Primary orifice of zooecia sub-orbicular, the lower margin with an internal median
denticle. Secondary orifice canaliculate below ; generally a small avicularium either
within or just beneath the sinus. Cretaceous to Recent.

Mucronella Hincks (Fig. 520). Similar to Smittina, but with simpler orifice,
and the lower part of the peristome elevated into a more or
less prominent mucro. Cretaceous to Recent.

Porella Gray. Zoaria encrusting or erect. Zocecia with a

Fig. 520.

Mticronella coccinea
Abildg. Miocene ; Eisen-
stadt, Hungary. Anuiii-
ber of zooecia enlarged
(after Renss). The aper-
tures are denticulated,
and each zooecium has a
pair of avicularia. o,
Ovicell.

Fig. 521.

Lepralia pallasiana Moll.
Recent ; England. Zocecia
highly magnitied (after
Hincks).

Fi(}. 522.

Schizoporella cornuta
(G. and H.). Post-
Pliocene ; Santa Bar-
bara Co., Cal. Zooecia
highly magnified

(after Gabb and
Hörn).

semicircular primary orifice; the secondary (adult) orifice elongate, inversely sub-
triangular, or horseshoe-shaped, and enclosing an avicularium with a rounded or
sub-triangular mandible. Cretaceous to Recent.

Family 13. Lepraliidae Smitt.

This family, like the preceding one, can be only provisionally defined at present.

Lepralia Johnson (Fig. 521). Zoaria encrusting or rising into simple or branching
expansions, composed of one or two layers of cells. Zooecia usually ovate, the orifice
with a thin peristome and entire lower margin. Rare in Cretaceous, more abundant
in Tertiary and Recent.

Hippoporina Neviani. Like Lepralia but aperture constricted ])y two lateral
teeth. Tertiary.

Schizoporella Hincks (Fig. 522). Zoaria variable : zooccial oiifice varying from

ORDER V

CHEILOSTOMATA

353

semicircular to sub-orlncular, the loAver margin witli a distiiict siniis. Cretaceoiis to
Recent.

Family 14. Meniscoporidae Caiiu.

This family is characterised by the occurrence of three kinds of zooecia : (1)
typical zocecia, (2) genesies or zooscia bearing internal oa3cia, and (3) aviciilaria.
Abundant in Tertiary.

Meniscopora Gregory. Aperture constricted as in Hippoporina.

Schizostoma Canu. Like Schizoporella biit with genesies.

Poristoma, Poricella, Smittistoma and Galvetina Canii ; Lohopora Levinsen.

Family 15. Reteporidae Smitt.

Retepora Imperato {Phidolophora Gabb and Hörn) (Fig. 523). Zoaria consisting
usually of inosculating brancbes whicb spring from an encrusting base. Zooecia
disposed on one face of tlie brancbes only, in most cases immersed. Primary orifice

Retepora celhdosa Linn. Cra^
Suffolk, England.

Fig. 524.

Myriozoum jninctatum (Phill.). Miocene ; Ortenburg, Bavaria. A,
Zoarium, i/i- B, Upper surface, enlarged. In the forward portion the
apertures are open ; in the rear, covered over by a calcareous deposit.
C, Gross section of a branch.

rounded or semi-elliptical with entire border. Afterwards the peristome becomes
miicli raised and multiform ; usually there is a fissure below, or there may be a
prominent rostrum bearing an avicularium. Tertiary and Recent.

Family 16. Myriozoidae Smitt.

Myriozoum Donati {Myriopora Blainv. ; Vaginopora Reuss) (Fig. 524). Zoaria
consisting of thick, dichotomously dividing branches, obtuse at their growing ex-
tremities, and rising from an attached basal expansion. Zooecia disposed about an
imaginary axis, even at the surface, their boundaries scarcely distinguishable. Entire
surface and also the inner walls minutely porous. Orifice above the centre of the
zooecium, sub-orbicular, notched or canaliculate below. As a rule, the openings are
closed on the lower parts of tlie branches by a calcareous pellicle. Tertiary and
Recent ; perhaps also Cretaceous.

Family 17. Celleporidae Busk.

Zocecia urceolate, more or less erect, and irregularly crowded together ; often forming
several or many superimposed layers.

Gellepora Fabricius, emend. Busk (Spongites Oken ; Celleporaria Lnmx.) (Fig.
525). Zoarium multiform, encrusting, or erect and ramose. Zocucia in the oldcr
VOL. I 2 A

354

MOLLUSCOIDEA— BRYOZOA

PHYLUM V

portions : iiiore or less erect and very irregiüaiiy disposed. Orifice terminal, entire
or sinuated, witli or wifhoiit internal denticles ; in connection witli it are usually one

or more rostra bearing avicularia. Inter-
calated avicularia generally present also. The
surface of weatliered specimens dotted by
the unequal apertnres of vesicle-like cells.
Tertiary and Recent.

Subclass 2. PHYLAOTOLAEMATA
AUman.

The Bryozoa referred to this subclass
are soft - bodied, and therefore cannot be
expected to be found fossil except under
unusual conditions of preservation. The
fresh- water Cenomanian beds of Bohemia
have yielded an organism incrusting a Unio,
resembling the Recent genus Plumatella.
Although the structure is too iniperfectly preserved for certain Identification, this
specinien {Plumatellites proliferus Fric) may well be a fossil representative of the
Phylactolaemata.

Fig. 525.

Cellepora conglomerata Goldfuss. Oligocene
Astrupp, near Osnabrück. A, Zoarium, i/i
B, Upper surface, enlarged.

Range and Distribution of the Bryozoa.

The class Bryozoa begins in the earliest OidaYifiianj and is represented con-
tinuously up to the present time. The older Paleozoic forms belong chiefly to two
Orders — the Cyclostomata and Trepostomata.

A considerable nuinber of Cyclostomatous genera are present in the Ordovician,
niost of them being closely related with Mesozoic and Recent types ; but throughout
the remainder of the Paleozoic, and in the Trias also, the order is very sparingly
represented (except for the Ceramoporidae and Fistuliporidae), and in some parts quite
absent. In the Jura and Cretaceous, however, a reniarkable increase took place,
hundreds of species being known from these forniations. During the Tertiary their
strength was again materially reduced, and the living Cyclostomata barely exceed
100 species in number.

The Trepostomata appear suddenly and in great variety in the Ordovician, from
which over 400 species are known, but entered almost immediately upon a period of
decline. From the Trenton and Cincinnati groups alone more species have been
described than from all of the later Paleozoic formations put together. There is at
present no evidence to show that the group survived later than the Paleozoic era, but
it is not unlikely that their descendants may be found among certain Mesozoic
families, such as the Ceidae, which are provisionally assigned to the Cyclostomata.

The Cryptostomata are likewise confined to rocks of Paleozoic age, but, as has
been remarked above, may be very confidently regarded as the forerunners of the
Cheilostomata, True members of tlie latter group are first met with in the Jura, but
they develop rapidly, and from the Cretaceous onward remain the dominant type.

The Triassic and Liassic Bryozoans belong chiefly to the Cerioporidae. This
family, together with the Diastoporidae, Fascigeridae, and other members of the
Cyclostomata, is abundantly represented in the Middle Jura of Lorraine, Southern
Germany, England and Normandy. The Upper Jura, on the contrary, yields com-
paratively few Bryozoan fossils.

The Cyclostomata still predominate in the Neocomian and Gault, but in the

CLASS II BEACHIOPODA 355

Cenomanian a niimber of Clieilostomatous genera make their appearance. The fauna
is especially well developed in tlie vicinity of Le Mans, Havre and Essen, and in
Saxony, Northern Germany and Bohemia.

Bryozoans are surprisingly abundant in the Upper Cretaceous, particularly in the
Upper Pläner of Northern Germany, Saxony and Bohemia, in the White Chalk, and
the facies of Aix-la-Chapelle and Maestricht. D'Orbigny alone has described not less
than 547 species of Upper Cretaceous Cyclostomata, and about 300 Cheilostomata ;
many of these, however, are Synonyms or unrecognisable.

The Cheilostomata retain their siipremacy throughout the Tertiary period. The
Eocene and Oligocene deposits of the northern and southern slopes of the Alps are
remarkable for the abundance of their Bryozoan remains ; some of the most noted
Eocene localities being Kressenberg, Hammer and Neiibeuern in Upper Bavaria ;
Mossano, Crosara and Priabona, near Vicenza ; and Oberburg in Styria. The
Oligocene of Northern Germany, and the Miocene of Touraine, the Rhone Valley,
Upper Swabia, and the Vienna Basin, are also remarkably rieh in Bryozoan remains.
The Pliocene fauna of Italy, Rhodes, Cyprus and England (notably the Coralline
Crag) is made up almost entirely of existing genera, and in many cases of existing
species.

[The revision of the preceding chapter on Bryozoa has been prepared for the present
edition by Dr. R. S. Bassler, of the United States National Museum at Washington, D.C. —
Editor. ]

Olass 2. BRAOHIOPODA Dumeril.^

(Revised by Charles Schuchert.)

Bivalved Molluscoidea with inequivalved, equilateral shells attached to extraneous
objects by a posterior Prolongation of the body, or pedicle, throughout life or during

^ Literature : A. Anatomy and Embryology. — Hancocky A., On the Organisation of Brachio-
poda. Phil. Trans., 1858, vol. cxlviii. — Morse, E. S., On the Early Stages of Terebratulina
septentrionalis. Mem. Boston Soc. Nat. Hist., 1873, vol. ii. — On the Systeniatic Position of the
Brachiopoda. Proc. Boston Soc. Nat. Hist., 1873, vol. xv. — KovalevsM, A. 0., Observation on the
Development of Brachiopoda. Proc. Inip. Soc. Amateur Nat. Moscow, 1874, vol. xiv. — Brooks,
W. K., The Development of Lingula and the Systematic Position of the Brachiopoda. Sei. Results
Chesapeake Zool. Lab. 1878. — ShipLey, A. J£., On the Structure and Development of Argiope.
Mittheil. Zool. Station Neapel, 1883, vol. iv. — Oehlert in Fischers Manuel de Conchyliologie.
Paris, 1887. — Beecher, C. E., and Clarke, J. M., The Development of some Silurian Brachiopoda.
Mem. New York State Museum, 1889, vol. i. — Beecher, 0. E., Development of the Brachiopoda.
Amer. Journ. Sei., 1891-92, vols. xli., xliv. — Revision of the Families of Loop-bearing Brachiopoda.
Trans. Conn. Acad., 1893, vol. ix. — Beecher, C. E., and Schuchert, C, Development of the Shell
and the Brachial Supports in Dielasma and Zygospira. Proc. Biol. Soc. Washington, 1893,
vol. viii. — Biickman, S. S., Homoeomorphy among Jurassic Brachiopoda. Proc. Cotteswold Nat.
Field Club, 1901, vol. xiii. — Brachiopod Homoeomorphy : Pygope, Antinomia, Pygites. Quart. Journ.
Geol. Soc. London, 1906, vol. Ixii. — Brachiopod Homoeomorphy : " Spirifer glaber." Ibid., 1908,
vol. Ixiv. — Blochmann, F., Untersuchungen über den Bau der Brachiopoden. Jena, 1892, 1900.

B. Distribution of Recent Forms. — Schuchert, C, Paleogeographic and Geologie Signiticance of
Recent Brachiopoda. Bull. Geol. Soc. America, 1911, vol. xxii.

C. Bibliography. — Dali, W. H., Index to the Names which have been applied to the Sub-
divisions of the Class Brachiopoda. Bull. U.S. Nat. Museum, No. 8, 1877.— Davidson, T., and
Dalton, W. H., Bibliography of the Brachiopoda. Palaeont. Soc, 1S86.— Schuchert, C, Synopsis
of American Fossil Brachiopoda. Bull. U.S. Geol. Surv., 1896, No. 87.

D. Systematic Workü. — Walcott, C. D., Cambrian Brachiopoda. Mon. 51, U.S. Geol. Surv.,
1912. — Davidsoll, T., Monograph of British Fossil Brachiopoda. Palaeontographical Society,
1851-86, vols. i.-v. — Idem, A Monograph of Recent Brachiopoda. Trans. Linn. Soc, 1886-88,
vol. iy. — Waagen, W., Salt Range Fossils. Palaeont. Indica, ser. 13, 1882-85, vol. i.—Bittner, A.,
Brachiopoda der Alpinen Trias. Abhandl. k.k. geol. Reichs-Anst., Wien, 1891-92, vols. xvi., xvii.—
Hall, J., and Glarke, J. M., Introduction to the Study of Palaeozoic Brachiopoda. Palaeont. New
York, 1892-95, vol. viii., parts 1, 2.— Au Introduction to the Study of the Brachiopoda. Rept.
New York State Geologist, 1892-93, parts 1, 2.— Schuchert, C, Synopsis, etc.. see above.—

356 MOLLUSCOIDEA phylum v

only a portion of their existence, or cemented ventrally. Valves ventral and dorsal.

In composition, phosphatic or calcareous or hoth. Animal enveloped ly two pallial

memhranes intimately related to the shell. Within the mantle cavity at the sides of the

mouth are inserted the two, more or less long, oral, usually sinrally enrolled, cirrated

hrachia, which are variously modified, and are supported in the Terehratulacea and

Spiriferacea by an internal calcareous skeleton, or hrachidium, attached to the dorsal

valve. Anus present or absent. Central nervous System consisting of an oesophageal

\ ring with weakly developed hrain and infra-oesophageal ganglionic swellings. Blood-

S vascular System probaUy present with the sinuses developed into vascular dilatations

\ at the hack of the stomach and elsewhere. Sexes separate. Exclusively marine.

The class begins well represented in the Lower Cambrian, attains its
maximum development in the Silurian and Devonian, and is represented by
about 158 living species. Probably upwards of 7000 fossil and recent species
have been described ; these are distributed in 450 genera, grouped in 42
families, 14 superfamilies, and 4 Orders.

Cuvier (1792 and 1802) was the first to distinguish the Brachiopods from
the Acephala, and created for them a fourth family in his class of Molluscs.
To Dum^ril (1806) we owe the now generally accepted class name Brachio-
poda, or arm-footed animals. Since the arms, or brachia, are not homologous
with the foot of Molluscs, Gray (1821) changed the name to Spirobranchiopoda ;
BlsLinYiWe (1824:) to Falliobranchiata ; Risso (1826) to Branchiopoda ; Broderip
(1839) to Brachiopodidae ', Agassiz (1847) to Branchionopoda ; Bronn (1862) to
Brachionocephala ; Paetel (1875) to Branchionobranchia ; and Haeckel to Spiro-
hranchia. None of these has displaced Dumöril's term, though the latter is
founded on a false physiological Interpretation of the brachia.

Bxternal Characters : Form. — The shells of Brachiopods are very
variable in form. Usually both valves are convex, but they may be nearly
flat, with the interior cavity extremely shallow, or the dorsal valve may be
concave and follow closely the curvature of the convex ventral valve. The
ventral valve may be cone-shaped, with the dorsal operculiform, or the
former may be so modified by cementation as to assume the appearance of a
Cyathophylloid coral. The shell is commonly rostrate, with the ventral beak,
or apex, more or less incurved over that of the dorsal valve, or the valves
may be very greatly extended transversely. In fact, the form of the shell of
Brachiopods is so variable that, as a rule, no greater value than specific can
be attached to this feature.

Fixation. — The animal is generally attached to extraneous objects by a
muscular pedicle which projects either from between the contracted posterior
margin of the two valves (Fig. 536, A), through an opening in or under the
beak (Fig. 535, B), or through the ventral valve (Fig. 556, A). With
increasing age, however, the pedicle opening frequently becomes closed, and
the pedicle itself atrophied. The animal may then be anchored by spines

Schellwien, E., Die Fauna der Trogkofelschicliten. Abhandl. d. k.k. geol. Reichs- Aiist., 1900,
vol. xvi., pt. 1. — Skupin, H., Die Spiriferen Deutschlands. Geol. -pal. Abhandl., 1901, vol. viii.—
Tscher nyschew, T. , Die obercarbonischen Brachiopoden d. Ural und d. Timan. Mein. Comite Geol. ,
1902, vol. xvi., No. 2. — Girty, G. H., The Guadalupian Fauna. Profess. Paper 58, U.S. Geol. Surv.,
1908. — Buckman, S. S., Brachiopod Nomenclature. Ann. Mag. Nat. Hist. (7), 1906, vol. xviii.
— The Genotype of Terebratula. Ibid., 1907, vol. xix. — Brachiopod Morphology : Cincta, Eudesia,
and the Development of Ribs. Quart. Journ. Geol. Soc. London, 1907, vol. Ixiii. — Weiler, S.,
Internal Characters of some Mississippian Rhynchonelliform Shells, Bull. Geol. Soc. America,
1910, vol. xxi. — Genera of Mississippian Loop-Bearing Brachiopoda. Journ. Geol., 1911, vol. xix.

CLASS II BRACHIOPODA 357

(Chonetes, Produäus) or be cemented by the whole or a part of the surface of
the ventral valve (Crania, Davidsonia, Thecidea, Streptorhynchus). In some cases
(Glottidia and Lingula) Brachiopods live throughout life partially buried in the
sand or mud of the sea-bottom.

Ornamentation. — The external form and ornamentation of the shell afford
important characters for determining the species. The anterior margin of
one valve is frequently indented by a median sinus, and the other usually
exhibits a corresponding /oZc?, or elevation.

In the earliest shell growth stages Brachiopod shells are invariably smooth,
and may remain so throughout life, but the greater number develop radial
Striae, ribs or undulations, and these are usually crossed by concentric growth
lines, or lamellae, which are sometimes of great width, or may be extended into
spines. There may be more or less long tubulär spines scattered over one or
both valves, or sometimes restricted to a single row along the cardinal line.
Under the term Loricatae, Leopold von Buch included all Brachiopods in which
the radial folds, or costae, are arranged in regulär succession in such manner
that elevated ridges at the anterior margin of one valve coincide with the
indentations of the other. In the Biplicatae, a median fold or sinus is
bordered on either side by a broad fold. In the Cindae, the plications of the
two valves meet at the anterior margin in such manner as to form a straight
instead of a crenulated line, as in the Biplicatae. In young specimens the
ribs and folds are less prominent and numerous than at maturity. In very old
or senile individuals the shell is usually thickened and obese, and the growth
lines are much crowded anteriorly. At this stage inherited specific characters
are seen to disappear, and at the same time new ones may be introduced.

Shell Strudure. — The test of Brachiopods is composed of laminae of various
structure and composition, but difFers considerably from that of Molluscs.
The shell may be wholly calcareous or alternately calcareous and corneous.
When entirely calcareous the laminae are never more
than three in number : an inner thick prismatic layer,
an intermediate laminar layer, and an outer epidermal
film. The inner layer is made up of flattened prisms of
calcite arranged parallel to one another with great regu-
larity, and forming an acute angle with the surface of the
shell (Fig. 526). In the Thecidiidae these fibrous prisms
are so intimately united with one another that the shell
substance appears almost homogeneous. Very often the
fibrous layer is perforated by a series of minute canals
which pass from one surface of the valve to the other
in a more or less vertical direction, and are somewhat p^^ ^26

dilated externally. These canals contain tubuli, or certain prismatic fibrous struc-
prolongations derived from the mantle, but never com- (S[Aj?SÄto^^
municate with the exterior, owing to the fact that the (after Carpenter).
laminar layer of the shell is always covered with a
chitinous epidermis (periostracum). With the aid of a magnifier the openings
of these canals are visible in fossil forms, and they may be also seen in recent
specimens after the epidermis has been removed by an application of caustic
potash (Fig. 527). According to the presence or absence of tubuli, Brachiopods
are distinguished as pundate or impundate.

The Craniidae have thick shells composed of concentric layers of carbonate

358

MOLLUSCOIDEA

PHYLÜM V

of lime. In Crania the shell substance is homogeneous, and punctured by
distally branching canals. In the Lingulidae and Obolidae the shell consists

of alternating layers of phosphate of

lime, admixed with lime carbonate,

and a lustrous horny substance known

as ceratin. The calcareous layers are

prismatic, and are traversed by fine

tubuli (Fig. 528). It

is believed that the

function of the punc-

tae is for respiration,

but the fact that these

extensions of the

mantle are not ex-

verticai section posed to the water

of a Lingula shell

Fig. 527.

A, Punctate exterior of a Terebratuloid shell,
slightly enlarged. B, Vertical section of shell of
Magellania flavescens, showing distally enlarged tubules,
Joo/j. c, Inner surface of Magellania shell, showing
ends of tubules and oblique calcareous prisms, loo/^
(after Carpenter).

sLrvinT anernate Hiay not aCCOrd with

corneous («) and this explanation.

calcareous (ö) layers. tt- f -r.

Strongly magnified VolveS. BrachlO-

(after Gratiolet). t i t i i

pods are delicately
constituted animals, covered by two very vascular mantle lobes which secrete
the calcareous or corneo- calcareous valves, of which one is dorsal and the
other ventral in position. The valves are often thin and of unequal size, but
the inequality is rarely of such a nature as to disturb the bilateral symmetry
of the shell.

During life the ventral valve, which is commonly the larger of the two, occu-
pies typically a superior position, and the dorsal is down. But in describing
the shell, it is always so oriented that the posterior margin, or hinge-line, is
placed above, and the anterior one below. A line drawn from the beak to the
anterior margin describes the length ; and one at right angles to the same, in
the direction of right and left, the width ; a third line drawn perpendicularly
to the other two, and passing through the centres of the valves, measures the
thicJcness. In the Protremata and Telotremata the ventral valve is convex, and
curved in such manner at the posterior margin as to form a heak The beak
may be pointed, or it may be perforated by a round opening, or foramen, for
the Protrusion of the pedicle. In many cases, however, the pedicle opening
lies underneath the apex of the beak, and sometimes encroaches upon a
portion of the dorsal valve. In the Atremata the pedicle emerges from
between the two valves ; in the Neotremata the posterior margin of the
ventral valve is notched, or there may be a small, circular, eccentric Per-
foration, or a more or less long, narrow slit. In the Telotremata the pedicle
opening, or delthyrium, which is originally triangulär in form, becomes either
wholly or partially closed by the growth of deltidial plates. In the Protremata
the delthyrium is closed by a true deltidium, while in the Neotremata and
Atremata a similar looking plate may be present, but as it is of a difFerent
origin, being secreted by the mantle, it is called the homceodeltidium.

The Cardinal area is a term applied to the flattened or curved triangulär area
which is frequently observable between the hinge-line and the beak (Fig. 529). It
is more highly developed in the ventral than in the dorsal valve, and is bisected
medially by the triangulär delthyrium. A true cardinal area is absent in the
Atremata and Neotremata ; but when a small area is present in these Orders, it is

CLASS II

BRACHIOPODA

359

Fio, 529.
Cyrtina heteroclyta

called a false cardinal area (Fig. 546, B, G). A split tubulär structure, or syrinxy

whicli partially encloses tlie pedicle, is developed in the delthyrium of some spire-

beariiig forms.

The deltidium has its origiu in the Cephalula stage of Protremata {Thecidea

mediterranea) contemporaneously with the rudiments of the dorsal

and ventral valves, while the embryo is still in the free swimming

condition. The dorsal valve and incipient deltidium appear first,

being secreted by the rudimentary dorsal mantle and the dorsal sur-

face of the body, the latter subsequently becoming the pedicle. The

ventral valve is formed last, but is widely separated from the dorsal.

Between the two valves is placed the short and thick, but as yet

unattached pedicle, on the dorsal surface of which the third plate,

known as the prodeltidium, still remains. Shortly before the animal

becomes fixed by the pedicle, the prodeltidium fuses with the posterior (Defr.). High car-
-.1 iimi TT. ,. ^ , dinal arpa of ventral

margin ot the ventral valve. The pedicle is at this stage entirely valve showing dei-
surrounded by shell, being enclosed on one side by the ventral valve, fuged'" deiTidia^
and on the other by the deltidium. The latter plate then continues piates, or i)seudo-
to grow as one piece, extending from the apex in an anterior direction,
and is secreted entirely by the pedicle (Fig. 541). The deltidium is never punctate
in structure, but it may l)ear spines (Äulosteges), and sometimes exhibits a round er
pedicle Perforation {Glitambonites). The deltidium is characteristic of the Protremata,
while a similar plate, the homoeodeltidnim, is developed in some of the Neotremata
and Atremata. This covering of the delthyrium is always present in the young of the
Protremata, but is absent in the Telotremata. In many of the Protremata (Orthidae,
etc.) the deltidium is only present in nepionic stages of the individual, being
resorbed at maturity ; but in the great majority of these forms it remains persistent
throughout life.

Deltidial -piates occur only in the order Telotremata, and consist of two pieces
which begin as narrow, linear, calcareous piates, growing medially from the walls of
the delthyrium, They gradually increase in size, and usually come in contact
medially with one another, either below or above the pedicle foramen, and are
secreted by an extension of the ventral mantle lobe. Thus in respect to their origin
they differ from the deltidium of the Protremata, which is secreted by the pedicle,
and not by the mantle. The deltidial piates are never present in the earliest growth
stages of the shell, the delthyrium being then an open triangulär fissure through
which the pedicle is protruded. In the adult stage the deltidial piates may remain
as narrow, linear discrete piates (Fig. 530, B) ; may meet beneath the pedicle foramen

Fig. 530.

A, Cyclothyris vespertilio (Brocchi), with united deltidial piates. B, Terebratella dorsata (Lam.), with
discrete deltidial piates. C, Young specimen of Stringoce2yhalus bnrtoni (Defr.), with the deltidial piates united
above the foramen.

(Fig. 535, B) ; or they may wholly enclose the pedicle (Fig. 530, A). The deltidial
piates frequently unite l)y fusion, when they closely resemble a true deltidium, and
are known as a pseudodeltidium {Gyrtia, Cyrtina, Fig. 529).

The chüidium is a convex plate which often covers the cardinal process of the

360

MOLLUSCOIDEA

PHYLUM V

dorsal valve in the Protremata. It is particularly well developed in the families
Clitambonitidae and Stropliomenidae (Fig. 585, B). The chilidium is not to be homo-
logised with the deltidium, since it never appears earlier than the adolescent stage,
and is apj)arently a secretion of the dorsal mantle lobe. Both its origin and phyletic
significance are therefore very difterent from those of the deltidium.

The listrium is a plate closing the progressive track of the pedicle opening or
pedicle cleft, in some Neotremata, posterior to the apex of the ventral valve.

Internal Characters of the Shell : Articulation. — The two valves are
held in apposition either by muscles only (Atremata and Neotremata), or they
are united by articulation (Protremata and Telotremata). In the latter case
there are to be seen in the ventral valve a pair of cuneate or tooth-shaped
projections, one on either side of the delthyrium, called the hinge-teeth (Fig.
535, B), which fit into the so-called dental sockets of the dorsal valve. Articu-
lation is also aided by the cardinal process, which is a more or less well-
developed apophysis of the dorsal valve, and is received between the teeth of
the ventral valve. By the contraction of the muscles attached to the
cardinal process, the valves are opened along the anterior and lateral
margins; but when shut, the test entirely encloses the soft parts of the
animal.

The dental sockets are bounded on the inside by hinge-plates (Fig. 535, A),
which are often supported by vertical or inclined septal plates extending to

Fig. 531.

,«,V^'^1n willTfpnHlÄI'lf ^- •^' ^^''^^^rH ' fl^^^y ^™« supported by two simply curved crura. B, Theco-
Th f nnl nf L?ni-i^^^^^'r P/.""'!' ^'^ .T""^^'^- ^' ^^^^ieospim ; and D, Cyrtina ; outwardly coiled spiralia.
E.H, Loops of Brachiopods. E, Centronella ; F, Dielasma ; G, Terebratella ; H, Megathyris.

the bottom of the shell. The teeth of the ventral valve are sometimes
supported by lamellae known as the dental plates. In addition to the dental
plates, which frequently attain considerable size, there may be a median
septum of variable proportions. This may begin beneath the beak of the
valve, and may sometimes extend as far as the anterior margin (Fig. 535, A).
Some forms are also provided with lateral septa (Thecidiidae).

CLASs II BRACHIOPODA 361

Brachial supports. — Of special systematic importance are the brachidia, or
internal skeleton of the fleshy arms (Fig. 531), which occur in the Spiriferacea
and Terebratulacea. The brachidia are, as a rule, prolonged basally from the
crura, and are extremely variable in form. They usually pass through a
more or less complex series of metamorphoses during the growth of the
individual, and do not attain their complete development until the animal has
reached maturity.

The simplest form of brachial supports is found in the Rhynchonellacea and
Pentameracea, where it consists of two short, or only moderately long, curved
processes called the crura when discrete, and cruralium when the plates are
united. The crura are attached to the hinge-plates. The cruralium is
formed by the union ;of the crural plates in the Pentameracea. It serves
for the attachment of muscles, and may either rest upon the bottom of the
valve, or may be supported by a median septum. When the crura remain
separate, and are therefore not for muscular insertion, they are homologous
with and the equivalent of the crura in the Rhynchonellidae.

In the Spiriferacea, two thin, spirally coiled ribbons, or spiralia, are
given off from the crura ; the coils exhibiting great diversity in form, in the
number of volutions, and in the direction of the hollow cones (Fig. 531,
B, C, D). The spiralia are usually joined by a transverse band or jugum
(Fig. 531, D). When the latter is discontinuous, the parts are called the
jugal processes. The bifurcations of the jugum may enter between the con-
volutions of the spiralia, and may be continuous with them to their outer
ends, forming what is termed a double spiral or diplospire (Fig. 531, 5). In
the Terebratulidae, the brachia are also extensions of the crura, and form free,
shorter, or longer loops, which depend toward the anterior margin (Fig. 531,
E, F). The two descending hranches may either unite directly or may be
joined by a transverse band ; or the descending branches may recurve, continue
upward as ascending branches, and be connected posteriorly by a transverse
band. In the Terebratellidae, during all or some portion of the animal's
existence, the loops are attached to a median septum by outgrowths from the
descending lamellae (Fig. 531, 6^). In the Stringocephalidae and Megathyrinae
(Fig. 531, H) the descending branches are parallel to the lateral margins of
the Shell, and unite along the median line ; but in some degenerate species
a remnant of the loop is represented by a transverse band situated centrally
on the median septum. The entire form of the brachidia is manifestly
dependent upon the character of the convolutions of the fleshy arms. In
recent Hemithyris (Fig. 531, A) the brachia form hollow spiral cones, and if
we imagine these as supported by a calcareous framework, the result will be
a form of support like that seen in the Atrypidae. The fleshy arms of the
Terebratellidae are continuous with, and have at first the form of the loop,
but later develop a coiled median arm. Here the loops only have calcareous
supports ; but in the Spiriferacea the entire brachia are provided with an
internal calcareous skeleton.

The changes in the form of the brachidia in the Telotremata during the
ontogenetic stages of the individual furnish very important data in regard
to the relationships existing between the different groups. In the Spiri-
feracea, not only does the number of convolutions of the spirals increase with
age, but the brachidia begin with Centronella- and Dielasma-\\\Q loops, from
the outer ends of which the spires are developed. Still more striking are

362 MOLLUSCOIDEA phylum v

the metamorphoses which the loops of the Terebratulacea undergo. According
to G^hlert and Beecher, the loop of the living austral genus Magellania passes
through stages which correspond successively to those of Gwynia, Argyrotheca,
Boitchardia, Magas, Magasella, Terebratella and Magellania; and Friele has
shown that the metamorphoses of the loop in the boreal form Macandrevia
cranium correspond in succession to the genera Platidia, Ismenia, Miiehlfeldtia,
Terebratalia and Macandrevia.

A knowledge of the character of the brachidia in the Spiriferacea and
Terebratulacea is almost always requisite for critical generic determinations.
But an examination of the interior of the shell in fossil Brachiopods often
involves great difficulties, owing to the infiltration of calcite, or the filling up
of the shell cavity with sediment. Not infrequently the shell and the
brachidia are secondarily replaced by silica ; and if the interior filling matter
be dissolved away by dilute hydrochloric acid, exquisite preparations may be
obtained, often revealing the minutest details. Sometimes hollow shells are
found, in which the brachidia are well preserved, but these structures
generally are more or less encrusted. It is often necessary to remove the
ventral valve, when the infiltrated material can be cut away by the use of
proper tools. Success in manipulations of this kind requires not only con-
siderable dexterity, but the conditions of preservation must have been very
favourable. The brachidia must be perfectly preserved, and the surround-
ing matrix must admit of being removed with out injury to the specimen.
When other expedients fail, recourse can still be had to polishing, the shell
being gradually ground down by abrasion with emery powder on a glass
plate. The beaks are first ground away, until the first traces of the crura
appear; the surface is then cleaned and kept moistened while a careful
drawing is made. Grinding is resumed for a short interval, when the
surface is again cleansed and drawn. This process is repeated until the
sections include the entire brachial support. From the series of transverse
sections thus obtained, the brachidium can be ideally reconstructed.

The spondylium is an internal ventral plate traversing the posterior
portion of the valve (Fig. 585, 0). On the superior surface of the plate are
inserted the adductors, diductors and the ventral pedicle muscles. Beneath
the spondylium, which may be supported by a median septum, are situated
the reproductive organs. The plate is homologous with the solid or excavated
platform of the Atremata (Trimerellidae and Lingulasmatidae).

Soft Parts : ManÜe. — Lining the entire inner surface of the shell is a
thin, transparent membrane, which appears in the embryonic condition as
two distinct lobes of the thoracic segment in the Cephalula stage. This is
the mantle or pallium, which is primarily concerned in the secretion of the
shell. In Crania it consists of three layers : a middle cartilaginous, an inner
ciliated one, and an outer layer of cells. The layer lying against the surface
of the shell is often studded with minute caeca or blind tubes, which enter
the perforations of the test. The mantle (or certain of its layers) is folded
upon itself at various points, enclosing cavities or pallial sinuses, which contain
the circulating fluids, and frequently portions of the genital organs. Distinct
impressions of these sinuses are often observable in the valves of both recent
and fossil specimens (Fig. 532). In all the greater sinuses of the mantle, in
the peri visceral cavity, and in the cavernous brachia and cirri, occur calcareous
spicules of various shapes. These are especially abundant in the Thecidiidae,

CLASS II BRACHIOPODA 363

and form an irregulär mass or network. They appear to be absent in
Magellania, Terebratella and Lingula. The outer margins of the mantle are
thickened and set with numerous chitinous, simple
or barbed setae, sometimes of great length.

The shell cavity is divided by a vertical mem-
branous wall, which is an extension of the mantle,
into two regions : a posterior, or visceral cavity, and
an anterior, or brachial- cavity. The posterior cavity
contains the principal viscera, the alimentary, cir-
culatory, nervous and muscular Systems. The an-
terior Chamber is occupied by the arms.

Organs of the Visceral Cavity. — The membranous fig. 532.

partition is pierced centrally by the oval or slit-like camarophoHa humUetonensis
mouth, from which the digestive tuhe extends back- Enjand. internal mouXshowing
wards as a simple or bent canal. In inarticulate JXr üSsonX ^*"'*^ ^'""^^^
species, the alimentary canal is very long, makes

several convolutions, and terminates in a well-defined anus, situated on one
side of the animal. In the Protremata and Telotremata the digestive tube
is shorter and much simpler than in the Atrernata and Neotremata. The
intestine makes a single convolution and terminates blindly in the living
representatives of these Orders, being surrounded by large hepatic lobes.
In many Paleozoic species it probably did not terminate blindly, since the
intestine passed through the hinge-plate by a central foramen. There is no
heart, circulation being apparently maintained by the cilia lining the vas-
cular sinuses. These sinuses pass into the perivisceral Chambers, and are
developed into vascular dilations at the back of the stomach and elsewhere.
These bodies are not contractile, and their function is unknown. Two
numerously branched vascular trunks diverge from the anterior portion of
the perivisceral Chambers, traversing the mantle in either valve to its
margins, and several others pass over the fleshy brachia for their entire
length. The nervous System consists of a circum-oesophageal ring on which
two supra-oesophageal ganglia are inserted. From the swellings of the
oesophageal ring (notably from that on the lower side), nerve fibres are
given off to the brachia, muscles, pedicle and the two lobes of the mantle.
In adult Brachiopods sense organs are not known with certainty ; but in
the embryos such are believed to be present. So far as is known the
sexes are always separate. The sexual organs in both male and female
are located essentially alike, and have a paired arrangement. Generally
they occupy the main trunks ^of the vascular sinuses, but may extend into
the visceral Chamber, or, in some of the inarticulate forms, may be restricted
to the latter.

The Brachial Cavity. — The greater part of the anterior or brachial cavity
is occupied by the spirally enrolled labial appendages, the so-called arms, or
brachia. These are two in number, one at each side of the mouth, and are
of extremely delicate Constitution (Figs. 533, 534, and 531, ^). The tissue
of which they are composed is essentially cartilaginous, and is traversed by
several circulatory canals as well as by a groove. The' outer edges of the
brachia are fringed with long and movable cirri or tentacles, by means of which
currents are set up that conduct small food particles to the mouth. The
arms are frequently supported by a slender calcareous framework called

364

MOLLUSCOIDEA

PHYLUM V

the brachial supports, or hrachidia, described above. There are no special
respiratory organs, the blood being oxygenated in the inner surface of the

mantle and in the spiral
arms, where it is
brought into close os-
motic relation with the
water.

Muscular System. —
By means of muscles
Brachiopods are en-
abled to open and close
their valves, and to a
Median verticai limited cxtcnt can pro-

FiG. 533.

Liothyrina vitrea
(Liunaeus). Recent.
Fleshy brachia simply
recurved.

Magellania fla

section, slightly enlarged. d, Spiral brachia ; li, fm-^p onri rpfrnpt fVip

Fringed brachial marlin ; pr, Cardinal process ; ^^^^® ^^^ retract tne

^, Alimentary canal ; v, Mouth ; ss, Septum ; a, pediclc. In the articu-

Adductors ; c, c' Diductors (after Davidson). T , c /-r, j

late lorms (rrotremata
and Telotremata) there are three sets of muscles — namely, the diductors,
which by contraction open the valves ; the adduäors, which by contraction
close the valves ; and the pedide muscles, or adjustors, which also by contrac-
tion withdraw the pedicle. The points of attachment of these muscles leave
more or less distinct impressions in the valves of both recent and fossil
Brachiopoda, and the subject is therefore worthy of careful examination.

The adductors, or closing muscles, are attached on either side of the median line
in the dorsal valve, and leave two elongate scars lying immediately to the right and
left of the median line, enclosed between the diductors (Fig. 535, B, a). These
muscles extend almost
directly from one valve
to the other, and as eaeh
muscular band is once
divided, their insertions
on the dorsal valve are
quadruple. Their im-
pressions on this valve are
known as the anterior and
posterior adductors (Fig.
535, A, B, a, a).

The principal diduc-
tors, or opening muscles,
originate on the ventral
valve at the anterior edge
of the visceral area, and ^^^'- ^s^-

.,■■ .1 r. ,-1 Magellania flavescens (Val.). Recent; Australia (after Davidson). A,

on eitner Siae OI tue Dorsal valve. B, Ventral valve. D, Deltidial plates. F, Foramen. S,

median line • the scars of l^ooP« P^> Cardinal process ; x, Hinge-plate ; z, Hinge-teeth ; a, a', Im-

- 1 'i • 11 pressions of adductors ; d, rf', Diductors ; jj, p', Pedicle muscles.

these muscles bemg usually

the largest and deepest of any in the animal. They taper rapidly in crossing the
interior cavity, and their small extremities are attached to the anterior portion of
the cardinal process of the dorsal valve, There are also inserted on the cardinal
process, behind the principal diductors, two mucli smaller muscular bands, which
are called the accessory diductors. Their attachment on the ventral valve is repre-
sented by two feeble scars in the posterior part of the muscular region, but these are
rarely observable in fossil specimens (Fig. 535, A, B, d).

CLARS II

BRACHIOPODA

365

Wlien a fimctional pedicle is present, there are foimd, in addition to the valvulär
muscles, two pairs (one to each valve), and a single impaired muscle ; these are
attaclied to tlie pedicle, and are called the pedicle muscles (Fig. 535, -B,^, 'p'). The pair
in the ventral valve originates immediately outside of and posterior to the adductors
and diductors ; the pair in the dorsal valve is attaclied behind the posterior adductors ;
and the unpaired muscle lies at the base of the pedicle in the ventral valve. Only
the latter unpaired band, as a rule, leaves a perceptible scar in fossil specimens.

The entire muscular System in the Protremata and Telotremata works with the
utmost precision. The cardinal process is received
between the teeth of the ventral valve in such a
manner as to allow the dorsal valve to swing freely
in the median vertical plane as on hinges, and at
the same time prevents motion in a lateral direc-
tion, The diductors, being attached to the cardinal
process, act upon a lever arm when they contract,
thus opening the valves, while the contraction of
the adductors serves to close them (Fig. 534).

In the Atremata and Neotremata the muscles
are arranged differently, and are often more conipli-
cated and numerous, as articulation is almost never
present in these Orders. The greatest complexity is
attained in Lingula (Fig. 536), because these animals,
in addition to the absence of articulation, slide their
valves laterally.

Ontogeny. — The development of Brachio-
pods from the egg to maturity may be divided
into two periods: {a) stages of development from
the egg to that condition in which the animal is sheirwrth'^'pedicie, Srai^'size.' b\
recognisable as possessing some distinctive class JlTLfpre^SjT^^^

Characters ; and {h) from the first Shelled COn- Protractors ; p, Retractors ; o, Pedicle

dition, or protegulum, to maturity and old age.

Fig. 536.

Our knowledge of the earliest embryonic conditions is restricted to Terehratulina^
Liothyrina, Ärgyrotheca and Thecidea. After fertilisation the larvae may remain
attached, and pass their early stages within the parent ; or they may develop cilia
before segmentation, and be set free in the pallial Chamber or in the sea-water. The
free larvae swim by the aid of cilia with a twirling motion. There are five well-
marked stages of development before the
larvae can be definitely recognised as
Brachiopods. These are : (1) The prot-
emhryo, which includes the ovum and its
segmented stages preceding the formation
of a blastula, or primary internal cavity

Fig. 538.
Ärgyrotheca neapolitana (Schacchi). A,

Neo-

Argyrotheca iimpoUtana (Schacchi). Recent.
A, Protembryo; iinsegmented ovum. B, Prot-
embryo; ovum composed of two spheres. C,
Mesenibryo ; blastosphere. 7), Metembryo ; gast-
rula (after Shipley, from Reecher).

embryo; embryoof twosegments. ii, Xeoembryo ;
cephahila, ventral side, showing cephalic, thoracic
and caudal segments, eye-spots, and bundles of
setae. C, Neoembryo ; hiteral view of completed
cephalula stage, sliowing extent of dorsal (rf) and
ventral (c) mantle lobes, and umbrella-like
cephalic segment. {A and B after Kovalevski, G
after Shipley; all reproduced from drawings by
Reecher.)

366

MOLLUSCOIDEA

PHYLUM V

(Fig. 537, Ä, B) ; (2) the mesemhryo, or blastosphere, a multi-segmented larva with an
internal cavity (Fig. 537, G); (3) the metembryo, or gastrula stage (Fig. 537, D); (4)
the neoembryo, or the ciliated Cephalula stage, which consists atjfirst of a cephalic lobe,
bearing eyes in Ärgyrotheca, and a caudal lobe, to which is added later a thoracic
Segment carrying four biindles of setae, while at the same time the dorsal and ventral
sides of the latter segment become extended over the caudal lobe, and are progres-
sively defined as two lobes (Fig. 538) ; (5) the typemhryo, or larval stage, in which
the dorsal and ventral thoracic lobes, or mantle, fold over and enclose the cephalic
lobe (Fig. 539, B). Upon the mantle lobes, either
before or after turning, there is a corneous integument
which develops into the protegulum before the for-
mation of the true shelL The caudal segment be-
comes the pedicle, and may in this stage serve to
attach the larvae to foreign objects, or the pedicle

Ärgyrotheca neapolitana (Schacchi). A, Neoembryo ; completed
cephalula stage. B, Typembryo ; transformed larva resulting from
folding upwards of mantle lobes over cephalic segment ; ad, Muscles
from bundles of setae to sides of body cavity ; di, Muscles from dorsal
to Central sides of body ; vp, Muscles from ventral side of body to
caudal segment or pedicle (after Kovalevski, from Beecher).

Fig. 540.

ArgyrothecaneapoUtana(ßchsiCch.i).
A, Phylembryo ; Brachiopod show-
ing Shell (protegulum), beginning of
tentacles of lophophore (/), obsoles-
cence of eye-spots, and formation
of Oesophagus ; t, Hinge-teeth ; vp,
Ventral pedicle muscles. B, Nepio-
nic Brachiopod, showing distinct
tentacles of lophophore, mouth and
stomach, and transformation of
muscleg from typembryo ; ad, Ad-
ductors ; di, Divaricators ; vjj,
Ventral pedicle muscles (after
Kovalevski, from Beecher).

may remain undeveloped for a time. A rudimentary digestive tract is present, and
also four pairs of muscles, which later become the adductor, diductor and ventral
pedicle muscles.

In the phylembryo, orsixth stage ofdevelopment, the embryonic shell, ov protegulum,

is completed; the tentacular lobes of
the lophophore, or brachia, appear ; the
four bundles of setae are dehisced ; ob-
solescence of the eyes occurs, as well as the
agreement of the muscular system with
that in adult forms (Fig. 540).

The protegulum has been observed by

Fig. 541.

Thecidea (Lacazeiia) mediterranea (Risso). Recent. Beecher in many genera representiuff

A, Dorso- ventral longitudinal section of cephalula; ..r,r,T.Ur oll fl,^ l^o^- -p -t a ^-i

h, Head; d, Dorsal mantle lobe; v, Ventral mantle ^l^^rly all the leadmg families of the

lobe; ds, Beginning of dorsal ya.ive; dei, Shell piate class, and therefore it may be inferred

formmg on dorsal side of body; p, Pedicle. B, Dorso- 4.1, + +t. , . *^ xni-ciicu

ventral longitudinal section of typembryo ; vs. Ventral '^"-^^ tue protegulum IS common tO all

valve; hl, Hinge-line of dorsal valve. C, Adult speci- BmchioDods Tt 1=1 <iPminh^nM'\or> ^1. o^rr.;

men seen from the dorsal side, showing ventral area and -^^f ^^^lopo^S. It IS SemiCllCUlar or semi-

deltidium. (^ and iJ after Kovalevski; C after Beecher.) elliptical in Outline, with a straight or

arcuate hinge-line, and no cardinal area.

The prototype preserving throughout its development the main features of the

CLASS II • BRACHIOPODA 367

protegulum, and showing no separate or distinct stages of growtli, is represented by
tlie genus Paterina (Fig. 543).

So far as observed, the protegulum, or Paterina stage, in tlie Atremata and
Telotremata is followed by tlie Obolella stage of nearly circular outline. After this
stage, specific cliaracters appear, and in tlie open delthyrium of tlie Telotremata there
are usually developed the first rudiments of tbe deltidial plates. In the Protremata,
the Paterina stage is not followed by the Obolella stage, but the wide delthyrium of the
protegulum is at once affected and modified, and develops into the deltidium. In the
Acrotretacea, belonging to the Neotremata, there is often developed a homoeodeltidium,
resulting from secretion by the mantle, and therefore of different origin from the true
deltidium occurring in the Protremata, which is deposited by the pedicle. In the
Discinacea, belonging to the Neotremata, the pedicle opening is an open notch in the
posterior margin of the ventral valve. In derived forms this is progressively closed
posteriorly ; geologically in the phylum, and ontogenetically in the latest derived
genera and species.

Habitat and Distribution. — Brachiopods are usually gregarious in
habit, often growing in Clusters attached to one another. This is not only
true of Recent species, but of Paleozoic forms as well. Brachiopods are
found in all latitudes and at all depths, but are largely shallow-water animals,
for of the living species 71 per cent occur between the strand-line and 100
fathoms. Liothyrino, wyvillii was dredged from the enormous depth of 2945
fathoms. Terebratulina caput-serpentis ranges from a few fathoms to a depth
of 1170 fathoms.

Brachiopods are most abundant in warmer seas, the Japanese province having
twenty-nine species. As a rule, those occurring in cold waters are not found
in warm waters. Lingulids and Discinids are almost restricted to the strand-
lines in warmer waters less than 60 feet deep. Of the thirty-three living
genera, at least 60 per cent have fossil representatives. Lingula and Crania
have lived since the Ordovician ; since the Jurassic, six genera have continued,
since the Miocene one, since the Pliocene seven, and since the Pleistocene three.
Of the 158 living species only 16 per cent occur fossil, and but five are as old
as the Eocene and Miocene. Three genera are confined to the deep sea, and
all of the abyssal forms are usually thin-shelled, brittle and translucent.

Migration of Brachiopods is possible only during the early larval stages,
and then to a very limited extent among the articulate forms. Morse observed
that Terebratulina became attached in a few days, but Müller kept Discinisca
in confinement nearly a month before any became sessile.

Colour. — The shells of most living species are of light or neutral tints,
white or horn-colour. A deep orange-red in radiating bands or in solid tints
colours some species (Terebratulina, Kraussina, etc.) ; light yellows, deep and
light shades of green (Lingula), black in bands (Crania), or masses (Rhynchonella)
embellish these shells. Even among the fossil species traces of faded colour-
marks are occasionally observed ; Deslongchamps has described them among
Jurassic species, Davidson among the Carboniferous, and Kayser has found a
colour-marked Rhynchonella in the Devonian. The large highly ornamented
species of Paleozoic times, with their external sculpture heightened by a
brilliant colouring, must have been objects of exquisite beauty (Hall and
Clarke).

Classification. — The Brachiopoda, since 1858, have been divided by
nearly all systematists into two Orders, based on the presence or absence of

368 MOLLUSCOIDEA phylum v

articulating processes. These divisions, " Articules and Libres," were recog-
nised by Deshayes as early as 1835, but not until twenty-three years later
were the names Lyopomata and Arthropomata given them by Owen. These
terms have been generally adopted by writers, though some prefer Inarticulata
and Articulata Huxley, or Bronn's Ecardines and Testicardines. Bronn (1862)
and King (1873), while retaining these divisions, considered the presence or
absence of an anal opening more important than articulating processes, and
accordingly proposed the terms Pleuropygia and Apygia, and Tretenterata and
CUstenterata respectively. In many Paleozoic rostrate genera of Clistenterata,
it has been shown that an anal opening was also present, and therefore the
absence or presence of this organ is not of ordinal value.

The first attempt to construct a Classification of the Brachiopods was that
of Leopold von Buch, who topk for his principal differential characters the
conformation of the umbonal region, the presence or absence of a pedicle, the
nature of the deltidium, and the external form and ornamentation of the shell.
While his Classification does not reflect a perfect understanding of the features
in question, it is remarkable that von Buch, nearly eighty years ago, and
Deslongchamps, twenty-eight years later, recognised some of the principles
upon which the Classification of the Brachiopoda is now established, as, for
example, the nature of the pedicle opening.

Up to 1846 the general external characters of the Brachiopods served
the majority of authors as the essential basis for generic differentiation. In
that year, however, King pointed out that more fundamental and constant
characters exist in the interior of the shell, a fact which soon came to be
generally recognised, mainly through the voluminous and admirable contribu-
tions of Thomas Davidson.

Waagen in 1883 found it "absolutely necessary " to divide Owen's two
Orders into seven suborders. The basis for these suborders rests on no
underlying principle of general application, and yet five of these divisions are
of permanent value, for each contains an assemblage of characters not common
to the others.

No Classification can be natural and permanent unless based on the history
of the class (chronogenesis) and the ontogeny of the individual. However, as
long as the structure of the early Paleozoic genera remained practically un-
known, and the ontogeny wholly unrevealed, nothing of a permanent nature
could be attempted. In the excellent volume by Hall and Clarke (Palaeontology
of New York, vol. viii., 1892-95), the great majority of the Paleozoic genera
are clearly defined. The ontogenetic study of the Paleozoic species was
initiated in 1891 by Beecher and Clarke, followed by Beechßr, and more
recently by Schuchert ; and their results combined with those derived from
the study of the development of some living species, such as have been
published by Kovalevski, Morse, Shipley, Brooks, (Ehlert, Beecher and
others, confirm the conclusion reached through chronogenesis. Moreover, the
application by Beecher of the law of morphogenesis, as defined by Hyatt,
and the recognition and establishment of certain primary characters have
resulted in the discovery of a fundamental structure of general application for
the Classification of these organisms. It has for its foundation the nature of
the pedicle opening and the stages of shell development. On this basis
Beecher (1891) has divided the class into four Orders: the Atremata, Neo-
trematay Protremata and Telotreiaata.

CLASS II BRACHIOPODA 369

, The nature of the pedicle opening being employed for ordinal divisions,
persistent internal characters of the shell are, as a rule, used for superfamily
purposes. Such are the presence or absence of a spondylium, brachial supports,
etc. Family divisions are based upon a combination of external and internal
generic characters, such as the outer form, nature and position of muscles,
internal plates, etc.

No division, however, has any value unless the group contains forms of
but one phylum, since a phylum or line of descent cannot originate twice.
However, it happens that the same or nearly the same combination of mature
characters is developed along different lines (homoeomorphy) ; and when this
occurs the ontogeny will show it. It is therefore not correct to group different
Stocks under one and the same genus. For instance, the family Terebratellidae
probably divided during early Mesozoic times, one stock drifting into boreal
and another into austral regions. These two Stocks agree structurally in the
earliest shelled condition and also at maturity ; but between these two stages
of development, the austral group (Magellaniinae) passes through a different
series of loop metamorphoses from the boreal one (Dallininae)..

It was by the application of the above-mentioned principles that Schuchert,
in 1893, arranged all the genera of Brachiopoda under the four Orders
instituted by Beecher. Further attention has since been given to this subject
by the same writer, and the arrangement now offered combines the brilliant
results obtained by Charles D. Walcott in his studies of the Cambrian forms
of all lands, and the important work of S. S. ' Buckman, relating to the
Brachiopods of Great Britain.

Order 1. ATRBMATA Beecher.

This Order includes primitive inarticulate, corneous or calcareophosphatic
Brachiopoda, with the pedicle usually emerging freely between the two valves.
Growth takes place mainly around the anterior and lateral margins.
Delthyrium or pedicle aperture originally unmodified, in later genera modified
by homoeodeltidia and pseudochilidia, or by thickened, striated and more or
less furrowed or even cleft vertical cardinal margins, the ventral cleft in most
specialised forms tending to enclose the pedicle and finally to restrict it to
the ventral valve ; when completely restricted the genera are referred to the
Order Neotremata. Specialised forms tend to develop rudimentary articula-
tion or muscle platforms. The three other Orders of Brachiopods have
arisen from the Atremata.

Superfamily 1. RUSTELLACEA Walcott.

Primitive, thicJc-shelled, corneous or calcareo-phosphatic Atremata, developing more
or less of homoeodeltidia and pseudochilidia. Muscle scars and vascular sinuses as a
rule not well defiiied in the shell. Out of this stock arose the Oholacea and Kutor-
ginacea. Cambrian and Ordovician.

Family 1. Rustellidae Walcott.

Primitive Rustellacea with the pedicle aperture of hoth valves small, more or less
open, and not much modified by homoeodeltidia or pseudochilidia. Muscle scars and
vascular^ sinuses not well defined in the shell. Lower Cambrian.

VOL. I 2 B

370

MOLLUSCOIDEA

THYLUM V

liustella Walcott (Fig. 542). The most primitive known Brachiopod.
Lower Cambrian ; Vermont.

Family 2. Paterinidae Schuchert.

Progressive Rustellacea with the pedide aperture more or less closed hj
homoeodeltidia and pseudochilidia. Cambrian.

Paterina Beecher (Fig. 543). Surface concentrically ornamented.

Fig. 542.

Rustella edsoni Walcott. Lower Cam-
brian ; Vermont. A, Ventral valve sliow-
ing pedicle furrow (j))- B, Cardinal
View showing tlie open and unmodified
pedicle opening. i/i (after Walcott).

>^-^,

U

9

Fig. ,543.

Paterina superha Walcott. Middle Cambrian ; Vermont.
A-C, Views of the ventral valve showing the large convex
homoeodeltidium. D, Exterior of dorsal valve. '■^/.^ (after
Walcott).

Subgenera : Micromitra Meek; and Iphidella Walcott (Iphidea Billings 1872, non
Baly 1865). Shell in the former more or less ornamented by crenulated
concentric lines, while the latter has diagonally intersecting rows of pits.
Lower and Middle Cambrian ; North America.

Volhorthia von Möller. A globose form of Paterina, with well-developed
pseudodeltidia. Ordovician ; Esthonia.

Mickwitzia Schmidt. Very large round forms with more or less ornate
exteriors. Lower Cambrian ; Esthonia, Sweden, America. Causea Wiman
is regarded by Walcott as probably identical with Mickwitzia, Lower
Cambrian ; Sw^eden.

Superfamily 2. KÜTORGINACEA Walcott and Schuchert.

Progressive, thick-sheUed, almost calcareous atrematous-like shells, tending to he
transverse and developing rudimentary articulation, more or less rudimentary cardinal
areas, homoeodeltidia and muscle scars prophetic of the Protremata. Derived out of
Rustellacea. Cambrian.

Family 1. Schuchertinidae Walcott.

Primitive round Kutorginacea with small cardinal areas. Externally like Obolus,
with an open subtriangular delthyrium which apparently is without a homoeodeltidium.
Muscle scars and vascular markings prophetic of the Billingsellidae of the Protremata,
Cambrian.

Schuchertina Walcott (Fig. 544). Middle Cambrian ; Montana.

Family 2. Kutorginidae Schuchert.
Progressive transverse Kutorginacea with rudimentary cardinal areas, great

CLAss II BRACHIOPODA 37 1

delthyrial opening, rudimentary articulation and immature homoeodeltidia. Muscle
scars prophetic of the Strophomenacea of the Protremata. Cambrian.

A B

l'Ki. '.J44.

Fig. 545.

^, , , ,. , . w , .. ,r-,j, ^ Kutonßna cAngulatuBm. Lo wer Cambrian ; Vermont.

bckuchertina amhna Walcott. Middle Cambrian ; A, Interior of ventral valve. B, Siele view of conjoined

near Neihart, Montana. ^, Interior of ventral valve. valves. C, Interior of dorsal valve; h, Central scars-

L, Interior of dorsal valve (after Walcott). j, Anterior lateral scar ; s, Median septum (after Walcott).

Kutorgina Billings (Fig. 545). Lower Cambrian; North America and
Sardinia.

Superfamily 3. OBOLACEA Schuchert.

Derived in Eustellacea. Progressive, thick-shelled, calcareo-phosphatic or corneous
Atremata without homoeodeltidia or pseudochilidia. . Bounded or linguloid in outline,
more or less lens-shaped, and fixed hy a short pedicle throughout life to extraneous
objeds. Cambrian to Silurian.

Family 1. Ourticiidae Walcott and Scbuchert.

Primitive Obolacea with well-deßned pedicle aperture common to both valves.
Interior characters mucli as in Obolidae. Middle Cambrian.

Curticia Walcott. Middle Cambrian ; Wisconsin and Minnesota.

Family 2. Obolidae King.

Derived, progressive Obolacea with thicJcened, striated, vertical cardinal areas
traversed by pedicle grooves. Muscles and vascular trunks strongly impressed in the
valves. Cambrian and Ordovician.

Subfamily A. Obolinae; Dali.

Primitive Obolidae with the pedicle grooves more or less shallow oi' deeply rounded,
but never tending to form a sheath or to restrict the pedicle opening entirely to the
ventral valve. The most abundant Brachiopods of the Cambrian, vanishing
with the Ordovician.

Obolus Eidhwald ( Ungula Pander ; Ungulites Bronn ; Euobolus Mickwitz)
(Fig. 546). More or less rounded Obolids. Widely distributed in Europe
and America. The following subgenera are recognised by Walcott : Broeggeria
Walcott, Upper Cambrian, England; Mickwitzella Walcott (Thysanotus Mickwitz,
non Alt. 1860), Ordovician, Esthonia; Acritis Volborth (Aulonotreta Kutorga
1848, errdre 1847), Ordovician, Esthonia; Schmidtia Volborth, Ordovician,
Esthonia ; Palaeobolus Matthew, Cambrian, eastern Canada ; Fordinia Walcott,
Middle Cambrian, Utah ; Lingulobolus Matthew {Sphaerobolus Matthew),
Upper Cambrian, eastern Canada ; Westonia Walcott (has transversa parallel
ornamentation), Middle Cambrian, Wyoming, Utah and Idaho.

372

MOLLUSCOIDEA

PHYLÜM V

Helmersenia Paiider. Yery small Obolids with a pustulose or spiny
surface. Lower Ordovician ; Esthonia.

Lingulella Salter (Eooholus Matthew) (Fig. 547). More or less elongate
Obolids. Widely distributed throughout the world. The following are
subgenera: Leptemholon Mickwitz, a.nd Lingulepis
Hall (decidedly elongate Obolids). '"^Jk P

j

„ . -, . . . ;_-_. . p"^

c

Fig. 546.

O&oZtts ma^MiaZis Hall. Middle Cambrian ; Minnesota. J, Ex-
terior of ventral valve. B, Interior of saine. C, Interior of
dorsal valve ; a, Filling of pedicle furrow ; c, Areaof outside lateral
scars ; Ä, Central scars ; i, Transmedian lateral scars ; j, Anterior
lateral scars ; ps, Parietal band ; v, Area of visceral cavity ; vs,
Vascular sinus with outside and inside vascular branches (after
Walcott).

Fig. 547.

Lingulella acutangulus (Roemer).
Upper Cambrian ; Texas. A, Interior of
ventral valve. />', Interior of dorsal
valve ; g, Umbonal scar ; h, Central scar ;
i, Transmedian lateral scar ; j, Anterior
lateral scars ; l, Outside lateral scars ; p,
Pedicle furrow ; ps, Parietal band ; pvs,
Vascular branches ; s, Median septum ;
X, Cordiform cavity; z, Vascular
branches (after Walcott).

Delgadella Walcott. Has thickened internal margins. Lower Cambrian
of Portugal.

Leptoholus Hall. Yery small Lingulellids of the Ordovician of North
America, in which the interiors are marked by two or three diverging,
slightly elevated septa, which occasionally are somewhat bifurcated terminally.

Paterula Barrande (Cydus Barrande, non de Koninck 1841). Closely related
to Leptoholus, but the inner margins of the valves are thickened. Ordovician ;
Bohemia and North America.

(?) Spondylobolus M'Coy. Generic characters not well known. Ordovician ;
Ireland.

Subfamily B. Neobolinae Walcott and Schuchert.

Progressive OboUdae with posterior platforms, to which were prohably attached the
central, outside and middle lateral muscles. Seems to have arisen in thick-shelled
Middle Camhrian Obolus, and is transitional to the platform-bearing Trimerellids.
Middle Cambrian.

Neobolus Waagen {Lakhmina (Ehlert, and Davidsonella Waagen, non Mun.-
Chalmas 1880). Middle Cambrian of India.

Fk;

Elkania desiderata (Bill.). Upper
Cambrian; Quebec. J^, Interior of ven-
tral valve. B, Interior of dorsal valve ;
Ji, Central scars ; i, Transmedian lateral
scars ; j, Anterior lateral scars ; v, Pos-
terior lateral scars ; p, Platform with
muscle scars ; x, Vascular areas in front
of platform (after Walcott).

Subfamily C. Elkaniinae Walcott and Schuchert.

Divergent OboUdae with posterior or marginal
platforms, to which were attached the central, outside
and middle lateral muscles. Not in lineof develop-
ment to Trimerellids. Cambrian.

Elkania Ford {Billingsia Ford 1886, non de
Koninck 1876) (Fig. 548). Cambrian; North
America.

CLASft II BRACHIOPODA 373

Subfamily D. Biciinae Walcott and Schuchert.

Progressive Obolidae with the pedicle restrided to the ventral valve and more or
less endosed by a pedide tuhe. Articulation rudimentary. Out of ihis stock have
arisen the Oholellidae of the Neotremata. Cambrian.

Bida Walcott. Lower Cambrian of Quebec and New York. Dicellomus
Hall. Middle Cambrian of North America.

Family 3. Trimerellidae Davidson and King.

Large, thick-shelled, inequivalved Obolacea, with the ventral cardinal area usually
very prominent, triangulär and transversely striated. Adjnstor and anterior addudor
musdes elevated upon solid or excavated platforms. Ordovician and Silurian.

Dinobolus Hall (Conradia Hall ; Obolellina Billings). Cardinal area not so
prominent as in the other genera of this family. Platform small, with abruptly
conical vaults. Ordovician and Silurian ; North America, Great Britain,
Bohemia, Gotland and Esthonia.

Monomerella Billings. Similar to Trimerella, with well-developed platforms
in both valves ; that of the dorsal valve, however, but slightly excavated.
Silurian ; North America, Gotland and Livonia.

Trimerella Billings (Gotlandia Dali) (Fig. 549). Platforms long, narrow.

Fio. 549.
TriTnerella Undstroemi (Dali). Silurian ; Gotland, 1/2- ^. Shell seen from the dorsal side. B, C, Interior
of dorsal and ventral valves respectively. D, Internal mould. (A and B after Davidson ; C and D after

Lind ström,)

well developed and doubly vaulted. Dorsal beak often thickened into a
prominent apophysis extending against the cardinal slope of the ventral valve.
Silurian ; North America, Gotland and Faröe.
Bhinobolus Hall. Silurian ; North America.

Superfamily 4. LINGULACEA Waagen.

Elongate, thin-shelled, corneous, burrowing Atremata, derived out of Obolinue,
with a more or less long, worm-like, tubulär, flexible pedide. Ordovician to Recent.

Family 1. Lingulidae Gray.

Attenuate, sub-quadrate or spatulate, almost equivalved Lingulacea, with a more
or less long, tubulär, flexible pedide. Musdes highly differentiated and consisting of

374

MOLLUSCOIDEA

PHYLUM V

six pairs, two of addudors, and four of sliders or adjustors. Ordovician to
Recent. Maximum development in Ordovician, declining after Devonian time.

Pseudolingula Mickwitz. Has a ventral pedicle groove and a pair of
umbonal muscles. Ordovician and Silurian ; Europe and America.

Lingula Bruguiere (PAare^ra Bolton ; Lingularius Dumeril); (subgen. (r/ossma

Phill.) (Figs. 550, 551). Shell thin, usually
compressed, glistening, generally smooth, or
with fine, concentric, more rarely with both
concentric and radial Striae ; broad over the
pallial region, tapering more or less toward the
beaks. Ordovician to Recent. Maximum
development in Silurian and Devonian.

Glottidia Dali. Like the preceding, but

interior of ventral valve with two septal ridges

diverging from the beaks. Dorsal valve with

a Single median ridge. Recent; American seas.

Dignomia Hall. Both valves with median

septal ridges ; that of the

dorsal valve stronger, and

flanked by two submarginal

diverging ridges, which cor-

respond in position to grooves

in the ventral valve. Middle

Devonian ; North America.

Barroisella Hall andClarke.

Silurian and Devonian ; North

Lingula anatina Brug. Recent. A, Shell
with pedicle. B, Interior of ventral valve.

551.

Lingula lewisii Sow.
Sihman ; Gotland.

Lingulids with rudimentary articulation.
America ; (?) Bohemia.

Thomasina Hall and Clarke. Lingulids with the posterior margin of the
ventral valve notched, and with two conspicuous articulating processes.
Silurian ; France.

Lingulipora Girty. Lingulids with a punctate shell. Devonian and
Lower Carboniferous ; North America.

Family 2. Lingulasmatidae Winchell and Schuchert.

Platform-hearing Lingulacea derived through Lingulidae. Ordovician and
Silurian.

Lingulops Hall. Small Lingulids with narrow, depressed, not excavated
platforms. Ordovician and Silurian ; North and South America.

Lingulasma Ulrich (Lingulelasma Miller). Large thick-shelled Lingulids
with very prominent, slightly excavated platforms. Ordovician ; North
America ; (?) England.

Order 2. NEOTREMATA Beecher.

Derived and specialised inarticulate Brachiopoda, probably developed
through Biciinae of the Atremata. Shells as a rule more corneous than
calcareous, more or less cone-shaped, with the pedicle emerging through a
Perforation or sheath in the ventral valve, or through a triangulär more or

CLASö II BRACHIOPODA 375

less open cleft during life, or only so in the youngest shelled stages, after
which the ventral valve may become cemented to foreign objects. Pedicle in
geologically younger forms often modified by a listrium. Homoeodeltidia and
pseudochilidia as a rule not well developed.

Superfamily 1. SIPHONOTRETACEA Walcott and Schuchert.

Primitive, thicJc-shelled, calcareous or corneous, obolid-like Neotremata, with the
pedicle passing through a ventral sheath, the aperture of which may remain apical
and circular in outline and posterior to the protegulum, or may become elongate
through resorption by passing anteriorly through the 'protegulum and umbo of the
shell. Ä listrium is not developed. Dorsal protegulum marginal. Cambrian to
Silurian.

Family 1. Obolellidae Walcott and Schuchert.

Primitive Siphonotretacea with the pedicle emerging through a small circular
Perforation in the apex of the ventral valve posterior to the protegulum. Derived out
of atrematous Biciinae. Cambrian.

Obolella Billings (Fig. 552). Small, oval or round, thick shells resembling
Obolids but with a pedicle tube instead of an open furrow. Lower Cambrian
of North America and Sweden. The subgenus Glyptias Walcott, has trans-
verse parallel surface sculpturing. Lower Cambrian ; Sweden.

i '^> : A-

Fig. 552.

Obolella atlantica Walcott. Lower
Cambrian ; Canada. A, Ventral valve ^
showing vascular sinuses and fiUiug of „ re«

pedicle foramen (/)). B, Side view of * '"• ^"'*-

same. (', Dorsal interior showing the A-C, Sijihonotreta verrucosa Vern. Middle Ordovician ;

striated cardinal area(a)and moulds of Esthonia. D, S. ungtdculataEichw., showing the internal

the lateral scars (i) (after Walcott). opening of the pedicle aperture (after Walcott).

Botsfordia Matthew (Mobergia Redlich). Like Obolella but with a highly
Ornate papillose surface. Cambrian ; North America.

Schizopholis Waagen. Middle Cambrian of India. (?) Quebecia Walcott.
Lower Cambrian of eastern Canada.

Family 2. Siphonotretidae Kiitorga.

Progressive Siphonotretacea with the circular or elongate pedicle opening at the
apex or passing by resorption anteriorly through the protegulum aiul umbo of the
shell. Cambrian.

Siphonotreta de Verneuil (Fig. 553). Large and elongate forms in. which
the pedicle sheath is long and well developed, external aperture small and
circular. External surface with hollow spines, though rarely preserved ;
shell substance punctured by radiating and branching tubules. Ordovician
und Silurian ; Europe and (?) North America.

376

MOLLUSCOIDEA

PHYLÜM V

Schizambon Walcott (Schizamhonia Q^hlert). Small spiniferous Siphono-
tretids with much of the pedicle sheath open as a cleft on the outside.
Upper Cambrian and Ordovician ; America and Russia.

Trematobolus Matthew {ProtosipJion Matthew). With rudimentary articu-
lation and lamellose exterior. Lower and Middle Cambrian ; California and
New Brunswick.

Yorkia Walcott. The oldest form of the family. Concentrically striated
exterior. Lower Cambrian of eastern North America. Dearhornia Walcott.
Middle Cambrian ; Montana.

Keyserlingia Pander. Thick-shelled form with decided muscular impres-
sions and median septa in both valves. Lower Ordovician ; Esthonia.

Superfamily 2. ACROTRETACEA Schuchert.

Progressive Neotremata with corneous or calcareo-corneous shells that are more or
less circular in outline and from highly conical to depressed in form. The pedicle
opening is a simple, circular, more or less conspicuous Perforation through the apex
of the ventral valve, and is situated posterior to the protegulum. A listrium is not
developed. A false cardinal area is often present. Dorsal protegulum 7tiarginal.
Cambrian to Silurian.

Family 1. Acrotretidae Schuchert.

Same characters as superfamily. The large and depressed forms are of the
suhfamily Acrothelinae, white the small forms with more or less high ventral valves
are of the Acrotretinae. Cambrian to Silurian.

Suhfamily A. Acrothelinae Walcott and Schuchert.

Acrothele Linnarsson (Fig. 554).
cl

Cambrian ; North America and Europe.
Subgenus : Redlichella Walcott.
> Middle Cambrian ; Sweden.

Discinolepis Waagen. Middle
Cambrian ; India.

Fig. 554.

Acrothele {Redlichella) granulata (Linnarsson). Middle Cam-
brian ; Sweden. A, Ventral valve with its minute pedicle foramen.
B, Dorsal exterior. C, Acrothele matthewi (Hartt), showing vas-
cular Sinus (vs). Middle Cambrian ; New Brunswick (after
Walcott).

A

Suhfamily B. Acrotretinae
Matthew.

B

V5.

3 ^•f\^§

A false cardinal area often
present.

Acrotreta Kutorga (Linnars-
sonia C. D. Walcott) (Fig. 555).
Widely distributed throughout
the Cambrian and rarely in
the Ordovician of Europe and
North America.

Acrothyra Matthew. Ven-
tral valve often excessively
high and oblique or elongate in outline. Middle Cambrian ; New Brunswick.
Conotreta Walcott. Highly conical shells with the ventral interior marked
by a number of radiating ridges. Ordovician and Silurian ; North America.

Fig. 555.

A-C, Acrotreta schmalensii Walcott. Middle Cambrian ;
Sweden. A, Three views of the ventral exterior, B, Ventral
interior with vascular sinus (vs). C, Dorsal interior. D, E,
Acrotreta subconica Kutorga. Ordovician ; Esthonia. Cardinal
view and dorsal valve (after Walcott).

CLASs 11 BRACHIOPODA 377

Linnarssonella Walcott. Middle Cambrian ; North America.

Discinopsis Matthew. Has marked ventral vascular sinuses. Middle
Cambrian ; New Brunswick.

(?) Mesotreta Kutorga. Ventral valve spinöse. Basal Ordovician ;
Esthonia.

Superfamily 3. DISCINACEA Waagen.

Specialised Neotremata with phosphatic shells^ a listrium modifying the pedicle
slit, and without pseudodeltidia and false cardinal areas. Dorsal protegulum
usually subcentral. Ordovician to Recent.

Family 1. Trematidae Schiichert.

Primitive Discinacea, in which the posterior margin of the ventral valve has a
triangulär pedicle notch throughout life. A listrium is usually present. Ordovician
to Coal Measures.

Trematis Sharpe {Orhicella d'Orb. 1847, non Dana 1846). Ventral valve
unevenly convex, more or less depressed over the posterior region. Pedicle
fissure large, extending from the apex to the posterior margin. Dorsal valve
evenly convex, and sometimes with incurved beak ; posterior margin much
thickened, and broadly grooved for the passage of the pedicle. Surface of
both valves covered with punctures or small pittings arranged either in
quincunx or in radiating rows. Ordovician and (?) Silurian ; North America
and (?) Europe.

Eunoa Clarke. Very large, depressed, thin shells, with fine concentric
lines. Pedicle notch very large. Ordovician ; New York.

Schizocrania Hall and Whitfield. Ventral valve flat or concave, smaller
than the dorsal, and bearing a deep and very broad triangulär pedicle notch,
which extends from just behind the beak to the posterior margin. Apex of
notch occupied by a triangulär plate or listrium. Surface marked by
concentric growth lines ; no muscular impressions visible on the interior.
Dorsal valve more or less convex, with beak marginal. External surface
radially striated. On the interior, a low median ridge extends from the apex
to beyond the centre of the valve ; posterior adductor muscles strong ; the
anterior ones faint. Ordovician to Devonian ; North America.

Lingulodiscina Whitfield (Oehlertella Hall and Clarke). Much like Schizo-
crania^ but the ventral valve has concentric growth lines, and no radiating
Striae. Ventral pedicle area greatly elevated and transected by a narrow
open fissure. Devonian to Lower Carboniferous ; North America.

Schizobolus Ulrich. Devonian; North America. (?) Monoholina Salter.
May be an Obolid.

Family 2. Discinidae Gray.

Derived Discinacea with an open pedicle notch, in early life, in the posterior
margin of the ventral valve, which is closed posteriorly during neanic growth, leaving
a more or less long, narrow slit, partially closed by the listrium. Ordovician to
Recent.

Orbiculoidea d'Orbigny (Fig. 556). Shells inequivalved, sub-circular or
sub-elliptical in outline. Apices eccentric. Ventral valve deperssed, convex

378

MOLLUSCOIDEA

PHYLUM V

Fig. 556.

A, OrUculoidca circe Bill. Ordovician; Belle'
ville, Canada. Ventral valve, Vi (after Billings).
B, 0. nitida Phill " -

souri

or flattened. Dorsal valve larger, usually depressed conical. Pedicle furrow
B originating behind the apex, extending

over a greater or lesser portion of the
radius of the valve, and prodiiced at the
distal end into a short tubulär sipho, emerg-
ing on the interior surface near the posterior
margiii. Surface with fine, crowded or dis-
tant, rarely lamellose, concentric lines,
occasionally crossed by radiating lines.
Ordovician to Cretaceous; North and South
America, Europe, and probably elsewhere.
Discina Lamarck. Very much like
Do™-' 2/,^vertra?vXM/r' ' ^''' Ofbiculoidea, but the pedicle emerges through

the ventral valve antero-posteriorly, im-
mediately beneath the beak, instead of through a sipho postero-anteriorly as
in that genus. Recent.

Until recently Discina embraced all fossil Discinoid shells, but at present
this genus seems to be restricted to a single species,
D. striata, living off Cape Palmas, West Africa.

Discinisca Dali (Fig. 557). Like Orbiculoidea,
but with a small septum, as in Discina, behind
which is an impressed area, externally concave and
internally elevated. This is perforated by a longi-
tudinal fissure, extending from a short distance
behind the septum nearly to the posterior margin. ^.^l^;,^^
Tertiary to Recent ; North America and Europe.

Pelagodiscus Dali. Like Discinisca, but the brachia are without spirals
Recent ; deep oceans.

Schizotreta Kutorga. Ordovician and Silurian ; Russia and North America
Lindstroemella and Boemerella Hall and Clarke, are genera related to Orhi
culoidea. Devonian ; North America.

Fig. 557.

Discinisca lamellosa (Brod.). Recent ;
A, Side-view. B, Interior of
valve. C, Exterior of same.

Superfamily 4. CRANIACEA Waagen.

Specialised, cemented calcareous Neotremata without pedicle or anal openings at
maturity. Pedicle functional probably only during nepionic growtli. Ordovician
to Recent.

Family 1. Oraniidae King.

Crania Retzius. Shell inequivalve, sub-circular in outline. The interior
of both valves shows two pairs of large adductor scars, the posterior
of vi^hich are widely separated and often strongly elevated on a central
callosity. Impressions of the pallial genital canals coarsely digitate. Ordo-
vician to Recent ; maximum development in Ordovician and Cretaceous.

Pseudometoptoma von Huene. Very large thick-shelled forms with high
dorsal valves. Ordovician ; Esthonia.

Philhedra Koken. Ordovician ; Europe and America.

Petrocrania Raymond (Craniella Gi^hlert 1888, no?i Schmidt 1870). Large
Craniids with S-shaped vascular impressions. (?) Ordovician and Devonian ;
North America and Europe.

CLASS II

BRACHIOPODA

379

Eleutlierocrania von Huene. Biconvex Craniids related to Petrocrania.
Ordovician ; Esthonia.

A B V

Fig. 558.

Craniscus velatus (Quenst. ).
Upper Jura; Oerlinger
Thal, Würteniberg. Interior
of ventral valve, Vi (after
Quenstedt).

Fig. 559.

Ancistr<}crania parisiensis (Defr.). Upper Cretaceous ; France.
A, Prottle of dorsal valve. B, Interior of same. C, Interior of ven-
tral valve, i/j.

Craniscus Dali (Fig. 558). Ventral interior divided by septa into three
cavities. Jurassic ; Europe.

Ancistrocrania Dali (Fig. 559). Dorsal valve with two muscular fulcra.

Fig. 560.

Isocrania igfiabergensis (Retzius). Uppermost Cretaceous ; Ignaberga, Scania. A, Profile and dorsal aspect
of Shell, i/j. B, C, Interior of ventral valve. D, Interior of dorsal valve, enlarged.

Cretaceous ; Europe. Isocrania Jaekel (Fig. 560). Exterior plicate.
Cretaceous ; Europe.

Fholidops Hall (Craniops Hall). Biconvex and but slightly attached
Craniids. Ordovician to Carboniferous ; North America, England, Gotland.

Fseudocrania M'Coy (Palaeocrania Quenstedt). Radially striated shells
much lik'e Fholidops. Ordovician ; Europe.

Cardinocrania Waagen. Permian of India.

Order 3. PROTRBMATA Beecher.

Specialised (through atrematous Kutorginacea), articulate, calcareous
Brachiopoda, with well-developed cardinal areas. Exterior surface nearly
always either plicate, striate or spinous, and but rarely smooth. Pedicle
aperture restricted to the ventral valve throughout life and more or less
closed by a deltidium ; in some forms the pedicle is functional only in early
life and later the animals cement the ventral valve to foreign bodies. Chilidium,
spondylium and cruralium often present. Brachia unsupported by a calcareous
skeleton other than short crura.

Superfamily 1. ORTHACEA Walcott and Schuchert.

Progressive Frotreinata. The older gener a have immature spondylia that are
rarely freely suspended but are conimonly cemented directly to the valves ( = pseudo-
spondylia). In the great majority of the later gener a all traces of spondylia are lost.

380 MOLLUSCOIDEA phylum v

In earlyforms thepedide aperture is usually covered hy deltidia and chilidia, but in most
later fonns these plates are lost. Fedicle always fundional and in the great majority
of forms emerges freely out of the delthyrium. Cardinal process more or less well
developed except in the most primitive genera. Ä prolific stock of Brachiopods.
Throughout Paleozoic.

Family 1. Billingsellidae Scliucliert.

Primitive Orthacea with a more or less dosed, or an open delthyrium. A
Cardinal process arises in this family and is therefore either absent, rudimentary or
well developed. Ä spondylium is usually developed and to its upper surface are
attached the muscles of the ventral valve. Cruralia rudimentary. Shell strudure
dense, granulär, lamellar, rarely fibrous, apparently irregularly pundate in some
forms. Cambrian.

Siibfamily A. Nisusiinae Walcott and Scliiichert.

Primitive Billingsellidae with more or less well -developed deltidia and with or
without rudimentary chilidia. Spondylia and cruralia rudimentary or small, not
supported by septa. Cardinal process generally absent, but rudimentary when present.

Nisusia Walcott, and subgenus Jamesella Walcott. Distinctly plicate
Billingsellidae without cardinal process. Deltidium well developed with an
apical pedicle foramen. The genus has a spiniferous exterior while the sub-
genus is devoid of spines. Lower and Middle Cambrian of America and
Europe.

Protorthis Hall and Clarke. Has a spondylium, but the deltidium is widely
open for the protrusion of the pedicle. Shell substance apparently punctate.
Middle and Upper Cambrian of America and Sweden. The subgenus Loperia
Walcott, difFers in having the ventral umbo high and convex while the rest
of the Shell is concave. Middle Cambrian ; Cape Breton, Nova Scotia.

Subfamily B. Billingsellinae Walcott and Schucliert.

Primitive Billingsellidae very much like the Nisusiinae, but without true spondylia
(i.e. pseudospondylia are often present) and cruralia. There is a more or less well-
simple cardinal process except in Lower Cambrian forms.

Billingsella Hall and Clarke (Fig. 561). Shells essentially orthoid, plicate,

biconvex or planoconvex, and prob-
ably punctate. Deltidia well de-
veloped, but chilidia only partially
so; the pedicle may emerge be-
tween these plates or pass apically
through the deltidium. Common
and widely distributed throughout
the Cambrian of America, Europe

Billingsella coloradoensis (Shumard). Middle Cambrian ; i pti • , i i • , •

Texas. A, Ventral exterior. B, Ventral interior. C, Dorsal ^-UQ Uniua ; tnc gCnUS Qies OUt in

interior. c, Crural bases ; d, Deltidium; j, Cardinal pro- fV,p T.n-«7-pr OrrlnviVinn TVip emh-

cess ;«, Teeth ; vs, Vascular sinuses (after Walcott). tne l^OWer UrüOVlCian. lue SUD

genus Otusia Walcott, has small
eared forms without deltidia and with a well- developed cardinal process.
Upper Cambrian ; North America.

Fin. 561.

CLASS II

BRACHIOPODA

381

Wimanella AValcott. Like Billingsella but more primitive in that the
exterior is smooth. Lower Cambrian ; North America. Wynnia Walcott.
Middle Cambrian ; India.

Siibfamily C. Eoorthinae Walcott.

Derived Billingsellidae in which the delthyria are nearly always vndely open as
in Orthids ; deltidia and chilidia sometimes retained throughout life, hut more often
only in the younger growth stages. Spondylia ahsent. Cardinal process well
developed. Differ from the Orthidae mainly in that the shell structure is dense,
granulär, and with irregularly pundate lamellae.

Eoorthis Walcott. Very much like Pledorthis, but the shell is thinner
and its structure not fibrous. Middle Cambrian and Lower Ordovician, but
essentially of Upper Cambrian time ; North America, China, Argentina and
north Europe. . Subgenus Orusia Walcott, typified by Orthis lenticularis
Wahlenberg. Upper Cambrian of north-western Europe and New Brunswick.
Subgenus Fhikelnhurgia Walcott, has thick shells with strongly-marked ventral
vascular trunks. Upper Cambrian ; North America.

Family 2. Orthidae Wood ward.

Progressive, divergent and terminal Orthacea, derived out of the Eoorthinae,
nearly always with large open delthyria. Cardinal process well developed. Shell
structure fibrous, impunctate or punctate. Ventral muscle area small, obovate or
obcordate ; adductors extending to anterior margin of area. Ordovician to Permian.

Subfamily A. Orthinae Waagen (emend,).
Orthidae with the shell impunctate.

Orthis Dalman (s. str.) (Orthambonites Pander). Typified by 0. callactis
Dalman, or 0. tricenaria Conrad. Shells plano-convex ; costae strong, few,
generally sharp and but rarely bifurcating. Cardinal process a thin vertical
plate. There may be a flat apical deltidium. Plications often with large
oblique tubules penetrating the external layers. Ordovician and Silurian ;
Europe, North America, etc.

Plectorthis Hall and Clarke. Valves subequally convex. Ventral cardinal
area low. Plications strong, simple or duplicate. Ordovician and Silurian ;
North America and Europe. a b

The following are Ordo-
vician subgenera : Austin-
ella, Eridorthis, and Encu-
clodema Foerste (Cyclocoelia
Foerste, non Duj.).

Platystrophia King (Fig.
562). Contour spiriferoid ;
hinge-line long with dorsal
and ventral cardinal areas
equally developed. Strong, sharp plications with the exterior surface finely
granulöse. Ordovician and Silurian ; Europe and America.

Hebertella Hall and Clarke. Shells with convexity of valves reversed.

Platystrophia lynx (Eichw.).

Fio. 562.
Ordovician ; Cinciunati, Ohio. i/i.

382 MOLLUSGOIDEA phylum v

Exterior finely plicate, crossed by lamellose growth lines. Ventral muscular
area short, obcordate. Cardinal process well developed, often crenulate.
Ordovician ; America and Europe.

Orthostrophia Hall. Exterior like Hehertella. Muscular area of both
valves short, deeply excavate, with the vascular and ovarian markings
conspicuous. Silurian and Lower Devonian ; North America. Subgenus :

Schizoramma Foerste (Schizonema Foerste, non Agardh.).

Silurian ; North America.

Subfamily B. Dalmanelltnae, novum.
Orthidae with the shell ahundantly pundate.
^^•'•^^^- Dalmanella Hall and Clarke (Fig. 563). Widely

Silurian ; Gotiand. i/i- distributed in the ürdovician and öilurian, but persist-

ing to the end of the Devonian.
Thiemella Williams. Upper Devonian ; North America.

Family 3. RhipidomelÜdae, novum.

Progressive, divergent and terminal Orihacea with the external charaders of the
Orthidae, Shell strudure fibrous, impundate or pundate. Ventral muscular area
large, hilohed or elliptical ; addudors relatively small, and more or less completely
enclosed anteriorly by the flabellafe didudors. Ordovician to Upper Carbonif erous.

Subfamily A. Plaesiomiinae, novum.
Rhipidomellidae with the shell ii

Plaesiomys Hall and Clarke. Relative convexity of valves reversed.
Surface finely plicate and sometimes tubulose. Cardinal process thickened
and crenulate. Ventral muscular scars large and often bilobed. Ordovician ;
America and Europe. Subgenus : Dinorthis Hall and Clarke. Surface strongly
plicate ; there may be a small deltidium. Ordovician ; North America.
Subgenus : Valcourea Raymond. Near Plaesiomys but strophomenoid in external
expression. Lower Ordovician ; North America.

Pionodema Foerste (Bathycoelia Foerste, non Am. Serv.). Biconvex Orthids,
finely striate, some of them tubulose. Resemble small Schizophoria but are
impunctate. Lower Ordovician ; North America.

Subfamily B. Khipidomellinae, novum.
Rhipidomellidae with the shell abundantly pundate and finely striate.

Heterorthis Hall and Clarke. Contour strophomenoid with the ventral
diductor scars very large. Ordovician ; North America ^^ ^

and Europe.

Rhipidomella QEhlert (Rhipidomys QEhlert, non
Wagner). Biconvex, sub-circular shells with short
hinge-lines. Striae generally hollow and open on the
surface into (1) short tubulär spines. Late Ordovician p^,, r,Q^^

into Pennsvlvanian ; widely distributed throughout the BiiohUesbaobus(jjum.). siiu-

,, -^ ^ ./ o ^j^^. Qotiand. A, Shell, i/i-

World. B, Interior of dorsal valve, -^/j.

CLASS II

BRACHIOPODA

383

BiloUtes Linn. (Dicoelosia King) (Fig. 564). Silurian and Lower Devonian ;
Europe and North America.

Schizophoria King (Fig. 565). Relative convexity of valves reversed.
Large, very finely striate, with the Striae hollow and spinöse! Cardinal

Fk;. 565.
A-C, Schizophoria striatula (Schloth.)- Devonian ; Gerolstein, Eifel. A, Dorsal aspect. B, Interior of
dorsal valve. C, Interior of ventral valve. D, S. vulvaria (Schloth.). Spiriferensandstein (Lata Lower
Devonian) ; Niederlahnstein, Nassau. Internal mould. (All tigures of the natural size.)

process in mature shells with accessory ridges making it multilobate. Dorsal
interior marked by 4 to 6 deep pallial sinuses. Silurian to Goal Measures ;
widely distributed throughovit the world. Subgenus : Orthotichia Hall and
Clarke. Like Schizophoria externally, but in the ventral valve the dental
lamellae and a median septum are highly developed. Goal Measures ; Brazil
and India.

Subfamily C. Enteletinae Waagen.

Rhipidomellidae with decidedly convex valves and a few hroad plications super-
added to the very fine radial Striae. Developed out of Orthotichia.

Enteletes Fischer {Syntrielasma Meek and Worthen). Dorsal valve more
convex than ventral. Hinge-line short with a high ventral cardinal area. In
the ventral valve the dental lamellae are high and convergent, and between
them is a marked median septum ; the crural septa of the dorsal valve are
also well developed. Goal Measures and Permian ; North and South America,
Europe and Asia.

Enteletoides Stuckenberg. Upper Garboniferous ; Russia.

Superfamily 2. STROPHOMENACEA Schuchert.

Progressive, terminal Protremata, derived out of Orthacea (Billingsellidae), with-
out spondylia and cruralia. Deltidia and chilidia nearly always present throughout
life ; cardinal process always well developed. Pedicle nearly always small, emerging
through the apex of the valve, or lost when the shells cement toforeign objects or anchoi'
by means of ventral spines. A prolific stock of Brachiopods. Ordovician to Recent.

Family 1. Strophomenidae King.

Primitive Strophomenacea with well -developed deltidia and chilidia. Shells
usually ßat or concavo-convex and but rarely biconDex. Pedicle usually functional
but tending to be thin and weak, and often lost when the shells cement to foreign
objects or are otherwise held to the substratum {usually by spines). Ordovician to
Permian.

384

MOLLUSCOIDEA

PHYLUM V

Subfamily A. Eafinesquininae Sclmchert.

Strophomenids that as a rule throughout life have the ventral valve convex and
the dorsal cbncave. The relative form of the valves is the reverse of that in the
Orthotetinae.

Eostrophomena Walcott. Primitive, small forms with the cardinal process
Alling most of the dorsal delthyrium. Teeth inconspicuous, with the muscular
scars almost absent. Surface finely striate with alternating bundles of fine
lines between single coarser ones. Basal Ordovician ; Sweden and North
America.

Primitive Pledamlonites. Upper Cambrian
and Lower Ordovician ; North America
and England.

Plectella Lamansky. Intermediate
between Leptella and Plectambonites.
Ordovician ; Esthonia.

(?) Lamanshja Moberg and Seger-
berg. Ordovician ; Sweden.

Pledamhonites Pander (Leptaena

Davidson and auct.) (Fig. 566). Ordo-

^,., . vician and Silurian : North America

Leptella Hall and Clarke.

Fig. 566.

Plectambonites transversalis (Dalm.). ^jinman , , -y-,

Gotland. ^, Dorsal aspect, i/i- -B, Interior of dorsal and Europe.

Svar'icfeors'' """'''' ""'""' '^' ^' ''^''"'''" ' ""' Leptaena Dalman (Leptagonia M'Coy)

(Fig. 567). Shells having the characters
of Bafinesquina, but the flatter portions of the valves with corrugations and
wrinkles. Where these cease,
the Shells are more or less
abruptly and often rect-
angularly deflected. Ordovi-
cian to Lower Carboniferous.
Bafinesquina Hall and
Clarke (Fig. 568). Shells
normally concavo - convex
dorso-ventrally. Striae al-
ternating in size, and crossed
by finer concentric growth

A

Fig. 567.

Leptaena rliomboldalis (Wahlenh.). Silurian ; Gotland. A, B,
Dorsal aspect and profile. C, Interior of dorsal valve.

Fi(i. 568.

A, Bafinesquina aüernata (Conrad). Ordovician; Cincinnati, Ohio, i/l- B, E. exxwmsa (Sowerhy).

Interior of ventral valve, showinc; muscular and vascular impressions.

CLASS II BRACHIOPODA 385

lines. Muscular area of ventral valve consisting of two broad flabellate
diductor scars enclosing an elongate adductor. In the dorsal valve, the
bilobed cardinal process is low ; the posterior arborescent adductor scars well
defined. Vascular and ovarian markings often well indicated. Ordovician
and basal Silurian ; North America and Europe.

Stropheodo7ita Hall. Shells very much like Eafinesquina, but with the
cardinal margins finely denticulate and the deltidium flat or not discernible.
Silurian and Devonian ; North America and Europe.

Leptostrophia Hall and Clarke ; Douvillina CEhlert ; and Brachyprion Shaler
are subgenera of Stropheodonta. Silurian and Devonian.

Pholidostrophia Hall and Clarke. Smooth or squamose, nacreous small
Stropheodontas. Devonian ; North America and Europe.

Strophonella Hall (Amphistrophia Hall and Clarke). Eesupinate Stropheo-
dontas. Silurian and Devonian ; North America and Europe.

Gaspesia Clarke. Aberrant Strophomenid recalling coarsely plicate Orthids.
May, however, be a Pelecypod. Lower Devonian ; Gaspe, Canada.

Subfamily B. Tropidoleptinae Schuchert.

Aberrant Strophomenidae with two very long slender crura that unite vnth a high
vertical dorsal septum. The family is sometimes regarded as better placed among the
Terebratellids of the Terebratulacea.

Tropidoleptus Hall. Plano-convex, plicated shells with a long, straight and
narrow cardinal area. Teeth and dental sockets corrugated on their outer
surfaces. Devonian ; America, Europe and South Africa.

Subfamily C. Davidsoniinae King.

Small specialised Strophomenids, derived out of Eafinesquininae and devoid of a
being cemented by the ventral valve to foreign objeds.

Christiania Hall and Clarke. DifFers from Leptaenisca in having prominent
longitudinal ridges instead of spiral markings on the dorsal interior. Ordo-
vician ; North America, England and Eussia.

Leptaenisca Beecher. Ventrally cemented shells having
some of the characters of Plectambonites. Markings of
the fleshy arms are retained on the dorsal shell. Silurian
and Lower Devonian ; North America.

Davidsonia Bouchard (Fig. 569). Thick Leptaenisca-Mke ^^^ ^^^

Shells, with Spiral markings of the fleshy arms strongly ^^^,,,,„,,;, ,;^,,,,.
impressed on both valves. Devonian; England, Belgium iana d.-^ Kon. Devonian ;

^ . cj ^ Eifel. Ventral valve witli

and KuSSia. spiral markings, 2/j.

Subfamily D. Orthotetinae Waagen.

Strophomenids with the ventral valve convex during early growth, becoming sub-
sequently concave, or the reverse of the order in the Eafinesquininae. In the later
forms both valves tend to be convex.

(?) Orthidium Hall and Clarke. Basal Ordovician ; North America.
VOL. I 2 c

386

MOLLUSCOIDEA

PHYLUM V

Strophomena Blainville. Shells like Bafinesquina, but with the relative con-
vexity of valves reversed, and the ventral muscular area sharply limited by

an elevated margin. Ordovician ; America
and Europe.

Schuchertella Girty (Fig. 570). Much like
Strophomena. Shell piano -convex, concavo-
convex or biconvex. Surface covered with
radiating Striae, which are convoluted by
sharp concentric lines. Cardinal area of
ventral valve prominently developed and not
attached by cementation ; dorsal area narrow.
Dental plates rudimentary. Cardinal process
united to crural plates, the whole forming
a vertical subcrescentic process. Muscular
impressions flabelliform. Silurian to Upper
Carboniferous ; North and South America,
Europe and India.
Like Schuchertella, but with the muscular areas
Lower Devonian ; North America.

Fig. 570.

Schuchertella umhraculum (Schloth.).
Devonian ; Gerolstein, Eifel. Natural size.

Hipparionyx Vanuxem.
much larger and no dorsal cardinal area.

Schellwienella Thomas (Orthothetes Waagen, non Orthotetes Fischer) (Fig. 571).

Fig. 571.

Schellwienella crenistria (Phill.). Lower Carboniferous; Wexford. A, Muscular portion of vential valve.
B, Interior of dorsal valve. A, A', Adductors ; R, Diductors ; j, Cardinal process; d, Uental sockets (after
Davidson).

Near Schuchertella, but with short diverging dental plates and the cardinal area
either rudimentary or absent, Lower Carboniferous ; Europe.

Kayserella Hall and Clarke. Small Schuchertella-like shells, with a very
high dorsal median septum. Devonian ; Germany.

Orthotetes Fischer. Like Schuchertella, but in the ventral valve there is a
small triangulär umbonal Chamber formed by the uniting of the dental plates,
in front of which is a well-developed median septum. Ventral cardinal area
usually attached by cementation. Upper Carboniferous and Permian ; North
and South America, Europe, India and Russia.

Derlya Waagen. Like Orthotetes, but without the umbonal Chamber.
Lower and Upper Carboniferous; North and South America, Europe and
India,

Omionia Caneva. Related to Orthotetes as Geyerella is to Meekella. Permian ;
Italy.

CLASs II BRACHIOPODA 387

Scacchinella Gemmellaro. Near to Derbya, but with excessively high
ventral cardinal areas. Ventral beak cemented ? Shells resemble Michiho-
fehia, but have originated in some Orthotetinae and not in the Productinae.
Permian ; Sicily and Austria.

Aräitreta Whitfield. Imperfectly known, but seemingly a member of the
Orthotetinae. Upper Carboniferous ; Arctic America.

Streptorhynchus King. Very much like Schuchertella. Ventral area high,
Short, twisted and probably cemented. Carboniferous and Permian ; America,
Europe and India.

Meekella White and St. John. Very biconvex shells, with the teeth of the
ventral valve supported by very long dental plates which are nearly parallel
and reach to the bottom of the umbonal cavity ; no median septum. Surface
of valves with coarse costae and fine, radiating, often plumose Striae. Upper
Carboniferous ; North America, Eussia, India and China. Subgenus : Ortho-
thetina Schellwien. Like Meekella, but without costae. Late Upper Carboni-
ferous and Permian ; Europe.

Geyerella Schellwien. Near to Meekella, but with very high ventral areas ;
very long dental septa converging and uniting in a median septum. Ventral
beak cemented. Upper Carboniferous and Permian ; Europe.

Subfamily E. Tripleciinae, novum.
Biconvex Strophomenids with markedfold and sinus.

Triplecia Hall (Dicraniscus Hall). Trilobate, unequally biconvex, short-
hinged shells. Cardinal process long, erect and bifurcate. Surface smooth.
Ordovician and Silurian ; North America, England and Bohemia.

Cliftonia Foerste. Striated Triplecia. Ordovician and Silurian of America
and Europe.

Mimidus Barrande. Like Triplecia, but with the median fold on the
ventral valve. No external evidence of a deltidium. Silurian ; Bohemia and
North America.

Streptis Davidson. Like Triplecia, but biconvex and bilaterally unsym-
metrical. Exterior with lamellar concentric shell expansions. Silurian;
Europe and North America.

Family 2. Thecidiidae Gray.

Cemented StropKomenacea, in which the interior of the shell is impressed with
variously indented brachial furrows. Carboniferous to Eecent.

This family was formerly associated with the Terebratulidae. Beecher has shown,
however, that brachial Supports are wanting, and that a true deltidium is present.

Subfamily A. Leptodinae, novum.
Thecidiidae with the brachial markings common to both valves.

Keyserlingina Tscherny. An early form of Leptodus, with few brachial
ridges. Upper Carboniferous ; European Russia and Austria.

Leptodus Kayser {Lyttonia Waagen ; Waagenopora Noetling). Very large,
highly inequivalved, irregulär shells, frequently with broad lateral expansions.

388

MOLLUSCOIDEA

PHYIÜM Y

Numerous, laterally directed, brachial ridges in the ventral valve, with corre-

sponding divergent grooves in
the median region of the dorsal
valve. Permian; China and India.

Oldhamia Waagen (Fig. 572).
Differs from Lejotodus in that the
ventral valve is sub-hemispherical
with the incurved apex covered
by a callosity, as in Bellerophon.
Permian ; India and China.

Loczyella Frech. Said to be

like Leptodus, but without the

^, ,. . , . . r^ ^^"^ t . . ^. r. brachial rideres. May not be a

Oldhamm decipiens Waagen. Productus Limestone ; Salt t, ^ • i tt /~i ^

Range, East India. A, B, Interior of ventral and dorsal brachlOpod. Upper UarDOni-

ferous ; Nanking, China.

valves, respectively (after Waagen).

Subfamily B. Thecidiinae Dali.
Thecidiidae with the brachial markings restricted to the dorsal valves.

Thecidea Defrance (Thecidium Sowerby) (Fig. 573). Dorsal brachial im-
pressions with three pairs of symmetrical lobes, radially directed. Cretaceous.

Thecidea and the following genera of the subfamily Thecidiinae comprise for the
most part small, sometimes extremely minute forms, represented from the Trias to
the present day ; the climax of diversity occurred in the Cretaceous.

Lacazella Munier-Chalmas (Figs. 574, 575). Dorsal brachial impressions

Fig. 573.

Thecidea papillata Schloth. Upper
Cretaceous ; Ciply, Belgium. A, B, In-
terior of ventral and dorsal valves, re-
spectively, 2/j (after Woodward).

Fig. 574.

Lacazella vertnicularis
(Schloth.). Upper Cretaceous ;
Maestricht. Dorsal valve, 2/j
(after Suess).

Fig. 575.

Lacazella tnediter-
ranea (Risso). Re-
cent. Interior of
dorsal valve showing
brachia, ^/i (after
Woodwaid).

The two large, dorsal, brachial

with two or three unequal pairs of lobes, medially directed. Jurassic to
Eecent; Europe.

Thecidiopsis Munier-Chalmas (Fig. 576).
impressions each have four pairs of lobes
laterally and medially directed. Creta-
ceous ; Europe.

Thecidella Munier-Chalmas. Dorsal
brachial impressions simple, anteriorly
directed. Jurassic ; Europe.

Eudesella Munier-Chalmas. Trans-
verse Shells in which the dorsal brachial
impressions have three pairs of simple lobes antero-laterally directed. Jurassic;
Europe.

Fig. 576.
Thecidiopsis digitata(ßo\äii.). Greensand ; Essen
on the Rhine. A, Dorsal aspect. B, C, Interior
of ventral and dorsal valves, respectively, l/j.

CLASS II

BRACHIOPODA

389

Fterophloios Gümbel (Badrynium Emmrich) (Fig. 577). Dorsal brachial
impressions with about ten laterally directed lobations. Alpine Rhaetic.

Davidsonella Munier-Chalmas. Elongate shells with
the long, narrow, dorsal, brachial impressions simple
and antero-laterally directed. Jurassic ; Europe.

(?) Cadomella Munier-Chalmas. Lias ; Europe.

Family 3. Productidae Gray.

Strophomenacea with hollow anclioring spines.
Ordovician to Permian.

Late

Fio. 577.

Pterophloios emmrichi Güm-
bel. Ehaetic ; Kössen, Tyrol.
Interior of dorsal valve, i/i.

Subfamily A. Chonetinae Waagen.

Froductids with the few anchoring spines restrided to the ventral cardinal margin.

Chonetes Fischer (Fig. 578). Shell transversely elongate, semicircular in
outline, typically concavo-convex, sometimes plano-convex. Upper margin of
cardinal area in ventral valve bearing a single row of hollow spines ; these are
prolongations of tubes which penetrate obliquely the substance of the shell
along the hinge-line. Teeth strong. Cardinal process of dorsal valve divided
by a narrow median and two broader lateral grooves. Brachial impressions
more or less distinct. External surface usually covered with radiating Striae,
rarely smooth or concentrically rugose, Late Ordovician to Permian. Sub-
genus : Eodevonaria Breger. Chonetids with denticulate hinge-lines. Lower
Devonian ; America and Europe.

Anoplia Hall and Clarke. Smooth or squamose shells like Chonetes, sup-
posed to be without cardinal spines. Lower Devonian ; North America.

Chonostrophia Hall and Clarke. Like Chonetes, but with the shell reversed
Lower and Middle Devonian ; North and South America.

Chonetella Waagen. Upper
Carboniferous ; India. Chonetina
Krotow. Permian ; Russia.

(?) Daviesiella Waagen. Shell
productoid, but without spines
and well-developed cardinal area
and teeth. Upper Carboniferous ;
England.

(?) Aulacorhynchus Dittmar {Iso-
gramma Meek and Worthen). Very
large, transverse, thin shells with a
ventral platform. Exterior surface
with numerous, regulär, continuous,
concentric ridges. Upper Car-
boniferous ; Europe and North
America.

or concavo-convex.

Fin. 578.

A, Chonetes striatelhis (Dalm.). Silurian ; Gotland. i/i-
B, Interior of dorsal valve (after Davidson). C, C. sar-
cinulatus de Kon. Devonian ; Coblenz. i/j.

Subfamily B. Prodüctinae Waagen.

Produdids with the anchoring spines more or less ahundant over the entire ventral
and sometimes also over the dorsal valve.

Produdella Hall. Shells small, productoid, with narrow cardinal areas in

390

MOLLUSCOIDEA

PHYLUM V

both valves. Ventral valve with small teeth ; dorsal valve with sockets and

crural plates. Brachial impressions distinct. Devonian ; America and Europe.

Produäus Sowerby (Pyxis Chemnitz ; Arhusculifes Murray ; Protonia Linck ;

Producta Sow.) (Figs. 579, 580). Shell without functional pedicle, anchored

Fig. 579.

A, Productus semiretimlatus (Martm). Lower Carboniferous ; Vise, Belgium. Vi- B, P.igiganteus(M.a.rtm).
Same horizon ; England. Interior of dorsal valve (after Woodward). C, D, P. horridus Sow. Permian ; Prussia
and England, i/i- C, Interior of dorsal valve. D, Internal mould of ventral valve. A, Adductors ; R, Diductors ;
pr, Cardinal process ; h, Hinge-line ; v, Brachial impressions.

by the ventral spines ; concavo-convex, valves usually produced anteriorly ;

outlines semicircular, sometimes transversely elongate. External surface

spinöse, usually with more or less prominent radiating

ribs, which are crossed by concentric lines or wrinkles ;

rarely smooth or finely striated. Cardinal areas, teeth,

sockets and crural plates absent or rudimentary.

Ventral valve convex, sometimes geniculated; often

Fig. 580. with median sinus. Muscular impressions consisting of

Productus horridus sowerhy. two deudritic adductors and a pair of broadly flabel-

Permian ; Gera, Germany. 1/4-1 • t -1 /-i t i i

late, striate diductors. Cardinal process strong, curved
or erect, extending far above the hinge-line. Brachial ridges well defined ;
traces of spiral or brachial cavities occasionally present in the pallial region.
Extraordinarily abundant in Carboniferous and Permian. Distribution
general.

P. giganteus is the largest Brachiopod known, sometimes attaining a width of nearly
one foot.

Subgenera : Diaphragmus Girty. Productus with an internal plate in dorsal valve.
Upper Carboniferous ; North America. Marginifera Waagen. Has thickened internal
submarginal ridges. Upper Carboniferous ; North America, India.

Tschernyschewia Stoyanow. Typified by Productus humholdti d'Orb. Upper
Carboniferous; India, Russia.

CLÄSS II

BRACHIOPODA

391

Proboscidella (Ehlert. Valves very unequal; dorsal valve small, concave,
operculiform ; ventral valve larger, convex, furnished with two lateral expan-
sions which bend downward to meet the margins of the dorsal valve, and an
anterior expansion, which is produced forward into one, or occasionally two,
long cylindrical tubes. Carboniferous ; Europe and North America.

Subfamily C. Strophalosiinae, noviim.
Produdids anchored to foreign objeds hy the spines or hy most of the ventral shell.

Chonopedus Hall and Clarke. Chonetes-like shells, but cemented ventrally
to extraneous objects. External surface reticulated by a double, oblique
series of concentric lines and fine radiating Striae. Lower Carboniferous ;
North America.

Strophalosia King (Orthothrix Geinitz ; Leptaenalosia King) (Fig. 581).
Shell productoid in general

form, cemented by the ven-
tral umbo. Both valves
with well-defined area, del-
tidium and chilidium. Ven-
tral valve with two pro-
minent teeth unsupported
by dental plates. Muscular
impressions small ; brachial
ridges distinct. Surface of
ventral valve covered with
spines ; that of the dorsal

\

\

Fig. 581.
Strophalosia goldfussi (Münst.). Permian ; Gera, Germany. A,
Dorsal aspect. B, Profile. C, Interior of dorsal valve with brachial
impressions. Natural size.

Middle Devonian to Permian ;

valve either spinous, lamellose or smooth.

Europe, India, North and South America.

Aulosteges Helmersen. Much like Strophalosia, but not cemented by the

ventral umbo ; deltidium covered with small spinules and the surface of both

valves thickly set with spines. Permian ; Russia and India.

Etheridgina (Ehlert. Shell very small, nearly as broad as long, and

attached to foreign bodies, notably crinoid stems, by the spines of the ventral
valve. Dorsal valve with a small beak ; surface ornamented
by concentric flexuous plications bearing a few scattered
spines. Carboniferous ; Scotland.

Family 4 Richthofeniidae Waagen.

Strophomenacea developed out of the Produdidae, and
remarkably modified by ventral cementation. The form is that
of cyathophylloid corals with an operculiform dorsal valve.
Shell strudure cystose. Upper Carboniferous and Permian.

Tegulifera Schellwien. A youthful expression of the
highly modified Eichthofenia, in which the productoid
characters are still recognisable. Upper Carboniferous;
Au Stria.

Eichthofenia Kayser (Fig. 582). These most remarkably

Fio. 582.

Richthofenia lawrenci-
a«a Waagen. Permo-Car-
boniferons ; Salt Range.
Vertical section of ven-
tral valve (after Waagen).

392

MOLLUSCOIDEA

PHYLUM V

modified Brachiopods are found in the Permian of China, India, Sicily and
Texas.

Gemmellaroia Cossman (Megarhynchus Gem., non Lap.). Permian ; Sicily.

Superfamily 3. PENTAMERACEA Schuchert.

Protremata developed out of Nisusiinae among the Orthacea, with well-
supported or free spondytia, and, as a rule, cruralia. Deltidia and chilidia
present in the more primitive forms and generally absent in the last developed f amilies.
The least prolific stock of the Protremata. Cambrian to Permian.

. Family 1. Syntrophiidae Schuchert.

Primitive transverse Pentaiaerids, derived out of Nisusiinae, having as a rule long,
straight cardinal areas that usually are devoid of deltidia and chilidia. Spondylia
and cruralia free or supported by septa. Cambrian and Ordovician.

(?) Swantonia Walcott (Fig. 583). Rostrate, plicate, small and rare shells,
with a free but small spondylium. Lower Cam-
brian : North America.

ml

Fig. Ö83.

Stvantonia antiquata (Bill.).
Lower Cambrian ; Vermont. A,
Ventral exterior. B, Side view
of same showing spondylium
(after Walcott).

Fig. 584.

SyntropMa lateralis (Whitfield). Ordovician ; Fort Cassin,
Vermont. A, C, D, E, Views of ventral valve showing cardinal
area and spondylium. B, Dorsal valve. F, Cardinal view of
both valves ground away to sliow section of spondylium and
cruralium (after Hall and Clarke).

Syntrophia Hall and Clarke (Fig. 584). Transverse, straight-hinged,
primitive Pentamerids with open delthyria in both valves. Spondylia well
developed and supported by an incipient septum ; cruralia small and supported
by a septum. Middle Cambrian to Lower Ordovician ; North America.
Subgenus : Huenella Walcott. Has a plicate surface. Middle and Upper
Cambrian ; North America, China and Australia.

Clarkella Walcott. Like Syntrophia, but the spondylium is supported by
three septa. Lower Ordovician ; Montana.

Family 2. Olitambonitidae Winchell and Schuchert.

Divergent transverse Pentamerids, derived out of Syntrophiidae, with well-
cardinal areas, deltidia, chilidia and spondylia. Cruralia not developed. Essenti-
ally Ordovician but ränge sparingly into Devonian.

Clitambonites Pander (Orthisina d'Orb. ; Pronites and Gonambonites Pander)
(Fig. 585). Valves convex or sub-pyramidal. Hinge-line straight, forming

I

CLASS II

BRACHIOPODA

393

the greatest diameter of the shell. Cardinal area of the ventral valve high ;

delthyrium broad, and covered by a perforate deltidium ; that of the dorsal

valve covered by a

chilidium. Dental

lamellae of ventral

valve very strongly

developed, uniting

to form a concave

spatulate plate or

spondylium. This

plate serves for the

attachment of

muscles, and is sup-

ported by a median

septum extending

for about one-half the length of the valve. External surface radially striated

and often lamellose. Shell substance impunctate. Ordovician ; North Europe

and North America.

Subgenus : Hemi^nonites Pander. Biconvex Orthid-like forms with fine non-lamellose
Striae. Ordovician ; Esthonia.

Polytoechia Hall and Clarke. Like Clitambonites but with the spondylia
supported by three septa, thus dividing the umbonal cavity of the ventral
valve into five Chambers. Ordovician ; North America.

Scenidium Hall (Mystrophora Kayser). Small orthisinoid shells with the
delthyrium partially closed by a concave imperforate deltidium. Cardinal
process extending as a median septum throughout the length of the shell.
The septum is sometimes greatly elevated anteriorly in Devonian species.
Ordovician to Devonian ; North America, Europe and the Urals.

Fifi. 585.

A, Clitambonites adscendens (Fand.). Ordovician ; Pawlowsk, near St. Peters-
burg, i/j. B, ü, C. squamatus (Pahlen). Ordovician ; Kuckers, Esthonia. B,
Interior of dorsal valve, showing edge of the chilidium. C, Interior of ventral
valve, showing spondylium, septum and deltidium (after Pahlen).

Family 3. Porambonitidae Davidson.

Derived {out of Syntrophiidae), progressive, semi-rostrate Pentamerids, with the
deltidia and chilidia vanishing more and more in time. Spondylia and cruralia
present, but the former tends to thicken and unite with the ventral valve. Ordovician
to Lower Devonian.

Subfamily A. Porambonitinae Gill.
Non-plicated Porambonitidae, with the shells ezternally pitted. 'Ordovician.
Porambonites Pander (Isorhynchus King) (Fig. 586). Shells similar

A B C D E F

to

Fig. 380.

Porambonites aequirostris (Schloth.). Ordovician (VaginatenRalk) ; St. Petersburg. A-C, Anterior, lateral
and posterior aspects of shell, Vi. D, Punctate surface, magnified. E, F, Interior of ventral and dorsal valves,
respectively.

Parastrophia in form, but without plications, and with obtusely triangulär

394

MOLLUSCOIDEA

PHYLUM V

areas in both valves. Shells thick, variously pitted externally. Ordovician ;
Eussia.

Noetlingia Hall and Clarke. Exterior like Porambonites, but with long,
straight hinge-line, prominent cardinal areas, andperforate beaks. Ordovician;
Russia.

Subfamily B. Parastrophiinae, novum.

PUcated Poramhonitidae. Ordovician to Lower Devonian.

Camarella Billings. Small, smooth shells with a few low plications and
without cardinal areas. Dorsal valve at maturity most convex. Spondylium
well defined. Cruralium very small, supported by a long septum. Ordovician ;
North America and (?) England.

Parastrophia Hall and Clarke. Much like Camarella, but with a moderately
long, straight cardinal line, and no cardinal area. Dorsal umbo conspicuous,
projecting beyond that of the ventral valve. Ordovician and Silurian ; North
America and England.

Änastrophia Hall {Brachymerus Shaler, non Dej.). Much like Parastrophia,
but with the dorsal umbo more prominent and the valves with numerous
sharp plications extending to the beaks. Silurian and Lower Devonian;
North America, England and Gotland.

(?) Lycophoria Lahusen. Russia and Scandinavia.

; Family 4. Pentameridae M'Coy.

Terminal, usually rostrate Pentamerids, developed out of Poramhonitidae.
Spondylia and cruralia well developed. Sometimes there is a concave plate in the
ventral delthyrium that is interpreted as the "deltidium ; if so, it is a special develop-
ment due to the highly incurved beaks of both valves in the decidedly convex species.
Silurian to Permian.

Conchidium Linn. {Gypidia Dalman ; Antirhynchonella Quenstedt ; Zdimir
Barrande) (Figs. 587 ; 588, D). Shell strongly inequivalve, biconvex, with

Fig. 587.
Conchidium Uloculare Linn. Silurian ; Gotland. A, Shell of the natural size. B, Beak showing concave
deltidium. C, D, Interior of dorsal and ventral valves, respectively. x, Spondylium ; S, Median septum of
ventral valve, Fig. D ; b, Dental lamellae ; c, Crura ; S, Septum-like supports, Fig. Ü.

n

highly arched ventral valve. Surface numerously plicated. Spondylium narrow
and deep, and supported by a high vertical septum of variable length. A
small cardinal process present. Silurian and Devonian ; distribution general.

CLASS II

BRACHIOPODA

395

Stricklandinia Billings. Similar to Conchidium, but with a straight hinge-
line and no prominei*t arched ventral beak. Spondylium small and short,
supported by a short median septum. Silurian ; North America, England
and Gotland.

Pentamerus Sowerby (PentasÜre Blainville). Like Conchidium, but with
smooth Shells, or sometimes with a few broad and obscure radiating undula-
tions. Silurian ; distribution probably general.

Orthotropia Hall and Clarke. Similar to small Pentamerus, but with a
short hinge-line. Differs also internally. Silurian ; Wisconsin.

Holorhynchus Kiär. Transverse Pentamerus, with incipient plications.
Spondylium not supported by septum. Silurian ; Norway.

Cajpellinia Hall and Clarke. Like Pentamerus, but with the relative con-
vexity of the valves reversed. Silurian ; North America.

Clorinda Barrande {Barrandella Hall and Clarke). Small Gijpidula-\ikQ
Pentamerids usually with smooth shells, rarely plicate. Spondylium with-
out a supporting septum. Silurian ; North America and Europe.

Pentamerella Hall. Much like Clorinda, but with strong plications and a
narrow cardinal area. Devonian ; North America.

Sieberella CEhlert ; and Gypidula Hall. (Fig. 588.) Galeatiform Penta-

FiG. 588.

Ä-Ct Gypidula galeata (Dalm.). Devonian ; Gerolstein, Eifel. A, Dorsal aspect, i/i. B, Anterior aspect.
C, Transverse section below the hinge-line. (Lettering the same as in Fig. 587, C, D.) D, Conchidium knightii
(Sow.). Silurian ; England. 1/2.

merids,with the median sinus on the dorsal, and the fold on the ventral valve.
In Sieberella there is no cardinal area, but in typical Gypidula there is a well-
defined, cross-striated, cardinal area.
Surface smooth or plicate. Silurian and
Devonian; North America and Europe.

Branconia Gagel. Like Gypidula,
but with sharp and few plications, as
in Pugnax of the Rhynchonellids. Sil-
urian ; Glacial drift of Germany.

Seminula M'Coy {non auct.). Ac-
cording to Buckman the genotype is
Terebratida penta'edra Phillips. Shells
rhynchonelliform with the surface
more or less strongly plicated. Spon- ^,^-7 1 iV^iil^^t in^^^^^^^^^^

dvlium SUDÜOrted bv a long median of shell, enlarged. pr, Cardinal process ; c, Crtira ;
•^ , T^ • i. -n • T? .« ^, Spondylium; g, Dental plates of dorsal valve;

septum. Devonian to Permian ; Europe, ,,; g'^ Median septa.

India and North America. Subgenus

Camarophoria King (Fig. 589) may, according to Buckman, be used for the

more transverse, fully plicate shells.

Fig. 589.

396 MOLLUSCOIDEA phylüm v

■ Camarophorella Hall and Clarke; Biconvex, sub-circular Camarophoriae,
biit without sinus, f old and plications. Lower Carboniferous ; North America.

Strophomenacea of unknown relationships.

Family 1. Eichwaldiidae Schucliert.

Primitive or aberrant, rostrate Strophomenacea, with narrow lateral grooves and
ridges for articulation. Delthyrium closed hy a concave plate {? deltidium). Pedicle
emerging through the ventral umhone and moving with growth anteriorly hy resorption
through the shell, as in Siphonotretidae. Ordovician and Silurian.

Eichwaldia Billings. The single species of this genus has a smooth
exterior. Ordovician ; North America.

Dictyonella Hall {Eichwaldia auct.). Exterior surface of valves pitted in
quincunx, resembling Trematis. Silurian ; North America, England, Bohemia
and Gotland.

Order 4. TBLOTRBMATA Beecher.

Specialised (through Atremata, ? Obolacea), articulate, calcareous Brachio-
poda, with the pedicle opening shared hy both valves in earliest shell ed
stages, usually confined to one valve in later stages, and becoming more or less
modified by deltidial plates in advanced growth stages. Brachia supported by
calcareous crura, loops or spiralia.

Superfamily 1. RHYNCHONELLACEA Schuchert.

Rostrate, primitive Telotremata, with or without crura for the support of the
hrachidia. Pedicle foram^n nearly always heneath the heak and hut rarely through
a truncate ventral apex. Shells almost always impunctate. Ordovician to Recent.

Family 1. Protorhynchidae Schuchert.

Primitive Rhynchonellacea without deltidial plates or crura. Ordovician.

Protorhyncha Hall and Clarke. Biconvex Rhynchonellae with the fold
and sinus ill-defined. No cardinal process or dorsal median septum. Surface
with low radial plications. Ordovician ; North America.

Family 2. Rhynchonellidae Gray.

Rhynchonellacea with crura of greater or lesser length. Shells usually plicate,
rarely smooth or spinöse. Ordovician to Recent.

Subfamily A. Rhynchotreminae, novum.

Rhynchonellids with a cardinal process. Ordovician to Devonian.

Orthorhynchula Hall and Clarke. Rhynchonellae with short, straight hinge-
line and cardinal areas in both valves, bisected mesially by open delthyria.
Teeth unsupported by dental lamellae. A linear cardinal process present.
Ordovician ; North America.

Rhynchotrema Hall (Stenochisma Conraid, 1839; and Hall, 1867) (Fig. 590).

CLASS II BRACHIOPODA 397

Thick-shelled, often gibbous Rhynchomllae with prominent, thick, concave
deltidial plates. Dorsal valve with a thick median septum, upon which rests

B

A

C

Fio. 590.
Rhynchotrema capax (Conrad). Ordovician ; Wisconsin. A, Interior of ventral valve sliowing concave
deltidial plates {dp) and teeth (0- B, Dorsal view. C, Dorsal interior showing cardinal process (j), crural
processes (c) and dorsal sockets (h). (After Hall and Clarke.)

a linear cardinal process. Crural plates very broad and stout. Ordovician ;
North America.

Stegerhynchus Foerste. Exterior as in Camarotoechia^ but with a thin
vertical cardinal process as in Rhynchotrema. Silurian ; North America and
Europe.

Rhynchotreta Hall. Trihedral Rhynchonellae with the ventral beak acu-
minate, produced and truncate. Pedicle foramen apical, the delthyrium
being completely closed by the deltidial plates. Dental lamellae and car-
dinal process present. The prominent dorsal median septum separates
posteriorly, each brauch supporting one process of the divided hinge-plate.
Silurian ; North America and Europe.

Eatonia Hall. Rhynchonellae with large, flabellate, deeply excavated
muscular scars in the ventral valve. No dental lamellae. Cardinal process
large, resting upon a short median septum, and bifurcate at its summit.
Devonian ; North America.

Uncinulus Bayle. Like fVilsonia, but with the hinge-plate undivided, and
with a well-developed cardinal process. Devonian ; North America and
Europe.

(?) Cyclorhina Hall and Clarke. May be of the Athyridae rather than of
the Rhynchonellidae. Devonian ; North America.

Subfamily B. Rhynchonellinab Gill.

Rhynchonellids without a cardinal process. Silurian to Recent.

Camarotoechia Hall and Clarke (Fig. 591). Sharply plicate Rhynchonellae
with the dorsal median

septum bearing pos- >**. ^ B ,hD ^'

teriorly a short crural

cavity. Cardinal process ^^/jl^^^^ <^|^|^4^- ,^||||||Q^J^v
absent ; dental lamellae
present. Silurian to
Lower Carboniferous ; p^^. ^^^^

North America and CamarotoecUa congregata {Conv&A). Devonian ; New York. ^.Dorsal

Für one aspect. B, C, Dorsal interiors showing hinge-plate (hp), rostral Chamber

o-iui upc. ^^^^ crural processes and dental sockets (h). (After Hall and Clarke.)

Plethorhyncha Hall
and Clarke. Large, ponderous Rhynchonellae, with almost no dental lamellae
and 110 crural cavity. Lower Devonian ; North America and Europe.

398 MOLLUSCOIDEA phtlüm v

Rhynchotetra Weller. Elongate, coarsely plicate shells nearest to
Camarotoechia. Dental lamellae uniting iiito a spondylium, which is supported
by a median septum. Lower Carboniferous ; North America.

Tetracamera Weller. Like Camarotoechia, but with rostral dorsal cavity
divided into four Chambers by the crural plates and a median septum. A
spondylium present, but practically without septal support. Lower
Carboniferous ; North America.

Paraphorhynchus Weller. Coarsely plicate Rhynchonellae with fine
additional Striae. Interior much as in Camarotoechia. Lower Carboniferous ;
North America.

Leiorhynchus Hall. Internally like Camarotoechia, but with the plications
on the lateral slopes usually faint or obsolete. Devonian to Carboniferous.
^ubgenus : Moorefieldella Girty. Differs in having a finely plicate surface.
Lower Carboniferous ; North America.

Wilsonia Kayser {Uncinulina Bayle). Sub-cuboidal or sub-pentahedral
Rhynchonellae with the low plications marked anteriorly by fine median lines.
Internally as in Camarotoechia. Silurian to Lower Carboniferous. North
America and Europe.

Hemiplethorhynchus von Peetz. Very similar to Camarotoechia. Crural
cavity with a posterior triangulär opening. Upper Carboniferous ; Altai,
Kussia.

Hypothyridina Buckman {Hypothyris King, non Hubner 1822). Sub-
cuboidal Rhynchonellae with a very rudimentary dorsal median septum.
Plications as in Wilsonia. Vascular sinus frequently strongly impressed in
the ventral valve. Devonian ; North America and Europe.

Pugnax Hall and Clarke. Rhynchonellae with a deep dorsal and shallow
ventral valve, and very prominent fold and sinus. Dental lamellae short ;
no median septa. Devonian to Carboniferous ; North America and Europe.
Subgenus : Ällorhynchus Weller. Has decided angular plications as in
Camarotoechia. Lower Carboniferous ; North America.

Fugnoides Weller. Exterior like Pugnax, with the internal characters of
Camarotoechia. Lower Carboniferous ; North A.merica.

Shumardella Weller. Much like Pugnax, but with a short dorsal median
septum that is not connected with the hinge-plate. Lower Carboniferous ;
North America.

Rhynchopora King (Rhynchoporina QEhlert). Plicate Rhynchonellae with
the shell substance punctate. A crural cavity as in Camarotoechia, but roofed
over by the hinge-plate. Dental lamellae well developed. Eange from
Lower Carboniferous to Permian ; Europe and North America.

(?) Torynifer Hall and Clarke. May be Rhynchonellae with the crural plates
united into a hinge-plate. Genus not yet defined. Lower Carboniferous ;
North America.

Terebratuloidea Waagen. Rhynchonellae with very large apical truncate
foramen, but without dental plates or median septa. Carboniferous to
Permian ; India.

Rhynchonella Fischer (as restricted by Hall and Clarke) (Fig. 592, A).
Sub-pyramidal pauciplicate shells with the pedicle opening as in Cyclothyris.
Dental lamellae and a dorsal median septum present. Jurassic and
Cretaceous.

Cyclothyris M'Coy (as redefined by Buckman in 1906) (Figs. 592, B,

CLASS II BRACHIOPODA 399

;ind 593). Multiplicate Bhynchonellae with the pedicle opening below the

A, Rhynchonella loxia Fisch. Upper Jura ; Moscow. a, b, Profile
and dorsal view, i/j ; c, Internal mould ; d, Anterior view. B,
Cyclothyris quadriplicata (Quenst.). Middle Jura; Bopflngen, Wür-
temberg.

Fig. 593.

A, Cyclothyris vespertilio
(Brocchi). Upper Cretaceous ;
Villedieu, Touraine. Vi- -ß. C.
lacunosa (Schloth.). Upper Jura ;
Engelhardsberg, Franconia. In-
terior of dorsal valve.

ventral beak. Embraces the bulk of Mesozoic Rhynchonellids. Genotype
Terebratula latissima Sowerby. Distribution general in Mesozoic time.

Upwards of 700 species of Brachiopods have been described under the name of
Rhynchonella, niost of wliich are found in Mesozoic strata and are now to be referred to the
genus Cyclothyris. But few Rhynchonellids agree with the genotype, which is Rhynchonella
loxia Fischer (Fig. 592) from the Upper Jura of Russia. It is probable that there are no
Rhynchonellas in the Paleozoic. Hall and Ciarke and Weller have shown that most of the
American Paleozoic species belong to other genera. Bittner has also removed from
Rhynchonella many Triassic species.

Halorella Bittner. Sharply plicated Bhynchonellae with a median sinus
on both valves. Alpine Trias.

Austriella Bittner. Small triangulär, usually smooth-shelled Bhynchonellae
without prominent fold and sinus. Alpine Trias.

Norella Bittner. Like Austriella, but with prominent anterior fold and
sinus. Alpine Trias.

Bhymhonellina Gemmellaro. Transverse Bhynchonellae with fine radial
Striae. Cardinal margin nearly straight, with a low concave ventral area.
Crura very long, ventrally curved. Median septum of dorsal valve faint.
Jura ; Sicily and the Alps.

Dimerella Zittel. Small plicate shells with a high umbo and a straight
hinge-line. Delthyrium large, with linear deltidial plates. Dorsal valve with
a high median septum extending to the ventral
valve. Alpine Trias.

Peregrinella (Ehlert. Large, strongly plicate
Bhynchonellae without fold or sinus. Cardinal
area well developed. Cretaceous ; Europe.

Hemithyris d'Orb. (Fig. 594). Smooth or
faintly plicate Bhynchonellae with a high ventral
beak and open delthyrium. No dental plates. . Fif=- 5^^.

_-, j. ./ Jlemi thyris pstttacea (Chem.). Recent

Kecent. Mediterranean. Vi.

400 MOLLUSCOIDEA phylüm v

Basiliola Dali. Deep-sea forms resembling Hemithyris, but with the
deltidial plates united into a spondylium-like plate. Eecent.

Frieleia Dali. Resembling Heynithyris, but with a small dorsal spondylium.
Recent ; American Pacific.

Atretia Jeffreys (Cryptopora Jeffreys 1869, non Cryptoporus Motoch 1858;
Neatretia CEhlert). Small, smooth sbells with an acute and
prominent open ventral beak. Dental plates and a high,
mesially situated, dorsal septum present. Recent.

Subfamily C. Acanthothyrinae, novum.

Ehynchonellids with a spinöse surface.

Acanthothyris d'Orb. (Fig. 595). In general like Hemi-
(Schioth.). Middie tfiyns, Dut witü well-developed dental plates. Jurassic to
pSifate'^'"^'^^^'' Recent ; Europe and Japanese sea.

Fio. 595.
Acanthothyris spinosa

Superfamily 2. TEREBRATULAOEA Waagen.

Specialised Telotremata with the brachia supported hy calcareous, primitive or
metamorphosed loops. Shell strudure always pundate. Devonian to Recent.

Division A. Terebratuloids.

Terebratulacea with the loops unsupported hy a median dorsal septum at any stage
of growth. Brachial cirri directed outwards in larval stages.

Family 1. Centronellidae Hall and Clarke.

Primitive Terebratuloids with short loops developing dired and composed of two
descending lamellae, uniting in the median line and forming a broad arched plate.
Shells smooth, faintly striate or rarely plicate. Devonian to Triassic.

This family comprises the simplest of all Terebratuloids, and from it are probably
descended the other loop-bearing f amilies.

Centronella Billings (Fig. 596). Commonly small, smooth, plano-convex

or concavo-convex shells, with the descend-
ing branches of the loop broadening
rapidly anteriorly, and uniting in a tri-
angulär, mesially ridged plate. Hinge-
plate perf orate. Devonian ; North America,
Amphigenia Hall (Enantiosphen Whid-
borne). Elongate-ovate, high-shouldered
Shells without median fold or sinus.
Fig. 596. *' Surface with concentric growth varices

Centronella glansfagea (Hall). Devonian ; Brie and f aint radial Striae. Dorsal Valve with
County, N.Y. ^, £, Profile and dorsal aspect, ^/.. ^ ■, i . i • i j_ j- j_ ^

c, Loop, eniarged. a large sub-quadrate ninge-plate periorated

by the visceral foramen and without a
cruralium. Middie Devonian; North and South America, France and
Germany.

Eensselaeria Hall. Ovate or elongate-ovate striate Terebratuloids. The
descending branches of the loop diverging for a short distance, thence acutely

CLASS II BRACHIOPODA 401

beut, converging, and uniting in an elongate triangulär plate, which on the
posterior margin gives off a small, posteriorly directed, rod-like process.
Hinge-plate large and often much thickened. Thick dental plates present.
Lower Devonian ; North America and Germany.

Lissopleura Whitfield. Strongly plicate Bensselaeriae, with the dental
plates uniting to form a short rostral cavity. Lower Devonian ; North
America.

Beachia Hall and Clarke. Lentiform, finely striated Bensselaeriae with the
lateral margins of the valves inflected, the anterior plate of the brachidium
broader, and the rod-like process longer. Lower Devonian ; North America.

Newberria Hall (Bensselandia Hall). Resembling Bensselaeria externally,
but without the striate surface. Interior strongly marked by muscular scars
and vascular sinuses. Devonian ; North America and Europe.

Chascothyris and Deiikmannia Holzapfel. Devonian ; Germany.

OrisJcania Hall and Clarke. Large Centronellae with a continuous hinge-
plate bearing a thin vertical spur or cardinal process. Lower Devonian ;
North America.

Selenella Hall and Clarke. Comprises biconvex terebratuliform shells
with a Centronella-like loop, but the triangulär plate not mesially thickened.
Devonian ; North America.

Bomingerina Hall and Clarke. Small biconvex Centronellae with the
median ridge on the anterior plate of the loop elevated into a high vertical
lamella almost touching the ventral valve and extended both anteriorly
and posteriorly. Devonian to Lower Carboniferous ; North America.

Trigeria (Bayle) Hall and Clarke. Plicated, plano-convex Centronellae.
Devonian ; France, Brazil and North America.

(?) ScaphioGoelia Whitfield. Very large, plicate, piano- or concavo-convex,
Cenironella-\ike shells exteriorly. Loop unknown. Shell substance fibrous,
impunctate. (?) Devonian ; South America.

Juvavella Bittner. Small, smooth, biconvex shells, with a very short
Centronella-\\kQ loop. Alpine Trias.

Juvavellina and Dinarella Bittner. Alpine Trias. Aspidothyris Diener.
Trias of India.

Nucleatula Bittner. Like Juvavella^ but having a longer loop with a well-
developed and fimbriated vertical median plate. Alpine Trias.

Family 2. Stringocephalidae King.

Specialised Devonian Terebratuloids with a long loop, follomng the margin of the
dorsal valve, and not recurved in front. Development direct. Prohahly no median
coiled arm. Shells smooth. Devonian.

Stringocephalus Defr. (Fig. 597). This, the solitary genus of the family, is
limited to the Devonian of Europe and North America.

Family 3. Terebratulidae Gray.

Terebratuloids developing originally a Centronella-like loop, and thence by a short
series of metamorphoses resulting at maturity in a free loop of varying form
Devonian to Recent.

VOL. I 2 D

402

MOLLUSCOIDEA

PHYLUM V

Subfamily A. Megalanterinae Waagen.

Faleozoic Terebratulidae with a longlloop giving off ascending hranches.
smooth. Devonian to Carboniferous.

Shell

Fig. 597.
Stringocephalus burtini Defr. Devonian ; Paffrath, near Cologne. A, Side-view, 2/3 natural size. B, Greatly
reduced diagram showing brachidium and median septa. C, Young speclmen with large delthyriurn and deltidial
plates. D, Interior of dorsal valve, natural size, partly restored. a, Adductors ; c, Crura ; d, Dental sockets ;
l, Loop ; pr, Cardinal process ; s, Median septum.

Megalanteris (Ehlert (Meganteris Suess). Large, smooth, equally biconvex,
sub-oval Shells, with the long convergent jugal processes of the loop extending
beyond the connecting band of the ascending branches. Devonian ; Europe
and North America.

Cryptonella Hall. Elongate oval shells with short jugal processes.
Devonian to Lower Carboniferous ; North America, England and Bohemia.

Harttina Hall and Clarke. Centronella-like shells with a high dorsal
median septum and the descending branches of the loop laterally fringed with
irregulär ly set spinules. Carboniferous ; North America and Brazil.

(?) CryptacantUa White and St. John.
Upper Carboniferous ; North America.

Subfamily B. Dielasmatinae, novum.

Berived Faleozoic Terebratulidae with
short loops. Often there are cruralia present.
Shells smooth or coarsely plicate. Devonian
to Permian.

Eunella Hall and Clarke. Like Dielasma
but without a cruralium. Devonian ; North
America.

Dielasma King (Epithyris King, non
Phillips) (Fig. 598). Dental lamellae
strong. „To the divergent crural plates is attached a shallow, often quite long,
free or sessile cruralium. Devonian to Permian ; Europe, India and America.

Dielasma elongatum (Schloth.). Permian; Hum
bleton, England. A, Dorsal and anterior views
1/1. B, Interior of conjoined valves, greatly en
larged (after Davidson).

CLASS TT

BRACHIOPODA

403

Girtyella Weller. Like Dielasma, but the cruralium is supported by a
septum. Lower Carboniferous ; North America.

Dielasmoides Weller. Like Girtyella, but with septal plates instead of
crural lamellae. Lower Carboniferous ; North America.

Cranaeiui Hall and Clarke. Dental lamellae strong. Socket plates
uniting into a hinge-plate which is posteriorly perf orate ; no cruralium.
Devonian and Lower Carboniferous. Subgenera : Hamburgia and Dielasmella
Weller. Lower Carboniferous, North America.

Dielasmina Waagen. Plicated Dielasmids. Carboniferous ; India.

Beecheria Hall and Clarke. Like Dielasma, but without dental lamellae ;
cruralium completely sessile. Carboniferous ; North America and India.

Bowleyella Weller. Both valves with median septa. Lower Carboniferous ;

North America.

Heterelasma Girty.

Smooth Dielasmids with a ventral fold and a dorsal

smus.
Texas.

Median septa in both valves. Hinge-plate rudimentary. Permian ;

Hemiptychina Waagen. Plicated Dielasmids without dental plates. Carboni-
ferous to Permian ; India.

Notothjris Waagen (Eostranteris Gemmellaro). Coarsely plicate biconvex
Shells with a perforate hinge-plate as in Centronella. Permian ; India.

Subfamily C. Terebratülinae Dali.

A median unpaired coiled arm

Post-Paleozoic TerehratuUdae with a short loop.
exists in Recent genera. Triassic to Recent.

Terehratula Müller 1776 (as redefined by Buckman 1907) (Fig. 599).
Genotype Anomia terehra-
tula Linn. Pliocene. Large
biplicate shells of the Ter-
tiary of Europe.

Musculus Quenstedt.
Buckman states that this
term will be useful for the
Cretaceous biplicate species.
Genotype Terehratula acuta
Quenst. Europe.

Epithyris Phillips, non
King. Buckman uses this
genus for a small group
of Jurassic biplicate forms.
Genotype Terehratula maxil-
lata Sowerby. Europe.

Ehaetina and Zugmeyeria Waagen. These genera comprise biplicate
forms. Trias ; Europe.

Pygope Link (Diphyites Schröter) (Fig. 600); Antinomia Catullo ; and
Pygites de Haan (as redefined by Buckman 1906). Three independent genera,
according to Buckman, with the shells originally bilobed, the two lobes often
uniting anteriorly in adult specimens, but leaving posteriorly a median
hollow Space passing through both valves. Developed out of a Glossothyrid-
like form. Jurassic ; Europe.

Fig. 599.

Terehratula phillipsi
Morris. Middle Jura ; Egg,
near Aarau, Switzerland. i/i.

Pygope diphya (Colonna). Tithonian ;
Trent, Tyrol. l/l-

404

MOLLUSCOIDEA

THYLUM V

Fropygope Bittner. Triassic ; Europe.

Didyothyris Douvillö (Fig. 601); Glossotky r is IdoviYiWii (Fig. 602); Pseudo-
glossothyris Buckman ; (?) DiscuUna Deslong. All from the European Jura.
Liothyrina Q^hlert (Liothyris Douville) (Fig. 603). Tertiary to Recent.
Terebratulina d'Orb. (Fig. 604). Jurassic to Recent ; distribution general.
Chlidonophora Dali. Deep-sea Terebratulinae. Recent.

Subfamily D. Dyscoliinae Beecher.

Post-Paleozoic Terebratulidae with the loop short and no coiled median arm.
(?) Cretaceous, Recent.

B C

Fig. 602.

Glossotliyris nucleata (Schloth.).
Upper Jura ; Bngelhardsberg,
Franconia. i/j.

Didyothyris coarctata (Park.). Great Oolite ; Bath, England. A-C, Tliree
Views of the natural size. D, Portion of outer surface, enlarged.

Fig. 603.
Liothyrina vitrea (Linn.). Recent ; Mediterranean. i/^.

Fig. 604.

Terebratulina suh-
striata (Schloth,).
Upper Jura ; Nat-
theim, Würtem-
berg. Vi-

Dyscolia and Eucalathis Fischer and (Ehlert. Recent.
(?) Ägulhasia King. Small TerehratuUna-like shells with the ventral beak
greatly elevated and a triangulär false cardinal area. Cretaceous to Recent.

Division B. Terebratelloids.

Terebraiulacea with the loop supported hy a

dorsal septum throughout
life, or only in the younger stages. Brachial cirri direded inwards during larml
This section has two phyla having a common origin, now geographically
' in two provinces, one austrat, the other horeal.

Family 1. Terebratellidae King (emend. Beecher).

Terebratelloids with the loop in the higher genera composed of two primary and
two secondary lamellae, passing through a series of distind metamorphoses white
attached to a dorsal septum. Devonian to Recent.

I

BRACHIOPODA
Subfamily A. Megathyrinae Dali (emend. Beecher).

405

Terehratellidae in luhich the loop is composed of descending hranches only, passing
in the highest genus through stages correlative with Gwynia, Argyrotheca and
Megathyris. The lower genera do not complete the series, The original stock for the
two following suhf amilies. Jurassic to Recent.

Gwynia King. Minute, elongate-oval, smooth shells with a short, nearly
straight hinge-line. Neither septa
nor loop. Brachia primitive, consist-
ing of a circlet of cirri. Eecent.

Zellania Moore. Minute shells
without a loop, but with a median
septum in each valve. Lias ; Europe.

Argyrotheca Dali (Cistella Gray)
(Fig. 605). Externally like Mega-
thyris, but without lateral septa.
Cretaceous to Recent ; Europe.

Megathyris d'Orb. {Argiope Des-
long.) (Fig. 606). Transversely elongate, plicate shells with long and
straight hinge-line. Dorsal valve with three or five septa, causing the
brachidium to have four lobes. Jura to Recent ; Europe.

Fio. 605.

Argyrotheca bilo-

cularis (Desl.).

Cfinomanian ; La

Manche, i/i.

Megathyris (lecollata (Chem.).
Cent; Mediterranean. Interior of
dorsal valve. 4/j (after Davidson).

Subfamily B. Dallininae Beecher.

Terehratellidae with the loop composed of descending and ascending lamellae,
passing in the highest genera through metamorphoses comparable to the adult structure
of Platidia, Ismenia, Muehlfeldtia, Terebratalia, and Dallina. The lower genera^
therefore, do not progress to the final stages. Jura to Recent. Recent genera
restricted to boreal seas.

Platidia Costa {Morrisia Davidson). Small, smooth, biconvex shells with
a large pedicle opening common to both valves. In the dorsal valve there

is a high vertical
plate to which are
attached the de-
scending branches;
ascending branches
not represented.
Recent.

Ismenia King.
Coarsely plicate
Shells with the loop
consisting of fim-
briate descending
branches and
simple ascending
branches. Jura.

Fin. 607.

Trigonellma pectuncula (Schloth.)- Upper
Jura ; Engelhardsberg, Franconia. A-C\
Shell of the natural size. D, E, Two.views
of loop, enlarged.

Fio. 608.

Mvehlfeldtia truncata (Gemni.).
Recent ; Mediterranean. Interior
of dorsal valve. c, Crura;(Z, Dental
socketa ; e, Jugum ; /, l, Ascending
and descending branches of loop ;
p, Process attached to median sep-
tum ; pr, Cardinal process ; S,
Median septum.

Trigonellina Buckman (Fig. 607). Jurassic ; Europe.
Muehlfeldtia Bayle (Megerlea King) (Fig. 608). Jura to Recent.

406

MOLLUSCOIDEA

PHYLÜM V

Frenulina Dali. Subgenus of Muehlfeldtia. Recent.

Terebratalia Beecher. Shell when adult like Terebratella, but passing
through a quite different series of metamorphoses. E-ecent.

Dallina Beecher. Elongate Terehrataliae with a small cardinal process and
a ventral median sinus. Tertiary to Recent.

Macandrevia King. Elongate Terehrataliae with dental plates and no
cardinal process. Recent. A subgenus of Budesia, according to Dali.

Laqueus Dali (Frenula Dali). Like Terebratalia, but the loop has two
lateral processes connecting the ascending and descending branches. Recent.

Fig. 609.
A, B, Kingeim lima (Defr.). Cretaceous ; England. Lateral and frontal aspect of loop, enlarged (after
Davidson). C, Specimen froni the Galeritenpläner of Salzgitter, i/^. D, Bxternal surface, enlarged. E, F,
Kingena friesensis (Schriifer). Upper Jura ; Gruibingen, Würtemberg. i/i. c, Crnra ; d, Dental sockets ;
e, Jugum ; /, l, Ascending and descending branches of loop ; j, Cardinal process ; r, Point of recurvatiire of
loop ; S, Median septum.

Kingena Davidson (Kingia Schloenbach) (Fig. 609). Cretaceous ; Europe
and North America.

PseudoJcingena Böse and Schlosser. Cretaceous ; Europe.

Lyra Cumberland (Terebrirostra d'Orb.) (Fig. 610). Cretaceous; Europe.

Fio. 610.

Lyra neocumiensis (d'Orb.).
Lower Cretaceous ; Morteau,
Doubs. Natural size.

Fig. 611.

A, Trigonosemus elegans Koenig. White Chalk ;
England. Interior of dorsal valve, enlarged (after
Davidson). B, T. palissyi Woodw. Upper Cretace-
ous ; Ciply, Belgium. i/i.

Trigonosemus Koenig (Fissurirostra, Fissirostra d'Orb. ; Delthyridea King)
(Fig. 611). Cretaceous; Europe.

ificro^^m Deslongchamps (Fig. 612); Orw^Mk Deslongchamps ; Zeilleria
Bayle. Jurassic genera ; Europe.

Äulacothy ris DovcviW^ (¥ig. 613). Trias to Cretaceous; Europe. Eudesia
King ; Orthotoma and Trigonella Quenst. ; Flabellothyris Deslong. Jura ; Europe.

!LäSR II

BRACHIOPODA

407

Fimbriothyris and Epicyrta Deslong. Jura. Camerothyris Bittner. Trias.

Cincta Quenstedt. Jura. Antiptychina
Zittel. Jura. Plesiothyris Douvillö. Jura.
These are all European genera.

l\^^ // ^ Jf \\ 1 Hynniphoria ^uess; ICruratula Bittner;

I ^ ^ ' * /\ \\ * 1 Orthoidea Friren.

Fio. 612.

Microthyrls lagenalls (Schloth.). Cornbrash
Rushden, England. Vi (after Davidson).

Fic. 613.

Aulacothyris resupinata (Sow.). Middle Lias ; Ilminster,
England (after Deslongchamps).

Siibfamily C. Magellaniinae Beecher.

Terebratellidae with the loop composed of descending and ascending branches,
passing in the higher genera through metamorphoses comparable to the adult structure

Fig. 614.

Mayas pumilus Sow. White
Chalk ; Menden, near Paris. A,B,
Shell, i/i. Ü, Vectical section. D,
Interior of dorsal valve.

Fio. 615.
Coenothyris vulgaris (Scliloth.). Muschelkalk ; Wiirzbnrg. A,
Dorsal and anterior views, i/i- -ß> Loop enlarged and restored
from sections treated with acid (parfcly after Koschinsky).

of Bouchardia, Magas, Magasella, Terebratella and Magellania. The lower genera
become adult before reaching the terminal stages. Jura to Recent. Recent genera
restricted to austral seas.

Bouchardia Davidson (Fachyrhynchus King). Recent ; South Atlantic.

Magas Sowerby (Fig. 614). Cretaceous ; Europe. Pachymagas von
Ihering. Tertiary ; Patagonia. Magasella Dali. Recent. Coenothyris
Douville (Fig. 615). Trias; Europe.

408

MOLLUSCOIDEA

PHYLÜM V

Magellania Bayle {Wa

Terehratella d'Orb. {Delthyris Menke ; Ismenia King ; Waltonia Davidson)
(Fig. 616). Jura to Recent.

King; Neothyris Douville) (Figs. 534, 535,

617). Jura to Recent.

Bhynchorma (Ehlert. Cre-
taceous. Megerlina Deslong-
champs. Recent. Kraussina
Davidson (Kraussia Davidson,
non Dana 1852). Recent.
Mannia Dewalque. Miocene.
(?) Bhynchora Dalman. Cretace-
ous.

Superfamily 3.
SPIRIFERACEA Waagen.

Telotremata with the adult
j^^ brachia supported hy calcareous

Fig. 616.

Terehratella dorsata
(Lam.). Recent; Chili.

lA.

Fig. 61^

Magellania flavescens (Val.). ^.„ . . 7 . r^

Cent ;■ Australia. Interior of dorsal Spiral lamellae OT Spiralia. Or-
valve, somewhat enlarsed. j • • j. t

dovician to Jurassic.

The Spiriferacea are abundantly represented from the Silurian tö the Carboni-
ferous, during which time the jugum undergoes many and often rapid changes. The
brach idia in Zygospira are known to begin with a Gentronella-like loop, as in the
primitive Terebratulacea.

Family 1. Atrypidae Gill.

Divergent Spiriferacea with the crura directly continuous with the primary
lamellae, which diverge widely and have the spiral cones hetween them. Jugum
simple, complete, or incomplete. Ordovician to Devonian.

Subfamily A. Zygospirinae Waagen.

Primitive Atrypidae with a simple jugum, either posteriorly or anteriorly
directed. Spiralia with apices directed tovjard the median dorsal region. Ordovician
to Devonian.

Zygospira Hall (Anazyga Davidson ; Orthonomaea
and Schuchert ; Protozyga Hall and Clarke) (Fig.
618). Like Atrypa, but small, and the spirals
composed of fewer coils. Jugum a simple con-
necting band, situated rather anteriorly. Sur-
face sharply plicate, never lamellose. Ordovician
and Silurian ; North America.

Catazyga Hall and Clarke. More rotund and
finely striated than Zygospira, with the complete
jugum decidedly posterior in position. Ordo-
vician and Silurian ; North America.

Atrypina Hall and Clarke. Primitive Atrypae
with few plications, and but three or four
volutions in each spiral. Jugum as in Atrypa,

Hall : Hallina Winchell

Fig. 618.

Zygospira modeffta Hall. Ordovician
Cincinnati, Ohio. «Vi (after Hall).

CLASS II

BRACHIOPODA

409

but contiriuous. Late Ordovician to Devonian ; North America and
Euroj^e.

Glassia Davidson (Fig. 619). Small, smooth shells, with the apices of the
laterally compressed spirals situated at the centre of
the brachial cavity. Jugum similar to that of Atrypina.
Ordovician to Devonian ; Europe and America.

Subfamily B. Atrypinae Waagen.

Terminal Atrypidae with the jugum situated extremely
posteriorly, complete in young stages, but at maturity dis-
continuous. Spiralia dorso-medially directed, Late Ordo-
vician to Devonian.

Atrypa Dalman {Spirigerina d'Orb.) (Fig. 620). sifuS"; WeÄÄS:
Shell radially plicated, usually with lamellar expansions J"^'^"'g of dorsal vaive. s/^
or hollow spines. Spirals introverted, dorso-medially
directed. Jugum extremely posterior in position, and complete in young

Fio, 619.

Fig. 620.

Atrypa reticularis (Linn.). Middle Devonian; Gerolstein. Eifel. ^, Umbonal aspect of adultspecimen. B,
Ventral aspect and profile of young shell. C, Interior of dorsal valve, showing spiralia, crnra, and jugum.
D, Ventral valve, showing muscular and vascular impressions. a, Adductors ; c, Diductors ; d, Deltidial plates ;
o, Ovaries ; p, Pedicle muscle.

stages ; but mesially absorbed at maturity. Widely distributed in the late
Ordovician, Silurian and Devonian.

Grueneivaldtia Tschernyschew. Atrypa-like shells, but with the relative
convexity of the valves reversed. Devonian ; .Russia.

(?) Karpinshya Tschernyschew. Elongate, Atrypa-like shells, with a median
dorsal septum. Devonian ; Russia.

(?) Glintonella Hall and Clarke. Silurian ; North America.

Fio. 621.

Daiiianavicitla (ßow.). Silurian; Lud-
low, Shropshire. s/o (after Davidson).

Subfamily C. Dayiinae Waagen.

Derived Atrypidae with the jugum drawn out
posteriorly into a simple short process. Spiralia
laterally directed.

Dayia Davidson (Fig. 621). Small smooth
shells, with the jugum situated anteriorly, and
drawn out posteriorly into a simple short process.
Spiralia laterally directed. Silurian ; Europe.

410 MOLLUSCOIDEA phylüm v

Family 2. Oyclospiridae, noviim.

Primitive Spiriferacea with the crura directly continuous with the hases of the
primary lamellae, which are closely set and nearhj parallel. Spiralia very dightly
introverted and of hut three or less volutions ; no jugum present. Middle Ordovician.

Cyclospira Hall and Clarke. Small, smooth, rostrate shells, with a deep
ventral and a shallow dorsal valve. Dorsal hinge-plate supported by a median
septum. Middle Ordovician ; North America.

Family 3. Spiriferidae King.

Derived Spiriferacea with the crura directly continuous with' the hases of the
primary lamellae, which are situated hetween the laterally directed spiralia. Jugum
simple, complete, or incomplete. Silurian to Jurassic.

Subfamily A. Spiriferinae, novum.

Spiriferidae with the jugum discontinuoiis at maturity, represented by two short
jugal processes, one attached to each primary lamella. Shell structure with scattering
perforations, hut never regularly punctate. Silurian to Permian.

Spirif er Bowerhy. This name has been made to cover a vast number of
Paleozoic Brachiopods having a more or less alate form, a multiplicate surface,
and terminally directed spiralia. Yarious attempts have been made to group
the species into phyletic series, but as there is present more or less of homoeo-
morphic development a completely satisfactory arrangement is not yet at
band. The following scheme is of tentative character.

Spirifer Sowerby sensu stricto {Fusella M'Coy) (Fig. 622, A). Transverse,
usually alate Spirifers with the entire shells more or less closely plicate ;
plications simple or dichotomous. Short dental plates developed, but no high
median septa in either valve. Genotype Anomites striatus Martin. Section
Aperturati Hall and Clarke. Devonian to Permian ; distribution general.

Section Spiriferella Tschernyschew. , A group of subquadrate Spirifers
suggesting S. cameratus, but with the surface finely papillose. Ventral shells
very thick, with strong dental plates. Upper Carboniferous ; Urals, Alaska
and North America.

Section Trigonotreta Koenig. Early, coarsely plicate Spirifers in which
the plications are simple and not dichotomous. Genotype S. aperturatus
Schlotheim. Devonian ; Europe and America.

Section Choristites Fischer (Fig. 622, D). Quadrate Spirifers that are
decidedly multiplicate and have long dental plates. Genotype S. mosquensis
Vern. Carboniferous ; Europe and America.

Section Dzieduszychia Siemiradz. Large short-hinged Spirifers with a
plicate sinus in either valve. Genotype Terehr. hielcensis Roemer. Middle
Devonian; Europe.

Section Brachythyris M'Coy. Rounded, tumid, short-hinged Spirifers, with
broad and depressed plications tending to be absent on fold and sinus.
Genotype S. ovalis Phillips. Carboniferous ; Europe and America.

Subgenus Adolfia Gürich (Fig. 622, B, G). Quadrate to alate, multiplicate
but not dichotomously plicate Spirifers, that have no plications on fold or
sinus ' (rarely, the fold is bilobed and then there may be a plication in the
sinus). Surface pustulose or finely pustulo-striate. Dental plates short ; no
ventral median septum. Genotype aS^. deflexus Roemer. Section Ostiolati

HP

^Hlärs II

BEACHIOPODA

411

Hall and Clarke. Essentially Devonian but persisting into Carboniferous ;
distribution general.

Subgenus Syringothjris Wiiichell (Syringopleura Schachert). Like Adolfia^
'but usually Avith large and erect ventral cardinal areas, and always with an
internal tube or syrinx, situated in the delthyrium. Upper Devonian and
Lower Carboniferous ; widely distributed.

Fig. 622.

A, Spirifer striatus (Martin). Lower Carboniferous ; Ireland. Portion of dorsal valve removed, showing
spiralia, 3/^ (after Davidson). B, S. (Adolfia ?) speciosus (Schlotli.). Devonian ; Eifel. Vi- f'. S. (Adolfia ?)
macropterus (Goldf.). Devonian ; Coblenz. Mould, i/]. D, S. (Choristites) mosqnensis Veni. Middle Carboni-
ferous ; Moscow. E, Same, interior of ventral valve, i/i. 2'. Pseudodeltidium ; x, Dental plates.

Subgenus Syringospira Kindle. Like Syringothyris, but with a striate fold
and sinus. Upper Devonian ; New Mexico.

Subgenus DeUhyris Dalman. Small early Spirifers that are coarsely plicate
except on the fold and sinus. Surface lamellose ; the imbricating lamellae
marked with very fine radiating Striae which do not terminate in spines.
Short dental lamellae present along with a more or less high ventral median
septum. ' Resemble Spiriferina, but the shell structure is not finely and
regularly punctate. Genotype D. elevata Dalman. Section Lamellosi-Septaii
Hall and Clarke. Silurian and Devonian ; distribution general.

Subgenus Uospirifer, novum. Quadrate or alate early Spirifers that are
either smooth, radially undulate, or plicate, but without plications on fold and
sinus. Surface with additional fine, filiform, radiating Striae which may be
minutely crenulate or granulöse. Dental lamellae present. Genotype Bpirifer
radiatus Sowerby. Section Radiati Hall and Clarke. Essentially Silurian
but persisting into Lower Devonian ; distribution general.

412 MOLLUSCOIDEA phylum v

Dalman (Fig. 623). Distinguished from Spirifer by having an
unusually high ventral area, with its narrow delthyrium closed by a perforated
pseudodeltidium, resulting from fused deltidial plates.
Silurian to Devonian ; Europe and North America.

Siibfamily B, Reticüläriinae Waagen.

Spiriferidae with a spinöse surface. Spiralia prdbahly
as in Triqonotretinae. Late Silurian to Permian.

Cyrtia exporreda (Walil-

Naturai size!"^^ ' ° ^"' " Beticularia M'Coy. Spirifers without alations, and

generally without radial undulations. Surface with
imbricating lamellae that terminate in spines. Dental plates present.
Genotype B. reticulata M'Coy. Section Fimbriati {pars) Hall and Clarke.
Devonian to Lower Carboniferous ; widely distributed.

Subgenus Prosserella Grabau. Small early Eeticulariae with well-developed
parallel and closely set dental lamellae. Late Silurian ; North America.

Subgenus Sguamularia Gemmellaro. Like Beticularia^ but without dental
er septal plates. Carboniferous and Permian ; widely distributed.

Siibfamily C. Martiniinae Waagen.

Spiriferidae with a smooth surface. Spiralia prohally as in the Trigonotretinae.
Devonian to Permian.

Amhocoelia Hall. Small, concave, or plano-convex, usually smooth Spirifer-
like Shells. Four well-defined adductor scars near the anterior margin in the
dorsal shell. Devonian to Carboniferous ; North America and Europe.

Martinia M'Coy. Short-hinged Spirifers that in general have smooth or
concentrically marked exteriors, and rarely may be somewhat radially un-
dulate. No dental plates or median septa. Genotype Aiiomites glaher Martin.
Section Glahrati-Äseptati Hall and Clarke. Lower Carboniferous to Permian ;
distribution general.

Subgenus Martiniopsis Waagen. Like Martinia, but with well-developed
diverging dental and septal plates. Permian ; India.

Subgenus Mentzelia Quenstedt. Like Martinia, but with a prominent
ventral median septum. Triassic ; Europe.

Metaplasia Hall and Clarke. Smooth Spirifer-\\kQ shells, with a median
fold on the ventral valve and a sinus on the dorsal valve. Lower Devonian ;
North America.

Verneuilia Hall and Clarke. Small, smooth Spirifers, with a deep median
sinus and two pronounced angular divergent ridges on each valve. Devonian
to Carboniferous ; Europe.

Family 4. Suessiidae Waagen.

Spiriferacea with the crura directly continuous with the hases of the primary
Spiralia laterally directed. Jugum continuous and more or less V-shaped.
Shell structure highly punctate. Silurian to Jurassic.

Cyrtina Davidson (Fig. 624). Cydm-like shells, with the dental lamellae

CLASS II

BRACHIOPODA

413

converging and united with the median septum. Silurian to Lower Carboni-
ferous. Distribution general.

(?) Cyrtinopsis Scupin. Like Cyrtina, but shell structure is not punctate.
Devonian ; Germany.

Thecocyrtella Bittner. Very small, ventrally cemented, smooth-shelled
Cyrtinae. Alpine Trias. Cyrtotheca Bittner. Alpine Trias.

BiUnerula Hall and Clarke. Like Thecocyrtella^ but with the abbreviated

A, Cyrtina hcteroclyta(DefT.). Devonian ; Eifel. i/j. £, Shell with _

dorsal valv« mostly removed, showing spiralia, s/g (after Davidson). *^^'* ^^^'

C, Cyrtina carhonaria M'Coy. Lower Carboniferous ; Kendal, Ireland. Spiriferina rostrata (Sowerby).

i/i. Interior of ventral valve. The pseudodeltidium is removed to Middle Lias ; Ilminster. i/i (after

show the dental plates and median septum. Davidson),

dental plates uniting with the very high median septum, forming a transverse
platform beneath the united deltidial plates. Alpine Trias.

Spiriferina d'Orb. (Fig. 625). Like Spirifer, but with the shell substance
punctate, and a prominent ventral median septum. Loop simple, complete.
Carboniferous to Jura.

Suessia Deslongchamps. Similar to Spiriferina, but the dental plates not
extending to the bottom of the valve. Jugum with a median process. Jura ;
Europe.

Family 5. Uncitidae Waagen.

Spiriferacea with the crura directly continuous with the bases of the primary
lamellae. Spiralia laterally directed. Jugum as in Suessiidae. Just within the
posterior margin of the dorsal valve are concave pouch-like plates.
united and deeply concave. Shell structure impunctate,
Family anomalous. Devonian and Permian.

Uncites Defrance (Fig. 626). Shells rostrate, striate,
with the ventral beak long, frequently distorted and
arched. No cardinal area. Deltidial plates united,
forming a concave plate. Pouch-like plates just within
the margins of the dorsal valve. Devonian ; Germany.
Uncinella Waagen. Permian ; India.

Family 6. Rhynohospiridae Hall and Clarke.

Derived Spiriferacea with the bases of the primary
lamellae situated between the spiralia and sharply recurved
dorsally at their junction with the crura. Spiralia laterally
directed.

Deltidial plates

Fio. 626.

Uncites gryphus (Schloth.).

Jugum usually with a Single process that is ?oSf 'i/f"'^''^' "'*'

414

MOLLUSCOIDEA

PHYLUM V

Fig. 027.

A, B, Ptychospira ferita (von Buch). Devonian ; Gerolstein, Eifel. i/j.
D, RhyncJiospira scdteri (David.). Silurian ; Wenlock, Shropshire. C, In-

commonly recurved, but is sometimes bifurcated. Shells plicate and their structure
abundantly punctate. Silurian to Permian.

Bhynchospira Hall (Fig. 627, C, D). Rostrate, radially plicate shells with
a short curved hinge-line ; apex truncated by a circular pedicle opening.

Dorsal hinge-plate like
that of Trematospira.
Spirals with from six
to nine volutions.
Jugum V-shaped, ex-
panding apically and
terminating pos-
teriorly in an oblique
edge. Shell structure
punctate. Devonian
and Lower Carboni-
ferous; North America

terior ofdorsa'l valve. D, Median vertical section through both valves, 3/^ g^nd EurODe
(after Davidson). ^ ' .

Homoeospira Hall
and Clarke. Like the last, but dilFers in having a linear cardinal process
separating the crural plates. Jugum not apically expanded, but terminating
in an acute stem. Silurian ; North America.

Ptychospira Hall and Clarke (Fig. 627, A, B). Like Bhynchospira, but with
a few angular plications. The jugum has a long, simple process passing
outward between the coils to near the inner surface of the ventral valve.
Devonian to Lower Carboniferous ; North America and Germany.

Betzia King (Trigeria Bayle). Resembling Bhynchospira externally. The
ventral umbonal cavity has a split tube. The single process of the jugum
terminally forked. This genus formerly contained all shells having a retzioid
exterior. At present, however, but a single species is admitted. Devonian ;
Europe. ^

Hustedia Hall and Clarke. Externally like Eumetria,
but with coarse plications, and internally with a split
tube, as in Betzia. Spirals and jugum similar to those
of EuwMria, but with fimbria and spinules respectively.
Upper Carboniferous and Permian; America, Europe,
India and China.

Trematospira Hall. Transverse Bhynchospirae. Silu-
rian and Devonian ; North America.

ParazygaHsÄlai.ndClsi.Yke (Fig. 628). Like Trematospira,
but with the fine, simple ribs covered with very delicate,
short, hair-like spines. Devonian ; North America.

Eumetria Hall. Elongate terebratuliform shells with
numerous fine radiating Striae. Hinge - line short.
Dorsal hinge-plate very complicated. Jugum similar
to that of Betzia, but the terminally bifurcated process
is extended back ward at an abrupt angle, and termi- Pamzyga Ursuta (Haii).
nates just in front of the apices of the primary lamellae. tud?y!^T, shei°i"me natural
Shell structure punctate. Lower Carboniferous; North '^"*'- ^''«^"^e with dorsal

Fig. 628.

America and Europe.
Acambona White.

Carboniferous : North America.

valve partly broken open,
shovving spiralia. C, hinge-
line of ventral valve, enlarged
after Hall).

BKACHIOPODA

415

^^^RiASS II

^B Family 7. Meristellidae Hall and Clarke.

Derived Spiriferacea, with the bases of the primary lamellae situated between the
spiralia and sharply recurved dorsally at their junction with the crura. Spiralia
laterally direded. The jugum has a Single process that may remain simple or may
bifurcate ; the bifurcations, however, do not enter between the lamellae of the spiralia^
but recurve and join the jugal process near their origin. Shell usuülly smooth, but
sometimes finely hirsute, and the structure impundate. Late Ordovician to
Devonian.

Siibfainily A. Hindellinae Schuchert.

Primitive Meristellidae in which the jugum has a single process that is usuwUy
simple and rarely is sharply recurved terminally.

Hindella Davidson. Ovate or elongate, sub-equally convex, smooth,
meristelloid shells. The V-shaped jugum has a short, acute process. A
dorsal median septum present. Late Ordovician ; North America. Sub-
genus Greenfieldia Grabau. Has no median dorsal septum. Late Silurian ;
North America.

Whitfieldia Hall and Clarke. Externally sometimes like Hindella, but
usually the shells have a fold and sinus,
the spirals have more volutions, and the
jugal process is longer and curved.
Genotype W. nitida H. and C. Silurian
and Lower Devonian ; North America
and Europe.

Hyattidina, nom. nov. (Hyattella Hall
and Clarke, non Fer. 1821). Similar
to Hindella, but compactly sub-penta-
hedral, and without the dorsal median
septum. Late Ordovician and early England
Silurian ; North America.

Nucleospira Hall (Fig. 629). Sub-circular, biconvex shells with numerous
fine, short spinules. Jugum with a long, straight, simple process. Silurian
to Lower Carboniferous ; North America and Europe.

Fig. 629.
Nucleospira pisum (Sow.). Silurian ; Wenlock,
Interior of dorsal valve, B, Vertical
section through both valves, s/g (after Davidson).

Subfamily B. Meristellinae Waagen.

Specialised Meristellidae, in which the jugal process bifurcates and may remain

so or may continue to grow, forming two loops as in the handles of scissors.

Meristina Hall {Whitfieldia Davidson) (Fig. 630). Biconvex, smooth-
shelled. Jugal stem with a short bifurcation. Silurian; North America
and Europe.

Glassina Hall and Clarke. Like Meristina^ but with the bifurcations of
the jugum originating directly from its apex. Silurian ; England.

Meristella Hall. Externally like Merista, but without spondylia. Apex
of jugum with two annular processes. Devonian ; North and South America
and Europe.

MeristoSpira Grabau. Like Meristella, but with strong dental lamellae.
Hinge-plate perforated by a visceral foramen and the dorsal septum not united
with the hinge-plate. Late Silurian ; North America.

416

MOLLUSCOIDEA

PHYLÜM V

Charionella Billings. Similar to the last, but with a greatly modified
hinge-plate. Devonian ; North America.

Pentagonia Cozzens (Goniocoelia Hall). Meristellids with a broad, angular,

Ä B G

Fig. 630.

Meristina tumida (Dalra.). Silurian ; Gotland. A, Shell of the natural size. B, Interior of ventral valve.
C, Hinge-line and median septum of dorsal valve.

sharply limited, ventral sinus and abrupt lateral slopes. Dorsal valve with
a wide, rounded fold, divided by a narrow sinus and umbo-laterally with two
short flanges. Devonian ; North America.

Merista Suess (Camarium Hall) (Fig. 631). Like Meristella, but with a
spondylium. Silurian (?) and Devonian ; Europe and North America.

Fig. 631.

Merista hercuUa (Barrande). Devonian (F-^); Konieprus, Bohemia. A, External aspect of ventral valve,
broken away near the apex so as to show the "shoe-lifter jirocess," i/i- B, Fractured shcll showing median
septum ; spiralia destroyed (after Barrande). C, D, Frontal and lateral views of spiralia, slightly enlarged
(after Davidson).

Dicamara Hall and Clarke. Meristellids with a spondylium (" shoe-lifter
process ") and brachidium. Devonian ; Europe.

Dioristella Bittner. Similar to Meristella. Alpine Trias.

öamarospira Hall and Clarke. Like Meristella, but with a small spon-
dylium supported by a median septum, to which is attached only the pedicle
muscle. Devonian ; North America.

Family 8. Ooelospiridae Hall and Clarke.

Specialised Spiriferacea, with the primary lamellae as in the Meristellidae ; the
jugum has a single process which may remain simple and free, or articulate in a
ventral septal socket. Shells plicate, often lamellose, and the structure impuncfafe.
Silurian and Devonian.

Änoplotheca Sandb. {Bifida Davidson). Concavo-convex small shells with

3S II

BRACHIOPODA

417

few plications, crossed by fine, often imbricating growth lines. Jugum
originating iiear the mid-length of the primary lamellae, uniting and forming
a simple upright stem articulating in a cavity in the ventral valve. Dorsal
valve with a high median septum. Devonian ; Germany and France.

Coelospira Hall. Shells externally much like Atrypina, but with laterally
directed spirals. Jugum similar to that of Anoplotheca. Silurian and
Devonian ; America and Europe. Subgenus : Leptocoelia Hall. Larger shells
with coarser plications. Silurian and Devonian ; widely distributed.

Anabaia Clarke. Similar to Coelospira^ but with a highly convex dorsal
valve. Silurian ; Brazil and North America.

Vitulina Hall. Like Coelospira, but with few plications and a long
hinge-line. Plications covered with fine radiating lines or rows of pustules.
Devonian ; America and South Africa.

Family 9. Athyridae Phillips.

Specialised Spiriferacea, with the hases of the primary lamellae situated between
the spiralia and sharply recurved dorsally at their jundion with the crura. Spiralia
laterally directed. Jugum complete, F-shaped, with the apex drawn out into a simple
process which hifurcates ; this elongates and enters more or less extensively between the
lamellae of the spiralia. Shells smooth, lamellose^ or spinöse ; structure impunäate.
Devonian to Triassic.

Subfamily A, Athyrinae Waagen.

Primitive Athyridae, in which the single process of the jugum bifurcates. The
branches usually terminale between the first and second volutions of tJie spiralia.
Shells lamellose or spinöse.

A li c

Fio. 632.

Athyris concentrica (von Buch). A, Shell with dorsal valve partly removed.
i/i. C, D, Frontal and lateral aspect of spiralia (after Davidson).

Ji, Interior of dorsal valve,

Athyris M'Coy (Cleiothyris Phillips, 7ion King ; Spirigera d'Orb. ; Euthyris
Quenstedt) (Fig. 632).

Sub-equally biconvex shells with concentric growth lines extended into
lamellae. Ventral umbo not prominent, incurved, usually concealing the
pedicle opening and deltidial plates. Teeth supported by dental lamellae.
Hinge-plate of the dorsal valve perforated by a "visceral foramen." The
peculiar jugum of this genus is illustrated in Fig. 632, C, D. Devonian and
Carbonif erous ; distribution general.

Anathyris von Peetz. Athyrids with straight hinge-lines and a hidden
ventral area. Devonian ; Europe.

VOL. I

2 E

418 MOLLUSCOIDEA phylum v

Actinoconchus M'Coy. Athyrids with very wide, radially striate, concentric
lamellae. Carboniferous ; Europe.

Cleiothyridina Buckmaii (Cleiothyris King, non Phillips). Athyrids with con-
centric rows of flat spinules. Carboniferous and Permian ; distribution
general.

Composita Bronn (Seminula Hall and Clarke, non M'Coy). Genotype Spirifer
amhiguus Sowerby. Smooth-shelled Athyrids. Dorsal hinge-plate very pro-
minent. Carboniferous ; distribution general.

Comelicania Frech. Large, decidedly alate Athyrids with arigulated sinuses
in both valves. Alpine Upper Permian.

Janiceps Frech. Small, sharply triangulär Athyrids with angulated sinuses
in both valves. Alpine Upper Permian.

Spirigerella Waagen. Permian ; South America and India.

Amphitomella Bittner. Smoot'h - shelied
Athyrids with a double cardinal process and
median septa in each valve. Alpine Trias.

Tetraäinella Bittner (Plicigera Bittner)
(Fig. 633). Athyrids with four correspond-
ing ribs on each valve. Alpine Trias. Sub-
genus : Stolzenhurgiella Bittner. Alpine Trias.
^ , . „ .„.„,,,. X Pentadinella Bittner. Athyrids with five

Tetractmella tmgoiulla (ßc\\\ot\\Gim). ,. ., , ~ ^

Muschelkalk; Recoaro, italy.. i/i- corrcspoudmg ribs on each valvc. Uccurs in

the Alpine Trias.
Anomactinella Bittner. Athyrids with a number of angular alternating
ribs towards the anterior margins. Alpine Trias.

Pomatospirella Bittner. Small smooth shells having the contour of Dayia
or Cyclospira. Alpine Trias.

Subfamily B. Diplospirellinae Schuchert.

Specialised Athyridae {out of the Athyrinae), with the jugal bifurcations very
long, lying hetween the volutions of the spiralia, and continuing with these to their
outer ends. Sometimes there is an additional jugal process which articulates with the
ventral valve, or recurves and joins the jugum. Devonian to Triassic.

Kayseria Davidson. Lenticular, plicated shells with a median plicated
sinus on both valves. Jugum with a ventral articulating process and the
bifurcations continued between the spiral ribbons to their outer ends.
Devonian ; Germany. *

Diplospirella Bittner. Athyrids with the jugal processes coextensive
with the principal spiral coils. Alpine Trias.

Pexidella Bittner. Athyrids difFering from Diplospirella in that the
jugum is much reduced and situatedj^in the umbonal region. Valves much
thickened in the apical region. Alpine Trias.

Euractinella Bittner. Diplospirellids with short corresponding ribs.
Alpine Trias. Didymospira. Salomon. Alpine Trias.

Anisactinella Bittner. Diplospirellids with alternating ribs, The
secondary spiral coils give off a process which returns and joins the jugum.
Alpine Trias.

I CLÄSS II

m

BKACHIOPODA

419

Su1)family C. Koninckininae Waagen.

Highly specialised Athyridae with jugum and spiralia essentially as in Diplo-
spirellinae. The spiralia, however, are not laterally direäed as in the former group,
hut point ventrally, this being due to the concave form of the dorsal valve. Triassic
and Jurassic.

KonimUna Suess (Fig. 634). Shell sub-orbicula^r, concavo-convex, smooth,
with a straight hirige-line, or strophomenoid in external appearance. Car-
dinal area obsolete at maturity. The accessory spirals take their origin

Fig.- 634.

Koninckiiia leonhardi (Wissm.). Upper
T*rias ; St. Cassian, Tyrol. A, Shell show-
ing spiralia, enlarged. B, Ventral and
dorsal aspects, Vi-

Fig. 635.

AmpMclinafVfith re-
stored brachidia (after
Bittner).

Fig. 636.

Thecospira haiditigeri (Suess).
Rhaetic ; Starhemberg, Austria.
A, Ventral valve, Vi- B, C,
Brachidia, enlarged (after Zug-
meyer). '

from the upper surface of the jugum, and are coextensive with the primary
spirals. Trias ; Europe.

Amphidina Laube (Fig. 635). Like Koninckina, but sub-trigonal in out-
line, and with well-developed cardinal area and deltidial plates. Trias and
Jura ; Europe.

Koninckella Munier -Chalmas. Similar to Amphidina, but with well-
developed cardinal process. Trias and Jura ; Europe.

Amphidinodonta Bittner. Like Amphidina, but with interlocking denti-
culate ridges and tubercles within the margins of the valves. Alpine Trias.

Koninckodonta Bittner. Like Koninckina, but with prominent cardinal
areas and a row of sub-marginal thickened tubercles on the interior of the
ventral valve, which interlock with similar callosities on the dorsal valve.
Alpine Trias.

Thecospira Zugmeyer (Fig. 636). Ventrally cemented Koninckininae with
well-developed cardinal area and cardinal process. Alpine Trias.

Range and Distribution of the Braohiopoda.

Owing to their great abundance, world-wide distribution and remote
antiquity, as well as their excellent state of preservation, Brachiopods occupy
a very conspicuous rank among extinct Invertebrates, and furnish us besides
with a large number of important stratigraphic index fossils. The composi-
tion of their shells, usually of calcite, enables them to resist the destructive
action of the fossilisation process more successfully than the shells of Mollusks,
many of which are composed wholly or in part of aragonite. Their value
as index fossils, however, is somewhat lessened owing to the difficulty of
identifying numerous genera, without a knowledge of their internal structure,
and this is often difficult to ascertain.

420 MOLLUSCOIDEA phylum v

Three of the four Orders into which the class is divided are represented in
the lowest Cambrian, or Olenellus zone, indicating that Brachiopods had their
origin in pre-Cambrian times. In the Lower and Middle Cambrian, the
Atremata and Neotremata predominate ; and although the Protremata are known
in the Lower Cambrian by very typical species, it is not until the Upper
Cambrian that the order becomes conspicuous. They are particularly char-
acteristic of the Paleozoic. The Telotremata do not appear until the Middle
Ordovician and since Silurian times have always been prolific, but are
especially characteristic since early Mesozoic times.

In the Lower Cambrian (Olenellus beds), 22 genera of Brachiopods are
represented, occurring both in North America and in Europe. A marked
increase is apparent in the Middle Cambrian, for here Walcott records 37
genera, and in the Ordovician and Silurian, where the climax of their diversity
is reached, upwards of 3000 species are known. These are distributed chiefly
in North America and in Europe (Great Britain, Scandinavia, Bohemia,
Russia and Portugal) ; but numerous forms are also found in South America,
Australia, China and eastern Siberia.

In the Devonian, Brachiopods are scarcely less plentiful than in the Silurian,
although a considerable number of genera, especially those belonging to the
Atremata and Neotremata, have now disappeared. The most noted European
localities where Brachiopods abound are the Eifel, Rhineland, Westphalia, the
Hartz, Belgium, Devonshire, Boulogne-sur-Mer, Cabrieres in the Cevennes,
the Asturias and the Urals. North America also yields great quantities of
Devonian Brachiopods.

The Carboniferous of North America and its equivalent horizons in Europe
and Eastern Asia, together with the Permian of the Mediterranean countries,
India and Armenia, are very rieh in Brachiopod remains, especially those
belonging to the Produdidae, Strophomenidae, Spiriferidae and Rhynclionellidae.

In the North European Permian, the number of species of Brachiopods is
reduced to about 30, but in the Salt Range of India far greater numbers
occur. In the Alpine Trias, the Terehratulidae, Rhynchonellidae and Koninck-
ininae attain a great development.

The Jurassic and Cretaceous Brachiopods belong almost exclusively to
the Terehratulidae, Rhynchonellidae and Thecidiidae ; the first two families in
particular being represented by an astonishing number of species. The
Spiriferacea become extinct in the Lias.

With the beginning of the Cenozoic era, Brachiopods are no longer a con-
spicuous group of fossils. The species occurring in the Tertiary are almost
without exception generically identical with those now living, and scarcely
exceed them in number. On this account they are devoid of practical interest
or importance to the geologist.

Phylum VI. MOLLUSCA.'

(Malacozoa Blainville ; Saccata Hyatt.)

The Mollusca form a well-characterised, and, on the whole, remarkably
homogeneous group of Invertebrates, which have existed since the earliest
recognised advent of life upon the globe. Their progressive modifications
afFord us a most important guide to the successive stages of the evolution of
organic life as preserved in the various geological horizons.

The Mollusca are characterised as a group by passing through a Trocho-

^ Literature : Adams, H. and A., The Genera of Recent Mollusca, 2 voLs. London, 1853-58. —
Philippi, R. A., Handbuch der Conchyliologie, Halle, 1853. — Keferstein, W., Die Malacozoa.
Bronn's Classen und Ordnungen des Thierreichs, vol. iii., 1862-66. — Tryon, O. W., and Pilsbry,
H. A., Manual of Conchology, 16 vols. Philadelphia, 1879-96. — Fischer, P., Manuel de Con-
chyliologie et de Paleontologie conchyliologique, 1880-87. — Woodward, S. P., Manual of the
Mollusca. 4th Edition, with Appendix by R. Täte, 1880. — Tryon, G. W., Stnictural and Syste-
matic Conchology, 3 vols. Philadelphia, 1882-84. — Ihering, H. von, Le Systeme naturel des
Mollusques. Bull. Sei. France, 1891, vol. xxiii. — Pelseneer, P., Introduction ä l'etude des
Mollusques. Brüssels, 1894.

Soioerhy, J., Mineral Conchology of Great Britain, 7 vols. London, 1812-30. — Brocchi, G. B.,
Conchiologia fossile subappenina, 2 vols. Milan, 1814. — Deshayes, G. P., Coquilles fossiles des
environs de Paris, 3 vols., 1824-37. — Goldfuss, A., Petrefacta Germaniae, 1826-40. — Conrad, T. A.,
Fossil Shells of the Tertiary Formations of North America (1832-33) ; and Fossils of the Medial
Tertiary of the United States (1838-61). Reprints by G. D. Harris, \^^Z.— Morton, S. G., Synopsis
of the Organic Remains of the Cretaceous Group of the United States, 1834. — Philippi, R. A.,
Enumeratio Molluscorum Siciliae, 2 vols., l^^Q-ü.—Grateloup, J. P. S., Catalogue zoologique du
Bassin de Gironde. Bordeaux, 1838-40. — Hall, J., Palaeontology of New York, vols. i.-viii.
Albany, 1847-95. — Wood, S., Monograph of the Crag Mollusca. Palaeont. Soc, 1848-56, vols. 1.,
ii.^ — Sandherger, G. and F., Die Versteinerungen des rheinischen Schichtensystems in Nassau,
1850-56. — Morris and Lycett, Monograph of the Mollusca of the Great Oolite. Palaeont. Soc,
1850-63. — M^Coy, F., British Palaeozoic Fossils. London, 1851-55. — Pictet, F. J., and Campiche,
G., Description des fossiles du terrain cretace de Sainte-Croix. Paleont. Suisse, ser. 5, vols. i.-iv.,
1858-72. — Quenstedt, F. A., Der Jura. Tübingen, 1858. — Sandherger, F., Die Conchylien des
Mainzer Beckens. Wiesbaden, 1860-63. — Deshayes, G. P., Description des animaux sans vertebres
decouverts dans le Bassin de Paris, 5 vols. Paris, 1860-66. — Loriol, P. de, Monographs of the
Fauna of the Upper Jura of Switzerland, Haute-Marne, Yonne, Boulogne-sur-Mer, Valßn, Tonnerre ;
of the Neocomian of Mt. Saleve ; the Urgonian of Landeron ; the Gault of Cosne, etc., 1861-75. —
Cossmann, M., Essais de paleoconchologie comparee. Paris, 1895. — Gabb, W. M., Palaeontology of
California, vols. i. and ii., 1864, 1869.— Idem, Topography and Geology of Santo Domingo. Trans.
Am. Phil. Soc, 1873, vol. xv.— Geinitz, IL B., Die Dyas. Leipzic, 1864. — Ktminck, L. G. de,
Faune du calcaire carbonifere de la Belgique. Ann. Mus. d'Hist. Nat. Belg., 1886, vol. vi. — M'Coy,
F., Synopsis of the Characters of the Carboniferous Limestone Fossils of Ireland, 1862. — Meek,
F. JB., Report on the Invertebrate Cretaceous and Tertiary Fossils of the Upper Missouri Country.
U.S. Geol. Surv. Terr., 1876, vol. ix. — Waagen, W., Salt Range Fossils. Mem. Geol. Surv. India.
Palaeont. Indica, ser. 13, \880-9>7 . — White, C. A., Non-marine fossil Mollusca of North America.
3rd Ann. Rept. U.S. Geol. Survey, 1883.— Walcott, C. D., Fauna of the Lower Cambriau or
Olenellus Zone lOth Ann. Rept. U.S. Geol. Surv., 1890. — Whidhorne, G. F., Monograph of the
Devonian Fauna of the South of England. Palaeontogr. Soc, 1889-1907.— J/ee^, F. B., and
Worthen, A. H., Palaeontology of Illinois, 1866-75, vols. i.-vi.

421

422 MOLLUSCA phylum vi

sphere and a Veliger larval stage ; by possessing bilaterally symmetrical,
unsegmented bodies ; a larval shell gland, from which a Härder exoskeleton
or shell is secreted, though not always permanently retained ; a mouth,
intestinal canal and anus ; a closed, but partly lacunary circulation, assisted
by a heart with one or more auricles, and containing a usually colourless
body fluid or haemolymph ; a nervous System with at least three pairs of
ganglia connected by commissures ; sexual reproduction by ova and sper-
matozoa ; audition and equilibration provided for by otocysts ; respiration
by ctenidial or secondary gills, or by the tegumentary surface, which may be
invaginated to form a pulmonary sac ; locomotion by a muscular organ called
the foot, or by special parapodial structures, or by swimming; the organs
typically paired, and protected by a sac-like integument called the mantle ;
and the visceral sac having a tendency toward torsion, so as to become usually
asymmetrical. Sexually Mollusks are usually dioecious ; or, if monoecious,
are incapable of self-fertilisation.

Owing to the homogeneity of the group, its division into classes has been
attended with some differences of opinion, depending upon the point of view,
the anatomist laying more stress upon certain groups of characters, and the
morphologist upon others. From a general Standpoint, the Mollusca are
readily divisible into five classes, as follows : Pelecypods, Scaphopods,
Amphineura, Gastropods and Cephalopods. The first of these is well marked
ofF from the rest by the presence of a bivalved shell and the absence of a
distinct head and of a radula, and the two groups have been contrasted as
Aglossa (or Lipocephala) and Glossophora (or Cephalophora).

' Olassl. PELECYPODA Goldfuss.^

(Lamellibranchiata Blainville ; Conchifera Lamarck ; Bimlvia (Bonanni) Linn6 ;

Lipocephala Lankester.)

Aquatic, bilaterally symmetrical, acephalous Mollusks, protected hy a pair of
shelly valves, which are secreted by the lateral portions of the mantle, connected by an

1 Literature : Neumayr, M., Zur Morphologie des Bivalvenschlosses. Sitzungsber. Akad.
Wiss. Wien, 1883, vol. Ixxxiii,, and Denkschr. 1891, vol. Iviii,— üeber die Herkunft der Unioniden.
Sitzungsber. Akad. Wiss. 1889, vol. xcviii. — Beiträge zu einer morphologischen Eintheihmg der
Bivalven ; mit Vorwort von E. Suess. Denkschr. Akad. Wiss. Wien, 1891, vol. Iviii. — White,
CA., Review of the fossil Ostreidae of North America, 4th Ann. Report U.S. Geol. Survey
(1883), 1S8A.— Jackson, R. T., Phylogeny of the Pelecypoda. The Aviculidae and their Allies.
Mem. Boston Soc. Nat. Hist., 1890, vol. iv. no. 8. — Minegaux, A., Recherches sur la circulation
des Lamellibranches marines, 1890. — Hyatt, A., Remarks on the Pinnidae, Proc. Boston Soc.
Nat. Hist., 1892, vol. xxv. — Moynier de Vülepoix, R., Recherches sur la formation et l'accroisse-
ment de la coquille des mollusques, 1893.— ^erwar^, F., Serie de notes sur le developpement et la
'morphologie de la coquille chez les Lamellibranches. Bull. Soc. Geol. France [3], 1895-97, vols.
xxiii. -XXV.— Dali, W. ff., Anew Classification of the Pelecypoda. Trans. Wagner Inst. Sei. Phila-
delphia, 1895, vol. iii. pt. 3. Also Proc. U.S. Nat. Mus., 1895, vol. xvii. no. 1Q^2.— Hyatt, A.
Terminology proposed for the Description of the Shell in Pelecypoda. Proc. Am. Assoc. Adv.
Sei., 1895, vol. xliv.— Fischer, ff., Resume des travaux de M. F. .Bernard sur le developpement
de la coquille des Pelecypodes. Journ. de Conch., 1897, vol. xlv., no. A.—March, M. C, General
Classification of the Pelecypoda. Ann. Mag. Nat. Hist., [8] 1912, vol. x.

A. On Paleozoic Forms : Barrande, J., Systeme Silurien du centre de la Boheme. Acephales,
i.-iv., 1882.— ßee«ie, /. W., Carboniferous Invertebrates. Kansas Univ. Geol. Surv., 1900, vol. vi.
—Clarke J. M., Naples Fauna in western New York. Mem. N.Y. State Mus., vi., 1900.— //aZ^, J.,
Geol. Surv. New York. Palaeont., vol. v., 1884-85.— /rZew, Whitfield, R. P., Meek, F. B., and
Ulrich, E. 0., Description of Palaeozoic Fossils. Palaeont. Ohio, 1873-75, vols. i., ii., and Geol.
Ohio, 1893, vol. \\\.~ffind, W., Monograph of the British Carboniferous Lamellibranchiata.

CLASS I PELECYPODA 423

elastic Wjament, and closed hy the contradion of musdes attadied to the inner faces of
the valves ; feeding hy ciliary adion and destitute of a radula or jaw ; breathing hy
lateral gills ; im'perfedly sensible to light and rarely provided with peripheral Visual
Organs ; possessing olfadory organs (osphradia)^ auditory and equilibrating organs
(otocysts), tadile papillae, and a nervous system composed of ganglia united hy nerves^
but without a pedovisceral commissure ; provided with an extensile, tadile or loco-
motor organ (foot) ; a circulatory system containing haemolymph, and operated hy a
Single or paired cardial ventricle and two aurides ; a more or less convoluted intestinal
ca7ial, with its oral and anal extremities at opposite ends of the hody ; a stomach ;
paired nephridia, conneded with the pericardium, and discharging independently of
the redum ; reproducing without copulation, hy ova and spermatozoa ; monoecious or
dioecious ; development external to the ovary ; the post-larval stage proteded hy a
prodissoconch, and sometimes exhihiting special nepionic stages.

External Charaoters. The Shell. — The embryonic Pelecypod is provided

Palaeoiit, Soc, 1896-1905. — Ulrich, E. 0., Lower Silurian Lauiellibranchiata of Minnesota. Rept.
Geol. Surv. Minn., 1897, vol. iii.

B. On Mesozoic Forms : Benecke, E. W., Die Versteinerungen der Eisenerzformation von
Deutsch - Lothringen und Luxemburg. Abh. Geol. Spezialkarte Elsass - Lothring., 1905, n.s.,
vol. V. — Bittner, A., Revision der Lamellibranchiaten von St. Cassian, Abh. Geol. Reichsanst.
Wien, 1895, vol. xviii. — Böhm, O., Die Bivalven der Stramberger Schichten. Paläont. Mittheil.
Mus. Bayer. Staates, 1883, vol. ii. — Borrissyak, A., Die Pelecypoden der Jura- Ablagerungen im
europaischen Russland. Mem. du cours geol., nouv. ser., 1904-9. — Broili, F., Die Fauna der
Pachycardientuffe der Seiser Alp. Palaeontogr., 1903-7, vols. 1., liv. — Coquand, W., Monographie
du genre Ostrea des terrains cretaces, 1869. — Healey, 31., The Fauna of the Napening beds
(Rhaetic) of Upper Burma. Palaeont. Indica, 1908, n.s., vol. ii., no. 4. — Holzapfel, E., Die
Mollusken der Aachener Kreide. Palaeontogr., 1887, vol. xxxiv. — Kitchin, F. L., The Jurassic
Fauna of Cutch. Lamellibranchiata. Palaeont. Indica, 1903, ser. ix., vol. iii., pt. 2. — Lavhe, O.,
Die Fauna von St. Cassian. Denkschr. Akad. Wiss. Wien, 1866, vol. xxv. — Pavloto, A., Enchaine-
ments des Aucelles et Aucellines du Cretace Russe. Nouv. Mem. Soc. Imper. Nat. Moscou, 1009,
vol. xvii. — Pompeckj, J. F., Über Aucellen und Aucellen - ähnliche Formen. Neues Jahrb. f.
Min., 1901, Supplem. vol. xiv. — Qiiaas, A., Beitrag zur Kenntniss der Fauna der obersten
Kreidebildung in der Lybischen Wüste. Palaeontogr., 1902, vol. xxx. pt. 2 — Stoliczka, F.,
Cretaceous Fauna of Southern India! The Pelecypoda. Mem. Geol. Surv. East India, 1871, vol.
iii. — Waagen, L., Die Lamellibranchiaten der Pachycardientuffe der Seiser Alp. Abh. Geol.
Reichsaust. Wien, 1907, vol. xviii. pt. 2. — Wood, H., Monograph of the Cretaceous Lamelli-
branchiata of England. Palaeont. Soc, 1899, vol. \m.~Zittel, K. A. von, Die Bivalven der
Gosaugebilde. Denkschr. Akad. Wiss. Wien, 1865-66, vol. xxv.

C. On Tertiary Forms : Androussov, JV., Fossile und lebende Dreissensidae Eurasiens. Trav.
Soc. Imp. Sei. Nat. St-Petersb., sect. geol., 1897, 1903, vols. xx., xxix. — Arnold, R., The
Tertiary and Quaternary Pectens of California. U.S. Geol. Surv. Profess. Papers, no. 47, 1906. —
Bellardi, L., and Sacco, F., 1 Molluschi terziari del Piemonte e della Liguria. Torino, 1872-1901. —
Cossvumn, M. , Catalogue illustre des coquilles fossiles de l'Eocene des environs de Paris. Fase.
Ann. Soc. Malacol. de Belgique, 1888-89, vols, xxiii., xxiv.—Idem, and Pissaro, ^ G., Iconographie
complete des coquilles fossiles de l'^^ocene des environs de Paris. Fase. 1, Pelecypodes, 1904. —
Dali, W. H., Contributions to the Tertiary Fauna of Florida, i.-vi. Trans. Wagner Inst. Sei.,
1890-1903, vol. in.— Deperet, G., and Roman, F., Monographie des Pectinides neogenesde l'Europe
et des regions voisiues. Mem. Soc. Geol. France, 1902, vol. x. — Fontannes, F., Les Mollusques
pliocenes de la Vallee de Rhone et du Roussillon. Lyons, 1879-83.— G^regrorto, A., Monographie
de la faune eoci'nique de l'Alabama. Palermo, 1890. — Ä^ams, G. D., Bull. Amer. Palaeont.,-
1895-97, vols. i.-iv. — Hoernes, M., Die fossilen Mollusken des Tertiärbeckens von Wien. Abhandl.
Geol. Reichsanst. Wien, 1870, vol. iv.—Koenen, A. von. Das norddeutsche Unter-Oligocän und
seine Mollusken-Fauna. Abhandl. Geol. Spezialkarte Preussen, 1889-93, vol. x.—Oppen}wim,
P., Zur Kenntnis alttertiärer Faunen in Ägypten. Palaeontogr., 1903-6, vol. xxx. pt. 3. —
Ortmann, A. E., Families and Genera of the Najades. Ann. Carnegie Mus., 1912, vol. viii. no.
x. — Sandherger, F., Die ■ Conchylien des Mainzer Beckens, 1860-63.— /rfm. Die Land- und
Siisswasser - Conchylien der Vorwelt. Wiesbaden, \9>n. — Schaff er, F. X., Die Bivalven der
Miocänbildungen von Eggenburg. Abh. Geol. Reichsanst. Wien, 1910, vol. xxW.— Simpson, C. J.,
Synopsis of the Naiades or Pearly Fresh-water Musseis. Proc. U.S. Nat. Mus., 1900, vol. xxii., no.
1205. — Ugolini, R., Monografia dei Pettinidi neogenici della Sardegna. Palaeont. Ital. 1906-7,
vols. xii., xnl— Wood, S., Monograph of the Eocene Bivalves of England. Palaeontogr. Soc,
1861-71.

424

MOLLUSCA

PHYLÜM VI

with a saddle-shaped, single shell gland, which secretes a pellicle of the same
form, lipon which, at two points corresponding to the valves, calcification sets
j j^ in independently. These rudiments remain con-

nected across the dorsum for a time, by the uncal-
cified portion of the original pellicle, which develops
into the ligament of the adult. The paired em-
bryonic shell, corresponding to the protoconch of
Cephalopods, has been named by Jackson the pro-
dissoconch (Figs. 637, 638). In general these valves
are very uniform in character, as seen on the tips
Compieted of the uneroded valves in the adult. They are
usually rounded or slightly pointed at the umbonal

Fio. 637.

Ostrea virginiana
prodissocouch stage, viewed from
the anterior end (A), and from
the right upper aide (B).
(after Jackson).

**^/i end, and have in their earliest stages a straight,
rather long hinge line. In Solemya the prodissoconch
is elongate, rounded at the ends, with the ventral and dorsal margins nearly
parallel, much as in the adult shell. In Pinna the prodissoconch is globular,
as in most bivalves. In Z7mo, Anodon and Philohrya, a second or nepionic

Fig. 038.

A, Avicula sterna. Young specinien, viewed from tlie left (a) and right (b) sides, the latter showing byssal
sinus. i9/i. B, Area pexata. Very young, showing prodissoconch (2>), succeeded by early dissoconch growth.
"i^/i (after Jackson),

stage is traceable, owing to a semi-parasitic habit of the young, which leave
the mother and become encysted on the fins or gills of fishes ; during this
period the shell remains stationary, though some development of the contained
soft parts is in progress.

The bivalve shell reduced to its lowest terms comprises two convex pieces
(the valves), attached to one another dorsally (1) by an elastic ligament usually
external to the cavity of the two valves; and (2) by muscles and connective
tissues which pass from the inner surface of one valve to the inner surface of
the opposite valve. The contraction of the muscles brings the margins of the
valves into close contact, thereby forming a hollow receptacle in which the
soft parts of the animal are enclosed, and from which all obnoxious foreign
matters may be excluded. The elasticity of the ligament, acting on the
principle of the C-spring, tends to separate the valves when the tension of
the internal adductor muscles is relaxed. The extension of the substance
of the valve is secreted by marginal glands around the edge of the investing
tissue or mantle, and is subsequently reinforced by material supplied by
secretion from the general surface of the mantle. As the animal grows and
the original prodissoconch becomes too small to cover the soft parts, the valves
are enlarged around the margins, so that each of them represents, fundament-
ally, a hollow cone. Since growth progresses more rapidly along some
portions of the mantle than at others, the cones necessarily become oblique,

CLÄSS I PELECYPODA 425

arched or cycloidally curved. The apex of the cone is formed by the beak
or umho of the valve, the base is the entire margin of the valve.

The shell of most Pelecypods is composed of several layers of distinct
structure. The external layer is usually thin, flexible and dark-coloured,
chiefly composed of a horny substance termed conchiolin. This layer is
known as the epidermis, or more properly the periostracum ; it is not easily
corroded, and hence serves as a protection to the underlying calcareous
layers. The outer calcareous layer is composed of prisms of calcite arranged
more or less perpendicular to the external surface ; the inner layer is made
up of thin, more or less parallel lamellae of porcellanous or pearly texture,
disposed at right angles to the general direction of the prismatic layer,
and exhibiting the mineralogical characters of aragonite (Fig. 639). Besides
the lamellar or prismatic
structure, many forms show
under the microscope
minute, sometimesbranched
tubulation.

The variations in shell
substance are somewhat
characteristic of diff'erent
groups. The prisms difFer p^^. 239

greatly in size, the larger Vertical section of the shell of Unio. e, b, a, a', the oiiter pris-

nppnrriTirr in hinnm-nmiiQ ':^n(\ «latic layer, showing successive increments of shell growth ; c, c',
OCCUrring m inoceramus ana ^.j^^ 1^^^^ lamellar strata. Highly magnified (after Carpenter).

Pinna, the smaller in the

Anatinidae and Myacidae. The prismatic layer is wholly absent in the
Chamidae and many other Teleodesmacea ; in the Pectinidae and Limidae
the prismatic layer is feebly developed and often recognisable only in young
Shells. In the Rudistae the prisms run nearly parallel with the outer surface.
As aragonite is more soluble than calcite, it frequently happens in fossil
Shells that the layers composed of the former mineral have entirely dis-
appeared, leaving only the calcitic layers. Pearls are merely loose portions
of the inner layer secreted by the mantle surface, usually around foreign
bodies which have reached the interior of the shell and set up Irritation there.

In the majority of Pelecypods the valves form a nearly complete defence ;
in borers, burrowers and a few degenerate types, the valves cover less and
less surface in proportion to that which is bare ; in a few the mantle is re-
flected so as to envelop more or less of the outer surface of the valves ; and
finally, in Chlamydoconcha, the valves are permanently internal, separately
encysted, with the ligament isolated and encysted between them. No
example is known of a Pelecypod absolutely destitute of valves in the adult
State.

The valves of the shell are in general substantially equal ; but sometimes
they are unequal, especially in sessile or sedentary forms ; and rarely they
are spirally twisted, as in Stavelia and Spirodomus. The hinge or articulus
comprises the whole articulating apparatus — hinge plate, teeth, ligament, etc. ;
the primitive hinge, which is coextensive with the ligament, is distinguished
by Hyatt as the cardo. The cardinal axis, or right line forming the axis of
revolution of the hinge, is parallel with the antero-posterior axis of the
animal (as determined by a line drawn through the mouth and posterior
adductor) in the ordinary Teleodesmacea ; but in the winged Prionodesmacea,

426 MOLLUSCA phylum vi

such as Ostrea^ Pedalion, etc., the two axes are at a considerable angle with each
other.

The dental armature is usually situated on the dorsal margin, which for
this reason is called the cardinaL margin. It comprises the teeth, or project-
ing processes and sockets, usually alternating in the single valve, and opposite
with respect to both valves. In the more modern and perfected types, the
Cardinal margin is reinforced by a vertical deposit of shell in the form of a
lamina called the hinge plate, upon which the teeth are set. Above the hinge
plate in each valve rise the beaks or umbones, which are usually curved
toward the anterior end of the shell (prosogyrate), but are sometimes directed
back ward (opisthogyrate) or outward (spirogyrate).

According to the ordinary terminology, the height of a Pelecypod is
measured on a vertical line from the beaks to the ventral margin ; the length
corresponds to the greatest distance between the margins parallel with the
antero-posterior axis above defined ; and the thickness, or diameter, is measured
by a line at right angles to the vertical plane descending from the cardinal
axis (Fig. 641). When the shell is placed with the oral end anterior, the
valves are termed right and left respectively, as viewed from above the
articulus. The portion of the shell anterior to the beaks is usually shorter
than that behind them, except in such forms as Donax or Nucula.

Viewed laterally, most Pelecypod valves may be divided into regions,
corresponding in the main to the Disposition of the internal organs. The oral
area extends from the anterior end of the cardinal line to the anterior side of
the pedal area. The latter is often marked by a swelling of the valves, and
sometimes by a sinus (Pholas) ; it extends backward to a point where the
branchial crest, radiating from the beaks, forms the anterior boundary of the
siphonal area. The dorsal or posterior limit of the siphonal area is marked by
an angle in the incremental lines ; and above this, extending to the posterior
end of the cardinal line, is the intestinal area. In the alate forms, like Fteria,
the wings usually called anterior and posterior are really, with reference to
the antero-posterior axis of the animal, dorsal and ventral.

In certain borers, the siphons are greatly produced beyond the valves, and
a calcareous tube is secreted, lining the burrow ; the valves, situated at the
anterior end of the boring, either lie free, or are partially or wholly fused
with the tube. In the Pholadidae the naked portions of the animal between
the edges of the valves are often protected by additional shelly pieces, which
are organically separate from the valves ; and some burrowers have the free
ends of the siphons protected by leathery or calcareous shields. In the
Teredinidae these shields are specially modified to protect the entrance of the
burrow, and are called " pallets."

Ornamentation. — The external ornamentation of the valves is always a
conspicuous character. It comprises (beside the concentric or incremental
lines which indicate the successive additions to the shell margin, and are
believed to coincide with resting stages during the process of growth) radial
or concentric Striae, ridges, ribs, folds, nodes, spines or foliaceous processes.
These are supposed to arise from temporary or permanent modifications of
the mantle margins, such as papillae, minute tentacular or proliferate
processes.

Above the hinge line, in archaic types, is an area often set off by an
impressed line and called the cardinal area. In the more perfected modern

OLASS I PELECYPODA 427

forms this area is commonly divided ; a heart-shaped space in front of the
beaks, and bounded by a ridge or groove, being known as the lunule; and a
more elongated space extending backward from the beaks being designated the
escutcheon. Both areas often have a special sculpture, differing from that of
the remainder of the shell.

Another form of ornamentation is sometimes found on the opposed inner
margins of the valves, away from the hinge line, as in Digitaria (Fig. 756),
or Transennella ; it probably aids in preventing a lateral displacement of the
valves. In general, all ornamentation may be confidently ascribed to a
dynamic origin.

Internal Characters. Soft Parts. — The Pelecypod body is enclosed
within two thin, partly fleshy mantle lobes, which are united or continuous
below the cardinal margin, and open or partially united at other points on
their periphery. Within the mantle lobes are the visceral mass including
the internal organs, the gills or denidia, the foot and the palpi. When the
mantle edges are united so as to form tubes for the entrance and discharge of
water, such tubes are called siphons. These organs, all of which have been
utilised in Classification, will be considered separately.

The mantle is closely applied to the surface of the valves, and is usually
attached to them along a line near its periphery. This line is indicated by a
continuous scar or Impression upon the inner surface of the valves, termed
the pallial line. Outside the pallial line a portion of the margin is free and
usually thickened. In it are contained the glands which secrete the shell,
and also pigment glands ; it is ornamented by papillae, tentacular processes,
etc., and is sometimes furnished with visual organs of a primitive sort.
Certain archaic forms had no distinct pallial line, the mantle being organi-
cally attached over a more or less irregulär area. The ends of the pallial
line are commonly continuous with the scars of the adductor muscles.

The majority of Pelecypods have two adductor muscles, and are distinguished
accordingly as Dimyarian, or Homomyarian ; in some the anterior muscle is
absent or degenerate (Monomyaria) ; and in others an intermediate condition
obtains (Heteromyaria or Anisomyaria). The number and position of the
adductors was f ormerly accepted as a fundamental feature in Classification,
although many difficulties were presented by exceptional cases. Eecent
researches have shown that an absolute foundation for Classification cannot
be afForded by the number of adductors ; but still, if allowance be made for
degeneration caused by inequilaterality, torsion and other causes, the general
myarian types harmonise fairly well with the larger divisions based on the
totality of characters.

The visceral mass, as a rule, occupies the Upper portion of the shell,
and contains the heart, intestinal canal, generative organs, renal and other
glands. The rectum usually lies above the posterior adductor, and dis-
charges into the anal siphon, when present. The mouth is placed at the
forward end of the visceral mass below the anterior adductor, and is commonly
furnished on each side with a pair of leaf-like expansions of the integument
called ]i)<^lph which are ciliate internally, and serve to conduct alimentary
matter from the gills to the mouth. Palpi are seldom wanting, and their
form and character remains fairly constant throughout a number of groups.
The mouth itself is unarmed, and the alimentary canal is more or less bent,
usually exhibiting a dilation which is regarded as the stomach.

428 MOLLUSCA phylum vi

The Foot. — From the ventral surface of the visceral mass projects an
extensile muscular organ, known as the foot, which is capable of being pro-
truded beyond the margins of the valves, or entirely retracted within the
mantle lobes. The muscles serving to move this organ are inserted upon the
Shell near the adductor scars, leaving small accessory impressions. In a
large majority of bivalves, the foot has the familiär hatchet-shape from which
the class name is derived, but as an organ of locomotion, tactile use, and
possibly prehension, it is modified for special uses in many forms. A few
Pelecypods, such as Osfrea, have the foot altogether aborted, though remnants of
its retractor muscles exist and are attached to the valves ; and in some cases
{Pholadomya, Halicardia) an accessory foot-like organ, or " opisthopodium,"
is developed at the posterior end of the visceral mass.

In many Pelecypods the foot is provided with a gland secreting horny
matter which solidifies in threads after extrusion, forming a fixative tuft or
cable called the byssus, by which the animal adheres to extraneous objects.
Some sessile genera have the byssus more or less calcified, when it forms a
shelly plug closing a sinus or foramen in one of the valves through which it
passes. Many of the Pectinidae have a comb-like series of denticles (denolium)
on the edge of the byssal sinus, in which the byssal threads rest. In perma-
nently sessile forms, the byssus is usually absent.

Gills. — On either side of the visceral mass above the foot and usually
extending from the palpi to the posterior adductors are the gills or denidia.
In a general way the ctenidium is composed of a stem carrying a nerve and
blood-vessel, from which on each side leaflets or slender filaments are given
out laterally. In the more archaic types (Nucula, Yoldia, Solemya) these gills
are plate-like, not organically united except by the stem, though in some
cases attaining a solidarity as a mass, by the interlocking of very large cilia,
distributed in bands or patches on the opposed surfaces of individual plates.

These plate-like gills are termed foliobranchiate or protobranchiate.
According to their structure, other types of gills are intermediate between
these and the so-called " filibranchiate," in which the plates are elongated and
strap-like, and the " reticulate," in which the filaments are united by cross
conduits in a net-like manner. Attempts have been made to employ the
various types of gills as fundamental characters in Classification, but experience
has shown that they cannot be depended upon as the exclusive basis of any
systematic arrangement.

Siphons. — When the mantle lobes are united, two posterior openings, more

or less tubulär, are always present
(Fig. 640). The dorsal tube, called
the dorsal or anal siphon, serves for
the discharge of water which has
j, been inhaled through the ventral
Fifi. 640. or branchial siphon, carried to the

Saxicava arctim Lam. Animal with closed mantle gÜls, dcprivcd of itS OXygeU and

ges, showing foot (p), protruding from the pedal open- j-i,i j.- ^ j j.i, n j

mg, and anal (s) and branchial (s') sTphons. Natural siL edlble particles, and then expelled.

The anal siphon also carries efFete
matters from the rectum, and sometimes ova are discharged in the same
way. The tubes are sometimes adherent or enclosed in the same envelope,
and sometimes separate to their base ; in general, however, a septum or
partition exists between the two passages, thus avoiding the mixture of the

CLASS I

PELECYPODA

429

two currents. The siphonal septum is frequently carried forward internally,
or supplemented by a junction of the gills in such manner as to form a
practically continuous partition between the anal and branchial regions
within the mantle. The siphons are always contractile, and, except in
sedentary burrowers, usually retractile within the shell.

The siphons, being a local modification of the mantle margin, receive their
musculation from the same source. In general, the muscles have spread
inward, pari passu with the increase in length of the organ to be retracted,
and their Insertion on the valve leaves an angular scar called the pallial sinus,
which is an important aid in Classification of the minor groups. It has some-
times been assumed that the absence of this sinus was evidence of the
asiphonate character of the species, but the example of Lucina, Cuspidaria,
and several other siphonate forms which have no pallial sinus show that this
is not necessarily true. Formerly, when the character of the pallial line was

Lutraria elUptica Roissy. Interior of left valve show-
ing i>allial line (p) ; pallial sinus (s) ; anterior (a) and pos-
terior (o/) adductor scars ; and resiliifer (l). hv, Length ;
ui, Heiglit of the shell. '■^/^ natural size.

Fio. 642.

Crassatell ites plumbeus (Chem.). Interior of left
valve showing entire pallial line (m) ; anterior (a)
and posterior («') adductor scars ; and resiliifer
(0. 2/g natural size.

regarded as of prime importance, the Pelecypods with a sinus were called
Sinupalliata (Fig. 641), and those without, Integripalliata (Fig. 642).

The Hinge. — The origin both of the hinge structure and the ornamentation
of the shell can be perhaps best understood by a consideration of what is
known regarding the archetype of the class, and by noticing the changes that
have since been introduced. The original protopelecypod was small, thin,
symmetrical, sub-circular or oval, with a short external ligament equally dis-
posed on each side of the beak along the hinge line. The mantle was not
uniformly attached to the shell along a pallial line, as in modern Pelecypods,
but adhered more or less irregularly and was not provided with extrusile
siphonal tubes. The adductor muscles were sub-equal, symmetrical, and
situated high up in the valves. The surface of the valves was smooth, or
(probably in connection with the development of tactile papillae on the mantle
edge) radiately ribbed. These conclusions are justified not only by inference
and by recent investigations on the morphology of the prodissoconch, but by
the characters of the most archaic Pelecypods, summarised by Neumayr under
the name of Palaeoconcha.

Since the general form of the Pelecypod depends upon its principal
anatomical characters (the size, number and position of the muscles, the
presence, size and character of siphons, byssus, etc.), then, to a certain
limited extent, especially in the modification of the primitive simple Palaeo-

430 MOLLUSCA phylum vi

conchs, it is piain that the differences of form would tnarch with the respective
anatomical differences. For example, those forms which retained the simple
open mantle and sub-equal adductors would continue to be of a rounded and
symmetrical shape ; while those which tended to produce elongate siphons, or
in which marked inequality of the adductors was developed, would probably
present more elongate or triangulär outlines. The differences of form would
necessarily react upon the developing hinge, from the inevitable Operation of
physical laws, and thus tend to produce in connection with particular lines of
evolution of form, particular types of hinge.

The recent researches of Bernard and Simroth have developed the fact
that in some Pelecypoda the ctenidium originates as a lateral plate, which
becomes transversely folded, and in which the reticulate form results from
subsequent perforations between the folds, and not from the concrescence of
originally separate filaments, as has been hitherto supposed to be the invari-
able mode.

Neumayr has shown that, among the Palaeoconcha, ribbing existed in
various species along the dorsal as well as the other margin, and that it pro-
duced denticulations there ; and that when these denticulations had become
a fixed specific character, the ribbing disappeared from the area above the
hinge margin.

In this way (as analogically in the Recent Crenella, etc.) the Initiation of
the processes called hinge teeth began. Such projections, interlocking at a
time when the serrations of the other margin of the open valves could be of
little assistance in securing rigidity, offered a means of defence of the greatest
importance when fully developed by natural selection, one which would be
useful at every stage of development, but would increase in usefulness with
increase in size. In fact, this was just such a feature as would lend itself to
the füllest Operation of natural selection. Once well initiated, its progress
was inevitable, and its variety and complexity only a question of time.

From recent studies by Bernard of the development of hinge teeth in
nepionic Pelecypods of many groups, it appears that in most if not all Priono-
desmacea and some Teleodesmacea there is first developed on each side of the
ligament (or behind it in Ostrea) a series of transverse denticulations or
minute taxodont teeth, f orming what has been called a provinculum or primi-
tive hinge, independent (so far as yet observed) of the permanent dentition.
The latter begins subsequently by the development of distinct laminae on
the hinge plate. In the Teleodesmacea, toward the ends of the hinge plate
the primitive lamellae originate below the provinculum or in its absence, and
grow proximally. The inner ends of the anterior lamellae become hooked,
and these hooks separate from the distal portions which remain to form the
anterior laterals, while the hooks develop into the cardinals, and the posterior
lamellae into the posterior lateral teeth. The facts point, of course, to the
provinculum as representative of the primitive hinge as observed in many
Palaeoconchs ; but the gap between the provinculum and the beginnings of
the permanent dentition, indicates a suppression of certain developmental
stages which only further researches can supply.

The dynamical origin of the shelly processes of the hinge, which we call
teeth, has only recently attracted attention. In this work Neumayr led the
way, and his contributions have been most valuable ; yet, as often happens
with pioneer work, he failed to grasp fully all the details of the subject, and

CLASS I

PELECYPODA

431

the nomenclature he proposed has required revision. Several groups or
kinds of teeth can easily be distinguished. These are not iiecessaiily funda-
mental, since the teeth, being largely moulded by the dynamics of their
Situation, change with the influences to which their form is due, and in course
of time may become obsolete froin disuse (Anodon), or modified so as to
simulate the teeth of groups with widely different pedigree (Nucula, Mutela,
Plicattda, Trigonia). In general, however, at any given time, the types of
teeth are good evidence of the relationship of forms to which they are
common, especially if the development from the younger stages of the species
under comparison proceeds along similar lines.

The modifications of the hinge now generally recognised are as follows : —

In the Taxodonta the hinge is composed of alternating teeth and sockets,

mostly similar, and frequently forming a long series, as in Area (Fig. 643, A)

Taxodont liinges.

Fio. G43.
A, Area, with external ligament.
with internal resilium.

B, Leda,

Fio. C44.

Schizodont hinge.
Trigonia pectinata
Lam. Recent ; Aus-
tralia.

or Leda (Fig. 643, B). The Schizodonta have heavy, amorphous, variable
teeth, often obscurely divided into sub-umbonal (pseudocardinal) and lateral
(posterior) elements, as in Trigonia (Fig. 644), Unio (Fig. 645), and Schizodus.

In the Isodonta the original taxodont
provinculum is often replaced in the adult
by a hinge structure derived from tM^o
ridges (the "auricular crura") originally
diverging below the beaks. This becomes,
in the most specialised forms, an elaborate
interlocking arrangement of two concentric ^\
pairs of teeth and sockets, which cannot
be separated without fracture, as in Spon-
dylus (Fig. 718). In less specialised forms,

such as Peden, the provinculum becomes schizodont hinge of Unio stachei Neumayr,
, , , , ,, ^ 1 „j.* ii„ J^ ahowing pseudocardinal and lateral teeth.

obsolete, and the crura only partially de- pnocene ; siavonia.
velop.

The Di/sodonta of Neumayr was originally a heterogeneous group, and the
term is now restricted to that division having a feeble hinge structure, whose
origin is more or less palpably derived from external sculpture impinging
upon the hinge line, as in MijoconcJia (Fig. 646), Pachymytiliis (Fig. 647), and
Crenella.

The preceding groups, together with the edentulous Solemyacea, constitute
the Order Prionodesmacea, which is knit together by Community of descent
still traceable in their anatomy.

Fio. 645.

432

MOLLUSCA

PHYLÜM VI

Fig. 646.

Dysodont hinge of
Myoeoncha striatula
Goldf. LowerOolite;
Bayeux, Calvados.

Vi-

d'Orb.

France.

The Fantodonta are a small group of Paleozoic forms whose dentition
partakes of the syiithetic character of the more archaic forms, wliile fore-

shadowing the f uture teleo-
dont types. In this group
the laterals may exceed a
pair in a single group, which
is never the case in the
modern types. Orthodontiscus
and AUodesma are examples.
The Diogenodonta are the
modern and perfected forms
in which there are difFeren-
tiated lateral and true car-
dinal teeth upon a hinge
plate, the former never ex-
ceeding two, nor the latter
three in any one group.
Ästarte (Fig. 754), Crassatel-

Dy,odont hinge ot'pachymytilus petasus UteS (Fig. 642) and CorUcula
Coral Rag; Ooulange-sur-Yonne, (^jg, 761) are examples.

The Cydodonta exhibit
extreme torsion in their dentition, which cijrves out from under the beaks
and is not set upon a flat hinge plate. Isocardia (Fig. 806), Tridacna and
Cardium (Fig. 801) are examples.

In the Teleodonta are found the most highly perfected types of hinge.
The characters of the less specialised forms hardly difFer from those of the
Diogenodonta, but they are placed here on account of their obvious affinities
as shown by other characters. The most specialised forms add to the ordinary
Cardinal series of the Teleodesmacea (10101 ) either a roughened area, as in
Venus; a series of extra cardinals, as in Tivela; or accessory lamellae, as in
Madra, making the hinge more complicated or efficient. Cytherea (Fig. 809),
Mactra (Fig. 824), Venus mercenaria and Tivela are examples.

Several of these forms were included by Neumayr in a group called Des-
modonta, which he founded on such types as Madra under a misapprehension
as to the character of the hinge ; almost all of the others were included in
his Heterodonta, which, construed strictly, would take in all dentiferous
Pelecypods, since the alternation forming its essential character is inseparable
from the possession of functional teeth.

The Asthenodonta comprise borers and burrowers in which the teeth have
become obsolete from disuse. Corhula (Fig. 828), Mya (Fig. 827) and Fholas
(Fig. 833) are illustrative types. In the last-named a remarkable develop-
ment of the sub-umbonal attachment of the mantle has produced a myophore
which is sometimes wrongly interpreted as a tooth. The exceptional develop-
ment of this f eature is explained by the dynamics of Pholad existence.

The above groups form the orderTeleodesmacea, and dentally are intimately
related. Recent studies by Bernard ^ as to the genesis of individual teeth

^ Bernard, F., Sur le developpement et la morpliologie de la coquille chez les lamellibranclies.
Bull. Soc. Geol. France [3], 1895-97, vols. xxiii., xxiv. — Vest, W. von, Über die Bildung und
Entwicklung des Bivalvenschlosses. Verh. Siebenb. Vereins Naturw., 1895-96, vol. xlviii. —
Dali, W. II., On the hinge of the Pelecypods and its development. Amer. Journ. Sei,, 1889 [3], vol.
xxxviii. — Reis, 0., Das Ligament der Bivalven. Jahresh. Ver, Vaterl. Naturk. Württ., 1902, vol. Iviii.

CLASs I PELECYPODA 433

among mcmbers of this order show great uniformity in the early stages.
But inasmuch as these observations are dependent upoii the mode of growth
in highly specialised Pelecypods, in which the development of teeth is largely
secondary, care must be taken not to confound these processes with those by
which hinge teeth were originally initiated in edentulous Protopelecypods.

Finally, in the Anomalodesmacea we have a tribe of burrowers which have
preserved to the present day some of the features which characterised the
edentulous Protopelecypods of ancient geological time. The small teeth of
the neaily edentulous hinge may sometimes be associated with the submersion
of the resilium and the development of a chondrophore, but in other cases
they may be the remnants of hinge teeth acquired in the ordinary way early
in the geological history of the group.

Dental Formulae. — For the purpose of recording compactly the number
and character of the teeth in adult Pelecypods, a formula has been suggested
by Steinmann, which, somewhat amplified, is as follows : —

Let L represent the left and E the right valve, and the teeth be repre-
sented by units ; the sockets into which teeth of the opposite valve fit by
zeros ; the resilium or chondrophore by C ; the laterals by 1 ; the clasping
laminae which receive the laterals by m, if single ; if double, by m2. Where
two taxodont rows meet on one hinge margin and are not separated by a
resilium, as in Glycimeris, let their junction be marked by a period. Obsolete
or feeble teeth may be represented by the italicised symbol for normal teeth.
For amorphous, interlocking masses, which cannot be classified as teeth, and
are of varied origin, the symbol x is adopted. The enumeration begins at the
posterior end, and the right-hand end of the formula is always anterior.

Thus, types of teleodont dentition may be represented as follows : —

Astarte horealis, ^ ■, ,^,^^r- ; Crassatellites antillarum, ^ . ^,7^ : Fenus mercenaria,
Rxioioi ^^^ ^^^^ ^^^^ ^ represents the rough area below the ligament).

In investigating the genesis of the individual hinge teeth in various
genera of the Teleodesmacea, Munier-Chalmas and Bernard have adopted the
following formula, which expresses at once the origin and position on the
hinge of the several teeth. In the majority of cases the teeth appear to be
derived from two primitive pairs of lamellae in each valve, one pair anterior
and one posterior. Each adult tooth is designated by an Arabic numeral
corresponding to the primitive lamella from which it is derived, with a for
the anterior and b for the posterior tooth when a single primitive lamella
gives rise to two teeth. The laterals are counted from below upward in
Koman numerals, the odd numbers belonging in every case to the right, and
the even numbers to the left valve. If it is necessary to name a socket it
receives the designation of the tooth which occupies it, supplemented by an
accent ('). A and P stand for anterior and posterior, L for lateral, and CA
for Cardinal teeth. Finally, if a tooth disappears, its place is indicated by
a zero with an index showing which particular tooth it was. The numeration
of the cardinals always begins with the right median cardinal tooth. Thus,
CAl = median cardinal of the right valve, CA2b = left median cardinal derived
from the posterior part of primitive lamella number two; LA I = ventral
anterior lateral, LP III --= dorsal posterior lateral, etc.

Ligament. — The ligament which unites the two valves, as stated above, is
primitively continuous with them as the uncalcified part of the primitive
VOL. I 2 F

434 MOLLUSCA phylum vi

pellicle secreted by the original shell gland ; it is therefore neither external
nor internal. With its subsequent differentiation, and the thickening of the
valves by calcification deposited about it, it occupies a depression in the
Cardinal margin which Bernard has regarded as internal. In a sense it is
internal, but its position at this stage is not significant, and there is no
fundamental difference between the cases. The differentiation in function
and structure which we find in the adnlt between the ligament, properly
so-called, and the " internal ligament " or resilium, is a later development.

The ligament may be regarded as a fundamental character of Pelecypods,
and is universally present, though in some cases as a mere degraded rudiment
(Pholadacea) ; it may be separated from the valves and functionless {Chlamydo-
concha), or present only in the young stages and lost through specialisation
due to the sessile habit (Rudistids).

As the most important factor in the mechanism of the valves, the liga-
ment has undoubtedly developed with the evolution of the class, and its
chief modifications date from the earliest period in the life-history of the
group. The function of the original ligament was that of an external link
between the valves having the essential nature of a C-spring. That is, the
insertion of the ligament edges on the cardinal margins, or, at a later period,
on thickened ridges or nymphae by which these margins are reinforced to bear
strains, resulted in the following conditions : — The valves being held together
and, in closing, approximated by the contraction of the adductor muscles, the
preservation of their precise apposition, marginally, is due to a rotary motion,
exerted along the axis of the ligament, which pulls the attached edges of the
ligament nearer to each other and exerts a strain on its cylindrical exterior.
This Operation, with a thin ligament, involves a tensile strain on the whole
cylinder; with a thick ligament the external layers are strained and the
internal layers compressed, so that to the tensile elasticity of the external
layers is added the compressional elasticity of the internal portion. The
result of the differing strains to which the several layers of the ligament are
subjected brings about a diiference of structure, and, whenever the ligament
becomes deep-seated, there is a tendency for the respective parts to separate
along the line where the two sets of strains approximate. We then have two
elastic bodies, operating reciprocally in opposite directions, the outer or liga-
ment proper tending to pull the valves open to a certain distance correspond-
ing to its ränge of tensional elasticity ; and the other or resilium (for which
the objectionable terms " cartilage " and " internal ligament " have been used)
tending to push them open to an extent corresponding to its ränge of expansion.

The ligament proper is of a more or less corneous nature, tough and semi-
translucent beneath its external surface. When dry it has a vitreous fracture,
and often shows hardly any fibrous texture.

The resilium is distinctly lamellar or composed of horny fibres, which are
apt to give a pearly sheen to its broken surface. There is often a more or
less extensive intermixture of lime in its substance, which may be diffused, or
may be especially concentrated along the median plane. As may be seen by
examining the unbroken resilium (as in Madra), this organ in such cases has
something of an hour-glass shape ; the ends which fit into the " cartilage pits "
or resiliifers being more expanded than the centre between them. The deposit
of lime in the form of an accessory shelly piece, usually termed the ossiculum
or lithodesmaj serves for the reinforcement of the resilium.

CLASs I PELECYPODA 435

For the type of ligament which extends on both sides of the beaks,
Neumayr adopts the designation amphidetic ; and for the more perfected type
which has been withdrawn wholly behind the beaks, he employs the term
opisthodetic (Fig. 648). Glycimeris offers a conspicuous type of the amphidetic
ligament ; Teilina and Venus ex-
emplify the opisthodetic arrange-
ment. In many bivalves a
lozenge-shaped cardinal area ex-
tends amphidetically between the
beaks, while the ligament is wholly
posterior, being visible as an
oblique triangulär space, with its
apex at the umbonal point and
its base at the hinge line, as in
Pteria. Nearly every stage in
the recession of the ligament can

, , 1 <• ^1 . 1 i Homomya calciformis Ag. Lower Oolite ; near Bayeux.

be ODServed, irom truly central tO WltU well-preserved extemal, opisthodetic Ugament. 2/3.

posterior, in Lima and its allies.

The most perfected type of ligament is that which may be compared to a
cylinder split on one side, and attached by the severed edges, one edge to
each valve. This type is known as parivincular (Tellina, Cardium) ; its long
axis corresponds with the axis of motion or vertical plane between the valves,
and in position it is usually opisthodetic. Another form is like a more or
less flattened cord extending from one umbo to the other {SpondyluSj Liina),
with its long axis transverse to the plane of the valve margins and the axis
of motion. This is called alivincular ; it may be central or posterior to the
beaks, but, unless very short, is usually associated with an amphidetic area.
Lastly, a third form must be noted which consists of a reduplication of the
alivincular type at intervals upon the area (Perna, Area, Fossula), either
amphidetically or upon the posterior limb of the cardinal margin. This is
designated as multivincular, and is developed out of the alivincular type.

In some forms with a rigid hinge and internal resilium, the ligament may
degenerate into its archaic epidermic character, as in some species of Spondylus.
It is impossible to draw a sharp line between these and similar forms in which
the ligament is not quite reduced to the State of epidermis, as in some species
of Ostrea. The cardinal area above referred to is in part the morphological
equivalent of the lunule of teleodont Pelecypods. In general, when the
ligament has become opisthodetic, the remnant of the area in front of the
beaks forms the lunule and may be called prosodetic. The amphidetic area
is an archaic feature which has been lost by the more specialised types of
modern bivalves, and its gradual disappearance may be traced in various
Prionodont genera.

The Separation of the ligament and resilium has been described as due to
mechanical causes. In those cases where the resilium becomes submerged
between the valves, the area of attachment of its ends in thin-shelled forms is
more or less thickened and assumes a spoon-like form projecting from the
hinge-plate, termed the chondrophore or resiliifer ; this is often reinforced by a
special prop or buttress called the clavicle. It has been suggested by Neumayr
that part of the armature of the hinge, in the shape of teeth, is due to deposits
made parallel to or induced by the presence of the chondrophore and resilium.

436 MOLLUSCA phylum vi

There is some reason to think that the presence of the resilium in Pecten
and Spondylus may be connected with those changes of the auricular crura
which lead to the assumption of dental functions by the latter. But it is well
known that submergence of the resilium occurs independently in many unre-
lated groups of bivalves ; and it is probable most of them were previously
dentiferous and still retain their teeth, although more or less modified or
displaced, while the edentulous gen era seldom show any teeth which appear
to owe their existence solely to the presence of a chondrophore. The nearest
approach to a hinge composed of dental laminae of such an origin is found in
Placuna, Placenta and Placunanomia, together with the Spondylidae already
mentioned.

Classification. — The class Pelecypoda, which comprises about 5000 recent
and twice as many fossil species, appears to be divisible into three ordinal
groups : Prionodesmacea, Anomalodesmacea and Teleodesmacea ; of which the
third represents the most perfected and developed (though not always the
most specialised) modern type of bivalve. There seems little reason to doubt
that all these Orders are descended frora a Prionodesmatic radical or prototype,
and that for various reasons the first and second retain more evident traces of
this origin than the third.

For convenience of comparison, the characteristics of these Orders will be
stated here.

Prionodesmacea. — Pelecypods having the lobes of the mantle generally separated, or,
when caught together, with imperfectly developed siphons ; the soft parts in general
diversely specialised for particular environments ; the shell strueture nacreous and prismatic,
rarely porcellanous ; the dorsal area amphidetic or obscure, rarely divided into lunule and
escutcheon, and when so divided, having an amphidetic liganient ; ligament variable, rarely
opisthodetic ; nepionic stage usually Avith a taxodont provinculum ; permanent armature of
the hinge characterised by a repetition of similar teeth upon the hinge line, or by amorphous
schizodont dentition ; habits active, sessile or nestling, not burrowing ; monoecious or
dioecious.

This group, originating with the earliest forms, has retained many archaic
features through immense periods of geological time, although occasionally developing
remarkable and persistent specialisations. Notwithstanding most of its subdivisions
have arrived at a notable degree of distinctiveness, intermediate forms of ancient date
connect them all, more or less effectively, with the parent stem.

Anomalodesmacea. — Pelecypods having the mantle lobes more or less completely united,
leaving two siphonal, a pedal, and sometimes a fourth opening between them ; siphons well
developed, always at the posterior end of the body ; two subequal adductor muscles ; the
shell strueture nacreous and cellulo - crystalline, rarely with a prismatic layer ; the area
amphidetic or obscure, rarely distinctly divided ; the ligament usually opisthodetic, generally
associated with a separate resilium, chondrophores and lithodesma ; valves generally un-
equal, the dorsal margin without a distinct hinge plate, armature of the hinge feeble, often
obsolete or absent ; rarely with lateral laminae "orwell-developed dental processes ; usually
burrowing, hermaphrodite, and marine.

This group is intimately related to many of the Palaeoconcha, except as regards
the presence of a pallial sinus. It retains many archaic features, and includes several
of the most specialised modern forms. Through the Anatinacea it approximates the
Myacean Teleodesmacea. It is peculiar in the possession of a lithodesma, and in the
strueture of its gills and hinge. The forms with a reticulate gill have it of a different
type from the reticulate gills of the other Orders ; those which retain a modified
foliobranch gill have it different from the foliobranch gill of Prion odesmacean groups.
There are no forms with a filibranchiate gill, or with a typically fully developed
reticulate gill.

CLASs I PELECYPODA 437

Teleodesmacea. — Pelecypods witlj reticulate gills, the vontricle of the heart embracing
tlic rectum ; having the maiitle lobes more or less connected and u.sually possessing dcveloped
siplions ; the adductors practicaily e(|ual ; the shell structure cellulo-crystalline (porcellanous)
or obscurely prismatic, never nacreous ; the dorsal area, when present, always prosodetic or
divided into lunule and escutcheon ; ligament opisthodetic, with or without separate
resilium ; without' a lithodesraa, rarely with externa! accessory shelly pieces ; nepionic stage
usually without a taxodont provinculum ; permanent armature of the hinge characterised by
tlie Separation of the hinge teeth into distinct cardinals and laterals ; the posterior laterals,
when present, placed behind the ligament ; the animals active or nestling, sometimes sessile,
but rarely sedentary burrowers, rarely inequivalve, usually possessing a hinge plate and a
pallial sinus ; sexes usually separate.

It is doubtfiü if this groiip is represented in tlie Paleozoic rocks, especially below
the Carboniferous, thoiigli genera beloiiging to it are foresliadowed by some of the
Palaeoconclis. Altbough most of the Teleodonts live embedded in the surface of the
sea-bottom, they retain their ability to migrate, and only a few extremely specialised
forms inhabit permanent burrows of their own constriiction. They are sometimes
commensal in the burrows of other animals. Similarly, few of them fix themselves
permanently by a byssus, although often byssiferous, especially when young. With
the exception of a few specialised forms they possess a pair of direct and reflected
branchial laminae on each side of the body, frequently united behind the foot, forming
an anal Chamber ; the two sets on one side usually of unequal size, and of the reticulate
type. None are known with typically foliobranch or filibranch gills, although some
abyssal forms have archaic sub-foliobranchiate etenidia.

There remains a small group of fossils, difficult to refer to a place in the System,
yet characterised by several features in common ; these have been named by Neumayr
Palaeoconcha, and are defined by him as follows : —

Palaeoconcha.— Prototypic Pelecypods, with thin shells, a simple or obscure pallial line,
sub-equal adductor scars placed high in the valves ; dorsal area absent or amphidetie ; liga-
ment external, variable; hinge margin edentulous or with polymorphous teeth form«d by
modifications of the margin and not set upon a hinge plate.

While the forms included here are not always actually the most ancient, yet in
their modifications they indicate clearly the origin of many subsequently developed
structures found in Pelecypods of a more modern type ; and owing to their undifferen-
tiated polymorphic character are difiicult to assign a place in any Classification based
on more highly developed forms. There is little doubt that some of these show taxo-
dont affinities, and others recall PJioladomya ; but the final discussion of these puzzling
forms awaits greater knowledge of them and other early bivalves. It is to be under-
stood that the places assigned them in the present systematic arrangement must be
more or less provisional. Neumayr included in this group the following families : —

Vlastidae. Praecardiidae. Solenopsidae.

CardioUdae. Silurinidae. Grammysiidae.

Antipleuridae. Protomyidae (including possibly Posidonomyidae.

Lunulicardndae. the Recent Solemya). Daonellidae.

The pelagic Planktomya henseni, recently described by Simroth, presents many of
the characteristics of the Palaeoconchs. The posterior cardinal margin is denticulate,
the ligament internal, and the gills are represented by a single lateral plate parallel
with the longer axis of the shell on each side ; a type elsewhere only known in con-
nection with the younger stages of Scioheretia.

438 MOLLUSCA phylüm vi

Order 1. PRIONODBSMACEA DalL

Section A. Palaeoconcha p.p. Neumayr.i
Family 1. Solemyacidae.

Shell soleniform, equivalve, low-heaJced, edentulous, gaping, with the anterior end
longer and the epidermis conspicuous, exceeding the valves ; area obscure or none ; Ligament
amphidetic, parivincular, usually internal posteriorly ; mantle lohes united ventrally,
attached in front to the periostracum and valves hy a hroad surface, leaving no distinct
pallial line ; a single posterior siphonal and anterior pedal foramen in the mantle ;
adductors sub-equal, with a thickened ray in front of the posterior scar ; animal dioecious,
marine, hurrowing. Devonian to Recent.

Solemya Lam. Carboniferoiis to Recent, rare in all horizoiis. Janeia King,
shorter and less inequivalve, may include most of the Paleozoic species hitherto
referred to Solemya. Glinopistha Meek and Worthen, from the Carboniferous, is also
allied, and Dystactella Hall, is nnited with it by Zittel. Phthonia Hall, from the
Devonian, is placed here by Ulrich. Ächarax Dali, Mesozoic to Recent, has a purely
external ligament and no clavicle.

Family 2. Solenopsidae Neumayr.

Shell thin, elongate, equivalve, with very anterior heaks ; the hinge edentulous, ligament
parivincular, external ; pallial line not sinuated ; a ridge or groove radiating from the
beak to the lower posterior angle of the valves. Marine. Devonian to Trias.

Sanguinolites M'Coy. Elongate, obliquely truncate behind ; beaks low, sculp-

ture of concentric or broken lines, an-
terior adductor scar buttressed by a
ridge. Carboniferous.

Promacrus and Prothyris Meek.
Pj,. 649 Carboniferous,

Solenopsis pelagica Goldf. Devonian ; Bifel District. Ärcomyopsis Sandb. Somewhat

curved, with prominent beaks ; obliquely
truncate behind; posterior area radially, the rest of the surface concentrically
sculptured. Devonian.

Solenopsis M'Coy (Fig. 649). Very long, scabbard-shaped, smooth ; anteriorly
Short and rounded, gaping behind. Devonian to Trias.

Family 3. Vlastidae Neumayr.

Shell thin, very inequivalve, beaks elevated, hinge line edentulous, arehed, meeting at an
obtuse angle beneath the beaks, leaving a dorsal opening ; surface smooth or concentrically
striate.

The two genera Vlasta and Dux (Vevoda) Barrande, from the Silurian of Bohemia
(Etage E 2), constitute this family.

Family 4. Grammysiidae Fischer.

Shell thin, equivalve, oval or elongate, with the beaks sub-central to anterior ; hinge
edentulous, sometimes thickened. Ligament parivincular, external; imllial line not
sinuate ; surface smooth or concentrically sculptured. Silurian to Carboniferous.

^ [The terms Palaeoconcha, Taxodonta, Schizodonta, etc., preceded by Roman numei-als, are
retained here merely as convenient descriptive ai)pellations, and are in nowise to be regarded as
possessing systematic values.j

CLASS I

PELECYPODA

439

Grammysia Vern. (Sphenoynya Hall) (Fig. 650). Shell elongate-ovate, concen-
trically sculptured, witli a deej) luniüe ; cardinal niargin thickened, edentulous ;
siirface with several radial
grooves. Silurian and De-
voiiian. Protomya Hall ih!
similar l)ut without the
grooves.

Leptodomus M'Coy, Sil-
urian ; Elymella, Glossites^
Euthydesma, Paleanatina

and (?) Tellinopsis Hall ;
Devonian.

Gardiomorpha Koninck. " ^'■" '''''^"

C^^Tn^ iiiflaforl hoaVc olrv^r^cf Grmnmysia hamükmeni<is Vem. Spirifer Sandstone (Lower Devonian) ;
UVai,^ mnatea, OeaKS almost Lahnstein, Nassau (after Sandberger).

anterior, cons2:)icuous, ad-

jacent, prosogyrous ; hinge line thin, arched. Silurian and Carboniferous.

Isoculia M'Coy. Like the preceding, but with coarse concentric sculpture,
Carboniferous.

Other Carboniferous genera are Broeckia Koninck ; Ghaenomya Meek ; Sedgwickia
M'Coy ; and Edmondia Koninck. The last is like Gardiomorpha but gapes in front,
with a narrow ridge below the beaks.

The Cambrian FordiUa Barrande, earliest of bivalves if a Mollusc, very likely belongs
to the bivalved Crustaceans near Estheria. It is minute, oval, somewhat arcuate, and eon-
centrically striated. Lower Cambrian ; New York and Massachusetts.

Another bivalved shell, regarded by some authors as a Pelecypod, Modioloides priscus
Walcott, from the Lower Cambrian of eastern New York, is probably also of Crustacean
affinities. Pizzaroa, Tunaria and Bistramia Hoek, from' the Silurian of Bolivia, are probably
byssal bivalves.

Family 5. Cardiolidae Neumayr.

Shell equivalve, inflated, ohliquely ovate, with prominent heaks, and edentulous hinge ;
sculpture offen radial, or sometiraes of concentric ridges lohich may he confined to the
beaks. Silurian and Devonian.

Gardiola Brod. (Fig. 651); Gloria Barrande; Eopteria
(? Euchasma) Billings ; from the Ordovician, may also belong here.

Family 6, Antipleuridae Neumayr.

Shell very inequivalve without gape below the beaks ; hinge
obscurely taxodont, with an amphidetic area and predominantly
radial sculpture. Silurian.

Äntipleura, Dualina and Dalila of Barrande.

Fig. 651.

Cardiola cornucopiae
Goldf. Devonian ; Ebers-
reuth, Fichtelgebirge, i/^.

Family 7. Praecardiidae Neumayr.

Shell equivalve with taxodont dentition and usually strong
radial sculpture. Silurian and Devonian.

This family contains the following genera of Barrande from the Silurian of
Bohemia : Praecardium, Paracardium, Puella, Pentata, Buchiola {Glyptocardia Hall),
Praelucina, Regina, Praelima ; to which Neumayr adds Pleurodonta Conrath, and
Pararca Hall. It is possible that Silurina Barrande, regarded by Neumayr as the
type of a distinct family, may also be included. It is distinguished by its feebler
structure and a dorsal radial groove near the cardinal border.

440

MOLLUSCA

PHYLUM VI

Section B. Taxodonta Neiimayr (emeiid.).
Superfamily 1. NUCULACEA.

Shell of variable form, closed ventrally, equivalve, with a smooth epidermis ; nacreous
or porcellanous with tuhuliferous external prismatic layer ; area ohscure, or none, when
present divided into lunule and escutcheon ; ligament variable, amphidetic ; gills folio-
branchiate; both adductors present and sub-equal ; foot grooved and reptary, not

erous ; marine.

Family 8. Otenodontidae Dali.

Shell nuculiform, with the teeth in a continuous arched series ; no area ; ligament
external, alivincular, without an external resilium ; pallial line simple. Ordovician
and Siluriaii.

Gtenodonta Salter {Tellinomya Hall p.p.) (Fig. 652). Oval, smooth or con-
centrically striate, in the later horizons sometimes with Leda-like
ornamentation. Ordovician and Siluriaii.

Gucullella (M'Coy) Fischer. Ovate, thin-shelled, with a straighter
hinge line and a radial buttress to the anterior addnctor. Silurian.

p^^^ g^2 Family 9. Nuculidae Adams.i

ctenodontapectun- Shell Compact, closed, with the teeth in two series meetinq below the

culoidesHall. Ordo- , ,77777 ,777

vician ; Cincinnati, umbones, separated by a chondrophore ; area represented by an obscure

^^^^^^ lunule and escutcheon; no ligament, but a wholly internal, amphidetic,

alivincular resilium ; internal layer of shell nacreous ; mantle lobes

free, without siphons ; pallial line simple. Silurian to Recent.

Nucula Lam. {Nuculana Link) (Fig. 653). Oval or triangulär, concentrically or
reticulately sculptured. Silurian to Recent. Re- a

presented by over 200 fossil and half as many Recent
species.

Acila Adams. With divaricate sculpture. Lower
Cretaceous to Recent.

Ohio. 2/j
Hall).

Family 10, Ledidae Adams.i

Shell as in the Nuculidae, but elongated with the
ligament variable, the resilium sometimes external or
absent, the internal shell layer sub-nacreous or por-
cellanous, the ends of the shell partly gaping ; the

mantle lobes more or less united

elongate siphons

to Recent.

Fi(i. 053.
A, Nucula strigilata Goldf. Upper
Trias; St. Cassian, Tyrol. i/i- B, N.
nucleus Linii. Miocene ; Grussbach, near
Vionna. i/j.

ivith complete, sometimes
pallial line usually sinuated. Ordovician

Gleidophorus Hall {Adranaria Mun.-Chalm.) (Fig.
654). Shell rostrate, the anterior side sh orter, with an
internal radial buttress. Ordovician and Devonian.

Gytherodon Hall. Silurian and Devonian. (?) Redonia
Rouault ; Gadomia Tromelin ; Palaeoneilo Hall ; Anuscula
Barr. ; and Myoplusia Neiimayr. Silurian.

Fio. 654.

CkidopTiorus cuUratus Sandb.
Internal monld from Lower Devon-
ian ; Niederlahnstein, Nassau, i/j.

1 Verrül, A. E., and Bush, K. ./., Revision of the genera of Ledidae and Nuculidae.
Joura. Sei. [4], 1897, vol. iii.

Am er.

CLASS I

PELECYPODA

441

Leda Scliuiu. (Figs. 655, 656). Shell rostrate, elongate, often keeled, conceiitri-
cally Stria te ; liiiige as in Nucida ; pallial siiius siiiall. Siluriaii to Receiit.

• Fio. 655.

Leda rostrata
(Lam.). Middle Jura;
Milhaud, Aveyron.

Vi.

Fio. 650.

Leda desJiayesiana Duch.
Oligocene ; Rupelmonde,
Belgium. i/j.

Yoldia arctica Gray.
Pleistocene ; Bohus-
län, Sweden. i/i-

Fig. 658.

NucuUna ovalis
(Wood). Miocene;
Forchtciiau, near
Vienna.

Yoldia Moller (Fig. 657). • Sliell tliin, wide, and niore or less gaping beliind,
hinge as in Nucula. Cretaceous to Recent.

Nuc'idina ^^Ov\). (Fig. 658). Nuculiform, hinge teethfew and discrepant ; with
large lateral tootli and external ligament. Tertiary and Recent.

Malletia Desm. and Tindaria Bell. Yoldiform and nnculiforni respectively, but
without internal chondrophore. Tertiary and Recent.

Superfamily 2. ARCACEA Deshayes.

Shell of varied form, usually with a pilose epidermis, porcellanous, with tiihiiliferous
non-prismatic external layer ; area typically amphidetic, ligament external, ali- or
multivincular ; gills filibranchiate, with the filaments usually reflected ; mantle lohes
free, without siphons, the pallial line simple; foot variable, deeply grooved, hyssogenous ;
marine or fluviatile.

Family 11. Parallelodontidae Dali.

Shell arciform, with the posterior hinge teeth elongated, tending to he parallel to the
hinge margin ; ligament multivincular. Carhoniferous to Recent.

The ancient forms of this group appear to connect
with the Pteriacea through Fterinea, and with Area
through Cucullaea. The Recent forms, which froni
their shell characters have been referred to Maerodon,
are all small and probahly should be referred to the
Arcidae. The relationship of this family to the
Arcidae is very iutimate but not exclusive.

Parallelodon Meek {Maerodon Lycett) (Fig.
659). Shell elongate, snl)-qnadrate, with ani-
phidetic area, and
prominent, rather
anterior beaks.
Anterior teeth
transverse or flex-
uous, posterior long
and parallel to the
hinge line. Devon-
ian to Tertiary ;
maximum in Goal
Measures.

Grammatodon

Parallelodon hirsonensi.i Morris and
Lyc. Great Oolite ; Minchinlianii)ton,
England. Vi-

Fio. 6ö0.
CmnUaea hersilüi d'Orb. Oxford ian
St. Reniy, Ardennes. Vi-

Vieil

442 MOLLUSCA phylüm vi

Meek and Worthen, and Nemodon Conrad, are allied. Garhonarca Meek and Wortlien.
Beaks inflated, curved, angiüar beliind ; hinge margin curved, witli two oblique
teetli. Carboniferous,

Gucullaea Lani. (Fig. 660). Sliell inflated, trapezoidal ; liinge teetli in tlie centre
of tlie hinge short, transverse or oblique, the terminal teeth on each side longer, sub-
parallel to the hinge line ; posterior adductor usually supported by a radial elevated
lamina or buttress. Jura to Recent ; maximum in Mesozoic.

Gucullaria Desh., of the Eocene, and Idonearca Conrad, are closely allied.

Family 12. Oyrtodontidae Ulrich.

Shell equivalve, short, usually heavy, convex and earthy, without persistent epidermis,
area small, ligament parivincular (.?) ; hinge teeth transitional between the Parallelodon
and Dysodont type; adductor scars suh-equal, the posterior larger hut less impressed.
Ordovician and Silurian.

These forms are evidentlj" intermediate in character. They recall Limopsis among later
types, are nearly related to the Parallelodontidae, but have not the multivincular ligament ;
the hinge has Dysodont elements, but the ditference of texture and epiderniis stand in the
way of assimilating them with Mytilacea.

Gyrtodonta Bill. (Gypricardites p.p. Conrad ; Palearca Hall). Shell rounded,
moderately ventricose, with rather tumid, incurved, anterior beaks ; area narrow and
obscure ; cardinal teeth two to four, obliquely curved or horizontal ; lateral teetli near
the posterior eiid of the hinge elongate, strong, curved or oblique ; pallial line simple.
Anterior adductor set on the wall of the valve. Ordovician and Silurian.

Vanuxemia Bill. Beaks more nearly terminal, anterior adductor scar excavated
out of the hinge plate. Ordovician.

Whitella and Tschyrodonta Ulrich ; Matheria Billings. Ordovician and Silurian.

Family 13. Limopsidae Dali.

Shell pectunculoid, equivalve or nearly so; the ligament alivincular, partly
immer sed, its socket approaching a chondrophore ; area small ; foot long, narrow, grooved,
byssiferous ; otherwise as in Ärcidae. Trias to Recent.

These forms precede the typical Area and have a special facies of their own. The two
dental series of the hinge are often discrepant in character or direction, recalling the
Parallelodontidae.

Limopsis Sasso (Fig. 661). Small, rounded or oval, recalling Glycimeris, except
for the alivincular ligament. Trias to Recent.

Trinacria Mayer {Trigonocoelia Nyst). Like Limopsis, but tri-
angulär, with the posterior slope keeled. Eocene. Gnisma Mayer,
from the Eocene, appears to be related.

Family 14. Arcidae Dali.

Shell trapezoidal or rounded, with the posterior side longer; ligament

Fig. 661. usually multivincular ; hinge typically taxodont, with the teeth in two

Limopsis aurita ^'^'^'^^o^i' series, meeting helow the heaks, and approximately vertical to

pL^Sza^^iT^"^' ^^^ inargin of the valve; foot stout, short, deeply grooved. Jura to

Recent.

Most of the Paleozoic ^rca-like forms are probably Parallelodontidae, and the typical
Areas are preceded by Pectunculoid forms. The convergence of the types of Arcacea as \ve
recede in geological time is very marked, and their relations to the Nueulacea are evident in
spite of the later developed ditferences.

CLASS I

PELECYPODA

443

Area Lani. (type A. noae Liiin.). Shell trapezoid, eqiiivalve, with a wide amphi-
detic area, distant conspiciioiis Ijeaks, and radial sciilpture ; a wide l)yssal gape ; a
long, straiglit, transversely dentale hinge line, with niany sniall siniilar teeth.
Tertiary and Recent. Used in the wider sense to include all the groups of Arcidae,
there are some 200 living and 300 to 400 fossil speeies.

Subgenera : Barhatia Gray (Fig. 662) ; Scapharca, Noetia, Anadara (Fig. 663) and
Argina Gray ; Scaphula Benson (fresh-water), etc.

Isoarca Münst. (Fig. 664). Shell smooth, inflated ; beaks füll, incurved ; hinge
line with rather aniorphous dentition. Upper Jura and Lower Cretaceous. •

Fig. 662.

Area (Barhatia) harhata Linn. Miocene ;
Grund, iiear Vienna. i/j.

Fig. 603.

Area {Anadara) diluvii Lam.
Pliocene ; Siena.

Pio. 664.

Area (Isoarca) cordi-
formis Ziet. Upper Jura ;
Nattheim, Würtemberg.

V,.

Glycimeris Da Costa {Pectunculus Lam. ; Axinea Poli) (Fig. 665). Rounded and
almost symmetrical. Basal margin dentate ; area as in Area, but shorter ; ligament

Fig. 665.
Glycimeris dbovatus (Lam.). Oligocene ; Weinheim, near Alzey, Hesse. Vi-

multivincular ; teeth oblique, in an arched series, interrupted during growth by the
subsidence of the areal margin. Cretaceous to Recent ; maximum in Miocene.

Section C. Schizodonta Steinmann (emend.).

Superfamily 3. PTERIACEA Dali.

Shells of varied form, frequently alate, with a nacreous or suh-nacreous inner and
prismatic outer layer ; the epidermis seldom conspieuous ; area amphidetic ; ligament
variable, usually not parivincular ; gills filihranchiate or reticulate, usually reßected ;
mantle lobes free, without siphons ; pallial line simple; the anterior adductor smaller.

444

MOLLUSCA

PHYLUM VI

or frequently obsolete in the adult, thoiujh iiresent in the young ; generally hyssiferous ;
hinge schizodont or edentulous. The young sometimes showing a distinct nepionic stage.
Marine.

Family 15. Pterineidae Dali.

Shell pteriiform, Malaie, dirayarian, the anterior adductor smaller ; inequivalve, very
inequilateral ; dentition ohscure ; ligament amphidetic, external, multivincular (?) ; the
hyssus passing through a notch in the smaller valve. Ordovician to Devonian.

In Pterinea and its allies we have the first indications of divergence of what ultimately
becanie taxodont and schizodont dentition. From this assemblage, as indicated by Jackson,
a large proportion of the Prionodesmacea have diverged in various directions. It is probable
that from tliis source the filibranchiate Taxodonts have sprung, rather than directly from the
foliobranchs.

Rhomhopteria Jackson (Fig. 666). Posterior wiiig separated from tlie body of the

A B

Fio. 666.

Rh(ynibopteria mira
(Barr.). Silurian (E) ;
Prague, Bohemia(after
Jackson).

Fio. 667.

A, Pterinea laevis Goldf. Devonian ; Niederlahnstein, Nassau. Interior of left

valve, Vi- -B, P- Uneata Goldf. Same locality ; external view.

valve by a shallow sinus ; anterior wing short ; teeth obscure, the posterior elongated.
Silurian.

Pterinea Goldf. (Fig. 667). Left valve convex, riglit valve flat ; hinge plate long,
broad, auriculate before and behind ; area amphidetic, grooved ; ligament parivin-
cular (?) ; anterior teeth obscure, transverse ; the posterior elongate, nearly parallel to
the Cardinal margin, depressed behind. Posterior adductor scar large, the anterior
small but strong, inserted below the anterior wing. Ordovician to Carboniferous ;
particularly abundant in the Devonian of Europe and America.

Äctinodesma Sandb. {Glijptodesma, Ectenodesma Hall; Dolichopteron Maurer).
Like Pterinea, but with the wings elongated and pointed. Devonian.

Leptodesma Hall ; Kochia Frech {Onychia Sandb.; Loxopteria Frech). Devonian.

Family 16. Lunulicardiidae Fischer.

Usually equivalve, triangulär shells with terminal healcs, from which a sharp ridge
runs toward the lower margin, hounding a flattened area. Hinge margin straight, long.
Internal characters unknown. Silurian and Devonian.

Lunulicardium Münst. Anterior side with a byssal sinus. Silurian and
Devonian. L. semistriatum Münst.

Patrocardium Fischer {Hemicardium Barr., non Cuvier). Without byssal sinus.
Silurian.

Additional genera : Amita {Spanila, TetinJca), Mila, Tenha, Bahinha {Matercula)
Barrande. Silurian.

CLASS I

PELECYPODA

445

Family 17. Ambonychiidae Miller.

Shell mytiliform, with no anterior wing, the anterior adductor obsolete; equivalve,
very inequilateral ; dentition obsolete or schizo-
dont ; licjament external,^ multivincular (?) ;
byssus passing through a narrow gape hetween
the valves which are otherwise closed. Ordo-
vician to Devonian.

The typical Amhonychia, according to Ulrich,
is edentulous ; the fornis ordinarily i)assing under
that name being now referred to Byssonychia, In
this group the byssus does not pass through a
notch in one of the valves.

The Ambonychiidae include the typical meni-
bers of Amhonychia, JByssopteria and Amphicoelia
Hall ; Opisthoptera {Megaptera) Meek ; Anomalo-

dontamm^v, Byssonychia and AUonychia UMch, a, Byssonychia sp. Cincinnati Group; Cin-
and their allies. cinnati, Ohio. Interior of right valve. V, (after

Miller). B, B. radiata (Hall). Same locality.

Byssonychia Ulrich {big. 668). Hinge
with several small cardinal and two or three slender lateral teeth ; area striated ;
byssal opening present in tlie upper half of the anterior face ; otherwise as in
Ämbonychia.

Silurian. Mytilarca and Plethomytilus Hall. Devonian.
{Cyrtodontopsis Frech.). Thicker shelled, with heavier and
Devonian.
Edentulous, concentrically sculptured. Ordovician.

Paleocardia Hall.
Gosseletia Barrois
more numerous teeth.
Glionychia Ulrich.

Pinna pyramidalis Münst.
Quader Sandstein ; Schan-
dau, near Dresden. 1/3.

Fig. 670.

Pinnigena scehachi Böhm. Upper Jura ; Kelheim, Bavaria.
External and internal views, 1/3 natural size.

446

MOLLUSCA

PHYLUM VI

Family 18. Pinnidae Meek.

Shell mytüiform^ not alate, dimijarian, the anterior adductor smaller ; equivalve,
truncate and wholly open behind ; edentulous ; area linear ; ligament parivincular^
internal ; shell structure coarsely prismatic, with a thin, partial, nacreous lininfj ;

ferous. Devonian to Eecent.

Palaeopinna Hall. Devonian ; North America.

Aviculopinna Meek. A very small wing in front of the beaks. Carboniferous
and Permian.

Pinna Linn. (Fig. 669). Shell thin, with a long hinge line and emarginate
nacreous layer; valves carinate, the carina sulcate, section triangulär. Jura to
Recent. •

Pinnigena Sauss. (Trichites Plott) (Fig. 670). Muscular imj)ression very large ;
prismatic layer extremely thick ; sculpture divaricate. Jura and Cretaceous.

Atrina Gray. Shell with broad adductor scars ; short hinge line, no sulcus or
carina, the nacreous layer entire. Carboniferous to Recent.

Gyrtopinna Mörch. Jura to Recent.

Family 19. Oonocardiidae Neumayr.

Shell sub-trigonal, anteriorly truncate and gaping, the margins of the gape frequently
produced into a tuhe-like rostrum and sharply serrate helow, the posterior end usually

alate, the wing divided internally hy a longitudinal ridge;
dimyarian, the anterior adductor scars smaller ; equivalve
more or less gaping behind; schizodont, with a single
anterior lateral, and an obscure or obsolete cardinal
tubercle ; area ill-defined, amphidetic ; ligament external,
parivincular ; shell structure cancellate, or built up of
hollow prisms resembling those of Pinna, but not solid ;
valves thick, internally marginate ; byssifeous {?) ; marine,
conocardium almforme Sowerby. Ordovician to Carboniferous.

Lower Carboniferous ; Tournay, Bel-

gium. i/i- This group inchides Conocardium Bronn {Pleurorhynchus

Phill.) (Fig. 671), and Mhipidocardium Fischer. It is ex-
tremely isolated, and comprises some fifty species. These remarkable shells have been
referred by most paleontologists to the Cardiacea, with which they liave no conncction what-
ever except analogy of form with a few aberrant Cardiidae.

Family 20. Pernidae Zittel.
Shell sub-mytiliform, with a broad posterior wing; monomyarian, the anterior adductor

Fig. 671.

Fio. 672.
Ä, Gervülia aviculoides Sow. Oxfordian ; Dives, Calvados. B, G. linearis Bouvignier. Hinge.

absent in the adult ; inequivalve, teeth irregulär or absent, with a serial multivincular
ligament ; byssiferous, with a moderate gape, or none. Permian to Recent.

CLASS I

PELECYPODA

447

This family differs from the Pteriidae chiefly by its multivinciilar ligament in tlie adult
State. It linds its niaximum development in the Jura and Cretaceous.

Bahewellia King. Small, obliqiiely eloii-^Mlud, alate Ijehind, tliree to four den-
ticulations iinder the beaks. Pernnan.

Gervülia Defr. (Fig. 672). Posterior wing obscure, hinge plate thick, beaks
terminal, pointed, with obscure dental ridges siib-parallel
to the long axis of the valve. Trias to Eocene,

Subgenus Hoernesia Laube (Fig. 673). With a streng tooth
under the beak and subtaxodont denticulations on the pos-
terior Cardinal border. Trias.

Fig. G73.

Odontoperna Frech. Quadrate with two to three
oblique dental folds below the beaks. Trias.

Pedalion Solander (Jsognomon Klein ; Perna Brug. ;
Mulletia Fisch.) (Fig. 674). Equi valve, subquadrate,
with terminal beaks, an anterior byssal notch, edentulous Muschelkalk ^"würzburg, Bavaria.
hinge, and numerous ligamentary grooves. Trias to Recent.

Alpine Trias. Pernostrea Munier- Chalmas. Jura.

Inoceramus Sowerby (Gatillus
Brong. ; Haploscapha Conr. ; Neo-
catülus Fisch.) (Fig. 675). Rounded

Fio. 674.

Pedalion soldanii (Desh.). Oligocene ; Waldböckelheim,
near Kreuznach, Prussia. 1/2.

hwceramus cHpsi Mant. Upper Cretaceous
Gosau, Austria. 1/2 natural size.

with concentric sculpture ; prominent, rather anterior beaks,
and edentulous hinge bearing numerous small ligamentary pits.
Jura, and especially the upper and middle Cretaceous.

Subgenera ; Actinoceramus Meek (Fig. 676), with radial sculp-
ture.; Volviceramus Stol. ; Anopaea Eichw. ; Haenleinia Böhm.

Grenatula Lam. Thin-shelled, elongate, smooth. Jura (?),

Pliocene and Recent.

Family 21. Pteriidae Meek.

Shell aviculoid, Malaie, monomyarian, inequivalve, with an
alivincular ligament ; the hjssus issuing hy a notch in the smaller
valve ; the yonng dimyarian, the anterior adductor disappearing
with age. Silurian to Recent.

Pteria Scopol! (Avicula Brug.) (Fig. 677). Cardinal
border in the young with pseudocardinal and lateral teeth, becoming more or less
obscure with growth ; shell thin, oblique. Devonian to Recent.

A et inoceramus sulcatus
Park. Gault; Perte du
Rhone, Ain. i/j.

448

MOLLUSCA

PHYLÜM VI

Sub^^enera: Adinopteria, Leiopteria, VertiLmnia Hall. Devonian. Pteronites WQoy.
Devonian and Carboniferous. ? Rittotia de Kon. Carboniferous. Oxytoma Meek (Fig. 6/8).
Trias to Cretaceous. Mcleagrina Lam. Jura to Recent.

Limoptera Hall (Monopteria Meek ; Myalinodonta, Parops
wing reduced, posterior large. Devonian and Carboniferous.

ffililert). Anterior

Fig. 677.
Pteria contorta
(Porti.). Rhae-
tic; Kössen,
Tyrol.

Fici. 678.

Pteria (Oxytoma) costata Sow. Great Oolite
Luc, Calvados.

Fig. 679.

Pseudomonotis ecliinata Sow. Cornbrash
(Oolite) ; Button, England.

Pteroperna Morris and Lycett. Middle Jura.

Pseudomonotis Beyr. {Eumicrotis Meek) (Fig. 679). Left valve fiat, anterior wing
not developed or minute. Devonian to Cretaceous,

Gassianella Beyr. (Fig. 680). Left valve inflated with prominent incurved beak ;

Fig. 680.

Gassianella gryphaeata (Münst.). Upper Trias
St, Cassian, Tyrol.

Fig. 681.
Monotis salinaria (Schloth.). Red

Alpenkalk (Norian) ;
Bavaria. -j^.

Berchtesgaden,

the right Hat or concave, witliout byssal sinus ; teeth small as in Pteria, but more
numerous ; area ampliidetic, wide. Trias.

Monotis Bronn (Fig. 681). Equivalve, compressed, radially striate, witli low, sub-
central beaks ; anterior wing indistinct, rounded ; posterior wing short, truncate or
oblique. Trias.

Halohia Bronn {Daonella Mojs.) (Fig. 682). Equivalve like Monotis, but the

Halohia {Daonella) lommeli Wissm. Lower Keuper (Norian) ;
Wen gen, South Tyrol.

Fig. 683.

Posidonomya hecheri Bronn. Culm Measures :
Herborn, Nassau, i/^.

anterior wing only represented by a smooth non-projecting area (Halohia), or botli
wings absent (Daonella). Abundant in the Trias.

CLASS T

PELECYPODA

449

Posldiniininjd V>v(nn\ {Ahlacomnja Stciiini.) (Fig. 683). EciuivaTve, lliiii, (•(Mii]ir<->('d,
coiicentiically wavcd ; liiiigc inargiii sti;iigli1, cdciilulous ; valves not auriculate ; beaks
sub-ceiitral, not conspicuous. Sihuian lo Jul■a^i<i(•. Ovcr fifty species are known ;
very jjrofiise in tlie Jura-Trias, sometinies forniing massive beds.

Malleus Lam. ; (?) Pltilohrya Carpenter ; (?) Hochstetteria Velain. Recent.

heaks

Aucella mosqucnsis Keys. Upper
Jura ; Moscow, Russia.

Family 22. Myalinidae Frech.

Shell obliquely ovate, widened hehind, sometinies lüith a small anterior ear
anterior or terminal ; hinge edentulous, straight ; area
amphidetic, longitudinally grooved ; ligament parivin-
cular (?) Adductor scars suh-equal ; hyssal notch distinct.
Silurian to Jura.

Myalina de Kon. Shell thick, ol)lique, with deep
adductor scars anteriorly under the terminal beaks.
Silurian and Devonian.

Hoplomytilus Sandb.; Myalinoptera Frech ; Ptycho-
desma, Mytilops and Modiella Hall. Devonian. Leio-
myalina Frech ; Aphanaia, Posidoniella de Kon. ; Liebea
Waagen ; Atomodesma Beyr. Carboniferous.

Pergamidea Bitt. Thick-shelled, equivalve, inflated ; anterior auricle distinct,
sharply truncated ; hinge margin notch ed below the beak. Trias of Asia Minor.

Mysidia Bitt. Anterior ear reduced. Trias.

Aucella Keys. (Fig. 684). Tliin, inequivalve, inflated, small, concentrically
waved, sometinies with radial Striae. Left valve larger, arcuate, witli very small
anterior ear ; riglit valve flatter and smaller. Area short,
striated, with a ligamental sulcus below the beak. Upper Jura
and Cretaceous ; distribution world wide.

Family 23. Vulsellidae Adams. ^

Shell Ostreiform, not alate, monomyarian, edentulous, inequi-
valve, with an alivincular ligament ; hyssus wanting ; otherwise
as in the Pteriidae. Tertiary to Recent. A degraded type
which has become specialised through commensalism with
Sponges.

Vulsella Lam. (Fig. 685). Shell vertically produced,
irregulär, edentulous, with a triangulär chondrophore for the
Eocene to Recent.

Vulsellina de Raine. Eocene. (?) Ghalmasia Stol. Creta-

s. (? suh Ostreidae.)

Superfamily 4. OSTRACEA Goldfuss.

Shell degenerate, sessile, inequivalve, generally edentulous,

wings obsolete; with a sub-nacreous or porcellanous inner and

,■ 2tt prismatic outer layer ; epidermis inconspicuous ; area amphidetic,

Miiiich', ligament alivincular ; foot and byssus ahsent ; valves usually

close-fitting ; mantle lobes free, without siphons.

ligament

Fin. 685.

Vllhrll,, r,,;/hni

E!,'ypt. -'/o.

Family 24. Ostreidae Lamank.
Shell distorted by early adherence to other objects ; monomyarian, the anterior

l)nvrill,\ //.. Ktudes sur Irs Vulsc'llidc's. Ami. Fiilroiit.. 1907, vol. ii.

VOL. 1

2 G

450

MOLLUSCA

PHYLUM YI

adductor ahsent ; edentulous, or luith ohscure schizodont dentition ; dimijarian when
young ; the foot obsolete or ahsent in the adidt. Carboniferous to Recent.

Ostrea Linn. (Fig. 686). Shell irregulär, iiiequivalve, and witli terminal beaks,

Fio. 686.
Ostrea digitalina Dubois. Miocene ; Vienna Basin.

Fio. 687.

Alectryonia (jregaria
(Sow.). Oxfordian ;
Dives, Calvados.

witb radial or foliaceous sculpture, usually discrepant on the two valves. Some species
(0. virginica^ titan, gigantea, etc.) attain a very large size. Carboniferous to Recent.

Alectryonia Fischer (Dendrostrea Swains ; Adinostreon Bayle) (Fig. 687). Left
valve attached to roots or branches by clasping shelly processes ; botli valves with
strong, often divaricate folds and undulate margins. Trias to Recent ; maximuni in
Jura and Cretaceous.

Gryphaea Lam. {Pycnodonta Fisch.; Gryjjhaeostrea Conr.) (Figs. 688, 689). Left

Fig. 688.

Gryphaea arcuata Lam.
Lower Lias ; Pf obren, near
Donfiuescbingen, Baden.

Fig. 689.

Gryphaea vesicularis Lam. Wlxite Clialk
Isle of Rügen.

valve strongly arched, with incurved beak, sessile when young, later free ; right valve
flat and opercular. Lias to Tertiary ; chiefly Mesozoic.

Exogyra Say {Amphidonta Fischer ; Geratostreon, Aetostreon^ Ehynchostreon Bayle)
(Figä. 690, 691). Resembliug Gryphaea, but the valves more equal, hinge with an
obscure tooth, beaks of both valves niore or less spiral, the pit for the ligament narrow.
Upper Jura and Cretaceous.

CLASR I

PELECYPODA

451

Terquemia Täte {Garpenteria DesL). Shell witli a marginal ridge, f
right valve ; left valve fiatter, free. Trias and Lias.

sessile by the

Fig. 690.

Exogyra columha Lam. Greensand (Ceno-
manian) ; Regensburg, Bavaria.

Fig. 691.

Exogyra flahelkitoi (Goldfuss). Cenomanian
Saint Paul Cloister, Egypt.

Family 25. Eligmidae Gill.

Shell thick, suh-equivalve, free lohen adult, resemhling Chalmasia in form, anteriorly
with an irregulär pedal gape ; edentulous, monomyarian, tüith the adductor seated on the
free extremity of a myophore projecting from the umhonal cavity, otherwise like the
Ostreidae. Upper Jura.

Eligmus Desl. If the cliaracters of this genus liave been correctly interpreted, it
can hardly be retained in tlie Ostreidae. Fiirther investigation of tlie genns is
desirable.

Superfamily 5. NAIADACEA Menke.

Shell of varied form, normally equivalve and dimyarian ; rarely alate ; shell
suhstance nacreous and prismatic, loith a conspicuous epidermis ; area ohsßure er
amphidetic ; ligament parivincular, usually opisthodetic and external ; pallial lobes
usually free, except for an anal siphon, the pallial line simple; foot normally long,
compressed, heeled ; hyssus obsolete ; young usually with a distinct nepionic stage ; Station
usually fluviatile or lacustrine.

Family 26. Oardiniidae Zittel.

Shell equivalve, closed, with feehle concentric sculpture or smooth ; dentition schizodont
or ohscure ; ligament opisthodetic, external ; dimyarian, adductor scars suh-equal, pedal
scar feehle or invisihle ; Station marine or hrackish water. Devonian to Trias.

Ämnigenia Hall. Devonian (Catskill) of North America, and Rhenish Priissia.

Garhonicola M'Coy {Anthracosia King) (Fig. 692). Shell thin, oblong ; hinge
with a blimt elongated cardinal, and a feeble posterior lateral tooth upon a thickened
hinge plate. Common in the Goal Measures and estuarine Permian of Rnssia, also
America and Africa.

Naiadites Dawson {Anthracoptera Salter). Shell modioliform, obliquely triangulär,
Avitli almost terminal beaks, straight hinge-line, striated hinge-plate, and superficially
marked with flat concentric lamellae. Goal Measures ; North Amei-ica and Europe.

452

MOLLUSCA

PHYLUM VI

Anthracomya Salter ; Asthenodonta Whiteaves. Goal MeaBures. Palaeomutela
(Ohligodon) and Palaeanodonta Anializky. Brackisli Perniiaii marls of Europe,

Anoplophora Sandb., emend. von Koenen (Uniona Poldig) (Fig. 693). Eiglit valve
with a blunt tliick cardinal tootli fitting into a .socket in tlie opposite valve. Left
valve beside tlie socket has a long posterior lateral tootb. Trias (Lettenkoble). A.
donacina Scblotli. ; A. leitica (Quenst.).

Anoplophora lettica (Quenstedt).
Trias ; Friedrichshall (after Al-
berti).

A

Fig. 692.

A, Carhonicöla carbonaria (Goldfuss).
Permian ; Niederstaufenbach, near Kusel,
Rhenish Bavaria. B, C. Uttneri (Ludw.).
Goal Measures ; Hannibalzeche, near
Bochiim, Westphalia (after Ludwig).

Fig. 694.

Trigonodus sandhergeri Alberti.
Trias (Lettenkohle); Zimmern,
Würtemberg. A, Hinge, from a
gutta-percha cast taken from a
natural mould. 7i, Natural mould.

Vi-

Trigonodus Sandb. (Fig. 694). Cardinal tootli strong, triangulär, sometimes
divided, short, oblique, anterior ; two elongate laterals in the left valve, and one
lateral in the right valve. Trias ; especially common in the Lettenkoble dolomite
and the Eaibl beds.

Heminajas Neumayr. Trias. H. (Myophoria) fissidentata Wöhrmann.

Pachycardia Hauer. Oblong or trigonal, concentrically striate or smooth ; beaks
nearly terminal, curved, adjacent, with a lumule ; anterior end inflated, blunt;
posterior compressed ; two strong divergent cardinal teetli in each valve, the anterior
on the right being weaker and nearly marginal ; each valve has also a long posterior
lateral tooth. Alpine Trias.

Gardinia Agassiz {Tlialassites Quenst.) (Fig. 695). Oblong, thick, short anteriorly,

Fig. 695.
Lower Lias ; Ohrsleben, near Halberstadt, Saxony.

Cardinia hyhrida Sow.

rounded. Cardinal teeth weak or obsolete, posterior lateral strong. Lower Lias, and
reported also from the Dogger.

{TjNyassa Hall. Devonian. (i) Guerangeria {Davousti) (Ehl&ci. Lower Devonian.

CLA.SS I

PELECYPODA
Family 27. Megalodontidae Zittcl.'

453

> Shells equivalve, sah-mytüiform, closed, witli feehle concentric sculpture or none ; di-

myarma, with amphidetic area, and external opisthodetic ligament, frequently supported
hy nijmphae; cardinal teeth strong, usually two or three, ivith a posterior lateral, all

Fig. 696.
MigiiJniliiii (Eumcijalodon) cucullatus Goldf.
near Cologne. i/^.

Devonian ; Pattrath,

tri'iurti i{\\'uUtiu). lutenial
niould. Trias dolomite ;
Bleiberg, Carinthia.

Fio. 698.
Megalodon (Neomeij'ilniltiii) fiilmheli Stoppani. Rhaetic ; Elbigenalp, Tyrol (after Gümbel).

heavy and amorphous ; anterior adductor scars distinct, with a ivell-marked myophoric
ridfje and pedal scar, the posterior adductor scars frequently hordered hy an elevated
crest. Marine. Silurian to Upper Jura.

These Shells, which are ofteii very ponderous, sometimes bear a remarkable resemblance
to some Recent American Uniones. The myophoric ridge is common to very distinct bivalves
of many unrelated groups. The true position of these forms cannot be regarded as positively
üxed as yet. Pachyrisma is thought by Böhm to be genetically related to Cardium, and the
genus Mcgalodon niay have been ancestral to primitive Chamacea.

Megalodon Sow. {Tauroceras amd Lycodes Schafli. ; Conchodon Stopp.) (Figs. 696-698).

^ Gümhel, C. W., Die Dachsteinbivalven. Sitzuiigsber. Akad. Wiss. Wien, 1862, vol. xlv. —
ITocnu's, R., Materialen zu einer Monographie der Gattung Megalodus. Denkschr. Akad. Wiss.
Wien, 1880, vol. xl. — Böhm, G. Megalodon, Pachyrisma und Diceras. JSer. Naturforsch.
Gesellsch. Freiburg, 1891, vol. vi.

454

MOLLUSCA

PflYLUM V

Beaks prosogyrous ; hinge plate veiy broad and massive, without laterals ; tlie two
cardinal teetli separated by a deep socket ; anterior adductor scar small, seniilunar,
in front of the anterior cardinal ; posterior scar longer, less distinct, sitiiated on an
elevated or thickened radial ridge. The oldest Devonian species (M. cucullatus Goldf.)
has amorphous cardinals and a sniooth rounded shell (ßumegalodon). The Triassic
species sometimes attain a large size, have a radial posterior ridge, smooth teeth, and
divided right posterior cardinal teeth {Neomegalodon Gümb.). They are extraordinarily
abundant in the Dachstein limestone and Hauptdolomite of the Northern Alps, and
are also plentiful in the Raibl and Rhaetic beds of the Southern Alps.^

Pachyrisma Morr. and Lyc. {Pachymegalodon Gümb.). Like MegalodoUy but with
a larger anterior adductor scar, a rounded anterior tooth before the cardinals, and a
strong posterior lateral. Trias to Upper Jura.

Durga Böhm. ■ Like Pachyrisma, but without an elevated area at the posterior
adductor. Lias.

Protodiceras Böhm. Lias. Dicerocardium Stoppani. Rhaetic.

Megalomus Hall. Silurian ; North America.

Family 28. Unionidae Fleming.

Shell equivalve, dimyarian, typically schizodont, ivith pseudocardinals and laterals
if dentiferous ; conspicuously nacreous ; beaks usually sculptured ; ligament opisthodetic,
external ; lohes of the mantle generally united to form an anal siphon, hut the functional
hranchial siphon always incomplete helow ; foot compressed, keeled, large, rarely with a
feehle hyssus ; usually dioecious ; the young having a specialised prodissoconch
{glochidium) and a distinct nepionic stage. Fluviatile. Trias to Recent.

Typical Uniones make their appearance in the Trias of Texas, but are not abundant until
the Cretaceous and Tertiary. The origin of the family has been sought in the Trigoniidae,^
which have a very similar ontogeny as a group ; in Trigonodus ^ and related forms ; and by
Pohlig in the Triassic Uniona. An older view recognises the Carboniferous Anthracosia and
other Cardiniidae as probable ancestors. The weight of evidence is in favour of the latter,
thougli there is much probability that each of these groups bears a certain amount of relation-
ship to the present family, which will be better realised when niore evidence is obtainable.

Recent studies by Simpson and Ortmann of the anatomy of living genera of Unionidae
have sliown that considerable ditFerences exist as regards the soft parts, more especially the

Fig. 699.
Unio stachei Neumayr. Pliocene (Congerian stage) ; Sibinj, Sla venia, p, Adductor ; x, Pedal scar.

marsupial apparatus (that part of the gills which contains the glochidia) and the shape of
the glochidia. These differences permit of an improved System of Classification for the
modern forms, but as the shape of the shell is not at all correlated with the natural divisions
indicated by the structure of the soft parts, it is impossible to apply tliis System with
certainty to fossil Unionidae.

Unio Retzius (Fig. 699). This, the typical genus, originally included also the pearl

^ Tausch, L. vo)i,_tJheT Conchodus, etc. Abhandl. geol. Keichsanstalt, 1892, vol. xvi.
2 JSTeumayr, M., Über die Herkunft der Unioniden. Sitzber. Akad. Wiss. Wien, 1889, xeviii.
•^ Wöhrmann, S. von, Über die systematische Stellung der Trigoniden und die Abstammung
der Nayaden. Jahrb. geol. Reichsanst., 1893, vol. xliii.

CLASS I PELECYPODA 455

müsse] {My(c tnargaritifera Liiiii.), in which tlie posterior luiiiiiiac of the liinge are
obsolete. It sliows in the niajority of species aniorplious, heavy, radial, pseudocardinal
and lateral teetli on the hinge ; the sliell is variable in form and ornamentation, some
species having strongly marked sexual difterences in the shell. Most of the species
are peaiiy, with a conspicuous brown or greenish periostracum ; the anterior adductor
scars are high, and the pedal scars conspicuous.

Änodonta Cuv. Valves thin, and armature of the hinge obsolete ; lives in still,
muddy water. Tertiary and Recent.

Margaritana Schum. The pearl mussei, formerly associated with Mya and Unio^ is
anatomically intermediate Ijetween the Unionidae and Mutelidae. Tertiary and Eecent.

Family 29. Mutelidae Gray.

Shell resemhling that of the Unionidae, without pseudocardinals and laterals ;
having, when dentiferous, an irregularly taxodont hinge armature; heahs unsculptured ;
mantle lohes generally partly closed ; siphons more complete. Nepionic stage {Jcnovm
only in a fev) South American forms) said to he represented by a Lasidium. Cretaceous
to Recent.

Spatha Lea. Elongated, inequilateral, with a short edentulous hinge. Living in
Africa, and doubtfully present also in the Upper Cretaceous of Provence.

Anodontites Bruguiere (Glaharis Gray) ; Leila Gray ; Monocondylaea and Mycetopoda
d'Orl).; Mutela Scopoli {Iridina Lam.); and Pleiodon Conrad. Recent. Two
subfamilies, Mutelinae and Hyriinae, are recognised by Ortmann on the basis of
structural differences in the soft parts.

Family 30. Etheriidae Lamarck.

Shell sessile, irregularly modified by adherence to other bodies, nacreous, with a
tendency to cellularity of structure ; edentulous; ligament amphidetic, parivinculary
deeply sunken, with a large internal resilium, modified by the distortion of the valves ;
young regulär, equivalve, dimyarian ; the adult irregulär, inequivalve, and either (1)
monomyarian, or (2) with a very degenerate anterior adductor, or (3) with sub-equal
adductors. Mantle lobes united only for the anal siphon ; foot degenerate or absent in
the adult ; young hyssiferous ; Station ßuviatile. Pleistocene and Recent.

The young shell of Bartlätia has well-niarked nymphae and internal resilium. The
relationship of the Naiadacea to Pteria renders the remarkable resemblance of the adult
Muelleria to Ostrea less surprising, siiice Ostrca is now known also to be derived from the
Pteriidae.

Etheria Lam. Ostreiform, attached to rocks in African rivers. Also Pleistocene
of West Africa.

Muelleria Ferussac ; Bartlettia Adams. Recent ; South American rivers.

Superfamily 6. TRIGONIACEA Bronn.

Shell equivalve, inequilateral, closed, dimyarian, not alate ; shell suhstance nacreous
and prismatic ; hinge teeth few, sub-umbonal, typically schizodont ; area obscure or none ;
ligament parivincular, opisthodetic, external ; gills filibranchiate ; mantle lobes usually
free, but modified on the posterior edges to form functional siphons without conjunctive
partitions ; pallial line usually simple; non-byssiferous, though possessing an obsolete
byssal apparatus ; young without a distinct nepionic stage ; dioecious ; marine.

Family 31. Lyrodesmidae Ulrich.

Shell with the hinge armature radiating fan-like from below the umbones ; teeth five
to nine; pallial line feebly sinuate or simple. Ordovician and Silurian.

LyrodesmM Conr. {1 Actinodonta Phil.). Shell oval, cardinal boixler narrow, wiili-
out ligamentary area. Ordovician and Silurian ; America and Europe.

456

MOLLUSCA

PHYLÜM VI

,, siuootli ; lateral teetli not fliited
Abiiiidaiit 111 the Periniaii.

Family 32. Trigoniidae Lamarck.

Shell with few hinge teeth (|), the mantle lohes lüholly free, hut so applied to each
other in life as to form functional siphons ; pallial line simple. Devoiiiaii to Receiit.

Schizodus King (Fig. 700). Ovate or quadrate,
anterior adductor scar witli a sniall radial buttress.

MyophoriaBi-oiiii{Neoschizodus ^^ Gieb.) (Figs. 701, 702).

Smooth or radially sculptured, \^^ ^J usually with a strong

radial ridge extending from the ^^^^!^^^ uinbones back ward and

down ward to the basal margin ; ^^^r the sciüpture on the areas
AB

Fig. 700.

Schizod7is obscürus Sow. Zeclistcdn; Nieder-
rodenbach, near Hanau. A, Internal niould,
Vi. B, Hinge, i/i (after King).

Myophoria lasvigata
(Alberti). Schaumkalk ;
Rüdersdorf, near B(!r-
lin. Vi-

M yitpliAyrUt decustiata Münst.
Upper Trias ; St. Cassian, Tyrol.

A, Bxterior of riglit valve, Vi'

B, Enlarged vlew of hinge.

Trigonia navis Lam. Lower Brown Jura ;
Gundershofen, Alsace. Vi-

Trigonia dandala Park. Middle Crcitaceous
(Hervien) ; Meule de Bracquegnies, Belgium. i/i.

Fig. 705.

Trigonia costata Sow,
Middle Jura ; Würteißterg.

Fig. 706.
Trigonia cf. aliformis Park. Senoni;
Vaels, near Aix-la-Chapelle. i/i-

Fig. 707.

Trigonia pectinaia
Lamarck. Recent;Aus-
tralia. Hinge, l/i.

CLASS 1

PELECYPODA

457

thus Heparated usiially discrepaiit. Beaks inesogyrate, lateral teetli fluted, inuscular
scars biittressed by feel)le ridges. Abuiidaiit in the Trias.

Siil)genus : Myoijhorio'psis Wüliriii. {Astartopsis Wölir.). Trias.

Trigonia Brug. (Figs. 703-707). Surface sculptured witli iiodulose ribs or rows of
pustiiles, tlie 2>osterior dorsal area usiially discrepaiit witli tlie rest. Beaks opistho-
gyrous, nearly teriuinal ; teetli striated ; addiictor scars stroiig, with biittressiiig ridges.
Lias to Recent ; abuiidant in Jura and Cretaceous, very sparse in later horizons.

Section D. Isodonta Fischer.

Superfamily 7. PECTINACEA Reeve.

Shell usually inequivalve, ßabelliform, more or less auriculate, and monomyarian ;
shell structure sub-nacreous, corrugated, and rarely prismatic^ occasionally tahular ; area,
when present, amphidetic ; ligament amphidetic, alivincular ; gills filibranchiate, free, the
filaments loith or withoiU a reßected limb ; mantle lobes free, without siphons, usually with
ocelli, papillae, or other tactile prominences along the margin, and with an inner pro-
jecting lamina (curtain) near the margin, at right angles to the plane of the valves ; pallial
line simple ; foot small, usually sub-cylindrical, grooved, and byssiferous ; usually mon-
oecious : marine.

Family 33. Pectinidae Lamarck.

Shell inequivalve, inequilateral, auriculate, usually closed,
free; area amphidetic or obscure ; ligam.ent obsolete extern-
ally, the immersed portion forming an internal resilium,
provinculum taxodont in the very young, obsolete later, the
crural teeth feeble or not developed. Silurian to Recent.

Aviculopecten M'Coy (Fig. 708). Shell pectiniforni,
radially sculptured. Hinge margin long, feebly auriculate;
ligament in numerous shallow grooves radiating to the
amphidetic margin of the area. Silurian to Carboniferous.

Subgeiiera : Ficrineo2)ecten Hall
2)ecten Hall). Devonian.

monomyarian, us

ually

Orhipecten Frech {Lyrio-

Fio. 708.

Ä viculopecten
Goal Measures
phalia.

]Hipyraccus Sow.
Werden, West-

Grenipecten Hall (Pernopecten Winch.). Like Aviculo-
pecten, but with a taxodont hinge. Carboniferous.

The preceding genera lead up to the prototypes of Pteriidae
as a radical for the present family.

Pecten Müller {Vola Mörch ; Janira Schum. ; Neithea
Drouet) (Fig. 709). Shell nearly equikteral, very inequi-
valve, sub-symmetrical, with well -developed, sub-equal
ears ; one valve (usually the right) more convex than the
other ; interior of the valves not lirate ; hinge with a
strong medial internal resilium, on each side of which
interlocking crural ridges and grooves radiate in the
adult ; Ijyssal notcli inconspicuous. Cretaceous to Recent.

The above diagnosis is of the subgenus Pecten s. s. In a
Wide sense all the species of Pecten are free and auriculate, and
without internal lirae. Thoy have been divided into an ex-
cessive number of sections aecording to the superficial shell characters, but these rarely
niarch with anatomical differences, and cannot properly be regarded as of generic value. The
most familiär of the groups thus named are as follows : —

Chlamys Holten {Pallium Schum.; Decadopedcn Rüpp.) (Figs. 710, 711). Shell radially

l'ecten quinquecostata Sow. Ceno-
manian ; Rouen. i/i-

458

MOLLUSCA

PHYLÜM VI

sculptured, nearly equivalve, with small, iinequal ears, and deep byssal notch with well-
developed ctenolium. Trias to Recent.

CamjJtonectes Ag. (Fig. 712). Shell small, tliin, nearly smootli, with fine divergent
striation radiating from a median line. Jura to Recent.

Fio. 710.

Peden (Clüamys) suUextorius
Goldf. Coral-Rag ; Nattheim.

Fio. 711.

Peden (Chlamys) varius Linn.
Pliocene ; Rhodes.

Fk;. 712.

Fig. 713.

Peden (Ento-

liwrn) cornutus

Peden {Camptonedes) Uns Qnenst. Upper

Sovv. Middle Jura ; Baiin, Jura ; Hohen-

near Cracow. i/^. zolleni. i/i.

Entoliutn Meek (Fig. 713). Smooth, thin, with sub-equal ears diverging at a sharp angle
above the beaks ; byssal notch obsolete. Carboniferous to Cretaceous.

Pseudamusium Adams. Shell small, thin, glassy ; the posterior ear obsolete, byssal notch
distinct. Cretaceous to. Recent. Syncyclonema Meek is scarcely different.

Amusium Bollen (Fig. 714). Shell with raised radial riblets interiially ; ex-

FiG. 714.
Ämuslwin cristatus (Bronn). Miocene Baden, near Vienna. l/i.

Fig. 715.

Hinnites ahjcdus (Phill.).
Middle Jura ; Baiin, near
Cracow. i/i.

ternally smootb. or delicately sculptured ; valves large, flattish, with sub-equal ears ;
byssal notch inconspicuous or absent. Lias to Eecent.

Subgenus : Propeamusium Greg. Small, thin, abyssal^, often with relatively conspicuous
sculpture, usually discrepant on the valves. Tertiary and Recent.

Hinnites Defr. (Fig. 715). Shell free and Pectiniform when young, later adherent
to other objects and more or less distorted. Trias to Eecent.

Pedum Brug. Shell with an alivincular ligament in an oj)en groove and area like
that of Spondylus in the adult ; the young like Ghlamys. Eecent ; sessile on corals.

Family 34. Spondylidae Fleming.

Shell inequivalve, nearly equilateral, closed, 'pectiniform, obscurely auriculate, mono-
myarian; sessile; area amphidetic,7nuch larger on the attached valve; ligament alivincular^
rmlium more or less suhmerged ; byssus obsolete; hinge with a taxodont provinculum,

CLASS I

PELECYPODA

459

hecoming obsolete in the adiUt and re-placed hy the tyjncally isodont develo^ment of the

crura ; otherivise as in the Pectinidae. Trias to Recent.

Plicatula Lam. {Harpax Park.) (Fig. 716). Shell
conipressed, with coarse radial, often divaricate
ribbiiig, a small area, and long shallow crenulate
crural teeth, diverging at a sharp angle. Trias to
Recent ; inaximum in Jura and Cretaceous.

Spondijlus Linn. (Figs. 717, 718). Sliell inflated,
with radial, often spiny or foliaceous sculpture ;

Fio, 716.

Plicatula 2)ectinoides Lara. Middle Lias ;
Nancy, France.

Fio. 717.

Spondylus spinosus (Sow.). Plänerkalk ;
Strehlen, near Dresden. 2/3.

Fio. 718.

Sptondylus tenuisplna Sandb. Oligocene ; Waldböckelheim, near
Kreuznach, Prussia. 1/1.

Jura

attached valve with a conspicuous area ; crural teeth heavy, short, smooth.
to Recent ; maximuin from the Tertiary onward.

(?) Pachijpteria de Koninck. Carboniferous. P. nobilissima (de Koninck). Pro-
spondylus Zinimerin. Pennian and Trias. Philippiella Waagen. Alpine Trias.

Family 35. Dimyidae Dali.

Shell inequivalve, irregulär, closed, auricles not differentiated, Ostreiform, dimyarian,
shell suhstance suh-nacreous and

fihrous ; area amphidetic, ohscure ; liga-
ment obsolete, resilium alivincular, in-
ternal; hinge armature taxodont, obsolete;
crural development feeble; gills fili-
branchiate, the direct filaments not
reflected; foot and byssus absent ; an-
terior adductor distinct, small ; posterior
duplex, larger. Trias to Recent.

Dimya Rouault {Dimyodon Mun.-
Chalni.) (Fig. 719). The Recent forms inhabit deep water.

Fio. 719,

Dimya deshayesiana Rouanlt. Eocene ; Pyrenees. Inner
and outer views of right valve, 3/2 (alter Rouault).

Family 36. Limidae d'Orbigny.

Shell equivalve, auriculate, gaping, Pectiniform, monomyarian ; shell substance
fibrous, with minute tubules, not nacreous or prismatic ; hinge edentulous, or with traces
of taxodont armature; area amphidetic, eqiial in both valves ; ligament alivincular,

460

MOLLUSCA

PHYLÜM VI

luaximiim m

resilium suh-internal ; gills filibranchiate ivith cUrect and reßected li7iibs ; foot small
digitiform, usually hyssiferous, the byssus passing through the gctpe of the valves.
Carboniferoiis to Receiit.

Lima Bi'ug. Shell inflated, with radial sculpturc ; beaks pointed, and separated
by a lozenge - shaped area ; edentuloiis.
Carboniferoiis to Recent
Mesozoic (over 300 species).

Subgenera : Lima s. s. {lladula
aiict, 71071 Gray) (Fig. 720). Shell wil
strong radial ribs.

Fio. 722.

Lima (Limatula)
it ihbosa S o w.
ijower Oolite ;
üayeux, Calvados.

Fio. 720.

Lima peetinoides Sow.
Lower Lias ; Balingen,
Würteinberg. i/j.

Fig. 721.

Lima {Flagiostoma) gigantea Sow. Lower Lias :
Göppingen, Würtemberg. 2/.^.

Fig. 723.
Limaea dupli-
cata Goldf. Great
Oolite ; Lan grüne,

Xoi-iiiaiidy.

Fig. 724.
Ctenostreon proboscidea Sow. Oxfordian ; Dives, Calvados.

Flagiostoma Sow. (Fig. 721). Sniooth or finely striated.

Limatula Wood (Fig. 722). Medially ribbed, laterally smooth, valves not gaping.

Limaea Bronn (Fig. 723). Small, with taxodont armatiire at the angles of the
hinge. Lias and Recent.

Ctenostreon Eichw. (Fig. 724). Compressed, irregulär, thick-shclled, with coarse
radial ribs. Upper Jura. Badiotella Bittner. Alpine Trias.

CLARS I

PELECYPODA
Superfamily 8. ANOMIACEA Herrmannsen.

4G1

Shell monomyarian, not alate ; edentulous or isodont, usually sessile ; shell substance
nacreous, tuhidiferous, ivith traces of a prismatic layer ; area ohscure, usually small,
amphidetic ; ligament ohscure, ivith an alivincular internal resilium ; (jills filibranchiate,
mantle lohes free ; foot small, grooved, digitiform ; dioecious ; marine.

Family 37. Anomiidae Gray.

Shell variable, irregulär and inequivalve when sessile, byssiferous vjhen young ; in
most genera the hyssus becomes modified to a calcißed or horny flug ^Kissing through
a foramen in the right valve, and fastened to other ohjects, a condition which may he
permanent or transient ; area small, amphidetic ; ligament amphidetic, more or less
internal, supplemented by an internal resilium, for which the crura serve as chondrophores,
ali- or multivincular ; hinge usually edentulous, rarely rugose, with amorphous inter-
loching rugosities ; posterior adductor small, sub-central, in the sessile forms reinforced by
the pedo-byssal muscles, which are modified for Service as adductors. (?) Devonian. Jura
to Kecent.

Anomia Müll. Shell thin, sessile by tlie calcified byssus passing through a siiiiis
or Perforation in the right valve, conforming to the subjacent surfece ; the left valve
more convex, with four miiscular scars on
a central area ; a chondrophore in the
lower valve. Jura to Eecent.

(?) Limanomia Bouch. Devonian.
Hypotrema d'Orb. Jura and Cretaceous.
Placunanomia Brod. Miocene to Recent.

Garolia Cantraine. (Fig. 725). Shell
orbicular, compressed, radially striated ;
right valve with a byssal foramen nearly
closed in the adult ; resilium much as in
Anomia ; adductor scar single. Eocene ;
Egypt.

Subgenus : Wakullina Dali. Smooth ;
byssal foramen obsolete ; the resilium received
on diverging crura on the upper valve. Oligo-
cene ; Florida.

Placenta Retzius {Placuna Brug. ;
Placunema Stob; Pseudoplacuna Mayer).
Shell free, orbicular, thin, very compressed ;
the resilium with long, unequal crura.
Tertiary and Recent.

Ephippium Bolten. Like Placenta,
but the Shell radially waved ; young with a small byssal Perforation, which becomes
closed and obsolete in the adult. Tertiary and Recent.

Placunopsis Morr. and Lyc. Shell rounded, imperforate, free, or sessile. Jura.

Hemiplicatula Desh. {Semiplicatula Fisch.) ; Saintia Raine. Eocene. Paranomia
Conrad. Ripley Group. Monia Gray. Miocene to Recent ; California.

Section E. Dysodonta Neumayr (emend.).
Superfamily 9. MYTILACEA Färussac.

Shell anisomyarian, usually equivalve, not alate or notched for a hyssus, edentulous or
dysodont ; shell substance sub-nacreous, rarely more or less prismatic, with a rom^icuons

Fic. 725.

Carolia placunoides Cantr. Eocene ; Wadi el Tih, near

Cairo, Egypt. Interior of both valves, 2/3.

462

MOLLUSCA

PHYLUM VI

epidermis ; area amphidetic or ohscure ; ligament parivincular, usually opisthodetic and
external ; gills usually ßlibranchiate ; mantle lobes without ocelli, iiiore or less free^
generally with the anal siphon complete and the hranchial incomplete ; foot small, digiti-
form, gi'ooved, hyssiferous ; monoecious ; mostly marine.

Family 38. Modiolopsidae Fisclier (emend.).

Shell modioliform, usually eqidvalve, ß'ee, thioi, with suh-equal adductor scars ;
ligament deep-seated ; hinge edentulous or dysodont ; sometimes hyssiferous. Ordovician
to Cretaceous.

The lieavier fornis show an obtuse ridge or two extending from the beaks toward the basal
margin. The pedal scars are separate from and behind the anterior adductors. The forms

included here aj)pear to be
the prototypes of the Myti-
lidae, from which they difFer
chiefly in those characters
that are common to most of
the ancient types, such as the
sub-equality of the adductor
scars and their more dorsal
Situation. The recent Idas is
very similar.

Modiolopsis Hall (Fig.
726). Valves elongate-
oval, closed, with iiearly
terminal beaks, narrow
hinge plate, and edentulous
hinge, Ordovician and
Silurian.

Modiomorpha Hall.

Similar, but with a wider
hinge plate, and Single,
oblique, elongate, posterior
ridge - like tooth. De-
vonian.

Myoconcha Sow. (Fig.

727). Hinge usually with an elongate cardinal, and a long, weak, lateral tooth in

the right valve ; otherwise resembling Modiolopsis. Carboni-

ferous to Cretaeeous.

(?) Hippopodium Sow. Thick, infiated ovate, concentric-

ally waved. Hinge with a long, blunt, oblique, cardinal

tooth, or edentulous ; adductor scars strong. Jura.

Modiolodon, Whiteavesia, Eurymya, Aristerella, and Prolo-
hella Ulrich; Ordovician; North America. Goniophora

Phillips. Silurian and ]3evonian. Orthonota Conrad. De-

vonian. Orthodesma Hall and Whitf. Ordovician; North

America.

Family 39. Mytilidae Fleming.

Shell equivalve, very inequilateral^ heteromyarian, slightly
gaping, typically dysodont ; area amphidetic or noite ; ligament
usually external^ deep-seated; rarely with an alivincular
internal resilium ; pallial line simple; mantle lohes united
helow the anal siphon, otherwise free; generally hyssiferous.
Devonian to Kecent.

Pio. 726,

Modiolopsis modiolaris
(Conrad). Ordovician ; Cin-
cinnati, Ohio. i/i.

Fig. 727.
Myoconclia striatula Goldf.

Lower Oolite ;
Bayeux, Calvados, i/i-

Fig. 728.

Mytilus suhlaevis Sow. Great
Oolite ; Minchinhampton, Eng-
land, i/i-

CLASS T

PELECYPODA

463

Mytilus Liim. (Fig. 728). Shell elongated, thiii, witli terminal pointed beaks ;
valves wider and rounded beliind, gaping a little for tlie byssus, smooth or radially
sculptured, witli sniootli niargins, conspiciious epiderinis, and a thin nacreous layer ;
hinge with a few small teeth iinder tlie beaks, or edentulous. Trias to Recent.

Pachymytilus Zitt. (Fig. 729). Shell thick, trigonal ; the front margin deeply

impressed. Upper Jura.

Modiolus Lam. (Figs. 730, 731). Like Mytilus,

Pacliy mytilus petasus d'Orb. Coral-Rag ;
Coulaiige-.sur-Yonne. 2/3.

Fi(!. 730.

Modiolus OS- ^^'^- "^l-

per US Sow. Modiolus imhri-

Great Oolite ; cahis Sow. Middle

Langrune, Cal- Jura ; Baiin, near

vados. i/x- CracoWjAn.stria.i/i-

Fio. 732.

Lithopliagus inclusus (Ph\l\.).
Qreat Oolite ; Minchinhamp-
ton, England. A, B, Shell,
1/1. ü, Mould of the burrow.

but the beaks not terminal, edentate, anteriorly rounded and wider. Devonian to Recent.

Subgenera : Modiolaria Loven. Small, radially sculptured toward the ends, usually
smooth toward the middle, modioliform. Tertiary and Recent. Creiiella Brown. Small,
rounded, radially sculptured all over.' Tertiary and Recent.

Stavelia Gray. Recent. Valves spirally twisted.

Litliophagus Meg. {Lithodomus Cuv.) (Fig. 732). Sub-cylindrical, with rounded
ends ; perforating coral, limestone and other substances, in wliieli the animal forms
flask-shaped excavations ; moulds of the latter are often found in the fossil State.
Carboniferous to Recent.

Family 40. Dreissensiidae Gray.

Shell mytiliform, equivalve, of prevailingly prismatic suhstance ; area linear , amphi-
detic ; ligament sub-internal ; anterior adductor and pedal protractors inserted on a
myophoric septum ; mantle lohes united to form anal and hranchial siphons, and also
ventrally with a pedal opening ; pallial line usually simple ; gills reticulate ; otherwise
as in Mytilus. Tertiary to Recent. The relations of this family are in question.

Dreissensia Van Ben. {Tichogonia Rossm.) (Fig. 733). Smooth, without a pearly
layer, with a Single apical septum ; fluviatile and estuarine. Eocene
to Recent ; Europe.

Mytilopsis Conr. Mytiliform, small, thin ; myophore for the
pedal protractor distinct from that which supports the anterior
adductor. Tertiary and Recent ; America.

Gongeria Partsch (Fig. 734). Sub-quadrate,. heavy, large ;
myophores as in Mytilopsis. Very profuse in the Neocene of Eastern
Europe (Congeria beds).

IJreissensiomya Fuchs. Notalgie for being the only example of the
Mytilacea with a distinct pallial sinus. Miocene ; Eastern Europe.

Septifer Recluz. Valves wuth strong radial or divaricate sculpture.
Tertiary and Recent.

Fig. 733.

Dreissensia brardi
Faujas. Miocene ;
Weissenau, near
Mayence. Vi-

Marine

464 MOLLUSCA phylum vi

The Eeceiit families, Juliidae and Modiolarcidae, if their validity be confirmed,

Pi(i. 734.
Congeria suhglohosa (Partscli). Upper Mioceiie ; Inzersdorf, near Vienna.

may find a place in tliis vicinity. Julia Gould {Prasina Desh.), and Berthelinia are
reported from the Tertiary, the former in the Oligocene of Florida.

Order 2. ANOMALODBSMACEA DalL

Superfamily 1. ANATINACEA Dali.

Anomalodesmacea with \/-shaped reticulate gills not secreting a calcareous tuhe exterior
to the shell.

This group is divisible into sections as follows : — (a) Eusiphonia, with long siphons, and
the lithodesma, when present, at the anterior end of the internal resilium, and external to
the mass of the resilium ; and (&) Adelosiphonia, with short siphons, the lithodesma dividing
the mass of the resilium mesially.

Section A. Eusiphonia.

Family 1. Pleuromyacidae Zittel.

Shell slightly inequivalve, hinge with an ohscure protection or edentulouSj the cardinal
horder of one valve covering that of the other valve, ivhich is supplemented hy a sort of

laminar nymph, the ligament suh-internal hetween
them ; area inconstant or ohscure; pallial sinus
present ; ralves closed or slightly gaping. Trias to
Lower Cretaceous.

Pleuromya Ag. {Myacites auct.) (Figs. 735, 736).
Posterior side longer, somewliat gaping, hinge
margin with a thin horizontal lamina in eacli
valve, the left inferior, the margin wdtli a feeble
notcli behind the lamina ; ligament parivincular.
Trias to Lower Cretaceous ; almndant, but seldom
.well jjreserved.

Fkj. 735. Gresslya Ag. (Fig. 737). Like Pleuromija, but

Pleuromya peregrinaA'Ovh. Upper Jnra ; the right hinge margin proi'ectinff over the left,

Chorostköw, near Moscow. A, Internal , • ^^ ^ ^ • ^ ^• . • • -,

mouid, i/i- li, Hinge. anterior side snort, Wide ; ligament parivincular,

almost internal, attached to an internal nympli-
like callosity in the right valve, which appears as a groove on internal moulds.
Abundant in the Jura, especially in the Lias.

CLASS I

Geromya Ag. (Fig. 738).

A-. .Middle Juni, Zii
jaczki, Poland. i/i-

PELECYPODA

Cordalc, iiillal

Fki. 737.

Crrss/i/,,, htfirnsin,
Ai^-. Lowcr Oülite
Tainiie, öartlie. i/i-

465

], witli i'atlici' aiilcrior, |iI(i.-(il;\ rous
--; hiii^v iiiai\^iii u\ ilic ri^lit valve
ri(»r, (■(Iciiluious, Ijiil willi a blunt

Fir;. 738.

Ceromija cf. aalcnsls Queiist. Middle Jura ;

Kneuttingeu, Lonaine. Hinge, 1/2'

elongated process in front of an internal callosity. Chiefly occnrring as moulds. Jura.

Family 2. Pholadellidae Miller (eniend.).

Shells obovate, usually attenuated hehind and slightly gaping, hinge margin thin,
edentulous, ligament parivincular, external ; posterior adductor scar large. Paleozoic.

Allorisma King. E longa te, arcuate, tlie pallial line sinuated, anterior side
sliorter, sometimes witli a liinule ; sciüpture strengest mesially. Carboniferous and
Permian.

Ehytimya Ulricli, Elongate, sub-quadrate, concentrically waved, tbe waves
stronger anteriorly ; sculptnred on the posterior half witli
radiating series of grannies ; lunnle very narrow. Silurian.
Pholadella and Gimitaria Hall. Devonian ; North
America.

Family 3. Pholadomyacidae Gray.
Shell suhstance nacreous and cellulo - crystalline ; gills

Pliolniloiin/ii. vnnrh:.«!,,; S(
MiddltNJui-a; l'iezclinow, l-olai
Vi.

completely united, hehind, forming a septurii heloiv the anal chamher ; foot small, with an

opisthopodium ; siphons long, united to their tips, not wholly retradile, naked ; ventral

commissure of the mantle ivith a pedal and an opisthopodial foramen. Shell thin, equi-

VOL. I ' 2 H

466

MOLLUSCA

PHYLUM VI

valve, (japing, edentulous, or loith an ohscure subumbonal tuhercle ; ligament^ and
resilium external, opisthodetic, seated on nymphae ; area obsolete or obscure, not amphi-
detic ; beahs entire ; pallial sinus well marked ; marine. Trias to Recent.

Pholadomya Sow. (Figs. 739-741). Shell thin, sub-ovate, with. radial and coii-
centric sculpture, inflated, and with rather prominent beaks ; hinge edentulous, or
with an obscure thickening ; scars feeble, pallial sinus moderately deep. In the

Fia 742.

Goniomya duhoisi Ag. Inferior Oolite ; Bayeux,
Calvados. A, Shell, i/j. B, Surface showing puncta.
tions, magnified.

Hmnomya (Arcomya) calceiformis Ag. Inferior Oolite ;
Les Moutieux, near Bayeux, Calvados. 2/3.

posterior dorsal region the radial sculpture is usually feeble or absent. Lower Lias to
Recent ; formerly very abundant, but now represented by a single species from the
Antilles, P. Candida Ag., and another from Japan.

Procardia Meek. Includes those forms with an escutcheon. Jura.

Goniomya Ag. (Fig. 742). With V-shaped sculpture. Lias to Cretaceous ; very
plentiful in Middle and Upper Jura.

Homomya Ag. {Arcomya, Myopsis Ag. p.p.) (Fig. 743). Distinguished from the
typical Pholadomyas by its smooth or very finely sculptured shell, without ribs.
Trias to Cretaceous.

(?) Machomya, Plectomya Loriol ; Mactromya Ag. Jura and Cretaceous.

Family 4. Anatinidae Dal].

Soft parts like Pholadomya, the foot small and grooved, ventral foramina small, and
the siphons with a horny integument, not entirely retractile. Shell sub-equivalve, truncate,

or gaping behind, edentulous, the resilium internal between
two spoon-like chondrophores vertically directed and often
supported by buttresses ; ligament obsolete or absent ; area
obsolete; beahs transversely fissured ; pallial sinus well
marked ; monoecious ; marine. Jura to Recent.

Anatina Lam. {Platymya, Cercomya Ag. ; Plicomya
Stol.) (Fig. 744). Shell thin, nearly equivalve, con-
centrically but feebly sculptured, posterior side shorter
than the anterior. Jura to Recent. Laternula Bolten, is a prior name.
Periplomya and Anatimya Conrad ; Rhynchomya Agassiz. Cretaceous.

Fio. 744.

Anatina producta Zittel. Upper
Cretaceous ; Gosau Valley, Austria

Family 5. Periplomatidae Dali.

Shell sub-nacreous, conspicuqusly inequivalve, nearly closed, edentulous ; the resilium
internal, between two anteriorly or vertically directed chondrophores, often buttressed, the
lithodesma rarely ivanting ; ligament and area absent ; beaks fissured ; pallial sinus
broad and shallow ; siphons separated to their bases, naked and wholly retractile ; mono-
ecious; marine. Tertiary and Recent.

CLASS I PELECYPODA 467

Periploma Schiiin. Shell oval ov rounded, siiiootli or witli faiiit coucentric Striae ;
lithodesnia preseiit. Tertiaiy and Eecent.

Gochlodesma Couth. Buttress of the chondrophore posteriorly directed ; no litlio-
desiiia. Pliocene and Recent.

Bontaea Leach {Ligula p.p. Mont.) ; Tyleria Adams. Kecent,

Family 6. Thraciidae Dali.

Shell earthy and cellulo-crystalline, not nacreous ; inequivcdve, thin, edentulous, often
with a granulär surface ; licjament and resilium
chiefly external, opisthodeticj parivincular, seated
on posteriorly directed nymphae ; area absent,
heaJcs usually entire ; valves nearly closed, with
pallial sinus ; mantle openings small ; siphons
long, separated to their tips, nahed ; monoecious ;
marine. Jura to Recent.

Thracia Leach {Gorimya Ag.) (Fig. 745).
Shell smooth or concentrically striated, with
granulär surface, usually more or less rostrate.
Trias to Recent.

Gyathodonta Conr. Shell with oblique or ■^^^' '^'^^•

angular waves of sculpture, otherwise like the ^'"««^ ^«<^ß»-^ Ag.^^Upper Jum
preceding. Tertiary and Recent.

Bushia Dali ; Asthenothaerus Carpenter. Recent.

Family 7. Myochamidae Dali.

Shell very inequivalve, free or sessile, solid, suh-nacreous, edentulous, the dorsal
margins of one valve overlapping those of the other, which fit into corresponding depres-
sions in the shell wall; ligament amphidetic, external or ahsent ; resilium internal,
alivincular ; area amphidetic or obsolete, a false area formed on each side of the beaks by
the flattened cardinal margin of the valves ; shell closed ; pallial sinus small. Tertiary
and Recent.

The gills and siphons of Myochama Stutchbury, which lives sessile on shells, are
more like those of Thracia than of the Pandoridae, with which it lias usually been
associated. The anatomy of Myodora is unknown. Its minute area curiously recalls
that of Spondylus, and it is free.

Section B. Adelosiphonia.
Family 8. Pandoridae Gray.

Shell compressed, inequivalve, free, solid, with nacreous and prismatic layers ; the
dorsal edges of the valves overlapping^ but not socheted, with dentiform crural ridges on
either side of the resilium, but no true teeth ; ligament amphidetic, external, obsolete;
resilium internal, opisthodetic, usually reinforced on its anterior surface by a mesial
elongate lithodesma ; area none ; valves closed, beaks entire, pallial line simple ; marine.
Cretaceous to Recent.

Pandora Brug. Diverging crura without connecting lamellae ; buttress and
lithodesma absent. The subgenus Kennerleya has a lithodesma. Tertiary and Recent.

Goelodon Carp. Crura of the left valve united by a transverse lamella. Glidio-
phora Carp. has the hinge plate buttressed and a lithodesma. Tertiary and Recent.

468 MOLLUSCA phylum vi

Family 9. Lyonsiidae Dali.

Shell inequivalve, thin, sub-nacreous, edentulous ; ligament obsolete, the resilium
internal^ uniting the edges of a long, mesial lithodesma to a narrow chondrophoric sub-
marginal ridge on each valve ; beaks entire, valves nearly closed, pallial sinus distinct ;
marine. Tertiary and Kecent.

Lyonsia Turton. Small, thin, posteriorly elongate with delicate radiating sculp-
ture. Tertiary and Eecent.

Entodesma Pliilippi, Kecent. Actinomya Mayer. Eocene ; North America,

Family 10. Lyonsiellidae Dali.

Shell nearly equivalve, sub-nacfeous, with a more or less distinct tubercle in front of
the resilium on the dorsal margin ; ligament obsolete, cartilage internal with a, large
lithodesma ; area obscure or absent ; beaks entire ; valves almost closed ; pallial sinus
obsolete. Tertiary and Recent.

Halicardia Dali ; Lyonsiella Sars. Chiefly Recent.

Superfamily 2. ENSIPHONACEA DaU.

Differing from Anatinacea by the formation of a calcareous tube, which may include
one or both of the valves, and is usually furnished with a perforated anterior
disk surrounded by a more or less complete f ringe of small calcareous tubules.

Family 11. Clavagellidae d'Orbigny (emend.).

Shell degenerate, extremely specialised for a burrowing life; valves
nacreous, free when young ; when adult, one or both merged in a calcareous
tube anteriorly discoid and fringed, with a narroio pedal foramen in the
middle of the disk ; free valves edentulous, the ligament external, opisthodetic,
supported by nymphs ; pallial line sinuate ; tube frequently encrusted with
extraneous material ; marine. Cretaceous to Recent.

Glavagella Lam. (Bryopa Gray ; Stirpulina Hol.) (Fig. 746). One
of the valves not attached to the tube and adductor muscles persistent.
Cretaceous to Recent.

Brechites Guett. {Äspergillum Lam.). Both valves merged in the
tube, anterior adductor reduced, and the posterior obsolete. Pliocene
„ ^,. and Recent.

Fig. 746.
Glavagella

caüiati Desh. Superfaiüily 3. POROMYACEA DaU.

Eocene; Grig-

Desiiayes)* ^ Anomalodesmacea having modified foliobranch or lamellar gills, slightly

or not at all reticulated, and frequently degenerate or even absent; valves
free, without a calcareous tube external to them ; mantle lobes united, with siphons and
a pedal, but no opisthopodial foramen ; the cartilage reinforced below by a lithodesma.

Family 12. Euciroidae Dali.

Shell sub-equivalve, nacreous and cellulo-crystalline, externally granulöse; hinge
with a strong tubercle in the right valve before the resilium, and the dorsal margins
modified to overlie and underlie each other ; ligament obsolete; resilium opisthodetic,
internal, with a strong lithodesma ventrally ; area obscure or absent ; a depressed false

CLASS I

PELECYPODA

469

lumde hefore the hcaks ; valves closed, imllial sinus shalloiv, nhscure ; siphons short,
separate ; marine. Tertiary to Receiit.

Pecchiolia Menegli. Sliell heavy ; beaks spirogyrate, distant ; sciilptiire radial.
Eocene ; Alabama. Mioceiie ; Europe.
Euciroa Dali. Recent, abyssal.

The genera Verticordia Wood ; Trigonulina d'Orb. ; Haiiris Dali ; and (?) Allo-
pagus Stol. {Hippagus Desli., non Lea) are included linder the faniily Verticordiidae.
Tertiary and Recent.

Family 13. Poromyacidae Dali.

Shell rounded, nacreous and cellulo-crijstalline, granulär or smooth externally ; hinge
with^ obscure tuberdes in front of the resilium ; ligament external, opisthodetic ; resilium
sub-internal below the ligament, with a small lithodesma ; area obscure or absent ; a
depressed false lunule in front of the beaks; valves nearly or entirely closed; pallial
sinus small or obsolete ; marine. Cretaceous to Recent.

Liopistha Meek {Gymella, Psilomya Meek) (Fig. 747). Eqiiivalve, oval, thin, in-
flated, concentrically or
radially striated, gapiiig
and compressed behind ;
beaks prominent, in-
curved ; hinge with a
nymph and projecting
process on eacli side ;
ligament siinken, partly
external. Cretaceous.

(?) Basterotia Mayer
{Eucharis Recliiz, non
Peron). Valves sub-equal, closed, with a strong tooth in the right and two in the
left ; surface granulär ; form trapezoid. Miocene and Recent.

Poromija Forbes {Embla Loven). Ovate, plump, surface granulär ; pallial line
irregularly widened, not sinuate. Eocene and Recent.

Dermatomya Dali. Surface smooth, with a conspicuous periostracum ; pallial
line sinuate. Recent, abyssal.

Cetomya, Getoconcha Dali (ßilenia Smith). Recent, abyssal.

Fi(i, 747.
Liopistha frequens Zitt. Upper Cretaceous ; Gosau, Austria. Vi^

Family 14. Cuspidariidae Dali.

Shell sub-equivalve, rostrate, earthy or cellulo-crystalline, rarely with surface granula-
tions ; hinge edentulous or with sub-umbonal tubercula-
tion, sometimes buttressed ; ligament sub-internal, anterior
to the beaks or obsolete; resilium internal, with a mesial
or ventral lithodesma ; area amphidetic or obscure ; valves
closed except at the tip of the rostrum ; pallial line simple ;
siphons united ; marine. Jura to Recent.

Guspidaria Nardo {Neaera Gray ; Ryderia Wilton)
(Fig. 748). Shell concentrically sculptured ; hinge
with a small posteriorly inclined chondrophore in each

valve, and an elongated ridge behind it ; ligament always anterior to the bciks

when present. Jura to Recent.

Subgenera : Cardiomya Adams ; Avith radial sculpture and a posterior lateral tooth in
the right valve. Lciomya Adams ; smooth, with an anterior cardinal in each valve, and

Fi(i. 748.

Cusindaria cuspidata Olivi.
Miocene ; Baden, near Vienna.

470 ■ MOLLUSCA phylum vi

anterior and posterior laterals in the right valve only. Plectodon Carp. ; surface granulated.
Rhinoclama D. and S. ; like Plectodon, but without cardinal teeth. J'ropidomya D. and
S. ; hinge witli a buttress, one anterior cardinal, but no lateral in either valve. Halonymplia
D. and S. ; right valve with a single cardinal, no other teeth in either valve, a conspicuous
posterior laminar buttress in each valve. Luzonia Dali. Tertiary and Recent.

Myonera Dali and Smith. Shell thin with concentric waves and sparse radial
ribs ; hinge edentulous ; rostrum short, rounded. Recent, abyssal.

(?) Gorhurella Lycett. Middle Jura. Spheniopsis Sandberger. Tertiary.

Order 3. TELBODBSMACEA DaU.

A. Pantodonta.
Laterals exceeding tivo in any one group.

Family 1. Allodesmidae Dali {Gycloconchidae Ulrich).

Shell rounded; valves equal, free, closed, with feehle concentric sculpture ; area
linear, amphidetic ; ligament suh-external, parivincular, opisthodetic ; adductor scars
suh-equal, pedal scars ahove and distinct from the adductors ; pallial line entire ; hinge
with one or two lateral laminae on each side of the beaJc, the posterior helow the ligament,
received into corresponding grooves on the right valve; cardinal teeth radially grooved ;
one or two in each valve, those in the right valve stronger. Ordovician and Silurian.

This family, as suggested by Neumayr, probably exemplifies the first step in the develop-
naent of the Teleodesmacean hinge. But it must be adraitted that its amphidetic though
linear area, the occasional multiplication to three of the lateral laminae, and the sub-ligament-
ary localion of the hinder laminae, are very reminiscent of the prevalent Silurian Schizodont
type, and the family can be adraitted to the Teleodesmacea only as a probable ancestor, rather
than a perfectly developed type of the modern assemblage.

Orthodontiscus Meek {Cycloconcha Miller ; (?) Anodontopsis M'Coy). Ordovician
and Silurian.

Ällodesma Ulrich. Like Orthodontiscus, but more elongate, the beaks more
anterior, the anterior adductor scar buttressed by a radial ridge, and the anterior
lateral teeth short or absent. Ordovician

B. DiOGENODONTA.

Laterals normally one or two, and cardinals three or less, in any one group.

Superfamily 1. CYPEICARDIACEA Dali.

Lobes of the mantle partly closed ventrally ; anterior lateral laminae absent, or
grouped with the cardinal teeth, short and obscure.

Family 2. Pleurophoridae DalLi

Shell substance cellulo-cry stalline ; valves equal,free, closed ; adductor scars sub-equal,
free from the pedal scars ; pallial line entire, or feebly sinuated ; area obscure ; liga-
ment external or seated in a groove, parivincular ; margins of the valves usually piain ;
hinge with one left and two right posterior laminae, the anterior laminae absent or con-
fused with the cardinals ; two or three cardinal teeth in each valve, of which the posterior
in both valves is sub-parallel to the dorsal shell margin, and in the right valve is usually
bifid. Mantle with a moderate pedal and two siphonal openings, the latter usually not
produced into tubes. Devonian to Recent.

1 Cyprinidae p.p. of authors, but this name cannot be used.

CLARS I

PELECYP0DA

471

This family, so well known under the preoccupied nanie Cyprinidae, probably shared the
same origin as the Astartidae, and tlie two do not definitely separate until the Jura. The
Position of the Paleozoic ancestors is neeessarily doubtful, and they are placed ditferently
by different authors. The group i.s divided into two subfaniilies, Pleurophorinae and
Vetiiellinae.

.Pleurophorus King (Fig. 749). Elongated, siib-rectangular ; beaks sub-terminal ;
surface smootli or witli radial sculpture ; hinge with two cardinal teeth in each valve ;

Pleurophorns costatu!^ King. Per-
mian ; Byers Quarry, England. A,
Shell, Vi Gifter King), ß, Internal
mould Ironi Gera, Tlniringia (after
Geinitz).

Anisrimrdia elegans Mun.-Chalra. Kimmeridgian
Cap de la Heve, near Havre i/i>

anterior adductor scars deep, with a buttress-like ridge behind it. Devonian to
Trias ; especially abimdant in the Permian,

Cypricardella Hall {Microdon Hall); Mecynodon Keferst.; Gypricardinia Hall.
Devonian. Astartella Hall. Carboniferous.

Änisocardia Mun.-Chalni. (Fig. 750).

Rounded or trapezoid, plump, smooth or
radially striate ; posterior slope some-
tinies keeled ; hinge with a strong
sometinies bifid right cardinal behind,
and an anteriorly directed front cardinal;

Venilicardia cordiformis, d'Orb.
Gault ; Seignelay, Yonne.

Fi(i. 753.
Veniella tumida Nyst. Crag ; Antwerp.

left valve with a forwardly directed anterior and a posterior cardinal tooth. Jura to
Tertiary.

Boudairia Munier-Chalm. Like Trapeziim, but with a sharp keel and smooth
area behind, anteriorly with concentric ridges ; right posterior cardinal bifid. Upper

Cretaceous.

472 MOLLUSCA phylüm vi

Trapezium Huiniili. emend. Megerle {Lihitina Schiiin . ; Gypricardia Laiii.), Shell
elongate, traj^ezoidal, coiicentrically, or luore rarely radially sculptured, often with a
posterior keel ; three cardiiial teetli in each valve, tlie posterior in tlie right valve
often bifid. Jura to Eecent.

Plesiocyprina Munier-Chalm. Jura. Gicatrea Stol. Cretaceous. Goralliophaga
Blainv. Tertiary and Recent.

Ärctica Schum. (Gyclas Brug. ; Gyprina Lam.) (Fig. 751). Oval or rounded, in-
flated, concentrically striated ; beaks prominent, curved, cardinals three in each valve,
the left posterior often bifid, the middle left cardinal largest, and tlie posterior ridge-like.
Abundant in the Jura and Cretaceous, and represented by one or two living species.

Venilicardia Stol. (Fig. 752). Cretaceous. Pygocardia Mun.-Chalm. Tertiary.

Veniella Stol. {Venilia Morton; (?) Goniosowa Conr.) (Fig. 753). Left valve with
the anterior cardinal strong, sub-triangular. Cretaceous and Tertiary.

Superfamily 2. ASTARTACEA Dali.

Lohes of the mantle free ventrally ; lateral laminae ohscure, wlicn present distant
from the cardinals.

Family 3. Curtonotidae Dali.

Shell short and heavy, with suh-terminal heaJcs ; valves free, eqnal, closed ; area
ohscure ; ligament as in the Astartidae ; adductor scars, especially the anterior, deep ;
pallial line simple ; hinge plate hroad, vnthout lateral laminae ; the formula of the

cardinals ^ttt-i^j or uTttt- Devonian and Carboniferous.

This group is inserted conformably with the opinion of Neumayr, wlio regards it as the
radical of the Astartidae.

Gurtonotns Salter. Oval, cardinal border thick, with one very strong tooth in the
left, and a strong anterior and thin posterior tooth in the right valve. Scars of the
adductors strong, especially the anterior. Devonian ; England.

Prosocoelus Keferst. Devonian. Protoschizodus de Kon. Carboniferous.

Family 4. Astartidae d'Orbigny (emend.).

Shell suhstance cellulo-crystalline, with a pronounced epidermis ; shell rounded or

suh-triangular, usually with concentric or not radial sculpture ; valves equal or suh-eqnal,

free, closed ; area distinct ; ligament and. resilium external, parivincular, opisthodetic ;

heaks prosocoelous ; adductor scars sub-equal, with a distinct anterior pedal scar ; pallial

line simple; hinge plate distinct, hinge with anterior and posterior

lateral teeth and their respective sockets, usually more or less obsolete;

cardinal teeth not bifid at the summit, the terminal teeth frequently

obsolete. Lobes of the mantle free ventrally, not produced into siphons.

Pio. 754. Trias to Recent.,

Middle Jura; Gun'- Astarte Sow. (Grassina Lam.) (Fig. 754). Roundly triangulär or

dershofen, Aisace. oval, rather compressed, thick ; smooth or concentrically sculptured ;
l^mule impressed ; right anterior cardinal strong.

A nmnber of genera have been associated with Astarte which probably belong elsewhere.
The following subgenera, however, are Avorthy of recognition ; Coelastarte Böhm, Freconia
Stol. ; Crassinella Bayle, non Gnppy (Fig. 755); rroroMa Biilini. Jura. Eriphyla Gabb.
Cretaceous. Grotriania Speyer ; Goodallia Turton (Yhj,. 1()1) ; Uhcdocyvm Dali ; Diqitaria
Wood (Fig. 756). Tertiary and Recent.

SS I PELECYPODA 473

02ns Defr. (Fig. 758). Trigoiial, cordate, sinootli or coiMcutricnlly sliialc; beaks

Fig. 757.

Astarte (Goodallia)
milinris Defr. Eocene ;
Grignon, near Paris
(after Desliayes).

Fig. 755.

Astartc ohllqua Desh. Inferior
Ooiite ; Bayeux, Calvados.

Fig. 756.

Digitari profunda Desh.
(as Woodia). Eocene ; Aizy,
near Laon. A, Hinge, en-
larged. B, Shell.

2)ronii]ieiit, prosocoelous ; limule very deep, bordered by a keel ;
cardinal teetli long, iiarrow (2 : 1). Trias to Cretaceous.

Fig. 758.

Opis goldfussiana

Opisoma Stol. Jura. Seehachia Neiiniayr. Cretaceous. theim*. Würtemberg.^

Family 5. Crassatellitidae Dali.

Shell as in thr, Ädartidae, hut the valves always somewhat unequal, and nsualhj
Diore or less radrufi', fhe heaks compressed, erect or opisthocoelous ; liyanient infernal,

CrassatelUtcs plumlmi (Chem.).

Fig. 750.
Eocene (Calcaire Grossier) ; Damery, near Epernay. 2/3.

more or less obsolete, resilium large, wholly internal, attached at each end to a chondro-
phoric pit in the hinge plate behind the cardinal teeth ; lateral teeth and sockets usually
alternated in the valves, the hinge plate heavy, flat ; the posterior cardinal in the right
valve very small or obsolete, lüith no distinct socket in the opposite valve ; füll cardinal

formula

L 1010
RIOIUI'

Lower Cretaceous to Kecent.

Tlie earlicr foriiis of tliis fiiniily liave a sniall resilium close to the nearly ni.iVL^iiial ülj.-i-
ment. Witli iimc. Liter oin's show ;i gradual descent of tliese organs, until in sninc of \\\v
niorc spoeialiscd iiioilcni n|ii('sriitati\-es tliere is no approciable liganient rciiiainiiiLr. and tlie

474

MOLLUSCA

PHYLUM TI

resilium has become large and deeply immersed. The parallelism between this group and
the Mactridae, in the gradual inimersion of the ligament, could hardly be
niore complete.

Grassatellites Kruger {Grassatella Lam. 1819, non Lam. 1799)
(Figs. 759, 760). Cretaceous to Kecent ; represeiited by about seventy
fossil and forty living species.

Triodonta Koenen. Oligocene. Scamhula Conrad ; Bemondia
Gabb {Stearnsia White) ; Änthonyia Gabb ; Grassatellina Meek.
Cretaceous.

(?) Ptychomya Ag. Like Grassatellites, but witli radial sculpture
and three cardinals in each valve. Cretaceous.

Grassinella Guppy, non Bayle {Gouldia auct., non Adams ;

Fk

Grassatellites
hronni Merian.

Oligocene; Wein- Pseuderiphyla Fisch.). Small, sub -triangulär, very compressed, con-
Vi. centrically ribbed. Tertiary and Kecent.

Superfamily 3. CYRENACEA Tryon.

Gypricardians which have become specialised for fresh or brackish water conditions,
and, as usual in such cases, have developed great variability of character ; usually vivi-
parous.

Family 6. Oyrenidae Gray.

Shell porcellanous, with a conspicuous epidermis, usually with concentric sculpture ;
valves equal, free, closed, usually with piain margins ; area obscure or none ; ligament
and resilium external, parivincular, opisthodetic ; adductor scars sub -equal, separate
from the pedal ; pallial line simple or ivith a small sinus ; hinge with anterior and
posterior laterals usually double in the right, single in the left valve, distinctly separated
from the cardinals ; cardinal teeth bifid. at the summit, three in each valve when none
are obsolete. Mantle open ventrally, the siphons distinctly developed, short, more or less
united. Lias to Recent.

Many of these forms merge with one another as'we recede in time. The Recent American
forms and many fossils show a pallial sinus ; oriental species are generali y without it. In
some fossils the laterals oF the right valve are not double,

Gyrena Lam. Rounded, sub-equilateral, plump, concentrically sculptured, with
smooth margins ; cardinals three, the laterals smooth. Lias to Recent (300 species) ;
maximum in the Cre-
taceous and onwards.

Subgenera : Corbicula
Megerle (Figs. 761, 762).
Smaller than Gyrena, and
the laterals sharply cross-
striated. Egeta Adams.
Compressed, elongated,

thin ; almost rostrate.
Recent : marine.

Fig. 761

CorMcula fluminalis
(Müll.). Pleistocene ;
Like Teutschenthal, near
. Halle, Saxony.

right

Fir.. 762.

Corbicula semistriata Desli. Oligocene
(Gyrena marls) ; Flonheim, near Alzey. i/^.

Batissa Gray.
Gyrena, but the

anterior and left posterior cardinals feeble or obsolete ; anterior laterals very short,
posterior ones elongated. Upper Cretaceous of Oregon, and living in Indo-Pacific
region. <

^ Veloritina, Leptesthes Meek. Laramie Group. Villorita Gray {Velorita Gray, 1 847).
Oligocene to Recent. The relations of the Recent Egeria Roissy, and Profischeria Dali
{Galatea Brug., non Fabr. ; Fischeria Bernardi, non Desv.) are not positively fixed.

CLASS I

PELECYPODA

475

Family 7. Sphaeriidae Dali,

Shell as in the Gyrenidae, but small, with a feehle, short ligament, a simple pallial
line, and no hinge plate ; cardinal teeth usiially two in each valve, variable, very thin,
often nearly parallel to the hinge margin or defective in pari of the series ; laterals as in
the Gyrenidae, distinct. Upper Cretaceous to Recent,

Sphaerium Scop, {Gyclas Lam., non Bnig,). Brancliial siphon complete ; shell
equilateral, inflated, rounded. Upper Cretaceous to Recent.

Subgenus Eupera Bgt. Shell compressed, trapezoid. Tertiary and Recent ; sub-tropical.

Gorneocydas Ferussac {Pisidium Pfeitf.). i Shell ineqiiilateral ; branchial siphon
merged with the pedal opening. Eocene to Recent.

Superfamily 4. CARDITACEA Menke.

This group appears to have branched off from the Ästartoid radical in the early
Mesozoic, forming in one sense a sort of parallel series with the Ästartidae, with ivhich it
is contrasted most obviously by its prevailing radial sculpture and prolonged posterior
cardinal tooth.

Family 8. Oarditidae Gill.

Shell as in the Ästartidae, but usually with radial sculpture, the pedal adjacent to
the anterior adductor scar ; ligament external, parivincular ; re'silium usually included
in the ligament, rarely internal; hinge fully developed, with the laminae as in the
Ästartidae, and usually obsolete; the anterior cardinal often obsolete, the posterior pro-
longed parallel with the dorsal margin even below the ligament. Füll cardinal formula

p • Marine; dioecious, frequently viviparous. Trias to Recent.

The earlier forms approaeh the Ästartidae and Pleurophoridae so closely that they can
hardly be discriminated.

Gardita Brng. Elongate, quadrate, with prominent, very anterior beaks ; sculp-

m

Fio. 7G3.

Palacocardita crenata
(Münst.), Upper
Trias ; St. Cassian,
Tyrol.

Fi(i. 764.
Venericanlia imbricata Lam. Eocene ; Grignon, near Paris.

tiire radial and usually imbricated, commonly with a lunule ; inner margins dentate ;
cardinals long and oblique. Trias to Recent.

Palacocardita Conr. (Fig. 763). Like Gardita, but with a posterior lateral
tooth. Trias and Cretaceous.

Venericardia Lam. (Fig. 764). Rounded or cordate ; lateral teeth absent or
obsolete. Cretaceous to Recent.

476

MOLLUSCA

PHYLUM VI

Garditamera Conr. Elongated, sub-mytiliform. Pleuromeris Conrad. Small,
eqiiilateral, trigonal. Cahjidogena Dali. Ovoid, smootli extenially. Garditella
Sinitli. Siuall, witli internal ligament. All Tertiary and Kecent. Thecalia Adams ;
Milneria Dali. Females with a slielly marsupium. Eecent.

Superfamily 5. CHAMACEA Geinitz.

Garditian forms specialised for a sessile habit, usually with exceptionally spiral
growth, and very unegual valves. Marine.

Family 9. Diceratidae Dall.^

Resemhling Ghama, but with the adductors usually borne on myophoric laminae, or
projections which o.re prolonged into the umbonal cavity below the hinge plate ; valves
grotesquely distorted, sub-equal, with prolonged and twisted umbones, or the free valve is
reduced to an opercular form, spiral, and even concave ; the teeth often reversed relatively
to their Situation in Ghama. Jura and Cretaceous.

This family lias possibly been derived from the Megalodontidae of the Paleozoic and early
Mesozoic, and in .tuvii has given rise to a branch that has siu'vived to the present day

Fig. 765.

Diceras arietinum Lam. Coral-Rag ;
St. Mihiel, Meuse. 2u

Fio. 766.

A, Diceras arietmum Lam. Coral-Rag; St. Mihiel, Meuse.
Fixed left valve, 2/3. B, D. zitteli, Mun. - Chalm. Tithonian ;
Stramberg. Right valve, 2/3. a, a', Anterior and posterior
adductor sears ; c, Major cardinal ; d, Socket for left anterior
Cardinal ; l, Ligamentary groove ; s, Buttress ridge before
posterior adductor scar.

(Chamidae), as well as to others that became extinct at the close of the Mesozoic. In all cases
the forms in which the umbo of the free valve is coiled have preceded more specialised forms

^ For the Ghamacea and Rudistae, Neumayr proposed the term Pachydonta. For special litera-
ture see: Zittel, K. A. von,J)\Q Bivalven der Gosaugebilde. Denkschr. Akad. Wiss. Wien,
1864, vol. xxiv.—Gemmellaro, O. G., Caprinellidi della Ciaca dei dintorni di Palermo, 1865.—
Munier- Ohalmas, K, Prodrome d'une Classification des Rudistes. Journ. deConchyl., 1873, vol. xxi.
— White, O. A., Bull. U.S. Geol. Surv., No. 4, 1884 ; No. 22, 1885. —Bouville, IL. Several papers in
Bull. Soc. Geol. France [3], xiv. p.. 389 ; xv. p. 756 ; xvi. p. 699 ; xvii. p. 627 ; xviii. p. 324 ;
1886-90. — di Stefano, G., Studii stratigrafici e paleontologici sul systema cretaceo di Sicilia.
T. Gli Strati con Caprotina. Palermo, 1888. II. Calcari con Polyconites di Termini-Imerese.
Palaeont. Ital., 1898, vol. iv. — Futterer, K., Die Oberen Kreidebildungen der Umgebung des Lago
di Santa Croce. Palaeont. Abb., 1892, n.s. vol. ii.—Böhvi, G., Beiträge zur Kenntnis der Kreide in
den Sitdalpen. Palaeontogr., 1894, vol. x\i.—Douville, H., Etudes sur les Rudistes. Mem. Soc.
Geol. France. Paleontologie, i. iii., 1890-96.— /^arowa, G. F., Sopra alcune Rudiste Senoniane
deir Appenino meridionale. Mem. Accad. Torino, 1900, ser. 2, vol. I.—Paquier, F., Les Rudistes
urgoniens. Mem. Soc. Geol. France, Paleont., 1903, vol. xi.—Toucas, B., fetudes sur la Classifica-
tion et l'evohition des Hippurites. tom. cit., 1903, and vol. xxi. p. 506, 1891.

CLASS I PELECYPODA 477

with an oiierculiforni free valve. The higlily modified Hippuritidae evidently indicate the
last stage of the evolutioiiary series.

Diceras Lam. {Heterodiceras, Plesiodiceras Mun.-Chalm. ; Pseudodiceras Gemm.)
(Figs. 765, 766). Shell smooth, inequivalve, with botli valves convex, the attached
valve larger, dentition normal or inverse ; beaks prominent, j^rosocoelous ; ligament as
in Chama, supported on nympliae ; right valve with a small anterior and large
elongated curved posterior tootli almost parallel with the hinge margin ; left valve

A, Rcquicnia ammonia (Goldf.). Urgonian ; Orgon, Bouches-du-Rli6ne. 1/3. B, C, Small individual of
R. {Toueasia) lonsdalei (Sow.), from same locality. B, Left ; C, Right valve, Vi-

with a Single, large, ear-shaped tooth in front of the elongated socket for the principal
tooth of the right valve ; posterior adductor scar on a projecting buttress. Upper Jura.

Apricardia Gueranger. Cenomanian and Turonian. A. carinata Guer.

Requienia Matheron (Fig. 767, A). Smooth, very inequivalve, attached by the
spirally twisted beak of the left valve ; right valve opercular, spiral, flat ; teeth
feeble ; posterior adductor scar buttressed. Lower Cretaceous, especially the Urgonian
of Southern Europe, the Alps and Texas.

Subgenus Toueasia Mun.-Chalm. (Fig. 767, B, C). Differs from Rcquicnia in having
both valves keeled. Urgonian and Cenomanian.

Matheronia Mun.-Chalm. Urgonian and Cenomanian. M. vircjinae (Gras.).

Family 10. Ohamidae Lamarck.

Bhell suhstance threefold, the inner layers porcellanoiis and tubulär, the middle
obscurely prismatic, the external cellulo-crystalline with reticulated tuhules and an incon-
spicuous epidermis ; valves unequal, irregulär, one of them sessile ; closed, usually
rounded in form with conspicuous sculpture, often differing in the opposite valves ;
adductor scars suh-equal, elongate, pedal scars minute, distant ; ligament and resilium
external in a deep groove, parivincular, opisthodetic ; area distinct, prosodetic ; beaks
more or less spiral, prosogyrous ; pallial line simple ; hinge plate heavy, arcuate ; hinge
frequently with a minute or obsolete posterior lamina, chießy in the fixed valve;
cardinals one or two in the free valve, two with an intermediate socket in the ßxed valve ;
the anterior cardinal broad, usually deeply grooved or multißd, the posterior simple, long
and curved parallel with the dorsal border ; siphonal orifices not produced into tubes ;
adductors each composed of tivo Clements. Cretaceous to Receiit.

Either of the valves of Chama may be the attached one, but the teeth in the fixed valve,
whether right or left, are ahvays the same, and similarly with the free valve. The fixation
is generally by the left valve.

Chama lAnw. (Fig. 768). Nepionic shell rounded. Ligament sometimes continued
to the point of the beaks, as in otlier bivalves with g}^rate umbones ; form rounded,

478

MOLLUSCA

PHYLUM VI

attached valve deeper and larger, tlie free valve flatter ; margiiis usually cross-striated,
surface lamellar or spinöse ; adductor scars large, not elevated. Cretaceous to Recent;
maximum in Eocene.

Fig. 768.
Chama squamosä Lam. Eocene ; Hampshire, i/j.

Echinochama Fiscli. Nepionic shell elongated, liaving the form, liinge and otlier
cliaracters of Gardita ; attaclied when adolescent, free in the yoiing and adult stages.
Valves sub-equal and similar; surface vermiculate, spinöse, witli radial ribs. Oligocene
and Recent.

Family II. Monopleuridae Fischer.

Shell suhstance loiihout canals ; shell sessile, closed, very inequivalve ; free valve ivith
the cardinal formula 101, operculiform or slightly spiral ; fixed valve with the formula
010, conical, unrolled or spiral; area wanting ; ligament external, parivincular,
opisthodetic. Cretaceous.

Monopleura Math. (? Dipilidia Math.) (Figs, 769, 770). Very inequivalve, smooth
or ribbed ; dentition always inverse ; attached by the right valve, v^^hich may be either

Fig. 769.

Fig. 770.

Monopleura trüobita d"Orb. Neocomian (Schrattenkalk); Orgon, Monopleura varians Math. Ur-

Bouches-du-ßhone. i/i. A, B, Anterior and posterior views. C, Interior gonian ; Orgon, Bouches-du-Rhone.
attached valve. Interior of both valves. i/^.

twisted or coniform ; left valve conical or flat ; ligament as in Chama ; posterior
adductor scar buttressed. Lower Cretaceous ; Southern Europe and Texas.

Valletia Mun.-Chalm. Neocomian. Gyropleura Douville. Cenomanian to
Senonian. Bayleia Miin.-Chalm. Turonian. B. pouechi Mun.-Chalm.

Family 12. Caprinidae d'Orbigny.

Shell suhstance internally furnished with large parallel canals, the external layer
valves heavy, irregulär, unequal, closed ; free valve spiral, cardinal formula

PELECYPODA

479

101, with a iiosterior myophoric crest for the adductor ; fixed valve conical or spiralj
Cardinal formula 010; ligament in a dcej) groove, almost internal, parivincular,
opisthodetic. Cretaceous.

Gaprina d'Orb. {Gemmellaria Mun.-Chalm. ; Gornucaprina Fiitt.) (Figs. 771, 772).

Fio. 771.

Longitudinal section of
the lixed valve of Caprina
adversa, shovving cavities in
the inner .shell layer.

Fig. 772.

Cross-section
of the free valve
of Capritui mm-
inunis Gemmeh,
showing parallel
canals in the
middle layer.

Fig. 773.

Flagioptychus aguüloni d'Orb. Upper Cretaceous ;
Gosau, Austria. s/^j.

Very inequivalve, attaclied by tlie apex of the coniform right valve. Left valve large,
spirally twisted ; inner layer of lower valve made up of concentric lamellae between
wliich cavities are sometimes left. The middle layer of the free valve traversed by
numerous simple, wide, parallel canals, extending from the margin to the apex; tooth
of the attached valve well developed, a series of depressions between the posterior
adductor scar and the margin. Cenomanian. The typical species, G. adversa d'Orb.,
is of large size.

Schiosia Böhm. Like Gaprina, but the fixed valve somewhat gyrate and the
canal syatem present in both valves. Cenomanian ; Upper Italy.

Flagioptychus Math. {Sphaerocaprina Gemm. ; Orthoptychus Futt.) (Figs. 773,

A B

Flagioptychus aguüloni (d'Orb.) (P. paradoxus Math.). Upper Cretaceous (Hippurltes Liniestone); Le
Beausset, Var, France. A, Right. B, Left valve of the same individual, seen from within, 2/3. «, Anterior;
a' Posterior adductor scar ; l, Ligamentary groove ; c, Anterior tooth ; c'. Posterior tooth of left valve ;
d! Socket ; s, Buttress. . C, Section of the small valve near the margin, showing canals (y) of tlie middle layer.
Magnified.

774). Right valve conical or twisted, attached ; left valve convex, with inciirved

480

MOLLUSCA

PHYLUM VI

beak ; ligament as in Ghama. Shell structiire like Gaprina, biit tlie free valve with
canals in the luiddle layer ; tlie walls of the canals bifurcate outwarcl, forming in
section a fringe of periplieral minor cliannels (Fig. 774, (7). Cenomanian and Turonian ;
Europe.

Caprinula d'Orb. (Chaperia Mun.-Chalni.) (Figs. 775, 776). Right valve elongated,

A attaclied, conical or incurved ;

left snialler, gyrate ; botli with
caiial System, the periplieral
canals smaller ; hinge as in
Gaprina. Cenomanian and
Turonian, especially in Portu-
gal, Sicily and Texas.

Ichthyosarcolithus Des-
marest {Gaprinella d'Orb.).

Fig. '775.

Caprinula haylei Geinm.
Upper Cretaceous ; Ad-
dauran, near Palermo. 1/2
(after Gemmellaro).

Fig. 776.

Caprinula boissyi d'Orb. Cross-
section of the lower(^)and upper
{B) valves. c, Teeth ; s, Septum ;
u, Body cavity; x, Sockets. 2/3
(after Wood ward).

Fig. 777.

Mass consisting of Caprotina
semistriata and C. striata
d'Orb., and a smooth Spliaeru-
litcs. Greensand ; Le Mans,
Sarthe (after d'Orbigny).

Cretaceous. Gaprotina d'Orb. (Fig. 777). Canals obsolete, replaced in some species
by cavities. Neocomian to Turonian.

Goralliochama White. Right valve conical, elongated, attaclied ; left smaller, with
incurved beak ; anterior cardinal tooth buttressed, strong ; posterior cardinal weak ;
canals as in Plagioptychus, bounded within by a coarsely cellular layer ; lower valve
with a prismatic outer and laminar inner layer, separated by an intermediate cellular
Stratum. Cretaceous ; California.

Superfamily 6. RUDISTACAE (Rudistae, Lamarck).

Ghamacea in which the spirality of the valves has been lost, the area and ligament
vertically suhmerged, and the dorsal margins recurved over them so as to bring the ligament
into a sub-central position above the teeth but far beloio the dorsal margin, where itfinally
becomes obsolete. The teeth, no longer forming a hinge but rather a clithrum, specially
modißedfor the vertical motion of the operculiform, left valve, in which rotation isprevented
by the protection of the modißed teeth into deey sockets in thefixed valve ; the latter conical,
thich ; pallial line simple, enclosing the whole cavity ; shell structure specialised in two
very different layers ; sessile, marine.

The prisms of the outer shell layer are parallel to the long axis of the valve, and are out
at right angles by numerous tahulae, which, together with the upper margin, often hear
impressions of radial vessels. The laminae of which the inner layer is composed are often
separated by cavities which recall the septa of Cyathophylloid Corals, or those cavities found
in some oyster shell s. In Hippurites the outer layer is traversed by a complex of canals.
The Rudistacae are the most peculiarly modified of all Pelecypods. Their relationship to
the Chaniidae through Monopleura and Caprotina was first recognised by C^uenstedt, and
afterwards confirmed by Wood ward, Bayle, Zittel, Munier-Chalmas, Douville and others.

CLASiS I

PELECYPODA

481

Formeily the groiip was referred to tlie most diverse connections, such as Biachiomds, Corals
Cirripedes, etc., or placed in a special class by itself. '

The luajority of Rudislids occur gregariously in hirge nuuibers, sometinies filling entire
beds ; they are often found m their natural position, standing vertically on the apex of the
attached valve. Notwithstanding their abundance, it is extremely difficult and often irapos-
sible to separate the two valves and expose the interior, hence the hinge of many species is
still only inij>erfectly known.

Family 13. Radiolitidae Gray (emend.).

Shell sabstance wüh the external layer thick, prismatic ; the internal thin, cellulo-
crystalline (frequently destroyed in fossilisation) ; valves very unequal, the ligamentary
sitbsidence usually marhed ; free valves wüh two projections and two somewhat irregulär
myophores ; fixed valve with one myophore and two sockets ; summit of the valves suh-
marginal in the young, subcentral in the adult. Cretaceous.

a, h, RadioUtcs {IHradiolites) cornu-pasturis d'Orb. Middle Cre-
taceous (Oarentonian) ; Pyles, near Perigeux. a, Shell with closed
valves. B, C, The two more tinely ribbed vertical bands. h, Interior
of larger valve, viewed from above. a, a', Adductor scars ; m, Pallial
line ; n, Space occupied by soft jmrts ; x, Empty space botween the
sockets. 1/2 (after Bayle). c, Opercular valve of Ä. bournoni (\)esn\.).
Upper Cretaceous (Dordonian) ; St. Mametz, Dordogne. a, Anterior ;
a', Posterior myophore ; c, c', Anterior and posterior processes of
clithrum. 1/3 (after Bayle).

Fi(i. 779.

Ujtper
Shell

Spliaerulites angeiodes Lam
Cretaceous ; Gosau, Austria.
with closed valves, Vi- ^. Opercular
valve, 1/1. A, Sinus of hinge; a, a',
Myophores ; c, c', Processes of clithnim.

Radiolites (Lani.) Bayle (Biradiolites d'Orb.) (Fig. 778). Lower valve conical,
erect, elongated, vertically ribbed, or made iip of siiccessive layers ; usually with two
somewliat smooth bands exteiiding from the apex to the upper margin, which are
supposed by Douville to indicate the position of siphonal orifices ; outer layer very
thick, composed of large polygonal cells or liollow prisms (Fig. 780). Upper valve
operculate, flat or conical, with central or eccentric umbo. The clithrum is formed by
two vertically projectiiig striated processes (Fig. 778, c, c) fitting into sockets near
the outer wall of the fixed valve; next to and outside of the sockets are two large,

VOL. I

2 I

482

MOLLUSCA

PHYLUM VI

uneqiial, slightly excavated adductor scars, corresi^oiiding to two broad myophores in

the Upper valve. Middle and Upper Cretace-
ous ; Europe and Texas.

Subgenera : Lapeirousia Bayle. The smootli
bands correspond internally to tAvo prominent
tubercles. Synodontües Pirona. Has the two
teeth of the upper valve fused.

Sphaerulites Delam. {RadioUtes, Birostrites
Lam. ; Jodamia Defr. ; Dipilidia. ? Agria
Math.) (Figs. 779-
781). Externally
like Radiolites, but
without the two
bands; valves with
a re-entrant sinus
between the teeth,
which. fit into sepa-
rate pits {dj d'),
usually joined by a
ridge with the

Fio. 781.

Fig. 780.

Sphaerulites foliaceus Lam. Carentonian ; Ile
d'Aix, Charente. A, Sinus of the hinge, a, a',
Portion of the outer shell layer Anterior and posterior adductor scars ; d, d',
Anterior and posterior grooved sockets for tlie
processes of the upper valve ; x, x', Empty spaces
of the ligament pits ; y, Cavity at the inner end
of the Sinus. 2/3 (after Goldfuss).

of the lower valve of a Sphaeru

Utes or Radiolites showing the
hin^Pr marfrin of ^^^8® hollow prisnis. Cretace-
mner margin 01 ^^^ . jj^^^.^ Gargano, itaiy. Vi-

the sinus ; the two

depressions (Fig. 781, x, x) next the sinus were shown by Pethö to have been the
seat of a ligamentary connection between the valves ; the adductor scars {a, a) resemble
those of Radiolites. Widely distributed in the Middle and Upper Cretaceous.

The supposed genera Diinlidia, Birostrites and Jodamia are based on internal
moLilds of Radiolites. The visible submersion of the ligament in some Radiolites
enables us to understand how the stages shown by Hippurites have arisen.

Family 14. Hippuritidae Gray.

Shell suhstance of two layers, the external porous, grooved and punctate ; the inner
lacunary and prismatic ; exterior with sutures corresponding to an " anal " and
'' hranchial " inßection, and sometimes with a ligamentary suture ; clithrum formed of
two processes in the free valve, the adductors attached to myophores ; fixed valve with one
thin laminar process ; the adductor scars excavated, the anterior adductor duplex, forming
distinct scars. Cretaceous.

Hippurites Lam. (Figs. 782-786). Lower valve cylindro-conic, sometimes a metre
in length, attached by the apex, smooth or longitudinally ribbed, wdth three furrows
bounding two " columns," or columnar areas, extending from the apex to the upper
margin {A, B, C). Upper valve depressed, conic, with siib-central umbo, usually with
two round or oval foramina ; outer surface showing pores, the apertures of short canals
which join larger canals radiating from the beak. The thick outer layer of the lower
valve is usually brown-coloured and made up of thin horizontal strata, which are in
turn composed of small vertical prisms. The white inner layer is porcellanous, and
sometimes contains vacant spaces in the lower part of the shell. Three prominent
folds are present, on the inner side of the shell, formed by the inbending of both
layers of shell, and corresponding to the external grooves {A, B, G). Of these the
anterior {A) is longer and thinner than the others, which are thickened at the internal
end and carry a small tubercle above. In the two subgenera, Orhignyia Woodward
{H. biloculus Lam.), and Batolites Montfort (H. organisans Laj).), the anterior sinus
disappears entirely. In Pironaea Menegh., a number of accessory folds appear behind
the two columns. According to Douville, the two posterior columns are homologous

CLASS I

PELECYPODA

483

with tlie smooth band« of Radiolites, and indieate the position of the siphons.
Woodward supposes that tlie pit (x) contaiiied the internal ligarnent ; but so far,

'ö\nilUi:||

Hippurites gosaviensis
Douv. Upper Cretace-
ous ; Gosau Valley,
Austria. 1/2-

Fio. 783.

Hipjmrites oppeli Douville. Nefgraben, near Russ-
bach, Salzburg. A, B, C, Iinpressed lines bounding
convex vertical areas (columns) corresponding to the
region of the hinge. 1/2.

Fig. 784.

Hippurites organisans
Montf. Vertical section
of a valve below the
living Chamber, show-
ing the septa and inter-
septal cavities of the

middle layer.

Vi.

remains of the ligainent have only been found in the bottom of the outer anterior
sulciis, where it seemed to form a vertical band. The second adductor scar is small,
and located between the sulciis and the anterior column (B). The clithruni of the

Hippurites radiosus Desm. Upper Cretaceous (Dordonian) ; Royan, Charente. a, Upper valve (^1, Sinus of
the hinge • B C Grooves corresponding to anterior and posterior coluinns of the lower valve ; c, Anterior, and
c' c" Posterior processes of the clithrum). h, Interior of lower valve seen from above (^1, Sinus ; B, C, Posi-
tion of anterior and posterior columns ; a, a', Adductor scars ; d, Socket of anterior, and d', d", of posterior
processes of clithrum ; u, Body Chamber of shell ; x, Vacant cavity near the sinus). 2/3 (after Bayle).

Upper valve is extremely difficult to prepare, and is known in only a few species.
The anterior process shows near its base two tubercles (a, «')> wliich correspond to

484

MOLLUSCA

PHYLUM VI

the divided addiictor scar

of the lower valve. Behind tlie anterior tliere are two
supplemental processes, wliich are received into the
sockets d' and d" of the lower valve. The species are
abimdant in the Middle and Upper Cretaceous, and occur
chiefly in littoral shallow water deposits. The most
noted localities are the Alps and Pyrenees, Provence,
Charente, Istria, Dalmatia, Greece, Sicily, Asia Minor,
Persia and Algiers.

Barrettia Woodvvard. Cretaceous ; Jamaica and
Guatemala.

Superfamily 7. LUCINACEA Anton (emend.).
„ , ,„ Shell tvith the anterior adductor scar narrower, pro-

Htppurites cornu-vacctnum Goldi. . 7 7 77 • 7

UpperCretaceons;Gosau,Austria. duced ventrally ; posterior scar shorter, rounded ; palhai
vaTv£'ko:fngVJ"ÄcW,?g l^ne simple; foot elongate, suh-clavate ; hinge feehle, teeth

clithruni and relation of the sliell- radial, often obsolete.
layers. 1/2

Family 15. Tancrediidae Fischer.

Shell donaciform, equivalve, ivith an external ligament ; the margin of the valves
entire ; hinge with posterior
and anterior laterals, the latter
inconstant ; cardinals one in
the left and two in the right
valve, or two in each valve.
Trias to Cretaceous, (?) Eecent.

Tancredia Lycett {Het-
tangia Terq.; Palaeomya Zitt.
and Goub.) (Figs. 787, 788).
Shell sub-arcuate, attenuated
before the beaks, wider and
shorter behind them ; obli-
quely truncate and somewhat
gaping posteriorly ; a cardinal tooth on each side, and also an elongated posterior
lateral. Trias to Cretaceous ; niaximum in Lias.

(?) Meekia Gabb. Cretaceous ; California. (?) Hemidonax Mörch {Donacicardium
Vest), Recent.

Family 16. Unicardiidae Fischer.

Shell cordiform, equivalve, closed, concentrically striated ; adductor scars elliptical,
the anterior longer; pallial line simple; margin of the
valve smooth ; ligament external, parivincular, seated in a
groove ; with a grooved hinge-plate bearing a single obsolete
cardinal in each valve, or none. Carbon iferous to Cre-
taceous.

Fig. 787.

TaTwredia securifonnis (Dunker). Lower Lias ;
Hettingen, Lorraine, i/i (after Terqnern).

Fio. 788.

Tancredia (Falaeo-
viya) corallina 'Zitt.
and Goub. Coral-
Rag ; Glos, Calvados.

Rounded, inflated.

Fki. 789.
Unicardium cxcentricum d'Orb.
Kimmeridgian ; Cap de la Heve,
near Havre. i/i.

Unicardium d'Orb. (Fig. 789).
with incurved beaks ; hinge margin thin, with a weak
cardinal tooth ; ligament deep seated. Trias to Cretaceous.

Sealdia Ryckholt. Carboniferous.

Pseudedmondia Fischer. Ligament comjjletely external.
Carboniferous.

CLASS

PELECYPODA

485

Family 17. Lucinidae Fleming.

SheU substance porcellanous or chalky, usually with inconspicuous or dehiscent
epidermisy rounded, variably sculptured ; valves equal^free, closedy with low, prosocoelous

Fig. 790.
Lucina ( Miltha) gigantea üesh. Eocene (Calcaire Grossier) ; Grignon, near Paris. 2/3.

heahs ; adductor and pedal scars adjacent or distinct, the lauer small ; anterior adductor
elongated, largehj within the pallial line, which is not sinuate ; area within the pallial
line often granulär or punctate ; cardinal area small, often deeply impressed ; ligament
and resilium suh-internal, set in a deep groove, but usually more or less visible externally ;
hinge-plate distinct ; lateral laminae distant from the cardinals, anterior and posterior
in the right, vjith corresponding sockets in the left valve ; cardinal teeth radial, formula
LlOlO
ROlOl'

the posterior tooth larger and often bifid, but any or all of the teeth may be obsolete

or absent. Silurian to Eecent.

Paracyclas Hall. Eounded, thin-shelled, concentrically striated ; no luniile ; hinge
miknown. Devonian.

Lucina Briig. (Figs. 790-793). Koimded, convex or lenticular, usually with a

Fia. 791.

Lucina {Myrteä) columbella Lani. Miocene ;
Steinabrunn, near Vienna.

Lucina (Proltunna) prisca His. Silurian ; Gotlanil.
Internal nioiild (after Roemer).

lunule ; with delicate, concentric, or more rarely radial sculpture ; dentition usually
normal, the laterals developed. Represented by upwai-ds of 300 fossil and 100 recent
species. (?) Silurian, Trias to Kecent.

486

MOLLUSCA

PHYLUM VI

Subgenera : Lucina s.s. Lam. 1799 {Loripes auct.)- Shell smootli. Adult with the teetli

and posterior radial plication of the valves obsolete.
Tertiary and Receut.

Prolucina Dali (Fig. 792). Compressed, arcnate,
almost rostrate ; the anterior side larger. Silurian.

Myrtea Turton (Fig. 791). Rounded, sub-equi-
latei'al ; teeth and posterior fold present. Tertiary
and Recent.

CodaJcia Scopoli. Compressed, reticulately sculp-
tured. Tertiär}' and Recent.

Miltha Adams (Fig. 790). Compressed, nearly
smooth ; laterals absent, cardinals long, feeble (3 : 2).
Tertiary and Recent.

Divariceila Martens. Rounded, inflated, valves
ornameiited with angular divergent grooving. Ter-
tiary and Recent.
Tertiary and Recent.

Pkacoides pulchra (Zitt. and Goiib.).
. Coral-Rag ; Glos, Calvados. 2/,.

Phacoides Blainville (Fig. 793).

Family 18. Oorbidae Dali.

Shell differing from the Lucinidae in heing transversely oval, thicJc, with a heavy
hinge plate, and usually luell-developed laterals ; two or three strong cardinals in each

Pio. 794.
Gonodun mellingi Hauer. Upper Trias ; Sarize am Predil, iiear Raibl, Tyrol. Vi-

valve; the margin of the valves denticulate, and the exterior strongly sculptured
external, the adductor scars oval, and not projecting into the pallial area.
Recent.

This family is an ofFshoot of the Lucinidae, with which it is commonly united.
Gonodon Scliafh. (Gorhis p. p. auct.) (Fig. 794). Rounded, plump, concentrically

ligament
Trias to

striated. Cardinals

LlOl
ROlO

sometimes a weak

posterior lateral present. Trias and Jura.

Gorhis Cuv. {Fimhria Megerle, non Boh.) (Fig.
795). Thick-shelled, oval, inflated, reticulately
sculptured ; each valve witli two short cardinals,
and anterior and posterior laterals ; adductor scars
similar, sub^equal. Jura to Recent.

Corhis lamellosa Lam. Eocene (Calcaire
Grossier) ; Grignon, near Paris, i/j.

Fio. 79(5.
Mutiella coarctata Zitt. Tnronian ; Gosau, Austria. Vi-

CLASS I

PELECYPODA

487

Sphaera Sow. (Palaeocorhis Conr.). Lower Civl;i(((.us. Sjihaeriola Stol. Trias

to Cretaceoiis. Fimhriella Stol. Chalk of Britaiii. Gorbicella Mor. and Lyc. Jura.

M'utiella Stol. (Fig. 796). Anterior cardinal border corriigated, uptiirned ;

posterior rectilinear, horizontal, witli a feeljlc lalcial tootli. Upper CretrOceous.

Family 19. Diplodontidae Dali.

Shell sub-circular in outline, rarely nestling and irregulär ; hinge with the laterals
obscure or absent, and the valve margins piain ; the adductor scars continuous peripher-
ally with the pallial line ; soft parts like the Lucinidae, but with the external limb of the
gills developed, and the anal foramen not tubulär. (?) Jura, Cretaceous to Recent.

Diplodonta Bronn (Fig. 797). Thin-shelled, orbicular, convex, concentrically
striate or pustulose ; cardinals 2 : 2, tlie left anterior and riglit posterior l)iM ;
laterals obscure or absent. Tertiary and Recent.

Ungulina Daudin. Nestling and often ir-
regulär. Felania Recluz. Shell conipressed ;
feeble laterals present. Axinopsis Sars ; Sphae-
rella and Tenea Conrad. Cretaceous to Recent.

Family 20. Oyrenellidae Fischer.

Diplodonta dilatata Phill. Plioceiie ;
Hhodes. Vi-

Shell as in Diplodonta, but loith a con-
spicuous epidermis ; pallial area smooth ; pallial
line not sinuate ; hinge without lateral laminae ; the cardinals like Diplodonta, or
with two cardinals in each valve soldered to each other dorsally ; cardinal formula

RTmmn' ^'^^ anterior left cardinal usually obsolete. Pliocene to Recent, in fresh and

brackish water.

Cyrenoida Joannis (Gyrenella Desh.). Pliocene of Florida, Recent in the Antilles
and West Africa.

Joannisiella Dali. Hinge as in Diplodonta, resilium immersed, the larger cardinal

)ifid, the teeth not soldered above. Cardinal formula

LlOlO

Roior

Recent ; Philippines.

Family 21. Thyasiridae Dali.

Shell substance earthy, ivith inconspicuous epidermis and prosocoelous beaks ; valves
equal, free, closed, ivith piain margins, smooth, or with feeble
concentric Striae, and usually with a radial posterior ßexure ;
adductors Lucinoid, pallial area often punctate ; ligament and
resilium parivincular, opisthodetic, sub - external, seated in a
groove ; area impressed ; hinge feeble without lateral laminae,
edentulous, or with an obsolete cardinal tooth in the right valve.
Cretaceous to Recent.

Thyasira Leach (Gryptodon Turton ; Axinus Sow.; Con-
chocele Gabb) (Fig. 798). Smooth, thin-shelled, living in
deep water. Cretaceous to Recent.

Philis Fisch, Lunule deeply indented, projecting sj^oon-
like into the cavity of the valves. Recent.

Fio. 79S.

A, Thyasira sinuosa (Don.).
Miocene ; Grund, near Vienna.
Vi- B, T. unicarinata Nyst.
Oligocene (Septaria - clay) ;
Freien wal<le, near Berlin.

Superfamily 8. LEPTONACEA Dali.

37te incurrent and excurrent openings between the mantle lohx "/
body, the former anterior.

'l'l'"

mh nl Ihr

488

MOLLUSCA

PHYLUM VI

This gi'oup contains a great many comniensal, nestling or parasitic forms ; if indepen-
dent usually very active, crawling like Gastropods on a sub-reptary foot, and witli the mantle
edges more or less reflected over the valves.

Family 22. Leptonidae Gray.

Shell cellulo-crystalline with a periostmcum ; valves equal, free, smooth-edged, often
gaping, variahly sculptured ; adductor scars peripheral, suh-equal ; pallial line simple ;
area ohscure or none ; ligament parivincular, opisthodetic, exter-
nal, often ohsolete ; resilium usually internal, suh-umhonal or
oblique ; hinge-plate narrow, channelled to receive the resilium ;
hinge variable, typically consisting of one or two radiating
cardinals and a pair of lateral laminae in each valve, the
anterior laminae often ahsent, and the posterior frequently
closely adjacent to the resilium, simulating cardinals. One
Cretaceoiis, and a niimber of Tertiary and Recent species.

Fio. 799.

A, Erycina pellucida Lam.
Calcaire Grossier ; Parnes. B,
Hinge of E. foucardi Desh.
Lower Bocene ; Herouval.
Greatly enlarged (after De-
shayes).

Erycina (Lam.) Fischer (Fig. 799) ; Kellia Turton ;
Pythina Hinds ; Lasaea Leach ; Lepton Turton ; Erycinella
Conrad ; Spaniodon Reuss ; Fahella Conrad, etc. Tertiary
and Recent.

Family 23. Galeommatidae Gray.

Shell without a perceptihle epidermis ; valves equal, free, widely gaping ventrally,
smooth or variahly sculptured ; adductor scars distant, oval, reduced ; pallial line
simple ; ligament usually ohsolete, resilium internal, suh-umhonal or oblique, attached
to an excavated chondrophore in each valve ; hinge-plate hardly
developed ; laterals ohscure or ahsent ; one or two cardinal teeth in
each valve or none. Tertiary and Recent.

Scintilla Desli. (Fig. 800) ; Galeomma Turton ; Passyia and
Sportella Desh. ; Hindsiella Stol. ; Ephippodonta Täte ; Solecardia
Conrad, etc. Tertiary and Recent.

Family 24. Ohlamydoconchidae Dali. scintuia paHsiensis

Desli. Upper Eocene ;
Shell cellulo-crystalline without an epidermis, comprising the ^f^^TieshaYes)^^' ^^^
prodissoconch with narrow, long, laminar accretions, very small ;
valves wholly internal, not connected, contained in laterodorsal separate capsules, without
hinge or hinge-plate, not attached to muscles or ligament ; ligament ahsent, resilium
separately encapsuled hetween the ohsolete valves, functionless. Recent ; California.

The genus Chlamydoconcha Dali is evidently the last term in a series beginn ing
with forms like Lepton, and continned l)y Galeomma and Eyhippodonta, but the
specialisation has been carried so far tliat it may well be regarded as the type of
a distinct family.

Family 25. Kelliellidae Fischer.

Shell with a periostracum ; valves equal, free, closed, smooth externally with piain
m,argins ; pallial line simple ; area ohscure or none ; ligament external, parivincular ;
resilium external or slightly sunken ; hinge plate narrow, entire, with one or tioo
cardinals, and a single anterior lateral placed ahove the anterior cardinal teeth. Tertiary
and Recent.

CLASS I

PELECYPODA

489

Kelliella Sars ; Lutetia Desli. ; (?) Ällopagus Stol. ; Turtonia Alder.
Receiit.

C Cyclodonta.

Eocene to

Teeth arched, sprmging from helow the hinge margin, with the hinge-plate ohscure or
absent.

Superfamily 9. CARDIACEA Lamarck.

Lobes of the mantle free behind the siphons, foot elongate, geniculate ; sculpture of
the shell chiefly radial ; cardinal teeth conical, the lateral laminae short, distant from the
cardinals.

Family 26. Cardiidae Fischer.

Shell substance cellulo-crystalline, with the external layer more or less tubulär ; valves
equal, free, gaping slightly behind, the beahs prosocoelous, the margins usually serrate or
radially striated ; adductor scars sub-equal, the pedal distinct and usually distant;
ligament and resilium parivincular, external, short, set in a groove ; area obscure ; com-
plete hinge armature consisting of an anterior and posterior lateral in the left, and two

B

Fio. 801.
Cardium %irodiLctum Sow. Turonian ; St. Gilgen, Salzburg, i/i-

anterior and one posterior lateral in the right valve, any or all of which may be absent ;
cardinal formula üöfQi > ^^^^ ^ß^^^^ simple, smooth, never bifid, one cardinal in each valve
usually persistent, the others inconstant. Trias to Recent.

Cardium Linii. (Figs. 801-803). Cordate, iiiflated, radiately ribhed or .striated,

Fio. 802.

Protocardia hifrons
Reuss. Turonian;
Strobl- Weissenbach am
Wolfgangsee, Austria.

Vi-

Fio. 803.

Cardium (Discors) discrejxins Bast. Miocene
Dax, ne.'ir Bordeaux, '/i.

490

MOLLUSCA

PHYLUM VI

with prominent beaks. Represented l)y aboiit 200 recent and over 100 fossil species. .
Trias to Recent.

A very large nuniber of subgenera aiid sections have been proposed, based chiefly pn the
external sculpture. Some of the more conspicuous groups are the following : —

Protocardia Beyr. (Fig. 802). Cretaceous. Discors Desh. (Fig. 803) ; Laevicardium
Swains. ; Serripes Beck ; Fragum Bolten ; Papyridea Swains. Tertiary and Recent.
Didacna Eichwald, estuarine, leads toward the next family.

Family 27. Limnocardiidae Stoliczka.

Like the Gardiidae, biit thin-shelled, with long nnited siphons, a short compressed

foot, a pallial sinus and obsolete
hinge armature, living in
bracMsh or fresh water. Ter-
tiary and Recent.

ii

Fi(i. 804.

Limnocardiuin conjungens Partsch. Pliocene (Congeria Stage) ;
Brunn, near Vienna. i/i.

Adacna Eicbw. Shell

elongate oval, truncate behind,

gaping at both extremities ;

Siphons very long, pallial

sinus deep. Miocene, and

Recent in Caspian Sea.

Limnocardium Stol. (Fig. 804). Cardinais weak, laterals strong, distant, pallial

sinus moderate, shell closed anteriorly. In brackish Miocene beds, especially the

Sarmatic and Pontic horizons of Eastern Europe, and in estuaries of the Aral, Black

and Caspian Seas.

Subgenera : Prosodacna Tourn. (Psüodon Cob.) ; Monodacna Eicliw. ; Ilhiocardimn Capell. ;
Arcicardium Fischer.

Superfamily 10. TRIDACNACEA Menke.

Soft parts rotated forward nearly 90° loith relation to the valves as compared with
typical dimyarian Pelecypods, the anterior adductor wanting, and the posterior nearly
central in the shell ; cardinal teeth lamellar, oblique.

Family 28. Tridacnidae Cuvier.

Shell very densely porcellanous, with no visible epidermis ; valves equal, free, with
a byssal gape, radially sculptured, with serrate margins and prosocoelous beaks ; ligament
and resilium as in the Cardiidae ; hinge with a single oblique cardinal in each valve, a
Single posterior lateral in the left, and two in the right valve. Eocene to Recent.

Byssocardium Mun.-Chalm. and Lithocardium Woodw., of the Eocene, are
perhaps precursors of the Recent Tridacna Brug. and Hippopus Lamarck.

Superfamily 11. ISOOARDIAOEA Dali.

Lobes of the mantle closed, except for the pedal and siphonal openings, smooth, double-
edged ; foot short, compressed ; . sculpture of the shell faint or concentric ; cardinal teeth
lamellar, parallel with the hinge margin.

Family 29. Isocardiidae Gray.

Shell substance cellulo-crystalline, the external layer not tubulate, with a marhed
epidermis ; valves equal, free, rotund, completely closed, with piain margins and pro-

CLA8S I

PELECYPODA

491

minent prosogyrous heaJcs ; adductor scars sub-equal ; pedal scar adjacent ; area not dis-
tinctly limited ; ligament and resilium external, parivincular, set in a deep groove, con-
tiniious to the heaks ; complete armature of the hinge with an inconstant posterior lateral
in each valve, and rarely, an anterior lateral dose to the cardinals ; cardinal formula

pqYqT) ihe teeth lamelliform, and very variable in details of form. Jura to Receiit,

Many species have been referred to this group solely on account of their having gyrate
beaks. Tlie Paleozoic and many Mesozoic species so referred must be separated from
Isocardia.

Isocardia Lam. (Figs. 805, 806). Inflated, smootli or concentrically striated ;
beaks distant, iniich produced, prosogyrate. Jura to Receiit

B

B'k;. 8UÖ.
Isocardia striata d'Orb. Portlandian ; Cirey, Haute-Marne (after Loriol).

Meiocardia Adams. Keeled, concentrically ribbed. Tertiary and Recent.
? Glisocolus Gabb. Cretaceous ; North America.

Fio. 806.
Hinge of Isocardia lunulata Nyst. Crag ; Antwerp.

Family 30. Vesicomyacidae Dali.

Shell as in the Isocardiidae, hut with low and inconspicuous heaks, the valves more
elongated, and the lunule delimited hy a sharp groove; cardinal formula piqiq^q'
Tertiary and Recent.

Callogonia Dali. Pallial line deeply sinuated, and a distinct anterior lateral close
to tlie cardinal teetli, Recent ; abyssal.

Vesicomya Dali. {Gallocardia auct., non Adams). Rounded or Tapetiform, com-
pressed, or not infiated, witli low, inconspicuous, non -gyrate beaks. Eocene and Recent.

D. Teleodonta.

The most perfected type of modern teeth, to which, in addition to the typical (10101)
cardinal series of the ordinary Teleodesmacea, there is added in the most specialised types
(Veneridae, Mactridae) either a roughened area (Veiius), a series of extra cardinals
(Tivela), or accessory lamellae (Mactra), rendering the hinge rnorr < ifinent, or covvphcdfrd.

492

MOLLUSCA

PHYLUM VI

The hinge characters of the less specialised forms hardly differ from the Diogenodonta,
but they are grouped here on account of their ohvious aßnities, as shown hy other
characters.

Superfamily 12. VENERACEA Menke.

Teleodonts with normal gills united to form a complete anal Chamber, the mantle
lobes free behind the siphonal region, sub-equal adductors, an external parivincular liga-
ment seated in a groove, and the shell substance densely cellulo-cry stalline with incon-

spicuous epidermis. Complete hinge formula r^wr — —f. — q-.^-./-. 0^, of which a large

part is usually deßcient.

Family 31. Veneridae Leach.

Valves equal, free, closed, with prosogyrous beaks, variably sculptured, with the
margins more or less dentate, except in the smooth species ; adductor scars peripheral,
pedal distant ; pallial sinus more or less sinuated, area very distinct ; resilium usually
external, embraced by the ligament ; hinge-plate developed ; formula of the cardinals

KÖToToT' '^'^^^ ^ Single obsolete lateral in one valve ; the cardinals frequently bifid,
usually radially

and sub-equal in size, except the posterior left one, which is often
obsolete or obscure ; supplementary cardinals or
rugosities are present in specialised forms. Jura
to Recent ; maxinuim in Tertiary and later.

The faniily must be divided into at least four
subfamilies, as follows : —

a. Venerinae : typical, with produced siphons,
not byssiferous, the yoimg not retained within the
mather after leaving the egg.

h. Circinae : with separate short siplions, cor-
relative nearly simple pallial line, sub - internal,
partially amphidetie resilium, and compressed beaks.

c. Tapetinae : with long but partly separated
siphons, a byssus present at least in the young ;
hinge with no lateral teeth, otherwise like the
Venerinae.

d. Gemminae : minute Shells, with more or less
separated siphons, no byssus, obsolete lateral laminae,
and sheltering the nepionic young within the cavity
of the mother.

a. Pronoella Fisch. (Pronoe Ag., non Guer.

Men.). Compressed, pallial sinus very shallow ;

a posterior lateral and tliree cardinals in eacli

valve. Jura.

Like the preceding, but the riglit valve wdth only

two cardinals, the hinder one bifid ; pallial sinus very shallow. Cretaceous.

Dosinia Scop. {Artemis auct.). Orbicular, lentiform, concentrically sculptured,
with a deep, well-marked lunule : cardinals 3:3; pallial sinus deep, ascending,
pointed. Cretaceous to Recent.

Eocyclina Dali. (Cyclina Desh.). Cretaceous to Recent. Sunetta Link {Meroe
Sclium.) ; Grateloupia Desm. Tertiary and Recent. dementia Gray. Oligocene to
Recent.

Venus Linn. (Fig. 808). Oval or rounded, plump, cordate, thick ; concentrically
or radially sculptured, with denticulate margins ; hinge-plate broad, with tliree
cardinals in each valve and no lateral teeth ; pallial sinus short, angular. Jura to

Fig. 807.
Cyprimeria discus (Math.). Upper
Cretaceous ; Gosau Valley, Austria.

Cyprimeria Conr. (Fig. 807).

CLASÖ I

PELECYPODA

493

Recent ; represented by about 200 fossil and as many recent species. Very numerous
siib-divisions have been proposed ; Venus s.s. is typified by V. mercenaria Lam.

Venus cinda Eichw,

Fig. 808.
Miocene ; Gainfahrn, near Vienna.

Fig. 809.

Meretrix semisulcata Lam.
Bocene ; Grignon, near Paris,

Meretrix Lam. {Gytherea aiict.) (Figs. 809, 810). Hinge with lateral teeth.
Macrocallista Meek ; Callocardia Adams ; Saxidomus Conrad. Tertiary and Recent.

Meretrix inciussata Sow,

Weinheim, near Alzey.

Fig. Sil.

Circe exiviia
Hoernes. Miocene ;
Bnzesfeld, near

Vienna.

Tivela Link. Hinge with supplementary cardinals. Miocene to Recent.
h. Girce Schiim. (Fig. 811). Gafrarium Bolten. Umbones compressed, sculpture
often divaricate, ligament immersed. Tertiary and Recent.

Subgenus Gouldia Adams. Sniall, concentrically striated.
Eocene to Recent.

Ptychomya Agassiz.
Cretaceous.

c. Paphia Bolten
(Tapes Megerle ; Pul-
lastra Sow.) (Figs. 812-
814). More or less
elongate, oval, with
narrow hinge - plate,
divergent and often
bifid cardinals, no la-
terals, and deep pallial
sinus. Cretaceous to
Recent ; about 150
living species.

Flu. Sl-J.

Paphia gregaria Partsch.
Sarmatian Stage ; Wiesen, near
Vienna.

Fig. 813.

Paphia (Baroda) fragilis (d'Orb.).
Upper Cretaceous ; Gosau, Austria.

494 MOLLUSCA phylüm vi

Of tlie nunierous subgeiiera, Baroda (Fig. 813) and Iscanotia (Fig. 814) Stol., from the

Cretaceous, are remarkable tbr their elonga-
tioii and tlie ridge-like form of tho posterior
Cardinal.

Onco'phora Rzehak. Differs from Ta2?es

in having a very sliort pallial sinus, and

the anterior addiictor scar bounded by a

ridge. Miocene brackish-water beds.

Fio- 814. Venempis Lam. Cardinal teeth 2 :

' Paphia (Iscanotia) impar Zitt. Upper Cretaceous ; 2-3, stronff ; a borer or nestler, often de-

Gosau. /.im. T 1-,

formed. Tertiary and Kecent.

d. Gemma Desli. ; Parastarte Conr. ; Psephidia Dali. Minute Shells. Eocene
to Recent.

Family 32. Petricolidae d'Orbigny.

Valves, when not distorted, equal, free, somewhat gaping hehind, radiately sculptured
with piain margins and inconspicuous heaks ; posterior adductor scar larger tkan the
anterior, pedal narrow, elongated, distinct ; ligament and resilium external ; area
ohscure or not defined ; hinge without lateral laminae, with two or three small, usually
bifid, radial cardinal teeth in each valve. Cretaceous to Recent.

Petricola Lam. (Choristodon Jonas ; Naranaio Gray) ; Petricolaria Stol.

The family Glaucomyacidäe, of estuarine or fluviatile habit, appears to be related
to Petricola, and includes the Recent Glaucomya (Bronn) Woodward, and Tanysiphon
Benson.

Superfamily 13. TELLINACEA Blainville.

Siphons distinct to their hases, usually long ; ^aZ^m? line sinuate ; ligament external,
seated on nymphs ; hinge typically with an anterior and posterior lateral in each valve,
two radial cardinals, of which the anterior is commonly hifid and somewhat pedunculated,
and the posterior, as well as the laterals, often obsolete.

Family 33. Tellinidae Deshayes.

Shell substance cellulo-crystalline, with an inconspicuous epidermis ; valves slightly
unequal, free, rounded in front, more or less rostrate, oblique, and gaping behind, com-
pressed, usually loith smooth margins, low beaks, and variable, chießy concentric sculpture ;
anterior adductor scar larger, frequently irregulär ; pedal distinct ; resilium embraced in
the ligament, sub-external ; area narrow, small, covered with a dark ejndermis, or
frequently obsolete ; hinge-plate narrow, anterior laterals approximate, posterior more
distant from the cardinals, when present ; cardinal teeth small ; pallial sinus deep,
discrepant in the opposite valves. Jura to Recent.

Tellina Linn. Elongated, the rostrum more or less twisted ; two lateral teeth in
each valve ; shell porcellanous. Jura to Recent.

Subgenera: Teilina s.s. (Figs. 815, 816); Tellidora Mörch ; Strigilla Turton ; Lincaria
Conrad (Areopagia d'Orb.) (Fig. 817), etc.

Macoma Leach. Anal siphon long, branchial very short, hinge without laterals ;
shell smooth, earthy, less elongated than in Tellina. Tertiary and Recent.

Gastrana Schum. {Fragilia Desh.). Miocene and Recent.

Quenstedtia Mor. and Lyc. Long, oval, obliquely truncate behind ; beaks low,
pallial sinus shallow, only a single cardinal tooth present. Jura.

CLASS I

PELECYPODA

4Ü5

Fig. 810.

Tcllina rostralina Desh. Eocene ; Damery,
near Epernay.

Tellina plaiiata Lam. Miocene
near Vienna.

Pötzleinsdorf,

Fig. 817.

Tellina (Linearia) biradiata Zittel. Upper

Cretaceous ; Gosau, Austria.

Family 34. Semelidae Dali.

Resembling the Tellinidae, but with the resilium internal, often on a distinct chondro-
phore, and lüith the laterals, when present, stronger and less distant. Tertiary to Kecent.

Semele Schiim. (Ämphidesma Lam.). Shells large, rounded, thick, often conspicu-
ously sculptiired ; 100 species. Tertiary and
Kecent.

Cumingia Sow. Small, tliin, with a spoon-
like chondrophore ; habit nestling. Tertiary
and Recent.

m-^^

Fig. 818.

Ahra apelina (Ren.). Miocene ; Grund,
near Vienna.

Scrohicularia Schum. Differs froni Semele in
having no lateral teeth. Tertiary and Recent.

Ahra Leach (Syndosmya Recluz) (Fig. 818).
Smooth, small, thin ; cardinals 2:2, an anterior and posterior lateral present ;
chondrophore narrow, oblique, not separated from the hinge line. Tertiary and
Recent ; chiefly in deep water.

Family 35. Psammobiidae Dali.

Shell as in the Tellinidae, hut usually more
equivalve and less twisted, with more conspicuous
epidermis and nymphs, hroader hinge-plate, and
a wider posterior gape ; lateral laminae on the

Fig. 819.

Psammobia effiisa Desh. Eocene (Calcaire
Grossier) ; Farnes,

• Fig. 820.

Psammosolen (Macha) deshayesii (Desm. ). Calcaire
Grossier ; Grignon, near Paris, i/j.

496

MOLLUSCA PHYLUM VI

hinge ivantiiKj^ and the cardinals sometimes three in one valve ; li(jament external and
conspicuous ; no defined area. Tertiary and Recent.

Psammohia Lainarck {Gari Sclium.) (Fig. 819). (?) Cretaceoiis. Tertiary and
Recent.

Pliorhytis Conrad ; Asaphis Modeer ; Sanguinolaria Lam. ; Tagelus Gray ; Nova-
culina Beiison ; Ämphichaena Phil. ; Psammosolen Risso, witli subgenus Macha Oken
(Fig. 820) ; Azor Leach ; and Heterodonax Mörcli. Cretaceons to Recent.

Family 36. Donacidae Desliayes.
Valves equal,free, siib-trigonal, usually closed, solid ; outer surface and inner margins
smooth or radially sculptured, the posterior end usually shorter and obliquely sub-truncate ;
2Jallial sinus similar in both valves ; resilium sub-internal, sometimes amphidetic ;
ligament short, external, seated in a deep groove, episthodetic ; hinge-plate moderately
developed, usually with a posterior and anterior lateral in the right, and corresponding

sockets in the opposite valve; cardinal formula t.q-,qY' ^^'^ strongest cardinal tooth often
bifid. Lias to Recent.

The resilium is chiefly opisthodetic and sub-internal, but some of the large species have a

sniall Segment of the resilium separate from the rest,
wholly internal, and in front of the beaks.

Isodonta Buv. {Soiverbya d'Orlj.) Snb-syniniet-
rical, convex, laterals strong, pallial sinus deep. Jura.
Donax Linn. (Fig. 821). Anterior side longer,
laterals weak. Upper Eocene and Recent ; about
Piti. 821. lOÖ species. Subgenus Iphigenia Schuni. Recent.

Donax lucÄda Eichw. Miocene (Sarmatian Egeria Lea. Lower Eocene.

stage); Wiesen, near Vieiina. ^2) Hemidonax Morch {Donacicardium Vest).

Superfamily 14. SOLENACEA Lamarck (emend.).
Dwellers in soft sea-bottom, narrow, elongated, modified for burrowing, gaping at
both ends ; foot elongated, distally modified to serve as a piston or stilt within the
burrow ; siphons short ; hinge without lateral laminae.

Family 37. Solenidae Leach.

Shell substance as in Tellina, but the external layer showing its cellular structure
more clearly ; with a pronounced epidermis ; valves equal, free, usually truncoAe at both
ends, and more or less ineqidlateral, with low beahs, smooth margins, not rostrate, smooth
or feebly sculptured ; adductor scars narrow, elongate, dorsally distributed, pedal distinct ;
pallial sinus small in species with anterior umbones, and vice versa ; ligament and re-
silium external, parivincular, seated on nymphs ; area obscure or none ; hinge-plate
hardly developed ; hinge often with a thickened ray crossing the valves and serving as a
buttress ; cardinals varying from one to four in each valve, usually a single slender
radial laminar cardinal in the right, and tioo in the left valve, with or without one or
two placed parallel with the hinge margin, simulating laterals; radial teeth usually
more or less pedunculated, rarely bifid. Devonian to Recent.

The Silurian forms heretofore referred to this family do not seem to belong to it, but
Palaeosolen Hall is scarcely distinguishable externally from some modern forms ; its hinge,
however, is unknown. The species of this family are mostly much modified for a special
mode of life, hence the variability in certain features, such as the siphons, foot and ferma-
ture of the mantle lobes.

Solen Linn. (Fig. 822), Scabbard-shaped, straight, with terminal beaks. Among
the numerous subgenera are : Ensis Schum. ; Pharella Gray ; Geratisolen Forbes ;
Siliqua Megerle ; Gultellus Schum. (Fig. 823). Tertiary and Recent.

CLASS I PELECYPODA

Palaeosolen Hall. Devoiiian. Leptosolen Conrad, Cretaceous.

497

Solen suhfragilis Eichw. Miocene (Sarma-
tian Stage) ; Pullendorf, Hungary.

Fio. 823.

Cultdlus gngnonensis Desh. Calcaire
Grossier ; Grignon, near Paris.

Superfamily 15. MACTRACEA Gray.

Resilium internal, seated on chondrophores, left cardinal tooth hifid, fitting below the
hüo right cardinals, which are more or less joined together dorsally. Inner ivall of the
mantle hehind the siphons exhibiting a laminar sense organ.

Family 38. Mactridae Gray.

Shell porcellanous, loith an ohvious epidermis, usually rounded-triangular, with
smooth or concentrically sculptured surface, smooth margins, and prominent prosogyrous
heahs ; valves eqtial, 'free, usually with a slight posterior gape ; area not limited; liga-
ment variahly external or internal; resilium connecting sub-triangular chondrophores
usually excavated out of the hinge-plate, rarely with a prop or buttress ; hinge-plate well
developed, with tijpically an anterior and posterior lateral in the left, received into sochets
or paired laminae in the right valve, or obsolete ; cardinals in the right valve two, with
their dorsal edges usually soldered together, and one bifid or deltoid cardinal in the
left, fitting beloiv the former, a delicate accessory lamella often present in either valve, or
all may be more or less obsolete; siphons well developed, united, and usually with an
epidermal tunic ; adductors peripheral, sub-equal. Cretaceous to Eecent.

This group is so large and its extre;nes so variable, that
it is best divided into subfamilies, as follows : ^ Mactrinae,
Pteropsidinae, Lutrariinae, Zenatiinae and ? Anatinellinae.

Mactra Linn. (Fig. 824).
separated by a shelly septum.

Ligament and resilium
Tertiary and Recent

Subgenera : Mactra s.S., Coelomactra, Mactroderma,
Mactrotoma Dali ; Mactrella Gray.

Fk;. S24.

Mactra podolica Eichw. Miocene
(Sarmatian Stage) ; Wiesen, near
Vienna.

Fi(i. 825.
lAUraria elliptica Roissy. Pliocene ; Rhodes. 2/3

Spisula Gray. Ligament and resilium not separated, the former more or less
external. Cretaceous to Recent.

^ Dcdl, W. ff., Synopsis of a Review of the Genera of Recent and Teitiary Mactridae and
Mesodesmatidae. Proc. Mal. Soc., 1895, vol. i.

VOL. I 2 K

498

MOLLUSCA

PHYLUM VI

Subgenera : Hemimactra Swains. ; Leptospisula Dali ; Cymbophora Gabb ; Schizodesma Gray.

Mulinia Gray. Ligament and resilium immersed in the same socket. Miocene
and Recent.

Rangia Desni. (Gnathodon Gray, non Goldfuss). Like Mulinia, but with
elongated laterals, and the anterior lateral liooked at the umbonal end. Estnarine.

Pteropsis Conrad. Eocene. Xak'om (Schmidt) Möller. Miocene and Recent.

Lutraria Lam. (Fig. 825). Soleniform, hinge Mactroid. Tertiary and Recent.

Schizothaerus Conr. {Tresus Gray) ; Eastonia Gray ; Heterocardia Desli. Tertiary
and Recent. Zenatia Gray ; Änatinella Sow. Recent.

Family 39. Oardiliidae Dali.

Shell cordiform, with prominent prosogyrous heahs, small, thin, radially scu^Jtured ;

^rior adductor scar impressed upon a radial myophoric lamina, the anterior scar
elongated, pallial line not sinuated ; ligament external, seated on nymphs ; resilium
internal connecting projeding chondrophores ; hinge without laterals, hut the cardinal
teeth as in Mactra. Tertiary to Recent.

Gardilia Deshayes. Eocene and Recent.

Family 40.

Fig. 826.

Ervilia podolica Eichw. Miocene (Sar-

matian Stage) ; Wiesen, near Vienna. Vi-

Mesodesmatidae Deshayes.

Shell solid and heavy, usually Donaciform, with
erect or opisthogyrate heahs, otherwise as in the Mactridae;
Siphons naked, not united. Tertiary to Recent.

Mesodesma Desh. Tertiary and Recent. Mac-
tropsis Conr. Eocene. Ätactodea Dali (Paphia
Lam. ; Eryx Swains.) ; Davila Gray ; Anapella Dali.
Recent. Ervilia Turton (Fig. 826). Tertiary and
Recent. Gaecella Gray. Recent, fluviatile.

E. ASTHENODONTA.

often essehtially Mactroid, hut usually degenerate or ohsolete, owing to modi-
fications induced hy the hurroiving hahit.

Superfamily 16. MYACEA Menke (emend.).

Burrowing, long siphoned, frequently inequivalve Pelecypods, usually with the mantle
lohes largely united helow, more or less united siphons, and degenerate hinge apparatus.

Family 41. Myacidae Wood ward.

Shell suhstance cellulo-crystalline, earthy, with a conspicuous epidermis ; valves un
equal, more or less elongate, rounded in front
and gaping hehind ; adductor scars suh-
equal ; pallial line sinuated; shell margins
piain ; area ohsolete or none ; ligament and
resilium internal, opisthodetic, attached in
the left valve to a projeding chondrophore
merging with the dorsal margin hehind, and
in the right valve to an inconspicuous,
usually suh-umhonal chondrophore; hinge
edentulous ; siphons united, with a horny
tunic, not wholly retradile. Tertiary and
Recent.

Fig. 827.

Mya arenaria Linn. Pleistocene (Glacial Deposits)
Bohuslän, Sweden.

CLASS I PELECYPODA 499

Mya Liiiii. (Fig. 827). Smooth externally. Tertiary and Recent.

Siibgenera : Platyodon Conrad. Surface dccussated, siphou with horny appendages.
Cryptomya Conrad. Small, the pallial line discrepant in the two valves. Sphenia Turton.
Minute, byssiferous, nestling. Tugonia Gray. Tertiary and Recent.

Family 42. Oorbulidae Fleming.

Shell small, much as in Mya, hut the pallial line feeble or obsolete, the ligament
usually suh-external, separated from the resilium, which is internal, alivincular and
amphidetic ; the chondrophore
is received into a socket of the
opposite valve, not merged with
the valve margin ; hinge lüith
one or two sub-umhonal pro-
jecting teeth, and rarely ohscure
traces of laterals ; the posterior
gape inconspicuous ; siphons
short, united, naked, wholly
retractile. Trias to Recent.

Fio. 828.

Corbukt (Bicorbula) gallica La in.
Calcaire Giossier; Damery, near
Epernay, France. Hinge, i/i.

Fio. 829.

A, Corbula carinata Duj.
Miocene; Pötzleinsdorf, oear
Vienna. B, C. angjisUUa Sow.
Upper Cretaceous ; Gosau.

Corbula Lam. (Figs. 828,
829). Small, ovate, rostrate, very inequivalve, the riglit valve convex, larger, with a
prominent tooth in front of the pit for the resilium, left valve with a flattened
chondrophore, and usually a posterior tooth. Trias to Recent.

Subgenera : Erodona Daudin {Azara d'Orb. ; Potamomya Sow. ). Pallial sinus obsolete,
fluviatile. Pleistocene and Recent. Bothrocorbula Gabb. With a lunule deeply indented
into tlie cavity of the valves. Tertiary and Recent. Corhulamella Meek. With an anterior

myophore. Cretaceous. Aniso-
Ä thyris Conr. (Pachydon Gabb).

Pliocene. Paramya Conr. ; Cor-
hulomya Nyst. Tertiary and
Recent.

Family 43. Saxicavidae

Gray.

Shell substance as in Mya ;
epidermis conspicuous ; valves
equal, free, rüde and often
irregulär, more or less elon-
gated and gaping, not fully
covering the animal ; adductor
scars often irregulär, the pallial
line discontinuous or irregulär,
the sinus distinct ; shell mar-
gins smooth; area obsolete;
ligament and resilium external,
parivincular, seated on strong
nymphs, sometimes widely ex-
tended ; hinge without laterals^
with few feeble or obsolete sub-
umbonal cardinals. Creta-
ceous to Recent.

Saxicava Fleuriau (Glycimeris Schum. ; Hiatella Daudin ; Byssomya Cuvier ;
Agina Turton). Hinge edentulous in the adult, with one or two caitlinals in the

Panope msnardi Desh
of valves. B, Internal mould

Miocene; Vienna Basin. A, Dorsal view
C, Hinge-plate seen from above, V2'

500

MOLLUSCA

PHYLUM VI

yoiing, boriiig in the softer rocks. Tertiary and Recent. Subgenus Panomya Gray
{Chaenopea Mayer).

Panope Menard ^ {Glycimeris Lam. 1799, non Da Costa) (Fig. 830). Large, gaping
widely behind and sliglitly in front ; siirface concentrically, or feebly sculptured ; an
obscnre tootli in eacli valve. Cretaceous to Recent.

Gyrtodaria Daudin (Glycimeris Lam. 1801, non. Schum.). Solenoid witli strong
epidermis. Pliocene and Recent.

Family 44. Gastrochaenidae Gray.

Shell suhstance as in Saxicava ; valves equal, widely gaping in front ; adductor scars
unequal, the anterior smaller ; pallial sinus deep, margins simple ; area none ; ligament
and resiliurn external, parivincular ; hinge with a single obsolete cardinal or wholly

edentulous ; animal frequently forming
an external protective tuhe to Supplement
its hurrow, hut to which it is in no way
attached. (?) Permian. Trias to Recent.

This group Stands between the Myacea

and Adesmacea, verging on the latter. Many

of its characters are adaptive, and are re-

peated in the Ensiphonacea, but niorpho-

c»^™=e. mS l°gi'=='"y it« ■■•'l'^ttons to the Saxicavidae

- - seem close.

Fio. 832.
Gastrochaena deslong-

Fio. 831.

Gastrochaena angusta Desh
Eocene (Sables moyens)
Valmandois, near Paris.

Jura; Baiin, near Cracow
Internal mould of burrow
including one of the
valves, i/j.

Gastrochaena Spengler ( Ghaena

Retzius ; Rocellaria Blainv.) (Figs. 831,

832). Bores cylindrical or pear-shaped cavities in rock, sliell, or coral. Trias to Recent,

Fistulana Brug. Secretes calcareous tiibes wliich stand upriglit in the sand or

mud. Recent.

Superfamily 17. ADESMACEA Blainville.

Gills with direct and reßected laminae, long, united, extended into the hranchial
siphon ; posterior adductor usually in front of the visceral ganglion, anterior adductor
external to the cavity of the valves, exerted in a contrary sense to the posterior muscle ;
hinge margin reflected, edentulous ; ligament obsolete ; a myophoric process extending
freely into the valve from the sub-umbonal cavity.

Family 45. Pholadidae Fischer.

Shell cellulo-crystalline, with a thin epidermis ; valves more or less gaping in front
and behind, with inconspicuous beahs and reticulate, often spinöse sculpture ; in the

Fig. 833.
Fholas levesquei Watelet. Eocene ; Ciiise de la Mothc

adult supplemented by accessory shelly pieces, always attached to the valves, but rarely by
an exterior shelly tube like that of the Gastrochaenidae ; the antero-dorsal margins more
or less extensively reßected, the postero-ventral approximated ; pallial line sinuated, area

^ Erroneously written Panopea by many authors.

CLASS I

PELECYPODA

501

none ; liijament and resilium usually ahsent, an obsolete remnant of the redlium and
chondrophore sometimes present in the left valve. (?) Carbon it'eroiis, Jura to ßecent.

Pholas Linn. (Fig. 833). Surface divided by grooves iiito areas which ofteii have
diverse sculpture ; the adult ofteii provided with accessory shelly plates, eacli of which
when seated in front of the beaks has been named
a " protoplax " ; when above the beaks, " mesoplax" ;
when behind the beaks between the valves, " nieta-
plax " ; and when between the valves ventrally
(Martesia), " hypoplax." A calcareous septum,
secreted after the conipletion of the burrow, and
occupying the pedal gape of the valves, is called
the "callum." The addition of these plates and
appendages dnring growth so changes the appear-
ance of the shell that old and yoiing stages have
frequently been described as specifically or even
generically distinct. Typical Pholads date from
the Jura. Many subgenera have been named.

Turnus Gabb (Fig. 834). Cretaceous. Martesia Leach (Fig. 835). Carboniferous
to Eecent. Jouannetia Desni. Tertiary and Recent. Teredina Lani. Valves in the
adult stage soldered together and to a thick adventive calcareous tube. Eocene.

Fig. 834.

Turnus (Xylopha-
gella) ehgantulus
Meek. Upper Cre-
taceous ; Idalio.
Enlarged (after
Meek).

Martesia conokka
Deshayes. Eocene ;
Auvers, near Paris.

Vi.

Shell

Family 46. Teredinidae Scacclii.

reduced, equivalve, auriculate, widely gaping, the valves apposited
ventrally only on the surface of a parietal tubercle ; adductor
scars unequal, thd anterior marginal very small ; pallial
line coincident with the valve margins ; a styloid myophore
projecting from the cavity of the beaks ; mantle secreting a
calcareous lining to the burrow; pallets variable in form, the
valves without attached accessory shelly plates ; area none ;
hinge margin reflected, edentulous ; ligament absent or
obsolete; anterior adductor degenerate^ attached on the
anterior edges of the valves^ and covered only by the mantle ;
animal boring, chießy in wood. Carboniferous (?) ; Jura to
Recent.

Pallets simple, spatuli-
Pallets articulated,

Fir,. 836.

A, Valves of the recent Teredu
norvegica Spengl ; inner and outer
Views. B, Fallet of Xylotrya sp.
C, Fallet of Teredo sp. D, Gasts
of borings of Teredo tounmU Leym.
Eocene ; Kressenberg, Bavaria.

Teredo Linn. (Fig. 836, A, G).
form. Jura to Recent.

Xylotrya Leach (Fig. 836, B).
bipinnate. Tertiary and Recent.

The name Teredolites Leymerie, has been proposed for
the casts of borings of fossil Teredos (Fig. 836, D). The
problematical genus Polorthus Gabb, from the American
Cretaceous, has been referred to this family. The
Paleozoic species are known only by burrows, which are
of somewhat doubtful origin.

Vertical Range of the Pelecypoda.

Two sniall forms of bi valve shells, Fordilla and Modioloides, occurring in the
Lower Canibrian of New York State, have been doubtfully referred to Pelecypods,
but are more probably to be regarded as Brauch iopod Crustaceans. Aside from these
fossils, whose molluscan affinities must be considered as highly problematical, Pelecypods

502 MOLLUSCA phylum vi

are unknown from strata geologically older than the St. Peter sandstone, whicli is of
early Ordovician age. Here appear suddenly several genera of the Modiolopsidae, and
this family, together with the Anibonychiidae, Cyrtodontidae, and Ctenodontidae,
attain the acme of their development during the Middle and Upper Ordovician. In
the Silurian a considerable number of bivalves is observable, as many as eighty
species having been distinguished in the fauna of the small island of Gotland alone.

A very marked difference in geological ränge is perceptible among the three Orders
into which the class is divided. The Prionodesmacea, including most of Neumayr's
Palaeoconcha, are pre-eminently characteristic of the Paleozoic faunas. Of the forty-
two families referred to this order, no less than seven occur in the Ordovician, and
eighteen in the Silurian, to which seven are added during the Devonian, only three in
the Carboniferous, and one in the Permian. From these ancient Stocks only seven
Prionodesmacean families are evolved during the whole of the Mesozoic, and but two
in the Tertiary, while three are Eecent.

The Order Änomalodesmacea is represented in the Paleozoic solely by its radical,
the Pholadellidae ; eight of its sixteen families originate in the Mesozoic and Tertiary,
and, with the exception of the Pholadellidae and Pleuromyacidae, all have endured
until the present time. Only one family appears to be exclusively Eecent.

The Teleodesmacea are distinctively modern, although foreshadowed in the Paleo-
zoic by Cypricardian, Lucinoid and Allodesmid radicals (the Solenoid radical is still
questionable). Of forty -seven families thirty can be first definitely recognised in the
Mesozoic, twelve originate in the Tertiary, two are exclusively recent, and only a single
one can be traced continuously from the Paleozoic to the recent fauna.

Of the Prionodesmacean families, lO'ö per cent survive ; of the Teleodesmacean 71
per cent ; and of the Anomalodesmacean 88 per cent. If it were not for the mortality
among the Chamacea and Rudistacae, the ratio of survival among the Teleodesmacean
families would be 95 per cent. Of 105 families which have been discriminated during
the whole history of the class, 76, or about 72*3 per cent, are represented in the
existing fauna. Families have originated in the various geological epochs as follows :
Ordovician 9, Silurian 11, Devonian 9, Carboniferous 3, Permian 1, Trias 13, Jura 14,
Cretaceous 18, Eocene 15, Miocene and Pliocene 3, Pleistocene and Recent 6. From
this it appears that the development of the group, judged by the increase of families,
was most intense during the Silurian, thereafter rapidly decreasing until the Trias,
then gradually increasing until the Cretaceous, after which the rate of differentiation
again rapidly declined. It is noted that in the Paleozoic the Pelecypods form about
one-quarter of all the moUusks known from this era ; in the Jura and Cretaceous
about one-half, and in the Tertiary about one-third of this number.

The Ordovician and Silurian are especially characterised by the presence of
Taxodont, Palaeoconch, and the older forms of Schizodont Pelecypods. The Cardio-
lidae, Pterineidae, Ambonychiidae and Modiolopsidae are common to both the Silurian
and the Devonian.

The Devonian has no families solely characteristic, but the brackish-water Car-
diniidae, the Megalodontidae, Trigoniidae, Pinnidae, Pectinidae and Mytilidae first
take rise in this period, and the sinupalliate Ällorisma is the first Pelecypod showing
clear evidence of retractile siphons.

The Carboniferous is marked by the appearance of Parallelodon and its allies,
the Limidae and Ostreidae, and some precursors of the Lucinacea and Pholadacea.
The Pernidae and Gastrochaenidae make their advent in the Permian ; but, on the
whole, the Carboniferous fauna persists throughout this period. In the Trias, however,
important changes take place ; many old genera disappear, and such forms as the Limop-
sidae, the true Uniones, Spondylus, Dimya, the Pleuromyacidae, Pholadomyacidae,
Astartidae, Lucinacea, Cardiidae and Corbulidae enter upon the scene.

During the Jura, genuine Arcidae, Änomia, Eligmus, various Anatinacea, Cyrena^
Diceras, Isocardia, and the Teleodont Veneridae, Tellinidae, Donacidae and Pholadacea

CLASS I PELECYPODA 503

arc initiated. The cliaracter of the Cretaceous is strongly influenced ]jy tlie aberrant
and sliort-livcd Chamacea and Rudistids. The Mutelidae, Pandoridae, Clavagellidae,
Poromyacidae, Crassatellitidae, Cryptodontidae, Petricolidae, true Solens, the Mac-
tridae and Saxicavidae, also take their origin during this period.

With the beginning of the Tertiary a gradual approxiniation to present conditions
takes place. The Rudistae have disappeared, the Dysodonts are on the decline, and
the Teleodesniacean types on the increase. Nunierous Anatinacea, Leptonacea, Tridac-
nidae, Callocardiidae, Senielidae, Mesodesmatidae and Myacidae appear. At the close
of the Eocene, the wide distribution of many types now characteristic of warm-
ternperate, or tropical waters begins to be restricted ; and during the Miocene the
faunal boundaries of mollusks depending* upon temperature conditions are laid down
nearly on existing lines.

The following table indicates more ejcactly the geological ränge of the families of
Pelecypods according to oiir present information : —

[Tabl:

504

MOLLUSCA

PHYLUM VI

Families.

1

i

i
1

1

! d

CS

i

1-5

1

i

6

1

Order 1. Prionodesmacea

A. Palaeoconcha

1. Soleniyacidae .

2. Solenopsidae .

3. Vlastidae

4. Grammysiidae

5. Cardiolidae .

6. Antipleuridae

7. Praecardiidae .

B. Taxodonta
Superfamily 1. Nuculacca

8. Ctenodontidae

9. Nuculidae

10. Ledidae .

Superfamily 2. Arcacca

11. Parallelodontidae .

12. Cyrtodontidae

13. Limopsidae .

14. Arcidae .

C. SCHIZODONTA

Superfamily 3. Pteriacea

15. Pterineidae .

16. Lunulicardiidae

17. Ambonycliiidae

18. Pinnidae

19. Conocardiidae

20. Pernidae

21. Pteriidae

22. Myalinidae .

23. Vnlsellidae .

Superfamily 4. Ostraeea

24. Ostreidae

25. Eligmidae

Superfamily 5. Naiadacea

26. Cardiniidae .

27. Megalodontidae

28. Unionidae

29. Mutelidae

30. Etheriidae .

Superfamily 6. Trigoniacea

31. Lyrodesmidae

1
i

^""^

-

1

! _

i

!
i

i
'■"'

1

!

■

[

'

—

..

—

1 1

■

~

32. Trigoniidae .

1

1

!i

i 1

CLASS I

RANGE OF THE PELECYPODA

505

Families.

s

O I Ä

D. ISODONTA

Superfamily 7. Pectiih

33. Pectinidae

34. Spondylidae

35. Dimyidae

36. Limidae .
Superfamily 8. Anomiacea

37. Anoraiidae

E. Dysodonta
Superfamily 9. Mytüacea

38. Modiolopsidae

39. Mytilidae

40. Dreissensiidae

Order 2. Anomalodesmacea
Superfamily 1. Anatinacea

A. Eusiphonia

1. Pleuromyacidae

2. Pholadellidae .

3. Pholadomyacidae

4. Anatinidae

5. Periplomatidae

6. Thraciidae

7. Myochamidae .

B. Adelosiphonia

8. Pandoridae

9. Lyonsiidae

10. Lyonsiellidae .
Superfamily 2. Ensiphonacea

11. Clavagcllidae .

12. Euciroidae
Superfamily 3. Poromyacea

13. Poromyacidae

14. Cuspidariidae

506

MOLLUSCA

PHYLUM VI

Families,

Order 3. Teleodesmacea

A, Fantodonta

1. Allodesmidae .

B. DiOGENODONTA

Superfamily 1. Cypricardiaeea

2. Pleurophoridae
Superfamily 2. Astartacea

3. Curtonotidae .

4. Astartidae

5. Crassatellitidae
Superfamily 3. Cyrenacca

6. Cyrenidae

7. Sphaeriidae . ,
Superfamily 4. Gardüacea

8. Carditidae

Superfamily 5. Chamacca

9. Diceratidae .

10. Chamidae

11. Monopleuridae

12. Caprinidae

Superfamily 6. liudistacea

13. Radiolitidae .

14. Hippuritidae .
Superfamily 7. Lucinacea

15. Tancrediidae .

16. Unicardiidae .

17. Lucinidae

18. Corbidae

19. Diplodontidae

20. Cyrenellidae .

21. Thyasiridae .

Superfamily 8. Leptonacea

22. Leptoiiidae .

23. Galeommatidae

24. Chlamydoconchidae

25. Kelliellidae .
C. Cyclodonta

Superfamily 9. Gardiacea

26. Cardiidae

27. Limnocardiidae

Superfamily 10. Tridacnacea

28. Tridacnidae .

CLASS I

RANGE OF THE PELECYPODA

507

Families.

1

o

a
.2

Devonian.
Carboniferous.

1

i

i

9

i
1

i
i

1

Superfamily 11. Isocardiacea

29. Isocardiidae .

30. Vesicomyaciidae

D. Teleodonta
Superfamily 12. Veneracea

31. Veneridae

32. Petricolidae .
Superfamily 13. Telliimcea

33. Tellinidae

34. Senielidae

35. Psammobiidae

36. Donacidae
Superfamily 14. Solenacea

37. Solenidae
Superfamily 15. Mactracea

38. Mactridae

39. Cardiliidae .

40. Mesodesmatidae

E. ASTHENODONTA

Superfamily 16. Myacea

41. Myacidae

42. Corbulidae

43. Saxica-vidae .

44. Gastrochaenidae .

Superfamily 17. Adesmacea

45. Pholadidae .

46. Teredinidae .

?

—

-

^__^

_

_

?..

1

?..

^^^

■■■"

—

?..

[The text for the preceding chapter on Pelecypods was revised for the first edition of this
work by Dr. William H. Dali, of the United States National Museum, and is here reproduced
with comparatively few changes proposed by himself and Dr. R. S. Bassler. — Editok.]

508 MOLLUSCA phylum vi

Class 2. SCAPHOPODA Bronn.i

(Cirrhohranchiata Blainville ; Solenoconchia Lacaze-Duthiers ;
Prosopocephala Stoliczka.)

Aquatic, marine^ hilaterally sijmmetrical moUusks, profeded hy an external,
tubulär, somewhat curved and fapering shell, open at both ends, the concave side
of which is dorsal ; the shell secreted by a mantle of the same shape, the larger,
anterior opening of which is provided with a- circidar muscidar thicJcening, the smaller
opening serving as outlet for organic waste and genital products. Mouth furnished
with a radula, borne on a cylindrical snout, and surrounded by a rosette of leaf-like
appendages ; a düster of numerous exsertile filaments (captacula) sprhiging from its
base. Otocysts present, but no eyes or tentacles. Foot rather long, conical, with
lateral lobes, and adjacent to the snout ventrally.

GUIs are wanting, the gener al surface assuming respiratory fundions. Liver
large, bilateral; intestine strongly folded, the anus ventral and rather anterior,
genital and kidney orifices adjacent to it. Heart rudimentary, with a single Chamber.
Nervous System with well-developed ganglia united by commissures. Reprodudion
without copulation, the sexual products voided through the right kidney.

Scaphopods are without exception marine, and for the most part inhabit
deep water. There are few littoral species. They live embedded in mud or
sand, with only the smaller end of the shell projecting above the surface.
Their food consists chiefly of Foraminifera and similar organisms, captured
by the filamentary captacula.

The tubulär, curved shell, open at both ends, is characteristic of the class,

the tubulär shells of certain Gastropods and Cephalopods being invariably

closed at the smaller end. Some tubicolous worms (Serpulidae) form a similar

shell, but it is composed of two layers only, instead of three as in Scaphopods,

the growth is more irregulär, and its microscopic structure very different.

The shell of Scaphopods increases by successive increments at the larger

end, and at the same time loses by wear and absorption at the

smaller end. The posterior slits or notches occurring in some

species are therefore formed by resorption of the previously

solid shell wall, and have a genesis whoUy different from the

slits or fissures of Pleurotomaria, Fissurella, and other Gastropods.

Various genera described as Scaphopods have since been

found to belong to the Serpulidae. Such are Pyrgopolon Montf.

(Fig. 837), from the Maestricht of Belgium, also known as

/g\ Entalium Defr., and Pharetrium König ; and Hamulus Morton

\>J^ {Falcula Conrad), of the American Cretaceous. The Cambrian

Fig. 837. geuus Spirodentolium Walcott, in which the shell has spiral

Pyrgopolon mosat Striae, is at present too imperfectlv known to lustify its refer-

Montf. UppsrCre- i.j.i.cii ^ iT»«-n

taceous; Belgium. ence to the bcaphopods, or even to the Mollusca.

1 Literature (see also, .linder the head of Mollusca, antea) : Deshayes, G. 1\, Anatomie et
monographie du genre Dentale. Mem. Soc. Hist. Nat. Paris, 1825, vol. in.— Lacaze-Duthiers, H. de,
Histoire de l'organisation et du doveloppement du Dentale. Ann. des Sei. Nat., 1856-57, ser. 4, vols.
vi., wm.—Sars, M., Om Siphonodentalium vitreiim, en ny Slaegt af Dentalidernes Familie.
Universitets-Prograra, Christiania, 1861. —Stoliczka, F., Palaeontologia Indica. Cretaceous Fauna
of Southern India, vol. ii., 18Q7-Q8.— Gardner, J. S., Ou the ^Cretaceous Dentaliidae. Quar.
Journ. Geol. Soc. London, 1878, vol. xxxiv. — Kovalevsky, A., I^tude sur rembryogenie, etc., dn
Dentale. Ann. Mus. Hist. Nat. Marseille, 1882-83. Zoologie, Mem. No. I.—Plate, L., Über

CLASS ir

SCAPHOPODA

509

Family 1. Dentaliidae Gray.

Scaphopoda havimj a conical foot ivith an encircling sheath expanded laterally and
interrupted dorsally. Shell tubulär, curved, regularly tapering throughout, not contracted
anteriorly, sculptured or smooth. Ordovician to Eecent.

DentaUum Linn. (Figs. 838, 839). Characters those of tlie family. Beginning
with a few species in the Ordovician, the number increases slowly until the Cretaceous.
A great acceleration then ensues, wliich continues to the present.
About 275 fossil and 150 recent species known. Various autliors liave *
attempted to subdivide tlie genus upon cliaracters of tlie posterior slit
of the Shell, but this has proved to vary widely even aniong individuals.
The following siibgenera based upon the system of sculpture and
shape of the tube appear more stable : —

DentaUum s. str. (Fig. 839). Shell with streng longitudinal ribs, apical
notch Short or wanting. Eocene to Recent.

Antalis Adams {Entalis, Gray non Sovvb, ;
Entaliopsis Newton and Harris) (Fig. 838,
A). Shell with longitudinal riblets or Striae
at least in the young ; apex with a short
ventral slit and a sheath. Cretaceous to
Recent.

HeteroscMsma Simr. With longitudinal
riblets and a dorsal slit. Recent.

Fissidentaliuvi Fischer. Large and solid,
with many longitudinal ribs or Striae ; a long
ventral slit usually present. Eocene to Re-
cent. Schizodentalium Sowb., in which the
slit is interrupted into a series of holes, is
probably a modificatiou of this group.

Gra-ptacme Pils, and Sharp. Surface with
close, fine longitudinal Striae near apex only,
or throughout. Tertiary and Recent.

La^videntalium Cossni. Arcuate, smooth,
with growth-lines only, circular in section,
apex simple or notched. Silurian ? to Recent.

Rhahdus Pils, and Sharp. Smooth, thin,
glossy, nearly straight, sub - circular in
section, apex entire. Recent.

Upisiphon Pils, and Sharp. Small and very slender, smooth, thin, the apex generally
with an inserted tube. Oligocene to Recent.

Compressidcns Pils, and Sharp. Small, much tapering, vertically compressed, smooth.
Eocene to Recent.

Lohantale Cossm. Shell compressed, with two internal longitudinal ribs. Eocene.

Fustiaria Stol. (Fig. 838, B, C). Shell with a very long and linear ventral cleft posteriorly.
Cretaceous to Recent.

Plagioglypta Pils, and Sharp. Surface with extremely oblique, sinuous, encircling Striae
{D. undulatum Münst.). Carboniferous to Trias.

A, D. (Antalis) kickxi Nyst. Oli-
gocene ; Weinheim, near Alzey. B,
D. {Fustiaria) lucida Desh. Eocene ;
Cuise la Mothe. i/i- 6', Posterior
portion of same enlarged, showing
slit.

Fio. 839.

DentaUum sex-
angulare Lam.
Pliocene ; Asti,
Italy.

Family 2. Siphonodentaliidae Simroth.

Scaphopoda having the foot either expanded distally in a symmetrical disk with
crenate continuous edge, or simple and vermiform, without developed lateral processes.
Shell small and generally smooth, often contracted towards the mouth. Cretaceous to
Recent.

den Boa und die Verwandtschaftsbeziehungen der Solenoconchen. Zool. Jahrb., Abteil, für Anat.
und Ontog., 1892, vol. v. [Biltliography, pp. 38i-dS6.]— Simroth, H., Mollusca, in Bronn's
Classen und Ordnungen des Tierreichs, vol. iii., 1893-95. — Pilsbry, H. A., and Sharp, B., Scapho-
poda, in Tryon and Pilsbry's Manual of Conchology, 1897-98, vol. xvii. — Bellini, li., Revisione
delle Dentaliidae dei terreni terziari e quaternari d' Italia. Palaeont. Ital., 1909, vol. xv.

510 MOLLUSCA phylum vi

Althougli tliis family is usually cliaracterised by a sinall smootli sliell, tlie essential
difference from tlie Dentaliidae is in the form of tlie foot. Typical forms of Gadulus

appear in the Cretaceous ; the remaining

A B c D genera are Tertiary and Recent.

^|(-v f / Entalina Monts. Shell Dentalium-WkQf

J|j||/S Ml largest at the apertnre, thence tapering to

/nlj^ fl ^C\ %S ff *^^ ^"^^^ ' ^^^^^g^y ribbed, and angular in

iM I ■ Im ^ tf section near tlie apex. Miocene to Recent.

^ /l ^(^ hi Siphonodentalium Sars (Pulsellitm Stol. ;

^^ SipJionentalis Sars). Shell an arcuate,

Fig. 840. sliglitly taperiiig tube, circular in section

A, Cadulus (Polyschides) denticulatus Desh. Cal- qj. nearly SO, and smooth externallv. Apex

caire Grossier ; Damery, near Epernay. B, Cadulus '' ^ • ^^ ^•^ • ^ ^^ f ^

{DiscUdßs) hifissuratus Desh. Calcaire Grossier; rather large, typicaliy sllt mto lobes, but

?oSN"oTteS,o.'''ASr.S™c. Tor.- sometime-s simple. Pliocene to Recent.

tonian ; Monte Gibbio, near Sassuolo, Italy. Cadulus Phil. {Gadus Desh. ; Gadüa

Gray; Heionyx Stimp.) (Fig. 840, G, D).
Shell tubulär, circular or oval in section, swollen near the middle or anteriorly, con-
tracting toward the apertnre. Cretaceous to Recent.

Typical forms with simple anal orifice appear first in the Cretaceous, Dischides,
Jeffr. (Fig. 840, B), with two lateral slits, and Polyschides Pils. (Fig. 840, Ä), with
several notches, appear in the Eocene. All continue to the present time.

Olass 3. AMPHINEURA von Ihering.i

Aquatic, marine^ hilaterally symmetrical moUusks, with the head partially or not
differentiated ; in form worm-like with a ventral groove or none, or oval, flatternd,
with a foot adapted for creeping. Nervous System consisting of an oesophageal ring
with ganglia and four longitudinal cords, two ventral and two lateral ; no cephalic
eyes, tentacles, or otocysts. Gillspaired or many, posterior or lateral ; mouth anterior,
usually with a radula ; anus posterior, median. External surface with a series of
eight shelly plates, or stiffened tvith calcareous spicules.

Order 1. APLACOPHORA von Ihering.

Body vermiform, with a ventral groove, the skin elsewhere heset with calcareous
spicules ; no dorsal shelly plates in the adult.

This is a degenei|ate group, represented in the Eecent fauna by about a
dozen genera belonging to two families — Chaetodermatidae and Neomeniidae.
Fossil remains are unknown.

Order 2. POLYPLACOPHORA Blainville. Chitons.

Amphineura protected by a dorsal series of eight shelly valves and an encircling
girdle ; with differentiated head, and a ventral sole or foot adapted to creeping ; gills

^ Literature : Ihering, H. v. , Vergleichende Anatomie des Nervensystems und Phylogenie der
Mollusken, 1877.— Dali, W. H., On the Genera of Chitons. Proc. U.S. Nat. Museum, 1881, vol.
iv. — Hubrecht, A. A. W., A Contribution to the Morphology of the Amphineura. Quar. Journ.
Microscop. Soc, 1882, vol. xxii. [Bibliography, pp. 226, 227 .}— Hochebrune, A. T. de, Mono-
graphie des especes fossiles appartenant ä la classe des Polyplaxiphores. Ann. Sei. Geol. 1883, vol.
xiv. — Pruvot, Q., Sur l'organisation de quelques Neomeniens des cotes de France. Arch. Zool.
Exper. et Gener. [2], 1891, vol. ix. [Bibliography, pp. 702, 703.]— PiMry, H. A., Monograph of
the Polyplacophora. In Tryon and Pilsbry's Manual of Conchology, vols. xiv. and xv., 1892-93.
— Broili, F., Die Fauna der Pachycardientuffe der Seiser Alp. II. Scaphopoden und Gastropoden.
Palaeoutogr., 1907, vol. liv.

cLAss III AMPHINEURA 511

numerous, occupying the groove hetween foot and girdle ; radula present, heterodont ;
sexes separate.

The exteriial covering in the Polyplacophora, or Chitons, consists of eight
valves bound together by an encircling flexible band called the girdle. The
anterior or head-plate (Fig. 841, A, below) is invariably semicircular, with the
apex or mucro at the middle of the straight margin ; the six succeeding plates
are generally Square (Fig. 842, below), with the apex posterior on the median
line ; and the posterior or tail-valve (Fig. 841, B) is semicircular or subcircular,
with apex varying in position from in front of the middle to the hind margin.
All of the plates are composed of two layers — an outer porous layer, the
tegmentum, and an inner porcellanous one, the articulamentum. In most of the
lower Chitons these layers are coextensive and have smooth edges; but in
the higher forms the articulamentum projects beyond the outer layer into the
substance of the girdle, in which it is firmly inserted. These projections at
the outer or peripheral margin are termed Insertion plates. They are generally
slit or notched into so-called " teeth," which may be either smooth and sharp
along the edge, or crenulated (pectinated). Insertion plates serve the function
of binding the valves firmly to the girdle.

The anterior margin of each valve except the first one invariably shows
two projections of the articulamentum called sutural laminae (Figs. 841, B,
842), which pass under the rear margin of the next anterior valve, thus pre-
venting vertical displacement of the series. The tegmentum is traversed by
a multitude of fine canals which terminate at the surface in minute sense
Organs. The cavities of the latter in dry or fossil valves are visible as fine
quincuncial punctations. In the highest Chitons a certain number of these
sense organs have become enlarged and modified into eyes, easily recognised
as pigmented dots in recent, and small pits in fossil specimens.

Polyplacophora make their appearance as early as the Ordovician ] they are
rare in the > Silurian and Devonian, but somewhat more abundant in the
Carboniferous. None of the Paleozoic genera is known to continue into the
Mesozoic, but the Eoplacophora are replaced by types more related to modern
Chitons (^Mesoplacophora). Members of the most specialised suborder, Teleo-
placophora, first appear in the Eocene, although they doubtless arose earlier.
About twenty Paleozoic, five or six Mesozoic, and fifty Tertiary species have
been described. Recent forms number several hundreds. A good many
species supposed to be Chitons have been based upon barnacle valves, fish
scales, and other fragments. The recently described Duslia insignis Jahn is
apparently a Crustacean ; certainly not a member of the Polyplacophora.

Three suborders are recognised, according as the insertion plates are
absent, or if present, unslit (Eoplacophora) ; developed, smooth, and slit into
teeth (Mesoplacophora) ; or both slit and pectinated (Teleoplacophora).

Suborder A. EOPLACOPHORA Pilsbry.

Polyplacophora with the tegmentum coextensive with the articulamentum^ or with the
latter projecting in smooth, unslit insertion plates ; gills posterior.

Family 1. Gryphochitonidae Pilsbry.

Insertion plates ahsent, sutural laminae small ; one or both end-valves with the
terminal margins elevated ; form elongated and narrow. Paleozoic.

512

MOLLUSCA

PHYLUM VI

Helminthochiton Salter. Valves tliin, mucro subcentral, low; end-valves not
elevated terniinally. Silurian.

Priscochiton Billings. Similar in the non-sinnous liead-valve, biit beaks of tlie
valves greatly produced backwards. Ordovician.

Gryphochiton Gray (Fig. 841). Elongated, with small beaks and very small sntural
laminae ; terminal margins of end-valves strongly elevated ; tail-valve witli low,
decurved mucro behind the middle, Carboniferous.

Pterochiton Carp. (Änthracochiton Rochebr,). Elon-
gated, the valves strongly beaked and laterally excavated ;
tail-valve with depressed post- median mucro and no
posterior sinus, anterior valve with the front margin
elevated, sutural laminae large. Carboniferous.

Gymatochiton Dali (Protalochiton Rochebr.). Oval,
elevated and granulär, the valves short and wide, with
small, low sutural laminae and distinct lateral areas ;
mucro of posterior valve post-median, elevated. Permian.
Proholaeum Carp. Elongated, elevated ; valves very
strongly beaked, the pleura projecting beyond the jugal
tract ; anterior valve sinuate in front, posterior valve
unknown. Devonian.

Ghonechiton Carp. Median valves as in Gryphochiton ;

Fig. 841.

Gryphochiton priscus (Münst.).
Carboniferous ; Tournay, Belgium.
J, Anterior and threeintermediate posterior valve with the mucro
valves. B, Posterior valve, ventral ^ , • y^ , 7

and dorsal aspects. Vi- thrown backward, as m Cryptoptax.

Carboniferous.

Loricites Carp. Somewhat like the Recent Lorica, Init

without Insertion plates. Carboniferous.

Family 2. Lepidopleuridae Pilsbry.

Fig. 842.

Lepidopleurus
(Sandb.). Miocene ; Wald-
böckelheim, near Creuz-
nach, Germany. A median
and a posterior valve. '-^/i.

Insertion plates ahsent, or present and unslit ; end-valves
with the terminal margins never elevated; form oval or oblong.
Tertiary and Recent.

Lepidopleurus Risso {Leptochiton Gray) (Fig. 842). Small, oval ; Insertion plates
entirely absent, sutural laminae small ; girdle minutely scaly or chaffy. Eocene to
Recent.

Hanleyia Gray. Like the last, except that the anterior valve has an unslit Insertion
plate, and the girdle is spiculose. Champlain to Recent.

Hemiarthrum Carp. Both anterior and posterior valves with smooth unslit
Insertion plates, the others lacking them ; girdle downy, with small sutural pores.
Rec^int.

Ghoriplax Pils. Valves partly immersed in the minutely granulöse girdle, all with
thin, smooth Insertion plates. Recent.

Suborder B. MESOPLACOPHORA Pilsbry.

Insertion plates developed, slit, not vertically grooved or pectinated outside.

Family 1. Ischnochitonidae Pilsbry.

Valves having the inner layer well covered hy the outer. Surface of intermediate
valves divided into lateral and central areas hy a diagonal rib (pften indistinct), extending
from the beah to each anterior outer angle of tegmentum ; or when this is not clearly the
case, the posterior valve has a crescentic series of well-developed teeth ; all valves with
slits. Eocene to Recent.

CLASs III AMPHINEURA 513

Two subdivisions of this family are recognised, according as tlie anterior and side
slits correspond in position witli ribs on the extenial surface or not. Among the
genera included under tlie first section {Callistoplacinae) may be mentioned the follow-
ing : — CallistocJiiton, Nuttalina, and Callistoplax Carpenter ; Graspedochiton Shuttle-
worth ; and Geratozona Dali. Representatives of the second subfamily {Ischnochitoninae)
are as foUows : — Schizoplax Dali ; Tonicella, Trachydermon, and Dinoplax Carpenter ;
Gallochiton and Ischnochiton Gray ; Ghaetopleura Shuttleworth.

Family 2. Mopaliidae Pilsbry.

Valves externally divided tijpically into central and lateral areas, the posterior valve
with a sinus hehind, one or two slits pn each side of it or none ; intermediate valves each
with a Single slit ; teeth smooth, sharp, often with thickened edges on the outside ; girdle
more or less hairy. Pleistocene and Recent.

This family comprises the following genera : — Mopalia and Plaxiyhora Gray
Placiphorella Carpenter ; and Placophoropsis Pilsbry.

Family 3. Acanthochitidae Pilsbry.

Valves more or less immersed in the smooth or hairy girdle, the tegmentum therefore
much smaller than the articulamentum ; the exposed surface divided into a narrow dorsal
and wide latero-pleural areas, the latter formed hy the union of the lateral and pleural
areas of typical Ghitons. Insertion teeth sharp, rarely smooth; posterior valve either
slit like the head-valve, or having a posterior sinus ; head^valve usually with five slits,
intermediate valves singly slit Body never vermiform. Pliocene to Recent.

The following representatives are to be cited : — Acanthochites Risso ; Spongiochiton
Carpenter ; Katharina and Amicula Gray ; Gryptochiton Midd. and Gray.

Family 4. Oryptoplacidae DalL

Elongated or vermiform Ghitons with small valves; insertion and sutural plates
strongly drawn forward, sharp and smooth ; the anterior valve with three to flve slits, the
others with one slit on each side, or none; tail-valve having the mucro far posterior,
insertion plate continuous hehind ; girdle very thick and wide.

This is a highly specialised branch of a low groiip of Chitons, unknown in the
fossil State. Gryptoplax Blainville {Ghitonellus Lam.), and Ghoneplax Carpenter, are
examples.

Suborder C. TELEOPLACOPHORA Pilsbry.

All valves, or the first seven, with insertion plates cut into teeth hy slits ; the teeth
sharply sculptured (^ectinated) outside hy fine vertical grooves.

Family 1. Ohitonidae Pilsbry.
Gharacters those of the suhorder. Tertiary and Recent.

The family is illustrated by the following genera, of which only the first two occur in
the fossil condition : — Ghiton Linne ; Trachyodon Dali ; Eudoxochiton Shuttleworth ;
Tonicia, Schizochiton, Enoplochiton and Onithochiton Gray ; Acanthopleura Guilding ;
Lorica Adams ; Loricella and Liolophura Pilsbry.

VOL. I 2 L

514 MOLLUSCA phylum vi

Olass 4. GASTROPODA. Snails/

MoUusks with distind head, soled or more rarely fin-like foot, and undivided
mantle, which latter usually secretes a univalve, spirally wound, or saucer-shaped shell

Gastropods difFer from Pelecypods in having a more or less distinctly
marked head, which usually bears tentacles, eyes, and ears, and contains a
large cerebral ganglion. The ventral aspect of the creature is commonly
formed by a broad foot ; but in the Heteropoda this is modified into a vertical,
laterally compressed fin ; and in the Pteropoda it is represented by two wing-
like swimming membranes near the head. The base of the foot is sometimes

^ Literature (see also under head of Mollusca, antea) : Ihering, H. v., Vergleichende Anatomie
des Nervensystems und Phylogenie der Mollusken. Leipsic, 1877. — Koken, K, Über die Ent-
wickehmg der Gastropoden vom Kambrium bis zur Trias. Neues Jahrb. f. Mineral., 1889, supplem.
vol. vi. — Quenstedt, F. A., Petrefaktenkunde Deutschlands. Gastropoden, vol. vi., 1881. — Simroth,
H., Gastropoda, in Bronn's Klassen und Ordnungen des Tierreichs, 1896. — Troschel, H., Das
Gebiss der Schnecken, zur Begründung einer natürlichen Classification, vols. i., ii. Berlin, 1856-78.

A. On Paleozoic Forms. — Billings, E., Palaeozoic Fossils. Geol. Surv. Canada, 1865-74, vols. i.,
ii. — JaTcowlew, F., Die Fauna einiger oberpaläozoischer Ablagerungen Russlands. Mem. Comite
Geol., 1899, vol. xv., No. 3. — Koken, E., Die Gastropoden des baltischen Untersilurs. Bull. Acad.
Imp. Sei. St. Petersb., 1897, vol. vii., No. 2. — Koninck, L. G. de, Faune du calcaire carbonifere
de la Belgique. Ann. Mus. d'Hist. Nat. Belg., 1882-85, vol. vi. — LindstrUvi, G., On the Silurian
Gastropoda and Pteropoda of Gotland. K. Svensk. Vetensk. Akad. Handl., 1884, vol. xix.
— Ferner, J., Gasteropodes, in Barrande's Systeme silurien du centre de la Boheme, vol. iv.
Prague, 1903-7. — Salter, J. W., Catalogue of the collection of Cambrian and Silurian fossils in
the Museum of Cambridge, 1873. — Spitz, Ä., Die Gastropoden des karnischen Unterdevon. Beiträge
Pal. und Geol. Österr.-Ung., etc., 1907, vol. xx. — Ulrich, E. 0., and Scoßeld, W., The Lower
Silurian Gastropods of Minnesota. Rept. Geol. and Nat. Hist. Surv. Minn., 1897, vol. iii., pt. 2.

B. On Mesozoic Forms. — Ahlburg, J., Die Trias im s. Oberschlesien. Abhandl. Preuss. Geol.
Landesanst. u. Bergakad., 1906, n.s., Heft 50. — Böhm, J., Die Gastropoden des Marmolatakalkes.
Paläontogr., 1895, vol. xlii. — BrUsamlen, R., Beitrag zur Kenntnis der Gastropoden des schwäbischen
Jura. Paläontogr., 1909, vol. Ivi. — Deninger, K., Die Gastropoden der sächsischen Kreideformation.
Beiträge Pal. und Geol. Österr.-Ung., etc., 1905, vol. xviii. — Haberle, D., Paläontologische Unter-
suchungen triadischer Gastropoden aus dem Gebiet von Predazzo. Verhandl. Naturh. Med. Vereins.
Heidelberg, 1908, n.s., vol. ix. — Hudleston, W. H., A Monograph of the British Jurassic Gasteropoda.
Paläontogr. Soc, 1887-94. — Kaunhoven, F., Die Gastropoden der Mästricher Kreide. Paläont.
Abhandl., 1897, n.s., vol. iv. (viii.). — Koken, E., Die Gastropoden der Trias um Hallstadt. Jahrb.
Geol. Reichs- Anst. Wien, 1897, vol. xlvi., and Abhandl., vol. xvii. — Morris, J., and Lycett, J.,
Mollusca from the Great Oolite : Univalves. Palaeontogr. Soc, 1850. — d'Orhlgny, A., Paleontologie
fran9aise. Terrains jurassiques ii. et iii., 1850-82. Terrains cretaces ii., 1842-3. — IHcard, E.,
Beitrag zur Kenntnis der Glossophoren der mitteldeutschen Trias. Jahrb. Preuss. Landesanst.,
1901, vol. XXV. — Stoliczka, F., Cretaceous Fauna of Southern India. Gastropoda, vol. ii. Mem.
Geol. Surv. East India, 1868. — Zittel, K. A., Die Gastropoden der Stramberger Schichten. Mitt.
Mus. Bayer. Staates, 1873, vol. ii., pt. iii.

C. On Tertiary Forms. — Beyrich, E., Die Conchylien des norddeutschen Tertiärgebirges.
Zeitschr. Deutsch. Geol. Ges., 1853-6, vols. v., vi., viii. — Gossmann, M., Mollusques eoceniques
de la Loire-Inferieure, i. and ii. Bull. Soc. Sei. Nat. Ouest Nantes, vols. vii.-ix., 1895-1901.
Contribution ä la paleontologie fran9aise des terrains jurassiques. Mem. Soc. Gool. France, 1895,
1898, Mem. Nos. 14 and 19. Essais de paleontologie comparee, i.-iv. Paris, 1895-1904. — Gossmann,
M., and Pissarro, G., Faune eocenique du Cotentin. Bull. Soc. Geol. Normandie, 1900-2, vols. xix.-
xxi. — Dali, W. H., Contributions to the Tertiary Fauna of Florida. Trans. Wagner Free Inst. Sei.,
1895-97, vols. iii., v. — Harris, G. F., The Australasian Tertiary Mollusca. Cat. Tert. Mollusca
Brit. Mus., pt. i., 1897. — Hoernes, R., and Auinger, M., Die Gastropoden der Meeresablagerungen
der ersten und zweiten Mediterranstufe. Vienna, 1879-91. — Martin, K., Die Fossilien von Java.
Samml. Geol. Reichsmus. Leiden, 1895-99, n.s., vol. i., pts. 2-10. — Newton, R. B., Systematic List
of British Oligocene and Eocene Mollusca, 1891. — Philippi, R. A., Die tertiären und quartiären
Versteinerungen Chiles. LeipsiQ, 1887. — Sandberger, F., Land- und Süsswasserconchylien der
Vorwelt. Wiesbaden, 1870. — Vinassa de Regny, P. E., Synopsis dei molluschi terziari delle Alpe
venete. Palaeontogr. Italica, 1896-97, vols. i., ii. — Wood, E., The Phylogeny of certain Cerithiidae.
Ann. N.Y. Acad, Sei., 1910, vol. xx. — Grabau, A. W., Studies of Gastropoda. Amer. Nat.,
1902-3, vols. xxxvi., xxxvii.— Phylogeny of Fusus. Smiths. Mise. Coli., 1904.

CLASs IV ' GASTKOPODA , 515

of considerable size, and in some forms (Strombidae) the animal is enabled to
spring quite a distance by contracting the foot. The mantle lobe is elevated
along the back like a hood, extending as far as the head, and usually secretes
a shell from its outer surface. The shell (which may be wanting or obsoles-
cent in the adult) Covers the intestinal sac and lung-cavity, and usually permits
of retraction into it of the entire body of the animal. Body and shell are
united by muscular attachment ; in spiral shells the muscle is fastened to the
columella, but in bowl-shaped forms to the inner surface of the shell.

The nervous System consists of two cerebral ganglia, the paired pedal and
visceral ganglia, and two or three additional pairs, all of which are united by
commissures. A complete crossing of the commissures of the visceral ganglia
sometimes takes place (Chiastoneura), but in other forms they run parallel
(Orthoneura).

The peculiar armature of the mouth, although developed in all classes of
Mollusks except Pelecypods, is especially characteristic of Gastropods. This
consists of one or more horny plates on the anterior upper margin of the
Oesophagus, opposed to which is a chitinous grating, strap or radula, resting
upon the tongue or odontophore. The tongue itself is merely a swelling at
the bottom of the buccal cavity. The radula is usually quite long, and is
beset with innumerable small teeth or hooks, placed in transverse and
longitudinal rows, and exceedingly constant in form throughout the several
groups. The characters of the radula among the difFerent groups were
therefore advantageously employed by Lov^n and Troschel as a basis of
Classification.

The Oesophagus conducts into a long, coiled, intestinal canal, which is
surrounded by a large liver, the kidneys, and numerous glands. The intestine
ends in an anal opening placed anteriorly. The heart, as a rule, has one
auricle (Montocardia), more rarely two (Diotocardia), and serves as a central
organ for the supply of a much branched System of blood-vessels. When the
gills or lungs are placed in front of the heart (Prosobranchia, Pulmonata), the
auricles are anterior to the ventricle ; but when placed behind the heart
(Opisthobranchia, Fteropoda) the auricle is posterior.

Only a few Gastropods breathe through the general surface of the body,
and are without distinct organs of respiration ; the vast majority possess gills
or lungs. The gills are lamellar or tuft-like, sometimes branched or feathered
lobes of the integument, and are usually placed in the gill-cavity below the
mantle ; more rarely they project freely on the back or at the sides. Only
exceptionally are they present in large numbers and symmetrically developed ;
and when so disposed they are always secondary structures not homologous
with the normal ctenidia. Typically there are two gills, but the left usually
becomes completely atrophied, and the right takes up a median position, con-
sequent upon the torsion of the body, or even migrates over to the left side.
Air-breathing snails have the gills replaced by a sac-like cavity, the lung
occupying the place of the gill-cavity. The walls of this respiratory cavity
are covered with a finely branched network of blood-vessels. The Arnpul-
lariidae and Siphonariidae possess both gills and lungs. The opening of the
respiratory cavity ns reduced to a round or crescentic aperture, called the
breathing pore. The sides of this pore, in operculated snails, are often pro-
duced outwards, so as to form a closed or cleft tube, corresponding with which
there is frequently a canal-like process of the shell.

516 . MOLLUSCA ' phylum vi

Gastropods are remarkable for the extreme differentiation of their repro-
ductive Organs. The sexes are distinct in the Prosobranchia and Heteropoda,
but united in the Opisthohranchiata, Pteropoda and Pulmonata. The ovarian
and seminal ducts of hermaphrodites sometimes open into a common cloaca,
or they may terminate in separate openings.

The shell, as has already been remarked, is secreted by the mantle, and is
limited in form and size by the configuration of the intestinal sac. It is
composed of a chitinous substance {conchioUn) infiltrated with lime carbonate,
or exceptionally with sulphate of lime in small quantities. Shell characters
are of great importance in distinguishing genera and species, but their value
in classifying larger groups is comparatively slight, owing to the fact that
very similar shells are often developed among forms which difFer widely in
their general Organisation. Two forms of shell-habit occur, the symmetrical
and the spiral. The first are flat, conical or saucer-shaped, and characterise
only a few groups (Cyclobranchia, Aspidohranchia, Pulmonata). Transition
forms between the symmetrical and spiral are to be observed in conical shells
with slightly inrolled beaks. Exceptional forms of the spiral shell are seen
in Vermetus, which is irregularly coiled, and in Planorhis, Bellerophon and
Atlanta, coiled in one plane (discoidal). Usually the shell forms a screw-like
spiral, and rests upon the back of the creature in such a way that the apex is
directed upward and backward, the aperture f orward and downward. Holding
the shell upright so that the apex is above, and the aperture below, facing
the observer, it is said to be right-handed or dextral when the opening is on
the right side, and left-handed or sinistral when on the left side. By far the
larger number of Gastropods are dextral ; but a few (Clausilia, Physa, Spirialis)
are normally sinistral. Right-handed individuals of normally left-handed
genera, as well as pathologic sinistral individuals of normally right-handed
forms, are occasionally met with.

In drawing and describing Gastropod shells, the apex is ordinarily directed
upward, so that the right- or left-handedness may be seen at a glance. It is
also customary to employ the terms above and below in the same sense as
posterior and anterior. The height or length of the shell is measured by a
line drawn from the apex to the lower margin of the aperture.

The shell is to be considered as a more or less rapidly wädening cone,
which is wound either around an axial pillar, called the columella, or about a
central tubulär cavity. Each coil of the tube is termed a whorl, and all the
whorls except the last one form together the spire. The last or body whorl
is often very much larger than the preceding ; its lower, sometimes flattened
surface is called the hase. As a rulö, the whorls are in contact with each
other, each in succession either partly or entirely covering the preceding ; but
in rare cases they form a loose spiral, in which the whorls are separated from
one another. The spire is said to be convolute when the later whorls
entirely conceal the earlier ones, as in Cypraea. The line between two con-
tiguous whorls is known as the suture. According to the manner of inrolling,
various shell contours are produced, requiring numerous descriptive names,
such as conical, auriform, turbinate, fusiform, cylindrical, spherical, oval,
pyramidal, etc.

When the inner parts of the whorls coalesce to form a columella, the shell
is said to be imperforate ; it is perforate when they do not so coalesce, but
leave a central tubulär cavity instead. The opening of this Perforation below,

CLASS IV

GASTROPODA

517

Apex

Siiture

in the centre of the base, is designated the umbilicus. A true ümbilicus
reaches to the apex of the shell ; when confined to the last whorl only, it is
called a false umbilicus. An umbilical fissure is sometimes produced through
a partial covering of the umbilicus by the reflected inner lip, er by a shelly
growth termed the callus.

The aperture is variable in form, being most commonly oval, rounded,
crescentic or half-round, but is sometimes contracted or even fissure-like. Its
margin is called the peristome, the outer partof which forms the outer lip, and
the part next the columella the inner lip. Some shells have a continuous,
uninterrupted peristome, but as a rule the inner and outer lips are discon-
nected. The aperture is said to be entire when
rounded anteriorly (inferiorly), as in the Holosto-
mata \ it is channelled when a basal notch or
canal, caused by an inbending of the margin
next the base of the columella, is developed.
This anterior canal serves for the lodgment of
the siphon, as the tube is called which conducts
water to the gills ; it may be either straight or
recurved, and in the Siphonostomata it is greatly
produced, sometimes even exceeding the aper-
ture in length. The outer lip may be entire or
incised, thin and sharp or thickened, curved
outward (reflected) or inward (inflected), even
or crenulated, or it may be produced into alar
or finger-like processes. It is sometimes chan-
nelled by a canal at the posterior border, in
which the anal or excurrent canal is placed.
The Upper or posterior portion of the inner
margin is commonly designated as the parietal
wall, in contradistinction from the lower or
columellar portion. The inner lip is formed
either by the wall of the penultimate whorl, or
by a calcareous callus ; like the outer lip and
columella, it may bear spiral folds, which in
some cases extend backward as far as the
apex (Fig. 843), but sometimes are progres-
sively absorbed internally.

The external ornamentation usually consists of impressed lines or grooves,
or of elevated ridges, ribs, folds, nodes, spines and the like. The markings
are called spiral when they run parallel with the suture, and axial or
longitudinal when they meet the suture at right angles or obliquely. Many
Gastropods are brilliantly coloured ; some have a smooth or rough, and others
a velvety or hairy epidermis. The fossilisation process is usually destructive
not only of the epidermis, but of the coloration as well.

The essential constituent of univalve shells is aragonite, which usually
forms a homogeneous, porcelain-like layer. Many families have in addition
to this an inner nacreous layer, which is made up of alternating strata of
conchiolin and calcium carbonate, running parallel with the inner surface of
the shell. The porcellanous material is composed of three distinct layers,
each of which is made up of thin laminae, and the laminae in turn of very

Canal

Fio. 843.

Mitra episcojmlis Linn. View of shell
sawed through longitudinally, showing
columella with folds.

518 MOLLUSCA phylüm vi

small oblique prisms. The laminae of the middle layer are disposed at right
angles to those of the adjacent layers.

Many Gastropods have a calcareous or horny plate, called the oj)erculum,
attached to the posterior part of the foot, and serving to close the aperture
more or less completely when the animal withdraws into its shell. Being
most commonly of corneous nature, it is seldom preserved fossil ; sometimes,
however, it is calcareous, and may attain considerable size and thickness. On
the outer surface it may be smooth, furrowed, granulated or covered with
excrescences. The nucleus or initial point of growth is sometimes central, or
may be eccentric or even marginal in position ; it may be surrounded by con-
centric markings, or form the origin of a spiral consisting of few (paucispiral)
or many (multispiral) whorls. Certain Solariidae have a conical operculum,
which is covered externally with numerous spiral lamellae.

The embryonic stages of Gastropods are usually completed in the egg-
capsule. Early in its development the embryo forms a small shell, the proto-
conchf which consists sometimes of several whorls, and not infrequently difFers
in form from the shell of the adult. The protoconch remains attached
to the apex for a time, in the form of a small glistening knob, or a short
smooth spire, which occasionally Stands at an angle to the rest of the shell, or
is even twisted in a contrary direction (heterostrophic). Should the protoconch
become decollated, a small calcareous plate closes over the apex of the spire.

All branchiate Gastropods are aqueous in habitat, but there are some
forms having a lung-cavity which live permanently in fresh water (Lymnaeidae),
and others which are exclusively marine (Siphonariidae). The greater number
of Gastropods, especially the large and solid forms, frequent the coast-line,
and inhabit comparatively shallow water. Some become attached to rocks
and plants, others burrow in sand or mud. A great reduction in the Gastropod
fauna is noticed at a depth of between 70 and 100 metres, but many genera
(Pleurotoma, Fusus, Natica, Odostomia, Eulima, Scissurella, Turbo, Cylichna,
Tornaüna, Adaeon, etc.) persist into the greatest depths yet explored. Most
marine Gastropods are killed by removal into fresh water ; a few genera,
however, are able to maintain their existence in brackish or in fresh water
(Cerithium, Littorina, Rissoa, Trochus, Purpura, etc.). On the other band, many
fresh-water forms (Melania, Melanopsis, Neritina, AmpuUaria, Lymnaea, Planorhis)
can survive in brackish or even strong salt water. There are also large
numbers of terrestrial Gastropods, especially in tropical regions.

Most Gastropods are herbivorous, but a few subsist upon living or decom-
posed animal food. Many genera (Natica, Buccinum, Murex) perforate the
Shells of other MoUusks with their radula, and extract the contents.

Classification. — Ordinal divisions have been based since the time of Cuvier
and Milne Edwards upon the respiratory organs, and the structure of the foot
(whether adapted for swimming or crawling). The reproductive organs, and
the structure of the heart and nervous System, are also of prime importance.
For separating smaller groups, shell characters and the radula are largely
employed. Gastropods may be divided into two subclasses : Stre^itoneura,
with the Orders Ctenohranchiata and Aspidohranchia ; and Euthyneura, with
the Orders Opisthohranchia and Pulmonata.

CLASS IV GASTROPODA 519

Subclass 1. STREPTONEURA Spengel.

{Prosohranchia Cuvier; Cochlides von Ihering.)

Gastropods in which the visceral commissures are crossed, producing an S-shaped
loop ; sesces separate ; heart behind the gilt ; a shell almost always developed, and
with few exceptions provided with an operculum.

The Streptoneura, or Prosobranchiates as they are often called, constitute by
far the largest group of Gastropods, and comprise at least 20,000 living and
fossil species. The shell is usually spiral, more rarely symmetrical, saucer-
shaped or conical. The intestinal sac is twisted from left to right, so that
the anal opening is placed on the right side near the head, and the organs
normally belonging to the right side (kidneys and gills) migrate over to the
left. As a rule, one only (the right) of the lamellar gills is fully developed,
but in some cases the two are of equal size. The gill veins enter anteriorly
into the single or double-auricled heart.

The large number of Prosobranchiates have been variously classified.
Cuvier, Milne Edwards, and most of the older zoologists laid emphasis upon
the number and formation of the gills ; Troschel and Loven upon the char-
acters of the radula ; von Ihering upon the nervous system ; Mörch and more
recently Perrier and Bouvier upon the structure of the heart. As none of
these characters leave a marked impress upon the shell, they are without
practical value in Paleontology. Nevertheless, the two Orders Aspidobranchia
and Ctenobranchia form natural groups, and are recognised, albeit under
difFerent names, in all classificatory Systems.

Order 1. ASPIDOBRANCHIA Schweigger.

{Gyclohranchia and Scutihranchia Cuvier.)

Nervous system not much concentrated anteriorly ; a penis generally ahsent ; radula
multiserial.

This group includes most Paleozoic Gastropods, and is regarded as the most
primitive expression of the class. The nervous system and radula are of low, decidedly
generalised type, and in some families two symmetrical ctenidia or gills are developed,
as in Pelecypods.

Suborder A. DOCOGLOSSA Troschel. Limpets.
{Gyclohranchia pars Cuvier ; Heterocardia Perrier.)

Symmetricalj with conic or howl-shaped non-spiral shells, or with spiral shells coiled
in the same plane ; operculum wanting. Organs of respiration rqnesented either hy a
ring of laminae {secondary or pallial gills) heneath the mantle margin, or by a comh-
shaped true gill in front^ anterior to the heart, or by hoth true and secondary gills.
Tongue set with peculiar modified teeth. Heart with one auricle. Marine. Cambrian
to Recent.

The impression of the adductor muscle in the shell cavity is horseslioe-shaped,
open in front. In the family Tryblidiidae, the horse-shoe is broken into numerous
separate impressions. The three families Patellidae, Acmaeidae and Lepetidae have
the impression uninterrupted, and are distinguished by the structure of the gills. The

520 MOLLUSCA phtlüm vi

Shells themselves exhibit little Variation in form, and hence tlieir generic and even
family affinities are almost always doubtful in tlie fossil state. About 400 Eecent
species of limpets are known ; these are almost exclusively shallow water inhabitants,
and subsist on algae. Fossil forms are uncommon.

In tlris very primitive groiip two divisions have been proposed by Ulrich and
Scofield : (1) the Patellacea, which embraces the first tliree families noted below ; and
(2) the Bellerophontacea, including the remaining five families. The latter group by
Meek was regarded as involute Fissureil idae, a view which is not withoiit plausibility.

Family 1. Patellidae Carpenter.

Patella Linn. Cup-shaped, round or oval, depressed conical, with sub-central or
eccentric apex. Surface usually with radiating ribs or Striae. Silurian to Eecent.

Helcion Montf. Differs in having the beak strongly recurved anteriorly. Eocene
to Eecent.

Helcioniscus Dali ; Nacella Schum. Eecent.

Family 2. Acmaeidae Dali.

Acmaea Eschscholtz {Tectura auct.) (Fig. 844, B). Like Patella, but shell having
generally a differentiated marginal band inside ; externally smooth, finely Stria ted, or
radially ribbed. Beak anterior to the middle. Silurian to Eecent. Lottia Gray is
closely allied.

Scuiria Gray (Fig. 844, G). High conical, smooth, with sub-central beak. Jura
to Eecent.

A B C D

844.

A, Archinacella cingulata Vir. Ordovician ; Kentucky. B, Acmaea raincourti Deah. Eocene; Auvers, near
Paris. C, Scurria nitida Deslongcli. Upper Jura ; Langrune, Calvados, l/i. D, Helcionopsis striata Ulr.
Ordovician ; Kentucky.

Metoptoma Phil. Depressed conical with sub-central beak. Posterior side exca-
vated. Silurian to Carboniferous.

Lepetopsis Whitf. Silurian to Carboniferous.

The genera, Palaeacmaea Hall; Archinacella Ulrich and Scofield (Fig. 844,^); and
Scenella Billings are the oldest representatives of the Docoglossa. They are small,
smooth or radially ornamented, and scarcely to be distinguished from Acmaea.
Lepeta Gray and Lepetella Verrill are small simple limpets of the Eecent and late
Tertiary, with degenerate, aborted gills. They form the family Lepetidae. *

Helcionopsis Ulr. and Scof. (Fig. 844, i>), and Gonchopeltis Walcott, from the
Ordovician of North America, are doubtfully referred to this vicinity.

Family 3. Tryblidiidae Pilsbry.
Limpets with the muscle scar broken into numerous separate impressions. Silurian.

CLASS IV

GASTROPODA

Tryhlidium Lindströni (Fig. 845). Shell depressed, very thick, oval, with anterior
beak ; ornamented externally with eoiicentric lamellae. Six pairs of miiscle scars
arranged in tlie form of a horse-shoe. Ordovician anid Silurian.

Family 4. Cyrtolitidae Ulrich and
Scofield.

Symmetrical, involute shells with two or
three volutions, barely in contact, sharply
angular dorsally ; aperture not expanded, the
sinus V-shaped, never deep, sometimes want-
ing ; slit absent ; surface reticulate. Ordo-
vician and Silurian.

Cyrtolites Conrad (Fig. 846, Ä, B). Shell
carinated on the back and often on . the
sides, giving a sub-quadrate cross section ; no
slit band.

Gyrtolitina Ulrich. Small thin shells
with a slit band.

Microceras Hall.

Fig. 845.

Tryhlidiuvi reticulatum Lindström. Silurian ;
Gotland. A, Internal, and B, external aspect
(after Lindström).

Fig. 846.

A, B, Cyrtolites oniatus Conrad. Ordovician of Boonville, New York, and Cincinnati, Ohio. C-E, Sinuites
cancellatus (Hall). Ordovician of Minnesota.

Family 5. Sinuitidae, novum. {Protowarthiidae Ulr. and Scof.).

Symmetrical, involute shells with aperture not dhrwptly expanded; outer lip and
of growth with a broad or narrow dorsal sinus ; slit and band wanting.

Sinuites Koken {Protowarthia U. and S.) (Fig. 846, G-E). Aperture large with
outer lip bilobate ; dorsum convex ; umbilicus closed. Ordovician to Devonian.
Bucanella Meek. Dorsum of shell trilobate ; umbilicus large. Silurian.
Owenella Ulr. and Scof. Cambrian.

Family 6. Bucaniidae Ulrich and Scofield.

Symmetrical, involute shells with rather numerous whorls merely in contact or
embracing slightly, all visible in the umbilicus ; aperture often expanded abriiptly ; dorsal
slit band distinct with the slit long and narrow; surface with transverse lamellae or
lines usually crossed by short ribs. Ordovician to Devonian.

Bucania Hall (Fig. 847, A, B). Shell of three to five depressed volutions coiled
in a plane, generally with a wide umbilicus and with aperture never abruptly
expanded. Ordovician and Silurian.

Salpingostoma Eoemer (Fig. 847, G). Aperture abruptly expanded, trumpet-like ;
outer half of last whorl with a long, narrow slit closed some distance behind the
apertural expansion. Ordovician and Silurian.

Trematonotus Hall. Like Salpingostoma except that the slit band is replaced by
a row of perforations. Silurian and Devonian.

522

MOLLUSCA

PHYLUM VI

Gonradella U. and S. (PhragmoUtes Conrad) (Fig. 847, D, E). Ordovician and
Silurian.

A 1! C

Fig. 847.

A, B, Bucania haüi Ulr. and Scof. Ordovician ; Minnesota. C. Salpingostoma hudli (Whitf.). Ordovician ;
Illinois. D, E, Conradella fimbriata Ulr. and Scof. Ordovician ; Minnesota.

Tetranota U. and S. Like Bucania, but witli four dorsal ridges. Ordovician
and Silurian.

Kohenia U. and S. Ordovician. Megalomphala Ulr. ; Oxydiscus Koken.
Ordovician to Devonian.

Family 7. Bellerophontidae M'Coy.

Symmeti'ical, involute shells with rapidly enlarging wJiorls, mouth expanded
laterally and ventrally hut not dorsally ; umhüicus small or closed ; inner lip thickened,
outer ivith a short slit ; slit band always present ; surface with lines of growth only or
cancellated. Cambrian to Triassic.

The Bellerophontidae were classed by Montfort with the Cephalopoda ; by Deshayes,
on accoimt of their resemblance to Atlanta, with the Heteropoda ; and by de Koninck

with the Aspidobranchiates. The
thick Shells sometimes retain traces
of their original pigmentation. At
least 300 Paleozoic species have
been described.'

Bellerophon Montfort (Fig. 848).
Distinguished by : (1), the absence
of sculpture save the lines of
growth ; (2) the small or entirely
closed umbilicus ; (3) the moderate
expanse of the aperture ; (4) the
callosity on the inner lip, and (5)
a well developed slit band terminat-
ing in a slit in the outer lip. Or-

Fio. 848.

BelleropJion bicarenus Leveille. Lower Carboniferous ;
Tournay, Belgium.

dovician to Permian, maximum in Carboniferous,

Patellostium Waagen. Like Bellerophon, but aperture greatly expanded. Devonian
and Carboniferous.

3LASS IV

GASTROPODA

23

Euphemus M'Coy (Fig. 849). Differs from Bellerophon in tlie revolving folds of
the inner lip. Carboniferous.

Bucanopsis Ulricli. Ordovician to Permian.

Warthia, Mogulia, and Stachella Waagen. Carboniferons.

Fig. 849.

Euphemus nrii Fleming. Lower
Carboniferous ; EdinburKh.

Fig. 850.

Carinarojms cymhula Hall.
Ordovician ; Kentucky.

Family 8. Carinaropsidae Ulrich and Scofield.

Symmetrical, almost patelliform shells of not more than two volutions with greatly
expanded aperture within which is a hroad concave septum.

Garinaropsis Hall (Phragmostoma Hall, non Waagen) (Fig. 850). Dorsum carinate ;
slit band occasionally distingiüshable. Ordovician and Silurian.

Suborder B. RHIPIDOGLOSSA Troschel.

{Scutihranchiata Ciivier ; Zygohranchia and Diotocardia von Ihering.)

Symmetrical and limpet-like or with spiral shells. GUIs pliime-Uke, two and sym-
metricalf or single. Radula with several large plates or teeth in the median portion, and
excessively numerouSj crowded, narrow, hooh-shaped teeth. Operculum often present.

The Rhipidoglossa comprise both air-breathing and aquatic forms, and are divisible
into two series : Zygohranchia, in which two gills are developed, and the shell is
generally perforated at the apex or has a slit in the outer lip ; and Anisohranchia,
with a Single gill and generally unslit shell.

Family 1. Haliotidae Fleming.

Shell flattened, auriform, with wide aperture, and no operculum. Interior nacreous,
with a row of perforations on the left outer margin. Marine. Cretaceous to Recent.

Haliotis Linn. This, the solitary genus, occurs very rarely fossil except in the
Quaternary.

Family 2. Pleurotomariidae d'Orbigny.

Shell spiral, sub-spherical, turhinate, conic, turreted or Planorhoid, nacreous inter-

li

Fio. 851.
/ "- {Raphistomdia) nulians Wissm. Keuper ; St. Cassian, Tyrol. B, Pleurotomaria
(Cryptaenia) imlita Goklf. Lower Lias ; Göppingen, Würteniberg.

524

MOLLUSCA

PHYLÜM VI

nally. OiUer lip ivith a sUt, from which a slit-hand {the anal fasciole) extends hackward,
traversing all the whorls. The slit sometimes replaced by one or more perforations.
Operculum horny. Cambrian to Kecent.

Pleurotomaria Sowb. (Figs. 851-853). Shell broadly conical or turbinate ; spire
sometimes high, in other cases depressed ; umbilicus present or absent. Guter lip
with slit ; growth-lines strongly recurved, meeting ■ in the slit-band. Silurian to
Recent. Foiir living and several hundred fossil species known. Rare in the late
Tertiary.

Subgenera : Ptychomphalus Agassiz ; Mourlonia, Worthenia, Agnesia de Koninck ;
Gosseletina, Ivania {Baylea de Kon.) Bayle ; Raphistoinella (Fig. 851, A), Zygites, Laubella,

Fig. 852.

A, PZetwoiomaria iyifor^uato Deslongchanips. Middle Lias ; May, Calvados. B, P. suhscalaris
Deslongchamps. Lower Oolite ; Bayeux, Calvados. 1/2-

Fig. 853.
Pleurotomaria {Leptoinaria) mojcrompTialla Zittel.

Tithonian ; Stramberg, Moravia.

Stuorella, ScMzodiscus Kittl ; Brüonella Kayser ; Hesperiella Holzapfel ; Cryptaenia (Fig.
851, B), Leptomaria Deslongchamps (Fig. 853), etc.

Porcellia Leveille (Leveüleia Newton) (Fig. 854). Shell
discoidal, flat, widely iimbilicate, nearly symmetrical, and
all but the first few whorls coiled in the same plane. Outer
lip Sharp, with long slit. Slit-band prominent, traversing
the central portion of the whorls. Devonian and Carboni-
ferous.

Kohenella Kittl. Very flat, discoidal, and only slightly
asymmetrical, with a broad slit-band. Trias. K,
(Hoernes).

Fig. 854.

Car-

Porcellia puzosi Leveille. ^

boniferous ; Tournay, Belgium

CLASS IV

GASTROPODA

525

Pohjtremaria de Kon. Shell turbinate, with band replaced l)y a row of perfora-
tions, of which the posterior ones are siiccessively closed. Carboniferoiis.

Düremaria d'Orb. (Fig. 855). Two oval pefforations connected by a slit are
present beliind the outer lip ; base with an umbilical callus. Jura.

Trochotoma Deslongch. Shell turbin- a b c

ate, with conical base. A slit closed at
either end is present behind the outer
lip, and corresponding to it is a slit-band.
Trias and Jura.

Fig. 855.

Ditremaria granulifera Zittel. Upper Tithonian
Stramberg, Moravia.

Fig. 856.

A, MurcMsonia Mlincata d'Arch. and Vern.
Devonian ; Paflfrath, near Cologne. B, M. hlumi
Klipstein. Trias ; St. Cassian, Tyrol. C, M.
siibsulcata de Kon. Lower Carboniferous ; Tour-
nay, Belgium. Last two whorls, 2/j.

Schizogonium Koken ; l'emnotropis Laube ; Gantantostoma Sandb. Devonian.

MurcMsonia d'Arch and Vern. (Fig. 856). Shell turreted, with numerous smooth
or ornamented whorls Outer lip with a slit, and corresponding to it a slit-band.
Cambrian to Trias. Maximum distribution in Devonian and Carboniferous.

Lophospira Whitf. (Fig. 857, Ä, ß). Shell with more or less elevated spire ;
whorls angular on the periphery and bearing from one to five distinct carinae.
Ordovician to Devonian.

Hormotoma Salter (Fig. 857, D). Elongate, beaded, practically imperforate ; outer
lip with broad, deep notch. Ordovician and Silurian.

Liospira Ulr. and Scof. Shell lenticular with aperture deeply notched and
band scarcely distinguishable. Ordovician and Silurian.

Schizolopha and Turritoma Ulrich. Oidovician and Silurian. Seelya,' Plethospira

A B CD

Fi(i. 857.

A, B, Lopliospira sumnereiisis (Safford). Ordovician ; Tennessee. C, Trepospira spheriüata (Conrad). Goal
Measures ; Illinois. D, Hormotoma salteri Ulrich. Ordovician ; Kentucky.

and Euconia Ulrich. Ordovician. Goelocaulus (Ehlert ;• Clathrospira Ulr. and Scof. ;
Ectomaria Koken {Solenospira Ulr. and Scof.). Ordovician and Silurian. Bemhexia
(Ehlert ; Trepospira Ulr. and Scof. (Fig. 857, G). Devonian and Carboniferous.

Family 3. Fissurellidae Risso.

Shell symmetricaly cap- or limpet-shaped, non-nacreous^ without operculum. Apex
erect or pointing hackward, often recurved, perforated. Anterior margin often with a
fissure ; yoimg shell with a spiral protoconch. Marine ; shore forms. Carboniferous to
Recent.

526

MOLLUSCA

PHYLUM VI

Of tlie three subfamilies iiito wliicli tliis group is divided, the Fissurellinae are
known only in tlie recent fauna. Fissurellidinae occur in the Pliocene ; all tlie
eai'lier forms are Emarginulinae.

Fissurella Brug. Sliell conical, oval, witli an oval apical orifice
bounded inside by an entire calliis. Recent. The niimerous fossil
species referred to this genus belong to Fissuridea.

Fissurellidea d'Orb. ; Pupillaea Gray ; Megatehennus and Luca-
pinella Pilsbry ; Macroschisma Swains. These are all Recent genera,
witli the apical orifice very large.

Lucapina Gray. Like Fissurella, but with large apical orifice
and finely crenate periphery. Pliocene and Recent.

Fissuridea Swains. {Glyphis Carp. ; Fissurella auct.) (Fig. 858).
Sliell conical, oval, with apex in advance of the middle, giving
place to a Perforation which is bounded inside by a posteriorly
truncate callus. Carboniferous (?) to Recent ; very abundant in the Tertiary.

Puncturella Lowe. Shell conical, with a perforation at or in front of the post-
niedian apex, behind which there is a shelf within the cavity. Eocene to Recent.
Emarginula Lam. (Figs, 859, 860). Conical or cap-shaped, with persistent post-

c

AB

858.

Fissuridea italica
Defr. Miocene ;

Grund, Hnngary.

Fig. 859.

Emarginula schlotheimi
Bronn. Oligocene; Wein-
heim, near Alzey, Baden.

Emarginula muensteri Pictet.
Kei;per ; St. Cassian, Tyrol.
A, B, Natural size. C, Enlarged.

Fig. 861.

Tdmula goldfnssi (Roem).
Coral-Rag ; Holieneggelsen,
Hanover. A, Natural size.
B, Enlarged.

median apex, and a slit in the front margin of the shell. Surface cancellated.
Carboniferous to Recent.

Bimula Defr. (Fig. 861). Like the last, but slit replaced by a closed hole on the
anterior slope. Lias to Recent.

Suhemarginula Blainv. Like Emarginula, but slit sliort or wanting, and no slit-
band. Eocene to Recent.

Scutus Montf. {Parmophorus Blainv.). Shell depressed, oblong, without fissure,
slit, or slit-band ; muscle Impression near the edge. Eocene to Recent.

The families Phenacolepadidae, with the single genus Phenacolepas Pils. (Scutellina
Gray), Cocculinidae and Addisoniidae are recent groups allied to the Fissurellida e.

Family 4. Euomphalidae de Koninck.

Shell depressed conical to discoidal, spirally coiled, more or less deeply and widely
umUlicate. Whorls sometimes in a loose spiral, smooth or angular ; the earlier whorls
frequently separated of hy partitions. Outer lip usually with a shallow indentation.
Operculum calcareous. Cambrian to Cretaceous.

The Euomphalidae belong primarily to the Paleozoic era. They have been
variously associated with the Trochidae, Turbinidae, Littorinidae and Solariidae.' The
Shells bear a strong resemblance to those of the last-named group, but in Solarium the
embryonic apex is sinistral, whereas in the Euomphalidae it is dextral. Opercula are
known with certainty in only a few genera, such as Maclurea. De Koninck surmised
that the deeply excavated, slipper-shaped opercula from the Carboniferous, described
originally as Galceola dumontiana, are referable to Euomphalus.

CLASS IV

GASTROPODA

527

Btraiiarollina Billings. Canil)ri;ni. OpUleta Vanuxem. Cambrian to Siluriaii.
Maclurea Lesciieur ; Maclurina Ulr. and Scof. Ordovician and Silurian.

Platyschisma M'Coy. Thin - shelled, (l.]ii<>s('d
conical, smootli. Unibilicus relatively narruw ; outer
lip witli broad sinus. Silurian to Carboniferous. P.
helicoides Sowb. Carboniferous.

Straparollus Montf. (Fig. 862). Turbinate to
discoidal, with broad unibilicus. Whorls smooth or
witli fine transverse Striae. Silurian to Jura ; especially
abundant in Devonian and Carboniferous.

Phanerotinus Sowb. Like tlie last, except tliat tlie
wliorls form an open spiral. Carboniferous.

Euomphalus Sowb. {Pleuronotus Hall; Schizostoma
Bronn) (Fig. 863). Depressed conical to discoidal, witli wide umbilicus. Spire
flattened or eveii concave superiorly ; whorls angular, tlie edges sometimes set witli
nodes {Phymatifer de Kon.). Outer lip with emargination at the upper angle. Silu-
rian to Trias ; maximum in Carboniferous.

A B

Fig. 862.

Straparollus dionysii Montf.
Carboniferous ; Vise, Belgiuni.

Euomphalus catülus (Sowb.). Carboniferous ; Kildare, Ireland.
A, Superior, and B, Inferior aspect.

Fio. 864.

DiscoJielix orMs Reuss. Middle Lias
Hinter-Schafberg, Austria.

Subgenera : Omphalocirrus de Ryckholt. Devonian and Carboniferous. Coelocentrus
Zittel. Trias.

Discohelix Dunk. (Fig. 864). Fiat, discoidal ; upper side flat or slightly concave,
the lower widely umbilicate. Whorls rectangular, with sharp edges. Trias to
Oligocene.

Eccyliomphalus Portlock ; Eccyliopterus Remele ; Helicotoma Salter. Ordovician
and Silurian.

Family 5. Raphistomidae Ulrich and Scofield.

Gomprising shells intermediate hetioeen the Euomphalidae and Pleurotomarudae^ and
regarded as ancestral to these f amilies and the Trochidae.

Eaphistoma Hall. Shell depressed or completely flattened ; whorls angular above ;
umbilicus moderately broad ; outer lip with short notch on the keel. Ordovician
and Silurian.

Euomphalopterus Roemer. Distinguished by its more rounded volutions and
excessively developed carinae. Silurian.

Scalites Emmons, non Conrad. Turbinate, spire only moderately high and
acuminate; whorls flattened superiorly, risiut^ sie]. like one above the otlier, sharply
angular at the periphery, produced below. Bods w liorl very large, smooth; aperture

528

MOLLUSCA

PHYLUM VI

ßub-triangular, faintly notched ; no umbilicus. Ordoviciaii (Chazy), and according to
Laube, also Triassic. Type, S. angulatus Emmons.
Raphistomina Ulr. and Scof. Ordovician.

Family 6. Stomatiidae Gray.

Shell depressed, composed of a few very rapidly widening whorls ; nacreous internally ;
o,perture large.

Witli tlie exception of Stomatia Helb. and Stomatella Lamarck, a few rare repre-
sentatives of wliicli are known as early as tlie Cretaceous (perliaps also Jurassic), tliis
family belongs to tlie Recent period.

Fig. SC5.

Omphalotrochus discus Sowb. Silurian ;
Dudley, England, i/j (after Nicholson).

866.

Family 7. Turbinidae Adams.

Shell turhinate, discoidal or turreted, nacreous internally. Aperture rounded or
oval; inner lip smooth or with callus, the outer lip never reßecied. Operculum cal-
careous, very thick, convex externally. Ordovician to Recent.

The extremely abiindant Recent Turbinidae are distinguished principally by

cliaracters of tlie operculum ;
but inasmuch as tbis is
known in but few of tlie
fossil forms, tlie precise deter-
mination of tlie latter is
usually uncertain. It is
customary, therefore, to group
under the general head of
Turbo such fossil turbinate
Shells with a sub - circular
Omphalotrochus gioiosus aperture as are not speciallv

(Schloth.). Silurian; Got- ,. ^. • i n i ,

nd. Operculum pre- aistinguished by some otlier

served in place (after pItj, rnptpr«

Lindströin). cuaracters.

Omphalotrochus Meek

(Polytropis de Kon. ;
Oriostoma Liiidström,
non Munier - Chalm.)
(Figs. 865, 866). Dis-
coidal or depressed
conical, widely umbi-
licate. Whorls round,
ornamented with

raised longitudinal

keels. Operculum extremely thick, fiat internally, conical externally, multispiral.

Ordovician to Carboniferous ; especially abundant in Silurian.

Astralium Link (Figs. 867, 868). Turbinate; whorls rough, often spinöse, and

usually keeled. Aperture depressed, witli disconnected margin. Base more or less

flattened ; operculum calcareous, thick, flat internally, spirally coiled, and with very

eccentric protoconch. Trias to Recent.

Subgenera: Bolma Risso (Fig. 867); Pachypoma, Lithopoma, Uvanilla (Fig. 868), Guil-
fordia Gray ; Calcar Montfort, etc.

Turho Linn. (Fig. 869). Turbinate to concial ; aperture nearly circular. Oper-
culum calcareous, thick, flat internally, externally convex, multispiral, with sub-central
nucleus. Silurian (?) to Recent.

Fig. 867

Astralium (Bolma) rugosum Linn. Pliocene :
Pienza, Tuscany. Shell and operculum.

Astralium (Uvanilla) damon Laube.
Keuper ; St. Cassian,Tyrol.

CLASS IV

GASTROPODA

529

Snhgenom -.Sarmaticus, Ninella (Fig. 869), Modelia, aud Callopoma Gray ; Henectus
Humphr. ; Batillus ^c\\\\m. ^ die. "^

Gollonia Gray (Fig. 870). Like Turho, but operciilum witli a thin calcareous layer
disposed in a spiral rib. Eoceiie to Recent.

Family 8. Phasianellidae Trosc.liel.

Shell elongated, oval, thin, smooth, lustrous, ijorcellanous, not
nacreous internally,

loithout umhilicus. Body
lühorl large, with oval
aperture. Opercuhim

calcareous, convex exter-
nally. Devonian to
Recent.

Phasianella Lam.
(Phasianns Montf.) (Fig.
871). With the.jchar-
acters of tlie family.
Cretaceous to Recent ;
pcrhaps also Paleozoic.

Fig. 869.

Turho (Ninella) parlcitisoni
Bast. Oligocene ; Dax, near
Bordeaux.

Fig. 870.

Collonia- modcda
Fuchs. Oligocene ;
Monte Gninii, near
Castel Goniberto,
Italy.

Fig. 871.

Phasianella gosauica
Zekeli. Turonian;Qosau,
Austria.

Family 9. Delphinulidae Fischer.

Shell turbinate er discoidal, usually thich, nacreous internally, and ornamented
externally ivith spines, rihs or folds. Aperture circular, peristome entire ; outer lip
usually expanded or thichened. OperciUum horny, often strengthened by a thin calcareous
outer layer. Silurian to Recent.

Graspedostoma Lindström. Globose, narrowly umbilicate, with short spire, and
large transversely striated or cancellated body whorl. Inner lip with an alar process
at tlie end of the columella. Silurian. G. elegantulum Lindström.

Grossostoma Morr. and Lyc. (Fig. 872). Depressed turbinate, smooth, without

Fig. 872.

Crossostoina reflexi-
läbrum (d'Orb.).
Middle Lias ; May,
Calvados.

Fig. 873.

Liotia ffervillei
(Desliayes). Calcaire
Grossier ; Haute-
ville, near Valogne,
F'rance.

Fig. 874.

Delphinula segregata
Heb. et Desl. Callo-
vian ; Montreuil - Bel-
lay, Maine-et-Loire.

Fig. 875.

Delphinula scobina
(Brongniart). Oligocene ;
Gaas, near Dax, France.

urabilicus. Spire short, aperture round, narrowed by a callus. Outer lip somewhat
reflexed. Trias and Jura.

Liotia Gray (Fig. 873). Depressed turbinate, with transversa swellings. Aperture
thickened by a callous rim. Jura to Recent.

Delphinula Lam. (Angaria Bolt.) (Figs. 874, 875). Depressed turbinate, um-
bilicate. Whorls scaly, spinous or spirally ornamented. Aperture circular, lip
without thickening. Trias to Recent.

VOL. I 2 M

530

MOLLUSCA

PHYLUM VI

Family 10. Trochonematidae Zittel.

Shell pyramidal, turhinate or discoidal, dextral or sinistral, with internal nacreons
layer. JVhorls convex, with one or more longitudinal Jceels, and slightly undulating
transversa Striae or ribs. Aperture rounded, sometimes with faint notch. Operculum
unknown, presumahly horny. Marine. Cambrian to Cretaceous.

This extinct group is very abundant in tlie Paleozoic, and notably so in Jurassic
rocks. The shells, as a rule, are highly ornamented, and have been associated by some
with the Littorinidae, by others with the Turbinidae or Purpurinidae. They form
a distinct family, which is best placed in the neighbourhood of the Turbinidae and
Trochidae.

Trochonema Salter. Pyramidal to turbinate, deeply umbilicate, longitudinally
keeled and transversely striated. Aperture round ; the umbilicus surrounded by a
keel. Cambrian to Silurian.

Eunema Salter (Fig. 876). Pyramidal, with acute, elongate spire, and no umbilicus.
Whorls with two or more spiral keels, and strong transverse Striae. Aperture oval,
slightly notched anteriorly. Ordovician to Devonian.

Fig. 876.

Eunema strigilata Sal-
ter. Ordovician ; Pau-
quette Falls, Canada.

Fig. 877.

Cydonema bilix Conrad.
Ordovician ; Cincinnati,
Ohio.

Ambcrleya capitanea
Münst. Upper Lias ; La
Verpilliere, near Lyons,
France.

Cydonema Hall (Fig. 877). Turbinate, whorls infiated and ornamented with fine
Spiral Striae ; aperture rounded, peristome discontinuous. Ordovician to Devonian.

Strophostylus and Holopea Hall ; Gyronema Ulrich. Ordovician and Silurian.
Dyeria Ulrich. Ordovician. Bucanospira Ulrich. Silurian.

Amberleya Morr. and Lyc. (Eucyclus Deslongch.) (Fig. 878). Turbinate to

Fig. 879.

Platyacra impressa
(Schafhautl). Lower
Lias ; Hoclifellen,
ßavaria. Cirrus nodosus Sowb.

pyramidal, with deep sutures, and no umbilicus,

Fio, 880.
Lower Oolite

Yeovil, England.

Spiral keels usually nodose or spiny.

CLASS IV

GASTROPODA

531

and crossed by strong transverse Striae, which are more numerous in the lower portion
of the whorls tlian in tlie upper. Aperture rounded, sometimes witli a shallow notch.
Trias to Cretaceous ; common in all divisions of the Jura.

Oncospira Zitt. Pyramidal, spirally ribbed, with one or two transverse swellings
on each whorl, disposed continuously along the spire. Jura.

Harausina Gemni. Sinistral, with nodose longitudinal keels, and no umbilicus.
Lias.

Platyacra v. Amnion (Fig. 879). Like the last, but with flattened apex, and the
earlier whorls discoidal. Lias.

Cirrus Sowb. (Scaevola Gemm.) (Fig. 880). Sinistral, turbinate shells, deeply
and widely umbilicate. Spire acuminate ; whorls spirally keeled and striated, and
with strong transverse ribs. Trias to Middle Jura.

Family 11. Trochidae Adams.

Shell conical, turhinate or pyramidalj nacreous internally. Aperture trapezoidal or
sub-circular, peristome disconnected, inner lip often hearing a tooth. Base more or less
flattened ; operculum thin, horny. Ordovician to Recent.

Precise determination of the numerous fossil Trochidae is not less difficult than
that of the Turbinidae. Paleozoic and Mesozoic forms in many cases do not harmonise
with recent genera, but represent rather col-
lective types, in which characters now distri-
buted amongst several genera or even families
are united. Shells incapable of more accurate
determination liave been commonly assigned to
the genus Trochus. Among the more ancient
true Trochidae may be mentioned the following :
the Trochus species described by Lindström
from the Silurian of Gotland ; also Flemingia
and Glyptohasis de Koninck, and Microdoma
Meek and Worthen, from the Carboniferous ;
Turhina (Fig. 881) and Turhonellina de
Koninck, ranging from the Carboniferous to
the Trias.

Trochus Linn. (Fig. 882). Shell conical or pyramidal ; whorls slightly convex or
flat ; base angular at the periphery. Inner lip often truncated anteriorly, thickened
or with teeth. Silurian to Recent.

Subgenera : Tectus Montf. (Fig. 882) ; Folydonta Schum. ; Clanculus Montf., etc.

Monodonta Lam. (Figs. 883, 884). Turbinate, with nearly round aperture, the

Turhina spirulis
Münst. Keuper ; St.
Cassian, Tyrol.

Trochus {Tectus) luca-
sanus Brongt. Oligo-
cene ; Castel Gomberto
near Vicenza.

Fig. 883.

Monodonta nodosa Münst.
Keuper ; St. Cassian, Tyrol.

Fkj. 884.

Monodonta (Oxystele) patukt
Brocchi. Miocene ; Steina-
brunn, near Vienna.

Fi(i. 885.

Gibhula picta
Eichwald. Mio-
cene; Wiesen,
near Vienna.

Fir,. 886.

Gihhula brocchii
Mayer. Pliocene ;

Montopoli, Tuscany.

columella ending below in a tooth.
Phil., the tooth is wanting.

Trias to Recent. In the subgenera Osilinus and

.32

MOLLUSCA

THYLUM VI

Gihbula Eisso (Figs, 885, 886). Turbinate or low conical, iinibilicate, and witli
roiinded apertiire. Tertiary and Recent.

Fig. 887.

Calliostoma semi-
putictatum Münst.
Keuper ; St. Cas-
sian, Tyrol. 2/^.

Calliostoma aequalis
Buv. Coral-Rag ; St.
Mihiel; Meuse.

Fig. 889.

Leimsiella conica (d'Orb.).
Middle Lias ; May, Cal-
vados.

Fig. 890.

Solariella peregrina
(Libassi). Pliocene ; Or-
ciaiio, Tuscaiiy.

Fig. 891.

Margaritcs margaritula
Mer. Oligocene ; Weinlieim,
near Alzey, Baden.

GalUostoma Swains. {Ziziphinus Gray) (Figs. 887, 888). Conical, with peripheral
keel and flattened base. Trias to Recent.

Otlier genera are Cantharidus Montfort ; Leivisiella
Stol. (Fig. 889); Tegula Lesson; Solariella Wood
(Fig. 890) ; Margarites Leach (Fig. 891) ; Danilia Brus.
(Fig. 892) ; Gamitia Gray, and many others. Most of
these liave a more or less extensive Tertiary liistory.

Family 12. Umtaoniidae Adams.

Fig. 892.

Danilia cZaiTiraia (Etall.). Coral-Rag
Valfin, Ain. 2/^.

Shell small, usually depressed discoidal, s7nooth and
lustrous, or ivith fine spiral Striae, and without nacreous
layer. Outer lip sharp, peristome discontinuous. Um-
bilicus often concealed hy a callus ; operculum liorny. Silurian to Recent.

Allied to the Recent genera Umbonium Link (Rotella Lam.), Tsanda Adams,

Fig. 893.

^, , Fig. 894.

Chrysostoma

acmon(d'Orh.). Teinostoma rotellae-

Middle Jura ; formis Desh. Calcaire

Baiin, near Grossier ; Grignon,

Cracow. near Paris.

Helicocryptus pusillus (Roem.). Coral-
Rag ; Lindener Berg, near Hannover.

iFiG. 896.

Adeorbis tr
Desh. Middle
(Auversien) ;
Seine-et-Oise.

icostatus
Eocene
Auvers,

etc., are a nnmber of fossil forms, such as Pycnomphalus Lindström, from the
Silurian and Devonian ; Änomphalus Meek and Worthen, and Rotellina de Koninck,
from the Carboniferous ; Ghrysostoma Swainson (Fig. 893), from the Jura, and others,
which are probably the ancestors of the Umboniidae.

Whether the genera Teinostoma (Fig. 894) and Vitrinella Adams, together with
their fossil allies from the Carboniferous onward, are rightly assigned to this group, is
doubtful. Helicocryptus d'Orb. (Fig. 895), from the Jura and Cretaceous, is similar to
Vitrinella. Gyclostrema Marryat, comprising small, lustrous shells, and the spirally
Stria ted ones known as Adeorbis S. Woodw. (Fig. 896), present some resemblances to
the Umboniidae ; but, according to Fischer, they form separate families. All of these
genera have fossil representatives in the Tertiary.

CLA8S IV

GASTROPODA

533

Family 13. Neritopsidae Fischer.

Shell oval to semi-glohose, with short, sometimes laterally twisted spire, and without
umbilicus or nacreous layer. Body whorl very large ; aperture oval or semicircular,
Inner lip calloas, curved and occasionally notched. Operculum calca-
reous, not spiral, with suh-central nucleus, and internally lüith callous
colr.mellar margin, which forms a hroad, angular or rounded process in
the middle. Devonian to Recent.

The Neritopsidae are distiiiguished from the closely related
Neritidae, principally by the totally ditferent, non-spiral operculum,
and by the fact that the internal partitions are not resorbed, as in
the latter family. Detached operciila have been described under the
nanies of Peltairon, Scaphanidia, Cyclidia and Rhynchidia.

Naticopsis M'Coy {Neritomopsis Waagen) (Figs. 897-899). Shell oval to globose,
sraooth or transversely striated. Aperture oval ; inner lip flattened, somewhat

A B

%

Fio. S97.

Naticopsis mandel-
slohi (Klipstein).
Keuper ; St. Cas-
sian, Tyrol.

A, Naticopsis ampliata Phil. Carboniferous ; Vise, Belgium.
B, Operculum of N. planispira Phil., from sarae locality (after de
Koninck).

Naticopsis lemniscata Hoernes. Trias ;
Esino, Lombardy. Original coloration
preserved.

callous, curved and sometimes transversely striated. Sparse in Devonian, but very
common in Carboniferous and Trias.

Hologyra Koken. Semi-globose, smooth, with faintly impressed sutures. Spire
short, laterally situated, not resorbed internally. Inner lip flattened, callous, covering
the umbilicus, and with sharp margin. Abundant in the Trias. Some species, such
as H. neritacea (Münst.), have the original colouring admirably preserved.

Marmolatella Kittl. Auriform to cap-shaped, with very short, incurved and
almost marginal spire. Last whorl much distended ; inner lip callous, broad,
arched. Trias. M. stomatia (Stopp.), M. telleri (Kittl).

Natiria de Koninck. Silurian to Carboniferous. Palaeonarica Kittl (Pseudo-
fossarus Koken). •

Naticella Münst. (Fig. 900). Thin-shelled, depressed, with straight spire, and
large, transversely ribbed body whorl. Trias.

Fio. 900.
Naticella costata Münster.
Upper Trias; Wengen, Soutli-
eru Tyrol.

Fio. 901.

A, Neritopsis monillfoi-mis Grat.
Miocene ; Lapugy, Transylvania. B,
N. spinosa Heb. et Deslong. Callovian ;
Montnniil-Bellay, Maine-et-Loire.

Fio. 902.

Operculum of Nerito]ms raJiihi.
Recent; New Caledonia. Bxternal
and int«'rnal aspects (aft«'r Citisse).

534

MOLLUSCA

PHYLÜM V

Platychilina Koken {Fossariopsis Laube). Spire depressed, straight ; last wliorl
large, surface rough, tuberciilose. Inner lip even, witli simple margin. Trias. P.
pustulosus (Münst.).

Delphinulopsis Laube. Like the last, but spire composed of loosely connected
whorls. Sutures deep. Body wborl witli nodose longitudinal keels. Inner lip even,
with Sharp margin. Trias. D. hinodosa (Münst.).

Neritopsis Grat. (Figs. 901, 902). Spire depressed, body wliorl very large.
Surface witli spiral and transverse ribs or nodes, often cancellated. Inner lip
tliickened, witli broad, angular emargination in the middle. Trias to Kecent.

Family 14, Neritidae Lamarck.

Shell semi-glohose, without umhilicus or nacreous layer. Spire very short, somewhat
lateral; whorls rapidly hroadening, the last very large, and earlier ones resorbed
internally. Aperture semicircular ; margin of the ßattened or calloused inner lip often
with teeth. Operculum calcareous, with a lateral spiral nucleus, and a process for
muscle attachment on the inner side. Trias to Recent.

The Neritidae are partly marine, and partly fresh-water inhabitants. The former
live usually in the vicinity of the coast, the latter often in brackish water. Since the
earlier whorls are internally resorbed, moulds of the interior reveal no trace of the spire.
This character, together with the form of the operculum, serves to distinguish the
family from the Naticopsidae, from wliich both it and the terrestrial Helicinidae
are probably descended. Fossil forms not infrequently retain traces of tlieir former
coloration.

Neritaria- Koken {Protonerita Kittl). Spire acuminate, suture deej), surface
smootli. Outer lip sharp ; inner lip callous, flattened. Resorption of the inner walls
incomplete. Trias.

Nerita Linn. (Fig. 903). Thick, ovoid or semi-globose, imperforate. Surface
smooth or with spiral ribs. Inner lip callous, flattened, with a straight, often
denticulate border. Operculum sub-spiral. Trias (?) to Recent.

(?) Oncochilus Pethö (Fig. 904). Smooth ; inner lip arched, callous, bearing two or
three teeth on the margin or smooth ; outer lip sharp. Trias and Jura.

Lissochilus Pethö (Fig. 905) ; Neritodomus Morr. and Lyc. ; Neritoma Morris.
Jura. Otostoma d'Arch. ; Dejanira Stol. Cretaceous.

Velates Montf. (Fig. 906). Depressed conical, only the curved apex of the spire
Abc

Fig. 903.

A, Nerita laffoni Merian. Citharella Limestone ; Bpfen-
hofen, near Schaffliavisen, Switzerland. B, N. granulosa
Desh. Eocene (Sables Moyens); Auvers, near Paris. C,
Operculum of a recent Nerita.

Oncochilus chromaticus Zittel. Upper
Tithonian ; Stramberg, Moravia.

visible. Last whorl very large. Inner lip convex or straight, with denticulate margin.
Abundant in the European Eocene ; sometimes attaining a size of 10 or 12 cm.

Neritina Lam. (Fig. 907). Sniall, semi-globose, lustrous, smooth or spiny, mostly
brilliantly coloured. Inner lip flattened, with sharp or fiiiely toothed margin ; outer
lip Sharp. Inhabits brackish or fresh water. Abundant in Tertiary and Recent. The
supposed Mesozoic forms belong principally to Nerita.

CLASS IV GASTROPODA

Püeolus Sowb. (Fig. 908). Snicall, cup-shaped to

Fig. 905.

535

conical, ovoid or round.

Lissochilus sigaretinus Buv.
Coral-Rag ; Hoheneggelsen, Han-
nover.

Neritina (iratelonpana Fer.
Mioceue ; Häufelburg, near Günz-
burg.

Fig. 908.
Püeolus jilicatus Sowb. Bathon-
ian ; Langrune, Calvados, ^/i-

Fig. 906.

Velates schmidelianus Cham. Lower Eocene
(Londinien) ; Cuise-Lamothe, Oise.

Apex sliglitly cvirved backwards ; only the last wliorl visible. Aperture semicircular ;
inner lip broad, callous. Jura to Eocene.

Order 2. CTBNOBRANCHIATA Schweigger.

{Pectinihranchia Cuvier ; Azygohranchia von Ihering ; Monotocardia Bouvier.)

Right cervical gill jJectinate, very large, and usually transposed to the left side, owing
to torsion of the hody ; the left gill atrophied. Heart with hut one auricle. Radula
smally variously constructed, hut usually armed with fevj teeth in a transverse series.
Shell coiled in a more or less elevated spiral, rarely cup- or cap-shaped.

The Ctenobrancliiata constitute the largest group of the Streptoneura. They are
for the most part marine, but some are terrestrial, and some inhabit fresh water.
Beginning in the Sikirian, they attain their maximum distribution in the Mesozoic,
Tertiary and Recent periods, A division into two groups — Holostomata and Siphono-
stomata — according to the nature of the aperture, has been attempted ; but this is
unnatural, since it emphasises a shell character whicli is unaccompanied by any
anatomical differences. Classifications based upon the structure of the radula, such as
have been proposed by Troschel, and more recently by Bouvier, are valueless in
Paleontology. Here it will be sufficient to recognise two suborders primarily :
Platypoda, in which the foot is typically developed ; and Heteropoda^ in which it is
modified into a fin.

Suborder A. HETEROPODA Lamarck.

{Nucleohranchiata Blainville.)

To the Heteropoda belong naked or shell-covered, free-swimming and pelagic
marine MoUusks, with distinct liead and highly developed sense organs. Heart, gills,

536

MOLLUSCA

PHYLÜM VI

reproductive organs and nervous System agree with tlie correspondiiig organs of the
Ctenobranchiates ; tlie radula resembles that of tlie Taenioglossa. Tliey differ con-
siderably, however, from the Prosobrancliiates, since the foot is modified into a sort of
vertical fin, and imparts to them a peciüiar appearaiice. They
rise usually toward evening in great swarms to the surface of
the ocean, where they hover about with a very rapid motion,
swimming in an inverted position, with the dorsal side down,
and the foot uppermost. They are exceedingly delicate, often
transparent organisms, The body may be either entirely
naked or provided with a very thin, light shell.

Two Recent genera have been found also in early Tertiary
deposits. Of these Garinaria Lamarck, has a keeled, cap-shaped,
glassy shell ; while in Atlanta Lesson (Fig. 909), the delicate
shell is coiled spirally in a single plane, and the apertiire is provided with a slit.
Owing to a similarity in coiling of Atlanta and Oxygyrus to that of the Paleozoic
Bellerophontidae, a relationship between the two has been suggested. The latter
forms are distinguished by their heavier, thicker shells, but are very pi'obably related
to Emarginula and its allies.

Fio. 909.

Atlanta peronii Lesueur.
Recent ; Atlantic Ocean.

Suborder B. PLATYPODA Lamarck.

Fig. 910.

Superfamily 1. GYMNOGLOSSA Gray.

Mostly Jiolostomate forms, in which the radula is usually unarmed through degenera-
tion. The smaller forms frequently parasitic or commensal.

Family 1. Eulimidae Fischer.

Small, polished, elongate-conic shells, with ovate aper-
tures ; the axis often ddstorted, protoconch dextral. Trias
to Recent.

Eulima Risso {Melanella Bowdich) (Fig. 910). Tur-
reted, smooth, lustrous, without umbilicus. Trias to
Recent.

Niso Risso (Fig. 911). Like the last, but with deep
umbilicus reaching to the apex. Trias to Recent.

A, Eulima suh
ulata Don. Plio

Family 2. Pyramidellidae Gray. cene ; Coroncina

Tuscany. B, E.

Shell turreted to elongate-oval. Aperture oval, an- poiita (Linn.),
teriorly rounded, or angular ; outer lip sharp. Operculum leis, Moravin.
horny, spiral. Marine. Cambrian to Recent.

The protoconch consists of several whorls, and in Paleozoic and Mesozoic forms is
coiled in the same direction as the remainder of the shell. But in the younger and
more typical genera it is heterostrophic, distinctly separated from the rest of the
shell, and often Stands at an angle with the adult spire. It is questionable whether
forms older than the Cenozoic can be retained in this family ; Fischer places most of
thent in a new family, entitled Pseudomelaniidae.

Macrocheilus Phil. {Macrochilina Bayle ; Strohaeus de Kon.) (Fig. 9 1 2). Elongate-
oval, without umbilicus, smooth or with slightly curved growth-lines. Spire acuminate,
only moderately high ; last whorl large. Aperture angular posteriorly, sometimes
also in front. Inner lip with weak anterior folds. Silurian to Trias.

(?) Ptychostoma Laube ; (?) Undularia Koken. Trias.

Loxonema Phil. Turreted, whorls arched, with S-shaped growth-lines. Sutures

Fig. 911.

Niso eburnea
Risso. Plio-
cene ; Monte
Mario, near
Rome.

CLASS IV

GASTKOPODA

537

Silnrian to Trias ; paiticiilarly

deep ; aperture higlier tlian wide, with shallow canal.
abundaiit in tlie Carboniferoiis.

Zygopleura Koken. Like the last, but whorls with sharp, sliglitly curved
transverse ribs, or transverse nodose keel. Devonian to Lower Cretaceoiis.

Bourgetia Deshayes {Pithodea de Kon.). Lai-ge,
elongate-oval to turreted, with large, inflated body
whorl. Snrface marked with spiral Striae or furrows.
Carboniferous and Upper Jura.

Pseudomelania Pictet {Chemnitzia p.p. d'Orbigny)
(Fig. 913). Turreted, with
numerous, ahnost flat whorls,
and slightly impressed sutures.
Snrface smooth, or marked by
fine growth-lines ; aperture
rounded anterioiiy, or with
faint canal. Unibilicus want-
ing; rarely an umbilical fissure
present. Very abundant in the
Trias and Jura, less so in
Cretaceous and Eocene ; prob-
ably present also in the Car-
boniferous.

Siibgenera : Oonia, Microschiza
Geram. ; Hypsipleura, Anoptychia
Koken. Trias and Jura. Coe-
lostylina, Eiistylus, Spirostylus
Kittl. Trias. Bayania Munier-
Chalm. (Fig. 914). Eocene.

Fio. 912.
Macroclieilus arculatus
(Schloth.). Middle De-
vonian ; Paffrath, near
Cologne.

Fio. 913.

Pseudomelania
heddingtonensis
(Sowb.). Oxford-
ian ; France. Bands
of original colora-
tion still showing.

Fig. 914.

Pseudomelania
(Bayania) lactea
Lam. sp. Cal-
caire Grossier ;
Grignon, near
Paris.

Pustularia Koken, non Swains. Turreted, with groove-like sutures. WhorLs
flat, with three or more spiral rows of nodes. Trias.

Gatosira Koken. Whorls flat, with transverse ridges. Aperture canaliculate ;

base with spiral grooves. Trias and Jura.

Biastoma Desh. (Fig. 915). Like the last,
but aperture separated from the body whorl.
Whorls with transverse folds and spiral Striae.
Cretaceous to Recent.

Mathilda Semper {Promathilda Andreae).
Turreted ; whorls transversely and spirally
striated or ribbed. Aperture with canaL Proto-
conch heterostrophic. Jura to Recent.

Keilostoma Desh. {Paryphostoma Bayan) (Fig.
916). Turreted, spirally striated. Outer lip
with externally thickened margin. Eocene.

Turbonilla Risso {Chemnitzia p.p. d'Orb.) (Fig.
917). Small, turreted, with heterostrophic proto-
conch. Whorls transversely ribbed or smooth.
Inner lip straight, or occasionally with folds.
Tertiary and Recent.

Odostomia Fleming (Fig. 918); Pyramidella

Lamarck (Fig. 919). Cretaceous to Recent.

Tertiary and Recent. Palaeoniso Gemm. Trias

Fig. 915.

Diastema costcllata
(Lam.). Calcaire
Grossior ; Daniery,
near Bpernay.

Syrnola Adams
and Jura.

The genera

Fig. 916.

Keilostoma turricula
Brug. sp, (Melania
margiimta Lamarck).
Calcaire Grossier ;
Grignon, near Paris.

Eidimella Fischer.

Suhulites Conrad (? Pohjphemopsis Portlock), from the Cambrian t^

538 MOLLUSCA phylum vi

Carboniferous ; Fusispira Hall, Ordovician ; and Soleniscus Meek and Wortlien,

Fio. 917.

Turbonüla rufa
Phil. Crag; Sutton,
England.

Fig. 918.
Odostomia pli-
cata (Montf.).
Upijer Oligocene ;
Nieder-Kaufungen,
near Cassel.

Fig. 919.

Pyramidella pli-
cosa Bronn. Mio-
cene ; Niederleis,
Moravia.

Fig. 920.

Euchrysalis fusi-
formis (Münster).
Kenper ; St. Cas-
sian, Tyrol.

Carboniferous, are cliaracterised by narrow, anteriorly elongated and canaliculate aper-
tures. They probably form a separate family, in which also sliould be placed the
Triassic Euchrysalis Laube (Fig. 920).

Superfamily 2. PTENOGLOSSA Gray.

Teeth of the radula suhulate, numerous and similar in each transverse row.

Family 1. Epitoniidae, novum (Scalariidae Broderip).

Shell turreted, usually narrowly umhilicate. Whorls convex, transversely rihbed or
striated. Aperture round, with entire peristome. Operculum horny, paucispiral.
Marine. Sikirian to Recent.

Holopella M'Coy {Aclisina de Kon.). Slender, turreted ; whorls witli fine trans-
verse Striae, sometimes cancellated. Silurian to Carboniferous.

Gallonema Hall {Isonema Meek and Worth.). Turreted, oval to
globose ; whorls covered with lamellate transverse ribs ; aperture
circular. Silurian and Devonian.

Scoliostoma Braun. Devonian. Chilocyclus Bronn {Gochlearia
Braun) ; Ventricaria and Batycles Koken. Trias.

Epitonium Bolten {Scalaria Lam. ; Scala Klein ; Cirsotrema
Mörch) (Fig. 921). Turreted; whorls strongly arched, with trans-
verse ribs, and often also spirally striated. Aperture round, outer
lip sometimes thickened. Trias to Recent. Many subgenera.

Family 2. Solariidae Chenu.

Fk;. 921.

Scalaria lamellosa Shell depressed conical, deeply and hroadly umhilicate, without

Brocchi. Miocene ; nacreous lauer, Whorls

Baden, near Vienna. , '^ , ,

anguiar ; operculum horny

or calcareous spiral. The protoconch is

heterostrophic. Marine. Cretaceous to

Recent.

The Solariidae exhibit some resem-
blance to the Euomphalidae, from which
they are distinguished principally by the
heterostrophic protoconch. ^^^^.^^^ ^.^^^^^^

Solarium Lam. {Architectonica Bolten) Bronn. Miocene;
(Figs. 922, 923). Aperture quadrilateral ; Niederleis, Moravia.
operculum horny ; umbilical angle notched or sharp. Jura to Recent. A number
of Mesozoic forms confused with this genus probably belong to Euomphalus.

Torinia Gray. Tertiary and Recent. Bifrontia Desh. {Omalaxis Desh.). Eocene.

Fig. 923.

Solarium leymeriei Ryckholt.
Tourtia (Cenomanian) ; Tour-
nay, Belgium.

CLA8R TV

GASTROPODA

539

Superfamily 3. TAENIOGLOSSA Bouvier.

Teeth of the radula seven in each transverse roiv. Mainly holostomate forms, hat
some (jenem have deeply notched apertures, as in the higher divisions.

Family 1. Purpurinidae Zittel.

Thick-shelled, oval, with platform-like spire, and with-
out pearly layer. TVJiorls flattened heneath the suture and
angular, the angles often heset with nodes. Body whorl
large ; aperture oval, with anterior emargination, and
discontinuous peristome. Operculum unknown. Carboni-
feroiis to Cretaceous.

Trachydomia Meek and Worth. {Trachynerita Kittl).
Goal Measures ; North America and Europe. Pseudoscalites
Kittl ; Tretospira Koken. Trias ; Europe.

Purpurina d'Orb. Elongate-oval. Whorls angiilar
superiorly, sj)irally ribbed, with transverse folds or costae,
highly ornamented, often with umbilical fissure. Aperture
oval, anteriorly notched. Rhaetic and Jura. Furpuroidm noduiata (Young

n -TT j.i. /ny- r\ n A \ c< • • J.^ • and Bird). Great Oolite ; Minchin-

Furpuroidea Lycett (Fig. 924). Spire with successive hampton, England.
Steps or platforms, the flattened surface beneath the suture

bounded by a row of nodes. Last whorl inflated, smooth. Aperture anteriorly with
canal-like notch ; outer lip thin. Jura and Gretaceous.

Brachytrema Morris and Lycett ; Tomocheilus Gemm. Jura.

Fig. 924.

Family 2. Littorinidae Gray.

Shell turhinate, usually smooth or spirally ornamented, without nacreous layer.
Aperture rounded ; outer lip sharp. Operculum horny, paucispiral. Marine.
Ordovician to Recent.

Fossil Shells of this family are distinguished solely from those of the Turbinidae

and Trochidae by the absence of a pearly layer. The animal,

however, differs radically. The heart has but one auricle in

the Littorinidae, two in the Turbinidae and Trochidae. The

radula in the last-named groups is rhipidoglossate ; in the

present family it is taenioglossate. The differences.in essen tial

structure are thus seen to be considerable ; yet the sliells

when fossilised are so similar, it can scarcely be doubted tliat

the so-called Paleozoic Littorinidae are in many cases very

closely related to genera referred to the Turbinidae and

Trochidae. The limits of these families are therefore very

Ym, 925. uncertain, so far as Paleozoic forras are concemed. Among

Turhoniteiia subcostafa the extinct genera which exhibit great similarity to Littorina,

(^"i^^f;)- Middie üevonian ; j^^^; are often assigned to the above-named families, may be

Paffrath, near Cologne. , , „°, . „ , xx n r\ j • • ^

mentioned the followmg : Holopea Hall. Ordovician to
Devonian. Turhoniteiia de Koninck (Fig. 925). Devonian and Carbonil'.ioii>.
Portlockia, Turhinilopsis and Rhahdopleura de Koninck. Lower Carboniferous.
Lacunina Kittl. Tiias.

Littorina Fer. (Fig. 926). Thick-shelled, turbinate to globose, smooth or s])ii-al]y
striated, without umbilicus. Aperture oval. Jura to Recent.

540

MOLLUSCA

PHYLUM VI

Lacuna Tiirton (Fig. 927). Like the last, biit thiii, small, with an excavated pillar.
Tertiary and Recent.

Fi(f. 926.

Littorina litorea (Linn.).
Post-Pleistocene ; Isle of
Skaptö.

Fig. 927.

Lacuna (?) basterotina
Bronn. Miocene ; Stein-
abrunn, near Vienna.

Fig. 92

Fossarus costatus Brocchi. Pliocene :
Limite, Tuscany.

Lacunella Desli. Eocene. Litiopa Rang ; Planaxis Lam. ; Quoijia Desh. Tertiary
and Recent. The families Litiopidae and Planaxidae are usually recognised.

The genns Fossarus Phil. (Fig. 928) forins, according to Fischer, a separate family,
Fossaridae. It occiirs in the late Tertiary and Recent.

Family 3. Cyclostomatidae Menke.

Shell extremely variable in form, turhinate to discoidal, sometimes turreted, covered
with epidermis. Äperture circular, with usually entire peristome. Operculum horny or
calcareous, spiral. Terrestrial. Cretaceous to Recent.

Like the pulmonate snails, the animal possesses a respiratory cavity, But in
other respects they apjDroach the Littorinidae very closely, which latter forms also
have the gill much reduced. The shell habit is excessively variable. Tliere are more
than 600 Recent species distributed throughout all parts of the globe, but the majority

Fig. 929.

Cydostoma hi-
sulcatum Zieten.
Miocene ; Ermin-
gen, near Ulm,
Würtemberg.

Fig. 930.

Pomatias labellum
(Thoraas). Helix
Beds (Upper Oligo-
cene); Hochheim,
near Wiesbaden.

Fig. 931.

Cydotus exaratus Sandb.
Upper Eocene ; Pugnello,
Italy. Shell and operculum
(after Sandberger).

Fig. 932.

Strophostoma anom-
phala Capellini. Oligo-
cene ; Arnegg, near
Ulm, Würtemberg.

of tliese are tropica! Fossil forms are found in fresh-water deposits as old as the
Middle Cretaceous.

Gyclostomus Montf. (Fig. 929). Turbinate, with calcareous spiral operculum.
Tertiary and Recent.

Otopoma, Tudora Gray. Tertiary and Recent.

Megalomastoma Guild. Turbinate to chrysalis-shaped, usually smooth. Peristome
with thick margins ; outer lip reflected. Operculum horny. Cretaceous to Recent.
M. mumia (Lamarck).

Pomatias Studer (Fig. 930). Turreted, transversely striated, with reflected
margins and calcareous operculum. Tertiary to Recent ; palearctic.

Leptopoma Pfeiff.; Gijclophorus Montf.; Graspedopoma Pfeift'.; Gyclotus Guilding
(Fig. 931), etc. Upper Cretaceous. These genera are considered to form a distinct
family, Gyclophoridae. Strophostoma Desh. (Fig. 932). Upper Cretaceous to Miocene.

CLASS IV

GASTßOPODA

541

Family 4. Oapulidae Cuvier.

Shell cu2J-f ca])-shai)ed or oval, irregulär^ with spirally twisted apex ; in some cases
the shell is comjwsed of several depressed whorls. Body whorl very large ; aperture wide ;
operculum absent. Marine. Cambrian to Receiit.

Various genera beloiiging liere are stationary, remaining througliout nearly the
wliole of tlieir existence attached to some foreign body, to
wliich tliey gradually become accommodated in form.

Stenotheca Salter. Shell small, cap-shaped, concentrically
striated or fiirrowed, with slightly incurved apex, whicli
latter is distantly situated posteriorly. Lower Cambrian.

Capulus hungaricus (Linii.).
Pliocene ; Tuscany.

Fig. 934.

Capulus rugosus (Sowb.).
Great Oolite ; Langrune,
Calvados, i 'i

Fig. 935.

OrthonycMa elegans Barr.
Silurian (Etage E) ; Lochkow,
Bohemia.

Capulus Montf. (Pileopsis Lam.; Brocchia Bronn) (Figs. 933, 934). Irregularly
conical or cap-shaped ; apex greatly displaced backward, more or less spirally inroUed.
Aperture wide, rounded or irregulär ; internally with a horseshoe-shaped muscular
Impression. Exceedingly abundant from the Cambrian to Carboniferous, but rather
sparse from the Trias onward.

Orthonychia Hall {Igoceras Hall) (Fig. 935). Shell conical, straight or slightly
curved, often plicated. Apex but faintly spiral. Silurian to Carboniferous.

Platyceras Conrad {Acroculia Phil.) (Fig. 936). Apex bent and spirally inroUed.

Platyceras neritoides Phil.
Carboniferous ; Vis6, Belgium,

Diaphorostoma
Hall. Silurian ;
Indiana.

:. 93^.

Horiostoma harrandci Mun.-Chalm.
Lower Devonian ; Gahard, lUe-et-
Vilaine (after Munier -Chalmas).

Surface smooth, striated, plicated or covered with small spines. Young shell coiled
as in Diaphorostowa, late stages non-coiling, often spinous. Commensal on Echinoids.
Silurian to Coal Measures.

Diaphorostoma Fisher {Platyostoma Conrad) (Fig. 937). Shell composed of numerous
rapidly widening whorls. Spire low, body whorl very large. Inner lip reflected and
somewhat thickened. Aperture round, of large size. Silurian to Carboniferous.

Horiostoma Munier-Chalm. (Fig. 938). Shell ihick, spirally ribbed, with short
lateral spire, and wide umbilicus. Devonian.

Tuhina Barr. Silurian. Rothpletzia Simonelli. Tertiary.

542

MOLLUSCA

PHYLÜM VI

Hipponix Defr. (Gochlolepas Klein) (Fig. 939). Shell tliick, obliquely conical to
cup-shaped. Beak straiglit, rarely spiral, greatly removed pos-
teriorly. Aperture oval or rounded, internally with a horseslioe-
shaped miiscular imj)ression. The foot often secretes a thick,
operculiform calcareoiis disk. Cretaceous to Kecent.

Hipponix cornucopiae (Lamarck.) Calcaire
Grossier; Liancourt, near Paris. A, Shell.
B, Foot-plate.

Fig. 940.

Calyptraea (Trochita) trocJiiformis Lam. Calcaire Grossier ;
Damery, near Epernay.

Calyptraea Lam. {Galerus Gray) (Fig. 940). Shell thin, conical, with central
Spiral apex. AVhorls flattened, often spinöse. Base horizontal :
aperture wide, depressed. Cretaceous to Eecent.

Grepidula Lam. (Fig. 941). Slipper -shaped, elongate-oval, flat
or arched. Beak at the posterior end, almost marginal, somewhat
curved. Aperture greatly elongated, wide ; inner lip formed by a
thin horizontal lamella. Cretaceous to Eecent.

Crucihulum Schum. Tertiary and Recent.

Family 5. Naticidae Forbes.

Fig. 941. Shell with short spire and large hody whorl. Aperture semicircular

Crepiduia ungui- to oval, angular posteriorly, hroadly rounded anteriorly. Operculum
ceneT Tu^cany. ^°" calcareous or horny, paucispiral. Marine. Trias to Recent.

The distinction of fossil Naticidae from Naticopsis, Nerita and Ämpullaria is
attended with some difßculty, since they frequently possess nearly identical characters
in common, differing mainly in the operculum, whicli is not preserved fossil.

Sinum Bolten {Sigaretus Lam.) (Fig. 942). Shell depressed, auriform, spirally

Fig. 942.

Sinum haliotoideum
(Linn.). Miocene ; Grund,
Hungary.

Fig. 943.

A, Natica millepunctatu Lam,
Pliocene ; Monte Mario, near Roma.
-B, Operculum of N. multipunctata
S. Woodvv. Crag ; Sutton.

Fig. 944.

Natica (Ampullina) patula
Lam. Calcaire Grossier ;
Damery, near Epernay.

striated or furrowed. Spire very low, with rapidly widening whorls. Aperture greatly
distended ; operculum horny. Tertiary and Recent.

Natica Scopoli (Figs. 943-946). Globose, semi-globose, ovate or pyramidal, smooth
and lustrous, rarely spirally striated, umbilicate or not. The umbilicus, when

GASTROPODA

543

jiresent, often iiartially or entirely filled witli calliis. Aperture semicircular or oval.
Outer lip sliaip ; inner lip thickened by a callus. Excessively abundant from the

Trias onward.

Subgenera : Ampullina Lam. (Fig. 944) ;
Amaurojysis Mörch. (Figs. 945, 946) ; Polinices
Montfort ; Euspira Agassiz ; Lunatia, Cernina
Gray ; Neverita Risso, etc.

(?) Deshayesia Raul.
(Fig. 947). Like Natica,
but inner lip witb a
thick callus and den-
ticulated. Miocene and
Pliocene.

Family 6.

Xenophoridae

Deshayes.

Shell turbinate^ with-
out nacreous layer ;
whorls flat, often covered with agglutinated foreign hodies. Base concave or flat, with
a peripheral keel. Aperture ohliquely quadrilateral. Operculum horny. Silurian to
Recent.

Fig. 945.

Natiai {Ampullina)
loülemetl Lam. Cal-
caire Grossier; Da-
mery, near Epernay.

Fig. 946

Natica (Amauropsis)
biilbiformis Sowh. Upper
Cretaceous ; St. Gilgen
on Wolfgangsee, Austria.

Deslutyesia cochUaria
(Brongniart). Oligocene ;
Monte Grumi, near
Vicenza.

The Xenophoridae are an ancient family, the modern representatives of which
have acquired a high differentiation. The radula is like that of the Capulidae,
Littorinidae and Strombidae, not like that of the Trochidae. The earlier forms,
encountered in the Silurian, present a great superficial resemblance to the Paleozoic
Trochus species,

Eotrochus Whitfield (Fig. 948). Thin-shelled, turbinate, widely umbilicate.
Whorls flat, rarely with aggluti-
nated foreign particles. Base con-
cave, its periphery formed by a
compressed lamellar belt. Silurian
to Recent.

Omphalopterus Roemer. De-
pressed turbinate, widely umbili-
cate. The wide peripheral margin
at the base composed of two lamellae,
separated by a slit. Silurian.

Glisospira Billings ; Autodetus
Lindström. Silurian.

Xenophora Fischer {Phorus
Montf.) (Fig. 949). Low trochiform, narrowiy umbilicate.

Fig. 949.

Eotrochus heliacus
(d'Orb.). Upper Lias ; La
Verpilliere, near Lyons.

Xenopliora agglutinans (Lam.).
Calcaire Grossier ; Damery, near
Epernay,

Whorls usuallv covered

above with agglutinated extraneous objeots. Cretaceous to Recent.

Family 7. Ampullariidae Gray.

This family inhabits fresh or brackish water, and is found in Africa, Asia and
tropical America. Some of their shells are hardly to be distinguished from Ampul-
lina. The animal possesses a lung cavity above the riglit gill. Fossil forms occur in
fresh -water deposits of Cretaceous age at Rognac, near Marseilles, and also in the early
Tertiary.

544

MOLLUSCA

PHYLUM VI

Family 8. Valvatidae Gray.

Shell composcd of few ^vhorls, conical or discoidal, umhilicate. Ajjerture round, with
continuous 'peristome. Opercuhim horny, circular, multisjjiral.
Upper Jura to Kecent.

The genus Valvata Müll. (Fig. 950) is small, and varies

froiu turbinate to discoidal. It comprises about twenty-five

Fio. 950. Eecent species, inliabiting tlie fresh waters of Eiirope and

Valvata piscinaiis Müll. Nortli America, It is initiated in tlie Purbeck, biit does not

?ransVivanr'''' ^^'^^'' become at all abundant until tlie Tertiary.

Family 9, Viviparidae Gill.

Shell conical or ttirhinate, with thick epidermis ; imjyerforate or with narrow
umhilicus. Whorls smooth, tubulär or angular. Äpertiire rounded, oval, suh-angular
posteriorly, with continuous peristome. Operculum horny, concentrically striated, with
eccentric nucleus. Jura to Eecent.

Tliis, tlie principal genus, is
G D

Vivipara Montf. [Paludina Lam.) (Fig. 951).
abundant in fresh water a b

of all parts of the globe,
with the exception of
tropical and South
America. Several other
genera and subgenera
are . recognised, such as
Gampeloma Kaf. (Me-
lantho auct.) of North
America, comprising
mostly smooth, thick-
shelled species, with
thickened inner lip ;
Tulotoma Haldem., including forms with angular whorls, North America ; Margarya
Nev., China ; Lioplax Troschel ; Laguncula Benson ; Tylopoma, Boshovicia Brusina, etc.

Typical species of this genus are found in the Wealden clays. Vast numbers of
Vivipara occur in the Pliocene of southern Hungary, Croatia, Slavonia, Eouniaiiia
and the Island of Cos, where they are remarkable for their extreme variability.
Neiimayr has described a number of mutation series from this horizon, wliich begin
with smooth Vivipara species, and terminate with angular Tulotoma-like forms.

Fig. 951.

A, B, Vivipara hrusinae Neumayr, C, V. (Tulotoma) forbesi Neumayr.
Pliocene ; Isle of Cos. D, V. {Tulotoma) hoerneri Neumayr. Pliocene : Novska,
Slavonia.

Family 10. Hydrobiidae Fischer {Ämnicolidae Tryon).

Shell turbinate to turreted, small, usually thin, and either smooth, longitudinally
ribbed or spirally keeled. Äperture ovate ; operculum horny or calcareous, spiral or
concentric. Cretaceous to Eecent.

These are fresh or brackish water inhabitants, some of which, however, are able to
survive for a considerable period on land. It is difficult to distinguish the different
genera belonging to this family by means of shell characters alone. All the forms
are diminutive.

Bithinia Gray (Fig. 952). Thin-shelled, turbinate, with umbilical fissure.
Peristome continuous, outer lip sharp. Operculum calcareous, concentric. Wealden
to Eecent.

CLASR IV

GASTROPODA

545

Staliola Brusina. Outer lip thickened ; operculum calcareous. Cretaceoiis to

Miocene.
.1 (' Fosmrulus Neuinayr. Like tlie last, but vvitli Bpiral ribs.

Upper Miocene.
HWL z*^ Nematura Benson {Stenothyra Benson) (Fig. 953). Like

Bithinia^ but aperture contracted. Operculum calcareous, spiral.

Tertiary and Recent.

Fig. 952.

A , Bithinia tentaculata
(Linn.). Upper Mionene;
Miocic, Dalmatia. B,
Operculum of same. C,
B. gracilis Sandb. Fresh-
water Molasse ; Ober-
kirchberg, near Ulm.

Fio. 953.

Nematura ptipa (Nyst).
Oligocene ; Hackenheim,
near Alzey.

Fio. 954.

Nystia chastelii
(Nyst). Middle Oligo-
cene ; Klein-Spouwen,
Belgium.

Fm. 955.

Hydrohia acuta A.
Braun. Miocene ;
Weissenau, near
Mayence.

Nystia Tourn. {Forbesia Nyst) (Fig. 954). Outer lip reflected ; operculum
calcareous, spiral. Tertiary and Recent.

Assiminea Leach. Tertiary and Recent.

Hydrohia Hartm. {Littorinella Braun ; ToiLrnoueria Brusina) (Fig. 955). Conical
to turreted, acuminate, smootli, Aperture oval ; operculum homy, paucisj)iral.
Cretaceous to Recent. The Indusia Limestone (Lower Miocene) of Auvergne is
almost exclusively composed of the shells of H. duhuissoni Bouill. Similarly, the
Littorinella Limestone of tlie Mayence Basin, wliich is of equivalent age, is made
up of the Shells of H. acuta Braun. Strata in the fresh-water limestone of Nördlingen
are charged with H. trochulus Sandb. ; and the Upper Eocene marl of St. Ouen is
filled with the remains of H. fusilla (Prev.).

Other genera and subgenera closely related to the foregoing are Bythinella Moq. ;
Amnicola Gould ; Belgrandia and ^ ^ ^

Lartetia Bourguignat ; Lappare^itia
Berthelin.

Pyrgula Christofori and Jan.
(Fig. 956, Ä). Turreted, whorls
spirally keeled or ribbed. Peristome
continuous. Tertiary and Recent.

Genera allied to the last are

Micromelania Brus. (Fig. 956, 5) : , „

. rx 1 /-r-. r, Jy. ^» Py^gula eugeiiiae Neumayr.

Mohrensternia ötol. (Fig. 956, C); Upper Miocene; Arpatak, Transyl-

Pyrgidium Tournouer ; Prososthenia SSi (N»ima"r' Uppi? mS"!

Neumayr. Tertiary. Miocic, Dalmatia. C, Mohrensternia

T -±1 1 i, ry- 1 /■x^• nc^7\ m^«ta Andfzewsky. Congerien Stage

Llthoghjphus Ziegl. (Fig. 957). (Miocene) ; Inzensdorf, near Vienna.

Globose or ovate, with short spire ;

rather thick and aolid. Aperture large, obliquely oval ; inner lip thickened.
Tertiary and Recent ; Europe. Similar forms, Somatogyrus Gill, and Flumincola
Stimpson, occur in North America. There are other related genera in south-eastern
Asia and South America.

Fio. 956.

Fio. 957.

Lithoglyphus fusciis
Ziegler. Upper Mio-
cene ; Malino, West
Slavonia.

Family 11. Rissoidae Troschel.

Shell small, thick, turhinate to turreted, usually ribbed or spirally striated, rarely
smooth. Aperture oval, angular posteriorly, often with anterior canal. Operculum
homy, paucispiral. Jura to Recent.

Eissoina d'Orb. (Fig. 958).
VOL. I

Turreted, transversely ribbed, rarely smooth : outer

2 N

546

MOLLUSCA

phylü!m vi

lip arcuate, generally tliickened

aperture somewliat iiotclied or effuse at tlie base.
Dogger to Recent ; mainly
Tertiary.

Rissoa Frem. (Fig. 959).
Turreted, transversely ribbed
or cancellated, aperture eutire
below. Jura to Recent.

FiCx. 958.
A, Rlssoina amoena Zitt. Tithon-
ian ; Stramberg, Moravia. B, B.
(Ifcussata Montf. Miocene; Steina-
brunn, near Vienna.

Fio. 959.

A, Risfioa turbinata (Laiii.).
Oligocene; Weinheim, near
Alzey. B, R. (Alvania) mon-
tagui Payr, Miocene ; Steina-
brunn, near Vienna.

Family 12. Turritellidae
Gray.

Shell turreted, with high
acuminate spire. TFhorls numerous, iisually spirally rihhed or striated. Aperture oval,
round or quadrangular, sometimes with faint anterior canal. Outer lip thin, peristome
discontinuous. Operculum horny, multispiral Marine. Trias to Recent.

Turritella Lam. (Figs. 960, 961). Spire very high; aperture oval or rounded
quadrilateral ; outer lip thin, excavated behind, and
slightly produced in front. Trias to Recent ; maximum
in Tertiary. The older Mesozoic species are usually
small.

961). Like the last,

Subgenera : Mesalia Gray (Fig,
but aperture with shallow canal,
Tertiary to Recent.

Protoyna Baird
{Proto p.p. Defr.).
Aperture oval, an-
teriorly with canal-
like contraction,

which is surrounded
externally by a thick
swelling. Tertiary
and Recent. P.
cathedralis Brgt.

Glauconia Gie-
bel (Omphalia

Zekeli ; Gassiope

Coq.) (Fig. 962).

Thick-shelled, coni-

cal or turreted,

narrowly umbili-

cate. Whorls

spirally ribbed, rarely smooth. Aperture oval, with faint canal
anterior and median emargination. Abundant in the Cretaceous.

and twisted inner lip.

Fig. 960.

A, Turritella turris Bast. (T.
ir<'e?(raZiet. nonLinn.). Miocene
Moljisse ; Eriningen, near Ulm.
B, T. imhricataria Lam. Cal-
caire Grossier ; Grignon, near
Paris.

Turritella (Mesalia)
multisulcata Lam.
Eocene ; Calcaire
Grossier ; Grignon,
near Paris.

Fig. 962.

Glauconia kefersteini
Goldf. Middle Cre-
taceous ; Dreistätten,
near Wiener-Neust.

outer lip with

Family 13. Vermiculariidae, novum. {Vermetidae Adams).

Shell tubulär, the earlier whorls spiral, the later ones irregularly twisted, free or
attached. Aperture round; operculum horny, sometimes ivanting. Carboniferous to
Recent.

Some fossil Vermetidae are liable to be mistaken for Serpulidae, but differ from
them nevertheless in the structure of the shell and spiral protoconcli. The determina-
tion of the few Paleozoic and Mesozoic forms is uncertain.

Vermicularia Lam. {Vermetus Daudin) (Figs. 963, 964). Shell usually attached,
irregularly tubulär, internally vitreous, and often with septa. Carl)oniferous (?) to
Recent. Abundant in the Tertiary.

CLASS IV

GASTROPODA

.47

Subgenera : Thylaeodes Guettard (Fig. 963) ; Petaloconchus Lea (Fig. 964). Tertiary and
Recent.

Siliquaria Brug. (Fig. 965). Shell
free, coiled in a loose spiral. Aperture
lateral, and with a slit whicli continues
as a fine cleft or row of pores tlirougli-
out the entire length of tlie shell.
Cretaceous to Recent.

Fig. 963.

Vermicularia {Th ylacodes) arenaria
Linn. Miocene ; Grund, near Vienna.

V2.

V. (Petaloconchus) intorta Lam.
Pliocene ; Montespertoli, near
Florence. Some of the tubes are
fractured i and show the internal
lamellae.

Fig. 965.

Siliquaria striata

Desh. Calcaire Grossier ;
Chaussy, near Paris.

Family 14. Oaecidae Adams.

Shell small, discoidal in early stages, later becoming tubulär. TJie decollated yroto-
conch replaced by a septum. Operculum round, horny. Tertiary and
Recent.

Gaecum Flem. Abont one hundred Recent and twenty Tertiary
species are known.

Family 15. Melaniidae (Lamarck) Gray.

Shell turreted to oval, with thick, dark-coloured epidermis. Apex
usually truncated and corroded. Aperture oval, sometimes canali-
culate. Operculum horny, spiral. Jura to Recent.

Living species inhabit fresh, or more rarely brackisli, waters of
Southern Europe and the warmer zones of Africa, Asia and America.

Melania Lam. {Thiara Bolten) (Fig. 966). Shell smooth or
spirally striated, or with transverse ribs or nodes. Aperture oval,
anteriorly rounded. Upper Jura to Recent.

Stomatopsis Stäche. Whorls platform-like, with strong trans-
verse ribs ; aperture rounded, with entire, thickened and reflected uim!^ ^ ^^^
margins. Lowermost Eocene (Cosina Beds) ; Istria and Dalmatia.

Pyrgulifera Meek (Hautkenia Munier-Chalm.) (Fig. 967). Shell thick, elongate-
oval, with platform-like, transversely ribbed, and spirally striated whorls. Aperture

Fio. 966.
Melania eseheri

Brongt.

Miocene ;
near

548

MOLLUSCA

THYLUM VI

oval, sometimes with very faint canal. Upper Cretaceous of Europe and North
America,

Paramelania Sniitli. Resembles tlie preceding, Living in Lake Tanganyika.

Fascinella Stäche ; Goptostylus Sandb. ; Faunus Montf. ; Hemisinus Swainson.
Upper Cretaceous, Eocene and Recent.

Melanopsis Fer. (Figs. 968-970). Shell oval to turreted, smooth or ornamented.

Fig. 967.

PyrguUfera pich-
leri (Hoernes).
Upper Creta-
ceous; Ajka,
Hungary.

Fig. 968.

MeloMopsis gdllo-pro-
vincialisMsLth. Upper-
most Cretaceous ; Mar-
tigues, near Marseilles.

Melanopsis mar-
tiniana Fer. Mio-
cene ; Nussdorf,
near Vienna.

Fig. 970.

Melanopsis {Can-
thidomus) acanthica
Neumayr. Upper
Miocene; Miocic,
Dalmatia.

Fig. 971.

Pleurocera stfomhi-
formis (Schloth).
Wealden ; Oster-
wald, Hannover.

Upper

Base of columella trimcated ; aperture with short canal ; inner lip callous.
Cretaceous to Recent. Remarkably abundant in the Miocene and Pliocene.

Pleurocera Raf. (Fig. 971). Like Melania, but aperture with faint canal, and
outer lip sinuous. Cretaceous to Recent ; occurs only in North America.

Goniohasis Lea ; Änculosa Say {Leptoxis Raf.) ; Ptychostylus Sandb. Wealden.
The first two occur Tertiary and Recent in North America only.

Family 16. Nerineidae Zittel.
Shell turreted, pyramidal or ovate, perforate or imperforate. Aperture anteriorly

A B C D

Fio. 97:

Trochalia consohrina Zitt.
Tithonian ; Stramberg, Mor-
avia. Longitudinal section.

Fig. 973.

A, Nerinea defrancei d'Orb. Coral-Rag ; Coulanges sur Yonne. B, N.
(Hkitata d'Orb. Coral-Rag ; Oyonnax, Ain. C-E, N. hoheneqgrri Peters.
Tithonian ; Stramberg, Moravia. (', 2/,,. j), Vi- E, Longitudinal section.

CLASS IV

GASTROPODA

.49

loith short canal or shallow notch. Golumella and Ups with strong folds, contimious
throughoid the eniire length of the spire. Outer lip thin, posteriorly luith ßssure-like
incision, which leaves a small slit-hand immediately heneath the suture on all the whorls.
Marine. Trias to Cretaceous.

Aptyxiella Fisch. (Äptyxis Zittel, non Troschel). Turreted, very slender, im-
perforate. Aperture qiiadrangular ; inner and oiiter Ups witliout folds ; columella
somewhat thickened. Trias to Upper Jura.

Trochalia Sharpe {Gryptoplocus Pict. and Camp.) (Fig. 972). Turreted to
pyramidal, usually smooth and imperforate. The inner lip only has a strong, simple
ibid. Jura and Cretaceous.

Nerinella Sharpe (Pseudonerinea Loriol). Turreted, imperforate. Outer lip and
sometimes also the columella with a simple fold. Jura.

Nerinea Defr. (Fig. 973). Turreted or pyramidal, usually imperforate. Columella
invariably, and inner and outer lips generally, with simple folds. Jura and Cretaceous ;
maximum in the Coral-Rag (Upper Jura).

Ptygmatis Sharpe (Fig. 974). Like the last, except that the folds on both lips
and the columella are complicated by second-
ary constrictions and branchings. Jura and
Cretaceous.

Itieria Math. (Fig. 975). Elongate-oval,
usually umbilicate. Spire short, sometimes
insunken, Body whorl very large, more or
less enveloping the preceding. Columella
and both lips with folds. Jura and Cre-
taceous.

Family 17. Cerithiidae Menke.

Shell turreted; aperture elongated oval, or
quadrilateral, anteriorly with short canal.
Outer lip often thickened and reflected, or thin
and sharp. Columella sometimes with one
or tivo folds. Operculum horny, spiral.
Marine and hrackish water. Trias to Recent.

Fio. 974.

Ptygmatis pseudo-
bruntrutana Gem-
mellaro. Tithonian;
Inwald, Carpathia.
Vertical section.

Fig. 975.

Itieria staszycii Zeuschner.
Tithonian ; Inwald, Car-
pathia.

More than 1000 living, and about 500
fossil species are known, the latter being most numerous in the Eocene. The earliest
forms are usually of small size, and have a nearly entire peristome.

Gerithinella Gemm. (Fig. 976). Shell turreted, slender. Whorls numerous, flat,

ornamented with spiral ribs or rows of small nodes.
Aperture quadrilateral, with very faint canal.
Jura.

Cryptaulax Täte (Pseudocerithium Cossmann).
Small, turreted. Whorls with spiral ribs or rows
of nodes and transverse folds. These last usually
run continuously in a somewhat oblique direction
from one whorl to the next. Aperture oval or
quadrilateral, with scarcely perceptible canal.
Trias and Jura.

Ceritella Morris and Lyc. (Fig. 977). Trias
and Jura. Fibula Piette (Fig. 978). Trias to
Cretaceous. Pseudalaria Huddlest. ; Ditretus Piette. Jura.

Exelissa Piette (Fig. 979). Very small, turreted ; whorls with strong, continuous

Fi(!. 976.

Cerithinella aiinata
Goldf. Torulosus
Beds (Middle Jura) ;
Pretzfeld, Franconia.

Fig. 977.

Ceritella conica
Morris and Lyc.
Great Oolite ; Min-
chinhamptoii, Eng-
land.

550

MOLLUSCA

PHYLUM VI

transverse ribs and spiral Striae. Aperture contracted, rounded, without canal, some-
times slightly separated off, and with continuous peristome. Abundant in the Jura.
Bittium Leacli (Fig. 980). Turreted, with granulated spiral ribs,
and numerous transverse costae. Aperture with short, straight canal ;
outer lip sharp. Jura to Kecent. Abundant in the Tertiary.
Triforis Deshayes ; Gerithiopsis Forbes. Tertiary and Recent.

Eustoma Piette. Aperture with
long canal, which is often closed,
however, by margins of the inner
and outer lip. Inner lip callous
and strongly dilated ; outer lip
expanded. Jura.

Gerithium Brug. (Figs. 981,
982). Turreted, imperforate, with-
out epidermis. Aperture oblong,
ovate, with backwardly curved
canal ; outer lip often soinewhat
reflected. Columella concave, fre-
quently with one or two folds.
Certain Tertiary species attain a length of half a metre (C. giganteum). Jura to
Recent ; maxinium in Eocene.

Subgenera : Vicarya d'Arch. ; Glava Martyn (Fig. 982) ; Bellardia Mayer, etc.

Potamides Brongt. (Figs. 983, 984). Turreted, with epidermis; aperture with
emargination or faint canal. Inhabits only brackish water or
estuaries. Cretaceous to Recent.

Fig. 978.

Fibula undulosa
Piette. Bathon-
ian ; Bparcy,
Aisne.

Fig. 979.

Exelissa strangu-
lata (d'Arch.).
Bathonian ;
Eparcy, Aisne.

Fig. 980.

Bittium plicatum
Brug. Oligocene;
Ormoy, near Etampes,
France,

Fig. 981.

Gerithium serratum
Brug. Calcaire Gros-
sier ; Damery, near
Epernay.

Fig. 982.

Cerithium {Glava)
nudum Lam. Eocene ;
Chaumont, near Paris.

Potamides (Tympano-
tomus) margaritaceum
Brocchi. Oligocene ;

Hackenheim, near Alzey.

Subgenera : Tympanotomus Adaras (Fig. 983) ; Pyrazus, Telescapium Montf.
Swains. ; Lampania (Fig. 984) and Pyrenella Gray ; Sandbergeria Bosq.

Fig. 984.
Potamides (Lampania)
pleurotomides Desh.
Middle Meeressand ;
Mortetbntaine, 8eine-et-
Oise.

Cerühidea

Family 18. Aporrhaidae Philippi.

Shell fusiform, turreted or conical ovate. Aperture produced anteriorly in a canal.
Outer lip expanded in a wing-like or digitiform fashion^ or thickened. Operculum horny.
Marine. Jura to Recent ; maximum in Jura and Cretaceous.

Älaria Morris and Lyc. (Figs. 985-988). Shell turreted ; aperture with long or
Short canal. Outer lip not overriding the last whorl, digitated or winged. Spire

CLASS IV

GASTROPODA

551

and body whorl often retaining tiaces of apertures at earlier stages. Veiy abimdant
in Jura and Cretaceons.

Subgenera : Dicroloma Gabb ; Anchura Conrad (Fig. 987).
Cretaceous. Diempterus Piette. Jura.

Jura and

Fig. 985,

Alaria myurus Deslongch.
Lower Oolite ; Bayeux, Cal-

FiG. 987.

Fig.

Alaria armata Morris

and Lyc. Great Oolite; Alaria (Anchura) cari-

Minchinhanipton, Eng- nata Mant. Gault ;

land. . Folkestone, England.

Fig. 988.

Spinigera semicarinata
(Goldfuss). Callovian ;
Montreuil - Bellay,
Maine-et-Loire.

Spinigera d'Orb. (Fig,
rows of spines. Jura.

Aporrhais Da Costa {Ghenopus Phil.) (Figs.
989-991). Like Alaria, but niargins of aperture
elongated posteriorly in a canal, which remains
either attached to tbe spire, or extends free froiu
the sanie. Outer lip expanded, digitated or lobed.
Jura to Recent.

Wliorls keeled and ornamented with two opposite

Subgenera : AUpes Conrad ; ArrJioges, Tessarolax^
Helicaulax Gabb ; Ceratosi'phon Gill ; Cuphoselenus,
Malaptera Piette ; Pterocerella Meek ; Dimorphosoma
St. Gardner (Fig. 990) ; Lispodesthes White (Fig.
991). Jura and Cretaceous.

Fi(i. 989.

Aporrhais tridaciylus A. Braun. Oligo-
cene ; Hackenheim, near Creuznacli.

Fk;. 990,

Aporrhais (Dimor-
phosoma) calcarata
Sowb. Upper
Greensand ; Black -
down, England.

Fig. 991.

Aporrhais (Lispodesthes) rettssi Geinitz
var. viegaloptera Reuss. Pläner ; Postelberg,
Boheinia.

Family 19. Strombidae d'Orbigny.

Shell conical, turreted or fitsiform, with acuminate spire. Aperture canaliculate ;
outer lip often expanded, anteriorly with an emargination. Operculum horny. Jura
to Recent.

Although the shells of this family are excessively variable, the soft parts of the
animals exhibit great uniformity of structure.

552

MOLLUSCA

PHYLUM VI

Harpagodes Gill (Fig. 992). Sj^ire sliort, body wliorl very large. Canal long,
reflected. Outer niargin produced in a nuniber of tubulär spinous processes, the
posteriormost of wliicli rests against the spire and extends
nearly to the apex. Jura and Cretaceous.

Fig. 992,

Harpagodes oceani Brongt.
Kimmeridgian ; Lindner Berg,
near Hannover.

Sirombus crassüahrum Zitt. Gosaii-
Cretaceous ; St. Gilgen, Austria.

Pterocera Lam. {Hepta-
dactylus Klein). Spire
sliort ; canal beut sideways.
Outer margin wing - like,
with tubulär spinous pro-
cesses, beneath the niost
anterior of which is a deep
notch. Kecent.
Pterodonta d'Orb. ; Thersitea Goq. ; Pereiraea Crosse. Miocene.
Stromhus Linn. (Oncoma Mayer) (Fig. 993). Shell ovoid, tuberculose or spinöse,
solid ; spire with several whorls ; body whorl very large. Aperture
elongate, obliquely truncated and channelled anteriorly, canaliculate
posteriorly. Outer margin dilated in wing -like fashion, usually
thick, often produced behind, sinuate and sometimes channelled
in front. Columellar border simple, enamelled. Cretaceous to
Recent.

Pugnellus Conrad. Cretaceous. Struthiolaria Lam. Tertiary
and Recent.

Seraphs Montf. (Terebellum Lam.) (Fig. 994). Shell elongate,
sub-cylindrical ; spire short, summit obtuse. Body whorl very
large, smooth or striated. Aperture longitudinal, narrow pos-
teriorly, and slightly dilated anteriorly ; canal short. Outer
margin thin, simple, obliquely truncated anteriorly, sometimes pro-
longed in the spire posteriorly by a callosity. Columellar border
smooth, straight. Tertiary and Recent.

Rostellaria Lam. Spire high, whorls smooth. Aperture pro-
Seraiihs sopituin ^^^^^ anteriorly in a beak-like canal, and continued posteriorly
(Brander). Caicaire as a narrow Channel resting on the spire. Outer margin with
near Pari's. ' denticulate processes, notched anteriorly. Late Tertiary and Recent.

Hippochrenes Montf. {Gyclomops Gabb) (Fig. 995). Like the last,
but outer margin expanded in wing-like fashion, and destitute of processes. Upper
Crataceous and Eocene.

CLASS IV

GASTROPODA

553

Bimella Agassiz {Isopleura Meek) (Fig. 996). Surface cancellated. Outer lip
with tliickened inargin, entire or
creniüated. Upper Cretaceous to Re-
cent.

Orthaulax Gabb. Spire wholly
iiivolute and hidden. Oligocene ;
Antilles.

Family 20.
Oolumbellariidae

Fischer,

Fig. 996.

A, liimella fismrella (Lam.).
Calcaire Grossier ; Damery,
near Epernay. B, lt. hartonensis
(Sowb.). Calcaire Grossier;
Griguon, near Paris.

Shell thick, elongated
oval, with short conical
spire, and large, spirally
ribbed, frequently cancel-
lated body lohorl. Äper-
ture narrow, anteriorly with short canal, and pos-
teriorly with a canal directed obliquely outwar ds.
Inner lip callous, outer lip often thickened, denti-
culated or somewhat reflected outwardly. Jura and
Cretaceous.

HijipoiJiKiif^ iii}ii(hisoni Dc^h. Calcaire
Grossier ; Damery, neai Epernay.

Fi(!. 997.

^ , ^ „ . , Fig. 998. Fig. 999.

Columbellaria coral-

lina (Quenst.). Zittclia crasslsaima Fetersia costata

Ooral-Rag; Nat- (Zitt.). Tithonian; Gemm. Tithonian ;

theim. Stramberg. Palermo.

Columbellaria Rolle (Fig. 997). Surface covered with nuraerous spiral ribs,
sometimes cancellated. Aperture long and narrow, broadening somewhat anteriorly.
Outer lip denticulated internally, not thickened, somewhat reflected. Anterior and
posterior canals short. Upper Jura.

Zittelia Gemm. (Fig. 998). Like the last, but aperture very narrow or cleft-like.
Outer lip much thickened in the middle. Tithonian.

Golumbellina d'Orb. Cretaceous. Petersia Gemm. (Fig. 999).
Tithonian.

Family 21. Oypraeidae Gray. Cowries.

Shell ovate, convolute. Spire short, nearly or completely covered. in
the adult by the very large body ivhorl. Aperture of equal length ivith
the shell, narroio, anteriorly and posteriorly produced in a usually short
canal. Outer lip inflected. Operculum wanting. Upper Jura to
Recent.

Recent Cypraeidae of which about 210 species are known,
inhabit principally the warmer seas. They are often remarkable for
their beautiful coloration, and sometimes attain considerable size. Jurassic species are
sparse ; Tertiary ones rather more abundant.

Cypraea Linn. (Fig. 1000). Ovoid, ventricose, enamelled, smooth, lirate or

I !iprn,,f Silin, r,s

A. Jirauii. Uligc
cene ; Weinliein
near Alzey.

554

MOLLUSCA

PHYLUM VI

tuberculate ; spire exposed or enveloped. Aperture narrow, exteiiding the whole
length of the shell, and canaliciilate at each extremity. Inner lip and the inroUed

oiiter lip generally crennlate. Jura ((7. titonica
Stefan i) to Kecent.

Trivia Gray (Fig. 1001). Like the preceding,
but smaller, and sculptured with raised transverse
riblets. Anterior Channel not prolonged, wide and
slightly reverted. Tertiary and Eecent.

Erato Kisso (Fig. 1002). Sniall, ovoid or pyri-
form, with short conical si)ire. Aperture narrow.
Inner lip smooth, except for anterior columellar
Canal notch-like, broad. Cretaceous to Recent.

^

Fig. 1001.

Trivia affinis (Duj.),
Miocene ; Pont
levoy, Touraine.

Fig. 1002.

Erato laevis Don.
Miocene ; Nieder-
leis, Austria.

folds ; outer lip denticulate.

Family 22. Ovulidae Fleming.

Like the Gypraeidae^ except that the spire is convolute instead of produced and
covered, and the marginal teeth
of the radula are peculiarly
modified. Tertiary and Recent.

Ovula Brug. Shell ovate
or fusiform, the spire completely
enveloped. Aperture produced
anteriorly and posteriorly as a
canal. Inner lip smooth ; the
outer reflected, smooth or
denticulated. Tertiary and
Recent,

Gisortia Jousseaume (Fig.
1003). Large, thick - shelled,
ovate, with short convolute
spire. Surface typically keeled
or coarsely tuberculate. Body
whorl with a blunt ridge ;

aperture anteriorly and posteriorly with a short canal.
gigantea (Goldf.).

Pedicularia Swainson. Sessile on corals. Miocene to Recent.

Fig. 1003.

Gisortia tuberculosa Duclos. Lower Eocene (Londinion) ;
Ciiise Lamotlie.

Eocene. G. (Strornbus)

Family 23. Cassididae Adams.

Shell thick, inßated, glohularly ovate, sometimes varicose ; spire short, hody whorl

very large. Aperture narrow, elongate, anteriorly
with short canal. Inner lip resting on an exten-
sive callus, sometimes granulated or wrinkled.
Outer lip more or less thickened. Operculum horny,
with marginal nucleus. Marine. Upper Creta-
ceous to Recent.

Galeodea Link {Morio Montf. ; Gassidaria
Lam.) (Fig. 1004). Shell ventricose, not varicose.
Canal long, twisted, reverted or bent sidewise.
Inner lip greatly expanded, outer lip reflected,
often crenulate. Columellar border jDÜcate.
Upper Cretaceous to Recent ; maximum in
Eocene.

Fig. 1004.
Galeodea carinata
Lam. Calcaire Gros-
sier ; Grignon, near
Paris.

Fig. 100.-

Galeodea (Sconsia)
amhigua (Solander).
Oligocene ; Lattorf,
near Bernburg.

CLÄSS IV

GASTROPODA

555

Subgenus : Sconsia Gray (Fig. 1005). Last wliorl with varix ; canal sliort and straight.
Upper Cretaceous to Recent.

Gassis Lam. (Fig. 1006). Shell ovoid, ventricose, having
irregulär varices. Spire sliort, apertiire elongate. Oiiter
lip thickened, refiected, nsually denticiüate in the iiiterior.
Inner lip callous, expanded, denticulate, wrinkled or granu-
late. Canal very sliort, broad, sharply recurved, directed
upward posteriorly. Tertiary and Recent.

Fig. 1006.

Cassis sahuron Lam. Miocene ;
Gainfahrn, near Vienna.

Cretaceous to

Family 24. Doliidae Adams.

Shell thin, inflated. Spire very short, hody whorl very
large, longüudinally ribhed or cancellated. Apertur e wide,
oval ; canal straight or curved. Oper-
culum ahsent. Cretaceous to Recent.

Tonna Brünnicli {Bolium Lam.).
Spirally ribbed. Outer lip notched
internally ; canal short, obliquely directed.
Recent.

Pyrula Lam. {Ficula Swainson) (Fig. 1007). Spirally
ribbed, grooved or cancellated. Aperture very wide ; outer lip
sharp ; canal long, broad, straight. Lower Cretaceous to
Recent ; maximum in Tertiary.

Family 25. Nyctilochidae Dali.

Fig. 1007. Shell thicJc, ovate to fusiform, with epidermis. Spire

Pyrula reticuiata (Lam.). moderately high, lühorls varicose, aperture ivith thickened outer
Vienna, ' ' ^ ^Wi ^^^ open, straight or slightly hent canal. Operculum horny,

with marginal nucleus. Cretaceous to Recent.

Nyctilochus Gistel {Tritonium Link ;
Triton, Lotorium Montf.). Spire elon-
gated. The varices do not run con-
tinuously over more than a few whorls.
Columella and inner lip callous or
granulated. Outer lip thickened inter-
nally and notched. Cretaceous to
Recent ; abundant in the Tertiary.

Eugyrina Dali (Fig. 1008). Oligo-
cene to Recent.

Distortrix Link {Persona Montf.).
Tertiary and Recent.

Bursa Bolten {Ranella Lam.) (Fig.
1009). Like Nyctilochus, but with two
opposite varices, whicli are continuous
over all the whorls. Tertiary and
Recent.

Fig. 1008.

Eugyrina flandrica de, IUiih

Kon. Oligocene ; Wein- Brocclii.

heim, near Alzey. Vienna.

Fig. 1009.

(Aspa) marijin'ita
Miocene ; Grund, near

Superfamily 4. RACHIGLOSSA Gray.

Radida reduced to three teeth or to one tooth in a transverse series.

These are carnivorous marine fornis, which have their Initiation in the Mesozoic,
become somewhat numerous in the Cretaceous, and form an important element of the
Tertiary and Recent faunas.

556

MOLLUSCA ■ PHYLUM VI

Family 1. Columbellidae Tioscliel.

Shell small, ovate to fusiform, covered with epidermis, im2)erforate. Äperture narrow,
canal short. Outer Up denticulated internally, thickened in the middle.
Tertiary and Eecent.

The typical genus, Golumhella Lamarck (Fig. 1010), attains its
niaximum distribution in the Tertiary and Eecent seas. It is divided
into a number of subgenera.

Fig. 1010.

Columbella curia
Duj. Miocene ;

Family 2. Buccinidae Troschel.

Lapugy, Transyl
i^ania.

Shell elongate-oval, covered with epidermis. Äperture ivide, with
short canal. Outer Up sharp or thickened. Operculum horny. Cretaceons
to Recent.

Buccinum Linn, Infiated, smooth or transversely ribbed. Spire moderately
high ; äperture wide ; canal short, wide, open. Outer lip sharp and thin, inner lip
somewhat callous. Distributed principally in waters of the niore
northerly zones {B. undatum Linn.). Fossil in the Crag and
Pleistocene.

Cominella Gray (Fig. 1011). Usually spirally ribbed. The last
whorl somewhat depressed beneath the suture, so that the äperture
forms a small groove posteriorly. Outer lip sharp or crenate inter-
nally. Upper Cretaceous to Recent.

Pseudoliva Swains, (Fig. 1012). Like the last, but outer lip

with a small basal tooth or notch which ^ . „

, 1 1 T 1 T Commella casstaaria

corresponds to a groove on the body whorl. a. Braun, oiigocene;
Upper Cretaceous to Recent.

Bivona {Pisanella v.

Fig. 1011.

Hackenheim,

Alzey.

Koenen ;
Taurinia Bellardi). Elon-
gate-ovoid, spire moder-
ately high. Whorls
smooth or spirally
striated. Outer margin
thickened, notched inter-
nally. Tertiary and Re-
cent.

Gantharus Bolten
(Pollia Gray ; Tritonidea

Fig. 1012. Fig. 1013. Fig. 1014. SwaillS.) (Fig. 1013).

Pseudoliva zitteli Petliö. Gantharus sublavatus Ehurna caronis Oval, inilated ; spire and

Upper Cretaceous ; Fniska (Bast.). Miocene; Enz- (Brongt.). Eocene ; aperture of about equal

Gora, Hungary. esfeld, neartVienna. Ronca, nearVicenza. , ^t p ■,^

length ; suriace usually
spirally ribbed and transversely folded. Columella often with weak transverse folds ;
outer margin thickened, crenate internally. Aperture posteriorly with a short canal.
Tertiary and Recent.

Phos Montf. Shell elongate, bucciniform, turriculate ; spire sharp, elevated,
whorls ornameiited with prominent longitudinal costae, and less salient spiral threads
and sulci, often varicose. Aperture oblong ; outer margin lirate within. Columella
excavated, plicate in front ; canal short, slightly twisted. Tertiary and Recent.

Ehurna Lam. {Dipsaccus Klein) (Fig. 1014). Resembling Nassa, but smooth,
perforate, and with deeply incised sutures ; outer margin sharp. Tertiary and Recent.

Nassa Lam. {Älectrion Montf.) (Fig. 1015). Ovate, inflated. Aperture with short,
reverted canal ; inner lip callous, expanded ; outer margin usually crenate internally.

CLASS IV

GASTROPODA

Sparse in Upper Cretaceous and Eocene, abundant in Miocene and Pliocene ; living
species exceediiig 200 in number, and distiibuted in numerous suljgenera. .

Gyclonassa Agassiz ; Gyllene Gray ; Truncaria Adams ; Buccinopsis Conrad.
Tertiary and Recent.

Ghrysodomus Swains. {Neptunea p.p. Bolten). Elongate-ovoid, inflated, sometimes
sinistral, witb rather short and moderately bent canal. Cretaceous to Recent. C.
contrarius Lam. Crag.

Siphonalia, Zemira, Metula Adams ; Euthria Gray ; Hemifusus Swainson (Fig.
1016). Tertiary and Recent. Mitraefusus and Genea Bellardi. Neocene.
Melongena Schum. {Pyrula
Lam. p.p.; Myristica Swains.) (Fig.
1017). Pyritbrm, inflated, with
short spire. Body wliorl large,
longitudinally striated and beset
with nodes or rows of spines. Inner

Fig. 1015.

Nassa clathrata Brocchi,
Pliocene ; Larniano, Tus
eany.

Fig. 1016.
Hemifusus subcarinrüus
(Lam.). Eocene (Sables
moyens) ; Senlis, Seine-
et-Oise.

Fig. 1017.
Melongena cornuta Agassiz, Miocene ; Bordeaux.

Fio. 1019.

Strepsidura ficulnea
(Lam.). CalcaireGrossier;
Damery, near Epernay.

lip smooth; aperture gradually becoming merged into the short and wide canal.
Tertiary and Recent.

Bu^con Bolten {Fulgur Montfort). Tertiary and Recent.

Tudicla Bolten (Fig. 1018). Resembles FuUjur but has a straight and very long
canal ; inner lip with a fold. Cretaceous to Recent.

Strepsidura Swains. (Fig. 1019). Spire short ; body whorl inflated, tmnsversely
ribbed : canal curved. Eocene and Miocene.

Family 3. Muricidae Tryon.
Shell thick Spire moderately high ; whorls with transverse swellings, ribs or folia,
and frequently spinöse.

Aperture rounded or oval; canal more or less elongateJ^

558

MOLLUSCA

PHYLUM VI

ivholly or partially covered hy margins of the inner and outer Ups. Operculum horny.
Cretaceous to Eeceiit.

Murex Linn. (Figs. 1020-1022). Shell roimded, spire prominent. Surface with at
least three, often more than tliree varices or transverse rows of spines or nodes on each

whorl. Apertiire ovate ; inner lip smooth, outer lip
thickened. Canal much prolonged, partially closed,
usually spinöse. Cretaceons to Kecent.

Fig. 1020.

Murex (Phyllonotus) sedgwicki Micht.
Miocene ; Gainfahrn, near Vienna.

Fig. 1021
Murex spinicosta Bronn,

Fig. 1022.

Murex (Purpura)
tricarinatus Lam. Eo-

FiG. 1023.

Typhis tubifer
Montf. Calcaire

Miocene ;
Vienna.

Baden near cene ; Damery, near Grossier; Grignon,

Epernay.

near Paris.

Subgenera : Haustellum Klein ; Rhinacantha Adams ; Chicoreus, Phyllonotus (Fig. 1020)
Montfort ; Purpura Martyn {Pteronotus Swainson) (Fig. 1022) ; Tritonalia Fleming {Oeinehra
Leacli), etc.

Typhis Montf. (Fig. 1023). Like Murex, but with hollow spines. Canal short,

completely closed. Upper Cretaceous to Ee-
cent.

Trophon Montf. Spire high. Longitu-
dinal ribs replaced by thin lamellae. Canal
open, somewhat curved. Tertiary and Eecent.

Family 4. Thaisidae Dali.

Shell thick, usually ovoid ; spire short,
hody whorl large. Aperture ivide, inner lip
and columella more or less flattened ; canal
short. Operculum horny. Cretaceous to Ee-
cent.

Fir 1024 ^^ '

Fig. 1025. Thais Bolten (Purpura Brug.) (Fig. 1024).

Raijana laxecarinata Micht. Imperforate ; body whorl with transverse
OUgocene; Santa Giustina, ^ibs or nodes. Aperture oval, columella flat-
tened, smooth. Tertiary and Eecent.
Bapana Schum. (Fig. 1025). Like the preceding, but perforate. Inner lip callous,
expanded. Cretaceous to Eecent.

Lysis Gabb ; Stenomphalus Sandberger. Cretaceous and Tertiary.
Bistrum Montf. {Ricinula Lam.) ; Äcanthina Fischer de Waldheim {Monoceros
Lam.) ; Goncholepas Lam. ; Gymia Mörch, etc. Tertiary and Eecent.

Thais exilis
Partsch. Mio-
cene ; Möllers-
dorf, near Vienna.

ÖASTROPODA

559

Family 5. Fusidae Tryon.

Shell turreted, fusiform or ovoid, generally loithout varices. Canal more or less
elongated. Inner lip smooth, or with weak columellar folds ; outer margin thin. Oper-
culum horny. Jura to Recent.

These sliells are sparse in tlie Upper Jura and Cretaceous, but abundant in tlie

Fig. 1026.

Fususlongirostris Fio. 1027. Fio. 1028.

Brocchi. Miocene ; Clavella longaevus ham. Sycumbulbiformis (Lanu), C&l- Fig. 1029.

Baden, near Eocene ; Damery, near caire Grossier ; Grignon, near Fasdolaria tarbelliana Grat.

Vieniia. Epernay. Paris. Miocene ; Grund, near Vienna.

Tertiary and Recent. The animal difFers somewhat from that of the Buccinidae and
Muricidae.

Fusus Lam. {Fusiniis Raf. ; Colus Humph.) (Fig. 1026). Shell narrow, elongate ;
spire acuminate. Aperture ovate ; canal very long, straight, open. Outer niargin
thin, sometimes crenulate, and often striate within ; columella smooth. Rare in
Upper Jura and Cretaceous, very profuse in Tertiary and Recent.

Glavella Svvains. (Cyrtulus Hinds) (Fig. 1027). Thick-shelled, smooth or with
fine Spiral Striae. Body wliorl suddenly contracted anteriorly. Canal
very long, straight. Common in Eocene ; rare in Neocene and Recent.

Sycum Bayle {Leiostoma Swains.) (Fig. 1028). Spire short ;
body wliorl inflated, smooth, somewhat flattened below the suture.
Inner lip smooth ; canal straight. Common in the Eocene ; rare
in Miocene.

Fasdolaria Lam. (Fig. 1029). Like Fusus, but distinguished
in general by having a sliorter spire, more inflated body whorl, a
wider and more sinuous or flexuous canal, and in that the anterior
portion of the columella has two or three oblique plications.
Cretaceous to Recent. Fio. loso.

Latirus Montf. (Fig. 1030). Shell fusiform, turreted ; spire Latirus craticulatus
Costa te. Aperture oblong, outer margiu relatively thin, crenulate; Lapngy.Transyivania.'

560

MOLLUSCA

PHYLÜM VI

columellar border sliglitly twisted, witli two or tliree small oblique plaits anteriorly ;
sometimes umbilicate. Cretaceous to Receiit.

Pisanella v. Koenen. Oligocene. Peristernia Möreli ; Leucozonia Gray. Tertiary
and Eecent.

Family 6. Vasidae Adams. {Turhinellidae auct.).

Shell similar to those of the preceding family, but with strong, horizontal columellar
folds. Tertiary and Recent.

Xancus Bolt. {Tmhinella Lam. ; Mazza Adams ; Mazzalina Conrad). Tliick-
shelled, ovate - conical, smooth ; spire sliort and blunt, body wliorl large ; canal
straiglit, elongated. Eocene to Recent.

Vasum Link {Gynodonta Schum.). Shell lieavy, strongly scnlptured, often spinöse,
witli short canal. Tertiary and Recent,

Family 7. Volutidae Gray.

Shell thicJc, ovate to fusiform, dull or lustrous. Spire short or long, hody whorl large.
Aperture elongated, with a short canal or notch ; inner lip with columellar folds. Oper-
culum usually ahsent Cretaceous to Recent.

This family, as liere defined, contains genera distributed by malacologists amongst

several families — Marginellidae, Mitridae and
Volutidae — all of whicli are cliaracterised by tlie
strong development of columellar folds; but it is
likely tliat this structure originated independently
in several phyla at intervals remote from one
another. The Initiation of well-marked genera
with Volutoid plaits occurred in the Cretaceous.
Subsequently their number increased, and a great
many generic types became dift'erentiated. The
phylogeny of Tertiary and Recent forms has been
ably worked out by DalL^

Marginella Lam. (Fig. 1031). Shell oval or
oblong, smooth, glistening. Spire short ; aperture
narrow, slightly canaliculate anteriorly.' Columella
with three or four oblique folds of about equal
size ; outer margin frequently thickened and dentate.
Tertiary and Recent.

Mitra Lam. (Fig. 1032), Fusiform to elongate-
oval, solid ; spire high, acuminate ; aperture narrow,
channelled anteriorly. Columella with numerous
oblique folds, the posterior plaits

being often the strongest. Outer margin commonly thickened, and

smooth internally. Abundant in the Tertiary and Recent.

Turricula Adams. Like the last, but shell transversely ribbed.

Cretaceous to Recent,

Strigatella Swains. (Fig. 1033) ; Gylindromitra Fischer {Cylindra

Schum.) ; Imhricaria Schum, ; Volutomitra Gray ; Perplicaria Dali,

Tertiary and Recent,

Lyria Gray (Fig, 1034). Elongate - oval, transversely ribbed.

Aperture narrow. Columella anteriorly with two much compressed

Fig. 1031.

Marginella crassula
Desh. Calcaire Gros-
sier; Chaumont, near
Paris. 2/j.

Fig. 1032.

Mitra fusiforniis
Brocchi. Plio-

cene ; Rhodes.

1 Bull. Museum Comp. Zoology, vol. xviii., 1889 ; Proc. U.S. Nat.
Museum, vol. xii., 1890, Trans. Wagner Free lust. Sei. Pliilad., vol. iii,, 1890.

Strigatella lahratula
(Lam.). Eocene;
Grignon, near Paris,

CLASS IV

OASTUOPODA

561

and veiy large i)licatio]is, ]»eliiiid (above) wliicli are imintTou.s weaker oiics. Outcr
iiiargiii tliickeiied. Tertia ry and Recent.

Ämpulla Bolten {Halia Risso ; Priamus Beck). No columellar folds. Pliocene and
Recent.

VohUilühes Swains. (Figs. 1035-36). Shell fvisiform, spire elongate-conical; proto-
concli small, rising to a more or less acute apex. Whorls costate, typically spinöse.
Aperture anteriorly with short broad canal ; columellar folds variable, several in
number, tliose toward the anterior being generally the niost pronounced. Abundant
in the Cretaceous, Eocene and Oligocene.

Allied genera : Gosavia Stol.; Leioderma and Rostellites Conrad ; Liopeplum Dali ;
Volutoderma (Fig. 103V) and Volutomorpha Gabb. Cretaceous.

Äthleta Conrad. Spire short, body whorl inflated, posteriorly with a row of

Fig. 1034.

Lyria modesta
A.Braun. Oligo-
cene ; Weinheiin.

Fig. 1035.

Volutüithes bicorona
(Lam.). Eocene; Cour-
tagnon, near Epernay.

Fig. 1036.

Volutilithes muricinua Jjam.
Calcaire Grossier ; Damery,
near Epernay.

Fig. 1037.

Volutoderma elon-
(jaia d'Orb. Gosau-
Cretaceous ; St. Gil-
gen, Austria.

spinous nodes. Inner lip callous, inuch expanded ; columella anteriorly with three
strong transverse folds, behind (above) which follow a few weaker ones. Outer
margin thickened. Miocene and Pliocene.

Scaphella Swains. Shell in this genus is elongate-oval or fusiform, solid, broad, and
with elevated, turbinate, smooth protoconch. Spire short, longitudinally plicate, the
folds being elevated into obtuse tubercles on the base of the whorls. Aperture narrow,
canaliculate behind and broad in front ; inner margin often covered by a thin callus.
Columella carrying many plaits, four or five of which are prominent, the remainder
much smaller. Tertiary and Recent.

Subgenera : Fulgoraria Schuin. ; Scapha Gray; Zidona Adams; {Volutella d'Orb.);
Äuriiiia Adams (FoluHfusus Conrad) ; Caricella Conrad ; Adclomelon and Eucymha Dali, etc.

Voluta Linn. Spire short, protoconch small. Aperture narrow, inner lip callous,
with numerous transverse folds ; outer margin thickened. Tertiary and Recent.
Melo Humphr. {Gymbium pars, Bolten). Recent.

Family 8. Harpidae TroschcL

hody whorl inflated^ with sharp, uniformly spaced transverse ribs.
Aperture wide, with short broad canal. Inner lip callous. Operculum absent. Tertiary
and Recent.

VOL. I 2 0

562

MOLLUSCA

PHYLÜM VI

The typical genus Harpa Lam. {Silia Mayer) (Fig. 1038), ranges from tlie Eocene

to the present time.

Gryptochorda Mörcli (? Harpopsis Mayer)
(Fig. 1039). Elongate-oval ; spire short,
body wliorl large, smooth, lustrous. Aperture
with Short recurved canal ; inner lip callous.
Common in the Eocene.

Family 9. Olividae d'Orbigny.

Fig. 1038.

Harpa mutica Lam.
CalcaireGrossier; Grig-
noii, near Paris.

Fig. 1039.

Gryptochorda ström-
boides (Lam.). Calcaire
Grossier ; Damery, near
Epernay.

Shell elongate-oval to suhcylindrical, solid,
smooth and glistening. Spire short ; body
whorl very large. Aperture narrow ; outer
lip sharp ; columella anteriorly with an out-
wardly reflected callus. Canal very short.
Cretaceous to Kecent.

Oliva Martyn (Fig. 1040). Shell suhcylindrical ; suture line marked by a deep
groove. Columellar callus obliquely folded. . Cre-
taceous to Recent.

Olivella Swainson. Small, with acute en-
amelled spire. Tertiary and Recent.

Ancilla Lam. (Äncillaria Lam.) (Fig. 1041).
Shell oblong, occasionally acuminate. Suture
usually covered over by a lustrous enamel-like
callus. Aperture somewhat broadened anteriorly ;
columellar callus slightly twisted. Cretaceous to
Recent.

Superfamily 5. TOXOGLOSSA TroscheL

Fig. 1040.

Oliva clavula. Lam.
Miocene ; Dax, near
Bordeaux.

Fig. 1041.

Ancilla ijlandi-
formis Lam. Mio-
cene ; Steinabrunn.

Radula typically with only two arrow
teeth in each transverse row, although occasionally as many as five teeth are developed-
Shell similar to that of the Rachiglossa.

This group is most closely allied to the Rachi-
glossa, from which it probably became differentiated
in the Cretaceous. The Tertiary and Recent species are
excessively profuse. All are carnivorous and marine.

Family 1. Oancellariidae Adams.

Shell oval to turreted. Spire acuminate; hody
whorl inßated ; surface transversely ribhed and in most
cases cancellated. Aperture with short canal or notch ;
columella with several strong oblique folds, outer lip
grooved internally. Upper Cretaceous to Recent.

The typical genus Gancellaria Lam. (Fig. 1042)
attains a maximum distribution in the late Tertiary and Recent.

Fig. 1042.

Gancellaria can-
cellata (Linn.). Mio
cene ; Gainfahrn,
near Vienna.

Family 2. Terebridae Adams.

Shell turreted, slender, acuminate, with small body whorl. Aperture
oval or quadrilateral ; canal short, curved ; outer lip sharp. Oper-
culum horny. Tertiary and Recent.

Of the two leading genera, Terebra Lam. (Fig. 1043) and Hastula Adams, the first

Fig. 1043.

Terchra acuminata
Borson. Miocene ;
Baden, near Vienna.

CLASS IV

GASTROPODA

r)63

is characterised by a line running parallel witli the sutiue, and creating a narrow
suture band. Duplicaria Dali lias the sutiire channelled.

Family 3. Turritidae Adams (Pleuratomidae Stoliczka).

Shell fusiform, with moderately high spire. Äperture elongated, produced anteriorly
in a longer or shorter canal. Outer lip with a slit or notch below the suture. Operculum
horny, sometimes ahsent. Cretaceous to Recent.

Upwards of 700 recent and 1000 fossil species have been described, of which 28
are Cretaceous.

Turris Bolten {Pleurotoma Lam.) (Figs. 1044-1047). Shell turriciüated, spire long.
A B c A B

Fig. 1044.
A, Turris notata (Brocchi) var. (=r. monilis
Hoernes). Miocene ; Baden, near Vienna. B, T. (Sur-
cula) lamarcki Bell. Miocene ; Baden, near Vienna.
C, T. (Surcula) hclgica Nyst. Oligocene ; Weiuheim,
near Alzey.

Body whorl of nearly equal length with the spire
margin smooth. Outer mar-
gin of the äperture with a
narrow, deep sinus, situated
at or some distance below the
suture. Operculum pointed
ovate, with apical nucleus.
Cretaceous to Recent.

Subgenera : Surcula (Fig.
1044, B, G) ; Genota Adams
(Fig. 1045, A) ; Bathytoma
Harris (Fig. 1046) ; Oligotoma,
Rouaultia Bellardi ; Crypto-
conus V. Koenen (Fig. 1045, B) ;
Drillia (Fig. 1047) ; Bela Gray ;
Lachesis Risso, etc.

Ölavatula Lamarck (Fig. ^^^^ j^^g^

1048). Differs from Turris ^.^^^^ '(Bathytoma)
proper in that the outer margin cataphmcta Brocchi.

f ^ , , ,, . . T Miocene ; Baden, near

is cut by a shallow triangulär vienna.

notch, and the nucleus of the

operculum is situated in the middle of the anterior margin.

Subgenera : Pseudotoma, Glinura Bellardi.

Fig. 1045.

A, Tnrris (Genota) ramosa Bast.
Miocene ; Grund, Hungary. B,
T. (Cryptocojius) filosa (L&m.). Cal-
caire Grossier; Grignon, near Paris.

canal long and straight ; columeUar

Fig. 1047.
Turris (Drillia)
incrassata Diij. Mio-
cene ; Steinabmnn,
near Vienna. -/j.

Fig. 1048.
Clavatula asfiendata
Lamarck, Miocene ;
Gnind, Hnngary.

Cretaceous to Recent

564

MOLLUSCA

PHYLÜM VI

Borsonia Bellardi (Fig. 1049). Outer margiii witli a sliallow notch ; canal long
aud straight ; columella with one or two folds ; operculum iinknown. Eocene to
Recent.

Mangilia Risso (Fig. 1050). Shell small, fusiform, imperforate and typically,
with longitudinal costae or swellings. Aperture commonly narrow, with a short,

Fig. 1049.

Borsonia delucii
Nyst. Lower Oligo-
cene ; Lattdorff, near
Bern bürg.

Fig. 1050.

Mangilia angusta
Jan. Plioeene ;
Occiano, near Pisa.

Fig. 1051.

A, Clathurella strom-
hilla Duj. Miocene ;
Kienberg, near Vienna.
B, Bellardiella reticu-
lata (Brocchi). Plio-
eene ; Sassuola, near
Modena.

Fig. 1052.

Daphnella (RapJd-
toma) vnlpecula
Brocchi. Plioeene ;
Sassuola, near
Modena.

trimcated canal ; no operculum ; sinus near the suture. Outer margin usually acute,
not dentate posteriorly with shallow notch. Tertiary and Recent.

Allied genera are the following : Clathurella Carp. (Fig. 1051, Ä) ; Bellardiella

Fischer (Fig. 1051, B) ; Atoma Bellardi; Glypho-
stoma Gabb ; Daphnella Hinds, with subgenus Raphi-
toma Bellardi (Fig. 1052) ; Eucythara Fischer, etc.

Family 4. Oonidae Adams.

Shell convolute, turhinate or suhcylindrical,
generally smooth. Spire short, conical or ßattened.
Aperture long, narrow, anteriorly notched. Outer lip
sharp, sometimes with an anal sinus helow the suture.
Golumella smooth. Operculum horny. Cretaceous to
Recent.

This family is now enjoying its acme of
development, having entered upon its ascendency
during the Tertiary. The typical genus, Conus
Linn. (Fig. 1053), is divided by malacologists into
Ä, Conus ponderosus Brocchi. Miocene; numerous subgenera, connected with one another
Lapugy, Transyivania. B, c. parisiensis by intermediate fomis. It is initiated in the

Desh. Calcaire Grossier; Grignon, near r^ ,

Paris. Cretaceous.

Gonorhis Swains. Characterised by a high
spire, and a curved, outer lip, which is deeply notched posteriorly. Eocene and
Oligocene.

Fig. 1053.

Subclass 2. EUTHYNEURA Spengel.

Gastropods in which the visceral nerve commissures are not crossed, hut form a simple
loop ; the sexes are united (hermaphroditic) ; and the heart is often in front of the gill.
Shell Spiral or saucer-shaped, frequently vestigial or absent ; operculum generally wanting.
Radula generally multiserial.

CLASS IV GASTROPODA

Order 1. OPISTHOBRANCHIA Milne Edwards.

Marine, ivater-hreathing forms, either naked or shell-covered, in which the gills are
placed behind the heart and lie free on the back or side ; or true gills may be absent,
being replaced by secondary or false gills. Heart with a single auricle.

The Opistliobranchiates, imlike the Streptoneura (Prosobranchiates), send the blood
into the heart from behind, instead of from the anterior side. The gills, in the form
of a more or less branched plume, lie on the right side, or are replaced by false gills
not homologous with the ctenidium, arranged either in two rows on the back, or
wreath-like aroiind the anus. The gills are often covered by the mantle, and some-
times become completely atrophied. The radula generally resembles that of the
Pulmonates. The body and nervous System usually exhibit bilateral symmetry.

Three suborders are recognised in the recent fauna : (1) Nudihranchiata, in which
a Shell is absent, except diuing the larval stage, and the ctenidium is replaced by false
gills ; abundantly distributed in all seas at present, but owing to their perishable
nature are unknown as fossils ; (2) the Tectibranchiata, in which a mantle, shell and
ctenidium or true gill is developed ; and (3) the Pteropoda, dating from the Cambrian,
and from which the second suborder is perhaps derived. A provisional fourth sub-
order, the Gonularida, contains Paleozoic forms of doubtful affinities, of which part
are probably not Mollusca.

Suborder B. TECTIBRANCHIATA.^

This group, briefly defined above, has fossil representatives as early as the
Paleozoic. During the Mesozoic, a few genera now extinct were very profuse. Most
of the Tertiary species belong to existing genera.

Family I. Acteonidae d'Orbigny.

Shell ovate, with exposed spire, the surface usually grooved and punctured, sometimes
smooth. Apertur e long, rounded below ; columella generally twisted, or with folds.
Operculum paucispiral. Carboniferous to Recent.

Solidula Fischer von Waldheim {Buccinulus Adams ; Dactylus Schum.). Ovate or
oblong, compact, solid, with a short conic spire. Columella bearing two plications, the
anterior prominent and bifid, the posterior comparatively inconspicuous when the
Shell is entire ; between them the columella is spirally excavated.
A few ill-defined species from the French Eocene and Miocene, one
from the Australian Pliocene, and numerous Recent tropical species
are known.

Tornatellaea Conrad (Fig. 1054). Differs . from Solidula and
Acteon in the more anterior disposition of the two columellar
plications, in the marked depression on the anterior portion of the pio. 1054.
aperture, and in the greater thickness of the shell near the outer Tornatellaea Hm-
border of the aperture, which is frequently crenulated. Base of Jura ^'eTef Lattdofr;
to Miocene ; widely distributed. Type, T. bella Conrad. Subgenus : near Bemburg.
Triploca Täte. Eocene ; Australia.

Acteon Montf. {Tornatella Lam. ; Speo Risso ; Kanilla Silvert.). Oval, spirally
punctate-striate, with conic spire. Protoconch not very prominent ; nucleus sinistral.

^ Literature (see also preceding bibliographies) : Cossmann, M., Essais de paleoconchologie
comparee, i., 1S95. —Püshn/, IL A., Monograph of Recent Tectibranchiata, in Manual of Conch-
ology, vols. XV., xvi., 1894-95.

566

MOLLUSCA

PHYLUM VI

Columella thick, witli one strong, spiral, sliglitly oblique, plication. Upper Cretaceous

to Recent.

Ädelactaeon Cossm. {Myonia Adams). Sliell witli siiiistral protoconcli, tlie latter
not very large. Wliorls decussated by fine Striae, growtb-lines
inconspiciious. Columella sliglitly excavated, and carrying a
small but well-marked plication. Miocene of France and Ger-
many, and Recent.

■((II

Fio. 1056.

Actaeonina myosotis
Buv. Coral-Rag; St.
Miliiel, Meuse. 2/j
(after Buvignier).

Fig. 1055.

Actaeonina do'nnoisiana
d'Orb. Coral-Rag; Val-
fln, Ain.

Cylindrites acutus
(Sowerby). Great
Oolite; Minchin-
hanipton, England.

Actaeonella gigantea Sowb. Turonian
Grünbach, Lower Austria.

Actaeonina d'Orb. {Orthostoma Desb.) (Figs. 1055, 1056). Shell ovoid to fusiform.
usually smootb, rarely spirally striated. Spire conical, body whorl very large,
narrowing toward the base. Columella straigbt, witliout folds.
Outer lip sharp. Carboniferous to Recent.

Subgenera : jEuconactaeon, Conactaeon Meek.
Lias. Douvilleia Bayle. Tertiary.

Fio. 1059.

Actaeonella voluta
Goldf. Turonian;
Garns, Styria.

Fitt. 1060.

Actaeonella (Volvu-

Fdr. (Fig. 1057). Cylindrical-
ovoid with short spire. Columella witli an
anterior fold. Trias to Cretaceous.

Bullina Fer. Jura to Recent. Gylindro-
hullina v. Amnion, Trias and Lias. Etallonia
Desh. Jura and Tertiary. Bullinula Beck.
Jura to Recent.

Actaeonella d'Orb. (Figs. 1058 - 1060).
Thick - shelled, inflated, smooth. Spire short;
columella thickened anteriorly, with three
Sharp folds. Very profuse in the Middle and

Hna) laevis Sowb. Upper Cretaceous ; maximum distribution in

the Hippurite Limestone of the Alps.

Subgenus : Volvulina Stol. (Fig. 1060). Like the preceding, but with insunken spire.
Cretaceous.

Volvaria Lam. Cylindrical, with involute, concealed spire. Surface usually
spirally striated ; aperture narrow ; columella with four anterior plications. Eocene.
Ovulactaeon Dali. Similar in form to Gypraea, but witliout plications. Recent.

CLASS IV

GASTROPODA

567

^ Family 2. Ringiculidae Meek.

Inoperculate forms resemhling the Actaeonidae in having columellar folds. Creta-
ceoiis to Receiit.

Ginulia Gray (Fig. 1061). Globose, inflated, spirally grooved or pimctate. Spire
Short ; aperture crescentic ; oiiter lip reflected and thickened. Columella and inner lip
with numerous transversa folds. Cretaceous.

Subgenera : Avellana, Ringinella d'Orb. ; Eriptycha Meek ; Fortisia Bayan. Eocene.

Ringicula Desh. (Fig. 1062). Small, ovoid to globose, thick-shelled, with mammil-
lated protoconch. Spire sbort ; Iwdy whorl large, usnally smooth. Aperture canal-

-1 /; ('

Fifi. 1061.

A, Cinulia (Avellarm) incrassata (Mant.). Gault ; Perte du
Rhone. B, C. (Ringinella) lachryma Mich. Gault ; P'olkestone,
England. C, ('. {Eriptycha) demrtata Zekeli. Turonian ; Gosau,
Austria.

##

Fl(i. 10G2.

Ringicula hoernesi
Seguenza. Miocene;
Steinabrunn, near
Vienna.

iculate posteriorly, excavated anteriorly. Columellar border tliick and callous ; the
columella arched, and furnished with from two to four plications. Outer margin
usually very thick, reflected, and occasionally denticulated within Cretaceous to
Recent.

Pugnns Hedley. Cylindrical, with sunkeii spire. Recent.

Family 3. Akeratidae Pilsbry.

Shell oval or cylindrical, thin and fragile, the spire low or concealed.
Recent.

Tertiary and

Äkera Müller (Fig. 1063). Thin-shelled, flexible, with exposed, truncated spire.
Whorls separated from one another by deep sutures. Sutures
deep and prominent ; outer lip separated from the spire.
Eocene to Recent.

Haminea Leach. Oval, thin-shelled, brittle ; the spire
concealed. Tertiary and Recent.

Family 4. Hydatinidae Pilsbry.

Glohose or oval, with exposed, nearly level spire and tilted
protoconch. Jura to Recent.

Fia. 1063.

Akera striate.lla Lam.
Oligocene ; Castel Gomberto,
near Vicenza.

Hydatina Schumacher.
Pilsbry. Recent.

Jura to Recent. Aplustrum Schumacher; Micromelo

Family 5. Bullariida^ Pilsbry (emeud.).

Shell oval or suh-globose, involute, smooth. Spire sunken and concealed. Aperture
long, rounded anteriorly ; outer lip sharp. Marine. Jura to Recent

Bullaria Raf. {Bulla Linn.) (Fig. 1064). Oval, inflated, with sunken spire and
perforated apex. Aperture rounded posteriorly and anteriorly. Jura (?) to Recent.

568

MOLLUSCA

PHYLÜM VI

Family 6. Acteocinidae, novum {Tornatinidae Fischer).

Radula unarmed. Tertiary and Eecent.

Äcteocina Gray {Tornatina Adams) (Fig. 1065). Cylindrical, witli projecting
spire, and sinistral, tilted protoconcli. Columella bearing a single
fold. Tertiary and Eecent.

Retusa Brown. Shell resembling Gylichna. Tertiary and
Recent.

Volvula Adams (Volvulella Newton).
Fiisiform, the body whorl forming a point
above the sjiire. Eocene to Eecent.

Fig. 1064.

Bullaria ampulla
(Linn.). Pliocene ; Asti,
Italy.

Fig. 1065.

Äcteocina exerta
(Desh.). Oligocene ;
Jeurres, near Btampes
(after Deshayes).

Family 7. Scaphandridae Fischer.

Spire concealed ; radula with few teeth in a
row. Trias to Eecent.

Scaphander

Montf. (Fig. 1066). Shell sub-cylindrical, with epidermis, usnally
spirally striated. Body whorl of enormous capacity, much dilated
anteriorly. Columella spiral, leaving a false nmbilicus. Creta-
ceous to Eecent.

Atys Montf. Cretaceous to Eecent. Diaphana Brown. Ter-
tiary and Eecent. Smaragdinella Adams. Eecent.

Gylichna Loven {Bullinella Newton) (Fig. 1067). Small,
cylindrical, solid ; spire deeply perforated at
the summit ; body whorl covering all the
others. Aperture very narrow, outer margin
lower than the axis of the shell. Columella
thickened anteriorly ayd bearing a small plica-
tion ; often umbilicated. Trias to Eecent.

Fig. 1066.

Scaphander conic^is
Desh. Eocene ; Brack-
lesham, England.

Family 8. Philinidae Fischer.

Fig. 1067.
Cylielina conoidea

Similar to Scaphandridae, hut shell internal, wdnheim, near^Tizey.'

loosely coiled, punctate. Cretaceous to Eecent.
Philine Ascan. (Bullaea Lam.) (Fig. 1068). Cretaceous to Eecent.

Family 9. Umbraculidae Pilsbry.

Shell limpet-shaped, ivith low suh-central apex, and sharp, thin edges. Tertiary and
Eecent.

Umhraculum Schum. {Umhrella Lam.). Shell orbicular, broad,
patelliform, ornamented exteriorly with concentric lines of growth ;
internal surface with concentrically undulating Striae. Eocene to
Eecent.

Other families of Tectibranchiata, such as Aplysiidae, Pleuro-
hranchidae, etc., are represented in the Eecent fauna, but tlieir thin,
often membranous shells have not been found fossil. The supposed
Aplysias reported from the Pliocene by Philippi are flakes from the
interior of Pelecypod valves.

Fig. 1068.

Philine excavata
Deshayes. Eocene.
Calcaire Grossier ;
Grignon, near Paris.

CLAss IV GASTROPODA 569

Suborder C. PTEROPODA Cuvier.i

Nahed or shell-covered, hermaphroditic, pelagic Mollusca, without distinct head. Eyes
riidimentary, and foot modified so as to forra tvjo lateral, wing-like fins, situated on the
anterior end of the hody. The gills are placed hehind the heart.

The body of these free-swimming Mollusca is sometinies elongated, sometimes coiled
posterioiiy in a si>iral. In some instances it is covered by a thin transparent sliell
{Thecosomata), biit oftener it is naked (Gymnosomata). The creatures associate in vast
swarms in the open sea, and rise to the surface toward nightfall. Their shells often
accumulate in prodigioiis quantities on the sea-bottom, forming calcareous deposits of
considerable magnitude.

C 11 vier recognised the Pteropods as an independent class of Mollusca, having equal
rank with the Gastropods. Modern researches, however, have approximated theni
niore closely to the latter througli the swimming Opisthobranchs. If \ve regard it as
probable that invertebrate life began in the sea, it almost certainly follows that
Pteropods are among the earliest Mollusca. Also, granting that the conditions of
their existence have undergone no appreciable change since the ocean becanie capable
of sustaining such pelagic life, there is no obvious reason why the members of the
group should have since experienced any radical modification,

The earlier paleontologists, d'Archiac, de Verneuil, Sandberger, Barrande and
others, recognised the true relations of the Paleozoic Pteropods, though uniting with
them some forms of similar appearance, which probably are not of niolluscan nature,
such as Conularia, and perhaps Tentaculites.

Neumayer and Pelseneer, led by preconceived theories, have objected to the union
of Paleozoic forms like Hyolithes with the Pteropods, though proposing no satisfactory
alternative ; and by a curious reversal of paleontologic succession, have wished to
derive the Pteropoda from the more modern Opisthobranchs. Since the anatomy of
the Cambrian forms seemed inaccessible, the uncertainty bade fair to remain permanent,
when, by the discovery of the wonderful Middle Cambrian deposits of the Canadian
Rocky Mountains, among the otlier fossils showing traces of the soft parte, were found
several specimens of Hyolithes carinatus Matthew, with distinct and clear impressions
of the pteropodia. These, judging from the sharpness of their anterior margins, seeni
to have had there some kind of a chitinous support, perhaps like the chitinous rods
supporting the gill-lamellae of some Nuculidae.^ This wholly unexpected confirmation
of the earlier view as to the relations of these fossils, falls in with the views generally
held by malacologists as to the derivation of the swimming Opisthobranchs from the

^ Literature (see also preceding bibliograpliies) : Sandherger, O., Die Flossenfüsser oder Ptero-
poda. Neues Jahrb. für Mineral., pp. 8-25, 1847. — Barrande, J., Piigiunculus, ein fossiles
Pteropoden-Geschlecht. Neues Jahrb. für Mineral., pp. 554-558, 1847.— Systeme Sibirien du centre
de la Bolieme, vol. iii. Pteropodes, 1867. — Salter, J. W., Menioirs of the Geological Survey of
Great Britain, vols. ii., iii., 1848, ISQQ.—Seguenza, G., Paleontologia raalacologica dei terreni terziarii
del distretto di Messina. Pteropodi ed Eteropodi. Mem. Soc. Ital, Sei. Nat. Milano, vol. ii., 1867.
— Karpinsky, A., Die fossilen Pteropoden am Ost- Abhang des Ural. Mem. Acad. St. Petersbourg,
ser. 7, vol. xxxii. pp. 1-20, 18Si.—Doll/us, Q. and Ramond, G., Liste des Pteropodes du terraiu
tertiaire parisien. Mem. Soc. Malacol. de Belgique, vol. xx., \9>8b. — Walcott, C. D., Contribution
to Studies on tlie Cambrian Faunas of North America. Bull. U. S. Geolog. Survey, vol. iv. No. 30,
pp. 125-146, 1866.— The Fauna of the Lower Cambrian or Olenellus Zone. Tenth Ann. Rept.
U.S. Geol. Survey, 18^0.— Pelseneer, P., Report on the Pteropoda. Report Challenger Expedition,
Zoology, vol. xxiii., 1888.— /«ie?/i, Bull. Soc. Beige de Geol. Palaeont. et Hydrol., vol. iii., 1889.—
Blanckenhorn, M., Pteropodenreste aus der oberen Kreide Nord-Syriens und aus dem hessischen
Oligocän. Zeitschr. Deutsch. Geol. Ges., vol. xli., 1889.— iVb^'(i^^ 0., Revision der paläozoischen
Hyolithiden Böhmens. Abhandl. Böhm. Ges. Wiss. [7] vol. iv., 1891.— //oZm, G., Sveriges Kam-
brisk-Siluriska Hyolithidae och Conularidae. Afhandl. Sver. geol. Undersök., Ser. C, No. 112,
1893.— AS^^a^er, /., Monograph of British Conulariae. Palaeont. Soc, 1^01 . — Walcott, C. D., Cam-
brian Geology and Paleontology. Smiths. Mise. Coli., 1912, vol. Ivii., No. 5.

- A figure of this fossil is given by Walcott in Smithson Mise. Coli., 1912, vol. Ivii., No. 5.

570

MOLLUSCA

PHYLUM VI

same stem as tlie Pteropoda, and their natural association with the latter in a single
large group.

Family 1. Limacinidae Gray.

Shell thin, spiral, sinistral, with vüreous, paucispiral operculum. Tertiary and
Recent.

The genus Limacina Lam. (Spirialis Eyd. and Soul. ; Embolus Jeffreys), is of
sporadic occurrence in the Tertiary (Eocene and Pliocene). Valvatina Watelet,
includes flat sinistral shells from the Calcaire Grossier of Paris, and Planorhella Gabb
comprises similar forms from the Oligocene of San Domingo.

Family 2. Oavoliniidae Fischer.

Shell symmetrical, thin, vüreous, ventricose, pyramidal, or conically tubiform, but not
Spiral. Cretaceous to Recent.

GavoUna Abildgaard {Hyalaea Lam. ; Gamopleura Bellardi) (Fig. 1069). Shell

globose, laterally keeled and slit, acuminate pos-
teriorly ; composed of two unequally arched pieces,
one of wliich projects helmet-like above the otlier.
Recent, and fossil in the Italian Miocene and
Pliocene.

Glio Linnaeus (Gleodora Peron and Lesueur ;
Balantium Benson ; Flabellum, Poculina Bellardi)
(Fig. 1070, A, B). Shell somewhat angular, com-
pressed dorso-ventrally, with lateral keels, A crest
or rib generally extends longitudinally along the
back, and usually projects. Upper Cretaceous to
Recent. A common fossil in the Pliocene of Monte Mario, near Rome, and in the
vicmity of Messina and Turin ; also in the Oligocene of the Mayence Basin, and in
the English Crag.

Fig. 1069.
A, Cavolina (Hyalaea) tridentata Forsk.
Recent. B, C, C. (Gamopleura) taurinensis
Sism. Miocene ; Turin, Italy.

Fig. 1070.

A, Clio (nieodora't mimmhintn t ,•«„ -dt ^' ^"""^s^^s recta Lesueur. Recent (after

MonteMaroSrRomrR %/?«•; ^ '^^^"6 ; A^lams). B, Styliola striatulaNova\^. Devonian

cnr.L A idam? ge^ent. i^iSÄhellTaV;; (f ^'^f H) ; Hlubocep, Boheniia. 3/,. C, Crese^s

Adams). C, Vngindla depr^.Ta h^^^ '''''"'^;'' ^^"v, ?«^?nian (Etage H) ; Hostin,

strang^latam.lrS Mioceni'rSx^nJar BoEx TtlSent "''i/r'' "'""' -dividuals on

buTflthtiv ^ntl ITl? T ff »t^y «triated ; dorsal groove not parallel to axis of the shell
1 ne enSonrnnrT n ° / • ^'' ^''^■''''\ «^t^'e»^ity (wlnch ends in a rostrum) in the median
line embryonic portion ends in a pomted apex. Tertiary and Recent.

apeSlh-cuSr"' ^ ^' ^'^- ^'"^''^' '''^^ ^^"^^°"^ protoconch, no dorsal groove,

CLASS IV

GASTROPODA

571

In the Devonian of Bohemia, Nassau, Ural and North America, great niimbers of smooth,
circular, longitudinally striated tubes are occasionally met witli, the posterior end of whichis
intlated into a sniall bulb. Similar tubos have also been described by Blankenhorn froni the
Cretaceous of Syria. None of these differ externally to any great extent froni Clio or Styliola.

Vaginella Daudiii (Fig
slightly canaliculated and
Cretaceous to Recent.

Guvierina Boas ; Triptera
O. Meyer). Tertiary and Re(;ent
Fisclier. Eocene.

1070, C). Shell long,
compressed laterally

ventricose, depressed ; aj)erture
Cross-section elliptical. Upper
AB c

Qiioy {Tihiella
Euchilotheca

Fig. 1072.
, A, B, Hyolithes elegans Barr.

Family 3. Hyolithidae Nicholson.

Shell symmetrical, conical or pyramidal,
straight or sharply hent ; cross-section triangulär,
elliptical or lenticular ; one side often ßattened,
and the other arched or with a Munt median keel.
Surface smooth or ivith fine transverse Striae, rarely
longitudinally striated or ribhed. Aperture com-
pletely closed by an operculum, the latter being
semicircular, triangulär or lentiform, with lateral
nucleus, and concentrically striated ; fteropodia,

with a chitinous support to the anterior edge. f^^g ^^'' 1^°^«'"««' B«^«"^^*
Cambrian to Permian.

According to Holm the typical genus,
Hyolithes Eichwald {Tlieca Sowb. ; Pugiunculus
Barr.) (Fig. 1072), is divisible into two subgenera. One of these, Orthotheca Noväk,
contains forms with an abruptly truncated anterior end ; and in the other, Hyolithes
s. Str., the margin of the flattened side projects somewhat above the opposite wall.
ABC The forms known as Gleidotheca, Gentrotheca Salter,
Gamerotheca, Diplotheca Matthew, Pharetrella Hall,
Geratotheca and Bactrotheca Noväk, fall within the
synonymy of Hyolithes. TJiis genus is abundantly
distributed in the Cambrian, Ordovician and Silurian
of North America, Great Britain, Sweden, Russia and
Bohemia ; it occurs sparingly also in the Devonian,
Carboniferous and Permian.

Pterotheca Salter ; Phragmotheca Barrande. Silu-
rian ; Europe. Matthewia Walcott. Cambrian.

Ordovician ;
Slightly re-
C, H. tnctximas Barr. Caiiibrian
(Etage C) ; Mleschitz, Bohemia. Anterior
portion restored, with operculum, and viewed
from the side. 1/2. D, Operculum (after Bar-
rande).

Fig. 1073.

A, TentacuUtes scalarif
Schloth. Erratic block of
Ordovician age ; Berlin. B,
T. orwitiis Sowb. Silurian ;
Dudley, England. C, T.
rtrudritfs Rieht. Silurian con-
cretion ; Thuringia. A
smaller individual contained
within the larger (after
Xovak). «

Suborder D. CONULARIIDA Miller and Gurley.

Paleozoic forms of doubtful systematic position,
resembling some Recent Pteropoda, but probably to be
regarded as a parallel rath^r than as an identical
group.

Family 1. Tentaculitidae Walcott.

Thick - walled, , tapering, elongate, conical tubes,
having a circular cross-section, and terminating posteriorly either acutely or in an
embryonal bulb. Surface ornamented with parallel raised transverse rings. TJie apicaJ
portion of the shell often filled with calcareous matter, or divided off by transversr a< fiia.
Ordovician to Devonian.

572

MOLLUSCA

PHYLÜM VI

Tentaculites Schloth. (Fig. 1073). This, the solitary genus, is prodigiously
abuiidaiit in the Siluriaii and Devon ian, the strata being sometimes fairly charged
with their remains. The shell is composed of a compact outer layer, and an inner
layer made up of thin lainellae running parallel with the external surface.
The supposed Tentaculites described from the Oligocene by Ludwig and Blankenhorn
are thin-shelled, transversely ribbed, conical tubes, wliich probably belong in the
neighbourhood of Styliola or Euchilotheca.

Family 2. Torellellidae Holm.

Thich - ivalled, smooth, transversely or longitudinally striated, straight or bent tuhes,
acutely terminated posteriorly, and without opercula. Cambrian to Silurian.

Torellella Holm. Tubes strongly compressed, flattened at both ends, elliptical in
cross-section, and with fine transverse Striae ; composed of brownish-coloured calcium
phosphate. Cambrian to Silurian ; Sweden.

Hyolithellus and Salterella Billings ; Coleolus Hall ; and Goleoloides Walcott, from
the Lower Cambrian of North America, probably also belong here.

Family 3. Conulariidae Walcott.

Shell rectüinear, elongate- conical, rectangular to rhomhic in cross-section, with
usually sharp edges, acute or truncated posteriorly. Each of the transversely striated or
ribhed lateral faces divided into longitudinal halves by a superficial groove, corresponding
internally to a median ridge. Posterior portion of the shell divided off by septa.
Aperture constricted by four triangulär or linguiform incurved
lobes of the anterior margin. Ordovician to Jura.

Öonularia Mill. (Figs. 1074, 1075). This, the solitary
genus, sometimes attains a length of 20 cm., and is represented
by about 100 species. Its maximum distribution occurs in the
Ordovician and Silurian of Bohemia, Normandy, England,
Sweden and North America, and in the Devonian of North
America and Bolivia. It is rare in the Carboniferous and
Permian, and the last surviving species occurs
in the Trias and Lias.

Order 2. PULMONATA Cuvier.
Air-breathing Snails.^

Euthyneura in which the gill cavity is
transformed into a lung for breathing free
air. Mainly terrestrial or fresh-water forms.

A few Pulmonates have reverted to ex-

clusively aquatic habits, and have the lung

filled with water ; and in a few, secondary

iTpper Carboniferous gills are developed in the cavity. These,

Limestone; Glasgow, i,^,,,^,,^^ „_ J_ .^„_^;.„. rvi. .„^

Fig. 1075.

Conularia quad-

risulcata

5owb.

Fio. 1074.

Conularia anginala Barr,
Ordovician (Etage D)
Drabov, Bohemia.

Scotiand. showing however, are rare exceptions. The great
weii-preseryed aper- majority of forms breathe air by means of a

tural margms (after . i n n i ■, '^■, ^i

Etheridge). network Ol blooQ - vessels» spread upon the

inner surface of the lung. The ordinary
aquatic forms come to the surface of the water at intervals to renew their supply of

^ Sandherger, F., Land- und Siisswasser-Conchylien der Vorwelt. 1870-75. — TFMe CA.,
Review öf American non-marine Mollusca. 3rd Ann. Rep. U.S. Geol. Surv., 1881-82.— Tryow,
O. W. and Pilshry, H. A., Manual of Conchology, Puhmnata.

CLASS IV

GASTROPODA

573

air. The Pulmonates have, witli few exceptions, no operculiim, and the sliell is often
vestigial or absent.

Next to the Prosobranchs the Pulmonates are the largest group of Gastropods,
there being upwards of 6000 living and 700 fossil species known. The most
important and highly diversified genera {Helix, Bulimus, Ölausilia) are terrestrial in
habit ; certain others {Planorhis, Lymnaea, Physa) are confined to fresh water. The
oldest Piilmonates are of rare occurrence in the Devonian and Carboniferous ; they
are found sparingly in the Jura and Cretaceous, are of greater abundance in the
Tertiary, but do not attain their maximum distribution until the present geological
period.

The Thalassophila and Auriculidae are restricted to marine deposits ; the re-
maining Pulmonates are rarely found except in fresh-water strata, and are commonly
associated with other organisms that have been swept by rainfall or running water
into swamps or estuaries.

Suborder A. THALASSOPHILA Gray.

Shell either spiral and operculate, or bowl-shaped to depressed conical, ivithout spire,
and somewhat unsymmetrical. Animal usually provided with a single gill in addition
to the lung cavity. Tentacles fused with the discoidal head. Eyes sessile.

The Thalassophila inhabit the littoral zone of the ocean and brackish estuaries.
Fossil remains occur from
the Devonian onward.
Three families are recog-
nised — Siphonariidae, Gadi-
niidae and Amphibolidae,
but these are not readily
distinguishable by shell
characters alone.

Siphonaria Blainville
(Fig. 1076). Shell usually
radially ribbed. Apex
directed backwards or to-
ward the left side ; inter-
nally with two unequal muscular impressions, which are interrupted on the right
side in front by a broad groove. Tertiary and Recent.

Hercynella Kayser (Fig. 1077). Devonian. Anisomyon Meek and Hayden. Jura
and Cretaceous.

Valenciennesia Rousseau. Shell very thin, broadly bowl-shaped, concentrically
ribbed. Apex situated near the posterior margin. Right side bearing a broad
plication for the respiratory tube. Found in brackish water, Congerian Stage (Pliocene)
of Hungary, Roumania and South Russia.

Williamia Monts. ; Gadinia Gray. Recent and Pliocene.

Amphihola Schum. Shell spirally globose, thick, rugose and operculate. Recent.
This is placed in a separate family, the Amphibolidae.

Fig. 1077.

Siphonaria crassicosfata Desh.
Eocene ; Anvers, near Paris.

Herc^jnella bohemica Barr. Devonian
(Etage F) ; Lochkow, Bhemia.

Suborder B. BASOMMATOPHORA A. Schmidt.

Shell invariably present. Eyes situated at the base of a pair of tentacles.
or living in the vicinity of water.

AquatiCj

Family 1. Auriculidae Blainville.

Shell thick, ovate. Spire short, body whorl very large. Inner lip or columella bear-
ing plications. Shore forms or inhabitants of sali marshes. Jura to Recent.

574

MOLLUSCA

PHYLLTM VI

Äuricula Lani.
roimded anteriorly
times denticulated.

Gassidula Fer, :
(Fig. 1080) ; Melampus Montf.

Garychium Müller (Fig. 1081),

(Fig. 1078). Elongate-oval, with epidermis. Aperture narrow,
Inner lip bearing two or tliree folds ; outer lip thickened, sonie-
Jura to Kecent.
Plecotrema Adams ; Alexia Leach (Fig. 1079); Pythio'psis Sandb.

Shell small, smooth and glossy. Inner lip

Fig. 1079.

Fig. 107

Äuricula dutemplei

Deshayes. Lower Alexia pisoliim Desli.

Eocene ; Sainceixx Miocene ; Pontlevoy,

(after Deshayes). Touraine. ^/i.

Fi(i. lOSl.

Pythiopsis la- Carychium antiquum

marcki (Desh.). A. Braun. Miocene;

Eocene ; Houdan Hochheini, near May-

(after Deshayes). euce. Enlarged.

bearing one or two folds ; outer margin thickened, sometimes with a tooth. Jura to
Kecent. Terrestrial.

Scarahus Montf. (Polyodonta Fischer von Waldh.) ; Leuconia Gray ; Blauneria
Shuttlewortb, etc. Tertiary and Eecent.

Family 2. Chilinidae Dali.

Shell oval, auriculate, with large aperture, the columellar marcjin
provided with spiral folds ; surface coloured in various patterns.
Tertiary and Recent.

Ghilina Gray. This is said to be Streptoneurous. The
dentition resembles that of Physa. Miocene and Recent ; South
America.

Family 3. Physidae Dali.

Shell sinistral, oval, glossy, unicoloured. Aperture large; colu-
mella twisted or simple. Jura to Recent.

Physa Drap. (Fig. 1082). Shell brilliantly polished, thin,
sinistral. Upper Jura to Recent.

Fig. 1082.

Physa gigantea
Michaud. Lower
Eocene ; Rilly, near
Rheims.

Family 4. Lymnaeidae
Keferstein.

Shell thin, turreted. or dis-
coidal. Fresh-water inhahitants.
Lias to Recent ; especially abun -
dant in the Tertiary.

Lymnaea Lam. {Limnaeus
auct.) (Fig. 1083). Shell very
thin and corneous. Body whorl
very large ; spire acute, and
moderately high. Aperture wide, oval
to Recent ; maximum in Tertiary.

Planorhis Guettard (Figs. 1084, 1085),

Fig. 1083.

Lymnaea pachygaster
Fresh - water
Miocene ; Mörsingen,
near Ulm.

Thom.

JlFiG. 1084.

Planorhis cornu Brongt. var. mantelli
Dnnker. Upper Miocene; Mundingen,
Wiirtemberg.

outer margin sharp. Upper Jura (Purbeck)
Discoidal (exceptionally turreted), with

CLASs IV GASTROPODA 575

many whorls. Aperture oval to crescent-shaped ; outer margin sharp. Lias to
Recent ; very profuse in the Tertiary. P. multiformis (Bronn), from the Middle

^^

Fig. 1065.

Planorbis multiformis (Bronn). Upper Miocene fresh-water limestone; Steinheim, near Heidenheim,
Würt«mberg. A, var. suprema. B, var. trochifonnis. C, var. elegans. D, var, steinheimensis.

Miocene of Steinheim in Würtemberg, is particularly interesting on account of its
extraordinary variability. The different mutations of the species are usually found
at different liorizons of the fresh-water limestone occurring there, and constitute,
according to Hilgendorf and Hyatt, a remarkable genealogical sequence.

Isidora Ehr. Shell siniilar to that of Physa. Recent ; tropical countries.

Family 5. Ancylidae Dali.

Shell liiiqiet-shaped, conical^ not spiral, or with the apex recurved. Tertiary and
Recent.

Ancylus Geoftrey (Fig. 1086). Shell simply conical or with the apex slightly
incurved. Tertiary and Recent.

Gundlachia Pfeiff. A partial septum is developed at the end of
the first season's growth. Tertiary of Mayence Basin and Recent.

Suborder C. TELETREMATA Pilsbry.

Shell ahsent ; mantle covering the whole upper surface of the body.
Male and female orißces widely separated ; lung orifice and anus ^^^' ^^^^-

ventral and near the tau. DelÄcfiS:?

Several families of this suborder are recognised {Vaginulidae, ^^^^ " oursau .
Rathouisiidae, Onchidiidae), but owing to the absence of a shell, their remains are
not preservable in the fossil State.

Suborder D. STYLOMMATOPHORA A. Schmidt. Land Snails.

Eyes hörne on the extremüies of two peduncleSy which are capahle of invagination ;
a pair of short tentacles, rarely obsolete, are placed in front of them. Male and female
genital orißces contiguous, or uniting in a common vestibule, situated at the right or
left side of the head. Buccal retractors present ; lung foram^n and anus anterior to the
end of the foot, not ventral.

This suborder comprises most recent and all fossil land snails, and is divisible
into series or superfamily groups. The families proper are based almost wholly upon
characters of the soft anatomy, which are herein largely omitted or abridged.

Superfamily 1. HOLOPODA Pilsbry.

No longitudinal grooves above the margins of the foot ; jaw present, teeth quadrate.

Family 1. Helicidae Keferstein. Helices.
Shell depressed, globose or oval and elevated. Tertiary and Recent

This comprises an enormous assemblage in the Recent fauna, but most of the genera
have not as yet been found fossil. All the typical forms will probably in time be

576

MOLLUSCA

PHYLUM VI

traced back to tlie Eocene. Subfamily and generic characters are based largely upon
the genital System, and hence are of little practical importance to the paleontologist.

Polygyra Say. Globose or depressed,
Oligocene to Eecent ; North America.

Sagda Beck. Glossy, with many close

Fig. 1087.

A, Ilelix (DniiorplioptycMa) arnouldi Michaud. Lower
Eocene ; Rilly, near Rheims. B, Helix (Campylaea) inflexa
Klein. Upper Miocene ; Mörsingen. C, Helicodonta osculum
Thoni. Lower- Miocene ; Hochheim, near Wiesbaden.

with the lip reflected, often toothed.

whorls, the last usually with internal
laminae and a sharp lip. Oligocene to
Eecent ; Antilles.

Pleurodonta Fischer von Wald.
Solid, large, depressed and generally
keeled ; aperture often toothed. Oligo-
cene to Eecent ; Antilles, Florida.

Helix Linn. (Fig. 1087, Ä, B).
Shell semi-globose, conical to discoidal,
manifesting great variability of form.
Aperture oblique, crescentic or rounded,
with disconnected margin s. Very pro-
fuse in the Tertiary and Eecent of Europe and adjacent regions of Asia and Africa.

Helicodonta Fer. (Fig. 1087, G). Similar to Helix, but with thickened or
denticulated lip. Oligocene to Eecent ; Europe.

Other allied genera occur in European Tertiary deposits.
Eecent Helicidae reproducing by extraordinarily large eggs are
the foUowing : Helicophanta of Madagascar, Acavus of Ceylon,
Panda of Australia, and Strophocheilus of South America.

Family 2. Bulimulidae Fischer.

Shell elongated, ovate, with narroio umhilicus or none. Ter-
tiary and Eecent.

Bulimulus Leach. Oligocene to Eecent ; America. Amphi-
dromus Alb. Tertiary ; Europe and Asia.

Family 3. Pupidae Albers.

Shell small, cylindrical or oval, with narroio whorls. Tertiary
and Eecent ; also in the Carboniferous.

Glausilia Drap. (Fig. 1088). Shell turreted to
Aperture pyriform, with usually continuous peristome.

lOSS.

A, Glausilia hulimoides
A. Braun. Lower Miocene ;
Eckingen, near Ulm. B, C.
antiqua Schübler. Same
locality.

fusiform, slender, sinistral.
Inner lip bearing two folds ;
outer margin somewhat reflected ; the aper-
ture usually closed by a movable calcareous
plate. Occurs sparingly fossil from the
Eocene onward, and represented by about
400 Eecent species.

Pupa Lam. (Fig. 1089, B). Shell small,
cylindrical- ovate. Aperture semicircular,
usually constricted by teeth on the colu-
mella and inner and outer lips. The outer
margin reflected. Tertiary and Eecent.

Dendropupa Dawson (Fig. 1089, Ä).
Like the last, but aperture without teeth.
Upper Carboniferous ; Nova Scotia.
Vertigo Müller. Tertiary and Eecent.
Buliminus Ehrb. (Fig. 1090). High conical, solid, turreted. Eocene to Eecent.

Fig. 1089.

vetusta

A, Dendropupa
Dawson. Goal Measures ;
Nova Scotia (after Dawson).
B, Pupa diversidens Sandb.
Miocene ; Sansan, Gers (after
Sand berger).

Fig. 1090.

'Buliminus (Petraeus)
complanatus Reuss.
Lower Miocene;
Thalflngen, near Ulm.

ci'Ass IV GASTROPODA 577

Family 4. Achatinidae Pilsbry.

Ovate or elongate, imperforate shells, luüh the coluraella generally truncated at the
hase. Upper Cretaceoiis to Receiit.

Achatina Lam. Recent ; tropical Africa.

Stenofjyra Sliuttlew. ; Rumina Risso ; Opeas Alb.; Rhodea
Adams. These are all small menibers of tlie group, mainly Recent.

Megaspira Lea (Fig. 1091). Tiirreted, sleiider, very long;
columella witli transverse folds. Upper Cretaceoiis to Recent.

Gochlicopa Fer. ; Äzeca Leacli ; Gaecilianella Boiirg., etc.
Tertiary and Recent.

Superfamily 2. AGNATHA Mörch. „ ^'"' ^^^^-

Megaspira exarata

Garnivorous snails, usually with no jaiv, thorn-shaped teeth, and Eocene; Riiiy°nelr
without furrows above the f 00t

Fig. 1093.

Rheims.

Family 1. Testacellidae Gray.

Shell Spiral, of very small size, and situated near the tail of the
^ vermiform animal. Tertiary and Recent.

!^M Testacella Cuvier (Fig. 1092). Shell auri-

^^ form, borne on the posterior end of the animal.

Fig. 1092 Tertiary and Recent.

Testacella zelUi Klein. ParmacelUna Sandberger. Eocene. Daude-

Miocene ; Andeifingen bardia Hartm. (Helicophanta Fer. xy.vX

(after Sandberger). <^ , i -r. , i i y

Quaternary and Recent.

Family 2. Glandinidae Albers.

Shell oval or oblong^ capable of containing the entire animal.
Cretaceoiis to Recent.

Glandina Schum. (Fig. 1093). Shell elongate-oval, with high
spire. Aperture notched in front ; columella truncated. Upper
Cretaceous to Recent. Other Recent allied genera inhabit the Reitl^'''uuZine'\

American tropics. Richelberg, near Ulm.'

Superfamily 3. AULACOPODA Pilsbry.

Foot with longitudinal grooves above and parallel with its lateral margins.

Family 1. Zonitidae Pfeiffer.

Aulacopoda with a spiral, conical or helicoid shell, sometimes partially uncoiledj
usually smooth and loith simple lip ; marginal teeth of the radula thorn-like ; foot
margin wide ; jaiv rather smooth. Carboniferous (?) to Recent.

Vitrina Drap. Shell small, translucent, with short spire, and very large body
whorl. Tertiary and Recent.

Archaeozonites Sandb. (Fig. 1094). Thick-shelled, globose, with rather high spire,
deeply umbilicate ; outer margin sharp. Oligocene and Miocene. Here also should
be placed, perhaps, the archaic üTßZiic-shaped snails from the Goal Measures of Nova
Scotia.

VOL. I 2 V

5 78 MOLLUSCA phylüm vi

Zonites Montf. Like the last, biit with thinner shell, graniilatecl above, and
smooth below. Tertiary and Recent.

Fig. 1095. Fig. 1096.

Archaeozonites subverticillui! HyaUnia denudata Lychnus matheroni Requien.

Sandb, Lower Miocene; (Reuss). Miocene ; Upper Cretaceous (Gariimnian) ;

Bckingen, near Ulm. Tuchoritz, Bohemia. Rognac, Provence.

Hyalinia Fer. (Fig. 1095) ; Omphalosagda Sandb. ; Ariophanta Desm. ; Trocho-
morpha Albers. Tertiary and Recent.

Lychnus Montf. (Fig. 1096). Body wliorl large, bent upward at first, and later
decurved, so tbat the margins of tbe aperture lie in the basal plane. Upper
Cretaceous of Provence and Spain.

Family 2. Limacidae Lamarck.

NaJced slugs having a small vestigial shell, ßat and non-spiral, concealed within the
mantle, which latter forms a small oval shield on the forepart of the hody. Foot margin
narrow ; dentition and jaw as in the Zonitidae. Tertiary and Recent.

The principal genera are Limax Linn., in which the intestine has four longi-
tudinal folds, and the back is keeled at the tail only ; and Amalia Moq.-Tand., with
Spiral gut and strongly keeled back. Their small scale-like shells have been found
in the Tertiary and Pleistocene ; present distribution nearly world-wide.

Family 3. Endodontidae Pilsbry.

Shell Spiral and external, varying from cylindric to helicoid and planorhoid, usually
rih-sculptured and with opaque colouring ; lip thin, unex2)anded. Jaiv of separate or
united imbricating plates, or solid and striated ; marginal teeth squarish ; genitalia
without accessory organs. Carboniferous to Recent.

Punctinae. Jaw of numerous separate plates ; shell minute. Includes the
Holarctic genera Punctum Morse and Sphyradium, Charp., also the New Zealand
genus Laoma Gray. Recent.

Endodontinae. Jaw-plates united more or less completely. Genera : Fyramidula
Fitz. Discoidal or low conical, with tubulär ribbed whorls and open umbilicus.
Carboniferous to Recent. This is one of the most ancient land Mollusks known, and
is the oldest Helicoid form. Phasis, Ämphidoxa, Flammulina and Endodonta Alb.
are similar austral forms, but are only known Recent.

Family 4. Arionidae Gray.

Slugs having the shell rediiced to a ßat plate or a few granules, nearly or entirely
concealed, or ahsent. Mantle in the form of a shield on anterior part of the hody ; teeth
of the quadrate type. Recent.

This family is probably derived from the Endodontidae by degeneration of the
shell. Ärion Fer., and Änadenus Heyn, are leading genera of Europe and Asia ;
Ariolimax Mörch, and Prophysaon Bland occur abundantly in North America.

CLA>ss IV GASTROPODA 579

Family 5. Philomycidae Gray.

Slugs someiühat similar to Arionidae, hut the mantle Covers the entire U2)per surface
of the body. Ä shell is completely ahsent ; hence no fossil forms are hnown.

Superfamily 4. ELASMOGNATHA Mörch.

Jaio vnth a strong squarish process of attachment ahove.

Family 1. Succineidae Albers.
Shell thin, ovate^ consisting of few whorls.

Fig. 1097.

Succinea Pfeiffer (Fig. 1097). Shell thin, ovate, amber-coloured, SiuTinea peregHna
transluceiit, witli short spire and large body whorl. Outer margin cene;' Tuchoritz,
of apertiue sharp. Tertiary and Recent ; abundant in the Loess, Bohemia.

Range and Distribution of the Gastropoda.

Of all classes of Mollusks, the Gastropods exhibit the most manifold
variety. Beginning in the Cambrian, they acquire a very gradual increase
and distribution, and are at present enjoying their maximum vigour. There
exist probably over 20,000 Recent species, about thtee-fifths of which have
gills, the remainder being air-breathers.

At the base of the Cambrian (Olenellus zone) are found such archaic
genera as Scenella, Stenotheca, Platyceras, Bhaphistoma, Pleurotomaria ; a number
of Pteropods with some doubtful forms {Hyolithes, Hyolithellus, SaltereUa, Torel-
lella, etc.), which evince the great antiquity of the Aspidobranchs ; and forms
resembling the Capulidae. In the later Cambrian the Rhipidoglossa (represented
by the Plemvtomariidae, Euomphalidae and B eller ophontidae) predominate ; and
associated with these are certain Pteropod remains, members of the Capulidae,
and a few genera probably referable to the Turhinidae. A notable genus
occurring here is Subulites, which bears some resemblance to the Pyramidellidae,
and exhibits a distinct channelling at the base of the columella.

Unfortunately the poorly preserved remains of Cambrian Gastropods afFord
but scanty information regarding the disposition of the soft parts ; neverthe-
less there are good, although purely theoretical reasons for supposing that
the Rhipidoglossa and Ctenobranchs were formerly not so widely separated as
at present.

During the Ordovician and Silurian, Gastropods increased perceptibly in
the number of species, and a few new families were initiated (Epitoniidae,
Purpurinidae, Trochidae, Xenophoridae) ; but the faunal aspect remained on
the whole much the same as in the Cambrian, and no essential changes were
introduced during the remainder of the Paleozoic. Accordingly, the Paleo-
zoic Gastropod fauna may be said to be characterised by its general simplicity,
being made up principally of Pteropods, Rhipidoglossa, -a few Docoglossa
and Opisth'obranchs, and also a scattering representation of Ctenobranchs
(Capulidae, Pyramidellidae, Littorinidae).

During the Jura-Trias, the large, thick-shelled varieties of Pteropod-like
Mollusks became extinct. But, on the other hand, various families of the
Rhipidoglossa reached the acme of their development {Pleurotomariidae, Tur-
hinidae, Nerilopsidae, Neritidae); and among the Ctenobranchs, the families

580 MOLLUSCA phylum vi

TABLE SHOWING THE VERTICAL EANGE OF THE GASTROPODA.

Fainilies.

c
Xt

'>
o

1

i

i
1

Ä

1

1

d
^

o

4i

1. Streptoneura

Order 1. Aspidobranchia

A. Docoglossa .

B. RMpidoglossa

1. Haliotidae

2. Pleurotomariidae .

3. Fissurellidae .

4. Euomphalidae

5. Raphistomidae

6. Stomatiidae .

7. Turbinidae

8. Phasianellidae

9. Delphinulidae

10. Trochonematidae .

11. Trochidae \

12. Umboniidae .

13. Neritopsidae .

14. Neritidae

Order 2. Ctenobranchia

A. Heteropoda.

B. Platypoda

1. Eulimidae

2. Pyramidellidae

3. Epitoniidae .

4. Solariidae

5. Purpurinidae .

6. Littorinidae .

7. Cyclostomidae

8. Capulidae

9. Naticidae

10. Xenophoridae

11. Ampullariidae

12. Valvatidae .

13. Viviparidae .

14. Hydrobiidae .

15. Rissoidae

16. Turritellidae .

17. Vermiculariidae

18. Caecidae

19. Melaniidae .

20. Nerineidae .

21. Cerithiidae .

22. Aporrhaidae .

23. Strombidae .

24. Columbellariidae .

—

^^^

—

..? ..

1

.. ? ..

^^^

—

—

1

^—^

—

:

— .

'

! 1

1

j

___^

—

1
i

—

i

—

1

(

i

CLASS IV

RANGE OF THE GASTROPODA

581

Families.

ä

aS

1

ä
.2

i
1

CO

i

1

s
.SS

1

i

1 ^

•-»

1
1

■i

'i

25. Cypraeidae

26. Ovulidae

27. Cassididae

28. Doliidae

29. Nyctilochidae

30. Columbellidae

31. Buccinidae

32. Muricidae

33. Thaisidae

34. Fusidae .

35. Vasidae .

36. Volutidae

37. Harpidae

38. Olividae

39. Cancellariidae

40. Terebridae .

41. Turritidae .

42. Conidae .

2. Euthyneura
Order 1. Opisthobranchia

B. Tectihranchiata

1. Acteonidae

2. Ringiculidae ,

3. Akeratidae

4. Hydatinidae .

5. Bullariidae .

6. Acteocinidae .

7. Scaphandridäe

8. Philinidae .

9. Umbraculidae

C. Bteropoda

1. Limacinidae .

2. Cavoliniidae .

3. Hyolithidae .

D. Conulariida

1. Tentaculitidae

2. Torellellidae .

3. Conulariidae .

Order 2. Pulmonata

A. Thalassophila .

B. Basominatophora

1. Auriculidae .

2. Chilinidae .

3. Physidae

4. Lymnaeidae .

5. Ancylidae

C. Teletrcmata

D. Stylommatophora

1

!

1

1

i

1

•

1

i

i

1

1

—

—

—

■ —

^

—

1

1
1

~~i

^—

""

—

—

1

—

—

—

—

1

1

1

—

1

—

1

1

i

582 ' MOLLUSCA phylum vi

Pyramidellidae Nerineidae, Purpurinidae, TurriteUidae and Aporrhaidae multi-
plied in a great variety of forms.

The Cretaceous witnessed a decided increase among the siphonostomous
Ctenobranchs, and in the Tertiary this branch asserted itself as the dominant
type of Gastropods, surpassing all other families in point of numbers, and
gradually acquiring the aspect of living genera and species. The Nerineidae,
Pyramidellidae and Aporrhaidae, which played such a prominent role along
with the Rhipidiglossa during the Mesozoic era, became in part extinct in the
Tertiary, and the remainder entered upon their decline. The great majority
of Eocene and Oligocene genera are still living, but the species have with
very few exceptions become extinct. During the Miocene, more species made
their appearance which are still in existence, and of the Pliocene species,
between 80 and 90 per cent are represented in the Recent fauna.

The geological history of the Pulmonata is remarkable. Thalassophilous
Siphonariidae are first met with in the Devonian, where they are very sparse.
Land snails (Archaeozonites, Pyramidula, Dendropupa) were initiated in still
smaller numbers during the Carbon iferous; but not until the boundary between
the Jura and Cretaceous is reached do we find any traces of fresh-water snails.
We meet them first in the Purbeck. In the Wealden, and Cretaceous gener-
ally, both land and fresh-water Gastropods are quite abundant ; they became
highly developed and widely distributed during the Tertiary, attaining, in fact,
a differentiation nearly equal to that exhibited by the corresponding Recent
forms.

The successive approximations to present conditions among Gastropod
faunas have not been confined to the production of forms simulating more and
more those now living ; they include also the gradual demarcation of existing
geographical provinces. Mesozoic Gastropods are too dissimilar in their
general characters to admit of a close comparison with modern faunas ; but as
early as the Eocene resemblances to modern forms are observable, and a certain
correspondence is to be noted with Gastropods now inhabiting somewhat
warmer zones.

The Eocene faunas of Europe, North America, Asia and Northern Africa
share a great many genera in common, and have numerous others which are
vicarious. A very difFerent aspect is presented by the Eocene fauna of
Australia, New Zealand and South America, where we find the evident fore-
runners of forms now inhabiting the southern portions of the Atlantic and
Pacific Oceans.

Still more intimate is the relationship existing between the fossil land and
fresh-water Gastropods and their descendants on the several continents. It
has been observed that Miocene faunas bear a decidedly tropical stamp. On
this account European and American forms from the inland Miocene deposits
bear some resemblance to the Recent faunas of the Azores and the West
Indies, as well as to the land and fresh-water Gastropods inhabiting the colder
latitudes of Europe and Asia. Only as recently as the Pliocene did each
geographical province come to assume its present distinctive features.

In general, the stratigraphic sequence of Gastropod groups corresponds
closely with the zoological order, the most generalised forms appearing first,
the more specialised later. Beginning with the two-gilled Rhipidoglossa and
the Docoglossa, f ollowed by the single-gilled Rhipidoglossa, Opisthobranchs and
taenioglossate Ctenobranchs, the series leads to the Rachiglossa in later Mesozoic,

CLASS V CEPHALOPODA 583

and culminates in the great increase of rachiglossate and toxoglossate families
in Tertiary and Recent times. (See tables, pp. 580, 581.)

[The text for the preceding chapter on Gastropoda was revised for the first edition of
this work by Professor Henry A. Pilsbry, of the Philadelphia Academy of Natural Sciences,
and is reprinted here with some slight changes at the hands of Drs. W. H. Dali and
R. S. Bassler. — Editor, 1

Olassö. 0EPHALOPODA.1

Head sharphj defined in Recent forms, except Nautilus. Foot transformed into a

^ Literature : Angelin, N. P., Fragmenta Silurica, edited by G. Lindströin. Stockholm, 1880.
— A7ithula, J.,iiJhev die Kreidefossilien des Kaukasus. Beitr. Pal. Österreich - Ungarns, etc.,
1899-1900, vol. xii. — Arthaber, G. von, Die Cephalopodenfauna der Reifliuger Kalke. Beitr.
Paläont. Geol. Österreich - Ungarns, etc., 1896, vol. x. — Idem, Das Jüngere Paläozoicum aus. der
Araxes-Enge bei Djulfa. Beitr. Pal. Geol. Österreich -Ungarns, 1900, vol. xii. — Idem, Die Trias
von Albanien. Ibid., 1911, vol. xxiv. —Barrande, «/., Systeme Sibirien de la Boheme, vol. ii., Cepha-
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Spezialkarte von Elsass-Lothringen, N.F., 1905, Heft vi. — Bülings, E., Palaeozoic Fossils. Geol.
Surv. Canada, 1865. — Blake, J. F., Monograph of the British Fossil Cephalopoda, pt. i. London,
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Supplem. vol. iv. — Bonarelli'G., Osservazioni sul Toarciano d' Aleniano. Boll. Soc. Geol. Italiana,
vol. xii,, 1893. — Boule, M., Lemoine P., and Thevenin, A., Cephalopodes cretaces des environs de
Diego-Suarez. Ann. de Paleontol., 1906-7, vol. i, — Branco, W., Beiträge zur Entwickelungsge-
schichte der fossilen Cephalopoden. Palaeontogr., Bd. xxvi., xxvii., 1880-81. — Brown, A. P., On
the Young of Baculites compressus. Proc. Acad. Nat. Sei. Philad., 1891-92. — Buch, L. von.
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Canavari, M. , Sui fossili del Lias inferiore nell' Appenino centrale. Atti Soc. Toscano, vol. iv.,
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1910, vol. xxiii. — Clarke, J. M., The Protoconch of Orthoceras. Amer. Geol., vol. xii., 1893. — Nanno,
a new Cephalopodan type. Ibid. xiv., 1894. — The Lower Silurian Cephalopoda of Minnesota.
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Devonian Systems, etc. Journ. Acad. Nat. Sei. Philad., vol. viii., 1839-42. — Observations on
Recent and Fossil Shells. Amer. Journ. Couch., vol. ii., 1866. — Deslongchamps, E., Memoire sur
les Teudopsides. Mem. Soc. Linn. Normandie, vol. v., 1835. — Diener, C, Triadische Cephalopoden-
faunen der ostsibirischen Küstenprovinz. Mem. Com. Geol. St. Petersb., vol. xiv. No. 3, 1895.
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— Diener, C, and Kraft, A. v., Palaeontol. Indica, Lower Triassic Cephalopoda from Spiti, Malla-
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Limestone. Amer. Journ. Sei. [3], 1884, vol. xxvii.— Favre, F., Die Ammonitiden der unt. Kreide
Patagoniens. N. Jahrb. f. Min., 1908, Supplem. vol. xxv.

Foord, A. H., Catalogue of the Fossil Cephalopoda in the British Museum, pt. i., 1888 ; ii.,
1891 ; iii. (Foord and Crick), 1%%!.— Frech, F., Lethaea Geognostica, I. Teil. Lethaea Palaeozoica,
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Ungarns, etc., 1902, vol. xiv.— Neue Cephaloi)oden aus den Buchensteiner, Wengener, und Raibler
Schichten des südlichen Bakony. Res. Wiss. Erf. Balatonsees, 1903, vol. i.—Fncini, A., La Fauna
del Lias medio del Monte Calvi. Palaeont. Italica, vol. ii., 1897.— Ammoniti del Lias medio
deir Appenino centrale. Pal. Ital., 1899, vol. v. — Cephalopodi liassici del Monte di Cetona. /6w/.,
1901, vol. vü.—Gabb, W. M., and Meek, F. B., Geol. Surv. California. Palaeontology, vols. i., ii.,
l^Qi-Q'd.—Gemmellaro, G. G., La Fauna dei calcari con Fusulina, Palermo, 1887-89.— I Cefalopodi

584 MOLLUSCA phylum vi

funnel-shaped muscular swimming-organ ; mouth provided with jaws and radula.

del Trias superiore della regione occidentale della Sicilia. Giorn. Soc. Sei. Nat. Palermo, 1904,
vol. xxiv. — Grandjean, F., Le Siphon des Aramonites et des Beleinnites. Bull. Soc. Geol. France,
1910, vol. x.—Griesbach, C. L., Palaeontological Notes on the Lower Trias of the Himalayas.
Records Geol. Surv. India, vols. xiii., xiv., 1880-81. — Orossouore, A., Les Animonites de la Craie
superieure de la France. Explic, Carte Geol. France, 1893. — Gümbel, C. W., Ueber die baierisclien
Alpen. Verhandl. Geol. Reichsanst. Wien, Bd. xii., 1861-62. — Revision der Goniatiten des
Fichtelgebirges, Neues Jahrb., 1862. — Ueber Clymenien in den Uebergangsgebilden des Fichtel-
gebirges. Palaeontogr., Bd. xi., 1863-64. — Hall, J., Palaeontology of New York, vols. i.-iii., v.,
Albany, 1847-79. — Rauer, F, v.. Die Cephalopoden des Salzkammergutes und des Muschelmarmors.
Wien, 1846. — Neue Cephalopoden von Hallstadt und Aussee. Haidinger's Wissen. Abhandl.,
vols. i.-iii., 1847-50. — Beiträge zur Kenntniss der Cephalopodeufauna der Hallstädter Schichten.
Denkschr. Akad. Wiss. Wien, Bd. ix., 1855. — Nachträge, Sitzungsber., Bd. xli., 1860. — Choristo-
ceras, etc. Jbid. Bd. lii., 1866. — Die Cephalopoden des bosnischen Muschelkalkes. Denkschr.
Akad. Wiss. Wien, vols. liv., lix., 1888-92. — Hang, F., Beiträge zu einer Monographie der
Ammoniten-Gattung Harpoceras. Neues Jahrb. Beilage Bd. iii., 1885.— Über die Polymorphidae,
etc. Ibid. Bd. ii., 1887. — Hoernes, R., Zur Ontogenie und Phylogenie der Cephalopoden. Jahrb.
Geol. Reichsanst., 1903, vol. liii. — Holm, G., Ueber die innere Organisation einiger silurischer
Cephalopoden. Palaeont. Abhandl. Bd. iii., 1885. — Tvenne Gyroceras -formigt böjda Endoceras-
Arter. Geol. Foren. Stockholm Förhandl., Bd. xiv. Hefte 2, 3, 1892. — Om de endosifonala
bildningarna hos familien Endoceratidae. Ibid. xvii. Heft 6, 1895. — Om apikaläuden hos Endoceras.
Ibid. vols. xviii., xix., 1896-97. — Holzapfel, F., Die Cephalopoden-führenden Kalke des unteren
Carbon. Palaeont. Abhandl. Bd. v. Heft 1, 1889. — Die Cephalopoden des Domanik. Mnm. Com.
Geol. St. Petersbourg, 1899, vol. xii. — Huxley, T. IL, Structure of Belemnites. Mem. Geol. Surv.
United Kingdom, Monogr. ii., 1864. — Hyatt, A., The Fossil Cephalopods of the Museum of Com-
parative Zoology. Bull. M. C. Z., vol. i., 1868. — Remarks on Agassiceras and Oxynoticeras.
Proc. Boston Soc. Nat. Hist., vol. xvii., 1875. — The Jurassic and Cretaceous Ammonites collected
in South America. Ibid. xvii., 1875. — Genera of Fossil Cephalopods. Ibid. xxii., 1884. — The
Genesis of the Arietidae. Smithson. Miscell. Collect., No. 673, and Memoirs M. C. Z., vol. xvi.,
1889. — Carboniferous Cephalopoda. I., 2nd Ann. Rep. Geol. Surv. Texas, 1890; II. 4th Ann,
Rep., 1892. — Pliylogeny of an Acquired Characteristic. Proc. Amer. Philos. Soc. vol. xxxii. No.
143, 1894. — Remarks on the Genus Nanno. Amer. Geol., vol. xvi., 1895. — Pseudoceratites of the
Cretaceous. Mon. xliv., U.S. Geol. Survey, 1903. — Hyatt, ^., and Smith, J. P., Triassic Cephalopod
Genera of America. Prof. Papers, No. xl., U.S. Geol. Survey, 1905. — Karakasch, N. J., Le Cretace
Inferieure de la Crimen et sa faune. Trav. Soc. Imper. Nat., St. Petersburg, 1907, vol. xxxii.

Karpinsky, A., Über die Ammoneen der Artinsk - Stufe, etc. Mem, Acad. Sei. Imp. St.
Petersb. [7], vol. xxxvii., No. 2, 1889. — Kilian, W., Sur quelques fossiles du Cretace inferieur de
la Provence. Bull. Soc. Geol. France, vol. xiii., 1888.— Äi7<Z, F., Die Cephalopoden der oberen
Werfenerschichten von Mu(5 in Dalmatien, etc, Abhandl. Geol. Reichsanst. Wien, 1903, vol. xx.
— Koenen, A. v.. Die Ammonitiden des Norddeutschen Neokom, Abhandl. Preuss. Geol. Landesan-
stalt, 1902, Heft 24. — Ko7iinch, L. G. de, Faune du calcaire carbonifere de la Belgique, pt. ii.,
Cephalopodes. Ann. Mus. Nat. Hist. Bruxelles, vol. v., 1880. — Kossmat, F., Untersuchungen
über die südindische Kreideformation. Beitr. Österreich- Ungarns und Orients, vol. ix., 1895.—
Laube, G. (J., and Bruder, G., Ammoniten der böhmischen Kreide. Palaeontogr., Bd. xxxiii.,
1887. — Lindstrim, G., Ascoceratidae and Lituitidae of the Upper Silurian Formation of Gotland.
K. Svensk. Vetensk. Akad. Handling., Bd. xxiii., 1889. Philos. Trans. 1848, \^h^.~Martelli, A.,
Cefalopodi triasici-di Boljevici (Montenegro). Pal. Ital., 1907, vol. x. — Matheron, P., Recherches
paleontologiques dans le midi de la France. Marseille, 1879-81. — Meek, F. B., Report on the
Invertebrate Cretaceous and Tertiary Fossils of the Upper Missouri Country. U.S. Geol. Surv.
Territ., vol. ix., 1876. — Palaeontology, U.S, Geol. Exploration 40th Parallel Surv., vol. iv.pt. i.
(with notes on Ammonites by A. Hyatt), 1877. — Meek, F. B., and Hayden, F. F., Palaeontology
of the Upper Missouri. Smithsonian Contrib. Knowl. vol. xiv., 1866.— Meneghini, G., Monographie
des fossiles du calcaire rouge ammonitique (Lias superieur) de Lombardie. Paleont. Lombardie.
Milan, 1867-81. — Mojsisovics, F. v., Das Gebirge um Hallstadt. Abhandl. Geol. Reichsanst.
Wien, Bd. vi., 1873-75, suppl. Heft, 1902 ; pt. iL, ibid., 1893.— Die Cephalopoden der mediter-
ranen Triasprovinz. Ibid. Bd. x., 1882. — Über einige arktische Trias Ammoniten des nördlichen
Sibirien. Mem, Acad. Imp. Sei. St. Petersb. (7), vol. xxxvi. no. 5, 1888. — Beiträge zur Kenntniss
der obertriadischen Cephalopoden-Faunen des Himalaya. Denkschr. Akad. Wiss. Wien, Bd. Ixiii.,
1896. — Münster, G. von, Beiträge zur Petrefactenkunde, i.-viii., 1839-46. — Ueber die Clymenien und
Goniatiten im Uebergangskalk des Fichtelgebirges. Bayreuth, 1843.

Neumayr, M., Jurastudien. Jahrl). Geol. Reichsanst. Wien, Bd, xxi., 1871.— Die Cephalo-
poden-Fauna der Oolithe von Baiin bei Krakau. Abh. Geol. Reichsanst. Wien, Bd, v., 1871-73.
— Die Fauna der Schichten mit Aspidoceras acanthicum, etc. Verhandl. Geol. Reichsanst, Wien,
1874. — Ueber Kreideammoniten. Sitzungsber. Akad. Wiss. Wien, Bd. Ixxi., 1875 ; also in Zeitschr.
Deutsch. Geol. Ges., Bd. xxvii., 1875. — Ueber unvermittelt auftreteufle Cephalopodentypen im

CLAss V CEPHALOPODA 585

Sexes separate. Sensory organs highly developed. A circle of fleshy arms or ten-

Jura Mittel-Europa's. Jalirb. Geol. Reichsanst. Wien, Bd. xxviii., 1878. — Zur Kenntniss der
Fauna des untersten Lias in den Nordalpen. Abhandl. Geol. Reichsanst. Wien, B<1. vii. Heft 5,
1874-82. — Newnayr^ M., and Uklig, F., Ueber Ammonitiden aus den Hilsbildungen Nord-
deutschlands. Palaeontogr., Bd. xxvii., 1881. — Nickles, R., Contributions ä la paleontologie du
Sud-Est de l'Espagne. Mem. Soc. Geol. France, No. 4, 1890. — Niküin, S. N., Der Jura der
Umgegend von Elatma, Nouv. Mem. Soc. Imp. Moscou, vols. xiv., xv., 1879-89. — Allgemeine
geologische Karte von Russland, Blatt 56. Mem. Com. Geol. St. Petersb., vol. i., No. 2, 1884.
— Die Cephalopodenfauua der Jurabildungen des Gouvernements Kostroma. Verhandl. Russ.
Mineral. Gesellsch, [2], vol. xx. 1885. — Noelling, F., Cambrische und silurische Geschiebe Ost-
und West - Preussens. Jahrb. preuss. geol. Landesanst. und Bergsakad., 1882, — Beitrag zur
Kenntniss der Cephalopoden des Provinz Ost-Preussens. Ibid. 1883; also Zeitschr. Deutsch. Geol.
Gesellsch., Bd. xxxiv., 1882. — Fauna of Neocomian Belemnite Beds. Palaeont. Indica, Ser.
xvi., i., pts. 2, 3, 1897. — Untersuchungen über den Bau der Lobenlinie von Fseudosayeceras rmclti-
lobatum Noetling. Palaeontographica, 1905, vol. li. — Oppel, A., Palaeontologische Mittheilungen
aus dem Museum des baierischen Staates. Stuttgart, 1860-65. — d'Orbigny, A., Paleontologie
fraufaise, terrain cretace. I. Cephalopodes, 1840 ; Terrain jurassique, Cephalopodes, 1852.
— Prodrome de Paleontologie Stratigraphique. Paris, 1850-53. — Parona, C. F., Nuove osser-
vazioni sopra la fauna con Posidonomya alpina, etc. Palaeontogr. Italica, vol. i., 1896. — Fossili
albiani d' Escragnolles, del Nizzardo, etc. Ibid. ii., 1897. — Paulke, W., Die Cephalopoden der ob.
Kreide Südpatagoniens. Ber. Naturforsch. Gesell. Freiburg, 1905, vol. xv. — Pervinquiere, L. , Etudes
de paleontologie Tunisienne, I. Cephalopodes des terrains secondaires. Carte geol. de la Tunisie,
1907. — Philipjri, E., Die Ceratiten des oberen deutschen Muschelkalkes. Pal. Abhandl. N.F., 1901,
vol. iv. — Phillips, J., Illustrations of the Geology of Yorkshire, pt. ii. London, 1836. — Figures and
Descriptions of the Palaeozoic Fossils of Cornwall, Devon, etc. London, 1841. — Pictet, F. J.,
and Campiche, G., Description des fossiles du terrain cretace des environs de Ste. Croix. Geneva,
1858-72. — Pompeckj, J. F., Beiträge zu einer Revision der Ammoniten des schwäbischen Jura, Lief,
i., ii. Stuttgart, 1893-96. — Über Animonoideen mit "anormaler" Wohnkammer. Jahreshefte
Vaterl. Naturk. Wilrttemb., 1894. — Ammoniten des Rhät. Neues Jahrb., Bd. ii., 1895.

Quenstedt, F. A., Ueber die vorzüglichsten Kennzeichnen der Nautileen. Neues Jahrb.,
1840. — Petrefactenkunde Deutschlands, I. Cephalopoden. Tübingen, 1849. — Der Jura. Tübingen,
1858. — Die Ammoniten des schwäbischen Jura, Bd. i.-iii. Stuttgart, 1885-88. — Remele, A.,
Zur Gattung Palaeonautilus. Zeitschr. Deutsch. Geol. Gesellsch., Bd. xxiii., 1881. — Renz, C,
Die mesozoischen Faunen Griechenlands. I. Die triadischen Faunen der Argolis. Palaeontogr.,
1911, vol. Iviii. — Reynes, P., Monographie des Ammonites. (Text incomplete), 1879. — Roemer,
F. V., Lethaea Geognostica. I. Lethaea Palaeontologica. Stuttgart, 1880-83. — Das rheinische
Uebergangsgebirge. Hannover, 1844. — Riidemann, R., Structure of some primitive Cephalopods.
Report N.Y. State Paleontologist, 1904. — Sandberger, G., Beobachtungen über die Organisation
der Goniatiten. Jahrb. Ver. NatUrk. Nassau, Bd. vii. p. 292, 1851. — Sandberger, G. and F., Die
Versteinerungen des rheinischen Schichtensystems in Nassau. Wiesbaden, 1850-55. — Schlüter,
(!., Cephalopoden der oberen deutschen Kreide. Palaeontogr., Bd. xxi., xxiv., 1872-77. — Schröder,
II., Untersuchungen über silurische Cephalopoden. Palaeont. Abhandl., Bd. v. Heft 4, 1891. —
Siemiradzki, J., Monograph. Beschreib, der Ammonitengattung Perisphinctes. Palaeontogr., 1899,
vol. xliv. — Smith, J. F., Comparative Study of Palaeontology and Phylogeny. Journ. Geol.,
vol. V. No. 5, 1897. — Marine Fossils of the Coal Measures of Arkansas. Proc. Amer. Philos. Soc.
vol. xxxv., 1897. — The Development of Glyphioceras, etc. Proc. Calif. Acad. Sei. [3], vol. i.,
1897. — Tlie Carboniferous Ammonoids of America. Mon. xlii., U.S. Geol. Survey, 1903. — Siein-
maun, G., Ueber Tithon und Kreide in den peruanischen Anden. Neues Jahrb., Bd. ii., 1881.
—Stauton, T. W., The Colorado Formation. Bull. U.S. Geol. Surv. No. 106, \%^Z.—Stoliczka,
F., and Blanford, H. F., Fossil Cephalopoda of the Cretaceous Rocks of Southern India. — Mem.
Geol. Surv. India, Palaeont.. Indica, 1861-66.— Äwe^s, F., Ueber Ammoniten. Sitzungsber. Akad.
Wiss. Wien, Bd. lii., Ixi., 1866-70.— TtY^, A., Die fossilen Cephalopodengebisse. Jahrb. Geol.
Reichsanst. Wien, 1907, vol. liv. — Tornquist, A., Die degenerierten Perisphinctiden des Kimmeridge
von Le Havre. Abhandl. Schweizer. Pal. Gesellsch., Bd. xxiii., 1896.— Tot^a, F., Eine Muschelkalk-
fauna am Golfe von Ismid in Kleinasien. Beitr. Paläont. Geol. Österreich -Ungarns u. Orients,
Bd. X., 1896. — Uhlig, F., Die Cephalopodenfauua der Wernsdörfer Schichten. Denkschr. Akad.
Wiss. Wien, Bd. xlvi., and Sitzungsl)er. Bd. Ixxxvi., 1883. — Über die Cephalopodenfauua der
Teschener und Grodischter Schichten. Denkschr. Akad. Wiss. Wien, 1901, vol. Ixxii.— The
Fauna of the SpUi shales. Pal. Indica, ser. xv., 1910, vol. iv. — Waageii, TF., The Jurassic Fauna
of Kutch, vol. i. Cephalopoda. Palaeont. Indica, ser. ix., 1873-76.— Salt Range Fossils. I.
Productus Limestone Fossils ; Cephalopoda. Ibid. ser. xiii., 1879-88. II. Fossils froni the
Ceratite Formation. Ibid. ser. xiii., 1895.— Wähner, F., Beiträge zur Kenntniss der tieferen
Zonen des unteren Lias der nordöstlichen Alpen. Beitr. Paläont. Geol. Österreich-Ungarns u.
Orients, Bd. ii., ix., 1882-95. — Wag^ier, A., Fossile Überreste von nackten Tintenfischen. Abh.
Bayer. Akad. Wiss., Bd. viii., 1856-60. — Wedekind, R., Die Cephalopotlenfauna des höheren

586 MOLLUSCA phylum vi

tades Surround the moufh, and serve as prehensile and locomotive organs ; in the
Dibranchiates tliey are armed with hooJcs and sucker s.^

The Cephalopods are the most highly organised, and include the largest-
sized of all known Mollusca. They breathe by gills, and are exclusively marine.
Their nervous, circulatory, digestiye and reproductive Systems, their muscula-
ture and sense organs all exhibit remarkable differentiation as compared with
those of other Mollusks. A fleshy mantle, which is open above, encloses the
cavity which is occupied by the respiratory organs (the gills) and it also
serves as a covering for the reproductive, alimentary and secretory Systems,
the heart and the principal blood-vessels. A large ganglionic mass (cerebral
ganglion) and sub-oesophageal ganglion connected by commissures are placed
around the Oesophagus, and are surrounded by a cartilaginous enclosure in the
Dibranchiates, but in Nautilus this protects only the sub-oesophageal nerve mass.

Eecent Cephalopods were divided by Owen into two groups — Tetrahranchiata
and Dibranchiata. The former is represented in the present fauna by the soli-
tary genus Nautilus, but the latter still comprises a very considerable series of
forms. A host of fossil Cephalopods abounded in the Paleozoic and Mesozoic
seas. Among these the two largest groups, the Ammonoidea and Belemnoidea, do
not afford any certain information regarding the number of gills, but the shells
of the former agree essentially with those of Nautili, while those of Belemnites,
on the other band, are more like those of certain Dibranchiates ; hence it is
advisable to associate these fossil groups with the corresponding sub-classes
established for Eecent forms.

Subclass 1. TETRABRANCHIATA Owen.'

Cephalopods with four plumose gillSj and external chambered shells. Amhula-

Oberdevon am Enkeberg. Neues Jahrb. f. Min. etc., 1908, Supplem. vol. xxvi. — White, C. A.,
Mesozoic Fossils. Bull. U.S. Geol. Surv. No. 4, ISSA.—Whüeaves, J. F., Mesozoic Fossils,
vol. i. Geol. Surv. Canada, 1876-79. — Palaeozoic Fossils, vol. iii., ibid. 1884-97. — Contributions
to Canadian Palaeontology, vol. i., 1885-89. — Descriptions of Fossils from the Devonian of Manitoba.
Trans. Roy. Soc. Canada, vol. viii. sec. 4, 1890. — Whitßeld, R. P., Several papers in Bull. Amer.
Mus. Nat. Hist., 1886-97.— Eepublication of Hall's Fossils, etc. Ibid. vol. i., pt. ii., 1895.
Wright, T., Monograph on the Lias Ammouites. Palaeont. Soc, 1878-86. — Würtenberger, R.,
Studien über die Stammgeschichte der Ammoniten. Darwinistische Schriften, No. 5. Leipzic,
1880. — Vabe, H., Cretaceous Cephalopoda from the Hokkaido. Journ. Coli. Sei. Iniper. Univ.
Tokyo, Japan, 1904, vols. xix., xx. — Zittel, K. A., Cephalopoden der Stramberger Schichten.
Palaeont. Mittheil. Museum Bayer. Staates, Bd. ii., 1868. — Die Fauna der älteren Tithonbildungen.
Ibid. Bd. iii., 1870.— Handbuch der Paläontologie, Bd. iL, 1881-85.

^ A. E. Verrill has furnished the following note regarding the arms of Cephalopods : " The
arms, together with the siphon (ambulatory funnel) of Cephalopods, must be considered as
homologous with the foot of other Mollusca. The large nerves supplying these organs arise from
the pedal ganglia. In the early larval stages the arms arise as bud-like, paired lateral outgrowths
at the base of the large yolk-sac, while the rudiments of the siphon (fxmnel) arise as two oblique
pairs of folds situated farther back. The anterior pair of these folds eventnally unite and form
the central or tubulär part of the siphon, and the more posterior folds form the lateral or valvulär
portions of the same organ. The rudimentary arms arise posterior to the mouth on the ventral
and lateral sides of the yolk-sac, and only Surround the buccal region at a later stage. The
yolk-sac occupies the same relative position, behind the mouth, as the central part of the foot-
area of ordinary Gastropod larvae in the early veliger stages. Therefore the arms are muscular,
lateral outgrowths of this same foot-area. The two lateral rows of rudimentary arms are widely
separated at first by the yolk, but during the absorption of this, they rapidly approach each other
and converge around the mouth."

2 Owen, R., Memoir on the Pearly Nautilus. London, 1832, — Kerr, J. O., Anatomy of
Nautilus pompilius. Proc. Zool. Soc, London, 1895. — Griffin, L. E. , Anatomy of Nautilus
pompilius. Mem, Nat. Acad. Sei., 1900, vol. viii.

CLASS V

CEPHALOPODA

.87

tory funnel divided ; ink-lag ahsent ; arms represented in existing Nauüli by lobes
and numerous tentades, which are without hooks and suckers. Cambrian to
Recent.

Fig. 1098.

Nautilus 2^ompilius Linn.

Our knowledge of the soft parts of the Tetrabranchiates is based entirely
upon the single existing genus Nautilus (Fig. 1098). The soft parts are con-
tained in the outer-
most compartment
(living Chamber) of
the Shell, the ventral
portions being on
the external side.
The body is short
and thick, and the
head separated from
the remaining por-
tion. Around the
mouth are about
ninety external fili-
form tentacles,
placed upon the
edges of lobes, and
their basal parts
when contracted are
lodged in fleshy
sockets or sheaths.
The pair of tentacles
on the inner or
dorsal side are fused so as to form a thicker muscular lobe or hood, which
serves to close the aperture of the shell when the animal is withdrawn into
the living chamber. On the ventral side of the head and tentacles, but
separated from them, is a very thick muscular leaf, having the free edges
external and rolled in upon themselves (Fig. 1098, d). This is the so-called
ambulatory funnel of authors generally (hyponome of Hyatt), and its cavity
is contracted anteriorly and dilated posteriorly, where it opens into the
branchial chamber. It serves to conduct water which is taken by suction
into, and then violently expelled from the gill cavity of the mantle, thus
driving the creature backward by the force of reaction. Kerr suggests that the
structure of the infolding edges of the hyponome and the muscular character
of this Organ would enable the animal to unroU and flatten it out so as to be
available for crawling. It is supposed to be homologous with the foot of
Gastropods, and this Suggestion, if true, would show that it had not entirely
lost its normal functions in primitive forms of Cephalopoda.

On either side of the head, near the pair of lateral tentacles, is placed a
large eye of, primitive structure, which is supported on a short peduncle.
The mouth is in the centre of the lobes and grouj^s of tentacles, the tongue is
fleshy, and the radula armed with numerous rows of plates and hooks. The
reraarkably powerful jaws (Figs. 1099, 1100) are largely composed of a dark
horny substance, only their points being calcified. Similar calcified beaks are
not uncommon in Mesozoic terranes, being found either associated with

Recent ; Indian Ocean. Shell with contained soft
parts Seen from the left side, the shell being cut through along the median
line. a, Mantle ; b, Dorsal lobe of the mantle ; c, Hood ; d, Hyponome, or
" ambulatory funnel " ; e, Nidamental gland ; h, Muscle for attachment; o, Eye ;
s, Siphuncle ; t, Tentacles ; x, Septal Chamber (after R. Owen).

588

MOLLUSCA

PHYLUM VI

Nautiloid shells or detached. The jaws belonging to Nautilus hidorsatus from
the Trias were originally described under the name of BhynchoUtes and

Fig. 1099.

Upper jaw of Nautilus pompilius.
A, Side view ; B, Inferior aspect. i/i.

Fig. 1100.

Lower jaw' of Nautilus
pompilius. Side view. i/^.

Temnocheilus hidorsatus Schloth. ( = lihyn-
chnlithes hirundo Faure-Biguet). Muscliel-
kalk ; Laineck, near Bayreuth. A, Upper
jaw, viewed from above ; B, from the side ;
C, from below.

Conchorhynchus (Figs. 1101, 1102); the common Jurassic and Cretaceous
forms are known as llkynchoteuthis (Fig. 1103) and Palaeoteuthis d'Orbigny.
The long feather-like gills are disposed in two pairs at the base of the
hyponome, and between them is the anus, closely behind which is placed the

A Single or double orifice

of the generative Or-
gans. In the female
there is found at the
base of the gill cavity
a long, tri-
partite, nida-
mental gland,
which fuses
ex t er nally
wi th the
mantle.

The body

s h o r t,

sack - shaped,

rounded pos-

teriorly, and enveloped by the mantle. The base of the latter is prolonged
at a certain point into a fleshy, hollow cord or tube (the siphon), which passes
through a rounded aperture in each of the septa, and extends as far as the
inner side of the apex in the initial Chamber. The fastening of the animal
within the living Chamber is accomplished by two oval muscles situated on
either side near the base of the mantle. These muscles are attached to the
inner wall of the living Chamber, and have corresponding but very shallow
impressions. They are connected both dorsally and ventrally by a band of
fibres, the annulus, which also leaves its impression upon the shell. The form
and Position of the muscles for attachment and the annulus are sometimes
discernible on the internal moulds of fossil shells.

The shells of existing Nautili are coiled in one plane, and composed of
several volutions, the outermost of which either envelops all the earlier ones
{Nautilus pompilius), or leaves the umbilicus partly open (N umbilicatus).

Fig. 1102.

Temnocheilus hidorsatus Schlotheim
{= Conchorhynchus avirostris .Blainville).
Muschelkalk ; Laineck, neap Bayreuth.
Lower jaw viewed from above.

Ehynchotcuthis sahaudianus Pict. and Lor.
Neocomian ; Voirons, France. vi, Dorsal ;
aspect, showing in part the chitinous lateral
expansions. B, The calcareous beak seen
from below.

CLASS V CEPHALOPODA 589

With the exceptio!! of the last half of the outer volution, which is occupied
by the animal as a living Chamber, the shell is divided up into numerous
cavities or Chambers by parallel partitions called septa^ the mesal parts of which
are concave toward the aperture ; and they are disposed at regulär intervals.
The compartments thus formed are said by different authors to be filled
with air, gaseous or even fluid matter, and all are traversed by the siphon.^

The siphon has dense walls and is probably not capable of any extended
movements inside of the surrounding calcareous parts which form the siph-
uncle. The relation of the siphuncle to the septal Chambers in Nautilus has
not been sufficiently investigated to enable one to State distinctly what its
functions may be. The whole exterior of the mantle and siphon is encased
in a cuticle of horny matter, the remains of which are often found in the
living Chambers and siphuncles of fossil forms as well. The shell itself is
composed of two layers, an internal and an external. The outer layer is
composed of imbricated laminae, is porcellanous, light-coloured and super-
ficially ornamented with red or brown transverse bands ; the inner layer is
nacreous, and composed of thin, parallel laminae, which are crossed by fine
rectangular lines. The septa likewise consist of a pearly layer, but are
covered over like the inner walls of the Chambers with a very thin, opaque,
calcareous film. A large number of fossil shells have a structure similar to
the recent Nautilus. These are divided into several groups, characterised by
peculiarities of the initial Chamber, and by differences in the suture lines,
siphuncles, sculpturing and form of the aperture.

Our knowledge of the life-history of the Nautilus is very limited.
Although empty shells are cast ashore in great quantities in the Pacific and
Indian Oceans, the animal is rarely found alive. According to Kumpf, the
creature swims by ejecting water through the hyponome, and at the same time
holds the tentacles expanded horizontally, and the head protruded as far as
possible ; but when creeping, probably the head and tentacles are directed
downward.^ The shell is essentially alike in both cases. However, in
Nautilus pompiliuSf Willey has found that the f emales differ in having flatter
and more convergent sides, the males being stouter and more gibbous, which
is exactly contrary to the prevalent notions with regard to sex among shell-
bearing Cephalopods. The shell is supposed to serve as a hydrostatic apparatus,
sinking when the animal withdraws into the living chamber, but sufficiently
buoyant to float itself and the animal when the head and tentacles are
protruded in the act of swimming. Moseley ^ confirms the observations of

^ These conditions are described by Professor Verrill in tlie following note : ' ' The pericardium
of NmUüus ponipüms comniunicates directly with the gill cavity by special pores, which are close
to the orifices of the nephridia, but do not iinite directly with latter, as in most Mollusca. Water
can, therefore, pass directly into the pericardium and other coelomic cavities. The cavity of the
siphuncle appears to communicate directly with the pericardium, and hence with the gill cavity by
means of the special pores. Thus sea-water can readily pass into or out from the Chambers of the
shell, to equalise pressure at varying depths, as in most marine Mollusca. These Chambers are
unquestionably filled with fluid under normal conditions. But living as the animal does under
pressure at considerable depths, the fluid in the Chambers is saturated with the gases in Solution.
When the JVautüüs is rapidly brought to the surface, some of the gas is liberated in consequence of
diminished pressure, and must occupy part of the space within the chaml>ers by forcing out some of
the fluid. Hence the sliell will float until the free gases within the Chambers are absorbed or
otherwise eliminated. There is no evidence that free gases are ever naturally present in the living
Chambers during life,"

2 Rumphius, G. j&. , Amboinische Rariteitkamer, p. 59. Amsterdam, 1705.

3 Moseley IL iV., Narrative of the Voyage of the Challenger, vol. l— Fischer, P., Manuel de

590 MOLLUSCA phylum vi

Eumphius, but the animal he studied was drawn up by a dredge which had
been dragged on the bottom at a depth of 300 fathoms. This individual
swam in the manner described, but was not able to sink ; and this was
accounted for on the supposition that in rising from the bottom the sudden
expansion and rarefication of the contents of the air-chambers had interfered
with the action of the hydrostatic apparatus.

Nothing has yet been ascertained regarding the mode of reproduction
and development of the animal in Nautilus. The construction of the shell
in this genus, however, renders it probable that in the youngest stage a
perishable embryonal shell was formed, the presence of which is indicated by
a scar or cicatrix on the apex of the initial Chamber. Hyatt describes and
figures a more or less wrinkled lump on the apex of several species of the
Orthoceratidae, which he regards as an embryonal shell or protoconch ; and
Clarke also figures one having a nearly perfect form. The former explains
the absence of the protoconch in fossil genera and in the Recent Nautilus by
supposing it was usually membranous or imperfectly calcified, and hence
easily destroyed.

As the animal continued to grow, it advanced forward by building out
the edges of the aperture and secreted new septa at regulär intervals, each
one probably corresponding to a period of repose. A tubulär Prolongation of
the base of the mantle was formed at each period of progress, and this
remained behind in the first septal chamber and excreted the calcareous
matter that built the last segment of the siphuncle. Each septum bends
apically into a funnel around the origin of the siphon at the base of the
mantle, and this is continuous with a calcareous but more loosely constructed
and very porous wall that prolongs the tube begun by the funnel. This
porous wall or sheath coats the funnel on its external surface in the air-
chambers, but it continues alone apically beyond the funnel, and is inserted
into the spreading trumpet-like opening of the next preceding funnel. The
siphuncle is therefore a segmented, calcareous tube surrounding the siphon,
each segment crossing only one septal chamber and consisting of a funnel and
its connecting sheath.^

In Nautilus the margin of the external opening or aperture is sinuous, the
concavities being the sinuses, the outward convexities the crests ; and the
Single median concave bend on the venter is named the hyponomic sinus,
because it indicates the position of the hyponome. In some fossil genera
(Orthoceras) the aperture is often straight or simple (Fig. 1111); in others
the lateral margins are produced in the form of ear-like crests or lappets
(Lituites, Ophidioceras) ; and in some forms they approximate more or less,
forming contracted apertures.

The closure of the aperture is never complete, and may take place through
the inward growth of the lateral margins, as in Phragmoceras (Fig. 1136),
forming a direct dorso-ventral slit, or from the venter and the sides, as in
Mandeloceras (Fig. 1133), producing a T-shaped opening; or, as in Hercoceras
(Fig. 1120), it may occur principally from the dorsum and venter, resulting in

Conchyliologie, 1880-87.-^*7%, A., In the Home of the Nautilus. Natural Science, 1895,
vol. vi.

1 Brooks, H., On the Structure of the Siphon and Funpel in Nautilus pompilius. Proc. Boston
Soc. Nat. Hist., 1888, vol. xxiii. — AppelUf, A., Die Schalen von Sepia, Spirula und Nautilus. Kön.
Svensk. Vetensk. Akad. Handling., 1895, vol. xxv. No. 7. — Grandjean, F., Le Siphon des Ammonites
et des Belemnites. Bull. Soc. Geol. France, 1910, vol. x.

CLAss V CEPHALOPODA 591

a transverse aperture. The dorsal side of the aperture is, as a rule, occupied
by a crest, known as the dorsal crest (Figs. 1115, 1121, 1138). The position
of the hyponome is indicated by the large single opening and sinus at the
termination of the longer median slit of the aperture in shells with contracted
openings that obviously had this organ (Phragmoceras, Gomphoceras, etc.) ; but
in others like Hercoceras, which have no ventral sinus in the aperture, the
hyponome was probably absent or non-functional. The sinus in the lines of
growth, however (Fig. 1120), show that this organ was present in the pre-
ceding stages of development before the contracted apertures were formed.

Pompeckj states that contracted apertures occur only in senile stages of
growth, and small shells having this peculiarity must be regarded as dwarfs.
This is certainly true of many species, and is probably also the case with
Hercoceras and the like. T-shaped apertures often show several accessory
sinuses and crests (Fig. 1134), which probably indicate the number of their
protrusible arms or tentacles. Most curved forms have the ventral sinus on
the arched external side (exogastric shells), but some have it on the concave
internal side, as in Phragmoceras, and these are called endogastric shells. The
interior wall of the living Chamber, and volutions in recent and fossil
Nautiloids (Fig. 1122), are typically marked with fine transverse and longi-
tudinal lines. In the recent Nautilus a black superficial layer, composed in
part of organic matter, is deposited by the hood immediately in front of the
aperture on the dorsum.

The internal partitions or septa, which divide the volutions into Chambers,
Vary exceedingly in number among different species and also at diiferent ages
of the same individual ; but they are tolerably constant as a rule, within the
limits of one and the same species, if specimens of the same age are compared.
They follow one another in regulär succession, but as observed by Hyatt, the
intervals are relatively greater in the young, more constant in the adult, and
then markedly decrease in the oldest stages of development. Each septal
Chamber (camera of Hyatt) was part of the living Chamber until it was cut off
by a septum and left empty as the animal moved forward. Perfectly pre-
served shells may have the living Chamber alone filled up with stony matrix,
since the sediment could only pass into the preceding Chambers through the
siphuncle, or as a result of injury to the walls of the camerae. Nevertheless,
these last are seldom entirely empty, their interiors being frequently lined
with crystals of infiltrated calcite, quartz, celestine, baryte, pyrite, or with
organic secretions. Double septa occur in some forms (Actinoceras), and in
others the camerae are sometimes secondarily partitioned ofF by intermediate
walls or pseudo-septa, which may either run parallel with the septa proper, or
at an angle with them, and are composed of two readily separable calcareous
lamellae. The origin of these pseudo-septa has been attributed to the
calcification of regularly arched membranes at the posterior end of the body.

The line of junction between the septa and inner wall of the shell is called
the suture, This is invisible externally, except when the shell-substance has
been broken or worn, or dissolved away, and it is seen most clearly on natural
moulds. The sutures of Nautiloid shells follow, as a rule, simple, straight or
slightly undulating lines. These undulations, when convex toward the apex,
are termed lohes, and the reversed or forward curves are the saddles. They are
called lateral lohes when occurring on the sides, and when on the venter or
dorsum are termed ventral or dorsal lohes and saddles. The annular lohe is a

592 MOLLUSCA phylum vi

small median dorsal lobe, usually pointed and occupying the centre of the
main dorsal lobe. It is supposed to have had some relation to the correspond-
ing inflection or point of the annular muscle among the Nautiloidea. In more
specialised shells it is associated with a conical inflection of the septum itself.
The curves are undulatory as a rule, but in some genera may be more or less
angular.

The Position of the siphuncle does not enable one to determine which is
the ventral and which the dorsal side in most genera, but the hyponomic sinus
in the aperture and the curved lines of growth are an almost unfailing index
of the ventral side. The siphuncle is apt to change its position in the same
individual at diff'erent stages of development, but in shells of the same age
it is approximately constant, and is available for diagnostic purposes in a
number of genera.

The siphuncle differs in its form and characteristics among Paleozoic
genera, being tubulär in some (Fig. 1110), or inflated in the interseptal Spaces
in others, in such manner as to resemble a string of beads, or swollen discs
which are separated by narrow constrictions (Fig. 1126). When of consider-
able width, its cavity is partly filled up with thin calcareous lamellae (Fig.
1137), partly with the calcareous cones immediately to be described (Fig.
1105), or it is notably reduced by excretions around the interior of the
funnels forming peculiar annular swellings known as rings, and which are
generally composed of calcareous matter. The centre of the siphuncle in
these forms is usually kept open more or less perfectly by an axial tube
termed by Zittel the prosiphon (endosiphunde of Hyatt), which will be con-
sidered more fully in the descriptions of Endoceras and Adinoceras. In
Diphragmoceras the siphuncle is septate like the shell. The upper parts of
these large siphuncles were more or less unobstructed near the living Chamber,
and this part (the endoconal or siphuncular diamher of Hyatt) was doubtless
occupied by an extension of the mantle cavity, probably containing portions
of the viscera.

The funnel of the siphuncle as described above is simple in structure, and
is plainly directed towards the apex in all Nautiloids, with the exception of
Nothoceras and its allies, the funnels (?) of which are turned in the opposite
direction. The funnels, as a rule, are short and incomplete, although in
the early stages of development of many shells, and in the adult stage of
primitive forms they may be complete, extending from one septum to the next
following (Fig. 1105), or even to the second preceding this (Fig. 1104, C).
When the funnels are complete they are always contracted apically, and
inserted one within the other. The siphuncle in most Nautiloids, as in the
existing Nautilus (Fig. 1123), is apt to be more or less dilated in the younger
stages, especially in the second and first air-chambers, and it is closed at the
end within the first air-chamber by what is termed the caecum. The external
shell is perforated by an elongated scar or cicatrix (Fig. 1122), closed by a
plate, against some part of which the bottom of the caecum iropinges in the
interior. The presence of the cicatrix, as already stated, leads to the inference
that a deciduous embryonal shell or protoconch must have been present. The
shell on the apex is so much thinner than at later stages, and is so easily
abraded or destroyed, and the cicatrix itself in consequence so slightly marked
even in perfect shells, that good examples are rarely found, and when met
with require careful preparation and close Observation.

CLASS V CEPHALOPODA 593

In some Paleozoic Nautiloids with large siphuncles (Endoceras, Aäinoceras),
the apical end of the siphuncle is solid and dilated to form the nepionic bulb
(Hyatt), and this sometimes practically fiUs the camerae, and besides being
very large in a number of succeeding Chambers. The endosiphuncle expands
near the apex in these genera, and forms a good-sized conical Perforation er
cicatrix, which is obviously open at its termination (Adinoceras, Nanno).

Closely coiled shells have the apical part bent so as to enclose a vacant
Space (the umhilical Perforation) in the centre of the whorls (Fig. 1119).
This is present in all the Nautiloidea having this mode of growth, although in
some genera it is very minute. The Nautiloid shell is invariably cone-shaped,
but this may be straight or curved, or coiled in open or closed spirals, but in
rare instances it is even screw-like, or similar to a Gastropod shell. Along
with perfectly smooth shells, or those marked only with fine growth-lines,
which in some rare cases may retain traces of their original coloration, there
are others with external transverse ridges, keels, rows of tubercles or laminae ;
but this ornamentation is of a simple kind, and never attains the degree of
complexity observed among the more highly ornamented forms of Ammonoids.

Classification. — Great importance has always been attributed to the external
configuration and curvature of the shell in distinguishing genera, and the
principal groups usually named Orthoceras, Cyrtoceras, Gyroceras, Nautilus, etc.,
have been founded upon such characters. Barrande emphasised in addition
the shape of the aperture, direction of the funnels, and structure of the
siphuncle, but considered these subordinate in most cases to the general
form, and the majority of writers have followed his example. Hyatt,
however, regarded the general form and involution of the shell as relatively
minor characters, and depended upon coincidence of structure, outlines of the
aperture, and especially resemblances in developmental stages, as surer guides
to the affinities of the species and characteristics of the genera.

Terminology. — For sake of convenience, it is preferable always to speak of
the embryonal shell as the protoconch, and the later or epembryonic stages of
the shell as the conch, the term " shell " being really applicable to the entire
external skeleton inclusive of the protoconch. The history of the individual
and its shell can be divided into the following stages and substages : The
emhryo or protoconch ; the nepionic stage or infancy, represented by the apical
part of the conch ; neanic stage or adolescent part of the more mature cone ;
ephebic or adult stage of the same ; and gerontic or senile stage with which it
terminates in a complete example.

All of these stages differ materially from each other as a rule, and it is
often convenient to divide them into substages, connoted by the prefixes ana-,
meta-, snid para-. Thus the nepionic can be separated into ananepionic, meta-
nepionic and paranepionic, and it is often essential to treat the neanic and
gerontic stages in the same manner. ^

The many different forms of Nautiloid shells may be grouped into a few
leading types, as foUows : An orthocone is the young of the straight as well as
of many of the coiled forms. In this, although straight, the bands of growth
are broader on the venter than on the dorsum, and there is no hyponomic
sinus. A cyrtocone is the similar stage which replaces or, as is oftener the
case, succeeds this and is curved. Both of these may have crests in the bands

1 For a more extended discussion of terminology that can be advantageously used in descriptions
of sliells of this class See Hyatt, A., Phylogeny of au Acquired Characteristic, 1894, p. 422 et seq.
VOL. I ^ ^

594 MOLLUSCA phylum vi

of growth, on both the dorsum and venter, thus indicating that the young
animal did not possess a large hyponome. An orthoceracone is the older stage
of a straight form, and is nearly or quite straight on both venter and dorsum ;
the bands of growth are approximately equal, but there is usually a hyponomic
sinus. Cyrtoceracones are shells curved like Cyrtoceras on both venter and dorsum.
Gyroceracones are curved in a loose spiral like Gyroceras, the volutions being
sometimes in contact, but there is no impressed zone, i.e. the venter is not
involved by the overgrowth of the dorsum belonging to the next outer whorL

The impressed zone in its primitive form is the longitudinal impression
formed in the dorsum by the contact of the whorls. This is divisible into
two kinds — the contact furrow, arising and lasting only when the whorls are
in contact ; and the dorsal furrow, arising through inheritance in the young
before the whorls come in contact. There is also a third modification, which
for the present may be called the persistent dorsal furrow. This occurs in the
free senile whorls of some shells, and is a remnant of the impressed zone.
Finally, there is a furrow arising only from contact in the old age of some
distorted Ammonoids, and hence may be called the gerontic contact furrow.
Cyrtoceracones and gyroceracones do not usually have impressed zones, but
an exception is furnished by Cyrtoceras depressum.

Nautilicones are closely coiled shells having an impressed zone. This may
be only a very slight contact furrow, or a hereditary dorsal furrow deepening
by growth and Involution, as in Nautilus. Torticones are asymmetrical spirals
like those of a Gastropod, either loosely or closely coiled. These may or
may not have impressed zones. Among Nautiloids they may be distinguished
as trochoceracones, etc., according to their form, and among Ammonoids as
turriliticones, etc., when more precise descriptive terms are required. A special
nomenclature is employed in describing the position of the siphuncle, which
is of convenience in technical treatises, but may be omitted here. The septal
Chambers have been termed camerae in the sequel, because this avoids any
assertion with regard to their contents, such as is implied by " air-chambers "
and the like. The less appropriate term "loculus " has been used with the same
meaning by Holm.

Order 1. NAUTILOIDEA ZitteL

The conchs are camerated orthocones and cyrtocones in the young of primitive
forms, hecoming cyrtoceracones like the adults of these same ancestral shells in the young of
more specialised and coiled shells. Äpertures have, as a rule, ventral or hyponomic
sinuses, and crests on the dorsum. Septa are concave along the mesal plane toioards the
apex. Sutures straight or undulated, rarely with sub-angular lobes and saddles, and these
are prohahly never acutely angular, as in the Ämmonoidea. Each segment of the siph-
uncle is composed of a funnel and sheath as among primitive Ammonoids, hut the funnel
persists throughout life in the ontogeny of all forms (except perha]}S Nothoceras). Gollars
around the oral openings of the funnel are present in the later stages of Ascoceras {and
Nothoceras ?). Apex cup- or saucer-shaped, and marked hy a circular or elongated cavity
or cicatrix, tühich is more or less compressed elliptical, never transversely elliptical or
and is sometimes hidden hy the protoconch or its shrunken remnants.

The Order may be subdivided according to the general external features of
the Shell and structure of the siphuncle into five sub-orders, as follows, named with
reference to peculiarities of the funnels : — Holochoanites, Mixochoanites, Schistochoanites,

CLASS V

CEPHALOPODA

595

Orthochoanites and Cyrtochoanites. The characters of these different groups are defined
under tlieir proper headings.

Suborder A. HOLOCHOANITES Hyatt.

Funnels of siphuncular segments reaching from the septum of origination to the plane
of the next septum apicad or heyond this, or in some geyiera even to the plane of the second
septum.

I. DiPHRAGMiDA Hyatt.

This groiip contains biit one family, Diphragmidae, having the same characters as
the following uniqiie genus : —

Diphragmoceras Hyatt. Orthoceracones and cyrtoceracones having simple septa
and sutures as in Endoceratida, but siphnncle divided by tabnlae alternating with the
septa of the camerated shell. Chambers of siphuncle empty, as are also the camerae.
Quebec group.

II. Endoceratida Hyatt,

Orthoceracones, cyrtoceracones, gyroceracones and nautilicones having siphuncles of
variable diameter, but as a rule large in proportion to the width of the shell. They may he
empty or filled ivith internal organic deposits, but are invariably tubulär, and the funnels
completely shut off the interior from the interiors of the camerae. The latter are without
organic deposits.

Family 1. Endoceratidae Hyatt.

Smooth or annulated orthoceracones. Siphuncle alivays more or less filled with
organic deposits.

A B C

Fio. 1104.
A, Vaghiocems duplex (Wahlenberg). Ordovician ; Kinneknlle,
Sweden. Mach reduced. B, V. commune (Wahlb.), Ordovician ;
Oranienbaum, Russia. The anterior endocone of the siphuncle is
filled up with niatrix so as to form a dart (" Spiess "). 1/2- ^', !>>«-
gramniatic longitiulinal section of the last, showing siphonal
funnels. D, Detached caraera of Vcußnoceras with long siphonal
funnel. (Figs. C and D after Dewitz.)

Fig. 1105.

Endoceras proteiforme Hall. Ordovi-
cian ; New York. Longitudinal section
showing funnels and endocones.

Vaginoceras Hyatt (Fig. 1104). Ordovician. Cameroceras Conrad {Sannionites
Fischer von Waldheim ; Suecoceras Holm). Ordovician and Silurian.

Endoceras Hall {Golpoceras Hall; Diploceras Conrad) (Fig. 1105). Smooth or

596 MOLLUSCA phylum vi

annulated orthoceracones. Funnels reach from septum of origination to tlie next
apicad of this, but no farther. Septa pass entirely arountl the sipliuncle. Organic
deposits in tlie form of endocones, and taper off at tha centre into a spire that is
ßometimes tubulär and hollow, or again flattened and elliptical. This is tbe endo-
siphuncle. Ordovician and Silurian.

Narthecoceras Hyatt. Long, cylindrical, staff-like ortlioceracones. Siphuncle
large and filled witli organic deposits having a radiating fibrous structure like the
guard of a Belemnite. Endocones and an endosiphuncle developed. Septa continuous
around the siphuncle. Ordovician.

Nanno Clarke. Similar to the preceding, but endosiphuncle present only at the
apieal end. Siphuncle close to the shell, so that sutures appear to bend apically into
a lobe passing around the siphuncle. Trenton Limestone.

Family 2. Piloceratidae Hyatt.

Shorter and stouter orthoceracones and cyrtoceracones ivith relatively larger siphuncles
than in Endoceratidae, and more variable in their internal deposits. Septa are more
concave and sutures more sinuous. Gamerae empty and funnels similar.

Piloceras Salter. Breviconic cyrtoceracones with very large siphuncle and well-
defined endocones. Ordovician.

Family 3. Oyrtendoceratidae Hyatt.

Gyroceracones and nautilicones having large siphuncles filled with organic deposits or
empty, hut with endocones ohscure or ahsent, and no endosiphuncles.

Gyrtendoceras Remele. Gyroceracones with siphuncle near the dorsum and filled
with calcareous deposits. Ordovician.

Suborder B. MIXOCHOANITES Hyatt.

Orthoceracones and cyrtoceracones having expanded living Chambers with contracted
apertures in the gerontic stage of specialised genera. The oldest septa are beut sharply
orad, forming a series of dorsal saddles, and the siphuncle hecomes highly modified.
Primitive genera have the septa deeply concave or approximately sub-conical, the siphuncle
small and empty, and the septa sometimes more or less imperfect on the ventral side in the
gerontic stage. Specialised forms have siphuncles with short, straight funnels in the
young, and in the ephebic stage collars are built around the oral openings, thus becoming
parallel to some forms of Goniatitidae that have similar composite funnels.

Family L Ascoceratidae Barrande.

Cyrtoceracones, smooth or annulated. Siphuncle with long funnels only in the young
and later stages of primitive genera, but collars are added in later stages of specialised
forms, and segments become nummuloidal in the gerontic stage. Septa often more or less
imperfect around the siphuncle and on the ventral side.

Ghoanoceras Lindstr. Sections dej^ressed elliptical. Gerontic stages have no
saddles, and living Chamber uncontracted. Ordovician and Silurian.

Aphragmites Barr. Only gerontic living Chambers known ; these are similar to
those of Ascoceras, but have no internal sigmqidal dorsal saddles. Silurian.

Ascoceras Barr. (Figs. 11 06, 1 107). Gerontic living Chambers internally contracted
by the formation of large sigmoidal saddles, and septa more or less incomplete

CLASS V

CEPHALOPODA

597

ventrally. Siphuiicle with fuimels only in the young, the collars in ephebic stages
becoming nummuloidal and often inconijjlete in old age. Aperture open. Silurian.
Glossoceras Barr. Known only by gerontic living Chambers,
whicli are like those of Ascoceras, except that the aperture has dorsal
and lateral crests. Silurian.

Volborthella Schmidt. * Minute orthoceracones with conical
septa, small siphuncle, perfectly piain upon the surface of the septa.
Living Chamber flaring and uncontracted. Lower Cambrian ;
Finland, Esthonia. St. John Group ; Nova Scotia.

Family 2. Mesoceratidae Hyatt.

Depressed elliptical cyrtoceracones, known only hy their gerontic
living chamherSy and aßnities therefore uncertain. They are globular
at this stage, and have highly contracted^ transversely elongated, and
approximately dumh-hell shaped apertures.

Wv

Fio. 1106.

Äscoceras mamchrium
Lindström. Silurian ;
Gotland. 1/2. (Re-
stored after Lindström.)

Fig. 1107.

Äscoceras bohcmicuvi Barr. iSilurian (Etage E) ; Kozorz, Bohemia. A,
Specimeu with shell partially preserved. B, Mould of living Chamber detached
from preceding portion. C, Longitudinal section. 7t', Living Chamber; c 1-4,
Camerae ; l 1-4, Saddles contracting the living Chamber, i/j (after Barrande).

Mesoceras Barr. Aperture with very sliallow hyponomic sinus. No internal
gerontic sigmoidal septa. Silurian.

Billingsites Hyatt. Aperture without hyponomic sinus. Gerontic living Chamber
partly fiUed by dorsal sigmoidal saddles as in Äscoceras, but septa complete on the
ventral side. Silurian.

Suborder C. SCHISTOCHOANITES Hyatt.

Funnels usually more or less imperfecta present on the internal side, and ahscnt or
split on the outer side.

The typical form of the suborder is Conoceras Bronn.

Gyrtocerina Billiugs. Breviconic cyrtoceracones. Siphuncle large, on the concave
side and empty, but having internal ridges alternating with septa of the camerae.
These ridges appear to indicate affinity with Conoceras. Ordovician.

Conoceras Bronn {Bathmoceras Barr.) (Fig. 1108). Breviconic orthoceracones,

598

MOLLUSCA

PHYLUM VI

known only in their later stages of development. Sipliuncle of moderate size, sub-
ventran. Funnels reaching lialf-way across each camera, steeply inclined orad, and
split on tlie outer side. Closure of the walls effected by a
plate extending from the apical opening of each funnel through
the funnel itself orad to the apical opening of the next
beyond, and projecting into the interior as a flattened fold,
which is incomplete or open along the central axis. These
internal coUars or flat semiconical rings have been described
as complete cones (Dwight). Ordovician.

Suborder D. ORTHOCHOANITES Hyatt.

' Gerontic stages have uncontracted volutions and open aper-

tures, except in a few uncoiled phylogerontic genera. Siphun-
Fio, 1108. cular Segments may he slightly nummuloidal, fusiform or tubulär,

Conoceras pracpost^rum hut are never marJcedly nummuloidal, nor are the funnels hent
D)rVosä^^Bohemia^fafter ^harply outwards as in Gyrtochoanites. Deposits formed only in
Barrande). the siphuncles of Orthoceratidae and Kionoceras, and in them

they are irregulär and no endosiphuncles occur ; other genera
have empty siphuncles. Funnels, as a rule, hoth longer and straighter than in Gyrto-
choanites, and in Aturia almost equal to those of Holochoanites.

This group includes the greater number of Nautiloid forms, passing from the
smoothest to the most highly ornamented of Paleozoic shells, continuing in the Trias
as nautilicones of complex ornamentation, and terminating with smooth shells that
ränge from the Jura to the present time. The sutures become more sinuous and com-
plex in one of the subdivisions than in all other Nautiloids. The increase in number
of lobes and saddles begins in the Trias with Glymenonautilus, and ends with Aturia
in the Tertiary.

I. Orthoceratida Hyatt.

Orthoceracones and cyrtoceracones with smooth or ornamented shells, and not as a
rule contracted in gerontic stage ; apertures open throughout life. Although often short,
none are hrevicones, strictly speahing. Section circular or elliptical, very rarely oval.
Siphuncle with slightly nummuloidal, fusiform or tubulär segments, and generally near
the centre.

Family 1. Orthoceratidae M'Coy.

Section circular or compressed, living chamher uncontracted or only slightly so,
and aperture always open. Surface smooth or with only transverse bands, rarely
longitudinal Striae, never longitudinal ridges. Siphuncle small (except in Baltoceras),
Segments fusiform or cylindrical, never nummuloidal. Deposits when present irregulär,
and gathered about the funnels as in the Gyrtochoanites ; no definite endosiphuncles ever
formed.

Baltoceras Holm. Siphuncle large, but with short, straight funnels, and sheatlis
as in Orthoceras. Ordovician.

Orthoceras Breyn (Figs. 1109, 1110). Long tapering orthoceracones and cyrto-
ceracones, smooth, or with only transverse Striae and growth bands. Siphuncle
generally larger than in Geisonoceras, centren or slightly dorsad of centre. Deposits
when present gathered about the funnels as in the Annulosiphonata. Silurian to Trias.

Geisonoceras Hyatt (Fig. 1111). Similar to the last, but sides spreading more
rapidly, and siphuncle empty, centren or slightly ventrad of centre. Ordovician to
Carboniferous.

CLAss V CEPHALOPOJ)A 599

Protobactrites Hyatt. Long i)encil-shaped orthoceracones and cyrtoceracones,

Fio. 1100.

Orthocerasinter medium Marklin. Siluriaii ;
Gottland. Longitudinal section showing
siplmncle, septa and pseudosepta ; camerae
lilled up witli calcite.

Fig. 1110.

Orihoceras michelini
Barr. Silurian ; Kozorz,
Boheniia. Longitudinal
section showing sliort
sii)honal funnels.

circiilar, or compressed elliptical in section, ornamented with
transverse and sometiines longitudinal Striae. Siphuncle
tubulär, centren or near the centre. Truncation occurs in soiiie
species, and others are more or less transitional to Bactrites
among the Ammonoids. Type P. {Oriho-
ceras) styloideum (Barr.). Silurian to Car-
boniferous.

Family 2. Oycloceratidae Hyatt.

Fio, 1111.

Geisonoccras timidum
(Barr.). Silurian ; Loch-
kow, Bohemia.

Orthoceracones and cyrtoceracones having annuli with transverse
Striae or bands of growth at all stages ; longitudinal ridges^ when
jjresent, more or less discontinuous. The earliest forms often have
large siphuncles, and are apparently more directly connected with
primitive Endoceratida than with the Orthoceratidae.

Protocycloceras Hyatt. Annulated orthoceracones and cyrto-
ceracones without longitudinal ridges. Siphuncle large. Type
P. {Orihoceras) lamarcki (Bill.). Ordovician.

Cycloceras M'Coy {Dictyoceras, Heloceras Eichw.). Annulated
orthoceracones and cyrtoceracones with discontinuous longitudinal
ridges. Siphuncle generally tubulär or with fusiform segments ;
deposits when present irregulär as in Orihoceras. Annuli often
become obsolete in paragerontic stages. Ordovician to Perniian.

Daiüsonoceras Hyatt (Fig. 1112). Siniilar to Cycloceras, but
having prominent frilled bands of growth between and on the
annulations, the frills sometimes forming more or less discon-
tinuous longitudinal ridges. Silurian and Devonian.

Gtenoceras Noetling. Cyrtoceracones like Dawsonoceras dulce
(Barrande), but with fine longitudinal ridges between the annuli,
and living chamber with three internal folds or processes — one
median dorsan, and a pair on the venter. SiiJhuncle dorsad of
centre. Ordovician.

Family 3. Kionoceratidae Hyatt.
Orthoceracones and cyrtoceracones with more or less well-marked continuous longi-

FiG. 1112.

Dawsonoceras annula-
tum (Sowb.). Silurian
(Etage E) ; Viscocilka,
Bohemia. Terminalpor-
tion showing Shell of
living Chamber and
sectioned camerae (after
Barrande).

600

MOLLUSCA

PHYLUM VI

tudinal ridges, and either with or ivithout annulations. Spinous ])rocesses or tuhercles
often appear at the intersections of the longitudinal and transverse hands of growth.
Siphuncle with faintly iiummuloidal, fusiform or tubulär
Segments.

Kionoceras Hyatt. Longitudinal ridges present as a rule
only in the earlier stages, after wliich inconspicuous annuli
appear, but with some few exceptions become obsolete before
the ephebic stage. Silurian to Carboniferous.

Spyroceras Hyatt. Very long, slender, annulated shells,
with more or less prominent longitudinal ridges in the ephebic
stage. Ordovician to Carboniferous.

Thoracoceras Eichw. {Melia Eichw.) (Fig. 1113). Like the
last, but with more or less spinous longitudinal ridges. Silu-
rian to Carboniferous.

IL Plectoceratida Hyatt.

Orthoceracones, gyroceracones, and very discoidal nantilicones

with comparatively slight impressed zone. Volutions of gerontic

stage often have a centrifugal tendency, becoming sometimes

straight and even bending slightly in the opposite or ventral direction.

p ^. Shells annulated or costated, and often ivith longitudinal Striae or

Thoracoceras corbulatum -^^^ ridges, especially in the young, but these generally disappear

(Barr.). Silurian (Etage before the ephebic stage. Siphuncular Segments slightly num-

E); Dvoretz.Bohemia (after i -j i x -x ± i i

Barrande). muloidal, fusiform or tubulär.

Family 4. Tarphyceratidae Hyatt.

Orthoceracones, cyrtoceracones, gyroceracones and nautilicones, compressed oval in
section, venter narrower than the dorsum. Shell smooth or Sometimes with primitive fold-
like costae. Siphuncle empty, tubulär and ventrad of centre.

Aphetoceras, Deltoceras, Barrandeoceras, Tarphyceras Hyatt ; Planctoceras, Eury-
stomites Schröder ; Falcilituites Eemele. Ordovician. (For descriptions see Hyatt's
Phylogeny, 1894.) Eurystomites and Tarphyceras are whoUy nautilicones, the remain-
ing genera are either cyrtoceracones or gyroceracones.

Family 5. Trocholitidae Hyatt

Nautilicones resembling those of the preceding family, and not easily distinguished
from them in the young. As a rule they have excessively broad volutions with reniform
section and an impressed zone at a very early age ; the siphuncle is then ventrad of the
centre, but in the ephebic stage it is tubulär and dorsad of centre.

Schroederoceras, Litoceras, Trocholitoceras Hyatt; Trocholites Conrad {Palaeo-
nautilus, Palaeoclymenia Remele). Ordovician. Discoceras Barrande. Ordovician
and Silurian.

Family 6. Plectoceratidae Hyatt.

Gyroceracones, nautilicones and torticones having annular costae from the neanic
stage until late in life, and in some genera, more or less prominent longitudinal ridges,
which usually disappear in^ the ephebic stage. Siphuncle ventrad of centre.

CEPHALOPODA

601

Pledoceras Hyatt. Ordovician and Silurian. Sphyradoceras Hyatt {Peismoceras,

Systrophoceras Hyatt) (Fig. _

1114). Silurian and

Devonian. The first is gyro-
ceraconic, with some discoidal
nautilicones, and the second is
almost exclusively torticonic
of tlie trochoceran type.

Family 7. Ophidio-
oeratidae Hyatt.

Discoidal nautilicones^
costated from the neanic stage
onward. Volutions of the
young small and numerous.
Section during the ephebic stage
generally compressed, venter
narrower than the dorsum.
Siphuncle tubulär, small.

Fi«. 1114.

Sphymdoceras optaUim (Barrande). Silurian
(Etage E) ; Lochkow, Bohemia (after Barrande),

the young.

Ophidioceras Barr. (Fig.
1115). Nautilicones with
straight lateral costae and
raised bands on the venter,
and longitudinal ridges in
Siphuncle dorsad or ventrad of centre during ephebic
stage, biit ventrad during the nepionic.
Gerontic apertures with prominent dorsal
and lateral crests, and very deep hypo-
nomic sinus. Silurian.

Homaloceras Whiteaves. Cyrtocera-
cönes with section similar to that of Ophi-
dioceras, venter narrow and channelled,
bordered by crenulated ridges ; the dorsum
gibbous and rounded. Siphuncle near
the venter. Devonian.

Family 8. Lituitidae Noetling.

Ophidioceras simpUx Barr,
Silurian (Etage B); Lochkow,
Bohemia. i/i (after Barrande).

Excepting the supposed ancestral,
primitive genus, Gyclolituites, this is a
series of phylogerontic uncoiled forms with
an extreme modification in the almost
completely uncoiled Rhynchorthoceras.
Apertures quite distinct from those of the preceding family ; hyponomic
sinus shallower, there are narroio ventro-lateral crests, and small lateral
sinuses and crests, some forms having altogether as many as five sinuses
and five crests. Biphuncle tubulär and usually largc.

Fio. 1116.

Lituites lituus
Montf. Ordovician
drift ; East Prussia.
1/2 (after Noetling).
Gyclolituites Remele ; Lituites Breyn {Fig. 1116); Angelinoceras,

Holmiceras Hyatt. Ordovician. Ancistroceras Boll, and Rhynchorthoceras Remele.

Ordovician and Silurian. (For re-descriptions see Hyatt's Phylogeny, 1894.)

602

MOLLUSCA

PHYLÜM VI

II I. Pleuronautilida Hyatt.

Gomparatively smooth naufAlicones, the primitive genera discoidal hut leading up to
some highly involute shells in the Trias. The later Mesozoic and Tertiary shells nearly
all deeply involute. Some of the Triassic Glydonautilidae have more sinuous sutures
and a greater number of lobes and saddles than any other Nautiloids, and this
complexity persists, although to a lesser degree, among the Jurassic, Gretaceous and
Tertiary forms. Siphuncle tubulär and small, with mostly short funnels except in
Äturia, where they are very long.

Family 9. Grypoceratidae Hyatt.

Primitive forms have discoidal volutions ivith very simple sutures^ but are succeeded
hy involute shells having more complete sutures. The latter have promAnent ventral
saddles sometimes divided by a lobe, and, large lateral and dorsal lobes. All genera
save one known to have annular lobes. Shells less highly ornamented than in preceding
family, and sutures simpler than in the next following.

Syringoceras Hyatt. Discoidal with primitive, approximately tubulär, or sliglitly
compressed volutions. Surface marked by lougitudinal ridges, sometimes intersecting
the transverse lines so as to produce a cancellated surface. Sutures with faint ventral
saddles, slight lateral and dorsal, and minute annular lobes. Siphuncle very small
and near the venter. Trias.

Grypoceras Hyatt. Volutions more or less deeply involved, but umbilicus open,
the venter narrow and often channelled. Sutures with narrow, sometimes deep ventral
lobe, broad, sweeping lateral lobes, and deep dorsal with annular lobes. Siphuncle
dorsad of centre. Trias.

Family 10. Glydonautilidae Hyatt.

Shells have folds in some species, and all are deeply involute except the primitive genus

Glymenonautilus. Lateral lobes of sutures more
or less deep and often sub-angular, suggestive of
the Glymenidae among Ammonoids. Some highly
specialised and involute species have the umbilical
lobes exposed on the sides, and an additional
pair of laterals developed near the venter, thus
making three pairs of lobes on each side. The
compressed volutions, narrow venter, and aspect
of the young and primitive forms seem to in-
dicate dose affinity with the Grypoceratidae, but
only a few species of late Mesozoic time are
known to have annular lobes.

Glymenonautilus Hyatt. Smooth, discoidal
Shells with more or less compressed volutions,
and narrow convex venter. Sutures with pro-
minent ventral saddles, one pair of deep lateral
lobes, and large marginal saddles. Siphuncle
supposed to be near the venter. Type G.
{Nautilus) ehrlichi (Mojs.). Trias.
Fin. 1117. Glydonautilus Mojs. Deeply involved

Herc<^lossaf^n«n^a(0^^)^j„^rj.ra ; „autilicones with compressed volutions, narrow

concave venter, and umbilicus small or closed.
Sutures with prominent ventral saddles undivided by ventral lobes in adults hells. Trias

CLASS V CEPHALOPODA 603

Hercofjlossa Conrad {Enclimatoceras Hyatt) (Fig. 111'7). Deeply involute, with
sutures like those in Glyphioceratidae, Ijut the ventral saddle not divided by even the
shallow lobe nsually found in tliat faniily. Annular lobes present
only in some species. Siplumcle small, centren or dorsad of centre.
Trias to Tertiary.

Pseudonautüus Meek. Similar to Hercoglossa, but with lobes
on the venter, and two saddles on either side. Large annular
lobes present. Jura.

Äturia, Bronn (Fig. 1118). Similar to Hercoglossa, but with
large siphuncle close to the dorsuni from an early stage onward,
and funnels very long and larger than in any genus of Mesozoic
or Tertiary Nautiloids. Eocene and Miocene.

IV. Ryticeratida Hyatt.
Cyrtoceracones, gyroceracones and naütüicones having shells ^^^'" ■'^^.^"

covered with more or less projecting hands of groivth which often Mioce^ef Bordeaux'.

hecome sinuous or develop into spout-like spinöse, or nodose pronii- ^^^^'^ broken open to

r .1 ' T 1 1 n .1 , , 7 /. , Show siphonal funnels.

nences. In the more speciahsed shells these are apt to he confined

to the venter. The frills in the hands often form coarse longitudinal ridges. Siphuncle
tubulär or slightly nummuloidal, and commonly ventrad of centre.

Family 11. Halloceratidae Hyatt.

Orthoceracones and cyrfoceracones having depressed elliptical or suh-trigonal sections,
venter hroader than the dorsum, Shell with closely set and frilled projecting hands of
growth, having large ring-like hands at intervals that sometimes expand so as to form
wide collars. The highly specialised nautilicones may have a row of large nodes on
either side springing from the hases of large spout-like spines. Siphuncle tubulär ^ small,
and near the venter.

Zitteloceras Hyatt. Cyrtoceracones of depressed elliptical section, the venter
narrower and more gibbous than the dorsum. The layers finely frilled and closely
set in the intervals between more prominent annular bands. Ordovician to Devonian.

Halloceras Hyatt. Gyroceracones of sub-trigonal section, the venter broad and
dorsum sub-angular, with one row of large nodes at each of the ventro-lateral angles.
Devonian.

Family 12. Ryticeratidae Hyatt.

Cyrtoceracones and gyroceracones resemhling Halloceratidae, but much larger, with
coarser crenulated bands, and often with rows of spout-like spinous processes which some-
times form coarse longitudinal ridges. Siphuncle more or less nummuloidal, and larger
than in the Halloceratidae.

Ryticeras Hyatt {Rutoceras Hyatt), Cophinoceras, Strophiceras Hyatt. Devonian.

V. Khadinoceratida Hyatt.

Cyrtoceracones, gyroceracones and nautilicones having smooth or spinous longitudinal
ridges in the young, which hecome large and ßuted in some genera, hut disappear in
others. Ridges more or less sporadically comhined with fold-like annulations, thus
suggesting direct descent from the Kionoceratidae.

Family 13. Rhadinoceratidae Hyatt.

Primitive discoidal gyroceracones and nautilicones ivith stout volutions, circular or
depressed elliptical in section, but hecoming reniform in later stages of nautilicones.

604

MOLLUSCA

PHYLUM VI

Shells with longitudinal ridcjes and sometimes annular folds in the young, hut often
smooth in the ephehic stage. Sutures ivith ventral, lateral ^and dorsal lohes, or almost
straight Siphuncle nummuloidal and often dorsad of centre. Annular lohes knoimi to
he present in specialised forms.

Rhadinoceras, Nephriticeras Hyatt. Devonian.

Family 14. Trigonoceratidae Hyatt.

Gyroceracones and nautilicones having at some stage or throughout life trigonal
volutions, a more or less concave venter, and generally fluted shelL Sutures with ventral
saddles in the young, hecoming divided hy shallow lohes in later stages, and in some genera
the dorsal lohes of the young hecome divided suhsequently hy dorsal saddles. Gerontic
living chamher occasionally free near the aperture. Annular lohes ohserved in only one
species (Apheleceras disciforme). Young have longitudinal ridges roughened hy transverse
hands as in Thoracoceras. Siphuncle small, ventrad of centre.

Trigonoceras M'Coy ; Goelonautilus Foord {Trematodiscus Meek ; Trematoceras

Hyatt) ; Suhclymenia d'Orb. ; Strohoceras,
Apheleceras, Diorugoceras, Ephippioceras
Hyatt. Carboniferous. All nautilicones
but the first, which is gyroceraconic.

Family 15. Triboloceratidae Hyatt.

Gyroceracones and nautilicones similar
to Trigonoceratidae, and with concave
venter at an early stage or until late in
life. The venter afterwards hecomes more
or less elevated, and in most species convex.
Sutures also similar, hut annular lohes
are present in all the nautilicones save
Coloceras.

Fig. 1119.

Vestinautütis konincki (d'Orb. ). Lower Carboniferous ;
Tournay, Belgium. Oral and lateral aspects of young
individual, with umbilical Perforation.

Triholoceras Hyatt; Vestinautilus Ryckh. (Fig. 1119); Planetoceras, Stearoceras,
Goloceras Hyatt. Carboniferous.

Family 16. Rhineceratidae Hyatt.

Gyroceracones and nautilicones like Thoracoceras in nepionic stage, hut suhsequently
hecoming Uangular in section, and generally developing solid, more or less tetragonal,
volutions. Longitudinal ridges and flutes also developed, hut are more uniform in size
than in the preceding family, and venter is always convex. Annular lohes present in
all nautilicones so far as Jcnown.

Ehineceras, Lispoceras, Thrincoceras, Phloioceras, Discitoceras {Discites M'Coy),
Leuroceras, Phacoceras Hyatt. Carboniferous.

. VI. Hercoceratida Hyatt.

^ Primitive shells have projecting hands of groivth and processes similar to those of
primitive Ryticeratida, hut less numerous, heing present in only one row, and evolving
more rapidly into nodose or symmetrical, spout-like, spinous processes: More specialised
forms are tuherculated as in Ryticeratida, hut there are never more than three rows of
nodes on either side, and these are regiUarly distrihuted — one on the umhilical Shoulder,
another on the ventro -lateral angle, and the third dose to the median ventral line.

CLASS V

CEPHALOPODA

60/

Ännular lohes ahsent except in a feto Triassic forms. Siphuncle generally more or less
nummuloidal.

Family 17. Hercoceratidae Hyatt.

Gyrtoceracones, gyroceracones, nautilicones and torticones having depressed elliptical
suh-quadrate or trapezoidal sections. Aperture has two deep sinuses with projecting edges

Fig. 1120.

Hercoceras mirum Barr. Devonian (Etage G) ; Hlubocep, Bohemla
(after ßarraiide).

Ptenoceras (Gyr.) cdatum
(Barr.). Silurian (F) ;
Konieprus, Bohemia. i/i
(after Barrande).

at the ventro-lateral angles, and these are usually persistent, forming two lines of more or
less spout-like processes. Sutures with ventral, lateral and dorsal lohes. Siphuncle
ventrad of centre.

Hercoceras Barr. (Fig. 1120), Trochoceras Barr.; Ptyssoceras, Ptenoceras (Fig. 1121),
Anomaloceras Hyatt. Devonian.

Family 18. Tainoceratidae Hyatt.

Discoidal nautilicones with more or less massive volutions which at some stage or
throughout life are trapezoidal in section, tuherculated, and without well-deßned lateral
and umhilical zones. Sutures have ventral, lateral and dorsal, hut no annular lohes.
Spinous processes are complete, never spout-like. Siphuncle bmall, tubulär.

Temnocheilus M'Coy {Endolohus Meek and Wortli ; Gryptoceras d'Orb.). Section
trapezoidal throughout life, and one row of persistent spines and nodes on either
side at the ventro-lateral angles. Devonian to Carboniferous.

Foordiceras Hyatt. Permian. Metacoceras and Coelogasteroceras Hyatt. Carboni-
ferous. Diadiploceras Hyatt. Devonian. ' Tainoceras Hyatt. Carboniferous.

Family 19. Oentroceratidae Hyatt.

Gyroceracones and nautilicones with young similar to early stages of Temnocheilus
htfore the impressed zone is formed. Shell suhsequently hecoming tetragonal in section,
the venter is flattened or concave, and dorsum remaining convex until a late stage.
Nautilicones have a persistent convex centran area in the impressed zone. No annular
known. ' ,

606 MOLLUSCA phylum vi

Gentroceras Hyatt. Devonian to Carboniferous. Tetragonoceras Whiteaves.
Devonian.

Family 20. Pleuronautilidae Hyatt.

Mo.re or less discoidal nautilicones with stout volutions and large umhilical perfora-
tions ; the young, especially in primitive species, remaining cyrtoceracones until a late
stage. More specialised shells are costated and tuherculated on the sides. Sutures have
annular lobes except in Pselioceras. Siphuncle ventrad of centre in the young, hut
hecoming dorsad in later stages.

Pselioceras Hyatt. Permian. Pleuronautilus Mojs. ; Encoiloceras, Enoploceras,
Änoploceras Hyatt. Trias.

VII. KONINCKIOCERATIDA Hyatt.

Nautilicones with hiangular sections at an early stage of growth, developing later
into modißed trapezoidal outlines as in many of the Hercoceratida, hut shells are smooth,
and the trapezoidal form as a rule evolves during the phylogeny into quadrangular, and
finally into involute coils with compressed sections, or may become simply more or less
trigonal through elevation of the venter. Annular lohes present in most genera.
Aperture constantly open, and in some forms remarJcahle lateral projections are developed
during the gerontic

Family 21. Koninckioceratidae Hyatt.

Shells of primitive forms similar to Temnocheilus, hut leading into those with
tetragonal sections, and finally into highly compressed volutions. All are smooth and
have marked umhilical saddles. Volutions vnth hroad umhilical zones which hecome
lateral in the more involute species. Siphuncle ventrad of centre.

KonincMoceras, Domatoceras Hyatt. Carboniferous. Potoceras Hyatt. Devonian (?).
Stenopoceras, Peripetoceras Hyatt. Permian.

Family 22. Solenocheilidae Hyatt.

Compressed elliptical in section during early stages, hut full-grown of primitive forms
and young of specialised derivatives have a more or less trigonal section in neanic stage.
Later this stock evolves shells with volutions having depressed elliptical or hroadly hemi-
spherical outlines. Sutures generally have large ventral saddles, and saddles on the
umhilical Shoulders. Umhilical zone very hroad, the increase hy growth of the dorsum
heing remarkahly rapid. Shells smooth, hut the aperture in the gerontic stage may develop
peculiar lateral projections, especially at the umhilical Shoulders, which are usually very
prominent. Siphuncle suh-ventran.

Aipoceras, Oncodoceras Hyatt ; Asymptoceras Ryckholt ; Solenocheilus Meek.
Carboniferous. Pteronautilus Meek. Permian.

Acanthonautilus Foord. Nautilicones with sub-hemispherical volutions, the dorsum
flattened or concave. Aperture developing laterally into two projecting spines at the
umhilical Shoulders. Carboniferous.

VIII. DiGONiocE RATIDA Hyatt.

Primitive forms constantly retain depressed volutions having a more or less hiangular
or suh-trigonal section ; specialised shells repeat these stages in the young, hut suhsequently
hecome more involute, and the sections change to reniform, suh-quadrangular or suh-
elliptical. Shells smooth except in the single genus Gymatoceras. Aperture simple and
open at all stages ; gerontic living chamher only slightly contracted.

CLASS V

CEPHALOPODA

607

Family 23. Estonioceratidae Hyatt.

Gyroceracones and discoidal nautüicones having sUghtly depressed, hroad, rapidly
increasing hiangular sections in the young, tut hecoming depressed oval or depressed
suh-trigonal in later stages. Siphuncle variable in position.

Estonioceras Noetl. Ordovician. Edaphoceras, Remeleoceras, Lophoceras Hyatt ;
Diodoceras Hyatt. Type D. (Endolohus) avonense (Dawson). Carbon iferous. Digonio-
ceras Hyatt. Jura.

Family 24. Nautilidae Owen.

Nautilicones wiih more or less involved volutions, the siphuncle slightly nummuloidal
and variable in position, but never near either the dorsiim or venter except in the young,
when it is frequently either near the dorsum or is centren. Biangular stage much
abbreviated or absent, the trigonal stage present in
most Shells for a more or less prolonged period, but
developing invariably by spreading of the venter into

FifJ. 1122.

Nautilus pompilius Linn.
Recent. Portion ofconch showing
linear cicatrix at apical end (after
Hyatt).

Fio. 1123.

Apical Chamber and first
volution of N. pompilius,
sectioned longitudinally.
s, Siphuncle; c, Blind
origin of caecum; x, Euipty
Space or uuibilical Perfora-
tion (after Branco).

Fi«. 1124.

Nautilus intermedius Sowb. Middle
Lias : Hinterweiler, Würtemberg.

tetragonal, reniform or hemispherical outlines. Never decidedly dis-
coidal, although the umbilicus is often open. More specialised forms
have a minute umbilicus, and in some cases it is completely hidden
during the ephebic stage, although invariably open in the young.
Zone of impression present on the dorsum before the lohorls are in
contact. Annular lobes often developed at an early stage, but liable
to disappear in the adult ; absent in some Tertiary species.

Genoceras Hyatt. Jura. Gymatoceras Hyatt. Cretaceous.
Eutrephoceras Hyatt. Cretaceous and Tertiary.

Nautilus Linn. (Figs. 1122-1125). The young resembling
adults of Digonioceras until a late stage, and adults of primitive
species (like N. umbilicatus) similar to Genoceras. Sutures slightly
inflected, with faint ventral lobes ; annular lobes present. Volu-
tions sub-globose, and umbilical Perforation comparatively large.
Siphuncle centren in the apical camera, but later becoming ventrad
of centre, Tertiary (?) to Recent.

Fio. 1125.

NmUilns gcinitzi
Pictet. Tithonian ;
Stramberg, Moravia.

608 MOLLUSCA phylüm vi

Suborder E. CYRTOCHOANITES Hyatt.

Shells varying from orthoceracones to nautilicones, none of them highly ornamented,
although some are annulated or costated, and in rare cases slightly nodose. Sutures as a
rule simpler than in the Orthochoanites. Siphuncle varies exceedingly, passing from tubulär
in the young, and even in the full-grown of primitive forms, to highly nummuloidal in the
adults of specialised genera, or again in some groups retaining constantly its primitive
character. The funnels, however, are as a rule hent outward or crumpled, and generally
short.

I. Annulosiphonata Hyatt.

Mostly orthoceracones and cyrtoceracones, with a few gyroceracones and very rarely
nautiliconeSj the last-named heing invariably discoidal. Apertures constantly open.
Siphuncle may he empty, hut organic deposits when present always gathered about or
encrusting the funnels as hollow or solid internal rings. Deposits sometimes sujfflcient to
form more or less annulated endosiphuncles, the rings heing opposite the camerae, alter-
nating with the septa, and extending outwardly.

Family 1. Loxoceratidae Hyatt.

Smooth orthoceracones and cyrtoceracones similar to the Orthoceratidae^ hut siphuncle
distinctly nummuloidal, and funnels very short and crumpled. Deposits not uncommon,
hut irregulär, and only irregulär endosiphuncles occasionally formed.

Loxoceras M'Coy {Sactoceras Hyatt). Mostly orthoceracones, circiilar or elliptical
in section. Siphuncle supposed to be tubulär in the young, but highly nummuloidal
in later stages, centren or near the centre. Septa invariably single, and camerae
empty. Ordovician to Carboniferous.

Campyloceras M'Coy {Aploceras d'Orb.). Breviconic cyrtoceracones or orthocera-
cones with smooth or finely ridged shells, circular or depressed elliptical in section.
Siphuncle centren or ventrad of centre. Carboniferous.

Family 2. Uranoceratidae Hyatt.

Cyrtoceracones, gyroceracones and nautilicones, with stout volutions. Siphuncle in
primitive forms highly nummuloidal, hut invariably empty ; in nautilicones it has less
nummuloidal segments, and is uniformly ventrad of centre, hut not near the venter.
Sutures with ventral saddles, lateral lohes, and also dorsal saddles in primitive forms as
well as the young of all shells. Ventral and dorsal lobes arise suhsequently in the
ontogeny of nautilicones.

Uranoceras Hyatt. Stout, more or less breviconic cyrtoceracones, compressed
elliptical or sub-quadrangular in section. Sutures with broad ventral saddles, lateral
and dorsal lobes. Siphuncle large, nummuloidal, centren or ventrad of centre.
Devonian and Carboniferous.

Gigantoceras Hyatt. Gyroceracones similar to the preceding, but having longer
living Chambers and more compressed volutions. Includes the largest known Nauti-
loid Shells. Type G. (Gyroceras) inelegans (Meek). Silurian.

Family 3. Actinoceratidae Saemann.

Orthoceracones and cyrtoceracones with siphuncle more or less ßlled hy rings of
organic deposits, and having an endosiphuncle in the central axis. Camerae may he
empty or filled to various degrees with organic deposits, even to the extent of solidifying
the entire shell previous to the gerontic stage. Shells smooth or annulated, but not longi-
tudinally ridged, at least in the latter stages.

CLASS V

CEPHALOPODA

609

Actinoceras Bronn. (Figs. 1126-1127). Ortlioceracones and cyrtoceracones of usually
depressed elliptical section, with large, excessively nummuloidal siphuncle. Funnels
very short and crumpled, slieath almost globular. In-
ternal deposits contracting tbe central axis into an
annulated endosi])lnincle with tubuli radiating from the
annuli, Septa often double, with an interspace between

the two layei's near the

siphuncle, but solid near

the shell. Ordovician

to Carboniferous.

Subgenera : Ormo-

ceras Stokes (Fig. 1128).

Fig. 1126.

Actinoceras cochleatum (Schloth.)-
Silurian ; Gotland. Abraded frag-
inent showing Single septa and tliick
annulated endosiphuncle. 1/2.

Fig. 1127.

Actinoceras vertehratum Hall.
Silurian ; Lockport, New York.
Longitudinal section showing
organic dei)osits of siphuncle
(after Barrande).

Fin. 1128.

Actinoceras (Onnoceras) hayfieldi
Stokes. Ordovician ; Longitudinal
section showing organic deposits
of siphuncle partly dissolved away
(after Stokes).

Ordovician to Carboniferous. Paractinoceras Hyatt (Fig. 1129). Shells longer and
more slender tlian in the preceding, large siphuncular segments confined to early
stages, and very long living Chamber. Type P. (Sactoceras)
canadense (Whiteaves). Silurian.

Gyrtactinoceras Hyatt. Type C. (Cyrtoceras) rebelle (Barr.).
Deiroceras Hyatt; Huronia Stokes (Fig. 1130); Discosorus
and Gonioceras Hall. Silurian.

(?) Tretoceras Salter. Orthocera-
cones having a centren nummuloidal
siphuncle, similar to that of Acti-
noceras but smaller, and with a
superficial tulnilar siphuncle (so-
called), having very long but not
Holocho.anoidal funnels. Sheath not
yet shown to be present. It is pos-
sible that the structure referred to
is a peripheral pseudo - siphuncle
formed by abnormal condition of the
septa. Silurian.

Fi(i. 1J2;

Actinoceras (Faractinoceras)
docens (Barr.) Silurian (B);
Dvoretz, Bohemia. Vertical
section showing senile stage
without organic deposits,
prcceded by adult stage with
siphuncular rosettes (after
Barrande).

Fig. 1130.

Huronia vertebralis
Stokes. Ordovician; Isle
Drummond, Lake Hui"on.
Siphuncle.

II. AcTiNOSiPHONATA Hyatt.

OrthoceraconeSy cyrtoceracones^

gyroceraconeSj and a few discoidal

nautilicones. Shells frequently hreviconic, in which case the gerontic living Chambers and

apertures are more highly contractecl than in all other Nautiloids. Siphuncle sometimes

empty ; organic deposits, ivhen present

VOL. I

the form of laminae radiating from the sheath

2 R

610

MOLLUSCA

PHYLUM VI

0/ each Segment towards the interior. These internal calcareous septa are united only in
their peripheral parts, not meeting at the central axis so far as known, and also liahle
to he more or less interrupted in the transverse plane of each funnel. The interior is
consequently an actiniform endosiphuncle with rays extending outivardly hetween the
laminae of the deposits.

Family 4, Jovellanidae Hyatt.

Orthoceracones and cyrtoceracones ivith slightly compressed oval, or depressed and
more or less sub-trigonal sections. Shells smooth or partially annulated. Siphuncle large,
with well-developed actiniform lamellae, and distinct endosiphuncles. Apertur e open and
living Chamber uncontracted in the gerontic stage.

Includes Jovellania Bayle ; and Tripleuroceras Hyatt. Silurian and Devonian.
Mixosiphonoceras Hyatt. Type M. (Oyrtoceras) desolatum (Barr.). Silurian and
Devonian. Projovellania Hyatt. Type P. {Gyrtoceras) athleta (Barr.). Silurian.

Family 5. Rizoceratidae Hyatt.

Orthoceracones and cyrtoceracones expanding regularly hy growth throughout life, the
living chamher very slightly or not sensihly contracted in the gerontic stage. Aperture con-
stantly open, and with slight dorsal as well as somewhat deeper and
hroader hyponomic sinuses. Siphuncle generally small and empty,
hut actiniform lamellae and an endosiphuncle sometimes occur.
Shells as a rule smooth or with transverse hands only, hut longitu-
dinal Striae are often present in earlier stages.

Rizoceras Hyatt (Fig. 1131). Orthoceracones and exo- or
endogastric cyrtoceracones liaving circular or elliptical sections.
Living Chamber extraordinarily large and long as compared with
camerated part. Silurian to Carboniferous.

Gyrtorizoceras Hyatt. Sections more com-
pressed than in Rizoceras, living Chamber
shorter and apt to be more or less laterally
compressed in gerontic stage, but the dorso-
ventral diameters only very slightly so or not
at all. Sutures more sinuous, and with decided
ventral and dorsal saddles. Type G. (Gyrtoceras)
minneapolis (Clarke). Ordovician and Silu-
rian.

Rizoceras robustum
(Barr.). Silurian (E) ;
Bntowitz, Bohemia.
Aperture open. 1/2.

Family 6. Ooceratidae Hyatt.

Orthoceracones and gyroceracones with closely set septa and j,^if,_ 1x32.

large nummuloidal siphuncle in later stages of the ontogeny, hut ooceras (Gyrtoceras)

tuhular in the young. Actiniform. deposits oftener present than in bayhi (Barr.). Silurian

,-„. ^•7 7, j. T ry 1 .77 . (E) ; Lochkow, Bohemia

the Rizoceratidae, out not general. Jiunnels very variable, sometimes (after Barrande).

minutely plicated or hooh-like in section, confined to dorsal side of
tuhe, or sometimes ahsent altogether. Living chamher short and lihe that of Gyrto-
rizoceras; aperture not infrequently sub-trigonal in outline, hut alivays open.

Ooceras Hyatt (Oonoceras Hyatt) (Fig. 1132), Cyrtoceracones more elongated
and usually more compressed than in Gyrtorizoceras, but otherwise similar except in
structure of the siphuncle. Septa rise rapidly on ventral side, and may bend sharply
orad, forming a funnel ridge or Shoulder on that side, but disappearing on the

CLASS V CEPH ALOPOD A 6 1 1

opposite side of tlie saiiie funiiel. When the funnel itself is absent, the ridges look
like reversed funnels or collars. Silurian.

Gyrtoceras Goldf. Large exogastric, breviconic cyrtoceracones ; sections depressed
elliptical or approximating to trigonal, the dorsum more or less flat, and venter
elevated. Apertiire contracted in gerontic stage to a T-shaped opening, and placed at
an acute angle witli the central axis, so that the dorsal side is very miicli shorter than
the ventral. Siphuncle large, nummuloidal, with well-developed actiniform lamellae,
and with an endosiphuncle in later stages of ontogeny. Devonian.

Family 7. Oncoceratidae Hyatt.

Ä phylogerontic group of breviconic orthoceracones and cyrtoceracones similar to
Cyrtorizoceras, but shells much shorter and living Chamber usually contracted, especially
in their transverse diameters during the gerontic stage. Siphuncle tubulär or highly
nummuloidal, without deposits.

Eremoceras Hyatt. Cyrtoceracones similar to Gyrtorizoceras, but living Chambers
longer, and aperture more or less flaring and open. Siphuncle more or less nummu-
loidal. Type E. (Gyrtoceras) syphax (Bill.). Ordovician.

Gyclostomiceras Hyatt. Slender, short, exogastric orthoceracones and cyrtocera-
cones, circular or compressed in section. Living Chamber as compared with camerated
part longer and larger than in most forms, less contracted, and with open aperture in
gerontic stage. Type G. {Gomphoceras) cassinense (Whitf.). Ordovician to Devonian.

Oncoceras Hall. Compressed exogastric cyrtoceracones with sections like Gyrtori-
zoceras, but Shells as a rule much shorter and smaller, and siphuncle more distinctly
nummuloidal. Living Chamber also more flattened laterally, the aperture elongated
and often sub-trigonal, but typically open. Ordovician.

Subgenus : Meloceras {Melonoceras) Hyatt. Similar to the last, but lateral edges
of the gerontic aperture grow inwards, and form pear-shaped outlines. Silurian.

Family 8. Poterioceratidae Foord.

Smooth, breviconic orthoceracones and cyrtoceracones having circular or depressed
elliptical sections. Gerontic aperture, except in primitive forms, is contracted and apt to
issume a sub-trigonal outline; it is laterally narrowed and approximates those of the
lext family only in Streptoceras. Outlines of aperture entire ; sutures straight or only
kightly sinuous. Siphuncle in this and remaining families, so far as knoum, slightly
mmmuloidal and empty in the young, but becomes larger ; in specialised forms it is apt
be more or less filled with radiating lamellae, and in late stages has an endosiphuncle.

Glinoceras Mascke. Ordovician to Devonian. Sycoceras Pictet. Devonian.

Poterioceras M'Coy (Apioceras Fischer ; Äcleistoceras Hyatt). Orthoceracones and

exogastric cyrtoceracones, short and stout, with sub-trigonal gerontic aperture. Brachial

krea not decidedly differentiated from the hyponomic sinus, and contraction may take

)lace in all diameters or more extensively in the lateral. Ordovician to Carboniferous.

Streptoceras Bill. Like the last but more arcuate, with laterally contracted
iperture, and a short hyponomic sinus distinct from the brachial area. Silurian.

Family 9. Trimeroceratidae Hyatt.

Smooth breviconic orthoceracones and cyrtoceracones similar to Poterioceras in aspect
md sutures, but more slender, eqjecially in the young, and aperture very distinct in
imitive forms. Even the latter usually have the brachial distinctly marked of from
fhyponomic area by ingrowth of sides of the aperture, and in all specialised shells the

612

MOLLUSCA

PHYLÜM VI

hyponomic sinus and special inflections known as " brachial sinuses " are formed by bases
of the arms on edges of the brachial area. Finally, the aperture becomes reduced to a more
or less Y- or T-sha])ed figure, with an open semicircular sinus at the end of the hyponomic
slit or area, and similar sinuses in the edges of the brachial slit, corresponding to the
number of arms. Silurian.

Mandaloceras Hyatt (Dimorion Barr.) (Fig. 1133). DifFers from Poterioceras in
the gerontic aperture, wliich is laterally contracted, and has hyponomic and brachial
areas distinctly differentiated in all but the most primitive species. More specialised
forms have these areas narrowed down, but special sinuses are not formed.

Trimeroceras Hyatt (Trimorion, Trimeres Barr.) ; Pentameroceras, Septameroceras
Hyatt. Silurian. Aperture in the first has a median and
two brachial ; in the second a median and four brachial ;
and in the last a median and six brachial sinuses.

Mandaloceras (Gomphoceras) bohemicum (Barr.). Silurian (Etage E) ;
Dvoretz, Bohemia. A, Side view of conch. B, Aperture.

Fig. 1134.

Tetrameroceras panderi
(Barr.). Silurian (E) ; Dvoretz,
Boliemia. i/j (after Barrande).

Hemiphragmoceras Hyatt. Compressed endogastric cyrtoceracones having a
narrowed hyponomic area like Phragmoceras, but with brachial areas as in Dimeroceras.
Type H. (Phragmoceras) pusillum (Barr.).

Tetrameroceras Hyatt {Tetramorion, Tetrameres Barr.) (Fig. 1134). Like the last,
but with more highly contracted aperture and four lateral sinuses.

Hexameroceras Hyatt. Brachial area with six lateral sinuses. Octameroceras
Hyatt. Brachial area with eight lateral sinuses. Type 0. {Phragm.) callistoma (Barr.).

Family 10. Phragmoceratidae Hyatt.

Smooth breviconic cyrtoceracones and gyroceracones rapidly expanding by growth in
their dorso-ventral diameters, and having open apertures only in primitive types or the
young and ephebic stages of more specialised forms. In the latter gerontic apertures are
laterally contracted and have a very long hyponomic area terminated by a large
hyponomic sinus. The brachial area may be more or less open and ellijjtical, or
narrowed and transversely elongated, but always has an entire outline. Siphuncle
generally large, nummuloidal, and often has actiniform lamellae and endosiphuncles in
later stages. Shells mostly endogastric.

Godoceras Hyatt. Excessively short and rapidly expanding cyrtoceracones like
some species of Rizoceras, but with large living Chambers, narrow venter, and large
siphuncle just ventrad of centre. Aperture constantly open. Type G. (Gyrtoceras)
domitum (Barr.). Silurian.

Protophragmoceras Hyatt (Fig. 1135). Similar to the last, but form more com-

CLASS V

CEPHALOPODA

613

l)ressed, and sipliuiicle iiear the venter (internal). Ditfers from Phragmoceras in
having aperture open throughout life. Type P. {Cyrtoceras)
murchisoni (Barr.). Silurian.

Gomphoceras Sowb. Stout short orthoceracones and
cyrtoceracones similar to some species of Phragmoceras, but
straighter, stouter and less conipressed in form, and gerontic
aperture less contracted laterally. Hyponomic siniis
sh orter, and curvature exogastric. Ordovician and Silurian.

Phragmoceras Sowb. (Figs. 1136, 1137). Compressed
endogastric cyrtoceracones and gyroceracones, oval in
section, and venter narrowly roiinded. Siphuncle large
and near the venter (internal). Gerontic aperture much
contracted laterally, the hyponomic area very long and
narrow. Silurian.

Incertae Sedis.

Fifi. 1135.

Nothoceras Barr. Represented by the single species N. rrotc/pliragmoceras murchisoni
hohemicum Barrande, in which the septum turns orad, SSJ^kL, bSL. ^^Vr** ^^ '
forming an inverted funnel. This funnel connects with

a more or less inflated sheath that closed the siphuncle, and connected it with the
distal opening of the next succeeding septum, thus completely reversing the relative
positions of funnels and sheaths in other forms. The appearances as described by

^r^

Fig. 1130.

Phragmoceras hroderipi Barr. Silurian (^tage E) ; Lochkow, Bohemia.

1/2 (after Barrande).

Fio. 1137.

Phragmoceras loreni
Barr. Silurian (E) ; Loch-
kow, Bohemia. Section
showing laniellar organic
deposits (ait«r Barrande).

Barrande are not deemed suflficient to prove the truth of this statement, and it is
unsafe to accept it absolutely until the development has been studied. The cavity is
divided by radiating lamellae running longitudinally as in the Actinosii)honata.

614 MOLLUSCA phylüm vi

Range and Distribution of the Nautiloidea.

Fossil Nautiloidea have been recorded by Billings as occurring in Canada earlier
than tlie Quebec Group, but bis statement lacks confirmation. An abundant Ceplialo-
podan fauna makes its appearance in tlie earliest Quebec or Calciferous, and is quite
distinct from other later assemblages, JJiphragmoceras and otber ortboceracones and
cyrtoceracones with very peculiar sipbuncles occur here, but gyroceracones and nautili-
cones are absent. However, the information we have at present of this fauna is
limited, and but few positive conclusions can be drawn.

All the suborders of Nautiloidea are initiated in the Ordovician, and one of them,
^chistochoanites, is confined to this period. Holochoanites and Mixochoanites become
extinct in the Silurian, and only Orthochoanites survive the Paleozoic. The sub-
orders that disappear at this early date are remarkable for their complicated siphun-
cular structure, and peculiar sigmoidal septa observed in the gerontic living Chambers
of certain forms (Äscoceras, Gonioceras), while their prevailing habit is gyroceraconic.
The sigmoidal septa do not become complicated in correlation with closer coiling of the
Shell, but occur in cyrtoceracones correlating with highly compressed cones, and in
ortboceracones correlating with strongly depressed cones.

The older classifications recognised the straight ortboceracones, curved cyrtocera-
cones, loosely coiled gyroceracones, and more closely coiled nautilicones as distinct
natural divisions. Although it is possible to employ the habit of curvature in con-
junction with family groups as a convenient means for tracing laws of distribution and
the like, yet for more accurate data the genera must be considered independently.
For instance, some families made up largely of gyroceracones and nautilicones also
contain a few ortboceracones and cyrtoceracones, and these have to be neglected in
estimating the relative proportions of straight and coiled conchs. Other sources of
error are presented by sporadic uncoiled or gerontic forms whicli occur in families
having coiled shells. In a general way, however, it is possible to state the morphic
succession as follows : —

Ortboceracones, together with their almost invariably associated cyrtoceracones
exceed gyroceracones in the Quebec in the proportion of three families to one, and this
horizon contains but one family of closely coiled nautilicones, and one of the uncoiled
or gerontic type. In the Ordovician are found no less than fourteen families having
straight or approximately straight shells, as against seven families of gyroceracones and
nautilicones. Thereafter until toward the close of the Paleozoic, the proportions of
straight and coiled forms remain approximately equal. The Permian has but one
surviving family of ortboceracones, and four of the coiled groups ; in the Trias the
ratio is one to six, and in the Jura coiled forms alone persist. Thus, a slowly working
tendency is apparent, leading to the production of more and more closely coiled cones,
and the elimination of straight and slightly curved forms. Gyroceracones disappear
with the Carboniferous, and the more discoidal nautilicones with the Trias.

Some Gurions features are presented by the phylogerontic or uncoiled shells. Only
one family, the Silurian Lituitidae, have all the genera uncoiled save the probable
ancestral close-coiled type. Other families have isolated genera or species exhibiting
similar tendencies, and becoming partially uncoiled during their later stages, although
close-coiled in the young. Such forms occur throughout the Devonian, but none have
yet been found in the Carboniferous, where uncoiling of the volutions, when it
occurred, took place earlier than the gerontic stage. From the Mesozoic and later
horizons, no species is known in which the gerontic stage is to the slightest degree
uncoiled.

Torticones are more aberrant than any other conchs, and may be best classified as
phylogerontic forms, since tendencies toward unsymmetrical development of the
volutions occur in the gerontic stage, and are genetic in but a few genera, where they

CLAss V CEPHALOPODA 615

r

appear during tlie early stages and are preceded so far as known by a symmetrical
volutioii. The first manifestation of torticones is in the Ordovician, and tlieir acme is
attained during tlie Silurian. As regards ornanientation, annnlated shells appear in
the Calciferous, and those with longitudinal ridges later in the Ordovician, together
with tiiberciilated and costated gyroceracones and nantilicone.s. The last-named, how-
ever, are nuich more abimdant in the Devonian and Carbon iferous, after which they
disappear. Very higlily ornaniented shells exist in the Trias, but following this
period the conchs are smootli.

Very striking is the marvelloiisly sudden rise of the Nautiloidea as a gi'oup,
reaching its maximiim in the Silurian, and followed by a decline extending from the
Devonian to the Trias. Then the forces acting unfavourably upon their existence
were arrested, or their violence lessened, and the group has been affected by only very
sliglit changes, and an exceedingly slow process of retrogression until the present time.
The acme of siphuncular differentiation occurred in the Ordovician, of general morphic
diversity in the Silurian, of ornamentation in the Devonian, and of sutures in the
Trias.

Geographically considered, some facts of distribution are of general interest. The
fauna of the Quebec or Calciferous, which in Newfoundland, Canada, Vermont, and
the vicinity of Poughkeepsie, New York, is rieh in fossil remains, is represented by
a few camerated conchs in the Durness Limestone of Scotland. Holochoanites and
Schistochoanites 'are most plentifully represented in the American faunas, but Mixo-
choanites very sparsely so, at least as compared with the Oi-dovician and Silurian of
Bohemia. The same is true of the Lituitidae, Ophidioceratidae and Hercoceratidae
among Orthochoanites, and of the Jovellanidae, Trimeroceratidae, and kindred families
among the Cyrtochoanites. The Devonian and Carboniferous faunas of America
and Europe are nearly on a par, but the Permian of the western hemisphere is
very deficient in Nautiloid remains. The Jurassic faunas of America have so far
yielded but one specimen of a Nautiloid, but they were probably present to some
extent, since they are represented in the Cretaceous of this country. During the
Cretaceous and Tertiary the principal distribution of the Nautilidae was in the
eastern hemisphere, and the last surviving species of Nautilus are now restricted to
oriental waters. The following table shows the ränge of the leading Nautiloid
families.

[The systeniatic portion of the foregoing chapter on Nautiloidea was revised for the first
edition of this work by tlie late Professor Alpheus Hyatt. In the earlier edition some nine-
teen new genera of fossil Nautiloids were proposed by Professor Hyatt, as well as many new
genera of Ammonoids. The type species of these new genera were designated, but tlie author's
intention to publish suitable generic diagnoses has remained for the most part unfulfilled.
—Editor.]

[Tablk

616 MOLLUSCA

*

Table showtng Vertical Range of the Nautiloidea.

PHYLÜM VI

Families.

c
.2

o

.g

CO

CS

2
Vi

1
1

.2
1

CS

i s

2

1-5

i
1

1

1

A. HOLOCHOANITES

1. Dipliragmidae .

2. Endoceratidae .

3. Cyrtendoceratidae .

B. MiXOCHOANITES

1. Ascoceratidae .

2. Mesoceratidae .

C. SCHISTOCHOANITES

D. Orthochoanites
1. Orthoceratidae .

—

—

—

2. Cycloceratidae .

3. Kionoceratidae

4. Tarphyceratidae

5. Trocholitidae .

6. Plectoceratidae

7. Ophidioceratidae

8. Lituitidae

9. Grypoceratidae

10. Clydonautilidae

11. Halloceratidae .

12. Ryticeratidae .

13. Rhadinoceratidae

14. Trigonoceratidae

15. Triboloceratidae

16. Rhineceratidae

17. Hercoceratidae .

18. Tainoceratidae .

19. Centroceratidae

20. Pleuronautilidae

21. Koninckioceratidae

22. Solenocheilidae

23. Estonioceratidae

24. Nautilidae

!

i

—

—

_^^

„^^

_^_

—

^

i

E. Cyktochoanites
1. Loxoceratidae .

,.

2. Uranoceratidae

3. Actinoceratidae

4. Jovellanidae .

5. Rizoceratidae .

6. Ooceratidae

7. Oncoceratidae .

8. Poterioceratidae

9. Trimeroceratidae

10. Phragmoceratidae .

•

—

__.

.__

1.

1

—

!

ii

! 1

CLAss V . GEPHALOPODA 617

Order 2. AMMONOIDEA Zittel.i

Shells similar io ihose of the Nautiloidea in some primitive Paleozoic groups, hut
these give rise to others with mwe highly ornamenied shells, the apertures of which
have ventral rostra instead of hyponomic sinuses. Sutures, as a rule, have ventral
lobes in the later stages of ontogeny ; the inßedions become more numerous than in
Nautiloids even in Paleozoic genera, and their outlines during the Mesozoic are
cxtremely complex. Siphuncle invariahly small, and (except in the Clymeniidae)
situated near the venfer. Funnels short, retrosiphonate in primitive forms, hut
becoming sometimes pirosiphonate during the Paleozoic, and as a rule, prosiphonate
during the Mesozoic.

The ontogeny begins with a calcareous protoconch, the apical stage of the
conch being an open neck built in continuation of the permanent aperture of
the protoconch. The first septum is concave as in Nautiloids, and sutures are
straight or have more or less of a saddle on the venter. Young stages of
Mesozoic shells recapitulate the primitive adult characters of Paleozoic forms.
The aperture was closed when the animal was retracted by a single horny plate
(anaptychus) or a pair of calcareous plates (aptychis), probably secreted by
muscular lobes homologous with the hood in Nautilus.

Shell Characters. — There are apparently no characters, not even the presence
of a calcareous protoconch, which can be relied upon to separate Bactrites from
the orthoceraconic Nautiloids. Nevertheless, the position of the siphuncle and
its peculiar funnels are features which seem to place this form with true
Paleozoic Ammonoids. There is but one series of straight shells among
Ammonoids, and these are obviously not the same as orthoceracones, but are
more properly called bactriticones (Fig. 1169). Similarly, the loosely coiled
Mimoceras shells (Fig. 1170) are not gyroceracones, but only their morphic
equivalents in a different genetic stock ; hence the term mimoceracone should
be substituted for gyroceracone. In the same sense the closely coiled sym-
metrica! Shells, comparable in external aspect and intimate structure with
nautilicones, should be described among Ammonoids as ammoniticones. The
term torticone, however, can be conveniently applied to both groups, since it
does not connote any special structures, but is a general name for all asym-
metrical spirals.

Ammoniticones in some Paleozoic forms are mimoceracones during
nepionic stages, and consequently in later stages a Perforation is present
passing through the umbilicus as in Nautiloids. However, in most Paleozoic
and all later ammoniticones, the coiling is so close even at the beginning

^ Besides the works cited the followhig nmy be coiisulted : — Buckman, S. S., Divisions of so-
caUed Jurassic Time. Quar. Jonrn. Geol. Soc, 1898, vol. Uw—Clarke, J. M., The Naples Fauna.
16th Ann. Rep. N.Y. State Geologist, 1898.— CVicyfc, G. C, Muscular Attachment of the Animal
to its Shell in Animonoidea. Trans. Linn. Soc, 1898, ser. 2, vol. vü.—Haug, £., Etudes sur les
Goniatites. Mem. Soc. Gt'ol. Frunce, Paleont., 1898, vol. \n.—Levi, ('., Fossili degli strati a
Terebratula aspasia. Boll. Soc. Geol. Italia, 1895, vol. xv.—Parona, C. F., and Bonarelli, O.,
Faune du Callovien inferieur (Chanazien) de Savoie. Mem. Acad. Savoie, 1897, vol. vi.— Semenoff, B.,
Anwendung der statistischen Methode zum Studium der Vertheilung der Ammoniten. Ann. Geol.
Mineral. Russie, 1897, vol. il— Smith, J. F., Development of Lytocerasand Pliylloceras. Proc. Calif.
Acad. Sei., 1898, vol. \.~-Choffat, P., Les Ammonees du Bellasien, des Conches a Neolobites Vibra-
yeanus, du Turonien et du Senonien. Faune cret. du Portugal, 1898, ser. 2, vol. n.—Jackson, lt. T.,
Localised Stages of Development in Plauts and Animals. Mem. Boston Soc. Nat. Hist., 1899, vol. v.
— Novak, J., Untersuchungen über die Cephalopoden der oberen Kreide in Polen. II. Die Scaphiten.
Bull. Acad. Sei. Cracovie, ser. B, 1911.

618

MOLLUSCA

PHYLUM VI

of the conch, that the protoconch is closely enwrapped by the first volution,
and no Perforation is visible even under a magnifier. There are two pits,
however, one on either side of the apical end of the conch, which remain as
remnants of this Perforation, and are present in all ammoniticones (except
perhaps certain Clymeniidae). The bactriticone obviously represents the
primitive or primary radical of the Ammonoidea, and the mimoceracone the
next or secondary radical of this Order.

Ammoniticones of the Nautilinidae introduce a peculiar form of volution,
the anarcestean (Fig. 1171), which is depressed and crescentic in section, and
may be regarded as an ancestral radical. These f orms evolve a series becoming
more involute and compressed (Fig. 1172), and some with elevated or narrow
venters and well-defined lateral zones (Fig. 1173), but still retaining in the
young more or less of the anarcestean aspect. The Clymeniidae have a few
radical forms of similar aspect and with somewhat similar sutures (Fig. 1165) ;
they then produce a series of compressed discoidal shells having cordiform or
quadrate sections (Figs. 1166-1168), and these also develop involute forms
among specialised species. The Gephyroceratidae and Beloceratinae have a
similar history, but in the Glyphioceratidae coronate or gastrioceran forms with
trapezoidal section and broad venter become common in the ephebic stages
(Fig. 1196). In the more specialised groups, the anarcestean character re-
appears only during the young stages.

Phylogeronetic series (Bhabdoceras, Cochloceras) make their appearance in the
Upper Trias, become more abundant in the Jura, and still more important
during the Cretaceous. They have their own peculiar radicals, sometimes
found among discoidal and again among more involute shells, but for the
most part they do not originate from smooth shells.

The same descriptive terms are used for shell characters among
Ammonoids as among Nautiloids. Obviously the first stage of the conch

Fig. 1138.

Asellate protoconch of Gephyroceras calculi-
forme (Beyr.). Upper Devon ian ; Büdesheim,
Bifel. A, viewed from in front. B, From the
side (after Branco).

Fig. 1139.

Latisellate stage of Ärcestes cymhiformis (Wulfen).
Trias ; Anssee, Austria. A, Viewed from in front.
B, From the side (after Branco).

was that of a living Chamber, the protoconch being without internal septa
or siphuncle (Fig. 1150). Then, after building out the usually flattened
neck or apical part of the conch, the animal rested, and the first septum as
well as the caecum (or incipient stage of the siphuncle) was secreted. The first
septum closed the aperture of the protoconch, and the caecum projected into
its interior. The caecum is connected with the internal surface of the proto-
conch by bands (Figs. 1150, 1151); or semiconical prolongations, described
by Munier-Chalmas as the prosiphon. But these bands are of various shapes,
are not connected with the interior of the caecum, and appear to be merely

CLASS V

CEPHALOPODA

619

Fig. 1140.

Angustisellate stage of Phyllocercwi
heteropJiyllum (Sowb.). Lias.

calcareous supports for the bottom of the caecum. The earliest sutures,

desci'ibed in a masterly way by Branco, are divided by him into thiee classes :

asellate, latisellate and angusfisellate (Figs.

1138-11 40). The asellate cross the venter as

a straight line or very slight saddle, and are

present only in the ephebic stages of Cyrto-

chjmeniaCl) and in the young mimoceran stage

of the Nautilinidae. In all except primitive

forms it is confined (as are most of the

purely nautiloidean characters) to the first

septum. The latisellate stage is character-

ised by a decided broad saddle on the

venter, with corresponding deeper and broader lobes on the sides. The

angustisellate stage has prominent, sometimes almost sub- acute ventral

saddles with corresponding deep lateral lobes, accompanied by definite saddles

at the umbilical depressions.

The last two stages are progressive modifications confined to the larvae of
Ammonoids, and are not present in the ephebic stages of any known species.
The asellate condition of the first septum is found in the ananepionic stage of
one species of the Clymeniidae, according to Branco, but his figure shows a
saddle on the venter. The Nautilinidae and Gephyroceratidae are asellate, and
the Glyphioceratidae also in some primitive Devonian genera, but latisellate in
others, and angustisellate in the Trias. The Triassic Lobitidae and Arcestidae
are latisellate, while the Cladiscitidae and the Phylloceratidae are angustisellate
^ ji c throughout. The

embryosof theCera-
tidae are very little
known, but are sup-
posed to be latisel-
late, while the
highly specialised
Pinacoceratidae are
angustisellate. The
remaining system-
atic groups are
wholly Jurassic and
Cretaceous, and so
far as known, the
first septa are an-
gustisellate.

Sutures} — The second septum (Fig. 1141) in all but the most primitive
forms becomes divided by an entire azygous lobe on the venter, often termed
the " siphonal lobe," but herein after feferred to as the ventral lohe, and by a

^ The terminology comnionly in vogue designates the sutural inflectioiis as follows : — The ventral
or external lobe is bounded on eitlier side of the mesal plane by the \a.vge ßrst or mpeincn'-lateral
saddle. This is followed by the first or superior-lateral lobe, and then come the second or inferior-
lateral saddle and lobe in tlie order nanied. All additional inflections occurring ])etween the second
lateral lobe and the line of Involution are termed auxüiaries, and are nntnbered in replar order.
The antisiplional is also known as the internal, dorsal or coiiwiellar lobe. By "lobes" are always
nnderstood the angulated or digitated portions of the snture which are directed backicards, away
froni the niouth of the shell ; " saddles " are the elevations between them, which point tmcards the
aperture of the shell.

^^WxATN

A, Development of sntures in a latisellate Qoniatite, Gastrioceroft dioxlrma
(Goldf.). Lower Carboniferous ; Choquier, Belgiiini. B, Same in a latisellate
Ammonite {Tropites suhhuUatiis Hauer). G, Same in an angustisellate Ammonite
(all after Branco). Sutures of the first volution are lettered consecutively from
<i toi; those of the second from m to s.

620

MOLLUSCA

PHYLÜM VI

smaller azygous lobe (shown to the left in Fig. 1141, A-C) on the dorsum,
usually termed the

LSm

Suture - line of Cyrto
clymenkt laevigata Münst
Devonian.

Suture-line of Anarcestes subnautülnus
(Schloth.)- Devonian.

L EL

Fig. 1144.

Suture-line of Aganides sulcatus
(Münst.). Devonian.

oZ2 aZl

Left half of suture-line of Ceratites nodosus
de Haan. Trias.

f/. This imdivided ventral lobe (Figs. 1143,
1144, EL) persists
throughout the Nau-
tilinidae so far as
knovvn, and is obliter-
ated by a secondary
ventral saddle only
in the Clymeniidae.
It is present throughout the ontogeny of the simplest or radical forms of
Glyphioceratidae, Beloceratinae and Arcestidae. But in the Devonian Gephyro-
ceratidae and
in the Triassic
Ceratidae, shells
having imdivided
ventral lobes have
notbeenrecorded;
in the Tirolitinae
but one such

species has been doubtfully described. This class of radicals is replaced in
these groups by those having the ventral lobe divided by a small saddle

usually called the ventral or
siphonal saddle (Fig. 1146, m).
The class of radicals having
entire ventral lobes disappears
before the close of the Trias.

The entire antisiphonal lobe
has a more extensive distribution
than the entire ventral lobe, being
present throughout the ontogeny
of Nautilinidae, Clymeniidae and,

Siphonal saddle; n, Line of inrolution. EL, Ventral (also p „„ViTTT^/^«QT.r,f I^^orv IV/Tz-wcf r^f fVio

called siphonal or external) lobe, traversed by the siphuncle. Vrepnyroceratmae. IViOSL Ol tne

L First or superior-laterallobe ;?, Second or i^ Glyphioceratidae have this lobe
lobe. ES, LS^, LS^, First second, and third lateral saddles. . , . , i •r> t •

IS, Dorsal saddle. IL, Antisiphonal lobe, i, First dorsal entire, but it beCOmeS bind ID ths

lobe lying on line of Involution. i , , j. • ^' i £

later stages oi specialised lorms.
The radicals of Beloceratinae have it entire, but in specialised genera it becomes
bifid or even trifid. It is known to be entire in only a few of the Lecanitinae,
and is bifid in most of the Ceratitidae and Arcestidae, besides having for the
most part entire sides. It is also entire in some phylogerontic species of the
Trias. In the Desmoceratidae and Ly toceratidae it is generally bifid, but may
be trifid or irregulär in some species, and is accompanied by an extraordinary
growth of two of the branches inwards in a large number of forms. In
Jurassic and Cretaceous Ammonoids, it is as a rule more or less complicated
by the development of secondary inflections on the sides, termed marginals.

Paired or zygous lobes and saddles (Fig. 1141) appear between the two
azygous lobes and belong to two series, the laterals or externals, and the
dorsals. The first broad external lateral inflections, called the " first pair of
lateral saddles," are formed by the ventral lobe and the corresponding first
pair of dorsals by the formation of the antisiphonal lobe ; and between these
there appears a broad lobe, either wholly or the most part external (Fig.

FiCx. 1146.
Kight suture-line of Coroniceras bisulcatum Brug. Lius.

CLASS V

CEPHALOPODA

621

1141, J). This is the stage marked by four lobes and saddles — two azygous
and two zygous lobes, and four zygous saddles. The wide lateral lobes in the
next stage (Fig. 1141, Ck) are divided by saddles that arise on or near the lines
of Involution. These divide the two lobes into four, one pair being in part or
wholly dorsal, and becoming eventually the first pair of dorsal lobes ; the
others develop into the "first pair of lateral lobes." There are accordingly
six lobes and six saddles at this stage. In the next stage (Fig. 1141, A, Bm,
Gm) the saddles bridging the lines of involution become divided by lobes
arising on or near the lines of involution, and the inner arms of the saddle so
formed thus become the second dorsal saddle, while the outer form the second
lateral saddles ; but in some forms they may both pass into the lateral series.
This stage, therefore, has eight lobes and eight saddles — three paired lobes
and four saddles on either side of the mesal plane, and two azygous lobes.

Additional inflections arise in like manner along or near the line of
involution during succeeding stages. But there is considerable irregularity in
their advent even in the eight-lobed stage, and still more so at later periods ;
hence the above description must be regarded as a very general one, although
serving to indicate a few primitive lobes and saddles that are generated during
the younger stages, and are usually recognisable in the adult.

In subsequent stages additional inflections arising on or near the lines of
involution pass outward as the sides of the shell broaden by growth ; and the

Fio. 1147,

Pinacoceras tnctternwhi (Hauer). Keuper ; Someraukogel, near Hallstadt, Äustria. Left suture-line, much
reduced, showing auxiliary (inner) and adventitious (oiiter) inflections. The three longest lobes in the niiddle
are the flrst, second, and third laterals (after Hauer).

same law holds true for the dorsum, but of course here the inflections pass
inward toward the mesal plane. The number of inflections on the dorsum is
more limited in all forms than the laterals, and they have simpler outlines.
The inflections added to the sides after the first two or three saddles and lobes
appear are usually called the aiixiliaries (Figs. 1145, al; 1147), but the current
use of this term is not consistent with the development of the inflections, and
the distinctions are based for the most part on the contrast in size between
the saddles and lobes as they appear in the adult of different types. When
the ontogeny is known, however, the auxiliary inflections can be properly
discriminated and described, but otherwise are liable to confuse the nomen-
clature. Adventitious inflections (Fig. 1147) arise between the first pair
of laterals and the median line of the venter, either by the growth of
marginals in the arms of the ventral lobe, or by division of the outer parts of
the first lateral saddles, or by division of the inner parts of the siphonal

saddle.

The reo-ions of greatest metabolism or growth-changes in each genetic
series are near the lines of involution, and it is here that new inflections are
usually formed. The later formed lobes and saddles in these regions repeat

622 MOLLUSCA phylüm vi

in their own development the ontogenetic stages of modification through
which the older ones have already passed. It follows also from this that the
lobes and saddles nearest the umbilical lines of In-
volution are simple and often entire, and are parts
of a series that become progressively more compli-
cated outwards to the lines or columns of the oldest
class — the first lateral lobes and saddles. When
there are adventitious lobes, this series is reversed
on the ventral side of the first pair of saddles. The
inversion is sometimes quite complete, as in some of
the Beloceratinae, thus indicating unusual metabolism
on the venter like that of the regions of Involution.
Jackson's law of the localised recapitulation of onto-
MMffiSfwiuSiLS^'TSl genetic stages is well exemplified by the history of
FeXarfoS; V^AntSlphonai sutures amoug Ammonoids as already shown by him

lobe ; L, Superior' lateral lobe ; in Placeuticeras.

l, Inferior lateral lobe; ES, Ex- ™, , .1. i r j • j.- j.i i i i

ternai saddie ; LS, Is, First and i he above method of desiguatiug the lobes and

second lateral saddles. saddles as paired in the external aspect and on the

dorsum on either side of the mesal plane disregards, for sake of convenience,
an important fact that should be noted ; namely, that the azygoüs ventral and
dorsal lobes are in reality paired with each other in the mesal plane ; also
that the primitive dorsals and external lateral inflections correspond in the
same sense to one another, and are also more or less united across the septa
in some forms.

The outlines of the paired lobes and saddles first become complicated in
the Carboniferous Glyphioceratidae. "Minor or marginal inflections are intro-
duced, and what are termed bifid or trifid lobes occur in the arms of the ventral
lobe (Fig. 1182) ; they then affect the primitive first lateral lobes and saddles,
and extend thence toward the line of Involution (Fig. 1187). These marginal
inflections increase greatly in niimber and complexity during the Permian,
become preponderant in the Trias, and universal in the Jura and Cretaceous.
Duiing the Carboniferous it is the lobes only, as a rule, that are thus modified;
but in the Permian the saddles too are often aff'ected. * The modifications
in outline proceed from the lobes to their sides, and thence to the saddie bases,
except in certain cases when direct division of the saddles takes place by the
outgrowth of secondary median lobes that divide their bases. All these
secondary lobes and saddles are termed marginals.

Siphuncle. — The caecal condition of the siphuncle is apparently confined to
the ananepionic stage or first septum, but J. P. Smith has shown that some
species of Lytoceras and Phylloceras have a bulbous enlargement of this organ,
which may persist in several nepionic camerae. This is apparently a persistent
remnant of the caecal enlargement. The siphuncle of all Ammonoids is larger
in Proportion to the volution, and apt to be nearer the centre (Figs. 1149, 1150)
during the young than at later stages, and is also retrosiphonate, as in Nauti-
loids. It remains retrosiphonate in the Clymeniidae, Nautilinidae, and most
Gephyroceratidae,as well as primitive forms of Glyphioceratidae; but it becomes
transitional (having both funnels and fofwardly directed collars) in more
specialised Carboniferous Glyphioceratidae, and finally prosiphonate (funnels
lost collars alone remaining) in Permian genera. Most Triassic and all Jurassic
and Cretaceous genera have the siphuncle chloiochoanitic. The above stages

I

CLASS V

CEPHALOPODA

623

are repeated in regulär succession during the ontogeny of chloiochoanitic forms
(Fig. 1149) except when accelerated development (tachygenesis) occurs, and

Fio. 1149.

Tropites cf. phoebus Dittm. Trias. Bn-
larged section in the median plane of the
young, showing retro.siphonate funnels in
the nepionic stage, then transitional, and
later prosiphonate funnels. a, Position of
protoconch (after Branco).

Amaltheus spinatus Brug. Lias.
Section parallel to median plane, show-
ing Position of the siphuncle. a, Pro-
toconch ; c, Caeciim (after Branco).

then the monochoanitic stage may disappear. The reduction in size of the
siphuncle among Ammonoids is obviously correlated with loss of functional
importance, as is also the case among more specialised Nautiloids ; and con-
sequently organic deposits are not found in the caraerae of these shells.

Living Chamber. — This varies greatly in
all of its dimensions, thus indicating difFer-
ences in the size and proportions of the
animal, since its body parts were probably
wholly contained within this cavity. The
lines of growth and the few apertures known
among Nautilinidae and Clymeniidae show
that they had hyponomic sinuses on the
venter, and were swimmers like Nautiloids.
The same was probably true of the Gephyro-
ceratidae, except during the gerontic stage of
some species when a ventral crest arises, as Fig. 1151.

demonstrated by Clarke. In the Glyphio- ParUnsonia parkinsoni (Sowerhy). Middle

ceratidae and Beloceratidae many species that wShuib^lTenirrglTenUcrprlsip^^^
retain the so-called goniatitic form have «ndposition of protoconch (a) ^^^^^
hyponomic sinuses, but occasionally short

ventral crests appear, and later these become general. Only radical
Paleozoic forms of the-Arcestidae have retained the hyponomic sinus ; short
obtuse crests appear in the Trias, and continue thereafter. Jurassic and
Cretaceous Ammonoids have as a rule more pointed rostra than those of the
Trias, and frequently develop lateral crests and lappets (Figs. 1152, 1156).

Very decided decrease in the dimensions of the living chamber during the
senile stage does not occur as a rule among Paleozoic forms ; but this con-
dition appears among the Triassic Haloi'itinae and Tropitidae with a corre-
sponding contraction of the aperture. The Arcestidae (Fig. 1222) and some
species of the Ceratitidae also often have very narrow openings during the

624

MOLLUSCA

PHYLUM VI

paragerontic substage, biit the condition is in no sense phylogerontic except

LoUtes, and the like (Figs. 1217, 1218).

Pompeckj, in an important essay, asserts that contracted living Chambers
are invariably developed in old age, and that
small Shells possessing them are consequently not
immature individuals, but dwarfs (Fig. 1156).
It is probable that large numbers of shells are
indeed dwarfs, but it is also a fact that contrac-
tion of the living Chamber and volutions occurs
in some forms during comparatively early stages ;
and sometimes in such a way as to affect the
ephebic stages of the ontogeny, when the forms
become truly phylogerontic. This latter term is
used to designate shells in which the ontogeny
has become permanently modified by the assump-
tion of retrogressive characters that were intro-
duced first in the senile stages of allied pro-
gressive species. Whether these peculiar forms
SchioenbacUa cristata (Deiuc). have contracted apertures in their earlier stages,

äXum. ^P""*""" ""^"^ '''''^'■^' and then resorb them before building further, or

whether they never add lateral lappets, rostra,

etc., as claimed by Pompeckj, until the last resting stage of the ontogeny

(Fig. 1156), it is obvious that they are permanently affected by phylogerontic

Fig. 1152.

Fig. 1153.

Sphaeroceras hrong-
niarti (Sowb.). Oolite.
Aperture with broad,
contracted ventral ros-
trum.

1154.

Normannites braiken-
rulfji (Sowb.). Oolite.
Aperture with lateral
lappets.

Fig. 1155.

Oppelia nimbaia
(Oppel). Jura.

Lateral lappets.

Fig. 1156.

Oecoptychius re-
fractus (de Haan).
Jura. Living Chamber
contracted, with ros-
trum and lappets.

characters. These forms are comparatively rare in the Trias {LoUtes,
Cochloceras), but their number is sensibly increased in the Jura, although
usually confined to special localities. During the Cretaceous they become
more numerous and more widely distributed (Figs. 1261, 1262). In their
extreme modifications they become more or less uncoiled and finally per-
fectly straight.

Crick and Waagen maintain that Ammonoids had an annular band as well
as shell muscles, and that these served both to hold the anirnal in the living
Chamber, and also formed an air-tight band around the face of the mantle,
fastening the latter to the shell (Fig. 1157). Such was, however, probably
not the only means of attaching the animal to the shell. The steady pro-
gressive complication of sutures, affecting both lobes and saddles as well as

CL.VSS V

CEPHALOPODA

625

Fio. 1157.

Oppelia steraspis (Oppel).
Upper Jura ; Solenhofen. Com-
pressed shell with aptychus (a)
preserved in living Chamber and
distinct impression of sliell
rauscles (h) (after Waagen).

their marginal inflections, is directly correlated with the outgrowth of rostra.

The presence of a rostrum indicates the disuse and disappearance of the

swimming organ {hyponome), which in Nautilus causes

the formation of the hyponomic sinus in the aperture,

and flexed growth-lines on the venter. These facts

and the gregarious littoral habits of Ammonoids show

that they probably crawled along the bottom with

their shells carried above them, very rarely swimming.

Their shells are also less bulky in proportion than

those of Nautiloids, and correspondingly less buoyant.

All these observations justify the hypothesis that the

progressive complication of Ammonoid sutures took

place because of their Utility in helping to carry and

balance the shell above the extruded parts when the

animal was crawling. The greater complication of

the marginals in Jurassic Ammonoids, where the

number of auxiliary lobes and saddles is often reduced

(Fig. 1253), and the multiplication of the principal

inflections in Fseudoceratites of the Cretaceous in com-

pensation for the suppression of marginals (Fig. 1309), are all accounted for

by this theory. The phylogerontic forms, in which the lobes and saddles are

sometimes reduced in number, and the
marginals are also less complex — together
with the Position, form and mode of growth
of the last volution, and the short rostra
— suggest that these creatures could not
have been active crawlers during the
greater part of their ontogeny.

The occurrence of broods of young
Shells in the living Chamber may be taken
as suggesting that some Ammonoids were
viviparous, but the examples of this are
too rare to be relied upon for making a
general Statement.

Opercula. — Plates have been found in
situ closing the aperture and correspond-
ing in position to the hood of Nautilus in
a number of Ammonoid shells (Fig. 1158).
This positive fact, and the obvious fitness
of such plates to serve as opercula, lead
to the inference that they were for med by
an organ similar to the hood of Nautilus,
and protected the animal when it was re-

tracted into the living chamber. When composed of a single piece, the plate

is called an anaptychus ; in such cases it is invariably carbonaceous, and was

doubtless horny in the living animal (Fig. 1160). The anaptychus is rare in

the Paleozoic, and has not yet been found in the Trias, but occurs among the

Arietidae and Amaltheidae of the Lower Jura. The operculum, when formed

of two plates, is termed an aptychus, and is always of calcareous composition.

It is noteworthy that these plates occur uniformly in the same position among
VOL. I 2 s

1158.

Oppelia subradiata
(Sowb.). Inferior
Oolite; Dundry.
Aptychus in place,
closing aperture
(after Owen).

Aptychus Ja mcllonns
preserved as in Fig. 1157.
Upper Jura; Solen-
hofen, Bavaria.

626

MOLLUSCA

PHYLÜM VI

some species from certain localities, inside the living Chamber and close to the
^ j^ venter (Figs. 1159, 1161), a circumstance that led

Waagen to suppose they served to protect the nida-
mental gland of female shells. As shown by Michael
in Oppelia, even the embryonic shells were furnished
with aptychi.^

Aptychi are composed of three layers, of which the

middle one is the thickest and exhibits a cellular struc-

ture, whereas the two outer layers are comparatively

(Fig. 1164). Detached aptychi have been

Fig. 1160.

Anaptychi. A, Amaltheus Clense
nnatus Brug.
B, Goniatites uchtensis Keys

.spiruttus Bvng.ua.8.yy classificd by Zittel into several groups according to

their structure. Cellulosi (Fig. 1163) are smooth, thick
plates, with punctate external surface ; Imhricati (Fig. 1159) have ^ the
surface traversed
by oblique folds
or costae; Pundati
(Fig. 1164, C)
have rows of
punctae and over-
lapping folds;
Granulosi include
thin plates having
the external sur-
face covered with
concentric folds or
rows of tubercles
or spinules ; Bugosi
are thick plates
with irregularly
arranged granules
or rows of nodes on the outer surface

Fig. 1161.

Harpoceras lythense (Sowb.). Upper Lias ;
Boll, Würtemberg. Aptychus in the living
Chamber.

Fig. 1162.

Scaphites spiniger Schlüter.
Upper Cretaceous ; Coesfeld,
Westphalia. Detached

aptychus.

and Cretaceous.

Nigrescentes (Fig. 1161) are covered
with a thin carbonaceous coat-
ing; and Coalescentes (Fig. 1162)
have the two thin plates fused
along a median depression. This
last is a phylogerontic condition
of the aptychus occurring in
Scaphites.

Classification. — Leopold von
Buch prepared the way for a
general Classification of the
Ammonoidea by pointing out
three grand divisions which he
called "genera." These were
the Paleozoic Goniatites, Ceratites,
from the Trias and Cretaceous,
and Ammonites, from the Jura
Von Buch's chief distinctions were based on the outlines of

Fi(i. 1163.

Aptychus laevis v. Meyer. Litliographic Stone ; Solenhofeii
Bavaria. A, External aspect; B, Internal, i/i.

1 Michael, R., Zeitschr. deutsch, geol. Ges., 1894, vol. x\\\.—Retowski, 0..
1891, vol. ii. — Blackmore, IL P., Geol. Mag., 1896, dec. 4, vol. iii.

Neues Jahrb.

Min.J

CLA.SR V

CEPHALOPODA G27

the lobes and saddles, and were as natural and well-founded as the knowledge

Fio, 1164.

Vertical sections of ai)tychi belonging to A, CellvXosi {Ammonites zonatus Stopp.) ; B, Imhricati (Ammonite's
profundiis Voltz); and C, Punctati {A. imnctatus Voltz). 3/j (after Meneghini and Bornemann).

of the time permitted. D'Orbigny, Quenstedt, Sandberger and Barrande
greatly increased our knowledge of structure and Variation, and defined a
number of new genera.

The next marked epoch dates from the publication of Mojsisovics's great
works on the Trias, which made known a fauna as rieh and complex as that
of the Jura. Suess, Neumayr, Branco, Waagen, Buckman, Grossouvre, Haug,
Diener, Douvillö, Kilian, Zittel, Karpinsky, Hyatt and others made advances
of essential importance along difFerent lines. All of these authors attempted
to trace phylogenetic histories which of necessity crossed the lines of the
older classifications at right angles, and sometimes bridged over the divisions
of geologic time.

Suborder A. INTRASIPHONATA Zittel.

Family 1. Olymeniidae Gümbel,

Conchs varying from forms like Anarcestes to those that are more or less compressed in
section, and from completely discoidal to compressed and highly involute shells, the surface
heing either smooth or ivith large spines. The characteristic ventral saddles are almost
imperceptible in some primitive species, and although entire and large as a rule, are
in some genera divided by entire ventral lobes. Septa concave along the mesal plane.
Siphuncle dorsally situated. Living Chamber occupying about three-fourths of a volution ;
aperture with hyponomic sinus.

The ventral saddles are developed by the obliteration of primitive ventral lobes
and fusion of the first pair of saddles (Branco). It is at present questionable whether
the ventral lobes of some genera are secondary modifications or retentions of the
primitive ventrals, and also whether these can be regarded as divided ventrals even in
Gymaclymenia. The antisiphonal lobe is large and long, and often fused with the
siphuncular funnels. The dorsal sutures, so far as known, are very peculiar, having
only a pair of large saddles confluent with the last pair of external saddles ; or one
pair of zygous saddles, and one pair of zygous lobes, the second pair of zygous saddles
being confluent with the innermost external pair.

The Perforation tliroiigh the umbilicus, so constant in Nautiloids, is abeent, and so
too are the umbilical depressions on either side of the neck of the protoconch, common
in other Ammonoids. The forms are nevertheless ammoniticones, having the proto-
conch and other characters of the order. The first septum is described as asellate
(Branco), but is tigured as having a broad saddle on the venter.

Primitive forms similar to Anarcestes, but dift'ering in that tlie sutures have broad
entire ventral saddles and broad rounded lobes ; or if the latter are angulated, they

628

MOLLUSCA

PHYLUM VI

are incoraplete internally, rising to saddles at the lines of Involution. Siphuncle
tubulär and small, and funnels comparatively sliort (Gümbel).

1. Gyrtoclymenia (Fig. 1165), Oxyclymenia (Fig. 1167) Gümbel; Platyclymenia

Hyatt. Devonian.

Fio. 1166.

§2.

Conchs similar to tliose
of preceding genera, but sutures
liave two pairs of lateral saddles,
and tliere is a ventral lobe witli
' a median saddle.

Cymuclymenia (Fig. 1166), Sellaclymenia Gümbel. Devonian.
§ 3. Conchs difFer from preceding genera in that the sutures have deep undivided

Fig. 1165.

Suture-line of Gyrtocly-
menia laevigata (Münst.).

Butnre-line of Cymadymenüi
striata (Münst.).

Fig. 1167.

Oxyclymenia undulata (Münster).
Upper Devonian; Elbersreuth,
Fichtelgebirge.

Fig. 1168.

Gonioclymenia speciosa (Münst). Upper Devonian
Schübelhammer, Fichtelgebirge, i/o.

ventral lobes, and sometimes two pairs of lateral saddles are present. These last may
be either in part or wholly divided by marginals.

Gonioclymenia (Fig. 1168), Gycloclymenia, Discoclymenia Gümbel; Gryptoclymenia
Hyatt ; Äcanthoclymenia Hyatt. Type Ä. (Glymenia) neapolitana (Clarke). Devonian.

Suborder B. EXTRASIPHONATA Zittel.

The Extrasiphonata include straight, open-coiled and close-coiled forms, embracing
the old groups of Goniatites, Ammonites and Geratites, between which there are no
sharp lines.

The Goniatites are the oldest and most primitive Ammonoids, chiefly confined to
the Devonian and Carboniferous. They are mostly small in size, distinguished from
the Clymeniidae by their external siphuncle, and from the rest of the Ammonoidea by
their simple septa. The older Goniatites are retrosiphonate, and the aperture usually
has a ventral sinus. They grade over into Ceratites and Ammonites, the septa
becoming serrated or digitate, usually with an increase in the number of lobes, and
with the development of the forward-pointing siphonal coUars.

Family 1. Bactritidae Hyatt.

Bactriticonesi and cyrtoceracones, usually compressed ellipitical in section, and c
necting through Protohactrites ivith the Nautiloidea.

CLASS V

CEPHALOPODA

629

Bactrites Sandb. (Fig. 1169). In this, the only genus, the shell is straight,
gradually tapermg, and round or compressed elliptical in section. Devonian.

Family 2. Nautilinidae Hyatt {NauUUni Beyrich, 'pars).

Mimoceracones and
ammoniticones, rounded
in section. Body-
chamber long. Sutures
have narrow saddles on
either side of the un-
divided ventral lohe,
and hroad lateral lohes
with saddles at the lines
of involution or on the
umbilical zones, tvhen
the latter are differen-
tiated. Antisiphonal
lobe absent. Dorsiim
with a hroad azygous
saddle. Aperture with
a deep and narrow
hyponomic sinus, crests
on the ventro - lateral
angles,and hroad lateral
sinuses on either side.

Mimoceras Hyatt „ . •.

,„. , , _^s > Bactrites eleyans

{rig. 1170); Anarcestes Sandb. Upper De-
Moi'? ('Fi CT« 1171 anrl vonian ; Büdesheim,

Mojs. (^rigs. ii/i ana ^j^^j .4, Conch, i/.-
111^); ProlobitesKdiV^. b, Suture-

ß

Fig. 1169.

Fig. 1170.
Mimoceras comp^ressum (Beyr.). Lower Devonian :
Wissenbach, Nassau. A, B, Natural moulds, Vi- C
^epionic individual enlarged. '

Devonian.

line,
(after Sandberger).

Fig. 1171.

Anarcestes pleb^us (Barr.). Lower Devonian (^tage G) ;

Hlubocep, Bohemia (after Barrande).

Family 3. Aphyllitidae Frech.

Ammoniticones with truncated venters, compressed whorls and short body -Chambers.

Fig. 1172.

Anarcestes subnautilinu:
(Schloth.). Middle Devonian
Wissenbach, Nassau.

Fio. 1173.

AgoniatUes orcultus (Barr.). Lower Devonian (Etage G) ;
Hlubocep, near Prague, Bohemia (after Barrande).

Sutures similar to those of the Nautilinidae, except that a dorsal azygous lobe is sometimes
present.

630

MOLLUSCA

PHYLUM VI

Meek (Äphißlites Mojs.) (Fig. 1173); Palaeogoniatites Hyatt. Type
P. (Goniatites) lituum (Barrande). Devonian.

Paraphyllites Hyatt. Type P. {Goniatites) tahuloides (Barr.). Dorsiim of this
involute form is entirely occupied by a large azygous lobe terminating in a minute
annular lobe and partial cone similar to that observed in Nautiloids and in Pinacites.
The inner extension or cone is not present elsewhere among Ammonoids so far as
known. Devonian.

Pinacites Mojs. Highly involute, compressed ammoniticones with acute venters.
Septa biconcave, owing to a division of the lateral lobes by narrow saddles which
are connected by ridges with corresponding saddles on the dorsum. There are also
saddles at the unibilical angles and on either side of the ventral
lobes. The azygous dorsal lobe is large. Dorsum vi^ith one pair
of narrow zygous saddles and one pair of broad zygous lobes,
giving a formula of eight lobes and eight saddles. European
Devonian.

Family 4. Tornoceratidae Gürich.

Involute forms, luith ventral sinus, simple septa lihe those of
Fig. 1174, ^^^ AphylUtidae, and relatively short hody-chamhers.

Tornoceras simpiex (v. Tomoceras Hyatt (Fig. 1174), Maeneceras Hyatt (Fig. 1176).

Buch). Upper Devonian; t^ • J \ ö /» j \ b j

Büdesheim, Eifel. Devonian. ,

Family 5. Cheiloceratidae Frech.
Ammoniticones varying from discoidal and Änarcestes-like to highly involute, com-

'a^wvv^'

Fig. 1175.

Suture-line of Sporadoceras
münsteri (v. Buch).

Fig. 1176.

Suture-line of Maeneceras
terebratus (Sandb.).

Fig. 1177.

Suture - line of Aganides
sulcatus (Münster). Upper
Devonian ; Fichtelgebirge.

Fig. 1178.

Aganides rotatorius (de Koninck). Lower Carboniferous ;
Tournay, Belgium.

pressed shells with narrow venters. Shells smooth, hut with frequent labial constrictions.
Body chamler long. Aperture without hyponomic sinus.

In this family the septa are concave along the mesal plane as in Nantiloids,
becoming convex only internally and laterally, following the broad internal saddles in
the zone of Involution. Lobes and saddles entire. Primitive forms may have only

CEPHALOPODA

631

two broad saddles on either side, but more specialised sliells may have two pairs of
principal saddles fornied by division of the primitive first laterals. There is a corre-
sponding development of narrow saddles and lobes on the dorsum, but primitive forma
liave only two broad saddles here as in Änarcestes. Antisiplional lobe narrow, entire,
pointed. From this family sprang tbe Glyphioceratidae of the Carboniferous, and
through them came the Tropitidae and Arcestidae of the Triassic.

Gheiloceras Frech {Parodoceras Hyatt); Sporadoceras (Fig. 1175); Aganides Montfort
(Figs. 1177, 1178). Devonian and Carboniferous.

Family 6. Gephyroceratidae Hang.

Evolute to involute forms^ mostly laterally compressed, with short body-chamhers^ deep
ventral hyponomic sinus, and without labial constric- a

tions. This group includes forms with simple
goniatitic septa, forms with ceratitic septa, and forms
with exceedingly complex ammonitic septa.

The external sutures in primitive forms some-
times approximate to those of Änarcestes, but the
dorsals have only one large azygous lobe, the saddle
being confluent at the line of Involution with the
second external pair. In more involute forms the
antisiphonal lobe is large, entire and pointed ; there
is one pair of dorsal saddles, and one of broad
dorsal lobes ; the second pair of saddles, when
present, is confluent with the second pair of lateral
saddles,

Subfamily A. Primordialinae Hyatt
(Primordiales Beyrich).

Distinguished from Änarcestes by the divided
ventral lobes, large siphonal saddles, and especially
the first lateral saddles, which are very prominent
on the sides. Adventitious lobes and saddles are />„^fc„.„.,.„.,,„/„™<,„..^,/R„„, % TTr^r^or

Gephyroceras intumescens(iiejT.). Upper

formed by division of the first lateral saddles. Septa Devonian ; Nassau. A, Conch, i/i- -B.
in the young are concave and similar to those of " ^^^' '°^"

Änarcestes, but in later stages become convex along the mesal plane as in typical
Ammonoids. Siphuncle small, subventran, without calcareous sheath ; funnels retro-
siphonate and short, except in Manticoceras, where they are prosiphonate.

Gephyroceras (Figs. 1138, 1179), ikTavifzcoceras Hyatt; iVo6e/oceras Clarke ; Timanites
Mojs. Devonian. Nomismoceras Hyatt. Gonioloboceras Hyatt. Type G. (Goniatites)
goniolobus (Meek). Carboniferous. • Koenenites Wedekind. Devonian. (This and
related genera are described by Wedekind in Sitzher. Ges. Naturf. Freunde Berlin, 1913).

From the Gephyroceratidae probably sprang the Meekoceratidae of the Permian
and the Lower Trias, and through them came the Ceratitidae.

Fio. 1179.

Subfamily B. Beloceratinae Fi-ech.

Form compressed, discoidal, involute, with high whorls and narrow acute venters.
Lobes and saddles lanceolate, with numerous adventitious and auxiliary lobes.

Includes the genus Beloceras Hyatt (Fig. 1 1 80), of the Upper Devonian. From
the Beloceratinae probably came the Sageceratinae, the Hedenstroeminae, and the
Carnitinae, and possibly the Pinacoceratidae. Beloceras was probably derived from
Timanites with Probeloceras as a connecting link.

632

MOLLUSCA

I'HYLUM VI

Family 7. Prolecanitidae Hyatt.

The youny Uve « long undivided ventral lobe. Pnm^t^ve forms are compreesed,
discoidJ,aJmore epecialised gmera become invoUte and as^ume a ^od^fied ^^rcesjean
a^pect. Saddles aremtire in the former, but thefirst latcraU become very large and are
Jbdivided by simple marginal lohes. Lateral lobes entrre m pr^m^t^ve genera and
become bijid or trifid in specialised forms, but rarely have more nnmerous d^g^taUons.
Antüiphonal lobe entire or pointed. Siplmnele withont ealcareous sheath ; funnels pro-
siphonate so far as hnown.

yVVW^\

•^vAllnjUR/UK

Fig. 1180.

Belocerus muüüobatum (Beyrich). Upper
Devoiiian ; Adorf, Westphalia.

Fig. 1181.
Proleeanites lunulicosta (Sandb.).
Upper Devonian ; Nassau (after
Sandberger).

Subfaiiiily A. Prolecanitinäe Frech.

Shells discoidal or evolute, coiupressed or siibquadrate in section. Primitive forms
with undivided ventral lobes, and rounded saddles and lobes of the lecanitean type.
More specialised shells have entire hastate lobes and saddles, and similar but divided
ventral lobes. Aperture with well-marked hyponomic sinus. Shells smooth or
Costated, and often with longitudinal ridges.

Phenacoceras Frech ; Proleeanites Mojs. (Fig. 1181). Devonian to Garl)oniferous.

Subfamily B. Noritinae Karpinsky.

Similar to Prolecanitinäe, but the ventral lobe instead of becoming divided in the
usual way, retains the larval trifid stage throughout life in primitive species. In
specialised forms the larval siphonal saddles enlarge in the neanic stage, thus building
up a Single siphonal saddle with a comparatively large siphonal lobe. First lateral
lobes may be bifid, trifid or completely serrated in specialised shells, and the second
and other lateral lobes also may become ceratitic. The saddles, however, retain more
or less of their primitive outlines, and their bases are entire. Sutures with adventitious

CLASS V

CEPHALOPODA

633

inflections. Apertures have crests at the veiitro-lateral angles ; straight or with faint
sutures at the venter.

Pronorites Mo^s. (Figs. 1182, 1183); Triainoceras Hyatt (Fig. 1185); Farapronorites

Fic. 1184.

öepta of Gordlllerites angulatus Hyatt aud Smith.
Lower Trias ; Idaho.

Fi(i. HS

l'ronorUet>cydolohus(P\nU.).
Lower Carbonlferous ; Grass-
iugtoii, York.shire (after
Phillips).

Fig. 1188.

Septa of l'ronorites urkannasensL-
Öinith. LowerCarboiiiferous; Arkansas.
i/-' (alter J. P. Smith).

Fig. 1185.

Suture-line of Triainocaras
tuherculoso-costatum (Sandb. ). Upper
Devonian.

^^IWI*^

Fk;. 118(5.

Suture-line of Nuritea
gomlola Mojs. Muschelkalk ;
Schreyer Alp, near Hallstadt,
Anstria.

Gemm. ; Cordülerites lüyatt und Smith (Fig. 1184); (1) Amb^tes^Y'da,gen ; iVoWies Mojs.
(Fig. 1186); Daraelites Genim. Devonian to Trias.

Subfamily C. Medlicottiinae Karpinsky.

Shells compressed, discoidal and involute, with sinooth or costated
often costated or tuberculated and channelled venter.
Ventral lobe entire in primitive species, and trifid or
dividedas amoiig the primitive Noritinae inmorespecialised
forms. First lateral saddles simple but divided in primi-
tive genera, and acquire in Medlicottia through hyper-
trophy and the development of marginals extraordinary
serrated outlines. Aperture as in the Noritinae.

Sicanites Gemm.; Promedlicottia Karp.; Propina-
coceras Gemm. ; Episageceras Noetling ; Medlicottia
Waagen (Figs. 1187, 1188). Permian to Lower Trias.

sides, and

Fig. 1187.
Suture-line of Medlwottia primas Waagen. Pernio-
Carbonlferous ; Salt liange, India (afler Waagen).

Medlicottia trautsrholdi Gemm.
Pernio -Carbonlferous ; Sosio,
Sicily (after Genimellaro).

634

MOLLUSCA

PHYLUM VI

Family 8. Pinaooceratidae Mojsisovics.

Forms with involute, compressed, high whorls, with narrow and often acute venters.
Body -Chamber short. Septa goniatitic to ceratitic^ to digitale^ hut always with adventitious
and auxiliary lobes in addition to the regulär series.

The group is probably derived from the Beloceratinae, at least in so far as it is
a Unit. This is almost certainly true of the Sageceratinae and the Hedenstroeminae ;
the Carnitiiiae are probable derivatives of the Hedenstroeminae, and the Pinaco-
ceratinae apparently are derivatives from the Sageceratinae.

Subfamily A. Hedenstroemiinae Waagen.

Principal lobes and saddles with ceratitic outlines, but adventitious lobes and

___...._._,,.,— „^ saddles have Sageceras -like outlines.

HHHHH|^^^^^^^^^^^^^^^^H Antisiphonal lobe very long.

^^^^^^^^^^^^^^^^^^^^^^^^H Dorsal more complex than

1 1 RH^^HI^^^^^^^^^^^^^^^^H in preceding families. Aperture with

^ I ^m ^^^^r ^^^^^^^^^H Hedenstroemia Waagen {Glypites

■ I rW jHf ^^^^^^^H ^^aagen) (Fig. 1189); Prodromites

Tjm} ^^ ^^aS^B ^"^^*^ ^^^ Weller (Fig. 1190);

'f^m Äspenites H. and S. ; Longohardites

"^W Mojs. Carboniferous to Trias.

Fig. 1189.
Hedenstroemia kossimUi H. and S.

Lower Trias ; Idaho.

Fig. 1190.
Prodromites gorbyi Miller. Lower Carboni-
ferous ; Missouri. 1/2 (after J. P. Smith).

Subfamily B. Sageceratinae Hyatt.

Similar to the last, but lateral lobes bifid, and saddles acutely spade-shaped.
Adventitious and auxiliary lobes numerous. Antisiphonal lobe bifid. Aperture has
smuous lateral outlines with crests at the ventro-lateral ridges.

Iseudosageceras Diener (Fig. 1191); Sageceras Mojs. (Fig. 1192). Permian and
i rias.

CLASS V CEPHALOPODA 635

Subfamily C. Carnitinae Arthaber.

Form and sculpture like that of the Sageceratinae, except that in the Carnitinae
there is a tendency towards the development of ribs and knots. The septa are no

Fig. 1191.

Pseudosageceras intermontanum H. and S.
Lower Trias ; Idaho, x 3/^.

Fig. 1192.

Sagcceras haidingeri (Hauer). Upper Trias ;
Hallstadt, Austria.

Fig. 1193.

Septa of Arthaberites alexandrae Diener. Middle
Trias ; Alps (after von Arthaber).

longer lanceolate, but ceratitic or even largely digitate.
lobes is Short, but usually highly complex. This
groiip probably serves as a connecting link be-
tween the Sageceratinae and the Pinacoceratinae.

Garnites Mojs. ; Procarnites Art.; Arthaberites
Diener (Fig. 1193); LanceoUtes Hyatt and Smith;
Hauerites and Bamhanagües Mojs. ; Bosnites Hauer;
Tihetites Mojs. Trias.

Subfamily D. Pinacoceratinae Mojsisovics.
Forms thin, compressed, with acute venters.

The adventitious series of

Lobes and saddles all finely digitate. Adventitious
and auxiliary lobes numerous.

The Pinacoceratinae reach the highest degree
of complication of the septa found in any group
of Ammonites. The general plan of their septa
suggests a derivation from the Carnitinae, and
through them from either Hedenstroeminae or
Sageceratinae. It is also possible that the sub-

Pinacoceras layeri (Hauer). Upper Trias ;
Rötheistein, near Aussee, Austria.

636

MOLLUSCA

PHYLUM VI

gi-oups imder tlie Pinacoceratidae may have no near kinship with each other but
niay ratlier be inofely phylogerontic developments in different Stocks.
Pinacoceras Mois. (Figs. 1194, 1195); Placites Mojs.

AtlL EL

Pinacoceras metternichi (Hauer). Keuper ; Someraukogel, near Hallstadt, Austria.
Suture-line reduced (after Hauer).

Family 9. Glyphioceratidae Hyatt.

Form robust and involute, or evolute and trapezoidal in section. Body-chamher long.
Labial constrictions always present. Spiral ridges often present, especially on the venter.
External septa someivhat like those of the Primordialinae, but the dorsal or internal septa
have narrow saddles and an interior lateral lobe on either side of the pointed anti-
siphonal lobe.

Siphuncle sniall, and funnels generally prosiplionate. Aperture iisually with
hyponomic siniis, but some species liave ventral crests diiring ephebic stages. Shells
smootli, tuberculated or costated, but costae do not cross the venter as a rule. Venter
sonietimes with well-niarked longitudinal ridges.

This group is proba})ly descended from the Cheiloceratidae, and is the ancestral

stock of the Tropitidae and the Arcestidae,
possibly also of the Ptychitidae. Muenstero-
ceras, Gastrioceras (Figs. 1196, 1197), Glyphio-

Fiti. 1196.

Gastrioceras jossae (M. V. K.). Permo-
Carboniferous ; Artinsk, Ural.

Fig. 1197.

Ga'itrioceras (Ziade?>ui(Qoldf.).
Lower Carbon iferous Lime-
stone ; Choquier, near Liege,
Belgium.

Fig. 1198.

GlypMoccras sphaericum

(Qoldf.). Lower Carboniferous
Liniestone ; Suttrop, West-
phalia.

Fig. 1199.

Paralegoceras newsovii
Smith. Goal Measures ;

Arkansas.
Smith).

X 1/2 (after J. P.

ceras (Fig. 1198), Paralegoceras (Fig. 1199), Schistoceras Hyatt; Pericyclus Mojs.;
Pronanmtes Hang. ; Praeglyphioceras Wedekind. Devonian and Carboniferous.

Family 10. Thalassoceratidae Hyatt.
Forms robust, involute, laterally compressed. Septa from yoniatitic to ceratitic to

CLARS V

CEPHALOPODA

6?/

complex digitale, hut always with few lobes and saddles ; auxiliary series, if present,
short ; adventitious series consisting of not more than one lobe.

Fio. 1201.

Septa of Thalaasoceras
phillip.n Gemmel. Permiaii ;
Sicily (after Geminellaro).

Fio. 1202.

Septa of Ussuria waageni Hyatt and Smitli.
Lower Trias ; Idaho.

of tlie Devonian and Lower

Fig. 1200.

Dimorphoceras texanum Smith. Goal
Measures ; Texas, x i/i (after J. P. Smith).

This familj is probably derived from
Carboniferous. There is a
general resemblance to the
development of the Canii-
tinae, in tlie formation of
adventitious lobes, but
there is probably no kinship
with that group,

Dimorphoceras Hyatt
(Fig. 1200). Carboniferous.
Thalassoceras Genim. (Fig.
1201). Permian. Ussuria
Diener (Fig. 1202). Lower
Trias. Sturia Mojs. Alpine
Trias.

Family 11. Ptychitidae
Mojsisovics.

Similar in aspect to
the more robust forms of
Meelcoceratidae, but having
subacute venters, more com- Fio- 1203.

vlex SUtureS and the auxil- Ptychifes flexuosiis'M.oisi. ( = Ammo)iites studeri ümifr it.-p.). Muschelkalk;
■^ • ' • 7 . Schreyer Alp, Salzburg, Austria.

lary series straighter.

Ptychites (Fig. 1203), Japonites and Nannites Mojs.; Parannites Hyatt and Smith.

Owenites Hyatt and Smith. Trias.

638

MOLLUSCA

PHYLÜM VI

Family 12. Tropitidae Mojsisovics.

Forms usualhj robust, hut ranging from compressed-discoidal to keg-shaped. Body-
chamher long. Surface usually highly ornamented with rihs and Jcnots. Septa are
goniatitic in some reversionary genera, ceratitic in the most primitive forms known, hut
mostly slightly digitate. There are no adventitious lohes, and not more than one
auxiliary lohe.

The Tropitidae are derived from tlie gastrioceran branch of tlie Glypliioceratidae,
willi such forms as Protropites and Columhites as connecting links.

Siibfamily A. Tropitinae Mojsisovics.
Similar to the Anarcestidae in the ephebic stage, but the young frequently ha^

volutions with highly trapezoidal sections.
section of a System of longitudinal
ridges and transverse costae. Sutures
have deep, narrow ventral lobes divided
by siphonal saddles with peculiar trun-
cated bases, which are often retained in
later stages. Sutures in ephebic stages
of some forms are similar to those of
Haloritinae ; the young have a more or
less prolonged coronate stage, and are

Sliells higlily ornamented by the inter-

www*

Fig. 1204.

Margarites jokelyi (Hauer).
Upper Trias ; Sandling, near
Aussee, Austria.

Fio. 1205.

Tropites .iihlmllaiHs (ILiuer). Upper Trias
AussiM', Auslvia. l/j.

Fig. 1206.

Discotropites sandlingensis (Hauer). Upper Trias

California (after Hyatt and Smith).

trJfTt'^ ^^^■. 'l°S' n-'^'"' '^^'^ ""' ^; 1149; 1205), Paratropües [Micro-
(ropites), BarrandeHe., Szih/lhtes Mojs.; Discotropite, H. and S. (Fig. 1206). Trias.

CLASS V

CEPHALOPODA

639

Subfamily B. Haloritinae Mojsisovics.

Shells more globose and more involute in tlie young than in tlie Tropitidae, and
usually keelless, but having
similar volutions in a niimber
of species diiring later stages.
Ornament as a rule simpler
than in Tropitidae. Aper-
ture usually with ventral
crests, but these are primitive
in outline, broad, and in some
species scarcely indicated by
the lines of growth.

Halorites {Homerites),

W^->

Fic. 1207.

Juvavites subinterruptus Mojs.
Upper Trias ; California (after Hyatt
and Smith).

Fig. 1208.

Sagenites herbichi Mojs. Upper Trias ; California
(after Hyatt and Smith).

JoviteSj Parajuvavites, Juvavites (Fig. 1207), {Anatomites, Grieshachites, Dimorphites),

Miltites, Metasibirites,
Sagenites {Trachy sagenites)
Mojsisovics (Figs. 1208,
1209). Trias.

l

Fig. 1209.

Septa of Sagenites herbichi Mojs. Upper Trias ; California
(after Hyatt and Smith).

^^Wi

Fio. 1210.
Septa of Acrochordiceras hyatti
Meek. Middle Trias ; Nevada (after
Hyatt and Smith).

Subfamily C. Sibiritinae Mojsisovics.
Forms robust and highly ornamented, with strong lateral ribs and knots. Septa

640

MOLLUSCA

PHYLUM VI

ranRing from ceratitic U> moderately digitale. This group is probably the connecting
link between the Glypliioceratidae and the Haloritmae.

J^oXrtor« Hyatt (Fig. 1210) ; HtepUnite. Waagen ; S^hntes Mojs. Tnas.

Subfamily D. Celtitinae Mojsisovics.

Forms discoidal, evolute and slender in most gene.a. In primitive forms with

stron» umbüical rite, frequent constrictions and low whorls resembhng teemce,«.

'^ Septa always consistiiig ot lew iobes

I and saddles, ranging from goniatitic,

; through ceratitic, to slightly digitate.

___^ ^te Paraceltües Gemm. Permian.

IHiiP^'V W Geltites and Tropiceltites Mojs. ; Golum-

^^ 'i Wir hites Hyatt and Smith (Fig. 1211);

Proteusites Hauer ; Margarites Mojs.
, — - ^>^ Trias.

/ ' '^V V^ V^~V^^ This group is the connecting link

/». '"' ■ ' \ " «^ between Gastrioceras of the Paleozoic

and the Tropitinae of the Middle and
Upper Trias.

I

/■■ymk-^

,^'

qpirrr

Fig. 1211.

Columhites parisianus Hyatt and Smith. Lower Trias
, Idaho (after Hyatt and Smith).

Fig. 1212.

Agathiceras ciscoense Smith. Goal
Measures ; Texas (after J. P. Smith).

Family 13. Arcestidae Mojsisovics.

Forms smooth, involute, rohust, with frequent labial constrictions. Body-chamher
long. Septa ranging from goniatitic, to complex digitate, hut alvjays with a tendency
towards the multiplication of the lateral lohes, hoth external and internal. This family
is undouhtedly derived from the gastrioceran hranch of the Glyphioceratidae, hut may
he polyphyletic, inasmuch as hoth Agathiceras and Schistoceras may he radicals of
suhgroups.

Subfamily A. Pop anoce ratin ae Hyatt.

Forms very robust and involute. Septa relatively simple, ranging from goniatitic
(Agathiceras), though slightly serrated (Stacheoceras), but never becoming completely
digitate. This is the oldest and the most primitive group of the Arcestidae, and pro-
bably branched out from Schistoceras, with Stacheoceras as the connecting link.

CEPHALOPODA

C41

Agathiceras Gemin. (Fig. 1212). Carboniferoiis. Stacheoceras Gemm. (Fig. 1213).
Carboniferous and Permian. Popanoceras Hyatt (Fig. 1214). Permian, Parapopano-

iuff»w'f"fTff 1 ^

Fio. 1213.

Septa of Stacheoceras ganti Smith. Goal
Measures ; Texas (after .T. P. Smith).

fff^ffwwlf

Fig. 1214.

Popanoceras multistriatum Gemm.
Permo - Carboniferous ; Sosio, Sicily.
^/s (after Gemmellaro).

Fio. 1215.

A, Megaphyllites insectus
Mojs. Upper Trias ; Sand-
ling, near Aussee, Austria.
jB, Suture-line of M. jarlias
(Münster).

Fig. 1216.

Septa of Megaphyllites haugi Hyatt and Smith. Middh^
Trias ; California.

Fig. 1217.
LoUtes delphinocephalus (Hauer). Upper
Trias ; Sandling, near Aussee, Austria. A, B,
External aspect. ü, Median section. 1),
Suture-line, i/i.

Fig. 1218.

Lobites pisum (Münster).
Keuper (Carniolan) ; St.
Cassian, Tyrol.

ceras Hang ; Megaphyllites Mojs. (Figs. 1215, 1216). Trias ; Enrope. (?) Lobites Mojs
(Figs. 1217, 1218). Trias; Enrope.

VOL. I 2 T

642

MOLLUSCA

PHYLUM VI

Subfamily B. Cyclolobinae Zittel.

Forms as a rule mucli larger and witli more complex septa than in the Popano-
ceratinae. There is a distinct tendency towards a
phylloid development of the saddles. This subfamily
probably came from the Popanoceratinae, although the
most primitive and oldest genus assigned to the groiip,
Shumardites, almost certainly is descended directly from
Schistoceras.

Shwnardites Smith (Fig. 1219). Carboniferous. Gyclo-
lohus Waagen (Fig. 1220); Waagenoceras Gemm. (Fig.
1221). Permian.

Fio. 1219.

Septa of Shumardites simon(lM
Smith. Goal Measures ; Texas.

Subfamily C. Arcestinae
Mojsisovics.

This comprises smooth, globose,
deeply involute anarcestean forms,
discoidal only in primitive genera.
Gerontic living Chamber usually more
or less contracted laterally, becoming
sometimes subacute at the venter ; in
extreme age depressed, and truncated
or concave at the aperture. The
latter has typically in the ephebic
stage a low broad ventral crest, but
loses this in the paragerontic sub-
stage, and acquires a ventral sinus
simulating that of Paleozoic and more
primitive forms, Saddles and lobes
completely divided by more or less
complex marginals, the monophyllic
outline being completely obscured
except in the young, and in dorsal
sutures of some species. Siphonal
saddles long, and not very deeply
incised by marginal lobes. Antisi-
phonal lobe bifid or trifid, and com-
plex in specialised forms. Other
dorsals may also become quite com-
plex, and as a rule are completely
divided, although of course simpler
, . ^, than the external sutures. Dorsal

in epheWc sta e^''''''^ '''''^^^' ^^""'^ °^ ^^' Popanoceratinae. Funnels prosiphonate

Sphingites Arcestes JFigs. 1139, 1222), Stenarcestes, Proarcestes, Pa.'arcestes,
Ptycharcestes, Joanmtes (Fig. 1223), Didymites Mojs. (Fig. 1224). Trias.

Fig. 1220.

Cyclolöbus stachei Gemm. Permo-Carboniferous ;
Sosio, Sicily (after Gemmellaro).

Fig. 1221.

Septa of Waagenoceras Ulli Smith. Permian •
Texas, x 1/2 (after J. P. Smith).

Family 14. Cladiscitidae Mojsisovics.

..Jr Tli '^1 '7^7f ^' ^^'^^ '^^^^Vtly rounded ventral Shoulders and flattened

nndTrJ,n^fr' T V ^' '^^''^^^^^on of the aperture, and no labial constrictions.
Bodychamher long. Surface sp^rally striated. Lobes and saddles numerous, deeply and

CLASS V

CEPHALOPODA

643

Fio. 1222.

Arcestes intuslabiatus Mojs. Upper Trias ; Steinbergkogel, near Hallstadt, Austria.
A, B, Externa! aspect. C, Median section. D, Suture-line.

Fig. 1223.

Joannites cymhiformis Wulfen. Upper Trias ; Raschberg,
near Aiissee, Austria. Natural mciild showing the living
Chamber (after Mojsisovics).

finely divided, arranged serially.
The stems of the saddles are long
and narroiv, divided anteriorly into
two or four branches.

The shape and ornamentation
of the Shell suggest a derivation
from Agathiceras of the Carboni-
ferous and Permian, biit no con-
necting links are known.

Gladiscites Mojs. (Hypocladiscites
Mojs.) (Fig. 1225). Trias.

Family 15. Meekoceratidae
Waagen.

Gompressed discoidal and in-

Fio. 1224.

Suture-line of Didymites suhglohus
Mojs. Upper Trias ; Someraukogel,
near Hallstadt (after Mojsisovics).

volute forms. Surface nearly smooth, radial folds heing often present, but constrictions
and spines always absent. Body-chamber short Septa simple goniatitic in primitive
forms, becoming ceratitic in most genera^ but rarely reaching a digitate stage of com-
plexity in even the most specialised groups. The ventral lobe is divided in all forms ;

644

MOLLUSCA

the dorsal (antisiphonal) lohe 'is undivided in the most primitive

B

PHYLUM VI

forms, and hifid in the
more syedalised groups.

The entire family
is supposed to have
beeil derived from
Lecanites, and tlirough
tliat geiius to liave been
connected witli Nomis-
moceras of tlie Carboni-
ferous, and Gephyroceras
of the Devonian.

Fig. 1225.

Cladiftcitrs tornatus (Bronn). Upper Trias ; Steinbergkogel, near Hallstadt, Austria.
A, B, Lateral and anterior views. (', Suture-line.

Subfamily A. Lecanitinae Hyatt,

Primitive discoidal Shells like those of the Prolecanitidae, with short rounded entire
saddles and lobes like those of Prolecanites, but ventral lobes divided by short coin-
paratively broad and entire siphonal saddles. There are all
stages in the development of these saddles, so that their
aspect is rather' variable. There are as a rule but two
principal lateral saddles and lobes, with one auxiliary saddle
and shallow lobe on either side in primitive species, but in
others the number of auxiliaries may be considerably iii-
creased. Antisiphonal lobe entire, and often
long and acute. The zygous dorsal lobes are
very sliglit so far as known, and entire ;
merely marginals in the dorsal saddles.

Paralecanites Diener (Fig. 1226). Per-

iiiian and Triassic. Lecanites Mojs. ; Kyma-

tites, Parakymatites Waagen ; Proavites

eryx Arthaber; Badiotites Mojsisovics (Fig. 122V).

Trias.

Fig. 1226.

Fig. 1227.

H.

Paraleamites arnoldi
and S. Lower Trias ; Idaho
(after Hyatt and Smith).

Badiotites
(Münst.). Keui)er
St. Cassian, Tyrol.

Subfamily B. Meekoceratinae Waagen.

Shells smooth, compressed, discoidal and involute, and as a rule with narrow and
more or less flattened venter. Sutures in many forms have a tendency to extend the
inner lateral saddles or lobes, and to develop a corresponding series of auxiliaries -,
and this is carried to an excessive extent among some highly involute shells. The
ventral lobes, however, are apt to remain broad and shallow; their arms become
highly denticulated except in the Lecanitinae where they are narrow and rounded.
Saddles entire and generally somewhat elongate and linguiform, but plainly of the
Lecanites type. Antisiphonal lobe, so far as known, long, narrow and bifid. Ex-

CLASS V

CEPHALOPODA

645

tremities or dorsal sutures piodiiced and corresponding witli the inner parts of the
external sutures.

Meekoceras }iyaitt (Fig. 1228); Nicomedites Tou\a (KonincMtes) ; Clypeoceras nom.
nov. (Aspidites Waagen), of whicli the type is A^idites
süperb US Waagen ^ ; Proptychües Waagen. Triassic.

Family 16. Gymnitidae Waagen.

Smooth, compressed, discoidal shells with rounded
venter in primitive forms, hecoming involute with acute
venter in specialised species. Septa not reaching ahove
the ceratitic steige of development in most genera, hut nof
remaining in the goniatitic steige in any known genera.
Sutures in specialised groups similar in convexity and
general aspect to those of the Pinacoceratidae, hvJ
having peculiar, highly inclined auxiliaries which ar-
developed apparently from marginals on the umhilical
sides of the saddles ; no corresponding adventitious
inflections. Siphonal saddle similar to that of Meeko-
ceratidae, and arms of the ventral lohe narrow. First
lateral saddles are dependent on, or attached to the
large siphonal saddles, and often simulate adventitious
saddles.

Gymnites Mojs. (Fig. 1229); Buddhaites Diener;
Anagymnites Hyatt. Type A. {Gymnites) lamarcki (Diener),
Type P. (Plac.) sakuntala (Mojs.). Trias.

Xenodiscus and Xenaspis Waagen. Permian and Trias. Ophiceras Griesbach (Fig.
1230). Trias. Flemingites Waagen (Fig. 1231).
Trias. Japonites Mojs. Trias. Europe and Asia.

The Gymnitidae are commonly regarded as a
subfamily under the Ptychitidae, but they are

Meekoceras
Lower Trias ;
Hyatt and Smith).

Fig. 1228.

muslibachanum, White.
Idaho. X 1/2 (after

Paragymnites Hyatt.

Fig. 1229.

Gymnites palmai Mojs. Muschelkalk
Schreyer Alp, near Oosau, Austria.

Ophiceras jacksoni H. and S. I.ower Trias
Idaho (after Hyatt and Smith).

more probably an offshoot from the Lecanitinae, and through them from the
Gephyroceratidae.
1 The nairie Aspidites was preoccupied when Waagen usecl it, and a new one becomes necessary.

646

MOLLUSCA

PHYLUM VI

Family 17. Hungaritidae Diener.
Form involute, laterally compressed, with keeled venter. Surface often ornamented

Idaho 1/2 (after Hyatt and Smith),

\>

Fig. 1232.

Inyoites oweni H. and S. Lower Trias ; California
(after Hyatt and Smith).

with folds, rihs or hnots. Body
Chamber short. Septa usually cera-
titic, not reaching the digitate stage
in any genera, hut persisting in the
goniatitic stage in Beneckeia.

This group is not regarded as
a side branch from the Meekoce-
ratidae, but as an old and persistent
stock, Coming down with little modification from the Gephyroceratidae, probably
from the keeled form Timanites. The Hungaritidae have been confused with the
group of keeled Geratites, and also with compressed members of the Tropitidae, but
the resemblance is one of convergence, and bespeaks no near relationship.

Hungarites Mojs. ; Otoceras Griesbach. Permian and Trias. Beneckeia Mojs. ;
Inyoites Hyatt and Smith (Fig. 1232); Dalmatites Kittl. Permian and Trias.
Eutomoceras Hyatt {Halilucites Diener). Trias.

Family 18. Ceratitidae Mojsisovics.

Forms evolute to involute^ laterally compressed to robust and rounded. Surface
usually ornamented with folds, ribs, knots, spines or tubercles. Venter in some genera
provided with a keel, in others with a median furrow ; and occasionally biangidar. Body
Chamber rather short. Septa ranging from the goniatitic stage in some arrested or re-
versionary forms, through the typical ceratitic stage, to complex digitation.

This family may be, and probably is, polyphyletic, but a large part of it, including
the typical Geratites, seems to have been derived from Meekoceras or from some member
of that group. Only the more primitive members of Geratites show a youthful stage
similar to Meekoceras, but there seems to be a perfect intergradation between the more
complex species of Meekoceras and the more primitive species of Geratites.

Subfamily A. Ceratitinae Mojsisovics.

Primitive forms are discoidal or involute, but stout-whorled and keelless, becoming
more compressed, and having a broad, slightly elevated median ventral ridge in more
specialised genera. Sides have at least one line of nodes in primitive forms, and are more

CLASS V

CEPHALOPODA

647

Ol" less conii)letely costated witli several lines of tabercles in specialised shells. Sutures
in thc young and in primitive genera liave a magnosellarian aspect, but when the broad
internal saddles beconie divided, the internal inflections resemble those of Lecanitinae.

Fio. 1233.

Cemtitesnodomsdenmn. Muschelkalk; Wurzburg, Bavaria. yl, 7?, Conch, Vi- a Lcfthalf of suture-line.
D, First and second lateral saddles and auxiliaries to left of line of Involution (n); half of dorsal suture-lina to
right. (äL, Antisiphonal lobe ; other lettering as in Figs. 1145, 1146.)

In primitive forms (OleniMtes) the saddles are broad and very shallow ; lobes entire,
and ventral lobe divided by a larviform siphonal saddle, which is sometimes entire.

The large nodes and stout volutions of primitive
forms indicate parallelism with Stephanites. Saddles
and lobes have the typical ceratitic outlines, as a rule,
but in some forms the auxiliary line may be extended as
in the Meekoceratinae. Occasionally, also, costae may cross
the venter as in Sibiritinae.

Geratites de Haan (Figs. 1233, 1234) ; Danuhites and
Balatonites Mojs. ; Reiflincßtes Arthab. Gymnotoceras and
Olenikites Hyatt. Type 0. {Bin.) sjnniplicatus (Mojs.).
Keyserlingites Hyatt. Type K. (Geratites) subrobustus
Mojs. Beyrichites Waagen. Siibgenera : Hollandites and
Phülippites Diener. Trias.

Subfamily B. Tirolitinae Mojsisovics (pars).

Fig. 1234.

Cemtitrs (rinodosus Hauer. Mus-

Compressed, discoidal or involute shells reseml)ling chelkalk; Bakony, Hungary (after

Dinaritinae in thoir sutures and having entire saddles ' «J^'^omcs).

and slightly denticulated lobes. Ventral lobe may remain entire until a late stage

in some forms, but as a rule it is divided, and the siphonal saddle is small and often

648 MOLLUSCA thylüm vi

entire. Shells have a line of nodes on the ventro-lateral angles, and the venter is

invariably smooth and convex.

Includes Tirolües (Fig. 1235) and MetatiroUtes Mojs., froni tlie Alpine Trias and
froiii Idaho. The siibfamily of Clydonitinae has siitnres
similar to Tirolües, biit costae interriipted on the venter,
which is often channelled. Includes Gkjdonites and Eremites
Hauer ; and Ectolcites Mojs. Trias.

Subfamily C. Dinaritinae Mojsisovics ^pars).

Sutures resembling Tirolües in having only two broad
saddles, one pair of first lateral lobes, and inconiplete lobes
at the umbilicus. Shells smooth, or with coarse folds
most prominent at the umbilical Shoulders ; sides more or
less flattened or planoconvex, and venter rounded.

Dinarites Mojs. ; Cuccoceras Diener. Trias.

Subfamily D. Buchitinae Hyatt.

Primitive forms similar to Celtitinae, with smooth
elevated venter ; more specialised shells with slight keel on
Tirolües cassianus (Quenst.) the narrow venter, and simple costae or folds on the sides.
Lower Trias ; Grones-Hof, near Sutures have entire outlines, or lobes but slightly denti-

st Cassian Tvrol. o ./

culated ; and when the saddles are completely divided
their marginals are small. Sutures otherwise similar to those of Dinaritinae, and the
young have a Dinarites stage. Antisiphonal lobe entire and bifid in some forms.
Buchües, Helictites, Phormedites, Parathishites and Glyphidites Mojs. Trias.

Fig. 1235.

Subfamily E. Arpaditinae Hyatt.

Differs from the Buchitinae in the tendency to form channelled venters bordered
by two ridges, which may be either tuberculose or smooth.

Ärpadües (Fig. 1236), Klipsteinia, Dütmarites, Muensterües, Steinmannües, Dafli-
nües, Dionites, Brepanües, Heraclües, Guemhelües,
Cyrtopleurües and Acanthinites Mojs. Trias.

Subfamily F. Trachyceratinae Hyatt.

Discoidal and involute shells with well-defined and
often profusely tuberculated costations which are
interrupted on the ventral aspect by a smooth zone
or Channel. This may in some specialised forms
becorae a d istin et Channel bordered by tuberculated
ridges. Lobes and saddles completely divided by
marginals, but these do not become very long nor
complex.

Distichites, Trachyceras (Fig. 1237), Protrachyceras (Fig. 1238), AnolcÜes, Sand-
hngites, Siremtes, Anasirenites, DiplosirenÜes and Glionües Mois. (Figs 1239, 1240).
Trias. (?) Hesperites Pompeckj. Rhaetic.

Subfamily G. Choristoceratinae Hyatt.
Discoidal ammoniticones in primitive forms, becoming uncoiled phylogerons, and
finally even complete baculiticones in the most specialised species. Sutures also

Arpadites cinensis Mojs. Keuper
Esino, Lombardy.

CLASS V

CEPHALOPODA

649

phylogerontic, liaviiig oiily six entire or vciy faintly denticulated lobes, and six
entire saddles. Ventral lobe divided, and tlie antisiphonal either entire or bifid at

Fig. 1237.

Trachycerasaustriacum Mojs. Upper Trias ;
Rötheistein, near Aiis.see, Austria.

Fig. 1238.

Protrachyceras archelaus Laube. Upper Trias (Norian) ;
Bakony, Hungary (after Mqjsisovics). 1/2-

Fig. 1239.

(Jlionites fairhanksi H. and S. Upper Trias ;

California (after Hyatt and Smith).

Fig. 1240.
Septa of Clionites fairbanlcsi H. and S. x 1/2-

./Vr^y-

Fig. 1241.

Polycydus nastur-
tium (Dittmar).
Keuper ; Sandling,
near Aussee.

FiO. 1242.

Choristoceras marshi
Hauer. Rhaetic ; Kendel-
engraben am Osterhorn,
near Salzburg.

its extremity. Dorsal lobes and saddles otherwise entire. Connected through
Polycydus with Buchites, according to Mojsisovics.

Polycydus (Fig. 1241), Peripleurites Mojs.; Choristoceras (Fig. 1242), Rhahdoceras
Hauer (Fig. 1243). Trias.

650

MOLLUSCA

PHYLUM VI

/iW^K

Siibfamily H. Cochloceratinae Hyatt.

Turriliticones vvith costae similar to those of the preceding groiip, but more or less

asymmetrical in conseqiience of the asymmetry
of the spires. Lobes reduced to foiir in niimber,
and there are other phylogerontic suppressions,
Funnels monochoanitic, collars absent.

Gochloceras Hauer (Fig. 1244) ; Paracochloceras
Mojs. Trias.

Family 19. Phylloceratidae Zittel.

Fig. 1243.

RhaJ)doceras suessi
Hauer. Keuper ;
Sandling, near
Aussee (after
Hauer).

Shells smooth, wiih radial Striae or weak folds.
Form compressed, with rounded venters. Body
,, " , - ,,. Chamber tahing up one-half to three-fourths of the

Hauer. Sandling, last volution. Aperture simple, with short ventral
Hauer)."^'"'^^ ^^ crest. Lohes and saddles numerous, decreasing in
size towards the umhilicus. In primitive genera the
have monophyllic bases resembling those of the Popanoceratinae, but in the more
specialised groups only the marginal saddles retain the rounded outline, the others
becoming deeply divided, although always remaining phylloid in termination.

Monophyllites is the oldest and most primitive of the Phylloceratidae, and

fffP

V^-;

Fic. 1:^45.

Mouüphyliitcs dmonyi (Hauer). Upper Trias

Rötheistein, near Aussee, Austria.

Fig. 1246.

Monophyllites hillingsicmns Gabb.
Middle Trias ; Nevada (after Hyatt
and Smith).

probably connects the family with Nomismoceras or some other derivative of the
Gephyroceratidae. The resemblance of Phylloceras to the Permian Arcestidae is
purely one of convergence, for neither the young of Phylloceras nor the adiilts of
Monophyllites resemble any genera of the Arcestidae. But the young of Phylloceras are
like adult Monophyllites, and the young of Discophyllites are at first like Nomismoceras,
and the adolescent stages like Monophyllites. The developnient of Monophyllites
itself has not yet been studied.

CLASS V

CEPHALOPODA

651

The fainily of tlie Phylloceratidae is tlie most persistent and the longest-lived
aniong the Amnionoids, being continuoiis from the Permian to the Upper Cretaceous.

Subfaniily A. Monophyllitinae Smith.

Sliells compressed, discoidal, evolute. Septa with primitive monopliyllic saddles,
and more regulär in the relative size of the lobes and saddles than the succeeding
group. Antisiphonal lobe bifid, but otherwise entire. MonophylUtes Mojs. (Figs
1245, 1246) {Mojsvarites Pompeckj); Discophijllites Hyatt (type Lytoceras patens Mojs.).
Triassic. Discophyllites forms a connecting link with the Phylloceratinae, and might
with eqiial propriety have been classed with that group.

Subfamily B. Phylloceratinae Zittel.
Form usually involute. Septa very complex, with the saddles deeply digitate,

Fio. 1248,

l'hylloceras heterophyllum (Sowb.). Upper
Lias ; Whitby, Yorksliire.

Fhyüoceras ptychoicum (Quenstedt). Tithonian ; Stranibei^,
Moravia. AL, Antisiphonal lobe.

652

MOLLUSCA

PHYLUM VI

but retaining the phylloid ending, and witli the marginal saddles retaining the
monophyllic outlines. Antisiplional lobe with entire sides, or with only one pair of
lateral branclies, and extremities bifid.

Rhacophyllites Zittel (Fig. 1247); EitphylUtes Wähner ; Phylloceras Suess (Figs.

ifi a5 «•* a3 a2 ai l

Fio, 1250.

Suture-line of Phylloceras nüssoni (Heb.),
Upper Lias.
SL, Ventral or slphonal lobe ; L, First, and l, Second lateral lobes

Fig. 1251.

l Li AL

Sutiire-line of Sowerhiceras tortisulcatum (d'Orb.)
(after Quenstedt).

^ ^ ai - 6, Inner or .so-called auxiliary lobes ;

ri^Line of'involution ; Li,' Second dorsal lobe ; AL, Antisiphonal lobe.

1140, 1248-1250) ; Sowerhiceras Paroni and Bon. (Fig. 1251) ; Dasijceras Hyatt. Type
D. (Phylloceras) rakosense (Herbicb). Schistophylloceras Hyatt. Type S. (Phylloceras)
aulonotum (Herbich). Geyeroceras Hyatt. Type G. (Phyll.) cylindricum (Geyer).
Trarjophylloceras Hyatt. Type T. (Phylloceras) heterophyllus-numismalis (Qiienst.).
Meneghiniceras Hyatt. Type M. (Phylloceras) lariense (Menegh.). Trias to Cretaceous.

Family 20. Lytoceratidae Neumayr.

Shell widely umhilicate, sometimes forming a hose or snail-like spiral, sometimes
even hook-shaped. Body chamher two-thirds to three-fourths of the last volution. Aperture
rounded, whorls little emhracing. Surface often ornamented ivith simple rihs or rows
of knots. Septa deeply divided, with usually tvjo lateral lohes and an auxiliary. The
first and often the second lateral lohes and saddles are deeply hifid.

In all probability the family Lytoceratidae is not monophyletic, some of the
Scaphites and other degenerate groups Coming from different Stocks. The Lytoceratinae,
however, appear to be monophyletic, and to liave been derived from Monophyllites.

Subfamily A. Lytoceratinae Mojsisovics (pars).

Incliides only closely coiled, discoidal and involute shells with somewhat prominent,
often crenulated, transverse bands of growth. Antisiphonal
lobe with two long internal branches bending inwards and
attached to surfaces of the septa. Siphonal lobe short
like that of Phylloceras, and siphonal saddles narrow. The
first lateral saddles small and short, the first lateral lobes
much longer than the ventral. Eeduction of lobes along
the line of Involution is such that there are commonly
only six to eight in fuU-grown shells.

Lytoceras Suess (Thysanoceras Hyatt) (Figs. 1252,
1253). Jura and Cretaceous. Älocolytoceras Hyatt (Fig.
1254). Type Ä. (Amm.) germainei (d'Orb.). Pleurolytoceras
Lytocera.^fimbriaium{Sovfh.). Hyatt. Type P. (Amm.) hircinum (Schloth.). Jura.

Middle Lias ; Würtemberg. m, u xr j. n i ^

Cross-section (cf. Fig. 1148). ^ eiragonites Kossmat ; Gaudryceras Grossouvre. Cretaceous.

Subfamily B. Macro8Caphitinae Hyatt.
Symmetrical, closely coiled, discoidal ammoniticones during \oimg stages (and
persistently so in primitive forms), but becoming uncoiled in gerontic stages or earlier

CEPHALOPODA

653

1253.

Lytoceras liebicji (Oppel). Tithonian
Straraberg, Moravia.

in tlie ontogeny of phylogerontic forms,
and fmally straight in some genera.
Antisiphonal lobe sliort, and in some
genera trifid. Shells have constrictions
and large costae at intervals, but no
tubercles at any stage.

Macroscaphites Meek (Fig. 1255) ;
Leptoceras, Costidiscus Ulilig ; Tropaeiim
Sowb. ; Hamites Parkinson (Fig. 1256);
Ptyclwceras d'Orb. (Fig. 1257); Di-pty-

i^tin

Fig. 1254.

Alocolytoceras germainei (d'Orb.).
Upper Lias ; Pinperdu, near
Salins, Jura

Fic. 12Ö5.

Macroscaphites ivanii (d'Orb.).
Upper Neocomian ; Malleuewitz,
Carpathia.

Fio. 1256.

Hamites rotundatus (Sowb.).

Gault ; Folkestone.

Fic. 1257.

Ptychoceras puzo-
sianum (d'Orb.).
Barremian ; Vergons,
Basses Alpes.

654

MOLLUSCA

PHYLUM VI

choceras Gabb

Fig. 1258.

A, Baculites anceps Lam. B, B. faujasi
Lam. Upper Cretaceous ; Maestricht. t

Fig. 1259.

Suture-line of Diplomoceras cylindraceum
Defr. Uppermost Cretaceous ; Tresville,
Manche.

Oyrtochilus Meek {Scipionoceras Hyatt) ; Baculites Lam. (Fig. 1258).

Diplomoceras Hyatt (Fig.

1259). Type D. (Harn.) cylin-

ß draceum, (d'Orb.). Hamulina

d'Orb. (Fig. 1260, A). Cre-
taceous. Baculina d'Orb.
Juras.

Subfamily C. Turrilitinae
Hyatt {pars).

A heterogeneous group
of turret-shaped cones, with
Shells highly ornamented
witb ribs and tubercles. In
Turrilites the spire is sym-
metrical and close-coiled ; in
most other forms it is un-
symmetrical, and niore or less
open. The relationship of
this group to the Lytocera-
tidae is extremely problema-
tical.

Turrilites Lamarck. (Fig.
1261); Heteroceras d'Orb.
(Fig. 1262); Emperoceras
Hyatt ; Helicoceras d'Orb.
Cretaceous.

Fig. 1260.

A, Hamulina subcylin-
drica (d'Orb.). B, Suture-
line of A. lorioli (Uhlig).
Neocomian ; Angles, Basses
Alpes (after Uhlig).

Family 21. Aegoceratidae Neumayr.

Form discoidal, mostly widely umbilicate. Whorls
smooth, or with straight radial rihs that occasionally
hifurcate at the venter. Aper-
ture without lateral ears.
Venter with keel, or with for-
ward pointing crest. Body
Chamber comprising from
three-fourths to more thart, a
complete revolution. Suture
line not deeply digitale ;
usually with only two lateral
lobes and an auxiliary.

Subfamily A. Psilocera-
TiNAE Zittel.

Widely umbilicate,
whorls laterally compressed,
smooth or with simple ribs
whicli do not cross tlie fig. 1261.

rounded keelless venter.

The Psiloceratinae are

Fig. 1262.

GlnU^viiZJV''''''^''' "^'P""^- Heteroceras polyplomim (Roemer).
d'Orbigny). ' """ ^ Upper Cretaceouf ; Haldem, West-

CLASS V

CEPHALOPODA

6^

commonly supposed to have beeii tlie progenitors of all the other Aegoceratidae.

It is, however, just as likely tliat they are a degenerate groiip, reversioiiary towards

the ancestral radical. Tliey have a certain re-

semblance to Monophyllites, which has given rise h^f^^iS'^^

to the idea that they may be an offshoot from the r\ ^ ^,.v— w ;

Phylloceratidae. This too is improbable, the re-

semblance being most likely a convergence pheno-

menon.

Psiloceras Hyatt (Fig. 1263); Tmaegoceras
Hyatt. Lias.

Subfamily B. Arietitinae Zittel.

Veiiter with strong keel. Form evolute, volu-

tions of discoidal forms more quadrate than in

j)recediiig faniilies, and often with a channelled

venter. Costae more strongly developed as a rule,

and with prominent ventro- lateral angles, which

are sometimes tuberculated. Sutural inflections

reduced in number and complexity as compared

with preceding families, and phylliform marginals

replaced by saddles of more irregulär aspect.

Ventral lobe long and narrow, with corresponding

siphonal saddle. Usually only two pairs of large lateral saddles, the second often

the most prominent. First pair of lateral lobes large, second and third pairs snccessively

smaller ; third and fourtli pairs of saddles also smaller, the last often partially on

the line of Involution. Antisiphonal lobe
bifid, very long, and sometimes complex.
One pair of large dorsal saddles, and one of
short, often incomplete lobes. Anapytchus
observed in several species.

There are two types of young in the Arieti-
• tinae, which afterwards beconie separated in
other related groups : a broad depressed or
coronate type occurs in typical Arietitcs and
some others, and the conipressed Psiloceran
type in Arnioceras, etc. Pseudotropites shows
that Coeloceras may have originated from
the Arietinae through persistent develop-
ment of a trapezoidal form of young with
correlative changes. Arietites Waagen (Figs.
1264, 1265).

Subgenera : Vermiceras, Corojiiceras {Fig.
^*'* * ^ IIAQ), Arnioceras, Discoceras, Asterocei'as, &Tid

Arietites bisnlcatus Brug. Lower Lias ; COte d'Or Ovhioceras Hvatt Lias
(after d'Orbigny). ^ J • '

Psiloceras planorhis (Sowb.)- Infra-
Lias ; Bebenhausen, Würtemberg. Ana-
ptychus in living Chamber.

Subfamily C. Aegoce ratin ae Zittel.

Form widely umbilicate. Whorls with lateral ribs which frequently either divided
or undivided extend across the keelless venter. Under this subfamily are two groups
of genera, the first being that of Äegoceras Waagen which Hyatt has called the " Liparo-
ceratidae." In this the volutions remain rounded in section and frequently retain a
primitive discoidal aspect. Costae almost entirely disappear on the venter of some
forms, but form very large continuous folds in others. Sutures become excessively
complex, saddles narrow and deeply cut by complex marginals, and ventral lobe corre-
sponds, but usually of about equal length with the lateral lobes. Antisiphonal bifid,

656

MOLLUSCA

PHYLUM VI

and resembles (as do also the two dorsal saddles and small dorsal lobes) tliose of
tlie Arietitinae.

7..S-1 7.,S'" '"' !■

IL

Fior 1265.

Arütites Hsulcatus Brug. Lower Lias ; Würtemburg. A, Suture line ; B, (\ Portion of volution seen froiu

the lateral and ventral aspects.

Äegoceras Waagen (Fig. 1266)
Hyatt has proposed tlie following
snbgenera : Liparoceras, Microdero-
ceras and Ändrogynoceras. Lower and
Middle Lias.

The second group is tliat of Schlo-
theimia Bayle, called by Hyatt the
" Angulatidae." This includes more
or less compressed and costated shells,
the costae sometimes crossing the
venter in the young or extreme age,
but usually interrupted in the adult
by a smooth and occasionally sunken
median zone. Sutures inclined apicad
near lines of involution, more com-
plex in outline than in typical Ärie-
tites, and with phylliform marginals
Ventral lobe broader and shorter, with larger siphonal

Fig. 1266.

•ö mpricornus (Schloth.). Middle Lias
Gmünd, Würteniberg.

more like tliose of Psilocen

CEPHALOPODA

G57

saddles tlian Arietües, and antisiphonal lobe bifid, longer and more coniplex. First
pair of doi-sal saddles large and long, otlier
dorsal inflections variable, l)ut generally more
niinierous tlian in Arietües.

Schlotheimia Bayle (Fig. 1267); Waeh-
neroceras Hyatt. Lower Lias.

Subfamily D. Polymorphinae Hang.

Shells compressed discoidal, with smooth
young like tliose of Psüoceras. Costae apt
to be inclined or slightly signiöidal, and
continuous across the venter. Tliis is crenu-
lated in primitive forms, biit becomes smooth,
Channelled or keeled in specialised shells.
The latter have sutures similar to those of
Schlotheimia, biit less complex.

Agassiceras Hyatt {Paroniceras Bonar. ;
Gymhites Neumayr ; Amm. glohosum Opp. ;
Amm. miserabile Quenst.). Liparoceras Hyatt {Ammonites bechei Sow.) ; Polymorphites
Sutner ; Dumortieria Hang ; Amphiceras Gemm. Lias.

1267.

Schlotheimia angulata (Schloth.). Lower Lias ;
Göppingen, Würteniberg.

Family 22. Harpoceratidae Neumayr.

Discoidal and involute shells, with sigmoidal costae. Venter with smooth or crenuloAed
keel. Ayerture with curved sides or with projecting lateral ears, and rounded ventral
crest. Septa simply digitale, ivith the lobes and saddles arranged in a straight line, and
usually with several auxiliary lobes.

This family, which probably originated from the Arietitinae, ranges from the
Lias to the Lower Cretaceous.

Subfamily A. Harpoce ratin ae Zittel.
Discoidal involute shells with sigmoidal costae separated throughout or confluent

Hildoceras bifrons (Brug.)- Upper Lias ;
Whitby, Yorkshire.

Lioceras opalinnm (Rein.). Lower Dogger ;
Teufelsloch, near BoU, Wiirtemberg.

on the median lateral line, and sometimes bifurcated externally. Nodes never präsent,
VOL. I 2 U

658

MOLLUSCA

PHYLUM VI

although prominent crescentic ridges may arise on the sides tlirough confluence of
costae. The latter are straiglit in i^rimitive Catulloceras, wliich resenibles Caloceras

in aspect. Discoidal forms often both
keeled and channelled on the venter, and
sometimes have broad furrows on the
sides. Specialised invohite shells have
solid keels, bnt iisually no Channels, and
lateral zones often become smootli. Sutures
comparatively simple, and in discoidal
forms are similar to those of Ärnioceras,
biit more complex in highly involute
forms,

Harpoceras Waagen, and subgenera :
Hildoceras (Fig. 1268), Lioceras (Fig.
1269), Grammoceras Hyatt (Fig. 1270);
Gatulloceras Gemm. ; Arietieras Seg. ;
Hyperlioceras, Graphoceras, Brasilia and
Darellia Buckman. Upper Lias and In-
ferior Oolite.

Poecilomorphus, Huddlestonia^
Brodieia, Gosmogyria, Welschia Buckman ;
Ludwigia Bayle, These are also subgenera from the Inferior Oolite.

Fio. 1270.

Harpoceras Grammoceras thouarsensi d'Orb. Upper
Lias ; Heiningen, Würtemberg.

Subfamily B. Oppeliinae Hang.

Discoidal and highly involute shells with sutures, form and markings in primitive
species that show affinity with Harpoceran stock, and apparent derivation from Poecilo-
morphus through typical Oecotraustes. Costae highly flexed and sometimes fused, but
no well-marked lateral Channels as in hollow-keeled groups. Venter often truncated
and sides flattened, except in primitive species. The keel
may become very prominent, and fiUed with shell layers,
but never hoUow. It disappears on the body Chamber.
Aperture with ventral crest. The sigmoidal ribs often end
in marginal knots. Septa finely digitate. This subfamily
ranges from the Middle Jura to the Cretaceous, its maximum
falling in the Upper Jura. Typical genera are Oppelia
Waagen (Figs. 1155, 1157, and 1158), and Oecotraustes
Waagen (Fig. 1271). A revision of the group has recently
been published by Douville (1913). p^^, ^271.

Oppelia has been subdivided into a large number of oecotraustes macrotelns
groups, or transitional series (" Formenreihe "), some of which (^ppei). Tithonian ; stram-
might even take rank as subfamilies, but most of them ^^^'
are hardly more than subgenera. The largest group, which Hyatt distinguished
under the name " Glochiceratidae," includes discoidal and involute
Shells, smooth in primitive species, but acquiring highly inflected
costations, sometimes with two rows of tubercles on the sides, and
a median ventral row that may fuse into a continuous solid keel.
One line of ventral tubercles may also arise directly from folds that
appear in otherwise unornamented shells. Aperture sometimes
with long lateral lappets. Sutures similar to those in the Haplo-
ceratidae.

Gadomoceras, Creiiiceras, Mun.-Chalm. (Fig. 1272); Phlycticeras
{Lophoceras Bonar.) ; Ochetoceras Hang (Fig. 1273); Gy macer as
Quenst. (emend. Hyatt). Type G. (Ammonites) guemheli (Opp.). Strigoceras Quenst.

Fig. 1272.
Creniceraa renggcri
(Oppel). Oxford i an ;
Salins, Jura.

CLASS V

CEPHALOPODA

659

(Buckman); StrehUtes Hyatt (Fig. 1274). Type S. (Ämmonites) iiidus-costatus
(Quenst.). Glochiceras Hyatt. Middle and Upper Jura.

Another group, which Hyatt called " Distichioceratidae," includes the genera

1273.

Ochetoceras flexuosum (v. Buch). Upper
Jura (jS) ; Laufen, Würtemberg.

Fig. 1274.

StreUites tenuilöbatus (Oppel). Upper Jura

Pappenheim, Bavaria.

Horioceras and Distichoceras Munier-Chalmas, witli septa simpler than in GlochiceraS)
owing to arrested development. The yoimg of Distichoceras repeat the characteristic
form and costae of Glochiceras^ with smooth venter and lateral tubercles and then
acqiiire the featiires of Horioceras before the
median continuoiis keel of Distichoceras arises.

Family 23. Amaltheidae Fischer (pars).

Form laterally compressed, usnally involute,
high whorled. Sides with gently curved ribs or
folds, and often with lateral knots or spiral
lines. Venter keeled, and the keel is often
crenulated by ribs or thickened growth lines.
Aperture simple, or with narrow ventral crest.
Sutures deeply digitate with several auxiliary
lobes.

Subfamily A. Amaltheinäe Hyatt.

Discoidal and involute shells, the young of
which have fold-like costae rising into heavy
nodes just inside the lines of involution. Costae
became prominent and sharp at the umbilical

Pio. 127

AmaWieus margaritatus Montf. Middle
■Uli 1 j. 1 i. 1 1 j 4. ^'*^ ' Würtemberg. Living Chamber broken

Shoulders and ventro- lateral angles, and true away and exposing " wrinkied layer " on
tubercles appear in some groups. Venter keeled IT^^^} f"^^^?,"-, V^^^Jl^ homoiogous witii the

T 11 , 11^ Till olack layer of Nautilus.

and sulcated m discoidal forms, the keels alone

persisting in more involute species. Keel solid and crenulated by the passage of costae
or folds across the venter. Anaptychus present. Nodes prominent in the young of
primitive species ; costae with only one row of tubercles in later stages or none ; keel
invariably present and crenulated. Amaltheus Montf. (Figs. 1 150 ; 1160, ^ ; 1275) ;
Paltopleuroceras Buckm. {Pleuroceras Hyatt). Middle Lias.

660

MOLLUSCA

PHYLÜM VI

In another group of tlie Amaltlieinae, tlie yonng usually have gibbous volutions witli
a Single row of nodes, wliich eitlier persist, or are followed by a bispinous stage, and

inner ends of tlie sliort costae also become
tuberculated. Venter smootli at first, and
niay remain so or may have a solid keel.
Costae Single, and usually bend at ventro-
lateral angles toward the keel, but do not
cross the venter except in late stage of
Pseudotropites. Haplopleuroceras and
Borsetensia Buckm. ; Pseudotropites
Canav. ; Ganavarites Hyatt. Type C.
(Ärietites) discretum (Canav.). Lias to
Inferior Oolite.

The Amaltheinae are usually classed
as derivatives from the Arietitinae, but
this is doubtful. Oxynoticeras Hyatt
(Fig. 1276) from the Lias, is classed by
most writers with the Amaltheidae,
although Hyatt regarded it as a member
of the Arietitinae. In this genus the
Shells are compressed and more involute than in the Arietidae, with narrower and
more acute keeled venter, but no ventral Channels. Sutures have extended and
highly modified auxiliary inflections ; keel hollow in adult of some species. Lower Lias.

Fio. 1276.

OxynoHce.ras oxynotum (Quenst.).
(ß) ; Würtemberg.

Lower Lias.

Subfamily B. Hammatoceratinae Buckman.

Discoidal forms with Single or bifurcated costae, keeled and often channelled
Young similar to those of the Harpo-
ceratinae in compressed forms. Keel
hollow.

Cycloceras and Hammatoceras Hyatt ;
Lillia Bayle ; Haugia^ Polyplectus, Chart-
ronia, Benchmannia Buckm. ; Zurcheria
Douville.

Upper Lias and Inferior Oolite.

The Hammatoceratinae have usually
been classed as near relatives of the
Arietitinae but their systematic position
should probably be in the Amaltheidae,
with which they sliow near affinities in
form and septation.

Buckman placed two genera or sub-
genera of this subfamily in a separate
group " Sonniniinae." Sonninia includes
discoidal forms with a keeled but not
Channelled venter, and sides with coarse
bifurcated* costae diverging from a row
of nodes along the median line of the
rounded sides and continued internally
by Single costae. WitchelUa has nodes
only in the young, and costae become
Single or only slightly confluent. Sonninia Bayle {Waagenia Bayle) (Fig,
WitchelUa Buckman. Inferior Oolite.

venters.

1277.

Sonninia sowerhyi (Miller). Middle Dogger
(after Steinmann and Döderlein).

Lorraine

1277);

CLASS V

CEPHALOPODA

661

Family 24. Haploceratidae Zittel.

Shell smooth, with fine fjrowth lines, ivühout constrictions. Venter rounded, vnthout
Jceel. Apertures with lateral ears or lappets. Septa deeply digitale.

This family is supposed to be an off-shoot from the Harpoceratidae, and nearly
related to Oppelia.

Haploceras Zittel
(Lissoceras Bayle) (Fig.
1278). From Middle Jura
to Lower Cretaceous.

Family 25. Stephano-
ceratidae Neiimayr.

Forms usually robust
and inclined to be coronate,
at least in youth. Surface
with bifurcating ribs that
extend across the rounded
venter. Aperture with
lateral ears or lappets^
and usually constricted.
Septa deeply digitate, with
tivo lateral lobes and two
or three auxiliaries. Keel
present in some genera.

The Stephanocera-
tidae were derived from the

Fi(i. 127!t.

.1, Coelm-eran suharinalum (Youiig).
Whitby, Yorkshir«. B, Suture-liiie of
Coeloceras pettos Quenst. Middle Lias.

Fig. 1278.
Haploceras eUmatum (Oppel). Tithonian ; Strainberg, Moravia.

Aegoceratidae of the Lias, and in turn gave rise to
most of the Ammonite families of the later Jurassic
and Cretaceous, so much so that it might be well to
include these and their descendants in a superfamily,
or suborder Stephanoceratoidea.

The group has been subdivided into numerous so-
called families, most of which, in so far as they are
deserving of recognition at all, are here treated as
subfamilies, for the sake of uniformity in Classifica-
tion. It is not meant to imply by this that they
all have equal taxonomic rank.

Subfamily A. Dactylioceratinae Hyatt.

Discoidal forms with costae bifurcated and always
Crossing the venter. Sutures with very complex
outlines, but only three or four pairs of lateral lobes
and saddles. Dorsal sutures have two pairs of saddles
and one pair of zygous lobes,

This series is usually termed the Plaiiulati of the
Lias, but althoiigh an ofFslioot of the sarae common stock,
it is quite distinct from its supjiosed congeners of the
Middle and Upper Jura. Sutures are straight, not in-
clined apicad as in Perisphiuctinae. The subfamily com-
prises a complete cycle of forms varying from the broad
trapezoidal, tuberciilated volutions of Coeloceras through
Ariuatoid species to Dactylioceras, in which the costae
are smooth and sometimes even single.

662

MOLLUSCA

PHYLÜM VI

Goeloceras (Deroceras Hyatt) (Fig. 1279), Dadylioceras (Fig. 1280) and Peronoceras

Hyatt ; Pimelites and Diafliorites Fucini ;
(?) Praesphaeroceras Levi ; (?) Gollina Buckm.
Middle and Upper Lias.

Subfamily B. Stephanoceratinae
Steinmann.

Fi(i. 1280.

Dactylioceras commune (Sovvb.). Upper Lias
England.

Primitive radicals, highly coronate, dis-
coidal, giving rise ai)parently to involute and
partially comjiressed forms that in Macro-
cephalites and some otliers are without tubercles,
Venter always rounded, costae bifnrcating on
the sides and continuous acroßs tlie venter.
Only one line of nodes or tubercles at tlie
umbilical Shoulders, and the division of costae

Fig. 1281.

SpJuxerocerasbrongniarti (Sowb.). Inferior
Oolite ; Bayeux, Calvados.

Fk;. 1282.

Normannitcs braikenridgei (Sowb.). In-
ferior Oolite ; Bayeux, Calvados, i/i.

takes place along these lines in most forms. Sutures of the same type as in Dacty-

Fic. V2S3.

Af«r»e„A„«,» M^r„o,p„a,u. (Scl.lotl,.,. Upp» Doggor (Callovian) ; Ehninge,,, Würtcmbsrg.

lioidmae, l.ut nnich more complex, with usually „lore iniiections, and lote and saddle.

J

CLAS8 V

CEPHALOPODA

663

iiiore nearly equal. Doi-sal sutures generally have three pairs of zygoiis saddles and

two pairs of lobes in tlie coronate discoidal

forms.

Stefhanoceras Neiim. (Fig. 1285); Gado-
mites Mim.-Chalnis. ; S2)haeroceras Bayle (Fig.
1281); Emiida Buckman ; Normannites
Miin.-Clialmas (Fig. 1282); Macrocephalites
Sutner (Fig. 1283); Sutnerm Zittel (Fig. 1284).
Inferior Oolite.

Sutneria platynota (Rein.). Upper
Jura (Tenuilobatus Beds) ; Balingen,
Wärtern barg.

Fig. 1l>85.

StepTiiiTUKeras cor(ynati(s (Brug.). Callovian

Dept. Nievre, France. 1/3-

Subfamily C. Cadoceratinae Hyatt.

More specialised, comjDressed, and involute forms tend to evolve shells with
crenulated keels, and sometimes Channels also. Costae of Gadoceras divided as in
Steplianoceratinae, but other genera usually develop two lines of tubercles. Young
of Neumayria more or less costated, but sides and keel become smooth, and in some
species resemble the adult of Quenstedtoceras.

Tills group is remarkable for the close parallelism of some of its genera with Amaltheidae,
but the young are very distinct. Development and adul t stages of Gadoceras with its discoidal
and much depressed volutions plainly show derivation from Coeloceran stock, while its form
and sutures also show relationsliip with Steplianoceratinae.

Gadoceras Fischer ; Quenstedtoceras Hyatt ; Gardioceras Neumayr and Uhlig ;
Neumayria Nikitin. Kelloway.

Subfamily D. Perisphinctinae Steinmann.^

An extensive series of discoidal genera having rounded or subquadrangular
volutions, and costae single on the sides, but split into two, three or more on the
venter, which they cross uninterruptedly. Splitting does not begin as a rule at
umbilical Shoulders, but near the ventro-lateral angles. Inner parts of sutures steeply
inclined apicad, and dorsal sutures have a long pair of first dorsal saddles, usually two
additional pairs of saddles, and two pairs of lobes. All of these are so decidedly
inclined apicad that they often appear as a single pair of complex saddles.

These genera are morphic equivalents of the Liassic Dactylioidinae and are derived from
the same common stock. Young have depressed trapezoidal volutions and often minute
tubercles on ventro-lateral angles, but are otherwise smooth, like the young of Gadoceras
sublaeve. They become compressed in the neanic stage and rapidly assiime the discoidal
Perisphinctean form and costae without tubercles.

Perisphinctes Waagen {Grossüuvria, ProceriteSy Ghoffatia Siemirad.) (Figs. 1286-

^ Sieviiradzki, ./., Monographische Beschreibung der Gattung Perisphinctes. Palaeontogr. 1898,
vol. xlv. See also R. DouvilU's recent studies of Gardioceras, etc., 1913.

664 MOLLUSCA

1288) ; Ätaxioceras Font.; FroplamiUtes Teiss.; Pidonia Bayle ;
Lampl. Inferior Oolite and Cretaceous.

PHYLUM VI

Pavl. and

FiCr. 1286,

Suture line of Perisphindes colubrinus

(Rein.).

Fi(i. 1287.

Perisphinctes polyplocus (Rein.). Upper
Jura ; Pappenheim, Bavaria. i/g.

Perisphinctes tiziani (Oppel). Upper Jura (Bimammatus Beds) ;
Hundsrück, near Streichen, Würtemberg.

Subfamily E. Morphoce ratin ae Hyatt.

Globose and iisually involute fornis witli open umbilici showing the yoimg to be
highly coronate imtil a late stage. Costae on iimbilical zones Single and widely

separated, but divided into
very broad biindles of fine,
closely - set, ventro - lateral
costae diflering from those of
all other groups except sonie
Perisphinctinae. Only one
line of tubercles or nodes,
whicli usually occiir at um-
bilical Shoulders. External
and dorsal sutures resemble
those of Perisphinctinae, but
not so imiformly inclined
apicad. In discoidal coronate
Shells the lobes and saddles
are of equal length, and
dorsum has two pairs of
zygous lobes and two pairs of
saddles.

Morphoceras Douv. ;
Garantiana Siemirad. ; Olco-
stephanus Neuni. {Holcostephanus aiict.) ; Folyptijchites, SimhirsJdtes, Ästieria, and
Virgatites Pavl. and Lampl. Upper Jura and Cretaceous.

Fi(i. 1289.
ReinerJcia hrancoia (Steinm.). Caracoles, Boliva (after Steiiimann).

CLASS V

CEPHALOPODA

665

Siibfaiiiily F. Reineckiinae Hyatt.

Discoidal shells with costae siiigle on the lateral zones but bifuicated on their
outer parts, and
with one or two
liiies of tubercles,
the first being
iiear the point of
bifurcatioii of the
costae, and the
other near their
ventral termini.
Division of costae
takes place along
ventro - lateral
angles and not on
or near the um-
bilical Shoulders.
Costae cross the
venter only in
the coronate
young, when the
section is trape-
zoidal as in Goeloceras. Sutures as in the preceding subfamily.

Reineckia (Fig. 1289), Parkinsonia Bayle (Fig. 1290); Oecoptychius Neum. (Fig.
1291); Äulacostephanus Sutner and Pomp; (?) Waagenia Neum.; Strenoceras Hyatt.
Type *S^. (Ammonites) niortense (d'Orb.). Middle and Upper Jura.

Fio. 1290.

Farkinsonia farkinsoni (Sowb.). Inferior Oolite ;
Bayeux, Calvados.

Fig. 1291.

Oecoptychius refractus
(de Haan). Callovian ;
Niort, France (after
d'Orbigny).

Family 26. Aspidoceratidae Zittel.

Earlier volutions costate, later ones with one or two rows of tubercles. Venter hroad,
never keeled. Septa resemhling those of Dactylioidinae, hut saddles omd lohes hroader^ and

Fig. 1292.

Aspidoceras 2iemrmatum (Sowb.). Oxfordian

Dives, Calvados. V'2-

Fi«;. 1293.

Simocfnu^ volanense (Oppel).
Lower Titlionian ; Monte Catria,
Central Apennines.

dorsal sutures loith only one large pair of inner or first dorsal lobes^ the outer or second
pair being incomplete in the more discoidal species as in the Arietidae.

Aspidoceras Zittel (Fig. 1292); Peltoceras Waagen (Fig. 1294); (?) Aurigcrus

PHYLUM VI

QQQ MOLLUSCA

Oprel; (?) Simoceras Zittel (Fig. 1293); Siemiradzkia Hyatt. Type S. (Ämmonites)

Fio. 1294.

Peltoceras athleta (Phill.). Upper Callovian ; Vaches noires,
Normandy. i/i.

riiysodoceras circum-
spinosum (Oppel). Upper
Jura ; Swabian Alps. 1/2.

bakeriae (d'Orb.) [Terr. Jurass. PL 149, Fig. 1, non PL 148]. Physodoceras Hyatt
(Fig. 1295). Type P. (Ämmonites) circumspinosum (Oppel). Upper Jura.

Family 27. Desmoceratidae ZitteL

Discoidal moderately involute forms, with simple or divided rihs. These continue
without Interruption across the rounded keelless venter. Gonstrictions or varices at
regulär intervals. Septa finely digitate, with auxiliary lohes arranged in a straight row.

The Desmoceratidae are slightly modified descendants of the Stephanoceratidae,
and preserve in youth the characters of the ancestral family.

Subfamily A. Desmoceratinae Zittel (pars).

Mostly involute shells, smooth, or with constrictions and fold-like costae without

tubercles that commonly follow the
lines of growth across the rounded
venter uninterruptedly. Spines
sometimes present as in preceding
family. Sutures have blunt
siphonal saddles, never pointed.
First lateral lobes shallower than
Fio. 1296. "^ ^^^ Lytoceratidae, the first

lateral saddles broader, and less
deeply cut by marginals. Anti-
siphonal lobe long, straight, and

trifid. Lateral zygous inflections more numerous, and there are often three or more

zygous dorsal saddles.

Suture-line of Desmoceras latidorsatum Mich. Gault :
Parte du Rhone.

CLASS V

CEPHALOPODA

667

Eurynoticeras Canavari.

Jura. Desmoceras Zittel (Figs. 1296, 1297); Puzosia
Bayle ; Gleonoceras Paroiii and
Bon. ; Schlueteria, Hauericeras
Grossouvre. Cretaceous.

Subfamüy B. Silesitinae
Hyatt.

Similar to the Desmoceratinae,
but costae more strongly de-
veloped, and sometimes spinous.

Fio. 1297.

Desmoceras inayorianum (d'Orb.). Gault ; Perte du Rhone
(after d'Orbigiiy).

Fio. 15
Fachydiscus feramplus (Mantell). Lower Chalk ; England.

Fig. 1299.

Pcichydiscus wittekindi (Schlüter).
Upper Cretaceous ; Haldem, West-
phalia. 1/3.

Süesites, Holcodiscus Uhlig ; Fachydiscus Zittel (Figs. 1298, 1299); Parapachy-
discus Hyatt. Type P. {Ammonites) gollevülensis (d'Orb.). Cretaceous.

Family 28. Oosmoceratidae Zittel.

Shells richly ornamented with ribs that are divided, or broken wp into rows of hnots.
Usually with rows of umbilical and marginal hnots on the ribs. Sculpture interrupted
by a furrow on the venter. Aperture often with lateral ears or lappets. ? Septa deeply
digitate. One or two auxiliary lobes present.

668

MOLLUSCA

PHYLÜM Vll

The Cosmoceratidae are probably a polyphyletic group, derived from severalj
branclies of tlie Steplianoceratidae.

Subfamily A. Cosmocbratinae Hyatt.

Discoidal and involute forms having at a comparatively early stage or throughout

life two or tbree rows of large tubercles
■■^^ nf^7J?j)»«a Qj^ gg^(3i-^ gi(je^ and costae interrupted on

the venter by a sniooth median zone or
Channel.

Gosmoceras Waagen (Fig. 1300).
Middle Lias to Oxfordian.

Subfamily B. Hoplitinae Hyatt.

Discoidal and involute forms with
costae bifurcated on the sides at umbilical

Fio. 1300.

Gosmoceras ornatum (Sowb.). Callovian (Ornaten
thon) ; Gamiuelsliausen, Würteniberg.

Fit;. 1301

Hoplites tuberculatus (Sowb.).
Gault ; Folkestone, England
Siphuncle broken away f

Fig. 1302.

Uoplites noricus (Sowb.). i = Ho2Mtes amUygonius Neum,). Neocoraian ;

Achim, near Börsuni, Prussia.

Shoulders ; prominent tubercles at their forks, and also at or near their ventral
termini, these last being separated by a median zone or deep Channel. Young of
some species have costae continuous across the venter, and resemble those of Sonneratia.
Parallelism with Cosmoceratinae very close. Sutures resemble those of Mammites,
but more complex. Lateral saddles narrower and more deeply cut, and first lateral
saddles often trifid in late stages. Dorsal series with two pairs of complex zygous
lobes and saddles on either side of a long, narrow, complex, antisiphonal lobe.

Hoplites Neum. (Figs. 1301, 1302); Genomanites Hang {Discoceras Kossmat) ;
Sonneratia Bayle ; Neocomites Uhlig. Cretaceous.

CLASS V

CEPHALOPODA

669

Subfamily C. Acanthoceratinae Hyatt.

Robust and nioderately evolute forma. Surface highly ornamented witli ribs
either simple or bifurcating. Rows of tubercles usiially present on ribs, and often a

Fi(i. 1303.
Acanthoceras rhototnagense (Defr.). Cenomanian ; Rouen, France (after Quenstedt).

Fio. 1304.
Douvilleweras mamiUarc (Schloth.). Gault ; Macherom^nil, Ardennes.

median row, sometimes uniting in a keel. Septa deeply digitale, the first lateral
saddle being bifid.

Acanthoceras Neiimayr (Fig. 1303); Douvüleiceras Gross. (Fig. 1304); ITiur-
mannia Hyatt ; Steueroceras Cossmann {Odontoceras Steuer) ; Mammites Laube and
Bruder : Muniericeras and Barroisiceras Gross. Cretaceous.

Subfamily D. Crioceratinae Hyatt.

A heterogeneous group of degenerate forms, probably derived from several different
normal groups. Forms higbly ornamented witli. ribs and spines or knota. The

670

MOLLUSCA

PHYLUM VI

youtliful whorls are coiled spirally in a plane ; at maturity the whorl straightens out
temporarily, often bending back again in a hook-sliaped body -Chamber.

Fig. 13G5.

Spiroceras bifurcatum (Quenst.). Upper Dogger (Cal-
lovian) ; Ehningen, Würtemberg. A, Shell with protoconch
broken away, i/j. B, Portion of venter. (', Suture-line.

Fio. 1306.

Ancyloceras matheronianum d'Orb. Neocomian ;
Castellane, Basses Alpes. A, Concli. U, Suture-
line.

Spiroceras Quenstedt (Fig. 1305), Lower Oolite, supposed to be derived from
Parkinsonia. Grioceras Leveille ; ^.wc^Zoceras d'Orb. (Fig. 1306). Cretaceous.

Subfamily E. Scaphitinae Meek.

Whorl close-coiled in youth, opening out at
maturity into a hook-
shaped body - Chamber.
Form robust, tliick-set,
involute, surface highly
ornamental with ribs
and knots. Septa finely
digitate, usually with
several auxiliary lobes.

Scaphites Parkinson
(Figs. 1162, 1307, 1308);
Fin. 1308. Discoscaphites Meek ;

rfZnÄn,-"''^''''^'T, ^°'^^- Jahnites Hyatt. Greta-

i^enonianian; Ronen ^

France, l/i- ceoUS.

Fir„ 1307.

Scaphites spiniger Schlüter. Upper Greta
ceous (Senonian) ; Coesfeld, Westphalia.

CLASS V

CEPHALOPODA

671

Subfamily F. Placentice ratin ae Hyatt.

Coiupressed, involute, higli-whorled forms, witli venters flat coinijressed or concave
in youth, becoming somewhat rounded witli age. Surface either tuberculate or
smooth. Septa complex, with
irregulär outlines, and narrow
saddles.

This group appears to be little
modified from the ancestral Cosmo-
ceratinae,! and of all tlie so-called
Pseudoceratites of the Cretaceous it
is nearest to the typical form.

FlacenHcerasM.Qek ; JDvplacomo-
ceras Hyatt ; Forbesiceras Kossmat.
Cretaceous.

Family 29.

Bngonoceratidae
Hyatt.

Indoceras ismaeli (Zittel). Upper Seiionian ; Libyan
Desert west of Oasis Dachsei.

Shell compressed, patelliform,
narrowly uvihilicate, high lohorled.
Venter ßattened or rounded, or
acute. Flanks with broad low folds
which often end in marginal keels,
more seldom in knots or spines.

Septa not deeply digitate, lobes usually only moderately serrated, saddles often rounded
and entire. The external saddle is often divided into several secondary lobes. There
are several auxiliary lobes in most genera.

The Engonoceratidae were probably derived from the Placenticeratinae, and

through them from the Cosmoceratinae.

Engonoceras Neumayr ; Metengonoceras
Hyatt ; Hoplitoides von Koenen ; Indoceras
Noetling (Fig. 1309); Sphenodiscus Meek.
Cretaceous.

Family 30. Pulchelliidae Douville.

Form involute and high whorled. Venter
ßattened or rounded or acute. Flanks smooth,
or ornamented loith ribs or knots. Septa not
digitate, being mostly either ceratitic or gonia-
titic in character. Lobes and saddles shcdlow,
löith broad saddles and narrow lobes. External
saddle divided into several secondary lobes.
Auxiliary lobes two to three in number.

The Pulchelliidae were probably derived
from the Hojilitinae. Pulchellia Douville ;
Metoicoceras Hyatt ; Knemiceras J. Boehm ;
Buchiceras Hyatt ; lloemeroceras Hyatt ; Tissotia
Douville (Fig. 1310). Cretaceous.

Vir.. 1310.

Tissotia fourndi Bayle. Cenomanian ; Mzabel-
M'sai, Algiers (after Bayle).

^ Smith, J. P., The developmeiit and i)liylogeiiy of Placenticeras.
Sei., 3rd ser., Geol., 1900, vol. 1. No. 7.

Proc. California Acad.

672

MOLLUSCA

PHYLUM VI

In this familyi probably beloiig several geiiera comnionly classed witli Oxynoticeras
or Amaltheus, as follows :— Garnieria Sayii. ; Lenticeras Gehr. ; Eulophoceras Hyatt.

Family 3L Prionotropidae Zittel.
Form evolute. discoidal, laterally compressed. Flanhs with strong, simple or
dichotomous ribs that form one or more rows of hnots on the sides, and one on the
ventral Shoulders. Venter with sträng median keel, either smooth or hrolen up mto a

Fi(!. 1311.

Schloenbadda varians (Sowb,)- Cenomanian
Quedlinburg, Saxony.

Fig. 1312.

SchloenbacMa cristata (Deluc),
Lower Cretaceous.

roiv of hnots. Septa only moderately digitate. External and first lateral saddle hroad,
lateral lohes hifid, only one auxiliary lohe present.

This groiip is commonly siipposed to have been derived from the Amaltheidae,
but proofs of the connection are lacking.

SchloenbacMa Neumayr (Figs. 1311, 1312); Hystatoceras Hyatt; Barroisiceras
Gross. ; Mortoniceras Meek ; Peroniceras Gross. ; Prionotropis Meek. Cretaceous.

Range and Distribution of the Ammonoidea.

The Ammonoids are more than twice as rieh in forms as the Nautiloids. While
of the latter aboiit 2500 species have been described, the number of Ammonoids has
reached far beyond 5000 species. These are without exception extinct, and are
especially characteristic of the Mesozoic era.

Although Ammonites are unknown later than the Cretaceous period, nevertheless
this group must be regarded on the whole as the younger brauch of the stock of
Tetrabranchiates. After the Nautiloids had passed their culmination, the Goniatites
and Clymenias appeared as the oldest representatives of the Ammonoids. The time
ränge of the Clymenias is limited to a short epoch in the Upper Devonian ; the
Goniatites appeared first in the Upper Silurian (Kellerwald), developed a great
variety of forms in the Devonian, and continue until the close of the Paleozoic era.

Until a few years ago it was belle ved that only Goniatites and Clymenias occurred
in the Paleozoic deposits. The discovery of genuine Ammonites in the Permian of
the Salt Range of India, in the Ural Mountains, in Texas, in the Fusulina limestone
of Sicily, etc., and later the discovery of primitive Ammonites in the Goal Measures
of Texas and in the Lower Carboniferous of the Mississippi Valley, piished their ränge

^ DonvilU, IL, Evolution et Classification des Pulchellides. Bull. See. Geol. France, 1911, vol. xi.

CLASS V RANGE OF THE AMMONOIDEA 673

consideraLly furtlier back into the Caiboniferous system. These Paleozoic Aiunionoids
stand in the development of their septa between the Goniatites and the more highly
ypecialised Mesozoic Ammonites.

With the beginning of tlie Mesozoic era, the triie Ammonites developed with
great rapidity. In the middlo European Muschelkalk only the genera Ceratites,
JienecJceia, Hungarites, Balatoni^es, Arniotites^ Acrochordiceras and Ptychites have as
yet been discovered. On the oilier hand, in the Alps, Spitzbergen, the Himalayas,
in western North America and 'in Siberia, there have been found great numbers of
Ammonites in rieh faunas of the Lower, Middle and Upper Triassic. The families
of Tropitidae, Ceratitidae, Ptychitidae, Cladiscitidae and Pinacoceratidae belong
exclusively to the Triassic ; the Arcestidae begin in the Goal Measures, but reach
their greatest development in the Triassic.

In the development of their septa the Triassic Ammonites show an unexpected
variety of form and complexity. Certain genera {Sageceras, Lecanites, Lohites) scarcely
pass the goniatitic stage of development ; many others (MeeJcoceras, etc.) only reach the
ceratitic stage. In the Arcestidae, Tropitidae, Cladiscitidae, Ptychitidae and Phyllo-
ceratidae the lobes and saddles have become digitate. Indeed, in Pinacoceras is found
the greatest complexity of development of the septa that has been observed among the
Ammonites. Along with the typical forms the Upper Triassic of the Alps has fur-
nished also a number of reversionary types or aberrant forms (Gochloceras, Rhabdoceras^
Ghoristoceras), which are distinguislicd by reduction of the septa to great simplicity.

With the Lias a fundamental change in the Ammonites occurred. Of the
numerous Triassic genera and families, with the exception of the Phylloceratidae, all
have come to an end and are replaced by new forms. The causes that made the
Cephalopods so rare in the Ehaetic are unknown. It may be that not all these
groups were extinguished, but that they lived on in other, as yet unknown regions,
and when we next see them in the Jurassic they have changed beyond recognition.

In the Lower Lias the Aegoceratidae are almost the only forms ; the genera
Psiloceras, Arietites and Schlotheimia, are confined to this stage. In the Middle Lias,
along with the Aegoceratidae, are represented the Harpoceratidae, the Amaltheidae
(Oxynoticeras, Amaltheiis), the Phylloceratidae (Phylloceras), the Lytoceratidae
(Lytoceras), and the oldest members of the Stephanoceratidae {Goeloceras, Dactylioceras).
It is noteworthy that in the Liassic Ammonites the antisiphonal lobe is frequently
bifid (as in the Aegoceratidae and Amaltheidae).

With the exception of the Aegoceratidae all the families that appeared in the
Lias lasted into the Middle and Upper Jurassic, although the Harpoceratidae are
reduced in numbers, and perished in the Malm or Upper Jura. The only new
families added in the Middle Jurassic are the Haploceratidae and the Cosmoceratidae.
The most common genera in the Middle Jurassic are : Harpoceras, Oppelia, StephanoceraSj
Sphaeroceras^ Morphoceras, MacrocephaUtes, Oecoptychius, Reineckia, Parkinsonia,
Gosmoceras, PerispMnctes, Haploceras, Phylloceras, Lytoceras.

In the Malm are found nearly all those genera named under the Middle Jurassic,
but the number of species has changed greatly. Thus Harpoceras, StephanoceraSj
Reineckia, Parkinsonia and Gosmoceras, are reduced, while Oppelia, Haploceras,
Olcostephanus, and especially PerispMnctes have increased greatly. PerispMnctes is
decidedly the dominant genus in the Upper Jurassic, and along with it Asjndoceras,
Simoceras and Peltoceras show a large number of species. Aberrant forms are rare
in the Jurassic, and are confined to a few species of Sjnroceras and Baculina.

■ A change like that seen at the beginning of the Jurassic takes place also at the
end of this period. The Ammonites of the Creta,ceous belong largely to new genera.
Indeed a remarkable metamorphosis occurs in the entire habitus of the Cephalopod
fauna. Only the oldest Neocomian beds of the Alps contain a few species that had
lived in the Tithonian epoch, and show the continuity of the two Systems. The least
degree of change is shown by the Phylloceratidae and the Lytoceratidae. In place of
VOL. I 2 X

674

MOLLUSCA

Table showing Geological Kange of Ammonoidea

Families.

i

1

i

1

1

!

1

1 ^

i

f3
O

1. Clymeniidae
Extrasiphonata

1. Bactritidae

2. Nautilinidae

3. Aphyllitidae

4. Tornoceratidae .

5. Cheiloceratidae .

6. Gephyroceratidae

A. Primordialinae .

B. Beloceratinae .

7. Prolecanitidae

A. Prolecanitinae .

B. Noritinae .

C. Medlicottiinae .

8. Pinacoceratidae

A. Hedenstroemiinae

B. Sageceratinae

C. Carnitinae

D. Pinacoceratinae

9. Glyphioceratidae

10. Thalassoceratidae .

.... _

—

11. Ptychitidae

12. Tropitidae

A. Tropitinae

B. Haloritiuae

C. Sibiritinae

D. Celtitinae

13. Arcestidae

A. Popanoceratinae

B. Cyclolobinae

C. Arcestinae

14. Cladiscitidae .

1

15. Meekoceratidae
A. Lecanitinae

B, Meekoceratinae

-—...

16. Gymnitidae

17. Hungaritidae .

...

18. Ceratitidae

A. Ceratitinae

... «

B. Tirolitinae

—

C. Dinaritinae

■ D. Buchitinae

—

E. Arpaditinae

F. Trachyceratinae

G. Choristoceratinae

H. Cochloceratinae

1

—

1

RANGE OF THE AMMONOIDEA

675

Families,

i
1

0

1

G
O
>

£

1
1

Permian.

•

i

i

s

•-9

19. Phylloceratidae

A. Monophyllitinae .

B. Phylloceratinae .

20. Lytoceratidae

A. Lytoceratinae

B. Macroscaphitinae

C. Turrilitinae

21. Aegoceratidae

A. Psiloceratinae

B. Arietitinae .

C. Aegoceratinae

D. Polymorphinae .

22. Harpoceratidae

A. Harpoceratinae .

B. Oppeliinae .

23. Amaltheidae

A. Amaltheinae

B. Hammatoceratinae

24. Haploceratidae .

25. Stephanoceratidae

A. Dactylioceratinae

B. Steplianoceratinae

C. Cadoceratinae

D. Perispliinctinae .

E. Morphoceratinae .

F. Reineckiinae

26. Aspidoceratidae .

27. Desmoceratidae

A. Desinoceratinae .

B. Silesitinae .

28. Cosmoceratidae

A. Cosmoceratinae .

B. Hoplitinae .

C. Acanthoceratinae

D. Crioceratinae

E. Scaphitinae

F. Placenticeratinae

29. Engonoceratidae

30. Pulchelliidae

31. Prioriotropidae .

i

!

1

—

—

.

—

^

_

..

...»

tlie Harpoceratidae we find the Desmoceratidae, of which the genera Desmoceras and
Silesites especially characterize the Neocomian and Gault, and Pachydiscus the liiglier
stages of the Cretaceous. Of the Steplianoceratidae the genera Perisphinctes and
Olcostephanus, which liad survived from the Jurassic, are extinguished in the Lower
Cretaceous. In the i)lace of tlie Jurassic Cosmoceratidae appear HopliteSy Douvilleiceras
and Acanthoceras. A peculiar retrograde development of the septa, a reyersion to the
ceratitic stage, is seen in two families of Cretaceous Ammonites, the southern

676

MOLLUSCA

PHYLÜM VI

Piilclielliidae and Eiigonoceratidae, which were probably connected witli tlie younger
Cosnioceratidac (Hoplites). The Cretaceous Ammonitic fauna derives a special
character from tlie great development of aberrant forms, whicli are most abundant in
the Neocomian, but in part last into the higher stages of the Cretaceous. The genera
Macroscaphües, Pictetia, Hamües, Anisoceras, Turrilites, BacuUtes, Grioceras and
Scaphites are confined exclusively to the Cretaceous.

The sudden extinction of the Ammonites at the end of the Cretaceous is one of

Diagram showing the Relationships of Paleozoic and
Early Mesozoic Ammonoids

Tropitoidea

Ptychiloidea Lytoceratoidea

Pinacoceratoidea

3 ü

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the most reniarkable phenomena in the history of the organic world, and one as yet
witliout explanation. Great changes in conditions of life must have taken place at
the border between Cretaceous and Tertiary to have brought about the extinction of
this flourishing and highly organised group of animals not only in Europe, but also
in all other parts of the world.

The System of nomenclature now commonly in vogue has placed obstacles in the
way of a clear view of the general characters of the whole group of Ammonoids.
And this is especially unfortunate because in more recent years the genera and
families named have been difficult to distinguish, and in many cases have received
very vague definitions. At present the prevailing tendency is to subdivide rather
than to unite, and some authors are in a fair way to change every time-honoured
species into a special genus or family.

Few divisions of the animal kingdom have left such a perfect record of their

SUBCLASS II

DIBRANCHIATA

677

develojjmeiit, and sucli a great mass of evidence in favour of the theory of evolution
as liave the Amnionites, Indeed, in this group, on accoiint of tlie nncommon thinness
of tlie shell, internal nioulds are of as mucli importance froni tlie standpoint of precise
identification as those specimens whicli have the shell perfectly preserved.

Tlie first attempt to study a large number of species of Ammonites in tlieir
genetic relationships was made by Waagen in the series of Oppelia supradiata.
Similar attempts were made by Neumayr in the Phylloceratidae, Perisphinctinae, etc. ;
by Hyatt in the Arietitinae ; and with especial minuteness by Leopold Würtenberger
in the Jurassic groiips Äspidocei-as, Siinoceras, Waagenia, Peltoceras, Periaphinctes and
Stephanoceras. Also Mojsisovics, Uhlig, Hang, Douville, Frech, Diener, Pompeckj and
others have paid special attention to the genetic relationships of the various groups of
Ammonites. All these authors come to the conclusion that in the Ammonites there
are numeroiis genetic series of which the development may be followed step by step in
the species that occur in the various successive strata.

In the last few years great progress has been made in the study of the Ammonite
launas, especially of the later Paleozoic and Triassic horizons ; also in the most various
divisions of the many branched family tree of the Ammonites, much light has been
thrown upon the genetic relationships of numerous genera and families. But in
spite of this it is not yet possible to give a graphic representation of the development
and kinship of the Ammonoidea that is true of the whole group, and beyond suspicion
in any of its parts. However, in the above diagram a tentative effort is made in this
direction, and in this scheme the probable relationships of the Paleozoic to the
earlier Mesozoic genera are indicated in the light of ^

the present Status of our knowledge. '

[The foregoing chapter on Ammonoidea has been revised
for the present work by Professor James Perrin Smith, of
Leland Stanford Junior University, California. — Editor.]

Subclass 2. DIBRANCHIATA Owen.

Cephalopods with only two arborescent gills in the
mantle-cavity : provided round the mouth with eight
or ten arms hearing suckers or hooks, two of them
(when ten in all are present) heing often developed
into long tentacles. Funnel closed ; ink-sac usually
present Shell internal, or if external, it is not
chamhered ; in many forms entirely wanting.

The body of the Dibranchiates or Cuttle-fishes
is elongated, cylindrical or sac-shaped, and fre-
quently provided with two lateral fin-like append-
ages. The anterior cephalic region gives ofF a
circlet of eight or ten powerful, muscular arms,
the inner sides of which are armed with suckers
(acetahula), or a double row of hooks, and assist
in swimming or creeping, and also serve for the
capfcure of prey. The Sepioidea have two of
their ten arms developed into very long tentacles
which bear hooks or suckers only at their
thickened extremities (Fig. 1313). The lower surface of the suckers is disk-
or cup-shaped, perforated in the middle, and occupied by numerous radially

Fig. 1313.

Enoploteuthisleptura. Recent;
Pacific Ocean. A, Ventral aspect.
B, Internal shell or "pen."

678 MOLLUSCA— CEPHALOPODA . phylum vi

arranged muscle fibres ; they are also occasionally furnished with horny hooks
or Sharp claws. Each siicker is able to create a partial vacuum by pressiiig
bhe cartilaginous rim against some object and theri contracting the inner
folds, and hence can be used like a cupping-glass.

The jaws resemble those of Nautiloids in form, but are never calcified ;
and owing to their perishable nature, usually horny, they are not preserved in
the fossil State. The cartilage of the head forms a complete ring enclosing
the central portion of the nervous system. The eyes are of large size,
protected by a capsule, and recall those of vertebrates in structure.

The body is constricted at the mantle opening, which occurs just behind
the head, and at this point on the ventral , surf ace is placed the respiratory
orifice, bounded by a projecting fold of the mantle. Here also terminates
the cylindrical or conical funnel, on either side of which lie the dendriform
gills ; in this region also are placed the anal and genital openings.

The abdomen is sac-shaped, and contains besides the viscera and circu-
latory Systems a rather large pyriform vessel called the ink-bag. Its reservoir
is filled with an extremely opaque brownish-black fluid, which can be voided
at will through an excurrent canal terminating near the anus. Menaced or
alarmed, the creature discharges a dense cloud of ink, which serves to
conceal its retreat. One often finds within the body of fossil Dibranchiates
not only a cast or mould representing the ink-bag, but often a dark-coloured
residuum of the carbonaceous particles suspended in the ink.

The abdomen is completely covered by the mantle, which is a thick and
frequently brilliantly coloured muscular envelope. Traces of it are occasion-
ally found among fossil forms, owing to a slight secretion of calcareous matter
within it.

Most Dibranchiates secrete an internal shell within the mantle. Only
among the Octopoda is a shell absent entirely, or replaced in the female by a
thin, simple, unchambered spiral ; but this last is in nowise homologous with
the usual Dibranchiate shell. Spirula has a spiral, camerated shell, the septa
of which are traversed by a siphuncle, and the coils are not in contacb. It
is situated in the hinder portion of the body and is partially enveloped by the
mantle. Among extinct Belemnites the internal shell consists of three parts :
a chambered cone (phragmacone), which is prolonged forwards on the dorsal
side into a delicate corneo - calcareous proostracum, and is inserted at the
posterior end into a finger-like calcareous piece called the guard (sheath or
rostrum) (Fig. 1314, C).

Some living Cuttle - fishes have a horny, elongated-oval, feather-shaped
proostracum or "pen" (Fig. 1332), which is situated dorsally in a closed sac
of the mantle. It is sometimes extremely thin, and composed of conchyolin
or lime carbonate. The sepion, gladius, or " cuttle-bone," as the shell is called
when calcified in some genera, exhibits at its posterior end a small point (the
mucro) corresponding to the guard in Belemnites, and extends in front as a
broad shelly plate, like a proostracum. This forward extension, when viewed
from the front side, is seen to be covered by a mass of thin shelly lamellae,
which correspond to the septa more distinctly observed in Belosepia.

Many living Dibranchiates are gregarious, and swim in the open sea in
hordes ; others creep on the bottom or lead a separate existence along rocky
shores. They are extraordinarily active, voracious animals, and prey upon
mollusks, crustaceans and fishes. A few species are esteemed as food by man.

SüBCLAss II DIBRANCHIATA 679

In size Dibranchiates are extremely variable ; some forms are only 2 or 3 cm.
long, others attain gigantic dimensions. Architeuthis, for example, reaches
a total length of 12 metres, the body being 2*5 long, and over 2 metres in
circumference. Its arms are thick as a man's leg, and the suckers sometimes
as large as ordinary coffee-cups.

Dibranchiate Cephalopods are divided into three Orders, as follows : —
Belemnoidea, Sepioidea and Octopoda.

Order 1. BELEMNOIDEA. {Phragmophora Fischer.)^

Shell internal, chambered, and the septa traversed hy a siphuncle ; conical or more
rarely spiral, and {with the exception of Spirula) terminating posteriorly in a calcareous
sheath or guard. Arms ten in numher, provided with hooklets. Trias to Recent.

Save for tbe genus Spirula, all forms belonging to this suborder are extinct. Their
camerate shells, perforated by a siphuncle, betoken a kinship with Tetrabmnchiates, but
there are decided differences both in the structure and function of the shell. Tetra-
branchiates have the shell always external, enclosing the body, but in Dibranchiates it
is more or less enveloped by soft parts. Genetic connection between the Belemnoidea
and Sepioidea is apparent, and although their shells differ in form and structure, yet
a rudimentary phragmacone persists in the latter at the posterior end of the skeleton.
This rudiment is much more perfectly developed in Belosepia of the Tertiary, which is
a connecting link between Belemnoidea and Sepioidea. It is possible to explain the
entire internal shell of Spirula as homologous with the phragmacone of Belemnites.
It begins as a globular or inflated protoconch, which is constricted otf from the first
camera, and is devoid of a cicatrix. The siphuncle originates as a caecal tube, and is
continued apicad as a prosiphon, the same as in Ammonoids.

Family 1. Belemnitidae de Blainville.

Shell composed of a conical camerate phragmocone, continued on the dorsal side as a
proostracum, and an elongated solid rostrum or guard. Arms ten in number, of equal
length, provided with hooklets, Ink-bag present. ■ Trias to Eocene.

This family, owing to its great morphological diversity and geological importance, oecupies
a foremost position among Belemnoidea. The shell may be considered as the prototype of that
in all Dibranchiates,. since it has all the component parts fully developed, vvhereas in other
groups some of these become atrophied or wanting.

The shell of Belemnites (Fig. 1314) consists of three fundamental portions : (1) A solid
calcareous piece, usually much elongated, and of subcylindrical, conoidal or fusiform shape.
This is called the guard {rostrum, osselet, gaine, Scheide), and is excavated at its anterior

^ In addition to the literature cited nnder the head of Cephalopoda {v. antea) see the following :
Angermann, E., tjber das Genus Acanthoteuthis Münster, etc. Neues Jahrb. Miner., 1902,
supplem. vol. xv. — Blainville, IL D. de, Memoire sur les Belemnites, Paris, 1827. — Grick, O. C,
On Acanthoteuthis and Coccoteuthis. Geol. Mag., 1896-97, dec. 4, vols iii., iv. — [dem, Notes on
Actinocamax. Ibid., 1904, 1907, vols. i., iv. — Idem, On the Proostracum of a Belemnite from the
Upper Lias of Alderton. Proc. Malacol. Soc, London, 1896, vol. ii. pt. 3. — Idcm, On the Arms of
the Belemnite. Ibid., 1907, vol. vii., no. 5. — Idem, Buccal Membrane of Acanthoteuthis. Ibid.,
1898, vol. iii. pt. I.—Idem, On Belemnocamax bmoeri from the Lower Chalk. Proc. Geol. Assoc,
London, 1910, vol. xxi. — Danford, ö. G., Notes on the Belemnites of the Speeton Clays. Trans.
Hüll Geol, Soc, 1906, vol. v. — Grossouvre, A. de, Quelques observations sur les Bülemnitelles, etc.
Bull. Soc. Geol. "France, 1899, ser. 3, vol. xxvii. — Huxley T. II., On the Structure of Belemnitidae,
etc. Mem. Geol. Surv. United Kingdom, 1864, Monogr. ii. — Phillips, J., Monograph of British
Belemnitidae. Palaeontogr. Soc. , 1865-70. — Suess, A'., UeberdieCephalopoden-Sippe Acanthoteuthis.
Sitzber. Akad. Wiss. Wien, 1865, vol. Ii. — Voltz, P. L., Observations sur les Belemnites. Paris,
1827. — Idem, Observations sur les Belopeltis ou lames dorsales des Belemnites. Mem. Soc. d'Hist.
Nat. Strasbourg, 1840, vol. in.f—Appelöf, A., Die Schalen von Sepia, Spirula und Nautilus.
Kongl. Svenska Vetensk. Handl., 1893, vol. xxv.

680

MOLLUSCA— CEPHALOPODA

PHYLUM VI

broad extremity into a conical cavity or alveolus. Within the alveolus is placed (2) the
phragmaconc. This consists of a conical series of Chambers (loculi), the septa of which are
piereed at the ventral niargin Ibr the passage of the siphuncle. The phragmaconc begins with
a globular protoconch, and its last or anterior chamber is of coniparatively large size. It is
invested with a thin proper wall (conotheca), which is prolonged forwards on the dorsal side
into a more or less calcified plate called (3) the proostracmn. This last corresponds to the
" pen " of living cuttle-fishes. There is evidence that its anterior margin is convex, but it is
so extremely thin that it is never perfectly preserved, and like the phragmaconc, is wanting
in by far the greater nnmber of specimens.

Notwithstanding the fragmentary condition in which the proostracum invariably occurs,
it is possible to reconstruct its outlines from the peculiar conothecal Striae, or markings of the
membranous substance with which it is invested. The conotheca is made up of three very
thin superimposed laminae, the outermost of which usually shows the markings alluded to
most distinctly (Fig. 1314, C). The conical surface of the phragmaconc and proostracum is
divided by Voltz into four principal regions radiating from the" apex : A dorsal area, including
all the Space between two straight lines called the asymptotes, which extends from the apex of
the cone as far as the apertiire. This area occupies about one-fourth of the circumference, and
is marked with loop lines of growth convex toward the front. On eitlier side of the dorsal
area and separated from it by the asymptotes is a lateral or
hyperholic area, each one occupying about one-eighth of the
circumference, and covered with very obliquely arched lines
in a hyperholic form. The ventral area is covered with numer-
ous transverse Striae, of which there are many on each alveolar
Chamber, and tliey are closer together the nearer they are to
the apex of the phragmaconc. The Striae of the dorsal area
are less numerous than those of the rest of the shell, and
usually are less pronounced, being sometimes imperceptible.

"The guard oi Belemnites consists of prismatic calcareous
fibres, which are directed perpendicularly to the surface, and
radiate in all directions from an axial line, which is not
strictly central, but is somewhat nearer the ventral than the
dorsal side. The growth of the guard is effected by the
deposition of successive conical layers or sheaths, which are
secreted over the entire surface, but are thickest behind, and
become gradually attenuated in front. The surface of the
guard is sraooth ; or may be wholly or partially granulated
or wrinkled ; or, again, may be marked with branched vascular
impressions, which are especially conspicuous on the ventral
side. In many cases a well-marked groove — the ventral farrow
— runs from the edge of the alveolus backwards on the ventral
side, exteiiding for a short distance only, or reaching to the
point of the guard (Fig. 1318, C). The apical portion of the
guard often shqws two symmetrical grooves (the dorso-lateral
grooves) which diverge slightly and become shallower as they
extend forwards, and which mark the dorsal side of the shell."
(Nicholson).

As shown by vascular impressions on the rostrum, the shell
of Belemnoids was completely enveloped by the mantle. Well
preserved impressions of the animal in tlie English Lias (Figs.
1315, .ß; 1327) exhibit an elongated form of body, contracted
anteriorly, with a small head surrounded by ten equal arms.
An ink-sac is present, and the arms are provided with hooks.
The maximum size attained by Belemnoids is between 2 and
2-5 metres.

Aulacoceras Hauer {Didyoconites Mojs.) (Fig. 1314).
Guard elongated, clavate, contracted anteriorly, tliickened
^ in the posterior third, and pointed at the tip ; composed

Upper Trias ; Rr)theistein7'riear of concentric, loosely superimposed lameliae. Each side
phragmacone"^. ^]i, Guard, ^i/,*? ^'^^^^^^ ^7 a deep broad lateral groove reaching from
t^ ^°';V'°" °iP^''"^''"'i'l""e «ii^e'i the tip as far as the anterior alveolar margin. Phragma-

10 Show siphuncle aml siphonal \ -i . o ö

funneis. cone at least twice as long as the rostrum, slowly increas-

. , . ^^o 11^ width anteriorly, ornamented externally with

raised longitudmal lines, which are crossed on the dorsal side by a transverse series

Fig. 1314.
Aulacoceras reticulatum Hauer,
near

Vlth aj

ries, M

m

SUBCLASS II

DIBRANCHIATA

681

convex toward the front ; closely resembling Orthoceras. Septa rather distantly
spaced ; sipliuncle marginal, thin ; proostraciim unknown. Guards of this genuH
are rare, biit detached phragmacones are not unconunon. Upper Alpine Trias.

Atractitas Gümbel. Like Äulacoceras, but guard large, smooth and witliout lateral
furrows. Phragmacone either smooth, or with fine asymptotic lines, and dorsal area

marked with extremely fine
growth - lines, convex toward
the front. Guards and phrag-
macones almost always occiir
detached. The latter were
originally mistaken for Ortho-
ceratites, but are distinguished
by their marginal siphuncle
Hü-iiivGiaMMiu -; xeAruniiim. ^^^b^xw^kh ^nd characteristic conothecal

Striae. Upper Trias and Lias
of the Alps ; also Trias of
California.

Fig. 1315.

A, Vertical section of a Belemnite, the proostracum broken away
above the phragmacone. li, Belemnites hrugierianuH Miller. Lower
Lias ; Charmouth, England. Impression of complete individnal. Vs
(after Huxiey). ö, Restoration of a Belemnite shell.

Abbreviations : R, Rostrum or "guard"; l'h, Phragmacone; Po,
Proostracum ; a, Apical line reaching from apex of guard to bottom of
alveolus («) ; h, Impression of arms ; c, Camerae of phragmacone ; i, An-
terior end of proostracum ; o, Protoconch ; si, Siphuncle ; x, Ink-bag.

Fig. 1316.

Belemniteft compressus. Lias ;
Gundershofen, Alsace.
Phragnuicoiie with well-pre-
served conotheca. «, Asymp-
totic line ; h, Hyperbolic
area ; v, Ventral area.

Xiphoteuthis Huxiey. Middle Lias ; England. X elongata Huxiey.

Belemnites Lister (Figs. 1315-1319). Name first applied by Agricola in 1546.
Guard dactyliform, subcylindrical or conoidal, sometimes short and tliick, sometimes
slender and much elongated ; retral portion tapering, submucronate or obtusely
rounded. Owing to irregularity in secretion of calcite layers on the periphery of the
guard during growth, individuals belonging to the same species but of diflerent ages
frequently dilfer considerably in form. Such differences are well illustrated in />.
acuarius Schloth. The young are sometimes fusiform, l)ut grow cylindiical or
conical with age. About 350 species are known, ranging from the Lower Lias to

MOLLUSCA— CEPHALOPODA

PHYLUM VI

682

Distribution world-wide , most abimciant ^i , ^^ .^^^^ ^^^^.^ ^^ ^^^^ j^^^^

"* a a ?> and Cretaceous, this genus

®S) »^ ig scarcely less important
than the Amnionites.

Subgenera : Pachyteuthis
Bayle (Fig. 1318, A). Guard
perfectly smooth. Confined
to tbe Lower Lias. B. acutus
Mill.

Megateuthis Bayle {Dac-
fA/loteuthis Bayle, PaxiUosi)
(Fig. 1318, B). Apex of
the guard with two or tbree

Fio. 1317.
Belemnites {Duvalia)
dilatatus Blv. Neo-
comian ; Justithal,
Lake of Thuti, Switzer-
land.

I

Fig. 1318.

A, B. (Pachyteuthis) acutus Miller. Lower
Lias ; Lyme Regis, Dorsetshire. B, B. {Mega-
teuthis) paoällosus Schloth. Middle Lias ; Metzin-
gen, Würtemberg. C, B. {Pseudohelus) bipartitus
Blv. Lower Cretaceous ; Castellane, Basses
Alpes, a, h, c, Dorsal and ventral aspects and
cross-section, l/j. D, B. {Belemnopsis) canalica-
latus Schloth. Inferior Oolite ; Würtemberg.
E, B. (Belemnojms) hastatus Blv. Oxfordian ;
Dives, Calvados.

Fig. 1319.
Belemnites {Actinocamax) qnad-
ratus (Blv,). Upper Creta-
ceous ; Germany. A, Dorsal
View of guard with defonned
phragmacone projecting from
alveolus. B, Ventral aspect of
guard. C, Alveolus from above
(after Schlüter).

usually Short grooves. Middle Lias to Lower Cretaceous. B. paxülosus and B. giganteus
Schloth. ; B. elongatus Mill. ; B. subquadratus Roem., etc.

Belemnopsis Bayle (Hibolühcs Montf. , Gastrocoeli, Canaliculati, Hastati) (Fig. 1318, D, E).
Guard with deep and usually long ventral furrow extending from alveolar niargin toward the
apex, with or without dorso-lateral lines. Middle Jura to Middle Cretaceous. B. canaliculatus
Schloth. ; B. absolutus Fisch. ; B. unicanaliculatus Zeit. ; B. minimus Lister.

Pseiulobelus Montf. (Bipartiti) (Fig. 1318, C). Guard thin, slender, with deep dorso-
lateral grooves, with or without ventral furrows. Upper Lias to Lower Cretaceous. B. exilis
d'Orb. ; B. bipartitus Blainv.

^ Actinocamax Miller {Gonioteuthis Bayle) (Fig. 1319). Guard cylindrical, submucronate,
with Short but very deep ventral furrow ; anterior end foliaceous, and very liable to dissolu-

SUBCLASS II

DIBRANCHIATA

683

Fig. 1321.
Diploconus belem-

nitoidea Zittel,
thoiiian

Ti-

Straraber"

tion. Phraginacone only very slightly inserted in the guard, the two portioiis usually
separated by an mterval. Middle and Upper Cretaceous. B. suhvcntricosus Wahlb. ; B.
quadratus lilainv.

BelemnitcUa d'Orb. (Fig.
1320). Guard cylindrical, with
sliort, deep ventral furroAV fall-
ing short of the alveolar margin,
Pliragniacone inserted in guard.
Vascular impressions often
beautifully preserved. Upper
Cretaceous.

Diploconus Zitt. (Fig.
1321). Guard short, obtusely^
conical, and liaving a coii-
centric lamellar structure, not
radial and fibrous. Phragma-
cone reaching nearly to the
posterior end of the giiaid.
Tithonian.

Bayanoteuthis Mun.-
Chalm. Guard long, cylind-
rical, mucronate, with shallow
lateral grooves. Dorsal area
rougheried. Pliragmacone very
slender and long, oval in
section. Eocene ; Paris Basin
and Ronca, Italy. B. rugifer
Schloenb.

Vasseuria Mun. - Chalm.
Guard slender, elongated-
conical, with a nuniber of
longitudinal grooves extending

from the apex. Pliragmacone more than one-half as long as the guard. Septa
oblique, their necks extending from one septum to the next. Very rare in the Eocene
of Brittany.

Belemnosis Milne Edw. Very rare in the English Eocene. Styracoteuthis Crick.
Intermediate between Belemnitella and Bayanoteuthis. Eocene ; Arabia.

Beloptera Blainv. (Fig. 1322). Guard short and somewhat s wollen at its forwaixi
end, which makes a slight angle with the pliragmacone ; on either side it is expanded
into a conical projection. Eocene.

Belopterina Mun.-Chalm. Like Beloptera, but without the lateral wing-like
expansions. Eocene.

Fig. 1320.

Belemnitcs (Belemnitella) mucronatus
Schloth. Upper Cretaceous ; Drenstein-
furth, Westphalia. A, B, C, Ventral, dorsal
and lateral aspects. 2/3,

Fig. 1322.

Beloptera belem-
nitoidea Blv. Calcaire
Grossier ; Paris Basin.
Ventral aspect.

Family 2. Belemnoteuthidae Zittel.

Shell composed of a conical phragmocone and proostracum, the guard being reduced
to a thin calcareous or horny Investment of the phragmacone. Ten arms of nearly equal
length, each heset with a double row of hooJcs. Ink-sac present. Trias and Jura.

Acanthoteuthis Wagner and Münst. {Belemnites Quenst. p.p. ; Ostracoteiithis Zitt.)
(Figs. 1323-1325). Phragmacone with numerous septa, and siphuncle having short
siphonal funnels ; enveloped externally in a thin granulär calcareous layer represent-
ing the guard. Surface of proostracum divisible into a broad dorsal, and two narrow
lateral areas which are longitudinally striated and taper toward the front. Dorsal
area ornamented witli fine parabolic and also straight longitudinal liiies ; anterior

684 MOLLUSCA— CEPHALOPODA phtldm vi

margin rounded. An iniprÄssion of the animal found in the Lithographie Stone

■X\

(f' f ^

Fio. 1324.

Acanthoteuthis speciosa
Münst. Lithographie
Stone; Bichstiidt. A,
Impression of shell, the
proostracum accident-
ally bent sidevvays. Jl,
rrnoslracuni showing
septa and siphonal
funnels, 2/3.

-Ä*-Ä

VA it5

bw"

Fl(i. 132:

A canthotruthü speciosa
Münst. Lithographie,
Stone ; Solenhofen. Pro-
ostracum. 2/„^

Fig. 1323.
AcantlwteutMs speciosa Münst. Lithographie
Stone ; Eichstädt, Bavaria. Impression of arms
and body. 1/2.

shows an ink-bag and ten powerful arnis about the liead,
which are beset witb two rows of opposite, liorny, falciforni
liooklets. Upper Jura.

Phragmoteuthis Mojs. (Fig. 1326). Proostracum twice
as long as the conical phragmacone, with dorsal area
bounded by asymptotic lines, and two shorter lateral areas ;
anterior margin of all areas rounded. Phragmacone invested
by a brownish horny layer representing the guard. Trias
(Raibl Beds).

Belemnoteuthis Pearce {Gonoteuthis d'Orb.) (Figs. 1327-
1328). Like Acanthoteuthis but with smaller and curved
pliragmacone, which is not produced into a long proostracum.
Upper Callovian and Lower Cretaceöus.

Family 3. Spirulidae Zittel.

Shell reduced to a chamhered phragmacone coiled into a flat
Spiral, the coils not in contact ; situated in posterior pari of
the hody, and the greater portion contained within the mantle. In

SÜBCLASS II

DIBRANCHIATA

685

addition to the cight arins, hvo long tentacles vnthout hooJcs arc ijlaced between the third
and foitrth pairs. Oligocene to Recent.

^ ,#.

¥>}

Fig. 1326.

.(, PhragmoteutMs bisintiMta
(Bronn). Trias ; Raibl, Car-
inthia. Ph, Phragmacone ; l'o,
ProostracTim ; L, Lateral area
of proostracuin ; d, Ink-bag.
B, Hooklets of arnis, i/i (after
Suess).

Fio. 1327.

Bclcinnoteuthis antiqua
Pearce. Oxford Clay ; Chris-
tian Malford, Wilts. A, Partly
restored specimen, i/.j. oc,
Eyes ; m, Mantle. " Other
letters as in Fig. 132(i. B,
Hooklet, -^/i (after Mantell).

Fio. 1328,

Bdemnoteuthis sp. Oxford Clay ; Gam-
melshausen, Würtemberg. A, ü, Dorsal
and ventral aspects. B, Septum and
siphuncle.

Fig. 1329.

SpiruUrosim bellardü (Mich.). Mio-
cene ; Superga, near Turin, Italy. A,
Side View. B, Longitudinal section. R,
Guard ; Ph, Phragmacone. i/j (after
Munier-Chalmas).

SpiruUrostra d'Orb. (Fig. 1329). Shell composed of a
short triangulär pointed guard, which is excavated anteriorly
for the reception of the chambered phragmacone. The latter
begins as a spiral, but speedily becomes straight, and has
sejita pierced on the concave ventral side by the marginal
siphuncle. Only one species. Oligocene of Westphalia and
Upper Miocene of Turin.

SpiruUrostrina Canavari. Like the preceding, but guard
reduced to two small, lateral wing-like appendages. Neocene
of Sardinia.

SpiriUa Lain. (Fig. 1330). Shell thin, guard wanting.
Chambered phragmacone enrolled with the ventral side
concave, the coils not in contact, composed of nacreous sub-
stance ; septa concave ; protoconch globular
ventral and marginal in position, the septal necks directed "lencement of siphuncle;

ö A T-, . 1 -r. ?'> Prosiphon ; .<!, Sii)huncle

backwards between the septa. Prosiphon present. Recent ; (after Munier-Chaimas).

Fig. 1330.

Spinila peronii Lara.
Recent ; Pacific. Longi-
c,- -r 1 tiidinal section, i/i. a, Pro-
biphuncle toconch ; c, Caecal com-

686

MOLLUSCA-CEPHALOPODA

PHYLUM VI

• loHf- troi.icil scas For description of the animal see Keport on Spirula by
t^^^ti^:^r, in Appendfx to Ghallenoer Reports, Zoology, part Ixxxm.,

1895.

Order 2. SEPIOIDEA. (Sqiüds and Cuttle-fishes).
Shell internal, without differentiated phragmacone and guard, hui consisting essenti-
allZthTirroostracurn or ^^pen,^' which is either oval or narrow and elongated. Arms
tenin numher, provided with sucJcers or hooks. Inh-hag present.

I

Family 1. Sepiophoridae Fischer.

sepion'' a calcareous, elongated-oval plate, terminating posteriorly in a

and encloses a conical cavity.

Shell or
thickened mucro which represents a rudimentary

Siphuncle loanting.

The thickened posterior mucro is a rudimentary stmcture probably corresponding
^ to the guard of Belemnoids, and

its conical cavity to the alveolus.
Belosepia retains a vestigial cham-
bering but no siphuncle, and in
Sepia a recognisable phragmacone
is wholly wanting. These forms
are undoubtedly descended froni
Belemnoids like Beloptera.

Belosepia Voltz (Fig. 1331).
As a rule only the posterior portion
of the proostracum is preserved.
This ends in a bent spine, which
is thickened anteriorly, laterally
expanded, and contains near the
apejc a conical alveolus. The
latter shows on the dorsal side
incomplete traces of septa, and a
wide funnel - like depression
occupies the place of a siphuncle.
Eocene ; not uneommon in Paris
Basin and the London Clay. Rare
in Claibornian sands of Alabama.
Sepia Lam. (Fig. 1332). Shell
or "pen" of equal length with
the mantle, elongated - oval,
rounded anteriorly, thickened
posteriorly and terminating in a
short mucro. The latter contains
a conical alveolus. Dorsal and
ventral walls of the pen consisting of two brittle calcareous laminae, separated by a
horny layer. Internally with a mass of extremely fine parallel calcareous lamellae,
increasing in thickness anteriorly ; the lamellae separated from one another by
minute vertical rods, thus producing a spongy texture. The familiär cuttle-bone of
commerce, or ossa Sepiae, is the pen of Sepia oßcinalis Linn., and is found in great
quantities along the coasts of certain countries. Several Tertiary species known.

(?) Gampylosepia Picard. Muschelkalk ; Thuringia. Belosepiella De Alessandri.
Eocene : Paris Basin.

Fi(i. 1331.
Belosepi/t hlainvillei Desh.
Eocene ; Auvers, near Paris.
A, Posterior end of Shell,
ventral aspect. B, Same from
the sich; (after Deshayes).

Fio. 1332.

.S'qria officinalis Linn. Recent.
Ventral view of shell. a, Cal-
careous shelly plates represent-
ing vestigial septation. b, Posi-
tion of rudimentary phragma-
cone in front of mucro, '^1^

SUBOLASS II

DIBRANCHIATA

687

Family 2. Ohondrophoridae Fischer.

Internal shell in the form of a much elongated thin plate or jproostracum, divided
lenrjthwise into three areas, composed of conchiolin or of alternating layers of calcareous
and horny matter, thickened posteriorly, and ivith very little trace of any chambered
portion or phragmacone. Jura to Recent.

The ineinbers of this faiuily show a further reduction of the guard and phragmacone
than occurs in the stage represented by Belemnotenthis, and their horny, non-septate

Coccoteuthis Jiastiformis (Rüpp.).
Lithographie Stone ; Eichstädt,
Bavaria.

Fi(i. 1334.

Geoteuthis bollensit, Zieten.
Upper Lias ; Holzmaden, Wiirtem-
berg. Shows ink-bag and cono-
thecal Striae. 1/3.

Fig. 1335.

Beloteuthis schuebleri Qnenst.
Upper Lias ; Holzmaden, Wür-
teniberg. 1/2 (after Quenstedt).

Shells shoiüd be compared with the pen of the common squid or calamary, Loligo
vulgaris Lam.

Coccoteuthis Owen {Trachyteuthis v. Meyer) (Fig. 1333). Proostracum elongated-
oval, composed of calcareous and horny laminae, rounded posteriorly or with but
slightly prqjecting mucro ; external surface roughly granulated, and marked by lines
diverging from the apex. These lines limit the boundaries of two wing-like
expansions projecting from the sides of the elongated median j^ortion. Impressions of
the body and arms are occasionally found in the Lithographie Stone of Bavaria.
Upper Jura.

Leptoteuthis v. Meyer. Proostracum very large, thin, narrowing posterioriy and
composed of several layers of calcareous and horny layers. Median area ornamented
with fine undulating transverse Striae, convex toward the front, and separated from the
lateral areas by longitudinal lines diverging from the apex. Lateral areas marked
with oblique inwardly directed lines, and bordered by lateral expansions which are
widest posteriorly. Upper Jura of Southern Germany. L. gigas v. Meyer.

Geoteuthis Münst. (Fig. 1334). Proostracum composed of thin alternating horny

688

MOLLUSCA— CEPHALOPODA

PHYLUM VI

\>\

v(M-s, widest in front, rounded posteriorly,

^niudinal line, and boimded on either side

hyperbolic Striae. Ink-bag frequently preserved,
Contents transformed into a jet-like substance.

Median area divided into

by lateral areas with

, the

It is

possible to dissolve the carbonaceous particles so as to
prepare a wash resembling India ink. Upper Lias of
Gennany, France and England.

Beloteuthis Münst. (Fig. 1335). Proostracum very
tliin, elongated, feather - shaped, broadly rounded pos-
teriorly, pointed in front, traversed by" a median
longitudinal keel. Upper Lias of Würtemberg.

Teuthopsis Desl. Lias. Kelaeno Münst. Upper
Jura. Phylloteuthis Meek and Hayden ; Äctinosepia
Wliiteaves, Cretaceous ; Cana,da.

Plesioteuthis Wagner (Dorateuthis Crick) (Fig. 1336).
Proostracum very tliin, long, narrow, lanceolate, pointed
posteriorly, rounded in front, with a median longi-
tudinal keel and a raised line along each of the lateral
edges. Very abundant in the Lithographie Stone, and
impressions of the body and head not uncommon. Also
found in the Cretaceous of Maestricht and Syria.

Order 3. OCTOPODA Leach.

Body without internal shell, and only the female of
Argonauta secreting a single- Chamber ed external shell.
The two tentacles are not present, and the eight arms
bear sessile suckers without horny rims. Eye relatively
small, without sphincter-lihe lid. Body short and rounded^
usually without fin-like appendages,

The majority of genera belonging here are naked
and therefore without fossil representatives. The small
male of Argonauta Linn. is without a shell, but the
large female bears a delicate, boat- shaped, spiral shell
which is secreted partly by the mantle, and partly by
two fin-like ex^rnnsions of the dorsal arms. Outer surface
of Shell ornamented by folds and tubercles, and two
nodose ventral keels are present. Late Tertiary (Pied-
mont) and Recent.

Galais J. de C. Sowb. Body short and round,
provided with triangulär lateral fins, not united behind.
I;ili\ely stout tentacular arms, these being of nearly uniform
length and .size, and each bearing a single row of suckers. This is the earliest known
üctopod genua Upper Cretaceous ; Mt. Lebanon, Syria

Fig. 133(;.

Plesioteuthis prism
Lithograpliic Stone ;
A, Impression of aini
arms and iiik-hjt.L;. /;,

(liupi

).

list:MlL
liowin^-

Head

Sil

\v\\

Vertical Range of the Dibranchiata.

A. .•onipaml Mith Totraliranchiates, the Dibranchiata are of minor geological
'"•■'""•• ' l".ir ontuv Organisation renders them less well adapted for preserva-

I 111 t
»ruAini

lir n

:.''■'. '^'."^ ■"■^■"nliiigly WC shall never be able to form even an
,,„,,,,,„,,•. , f ;'"""■. ""l"^'tance m their contemporaneous faunae. The earliest
.op.cu.Ulu. of l>el..nn.o,dea appears in the Trias (Aulacoceras), ^nd the Sepioidea

suBCLASS II DIBRANCHIATA 689

are initiated in tlie Lias. From wliat grouj) Dibranchiates are descended, whether
from tlie Tetrabranchiates or from primitive naked ancestors, \ve bave at present no
certain iiieaiis for deterniining. They appear suddenly in a liigh state of develop-
ment ; biit a still more remai'kable fact is the swift culmination and decline of the
group of Belemnoids. In contrast to the small number of forms met witli in the Trias,
we find even in the Lias, as well as other divisions of the Jura and Lower Cretaceoiis,
a rieh and varied Belemnite fauna. At the close of the Cretaceous only two genera,
Belemnitella and Äctinocamax, persist in relatively large niimbers, and althoiigh a
few antiquated relics of the same stock continue into the Eocene, their rarity
demonstrates waning vitality. The sola living representative of Belemnoids is the
genus Spirula.

In all probability the Sepioidea are descended from Belemnoids. Belosepia of the
Tertiary has tolerably distinct indications of a phragmacone, but in Sepia proper the
septation has become vestigial. Jurassic Chondrophoridae approximate closely to
Recent squids and cnttle-fishes. All the evidenee at our disposal jiistifies the conclusion
that Mesozoic Sej^ioids possessed an essentially similar Organisation to that of Recent
forms,

[For certain changes introduced in the present treatment of Dibranchiate Cephalopods,
as compared witli the original German edition, the Editor alone is responsible,]

VOL. 1 2 Y

Phylum VII. ARTHROPOD A. (Articulates.)

Heteronomously segmented animals with, typically, a pair of appendages to each
somite of the hody ; the whole enclosed in a chitinous segmented exoskeleton, the joint-
ing of which extends to the appendages.

In the Arthropoda the segments are unequally developed, and the
appendages, primitively locomotor in function, may be modified on one or
more somites to subserve special functions, such as the seizure and comminu-
tion of food, respiration, Sensation, copulation, oviposition, fixation, etc.
These modifications of the appendages and the more or less complete union
of the Segments into groups may result in the difFerentiation of three distinct
regions : head, thorax and abdomen. Of these regions the head is concerned
largely in Sensation and feeding, the thorax is chiefiy locomotor in function,
and the abdomen frequently defensive.

The brain lies above and in front of the Oesophagus, and consists of a
fusion of several pairs of ganglia. The rest of the central nervous System con-
sists of a chain of ganglia lying in pairs on the ventral surface, with typically
a pair in each somite. Not infrequently there is a more or less extensive con-
centration or fusion of these ventral ganglia. The eyes may be simple,
aggregate or conipound, with in some cases an inversion of the retinal layer.

■ Respiration in the smaller forms is by the general surface of the body,
whereas in the larger certain regions become specialised for this purpose.
When respiratory outgrowths protrude from the body wall they are known
as gills or hranchiae; when invaginated they are termed lungs if they be
lamellar in arrangement, or tracheae if they consist of fine tubes ramifying
through the tissues.

Excretion is effected either by "segmental organs " (true nephridia)
which open at the inner end into the true body cavity (coelom) and at the
other to the exterior, or by diverticula developed at the hinder end of the
ahmentary canal The nephridia when present occur in only a few segments
of the body. The diverticula of the alimentary canal (Malpighian tubes) are
of two kinds-one developed from the mesenteron, the other from the procto-
(lacum. In all Arthropods the ducts of the reproductive organs are apparently
modified nephridia, and the organs themselves consist of gonads developed
rom the coelomic walls The circulation depends upon a dorsal heart enclosed
na vascular pericardial sac, and metameric blood - vessels terminating in
lacunar spaces. °

Arthropods are divisible into three groups or subphyla, distinguished
.c,„Ml,„. ,„ the natura of the respiratory organs, segmentation of the body,

690

cLAss I CRUSTACEA 691

and structure of the appendages as follows : Branchiata, Myriapoda and
Insecta. These are in turn divided into several classes, all of whicli have
fossil representatives. As to the origin of the Phylum, Paleontology afFords
no certain evidence. The entire Organisation of Arthropods indicates a close
relationship with Vermes, and especially with the group of Annelid Worms ;
nevertheless, the differentiation of the Arthropod type must have antedated
the Cambrian, since several Orders of Crustacea are encountered in the oldest
fossiliferous rocks which are almost as widely divergent from the supposed
ancestral stock as many Recent forms. The relatively late appearance of
Myriapods, which are the most worm-like of all Articulates, may be accounted
for by their terrestrial habitat and the destructibility of their body parts.

SuBPHYLUM A. Branchiata.

Arthropods breathing hy means of gills {or Imigs or tracheae modified from gills)
developed always in connedion with the appendages. Head and thorax rarely distinct,
hut usually more or less completely united in a cephalothorax. The genital duäs
open to the exterior near the middle of the hody, and true nephridia usually occur.
Malpighian tuhes, when present, are derived from the mesenteron. Anterior append-
ages all multiarticulate, the basal joints of one or more pairs serving as organs of
manducation.

The branchiate Arthropods include two classes : Crustacea and Arachnida.

Olass 1. CRUSTACEA.^

Arthropods of usually aquatic habitat, and breathing by gills (exceptionally
through the general body surface) ; with one or two pairs of appendages (antennae) in
front of the mouth, the first of which is purely sensory, and several pairs of post-oral
appendages, some of which are modified into organs of mastication. Appendages with
typically a basal Joint (protopodite) giving rise to two or three branches.

The segmentation of the body is distinct in all except certain parasitic
forms, where it is lost in the adult stage through degeneration. Usually the
demarcation between head and thorax is obscure, and the anterior region of
the body consists of a cephalothorax, the number of whose segments varies
within wide limits ; this being in sharp contrast to the Arachnids, where the
Segments are constantly six in number. The cephalothorax is frequently
covered by a chitinous shell or carapace, developed from the dorsal portion of
the second and third segments, and is frequently strengthened by deposits of
carbonate and phosphate of lime. Although the carapace is usually a single

1 Literature : Brongniart, A., and Bemarest, Ä. O, Histoire naturelle des Cnistaces fossiles
sous les rapports zoologiques et geologiques. Paris, 1822. — Müne Jidioards, IL, Histoire naturelle
des Crustaces, 3 vols. Paris, 1834-40. — Woodward, H., and Salter, J. W., Catalogue and Chart of
Fossil Crustacea. London, 1865. — Woodxoard, H., A Catalogue of British Fossil Crustacea.
London, 1877. — Oerstaecker, A., Crustacea, in vol. v. of Bronn's Classen und Ordnungen des
Thierreichs. Part 1 (Cirripedia, Copepoda, Branchiopoda, Poecilopoda, Trilobita), Leipsic, 1866-
79 ; part 2 (Isopoda to Decapoda), 1881-94. — Vogdes, A. W., A Catalogue of North American
Palaeozoic Crustacea confined to the non-trilobitic Genera and Species. Ann. N.Y. Acad. Sei.,
1889, vol. V. — Grohhen, K., Genealogy and Classification of the Crustacea. Sitzungsber. Akad.
Wiss. Wien, 1892, vol. ci. Translated in Ann. and Mag. Nat. Hist. [6J, vol. xi. — Kingsley, J. S.,
The Classification of the Arthropoda. Amer. Nat., 1894, vol. xxviii. Reprinted in Tufts College
Studies, No. 1, 1894, with bibliography.

ß92 ARTHROPODA phylüm vii

piece, yet in some forms (Estheriiform Branchiopods and Ostracods) it may
consi^t of two lateral valves, which enclose the body like a Pelecypod shell ;
or of four parts, as in certain Phyllocarida ; or again (CuTipedia) of a number
of calcareous plates. The abdomen is usually well developed and its Seg-
ments are free, but occasionally it becomes greatly reduced, as in certain

Entomostraca. . . , . -j t -^ • 4.1,

The total number of body somites varies within wide limits m the
Entomostraca and Trilobita, but in the Malacostraca they are almost constantly
twenty-one, ranging slightly higher in the Phyllocarida, and falling shorter in
the parasitic Laemodipoda. ^ i 1 i •

In all living Crustacea there are two pairs of antennae, although m some
forms (Apus, Oniscids) one or the other pair may become greatly reduced.
In the Trilobites, on the other band, but a single pair has been discovered.
The appendages are exceedingly variable in form, according as they serve
for Sensation, comminution of food (" mouth parts "), locomotion, respiration,
capture of prey or copulation. The primitive form was a lamellar appendage
like those found in the thoracic region of Branchiopods, but the typical leg is
usually stated to consist of a basal portion (protopodite) of one or two joints,
and a distal portion made up of an inner (endopodite) and a lateral brauch
{exopodite). In many cases the exopodite becomes greatly modified or even
entirely atrophied in the adult.

Most of the lower Crustacea escape from the egg in a larval condition
known as the nauplius stage. In the nauplius the body is unsegmented, there
is but a Single median eye, and but three pairs of appendages, correspond-
ing to the two pairs of antennae and mandibles of the adult. The nauplius
gradually becomes metamorphosed into the adult Crustacean, the changes being
accomplished by several moults of the external chitinous crust. In the higher
Crustacea this free-swimming nauplius stage is omitted, the animal already
having the form of the adult as it escapes from the egg. The Decapods have
a larval stage known as the zoea, in which seven pairs of appendages and a
segmented abdomen are present. These larval stages are of great value in
determining relationships, but most modern authorities regard them as adaptive
rather than ancestral; or, in other words, it is not believed that existing
Crustacea are descended from an ancestral form resembling the nauplius.

Two subclasses are recognised : Trilobita and Eucrustacea. The term
Entomostraca is here used in a collective sense to distinguish the lower orders
of Eucrustacea from the highest, or Malacostraca.

Subclass A. TRILOBITA Walch. Trilobites.^

Marine Crustacea, with a variable number of metameres ; body covered with a
hard dorsal shield or crust, longitudinally trilobate into the defined axis and pleura ;

^ Literature : A. General y^ox\i%.—Brongniart, A . , Histoire naturelle des Crustaces fossiles. 1 822.
—Dcdmcm, J. W., Ueber die Palaeaden oder die sogenannten Trilobiten. 1828. — (?reew, J.,
Monograph of the Trilobites of North America, with coloured modeis of the species. 1832.—
Bnrnmster, H V^xii Organisation der Trilobiten. \UZ. — Beyrich, E., Über einige böhmische
Trilobiten, Berlin, 1845-46. -Cor^a, /. C, and Haide, J., Prodrom einer Monographie der
böhmischen Trilobiten. Prag 1847.-^/^, /., Palaeontology of New York, vols. i.-iii., 1847-59.-
ßarmmk J., Systeme Silurien du ceutre de la Boheme, vol. i., 1852 ; Supplement, 1S7 2.— A7igelm,
A. i . , Palaeontologia Scandiuavica. Part i. Crustacea formationis transitionis, 1854. —Neiszkoivsld,
^„Versuch einer Monographie der in den silurischen Schichten der Ostseeprovinzen vorkommenden
irilobiten, im.—Jloßmnn, K, Sämmtliche bis jetzt bekannte Trilobiten Russlands. Vcrhandl.

3nden^
andl.9

süBCLASs I TRILOBITA 693

cephalon, thorax and ahdomen distind. Cephalon covered with a shield composed of
a primitivehj pentamerous middle piece, the cranidium, and two side pieces, or free

Mineral. Gesellsch. St. Petersburg, 1857-58. — Salter, J. W., A Monograph of British Trilobites.
Palaeontographical Society, 1864. — Idem and Woodward, H., Ibid., 1867-84. — Schmidt, F.,
Revision der ostbaltischen silurischen Trilobiten. Mem. Acad. Inip. St. Petersbourg, 1882-1907,
ser. 7, vol. XXX., and ser. 8, vol. xii, — Brögger, W. C, Die silurischen Etagen 2 und 3 in Kristiana-
gebiet und auf Eker, 1882. — Holm, O., De Svenske Arterna af Trilobitslägtet Illaenus. Bihang
Svensk. Vetensk. Akad. Handl., 1882, vol. vii., no. 3. — Matthew, G. F., Illustrations of the
Fauna of the St. John's Group, 1882-93. — Woodioard, H., Monograph of the British Carboniferous
Trilobites. Palaeontogr. Soc, 1883. — Hall, J., and Clarke, J. M., Palaeontology of New York,
1888, vol. vii. — Walcott, C. D., The Fauna of the Lower Cambrian or Olenellus Zone. lOth Ann.
Rept. U.S. Geol. Surv., 1890. — Jaekel, 0., Über die Organisation der Trilobiten. Zeitschr. Deutsch.
Geol. Ges., 1901, vol. liii. — Lake, P., Monograph of British Carabrian Trilobites. Palaeontogr.
Soc, 1906-1913. — Lorenz, T., Beiträge zur Geologie und Paläontologie von Ostasien, der Provinz
Schantung, etc. Zeitschr. Deutsch. Geol. Ges., 1906, vol. Iviii. — Monk, H., Beiträge zur Geologie
von Schantimg. Jahrb. Preuss. Geol. Landesanst. Bergakad., 1905, vol. xxiii. — Moberg, J. C, and
Segerberg, C. 0., Bidrag tili Kannedomen om Ceratopygeregionen med Särskild Hänsyn tili dess
Utveckling i Fogelsangstrakten. Acta Universitatis Lundensis, 1906. — Olin, E., Om de Chasmops-
kalken och Trinucleusskiffern Motsvarande Bildningarne i Skäne. Acta Universitatis Lundensis,
1906. — Raymond, P. E., The Trilobites of the Chazy Limestone. Annais Carnegie Mus., 1905,
1910, vols. iii., vii. — Idem, and Narraway, J. E., Notes on Ordovician Trilobites. Ibid., 1906,
1910, vols. iv. , vii. — Reed, F.R. C, Lower Palaeozoic Trilobites of the Girvan District. Palaeontogr.
Soc, 1903-1906. — Idem, The Lower Palaeozoic Fossils of the Northern Shan States. Burma.
Palaeont. Indica, 1906. — Idem, The Cambrian Fossils of Spiti. Palaeont. Indica, 1910. — Walcott,
G. D., The Cambrian Faunas of China. Proc. U.S. Nat. Mus., 1906, and Smithson. Mise Coli.,
vol. xxix., 1911. — Idem, Cambrian Trilobites. Geology and Paleontology. Smithson. Mise Coli.,
1908-11, vols. liii., iv. — Weller, S., Paleontology of the Niagaran Limestone in the Chicago Area.
Bull. Chicago Acad. Sei., 1907, no. 4.

B. Structure and Appendages : Burmeister, II., vide supra, 1843. — Billings, E., Notes on
some Specimens of Lower Silurian Trilobites. Quar. Journ. Geol. Soc, 1870, vol. xxvi. — Woodxoard,
H., Note on the Palpus and other Appendages of Asaphus from the Trenton Limestone in the
British Museum. Quar. Journ. Geol. Soc, 1870, vol. xxvi. — Walcott, G. D., Preliminary Notice
of the Discovery of the Natatory and Branchial Appendages of Trilobites. 28th Rept. N.Y. State
Mus. Nat. Hist., 1875. — The Trilobite ; New and Old Evidence relatiug to its Organization. Bull.
Mus. Comp. Zoology, 1881, vol. viii. — Novdk, 0., Studien an Hypostomen böhmischen Trilobiten.
Sitzungsber. Böhm. Ges. Wiss., Jahrg. 1879, 1886. — Glarke, J.M., The Structure and Development
of the Visual Area in the Trilobite Phacops rana Green. Journ. Morph ology, 1888, vol. ii. —
Matthew, W. D., On Autennae and other Appendages of Triarthrus beckii. Amer. Journ. Sei., 1893,
(3), vol. xlvi. — Beecher, G. E., On the Thoracic Legs of Triarthrus, ibid., 1893. — On the Mode
of Occurrence, and the Structure and Development of Triarthrus becki. American Geologist, 1894,
vol. xiii. — The Appendages of the Pygidium of Triarthrus. Amer. Journ. Sei. 1894 (3), vol. xlvii.
— Further Observation« on the Ventral Structure of Triarthrus. Amer. Geologist, 1895, vol. xv. —
The Morphology of Triarthrus. Amer. Journ. Sei., 1896 (4), vol. i. — Structure and Appendages
of Trinucleus, ibid., 1895. — Studies in Evolution, New York, 1901. — The ventral integument of
Tribolites, Amer. Journ. Sei., 1902 (4), vol. xiii. — Lindström, G. Researches on the Visual Organs
of Trilobites. Svensk. Vet. Akad. Handl., 1902, vol. xxxiv.

C. Ontogeny : Barrande, J., vide supra, 1852. — Beecher, G. E., The Larval Stages of Trilobites.
Amer. Geologist, 1895, vol. xvi. — MattJiew, G. F., Sur le developpement des premiers Trilobites.
Ann. Soc. Roy. Mal. de Belgique, 1889, vol. xxiii. — vide ante, 1882-93.

D. Systematic Position : Zittel, K. A., Handbuch der Palaeontologie, 1881-85, vol. iii. — Grundzüge
der Paläontologie, 1895. — Lang, A., Text-book of Comparative Anatomy. English Translation by
H. M. and M. Bernard. 1891. — Kingsley, J. S., Tlie Classification of the Arthropoda, Amer.
Nat., 1894, vol. xxviii. — Bernard, H. M., The Systematic Position of the Trilobites. Quar. Journ.
Geol. Soc, 1894-95, vols. 1., li. — The Zoological Position of the Trilobites. Science Progress,
1895, vol. iv. — Woodioard, H., Some Points in the Life-History of the Crustacea in Early Palaeozoic
Times. Quar. Journ. Geol. Soc, 1895, vol. li. — Haeckel, E., Systematische Phylogenie der
wirbellosen Tiere (Invertebrata), 1896. — Beecher, G. E., Outline of a Natural Classification of the
Trilobites. Amer. Journ. Sei., 1897 (4), vol. iii.

E. Classification: Barrande, J., vide suj)ra, 1852. — Beecher, G. E., ante, 1897. — Brongniart,
A., ante, 1822. — Biirmeister, H., ante, 1843. — Gmda, A. J. G., and Hawle, J., ante, 1847. —
Haeckel, E., ante, 1896. — IJalman, J. W., Oiu Palaeaderna eller de sä kailade Trilobiterna
Stockholm, 1826. — Milne Edwards, IL, Histoire naturelle des Crustact's, 1834-40. — Quenstedt,
F. A., Beiträge zur Kenntniss der Trilobiten. Wiegmann's Archiv für Naturgesch., 1837, vol. iii.
— Emmrich, H. F., De Trilobitis. Dissertation, 1839. — Zur Naturgeschichte der Trilobiten, 1844. —

ßg_^ ARTHEOPODA phylum vii

cheeks which may he separate or united in front, and carry the Compound sessile
eyes when present ; cephalk appendages pediform, consisting of five pairs of hmbs,
all hiramous and fumtioning as ambulatory and oral organs, except the simple
aiitemmles, ivhich arepurely sensory. Upper lipforming a well-developed hypostoma ;
umler lip p-esent. Sornites of the thorax movable upon one another, varymg m
numherfrom two to fwenty-nine. Abdominal segments variable in number, andfused
toform a caudal shield. All segments, thoracic and abdominal, carry a pair of
jointed hiramous limhs. All limbs have their coxal Clements forming gnathobases,
which hecome organs of manducation on the head. Respiration integumental and by
branchial fringes on the exopodites. Development proceeding from a protonauplius
form, the protaspis, by the progressive addition of segments at successive moults.

The Trilobites constitute a group of extinct marine animals, and are
related to the stock of the higher modern Crustacea ; they are therefore to be
considered as very primitive Crustaceans. The subclass had its origin in pre-
Cambrian times. Trilobite remains are very abundant in the oldest known
fossiliferous strata, the Cambrian, where they exceed in number and diversity
all other forms of animal life. They continue to be very plentiful during the
Ordovician and Silurian, but decline in the Devonian, and the few last sur-
vivors are found in the Carboniferous and Permian. Probably there have
been more than two thousand species described, distributed among nearly two
hundred genera. These numbers give an idea of the amount of difFerentiation
and specialisation attained by Trilobites during Paleozoic times.

Carapace. — Trilobites were covered or protected on the dorsal side by a
hard crust or shield, which is the only portion commonly preserved. Their
remains, even when fragmentary, are recognisable by the form and structure of
this shield. It is divided longitudinally by two dorsal furrows, or grooves,
into three portions or regions, and on this account the name Trilobite was
first given. The central part formed the axis of the animal, and contained the
principal organs, as the viscera, heart and chain of ganglia. Transversely the
shield is divided into (1) a head portion called the cephalon ; (2) a series of
joints or segments, forming the thorax; and (3) a tail-piece or pygidium,
forming the abdomen.

The test seldom exceeds one millimetre in thickness, and consists of thin
laminae of carbonaceous and phosphatic Compounds of calcium, some of which
were originally chitinous substances. The laminae are frequently traversed

Goldfuss, A., Systematische Übersicht der Trilobiten und Beschreibung einiger neuen Arten
derselben. Neues Jahrb. für Mineral, 1843.— Jf'Coy, F., On the Classification of some British
Fossil Crustacea, with Notices of new Forms in the University Collection at Cambridge. Ann.
Mag. Nat. Hist., 1849 (2), vol. \\.—Chapman, E. J., Some Remarks on the Classification of the
Trilobites as mtluenced by Stratigraphic Relations : with Outlines of a new Grouping of these
Forms. Trans. Roy Soe. Canada, 1889, vol. xii.—Oürich, G., Versuch einer Neueinteilung der
Irilobiten Centralbl Mineral. Geol. Pal., im .-Jaekel, 0., Über die Agnostiden. Zeitschr.
Deutsch. Geol. Ges., 1909, vol. \xl~Pompeckj, /. F., Über Calymmene, Brongniart. Neues Jahrb.,
1898, vol 1 — Äaymonti, P. E., Notes on Parallelism among the Asaphidae. Trans. Roy. Soc.
Canada 1912 (3) vol. v.-7^eerf, F R. 0., Notes on the Evolution of the genus Cheirurus.
Geol. Mag 1896 (4) vol. iy--Idem, Blind Trilobites. Ibid., 1898, vol. y.-Idem, On the British
spec.es of Conocoryphe. lUd., 1900, vol. vii.-7.^m, On some Wenlock species of Lichas. IMd„
inl /i //''" vV^' ??^' ^''^- ^^— ^'^^"^' The Classification of the Phacopidae. Ibid., 1905,
vo 1 v.~Idm, .Notes on he genus Lichas. Quart. Journ. Geol. Soc, 1902, vol. lviii.-/^m, On
1 .^..nns hunu.!..ns .eol. Ma,^, 1912 (5), vol. ix.-Wedekind, R., Klassifikation der Phaco-
\n'U-u. ^/rii.,-l,r. |)..ut^cli. (Icl. (ies., 1911, vol. Ixiii.

rv '," '"'!'''"f.'V'''? ■ ,''T-^*''!\ ^'" !'•' ^ ^^'l-'i'^'^««^ '-^Hd Annotated Bibliography of the Palaeozoic
i-.ru>lac..,,. (Hl. Acad. Sc,, o.cas. Papers, iv., 1893. Supplement in Proc. Cal. Acad., 1895, vol.iv.

SÜBCLAS8 I

TKILOBITA

695

by minute poies, which give a punctate appearance to the test, and which are
sometimes large, as in Homalonotus and related forms.

The carapace is somewhat arched or convex, generally elongate-oval in
form, and usually rounded at both ends. The length is almost invariably
greater than the width. Yery often the same species shows a broad form,
as well as a relatively larger, narrower one. The former was considerediby
Barrande as representing the female, and the latter the male individual. The
carapace is often ornamented with spines, teeth and knobs. These may be of
the nature of surface Ornaments, or in the case of spines, may be produced by
growths from the genal angles, the ends of the segments of the thorax and
pygidium, or the spiniform extension of the pygidial termination.

The carapace does not often terminate at the margin as a simple lamellar
plate, but is turned under, and forms a reflexed margin, or douhlure, which is
parallel to the outer edge, but is separated from the upper surface by a narrow,
partially included space. This produces the hollow spines from the ends of
the Segments, from the genal angles and from the pygidium. In rare instances,
the spines are solid.

The axial lohe, or middle part, is defined by two longitudinal dorsal furrows
extending the whole length of the thorax, and also over more or less ot the
cephalon and pygidium.

The pleura are the two lateral areas on each side of the axis. Thus, there
are pleural cephalic, thoracic and pygidial regions. The name pleuron (in
the Singular), or pleura, is especially applied to the extensions from the axial
portion of each free segment.

The Cephalon. — The cephalon, or cephalic shield (Fig. 1337), includes all
that part of the carapace in front of the thorax. It comprises the hypostoma,
epistoma, the free cheeks bearing
the eyes, the fixed cheeks, and the
glabella ; it is generally semicircular
in form, and is joined along its
posterior margin to the thorax.
The postero - lateral margins, or
genal angles, are frequently drawn
out into spines. Usually there is
an occipital furrow extending across
the cephalon parallel to the posterior
margin, and defining the occipital
ring or segment.

The glabella is the axial portion
of the cephalon, and is defined by
the primary dorsal furrows (Fig.
1337). It shows typically three
oblique or transverse furrows in
addition to the occipital ring, mark-

ing the limits of the original five Consolidated segments, and corresponding to
the paired appendages of the ventral side. Sometimes the positions of the
muscular fulcra are also indicated on the dorsal surface, by short furrows, or by
shallow pits. The glabella may constitute nearly the whole of the cephalon,
as in Deiphon or Aeglina, or it may be narrow, as in Earpes and Eurycare. In
some cases it does not extend over half the length of the cephalon, as in Harpes

Cf',plialon of DalTnanites Jiaiu?vtanni
(Brongt.). Devonian ; Bohemia. l,
Limb or border; fnn, Marginal furrow,
a, Genal snines ; ql, Glabella ; If,
Frontal lobe ; U-ß, Side lobes ; l-S,
Side furrows of glabella ; so, Neck
furrow ; A, Neck ring ; @, Facial
suture ; oc, Visual surface of the eyes ;
p, Palpebral lobe.

696

ARTHROPODA

PHYLUM VII

The hypostoma,^ or labrum,
Crustaceans, and consists of a

Fig. 1338.

Hypostomas.

1^,

A, Corydocephalus palviatus
C, Encrinurus intercostatus, side and front views
fafter Noväk). BB, Anterior edge ; M, Middle
furrow ; E, Posterior furrow of the middle por-
tion ; /', Posterior edge ; L, Lateral edge ; y, Pos-
terior wing.

and Anlacopleura, but it may extend to the frontal border as in Placopana ov
Ceraurus, or even beyond, as in Phacops, Ämpyx and Conoliclms The entire
Portion of the glabella which lies in front of the anterior lateral furrows, and
which is often somewhat enlarged laterally, is called the frontal lobe. Some-
times the limitation between the glabella and fixed cheeks is scarcely defined,
as in Illaenus and Dipleura. Most frequently, however, three pairs of grooves
can be distinguished in front of the neck furrow, marking the pentamerous
division of the glabella and the five pairs of appendages attached to the
cephalon. Sometimes the lateral furrows are continuous across the glabella,
or again, they may be directed obliquely (Triarthms), or even form longi-

tudinal grooves (ConoUchas).

is homologous to the upper lip of other
separate plate attached by an articulating
surface or line to the reflexed border of
the cephalic shield (Fig. 1338).

In front of the hypostoma is a rostral
area sometimes partly occupied by a
separate plate, the epistoma (Illaenus,
Calymene).

The fixed cheeJcs are lateral extensions
from the glabella, to which they are
firmly joined, forming the central portion
of the cephalon. They may occupy more
than two-thirds of the cephalon, as in
Conocoryphe, or may become greatly reduced, as in Lichas and Froetus. The
cranidium consists of the glabella and the fixed cheeks.

The free cheeks carry the Compound eyes, and are separated from the
cranidium by a suture. They may form (a) a continuous ventral plate, as in
Harpes, Agnostus, Crypiolithus, etc. ; they may include (b) a greater or lesser
portion of the dorsal surface, being either entirely separated by the cranidium,
or (c) meeting, and (d) sometimes coalescing in front. They are widely
separated in Ftychoparia, in juxtaposition in Asaphus, and continuous in
Dalmanites.

The geml angles are the posterior lateral angles of the cephalon. They
may be rounded, aS in Illaenus, angular, as in Goldius, or spiniform, as in
Crypiolithus and Dalmanites. They belong either to the fixed cheeks, as in
Dalmanites, or to the free cheeks, as in Illaenus, Goldius and Proetus.

The character of the cheeks is especially influenced by the facial sutures
separating the free cheeks from the rest of the cephalon. They appear
as sharply defined lines beginning either at the posterior margin, or
near the genal angles, or on the lateral margins, and extend to the eyes,
thence around the inner margin of the visual areas, then turn anteriorly, and
either unite in passing around the front of the glabella or remain separate, in
which case the sutures terminate in the anterior margin. The position of the
facial sutures thus determines the relative size of the fixed and free cheeks.
After the death of the animal, or after moulting, the cephalic shield frequently
teil mto pieces, dividing along these sutures.

In most Trilobites, the existence of eyes has been demonstrated, though

BihlnfÄ^k?\EÄ ^^^ einigen skandinavischen Asaplnden.

suBCLASs I TRILOBITA 697

they appear absent altogether in some genera (Conocoryphe, Agnostus), and aje
so imperfectly shown in others that for a long time they remained unrecognised
(Agraulos, Sao, Ellipsocephalus, etc.). The eyes are Compound, and are elevated
above the free cheeks. The adjoining area of the fixed cheeks is also drawn
upwards, thus forming the palpebral lobe. The visual areas of the eyes are
borne by the free cheeks. The shape of this area is extremely variable, but
together with the palpebral lobe it generally forms a truncated, conical or
semilunar elevation, of which the laterally directed, convex side is occupied
by the visual surface (Phacops, Asaphus). It may likewise have a circular or oval
form, and very little convexity above the general surface. The eyes may be
quite small, as in Encrinurus and Trimerocephalus ; large and prominent, as in
Phacops, Dalmanites and Proetus ; or very large, as in Aeglina, in some species
of which nearly the entire area of the free cheeks is faceted, and the visual
surface extends around the entire outer borders of the cephalon. In many of
the primitive genera the eyes are situated at the distal ends of raised lines, or
eye Ums, extending outward from near the forward end of the glabella.

As regards their structure, the Compound eyes of Trilobites are recognised
as of two kinds. In the first, the holochroal, the visual area is covered with a
continuous horny integument, or Cornea, which is either smooth and externally
gives no idea of its Compound nature, or granulär, on account of the facets
beneath. The lenses of the ommatidia are often visible by translucence. The
second type of structure, the schizochroal, is confined to the single family
Phacopidae. In this, the visual area is made up of small, round or polygonal
openings for the separate facets of the Cornea, between which is an interstitial
test or sclera. The size of the facets varies from more than 0*5 mm. in some
of the Phacopidae, to from 6-14 facets in the width of 1 mm. in other Trilobites.
The number and arrangement of the facets also vary greatly according to the
genus. Trimerocephalus volborthi shows only 14 facets, while species of Phacops
may possess from 200-300, and Dalmanites hausmanni has 600. Among the
holochroal eyes, the number of facets is much greater ; in Goldius palifer it is
estimated at 4000, in Ogygites nobilis at 12,000, and in Caphyra radians as high as
15,000. Usually the facets are arranged in regulär, alternating, vertical rows,
or quincuncially.

Certain genera show visual organs of an entirely difFerent type, which can
be best regarded as simple eyes, and correlated with the ocelli of many Crus-
taceans. Thus, the genera Harpes and Tretaspis present from one to three
simple elevations or granules on the fixed cheeks, at the ends of eye-lines,
while the ordinary Compound eyes on the free cheeks are absent.

The Thorax. — In contrast to the undivided cranidium, the thorax consists
of a series of short, transverse, articulating segments, which differ in number
with the genus and species. Every thoracic segment is divided by the dorsal
furrows into a middle portion {axis, tergum) and two lateral divisions {pleura,
epimera). The axial portions are firmly anchylosed with the pleura, and are
generally strongly convex, with the posterior margin incurved. Anteriorly
they bear an extension below the general surface, and separated by a furrow.
This forms a surface of articulation along which the segments are movable, and
is covered by the edge of the segment immediately in front, so that it is chiefly
visible in coiled or disarticulated specimens. Barrande distinguished two
types of pleura : (1) furrowed pleura (püvre ä sillon), which have a diagonal
furrow on the upper surface, running posteriorly from the anterior edge near

ARTHROPODA phylum vii

698

theaxis. and towards the free ^^^^^^ ^SetZcÄ^; ||

^^V;.r It^tlVoTÄ^^^^^^^^^^^^^ 0. inner poHion The

Ivtte^ exende rom the axis to the fulcrum or bend i... to a p ace where the
nleu a bend more or less abruptly downward, and aUo genera y toward the
^ear The dktal portion, beginning at the Merum, may continue o£ equal
Ihkknel and be rounded or obtuse at the extremity, or it may decrease :n

^'"xt nrl:ro;"thri: seg^ents dürers exceedingly among different
genera Z smallest number, two, occurs in Agnostus The largest number
fo £ar observed, twenty-nine, is found in some spemes of Harpes. A Variation
L ^ bfnoted even anfong the .pecies of a single genu. hence this ehar^cter
is not of general application for purposes of Classification. For example,

Fig. 1339. Fi«- l^*^-

PvL'idium of Onygiocaris huchi (Brongt.). Pygidium of Goldüis umhellißr (Beyr.).

Ordovician, Wales. Devonian ; Boliemia.

there are species of Ampyx and Aeglina with five to six thoracic segments,
Fhillipsia with nine to fifteen, Cheimrus with ten to twelve, Cyphaspis with ten
to seventeen, Ellipsoceplialus with ten to f ourteen, and Paradoxides with sixteen
to twenty. In general, there seems to be a sort of mutual relationship
between the number of thoracic segments and the size of the pygidium.
When the latter is large, the thoracic segments are usually few ; but if small,
the number of thoracic segments is large.

The Pygidium. — The abdomen of Trilobites is commonly known as the
pygidium (Fig. 1339), though sometimes styled the caudal shield or plate. It
consists of a single piece, with an arched upper surface, upon which may be
distinguished regularly a median axis and two lateral parts, or pleural lobes,
marked more or less distinctly by transverse furrows. Sometimes it bears
considerable resemblance to the cephalic shield {Agnostus, Eodiscus). The
pygidium evidently originated from the anchylosis of a number of similar
segments. The potential segmentation is often so strongly marked that it is
very difficult to recognise the dividing line between the thorax and pygidium,
except in disarticulated specimens. Sometimes the evidences of segmentation
disappear entirely or are but faintly indicated on the lower side. When
segmentation along the axial and lateral lobes is weak, the pygidium differs
considerably in appearance from the thorax.

The axiü may extend as far as the posterior end of the pygidium, or to

süBCLASS I TRILOBITA 699

any part of the length, but is sometimes reduced to a short rudiment {Goldius,
Fig. 1340), or it may be even eritirely obscured (Nileus). The number of
axial Segments normally correspoiids to the number of pygidial, and varies
between two and twenty-eight. On the lateral lobes, all or at least a part of
the pleura may also be seen, being continued from the axis as ribs separated
by furrows. In these cases, the furrowed and the ribbed pleura can usually be
distinguished, but not infrequently they have entirely disappeared as surface
features. Many of the Cambrian Trilobites are conspicuous for their small
pygidium and elongated thorax.

The outline of the pygidium is most frequently semicircular, parabolic or
elliptical ; more rarely it is triangulär or trapezoidal. The margin is entire,
less commonly dentate or spiny. The border, as in the case of the cephalon
and the pleura of the segments, has a reflexed margin, or doublure, which in
some genera attains considerable width.

The Ventral Side. — The ventral side of Trilobites is commonly inaccessible
for purposes of Observation, since, as a rule, it is so firmly attaehed to the
rock that the organs, even though present, cannot be exposed by the ordinary
methods. Furthermore the appendages and ventral structures are so thin
and delicate that the most favourable conditions are necessary for their pre-
servation. For this reason, great uncertainty has prevailed regarding the
presence and character of the legs and various appendages. After a careful
preparation of their inferior side, by far the larger number of Trilobites show
only the vacant hollow space beneath the dorsal shell, and the hypostoma
attaehed to the reflexed margin of the cephalic shield. This common condition
of the fossils led Burmeister, in 1843, to the assumption that all organs on
the lower side, as in Phyllopods, were originally soft and fleshy. Previous
to this, however, Linnaeus, in 1759, described what appeared to be antennae,
and Eichwald, in 1825, announced both antennae and legs. Altogether the
early literature down to 1870 contains quite a number of claimants for this
discovery. Most of the evidence is manifestly ^'erroneous, and the two or
three cases which bear some semblance of validity are too obscure to be of
any scientific value.

Billings, in 1870, published the description and figure of an unusually
well-preserved Isotelus gigas from the Trenton Limestone of Ottawa, Canada.
The ventral side of the specimen showed eight pairs of jointed legs on each
side of a median furrow. Soon after. Woodward described an antenna or
pediform cephalic appendage, lying beside the hypostoma of another individual
of the same species. Through the investigations of Walcott (1875-94) on
Ceraurus and Calymene, by means of transverse and longitudinal sections
of enroUed specimens, a number of problems have been settled as to the
characters of the ventral

side. It is now known c .^^^^^^.^^^^ i

that Trilobites possessed f , --.^..^i*"^'''^^''**''^'^^*^ -"^^

a thin, external, ventral I \ m. ^ "^^^^^^^^^v

membrane attaehed to the ^^^^ „ ,„,,

, ^^^^ Fig. 1841.

renexea margm OI tne Median vertical section of Ceraurus plpurexantliemus Green, c,

cephalon thoracic SeßrmentS Coplialon witli hypostoma below ; tu, Moiith ; Vy Ventral membrane ;

" .' ° ;, Intestinal canal ;;<(/, Pygidium (after Walcott).

and pygidium. it was sup-

ported by transverse processes which became thickened with age, and to

these the legs were attaehed.

^^Q ARTHROPODA phylüm vii

^tudwitrÄr^^^^^ to its termination in the anal open.ng at the

^•^'Z; :fth1 :tÄ— 'l^Sowledge of Mobite s«. have
con.e ffom the study o£ numerous very perfectly preserved specimens of

Triarthrus becki Green.

Fio. 1342.

Utica Sliale (Ordovician) ; (Rome, New York.
2/1 (after Beecher).

A, Dorsal, and B, Ventral aspect,

Triarthrus hecki Green, from the Utica Shale (Ordovician), near Rome, New
York. Undoubted antennae in this form were discovered by Valiant, and first
announced by Matthew in 1893. Subsequently a series of papers was
published by Beecher on the detailed structure of this Trilobite, which is now
the best known of any species, and necessarily forms the basis of much of the
following summary of ventral organs.

In the median line anteriorly, there is first the hypostoma or upper lip, at
the end of which, and opening obliquely back ward, is the mouth (Walcott, in
Calymene). In Triarthrus the lower lip, or metastoma, is a convex arcuate
plate, just posterior to the extremity of the hypostoma. At the angles on
either side are two small elevations, or läppe ts.

SUBCLASS I

TRILOBITA

701

Pairecl Appendages, — All segments of the cranidium, thorax and pygidium,
except the anal segment, carry appendages, all of which are l)iramous save the
anterior pair. The anterior
antennae, or antennules, are
attached at the sides of the
hypostoma, and consist of a
simple, many-jointed flagel-
lum (Fig. 1342). The
caudal rami of the Cambrian
genus Neolenus (Fig. 1343)
are long, slender, jointed
and attached to the last
segment of the pygidium.

The typical Trilobite
leg has two branches arising
from a basal Joint, or coxo-
podite, which is prolonged
into a gnathobase. The ^^^ i343

inner brancn, or endOpOdlte^ NeoUnus serratuß Romlnger. Middle Canibiiaii ; Burgess Pass,
has typically Six jointS. g-C.^ Microphotograph showing elongate x */i

The outer brauch, or exo-

podite, has a long proximal Joint, with a distal multiarticulate portion, or
the proximal Joint may be flat and elongate, forming the entire exopodite,
as in Neolenus (Fig. 1343). Long setae extend posteriorly, and on the distal
portion they are so crowded as to make a conspicuous fringe, imparting a
characteristic appearance to the leg.

Besides the antennules, the cephalon bears four pairs of pediform biramous
appendages, with large gnathobases functioning as manducatory organs. Of

Fig. 1344.

Triarthriis hrr]:i r;tcen. a, Restored thoracic limbs in transvpisi
soction of tlic .uiimal ; }>, Section across anterior portion of pygidium
c, Section across ])(jslt'rior portion of pygidium (aftcr Eeoclier).

Fio. 134Ö.

Triarthrus becki Green.
Dorsal view of second thoracic
leg, with and withoxit setae and
without gnathobase. e7i, Endo-
l)odite ; ex, Exoi)odite (after
Beccher).

these the first may be correlated with the posterior antennae of higher Crustacea.
In structure and function they are true mouth appendages, like the second
pair of nauplius limbs. The second pair, corresponding to the mandibles of
higher forms, and the third and fourth, corresponding to maxillae, have the
same structure as the first, with large gnathobases and fringed exopodites.
The thoracic and abdominal limbs are of the same biramous type. The endo-

702

ARTHROPODA

PHYLUM VII

podites are jointed, crawling legs ; posteriorly, especially on the pygidium,
the joiiits become flattened and leaf-like, carrying tufts of setae, and being
adapted for swimming. .

The exopodites are fringed along their posterior edges with narrow,
oblique lamellar elements becoming filiform at the ends, thus Converting the
limb into a swimming organ, and probably also serving respiratory functions

(Figs. 1343, 1346). ^ . . i.^ -,. .

Hahits.—\n the absence of any closely allied recent forms, it is difficult to
reach definite conclusions respecting the manner of life of Trilobites, except

Fig. 1346.

Cryptolithus tessellatus Green. Utica Shale (Ordovician) ; Rome, New York. A, Left half of pygidium and
three thoracic segments, with test removed, and showing fringes of the exopodites. B, Ventral aspect of same.
tt, Endopodite ; b, Exopodite. lo/i (after Beecher).

such as are based upon their Organisation and mode of occurrence. They were
undoubted marine animals, since their remains are found only in salt-water
deposits, associated with brachiopods, cephalopods, crinoids, and other typical
oceanic forms. Some species are plentiful in calcareous or argillo-calcareous
deposits, with thick-shelled brachiopods, gastropods and reef-building corals,
which evidently did not live at any considerable depth. Other forms appear
to have been bottom crawlers, frequenting either muddy or sandy bottoms ;
and again, others like Cryptolithus, lived partly buried in the soft mud. On
the other band, many species indicate, from the absence of visual organs, a
comparatively deep-water habitat. The structure of the appendages of many
was probably such as to permit of both swimming and
crawling, as in a number of families of modern Crustacea,
and they were therefore restricted neither to the shore
nor to the bottom. This doubtless explains the occur-
rence of the same species in very different Sediments.

Power of Enrollment.— The bodies of most Trilobites

were capable of being roUed up completely like many

Fia 1.347. ^^ ^he Isopods (Fig. 1347). In the enrolled condition

caiyimne mseH Foerste. ^^^ m^rgin of the pygidium is closclv applied to the

SSXlSr"'^'''^''''^- doublure of the cephalon, thus entirely concealing the

ventral side of the body. The thoracic segments over-

lap, and admit of more or less motion upon one another. The pleura also

SÜBCLASS I

TRILOBITA

703

imbricate, and their fulcra are provided with facets upon which the fulcra of
adjacent segments impinge. The ends of the pleura thus protect the ventral
surface along the sides, when the animal is enrolled. Some forms appear to
have possessed the power only to a limited degree. In these, the creature is
usually found extended, and the facets on the fulcra are either rudimentary
or absent.

Ontogeny. — Minute spherical or ovoid fossils associated with Trilobites
have been described as possible Trilobite eggs, but nothing is known, of
course, of the embryonic stages of the animals themselves. The smallest and
most primitive organisms which have been detected, and traced by means of a
series of specimens through successive changes into adult Trilobites, are little
discoid or ovate bodies not more than 1 mm. in length. This first larval form
has been named the protaspis, and has been found to be the typical larval form
characteristic of all Trilobites. It is believed to approximate the protonauplius
form, or the theoretical, primitive, ancestral, larval form of the Crustacea.

The simple characters possessed by the protaspis are the following, as
drawn from the study of this stage in all the principal groups of Trilobites : —
Dorsal shield minute, not more than 0*4 to 1 mm. in length ; circular or ovate in
form ; axis disti7ict, more or less strongly annulated, limited by longitudinal grooves ;
head portion predominating ; axis of cranidium with five annulations ; abdominal
portion usually less than one-third the length of the shield ; axis with from one to
several annulations ; pleural portion smooth or grooved ; eyes, when present, anterior,
marginal or submarginal ; free cheeks, when visible, narrow and marginal.

The changes taking place during the growth of an individual are chiefly
the following : — Elongation of the body through the gradual addition of the
free thoracic segments ; development of the pygidium ; translation of the
eyes, when present ; modifications in the glabella ; growth of the free cheeks ;
and final assumption of the mature specific characters of pygidium and
ornamentation.

In a Classification of the stages of development, the protaspis has the rank
of a phylembryo, and corresponds in value to the protoconch of cephalopods,
the prodissoconch of pelecypods, and the protegulum of brachiopods. In its
geological history and the metamorphoses it undergoes to produce the perfect
Trilobite, accurate information can be gained as to what the primitive char-
acters are, and the relative values of other features acquired during the long
existence of the class.

Of the developmental stages after the protaspis, the nepionic may be con-

Fio. 1348.

Ptychoparia Jdngi Moek.
Cambriaii. A, Protaspis en-
lar^Rfl. B, Adult reduced.

Fia. 1349.

Sao hirsuta Barr. Cambrian.
^, Protaspis enlarged. ü, Adult
reduced.

Fio. 1350.

Triarthrus becki Green.
Ordovician. A, Protaspis en-
larged. B, Adult reduced.

sidered as including the animal when the cephalon and pygidium are distinct,
and the thorax incomplete. There would thus be as many nepionic stages as
there are thoracic segments. The neanic stages would be represented by the
animal with all parts complete, but with the average growth incomplete.

704

ARTHROPODA

PHYLUM VII

Final pro^^ressive growth and development of the individual would fall under
the'epheblc stage. Lastly, general evidences of senility would be interpreted
as belonging to the gerontic stage.

Morphogeny. During the protaspis stage, several moults take place before

Fig. 1351.

Proetus jxirviuscuhis Hall.
Ordovician. A, Protaspis
mnch enlarged. B, Adult
slightly enlarged.

Fio. 1352.

Acidaspis tuberculata

Conrad. Devonian. A,

Protaspis enlarged. B,

Adult reduced.

Fig. 1353.

Dahnanitina socialis (Barr.).
Ordovician. A, Protaspis en-
larged. B, Adult reduced.
(Figs. 1348-1353 after Beecher.)

the complete Separation of the pygidium or the introduetion of thoracic Seg-
ments. These bring about various changes, namely, the stronger annulation
of the axis, the appearance of the free cheeks on the dorsal side, and develop-
ment of the pygidium by the introduetion of new appendages and segments,
as indicated by the additional grooves on the axis and limb. In the earliest,
or Cambrian genera, the protaspis stage is by far the simplest expression of
this period to be found. In the higher and later genera, the process of
acceleration or earlier inheritance has pushed forward certain characters until
they appear in the protaspis, thus making it more and more complex.

Taking the early protaspis stages in Solenopleura, Liostracus or Ptychoparia,
it is found that they agree exactly with the foregoing diagnosis in its most

elementary sense. Since they are the

characters shared in common by all larvae

^T?\ I MJ 1!^^ ^^ ^^^^ stage, they are taken as primitive,

Wjl 'yW ^r ^^^ accorded that value in dealing with

I 0 *^ adult forms possessing homologous features.

^ Therefore, any Trilobite with a large elon-

gate cephalon, eyes rudimentary or absent,

free cheeks ventral or marginal, and glabella

long, cylindrical, and with five annulations,

would naturally be placed near the begin-

ning of any genetic series, or as belonging

to a very primitive stock.

Next must be considered the progressive
addition of characters during the geological
history of the protaspis, and the ontogeny
of the individual during its growth from
., . , condition. It has been shown by Beecher that

there is an exact correlation to be made between the geological and zoological

nrofTi'if?.^ important structures not especially noticeable in all stages of the
o m anvn l"" ?^' \^''^ ^^^""^ ^^^^^^«^ themselves in the meta-

Visual areas of the eyes, when such are present, their appearance on the dorsal

Fio. 1354.

Sfto hirmta Barrande. Cambrian ; Skrey
Bohemia. A, Protaspis. B-F, Nepionic stages
of development (after Barrande).

the larval to its mature

SUBCLASS I

TRILOBITA

705

shield is practically simultarieous with these organs, and before the eyes have
travelled over the margin, the free cheeks must be wholly ventral in position.
When first discernible, they are very narrow, and in Ptychoparia and Sao,
include the genal angles. In Dalmanites and Cheirurus, however, the genal
angles are borne on the fixed cheeks.

Since the free cheeks are ventral in the earliest larval stages of all but the
highest Trilobites, and as this is an adult feature among a number of genera,
which on other grounds are very primitive, this is taken as generally indicative
of a very low rank. The genera Harpes, Agnostus, Cryptolithus and their allies
agree in this respect, and constitute the Hypoparia.

The remaining genera of Trilobites present two distinct types of head
structure, dependent upon the extent and character of the free cheeks. In
both, the free cheeks make up an essential part of the dorsal crust of the
cephalon, being continued on the ventral side only as a doublure or infolding
of the edge, similar to that of the free edge of the cranidium, the ends of the
thoracic pleura, and the margin of the pygidium. They may be separated
only by the cranidium, as in Ptychoparia; by the cranidium and separate

AB CD

Fig. 1355.

Ontogeny of Sao Mrsuta Barr. (Opisthoparia) A, Protaspis. B, Cephalon of nepionic individual. C, Cephalon of
later nepionic individual having eight free segments. D, Cephalon of adult (froni Beecher, after Barrande).

epistomal and rostral plate, as in Illaenus and Homalonotus ; or they may be
united and continuous in front, as in Aeglina and Dalmanites. One type of
structure is distinguished by having the free cheeks include the genal angles,
thus cutting ofF more or less of the pleura of the occipital segment. The
genera belonging to this group constitute the second order — the Opisthoparia.

The third and last type of structure includes forms in which the pleura of the
occipital segment extend the füll width of the base of the cephalon, embracing
the genal angles. The free cheeks are therefore separated from the cranidium
by sutures cutting the lateral margins of the cephalon in front of the genal
angles. Genera having this structure are here placed in the order Proparia.

The characters still to be noticed have chiefly family and generic values,

Fig. 135G.

Onlogeny of Dalmanitina socialis (Barr.). (Proparia) A, Protaspis. B, Cephalon of individual of three free
Segments. C, Cephalon of one with seven free segments. D, Cephalon of adult (from Beecher, after Barrande).

and are of great assistance both in determining the place of a family in an
Order and the rank and genetic position of a genus in a family.

There is very satisfactory evidence that the eyes have migrated from the
ventral side, first forward toward the margin, and then backward over the
cephalon to their adult position. The most primitive larvae should therefore
VOL. I 2 z

706

ARTHROPODA phylüm vii

present no evidence of eyes on the dorsal shield. Just such conditions are
fulfilled in the youngest larvae of Ptychoparia, Solenopleura and Liostracus.
The eye-line is present in the later larval and adolescent stages of these genera,
and persists to the adult condition. In Sao it has been pushed forward to the
earliest protaspis, and is also found in the two known larval stages of Triar-
thrus. Sao retains the eye-line throughout life, but in Triarthrus the adult has
no trace of it. A study of the genera of Trilobites shows that this is a very
archaic feature, chiefly characteristic of Cambrian genera, and only appearing
in the primitive genera of higher and later groups. It first develops in the
later larval stages of certain genera (Ptychoparia, etc.) ; next in the early larval
stages (Sao) ; then disappears from the adult stages (Triarthrus) ; and finally
is pushed out of the ontogeny (Dalmanites).

In Ptychoparia, Solenopleura, Liostracus, Sao and Triarthrus, the eyes are
first visible on the margin of the dorsal shield after the protaspis stages have
been passed through, and later than the appearance of the eye-lines ; but in
Proetus, Acidaspis, Ceratarges and Dalmanites, through acceleration, they are
present in all the protaspis stages, and persist to the mature or ephebic condi-
tion, moving in from the margin to near the sides of the glabella. Progression
in these characters may be expressed, and in so far taken for general applica-
tion among adult forms to indicate rank, as follows : — (1) Absence of eyes;
(2) eye-lines ; (3) eye-lines and marginal eyes ; (4) marginal eyes ; (5) sub-
marginal eyes ; (6) eyes near the pleura of the neck segment.

The changes in the glabella are equally important and interesting.
Throughout the larval stages the axis of the cranidium shows distinctly by
the annulations that it is composed of five fused segments, indicating the
presence of as many paired appendages on the ventral side. In its simplest
and most primitive state it expands in front, joining and forming the anterior
margin of the head (larval Ptychoparia and Sao). During later growth it
becomes rounded in front, and terminates within the margin. In higher
genera, through acceleration, it is rounded and well defined in front, even in
the earliest larval stages, and often ends within the margin (larval Triarthrus
and Acidaspis), From these few simple types of pentamerous glabellae, all
the diverse forms among species of various genera have been derived, through
changes affecting any or all of the lobes. The modifications usually consist in
the progressive obsolescence of the anterior annulations, finally producing a
smooth glabella, as in Illaenus and Niohe. The neck segment is the most per-
sistent of all, and is rarely obscured. The third or mandibular segment is
frequently marked by two entirely separate lateral lobes, as in Acidaspis, Cono-
lichas, Chasmops, etc. Likewise, the fourth annulation carrying the first pair
of maxillae is often similarly modified in the same genera, also in all the
I'roetidae,^ and in Cheirurus, Orotalocephalus, Sphaerexochus, Ampyx, Harpes, etc.
Here agam, among adult forms, the stages of progressive differentiation may
be taken as indicating the relative rank of the genera

The comparative areal growth of the free cheeks is expressed by the
gradual «moving of the facial suture toward the axis. As the free cheeks
become larger the fixed cheeks become smaller. In the most primitive pro-
nJJ'ir^''' Til '" ^"''^r.' ^^^'^'^ ^"^ Cryptoliihus, the dorsal Lface of the
Zttl'" ^ ^ ^ TT''^ \ '^' "^^^ ^^^ fi^^d «^^eks, while in the higher
S 11 r' f ^" ^^'^ '^''^' ^^^^^^^ r^d^^^d undl, as in Styginalnd
Phühpsia, they form a mere border to the glabella. Therefore the ratio

ä

suBCLAss I TRILOBITA 707

between the fixed and free cheeks furnishes another means of assisting in the
determination of rank.

The pleura from the Segments of the glabella are occasionally visible, as
in the young of Elliptocephala, biit usually the pleura of the neck segments are
the first and only ones to be distingiiished on the cephalon, the others being
so completely coalesced as to lose all traces of their individuality. The pleura
of the pygidium appear soon after the earliest protaspis stage, and in some
genera {Sao, Dalmanües) are even more strongly marked than in the adult
State, and much resemble separate segments. The growth of the pygidium is
very considerable through the protaspis stage. At first it is less than one-
third the length of the dorsal shield, but by successive addition of segments it
soon becomes nearly one-half as long. In some genera it is completed before
the appearance of the free thoracic segments, all of which are added during the
nepionic stages. An Interpretation of these facts, to apply in valuing adult
characters, would indicate that a very few segments, both in the thorax and
pygidium, may be evidence of arrested development or suppression. On the
other band, the apparently unlimited multiplication of thoracic and especially of
abdominal segments in some genera is also to be considered as a primitive char-
acter expressive of an annelidan style of growth. Genera like Asaphus, Phacops,
etc., having a constant number of thoracic segments accompanied by other char-
acters of a high Order, undoubtedly represent the typical Trilobite structure.

These analyses and correlations clearly show that there are characters
appearing in the adults of higher and later genera, which successively make
their appearance in the protaspis stage, sometimes to the exclusion or modifica-
tion of structures present in the more primitive larvae. Thus the larvae of
Dalmanites or Proetus, with their prominent eyes and glabella distinctly
terminated and rounded in front, have characters which do not appear in the
larval stages of ancient genera, but which may appear in their adult stages.
Evidently such modifications have been acquired by the action of the law of
earlier inheritance or tachygenesis, as it was called by Hyatt.

Position in the Zoological System. — Since Trilobites have been made the sub-
ject of special study, they have been commonly classed with the Crustacea, and
placed near the Phyllopods by most observers. Quite a number of naturalists,
however, still divorce the Trilobites and Limuloids from the Crustacea, and
ally them with the Arachnids. Leaving aside the question of the homologies
of Limulus, it is a fact that Trilobites show the clearest evidence of primitive
Crustacean affinities, in their protonauplius larval form, their hypostoma and
metastoma, the five pairs of cephalic appendages, the slender jointed antennules,
the biramous character of all the other limbs, and their original phyllopodiform
structure. They differ from Limulus, not only in most of these respects, but
also in not having an operculum. From Limulus and all other Arthropods
they are distinguished by having Compound eyes on free cheek-pieces, which
apparently represent the pleura of a head segment that is otherwise lost,
except possibly in some forms of stalked eyes and in the cephalic neuromeres
of later forms. The most recent discussions as to the affinities of Trilobites
are to be found in the papers by Bernard, Kingsley, Woodward and Beecher,
where, from the facts presented, the relationships of these animals with the
Crustacea follow as a necessary corollary.

As to the rank of the Trilobites in a classificatory scheme, there is also
much diversity of opinion. They have been long regarded as an order of

708 ARTHROPODA phylum vii

Crustaceniis, but any attempt to include them in this way under higher groups,
such as the Entomostraca, Malacostraca or Merostomata, results in such broad
generalities and looseness of definition as to render these divisions of little
value. The present state of knowledge of Trilobite structure and develop-
ment is in favour of assigning them nothing short of the rank of a subclass.

In nearly every particular, the Trilobite is very primitive, and closely
aerrees with a theoretical Crustacean ancestor. Its afiinities are with the
known subclasses of the group, especially their lower Orders, but its position
is not intermediate. The more primitive characters may be summarised as
follows : — (1) They are all free marine animals ; (2) they have a definite con-
figuration ; (3) the larva is a protonauplius-like form ; (4) the body and
abdomen are richly segmented, and the number of segments is variable ; (5)
the head is typically pentamerous ; (6) the thorax and abdomen are always
distinct, the number of segments in each being variable; (7) all segments
except the anal bear paired appendages ; (8) all appendages except antennules
are biramous ; and (10) the coxal elements of all limbs form gnathobases,
which become organs of manducation on the head. Walcott has recently
discovered (1912) the appendages of the Cambrian trilobitic genus Neolenus
and those of other Crustaceans, which indicate that the Trilobite is a
Crustacean intermediate in structural Organisation between the Branchiopoda
and the Merostomata.

Classification. — Barrande gives a complete räsumö of the classifications
applied to Trilobites down to 1850, and shows in a very satisfactory manner
the weak points of each, furnishing strong reasons as to why they are un-
natural and therefore untenable. The underlying principles *of these early
attempts at a Classification are here briefly summarised. (1) The first Classifi-
cation of Trilobites was advanced by Brongniart in 1822, in which all the
forms previously known as Entomolithus paradoxus were shown to belong to five
distinct genera. (2) Dalman, 1826, made two groups, based upon the presence
or absence of eyes. (3) Quenstedt, 1837, recognised the number of thoracic
segments and the structure of the eyes as of the greatest importance. (4)
/^N n r,, '' ■^^^^' ^onsidered the power of enrollment as of prime value.
(D) Ixoldfuss, 1843, established three groups depending on the presence or
absence of eyes and their structure. (6) Burmeister, 1843, accepted the two
divisions of Milne Edwards, and laid stress on the nature of the pleura and the
size of the pygidium. (7) Emmrich's first scheme, 1839, was founded on the
süape ot the pleura,_the presence or absence of eyes and their structure. (8)
wtfW fl. T'f'^*''''' ""^ ^^' ''^" ^^^^^^' P^blished in 1844, depended on
d^vi^ion. w! t""^? Z^l '""^P"''^ "^ ^^^^^ ^^ ^''^ segments, and the minor

Dvlidial Ir ' ^ tf.^ all Trilobites in two groups, one having an entire
M'C^^f 1 m^T'r .. ^' ''^'^ ^^'^ '^' P^S^^^™ l^b^d «r denticSate. (10)
divtio;al ch^^^^^^^^^ the presence or absence of a facet on the pleura for a
tTtTtLes not Hiff this IS an indication of the relative power of enrol-
Burme ster 7it\p ""'''•'""{ ^'"^ '^' ^^^^^^« ^^ ^^1^^ Edwards and

the Tchem s of m ' ^"^ ' Review brought down to 1885, includes in addition
the bfsis of itilJi '"'"^'i ''''' .'"^ (1') ^^1^^^' 1864, and remarks that
has ne her ^ j^fjf ^Seneral grouping, namely, the structure of the pleura,

BarrrnlandSa^?.r.f^'''^'^^ " morphological significance. Both
i3arrande and balter recognise nearly the same fan^ilL w,-fi.^.i,-.i.. a;^^ .

nearly the same families, with slight difFerences,

SUBCLASS I

TRILOBITA

709

aiid the latter adopts a division into two lines, based on the number of body
rings and size of the pygidium. These include and are themselves included
in four groiips, foundcd on the presence and form of the facial suture and the
structure of the eyes. (13) Chapman, in 1889, proposed four suborders or
primary groups based purely upon arbitrary features of general structure and
configuration, especially the form of the glabella, whether wide, conical or
enlarged. (14) Haeckel, in 1896, divided the Trilobites into two Orders
based upon the presence or absence of a functional pygidium.

The Classification here followed is essentially that prepared by Beecher for
the first edition of this treatise, but with some amplification and modification,
made possible by the recent work of Reed, Clarke, Jaekel, Walcott and others.
Beecher's Classification, although not universally accepted, has proved superior
to any previously proposed, and forms the basis for most of the modern
investigation of the group.

Order 1. HYPOPARIA Beecher.

Free cheeks forming a continuous marginal ventral plate of the cephalon, and in
sonie forms also extending over the dorsal side at the genal angles. Suture ventral,
marginal or submarginal. Compound paired eyes ahsent ; simple eyes may occur on each
fixed cheeJc, singly or in pairs.

Even in the higher genera of this order, the suture is frequently unnoticed, but cau
be Seen in all well-preserved specimens. In Gryptolithus and Harpes it follows the edge
of the cephalon, and separates the dorsal from the ventral plate of the pitted brim.
Since eye-spots occur on the fixed cheeks in the young of Gryptolithus and adult
Harpes, it is probable that this character is a primitive one in the order, and has
been lost in Agnostus, Eodiscus, Ampyx and Dionide.

The ontogeny of higher genera shows that the true eyes and free cheeks are first
developed ventrally, appearing later at the marginal, and then on the dorsal side of

this respect, a very primitive head structure, characteristic of the early larval forms

of higher families. Other secondary features show that this order, though the most

primitive in many respects, is more specialised than either of the others, except in

their highest genera. The characters referred to are the glabella and pygidium. Very

few species show the primitive segmentation of the glabella, it being usually smooth

and inüated and resembling in its specialisation such higher genera as Proetus,

W^Asaphus and Lichas. The pygidium often fails to indicate its true number of

^■Segments. Many species of Agnostus and Eodiscus show no segments either on the

Haxial or pleural lobes of the pygidium. Gryptolithus and others may have a numerously

^annulated axis and fewer grooves on the pleural portions. The number of appendages

correspoiids to the axial divisions. The multiplication of segments in the pygidium,

and their consequent crowding, make them quite rudimentary.

Cei)hala of Ilypoparia. A ,

Fio. 1357.
Agnostun. B, Eodiscus. C, Harpes.

D, Cryptolithus. E, Ampyx (after Beecher).

710

ARTHROPODA

PHYLUM VTI

Family 1. Agnostidae M'Coy.

Hypoparia with head and ahdomen shields similar ; free cheeks not visihle from the
dorsal side. Thorax with two segments. Cambrian and Ordovician.

Subfamily A. Condylopyginae Raymond.

Agnostidae with many-lohed shields, long glabella which expands toward the front,
and long and hroad axial lohe on pygidium.

Gondylopyge Corda. Anterior lobe of glabella broad. Pygidium
with three pairs of middle - lobes, and a broad end-lobe. Middle
Cambrian ; Europe and North America.

Pleurodenium Corda (Fig. 1358). Similar to Gondylopyge, but
with anterior lobe of glabella flattened, and crossed by radiating
grooves. Cambrian ; Europe.

Diplagnostus Jaekel. Anterior middle-lobe divided. Axial lobe
of pygidium pointed behind. Cambrian ; Europe,

Peronopsis Corda. Anterior middle lobe of glabella simple, not
wider than the part behind. Accessory lobes present at base of
granuiatum (Barr.), glabella. Middle Cambrian ; Europe and North America.

Cambrian ; Skrey,
Bohemia. ß/j (after
Barrande).

Subfamily B. Arthrorachinae Raymond.

Agnostidae with middle lohe of glahella short and simple; small accessory lohes
present at läse of glahella.

Arthrorachis Corda. Ordovician ; Europe and North America.
Hypagnostus Jaekel. Axial lobe of pygidium narrow, pointed behind.

Fig. 1358.
Pleurocteniw)

Subfamily C. Agnostinae Jaekel.

Agnostidae with hoth shields sculptured. Middle lohe of cephalon long, narroived
toward the front. Accessory lohes always present.

Agnostus Brongniart (Figs. 1357, A ; 1359). Surface
smooth ; accessory lobes simple. Cambrian ; Europe and
North America.

Ptychagnostus Jaekel. Surface wrinkled or otherwise
ornamented. Accessory lobes double. Cambrian ; Europe
and North America. Fig. 1350.

Agnostus pisiformis (Linn.).
Cambrian ; Andrarum, Svveden.

Sabfamüy D. Phalacrominae Corda. ^S^ofur^'^S^ltZkAZ^i

A i-j -,7 T . •■ , cephala and pygidia.

Agnostidae with shields scarcely lohed.

OrdSan' Eiiro^; ^'^'^^' ^""^^ ""^ ''^^'^^'''' ^''^ pygidium barely indicated-

Phalacrorm Corda. Cephalon and pygidium without lobes. Cambrian and
üi-dovician ; Europe and North America.

Family 2. Eodiscidae Raymond.

seameZ^ZllT^^ "T^ ^J'' f.'''^' '''' visihle from the dorsal ^de ; thorax of three
Segments , pygidium annulated. Cambrian.

SUBCLASS I

TEILOBITA '

711

Eodiscus Matthew (Microdiscus Salter non Emmons) (Fig. 1357, B). Glabella sliort,
occipital ring spined. Lower and Middle Cambrian ; Europe and North America.

Goniodüc'us Eaymond. Glabella long, occipital ring obtusely pointed. Type,
Microdiscus lobatus Hall. Lower Cambrian ; North America.

Family 3. Shumardiidae Lake, '

Hypoparia similar to the Ägnostidae in size and in structure of the cephalon, hut
with small, strongly segmented pygidium, and six segments in the thorax.

Shumardia Billings. Glabella prominent, expanding toward the fi-ont. Lower
Ordovician ; Europe and North America.

Family 4. Harpedidae Corda.

Hypoparia with very large head shield and small pygidium. Free cheeJcs ventral,
suture marginal. Thorax with numerous segments {seventeen to twenty-nine). Cephalon
loith hroad pitted hrim. Ordovician to Devonian.

The broad hippocrepian pitted brim of the Harpedidae has its counterpart in
Cryptolithus and Dionide, although less well developed in those
genera. The head is also relatively longer and larger, both
features being decidedly larval. The functional visual spots or
ocelli, situated on the fixed cheeks, are found only in this
family and in Tretaspis and in the young of Cryptolithus. The
great number of thoi'acic segments is another primitive
character, and the cephalon is larger than the thorax and
pygidium.

Harpes Goldfuss (Fig. 1357, C). Hypostoma somewhat
pentagonal, angular in outline. Silurian and Devonian ;
Europe and North America.

Eoharpes Kaymond (Harpina Novak) (Fig. 1360). Hypostoma
oval in outline. Ordovician ; Europe and North America.

Flu. 1360.

Koharpes ungula (Stern-
berg). Ordovician ;
Bohemia. l/i (after Bar-
tande).

Family 5. Trinucleidae Emmrich (Cryptolithidae Angelin).

Hypoparia with large cephalon and small pygidium. Free
cheeks ventral, carrying the genal spines. Cephalon with a pitted,
brim. Thoracic segments few (ßve or six). Ordovician.

Cryptolithus Green {Trinucleiis Murch. pars) (Figs. 1346, 1357,
D; 1361). Central portion of cephalon divided by the dorsal
furrows into three prominent portions. No ocelli in adult.
Ordovician ; Europe and North America.

Trinucleus Murch. (restr.). Glabella obovate, with two pairs

of weak glabellar furrows. Pits on brim set in deep radiating

furrows ; no ocelli or eye-lines. Ordovician ; Europe and North

America. Type T. fimhriatus Murch.

Glabella spherical in front, conical behind, with two pairs of

iye-lines present. Ordovician ; Europe and

Fig. 1361.
Cryptolithus gohlfus.'^i
(Barr.). Ordovician (Etage
D) ; Wesela, Boliemia.
xVi.

Tretaspis M'Coy.
strong glabellar furrows ; ocelli and
North America.

Dionide Barrande. Similar to Cryptolithus, but with an irregularly pitted border
and a large pygidium. Ordovician ; Europe.

712

K;imi

ly6.

ARTHROPODA
Raphiophoridae Angel

PHYLUM VII

Fifi. 1362.

Ampyx nasutus

(Dalmän). Or-

dovician ; Pul-

kowa, Russia.

Ampyx portlocki Barraiide.
Ordovician (Etage D) ; Leiskow
Bohemia. x Vi (after Bamuide).

. I. 7 u.'lnh,r1 cP,,halon without hrim, small, loide pygidium, and

Hypoparia wüh Urgc tnlohed '^'V^^''^' T ^^^^^^-^ ;^^,,,,,. Small free cheeics

visihle on the dorsal surface. Glahella
produced in front of the cephalon as a spme.
Ordovician and Silurian.

Raphiophorus Angelin. Glabella obo-
vate, witli an abrupt apical spine. Five
thoracic Segments. Europe.

Ampyx Bsilm!xn{Yig>^. 1357, i?; 1362,
1363). Glabella oval, terniinating in a
round spine. Six thoracic Segments.

^ Duu^iw.«. ^ ,1V - Europe and North America.

Lonchodomm Angelin. Glabellar spine long and prismatic in section. Europe and
North America.

Order 2. OPISTHOPARIA Beecher.

Free cheeks generally separate, always hearing the geml angles. Fadal sutnres
e.tendingforwardfror.t}u posterior part of the cephalon ,mtMn the f-f»;f2bem
cutting m anterior margin separately, or more rarey nmtmg m front of thegM^em,
Compound paired holochroal eyes on free cheeks, and well developed rn all hnt the most
primitive family.

The families which are here placed under this order lend themselves quite readily
to an arrangement based upon the characters successively appearing m the ontogeny ot
any of the higher forms. Thus Sao, Ptychoparia and other genera of the Olenidae

Fig. 1304.

Cephala of the Opisthojxiria. A, Atops. B, Conocwyphe. C, Ptychoparia. D, Olemis. E, Asa2-)hus.

F, lUaenus. G, Prwtus. H, Goldius. I, Lichas. J, Acidaspis (after Beecher).

have first a protaspis 8tage only comparable in the structure of the cephalon with the
genera of the preceding order. Therefore this stage does not enter into consideration
in an arrangement of the families of the Opisthoparia. In the later stages, however,
there is a direct agreement of structure with the lower genera of this order. The
nepionic Sao, with two thoracic Segments (Fig. 1355, B\ lias a liead structure agreeing
in essential features with that in Atops or Gonocoryphe (Figs. 1364, A, B). A later
nepionic stage, with eight thoracic Segments (Fig. 1355, G) agrees closely with the
adult Ptychoparia or Olenus (Fig. 1364, 0, D). These facts clearly indicate that the
family Conocoryphidae should be put at the base of this extensive order, Moreover,
as Ptychoparia Q.ndi Olenus are more primitive and simpler genera than Sao, they, as

SUBCLASS I

TRILOBITA

713

typifying tlie faniily Oleiiidae, govern its position, which accordiiigly woiild be after
the Coiiocoryijliidae.

Ditferences in tlie position of the eyes, the relative size of the free and fixed cheeks,
and the degree of specialisation of the glabella have a definite order in the ontogeny of
any Trilobite, and furnish characters of taxonomic value in arranging the families
placed nnder the Opisthoparia (see Fig. 1364).

Family 1. Oonocoryphidae Angelin.

Opisthoparia with free cheeks very narrow, forming the lateral margins of the
cephalon, and hearing the genal spines. Eye-lines are present, hut neither ocelli nor
Compound eyes. Thorax ivith from fourteen to seventeen segments. Pygidium small.
Cambrian.

The genera comprised under this family present a number of very primitive
characters, such as are displayed only in the larval stages of higher forms, The free
cheeks are narrow and marginal, and may be compared with those in the nepionic
stages of Sao and Ptychoparia. Eyes have not been detected, but the presence of an
eye-line suggests their possible existence. The variations in the glabella are very
marked, and are as great as those which in higher forms attain some importance as
family characteristics.

So far as known, all the larval forms in the other families of the Opisthoparia
agree in having the narrow marginal free
cheeks, bearing the genal angles, The
eye-line is present in most of the adult
Olenidae, and in the early stages of all so
far as known, so that the general average
of characters in the Oonocoryphidae re-
presents the main larval features through-
out the other families.

Conocoryphe Oorda (Figs. 1364, B;
1365, 1366). The glabella is convex,
tapering toward the front. Anterior
border of cephalon marked by a broad
and deep furrow. Oambrian ; Europe and
North America.

Ctenocephalus Oorda. Similar to Cono-
coryphe, but with a lobe in front of the
glabella. Oambrian ; Europe and North
America.

Fio. 1365.

Fig. 1367.

Conocoryphe sulzeri Schloth.
Without the free cheeks. Cam- Cephalon of>l /ojjs

-,««. ^ Toö^TN t>rian (Etage C) ; Ginetz, trilineatus Em-
Ätops tjmmojis (bigs. 13QA, A; 13b 7). Bohemia. Vi- "^o"«-

Glabella long, and does not taper. Thorax
of seventeen segments. Pygidium small. Lower Oambrian ; North America.

Family 2. Mesonacidae Walcott {OlenelHdae Moberg).

Opisthoparia with large cephalon and small, simple pygidium. Facial sutures in
a State of Symphysis and usually not to he distinguished. ' Eyes large, the palpebral lobes
extending to the glabella. Glabella narrow, sometimes tapering toward the front.
Thorax of numerous segments {thirteen to twenty-seven). Lower Cambrian.

This family is considered by "Walcott to have developed in pre-Cambrian time from sonie
annelid-like ancestor by the gradual combination of segments to form the ceplialon and
pygidium. A compact, stroiig pygidium, made up of raany segments, does not occur in this
family, nor among any of tlie simplest forms of Lower Cambrian Trilobites. The Middle

714

ARTHROPODA

PHYLUM YII

Cambrian Paradoxides is thought to have been descended from Callavia, through Ilolmia
and Wanneria.

Mesonacis Walcott. Thorax long and tapering, tlie tliird segment enlarged, and
tlie pleura extended as long spines. The fifteenth segment has a large spine on the

axial lobe. Ten segments behind the great spine.
Europe and North America.

Elliptocephala Emmons. Like Mesonacis, but
without the enlarged third segment, and with long
spines on the axial lobes of the last live segments.
Eastern North America. E. asaphoides Emmons.

Paedeumias Walcott. Like Mesonacis, but
with rudimentary thoracic segments and pygidium
posterior to the fifteenth segment. North America.
Olenellus Hall. Like Mesonacis, but without
segments back of the fifteenth, the great spine of
which is iisually considered as a pygidium,
Europe and North America.

Olenelloides Peach. Adult is essentially like a
larval form of Olenellus, as indicated by the large
cephalon and narrow thorax. Europe.

Holmia Matthew (Fig. 1368). Thorax with
sixteen segments, the pleura of which end in
rounded spines. Europe and America.

_ ^ ^ Wanneria Walcott. Similar to Holmia, but

Ringsaker.Norway. Lefriikif öf gTabeiia with broader spines on the pleura of the thoracic

romoved, exposing hypostoma beneath. 3/. j -.t, • ^^ no, ,i

(after Holm). ^ '"■ ■ '^ Segments, and with a spme on the fifteenth seg-

ment. North America.
Callavia Matthew. Similar to Holmia, but
with narrower glabella, and broader spines on the
pleura of the thoracic segments. Europe and
North America.

Peachella Walcott. Cephalon with blunt, tumid
genal spines; elongate, narrow glabella; small eyes
and marked convexity. Eastern Nevada.

Family 3. Paradoxidae Emmrich.

Opisthoparia with large cephalon, small free cheeJcs,
long narrow eyes, the palpehral lohes not reaching
the glabella in the adult. Thorax long, with numer-
ous segments {seventeen to twenty-
three). Pygidium small and
simple. Cambrian.

Paradoxides Brongniart (Figs.
1369, 1370). Glabella enlarging
toward the front. Middle Cam-
brian ; Europe, Eastern North
America and Australia.

Fig. 1368.
Holmia kjerulfi Linnarson.

Carabrian

Fio. 1369.
l'anuloxides l)ohemi(yus Barr. Cam-
bnan (Etage C); Ginetz, Bohen.ia. i^,.

Family 4. Olenidae Burmeister.

Opisthoparia with short and
Wide cephalon, small pygidium,

Fig. 1370.

Paradoxides (cf.
yoiing of P. inßatns
Cor da) = Hydro-
ccpludus carens Barr.
Cambrian ; Bohemia.

SUBCLASR I

TRILOBITA

71i

small free cheeks, and narrovj glahella. Eye-lines present, eyes small. Thorax of from
twelve to twentij-two segments. Cambrian and Ordovician,

Olenus Dalman (Figs. 1364, 1) ; 1371). Glabclla only inoderately convex, roimded
in front. Upper Cambrian and Ordovician ; Europe.

Eurycare Angelin (Fig. 1372). Cephalon very sbort and wide, eyes far apart.
Genal spines long and incurved. Cambrian ; Europe,

Fig. 1374.

F^«- 13'1. Fig. 1372. Fio. 1373. AulacopUuraTc<»vincU

Olennstruncatus Brunn. Eurycare brevicatida Ang. Sao hirsuta (Barr). Barr. Silurian (Etage
Cambrian ; Andrarum, Cambrian ; Andrarum, Sweden Cambrian (Etage C) ; D) ; Kuchelberg, near
Sweden (after Angelin). (after Angelin). Skrey, Bohemia. Prague. Bohemia.

Peltura Milne Edwards. Glabella wide, extending neaiiy to tlie 'front of the
cephalon. Eyes small, close to tbe front of tbe glabella. Pygidium small, witb short
spines. Upper Cambrian ; Europe and North America.

Ptychoparia Corda (Figs. 1348, 1364, C). Glabella convex and narrow, short,
furrowed. Pygidium large. Cambrian ; Europe, Asia and North America.

Sao Barrande (Figs. 1349, 1354, 1355, 1373).
Glabella strongly convex. Thorax of seventeen Seg-
ments. Pygidium very small. Surface granulöse.
Cambrian ; Bohemia.

Euloma Angelin. Glabella convex, short, with
prominent side lobes, similar to those of Calymene.
Pygidium short and wide. Ordovician ; Europe.

Aulacopleura Corda {Arethusina Barrande) (Fig.
1374). Glabella short, small, with basal lobes. Thorax
öf twenty-two segments. Pygidium small. Silurian ;
Bohemia.

Triarthrus Green (Figs. 1342, 1344-1345, 1350,
1375). Lacks eye-lines. Glabella low and broad. The
facial sutures cut the genal angles. This genus is note-
wortliy on account of the wealth of Information that has
been gained concerning the appendages, antennae and
other parts in wonderfully preserved remains. Ordovi-
cian ; Europe and America.

Bathynotus Hall. Eyes long and narrow. Axial
lobe wide. Thorax of thirteen segments. Lower Cam-
brian ; America.

Family 5.

Fig. 1375.

Triarthrus becki Green. Ordo-
vician ; Rome, New York. Specimen
showing antennae and ]>'<'<. -''^
(after Beecher).

Solenopleuridae Angelin.

Opisthoparia with free cheeks small and widely
separated in front, glahella short, convex, tapering toivard the front, eyes small.
Pygidium short, offeiv segments. Cambrian and Ordovician.

716

ARTHROPODA

PHYLUM VII

Solenopl..a Angelin. Eyo-lincs present. Cambrian ; Europe, Asia, and North
^'" /Sri»,-« EayB»nd, Eye-line. al«eut. Onlovician ; North America.

Fig. 1376.
Neolenus serratAt., (Rominger). Burgess shale (Middle Cambrian) ; Burgess Pass British Columbia. Posterior
portion of an individual showing thoracic legs and caudal rami. x ^/i (after Walcott).

Family 6. Oryctocephalidae

Beeclier.

Opisthoparia with large cephalon
and smaller pygidium, palpehral lohes
long and connected with the glahella.
Pygidium of six to nine Segments,
which end in spines. Cambrian.

Oryctocephalus Walcott. Glabellar
furrows represented by deep pits which
are connected across the top of the
glabella by shallow furrows. Middle
Cambrian ; North America and Asia.

Zacanthoides Walcott. Glabellar
furrows not deep, intergenal spines
present, thorax spinöse. Middle
Cambrian ; North America.

Olenoides Meek. Pygidium larger
and with shorter spines, and eyes
smaller than in Zacanthoides. Cam-
brian ; America.

Neolenus Matthew (Figs. 1343,
1376, 1377). Like Olenoides, bnt
the furrow on each pleuron of the

brian); British Columbia Group of thoracic and abdominal tliorax is diagonal instead of being
Iftirs. showiiit? basal mint or r.nxonoditft. and siv.in r,fo,i i,.r, o ^ ^^'^' ^^ O

Fio. 13Y7.
Neolenus serratits (Rominger). Burgess shale (Middle Cam-

legs, showing basal Joint or coxopodite, and six-iointod 1
with three terminal claws. x Vi (alter Walcott>!

straight. Cambrian ; America.

SUBCLASS I

TRILOBITA

717

Fig. 1378.

Alhertella helenae Walcott. Lower Cambrian
Powell County, Montana (after Walcott).

Family 7. Ceratopygidae Raymond.

Ojnsthoparia ivüh suh-equal cephalon and pygidium, long, nearly smooth glahella.
Pygidium with long spines at the sides. Caiuljrian and Ordovician.

Geratopyge Corda. Glabella long, narrow, with basal lobes. Pygidium with long
spines springing from the pleural lobes at the second annulation. Basal Ordovician ;
Euro2)e and North America.

Alhertella Walcott (Fig. 1378). Eyes long, glabella with
three pairs of furrows. Pleura of third segraent of thorax
extended into spines. Cambrian ; North America and Asia.

Family 8. Ellipsoce-
phalidae Matthew.

Ojjisthoparia with
narrow free cheeJcs, small
eyes, smooth, imfurroioed
glahella, twelve to sixteen
thoracic Segments, and small
pygidium. Cambrian.

Ellipsocephal'us Zenker
(Fig. 1379). Dorsal fur-
rows of the cephalon deep,
cheeks are very narrow.
Cephalon with a narrow,
raised border. Cambrian ;
Europe and North
America.

Agraulos Corda.
Glabella faintly outlined,
cephalon without concave
or rimmed border. Cam-
brian; Europe and
America.

Strenuella Matthew. Similar to Agraulos, but with a narrow
cephalon. Lower Cambrian ; America.

Fig. 1379.

Ellipsoceplialus hoffi
Schloth. Cambrian
(Etage C) ; Ginetz,
Bohemia.

Fig. 1380.

Caphyra radians
Barr. Ordovician
(Etage D) ; Königshof,
Bohemia. i/i (after
Barrande).

riin around the

Family 9. Remopleuridae Corda.

Opisthoparia with large, faintly furrowed glahella, ivhich has a tongue-like anterior
ptrojection. Eyes very large, extending nearly around the glahella. Thorax of eleven to
thirteen segments. Pygidium small. Ordovician.

Remopleurides Portlock, Pygidium wider than long, with two pairs of short
spines. Ordovician ; Europe and America.

Gaphijra Barrande (Fig. 1380). Pygidium long and flat. Genal spines and
pleura of thorax flattened. Ordovician ; Europe and North America.

Family 10. Bathyuridae Walcott.

Opisthoparia with cephalon and pygidium usually nearly eqiial in size. Glahella
long, cylindrical, reaching nearly to the anterior margin. Eyes large and dose to the
glahella. Tliorax of nine segments. Pygidium more or less strongly rihhed. Middle
Cambrian to Ordovician.

18

ARTHROPODA

PHYLUM VII

Bathyurus Billings (Fig. 1381).

Fkj. 1381.

Ikithyunis longispinus Walcott.
(Oi(iovician) ; Newport, N.Y.
Raymond).

Black River
X Vx (after

Glabellar fiirrows faint or absent. Pygidium
witli four pairs of smootli ribs, and a long^ pro-
minent axial lobe. Ordovician ; North America,
including Beekmantown beds of Newfoundland.

Petigurus Raymond. Cephalon like Bath-
yurus. Pygidium witli nodose ribs and strongly
annulated axial lobe, Ordovician ; Canada and
Ireland.

Bathyuriscus Meek. Glabellar furrows
deeper, eyes further forward, and pygidium
larger than in Bathyurus. Middle Cambrian ;
North America and Asia.

Bathyurellus Billings. Glabella low, smooth,
pointed in front. Cephalon and pygidium
witli broad concave borders. Ordovician ; North
America.

Family 11. Asaphidae Burmeister. ■

Opisthoparia with large, suh-cqual head and
ahdomen shields, prominent eyes, eight segments in
the thorax, and with a median vertical suture in
the doublure of the cephalon. Middle Cambrian
to Ordovician.

Subfamily A. Ogygiocarinae Raymond.

Asaphidae with hypostoma rounded or pointed hehind.

Ogygiocaris Angelin {Ogygia auct. non Brong.) (Fig. 1339). Pygidium with flat,
furrowed ribs. Axial lobe very narrow. Facial suture
marginal in front of
glabella. Ordovician ;
Europe,

Ogygopsis Wal-
cott (Fig. 1382).
Similar to Ogygio-
caris, but with eye-
lines, and eyes small
and far apart. Middle
Cambrian ; British
Columbia.

, Megalaspis Ange-
lin (Fig. 1383).
Glabella short,
cephalon and pygi-
dium nearly smooth
and sometimes
pointed. The facial
sutures meet in a
point far forward of
the glabella. Ordovi-
cian ; Europe, Asia,
and rarely North
America.

Fig. 1382

Fig. 1383.

Megalaspis extenuata Ang. Ordo-
vician ; Eäst Gotland, Sweden.
Vi (after Angelin).

SUBCLASS I

TRILOBITA

719

Äsaphellus Callaway. Similar to Megalaspis, but with loiiger and flatter glabella,
and shorter sbields. Treniadoc ; Europe. Lower Ordovician ; Nortli America.

Hemigyraspis Eaymond. Similar to Äsaphellus^ but witli facial sutiire marginal
in front. Tremadoc ; Eiiroi^e. Lower Ordovician ; North America.

Symphysurus Goldfuss. Cephalon and pygidium short, sub-hemisplierical, without
concave border. Axial lobe narrow. Lower Ordovician ; Europe and America.

Nileus Dalman. Similar to Symphysurus, but with broad axial lobe and very
large eyes. Ordovician ; Europe and North America.

Subfamily B. Asaphinae Raymond.
Asaphidae with hypostoma bifurcated.
Äsaphus Brongniart (Figs. 1364, E ; 1384). Cephalon and pygidium short and

Fig. 1384.
Asaphus expansus (Linn.). Ordovician ; Pulkowa, near St. Petersburg, Russia. i/i (after Salter).

wide, glabella prominent, expanding forward, and reaching
the anterior margin, which is without concave border.
Axial lobe of pygidium ringed, pleural lobes smooth.
Ordovician ; Europe and Asia.

Onchometopus Schmidt. Similar to Asaphus^ but the
glabella only obscurely defined, axial lobe rather wide, and
pygidium smooth. Ordovician ; Europe and North America.

Basüicus Salter. Pygidium strongly ribbed, glabella
convex, prominent, facial suture marginal in front. Ordo-
vician ; Europe and North America.

Ogygites Tromelin and Lebesconte {Ogygia Brongniart)
(Fig. 1385). Similar to Basüicus, but glabella less pro-
minent, and sutures meeting in a point in front of glabella.
Ordovician ; Europe and North America.

Ptychopyge Angelin. Glabella short, facial sutures well
inside the margin, pygidium not ribbed, concave borders
wide, and doublure very broad. Ordovician ; Europe.

Isotelus Dekay. Cephalon and pygidium smooth, with
wide depressed borders. Axial lobe of thorax wide. Ordo-
vician ; rare in Europe, abundant in North America.

Family 12. lUaenidae Corda.

Opisthoparia with large, convex cephalic and abdominal
shields which are nearly smooth and without concave border.
Epistomal plate large, hypostoma convex, ovoid. Thorax of
eight to ten segmeiits, with smooth pleura. Pygidium smooth, Fcc 13S5.

with short axial lobe. Ordovician and Silurian. Ogypitcs guettanU (Hrong.).

Ordovician ; An^«'rs, France.

Illaenus Dalman (Figs. 1364, F ; 1386). Axial lobe SrJÄBroSrt). ""'"

720

ARTHROPODA

PHYLUM VII

aboiit one-tliird tlie total widtli. Ordovician and Silurian ; Europe, Asia and North
America.

A n r

Fk;. 13.S(i.

A, lJ!'"'ny'< 'Iii'itiifniYolh. Ordovician; Pull<:owa, near
St. PctiTsbur-, liussiu. B, C, I. crassicauda Dalman.
Ordovician ; J)alck;uiieii, Sweden (after Holm).

Bumastus Murcliison. Axial lobe very wide ; ceplialon

and j^ygidiiim smooth.
and North America.
Thaleofs Conrad,
small and elevated.
America.

Ordovician and Silurian ; Europe

Glabella rather well defined

Fig. 13b7.

•j Dikelocephalus minnesotensis

Ordovician and Silurian ; North Owen. Upper Cambrian ; Wiscon-
sin. A, Cranidiuni, B, Pygidiuni
(after Hall).

Family 13. Dikelocephalidae Miller.

Opisthoparia with large cephalon and pygidium, glahella marked by faint furrows
which extend across it. Eyes large. Pygidium with short axial lohe, and usually a
pair offlat spines. Upper Cambrian and Lower Ordovician.

Dikelocephalus Owen (Fig. 1387). Spines on pygidium far apart, short and
broad. Complete specimens are known of D. Mensis and D. crassimarginatus.
Upper Öambrian ; North America.

Dikelocephalina Brögger. Spines close together at the posterior end of pygidium.
Lower Ordovician ; Europe.

Family 14. Goldiidae Raymond {Bronteidae Angelini).

Opisthoparia with eyes close to the glahella and to the posterior margin of the
cephalon. Glahella much expanded toward the front. Thorax with ten segments
Pygidium larger than the cephalon, with short axial lohe. Ordovician to Devonian.
Goldius de Koninck {Brontes Goldfuss) (Figs. 1340, 1364, H ; 1388). Pygidiuni

with radiating ribs extending from the end
of the axial lobe to the margin. Ordovician
to Devonian; Europe and America.

Thysanopeltis Corda. Like Goldius, but
with small spines along the posterior margin
of the pygidium. Devonian; Europe and
North America.

Bronteopsis Nicholson and Etheridge.
Cephalon like Goldius; pygidium with

tudinal ridge. The ribs on the r^uJTfl ^""f ^ ^''^'' ^^^'""^ "^^'^'^ ^' ^ ^^^^S^"
li".li..s tl.at tl,o latter appellatto'n wasprroccupreS =*'"*"*"ä '" ^••~'« "' t^e Same author „„

Fig. 1388.

'/" (13eyr). Cephalon. Devonian

U't. i-,, Konieprus, Bohemia (after Banande).

SUBCLASS I

TRILOBITA

21

Fig. 1389.
Froetus hohemicus Corda.

Pic. 1390.

Philli'pina gemimdifera
Phill. Lower Carboni-

Family 15. Proetidae Corda.

Small Opisthoparia ivith cephalon and pygidium nearly equal, free cheeJcs large, eyes
long, and dose to the glahella. Thorax with eight to ten segments. Ordovician to
Permian.

Proetus Steiiiinger (Figs. 1351, 1364, G; 1389). Glabella witliout deep lateral
furrows. Pygidium smaller tlian cephalon.
Ordovician to Carboniferous ; Europe,
Asia and America.

Gyphaspü Burmeister. Similar to
Proetus, biit with a strongly elevated
ridge which surrounds the glabella out-
side the dorsal furrows. Glabella with
prominent basal lobes. Ordovician to
Devonian ; Europe and America.

Haploconus Raymond. Similar to
Gyphaspis, but without the basal lobes on
the glabella. Type, Bathyurus smithi
Billings. Ordovician ; North America.

PhilUpsia Portlock (Fig. 1390).
Similar to Proetus, but with large pygi-
dium, and tosal lobes on glabella. This KÄt?r*ÄXr' fS" ' ■""""■ '"^
genus survived all other trilobites, but

became extinct with the close of the Permian. Carboniferous and Permian ;
Europe and America.

Family 16. Aeglinidae Pictet.

Opüthoparia with large glahella and eyes which occupy nearly the whole area of the
free cheeks.

This genus has the glabella strongly convex,
prominent, smooth ; fixed cheeks suppressed ;
eyes very large ; thoracic segments five or six ;
pleura grooved ; pygidium large, with short axis,
Ordovician ; Europe.

Family 17. Lichadidae Corda.

Opisthoparia with large cephalon and pygi-
dium, the glahella greatly modified hy the peculiar
development of the lateral furrows. Thorax with
nine or ten segments. Pygidium with short
axial lohe, and the pleural lobes modified in
various ivays. Oixlovician to Devonian.

Lichas Dalman (Figs. 1364, 7; 1392).
The glabella is broad, with axial furrows which
do not reach the neck furrow. Occipital lobes are present. Pygidium flat, with
the pleural lobes divided by furrows into two pairs of lobes with short free ends, and
a median flattened lobe. Ordovician and Silurian ; Europe and America.

Amphilichas Raymond {Platymetopus Schmidt). Glabella large, divided longi-
tudinally into three lobes by a pair of axial furrows which jom the neck ring.
Ordovician ; Europe and America. r ., i ,

Gorydocephalus Corda {¥i^. 1338,^ ; 1393). GlabeUa with three pairs of side lobes,

VOL. I ^ ^

Äeglina Barrande (Fig. 1391).

A n 0

Fio, 1391.
Aefilitia prisca Barr. Ordovician (Etage D) ;

Vosek, Bohemia
(after Barrande),

A, Nat. size. 7.', ü, enlarged

722

ARTHROPODA

PHYLÜM VII

tlie central lobe narrow.

Fia. 1392.

Lii-Iins laciniatus
Siluriaii ; Sweden
Angeliii).

Wahlb.
(after

13! »3.

Corydocephul us pti/onurufi
Hall and Clarke. Silurian ;
New York.

Pygidium small, tlie pleural lobes crossed by two narrow,
prominent ribs which end in spines.
Ordovician and Silurian ; Europe
and Nortli America.

Hoplolichas Dames (Fig. 1394).
Ceplialon trilobed, the central lobe
produced in front, and not depressed
at the back as in GonoUchas. Occipital
lobes present. Ordovician to De-
vonian ; Europe.

Geratarges Gürich (Fig. 1395).
Glabella witli two curved spines in
front, and pygidium with numerous
spines. Devonian ; Europe.

Geratolichas Hall and Clarke
(Fig. 1396). Ceplialon with two
pairs of long, curved spines on the
axial portion. Devonian ; North
America.

Terataspis Hall. Glabella bulbous,
strongly pustulose. Devonian; North
America.

Fig. 1395.

Ceratarges armatus
(Goldfuss). Devonian ;
Germany (after Beyrich).

Fio, 1394,

Hoplolichas schmidti Dames.
Ordovician ; Germany (after
Dames).

Fig. 1396.

Geratolichas gryps Hall
and Clarke. Devonian ; New
York (after Hall and Clarke).

Family 18. Odontopleuridae
Burmeister.

twelve Segments. Pygidium small.
Ordovician to Devonian.

Opisthoparia lüith large free
cheeks, small eyes. Thorax of eight to
All parts of the crust are usually very spinöse.

In this family, as well as in the Lichadidae, is to
be found the highest expression of difFerentiation and
specialisation among the Opisthoparia. The primitive
pentamerous lobation of the axis of the cranidium is
entirely obscured, and is only clearly seen in the pro-
taspis and early nepionic stages. These two families
are very closely related, the chief differences being
noted m the size and character of the pygidium, and
the ribbed or grooved pleura. The Lichades are
generally much larger and flatter, but the smaller and
spmose forms of Geratarges and Geratolichas approach
quite near some of the Acidaspidae.

^ Odontopleura Emmrich. Occipital ring smooth or
with a median tubercle. Ordovician and Silurian-
Europe and America. '

Ascidaspis Murchison (Figs. 1352 1364 j)
Occipital ring with a Single median spine.' Ordovician
and Silurian ; Europe and America.

Geratocephala Warder (Fig. 1397). Occipital ring
with two long nearly straight, divergent spines
Ordovician and Silurian ; Europe and North America

Fig. 1397.

Geratocephala dufrenoyi (Barr. ). Sil-
urian (Etage E) ; St. Ivan, Bohemia
(after Barrande).

I

SÜBCLASS I

TRILOBITA

723

r

K Äncryopyge Clarke. Margin of pygidium with twelve very long, slender, curved

B: spines. Devonian ; North America.

H Selenopeltis Corda. Thorax with very long spines extending from the pleura ;

B pygidium aspinose. Ordovician ; Europe.

B Glaphurus Raymond. Thorax witli twelve Segments. Pygidium very small and

B aspinose. Ordovician ; North America.

Order 3. PROPARIA Beecher.

Free cheehs not hearing the genal angles. Facial sutures extending from the lateral
margins of the cephalon in front of the genal angles, inward and forward, cutting the
anterior margin separately, or uniting in front of the glahella. Compound paired eyes
scarcely developed or sometimes ahsent in the most primitive family ; ivell developed and
schizochroal in the highest family.

This is the only order of Trilobites which apparently begins during the known
Paleozoic, and unlike the other Orders, had no pre-Cambrian existence. The earliest

Pio. 1398.

Cephala of the Proparia. A, Placopai'ia. B, Encrinurus. C, Calymene. D, Dipleura. E, Cheirurus.
F, Dahnanitina. G, Dalmanites. H, Chasmops, I, Phacopidella. J, Phacops (after Beecher).

forms of Proparia were initiated at the close of the Cambrian and dawn of the
Ordovician. The greatest generic differentiation of the group was early attained ;
during the Silurian and Devonian a rapid decline ensued, and only one or two
genera survived into the beginning of the Carboniferous.

Among the Opisthoparia, it seems clear that the Conocoryphidae formed the
natural base or most primitive family in the order, and is distinguished by the
narrow marginal free cheeks and absence of well-developed eyes. It is of great
interest and importance to be able to note that und er the Proparia there is a similar
primitive family having characters in common with the other, but still clearly
belonging to the higher order. Placoparia, Areia and Dindymene constitute a group
of apparently blind Trilobites with narrow marginal free cheeks, and present in
general the appearance of Atops, Gonocoryphe, Gtenocephalus, and other members of the
Conocoryphidae.

Family 1. Encrinuridae Angelin.

Proparia with narrow free cheeks ; either blind^ or ivith small eyes. Pygidium
composed of many segments, the pleural ribs usually less in numher than the rings on the
axial lohe, and usually ending in spines. Ordovician and Silurian.

Encrinurus Emmrich {Oromus Barrande) (Figs. 1338, B, G ; 1398, B ; 1399, 1400).
Cephalon tuberculated, glabella prominent, free cheeks separated in front by a small

ARTHROPODA

PHYLUM VII

fl K' I 1-1 ri.i ; r \ / i^xi.

724

, 1 . . cn.n elevated on conical promineiices ; tlioracic segmentB

epistomal plate ; eyes small, «levatedj^^^ _ ^^^.^.F^^^ ^^^^^^^^^^ triangulär. Ordo-

viciaii and Silurian ; Europe, Asia, and America.

Gyhele Loven. Similar to Encnnurus, but

with the ribs of the pygidium turning back

sliarply, parallel to the axis. Ordovician and

,, ,,,, Silurian ; Europe and America. J

Fi(i. 1400. "M

Fio. 13l»li. Encrinurns hohemicus ^

Encrinurus punc (liarrande). Silurian p ii„ £. Calymenidae Miliie Edwards,

taiTEmmrich.'^Sil- (Etege E) ; Lochkow. i^amiiy ^. y , ,, ,

urian ; Qotiand. Bohemia. Proparia wüh tUrteen Segments, the hypo-

aoma notched bekind, and attached to an ^AümM plate. Free cheeks narro^, the
facial sutures cutting the
margin almost exactly-\in
the genal angles. Oi^dovician
to Devonian.

Galymene Brongniart
(Figs. 1398, 0; 1401).
Glabella prominent, strongly
lobed, with two or three
pairs of lateral furrows.
Ordovician to Devonian ;
Europe, Asia and America.

Pharostoma Corda.
Glabella prominent, very narrow at the front, with

two pairs of glabellar furrows. Long genal spines

present. Ordovician; Europe.

Homalonotus Koenig. Axial lobe wide, cephalon

Short and trilobate in front, cheeks forming high

mounds crowned by the eyes. Silurian; Europe

and Nova Scotia.

Trimerus Green (Fig. 1402). Cephalon longer

than in the preceding, not trilobate in front, free

cheeks narrow. Silurian and Devonian ; world-wide

distribution.

Dipleura Green (Fig. 1 3 9 8, D). Axial lobe wide.

Pygidium smooth. Devonian ; Europe and America.

Family 3. Cheiruridae Salter. Fig. 1402.

Trimerus delphinocephalus Green.
Propana with small free cheeks, whose anterior ends ■ Silurian ; Lockport, New York.

are separated hy the glabella. Pygidium small with

pleura ending in spines. Thorax with nine to eighteen Segments. Ordovician to Devonian.

Fig. 1401.

Galymene meeU Foerste.
Ordovician ; Cincinnati, Ohio.

X Vi-

Subfamily A. Cheirurinae Raymond.

Cheiruridae with eleven segments in the thorax {rarely nine to thirteen), and four
Segments in the pygidium.

Gheirurus Beyrich (Figs. 1398, E ; 1403). Glabella smooth, more than one-third
the total width of the cephalon ; pygidium with six or seven sub-equal spines.
Ordovician and Silurian ; Europe, Australia and America.

Geraurus Green (Fig. 1341). Glabella pustulose, one-third or less the total width
of the cephalon ; pygidium very small, with the first pair of spines very long, the
others short or absent. Ordovician ; Europe, Asia, and America.

SUBCLASS I

TRILOBITA

725

Grotaloceplialus Salter. Siinilar to Gheirurus but witli furrows extending all
across the glabella. Silurian and Devonian ; Europe.

Sphaerexochus Beyrich. (Fig. 1404). Glabella globular, cheeks small. Ordovician

and Silurian ; Europe and America.
Pseudosphaerexochus Schmidt.
Glabella tumid, tapering forward.
Pygidium with subequal spines.
Ordovician ; Europe and America.

Nieszkowshia Schmidt. Glabella
tumid or prolonged into a spine
behind. Pygidium with two pairs of
spines. Ordovician ; Europe and
America.

Fig. 1403.

Cheirurus insignis Beyr. Sil-
urian (Etage E); Kozolup, Bo-
hemia. i/i (after Bairande).

Fig. 1404.

Sphaerexochus mirus
Beyrich. Silurian;
Listice, Bohemia. x Vi
(after Barrande).

Fig. 1405.

Cephalon of Pliomera fischeri
(Eichwald). Ordovician ; Pulkowa,
Russia.

Subfamily B. Pliomerinae Raymond.

Gheiruridae with fifteen to nineteen segments in the thorax ; pygidium hemispheric,
with five ßat segments.

Pliomera Angelin (Ämphion Pander) (Fig. 1405). Glabella expanding forward,
with two small median lobes on the front. Border of the cephalon denticulate.
Ordovician ; Europe.

Pliomerops Raymond. Similar to Pliomera^ but the glabella has parallel sides,
and lacks the two small lobes at the front. Oi-dovician ; Europe and America.

Placoparia Corda (Fig. 1398, A). Free cheeks are narrow ; eyes absent.
Ordovician ; Europe.

Subfamily C. Deiphoninae Raymond.

Gheiruridae with a part of the glabella bulbous.

Beiphon Barrande. (Fig. 1406). Glabella globular,
without lateral furrows. Free cheeks minute. Silurian ;
Europe and North America.

Staurocephalus Barrande. Glabella with two pairs
of glabellar lobes behind the bulbous portion. Cephalon
with a denticulate border, and pygidium similar to that
of Pliomera. Silurian ; Europe and North America.

Sphaerocoryphe Angelin. Glabella with one pair of
lobes behind the bulbous portion. Ordovician and
Silurian ; Europe and North America.

Deiphon forhesi
(Etage E) ; St.
(after Barrande).

Silurian
Bohemia

with large facets, schizochroal.

Family 4. Phacopidae Corda.

Proparia ivifh rather large free cheeks, eyes large.
Thorax with eleven segments. Ordovician to Devonian.

726

ARTHROPODA

PHYLUM VII

Subfamily A. Dalmanitinae Reed.

Phacopidae with more or less modified pentamerous segmentation of the glahella, and

usually lüith large cranidia and pygidia.

Dalmanitina Reed (Figs. 1353; 1356;
1398, i'^; 1407). Pentamerism of head well
marked, lobes of glabella distinct ; genal angles
rounded or with short spines. Pygidiiim
with few Segments, rarely more thaii ten.
Ordovician and
Silurian ; Europe.

Dalmanües Bar-
raude (Figs. 1337 ;
1398, G-, 1408).
Frontal lobe of gla-
bella detached. Pygi-
dium strongly mucro-
nate, with twelve to
Devonian ; Europe and

Dalmanitina socialis (Barr.). Ordovici?
D); Wesela, near Prague, Bohemia. Cephalon,

Silurian and

sixteen segments.
America.

Asteropyge Corda {Cryphaeus Green). Pygidium with five
pairs of marginal spines, and sometimes a terminal spine.
Devonian ; Europe and America.

Proholium (Ehlert. Cephalon with a snout-like anterior
Prolongation. Devonian ; Europe and America.

Subfamily B. Phacopinae Reed.

Phacopidae with glahellar furrows nearly or quite o
and pygidium small and rounded.

Fig. 1408.

Dalmanües limulurus
(Green). Silurian ; Lockport,
New York (after Hall).

Phacopidella Reed (Acaste Goldfuss) (Figs. 1398, 1; 1409).
Glabella with three pairs of ^.^^^^^^ faintly defined lateral furrows.

Ordovician and Silurian ; J^W^^^ Europe.

Phacops Emmrich (Figs. ijjflfg^^
furrows, except occasionally P J^j^^gpl the last pair, obsolete. Silurian
and Devonian ; world - wide fe'^ wkgmM^M distribution.

Fio. 1409,

Phacopidella dovmingiae
(Murch.). Silurian ; Lud-
low, England (after Salter).

Fig. 1410.,

Phacops latifrons
Bronn. Devonian ;

Gerolstein, Eifel
üistrict, Germany,

Fig. 1411.

Phacops sternbergi Barr.
Devonian (Etage G) ; Hostin.
Bohemia (after Barrande).

Trimerocephalus M'Coy. Eyes small and far forward. Devonian ; Europe.

^fplg.

süBCLASs I TRILOBITA V27

Subfamily C. Ptp^rygometopinae Reed.

Rather small Phacopidae, the cephalon with more or less modißed ijentamerous
lohation, and the pygidium less triangulär and with fewer Seg-
ments than in most of the Dalmanitinae.

Pterygometopus Schmidt (Fig. 1412). Glabella with three
pairs of lateral furrows, Ordovician ; Europe and North
America.

Chasmops M'Coy (Fig. 1398, H). Second pair of glabellar ^'''- ^^^^•

lobes absent, or represented by tubercles. Ordovician ; Europe. (DS.r'''oJ^i'ovfSrrf •

MonoraJcos Schmidt. Second and third pairs of glabellar iswos, Esthonia (after
furrows represented by pits. Ordovician ; Europe. ^ ™'

Geological Range and Distribution of Trilobites.

Trilobites are the only large division of the Arthropoda which has become extinct.
Even in the earliest Cambrian they bear evidence of great antiquity, — in their
diversified form, larval modifications, polymerous head and caudal shields. These
features show that Trilobite phylogeny must extend far back into pre-Cambrian
times, and it is probable that primitive Branchiopods, of a type corresponding to the
modern Äpus, were developed even earlier. The views of Bernard and Walcott
regarding the origin of Trilobites and higher Crustacea from a primitive Apus-like
ancestral stock are mentioned a few pages farther on under the head of Branchiopoda.

Concerning the habits of Cambrian Trilobites Dr. Walcott has suggested that the
adult animals probably crawled about the sea-bottom and did not swim freely in the
water to the extent that it would be necessaiy to see the bottom. Their habits must
have been very much like those of Limnlus when in search of food. That the
creatures burrowed and pushed their way through the mud and soft sands is proven
by the trails and burrows made by them, some of which we now designate as
Protichnites.

The maximum development of Trilobites occurred in the Cambrian and Ordovician,
after which they steadily waned both in numbers and variety. The genera of the
Conocoryphidae, Eodiscidae, Mesonacidae, Paradoxidae, Oryctocephalidae and Ellipso-
cephalidae, are wholly restricted to the Cambrian, and here also are found nearly all
the Olenidae and Agnostidae, only scattering representatives of which survive into
the Ordovician. The Asaphidae are more characteristic of the Ordovician, and the
Cryptolithidae, Shumardiidae, Remopleuridae, Bathyuridae and Aeglinidae are
restricted to it. The Raphiophoridae, Goldiidae, Harpedidae, Encrinuridae, and
Illaenidae flourished in the Ordovician and Silurian, while the Proetidae, Lichadidae,
Odontopleuridae and Phacopidae attained their greatest development in the Silurian
and Lower and Middle Devonian.

The later Devonian witnesses a decline in the number of families present, and with
the close of this era, the class practically became extinct, since only five genera of
one family, the Proetidae, are met with in the Carboniferous, and the single genus
Phillipsia alone persists as late as the Permian.

As regards their geographica! distribution, some genera are of cosmopolitan occur-
rence : such as Ägnostus, Conocoryphe, Ptychoparia, Paradoxides, Gryptolithus, Illaenus,
Proetus, Phillipsia, Äcidaspis, Lichas, Calymene, Homalonotus, Cheirurus, Phacops,
Dalmanites, and others. The majority of forms, however, are extremely limited in
distribution, so that a large number of genera found in Sweden, Bohemia, England
and North America are unknown outside of cerUiin very restricted areas ; and the
total number of species common to both sides of the Atlantic is very small.

A remarkable contrast is observable between the older Paleozoic Trilobites of the

728

ARTHROPODA

PHYLÜM VII

northern parts of Europe, and tliose of tlie middle and soutliern portions. Wliile the
niajority of northern genera and si^ecies are common to Great Britain, Scandinavia
and Russia, the forms of the central European provinces (Bohemia, Thuringia, Fichtel-
berg, the Hartz, Belgium, Brittany, Northern Spain, Portugal, the Pyrenees; the Alps
and Sardinia) are so dissimilar as to stand in closer relationships with the North
American than with the first-named Trilobite fauna. Of the 350 species found in
Norway and Sweden, and of the 275 species in Bohemia, only six are common to
hoth provinces, and it is doubtful if these are really identical.

The first of the accompanying tables shows the ränge and relative development of
the Orders and the subclass ; the second represents the vertical ränge of the several
families of Trilobites.

TABLE I

Diagram Constructed by Beecher showing Relative Development
OF THE Orders of Trilobites

[Table

SUBCLASS I

TRILOBITA

729

Table showing Vertical Range of Trilobites

Orders and Families.

? C i -O t:

Order 1. Hypoparia

Family 1. Agnostidae .

2. Eodiscidae .

3. Shumardiidae

4. Harpedidae

5. Trinucleidae

6. Raphiophcrridae

Order 2. Opisthoparia

Family 1. Conocoryphidae

2. Mesonacidae

3. Paradoxidae

4. Olenidae

5. Solenopleuridae

6. Oryctocephalidae

7. Ceratopygidae

8. Ellipsocephalidae

9. Remopleuridae

10. Bathyuridae

11. Asapliidae .

12. lUaenidae .

13. Dikelocephalidae

14. Goldiidae .

15. Proetidae .

16. Aeglinidae .

17. Lichadidae .

18. Odontopleuridae

Order 3. Proparia

Family 1. Encrinuridae

2. Calymenidae

3. Cheiruridae

4. Phacopidae .

Total Number of Famili

8 il 22 11

3 ' 1

[The foregoing cliapter oii Trilobites has been revised by Dr. Percy E. Raymond, of the
Museum of Comj)arativc Zoology at Cambridge, Mass. Some notes on Cambrian genera,
togetlier witli two or three figures illustrating the same, have been contributed by Dr. C. D.
Walcott. —Editor. ]

730

ARTHROPODA

PHYLUM VII

Subclass B. EUCRUSTACEA Kingsley/ (Crustacea proper.)

Crustacea having typically two pairs of antenniform preoral appendages and at
hast three pairs of postoral appendages acting as jaws.

In the Crustacea proper the appendages of the head-region are as follows :
the first and second pairs are preoral and are known respectively as antennules
and antennae ; the third pair, placed on either side of the mouth, are the
mandibles; the fourth pair, maxillulae, and fifth pair, maxillae (the two pairs
sometimes known as first and second maxillae), are secondary jaws. The
appendages behind these vary in character, some being Walking or swimming
feet, while from one to three pairs may be subsidiary to the maxillae in
feeding, in which case they are called maxillipeds.

Regarding the evolution of the subclass, Bernard has reached the conclusion

I

1

Strabops ■

Sidneyia • •

Agiaspis
Mobria

Emeraldella'- .
Habelia

y

NathorsUa

•Mauella

Bidentia

-Hymenocaris

, Opabin

Beltina^

Theoeetical Evolution of Cambrian Crustacea from the Branchiopoda
(accordmg to Walcott 2).

ilT'firü^Z""*'"^ are descended from a browdng carnivorous annelid with

md! n L "ir;"^ ? PÜ-T'"* ^°' P"^*^'"« f°°d into its mouth. The
Be.trd TZf'^'r .i'^'^'^^'P'''''^*'"^' crustacean-annelid, according to
fauna otß itÄ,„ W ^' ^"«ess shale (Middle Oambriän) crustalan

whTh have the L Hh \T' "'"*'" *"'"^"<^^' ^^' ^''»«^ W«^« Walcott,
Wh ch have the head bent down so that the mouth faces posteriorly, and in

Literature: Öerstoec^-er, yi. and Ortoj««« a v n ^ ■ ^ ,

des Thierreichs, vol. v., 1866-1901 — rl/T w/ m' ^^^«^^^ea, in Bronn's Klassen und Ordnungen
pt. vii., fasc. 3, 1909. ' ^""'^^» '^- ^^ Crustacea, in Lankester's Treatise on Zoology,

Smithson! mL^oU.', 1912!'voLTvi[!^no.^r'^'''^°'^^' ^^^^«««t^^««' Trilobita, and Merostomata.

J

süBCLASs II EUCRUSTACEA— BRANCHIOPODA 731

the opiiiioii of bheir describer may have been derived from the same general
type of animal as the accompanying crustaceans.

The preceding diagram, which is taken from Walcott, illustrates that
author's views as to the relations of Cambrian crustaceans to a theoretical
ancestral stock which for convenience is correlated with ^^'ws-like forms.
From this primitive stock it is assumed that the Branchiopoda were derived,
and from them three distinct branches were developed prior to, or diiring,
Cambrian time. According to this view Trilobita are direct descendants of
Branchiopoda, and in turn gave rise to the line leading through the Orders
Aglaspina, Limulava and Eurypterida to the Xiphosura. The structure and
probable habits of Trilobites lead Walcott to the opinion that these w^re
mud-burrowing animals more or less allied to Limulus. The Phyllocarida
and Ostracoda are assumed by the same author to have been derived from
the Branchiopoda, but on different lines of descent from that of the Trilobites
and the Orders grouped under the Merostomata.

The Eucrustacea are frequently divided into Entomostraca and Malacostraca^
but the first of these groups is not a homogeneous assemblage ; it is rather a
repository in which have been placed all forms not members of the Malacostraca.
The Eucrustacea are here divided into the superorders Branchiopoda, Ostracoda^
Copepoda, Cirripedia and Malacostraca.

Superorder 1. BRANCHIOPODA Latreille.i

Eucrustacea in which the carapace may form a dorsal shield or a bivalve shell or
may he entirely ahsent ; the number of body segments and appendages varies greatly ;
the appendages of the body are rarely pediform, generally foliaceous and lobed.

Under the Branchiopods are embraced very differently formed Crustaceans
of large and small size, living mostly in fresh water or salt lakes, and
possessing little eise in common than the leaf-like form of leg. The
segmentation of the body in the larger forms is very distinct, but in. the
water fleas (Cladocera) it is usually quite incomplete. The number of body-
segments varies considerably among different genera. In the strongly
segmented forms the body is elongated and protected in front by a flat or
shield-shaped dorsal carapace (Apus), or it is naked (Branchipus), In the
Cladocera and Estheriidae, which are enclosed in a bivalve shell, the body is

^ Literat ure : A. Recent Forms. — Grube E.., Bemerkungen über die Phyllopoden, etc. Wieg-
mann's Archiv für Naturgesch., 1853-1865, vols. xix., xxi. — Claus, C, Papers ou Branchipus
and Apus, in Abhandl. Gesellsch. Wiss, Göttingen, 1873, vol. xviii., and Arbeit. Zool. Inst, Wien,
1886, vol. vi. — Weismann, F. L. A., Zur Naturgeschichte der Daphniden. Zeitschr. Wissensch.
Zool., 1876-80, vols. xxvii., xxxiii. — Lankester, JE. R., Several papers on Limulus, Apus, etc.,
in Quart. Journ. Microsc. Soc, 1881, vol. xxi. — Packard, A. S., Monograph of the Phyllopod
Crustacea of North America, 12th Ann. Rept. U.S. Geogr. and Geol. Surv. Terr., 1883.— Äirs, G. 0.,
Fauna Norvegiae. I. Phyllocarida and Phyllopoda, 1896. — Bernard, H. M., The Apodidae. Nature
series, London, 1892.

B. Fossil Forms. — Jones, T. R., On Fossil Estheriae and their distribution. Quar. Journ.
Geol. Soc, 1863, vol. xix.— Monograph of the Fossil Estheriae. Palaeontogr. Soc, 1862.— 5th
and 7th Repts. Comm. British Assoc Adv. Sei. on Fossil Phyllopoda, 1887-89.— Geol. Mag.,
Sept. 1890, Feb. 1891, Dec 1893, July 1894.— Trans. Geol. Soc. Glasgow, 1890, vol. ix.—
Glarke, J, M., New Devonian Phyllopods. Amer. Journ. Sei., 1882, vol. xxiii. — Hall, J., and
Glarke, J. M., Palaeontology of New York, 1888, vol. viu—Bemard, IL M., Fossil Apodidae.
Nat. Sei., 1897, vol. xx.—Schuchert, C., On the fossil Phyllopod genera Dipeltis and Protocaris.
Proc. U.S. Nat. Mus., 1897, vol. xix.—Clarke, J. M., Estheria in Devonian of New York and
Carboniferous of Ohio. Rept, N.Y. State Paleontologist, 1900.— 7</eH(, Notes on Paleozoic Crus-
taceans. 54th Ann. Rept. N.Y. State Mus., 1902, vol. \.— Walcott, C. D., Middle Cambrian
Branchiopoda, Malacostraca, etc. Smithson Mise. Coli., 1912, vol. Ivii., no. 6.

732

ARTHKOPODA

PHYLUM VII

laterally compressed, shortened, and often indistinctly segmented. The head
is sharply demarcated from the rest of the body, and is usually provided with
two large eyes sometimes coalesced, in addition to which there is often a
a small unpaired eye. The Upper lip is very large, the mandibles have no
palps, and the maxillae are reduced or absent.

The body-limbs are usually foliaceous and lobed on the outer and inner
margins. They vary in number from four to more than sixty pairs, and
usually all carry gill-plates. The posterior part of the body is without
limbs and usually ends in a caudal furca, the rami of which may be filiform,
flattened or claw-like. All Branchiopods have the sexes ^distinct. The
males are often much less numerous than the females, and the latter
reproduce largely by parthenogenesis.

The Classification of the Branchiopoda here given diff'ers from that
commonly adopted, in that the term Fhyllopoda (Latreille, 1802) is not
employed for an ordinal division including several groups which are dis-
tinguished from the Cladocera chiefly by the greater number of somites and
appendages and by the prevalence of metamorphosis in development. Tnstead,
these groups of the old division Phyllopoda are more properly assigned the
rank of independent Orders, all three being sharply contrasted from one
another as well as from a fourth order, Cladocera. Phyllopods in the old
sense, therefore, are equivalent to the Orders Anostraca, Notostraca and
Conchostraca, as here recognised. The Substitution of the term Phyllopoda
for Branchiopoda, in the usage of Claus and some writers following him is
contrary to the rule.^

Order 1. ANOSTRACA Sars.

Head distinct, carapace ahsent, paired eyes pedunculate ; thorax with eleven to
nineteen pairs of trunJc-Umhs, none post - genital ; furcal rami_
unsegmented, rod-lihe or flattened.

Branchipodites Woodward. Similar to the Recent BrancU-
pus. Oligocene of Bembridge, Isle of Wight. B. vectensis
Woodw.

Opahinia^ Leanchoilia, Yohoia (Fig. 1413), Bidentia Walcott.
Middle Cambrian ; British Columbia.

Order 2. NOTOSTRACA Sars.

Carapace forming a dorsal shield ex-
tending over the anterior segments ; paired
eyes sessile ; antennae vestigial ; trunk-
limhs forty to sixty-three pairs, of ivhich
twenty-nine to fifty-two are post-genital ;
furcal rami multiarticulate.

Protocans Walcott (Fig. 1414). This
is the oldest representative of the Apus-
type, and exhibits a remaikable similarity
to Apus in its univalve carapace, multi-
, segmented abdomen, and sinj^le pair of

caudal spmes. Lower Cambrian ; Vermont.

Mlopoda, applj.n, 11,,. 1. tte o the superorder and the former to one of its divisions, but this
1'} priority or by universal custom.

Pio. 1413.
Yohoia tenuis Walcott
Middle Cambriaii ; I5i itisl
Columbia. Dorsal viiw
X2/i.

use is not sanctioned citli

Fig. 1414.

Frotocaris marshi
Lower Cambrian ;
Vermont, x 2/3.

^

SUBCLASS II

EUCEUSTACEA— BRANCHIOPODA

'33

Riheiria Sliarpe ; Ribeirella Shubert and Waagen. These names have been applied
to arched, univalved bodies with strong beaks, muscular scars and sub-cardinal ridge.
They occur in tlie eaiiy Ordovician of Europe and America, and are doubtfully
assigned to a position among tlie Apodidae.

Apus Latreille. Trias to Recent. Lepidurus Leach. Recent. These genera,
incliided in the family Apodidae, comprise the largest known forms of Branchiopods,
some species of Apus having a length of 70 mm. The under-mentioned Cambrian
Notostracans are placed in separate families by Walcott.

Naraoia (Fig. 1415), Burgessia and JVaptia Walcott (Fig. 1416). Middle
Cambrian ; British Columbia.

Änomalocaris Whiteaves. This name has been applied to bodies from the

Fig. 1415.

Narctoia compacta Walcott. Middle Cambrian ;
British Columbia. Dorsal view, x 2/,.

Fio. 1416.

Waptia fieldensis Wal-
cott. Middle Cambrian ;
British Columbia. Dorsal
view of flattened specimen,
X Vi-

Cambrian of British Columbia which have been compared to the segmented abdomen
of a Branchiopod, each segment bearing a pair of lamellate appendages. Although
the objects abound where found, nothing is known of the carapace, nor is there any
evidence of the surface markings which characterise most Crustacean shields. Their
affin ities are doubtful.

Euchasma, Eopteria and Ischyrina Billings ; Technophorus Miller. These names
have been applied to remains from the Ordovician of North America, regarded by
their describers as Pelecypods, but undoubtedly of Crustacean nature. Their reference
to the Notostraca is uncertain.

Orders. CONCHOSTRACA Sars.

Carapace hivalved, enclodng the whole hody ; antennae well developed, hiramous^
natatory ; paired eyes sessile, coalescent Body-limbs ten to twenty-seven pairs, of which
none to sixteen are post-genital, and thefirst one or two in the male form clasping organs.
Furcal rami claw-like.

734

ARTHROPODA

PHYLUM VII

Family 1. Limnadiidae Baird.
Family characters the same as ahove given for the order.

Estheria Riippel (Figs. 1417, 1418). Shell composed of two tliin rounded valves,
united by a straiglit tootliless margin. External surface concentrically ridged or

FlG

Estheria minuta Alberti. Lettenkohle Dolo-
mite ; Sinsheim, Baden. A, Vi- -B» ^/i- <?>
Portion of the exterior, 50/j.

Fig. 141S.

Estheria sp. indet. Lower barren
Goal Measures ; CarroUton, Ohio.
Umbonal portion showing muscular
or nuclear node, 13/^.

striated, and between the ridges are more or less regularly interlacing or branching
Striae. The latter character serves to distingiiish this geniis from Posidonomya among
Pelecypods. The beaks are not sharply defined, and the primitive portions sometimes
bear a strong ocular or muscular node.

The genus Estheria has numerous fossil representatives, being first met with in the
Devonian, and occurring mostly in brackish and shore deposits. It abounds in the
productive Goal Measures, in the Permian, Trias (Lettenkohlen mergel) and Wealden,
and has been found in the Pleistocene clays of Canada.

Leaia Jones (Fig. 1419). Carapace marked by one or two diagonal ridges

Fig. 1419.
A, Leaixi leidyi Jones. Goal Measures ; Pottsville,
Pennsylvania. B, Uaia Inentschiana Geinitz. Goai
Measures; Neunkirchen, near Saarbrücken (after
Golden berg).

Fig. 1420.

Schizodiscus capsa Glarke.
Hamilton ; Centerfield, New
York. 2/j.

whicb ran from the anterior end of the dorsal margin toward the lower margin.
Carboniferous ; Europe and North America.

Estheriella Weiss. Carapace as in Estheria, but with radial riblets crossing the
concentric Striae. Permian ; Russia. Buntersandstein ; Saxony
_ _ Schizodiscus Clarke (Fig. 1420). Carapace peltate, with a straiglit hinge which
18 in the major axis of the shield. Fach valve nearly a semicircle ; surface marked
with concentric ridges. Middle Devonian ; New York.

Lepeditta Matthew. Cambrian ; North America.

SÜBCLASS II

EUCRUSTACEA— OSTRACODA

735

Family 2. Bradoriidae Matthew.

Garapace bivalved, memhranaceous^ calcareo-corneus in composüio^i, not completely
separated hut prohahly often fused aloncj the cardinal edge ; free margins of valves
slightly gaping ; main muscle spot dose to antero-cardinal angle just hehind and beneath
the ocular tuhercle.

The niembers of this family have hitherto been considered as Cambrian Ostracoda, but
recent studies have shown them to be Branchiopoda. The genera listed below embrace
several distinct types of structure, and will in part be referred to other families in the course
of study.

Beyrichona Matthew (Fig. 1421, A, B). Valves subtriangiilar with a broad
undefined depression in the dorsal slope, limited in front by a short node-like ridge.

Fig. 1421.

A, Beyrichona tinea Jfatthew. x Vi- -ß'
Beyrichona papilio Matthew. x ■^/i. Middle
Cambrian of New Brunswick.

Fig. 1422.

A, Hipponicharion clavatum Matthew.

X 4/i- -B, ^luta enyo (Walcott). x 8/j.

Middle Cambrian of New Brunswick and

China.

Hipponicharion Matthew (Fig. 1422, A). Valves semi-elliptical with two
prominent marginal ridges and an inconspicuous central ridge near hinge line.

Polyphyma Groom. Valves semicircular with numerous rather variable tubercules.
Bradoria^ Escasona, Aluta Matthew (Fig. 1422, B). (?) Isoxys Walcott.

Order 4. CLADOCERA Müne Edwards.

Garapace hivalved, generally enclosing hody hut leaving headfree ; paired eyes sessile,
coalesced ; antennae large, forming swimming organs ; four to six pairs of body-limhs ;
furcal rami claw-like.

The egg-cases (ephippia) of Cladocera have been recognised in Glacial deposits in
Germany. Lynceites ornatus Goldenberg, from the Carboniferous, is a very doubtful
representative of this order.

Superorder 2. COPEPODA Milne Edwards.

Eucrustacea without a distinct carapace, but with one or two of the anterior
somites coalesced with the head. Paired eyes usually ahsent. Antennules anU
antennae usually well developed ; typicalhj six pairs of biramons body-limhs. Caudal
furca present.

The Copepoda are without knovvn representatives in the fossil State.

Superorder 3. OSTRACODA Latreille.i

Small, indistinctly segmented Crustacea completely enclosed in a horuy or calcareoiis
bivalve shell. Not more than seven pairs of appendages present — two of antennae,

^ Literature : Bosquet, J., Description des Eutoniostraces fossiles de la craie de Maestrich t.

736 ARTHKOPODA phylum vii

one of mandibles, two of maxillae, and two pairs of feet. Abdomen short and
riLdimentary.

As a ruie only the bivalved shell of the.Ostracoda is found fossil, and since
the Classification is based principally upon characters presented by the
appendages, the relations of recent to fossil forms cannot be made out with
certainty, especially as the form and ornamentation of the shell are largely
independent of the internal Organisation.

The valves are closed by a subcentral adductor muscle, the attachment of
which is marked on their inner sides by a tubercle, pit, or a number of small
spots. The shell is compact in structure, commonly from 0*5 mm. to 4 mm.
in length, although sometimes exceeding 20 mm. The outer surface may be
smooth and glossy, or granulöse, pitted, reticulose, striate, hirsute, or other-
wise marked, the effect being often quite ornamental. The two valves may
be of equal size (Beyrichia), or more or less unequal, with either the right or
left valve overlapping at the ventral border only (Leperditia), or at the dorsal
border as well (Bairdia), or in some cases overlapping all round (Cytherella).

Most commonly the outline is ovate or reniform ; in many cases, however,
one or both ends may be pointed or drawn out in the form of a beak ; and
when the dorsum is straight, the ends may join it angularly. Although
usually convex, the ventral margin is sometimes straight or gently concave.
It is sometimes impossible to distinguish between anterior and posterior
extremities, but as a rule the posterior half is somewhat thicker than the
anterior, even though of equal or of less height. The hinge -line may be
straight or arcuate, the hinge itself being generally simple, although among
the Cytheridae hinge teeth and corresponding sockets are often developed.
There are commonly a small median and two larger lateral eyes ; the position

Mem. Soc. Roy. Sei. Liege, 1847, vol. iv. — Description des Entomostraces fossiles des terrains
tertiaires de la France et de la Belgique. Mem. Couronn. Acad. Roy. Belg., 1850, vol. xxiv. —
Monographie des crustaces fossiles du terrain cretace du Duche de Limburg. Mem. Commiss. Carte
geol. Nederlande. Haarlem, 185i. —Reuss, A. E., Die fossilen Entomostracen des österreichischen
Tertiärbeckens. Haid. naturw. Abhandl., 1850, vol. iii., pt. 1.— Die Foramiiiiferen und Entomo-
stracen des Kreidemergels von Lemberg. JMd. iv., pt. 1, lS61.~Jones, T. R., A Monograph of
the Entomostraca of the Cretaceous Formation of England. Palaeont. Soc, 1849.— Idem, and
Hinde, G. J., A Supplemental Monograph of the Cretaceous Entomostraca of England and Ireland.
Ibid., 1890.— Jones, T. R., A Monograph of the Tertiary Entomostraca of England. Ibid., 1857.
—Idem, and Sherborne, C. I)., A Supplemental Monograph of the Tertiary Entomostraca of
England Ibid., 1889.— Jones, T. R., and Kirkby, J. W., Notes on Palaeozoic bivalved Entomostraca,
Nos. 1-32. Ann. Mag. Nat. Hist., 1855-95.— Ä'^rprer, ()., Die Ostracoden der Miocänschichten bei
Ortenburg Neues Jahrb., 1858. -^Sjpeyer, 0. W. C, Die fossilen Ostracoden aus den Casseler
Tertiarbddimgen. Cassel Jahresber., 1863, vol. xiil-Brady, G. S., Crosskey, H. W., and
Robertson, D.,k Monogi-aph of the Post-Tertiary Entomostraca of Scotland. Palaeont. Soc, 1874.
-Jones, T. R Kirkby, J. W^nd Brady, G. S., A Monograph of the British Fossil bivalved
Entomostraca from the Carboniferous Formations. Ibid., 1874, \884..-Jones, T. A., and Holl,
H. B Notes on Palaeozoic bivalved Entomostraca. Ann. Mag. Nat. Hist., 1869, ser. 4, vol. iii.-
^Zf^' Ä^; ;'• *"^^^'!i«f' ■^- ^-^ A Monograph of the marine and fresh-water Ostracoda of the
Monn^tnW i'' o / ,''' T^"""' i^^^" ^"^^^"^ ^"^^ ^889-96, vols. iv., V . - Lienenklaus, K,
Monographie der Ostracoden des nord westdeutschen Tertiärs. Zeitschr. Deutsch. Geol. Ges., 1894,

Trans R;TSin\f'i«S« ^T^^^' ^^^ ,'^" ^" Carboniferous Ostracoda from Ireland: Sei.
Geol M^nn" pLl plf ' 1 "' ""'l' 'o To^^''^' ^' ^^ ^^e Lower Silurian Ostracoda of Minnesota.
Sat Sd 1897 vo? v' ^1-- "'•^?*- ^' IP^—^herborn, C. D., The literature of fossil Ostracods.
Zeitschr Dent^;rV^;rr''''^^^^^^^ ^^.^'^ Tertiär-Ostrakoden des mittleren Norddeutschlands.
Ber tnckenber^Nt rp?'F l^?' 'A^r^'^''''^ ^'^ Ostrakoden des Mainzer Tertiärbeckens.
R^ckfirCaDe Brefon ■ r 'nfr^ ^'^' .l^OÖ-J/a^^Äe.., G. F., Ostracoda of the basal Cambrian
^f Phvlloeari<fa Proo P^^^^ T' ^>^^.^^^ "°^- ^^^-Ohapman, F., Son.e Silurian Ostracoda
Ä / ^TneHean Palen^^^^ fw" ^^f"""' ^^^4' "• «' ^^^' ^^n.-Ulrich, E. 0., and Bassler,
Ä. *3., jNew American Paleozoic Ostracoda, pts. ii. and iii Proo TT q NnV M,i« lonfiiQOS
vol,. XXX., xxxv.-Miocene Ostracoda. Maryland Geol. Surv, Siocte Vot 1904 - ' '

SUBCLASS II EÜCRUSTACEA— OSTRACODA 737

of the latter being often indicated on the exterior of the valves by a small
" eye tubercle," or ocular spot.

Save for one or two families (Cypridae) Ostracods are almost wholly
restricted to marine or brackish water. They are gregarious, and occur in
vast hordes swimming near the surface or creeping over the bottom, preferring
usually shallow depths. Their remains abound in nearly all the principal
formations, and they are often important rock-builders. The identification of
fossil Ostracods is very difficult on account of their similarity of form and
ornamentation, and usually minute size ; and they cannot be well intercalated
among the recent series for reasons already given. Sars has arranged the
living forms into four divisions, Podocopa, Platycopa, Myodocopa and Cladocopa,
but assembling the families into higher groups is not attempted here, and
only the more representative genera can be noticed.

Family 1. Leperditiidae Jones.

Thick-shelled Ostracoda, mostly of considerahle size. Valves smooth and glossy, of
very compact structure, and in general regularly convex ; hinge-line straight ; anterior
and posterior ends ohliquely truncated or rounded, and neither gaping nor excised.

Leperditia Rouault (Fig. 1423). Shell sub-oblong with an oblique backward
Swing, from 2 mm. to 22 mm. long; dorsal edge straight, generally angular at the
extremities ; ventral outline rounded. Valves unequal, the right larger and over-
lapping ventral edge of
the left. Surface often
corneous in appearance,
smooth, and eye tubercle
generally present on
the antero-dorsal

quarter. A large

rounded sub - central p ,^23 ^^°' ^^^^'

1 • • . ■ ■ Inochilina gigantea Roemer.

muSCUiar impnnt pre- Leperditia Usingen Schmidt. Silurian ; Silurian erratic ; Lyck, East

sent on interior. Ordo- Wisby", Gotland. i/i- Prussia. • 2/3 (after F. Roemer).

vician to Carboniferous.

Leperditella Ulrich. Similar to above, but the left instead of right valve is the
larger, and has a groove within its ventral border for receiving the simple edge of
the right valve. Eye tubercle wanting. Length 1 mm. to 3 mm. Ordovician.

Isochilina Jones (Fig. 1424). Like Leperditia except that the valves do not over-
lap but are equal in every respect. Ordovician and Silurian.

Äparchites Jones. Shell not over 3 mm. in length, equivalve, sub-ovate or
oblong ; ventral edge thickened, often bevelled. Ordovician and Silurian.

Schmidtella Ulrich. Ordovician. Paraparchites Ulrich and Bassler. Carboni-
ferous : North America.

Hfefe^l^B H^^^p

Family 2. Beyrichiidae Jones.

Small equivalve Ostracoda with a long straight hinge. Shells vertically sulcated and
more or less lohate, varying from forms having a simple median depression to oihers in
ivhich the surface of the valves is raised into numerous low lohes^ ridges or nodes.

Primitiella Ulr. (Fig. 1425, a). Valves with a broad, undefined mesial depression
in the dorsal slope. Ordovician to Devonian.

VOL. I 3 B

^38 ARTHROPODA phylüm vii

Primitia Jones and Holl (Fig. 1425, h). Has well - marked subcentral pit or
sulcus with furrow extending to the hinge line. Ordovician to Permian.

mcZella Ulr. (Fig. 1425, d). Like Prirrntia but has horn-hke process on one
or both sides of the sulcus. Ordovician. , -, , • ^ x. vi

Ichmina J. and H. (Fig. 1425, c). Sulcus is replaced by a smgle, horn-like
process. Ordovician to Mississippian.

Ulrichia Jones. Ordovician to Mississippian. Synaphe, BeyncUops%s, Beynchiella
Jones and Kirkby. Carboniferous. . . . , . -, • -a a

Eurychilina Ulr. (Fig. 1425, g). Like Pn'mi^a but ventral margm provided
with a Wide, friU-like border. Ordovician and Silunan.

/ones^i^« Ulr. (Fig. 1425, f). Valves subovate with a curved ridge on the
posterior two-thirds. Ordovician and Silurian.

Fig. 1425.

Paleozoic Ostracoda. a, Primitiella unicornis Ulr. x i4/i. b, Friniitia ci-ricinnatiensis Miller, x i^/i. c,
.4ecfcmiTio margitiata Ulr. x i4/j. d, Dicranella hicornis Ulr. x lo/i. e, Ctenobolbina ciliata Emmons, x ^/i-
f, Jomsdla crepidiformis Ulr. x ^2/^. g^ Eurychilina reticulata Ulr. x lO/j. h, Halliella labrosa Ulr. x ^4/^,
i, Kloedenia centricornis Ulr. and Bass. x i^/^. j, Tetradella quadrilirata H. and W. x i3/j. fc, Ceratopsis
ckambersi Miller, x i2/j. i^ Kloedenella turgüki Ulr. and Bass.
n, Beyrichia clavata Kai. x i^/j. o, Drepanella crasdnoda Ulr.

l4/i, m, Kirkhya subquadrata Ulr. X ^^/j.
X lO/j. Pj Dilohella typa Ulr. x l^/j.

Bollia Jones and Holl. Valves with a central looped or horseshoe-shaped ridge.
Ordovician to Mississippian.

Tetradella Ulr. (Fig. 1425, j). Valves marked by four more or less curved
vertical ridges united ventrally. Ordovician and Silurian.

Geratopsis Ulr. (Fig. 1425, Je). Has a horn-like process arising from the ex-
tremity of the posterior ridge. Ordovician and Silurian.

Gtenoholbina (Fig. 1425, e), Drepanella (Fig. 1425, o), Halliella Ulr. (Fig. 1425,
h). Ordovician to Devonian.

Beyrichia M'Coy (Fig. 1425, n). Valve has three lobes or nodes with the central
one the smallest. Ordovician to Devonian.

Kloedenia Jones and Holl (Fig. 1425, i) ; Kloedenella Ulr. and Bass. (Fig.
1425, i). Silurian and Devonian. Dilohella Vir. (Fig. 14:25, p). Ordovician. Hollina,
Jonesina, Treposella Ulr. and Bass. Devonian to Carboniferous.

The following genera, doubtfully referred here, should perhaps be regarded as
Paleozoic Cytheridae :

Kirkhya Jones (Fig. 1425, w). Devonian to Permian. Moorea J. and K.
Ordovician to Permian. Strepula J. and H. Silurian and Devonian. Macronotella
Ulr. Ordovician.

SÜBCLASS II

EUCRUSTACEA— OSTRACODA

739

Family 3. Cytheridae Zenker.

Minute shells of generally elongate-oval, reniform or suh-quadrate outline, and of
dense structure. Surface smooth, punctate, nodulose, striate or spinöse; hinge generally
denticulated, the right valve with
two teeth in most cases, and the left
with corresponding pits.

Fossil species of this family are
very numerous in the marine deposits
of the Cretaceous and Tertiary. The
resemblance between Cythere and the
Devonian genus Strepula is so decided
as to indicate relationship.

Cythere Müller (Fig. 1426, a).
Shell reniform or subquadrate,
usually widest in front ; surface
variously ornamented ; hinge teeth
strong, placed one at each end of
a horizontal bar which fits into a corresponding furrow and sockets of the left valve.
Permian to Recent.

Gythereis Jones (Fig. 1427). Like Cyther
wanting. Cretaceous to Recent.

Gytheridea Bosq. (Fig. 1426, c). Differs from Cythere in having hinge beset with

Fig. 1426.

Valves of fossil Ostracoda. a, Cythere hassleri Ulr. x l^/j.

h, Cytheropterorv nochsum Ulr. and Bass. x 17/]. c, Cytheridea

2)erarcuata Ulr. x ^%. d, Pachydomella tumida Ulr. x l4/j.

e, Xestoleberismuelleriana(ha.m.). X 30/j. f, Octonaria Stigmata

X 18/i.

but connecting bar of the hinge is

Ulr.

Fio. 1427.
Gythereis quadrilatera Roeraer. Gault ; Folkestone, England, x 25/j (after T. Rupert Jones).

row of small teeth in right valve, often interrupted in the middle, and with corre-
sponding pits in the left valve. Jurassic to Recent.

Cytherideis Jones. Shell more or less triangulär ; hinge simple. Cretaceous to
Recent.

Carbonia Jones. Carboniferous. Cytheropteron (Fig. 1426, h), Xestoleberis (Fig.
1426, e) and Pseudocythere Sars. Tertiary to Recent.

Family 4. Thlipsuridae Jones.

Reniform or ovate inequivalve shells^ less than 2 mm. in length, the margin of one
valve overlapping that of the other more or less completely ; dorsal margin arcuate,
ventral sometimes straight or slightly sinuate. Surface with two or more deßnite pits.

Thlipsura Jones and Holl. Valve generally with three pits, one posterior and two
in the anterior half. No ornament. Silurian and Devonian.

Octonaria Jones (Fig. 1426, /). Differs from the last in having the surface of
valves raised into a thin spiral or annular ridge which in the more typical forms is
8-shaped. Silurian and Devonian.

Phreatura J. and K. Posterior end of shell strongly compressed and marked by
a shallow semicircular pit ; a similar but smaller pit is present at the anterior
extremity. Carboniferous.

740

ARTHROPODA

PHYLÜM VII

Family 5. Oypridae Zenker.

Minute, mostly reniform or elongate-ovate, corneous or corneo-calcareous shells, with
thin, somewhat unequal valves, one overlapping the other either ventrally or dorsally or
both.

Recent Cypridae are chiefly fresh-water inhabitants, biit this is true in a lesser
degree of the fossil forras. All the Paleozoic representatives are marine, excepting
perhaps certain Carboniferoiis species. Fossil remains are extraordinarily profuse in
certain deposits, and the family is an important rock-builder.

Palaeocypris Brongt. Shell 0*5 mm. long, sub-ovate, smaller posteriorly than in
front ; surface granulöse and finely hirsute in dorsal region. Carboniferous.

Cypris Müller (Fig. 1428). Shell reniform or oval, thin, translucent, smooth or
A hirsute, often punctate ; hinge edentulous, somewhat

thickened ; ventral margin often sinuate. Tertiary to
Q Recent.

Fio. 1428.

Cypris faha Desm. Miocene;
Oeningen, Switzerland. A, Dorsal, and

B, Lateral view. i5/j (after Bosquet).

C, Valves composing fresh-water lime-
stone at Nördlingen.

Fig. 1429.

Cypridea rvaldensis
Sowb. Wealden ; Ober-
kirchen, Hanover. i5/j.

Fig. 1430.

Bo.irdia curla M'Coy.
Low er Carboniferous ;
Ireland. 15/, (after
Kirkby).

Cypridea Bosq. (Fig. 1429). Like Cypris, but with a small hook-like projection
at the antero-ventral angle. Purbeck and Wealden.

Bairdia M'Coy (Fig. 1430). Shell sub- triangulär or rhomboidal, with the
greatest height near the middle, generally smooth, both extremities narrowly rounded
or pointed. Dorsal margin more or less strongly convex ; hinge formed by over-
lapping edge of left valve. Ordovician to Recent ; maxiraum in Carboniferous.

Bythocypris Brady. Shell smooth, reniform, ovate or elliptical ; left valve over-
lappmg the smaller right valve usually on both dorsal and ventral margins.
lypically Recent, but a number of Paleozoic forms have also been assigned to this
genus. °

Macrocypris Brady. Similar to the last, but generally more elongate, posteriorly
more acuminate, and the right valve larger than the left. Ordovician and Silurian ;
also Jurassic to Recent.

Pontocypris Sars. Like Bythocypris, except that the shell is very delicate, and
the hinge is simple without overlap. Silurian, Carboniferous, Pleistocene and Recent.

Family 6. Cytherellidae Sars.

Fio. 1481.

Cytherdln mmpressa
(Münst.). Oligocene ;
Rflppelnionde, Belginm.
22/, (after Bosquet):

_ Fmiily characters chiefly displayed by soft parts. Shell minute,
mequivalve, thick, calcareous, not notched anteriorly.

Cytherella Jones (Fig. 1431). Shell oblong or sub-ovate,
compressed m front ; surface generally smooth, but sometimes
undulatmg and marked with pits and granules. Contact margin
Ol the larger right valve grooved for reception of fiange-like
edge ofsma 1er left valve. Ordovician to Recent.

mr^If7 T^J^'T ^""^ ^"^^- ^il^ri^^- (?) Pachydomella
Ulrich (Flg. 1426, d) ■ Bosquetia Brady. Recent.

SUBCLASS II

EUCRUSTACEA— OSTRACODA

741

Family 7. Bntomidae Jones.

Shells relatively short, strongly convex, reniformj ovate or rounded quadrate, suh-
equivalve, with a more or less well-marked depression near the middle of dorsal region.
Surface sculpture concentric or radiale.

Entomis Jones (Figs. 1432, 1433). Shell sub-ovate or fabiform ; valves with a
slightly curved sub -median vertical
furrow extending to the hinge line ;
in front of furrow occasionally a
rounded tubercle. Surface marked
generally with raised, concentric,
transverse or longitudinal lines.
Ordovician to Carbon iferous ; very
profuse in Devonian.

Entomidella Jones. Like En-
tomis, but with furrow extending
entirely across the valves to ventral
edge. Ordovician and Silurian.

Elpe Barr. Shell reniform, 3
mm. to 7 mm. long, with depres-
sion just behind the middle of the
dorsal slope ; posterior half sometimes strongly inflated
Ordovician and Silurian.

Fio. 1432.

Entomis pelagica Barr.
Lower Devonian (F) ;
Konieprus, Bohemia.

Fig. 1433.

Entomis serrato-striata (Sandb.).
Upper Devonian ; Weilburg,
Nassau. Ä, Fragment of matrix,
i/i. B, Ventral and lateral aspects.
5/i. C, Impression of valve, 9/i.

Delicate radial ornament.

Family 8. Oypridinidae Sars.

Shells equivalve sub-elliptical to oblong^ convex, smooth or punctate, and sometimes
ribhed, especially in posterior half. Anterior end with a notch and hook-like hood over-
an opening left between edges of valves for protrusion of the lower antennae ;
ior extremity frequently acuminate.

Milne Edw. (Fig. 1434). Shell generally acuminate, oviform, rarely

Fig. 1434.

Cypridina primaeva^de
Kon.). Goal Measures ; Braid-
wood, England. «/^ (after
Jones, Kirkby and Brady).

Fig. 1435.

Cypridella wrightii J. K. and B. Lower
Carboniferous ;{ Cork, Ireland. **/i (after
Jones, Kirkby and Brady).

Fig. 1436.

Cyprella chrysalidea((le
Kon.). Lower Carboni-
ferous ; Cork, Ireland.
4/i (after Jones, Kirkby
and Brady).

oblong ; antero-dorsal edge projecting beak-like over the strongly defined notch ;
muscle spot large, sub-central, often visible on exterior. Ordovician to Recent.

Gypridinella J. K. and B. Like Cypridina, but having the antero- ventral region
projecting somewhat prow-like and generally beyond the hook. Carboniferous.

Gypridellina J. K. and B. Differs from the last in having a tubercle or lump
above the centre of the valve. Carboniferous.

Cypridella de Kon. (Fig. 1435). Like Cypridellina, except that it has a curved
sulcus behind the tubercle. Carboniferous.

Cyprella de Koninck (Fig. 1436). Shell much as in the last, but annulate.
Carboniferous.

Sulcuna, Rhombina J. K. and B. ; Cypresis, Cyprosina Jones. Paleozoic.

^42 ARTHROPODA phylum vii

Fainily 9.. Entomoconchidae.
Shell suh-cjlobose, more or less inequivalve ; anterior edge truncate and with central
Portion of nmrgin inturned so as to leave a simple or sinuate sht. Beah not developed.
Entomoconchus M'Coy ; Offa Jones, Kirkby and Brady. Carboniferous.

Geological Range of the Ostracoda.

Numerous supposed Ostracoda {Bradoria, Beyrichona, etc.) liave been described
from the Cambrian, biit all of these now prove to be Brancliiopods. The earliest
undoubted Ostracoda are indicated by a few species of Leperditia found m the
Beekmantown beds (Lower Ordovician) of Tennessee. Diiring the Middle and
Upper Ordovician these Crustaceans flourished greatly, and form excellent horizon
markers. The prevailing Ordovician and Sihirian types belong to the Leperditiidae
and Beyrichiidae, although toward the close of the Silurian numerous Cypridae make
their appearance.

Devonian Ostracoda are less numerous, but manifest essentially the same types as
in the earlier periods. Here, however, the larger Leperditiidae are entirely wanting.
Although many small species of archaic genera persist in the Carboniferous, the aspect
of the fauna is changed by the strong development of Cypridinidae. Thereafter
Ostracods are but sparsely represented until the Cretaceous, when certain genera,
especially Gythere, develop a surprising variety of species, Little difference can be
detected between Tertiary Ostracods and their modern descendants, although on
account of the facilities for studying the anatomy of the soft parts it has been possible
to distingiiish many more genera among the living forms.

[The above revision of the groups Branchiopoda and Ostracoda has been prepared by
Dr. R. S. Bassler.— Editor.]

Superorder 4. OIRRIPEDIA Bur meist er. Barnacles.^

Sessile, mostly hermaphroditic animals, endosed in a memhranous mantle which
is often covered with calcareous plates. Body attached by the anterior extremity of the

^ Literature : A. Recent Forms : — Thompson, J. V., Zoological Researches and Illustrations.

1. Cork, 1830. — Discovery of the Metamorphosis in the Lepades, etc. Phil. Trans. Roy. Soc, pt.

2, 1835. — Burmeister, H., Beiträge zur Naturgeschichte der Rankenfüssler. Berlin, 1834. — Martin-
Saint-Ange, G. J., Memoire sur l'organisation des Cirripedes. Mem. Savans Strang., Acad. Sei.,
Paris, 1835, vol. y\.— Darwin, C, A Monograph of the Sub-Class Clrripedia. Ray Soc, 1851-54,
vols. i., \i.—Hoek, P. P. C, Report on the Cirripedia. Rept. Challenger Exped., ZooL, viii., x.,
lS8Z-8i.—AtiHvülius, 0. W. S., Studien über Cirripeden. Svensk'. Vetensk. Akad. Handl., 1893,
vol xxvi., no. I.—Oroom, T. T., On the Early Development of the Cirripedia. Phil. Trans. Roy.
Soc, 1894, vol. c]xxxv.— Hansen, H. /., Phyllopoda and Cirripedia. Plankton Expedition, 1895.
—Oruvel, A., Monographie des Cirrhipedes. Paris, 1905.

B. Fossil Forms.— Sowerby, J., and /. de C, The Mineral Couchology of Great Britain.
London, 1812-30. — Roemer, F. A. Die Versteinerungen des norddeutschen Kreidegehirges. Hanover,
1840-41.— Z>amm, C, A Monograph of the Fossil Lepadidae of Great Britain. Palaeont. Soc,
1851.— A Monograph of the Fossil Balanidae and Verrucidae of Great Britain. Ibid., 1855.—
Bosquet, J., Monographie des Crustaces fossiles du terrain cretace du Duche de Limbourg. Mem.
Commiss. Carte geol. Nederlande, 1854.— Notice sur quelques Cirripedes recemment decouverts
dans les terraius cretaces du Duche de Limbourg. Haarlem, 1857.— Reuss, A. E., Ueber fossile
Lepadiden. Sitzungsber. Akad. Wiss. Wien, 1864, vol. x\\x.—Wood%oard, IL, On Turrilepas, etc.
Quar. Journ. Geol. Soc, 1865, vol. xxi.— Barrande, J., Systeme Silurien du centre de la Boheme,
I. Siippl., lS72.—Seguenza, G., Ricerche palaeontologiche intorno di Cirripedi terziarii della Provincia
dl Messma, Pts. i., ii., Naples, 1873-76. Marsson, J., Die Cirripeden und Ostracoden der weissen
Schreibkreide der Insel iRügen. Mittheil, naturw. Ver. Neu- Vorpommern und Rügen, 1880, vol.
xn.~Zütel, K. A., Bemerkungen über einige fossilen Lepaditen aus dem lithographischen Schiefer
und der oberen Kriede. Sitzungsber. Bayer. Akad. Wiss., 1884, vol. xiv.— Faber, ö. L., Remarks

süBCLASs II EUCRÜSTACEA— CIRRIPEDIA 743

head ; obscurely, and at times not at all segmented ; posterior' portion with at most
six pairs of himmous legs or cirri, which^ howevei\ may he fewer in numher or
altogether absent.

The typictal and best known Ciiripedes {Balanidae, Lepadidae) differ so
widely from all other Crustacea in their external form, solid calcareous shells,
slightly developed respiratory and sensory organs, and especially in their
hermaphroditic sexual apparatus, that until 1830 they were commonly classed
with the Mollusca. About this time J. V. Thompson and Burmeister showed
that these Cirripedes pass through a nauplius stage, and that directly before
attachment both Baianus and Lepas undergo a C?/p7S-stage, thus showing very
clearly their relation to the Eucrustacea.

All Cirripedes are marine animals. Those with calcareous shells attach
themselves to stones, wood, mollusks, crabs, corals and sea plants, and often
Cover rocky coasts in myriad numbers. Some genera {Coronula, Chelonohia)
attach themselves to whales and turtles ; some {Pyrgoma, Palaeocreusia)
become embedded in corals, and others bore into shells of mollusks or
lead a parasitic existence on Decapods or within the shells of other Cirripedes.
Most Barnacles inhabit shallow water, but certain genera occur at great
depths, from 1900 to 2000 fathoms (Scalpellum, Verruca). Many of the
living families are naked, and naturally only those possessing shells
(Thoracica) have left fossil remains, although some of the tubulär cavities in
molluscan shells may have been perforated by naked Cirripedes. Fossil
forms occur sparingly in the older strata, and do not become abundant until
near the close of the Tertiary.

Order 1. THORACICA Darwin.

Body indistinctly segmented, and enclosed in a membranous mantle in which calcare-
ous plates are usually developed. Six pairs of cirri present. Mostly hermaphroditic,
sometimes with complemental males.

The relations of the first two of the foUowing families to the other members of
the Order are conjectural.

Family 1. Lepidocoleidae Clarke.

Body covered with two vertical coliimns of overlapping plates, those of one series
alternating with those of the other. Terminal or caudal plate axial. Basal or cephalic
portion of the body with a ventral curvature. Apices of the plates on the dorsal margin.
No accessory plates.

Lepidocoleus Faber (Fig. 1437). Elongate, blade-shaped ; dorsal edge the thicker,
ventral edge sharper and linear. The two series of plates niake a complete enclosure,

on some Fossils of the Cincinnati Group. Journ. Cincin. Soc. Nat. Sei., 1887, vol. ii. — Hall, J.,
and Clarke, J. M., Palaeontology of New York, 1888, vol. y\\.— Clarke., J. M., Notes on certain
.Fossil Barnacles. Amer. Geol., 1896, vol. xwiu— Matthew, G. F., On occurrence of Cirripedes in the
Cambrian. Trans. N. Y. Acad. Sei., 1896, vol. xw.—Logan, W. N., Cirripeds from Cretaceous of
Kansas. Kansas Univ. Quar. 1897, vol. \\. — Woodward, H., Cirripedes from the Trimmingham
Chalk in Norfolk. Geol. Mag. 1906, dee. 5, vol. \n.~Idem, on the genus Laricula. Ibid., 1908,
vol. v.—De Alessandri, G., Studi monografici sui Cirripedi fossili d' Italia. Palaeontogr. Ital.,

1906, vol. xii. Idem, Osservazioni sopra aleuni Cirripedi fossili della Francia. Atti Soc. Ital.

Nat.,' Milano, 1907, vol. \\x.-~Reed, F. R. C, Structiire of Turrilepas and its allies. Roy. Soc.
Edinb., 1909, vol. xM. — Withers, T. H., The Cirripede genus Scalpelhim. Geol. Mag. 1910,
dee. 5 vol. vii.—Idem, The Cirripede Brachylepas cretacea H. Woodward. Ibid., 1912, vol. ix.

744

ARTHROPODA

PHTLUM VII

iilerlocked on the dorsal edge, biit are only in apposition on tlie ventral
edge, wliere tliey were undoubtedly capable of dehiscence for
the Protrusion of the appendages. This is tlie most primitive
geniis of the group. Ordovician to Devonian.

Family 2. Turrilepadidae Clarke.

Body with four to six vertical columns of triangulär plates,
two of the columns heing small, accessory and sometim.es much
modified in shape. Gaudal plate patelliform, axial.

Fid. 1437. Turrilepas Woodw, {Plumulites

Lepidocoieus mriei Clarke. Barr.) (Fig. 1438). Body elongate-

ventral views. large triangulär overlapping scales,

some of which are keeled in the
middle. Besides having concentric Striae, the surface may be
radially lined or punctated. Cambrian (?) to Upper Devonian.
Strohilepis Clarke. Composed of four columns of over-
lapping plates, two of which are of large and equal size.
Of the other two intervening columns, one consists of a
few very small plates, and the other is modified into a series
of grooved spines which appear to overlap one another at
their bases, and to lie opposite the column of small plates.

Fig. 1438.

Caudal extremity terminated by a circular
plate, against the sides of
column. Middle Devonian

Turrilepas ivrightianus de

. , . ^ Koninck. Silurian ; Dudley,

COnical, axial England. A, Complete indi-

plate, against_ the rides of which lies the first plate in each Ä entrged^a'fter' Wo"

ward).

Family 3. Lepadidae Darwin. (Goose Barnacles).

Shell pedunculated, composed mainly of the paired terga and scuta, the unpaired
canna, and a variable numher of small calcareous plates, some of which Cover the
flexible peduncle; others take part in the capitulum. The calcareous plates are never

Archaeolepas Zittel (Fig. 1439). Peduncle flattened, the two principal surfaces

Fio. 143'.».
Archaeoiejjax rei/lru-
hu;heri (Opp.). Litliu-
graphic Stone ; Kel-
heiin, Bavaria. Vi- C',
Carina ; R, Rostrum ;
'S, Scutum ; T, Terguni.

Fig. 1440.
A, Loricula laevissima Zitt
Senonian ; Dülmen, West-
phaha. Vi. B, C, Lorimla
•'j.VnocaDames. Cenomanian
Lifibanon.

Fig. 1441.

Scalpellum gallicum
Hebert. Upper Cretaee-
ous ; Meudon, near Paris.
'^/i (after Hebert).

Vi aiKi 2/j.
andaLnut:^.:3Xe"ClX::^^ä:ior^ unpai./ea.„a,

I

SUBCLASS II

EUCRUSTACEA— CIRRIPEDIA

745

Pollicipes Leacli (Polylepas Blainv.). Capitulimi coinposed of numerous (eighteen
to one hundred) plates, anioiig wliicli the scuta, terga, rostrum and carina are dis-

A

Capitulum of Scalpellum fossulum Darwin.
Upper Cretaceous ; Norwich, England. 2/j.
C, Carina ; L, Laterale superius (upper latus) ;
R, Rostrum ; S, Scutum ; T, Tergum ; cl,
Carino -.latus ; il, Infra • median latus ; rl,
Rostral latus ; sc, Sub-carina ; sr, Sub-rostrum
(after Darwin).

Fig. 1443.

Scalpellum fossulum Darwin.
Upper Cretaceous ; England.
Carina much enlarged (after
Darwin).

Fkj. 1444.

Lepas anatifera Linn.
Recent ; Mediterranean. C,
Carina ; P, Peduncle ; S,
Scutum ; T, Tergum.

tinguishable by their size. Lateralia generally in two columns. Peduncle mem-
branous with minute scales. Upper Jura to Recent. Doubtfully recorded from
the Silurian.

Squama, Stramentum Logan. Upper Cretaceous (Niobrara) ; Kansas.

Scalpellum Leacli (Figs. 1441-1443). Capitulum with twelve to fifteen pieces.
Terga and scuta much larger than in Pollicipes and of
very characteristic form. Carina narrow, long, with
arched surface. Peduncle covered with fine scales,
rarely naked. Cretaceous to Recent, and doubtfully
recorded from the Silurian.

Le2}as Linn. (Fig. 1444). Peduncle naked.
Capitulum consisting of only two very large tri-
angulär scuta, two small terga, and a single carina.
Pliocene and Recent.

Poecilasma Darwin. Capitulum consisting of
three, five or seven pieces. Carina extending only to
base of the terga, the
Scuta sub-oval. Tertiary and Recent.

Fig. 1445.
BrachyUpas naissanti (Hubert) ( =

latter sometimes wanting. P^M^^s^lo,vissim^Lsqx^en^t.)._ Upper

Rostrum ; s, Scutum ;
l, upper latus ; t, tergum ; c, carina ; i.s.,
imbricating plates. Vi (after Withers).

Family 4. Brachylepadidae H. Woodward.

Shell sessile, with a large numher of plates, the arrangement of which indicates a
transition from the Lepadidae towards the Balanidae.

The Single known genus Brachylepas H. Wood ward (Fig. 1445) occurs in the
Upper Senonian of England and the continent of Europe.

746

AETHROPODA

PHYLUM VII

Family 5. Verrucidae Darwin.
Shells sessile and composed of six pieces. Of the scuta and terga only those of one

side are free the others heing fused with the rostrum or canna.

The solitary genus Verruca Sclium., ranges from tlie Cretaceoiis to Recent.

Family 6. Balanidae Darwin. (Acorn Barnacles).

Shell ohtusely conical, cireular or oval in cross section, with hroad, offen calcareous
and cellular hase ; composed of four to ten '' compartments" more or less completely fused

at their sides, and two pairs of free terga and scuta
which dose the upper aperture like an operculum.

Of tlie lateral plates whicli compose the crown-
shaped immovable test, two are designated as carina
AB c

Fig. 1446.

Diagram of the sliell of Baianus. B,
Basis ; C, Carina ; CL, Carino - lateral
compartment ; L, Lateral compartinent ;
R, Rostrum ; RL, Rostro-lateral com-
partment. Each valve or "compart-
ment" consists of a central "paries" (p)
flanked by "alae" (a) or "radii " (r).

Fig. 1447.

Scutum and tergum of Baianus. A, External aspect of tergum,
sliowing "spur" below and "beak" above. B, Internal view of
scutum, showing muscular scar (x). C, Internal view of tergum
(after Darwin).

and rostrum, the pieces lying between and occurring in pairs being called lateralia. If
^ ;. additional plates are inserted

among the lateralia, they are
termed according to their position
rostro- or carino - lateralia. The
scuta and terga lie free oii the
back of the aniinal, and in fossil
forms are generally lost. They
have a very characteristic form,
and hence are of great systematic
importance. Since among fossil
species, however, only the mar-
ginal plates are for the most part
preserved, the determination of
their structural characters is often
quite uncertain.

Baianus Lister (Figs. 1446-
,. j . , i p . 1449), Shell low, conical or

cyhndncal, composed of six pieces. Opercular plates sub-triangiüar ; base membranous

or calcareous. Eocene to Recent.

Protohalanus Whitf. Affinities doubtful. Composed of twelve plates, of which

bas^"^ MWdL dIvoS ''''*'''"' ''^^^^' ^""^''^^'^ '"^ ^^^ ^^^^ ^'''^^ ^^^^ ^'^' *^'

Pn^.f-''''^^^'''"^' ^V^l,^^^^P°«^d of «ix solid pieces. Base calcareous, cup-shaped ;
epizoic on Sponges and Alcyonarians. Pliocene and Recent.

Fig. 1448.
Balanw concamis Bronn. Crag; Sutton, England. .4, Shell.
Vi (after Darwin).

B, Tergum. C, Scutum.

suBCLASs II EUCRUSTACEA— CIRRIPEDIA 747

Pyrgoma Leacli (Creusia Blainv.). Shell formed of a single piece. Base cup-
sliaped or sub-cylindrical ; epizoic on Corals. Lower Devoniaii (?). Tertiary and
Recent.

Palaeocreusia Clarke (Fig. 1450). Affinities doubtful. Sliell in one piece, with
a deep cylindrical base ; epizoic on corals. Lower Devonian.

Coronula Lam. Composed of six lateralia, with thin, deeply folded walls dividing

Fio. 1450.

Palaeocreusia devonica Clarke.
j^ j^j,j Embedded in Favosites. Middle De-

vonian (Onondaga limestone) ; Le
Baianus jyictus Münst. Miocene ; Dischingen, Würtemberg. Koy, New York.

the interior space into Chambers which open at the lower side of the shell. Base
niembranous ; epizoic on whales. Pliocene to Recent,

Ghthamahis Ranz. (Euraphia Conrad). Shell depressed, composed of six pieces.
Base membranous. Cretaceous, Miocene and Recent.

Pachylasma Darwin. Shell in the young with eight pieces, which afterwards become
six, or by coalescence of the lateralia are apparently reduced to four. Base calcareous.
Pliocene to Recent.

Superorder 5. MALACOSTRACA Latreille.

Eucrustacea having, in Recent forms, typically fourteen {rarely fifteen) hody-
somites hesides the telson. All the somites {except the fifteenth) bear appendages
which are differentiated into two groups, a thoracic of eight and an abdominal of
six pairs.

The Classification of the Malacostraca has undergone considerable modifi-
cations at the hands of zoologists within recent years, and further research is
necessary before some of the fossil forms can be assigned to their proper
places in the newer arrangements.

The basis of the new Classification is the recognition of the fact that what
has been called the " caridoid facies " is a common inheritance from the
primitive stock of the Malacostraca (possibly excepting the Phyllocarida),
and does not imply close affinity between the various groups presenting it.
The Chief characters that go to make up this facies are the stalked eyes, the
scale-like exopodite of the antenna, the thoracic carapace, the natatory
exopodites of the thoracic limbs, the large and ventrally flexed abdomen,
and the " tail-fan " formed by the uropods and telson. The group " Schizo-
poda " has long served as a receptacle for primitive forms possessing these
characters, and its dismemberment into the three orders, Anaspidacea,
Mysidacea and Euphausiacea, is attended by the inconvenience that the
characters distinguishing these Orders are but rarely to be discovered in
fossils.

n

ARTHKOPODA p^ylüm vii

748

Following is the scheme of Classification here adopted :-

Series I. Leptostraca.

Division A. Phyllocarida.
Order Nebaliacea.
Series IL Eumalacostraca.

Division A. Syncarida.
Order Anaspidacea.

Division B. Peracarida.

Order 1. Mysidacea.

„ 2. Cumacea.

„ 3. Tanaidacea.

„ 4. Isopoda.

,, 5. Amphipoda

Division C. Eucarida.

Order 1. Euphausiacea.
„ 2. Decapoda.

Division D. Hoplocarida.
Order Stomatopoda.

Series I. LEPTOSTRACA Claus.
Division A. PHYLLOCARIDA Packard/

Order 1. NEBALIACEA Calman.

Abdomen of seven somites (in the Becent forms), the last of which is without
appendages, and a telson bearing a pair of movaUe furcal raini. Carapace present,

1 Literature : Salter, J. W. , On some new Fossil Crustacea, etc. Quar. Journ. Geol. Soc, 1856-62,
vols. xii., xix. — On New Sihirian Crustacea. Ami. Mag. Nat. Hist., 1860, vol. v. — Hall, J.,
Palaeontology of New York, 1859, vol. iii.— 16tli Ann. Rept. N. Y. State Cabinet Nat. Hist., 1863.
—Woodward, IL, On a new Genus of Phyllopodous Crustacea. Quar. Journ. Geol. Soc, 1866,
vol. xxii.— Geol. Mag., 1872, 1882, 1SS5.— Claus, G., Ueber den Bau und die systematische
Stellung von Nebalia. Zeitschr. wissensch. Zool., 1872, vol. xxii. — Über den Organismus der
Nebaliden. Arb. zool. Inst. Wien, 1888, vol. viil—Baro'ande, J., Systeme Silurien du centre de
la Boheme, I. Suppl., 1872. — Etheridge, R., On Ditliyrocaris andAnthrapalaemon in Scotland. Quart,
Journ. Geol. Soc, 1879, vol. xxxw. — Whitßeld, R. P., Notice of new Forms of Fossil Crustacea,
etc Amer. Journ. Sei., 1880, vol. x\x.—Glarke, J. M., New Phyllopod Crustacea from the
Devonian. Amer. Journ. Sei., 1882, vol. xxiii. — New Discoveiies in Devonian Crustacea. Ihid., 1883,
vol. XXV. — Ueber deutsche oberdevonische Crustaceen. Neues Jahrb., 1884, vol. i. — On the
Structure of the Carapace in Rhinocaris, etc Amer. Nat., 1893, vol. xxvii. — 14th Rept. State
Geol. N. Y. I., 1898.— ^eec/ier, ö. E., Ceratiocarida, from the Upper Devonian Measures. 2nd Geol.
Surv. Penn. Rept. PPP, \^%\.—Idevi, Revision of the Phyllocarida from the Chemung andWaverly
Groups of Pennsylvania. Quar. Journ. Geol. Soc, 1902, vol. \\\\\.— Jones, T. R., and Woodward,
H., Various Papers in Geol. Mag., 1884-94, and Reports 1-12 of Comm. on Fossil Phyllopoda, Brit.
Assoc. Adv. Sei., 1883-95. — Novdk, 0., Remarques sur le genre Aristozoe. Sitzungsber. bohm.

süBCLAss II EUCKUSTACEA— PHYLLOCARIDA - 749

with a movahly articulated rostral plate. Eyes pedunculate ; thoracic limbs foliaceous y
no brood-plafes (oostegites) ; first four pairs of abdominal limbs biramous, last two
pairs reduced.

This definition is based on the characters of the Recent- genus Nebalia
(Fig. 1452) and its allies, which Packard first grouped together under the
name Phyllocarida with the fossils described below. Many of the fossils^
however, show important difFerences from the Recent genera {e,g. in the
number of abdominal somites) which may eventually require the establishment
of new Orders if they are to be retained within the division of Phyllocarida.

Cephalic appendages have not been satisfactorily determined in any fossil
species, although traces of them have been noticed in a few genera (Cryptozoe,
Ceratiocaris, Bhinocaris). In the absence of contrary evidence there is reason
to suppose that the appendages of the head, thorax and abdomen were
after the type of Nebalia, since there is close correspondence in the form of
carapace, rostrum and abdomen. Owing to the non-preservation of limbs,
distinctions within the group are based principally on differences in the
structure of the carapace, and in number of body - segments. Several
fossil genera (Echiriocaris, Bhinocaris, Mesothyra) bear
a distinct optic node or pit, suggesting a sessile
simple eye in contradistinction to the stalked facetted
eye of Nebalia. In these genera, also, large cuspidate
masticatory organs (Fig. 1451) have been found,
which were apparently attached only by means of
muscles ; these are compared by H. Woodward with
the gastric teeth of the lobster. From the Middle
Cambrian of British Columbia Walcott has described
wonderfully preserved specimens of Phyllocarida
(new species of Hymenocaris, etc.) showing append- fig. i45i.

ages, which will probably repay more detailed Gastric teeth of EcUnocaHs

.°'.,. ^ "^ ^ "^ punctata Hall. Hamilton ;

investlgatlOn. Pratt's Falls, New York, i/i-

Suborder A. NEBALIINA Clarke.

Carapace folded, univalved and rostrate.

Family 1. Nebaliidae Baird.

Cephalic appendages five, thoracic eight, abdominal eight, terminating in two caudal
spines. No metamorphosis ; development direct.

Nebalia Leach (Fig. 1452). Represented by a few marine species inhabiting
shallow waters. Paranebalia and Nebaliopsis are also Recent and marine.

Akad. Wissens., 1885. Ibid., 1886. — On Occurrence of a New Form of Discinocaris inBohemia.

Geol. Mag., 1892, dec, 3, vol. ix. — Sars, O. 0., Report on the Phyllocarida (Leptostraca). Rept.
Challenger 'Expedition, 1887, vol. ^ix.—Hall, J. and Clarke, J. M., Palaeontology of New York,

1888, vol. vii. Whitjleld, R. F., New Genus of Phyllocaridae. Bull. Ainer. Mus. Nat. Hist.,

1896^ vol. \\\(.— Jones, T. R., and Woodward, IL, Mouograph of the British Palaeozoic Phyllopoda
(Phyllocarida, Packard), Part iii. Palaeontogr. Soc, 1898.— C/a?7.r, /. M., Some Devonic and
Siluric Phyllocarida from New York. 54th Ann. Rept. N.Y. State Mus., 1900 {1902). — WaJcott,
C. D. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithson,
Mise. Coli. 1912, vol. Ivii. No. 6.

750

ARTHROPODA phylum vii

Suborder B. HYMENOCARINA Clarke.

Nebalia-like forms with folded univalved carapace ; rostrum loanting {T).

Family 1. Hymenocaridae Salter.

Body with eight to nine thoracic and abdominal segments, and six caudal spines in
three pairs.

Hymenocaris Salter (Fig. 1453). Carapace narrow in front, very broad posteriorly,
convcx ; >nrface smooth or faintly lined. Cambrian ; Wales and British Columbia.

Fig. 1452.
Nebalia geoffroyi M. Edw. Recent ; Mediterraneaii. s/j.

Fig. 1453,

Hymenocaris vermicauda Salter.
Upper Cambriau ; Dolgelly, Wales.
Vi (after Salter).

Several peciüiar genera described by Walcott under the names of Hurdia, Tuzoia,
Odaraittj Fieldia and Garnarvonia, from the Middle Cambrian of British Columbia,
are doubtfiilly referred to this family.

Suborder C. CERATIOCARINA Clarke.

Carapace hivalved, with a median Symphysis and a free rostrum.

Family 1. Oeratiocaridae Salter.
Carapace pod-shaped, smooth and without eye-nodes.

Ceratiocaris M'Coy {Entomocaris Whitf.) (Fig. 1454). Valves of carapace elongate,
^^^^^^s^^^^^^^^^-^s^r^'^'-^^ sub-ovate or sub-quadrate,

narrow in front, sub-
truncate, but not in-
■^ curved iDehind. Surface
without nodes or carinae.
Antennae (?) obscure; sup-
posed gastric teeth large,
cuspidate. Rostrum
lanceolate. Body Seg-
ments fourteen or more,
four to seven extending

- ■ ' ot them with obscure

Fig. 1454.

n.an.lil.les ; ,, Rostral plate. lA^gfter

branchial appendages

SUßCLASS II

EUCRUSTACEA— PHYLLOCARIDA

751

Cardiolites Nich. Supposed tracks of Geratiocaris (?). Silurian ; Scotland.

Garyocaris Salter. Carapace smooth, narrow, sub-acute in front, thick. Abdomen
unknown ; caudal plate with three spines. Cambrian ; Wales.

Physocaris Salter. Carapace bladder-sliaped, pointed in front, bivalved (?), smooth.
Abdomen smooth ; telson longer than the cercopods. Silurian.

Lingulocaris, Saccocaris Salter. Very imperfect remains of Crustacean bodies.
Lingula Flags ; Wales.

Acanthocaris Peacli. Carapace small, with a blunt snoiit in front ; surface smooth.
Body Segments numerous, seven exposed beyond the carapace. Telson long ; cercopods
short or rudimentarj. Lower Carboniferous ; Scotland.

Xiphidiocaris Jones and Woodw. (emend.). Known only by its long curved blade-
like telson. Silurian (Ludlow) ; England. (X. ensis Salter.)

Gryptozoe Packard. Carapace smooth, broadly rounded in front ; imperfectly
known. Coal Measures ; Illinois, (C. problematicus Packard). Probably congeneric
with the Carboniferous species named Geratiocaris oretonensis and G. truncata Woodw.,
in which traces of four cephalic appendages liave been found.

Golpocaris Meek. Carapace smooth, with deep anterior marginal sinus and sharp
extremity. Caudal plate with three spines. Lower Carboniferous ; Kentucky.

Strigocaris Vogdes (Solenocaris Meek). Carapace narrow and elongate, with
longitudinally striated surface ; very imperfectly known.
Lower Carboniferous ; Kentucky.

Nothozoe Barrande. Doubtfully assigned here. Ordovi-
cian ; Bohemia.

Phasganocaris Novak. Known only from the abdomen
and telson. Last segment long, cylindrical, with strong
articulation. Telson articulated to the cercopods by deep
sockets ; edges spinöse. Surface scaly. Lower Devonian ;
Bohemia.

Macrocaris Miller. Carapace valves very narrow in
front, broad behind, strongly lineate. Body segments
numerous. Lower Carboniferous ; Kentucky.

Family 2. Echinocaridae Clarke.

Garapace elongate or oval, with nodes (muscular or seg-
mental) in the cephalic region, one of ivhich in each valve
may he ocular hut hears no optic pit ; one or more lateral

carinae usually present.

A free rostrum has been

ohserved in some genera.

Echinocaris Whitf.
(Figs. 1451, 1455). Hinge
short, carapace sub-oval, Fig. 1455.

broad in front, not in- EcUnocaHs punctata (Hall),
curved behind nonn^tprn Hamilton Group ; Pratt's Falls,
curveu uenma, no postero- ^^^^ york. % (after Beecher).

lateral spinules ; a single

sigmoid carina on each valve, sometimes a small
accessory ridge near the hinge. Surface punctate
and pustulose, no longitudinal striations. Of the
body Segments, six are exposed and bear small
spines on their surface and posterior margins.
Pephricarishorriinlata ci&rk^. Cheiiiung Telson and cercopods are spines of unequal size.

Group; Alfred, New York Vi (after ■.-r-jji i tt ^ • -..-r , . ^ .

Clarke). Middle and Upper Devonian ; North America.

Fig. 1456.

762

ARTHROPODA phylum vii

Pephricaris Clarke (Fig. 1456). Carapace as in the last, but without the lateral
carinae. Margins provided with a single row of long recurving spines. Three or
four abdominal segments protrude beyond the carapace, the last two having a single
pair of long spines. Upper Devonian ; New York.

Aristozoe Barr. (Bactropus Barr.). Carapace with cephalic node well developed,
but without lateral carinae. But one abdominal segment known, and this is very
long, cylindrical, with an intricate hinge at the articulation with the caudal spines.
Telson a long spine with a row of spinules on each lateral edge. Noväk has shown
that of Barrande's three species, Aristozoe regina, Bactropus longipes and Geratiocaris
deUlis, the first represents the carapace, the second the last abdominal segment, and
the third the telson of one form, A. regina. Devonian ; Bohemia. Species referred
to the same genus have been described from the Cambrian of North America and
Devonian of Germany and Russia.

Orozoe and Callizoe Barrande are presumably allied to Aristozoe. Silurian ;
Bohemia. Zonozoe Barr, and Solenocaris Young are not Crustaceans.

Eleutherocaris Clarke. Carapace elongate-subquadrate, truncate in front, incurved
behind ; rostrate (?). Broad, obscure nodes in the cephalic region ; lateral carinae
Single, anterior and very short. Body segments unknown ; caudal plate with a
slender telson and cercopods of equal length. Surface pf all known parts more or less
ßtrongly tuberculated. Upper Devonian ; New York.

Ptychocaris Noväk. Valves elongate-subquadrate, posterior margin sloping or
slightly incurved. Cephalic region with a Cluster of small nodes in front, and two
larger nodes behind. Lateral region with a single long sigmoid carina. Surface
striated with raised longitudinal lines. Abdomen and tail unknown. Lower
Devonian ; Bohemia.

Elymocaris Beecher. Surface of carapace evenly convex, smooth, without lateral
carina ; hinge line long ; posterior margin convex ; cephalic
nodes obscure ; rostrum not observed. Abdomen with two ex-
posed segments ; caudal plate short, with broad convex, rapidly
tapering telson and two cercopods, setigerous on their inner
margins. Middle Devonian; New York. Upper Devonian;
Pennsylvania.

Tropidocaris Beecher (Fig. 1457). Carapace with truncate
posterior margins; ocular node well defined, other cephalic
nodes obscure; rostrum narrow and ridged ; surface of valves
Tropiöocaris ,üuriru.ta ^IT"^^ '^T^ longitudinal carinae. Abdomen with two
Beecher. Chemung exposed Segments, which are sub- cylindrical and without
ÄLandToTtrum'""/; 'Pf^^'^' ^P?^^ Devonian and Lower Carboniferous ; Penn-

(after Hall and Clarke). Sylvania.

, ..V ^. . ^'^'^'^^^oe Jones and Woodw. Valves of carapace elongate,
narrow, and with distinct ocular node; other cephalic nodes wanting. Surface tith
fine longitudinal raised Striae. Abdomen unknown. Silurian.

Suborder D. RHINOCARINA Clarke.

Family 1. Rhinocaridae Clarke.

rosierior margin of carapace concave and spined.

SUBCLASS II

EUCRUSTACEA— PHYLLOCARIDA

753

Rhinocaris Clarke (Fig. 1458). Carapace smooth, with fiiie raised longitudinal
Striae ; divergent, branchiiig furrows radiating backward from the eyes. Lateral
cariiia very faint. Abdomen with two or three free segments, the last much longer
than the others ; all diagonally striated or chevroned. Caudal plate with a broad

Fig. 1458.

Rhinocaris coluvibina Clarke. Ham-
ilton Group ; Canandaigua Lake, New
York. A, E, Dorsal and lateral views of
animal. B, D, Same of rostrum, en-
larged. C, Median plate, enlarged.

Fig. 1459 bis.

Mesothyra oceani Hall. Portage Group
(Upper Devonian) ; Ithaca, New York. A,
Eye. B, Hinge of right valve. i/i.

Fig. 1459.

Mesothyra oceani Hall. Upper Devonian ; New
York. Reconstruction of carapace and abdonien.
1/2 (after Hall and Clarke).

telson and two long and slender cercopods fimbriated on their margins. Middle
Devonian ; New York.

Mesothyra Hall and Clarke (Fig. 1459). Carapace large, valves distinctly inter-
locking at point of contact. Lateral carinae strong, crenulated at the summit.
Abdomen with two broad, exposed Segments. Telson shorter than the cercopods,
the latter setigerous. Upper Devonian ; New York.

Dithyrocaris Scouler {Ar gas Scouler). Very similar in aspect to Mesothyra^
with the junction line of the valves overlapped by a (free ?) rugose ridge or narrow
interstitial plate. Rostrum not observed. Devonian and Carboniferous ; Scotland.
Rachura Scudder, known only from the abdomen and telson, is probably allied to
Dithyrocaris. Carboniferous ; Illinois.

Ghaenocaris Jones and W. Carapace valves with a very strong lateral ridge and
without posterior spine. Carboniferous ; Scotland and Belgium.

VOL. I

3c

754

ARTHROPODA

PHYLUM VII

Suborder E. DISCINOCARINA Clarke.

Sub-circular or oval shields with a triangulär rostrum filling an anterior notch.
Sarface ornamented loith raised concentric lines. Suhstance chitinous.

Family 1. Discinocaridae Woodward.

Test convex, sometimes mesially ridyed ; m a smgle piece.

Discinocaris AVoodw. Shield sub-circular, rostral notch and rostrum angulai.
Abdominal segments and caudal spines have been referred to this
genus by Jones and Woodward. Silurian ; Great Britain,
Bohemia.

Aspidocaris Reuss. Similar to Discinocaris, Raibl Bedt^
(Upper Trias) ; Hallstadt.

Dipterocaris Clarke (Fig. 1460). Shield with a deep posterior
notch, shorter than the anterior or rostral notch. Sides of shield
sloping. Silurian ; Scotland. Upper Devonian ; New York.

Fig. 1460.

Dipterocaris rctustm
d'Arch. and Vern. De-
vonian ; Bifel. Vi-

Family 2. Peltocaridae Salter.

Shields mesially sutured.

Peltocaris Salter. Circular shields with a rounded rostral notch and plate.
Abdomen unknown. Ordovician ; Great Britain.

Aptychopsis Barr. (Fig. 1461). Like Peltocaris, but with the
rostral notch angular. Silurian ; Bohemia and Great Britain.

Pinnocaris Etheridge. Similar to Dipterocaris, but bivalved.
Ordovician ; Scotland. (P. lapworfhi Etheridge jun.)

Addendum.

Fi<i. 1461.

Aptychopsis primus
Barr. Ordovician (D) ;
Branik, Bohemia. i/i

A iiumber of generic names, such as Gardiocaris (Fig. 1462),

Ellipsocaris, Pholadocaris Wood ward, and Spathiocaris Clarke,

have been applied to Devonian fossils which closely resemble the

Silurian Discinocaris, of whose Crustacean nature there seems to

be no doubt. Some of these bodies, however (Gardiocaris), have

been found in the living Chamber of Goniatites (G. intumescens),

and have undoubtedly served as opercula or aptychi of these

Cephalopods; of others the nature is not fully understood.

Lisgocaris Clarke is not a Crustacean; Gryptocaris Barrande is

Fio. 1462. probably the operculum of a Hyolithoid ; Myocaris Salter is

(■urdioturis (Anapty- stated to be a Pelecypod ; Proricaris Baily was founded on

tvvlv'^i'^y'^ni^n] P*^^« of Geratiocaris ; Grescentilla and Pterocaris Barrande are

Bttdeslieini, Eitel. Vi- doubtfully Crustacean.

Series II. EUMALAOOSTRAOA Grobben.

Abdomen of six somites, all of which may hear appendages, and a telson which
never bears movable furcal rami Thoracic limbs rarely all similar, typically
pediform. ^ ^ jr j

The remains of Crustacea presenting the primitive "caridoid facies," as
described above occur in the Carboniferous, and it may be that the Eumala-
costraca had their origin in that epocli. If certain Devonian fossils are

SUBCLASS II

EUCRUSTACEA— SYNCAKIDA

•765

correctly assigned to the Isopoda, however, the origin of the series must
have been considerably earlier,

Division A. SYNCARIDA Packard.^

VIII

Order. ANASPIDACEA Calman.

Carapace absent. First thoracic somite fused with the headj or defined therefrom
hy a groove. Eyes pedunculate or
sessile. Thoracic legs typically with
exopodites ; no oostegites. , Uropods and
telson forming a tail-fan.

The name Syn-
carida was applied
hy Packard to a
group of Carboni-
ferous and Per-
mian Crustacea of
which the affinities
long remained ob-
scure. The dis-

covery, in

Anaspides tasmaniae Thomson.

Fig. 1463.
Recent ; Tasmania.

groove ; ii, viii, Second and eighth thoracic somites
dominal somites (after Calman).

Male,

; 1, 6,

>/i. c.gr, "Cervical
First and sixth ab-

the
fresh waters of
Tasmania and
Australia, of living forms with similar characters has thrown a new light on

Ä . B

Fig. 14Ö4

l'alueocaris typua Meek and Worthen. Goal Measures ; Illinois. A, Restoration of body, omitting eyes, 4/^.
B, Telson and uropods, 6/^ (after Packard).

the subject, and reinvestigation of some of the fossils has only emphasised
their close agreement with the Recent Anaspides (Fig. 1463) and its allies.
Of the fossil genera, Palaeocaris Meek and Worthen (Fraeanaspides

1 Literature : Jordan, H. , and Meyer, H. von, Crustaceen der Steinkohlenformation von
Saarbrücken. Palaeontogr. , 1854, vol. iv. — Brocchi, P., Note sur un Crustace, etc. Bnll. See.
Geol. France, 1880, ser. 3, vol. viii. — Fackard, A. S., On the Syncarida, etc. Mem. Nat. Acad.
Sei. Washington, 1886, vol. iii. — Thomson, G. M., On a fresh water Schizopod from Tasmania.
Trans. Linn. Soc. London (2) Zool., vi., 1894. — Calman, W. T., On the Genus Anaspides, etc.
Trans. Koy. Soc. Edinburgh, 1896, vol. xxxviii., pt. iv. — On Pleurocaris, etc. Geol. Mag.,
1911, dec. 5, vol. viii. — Fritsch, A., Fauna der Gaskohle, 1901, vol. iv., Heft 3, Crustacea, etc.
— Woodward, H., Some Coal-measure Crustaceans, etc. Geol. Mag., 1908, dec. 5, vol. v. —
Sayce, 0. A., On Koonunga cursor, etc. Trans. Linn. Soc. London (2) Zool., xi., 1908. —
Smith, G., On the Anaspidacea, living and fossil. Quart. Journ. Microsc. Sei., 1909, vol. liii.

756

ARTHROPODA

PHYLÜM VII

Woodward) (Fig. 1464), froni the Goal Measures of England and North
America, is now the most completely known. It resembles Anaspides in
general form, in the segmentation of the body, the pedunculated eyes, the
characters of antenniiles, antennae, and even of the minute mouth-parts^ the
exopodites of the thoracic legs, and the form of the tail-fan. The only
important difFerence between the two, apart from the delicate lamellar gills
which could hardly be looked for in a fossil, is the presence in Falaeocaris of
a wedge-shaped first thoracic somite, which, in Anaspides, is fused with the

head.

Uronectes Bronn (Gampsonyx Jordan and v. Meyer) (Fig. 1465), from the
Lower Permian of Saarbrücken, resembles Falaeocaris,
but has one of the anterior pairs of legs enlarged and
armed with spines. Acanthotelson
Meek and Worthen, and Pleurocaris
Calman, from the Goal Measures of
Illinois and of England respectively,
have the first thoracic somite fused
with the head and may perhaps have
no thoracic exopodites. These exo-
podites are also stated to be absent in
Gasocaris Fritsch, from the Permian
Gaskohle of Bohemia. Palaeorchestia
Zittel (Fig. . 1466) and Neäotelson
(FSr''''coarMeai" ^^occhi, are less completely known,
-es ; Lisek, near Beraun, and are doubtfullv included in this

ohemia. i/^ (after

Fio. 1465.

Fig. 1466.

Uronectes fimbriatus
(Jordan). Rothlie-
gendes ; Lebach, Saxony.
V,.

ures ;
Bc

Fritsch).

group.

Division B. PERACARIDA Calman.

Carapace, when present, leaving at hast four of the thoracic somites distinct ;
first thoracic somite always fused with the head. Eyes pedunculate or sessile.
Oostegites attached to some or all of the thoracic limbs in the female, forming a hrood-
pouch.

Of the Orders included in this division, two, the Cumacea and Tanaidacea
are unrepresented in the fossil state.

Order 1. MYSIDACBA Boas.i

I

The caridoid fades is retained. The carapace extends over the greater part of
the thoracic regton, but does not coalesce dorsally with more than three of the thoracic
somites.

Among the caridoid forms known from Carboniferous rocks, PygocephaUs
Huxley, from the Engl.sh Goal Measures, has recently been shown by

gSi 'so 1861 7of iSi «,;■ /*''''/™„''''°*^'' ''■'"" B""«'' Goal Meas„re.s. Q,,art. Journ
Sand ' /^ISs K vnx5ÄJ«;„°TTTh°^^ '" Carloniferous „f

A,ner. Journ. Sei., 1897, ser. 4, vö . iv -S,trrö'/? 0^^!t™*° P°„"""" °f ^''«S"*^. '^■
Mer,, 1907 ,lec S vol iv —P„irhn\r L""*""™; "■' On the genus Pygocepludm, etc. Geol.

of l^oUand. Men;.te„i:-S^^!t;eatB*kta° "fSs'' °" ''*'■''' °™^*»"^^°f Carboniferous Rocks

I

SÜBCLASS II

EUCRUSTACEA— PERACAEIDA

757

Fig. 1467.

H. Woodwtird to possess a brood-pouch formed of overlapping oostegites,

and may therefore be referred, with little doubt, to the Mysidacea.

Crangopsis Salter, from the Lower Carboniferous

of Scotland and the base of the VVaverly in

Kentucky is placed here by Ortmann, since it

has the posterior thoracic somites distinct beneath

the carapace. Anthrapalaemon Salter (Fig. 1467),

Pseudogalathea, Tealliocaris, and Palaemysis Peach,

all from the Carboniferous, have also been referred

to this Order.

Order 4. ISOPODA Latreille.i

Body usually hroad and dep-essed. Carapace
absent ; first thoracic somite, rarely also the second,
fused with the head. Abdomen short, the last somite
almost always coalesced with the telson. Eyes sessile.
Thoracic limbs without exopodites. Abdominal limbs
lamellar, branchial. , ,, , •,. ,c ^w

' Anthrapalaemon gracilis M. and W.

Of the earlier fossils that have been referred ?£. .ATXr»ieä"a°ntwor*™r'
to this Order, Oxyuropoda Carpenter and Swain

(Fig. 1468), from the Devonian of Ireland,
has the strongest claim to be regarded
as an Isopod. Its appearance earlier

^ Literature : A. On Recent Forms. — Beddard,
F. E. , Report on the Isopoda. Sei. Resiilts Challenger
Exped., Zool., xL, \^Sh.— Hansen, H. /., Isopoden,
Cumaceen und Stomatopoden der Plankton-Expedition.
Ergebn. Plankton- Exped., ii., 1895.— /^ew, On the
Family Sphaeromidae. Quart. Journ. Microsc. Sei.,
1905, n.s. vol. xlix. — Miers, E. /., Revision of the
Idoteidae. Journ. Linn. Soc. London, 1883, vol. xvi.
— Richardson, H. , Monograph on the Isopods of North
America. Bull. U.S. Nat. Mus., 1905, vol. liv.—
Sars, G. 0., An aecount of the Crustacea of Norway,
vol. ii. Isopoda. Bergen, 1896-99.

B. On Fossil Forms. — Ammon, L. von, Beitrag zur
Kenntniss der fossilen Asseln. Sitzungsber. Bayer.
Akad. Wiss., 1?>%2.—Andree, K., Zur Kenntniss der
Crustaeeen-Gattung Arthropleura Jordan. Palaeontogr.,
1910, vol. Ivii.— Carter, /., On fossil Isopods. Geol.
Mag., 1889, dec. 3, vol. vi. — Edwards, H. Milne, Sur
deux crustaces fossiles. Ann. Sei. Nat. Zool., 1843,
ser. 2, vol. xx. — Idem, On Archaeouiscus. Ann. Mag.
Nat. Hist., 1844, ser. 2, vol. xm.—Kunth, A.,
Crustaceen von Solenhofen. Zeitschr. Deutsch. Geol.
Ges., 1870, vol. xx\\.— Meyer, H. von, Ueber Palaeo-
niscus obtusus. Palaeontogr., 1858, vol. v. — Racovitza,
E. G., and Sevastos, R., Proidotea haugi, n.g., n.sp.,
etc. Arch. Zool. Exper. Paris, 1910, ser. 5, vol. vi.—
Reines, M., tJber Palaeosphaeroma tihligi, etc. Beitr.
Paläont. Geol. Österr. - Ungarn, 1903, vol. xv.—
Woodward, H., Several papers in Trans. Woolhope
Field Club, 1870 ; Geol. Mag., 1870, dec. 1, vol. vii. ;
1890, dec. 3, vol. vii. ; 1898, dec. 4, vol. \.—Idem,
On Squilla, etc. Quart. Journ. Geol. Soc, 1879, vol.
XXXV. — Carpenter G. H., and Sioain, /., A Devonian
Isopod. Proc. Roy. Irish Acad., 1908, vol. xxvii.

Fio. 1468.

Oxyuropoda ligioüles Carp. and Swain. Upper
Cid Red Sand.stone ; Kiltorcan, Ireland. a,
Portion of antenna ; c, Chela (?) ; o, Eye ; p,
Segment of body-limb ; u, Uropod ; 1-7,
Thoracic segments ; i.-vi., Abdominal segments.
Vi (after Carpenter and Swain).

758

ARTHROPODA

PHYLÜM VII

than the primitive caridoid forms may, however, justify some suspicion as
to it-s affinities. Fraearcturus Woodward, from the Old Red Sandstone of
Herefordshire, has very slender claims to be admitted into
this Order, and the same may be said of Amphipeltis Salter
(Devonian of Nova Scotia), and Arthropleura Jordan (Goal
Measures).

Undoubted Isopods appear in Secondary rocks. Urda
Münster (Fig. 1469), from the Kimmeridgian of Solenhofen,
has some very peculiar characters in which it approaches
the males of the Recent Gnathia, differing, however, in the
large size of the eyes. Cyclo sphaeroma Woodward, from the
Great Oolite and Purbeck, resembles in general form some
Recent members of the family Sphaeromidae, as do also
Archaeoniscus Milne Edwards (Fig. 1470), from the English
Purbeck and JEosphaeroma Wood ward (Fig. 1471), from the
Eocene and Miocene. Palaega Woodward (Fig. 1472),
Cenomanian and Oligocene, has a general resemblance to
the Recent Aega and allied genera. Proidotea Racovitza and Sevastos, from

Fig. 1469.

Urda rostrata Miüist.
Lithogiaphic Stone ;
Solenhofen, Bavaria,
Vi (after Kunth).

Fro. 1470.

A , Archaeoniscus brodei
M. Edw. Purbeck ; Vale
of Wardour, Wiltshire. 3/
(after Wootlward). ß, Frag-
ment of inatrix. i/, (after
Quenstedt).

Fig. 1471.

A, Eosphaeroma hrongniarti
M. Edw. Middle Oligocene ;
Butte de Chaumont, near
Paris. 3/1 (after Woodward).
B Fragment of matrix. i/i
(after Quenstedt).

Fig. 1472.

Palaega scrobiculata (v.
Ammon). Lower Oligo-
cene ; Haring, Tyrol. an,
Antennae ; 0, Eyes ; jß,
Uropod ; I-Vll, Thoracic
Segments ; 1-6, Abdominal
Segments.

Se^VaTvifera"' Eoumania, is closely allied to the Recent Mesidotea in th.

Order 5. AMPHIPODA Latreille.i

Body usualhj compre.sed latendly. Carapacs absent ; first thoracic somüe, more

• •, « .italogue of the Amplupoda in the British Museum, 1862.

4

suBCLASS II EUCRUSTACEA— EUCARIDA 759

rarely also the seconcl, fused with the head. Abdomen shorf, ventrally flexed, the
last somite usually distinct. Eyes sessile. Thoracic limhs ivithout exopodites, the
basal Segments usually lameUar, carrying gills. Abdominal
appendages divided into two sets, the last three pairs directed
backwards, sfyliform.

Although various Paleozoic fossils from the Silurian ^ _,

^ Fio 1473

{Necrogammarus Woodward) and later rocks have been Gammarus oeningensis
referred to this order, it is only in the Tertiary that Heer. Miocpiie ; Oenin-
undoubted Amphipods appear. Some of these, from the " ' ' ^'
Miocene, are referred to the Recent genus Gammarus Fabricius (Fig. 1473),
from which Palaeogammarus Zaddach, foiind in Baltic amber, is doubtfully
distinct.

Division C. EUCARIDA Oalman.

Carapace coalesced dorsally vnth all the thoracic somites. Eyes pediinculate,
No oostegites.

Order 1. EUPHAUSIACEA Boas.i

Caridoid forms in which none of the thoracic appendages are specialised as
maxillipeds and the gills are in a Single series attached to the bases of the thoracic
limbs.

Anthracophausia from the Calciferoiis Sandstone of Scotland is described
by Peach as belonging to this group, but the points of resemblance are very
slight.

Order 2. DBCAPODA Latreille.^

The caridoid fades may be retained or may be very greatly modified. The first
three pairs of thoracic limbs are specialised as maxillipeds and one or more of the

G. 0., An account of the Crustacea of Norway, vol. i,, Amphipoda, Christiana, 1890-95. — Stebbing,
T. R. R., Report on the Amphipoda, Scient. Resalts Challenger Exped., Zool., 1888, vol. xxix.
— Idem, Gammaridea, in Das Tierreich, 1906, vol. xxi. — Zaddach, (7., Ein Aniphipod im Bernstein.
Schriften physik. -Ökonom. Ges. Königsberg, 1864, vol. v,

^ For literature references see under the head of Mysidacea.

'^ Literature : A. On Recent Forms. — Älcock, A., Materials for a carcinological fauna of India,
nos. 1-6. Journ. Asiatic Soc. Bengal, 1895-1900, vols. Ixiv., Ixv., Ixvii. -Ixix. — Idem, Catalogues
of Calcutta Museum, 1899-1910. — Bäte, C. S. Report on the Crustacea Macrura. Scient. Results
Challenger Exped., Zool., 1888, vol. xxiv. — Boas, J. E. V., Studier over Decapodernes Slaegtskabs-
forhold. Dansk. Vidensk. Selsk. Skr., 1880, ser. 6, vol. i. — Borradaüe, L. A., Classification of
Decapod Crustaceans. Ann. Mag..Nat. Hist,, 1907, ser. 7, vol. xix. — Bouvier, E. L., Sur l'origine
homarienne des Grabes. Bull. Soc. I'hiloniath., Paris, 1896, ser. 8, vol. viii. — Faxon, W., Revision
of the Astacidae. Mem. Mus. Comp. Zool., Cambridge, 188.5, vol. x. — Idem, Stalk-eyed Crustacea.
Albatross Reports, xv. Op. dt., 1895, vol. xviii, — Henderson, J. R., Report on the Anomura.
Scient. Results Challenger Exped., Zool., 1888, vol. xxvii. — Herrick, F. H., The American Lobster.
Bull. U.S. Fish Comm., 1895, and Bull. Bureau Fisheries, 1911, vol. xxix.—Huxley, T. IL, On the
Classification and Distribution of the Craytishes. Proc. Zool. Soc, London, 1878. — Ortmann,
A. E., Die Decapoden-Krebse des Strassburger Museums. Zool. Jahrb. Abth. Syst., 1890-94,
vols. v.-vii. — Idem, Das System der Decapoden-Krebse. Op. cü., 1896, vol. xi. — Miers, E. J.,
Report 011 the Brachyura. Sei. Results Challenger Exped., 1886, vol. xvii.

B. On Fossil Forms. — Bell, T., Monograph of the fossil Malacostracous Crustacea of Great
Britain. Paleontogr. Soc, 1857-62. — Bittner, A., Brachyuren des vicentischen Tertiärgebirges.
Denkschr. Akad. Wiss., Wien, 1877-83, vols. xxxiv., xlvi. — Carter, J., On Orithopsis honneyi.
Geol. Mag., 1872, dec 1, vol. ix. — Idem, Contribution to the palaeontology of the Decapod Crustacea
of England. Quart. Journ. Geol. Soc, 1898, vol. liv. — Cushman, J. A., Fossil Crabs of the Gay
Head Miocene. Amer. Nat., 1905, vol. xxxix. — Etallon, A., Description des crustaces fossiles.

ARTHROPODA ^hylum vii

77 . .h^inU The Ollis are typically in several series attached

'^\^cl.^^CZ,lf^^^ forerunners of this lavge and va.ied order.
Suborder A. NATANTIA Boas.

aMoul Z2ch Jdler tLn the others. Leg. shnder, someH^es mlh «opodtcs
ttyoTe oT'hTfirst three fain r.ay U enUrged. AMominal affendages ^ell deveU^ed,^
used for swimming. . 4

bf tlie three tribes which compose this suborder, the Penaeidea ^näStenopidea'
a»ree in having the fl..t three pairs of legs chelate (with a few exoeptions m the
P„««-«,a,/the side-plates „f the second aHonunal — ^not expand^d ; ^he.

legs is mucli larger than the
first in the Stenopidea, but not
in the Penaeidea. The Caridea
never have the third pair of
legs chelate, and have the
side-plates of the second ab-
dominal somite expanded to
^ overlap those of the somites

Fio. 1474. in front and behind.

Peuaeus meyeri Oppel. Upper Jura (Lithographie Stone) ; The Penaeidea are SOme-

Solenhofen. 1/2. ^j^^^ doubtfully represented

in the Trias, but a long series of fossils from the Solenhofen Lithographie Stone can
be referred with certainty to this tribe. Some of these are inchided in the Kecent
genus Penaeus Fabricius (Fig. 1474), while Äcanthochirus Oppel, Bylgia, Drohna an^
Dusa Münster are extinct genera.

The Stenopidea comprise a small number of Recent forms which show some

Bull. Soc. Geol. France, 1859, ser. 2, vol. xvu—Früsch, Ä., Über die Caliaiiassen der böhmischen
Kreide. Abhandl. Böhm. Ges. Wiss., 1868, vd. \iy.— Knebel, W. von. Die Eryoniden des oberen
Weissen Jura von Süddeutschland. Arch. Biontol., 1907, vol. ii. — Lörenthey, K, Über die Brachy-
uren der paläont. Sammlung des Bayer. Staates Termeszet Füzetek, Budapest, 1898, vol. xxi. —
Idem, Beiträge zur Decapodenfauna des ungarischen Tfertiärs. Math.-naturw. Ber. aus Ungarn,
1898, 1903, vols. xiv., xviii. — Idem, Paläontol. Studien über tertiären Decapoden. Op. cit., 1907,
vol. xxi. — Idem, Beiträge zur tertiären Decapodenfauna Sardiniens und Ägyptens. Op. cit., 1908,
1909, vols. xxiv., XXV. — Mark, W. von der, Fossile Fische, Krebse und Pflanzen aus der Kreide.
Palaeontogr., 1863, vol. xi. — Idem, and Schlüter, C, Neue Fische und Krebse aus der Kreide von
Westphalen. Op.ciL, 1868, vol. xv. — Meyer, H. von, Neue Gattungen fossiler Krebse. Stuttgart,
1840. — Moericke, W., Die Crustaceen der Stramberger Schichten. Palaeontogr., 1897, Supplem.
vol. ii. — Oppel, A., Ueber jurassische Crustaceen. Palaeont. Mittheil. Mus. Bayer. Staates, 1862,
vol. ii. — Ortmann, A. E., On Limiparus in the Upper Cretaceous of Dakota. Anier. Journ. Sei.,
1897, ser. 4, vol. iv. — Pilshry, H. A., Crustacea of the Cretaceous formation of New Jersey.
Proc. Acad. Nat. Sei. Philad., 1901, vol. in.— Rathhun, M. J., Descriptions of fossil crabs from
California. Proc. U.S. Nat. Mus., 1908, vol. xxxv. — Schlüter, C, Die Macruren-Decapoden
Westphalens. Zeitschr. Deutsch. Geol. Ges., 1862, vol. xiv.— Idem, Kreide- und Tertiär-Krebse des
nördlichen Deutschlands. Op. cit., 1879, vol. xxxi. — Idem, Podocrates im Senon von
Braunschweig. Op. cit., 1899, vol. W.—Stimpson, W., Fossil Crab from Gay Head. Journ.
Boston Soc. Nat. Hist., 1863, vol. vii. — Tribolet, M., Descriptions des crustacees du terrain
neocomien. Bull. Soc. Geol. France, 1874-75, ser. 3, vols. ii., in. — Whitfield, R. F., American
species of /yo2?Zq/?aria. Bull. Anier. Mus. Nat. Hist., 1907, vol. xxiii. — H^mÄ;Zer, T. C, Etudes sur
les genres Pemphix, Glyphaea, etc. Arch. Mus. Teyler, 1883, ser. 2, vol. i.~Woodward, H.,
Macrurous Crustacea, etc. Quart. Journ. Geol. Soc, 1872-76, vols. xxix., xxxii.

SUBCLASS II

EÜCRUSTACEA— EUCARIDA

761

affinities vvitli the Reptantia. The extinct genus Aeyer (Fig. 1475), whicli has
representatives in tlie Trias and also in tlie Solenliofen Lithograjjliic Stone, agrees
w'ith the Recent genera in having the third pair of legs chelate and much larger
than the first. It is, in all probability, a primitive member of this tribe.

Representatives of the Caridea are not known with certainty earlier than the
Kinimeridgian, though some Carboniferous fossils have been described as having the
enlarged side-plates of the second abdominal somite, which are characteristic of this
tribe. In the Solenliofen Stone numerous genera occur, some of which, such as Udora
Münster, and Udorella Oppel, have exopodites on the thoracic legs, a primitive
character suggesting affinity with the Recent family Acanthephyridae. Other
Solenhofen genera, in which these exopodites appear to be wanting, are Blaculla^

Fig. 1475.
Aeger tijndariiis (Schloth.). Upper Jura (Lithographie Stone) ; Eichstädt, Bavaria. 2/3.

Hefriga and Eider Münster. The Recent deep-sea genus Oplophorus Milne Edwards
(Acanthephyridae) has been identified, with considerable probability, in the Upper
Cretaceous of Westphalia. Some Caridea are found in fresh-water Tertiary deposits,
as for example Homelys von Meyer, from the Miocene of Oeningen ; but it is
impossible to say what relation they bear to the groups of Recent Caridea that have a
fresh-water habitat.

Suborder B. REPTANTIA Boas.

Body often depressed, rostrum often ahsent^ small and depressed if present. First
somite qf abdomen distinctly smaller than the others. Legs stout, without exopodites,
the first pair usually much larger than the others. First five pairs of abdominal
appendages commonly small, not used for swimming.

§ 1. Palinura.

This section consists of lobster-like forms with the rostrum very small or often
absent, with the carapace fused at the sides with the epistome, and the exopodite of
the uropods not divided by a distinct suture. It includes two tribes (1) the Eryonidea
and (2) the Scyllaridea (or Loricata).

The Eryonidea comprise, among living forms, only a small number of genera
such as Polycheles Heller, and Willemoesia Grote, which have chelae on the first four or

762

ARTHROPOBA

PHYLUM VII

■ f u^ AU are blind aud inhabit only the deep sea The fossil
on all live pairs of e^. /;" *'^; ^.^^ j,, ^^allow water and probably poBsessed

Fio. 1476.
/w.von. rrojdn'iuus (Schlotli.)- Lithographie Stone ; Solenliofen , Bavaria. I/o.

Desmarest (Fig. 1476), of whicli finely preserved specimens are foimd in tlie Upper

Jurassic Solenhofen Stone, ranges from tlie Lias (perliaps the Trias) to tlie Neocomian.

The Scyllaridea, which are distingiüshed, among other characters, by liavmg the

Fic. 1477.
Mecochiras lojuiivMum (tichloüi.). Lithographie Stone ; Eiehstädt, Bavaria. 1/2-

tirst pair of legs imperfectly chelate, include the Spiny Lobsters {Falinuridae)
and their allies, The earlier forms should probably all be referred to the
extinct family Glyphaeidae, of which, the first representatives occur in the Trias.
Pemphix von Meyer (Fig. 1478) occurs in the Muschelkalk. Lithogaster and
Glyphnea von Meyer (Fig. 1479) ränge froni Trias to Cretaceous. Pseudoglyphaea

SÜBCLASS II

EUCRUSTACEA— EUCARIDA

763

Oppel is Jurassic. Scajjheus and Preatya Woodward are Liassic. Mecochirus Kef.

(Fig. 1477) is foimd in the Middle and Upper Jura, and Meyeria M'Coy, in tlie

Neocomian. All of these have a more or less
distinct rostruni and the antennae moderately
developed.

Palinurina Münster, froni the Lower Lias and
Solenhofen Stone, appears to be a member of the
Palinuridae, a family which has the rostriim sup-
pressed and the antennae very stout. Podocrates
Geinitz, from Upper Cretaceous and Eocene is
hardly to be distinguished from the Recent Linu-
parus Gray. Gancrinus Münster, from Solenhofen,
which has the antennae short and very broad,
perhaps leads toward the Scyllaridae, in which the
antennae form broad flattened plates. Scyllaridia

Fig. 1478.

Pf.mphix .t)imrii Desm. Muschelkalk ; Crailsheim,
Würtemberg. i/i.

Fig. 1479.
Glyphaea tenuis Oppel. Lithographie Stone ;
Eichstädt, Bavaria. A, Side-view, i/i- ß, Rostral
region enlarged. a, a", First and second pairs of
antennae ; o, Eye ; s, Antennal scale ; f<t, Base of
second pair of antennae.

Bell is foLind in the Gault and London Clay, while the Recent Scyllarus Fabr. first
appears in the Chalk.

§ 2. AsTACURA. Lobsters and Crayfishes.

This section comprises only the tribe Nephropsidea (Astacidea) including the true
Lobsters and Crayfishes. In these, the rostrum is of moderate size, the carapace is
free from the epistome, and the exopodite of the uropods is divided by a suture.
The first three pairs of legs are chelate and the first pair is greatly enlarged.

The earliest member of this groiip is Eryma v. Meyer (Fig. 1480), found in the
Lias, and also occurring, together with Pseudoastacus, Stenochirus and Etallonia Oppel,
in the Solenhofen limestone. Isolated chelae of Magila (Fig. 1481) are abundant
throiighout the Jura. Enoploclytia M'Coy; Nijmphaeops Schlüter; Oncoparia Bosquet;

ARTHROPODA

PHYLÜM VII

-, rr 7 • M^nr^^r nppnrin tlieUDPei'Cretaceousof Westplialia,
Palaeastacus Bell ; and H<^,lopar«, M<.oy omr in the L pp ^ ^^ ^^^^^

lioliemia and England, the last-named genus also ''-''''"^uUinDy, the Eecent

geiiera which include the

Lübster/ the Crayfish of

Eiirope, and the Norway

Fio. 1481. Lobster {Nephroms of Leach),

Magih, " suwajurensis have beeil stated to occiir

(Quenstedt). Upper Jura; ^^ e^rlv as the Upper Cre-
Söflingen, Würteinberg. -^

d

Chela.

taceoiis.

Fk;. 1482.

Callianaffsa arcUaci M. Edw. Tnronian ; Montdragon,

Var (after Milne Edwards).

Fia. 1480.

Eryma leptoiiactyliTia (Germ.). Litho-
graphie Stone ; Solenhofen, Bavaria. i/i
(after Oppel).

Callimiassa antiqua Otto. Turonian ; Turnau, Bohemia.
Eight chela.

§ 3. Anomura.

This section includes forms which have the abdomen generally soft or bent upoii
itself, with reduced side-plates and tail-fan. They are rare as fossils. The tribe
Galatheidea is represented only by chelae from the Upper Cretaceous of Denmark,
referred to the Recent Galathea Fabr. Of the tribe Thalassinidea, the Recent
geniis Gallianassa Leach (Figs. 1482, 1483) is known from the Kimmeridgian, as
well as from the Cretaceous and Tertiary. Thalassina Latreille is Tertiary and
Recent. The tribe Paguridea, including the Hermit-crabs and their allies, is very
doubtfully represented in the Eocene of Hungary by chelae referred to the Recent
Pagurus Fabr. The Hippidea are unknown in the fossil state.

§ 4. Brachyüra. True Crabs.

The true Crabs have the abdomen small, bent under the thorax, and without a
tail-fan ; the carapace fused with the epistome at the sides and nearly always in the
middle line in front ; the third maxillipeds more or less broad and flattened, covering
the other mouth-parts.

1 The generic name Homarus Milne Edw. is most commonly used for the Lobster, and Astacus
Fabr. for the Crayfish. Some writers, however, employ Astacus Fabr. for the Lobster, and
PotainoUm Leach for the European Crayfish. The questions of nomenclature involved cannot suit-
ably be discussed here, but reference may be made to a recent ruling (1910) of the International
Commission on Zoological Nomenclature.

SUBCLASS II

EÜCßUSTACEA— EUCARIDA

765

The Dromiacea take the lowest place among the tribes composing this section,
differing from the more specialised Brachyura in retainiiig iiiany primitive characters.
Thus, the last somite of the abdomen often retains vestiges of uropods, the first
abdominal somite of the female has a pair of appendages, the fossettes for the reception
of the antennules are less cleaiiy defined, and the gills are more numeroiis.

Among the Recent Dromiacea, again, the family Homolodromiidae is the most
primitive, its members, which inhabit the deep sea, presenting many features which

C^^}

Fig. 1484.

A, Prosopon marginatum v. Meyer. Upper Jura (e); Oerlinger Valley,
near Ulm. s/g. B, P. personatum. Upper Jura (y) ; Weissingen, Würtem-
berg. Rostrum enlarged. C, P. amleatum v. Meyer. Same locality as A.
D, P, pnstulaium Quenst. Same locality as A.

Fig. 1485.

Dromiopsis rugosa
(Schloth.). Uppermost Cre-
taceous ; Faxoe, Denmark,

l^l '

link them with the Lobsters of the tribe Nephropsidea. It is therefore of special
interest to find, as Bouvier has shown, that the earliest fossil Brachyura, forming the
extinct family Prosoponidae, are allied, by the form of the carapace and the disposition
of the grooves upon it, to the existing Homolodromiidae. In the majority of cases
the carapace alone is preserved, but portions of the abdomen and limbs are known in
Protocarcinus (Palaeinachus) Woodward, from the Forest Marble (Bathonian) of
England. The genus Prosopon von Meyer (Fig. 1484) is of even earlier date,
appearing in the Bajocian and persisting to the Neocomian. Later forms approach
more specialised Recent types, such as Homolopsis Bell from the Gault, leading towards
the Homolidae; and Dromiopsis Reuss (Fig. 1485), leading towards the Dromiidae.
The Tertiary Dromilites Milne Edwards, is scarcely different from the Recent Dromia.
The tribe Oxystomata is characterised by the form of the mouth-frame, which is
triangulär and produced to the front of the head between the eyes. The earliest
example of the tribe is Mithracites Gould,
from the Lower Greensand. Palaeocorystes
Bell (Fig. 1486), ranges from the Gault
to the Eocene. Eucorystes and Necrocar-
cinus Bell (Fig. 1487), are found in the
Gault and Upper Greensand. The precise
relations of these to modern families are
doubtful. The Recent Calappa and
Matuta Fabr., however, are known from yw. i486.

Eocene and later deposits. Palaeocorystes stokesi

The remarkable family Raninidae, Jf^eeisand ; ^Cam^
distinguished by the unusual form of the bridge, England,
chelae and by the elongate carapace,

which is broader in front than behind, is known as early as the Cenomanian chalk,
and its representatives are not rare in the Tertiary. Raniella and Raninoides
Milne Edwards, are Cretaceous genera. Of the few Recent genera, Ranina Lamarck
(Fig. 1488) is known from the Eocene.

The tribe Brachygnatha, in which the mouth-frame is quadrate, includes the great
majority of the Brachyura. It is divided into two subtribes, the Oxyrhyncha and.
Brachyrhyncha.

Fio. 1487.

Necrocarcinus' tricarinatus
Bell. Greensand ; Cam-
bridge, England (after Bell).

766

ARTHROPODA

PHYLUM VII

The Oxyrhyncka have the carapace narrowed in front and produced into a more
distinct rostrum. Fossil forms are few and generally rather small.

A, B, Ilanina marestiana König (=ß. helli Schafli.). Bocene ; Kressenbeig, Bavaria. Ventral and
dorsal views. C, Chela of R. bouükana M. Edw. Eocene ; Biarritz, France. 1/2-

Micromaia Bittner

Fig. 1489.

Micromaia tuherculata
Bittner. Eocene ; San
Giovanni lUarione, Italy.
(After Bittner.)

lateral. Since, however, it
they are not separated in
the more recent Systems of
Classification.

The Catometopous
families -are not well repre-
sented among fossils. Litho-
phylax Milne Edwards,
from the Upper Cretaceous,
is an early and somewhat
doubtful form. Galenopsis
and Coeloma Milne Edwards
(Fig. 1490) ; Litoricola
Woodward ; and Palaeo-
grapsus Bittner, are known
from the Eocene and Oligo-
ce^e. The Recent Gecar-

and Microthorax Noetling, are Eocene and
Miocene forms respectively.
The Recent Lamhrus Leach
is known from the Eocene,
and Maia Lamarck from
the Pliocene.

The subtribe Brachy-
rhyncha includes a large
number of families which
are often divided into two
gronps : ( 1 ) the Cyclome-
topa, with the carapace
broad and arcuate in
front ; and (2) the Gatome-
topa, in which the carapace
is more or less quadri-
impossible to distinguish the two groups sharply.

Fig. 1490.

Coeloma vigil M. Edw. Eocene
Laverda, Italy.

Lobocarcinus pauUno vjuertemhergicus v. Meyer. Eocene '
Mokkatam, near Cairo, Egypt. Male.

SUBCLASS IT

EUCRUSTACEA— EUCARIDA

■67

cinus Leach, is stated to occur in the fresh -water Miocene deposits of Oeningen.
Archaeoplax Stimpson is found in the Miocene of Gay Head, Massachusetts.

The Cyclometopoiis faniilies have niany representatives in the Tertiary and a few
in the Cretaceous. The earliest are of Ccnomanian age, inchiding Etyus Mantell and,

Xanthopsiti kre.->'sniberg(msis v. Meyer.

Fio. 1492.
Eoceiie ; Kressenberg, Bavaria. Male,

?ntral aiul dorsal aspects, 1/2.

doubtfully, the Recent Xantho Leach. Titanocarcinus and Palaeocarpüius Milne
Edwards, appear in the Upper Cretaceous. The Recent Panopeus Milne Edwards, is
Said to date back to the Cretaceous. In the Eocene are found Harpactocarcinus Milne
Edwards ; Lohocarcinus Reuss (Fig. 1491) ; Xanthopsis M'Coy (Figs. 1492, 1493) ; and
Neptocarcinus and Carcinocarcinus Lorenthey. The Recent genera Cancer Linn. ;
Ätergatis de Haan ; and Etisus Milne Edwards, are recorded from the Upper Eocene,

Ficj. 1493.

Xonthopsiiihruckraanniv. Meyer. Eocene; Sonthofen,
Bavaria. Ventral view of female, Vi-

Fig. 1494.

l'mmmoair cinus hericarti (Desni.). Middle Meeressanci
(Miocene) ; Le Giie-ä-Tresraes, France (after» A. Milne
Edwards).

although the demonstration of their precise identity with Recent forms is not in all
cases satisfactory.

The easily recognised Swimming-crabs of the family Portunidae are certainly
represented as early as the Eocene by such forius as Psammocarcinus Milne Edwards
(Fig. 1494); Portunites Bell ; and the B.ecent Neptunus de Haan. The River-crabs
{Potamonidae) are said to be represented in the fresh-water Miocene of Oeningen by
the Recent genus Potamon Savigny {Thelphusa Latreille).

768

ARTHROPODA

PHYLUM VII

Division D. HOPLOCARIDA Calman.
Order 1. STOMATOPODA Latreille.i

Carapace small, leaving at hast four of the thoracic somües dM and mv
covered with a movable rostral plate anteriorly. Eyes pedunculate Eyes ard
Znnules hörne on raovahle segments of the head. First fivepans of thoracu hmls
^b.chelaie, the second pair very large. Abdomen largeand depressed, endmg ^n a
taü-fan. First five pairs of abdominal appendages carrymg tufted güls.

The existing Stomatopods form a very homogeneous group, within which
onlv one family (Squillidae) can be recognised, while many of the genera are
separated by comparatively slight differences. Representative forms are
Squüla Y^hr ■ LysiosquiUa ^nd PseudüsquillaB^nii ; Gonodactylus L^treiWe ; ^nd
Coronida Brooks. Modern Stomatopods are exclusively marine, the adults

generally inhabitmg burrows
in the sand or mud of the sea-
bottom in shallow water, chiefly
in the tropics, but extend-
ing also 50 degrees on either
side of the equator. Many
species seem never to wander
far from their burrows, into
which they retreat with great
rapidity when alarmed. The
larval stages, on the other
band, are exclusively pelagic,
of glass-like transparen cy, and
occur in great numbers in the
plankton of the warmer seas.
All the Stomatopods appear
to be of active, predatory
habits. They ränge in size
approximately from 38 to
340 mm.

The existence of Stoma-
topods in Paleozoic times is
still doubtful. Necroscilla
Woodward, from the English Goal Measures, is based on a fragment of the
abdomen and telson. Perimecturus Peach, from the Carboniferous of
Scotland, shows several features, such as the massiveness of the abdomen and
the movable rostral plate, that suggest an affinity with this Order. In the
Kimmeridgian of Solenhofen undoubted Stomatopods occur, some of which
are even referred to the Recent genus Squilla Fabr. (also known from

^ Literatiire: Münster, G. Graf zu, Beitrage zur Petrefaktenkunde. Parts iii. and v., 1840-
1842. — Mark, W. von der, and Schlüter, 0., Neiie Fische und Krebse aus der Kreide von Westplialen.
Palaeontogr., 1868, vol. xv.—Kunth, A., Über wenig bekannte Crustaceen von Solenhofen.
Zeitschr. Deutsch. Geol, Ges., 1870, vol. :kx\\.— Woodward, II., Contribntions to the knowledge of
fossil Crustacea. Quart. Journ. Geol. Soc, 1879, vol. xxxv.— Brooks, W. A", Report on the
Stomatopoda. Scient. Results Challenger Exped., Zool., 1886, vol. xyl—Miers, E. J. On the
Squillidae. Ann. Mag. Nat. Hist., 1880, ser. 5, vol. v.

Fig. 1495.

ScuMa pennata Münst. Upper Jura ; Bavaria. A, B, Dorsal
views, i/i and 3/j. c, Ventral aspect, 3/^. a, e, First and second
pairs of antennae (aft«r Kunth).

I

CLASS II ARACHNIDA 769

Cretaceous and Tertiary deposits). Sculda Münster {Eeckur Münst. ; Buria
Giebel) (Fig. 1495), also from the Solenhofen beds, differs considerably from
Recent forms. It is of infcerest to note that larvae of Stomatopods belonging
to what is known as the JErichthus type have been recognised in the Cretaceous
of the Lebanon.

[With the undernoted exceptions this revision of the Eucrustacea has been prepared for the
present treatise by Dr. W. T. Calman, of the British Museum of Natural History. The
systeniatic accouiit of tlie Branchiopoda and Ostracoda has been revised by Dr. R. S. Bassler,
of the United States National Museum, and that of the Phyllocarida by Dr. John M. Clarke,
State Geologist and Director of the New York State Museum at Albany. — Editoe.]

Olass 2. ARACHNIDA.

Arthropods in which the branchial folds function as gills or as lungs, or hecome
metamorphosed into air-tubes (tracheae). penetrating the hody. The hody is divided
into two regions, cephalothorax and abdomen, the line between the two passing behind
the sixth pair of appendages. Cephalothoracic segments usually coalesced, those of
the abdomen either free or fused. Frequently a post-anal spine is present. Antennae
lacking ; genital openings upon the first abdominal somite ; midgut long ; spermatozoa
motile ; development without nauplius or zoea

The affinities of the Recent Limulus and its extinct Xiphosurous allies
with the group represented by Scorpions, Spiders, etc., was pointed out by
Straus-Dürckheim as long ago as 1829, and additional reasons for removing
the Merostomes from association with Crustacea were brought forward at a
later period by various writers, among whom may be mentioned Henri and
Alphonse Milne- Edwards, Dohrn, Lankester, van Beneden, Kingsley, Laurie,
Clarke and Ruedemann. Kingsley, in discussing the relations between
Limulus and the Crustacea on the one band, and the Arachnida on the other,
has indicated the following points of agreement : (1) a branchial respiration ;
(2) absence of malpighian tubes ; (3) absence of salivary glands ; (4) absence
of embryonic envelopes ; and (5) presence of Compound eyes. He has also
shown 28 points in which Limulus and the Arachnids agree, and in which
both difFer from the other " Tracheates " (Myriapoda and Insecta).

The following points of likeness are considered as of special importance
for justifying the association of Merostomata with the Arachnida :

(1) The numerical homologies of segments and appendages; (2) the exact
homologies existing in the respiratory organs ; (3) the fact that the cephalo-
thoracic appendages are pediform, the basal joints serving as jaws ; (4) the
presence of true nephridia opening in the base of the third or fifth pair of
appendages or in both ; (5) genital openings in the seventh (or more probably
eighth) Segment of the body ; (6) extreme length of the midgut; (7) presence
of an internal structure, the entosternite ; (8) inclusion of the ventral nerve
cord and its nerves in the external artery and its branches ; (9) the close
similarities in the central nervous System.

The Arachnida form a more diverse class than the Insecta, and display
nearly as much differentiation among themselves in structure, size and habit
as do the Crustacea. The larger and more complex forms have a fixed and
constant number of segments, and in all Arachnida, as in Insecta and the
higher Crustacea, it is possible to analyse the body into twenty-one
VOL. I ' 3 D

770

ARTHROPODA

THYLUM VII

•fo«^ Some of these, however, may be suppressed during
:rorgi;;nTÄ är Absang t« *« adult «tage, 0. el.e be_g

fused in v.irious ways. r, •/!„ ^„a crrmmpd to^ether in hi2;her aggregates

The body Segments o^^Anjchmd ar g^rou^^^^^^^^^^^^^ g^^^^ ^ ^^

hanJ

L.ätera1 eyes
,■ 'Median e/es

esosoma

S fern am

qenital

•^ operculut

T

•I

■A/ers

Fig. 1496.

Duthus uccitanus Amoreux, a typical Old-World Scorpion, A, Dorsal, and B, ventral view.

1/3 (after Kraepelin).

metasoma (another name for the " postabdomen " or " tail " of earlier writers,
Fig. 1496). The first of these regions includes all of the segments in front
of the genital pore, usually six in number. The second, or mesosoma, begms
with the somite bearing the genital pore, and ends with the last somite which
bears free appendages, typically six segments in all. The third region, or
metasoma, consists usually of six segments, none of which bear appendages,
excepting that the terminal one often has attached to it a postanal " telson,
which may be considered as in the nature of an appendage. The latter takes
in Scorpions the form of the sting, in Xiphosures and Eurypterids that of the
spine. Among Merostomes, where the body is sometimes sharply divided
functionally into two regions only (" cephalothorax " and "abdomen" as

CLAss ir ARACHNIDA 771

they are then commonly called), the metasoma together with the mesosoma
make up the abdomeii. The abdominal segments, although usually distinct,
are sometiraes coalesced or fused.

Arachnids have the sexes distinct, and do not reproduce asexually or,
so far as known, parthenogenetically. As a rule there is little external
difFerence between male and female, except for a very frequent disparity
in size and an occasional modification of some of the appendages. In several
genera of Eurypterids two forms of opercular appendages of sexual significance
have been recognised, and, by analogy with Limidus, the more primitive of
these is assigned to the male, the more elaborate to the female. From this
it appears that, in Eurypterus at least, the adult males are smaller than the
females, as is true of Limulus also. Mites, Scorpions and Pedipalps are
viviparous, but all other members of the class lay eggs.

Primitive Arachnids appear to have been altogether marine, and to have
breathed by gill-books borne on appendages. During or after Silurian times,
when their descendants acquired a terrestrial habitat and changed from
water-breathing to air-breathing, the gill-books sank into the body and
became lung-books or were replaced by tracheae. Reference may be had to
the recently published works by Gaskell on The Origiii of the Vertebrates (1908),
and Patten on The Evolution of the Vertebrates and their Kin (1912), for an
extended discussion of the so-called Arachnid theory of the origin of
vertebrates.

The Arachnida are divided into two subclasses, Merostomata and Embolo-
branchiata. The chief distinguishing character of the former of these groups
is that the gills are patent and exposed, and (in living representatives)
malpighian tubules are absent. It is to be noted that both these features
are associated with aquatic life.

Subclass A. MEROSTOMATA Dana (emend. Woodward).i

(Syn. Gigantostraca Haeckel ; Delobranchiata Lankester.)

Six pairs of ambulatory limbs about the mouth, the foremost of which terminales
in chelicerae. The rest serve as organs of locomotion, and their coxal joints for
prehension and maslication. Behind the mouth is a single or paired metastoma.
Prosoma (^' cephalothorax") depressed, with usually a pair each of median ocelli and
laterally placed kidney-shaped Compound eyes. Respiration by means of lamellar
branchiae borne on the appendages of all, or all but one of the first six post-cephalic
Segments, which collectively form the mesosoma. In Limulus there are no salivary
glands, no malpighian tubules, and no embryonic membranes (^' amnion'') are found
in

Concerning the origin of the subclass, it is to be noted that the early
appearance and later atrophy of the abdominal appendages is clearly a
feature that points to a common ancestor for the Scorpion and Merostomes

^ The best bibliographies of Merostomata, including also historical reviews of the group, are to
be found in the following menioirs : — Woodward, IL, A Monograph of the British Fossil Crustacea
of the Order Merostomata. Palaeont. Soc, 1866-78, pp. 2l-Z().—Pachird, A. S., On the Car-
boniferous Xiphosurous Fauna of North America. Mem. Nat. Aead. Sei., 1885, vol. iii. pp. 153-6.
— Clarke, J. M., and Ruedemann, It,, The Eurypterida of New York. Mem. 14, N.Y. State
Museum, 1912, p. 438.

772

ARTHROPODA phylum vii

having such appendages. Also it is to be inferred that the cephalothorax
in the embryo of the Scorpion retains ancestral features, from the facts that
its length corresponds to about six abdominal segments and it equals the
latter in width.

A comparison of the larvae of all three, Eurypterids, Limulus and the
Scorpion, shovvs that the two last-named have lost the primitive form of the
abdomen by acceleration ; that of Limulus being much broadened, that of
the Scorpion abruptly contracted to the tail or postabdomen, while the
Eurypterids have best preserved the original gradual and uniform contraction.
The carapaces of Eurypterids and the Scorpion have most nearly retained
the original proportions and form of the common ancestor. Of the cephalo-
thoracic appendages the chelicerae are alike in all three groups and obviously
ancestral in their form ; the remaining legs have taken quite dilFerent courses
of adaptation, the Scorpions having developed the powerful chelate pedipalps,
the Eurypterids the swimming legs, while those of Limulus have remained
relatively undifferentiated.

These and other facts tend to support the inference that neither Limulus
nor the Scorpions are derivable from Eurypterids, but that all three, while
related, have early separated ; and that the Eurypterids are still nearest in
their general aspect to the early common ancestor. The appearance of
Eurypterids in the Cambrian with the essential characters of the group is
in accordance with their larval aspect, while the early Separation of Scorpions
from the primitive stock is evinced by the occurrence of typical Scorpions in
the Silurian, and by the fact that in the Carboniferous they show a greater
diversity of form than they do to-day. On the other band the similarity of
the ancient Palaeophonus nuntius to Recent forms is conclusive evidence that
the Scorpions have been very "persistent types " and had developed their
typical characters much earlier than the Silurian. There is no reason to
doubt that, as there are Eurypterids in the Cambrian, the Scorpions also
reach back to that era, and the diversion from the common ancestor ro.ust
have already been inaugurated in early Cambrian time.

^ As^ to what this common ancestor was we have no clue. Surely the
Trilobites, which are true primitive Crustacea, are not ancestrally or other-
wise closely related to Merostomes, and the latter even in the Cambrian are
far removed from any possible synthetic ancestors, as is shown by their very
definite number of segments and the arrangement of their appendages. We
must search, therefore, for still more primitive Arthropods than the Crustacea
as ancestors of Merostomes and Arachnids generally. In support of this view
Clarke and Ruedemann point to the absence of anything in the ontogeny of
the Eurypterids that would suggest a crustacean nauplius stage, the admitted
absence of all crustacean characters in the adult forms, and the equal absence
of all crustacean features in the ontogenies of Limulus and the Scorpion.

Order 1. XIPHOSURA Gronovius.i

Body inmature types, disti^dly trilohed longitudinally. Cephalothorax large,
sermarcular, the Compound eyes, when present, laterally situated, and ocelli near the

l^y\^T8B8-MZTe;^ ''-J'^VZ' ^''l''f^'' «^^ ^'^stoire naturelle et l'anatomie des Limnles.

CLASS II ARACHNIDA— XIPHOSURA 773

centre in front. First pair of appendages chelicerate. Metastoma with two small
accessori/ plates. Abdomen with seven to ten segments, which are dorsally free er
coalesced ; the six anterior ones provided with lamellar appendages on the under side.
Telson long, ensiform, movahle.

Family 1. Cyclidae Packard.

Cephalothorax small, orhicular, discoidal or convex, calcareous or chitinous,
hounded hy a distinct border. Cephalic appendages nearly as in embryonic Limulus.

Cyclus de Kon. (Fig. 1497). Known almost solely by the orbicular
cephalothorax with its imperfectly preserved appendages, which seem to be
simple swimming legs. Their enlarged joints cover the
ventral surface of the carapace everywhere except in J^^^^^^W^

the centre, which is occupied by a V-shaped plate,
towards the pointed extremity of which all the basal
joints of the limbs converge. Goal Measures ; Great
Britain, Illinois and Missouri.

Family 2. Belinuridae Packard

Fig. \m

Cyclus americanus Pack.
Goal Measures ; Mazon Creek,

Body limuloid in general aspect. Cephalothorax
rounded, with long, slender genal spines ; its a'ppendages as
in Idrval Limulus. Abdomen with the segments in part piinois. cephalothorax show-

,^ -^ ingtracesoflegsandahmentary

or almost wholly Consolidated ; telson of variable length. canai. Vi.

Belinurus König (Fig. 1498). Gephalothorax hippocrepiform, its central
portion surrounded by a broad, flat marginal area, which at the genal angles
is produced into a long, slender spine. Abdomen with eight segments,
besides the much-elongated, slender telson ; seventh and eighth segments are
Consolidated. Upper Old Red Sandstone and Goal Measures of Great Britain
and northern France (B. bellulus König; B. reginae Baily). Also in Goal
Measures of Illinois {B. lacoei Packard).

—Baily, W. II., Explanation of Sheet 137 of the Maps of the Geol. Surv. Scotland, 1859.—
Eemarks ou Belinurus. Ann. Mag. Nat. Hist, 1863, ser. 3, vol. xl— Giebel, O. G., Limulus
Decheni. Zeitschr. gesammt. Naturw., 1863, vol. xxi, — Meek, F. B., and Worthen, A. H., Rept.
Geol. Surv. 111., 1868, vol. iii. — Woodward, H., Notes on Neolinmlus, Cyclus, Merostomata, etc.
Geol. Mag., 1869-94, dec. 1, vol. v. ; dec. 3, vols. vii,, ix. ; dec. 4, vol. i. — Dohrn, A., Embryologie
und Morphologie des Limulus. Jeuaische Zeitschr., 1871, vol. vi. — Packard, A. S., Development
of Limulus. Mem. Boston Soc. Nat. Hist., 1872, vol. i. — Idem, Anatomy, Histology and
Embryology of Limulus. Anniv. Mem. Boston Soc. Nat. Hist., 1880. — Ideyn, Carboniferous
Xiphosurous Fauna of North America. Mem. Nat. Acad. Sei., 1885, vol. iii. — Van Beneden,
M. E., Systematic Position of King Crabs and Trilobites. Ann. Mag. Nat. Hist., 1872, ser. 4,
vol. ix. — Milne-Edioards, A., Recherches sur Tanatomie des Limules. Ann. Sei. Nat., 1873,
ser. 5, vol. xvii. — Lankester, E. R., Limulus an Arachnid. Quart. Journ. Microsc. Sei., 1881,
vol. xxi. — Peach, B. N., Further Researches among Crustacea and Arachnida. Trans. Roy. Soc.
Edinb., 1882, vol. xxx. — Williams, II. S., New Limuloid Crustacean from the Devonian. Amer.
Journ. Sei., 1885, ser. 3, vol. xxx.— Hall, J., and Clarke, J. M., Palaeontology of N.Y., 1888,
vol. vii. — Kishenouye, K., Development of Limulus. Journ. Coli. Sei. Tokyo, 1891, vol. v. —
Kinrjdey, J. >S., Embryology of Limulus. Journ. Morphol., 1892-93, vols. vii., viii. — Fritsch,
A., Fauna der Gaskohle. Prague, 1901, vol. \\.— Clarke, J. M., Pseudoniscus in the Eurypterus
Beds of New York. Rept. N.Y. State Palaeont. for 1900. (54th Ann. Rept. N.Y. State Mus.),
1902. — Rogers, A, F., Some new American Species of Cyclus from the Cqal Measures. Kansas
Univ. Sei. Bull., 1902, vol. i., No. 10. — Stromer von Reichenbach, E., Über Molukkenkrebse.
Zeitschr. Deutsch. Geol. Ges. Monatsber., 1907, vol. \ix. — Gaskell, W. II., Origin of the
Vertebrates, London, 1908. — Patten, W., Evolution of the Vertebrates and their Kin, 1912.

774

ARTHROPODA

PHYLÜM VII

PrestwicUa Woodw. {Euproöps Meek ; Jnthracopeltis Boulay) (Fig. 1499).
Differs from Belinurus in having seven coalesced abdominal segments, besides

a shortand obtuse caudal
spine. Outline of ab-
domen subsemicircular,
central axis of body
Segments narrow. Goal
Measures; England,
northern France, Russia
and Illinois. Type, F.
anthrax (Prestw.).

Protolimulus Pack.
Cephalothorax relatively
large, subsemicircular,
with small appendages ;
its genal angles less pro-
duced than in the two
preceding genera. Abdomen with six segments besides a large, thick caudal
spine. Upper Devonian (Chemung Group); Pennsylvania. Type, Prot,
eriensis (Williams).

Prolimulus Fritsch. Cephalothorax ellipsoidal, broader than long, without
genal angles, and with relatfively long appendages. Abdomen rounded,
shorter than the cephalothorax, with lamellar appendages. Telson slender
equalling one-half the total body length. Permian ; Bohemia. Type, P.
woodwardi Fritsch.

Fio. 1408.

Belinurus reqinae Baily.
Goal Measures ; Queen's
Couiity, Ireland. Vi (aft«r
Woof] ward).

Fia, 1499.

Goal Meas-

Prestwichia danae (Meek).
nres; MazoiiCreek,Grundy County, Illinois.
2/3 (after Packard).

Family 3. Limulidae Zittel (King or Horseslioe Crabs).
(Syn. Xiphosuridae Pocock.)

Body lov.ger than hroad ; cephalothorax arched dorsally, the central portion
separated from the sides hy longitudinal grooves ; marginal area large and flat.
Abdomen composed of six Consolidated segments forming a simple sub-triangular
shield, and a long slender telson. Six pairs of abdominal limbs, five of them having
over a hundred pairs of gill-leaves.

imwZws Müller, restricted by Fabricius (Fig. 1500). Living species belong-
ing to this, the solitary genus of the family, occur on the eastern shores of North
and Central America and Asia. According to Pocock's Classification {Jnn.
Mag. Nat. Hist., 1902, ser. 7, vol. ix.), the four Asiatic species are referable
to two genera distinct from Limulus s.s. In all forms the four cephalothoracic
feet are chelate, the sixth pair is furnished with a whorl of plates used in
pushing the animal through the mud. Gills are borne upon the five posterior
pairs of abdominal appendages, the anterior pair being without gills, but
havmg the genital opening upon the posterior face.

ohJJt^ males are smaller than the females, aud are further distinguished by the hooked, not
Ron n-r!' ^^^"^'"^^^«^ of the second, or second and third appendages, a cliaracter which they
«n?np l.^ ^ *• "^f "^jty- The young embryo of Limulus is without an elongated caudal
eSo^ C",,,lTT'/r'^^ ^y ?^.^'\^ ^^ '^^ abdominal appendages. With its mSrked lateral
Svp^" f^ abdonien and body divided into median and lateral regions by longitudinal
grooves, it presents considerable reseinblance to a Trilobite, and the stage has in ttct been

ARACHNIDA— XIPHOSURA

775

called the Trilobite stage (Fig. 1500, B). After the first moult the caudal spine begins to
elongate, and at this stage, while the abdomen retains its segmented larval character, a true
affinity with tlie Paleozoic Prestwichia and Beiinurus is clearly revealed. The prevailing
modern view is that in Lirmihis we have a meniber of the Arachnida which retains its water-
breathing liabit, and, in the features of the abdominal appendages, some traces of the
characteristic structure of the primitive crustacean stock from which the Arachnida originally
sprang.

The genus first makes its appearance in the Trias, one small species being known from
tlie Buntersandstein of the Vosges, and another, L. vicensis Bleicher, from the Keuper of

B, Embryo ot Limulus,
in the so-ctiUed "Trilo-
bite stage." Lateral
eyes faintly shown.
(After Dohrn.)

C, Limulus priscus
Münst. Muschelkalk ;
Laineck, near Bay-
reuth, i/i-

Fui. 1500.

A, Liimilus walchi Desm. Lithographie Stone ; Solenhofen, Bavaria. Dorsal and ventral aspeets, the
latter showing several pairs of imperfectly preserved ambulatory limbs. On the.carapace, covering the prosoma,
are seen impressions of the lateral eyes.

Lorraine. L. walchi in abundant in the Lithographie Stone of Bavaria ; L. natkorsH and
L. woodivardi are Jurassic species from Sweden and England respectively ; L. syriacus
occurs in the Cretaceous of the Lebanon ; and L. decheni occurs in the Oligocene brown coal
of Teuchern, near Merseburg.^

Order 2. SYNXIPHOSURA Packard.

Body elongated ; cephalothorax semicircular with more or less distindly defined
median axis, and no facial sntures. Compound eyes generally present, ocelli not

^ Böhm, J., Über Limidus decheni Zincken. Jahrb. Preuss. Landesanst. Bergakad., 1905,
xxvi. Oiie of these specimens described by Böhm represents doubtless the largest known

vol
Limidus

Fig. 1501.

7.g ARTHROPODA phylum vii

ohserved except in Neolimulus. Abdomen trüohed, its segments free, the pleura flat
and extended, and usualUj terminating in lateral projeäions or spmes.

With the exception of the Caml.rian Aglaspis (Fig. 1501), all the genera belonging to this
Order are of Silurian age, and are too imperfectly known as yet to permit a satisfactory
grouping into farailies, although several such have been proposed by Packard. Zittel united
theni, together witli certain genera of Xiphosura, in the family Henuaspidae, which term is
retained, but employed in a restricted sense.

Suborder A. AGLASPINA Walcott.

Body elongate, transversely trilobed, more or less sharply divided into two regions
only. Cephalothorax with or without sessile eyes ; on the ventral side it has an
epistoma and five pairs of movahle appendages. Abdominal
Segments all free, varying from seven (Aglaspis) to twelve
{Emeraldella) in addition to the caudal spine.

Family 1. Aglaspidae Clarke.

Cephalothorax moderately large, trilobed ; abdominal Seg-
ments with distinct axis and pleurae ; telson long and spiniform.

Aglaspis Hall (Fig. 1501). Cephalothorax relatively

large, its trilobed central portion short and conate, in front

Agias^pu eatoni whitf. of which are two approximate Compound eyes ; bounded

Ä^ns^r^^/r ' ^'"^'' ^" ^^^ ^^^^^ ^y ^ distinct border. Abdominal segments

described as seven in number, flat and blade-like, not

grooved on the pleura ; telson a long and somewhat obtuse spine. Cambrian;

Wisconsin.

Under this family also are included three genera from the Burgess shale
member of the Stephen formation (Middle Cambrian) of British Columbia,
described by Walcott under the names of Molaria, Habelia and Emeraldella.
They are remarkable for displaying well-preserved abdominal appendages.

Suborder B. BUNODOMORPHA, nomen novum.

This group contains only the family Hemiaspidae, as at present constituted.
It is a somewhat heterogeneous assemblage, but recognised as separated from
the Aglaspidae by more than family differences.

Family 1. Hemiaspidae Zittel.

This family, in its restricted sense, may be provisionally maintained
pending further investigation of the rare and in some respects obscure forms
embraced by it. The original definition of this family is no longer applicable,
Its limits having become narrowed by the removal of various genera to
other groups.

Neolimulus Woodw. Cephalothorax short and broad, crescentic, elevated
mesially, and bearing one or two pairs of ocelli. Compound eyes lateral and
connected with the genal angles by a suture. Abdomen very broad anteriorly,
not distinctly divided into two regions, all of its segments free, trilobed and

ARACHNIDA— SYNXIPHOSÜRA

.p.e.

at least nine in number; the telson not observed in any specimen thus far

discovered. Axial portion of abdomen diminishing rapidly from before

backwards. This geniis has been understood

as connecting the Xiphosura with the Synxi-

phosura. Silurian ; Scotland. Ty^Q, N.falcatus

Woodw.

Bunodes Eichw. (Exapmurus Nieszk.) (Fig.
1502). Cephalothorax semicirciilar, convex,
with radial furrows from the median portion.
Facial sutures obscure, converging from the
posterior to the anterior margin. According to
Patten's interpretation, a median ("parietal")
and a pair of lateral eyes are present, but no
genal spines. Abdomen divided into an an-
terior portion (mesosoma or "thorax") consist-
ing of six trilobite-like segments having a broad
median axis and lamellar pleura with diagonal
pleural lines ; and a posterior portion (meta-
soma or " postabdomen ") of four narrow seg-
ments, besides a long and acuminate telson,
External surface of carapace and somites pus-
tulose. Silurian ; Oesel.

Hejniaspis Woodw. (Limuloides Salter) (Fig.
1503). General form similar to that of Bunodes.

Cephalothorax one-half

as long as broad, with

several genal spines ;

central portion well de-

fined. Postcephalic Seg-
ments nine in number,

besides the acuminate

telson, more or less dis-

tinctly divided into two

Fig. 1502.

Fig. 1503.
Hemiaspis limuloides Woodw.

Bunodes lunula, var. schrenki, Niesz.
Silurian ; Rootziküll, Oesel. Drawing
made from a plaster model, as restored by
re^ions (mesosoma and hatten, 2/1. Pros, Prosoma ; Ms, Meso-
" \ 1 • 1 soma, füllowing wh ich are the four narrow

metaSOma), SUbtriangUlar somites and telson constltuting the meta-
in mifli'nP nnrl witli n ^°"^* ' ^^' I^'i^eral eye; pe, Parietal eye.
in outline, ana Wltn a (Supposed antennae omitted.)

broad median axis which

tapers gradually from before backwards. Pleura flat
and Short, the lateral margins of the sixth divided into
two lobes, as if Compound. Segments seven to nine
are narröwer and longer than the preceding, their

knd"^"Äo:?te^^^^^ combined length equalling that of the tail-spine.

Silurian ; Scotland.

Bunodella Matthew. Prosoma small, postcephalic segments seven in number,
tapering posteriorly. Axial portion of the body elevated ; telson not observed.
Silurian ; New Brunswick.

Pseiidoniscus Nieszk. (Fig. 1504). Prosoma relatively large, convex,
hippocrepiform, probably eyeless and without facial sutures ; genal angles
extended into short spines ; surface obscurely marked with radial furrows.
Postcephalic portion ("abdomen") strongly trilobed and trilobitiform, with

778

ARTHROPODA

PHYLUM VII

aradiiallv tapering median axis. Segments nine in number, besides a short
Sd tekon, all with smooth surfaces. The first five Segments w. h
i^" obliquely grooved pleura ; sixth and seventh

partly conjoined on the pleura, and corre-
sponding axial parts of the segments narrow ;
eighth and ninth segments narrow, lanceolate,
and with increasing retral curvature. Average
total length of animal 2-5 cm. Silurian ;
Oesel and New York State (Salina Group).

Order 3. BURYPTBRIDA Burmeister. ^

Body elongated, luith a thin chitinous epi-
dermal campace ornamented hy fine scale-like
■markings. Prosoma with two large, sometimes
facetted lateral eyes and a pair of median ocelli ;
on the ventral side with six pairs of appendages,
the foremost of which is preoral and chelicerate.
Mouth hordered posteriorly hy a metastoma.
"Abdomen" consisting of thirteen free segments,
of which the anterior six helong to the mesosoma
q.nd hear ventrally five pairs of hroad, foliaceous
appendages, corresponding or comparahle to the
operculum and hranchial appendages of Limulus.
The metasoma consists of six free, annular seg-
ments without appendages, together with a long
or spatulate telson.

This Order, which is restricted wholly to the Paleozoic, embraces the largest
Arthropods known, some of them {Pterygotus, Stylonurus) having attained a length

' Literature : Dekay, J. £., On a Fossil Crustaceous Animal. Ann. N.Y. Lyc. Nat. Hist.,
1825, vol. l—M'Coy, F., Some British Fossil Crustacea. Ann. Mag. Nat. Hist., 1849, ser. 2, vol.
iv. — Roemer, F., Ueber ein Exemplar von Eurypterus. Palaeontogr. , 1851, vol. i. — Huxley, T. IL,
On Himantopterus. Quar. Journ. Geol. Soc, 1856, vol. xii. — Idem, and Scdter, J. W., On Ptery-
gotus. Mem. Geol. Surv. United Kingd., 1859, vol. I—Page, D., Advanced ^ext-Book of Geology,
1856 and 1S59. —NieskowsM, J., De Euryptero remipede. Dorpat, 1858. — Hall, J., Palaeon-
tology of New York, 1859, vol. iii. — Salier, J. W., Some Fossil Crustacea, etc. Quar. Journ. Geol.
Soc, 1862-63, vols. xviii., xix. — Woodward, H., Numerous papers in Geol. Mag., ser. 1, dec. 1,
vols. i., ix., and Quar. Journ. Geol. Soc, vols. xxi., xxiii., xxiv., xxvii., xxviii., etc., 1864-72.
— Idem, Monograph of British Fossil Crustacea, Order Merostoniata. Palaeontogr. Soc, 1866-78.
—Orote, A. R., and Pitt, W. H., New Crustaceans from Water- Lime Group (Eusarcus, Ptery-
gotus, etc.). Bull. Buffalo Soc Nat. Sei., 1875, vol. in.— Pohlman, J., Fossils of the Water-Lime
Group. Ibid., 1881-84, vols. iv., v. — Peach, B. N., Further Researches among Crustacea and
Arachnida. Trans. Roy. Soc. "Edinb., 1882, vol. xxx.— Schmidt, F., Miscellanea Silurica. Mem.
Acad. Imp. Sei. St-Petersb., 1883, ser. 7, vol. xxxi.—IIaü, J., Note on Eurypteridae. 2nd Geol.
Survey Penn., Rept. PPP., lS8i.— /dem, and Clarke, J. M., Palaeontology of New York State,
1888, vol. \\\.—Whiteaves, J. F., Palaeozoic Fossils of Canada, 1884, vol. iii. — Fraipont, J.,
Eurypterides nouveaux du Devonien. Ann. Soc. Belg. Geol., 1889, vol. xvn.—Claypole, E. W.,
On Eurysoma, Carcinosoma, etc. Amel-. Geol., 1890-94, vols. vi., xiii. — Laurie, M., Eurypterid
Remains from Pentland Hills. Trans. Roy. Soc. Edinb., 1892, vol. xxxvii.— Idem, On Eurypterida.
Nat. Sei., 1893, vol. m.—Idem, Anatomy and Relations of the Eurypteridae. Ibid., 1893, vol.
xxxvii., and Nat. Sei., 1893, vol. m.—Holm, Q., Über Eurypterus Fischeri. Bull. Acad. Imp.
Sei. St-Petersb., 1896, ser. 5, vol. iv. ; also Memoires, 1898, ser. 8, vol. vüi., and Geol. För. i
Stockholm För., 1899, vol. xxx.—Semper, M., Gigantostraken des böhmischen Paläozoicum. Beitr.
Pal. u. Geol. Osterr.-Ung., 1898, vol. n.—Beecher, C. F., Restoration of Stylonurus. Amer.
Journ. Sei,, 1900, vol. x.—Idem, Eurypterid Remains from Missouri. Ibid., 1900, vol. xii., and
Geol. Mag. 1900, dec. 4, vol. yin.—Sarle, C. /., Eurypterid Fauna from the Salina Rept. N.Y.

Fio. 1504.

Pseudoniscus roosevelti Clarke. Complete
indivldual. Silurian (Salina Group) ; Monroe
County, New York, '^/i (after Clarke).

CLASS II

ARACHNIDA— EUEYPTERIDA

779

of nearly tliree metres. The presence of gills lipon the brancliial appendages shows

that tlie Eurypterids were aqiiatic, and the structure of their appendages indicates

that they were for the most pait luud-crawlers, though sonie were good swinimers.

They are found associated

with cephalopods and tri-

lobites in the Canibrian

and Ordovician of North

America ; with cejjhalo-

pods and marine arthropods

(Phyllocarids and Ostra-

cods) in the Silurian ; with

Ostra(3ophores and Arthro-

dires in the Devonian ; and

with land plants,scorpions,

insects, fishes, and fresh-

water amphibians in the

productive Goal Measures.

It is apparent, therefore,

that from being originally

marine forms, they became

gradually adapted to

brackish, and possibly even

fresh-water conditions.

The Eurypterids and
Xiphosures present a num-
ber of points of common
resemblance. Both groups
have a prosoma composed
of at least six fused Seg-
ments, and bearing two
pairs of eyes, one pair
simple, the other Com-
pound, on the dorsal sur-
face of the carapace. The
number and position of
the appendages of the
prosoma in Eurypterids
are the same as in Limulus,
and the chelicerae are
similarly constructed in

both cases. The basal joints of all five pairs of legs in Eurypterids are toothed and
function in mastication ; similarly in Limulus all are spiny except the coxae of the
last pair of legs. In both groups a similar process called the epicoxite is borne upon
the coxae. On the raesosoma the genital operculum and plate-like appendages with
brancliial lamellae are similar in both groups. A striking difFerence between them,
however, is seen in the segments of the mesosoma and metasoma, the somites being all
free in Eurypterids, but in Limulus fused together. The resemblance between Euryp-
terids and Scorpions is none the less striking, both groups showing the same number

Earypterus
County, N.Y.
Ruedemann).

Fig. 1505.

'emipes Dekay. Bertie Waterlime (Silurian) ; Herkimer
Restoration of dorsal aspect. 1/2 (after Clarke and

State Palaeont., 1903. — Schmidt, F., Über Stylouurus von Ösel. Bull. Acad. Imp. Sei. St-Petersb.,
1904, ser. 5, vol. xx. — Seemann, F., Zur Gigantostrakenfauna Böhmens. Beitr. Pal. u. Geol.
Österr.-Ung., 1906, vol. x'w. — I'iurost, 1\, Crustaees du nord de la France. Ann. See. Geol.
Nord, 1911, vol. xl. — Clarhr, J. i/., and Ruedemann, R., Eurypterida of New York. Mem.
N.Y. State Mus. 110. xiv., 1912.

PHYLÜM VII

•80

ARTHKOPODA
three regions of tlie body, and the appendages of the prosoma

of Segments in the

iff identical in nui ^ .,

Tl e gcneral fonn of tl.e boly in Euryptends

„f a Scorpiou, Imt ia relativoly broader and shorter.

beingidentical in_numteandl.«<iUon.^^^^^^^^.^^^ ^^.^ ^^^^^ .^ somewliat like tliat

■t#

-^&^^'

Tlie prosoma or cephalotliorax
consists of six fiised Seg-
ments covered by a quadrate
carapace witli its front
angles rounded. This bears
on its dorsal surface two
pairs of eyes— large kidney-
^^haped lateral eyes, and
median ocelli. Tlie Com-
pound lateral eyes are
smootb in theEnrypteridae,
facetted in thePterygotidae.
As sliovvn by Clarke and
Rnedemann, tbese facetted
eyes are identical in struc-
ture with tbose of Limulus.
On tlie ventral surface
of tlie prosoma (Fig. 1506)
are seen six pairs of appen-
dages, of wliicb tbe first pair
(the chelicerae) are preoral
in Position, and the remain-
ing five pairs are found at
the sides of the elongate
mouth, and are developed
as legs. These legs consist
typically of a basal Joint
{coxa), the inner margin
of which (gnathohase) is
provided with teeth and
able to function in masti-
cation, much as in Limulus
or Ä23US, whilst the distal
part of each appendage
served as an organ of loco-
motion. The ambulatory
part of the appendages is
usually six-jointed, and is
attached to a small, oval
"epicoxite" at its anterior angle exactly in' the same fashion as in Limulus. The
fifth pair of legs is spineless and slender, probably serving as balancing organs.
The sixth pair is characterised in all members of the order by its greater size and
usually somewhat flattened form, as well as by its termination in an oval plate or
claw. This last pair is commonly termed the palette or paddle, and seems to have
had a swimming function, although it is probable that the animal used it also
for anchoring or burying itself in the mud.

Behind the prosoma are twelve free Segments, plus the tail-spine, of which the
fii-st six form the mesosoma, and the remainder the metasoma. On the ventral
surface the Segments of the mesosoma bear pairs of plate-like appendages, each of
which slightly overrides the next succeeding one. These appendages bear on their
inner (posterior) surfaces the lamellar branchiae, which are oval in outline (Fig.

Fig. 1506.

Eurypterus fischeri Eicliw. Silurian ; Island of Oesel.
individual, 1/2 (from Holm).

Female

CLASS II

AEACHNIDA— EURYPTERIDA

781

1509), and in a general way are comparable to the leaf-like external gills of Limulus.
Tlie first and second Segments of the mesosoma are covered on the ventral surface
by tlie genital operculum, wliich consists of a pair of plates meeting in the middle
line and liaving a median lobe attached to them. Tlie latter, frora analogy with
Limulus, is undoubtedly genital in function, and varies in form in the same species,
correlating with sex.

Family 1. Eurypteridae Burmeister.

Body elongate, narrow in form to hroadly expanded in the mesosomatic re
Prosoma suhquadrate to suhtriangidar in outline, with rounded front angles ; telson
spiniform. Compound ey es smooth,
not facetted, gener ally near the
middle of the cephalic shield ; no
epistoma; chelicerae not extending
heyond the frontal margin of the
carapace. Sixth paif of legs
adapted for either smmming or
crawling. Femade genital append-
age composed of several lohes.

Certain genera which are here
included in this family {Eusarcus,
Stylonurus, etc.) present rather
Wide departures from the type, and
in the recent Classification proposed
by Lankester (Encyclop. Brit.,
12th ed., article on Arachnida)
theyare placedin sejmrate families.
Concerning geneticrelations, much
new light has been gained through
study of the stages of development
of the principal genera, and by
comparison of them with the
primitive and much generalised
Strabops from the Cambrian.
This genus is one of the earliest
known Eurypterids, and is re-
garded by Clarke and Ruedemann

as an actual progenitor of most ^''^^'^(^^opsthacheri Beecher. Fotosi limestone (Upper Cambrian) ;
CM • X- * -,. ^^- Fran(;ois County, Mo. Restoration of dorsal aspect. 2/„

bllurian iorms. Accordmg to (after Clarke and Ruedemann).

the authors just named the Euryp-
terids studied by them pass through a so-called Strahops-stage during the course of
their nepionic development. It has also been shown by them that the ontogeny of
Eurypterids fully corresponds to that of Limulus in lacking any indication of a
nauplius or zoea stage.

Strahops Beecher (Fig. 1507). Prosoma small, comparatively wider than
in Eurypterus, but the eyes further back, small, and very far apart ; body
somites not distinctly differentiated into two regions (mesosoma and
metasoma), twelve in number besides the short and blunt tail-spine. In view
of its generalised characters this genus is eminently fitted to serve as a

Fig. 1507.

782

ARTHROPODA

PHYLUM VII

prototype from which later Eurypterids are descended. Cambrian (Potosi
limestone) ; Missouri.

Eurypterus Dekay (Lepidoderma Reuss ; (?) Campylocephalus Eichw.) (Figs.
1505, 1506, 1508). Body elongate, narrow, attaining sometimes a length of
1 m. Prosoma contained five or six times in total length of the body, depressed
convex, subquadrate, with rounded anterior angles. Anterior margin nearly
straight, posterior slightly concave. Eyes reniform, somewhat in front of the
middle ; between them and close to the axial line are two ocelli. The entire
prosoma bordered by a narrow marginal furrow, and the margin broadly
enfolded on the ventral side. In the middle of the lower side is the cleft-
shaped mouth, which is bordered laterally by the basal segments of the fifth
pair of legs, and posteriorly by the large oval metastoma. Ordovician
(Normanskill shale) to Permian ; Europe and North America.

The first pair of appendages was regarded by Woodward and Schmidt as filiform and
tactile. Laurie, Holm, Clarke and Ruedemann, and others, however, have shown that tliey
are chelicerate, and thus in accord with homologous structures in other niembers of the
faniily. The three succeeding appendages are six- or eight-jointed and covered with fine
spines. The fifth pair is eight-jointed, and longer than those in front of it. The posterior
pair is a powerful swimming-organ ; its great subquadrate basal joints enclose the metastoma,
and together with this, cover nearly one-half of the ventral side of the prosoma.

All of the body segments are free. The first six form the mesosoma, and together
collectively occupy about one-fourth of the body-length. They are short and broad, and
nearly uniform in shape ; but the second segment has lost its hard skeleton on the ventral
surface, and the tirst Covers the greater part of the genital operculum. This first segment

joins the posterior margin of the prosoma
and consists of two lateral portions and
a median process. All six segments of
the mesosoma are moderately overlap-
ping on the ventral side, and each is
divided by a median suture or cleft into
two parts. After these follow the six
ring-like segments of the metasoma,
which diminish gradually in Avidth pos-
teriorly, and the body is terminated by
a long, slender telson. The latter is
properly to be regarded as an appendage
of the twelfth segment, as indicated by
the Position of the anus in relation to it.
Larval stages have the telson short,
thickand four-sided, with dorsal, ventral
and two lateral edges, corresponding in
form to that of the primitive Strahops.

About twenty-five species of Eury^-)-
terus are known, the largest being about
1 m. long. They are found for the most
part in argillaceous or sandy deposits
in transition strata between the Silurian
and Devonian of England, Gotland,
Oesel, Podolia, and in the Water-lime
Group (Silurian) of New York. They
are rare in the Devonian, but occur
again more frequently in the Goal
Measures of Scotland, Silesia, Bohemia,
Saarbrücken, and Pennsylvania. The
last survivor is from the Permian of
«««iation with land plants ( /Fafc/a«, Äy««^fe™) "Typ"; i "«ISe. tZy " "™'' '"

leg Sbnedln*;!"'"' "' ,?^-'i<'--"- Terminal claw (with Joint) of sixth

Fio. 1508.
^yer«.rmipe. Dekay. Bertie Waterlinie (Silurian);

TnHinn., T i^ r;-!'--"^^ «p^ie ; nitn pair undiffen

inaiand. iype, Luryptems kokomoensis Miller and Gurley.

CLxVSS II

ARACHNIDA— EUKYPTERIDA

783

Tyloptcriis Clurke and Ruedemann. Thick calcareo-chitinous integument,
witli median divided knobs on tergites. Silurian ; Canada. Type, Eurypterus
hoylei Whiteaves.

Echinognathns Walcott. Imperfectly known. Cephalothoracic appendages
with numerous curved spines, indicating an animal of large size. Ordovician ;
New York.

Megalograptus Miller. Richmond beds (Lowermost Silurian) ; Ohio.
Known only by fragmentary remains.

Dolichoptenis Hall. Sixth prosomatic appendage has the terminal claw
developed into an elliptical oar-plate. Waterlime (Upper-
most Silurian) ; New York. Silurian ; Oesel.

Eusarcus Grote and Pitt (Eurysoma and Carcinosoma
Claypole). Eurypterids with the six mesosomatic Seg-
ments greatly expanded, the next following of the
metasoma being abruptly contracted. Prosoma subtri-
angular, Compound eyes at apex in front ; metastoma
subtriangular. Second pair of legs the longest. Terminal
Joint of the sixth prosomatic appendage not expanded.
General aspect of body scorpion-like. Ordovician and
Silurian ; New York, Indiana, and Pentland Hills, Scot-
land.

Anthraconedes Meek and Worthen. Like Eurypterus^
but with spines on the falcate posterior angles of the
abdominal segments. Goal Measures ; Illinois and
Pennsylvania.

Adelophthalmus Jordan and von Meyer. Comprises
eyeless Eurypterids. Goal Measures ; Saarbrücken.

? Eurypterella Matthew. Probably not a Eurypterid.
Devonian ; New Brunswick.

? Beitina Walcott. Probably not a Eurypterid.
Algonkian ; Montana.

Slimonia Page (Himantopterus Salter) (Fig. 1509).
Body attaining a length of 60 cm., and width of 15 cm.
Prosoma subquadrate, with anterior marginal eyes and
median ocelli. Preoral appendages in the form of small shlrr"scoSid"'Rts"toia-
stout pincers, much like chelicerae in Limulus. Of the tion ' of ventral aspect,
five pairs of postoral appendages, the first is modified to Le^msoma^i?— vl^ViS-

tal operculum VII.— VIII.,

Segments of the mesosonia

The first two sternites vii- - xii metasoma

. . XIII.— XVIII., and telson

are represented by the genital plate and its posterior xix. Dotted areas of the

j. . • i.t, J.I, ü j' ^' 1 j. 1 • mesosoma are branchial

divisions ; the other nve are discontinuous plates bearing lameiiae .showhig tiirough
branchial lameiiae on their inner surface. The five f)^%£'Srier'"'^^^^°''
posterior segments are long, narrow, and cylindrical.
Telson like that of Pterygotus, but produced into a longer spine. Only one
species known. Old Red Sandstone ; Scotland.

Stylonurus Pa,ge (Fig. 1510). Body similar in general proportions to
Pterygotus, and often exceeding 1 m. in length. Prosoma quadrate or sub-
pentagonal, its margins bent under. Eyes large, approximate, sometimes
supported by strong orbital ridges ; ocelli on the slope of a median ridge.
Preoral appendages chelicerate. The five pairs of postoral appendages

Fig. 1509.
Slimonia acuminata

form tactile organs. The first seven postcephalic seg- äinnent8"of"the^
ments much wider than the rest.

784

ARTHKOPODA

PHYLUM VII

increase in len-th from the first backward, the last pair enormously elongated,

heincr nine-jointed, extending almost to the end of the telson, and termmating

^ •' in a Sharp claw. The first two

pairs of legs frequently bear
paired leaf-life spines. Telson
long and slender. Silurian and
Devonian ; Scotland, Russia, New
York, and Pennsylvania.

Subgenus : Ctenopterus Clarke
and Ruedemann. First three
pairs of legs with numerous paired
spines to each segment.

Tarsopterus Clarke and Ruede-
mann. Silurian ; New York.

Drepanopterus Laurie. Body
as in Stylonurus, but the pos-
terior legs much. less elongated.
Silurian ; Scotland and Indiana.

Family 2. Pterygotidae
Lankester.

Body elongate, narrow. Pro-
soma semielliptical to subquadrate in
outline; telson spiniform in Hugh-
spatulate and hilohed
te in all other genera. Com-
eyes facetted, marginal ;
epistoma present ; chelicerae some-
times greatly extended. Last pair
of legs always adapted to swimming.
Female genital appendage simple.

P ier ygotus Agassiz (Figs. 1511-1512). Eurypterids sometimes of gigantic
size, attaining a length of over 2 m. Prosoma semi-ovate, with anterior
marginal facetted eyes and median ocelli. The metastoma is a heart-shaped
plate attached along the middle line to the ventral wall of the prosoma,
between the bases of the last pair of legs, and extending outwards and
forwards so as to enclose the jaws in a kind of Chamber. Epistoma a thin
plate, occupying the same position as the hypostoma in trilobites, and having
the preoral appendages attached close to its posterior border. The latter are
large pincers, probably prehensile in function; by Schmidt and Woodward
they are represented as many-jointed, but it is now known that they consist
of but three long joints. Behind the mouth are four pairs of slender Walking
legs, followed by the large " swimming feet," which are similar to those in
Eurypterus, except that they are less broadly expanded at the tips. Telson
an oval plate, terminating in a slight projection. The species first referred
to this genus (P. proUematicus Ag.) is imperfectly understood, and P. anglims
Ag., which is well known, is generally accepted as the typical form of the
genus. Ordovician ; New York. Silurian ; Wales, Scotland, Sweden, Oesel,
Russia, New York, and Australia. Old Red Sandstone ; Scotland.

Fig. 1510.

Stylonurus excelsior Hall. Chemung-Catskill Group (Upper
Devonian) ; Pennsylvania. Restoration of dorsal aspect.
1/20 (after Clarke and Ruedeniann).

ARACHNIDA— EURYPTERIDA

785

Erettoptems Huxley and Salter. Like Pterygotus, but with a bilobed
telson. Siluriari ; Lanarkshire.

Hughmilleria Sarle. Small animals with carapace as in Pterygotus, chelate

Fig. 1511.

Pterygotus buffaloensis (Pohlman). Bertie Waterlime (Silurian) ; BufFalo, New York,
A, dorsal, and B, ventral aspect. 1/30 (after Clarke and Ruedemann).

Restoration of

appendages on short legs, and telson as in Eurypterus. Epistoma lyre-shaped,
flanked by lateral shields. Ordovician and Silurian ; New York.

Glyptoscorpius Peach. Body
attaining a length of 30 cm.
Surface covered with highly
developed scale-markings. The
animal is provided with a pair
of comb-like structures supposed
to resemble the pectines of
scorpions, and the legs end in a
double claw. Lower Carboni-
ferous ; Scotland.

Hastimima White. Large forms having
impressed median ventral plate.
Devonian of South Africa.

Fig. 1512.

Pterygotus buffaloensis (Pohlman). Bertie Waterlime (Silurian) ;
Buffalo, New York. The toothed anterior chela. 1/2.

i pterygotoid hastate telson with
Carboniferous ; Brazil, Nova Scotia (?) and

Order 4. LIMULAVA Walcott.

Body elongated. Frosoma with lateral or marginal eyes ; on the ventral side
with five pairs of appendages, some of which are hiramous. Fostcephalic portion
of hody {mesosoma and metasoma) consisting of twelve segments, the anterior nine of

VOL. I 3 E

786 ARTHROPODA phylüm vii

which bear gills ; the last has a central spatulate process that, comhined with
swimmerets, forms a strong caudal fin.

It is doubtful whether this group, which in the biramous jointed legs and
Compound telson possesses crustacean features, belongs to the merostomes or
connects the latter with the crustaceans.

Walcott, from his discovery of jointed body appendages in Sidneyia, is
inclined to the view that this genus is transitional between trilobites and
Eurypterids. One family is recognised, the original diagnosis of which is
given as follows :

Family 1. Sidneyidae Walcott.

Cephalothorax small, without lohes, eyes marginal; ventral side with large
epistoma, five pairs of movahle appendages, the gnathohases of the three posterior
pairs forming organs of manducation. Abdomen twelve-jointed, the three posterior
Segments annular and narrow, the terminal one forming, with lateral swimmerets, a
fan-like tail ; nine anterior segments with a pair of branchial appendages on each ;
the three posterior segments without ventral appendages. Surface smooth, or
ornamented by narrow, irregulär, fine imbricating ridges.

In this family are placed two genera, Sidneyia and Amiella Walcott, from
the Ogygopsis shale of the Stephen formation (Middle Cambrian), near Field,
in British Columbia, Canada. They are described and figured in Smithson.
Mise. Coli., 1911-12, vol. Ivii., nos. 2 and 6. Sidneyia inexpectans Walcott,
the type species, which attains a length of about 17 cm., is represented by
very fine material. The accompanying genus Amiella is less satisfactorily
preserved, and there are indications of its occurrence also in the Cambrian of
Yunnan, in Indo-China.

[The foregoing «chapter on the Merostomata has been revised for the present edition by
Dr. John M. Clarke, New York State Geologist, and drawings for several new figures of
Eurypterids have been kindly furnished by hini and Dr. R, Ruedemann, ofAlbany.— Editor.]

Subclass B. EMBOLOBRANCHIATA Lankester.'

Arthropods with at hast three preoral segments in the adult steige, ivith one pair of
preoral appendages called chelicerae, and five postoral pairs, the anteriormost of ivhich
are the pedipalpi. Chelicerae two- or three-jointed, retrovert or chelate. Pedipalpi
pediform, chelate or retrovert, typically six-jointed, legs typically seven-jointed. Uead
fused with at hast one thoracic segment, usually with the entire thorax, forming a
cephalothorax or prosoma. Genital opening on the first somite of the mesosoma.
Nephridia modified as coxal glands. Abdomen typically composed of twelve segments,

^ Literature : Gomstock, J. H., The Spider Book. New York, m2.—Fritsch, A., Paläozoische
Arachuiden. Prague 1904.-ÄWi, C. L., and Berendt, J. C, Die im Bernstein befindlichen
Crustaceen, Myriapoden, Arachniden und Apteren der Vorwelt. Berlin, l^U.—Lankester, E. R.,
Ar icles on Arachuida and Arthropoda in Encycl. Brit., IQll.-Laurie, M., Gn a Silnrian Scorpion

tl^^ff ""^^^''^'^'/^f^^^^ozoic Arachnida of North America. Trans. Conn. Aead. Sei. (In
KTainTn Q im'i ^^"«g^^P^^ of the terrestrial Carboniferous Arachnida of Great Britain.
/./ r 3; r'-' ^l^h~n''f''' ^- ^^•' ^''''^ «Pi^^^«- H^r^^rd Univ. Bull., 1882, vol. ii.-
His ' «QO V r-' r?" ^f^,°"^f«^of Arachnida of North America. Mem. Boston Soc. Nat.
fr^l ArSids 'r;;^ tT^ P V^c.*^'" ^r^"'' ^^''^^ ^'''^'^' °f ^^^ World, including Myriapods
branchLta in Pnn 1 1 ^-S- ^«0 • Surv. No. 71, ISn.- Warhurton, C, Chapter on Embolo-

r^i le Siluria^ 'n^^ A "'"'"^ ^S^^^F' ^""^^"^' ^^OQ.-Whüßek, k P. Fossil Scorpion

trom the Silunan rocks of America. Bull. Amer. Mus. Nat. Hist., 1885 vol i

SÜBCLASS II

EMBOLOBRANCHIATA

787

even when external segmentation is subsequently lost. Anus on last abdominal segment.
Eyes, when present, simple, variable in number. Respiration by lung-books or tracheae.

Tlie subclass of Embolobraiicliiata incliides spiders, scorj)ions, niites, ticks, etc.,
and comprises in all thirteen orders. Of these four are eiitirely extinct, and of
tliose still living six liave continued to exist since tlie Paleozoic, and only one is not
known to have fossil representatives. So far as tlie evidence of extinct forms goes,
tlie older menibers of tlie various Orders seem to have resembled to a remarkable
degree tliose existing at tlie present day, and serve to illiistrate the extreme antiquity
of living types of invertebrate animals. Tlie majority of fossil species is known from
remains preserved in amber of Lower Oligoceiie age in eastern Prussia. The most
delicate parts, including the finest hairs and sjDiders' webs are to be fonnd practically
iinaltered within this transparent fossil resinoiis siibstance which exiided from ancient
Cüiiiferous trees.

The Order Scorpionlda (Scorpiones) is the oldest among the Embolobranchiata

Fia. 1513.

Upper Silurian pninitive Scorpions, l'alaeopTionus. A, P. nuntiils Thor, and Lindst. Ludlow series
(Clunian); Gotland. Hcstoration of dorsal aspect. ^/s (after Pocock). B, F. caleilonicus Peach. Ludlow
series (Clunian) ; Lanarkshire. Reconstruction of ventral aspect, in which the space for a genital operculuni,
the pair of pectens, and the absence of any evidence of pulmonary Stigmata are noticeable features. »/o (after
Pocock).

and bears witness to a common origin witli the Eurypterida. Scorpions are
characterised by having three-jointed chelate chelicerae and six-jointed chelate
pedipalpi ; the head is fused witli the thorax ; the abdomen is composed of twelve
Segments, the last five of which are annular and form the so-called postabdomen or
tail. At the end of this latter is a telson modified as a poison gland witli sting.
On the ventral surface is foiind a characteristic pair of appendages, the "comb."
Lung-books are present in four pairs.

Silurian Scorpions ai'e grouped together uiider the suborder Apoxypoda, which
contains a single fainily represented by the genera Palaeophonus Thorell (Fig. 1513)

788

ARTHROPODA

PHYLUM VII

and Proscorpius Whitfield. The former of these comprises three species occiirring in
the Upper Silurian (Clunian) of Gotland and Lanarkshire, and tlie latter a Single
one froni the Bertie Waterlime of New York. Pocock has suggested that the
supposed mesosomatic " sternites " of Palaeophonus are really broadly laminate
gill-bearing appendages, as they have been shown to be in Eiirypterus. Similar
appendages occiir also in Eohuthus, and it is inferred that respiratory lamellae lay
beneatli tlieni as they do in Limulus. Thus, the breathing organs in primitive
Scorpions were gills, and the animals are thought to have been aquatic, possibly
even marine. But in Carboniferous genera an important change has taken place,
in that the covering plates have closed over the lamellae of the gills, leaving only
slit-like openings called Stigmata. Breathing in these forms took place by the
admission of air through the Stigmata to lung-books. P. nuntius was blind.

Eoscorpius Meek and Worthen (Fig. 1514) ; Isohuthus Fritsch ; and Cyclophthalmus
Corda, are exaraples of Carboniferous Scorpions. Eoscorpius does not differ in any
important respect from living forms, and appears to have been quite as liiglily
organised. According to Fritsch the order Scorj^ionida attained its acme during the
Carboniferous and snbsequently declined. Imperfect remains have been found in the
Trias of Warwickshire, and a species of Tityus Koch occurs in Oligocene amber.

The Order Pedipalpida (Whip-scorpions, etc.) has two-jointed retrovert chelicerae,
and six-jointed, retrovert or chelate, raptorial pedipalpi. The first pair of legs is

Fig. 1514.
Eoscorpius carhonarius Meek and Worth. Goal Measiires •
Mazon Creek, Illinois. A, Dorsal aspect of sonia, i/i- B, Pecten
or " comb, ' enlarged.

Fig. 1515.

Geralinura bohemica (Kusta).
Goal Measures ; Rakonitz, Bohemia.
Vi (after Kusta).

yery long and modified as tactile organs. Coxae of second pair of legs placed behind
those of the pedipalpi, while the small coxae of the first pair are widely separate
and situated above and external to the former. Abdomen segmented, movably jointed
to the cephalothorax ; last two or three Segments small, annular, either with or with-
outa segmented whip. To this order belong Geralinura (Fig. 1515) and Graeophonus
Scudder, from the Carboniferous ; Stenarthron Haase, from the Upper Jurassic Litbo-
giaplnc Stone of Bavaria ; and Phrynus Latreille, which occurs Tertiarv and Recent.

found m Southern Italy, Sicily, and Texas. It has no fossil representatives.

The extmct order Kustarachnida is represented by a Single family, comprising

SUBCLASS II

EMBOLOBRANCHIATA

789

Fig. 1516.

Kustarachne tenuipes
Scudder. CoalMeasures;
Mazon Creek, Illinois.
3/2 (after Petrunkevitch).

Fig. 1517.

Protosolpuga carbonaria Pet-
runk. Goal Measures ; Mazon
Creek, Illinois. 1/1 (after Pet-
runkevitch),

the solitary geiiiis Kustarachne Scudder (Fig. 1516), of wliicli iliree Carbon iferous
species have been described. Chelicerae not observed ; pedipalpi chelate, tlieir
coxae fused solidly together ; ,ab-
domen segmented, pediciüate, the
terminal segment annuliforni ; legs
long and slender;

The Order Solpugida (Solifugae)
has the head fused with the first
thoracic segment, all the remaining
thoracic segments being free. Cheli-
cerae chelate : pedipalpi pediform ;
abdomen segmented ; resj)iration by
means of tracheae ; trochanters two-
jointed ; coxae and trochanters of
the fourth pair of legs with a row
of characteristic " maleoli," Proto-
solpuga Petrunk. (Fig. 1517) is
known from the Carboniferous.
Modern forms are subtropical.

The Order Ricinulei or Podo-
gonida, is represented in the modern fauna by two tropical genera, and includes also
a few Carboniferous forms. Head and thorax fused, forming a cephalothorax, in
front of which is a movable plate called the " cucuUus." Abdomen composed of
nine segments, but so united with the cephalothorax that the first and second
abdominal segments are not visible. The three hindmost segments are small, annular,

forming a short " tail."
Chelicerae are two-
jointed, chelate; pedi-
palpi chelate ; tro-
chanter of first and
second pairs of legs
two-jointed ; the third
pair of legs in the
male is modified as a
copulatory apparatus ;
eyes absent in both
sexes. Polyochera
Scudder (Fig. 1518);
and Curculioides

J'olyochera pviiitulafa ISciul. Goal Measures ;

Mazon Creek,
vitch).

JUiuois. a/2 (after Petrunke-

FiG. 1519.
Chclifer liemprichi Menge.

Oiigocene; Baitic amber. 9/i. Buckland are Carboni-
ferous examples.

The Order Pseudoscorpionida also known as Chernetidea or Chelonetni (False
Scorpions), is chiefly Recent, with no fossil representatives older than the Tertiary.
In this group the head is fused with the thorax, the abdomen is segmented and
broadly joined to the cephalothorax. Chelicerae chelate, with openings on the
movable finger for the ducts of the spinning glands ; pedipalpi chelate. The Recent
genus Chelifer Geoffr. (Fig. 1519) occurs also fossil in Baitic amber.

The Order Araneida or Araiieae (Spiders) has numerous fossil representatives,
the earliest of which appear in the Carboniferous. Head and thorax fused ;
chelicerae two-jointed, retrovert ; pedipalpi pediform, tlieir terminal Joint in the
male modified as a copulatory organ ; abdomen segmented only in the most primitive
suborder, anteriorly constricted and movably united with tlie cephalothorax ; usually
six spinnerets present on the abdomen, but their number may vary between two

ARTHROPODA

PHYLUM VII

790

and eight. Arthrohjcosa Harger (Fig. 1520), and Protolycosa Roemer (Fig. 1521), are
CurboiiiftTon^; examples, but tlie majority of forms are known from Oligocene amber
fouii.l Oll llic slu.ivs of the Baltic in Fast Prussia. Mizalia Koch (Fig. 1522) is an

Fig. 1520.

Arthrolycosa antiqua Harger. Goal Measures
Mazon Creek, Illinois, i/i (after Petrunkevitch).

Fig. 1521.

Protolycosa anthra-
cophila Roemer.
Goal Measures ;
Myslowitz, Silesia.
(after F. Roemer).

Fig. 1522.

Mizalia rostrata Koch and
Berendt. Oligocene ; Baltic
amber. 3/,.

Fig. 1523.

A ttoides eresiformis Brongt.
Oligocene ; Aix in Provence.
lO/x (after Brongniart).

Fig. 1524.

Thomisns oeningensis
Heer. Fresh water Mio-
cene ; Oeningen, Baden.
'•2/1 (after Heer).

example from the latter locality ; Attoides Brongt. (Fig. 1523) occurs in the fresh -
water Oligocene marls of Aix in Provence, and Thomisus Walck. (Fig. 1524) in
similar deposits of Miocene age at Oeningen, Baden. The Upper Oligocene lignites

of Rott, near Bonn, Ger-
many, and the Miocene fresh-
water strata of Florissant,
Colorado, have also yielded
remains of this order. Among
Eocene localities, from which
fossil Spiders have been ob-
tained, should be mentioned
the Green River beds of
Wyoming, and the strata at
Quesnel, British Columbia.
The known species of fossil
Spiders aggregate about 250.
The Order Anthraco-
marti is confined to the
Paleozoic, and is perhaps
ancestral to the Pedipalps
and Opiliones, being in some
Its distinguishing characters are as follows :

Fio. ]

•'^ M.'as.uvs; Xeu-

ity.n-, .>i.>-m;i. Dorsal aspoct.
Vi (after Karsch).

FlO. VyOi

Goal M.,i
land. I)

• V'<-tncd (Buckland).
^ , < <).ill)iookdale, Eng-
' ■■i^l'i'ft, shovving ten

i?'?\. •'""'*^"^^ of the hind-bodv.

Vi (aftei \Vood\\ard\

Kl\vc(.ai them.

J

suBPHYLUM II MYEIAPODA 791

head fiised with the thorax ; abdomen segmented, apparently broadly joined to the
cephalothorax ; between the tergites and steniites one or two rows of pleural
sclerites ; anus witli an operculiim wliicli represents the tergite of the eleventh
Segment ; chelicerae not known ; pedipalpi short, pediform ; legs seven-jointed with
niovable coxae apparently articulated to a sternum. Änthracomartus Kartsch (Fig.
1525); Brachypyge and Eophrynus Wood ward (Fig. 1526) ; Maiocercus and Trigono-
tarhus Pocock ; and Kreischeria Geinitz are Carboniferous genera.

The Order Haptopoda is also confined to the Paleozoic. Head fused with the
thorax ; abdomen segmented, broadly joined to the cephalothorax ; pedipalpi short,
pediform ; pleura soft, withont sclerites ; tarsus of the first pair of legs seven-jointed.
Plesiosiro Pocock, from the Carboniferous of England, is the solitary known genus.

The Order Phalangiotarbi, like the two preceding Orders, is Paleozoic. Head
fused with the thorax ; al)domen broadly joined to the cephalothorax, segmented,
with soft pleura devoid of sclerites ;
several anterior tergites very short, wdth a
thickened posterior edge ; anus with an
operculum, representing the tergite of the
twelfth Segment ; chelicerae not observed ;
pedipalpi short, pediform. Phalangiotarbus
Haase ; Geratarbus Scudder ; and Archi-
tarhus{= Geraphrynus) Scudder (Fig. 1527);
Opiliotarhus Pocock; Discotarhus ^Vetruiik.,
etc., are Carboniferous.

The Order Phalangida or Opiliones
(Harvest -Spiders) has many fossil repre-
sentatives, most of which are preserved in

Oligocene amber. Head fused with the -^ • ^^

thorax ; abdomen broadly joined with the Fig. 152Y.

cephalothorax, segmented, the anal oper- ArcUtarhus rotundatus Scudder (=Geraphrynus
pnlnm ro-nrpcjpnf in» fliP tprcrifp nf tTiP tpnfli carbonaHus Scudder). Goal Measures ; Mazon Creek,
culum representing tue tergite ol tue tentn ^^^^^^^^^ un^er surface. i/i (after Petrunkevitch).

Segment. Chelicerae three-jointed, chelate;

pedipalpi pediform ; coxae of the first, often also of the second and tliird pairs of legs
with maxillary lobes ; one pair of tracheae. Nemastomoides Thevenin ; Dinopilio
Fritscli ; and Protopilio Petrunk,, all from the Carboniferous, are referred to this
Order. The first-named of these, however {Nemastomoides claveris Thevenin), may
possibly belong to the Anthracomarti.

The Order Acarina, Äcari, or Rhynchostomi (Mites, Ticks, etc.) comprises degenerate
Arachnids in which the abdomen is usually not segmented and is either broadly
joined to the cephalothorax or completely fused with it. Coxae of pedipalpi fused
together ; coxae of legs widely separate, without maxillary lobes. Numerous fossil
representatives are known from Oligocene amber and Tertiary freshwater deposits,
the majority of species being referable to Recent genera. Through the Opiliones this
Order appears to be connected with the Spiders.

SuBPHYLUM B. Myriapoda Latreille/

Tracheate Arthropods with distinctly separat ed head bearing a single pair of
antennae, and a soma composed of numerous {at least twelve) fairly similar segments

^ Literature : Fritsch, A., Fauna der Gaskohle, vol. iv. Prague, 1899-1901. — Orinnell, F.,
Quateniary Myriapods and Insects of California. Univ. of Cal. Publ., Dept. Geol., 1908, vol. v. —
Koch, 0. L., Die Myriapodeu. Regensburg, 1847. — Koch, G. L., and Berendt, J. C, Die im
Bernstein bettndliclien Crustaceen, Myriapoden, Arachniden und Apteren der Vorwelt. Berlin,

792 / ARTHROPODA phylum vii

which are'ne/er divided into tagmata ; there are two or three pairs of mouth appendages,
and num^röus pairs of legs.

The time-honoured division of Myriapods into the Orders commonly known
as Centipedes and Millipedes {Ghüopoda and Diplopoda), plus the inore recently
established groups of Pauropoda and Symphyla, which latter have no fossil repre-
sentatives, has of late years been abandoned. The prevailing modern view is to
regard the above-mentioned groups of tracheate Arthropods as independent classes of
the phylum ; and the reason for this is found in the recognition of closer affinities
between the Chilopoda (Centipedes) and the Hexapoda (Insects), on the one band, than
between the Chilopoda and Diplopoda on the other. According to the modern System
the older fossil Millipedes, which are embraced in the extinct orders Protosyngnatha
and Archipolypoda of Scudder, fall within the liniits of the class Diplopoda.

For practical purposes, however, it will be convenient to retain the designation
Myriapoda in a general sense, it being a familiär term, and the number of fossil
forms with which the paleontologist has to deal being comparatively limited. The
groups of which Centipedes and Millipedes are the most important members are here
treated as classes, conformably to the view which assigns them equal rank with the
exclusively Recent Pauropoda and Symphyla. Among the latter, certain genera
agree exactly in the numerical segmentation of the body with an isopod, a thysanuran,
and a primitive arachnid. This would lead to the inference, as pointed out by
G. H. Carpenter, that " all the Arthropodan classes must be derived from ancestors
with a definite number of segments, and the development of a large number of
somites in such forms as Julus, Geophüus, and Äpus must be regarded as a secondary
condition."

Olass 1. DIPLOPODA Gervais (Chilognatha Latreille). (Millipedes).

Trunk homonomously segmented, segments usually numerous and not ßattened, of a
variable numher {from 12 to 150), and the majorüy of them fused pairivise, each tergite
hearing two pairs of legs. Read with one pair of short, seven-jointed antennae, one pair
of mandihles, and one or two pairs of maxillae. No Compound eyes, hut numerous ocelli
usually present.

The anterior three or four segments of the soma are free, with a single pair of
legs to each segraent. The anterior pair, or both pairs of legs corresponding to the
seventh tergite are usually modified as copulatory organs
(gonopods), but in one order (Oniscomorpha) it is the
posterior pair of legs that is thus modified. A pair of
genital openings is present at the base of the legs of the
second segment. Respiration takes place by means of either
tufted or tube-like tracheae with spiracles at the base of
the legs.

Recent Diplopoda are divided into eight Orders. At
Fig. 1528. least five of the modern families have Tertiary representa-

0ÄnTl?S7tVE t^''' '^P'^^'^^y ''' ^^^^^- ^^^^«i^g Tertiary examples may
Bonn, Germany. i/j. be mentioned the foUowing : Julus Linn. (Fig. 1528);
_^^Gmspedmoma Leach ; Euzonus Menge ; Polyxenus Latreille i

Sof kTi^rlsgg Toi ^;.f"^y^«^ Myriapods from the Palaeozoic rocks of ScTtlaml. Proc. Phys.
iTu-t^dder S^^^^^^^^^^ ^., Articles on Centipedes and Millipedes in Encycl. Brit,

loKu^iT inn'/n^^^^^^ ^''^'- ^^^^on Soc. Nat. Hist., 1873-90

nanies ba.sed on American Insect7;;n7Araclmfd. f~ .t''f ' J' ^' '^•' ^"^'^'^^^^ "^" ^^' ^'''''''
type species. Bull. Amer. U^Cmllm^^^ "^■'^'- ^'''' ^"''^^'^°"^ '' '^^

I

SUBPHYLUM II

MYRIAPODA \ \ 793

of Julud (tA

and Phryssonotus Sciidder {Lophonotus Menge). A species of Julm (JV telluster
Scudder) occurs ki tlie Green River Eocene of Wyoming, and another in the Miocene
freshwater beds of Florissant, Colorado.

The older fossil forms are referable to the two extinct Orders of Scudder, Proto-
syngnatba and Arcbipolypoda. The former of these approaches closely to the Recent
Order Pencillata, and is represented by the Carboniferous genus Palaeocampa Meek
and Worthen. The second of these Orders comprises three families, of which the
Arcliidesmidae resembles the Recent Polydesmidae. Ärchidesmus Peach (Fig. 1529);

Fig. 1529. Fio. 1530.

Ärchidesmus macnicoli Peach. Lower Old Red Sand- Euphoberia armigera Meek and Worth. Goal

stone ; Forfarshire, Scotland. i/i (after Peach). Measiires ; Mazon Creek, Illinois, i/i-

and Kampecaris Page, from the Old Red Sandstone of Scotland, are examples, The
family Euphoberiidae shows sonie resemblance to the Julidae of the present fauna,
but the dorsal scuta are more or less distinctly divided into two portions corresponding
with the pairs of legs. Among Carboniferous genera belonging to this family may
be mentioned the following : Äcantherpestes and Euphoberia Meek and Worthen
(Fig. 1530); Ämijnilispes and Eileticus Scudder. Äcantherpestes is regarded by
Scudder as probably amphibious, and attains the relatively enormous length of
20 cm. {A. giganteus Baldwin). The family Archiulidae is represented in the
Carboniferous by Trichiulus and Archiulus Scudder, and Xylohius Dawson. One
Mesozoic species, Julopsis cretacea Heer, from the supposed Cretaceous of Greenland,
is of doubtful ordinal position, but may belong to the Arcbipolypoda.

Olass 2. OHILOPODA Latreille. (Centipedes).

Body more or less ßattened dorso-ventrally, composed of a variable number of
Segments {from 18 to 176), with a single pair of legs to each segment. One pair of
segmented antennae, the joints being at least fourteen in number, one pair of mandibles
and tum pairs of maxillae. First pair of somatic appendages modified as powerful
maxillipeds with poison glands emerging on the terminal claw (toxognaths). Last pair
of appendages (those borne by the antepenultimate segment) modified as copulatory organs.
Unpaired genital aperture on the penultimate segment. Eyes variable in number, simple
or Compound (Scutigera), often wanting. Respiration by means of tracheae with either
p)aired spiracles in the pleural membranes or single spiracles in the median dorsal line.

Recent Chilopoda are divided into five Orders, three of which have Tertiary
representatives, esjDecially in amber, and in the freshwater deposits of Aix in Provence.
The following true Chilopod genera are known from the Tertiary : Cermatia Rossi ;
Scolopendra Linn. ; Lithobius and Geophilus Leach. The older fossil remains cannot be
positively referred to any of the five existing Orders. By Scudder they were assigned
to two extinct families, named by him Gerascutigeridae and Eoscolopendridae.
The former of these includes the genus Latzelia Scudder, and the latter the genera
Palenarthrus and Ilyodes Scudder, all from the Coal Measures of Illinois.

[The text for the preceding chapters on Embolobranchiata and Myriapoda has been revised
by Dr. Alexander Petrunkevitch, of Yale Uiiiversity. — Editok.]

794

ARTHEOPODA phylüm vii

/BüBPHYLUM C. Insecta (Hexapoda). In'sects.^

Tracheate, Arthropods with hodtj at maturity consisting of a distind head, thorax
and abdorrten. Head provided with one pair of antennae, one of mandibles, and two of
maxillae. Thorax composed of three segments, each supplied with a pair of legs, and the
second and third segments also usually carrying a pair of wings on fheir dorsal surfaces
in the adult state. Abdomen composed of several (commonly ten) distinct segments, and
usually without leg-like appendages. Development usually through metamorphic stages.

No undovibted remains of Insecta are known from strata older than tlie
Cai'boniferoiis, but in the Goal Measiires and Perniian a considerable variety of
winged forms has been detected, in both Europe and North America. These earlier
Insects appear to be more generalised than are the post-Paleozoic forms, and the
majority are referred by Handlirsch to Orders distinct from those occurring in Mesozoic
and later formations. But one order, the Blattoidea, seems to have survived from
Paleozoic times onward to our own day. The primitive extinct order Palaeodictyop-
tera is regarded as the ancestral stock which gave rise to the other Paleozoic Orders,
and from the latter in turn have originated the modern Insect groups.

Although it is clear that strangely differentiated forms occurred among the
different Insect groups as early as the Carboniferous, yet it has been conclusively
shown that this differentiation had little depth, and that it is only through Mesozoic
and later descendants that we have any clue to a wide Separation of the original
Paleozoic forms. Among the latter, the neuration of the wings, though diversified,
had yet a far greater homogeneity than is found now, or than existed during Mesozoic
time, from the Trias onward. The fore wings of wh'atever type were as diaphanous as
the hind, and could never (as in most of their descendants) properly be called tegmina.
The wings of the Protodonata of Brongniart had indeed a superficial resemblance
to those of living Odonata in shape, reticulation, and sweep of the veins. But in
fundamental neuration they were altogether different, and no trace is to be discovered
of those characteristic features of the Odonata, such as the nodus, triangle and
pterostigma, which appear fully elaborated in the Mesozoic species.

"The wings, broadly speaking, may be said to be three-margined. The margin
that IS anterior when the wings are extended is called the costa, and the edge tliat is
then most distant from the body is the outer margin, while the limit that lies along
the body when the wings are closed is the inner margin.

"The only great order of insects provided with a single pair of wings is the Diptera,
and in these the metathorax possesses, instead of wings, a pair of little capitate
bodies called halteres or poisers. In the great order Coleoptera, or beetles, the
anterior wmgs are replaced by a pair of horny sheaths that close together over the
back ot the insect, concealing the hind wings, so that the beetle looks like a wingless
insect ; in other four-winged insects it is usually the front wings that are most useful
in night. In the Orthoptera the front wings also differ in consistence fmm the

rnZriTi^T TJ^ . *^'^^^' in repose, and are called the tegmina." (Sharp,
Cambridge Natural History, vol. v.) b \ i^,

lusL^l^TH''tlS£r''Z^ '" *'i V'7''S ™"^'^ -ell-known publications on fossil
1906-8. See IL nZd^Ch^. ^ Ta ^^•^- ^^''<^^i^'<^^ Die fossilen Insekten, Leipzig,

•■'■'•• H..]in„ Brues Bufr ?W1 ll ^^^^tribuüons one shonld consult the writings of Agnns

TlH- n„w, Z^^ S^'^lf^^'^' Ulmer, Wickham, and oth(

lers.

/^rj!/'.\'/7'/''' p"V'' \^'^ '"'"''* '''''"''' °^ Commentry are contained in the follow-
«tc. Saint- |.:t ienne, ' 1893 ^ ~-^Mry\'n-lr i^"" m """ ''T''' '' ^'^i^^^ire des insectes des temps primaires,
l-ilh.rde<^..n.ntry(Ailier).Tn;a^y,~:l;;^^^^^^^^^^^ '^^'^'^^ ^" '^''^'^

I

\

SüBPHYLüM III INSECTA \ ^ 795

\

Among the Orthopterons Insects of the British series of Carboniferl^us rocks are
a niim])ei' of forms allied to cockroaclies, and nodiiles of the same age contain wings of
Palaeodictyoi3terous and allied Insects, some of them showing colour bands (Brodjea).
At Comnientry (Allier), France, is found the riebest deposit of Carboniferous"' Insects
in the world, and this faiina has been ably investigated by Charles Brongniart
(1893) and later writers. Very numerous fossil remains are known from diiferent
Mesozoic and Cenozoic horizons. The Insects found in the English and German
Lias are for the most part small and insignificant, bat there are known a moderate-
sized dragonfly, and also a few Coleoptera. Various remains occur also in the Stones-
field Slate, Purbeck, Wealden, Bagshot Beds (Upper Eocene), and Bembridge Beds
(Oligocene) of England. Insects are well represented in the Lithographie Stone
(Kimmeridgian) of Bavaria ; in fresh water Oligocene deposits of Aix in Provence,
and especially in Baltic amber of the same age from East Prussia ; in the Miocene
brown coal of Rott near Bonn ; in the Miocene lacustrine deposits of Oeningen,
Baden, on Lake Constance ; and in similar deposits of Florissant, Colorado, also
of Miocene age. Many Insects also come from the Miocene deposits of Radoboj
in Croatia, and from the Indusial limestone of Lower Miocene age from Offenbach.
There is considerable reason to suppose that Insects were more numerous in species
during Tertiary times than they are at the present day.

In the System here adopted the winged or wingless condition is made the basis
for dividing Insects into two classes, Pterygogenea and Äpterygogenea. The former
of these comprises forty Orders, thirteen of which are entirely extinct. The lowly
organised class of apterous Insects comprises four Orders, three of which have Tertiary
representatives as well as Recent, and the remaining order is without known fossil
representatives.

If the opinion of Lankester and Börner,.that the primitive Insects have a special
afhnity with the Isopoda, be accepted, the discovery of Oxyuropoda in the Devonian
of County Kilkenny, Ireland, becomes of particular interest (see ante, p. 757). In
the view of G. H. Carpenter, a more general relationship between Insects and
Crustacea seems probable, so that this Devonian Isopod genus and the lowly organised
Pterygote order of Palaeodictyoptera must be regarded as having each advanced along
different lines of specialisation from their common ancestors. The common stock
from which both Crustacea and Insecta are descended must surely have been Arthro-
pods with undifferentiated trunk-segments, yet on the whole, resembling primitive
Crustaceans in structure, and possibly not very remote from Trilobites.

Olass 1. PTERYGOGENEA Brauer.

Insects normally winged in the adult, or secondarily wingless, with faceted eyes, and
ahdomen usually with nine or ten distinct Segments.

t Order 1. PALAEODICTYOPTERA Goldenberg.

Head moderately large, rounded, ivith siw/ple antennae, mouth parts adapted for
biting, and well-developed jaws. Two pairs of wings, suhequal in size, of similar form
and primitive venation, incapable of heing folded hacJcward over the ahdomen ; sometimes
a rudimentary third pair present on the first thoracic segment Ahdomen consisting of
ten nearly homonomous segments which often exhihit pleural lohes. Terminal segment
often with much elongated cerci. Thoracic legs similar.

In this Order the wing structure is very primitive (Fig. 1531), corresponding

t Tills sigu is iised tliroiigliout tlie following pages to indicate that the ßystematic group referred
to is extiuct.

796

ARTHROPODA

PHYLUM VII

viTV iH'.'irly 1(
less irro'nilar :

llie hypothetical type,
tlie anal lobe Is not

Tlie cross-veins are numerous and more or
by a fold ; the anal veins are always
well developed, more or less branclied,
and curved regularly backward to tlie
posterior margin ; and there is no
anal fold nor fan - like plaitings.
Larvae are similar to the imago.

The Palaeodictyoptera are best
regarded as a generalised group of
very primitive Organisation, and as
. the probable progenitors of all winged
Insects. They are restricted to the
Paleozoic, and occiir in various
European and North American
localities. There are about 120
known species, the majority of which
are European, and about one-fourth of this nuniber being found in the Carboniferous
of the United States and Canada. Six species are known from the Pottsville, ten
from the Kanawha and Little River groups, eleven from the Allegheny, one from the
Conemaugh, and the remainder of American forms from the Productive Goal Measures,
Many of these Insects attain considerable size. The foUowing named families liave
been distinguished :

Dictyoneuridae, of which the genus Stenodictya Brongn. (Fig. 1532) is an example.

Fig. 1531.
Diagram of the neuration of a primitive insect wing, one
of the Palaeodictyoptera. The principal longitudinal veins
are connected by a network of cross - veins. c, Costa ; sc,
Subcosta ; r, Radius ; rs, Radial sector ; m, Media ; cu,
Cubitus ; a, Anal veins or nervures (after Handlirsch).

Fig. 1532.

rJUa^^r^" ^^f"- ßfong»- Stephanian (Upper Carboni-
ferous) ; Commentry, Allier, France. The antennae ocelli and
tarsi are reconstructed. 2/3 (after Handlirsch). ' ^

Fig. 1533.
Eublephis danielsi Handl. Goal Measures ;
Mazon Creek, Illinois. The antennae. ocelli
and tarsi are reconstructed. 2/^ ' (after
Handlirsch).

L thoZ tl ' /^Wtüidae, HypermegetMdae, Mecy>opteridae, Syntonopteridae,
Fouaul r;..^^"T?^''^ Homoipteridae, Homothetidae, Heolidae, Broyeriidae
f~nted ,':Ä""'f%«P''^Pt«"dae, Lamproptüidae, Polycreagrida;, Eubleptida

t Order 2. MIXOTERMITOIDEA Handlirsch.

I

SUBPHYLUM III

INSECTA

797

Tliia Order is probably an early aberrant offshoot of the preceding group, and is
known from two genera. Mixotermes Sterzel (Fig. 1534) occurs in tbe Coal Measures of

\

Mixotermes lugauensis Sterzel. Coal Measures ;
Lugau, Saxony. Fore wing. 2/j (after Hand-
lirscli).

Fig. 1535.

Recula parva Schlechten. Coal
Measures ; Wettin, Saxony. Fore
wing. ^/i (after Handlirsch).

Saxony, and Geroneura Matthew in tlie Little Eiver group (approxiiiiately eqnivalent
to tlie Kanawha series) of New Brunswick.

t Order 3. RECULOIDEA Handlirsch.

An early aberrant offshoot of the Palaeodictyoptera, with peculiarly specialised wing
neuration, and approaching in some respects to the Protorthoptera and Protohlattoidea.

Tliis Order was proposed in a provisional sense to incliide the single genus Recula
Handlirsch (Fig. 1535), from the Coal Measures of Saxony.

t Order 4. PROTORTHOPTERA Handlirsch.

Wing pairs of unequal size, capahle of being folded backward over the abdomen, and
with more complicated venation than in the preceding types, approaching in some respects

Fio. 1536.

Spaniodera amhnlans Handl. Coal
Measures ; Mazon Creek, Illinois, i/j
(after Handlirsch).

Fio. 1537.

Oedischia williamsoni Brongn. Stephanian ;
Comnientry, France. A forerunner of true Locus-
toids, with long antennae and hind legs adapted
for springing. '■^/■^ (reconstructed by Handlirsch).

that of the modern Locustidae. Hind wings similar to the front pair, but with larger anal
area^ marJced off by a fold. Antennae long and slender ; mouth parte strong, adapted
for biting. Prothorax often elongated or saddle-shaped^ legs similar in form, the third

798 ARTHROPODA phylum vii

pair sometimes elongated and adapted for springing ; cerci short or of moderate size ;
abdominal segments without lateral lohes. Females of some species with a well-developed
ovipositor.

This Palet)zoic group is apparently intermediate in position between the Palaeo-
dictyoptera and Orthoptera proper. There are iipwards of ninety known species,
about twenty of wliich occur in the Goal Measures of North America, and forty in
the Permian of Kansas. The following named families have been distinguished :

Spanioderidae, of which the genus Spaniodera Handl. (Fig. 1536) is an example,
Isclmoneuridae, Cnemidolestidae, Prototettigidae, Homalophlebidae, Protokollariidae,
Schuchertiellidae, Pachytylopsidae, Caloneuridae, Stenaropodidae, Oedischiidae (with
well-developed jumping legs as shown in Oedischia Brongn.) (Fig. 1537), Omalidae,
Geraridae, Sthenaroceridae, Apithanidae, Cacurgidae, and Narkemidae.

Order 5. ORTHOPTERA Olivier.

Mouth parts well developed, mandihulate} Wings unequal, capahle of heing folded
backwards over the abdomen. Fore wings coriaceous^ with numerous cross-veins, and the
principal longitudinal veins, with most of their branches, directed towards the outer
margin. Bind wings thinner, delicately veined, with a large, plicated anal area.
Prothorax saddle-shaped ; hind legs generally saltatorial.

The Orthoptera are Insects of comparatively large size. The largest of existing
Insects are included within this order, and none of its members is so small as are
many minute representatives of other Orders. Modern forms include grasshoppers,
locusts, green grasshoppers, katydids, and crickets.

Suborder A. LOCUSTOIDEA Leach. (Locusts and Crickets).

_ Cubital area in the fore wings of the male (in most modern forms) modified into
stndulating organs ; anterior tibiae with auditory organ ; tarsi three- or four-jointed ;

antennae long and slender, consisting of
more than thirty segments; female almost
always with well developed ovipositor.

The earliest known members of this
suborder are found in the Lias of
Europe, and belong to the extinct
families of Locustopsidae and Elcanidae
(the latter typified by the genus Elcana
^'"•1538. Giebel) (Fig. 1538). Apparently no

MeÄr'l\?uTLoclsYXÄ^ stridulating organs were developed, but

oceiii partiy restored. 10/3 (after Handiirsch). ^ the Elcanidae lamellar appendages

tibiap bv mpoT,« r.f X.- 1 ^i^ • ^^^^ ^^^^ observed on the posterior

Ä wateTo. li . ; ^ects were probably able to ambulate on the surface
Wae The T T^ "^''V^' "^^^^"^^ °^ ''^' l^^-g Tridactylidae and
hoS and Crvlbd. ' P VTs ^'''j''^^'^ -«^« true Locustidae (Gieen Grass-
SÄeand^^v^o^^^^ ""l'^ stridulating organs, and the families Tri-

aactyhdae and Giyllotalpidae make their appearance in the early Tertiary. Remains

.na^ilfaClr 5, rS^^Vi^iiircthüt' IT'' • ^^ TT* ^^^^ ^" ^^^^^^ «^ --^^^^-' ^
that some of the mouth Parts are 0 a tul u^^^^^^^^ ^"""'^"'^ ^^ ' ^^''^^ *^' ^"'"^ '""^^^^^^ ^"^P^^^'^

or protects, a more minuitdlel^^SCIp^^^^^^^^^^ '" ' ^^°'^"^^' "^'^^^ ''''''''

SUBPHYLÜM III

INSECTA

^99

of crickets are known froni the Green Eiver Ecoene of Wyoming, and
are found also, witli locusts, in the Miocene lacustrine beds of
Florissant, Colorado. Various European species are known of J)ry-
madusa Stein. (Fig. 1539), and Gr ij II tis lAiui. (Fig. 1540). _

Fig. 1539.
Dryiriadusa sjteciosa (Heer). Miocene ; Oeiiingen, Baden, -/i

Suborder B. ACRIDIOIDEA Handlirsch.

Fig. 1540.

Gryllus macrocercus
Germar. Lower Oli-
gocene; Baltic
amber. s/g (after
Germar).

(Grasslioppers).

Stridulating organs situated in the hind femora and a modified longitudinal vein of
the fore wings. Äuditory organ on the side of the ßrst abdominal segment. Antennae
short, composed of less than thirty Segments. Tarsi short, three-jointed. No exserted
ovipo'sitor in the female.

Fig. 1541. *

Tyrbula russelli Seudder. Miocene lake
beds ; Florissant, Colorado, s/g (after
Seudder).

Tills is a group of com-
paratively late origin, and is
derived in all probability from
the Locnstopsidae or siniilar
lociistoid ancestors. Grass-
hüp})crs are known from the
Green Kiver Eocene of Wyom-
ing, and from the freshwater
Miocene of Florissant, Colorado,
and elsewliere. Tyrhula (Fig.
1541) and Nanthacia Seudder,
etc., are examples.

Fig. 1542.

Chresmoda obscura Germar. Tjithographic Stone (Upper Jura) ;
Solenhofen, Bavaria. -i/g (after Handlirsch).

Order 6. PHASMOIDEA Leach. (Walking-sticks, Leaf Insects, etc.)

Body usually long and slender, mouth parts orthopteroid, fore wings rarely well
developed, loithout stridulating organ, and without visihle demarcation hetween the
cubital and anal areas. Hind wings loith large, folded anal lohe; hind legs not
saltatorial, usually long and elender like the other pairs. Gerd short, genital appendages
of the female not prominent, tarsi five-jointed.

Here is placed the Upper Jurassic genus Chresmoda Germar (Fig. 1542), which,

800

ARTHROPODA

PHYLÜI* VII

a< ina.rated by tlie stnictnre of its legs, probably lived on tbe snrface of the water
as do luodern Gerridae. True terrestrial Phasmoidea occiir rarely in Baltic amber
and in the Miocene lake beds of Florissant, Colorado. An example from tlie latter
locality is Agathemera rechisa Scudder.

Order 7. DERMAPTBRA De Geer. (Ear-wigs, etc.)

Flat-hodied running Inseds with prognathous, orthopteroid mouth parts ; antennae
simple, consisting of from ten to thirty segments. Fore wings, when present, very feebly

developed, and forming sJiort, coriaceous tegmina.
Hind wings longitudinally and transversely plicated in
a complex fashion, consisting ahmst ivliolly of the
highly specialised anal lohe. Legs similar, with three-
jointed tarsi ; cerci chelate.

This is a specialised order, wliicli makes its first
appearance in tbe Tertiary of Europe and Nortli
America. Lahiduromma Scudder (Fig. 1543) is repre-
sented in the freshwater Miocene of Florissant, Colo-
rado, by about a dozen species. Forficula Linn.
ranges from the Eocene to Recent.

Fig. 1543.

Lahiduromnia exsulatum Scudder.
Miocene lake beds ; Florissant, Colo-
rado, a/j (after Scudder).

Order 8. DIPLOGLOSSATA de Saussure.

Includes the apterous, parasitical family Hemime-
ridae, living in Africa, nnknown in the fossil state.

Order 9. THYSANOPTERA Haliday. (Physopoda auct.).

Small terrestrial Inseds with asymmetrical, hypognathous, suctorial mouth parts,
short antennae, slender wings which are fringed ivhen present, but are often rudimentary
or wanting. Legs similar, tarsi with one or two joints, termi- j

natedhy avesicularstrudure; cerci reduced ; genital appendages ^"t^"^

oj the female forming a terehra. ^fJ

Several genera occur in the Oligocene and Miocene of
Europe, and three in the Green River beds (Middle Eocene) .^
along the White River in western Colorado. Thrips Linn. ; ^^
and Palaeothrips Scudder (Fig. 1544) are examples.

Fig. 1544.

t Order 10. PROTOBLATTOIDEA Handlirsch i'aiaeothripsfossuis smdder.

Green River beds (Eocene);

Insects usually attaining considerahle size. Read not con- ^''"- '''1^ ^^'''' ^''''^^''^■
cealed heneath the prothorax, with orthopteroid mouth parts, and simple, numerously
jomted antennae. Fore wings usually with multifurcate principal veins and numerous
cross-vetns; suhcosta well marhed ; anal area distinctly limited by a furrow, anal veins
mostly recurved. Hind wings with a distinct, enlarged, and folded anal lobe. Wings
capable of bemg folded over the abdomen, and the forward pair overlapping the hinder.
Legs non-saltatonal, the first pair som,etimes robust and raptorial. Abdomen rarely
slender generally more or less flattened ; cerci distinct ; female sometimes with a short
ovipositor.

This is an exclusively Paleozoic order, intermediate in position between the

I

SUBPHYLUM III

INSECTA

801

Palaeodictyoptera and the true cockroaclies and soothsayers (Blattoidea and Mantoidea)
of later date. The less specialised members of this order are very similar to those of
the parallel group Protorthop tera.

The Protoblattoidea are well represented in the Carboniferous and Permian of
Eiirope and North America by the following named families :

Stenoneuridae, Protophasmidae (typified by the genus Protophasma Brongn.)
(Fig. 1545), Eoblattidae, Oryctoblattinidae, Aetophlebidae, Cheliphlebidae, Eucaenidae

Fig. 1545.

Protophasma dumasi Brongn. Stephanian ;
Commentry, France. Antennae, ocelli, tarsi and
cerci restored from analogy. 4/g (after Hand-
lirsch).

Fig. 1546.

Eucaenus ovalis Scudder. Goal Measures ; Mazon
Creek, Illinois. Antennae, ocelli and tarsi recon-
structed. •i/g (after Handlirsch).

(typified by the genus Eucaenus Scudder) (Fig. 1546), Gerapompidae, Adiphlebidae,
Anthracothremmidae, and (?) Cnemidolestidae.

Order 11. BLATTOIDEA Handlirsch. (Cockroachesi).

Head deßexed, often entirely concealed from ahove hy the large shield-like pronotum ;
with orthopteroid mouth parts and long, numerously jointed antennae. Legs similar,
luith five-jointed tarsi and long coxae. Fore wings or tegmina more coriaceous than the
hinder pair, and more frequently preserved ; they are capahle of overlapping ahove the
ahdomen ; their suhcostae are more or less reduced, and the anal area is distinctly
separated hy a curved furrow. Hind wings with an enlarged, folded anal lohe.
Ahdomen short and hroad, provided with cerci, hut without visihle female genital
appendages.

This order includes the majority of Paleozoic Insects, upwards of 300 species
being known from North American strata, a still larger number from European rocks
and a few from the Carljoniferous of India. About 80 Jurassic species have been
described, half as many Tertiary, and we are acquainted with about 1200 Recent
species. In the most primitive family, the Archimylacridae, which includes more
than one-third of the American Paleozoic species, the neuration still resembles in the
main the Palaeodictyopteroid type. Highly characteristic of this family is the
condition of the long subcosta or mediastinal vein of the tegmina, which sends off a
large number of branches to the costal margin, either pectinate or arranged in groups,
but never issuing ray-like from the base of the wing.

1 Scudder, S. H., Revision of the American fossil Cockroaches. Bull. U.S. Geol. Surv., no. 124,
1895. — Schlechtendal, D. von, Über die Karbon-Insekten und Spinnen von Wettin. Leipzic, 1913.
VOL. I 3 F

802

ARTHROPODA

PHYLÜM VII

beeil derived a iiumber of more

MediaslinaL

Scapidar

fjrterriomedicai

i

Anal Veins
Internomedian

Froiu this generalised stock liave proLably -^ -, ,. n i Ar

specialised faniiL, also limited to tlie Paleozoic (Upper Productive Goal Measures
A and Permian), among which may

be mentioned tlie followiiig :

Spiloblattiiiidae, with smootli
fenestrated Spaces between the bor-
dered loiigitudiiial veins of the
tegmina ; Mylacridae, with the sub-
costal branches giveii off from a
common point of origin at the base
(Fig. 1548, C); Poroblattinidae
and Neorthroblattinidae, with a
very short siibcosta ; Mesoblatti-
nidae, with the subcosta forming
only a calloiis at the base of the
anterior border ; Pseiidomylacridae,
Dictyomylacridae, Neomylacridae,
Pteridomylacridae, Idiomylacridae,
Diechoblattinidae, and Protere-
midae.

Tertiary cockroaches are all
referable to modern families, and
are probably descended, at least for
the greater part, from the Mesoblattinidae, a family which is abundantly represented
in Jurassic rocks. Many larval forms and even ^^^'g packets of cockroaches are foiiiid

Fig. 1547.
Neuration of one of the tegmina of a Paleozoic Cockroach
Asemoblatta mazona (Scud.), from the Coal Measures of Illinois.
Tlie veins are named at the base of the tegmen, and the areas
are marked along the margin. 2/j (after Scudder).

Fi(i. 1548.

specialised

'''''"" 'Äimiyfcrid "''cTiLwf ^ ?''• ^t ^^' ^"'"*"^'' Archimylacrid. B, More highly
Arclumlyacrid. L, Mylacns, typifying the Mylacridae. Nervures are marked as in Fig. 15

fossil. Specific determinations are often difficiüt, no two individii^ls being exactly
MvidTd. ''''''"' '''' '""''^"'^ ^'^'''''' ^^'' ''^^^ ^^^ left wings of the same

SUBPHYLUM III

INSECTA

803

Illustrations of the tegiiiina of typical Paleozoic cockroaches are showii in
Figs. 1547 and 1548. Aniong North American examples may be mentioned
Adelohlafta (Fig. 1549) and Äsemoblatta (Fig. 1547) Hand-
lirscli, botli froni the Goal Measnres of Illinois ; Phylohlatta
and Bradyblatta Handlirsch, from the Perinian of West
Virginia ; Etoblattina and Spiloblattina Scudder, from the
Carboniferous and Permian respectively.

Order 12. MANTOIDEA Handlirsch.

(Soothsayers or Praying Insects).

Head exserted but deßexed, not covered by the j^fothorax,

which is elonyate and variously formed, but never disk-lihe.

Mouth parts and antennae as in the Blattoidea. First jpair

of legs largely developed, raptorial, the coxae elongate and

free; second and third pair of legs simple and similar ; the

tarsi five-jointedj without a päd between the claws ; a pair of

jointed cerci near the extremity of the body. Tegmina less

highly specialised than in the Blattoidea, subcosta well de- pio. 1549.

veloped, anal area not so distinct. Adeloblatta columbiana

(Scud.). Goal Measures ; Mazon
The earliest members of this Order are the extinct Creek, Illinois, ^k (after

Palaeomantidae from the Upper Permian of Russia, Higher

types, such as tlie extinct Haglidae and Geinitziidae, appear in the Lower and Upper

Lias respectively, of England and Germany. The latter family contains the single

genus Geinitzia Handlirsch (Fig. 1550), represented by three

species. Comparatively few Tertiary forms are known, but

in the modern fauna the Mantidae are an extensive family,

showing extreme variety in the shape of the body, and

characterised by the very remarkable front legs.

CUy

Fig. 1550.

Geinitzia schlieffeni (Gein.). Upper Lias ; Dobbertin in
Mecklenburg. 5/2 (after Handlirsch).

Fig. 1551.

Parotermes inslgnis Scudder
Miocene lake beds ; Florissant,
Colorado, -^/i.

Order 13. ISOPTBRA BruUö. (Termites or White Ants).

Social terrestrial Insects. Head not concealed, ivith orthopteroid mouth parts, and
simple antennae consisting of from nine to thirty-one joints. Wing pairs elongate and
similar, anal area reduced, and, owing to a sutiire nmr the base of the wings, the
'latter are deciduous. Legs similar, the body terminated by a pair of short cerci,
ovipositor concealed. JFingless individuals {worJcers, or sexually reduced males and
females) are polymorphous.

True Termites or White Ants appear first in the Eocene, and are represented in
Tertiary formations by about forty species. In the modern fauna upwards of 350

804

ARTHROPODA

PHYLUM VII

species are known. Parotermes Scudder (Fig. 1551) ; Eutermes Heer ; and Hodotermes
Hagen occur in the Miocene lake beds of Florissant, Colorado.

Order 14.

CORRODBNTIA Burmeister ^ (Copeognatha Enderlein).
(Book Lice).

Minute terrestrial Inseds with specialised orthopteroid mouth parts, filiform or hair-

like antennae, and two pairs of wiequal memhranous wings which are capaUe of heing

folded bachvard, loüh reduced cross-veins. Hind wings smaller,

\ / without folded anal lohe; neuration highly specialised. Legs

homonomous, with two- or three-jointed tarsi. Prothorax small ;

cerci reduced, ovipositor not prominent.

A number of species belonging in part to extinct and in
part to still living genera is known from Baltic amber (Lower
Oligocene of East Prussia), and from Sicilian amber of Upper
Miocene age. A very remarkable form with hard, cbitinous
wings, and interesting from a phylogenetic standpoint, is
Sphaeropsocus Hagen (Fig. 1552), preserved in Baltic amber.

The fifteenth order Mallophaga Nitsche, including parasitic
Bird Lice or Biting Lice, witli reduced mouth parts, and the
sixteenth order Siphunculata Meinert ( = Änoplura Enderlein), which is allied to the
Mallophaga but has suctorial mouth parts, comprise modern ectoparasitical Insects,
and are not known to be represented in the fossil state.

Fio. 1552.

Spkaeropsocxis kuenovii
Hagen. ' Oligocene amber ;
East Prussia. i^/^ (after
Hagen).

Order 17. COLEOPTERA Linnaeus. (Beetles).

Terrestrial or aquatic Insects with orthopteroid hiting mouth parts and generally
multiarticulate antennae. Four wings are present ; the upper pair shell-lihe in con-
sistency, and forming cases (elytra) which meet
together along the median dorsal line, so as to
sheathe completely the delicate memhranous hind
pair. Legs generally homonomous or the third
pair modified for swimming or leaping. Ahdo-
men sessile, without cerci or prominent ovipositor ';
the number of visible Segments more or less re-
duced.

Over 350 species of rather primitive Cole-
optera have been found in Mesozoic strata, the
largest number being from the Upper Jura.
The majority of these cannot be positively
assigned to Recent families, although it is
certain that many of these were represented as
early as the Mesozoic. On the other hand, Fio. 1553.

most of the Tertiary Coleoptera belong to exist- ^'«wedo«, homi Handl. Lithographie Stone

ing families, and comprise nearly 2300 species. ^^^^'' '^'"''•'^ ' ^^^'^^^^-^ % (after Handiirsch.)
This, however, is a small number in comparison to something like 200,000 described
species of Recent beetles.

The principal families which are represented in the fossil state are the Carabidae,
to which belongs the cursorial beetle Tauredon Handl. (Fig. 1553); Elateridae ;
Buprestidae; Dytiscidae, ete. The Strepsiptera of Kirby may be considered as a
1 £nderlein, G., Die fossilen Copeoguatheu und ihre Phylogenie. Palaeontogr., 1911. vol. Iviii.

SüBPHYLUM III

INSECTA

805

liighly specialised parasitical group of Coleoptera.

the Rhyncliopliora is represented in the Cretaceous of Greenland by tvvo genera

{Archiorhynchus Heer and GurcuUopsis HandL), and much more abundantly in the

Ku;. 1/

Fin. 1555.

Cyphon vetustus
Giebel. Purbeck ;
Vale of Wardonr,
England. 6/^ (after England
Brodie). Brodle).

Cerylonopsis striata
(Brodie). Purbeck ;
Vale of Wardour,

*^/i (after Scudder. Miocene lake beds ;
Florissant, Colorado. 5/i.

Fig. 1556.
Paltorhynchus redirostris

Fio. 1557.

Apion refrenatum Scudder.
Miocene lake beds ; Floris-
sant, Colorado. i2/j.

freshwater Miocene of Florissant, Colorado. The divisions Heteromera, Phytophaga,
Lamellicornia, Serricornia, Clavicornia and Adephaga are also fairly well represented
at the latter locality. Two English and two American species are shown in Figs.
1554-1557.

Order 18. HYMENOPTERA Linnaeus.^ (Ants, Bees, Wasps, etc.).

Terrestrial Insects ivith a free head having ivell-developed mandihles ; the first and
second maxillae are often elongated, and form in the higher groups a tubulär proboscis
adapted for sucJcing. Antennae generally long and multiarticulate. Thorax and first
abdominal Segments fused, the rest of the abdomen generally well separated by a con-
striction. Legs usually homonomous, with five-^ointed tarsi ; cerci.not distinct ; genital

Atocus defessus Scudder. Miocene lake
beds ; Florissant, Colorado. 2/^.

Fig. 1559

Pseudosirex schroeteri Genn. Litho-
graphie Stone ; Soienhofen, Bavaria. i/i
(after Oppenheim).

appendages of the female forming either a more or less pronounced terebra or a sting.
Four wings of membranous consistency and a reduced number of veins ; the front pair
larger than the hind^ which are always smaller and rarely fold up in repose. TFingless
forms frequent.

The earliest members of this order are of Jiirassic age, and it is probable that some

1 Mai/r, G., Die Ameisen des baltisclien Bernsteins,
berg, 1868. — Idem, Studien über die Radoboj-Formiciden.
vol. xvii. — Wheeler, W. M., Ants. New York, 1910.

Schriften der phys.-ökon. Ges. Königs-
Jahrb. geol. Reiclisaust. Wien, 1868,

806

ARTHROPODA

PHYLUM VII

primitive types of tlie suborder Symphyta were already in existence during the Mesozoic,
although the most primitive saw-fiies (Lydidae or Pamphilidae) are not known from
rocks older than tlie Tertiary. About 2900 Recent species of saw-flies are known,
several are preserved in Baltic amber, and fifty or more have been described from
Tertiary strata in Europe and North America. Of this number thirty-three occur
exclusively in the Miocene lake beds of Florissant. Here belong
the genera Dineura and Taxonus Dahlb.; Tenthredo Linn.; and
Atocus Scudder (Fig. 1558). Agroup of more highly specialised
Siricid-like Insects, constituting the extinct family Pseudo-
siricidae {Pseudosirex Weyenb.) (Fig. 1559) is rather abundant in
Jurassic formations of Europe, being accompanied by forerimners
of the next higher suborder, Apocrita. A great expansion of
the Order took place during tlie Cretaceous, contemporaneously
with the rise of Angiosperms.

Nearly all of the principal modern families are represented
in the Mid-Tertiary formations, as for instance true saw-flies of
the family Tenthredinidae ; Siricidae ; various subfamilies of the
parasitic Ichneumonidae ; small Cynipidae or gall-flies; Sphecidae;
May^JL^weroiigo^enel Vespidae or wasps ; Formicidae or ants (Fig. 1560); and Apidae
Baitic amber. 2/j (after Qp j^g^g Ants are exceedingly abundant in the Miocene lake
beds of Florissant, Colorado, thousands of individuals having been
obtained, and true wasps and bees are also present in large numbers. About
5000 species and sub-species of ants belonging to the modern fauna have been
described, as compared with about only 300 Tertiary species.

Fio. 15(30.
Prionomynnex longipes

t Order 19. HADENTOMOIDBA Handlirsch.

This Order, comprising a single family and genus, is evidently derived from the
Palaeodictyoptera, and shows specialisation in the reduced venation of the homonomous
wings.^ The small Carboniferous genus Hadentomum Handl. (Fig. 1561) is perhaps
transitional to the next following order.

Order 20. EMBIOIDEA Kusnezow

(Oligoneura Börner).

Terrestnal Insects with prognathous orthopteroid
mouth parts, homonomous free thoracic Segments,
apterous or with homonomous wings showing re-
duced venation. Antennae multiarticulate ; cerci
present ; first pair of legs with a spinning apparatus.

Modern Embiidae are one of the smallest
famüies of Insects, not more than sixty species
being known from all parts of the world, and
the group being an obscure one. They are small
and leeble Insects, and, as indicated by their
Wide distribution, are to be looked upon as the
mnnants of a once flourishing stock. A few
fossil remains have been found in Baltic amber and
in the Miocene lake beds of Florissant, Colorado

Fl(i. 15H1.

Hadentomum aviericannm Handl, Goal
Measnres ; Illinois, a/g (after Handlirsch).

SüBPHYLUM III

INSECTA

807

t Order 21. SYPHAROPTEROIDBA Handlirsch.

Body slender, of small size, with homonomous segments and two pairs of homonomous
lüings in ivhüh the medial and cuhital veins are greatly reduced.

Tliis Order, erected to contain the single geniis Sypharoptera Handl. (Fig. 1562),

Fig. 1562.
Sypharoptera pneuma Handl. Goal Mcasures ; Mazon Creek, Illinois, -i/i (after Handlirsch).

is probably to be regarded as a bigbly specialised lateral aberrant ofFshoot of the
Palaeodictyoptera. It is confined to the Upper Carbon iferous.

t Order 22. HAPALOPTEROIDBA Handlirsch.

Like the last, this order is probably a specialised derivative from the Palaeo-
dictyoptera, and appears to be related to primitive types of the next succeeding order.

' cu'

Fi(i. 15(53.
Hapaloptera gracUis Handl. Goal Jleasures ; Tremont, Penna. •'»/i (after Handlirsch).

In the Carboniferoiis geniis Hapaloptera Handl. (Fig. 1563), the wings have the
media and cul)itus reduced, and the sector radii well developed.

808

ARTHROPODA

PHYLUM VII

Order 23. PBRLARIA Handlirsch {Flecoptera Burmeister).

Amphibioiis Inseds with procjnathous ortJiopteroid mouth parts and long multi-
articulate antennae. Body segments very nearly Jwmonomous, legs fairly similar, and
wings with a rather specialised venation, generally showing
a few cross-veins. Hind wings often with a conspicuons
foldedanal lohe; cerci usually well-developed ; tarsi three-
jointed ; fem,ales without a prominent terehra.

Fi.i, 1564. From tlie Permian of Russia and North America"

l^idra gracilis Pictet. Lower are known a number of Insect remains wliicli appear to
PiSr^'^''^*'''^'"^''" '^^ ^'''^^''" l^eloiig to this Order, but whose precise relations are
difficult to determine. A few undoubted representatives
of tlie Order, such as Mesonemura, Mesoleuctra and Platyperla Brauer, occur in the
Middle Jura of Siberia, and several genera, including Perla Geoft'r., and Leuctra
Steph. (Fig. 1564) are preserved in Baltic amber.

t Order 24. PROTEPHBMEROIDEA Handlirsch.

Ämphibious Inseds of Palaeodidyopteran asped. Wings homonomous, with a very
primitive venation and numerous cross-veins, hut also showing intercalary veins extending
longitudinally. Thorax and ahdomen with very
nearly homonomous segments; legs similar; cerci
long.

Here is placed the solitary genus Triplosoha
Handl. { = Blanchardia Brongn.) (Fig. 1565) from
the Upper Goal Measures (Stephanian) of Com-
mentry, France. It is regarded as a connecting
link between the Palaeodictyoptera and true
Ephemeridae or may-flies belonging to the next
Order.

Order 25. PLECTOPTERA Packard

{Agnatha auct.). (May-flies).

Delicate ämphibious Insects with atrophied ortho-
pteroid mouth parts, short antennae, and four membranous wings having both intercalary
and cross-veining ; the hinder pair in all Recent and many fossil
species more or less reduced and sometimes wanting. Antennae
Short, with two basal joints and an apical needle-like segment
Ocular Organs large, often divided. Prothorax small, legs slender,
the first pair elongated, antenniform ; tarsi more or less reduced ;
cerci slender, very elongate ; last segment often filiform. Larvae
loith respiratory abdominal legs.

This Order is well represented in the Permian, Jurassic,
and Tertiary deposits of Europe and North America. The
older forms differ from existing Ephemerids in having the hind
wings equal in size to the front pair, and in having more com-
(Pictot) fower"or"" }^^^^*^^ /^'^^a^ion. Later and more highly specialised forms
cene -Baltic amber. '^3°; [^^^^ leduced venation. Nearly 300 species of may-flies are
known in the modern fauna, but these probably represent, as

Fig. 1565.

Triplosoha pulchella (Brongn.). Stephan-
ian ; Commentry, France. Vi (after
Brongniart).

Fio, 1566.
Cronicus anomalus

(after Pictet).

SUBPHYLUM III

INSECTA

809

Scudder suggested, the lingering fragments of an expiring groiip. The genera
Cronicus Eaton (Fig. 1566) ; Palingenia Burm. ; Baetis Leach ; and Ephemer a Linn.
occur in Baltic aniber, and the last-nained is found also in the Miocene lake beds of
Florissant, Colorado.

t Order 26. PROTODONATA Brongniart.

Mostly very large Insects ivith large eyes and heavy jaws ; segments of the thorax
unequal ; legs stout, homonomous. Wings suhequal, horizontally expanded and with a

Meganeura monyi Brongn.

Fig. 1567.

Stephanian (Upper Productive Goal Measures) ; Commentry (Allier), France.
i/g (after Brongniart).

finely reticulated venation ; the hinder pair somewhat dilated towards the hase, without
folds. Nodus, pterostigma, wing triangle, quadrangle, reduction of the anal vein, and
other characteristic wing structures of the true Odonata are not developed in this order.
Sector radii and media prohahly not crossed. Abdomen slender.

This group is of traiisitional character between the Palaeodictyoptera and the true
Odonata or diagon-flies. Its geological ränge is from the Goal Measures to the Trias,
and the several genera belonging to it are grouped under the families Protagrionidae,
Meganeuridae and Paralogidae. In all, less than a dozen species are known, only
three of which are North American. These last are referred to the genera Paralogus
Scudder, typified by F. aeschnoides from the Goal Measures of Ehode Island ; Palaeo-
therates Handlirsch, from the corresponding horizon in Pennsylvania ; and Tupus
Sellards, from the Permian of Kansas. The gigantic Meganeura Brongn. (Fig. 1567),
from the Upper Goal Measures (Stephanian) of Gommentry, France, measured over
75 cm. across the extended wings.

810

ARTHROPODA

PHYLUM VII

are elonyate,

reticulated, with a nodus, pterostigma,

Order 27. ODONATA Fabricius.i (Dragon-flies).

te Insects with very mohile head and large eyes, highly specialised orthopteroid

mouth parte and small, inconspicuous antennae terminating in a hnstle Thorax

Z y ^eciaUsed; legs Mar, all placed more anteriorly than the ^v^ngs. The u.ngs

equal or suhequal in size and similar m texture, membranous, finely

more or less developed triangulär areas, and

especially characterised hy

y ^ ^ r the Crossing of the anterior

hranches of the medial vein
hy the radial sector. Abdo-
men slender and elongate,
consisting of ten segments
and a pair of terminal
caliper-like processes (cerci) ;
females sometimes with a
terebra. The earlier stages
of life are aquatic ; the
mouth of the nymph develops
a peculiar structure called
the " masJc."

True Odonata appear
first in the Lower Lias, and
are present throughout the
Mesozoic and Tertiary.
Most of the Jurassic types
belong to the siiborder
Anisozygoptera, which is
represented in the modern
fauna by but a single
species. The more advanced
suborders, Zygoptera and
Anisoptera, became domi-
nant durin g the Tertiary,

o

Fia. 1568.
Vl'arsophM)ia eximia Hagen. Lithographie Stone (Kimmeridgian) ;
Eichstädt, Bavaria. An Upper Jurassic dragon-fly with long, forwardly
directed legs. 5/;j (after Handlirsch).

and comprise at the present day iipwards of 1000 and 1300 species respectively.

In the Anisozygoptera the wings are subequal and the nodal region resembles that
of the next succeeding suborder, but triangles are not formed by the cubitus and
cross-veins. Here belong the extinct families Diasatommidae ; Heterophlebiidae ;
Tarsophlebiidae (typified by the genus Tarsophlebia Hagen, Fig. 1568); Steno-
phlebiidae and Isophlebiidae.

In the Anisoptera the hind wings are considerably broader than the front pair,
the nodal region is generally situated in the middle of the costal margin and the
triangle formed by the cubitus and two cross-veins is well developed. A single
species belonging to the genus Gomphoides Selys is known from the English Lias, and
a number of allied genera, such as Nannogomphus and Mesuropetala Handl. ;
Protolindenia and Gymatophlebia (Fig. 1569) Deichmüller; Aeschnidium Westwood,
etc., occur in the Upper Jura. In Tertiary strata the families Gomphidae, Aeschnidae
aud Libellulidae are represented by about sixty species. As an example of Tertiary
Anisoptera luay be mentioned Stenogomphus carletoni Scudder, from the Eocene strata
of Roan Mountain, Colorado.

^ Kirby, W. F., Syiionymic Catalogxie of Neuroptera Odonata, with an appendix of fossil
species. London, lS90.—ÄfuttkoiosH, R. A., Catalogne of the Odonata of North America. Bull.
Puhlic Museum of Milvvaukee, 1910, vol. i.

SUBPHYLÜM III

INSECTA

811

In tlie suborder Zygoptera tlie wings are eqiial, no triangle is formed by the
cubitus and cross-veins, and tlie nodal region is situated very near tlie base of the
wings. Half a dozen species are known from tlie Upper Jura, and a considerably
larger number, mostly belonging to the faiiüly Agrionidae, occur in the Oligocene and
Miocene of Europe and North America. Dysagrion Scndder is represented by a few
species in the Green River Eocene of Wyoming, and several species closely related

Fig. 1569.

Cymaiophlebia longialata (Germar),
Lithographie Stone ; yolenhofen,
Bavaria. ^/s-

Argia aliena (Scudder). Miocene lake beds ; Florissant,
Colorado, '^/i-

to living forms are known from the Miocene lake beds of Florissant, Colorado.
Here also occurs Ärgia aliena (Send.) (Fig. 1570), together with representatives of
several related forms, such as Melanagrion Cock. ; Lithagrion Send. ; and Hesperagrion
Calvert. The most interesting dragon-fly from this locality, however, is Phenacolestes
Cockerell, which has been raade the subject of special investigation by R P. Calvert
{Proc. Acad. Nat. Sei. Philad., May 1913).

Order 28. MEGALOPTBRA Latreille. (Alder-flies).

Head with prognathous orthopteroid mouth parts and multiarticulate antennae.
Four membranous wings of moderate size, meeting in repose over the hack at an
angle ; the hinder pair slightly the smaller ; anal area plicate. Venation of a some-
what archaic type, the nervures and transverse veinlets heing moderately numerous,
and forming irregularly disposed cells. Segments of the thorax nearly equal, legs
homo7iomous, with five - jointed tarsi ; cerci usually
reduced, ovipositor not prominent. Larvae of aquatic
hahits, possessed of hranchiae and legs, hut no spiracles,
and with mandibles formed for hiting, armed with strong
teeth.

Fi(». 1Ö71.

This group has a long geological history, extending (,^„„^.,^,, j^^^m Pictet. Lower
from the Jjower Trias onward to the present day, and is oligocene ; Baltic amber. ■*/.! (after
probably descended from Palaeodictyopteroid ancestors. ^^^^^^)-

The genera Ghauliodites Heer, and Triadosialis Handlirsch occur in the Lower Trias
(Bunter) of Germauy, and an undoubted larval form, Mormolucoides articulatiis
Hitchcock, is not uncommon in the Upper Trias of Turner's Falls, Massachusetts.
In this latter a head, or thorax, of tliree segments, and an abdomen of nine segmeiits

812

ARTHROPODA

are recognisable. Chauliodes Latreille (Fig. 1571), an interesting form,
in lialtic ainber of Lower Oligocene age.

PHYLUM VII

preserved

Order 29. RAPHIDIOIDEA Handlirsch. (Snake-flies).

Terrestrial Insects with prognathous orthopteroid mouth parts and long, multi-
articulate antennae. Head large, ahdomen slender, prothorax greatly prolonged and
very mobile. Wings similar, memhranous, of nearly equal size ; venation more highly
specialised than in the Megaloptera, with a prominent pterostigma ; anal veins forming
several irregulär cells, of moderate size, and never fan-shaped in arrangement. Legs
similar, with five-jointed tarsi ; no cerci ; females with an elongate exserted ovipositor.
Larvae of terrestrial hahits, without abdominal legs and furnished with mouth parts
adapted for biting.

Only two Recent genera are known, Eaphidia Burm., and Inocellia Schneid.,
comprising in the aggregate about forty species. The former of these occurs fossil in
Baltic amber of Lower Oligocene age, and both genera are represented in the Miocene
lake beds of Florissant, Colorado, by a few species, Megaraphidia elegans Cock. also
occurs at the last-named locality. It is to be inferred, however, that the group is
of pre-Tertiary origin, inasmuch as the modern genera are peculiar to the Palearctic
and Nearctic regions.

Order 30. NBUROPTBRA Linnaeus. (Lacewing-flies, Ant-lions, etc.).

Usually slender, often very small Insects of terrestrial habits, with orthopteroid
mouth parts and generally long and multiarticulate antennae. Wings membranous,
subequal in size, with much reticidation, and longitudinal veins giving off numerous
branches towards the margin, some of them distally forked ; anal area not defined, with
few irregulär veins; pterostigma seldom developed. Legs similar, lüith five-jointed
tarsi, front pair sometimes raptorial ; abdomen without cerci or terebra. Larvae either
aquatic and provided with respiratory abdominal legs, or terrestrial ; in both cases with
mandibles and maxillae co-adapted toform spear-lihe organs that are suctorial in function.

In the emended sense this order includes only a limited number of species, of
which about 1300 are Recent, less than 30 are Cenozoic, and a small number are

Fio. 1572.
Iirodromus Handl.

Prohn,.,: _ , _

pobb(;rUu in M.'cklenbiirK
Handlirsch)

Upper Lias ;
Vi (reconstructed by

Fig. 1573.

Brongniartiella inconditissima Handl.
Lithographie Stone ; Solenhofen, Bavaria.
2/3 (after Handlirsch).

andT;rt. Lw t ^ ' r':1 ^f"" Palaeodictyopteroid ancestors. The oldest
.»est pnm>tive fa.ndy, that of the Prohemerobiidae, is represented in the Lias

I

SUBPHYLUM III

INSECTA

813

and Upper Jura by twenty-two species, some of which attain considerable size. The
genera Prohemerobius (Fig. 1572) and Archegetes Handl. ; and Brongniartiella Meunier
(Fig. 1573) are examples.

Otlier families of Neiiropterous Insects which are restricted to the Mesozoic, such
as the Epigambridae, Solenoptilidae, Nymphitidae, Kalligrammidae and Mesochryso-
pidae, show a certain approximation to Tertiary and modern forms. Members of the
now flourishing Osniylidae, Sisyridae, Nymphidae, Hemerobiidae, Coniopterygidae,
Chrysopidae, Nemopteridae and Myrmeleonidae have been recorded from Tertiary
rocks. The genera Osmylus Latr. ; Osmy-

lidia Cockerell ; Bothromicromus, Tribo- ^,^^^^^^__ / \/\

chrysa and Palaeochrysa Scudder are <^^^^^^^^^s^M^^
represented in the North American Mio-
cene. The last-named genus is represented
by four species at the Florissant locality,
and Tribochrysa by one. A single species
each of Polystoechotes Burm., and Halter
Eambur, has also been described from the
same locality.

t Order 31. MBGASBCOPTERA
Brongniart.

Insects lüith slender body, the segments
of which are very siviilar, long antennae
and cerci, and homonomous legs. Wing
pairs equal, horizontally expanded, venation
specialised in that there is a reduced numher
of branches and cross-veins.

This is an exclusively Paleozoic group,

derived from the Palaeodictyoptera, and

probably the progenitor of the next suc- Fig. 1574.

ceeding order. Here belong the families Mischoptera woodtmrdi Brongn. Stephanian (Upper
-rv- 1, + -1 /-^ ;i 1 'j-i n^^ Goal Measures) ; Commentry, France. Ocelli and

Diaphonopteridae, Corydaloididae, Cam- tarsi restored. v, (after Handiirsch).

pylopteridae, Mischopteridae (typified by

the genus Mischoptera Brongn.) (Fig. 1574), Raphidiopsidae and Prochoropteridae.

Order 32. PANORPATAB Brauer (Mecaptera auct.). (Scorpion-flies).

Terrestrial Insects with orthopteroid mouth parts and long, multiarticulate antennae.
Prothorax smaller than the remaining segments; legs similar^ lüith five-jointed tarsi ;

abdomen slender, with short cerci and

r „„ ^^^ .r== : large genital appendages in the male.

Wings equal, membranous, without en-
larged anal lobe, and with a limited
number of secondary branches and cross-
veins.
CH

This Order, which is now in a state
of decline, is abundantly represented
in the Lias and Upper Jura of Europe.
Most of the fossil species belong to the
family Orthophlebiidae, of which the genera Orthophlebia Westw., and Neorthophlebia
Handl. (Fig. 1575) are examples. True Panorpidae and Bittacidae occur in the

Fia. 1575.

Neorthophlebia maculipennis Handl. Upper Lias ; Dob-
bertin in Mecklenburg. 5/j (after Handlirsch).

814

ARTHßOPODA

PHi'LUM VII

Tertiary of Europe and North America. Representatives of tlie families Meropidae
and t Eobanksiidae, the latter typified by Eohanksia Cockerell, are also known from
the Florissant lake beds. About 100 Recent species of Scorpion-flies are known.

Order 33. TRICHOPTERA Kirby {Phryganoidea Stephens).

Moderate-sized, water-frequenting Inseds with long, multiarticulate antennae and
reduced or obsolete mandibles, but ivell-developed maxülae. Wings memhranous, unequal,
more or less clothed with hair, nervures dividing at very acute angles ; the front pair
ivith longüudinal veins moderately branched, very few cross-veins, specialised anal area,

and often a pterostigma ; the hind pair generally
with an enlarged and plicated anal lobe. Pro-
thorax small, legs similar, with five-jointed tarsi
and prominent spiirs ; cerci reduced, terebra
loanting. Larvae aquatic, with well - developed
mandibles, and as a rule providing themselves with
cases or tubes formed of extraneous matter.

Fig. 1576. Sonie half - dozen genera coniprising fifteen

Necrotaulius inte-nnedhis Handi. Upper gpecies of primitive Caddis-flies are known from

Lias; Dobbeitin in Mecklenburg, »/i (alter \ . ^ - r ^i v i • .. ^v

Handlirsch). Mesozoic rocks, most Ol them belongmg to the

extinct family Necrotauliidae. Necrotaulius
Handl. (Fig. 1576); and Trichopteridium Geinitz are examples from the Upper Lias
of Germany. About 1400 Recent and 200 Tertiary species have been recorded,
of which 24 occur in the Miocene lake beds of Florissant, Colorado. At this
locality remains in the imago State are extremely abundant, and many such remains
have been found in Europe. On the other band, the so-called indusial limestone
of Auvergne, which is from two to three metres thick over a wide area, is largely
composed of the cases of Phryganoid larvae. Similar masses of tubes occur also in
the Green River Eocene of Wyoming.

Order 34. LBPIDOPTERA Linnaeus. (Butterflies and Moths).

Terrestrial Insects with suctorial mouth parts, in which the mandibles are ahmst
invariably reduced and the first maxillae are either small -or, in higher forms, frolonged
in a spirally coiled proboscis ; antennae multi-
articulate and of various shapes. Fore and hind
itnngs unequal in size, membranous and densely
covered with scales ; the hind -pair shorter and
usually without enlarged anal area. Longitu-
dinal veins giving off but a limited number of
straight branches, and with very few cross-veins.

Fid. 1577.

J ■knvj, ad', edles dornest Öppenli. Middle Jura

öiberia. -^/s (after Oppenheim).

Fig.

Eocicada lameeri Handl. Lithographie
8tone (Upper Jura) ; öoleuhofen, Bavaria.
Au Upper Jurassic Lepidopterid, the antennae
and ocelli restored. . 4/y (after Handlirseh). - -

SUBPHYLUM III

INSECTA

15

Thorax much abbreviated, legs similar, ivith spiirs ; no cerci or terebra.
mandibles, thoracic and abdominal legs.

Larvae with

The earliest uiidoubted traces of Lepidoptera aie fouiid in Jurassic strata of
England, Spain, Bavaria and Siberia, and comprise a nnniber of genera belonging to
tlie faniily Palaeontinidae. Phragmatoe-
cites (Fig. 1577), Eocicada (Fig. 1578), and
Prolystra Oppenheim are exaniples, these
forms being somewhat distantly allied to
the non-suctorial Limacodidäe of our own
day. Several modern families make their
appearance in the Tertiary, bnt are repre-
sented by relatively few species. The
total nnmber of Tertiary species is not
over 85, as against some 60,000 Eecent
butterflies and nioths. Among North
American exaniples may be mentioned the
foUowing from the Miocene lake beds of
Florissant, Colorado, all described by
Scudder : Prodryas persephone (Fig. 1579),
Barbarothea ßorissanti (Fig. 1580), Jwpiteria charon, Lithodryas styx, Nymphalites
obscurus, Prolibythea vagabunda, Psecadia mortuella, and Stolopsyche libytheoides.
From the same locality Gockerell has described Ghlorippe wilmattae and some other
species, including a well-preserved larval form known as Phylledestes vorax.

Fig. 1579.

Prodryas persephone Scudder. Miocene lake beds ;
Florissant, Colorado, i/j (after Scudder).

Order 35. DIPTERA Linnaeus. (Flies).

Terrestrial or amphibious Insects with highly specialised suctorial mouth parts.
Antennae either long and multiarticulate, or consisting of a limited number of similar
or dissimilar joints. Only the fore wings are prominent ; these are usually well developed,

membranous, highly specialised, narroiv, with

/ ^ few cross - veins, and longitudinal veins

1^^ sparingly branched. Hind wings always

^^^^Mp^^^^^E reduced to clubbed ßlaments, the so-called

Fig. 1580.

Bdi-barothea florismnti Scudder.
Miocene lake beds; Florissant, Colo-
rado. Vi (after Scudder).

oTCU

Fio. 1581.

Architipula seehachiana Handl. Upper
Lias ; Dobbertin in Mecklenburg. 6/j (after
Ilandlirsch).

" halteres." Thorax much abbreviated, legs generally homonomous, with five-jointed tarsi ;
abdomen without terebra or visible cerci.

Upwards of 44,000 Recent and 1550 Tertiary species are known, 125 of the
latter being North American. The earliest Flies are found in the Upper Lias, and
comprise about 30 species, nearly all of which belong to the suborder Orthorrapha
of Brauer. They are grouped in the following named families : Protorhyphidae,
Mycetophylidae, Bibionidae, Psychodidae, Eoptychopteridae, Architipulidae (typified
by the genus Architipula Handl.) (Fig. 1581), Tipulidae and RhypÖidae. . In the

816

ARTHROPODA

PHYLÜM VII

Tertiarv of Nortli America tlie same suborder is abundantly represented, especially
in tho Miocene lakc beds of Colorado, wliere thousands of individuals and hundreds
of species have been found. The suborder Cyclorrapha is likewise well represented

I

i

Funthetria falcatula Handl. Oligocene ;
Britisli Columbia, ^/i-

Fig. 1582.

Necromyza pedata Scudder. Miocene ; Oeiiingen,
Baden, i^/j (after Scudder).

Fig. 1585.

Chironomus meyeri Heer. Miocene ; Oeningen,
Baden. 6/i (after Heer).

Bibw sticheli Handl. 9 Miocene ; Gotschee, Carlnthia
ö/i (after Handlirsch).

Fig. 1586.

Falemholus florigerus Scudder.
Miocene lake beds ; Florissant,
Colorado. 2/^ (after Scudder).

in the Miocene of Colorado, wliere numerous species occur, also in British Columbia,
and in the Green River Eocene of Wyoming. In the European Tertiary nearly all
of the modern families are represented, a few examples of which are shown in the
accompanyiii,!^ Fius. 1582-86. The most interesting genus from the Florissant locality
18 Glossina, üi^ t^ctse tly, two species of which occur here but not elsewhere in the
Western woiid. ^

/•

4

SUHPHYLUM III

INSECTA

817

Order 36. SUCTORIA De Geer (Siphonaptera, Äphaniptem auct.). (Fleas).

Small^ wingless, semijmrasüic Insects with slender body^ suctorial mouth parts, short,
cluhbed antennae, and legs adapted for
spriuging ; tarsi ßve-jointed. \,

Tlie sole representative of tliis order in
the fossil State is a species of Palaeopsylla
Wagn. (Fig. 1587) preserved in Baltic
amber of Lower Oligocene age. It is
interesting to note tliat Recent species of
this genus are restricted to central Eiirope,
and still inhabit the sanie region as in
mid-Tertiary tiraes.

t Order 37. PROTOHBMIPTBRA
Handlirsch.

Fig. 1587.

Palaeopsylla klebsiana Dampf. Lower Oligocene ;
lialtic amber. 36/j (after Dampf.),

Head small with projecting suctorial

mouth parts differing from the heak of true Hemiptera only in that the palpi of the

second maxilla are not fused in the middle line. Body stout, with a broad pronotum,

Wings horizontally expanded, the venation primitive, resembling that of the Palaeo-

dictyoptera, and ivith numerous cross-veins ; the anal area not separated off by an anal

. furrow so as to form a distinct region or " clavus." Front

N^. ^ A legs long and probably raptorial.

The sole representative of this group so far as
known is Eugereon Dohrn (Fig. 1588), the genotype
of which is the highly interesting E. boeckingi
Dohrn from the Lower Permian of Oldenburg.
It is a generalised form, and may be regarded as
a connecting link between the Palaeodictyop-
tera on the one band, and the Homoptera and
Hemiptera on the other.

Fio. 15S8.

Eiujcreon boeckingi Dohrn. Permian ; Birkenfeld in Oldenburg.
3/4 (after Dohrn).

t Order 38.

PALAEOHBMIPTBRA

Handlirsch.

Ä provisional group, estab-
lished for the reception of cer-
tain fragmentary remains,
mostly wings, which combine
in themselves the characters of
the Homoptera and Hemiptera.
The " clavus " or anal region
is separated by a straight ridge,
the corium and membrane are
not distinctly separated.

Here are placed the families Prosbolidae (typified by the genus Prosbole Handl.)
VOL. I 3 G

818

ARTHROPODA

THYLUM VII

(Ki, ,589), and Scytinoptcidae, .oü. .stncted ^ ^^^'^ ^^'''-^''-

Order 39. HEMIPTBRA
Linnaeus (Heferoptera
auct.). (Bugs).

Terrestrial or aquatic Insects
with sudorial mouth parts con-
sisting of a mobile prognathous
heak {the fused palpi of the
second maxiUae) which contains
the setiform mandihles and first
maxiUae. Äntennae never multi-
articidate and exhibiting a variety of form, often concealed in aquatic forms. Fore
wings covering the ahdomen, their apical areas mostly memhranous and overlapping,^
their basal moieties generally coriaceous, luith a definitely limited anal area or " clavus."
Hind wings concealed and loith a somewhat reduced venation.
and depressed ; prothorax

Fig. 1589.

Proshole hirsuta Handl. Upper Permian ; Tichagori, Russia.

2/i (after Handlirsch).

J^^^.

Body m,ore or less siout

large ; legs similar, with few
tarsal joints, and variously
adapted as for raptorial,
saltatorial, fossorial, or
natatory functions ; cerci
wanting.

Two main divisiojis are
recognised, Gymnocerata or
terrestrial Bugs, and Crypto-
cerata or aquatic Bugs.
Both groups are represented
in the Mesozoic, but many
of tliese ancient types cannot
be included within the limits
usually assigned to modern
families. During the' Ter-
tiary, on the other hand, no forms existed which differ markedly from Recent types,
and nearly all of the modern families are here represented. The following named
families are among the most important of those occurring in the Mesozoic :
t Archegocimicidae (typified by Archegocimex) (Fig. 1590), f Progonociniicidae,
t Eocimicidae, f Eonabidae, f Hadrocoridae, f Cuneocoridae, Proboscanionidae,
t Apopnidae, f Pachymeridiidae, f Prötocoridae, f Sisyrocoridae, f Diatillidae,
Coreidae, Nepidae, Belostomidae (typified by the genus Mesobelostomum Haase) (Fig.
1591), Naucoridae, Notonectidae, and Corisidae.

Fig. 1590.

Archegocimex geinitzi
Handl. Upper Lias ; Dob-
bertin in Mecklenburg.
6/i (after Handlirsch).

Fig. 1591.

Mesobelostomum deperditum
Upper Jura ; Solenhofen
(after Deichmüller).

Germar.
Bavaria. '^/-^

Order 40. HOMOPTERA Leach. (Plant-lice, Wax-bugs,
Harvest-flies, etc.).

Exclusively terrestrial Insects with hypognathous suctorial mouth parts having the
mme conformation as in the Hemiptera. Äntennae usually with heteronomous segments,
often Short and bristle-like. Wings as a rule not overlapping and disposed in a more
tectiform attitude, rarely coriaceous ; " clavus " in most forms distinctly bounded. Hind
wings generally smaller than the forward pair, sometimes with an enlarged anal lobe.

SUBPHYLUM III

INSECTA

819

Prothorax relatively large ; legs simüar, or the third imir adapted for springing ;
ahdomen without cerci ; females often with a terebra.

This group is divided iiito five siiborders, tlie most primitive of wliicli is tlie
Auchenorliyncha, ranging froni the Lias onward. It is represented in Mesozoic rocks
by 50 species, in the Teitiaiy by about 200, and in the modern fauna by upwards
of 10,000. Most of the Jurassic species belong to the families Fulgoridae (typified
by Fulgoridium. Handl.) (Fig. 1592) ; f Procercopidae (typified by Procercopis Handl.)

Fig. 1592

Fidijoridium pallidum Handl. Upper
Lias ; Dobbertln in Mecklenburg, ö/j
(after Handlirscli).

Fig. 1593.

Prooercopis alutacea Handl. Upper Lias ; Dobbertin in

Mecklenburg, ^/j (after Handlirscli).

(Fig. 1593); and Jassidae. One species of Cicadidae is reported from the Cretaceous,
and a dozen froiii Tertiary strata. The Fulgoridae, Cercopidae and Jassidae are
represented by numerous species in the Tertiary, and are now fiourishing families.
The suborders Psylloidea and Aphidoidea have a continiious ränge from the Jura
onward, and the division of Aleurodoidea is Tertiary and Kecent, but is represented
by relatively few species. Plant-lice (Aphididae) and Harvest-flies (Cercopidae and
Cicadidae) occur frequently in the Tertiaries of Utah, Wyoming, Colorado and British
Columbia.

Olass 2. APTERYGOGENEA Brauer (Apiera Linnaeus).i

Piirely wingless Insects. Ahdomen with from six to twelve segments. No meta-
morphosis.

Order 1. THYSANURA LatreiUe.

Small Apterygote Insects with orthopteroid, free mouth parts and simple midtiarticu-
late antennae. Compound eyes present ; head with hroad basis joined to thorax^ which
consists of three divisions ; tergite usually well developed, pleurite and sternite small;
prothorax as large as, or larger than the mesothorax. Abdomen consisting of ten well-
developed segments and bearing distinct cerci, a ter-
minal filum, and reduced styliform abdominal legs on
most of the segments.

The families belonging to this group, Machilidae Fig. 1594.

and Lepismidae, are ectotrophous — that is, the mouth MachjHs seticornis (Koch and

^ i-i-iiii ^ • Berendt). Lower Oligocene ; Baltic

parts are not buried 111 the head, bat are arranged m amber. a/j (after Koch and Berendt).

the fashion usual among mandibulate Insects. Both

families are represented in Baltic amber of Lower Oligocene age, the genus Machilis

Latr. (Fig. 1594) being specially abundant. Lepisma Linn. is represented by several

European and one North American species in the Oligocene.

^ Ol/ers, W. M., Die Ur-Insekten (Thysanura inid Collenibola im Bernstein). Scliriften der
physikal.-ökou. Ges. Königsberg, 1907, vol. xlviii. '

820

ARTHROPODA phylum vii

Order 2. CAMPODBOIDEA Handlirsch {Archinseda Haeckel).

Siiudl Ajilerinii'ir i nfnlvitphovs hisects {mouih parts or trophi reduced and huried in
fite had) vith f>'elilij~(h'n loi^'d njrt; and long, simple, midtiarticulate antennae. Bodtj
Segments very nearly eqttal ; ten well-developed abdominal segments, most of them with
reduced styliform legs ; cerci elongate or chelate.

The so-called abdominal legs in tliis gronp and in the Thysanura are appendages
^vlli(•ll help to support tlie abdoraen, and serve also as tactile organs. They are
ciillcil by Grassi false legs or '' Pseiidoza7npe" The Recent genus Campodea Westwood
occurs also in Baltic aniber of LoAver Oligocene age.

Order 3. COLLEMBOLA Lubbock. (Spring-tails).

Trophi reduced and huried in the head, eyes feehly developed, antennae sometimes
unequally segmented. Thorax with very unequal segments hut with homonomous legs.
Abdomen consisting of not more than six segments, the first of ivhich is furnished with a
ventral tuhe or papilla, and modified legs forming a springing apparatus being present
posteriorly.

About 450 Recent species of Spring-tails are known, and 70 have been recorded
fi'oni Baltic amber of Lower Oligocene age. The crustacean characters which we
find to-day in the CoUembola, the Thysanura, and tlie Ephemerida, are, as pointed
out by G. H, Carpenter, without doubt inherited survivals, indicating a true relation-
ship between the two subphyla of Branchiata and Insecta.

Order 4. PROTURA Silvestri (Myrientoma Berlese).
Minute subterraneous Insects without antennae and eyes.
This Order is without known representatives in the fossil State.

Geological Range and Distribution of Insecta.

It is estimated that about 1000 Paleozoic, as many Mesozoic, and upwards of
8000 Cenozoic Insects have been described by different authors. The total is,
however, a mere fragment of the insect fauna of past periods, and very small in
comparison with the half million species now in existence.

The earliest fossil Insects which have been definitely recognised are members of
the Palaeodictyoptera. Their first appearance in Europe is at the base of the Upper
Productive Goal Measures (Ouralien or Stephanien superienre of Commentry, France,
and the corresponding 'umteres Obercarbon" of German geologists). From the
Upper Goal Measures of France, Germany, Belgium, Bohemia, and other localities in
l^urope, and Irom the Lower Productive Goal Measures (Kanawha and Alleglieny
ormations) of Pennsylvania, Illinois and elsewhere in the United States and Canada
has been obtamed a large number of highly interesting types.i Other- representatives

renilinrwil^fnf ""'1^'''''^ ""! ^^- '^°^"' ^^^- B^^ii^wick, which has yielded a number of insect
PaeobotaiTv tnn?rT^ regarded as of Devonian age, but is now assigned on the evidence of
(livisbro7t ./pn^^^ ^"^^ ^'"^^^^^' corresponding to the Kanawha Group (upper

pZZI .^.It f '^/n^P^^'^^^ ''''''^ '''''S, described by Moberg under the !>ame of
Anot r^oub ful f; "^ the Graptohte beds of Sweden is probably not of Arthropod nature.
M^^Surit ofr.,^^^^^^^^ '\' '°-'""^^ ^'^^^^oUattina douvül J of Brongniartf from the
S f^e l^^^^^^ T Hl erpreted by Agnus as part of the pleural lobe of a Trilobite.

irMiiS^sTlns..?. , . '\\"'^n' ?«^""ianrocksof the south-east of Ireland, but no indubitable

fouu.l .t Fnrnl.v r- i'.'"', <-=irboniferous have been as yet forthcoming. Tlie insect remains

f-i,. th.. Fkr ia.it 1 p'l ',"■' ""'"^ ^^'°"^^* *" ^'' ^f ^''"^'^'' ^««tead of Triassic age. Those
fonue.lv '^' ^''' "°'' ^■^*"^"-«*^ to the Miocene, instead of to the Oligocene, ""

11 e, f^s^^M

4

suBPHYLüM III INSECTA 821

of various primitive groiips are known froni tlie Perniiaii of Riissia, Germany, West
Virginia, Kansas and Colorado, so that on tlie wliole we are fairly well acquainted
with these heterometabolic ancestors of modern Orders. Unfortunately, liowever, very
little evidence is fortlicoming from the Trias, during whicli era the transition from
tlie lieterometabolic to the holometabolic stage probably took place. Nevertheless,
a few fossil remains are known from tlie Trias of Sweden, Germany, Austria,
Switzerland and China. Niimerous tracks of supposed Insects, and also what are
believed to be the aquatic larvae of an alder-fly {Mormolucoides articulatus Hitchcock),
occiir in the dark shales of the Connecticnt Valley Trias.

A fairly rieh insect fauna has Ijeen discovered in the Lias of Schambelen in
Aargau, Switzerland, Dobbertin in Mecklenburg, Brunswick, Weyer in Austria, and
several localities in Somerset, Gloucestershire and Yorkshire, England. A few
remains are preserved in the Stonesfield Slate near Oxford, England, and in strata
of the same age in Siberia ; and a considerable number of species occurs in the Purbeck
of the southwestern counties of England. Eichest of all, however, is the Upper
Jurassic insect fauna, especially that which is found in the Lithographie Stoiie
(Kimmeridgian) of Bavaria. Contrariwise, the ^Cretacegus is markedly deficient in
Information respecting this group of invertebrates.

Tertiary Sediments have yielded an enormous quantity of well-preserved insect
remains. Aniong the more important localities that have furnished material of this
nature, mostly of mid-Tertiary age, may be mentioned the freshwater deposits of
Florissant, Colorado, Aix-en- Provence, Oeningen on Lake Constance in Baden, Radoboj
in Croatia, Eott (Upper Oligocene lignite) near Bonn on the Rhine, Brunnstatt in
Alsace, Sieblos in Bavaria, Bilin in Bohemia and Gabbro in Tuscany ; also the
Oligocene strata at Quesnel in British Columbia, and the Green River Eocene of
Wyoming, western Colorado and eastern Utah. But by far the largest and itiost
varied assemblage of Tertiary insect remains is obtained from Oligocene amber in
East Prussia.

Finally, in the Pleistocene, the interglacial clays of Switzerland, Germany and
Ontario, the peats of northern France and England, the ozokerite of Galicia, and the
lignites of Hösbach in Bavaria, deserve mention as localities which .have furnished
fossil insect remains. In the accompanyiiig table is indicated the geological ränge of
the different orders of Insects.

[The preceding chapter on Insecta has been prepared especially for the present work by
Professor Anton Handlirscli, of the Imperial Museum of Natural History at Vienna. A
few minor eniendations have been suggested by Dr. W. J. Holland, Director of the Carnegie
Museum at Pittsburgh, and otliers by Professor T. D. A. Cockerell, of the University of
Colorado. — Editor,]

822

ARTHROPODA

PHYLUM VII

Taiu.k showing THE Vertical Range op Fossil Insects.

Orders.

Class I. Pterygogenea

1. Palaeodictyoptera

2. Mixotermitoidea

3. Reculoidea

4. Protortlioptera

5. Orthoptera

6. Phasmoidea

7. Dermaptera

8. Diploglossata

9. Thysanoptera

10. Protoblattoidea

11. Blattoidea

12. Mantoidea

13. Isoptera .

14. Corrodentia

15. Mallopliaga

16. Siphunciüata

17. Coleoptera

18. Hymenoptera

19. Hadentomoidea

20. Embioidea

21. Sypliaropteroidea

22. Hapalopteroidea

23. Perlaria .

24. Protepliemeroidea

25. Plectoptera

26. Protodonata .

27. Odonata .

28. Megaloptera .

29. Raphidioidea .

30. Neuroptera

31. Megasecoptera

32. Panorpatae

33. Trichoptera

34. Lepidoptera

35. Diptera .

36. Suctoria .

37. Protohemii)tera

38. Palaeoheniiptera

39. Heniiptera

40. Homoptera

Class II. Apterygogenea (Aptera)

1. Tliysanura

2. Canipodeoidoa .

3. CoUcmbola

4. Protura ....

^S

I

INDEX

[Names of genera and subgenera regarded as synonyms are priuted in italics, all otliers in Roman. ]

Abacocrinus, 194
Ähatus, 296
Ablacomya, 449
Abra, 495
Abracrinus, 194
Ahrotocrinns, 222
Acacocrinus, 194
Acambona, 414
Acanthactinella, 62
Acantherpestes, 793
Acanthina, 558
Acanthinites, 648
Acanthocaris, 751
Acanthoceras, 669
Acanthocites, 513
Acanthoclaclia, 342
Acanthoclema, 344
Acanthoclymenia, 628
Acanthocrinus, 188
Acanthocyathus, 95
Acanthocystites, 150
Acanthodictya, 61
Acantholithus, 112
Acanthonaiitilus, 606
Acanthopleura, 513
Acanthospongia, 62
Acanthotelson, 756
Acanthoteiithis, 683
Acanthothyris, 400
Acasta, 746
Acaste, 726
Acavvis, 576
Acentrotremites, 172
Acervularia, 86
Aceste, 297
Acestra, 62
Acharax, 438
Achradocrinns, 219
Achradocystites, 151
Achrochordociinus, 232
Acila, 440
Acdeistoceras, 611
Aclisina, 538
Acloeodictya, 61
Acmaea, 520
Acritis, 371 f
Acrochordiceras, 640
Acrocrinus, 201
Acroculia, 541
Acrogenia, 346
Acroidaris, 275
Aoropora, 107
Acrosalenia, 279
Acrothele, 376
Acrothyra, 376
Acrotreta, 376
Acrura, 256
Actaeonella, 566
Actaeoriina, 566
Acteocine, 568
Acteon, 565
Actinacis, 107
Actinocamax, 682

Actinoceramus, 447
Actinoceras, 609
Actinoconchus, 418
Actinocrinus, 197
Actinodesina, 444
Actinodiclya, 61
Actinodonta, 455
Äctinomya, 468
Actinopora, 322
Actinopteria, 448
Actinosepia, 688
Actinostonia, 341
Actinostreon, 450
Actinostroma, 122
Actinotaxia, 326
Adacna, 490
Adelactaeon, 566
Adehtstrea, 101
Adeloblatta, 803
Adelopthalmus, 783
Adeonella, 339
Adolfia, 410
Adranaria, 440
Aechmina, 738
Aeger, 761
Aegiope 405
Aeglina, 721
Aegoceras, 656
Aeolopneustes, 282
Aeropsis, 297
Aeschnidium, 810
Aesiocrinus, 225
Aesiocystis, 159
Aetea, 348
Aethocystis, 157
Aetostreon, 450
Aganides, 631
Agaricia, 103
Agaricocrinus, 196
Agassiceras, 657
Agassizia, 296
Agassizocriniis, 224
Agathelia, 95
Agathemera, 800
Agabhiceras, 641
Agelacrinus, 159, 156
Agina, 499
Aglaspis, 776
Aglithodictya, 61
Agnesia, 524
Agnostus, 710
Agoniabites, 630
Agrawlos, 717
Agria, 482
Agriocrinus, 199
Agrion, 811
Aguthasia, 404
Aipoceras, 606
Akera, 567
Alarla, 550
Albertella, 717
Alecto, 319
Alectrion, 556

Alectryonia, 450
Alexia, 574
Alipes, 551
AUagecrinus, 209
Allionia, 237
Allocrinus, 191
Allocystites, 155
AUodesma, 470
AUomorphina, 29
AUonema, 318
AUonychia, 445
Allopagus, 469, 489
AUoprosallocrinus, 195
Allorhynchus, 398
AUorisma, 465
Alocolytoceras, 652
Aluta, 735
Alveolina, 39
Alveolites, 114
Alveopora, 107
Amaltheus, 659
Amauropsis, 543
Ainbites, 633
Amblypneustes, 282
Amblypygus, 289
Amblysiphonella, 71
Ambocoelia, 412
Ambonycliia, 445
Amiella, 786
Amicula, 513
Amiskwia, 135
Amita, 444
Ammobaculites, 26
Ammodiscus, 25
Ammolagena, 25
Amnicola, 545
Amnigenia, 451
Aviorphocystis, 152
Amperleya, 530
Ampheristocrinus, 218
Amphiastraea, 98
Amphibola, 573
Amphiceras, 657
Amphichaena, 495
Amphiclina, 419
Amphiciinodonta, 419
Amphicoelia, 445
Aniphicrinus, 205
Amphidesma, 495
Amphidonta, 450
Amphidromus, 576
Aiiiphigenia, 400
Amphilichas, 721
Amphion, 725
Amphipeltis, 758
Amphipora, 124
Amphispongia, 62
Amphistegina, 34
Amphistrophia, 385
Amphithelion, 59
Amphitomella, 418
Amphiura, 256
Amphora, 197

Amphoracrinus, 197
Amplexopora, 336
Amplexus, 83
Ampulla, 561
Ampullina, 543
Ampyx, 712
Amusium, 458
Amygdalocystites, 151
Amynilispes, 793
Anabacia, 103
Anabaia, 417
Anadara, 443
Anagyrnnites, 645
Ananchytes, 292
Anapella, 498
Anaphragma, 339
Anarcestes, 629
Anasirenites, 648
Anaspides, 755
Anastomopora, 342
Anasbrophia, 394
Anathyris, 417
Anatimya, 466
Anatina, 466
Anabinella, 498
Anatomites, 639
Anazyga, 408
Anchura, 551
Ancilla, 562
Ancillaria, 562
Ancistroceras, 601
Ancistrocrania, 379
Ancryopyge, 723
Anculosa, 548
Ancyloceras, 670
Ancylus, 575
Androgynoceras, 656
Angaria, 529
Angelinoceras, 601
Anisactinella, 418
Anisocardia, 471
Anisocrinus, 203
Anisophyllum, 84
Anisothyris, 499
Anisotrypa, 335
Anodonta, 455
Anodontites, 455
Anodontopsiif, 470
Anolcites, 648
Anolotichia, 328
Anomactinella, 418
Anomalanthus, 286
Anomalina, 33
Anomalocaris, 733
Anomaloceras, 605
Anomalocrinus, 213
Anomalocystites, 150
Anomalodonta, 445
AnomahmUs, 72
Anonialospongia, 72
Anomia, 461
Anonioclonella, 56
Anomplialus, 532

824

Aiini-ara, .117
Aniipli.'i. ■■'•>'■>
Aiinpldcnas, f>06
Aiioploplioia, 452
AiioplotlH'Ca, 41()
Anuptvcliia, 537
Antalis, 50i»
Antedon, 236
Aiitheinocrinufi, 189
Anthocrinns, 216
Aiithocystis, 153
Anthoiiyia, 474
Anthracochiton, 512
Anthracomartus, 791
Anthracomya, 452
Anthraconectes, 783
Anthnu-opeltis, 774
Anthnicophausia, 759
Anthmcoptera, 451
AnthriKX^sia, 451
Aiithrapalaenion, 757
Antinomia, 403
Aiitil)leura. 439
Antiptychia, 407
Antirhynclwndla, 394
Antocyrtis, 44
Anuscula, 440
Aorocrinus, 19G
Aparchites, 737
Apasmophyllum, ^4
Aphanaia, 449
Apheleceras, 604
Aphetoceras, 600
Aphragmites, 596
Aphrostroma, 124
Aphyllites, 630
Apioceras, 611
Apiocrinus, 230
Apiücystites, 154
Apion, 805
Apioceras, 608
Ai)orrhais, 551
Apricardia, 477
Apsendesia, 321
Aptychopsis, 754
Aptyxiella, 549
Aptyxis, 549
Apus, 733
Arachnocrinus, 219
Arachnocystites, 152
Arachnoides, 288
Araeacis, 96
Arbacia, 281
Arbusculües, 390
Area, 443
Arcanopora, 346
Arcestes, 642
Archaediscus, 34
Archaeocidaris, 300
Archaeocrinus, 188
Archaeocyathus, 105
Archaeolepas, 744 •
Archaeoniscus, 758
Archaeoplax, 767
Arcliaeoscyphia, 53
Archaeosphaerina, 37
Arcliarenicola, 139
Archastwins, 248
Archegetes, 813
Archegoci-nim:, 818
Archegocystis, 155
Archidesmus, 793
Archimedes, 341
Archinacella, 520
Archiorhynchus, 805
Architarbus, 791
Architectonica, 538
Architipnla, 815
Archiulus, 793
Arcomya, 466
Arcoiuyopsis, 438
Arcnjmgia, 494
Arctitrota, 387
Arenicola, 141
Areünunna, 715
Argas, 753

TEXT -BOOK OF PALEONTOLOGY

Ar(i(ixter, 248
Argia, 811
Argina, 443
Argonauta, 688
Argopa tagus, 297
Argyrothea, 365
Argyrotheca, 405
Aricardium, 490
Arieticeras, 658
Arietites, 655
Aristerella, 462
Aristocystites, 150
Aristozoe, 752
Arnioceras, 655
Arpadites, 648
Arrhoges, 551
Artemis, 492
Arthaberites, 635
Arthracantha, 200
Arthraster, 251
Arthroclema, 343
Arthrolycosa, 790
Arthropliycus, 141
Arthropleura, 758
Arthropora, 345
Arthroracliis, 710
Arthrostylus, 342
Arystidicta, 61
AsaphelluH, 719
Asaphis, 495
Asaphus, 719
Ascidaspis, 722
Ascoceras, 596
Ascocystites, 160
Ascodictyon, 318
Asemoblatta, 803
Aspenites, 634
Aspergillum, 468
Aspidiscus, 99
Aspidites, 645
Aspidocaris, 754
Aspidoceras, 665
Aspidodiadema, 276
Aspidophyllum, 86
Aspidopora, 333
Aspidosoma, 249
Aspidothyris, 401
Aspidura, 256
Assilina, 36
Assiminea, 545
Astacus, 764
Astarte, 472
Astartopsis, 457
Asteractinella, 62, 63
Asterias, 247, 252
Asteriatites, 237
Asterina, 251
Asteroblastus, 167
Asteroceras, 655
Asterocrinus, 201
Asteroderma, 57
Asteropyge, 726
Asthenodonta, 452
Asthenosoma, 278
Asthenothaerus, 467
Astieria, 664
Astraemorpha, 104
Astraeospongia, 62
Astraliuni, 528
Astrangia, 98
Astreopora, 108
Astrhelia, 95
Astrocladia, 55
Astrocnida, 255
Astrocoenia, 101
Astrocoma, 237
Astroconia, 62
Astrocrinus, 172, 190
Astrocystites, 160
Astroides, 76, 106
Astropecten, 247, 249
Astropkyton, 255
Astropyga, 278
Astrorhiza, 24
A.t!ih,rn,n,.,-22\
Ashihnnn.nun, 56

; Astylospongia, 55
I Asyniptoceras, 6Lü

Atactodea, 498
j Atactopora, 338
[ Atactoporella, 331
'■ Ataxaster, 248
j Ataxioceras, 664

Ataxocrinus, 213
I Ateleocystites, 150
i Atelestocrinus, 218

Atergatis, 767

Athleta, 561

Athyris, 417

Atikakania, 105

Atlanta, 536

Atocus, 806

Atoma, 564

Atomodesma, 449

Atops, 713

Atractites, 681

Atretia, 400

Atrina, 446

Atrypa, 409

Atrypina, 408

Attoides, 790

Aturia, 603

Atys, 568

Aucella, 449

Aulacoceras, 680

Aulacophyllum, 83

Aulacopleura, 715

Aulacorhynchus, 389

Aulacostephanus, 665

Anlacotliyris, 406

Aulocopium, 53

Aulocrinus, 224

Aulonotreta, 371

Aulophyllum, 86

Aulopora, 116

Aulosteges, 891

Anricula, 574

Aurigerus, 665

Aurina, 561

Austinella, 381

Austinocrinus, 233

Austriella, 399

Autodetus, 543

Avellana, 567

Avimola, 447

Aviculopecten, 457

Aviculopinna, 446

Axinopsis, 487

Axinus, 487

Axosmilia, 100

Aysheaia, 136

Azara, 499

Azor, 495

Babinka, 444
Bactrites, 629
Bactrocrinus, 218
Bactropora, 343
Bactropiis, 752
Bactrotheca, 571
Bactryninm, 389
Baculina, 654
Baculites, 654
Baculocystites, 150
Badiotella, 460
Badiotites, 644
Baerocrinus, 211
Baetis, 809
Bairdia, 740
Bakewellia, 447
Balanocrinus, 233
Balanocystites, 151
Balanophyllia, 105
Balantionella, 64
JUüamtium, 570
Baianus, 746
Balatonites, 647
Baltoceras, 598
Banibaganites, 635
Banffla, 141
Barbarothea, 815
Barbatia, 443

Baroda, 494

Barrandeites, 638

Barnmdella, 395

Barrandeoceras, 600

Barrandeocrinus, 195

Barrettia, 484

Barroisella, 374

Barroi sia, 71

Barroisiceras, 669, 67^

Bartlettia, 455

Barycrinus, 218

Baryphyllia, 99

Baryphyllum, 82

Barysmilla, 101

Basilicus, 719

Basiliola, 400

Basterotia, 469

Bathmoceras, 597

Bathybius, 17

Bathycoelia, 382

Bathycrinus, 230

Bathycyathus, 95

Batbynotus, 715

Bathysiphon, 24

Bathytoma, 563

Bathyurellus, 718

Bathyuriscus, 718

Bathyurus, 718

Batillus, 529

Batissa, 474

Batocrinus, 195

Batolites, 482

Batostoma, 338

Batostomella, 335

Battersbyia, 87

Bayania, 537

Bayanoteutliis, 683

Baylea, 524

Bayleia, 478

Bdellacoma, 251

Beacbia, 401

Becksia, 67

Beecheria, 403

Bela, 563

Belemnitella, 683

Belemnites, 681, 683

Belemnocrinus, 215

Belemnocystis, 151

Belemnoijsis, 682

Belenmosis, 683

Bolemnoteuthis, 684

Belgrandia, 545

Belinurus, 773

Bellardia, 550

Bellard iella, 564
Belleroplion, 522
Beloceras, 631
Beloptera, 683
Belopterina, 683
Belosepia, 686
Belosepiella, 686
Beloteuthis, 688
Beitina, 783
Bembexia, 525
Beneckeia, 646
Berenicea, 819
Berthelinia, 464
Beyrichia, 738
Beyrichiella, 738
Beyrichiopsis, 738
Beyricliites, 647
Beyrichocrinus, 195
Beyrichona, 735
Bicavea, 323
Bicia, 373
Bicrisina, 320
Bidentia, 732
Bidiastopora, 320
Bifida, 416
Biflabellaria, 326
Bifrontia, 538
Bigenerina, 29
Billingsella, 380
Billinqsia, 372
Billingsites, 597
Bilobites, 383

INDEX

825

J3iloculina, 38
BiradioliUs, 481
Birüstrites, 482
Bisidmonea, H20
Bitliinia, 544
Bittium, 550
Bittnerula, 413
Bitubigera, 820
Bldirocrinus, 197
Blanchardm, 808
Blastoidocrinus, 167
Blauneria, 574
Boliemura, 254
Boletia, 282
Bolivina, 28
Bollia, 738
Bolma, 528
Boutaea, 4ö7
Borelis, 39
Borsonia, 564
Boskovicia, 544
Bosnites, 635
Bosquetia, 740
Bothriocidaris, 270
Bothrocorbula, 499
Bothromicromus, 813
Büthryocanipe, 44
Botriopygus, 290
Botryllopora, 330
Botryocrinus, 221
Botryodictya, 60
Botsfordia, 375
Bouchardia, 407
Bourgetia, 537
Bourgueticrinus, 229
Brachiocrinus, 212

Brachiospongia, 62

Brachylepas, 745

Brachymerus, 394

Brachyprion, 385

Brachypyge, 791

Brachythyris, 410

Brachytrema, 539

Bradoria, 735

Bradyblatta, 803

Bralimacrinus, 200

Branchipodites, 732

Branconia, 395

Brasilia, 658 ,

Brechites, 468

Breynia, 297

Briarocrinus, 191

Brilonella, 524

BHssomorpha, 297

Brissopatagus, 297

Brissopsis, 297

Brissus, 297

Brocchia, 541

Brodieia, 658

Broeckia, 439

Broeggeria, 371

Brongniartiella, 813

Broiitftopsis, 720

Brontes, 720

Bronteus, 720

Bryopa, 468

Bucanella, 521

Bucaiiia, 521

Bucanopsis, 523

Bucanospira, 530

Buccinopsis, 557

Buccimdus, 565

Buccinum, 556

Bücliiceras, 671

Buchiola, 439

Buchites, 648

Buddliaites, 645

Bubiniiia, 29

Biiliiimlus, 576

Bulla, 567

l'.nUaca, 568

Hulliiiia, 567

BiiUiiia, 566

Bullimlla, 568

Bullinula, 566

Bumastus, 720

Bundenbachia, 254
Bunodella, 777
Bunodes, 777
Burgessia, 733
Buria, 769
Bursa, 555
Bursacriims, 225
Bushia, 467
Buskopora, 330
Busycon, 557
Buthus, 770
Byssocardiuin, 490
Byssomya, 499
Byssonychia, 445
Byssopteria, 445
Bythinella, 545
Bythocrinus, 229
Bythocypris, 740
Bythopora, 335
Bythotrypa, 328

Cacabocrinus, 191
Cactocrinus, 197
Cadoceras, 663
Cadomella, 389

Cadomia, 440

Cadomites, 663

Cadomoceras, 658

Cadulus, 510

Caecella, 498

Caecum, 547

Cainocrinus, 233

Calais, 688

Calamocrinns, 238

Calamophyllia, 99

Calamopora, 113

Calapoecia, 114

Calappa, 765

C(xlathocrinus, 225

Calathospongia, 61

Calcarina, 33

Calceocrinus, 213

Calceola, 88

Caleidocrinus, 206

Callavia, 714

Callianassa, 764

Callicrinus, 192

Calliderma, 250

Calliostoina, 532

Callistochiton, 513

Callistoplax, 513

Callizoe, 752

Callocardia, 491, 493

Callochiton, 513

Callocystites, 153

Callogonia, 491

Callonema, 538

Callopegma, 53

Callopoma, 529

Callopora, 337

Calloporella, 337

Calloporina, 337

Callotrypa, 335

Calostylis, 105

CalpiocrinuH, 203

Calvetina, 353

Calycanthocrinus, 208

Calymene, 724

Calyiune, 294

Calyptogena, 476

Calyptraea, 542

Camarella, 394

Camarium, 416

Cainarocrinus, 160, 190

Caniarophorella, 396

Camarophoria, 395

Catuarospira, 416

Cameroceras, 595

Cainerospongia, 68
j Cainerotheca, 571
I Camerothyris, 407
I Camitia, 532
i Campodea, 820
; Campophylluni, 84
j Catuptocrinus, 201
I Camptonectes, 458

( 'am]iyl(irej)halus, 782

Cainpyloccras, 608

Campylosepia, 686

Canadia, 136

Canadocystis, 151

Canavarites, 660

Cancellaria, 562

Cancer, 767

Cancrinus, 763

Caninia, 83

Canistrocrinus, 189

Cantantostoma, 525

Cantharidus, 532

Cantharus, 556

Capellinia, 395

Caphyra, 717

Caprina, 479

Caprinella, 480

Caprinula, 480

Capulus, 541

Carabocrinus, 217

Caratomus, 289

Carbonarca, 442

Carbonia, 739

Carbonicola, 451

Carcinocarcinns, 767

Carcinosoma, 783

Cardiaster, 294

Cardilia, 498

Cardinia, 452

Cardinocrania, 379

Cardiocaris, 754

Cardioceras, 663

Cardiocystis, 160

Cardiola, 439

Cardiolites, 751

Cardiomorpha, 439

Cardiomya, 469
Cardita, 475
Carditamera, 476
Carditella, 476 ,

Cardium, 489
Carduocrinus, 221
Caricella, 561
Carinaria, 536
Carinaropsis, 523
Carinifer, 326
Carinopora, 341
Carnarvonia, 750
Carnites, 635
Carolia, 461
Carolicrinus, 194
Carosyphaera, 42
Carpenteria, 33, 451
Carpenteroblastus, 172
Carpenterocrinus, 232
Carpocrinus, 194
Carpocystis, 156
Carpomanon, 56
Carpospongia, 56
Carterella, 57
Carterina, 124
Carychium, 574
Caryocaris, 751
Caryocrinus, 153
Caryocystites, 152
Caryomanon, 56
Caryophyllia, 95
Caryophyllites, 239
Caryospongia, 56
Casearia, 65
Cassianella, 448
Cassianocrinus, 225
Cassidaria, 554
Cassidula, 574
Cassidulina, 29
Cassidulus, 290
Ikissiope, 546
Cassis, 555
Vastanocrinus, 190
Castocrinus, 213
Catazyga, 408
(\itenipora, 117
Catillocrinus, 214
Vatillus, 447
Catopygus, 290

Catosira, 537
Catulloceras, 658
Caunopora, 123
Cavaria, 324
Caveii, 324
Cavolina, 570
Cea, 323
Cellaria, 348
Cellepora, 350, 353
Celleporia, 353
Cellularia, 348
Cellulipora, 320
Celtites, 640
Cenoceras, 607
Cenocrinus, 233
Cenomanites, 668
Cenosphaera, 42
Centrechinus, 277
Centriocrinus, 191
Centroceras, 606
Centrocrinus, 199
Centronella, 400
Centrotheca, 571
Cephalograptus, 130
Cephaloraphidites, 51
Ceramella, 346
Ceraviocrinus, 219
Ceramophylla, 328
Ceramopora, 327
Ceramoporella, 327
Ceratarges, 722
Ceratiocaris, 750
Ceratisolen, 496
Ceratites» 647
Ceratocephala, 722
Ceratocystis, 151
Ceratodictya, 60
Ceratolichas, 722
Ceratopsis, 738
Ceratopyge, 717
Ceratosiphon, 551
Ceratostreon, 450
Ceratotheca, 571

Ceratotrochus, 94

Ceratozona, 513

Ceraurus, 724

Cercomya, 466

Ceriocava, 326

Ceriocrinus, 225, 231

Cerionites, 72

Ceriopora, 326

Ceritella, 549

Cerithidea, 550

Cerithinella, 549

Cerithiopsis, 550

Cerithium, 550

Cermatia, 793

Cernina, 543

Ceromya, 465

Cerylonopsis, S05

Cetoconcha, 469

Cetomya, 469

Chaena, 500

Chaenocaris, 753

Chaenomya, 439

Chaenopea, 500

Chaetetes, 117

Chaetopleura, 513

Chalnodictyon, 340

Chalmasia, 449

Chama, 477

Chaperüi, 480

Charionella, 416

Chartronia, 660

Chascothyris, 401

Chasmatopora, 340

Chasmops, 727

Chauliodes, 812

Chauliodites, 811

Clieiloceras, 631

Cheirocrinus, 154, 213

Cheiropteraster, 251

Cheimrus, 724

Chelifer, 789

Chelocriniis, 225

Chevmitzia, 537

826

TEXT -BOOK OF PALEONTOLOGY

Cheiiendopora, 59
Chemypus, 551
Chicagocrlnus, 193
Chicoreus, 558
Chilina, 574
Chilocyclus, 53S
Cliilopora, 326
Chiloporella, 328
Chilostomella, 29
Cliilotrypa, 330
Chiridota, 313
Chiton, 513
ChiUmellus, 513
ChlaclocHnus, 232
Chlamydoconcha, 448
Chlamys, 457'
Chlidoiiophora, 404
Choanoceras, 596
Vhoffatia, 663
CholDcrinus, 203
Chonaxis, 85
Chondrostroma, 124
Chonediitoii, 512
Choneplax, 513
Clionetella, 389
Chonetes, 389
Chonetina, 389
Chonop«ctus, 391
Choiiopliyllum, 85
Chonostegites, 116
Chonostrophia, 389
Chorlplax, 512
Choristites, 410
Choristoceras, 6i9
Choristixion, 494
Chresmoda, 799
Christania, 385
Chrysodomus, 557
Chrysomelon, 278
Chrysostoma, 532
Chthamalus, 747
Cibolocrinus, 225
Cicatrea, 472
Cidaris, 372
Cülaroblastiis, 171
Cigara, 151
Ciniitaria, 465
Ciiicta, 407
Cinulia, 567
Circe, 493
Circopora, 124
Cirrus, 531
Cirsotrema, 538
Cistella, 405
Citrocystis, 152
Cladangia, 98
Cladiscites, 643
Cladochonus, 116
Cladocora, 97
Clwiocrinus, 206
Cladopora, 114
Clanculus, 531
Clarkella, 392
Clathrcxlictyon, 123
Clathropora, 345
Clathrospira, b'lb
Clathrospongia, 60
Clathurella, 564
Clausa, 324
Clausilia, 576
Clava, 550
CUmiehhishis, 170
Clavagella, 468
Clavatula, 563
Clav»!lla, 559
Claviclausa, 324
Clavisparsa, 320
Clavulina, 29
Cleidophorus, 440
Cleidotheea, 571
Ck'iocrimis, 186
Cleiotliyridina, 418
VhiothyrU, 417, 418
Cli!ist<!cliiinis, 2>)7
ClevuitiKrinus, 199
dementia, 492

Cleodictya, 61

Clmlora, 570

Cleonoceras, 667

Clesydrospongia, 61

Clidiopliora, 467

Clidochirus, 204

Cliftonia, 387

Climacammina, 29

Climacograptus, 130

Climactichnites, 142

Clinoceras, 611

Clinopistha, 438

Clinopora, 321

Clintonella, 409

Clinura, 563

Clio, 570

Clionites,'648

Clionychia, 445

Clisiophyllum, 85

Clisocolus, 491

Clisospira, 543

Clitambonites, 392

Clonocrinus, 190, 190

Clonopora, 321

Clorinda, 395

Closterocrinus, 218

Clydonautilus, (i02

Clydonites, 648

Clymenia, 628

Clymenonautilus, 602

Clypeaster, 285

Clypeina, 321

Clypeoceras, 645

Clypeus, 290

Clypites, 634

Cnemidiastrum, 57

Cnemidium, 57

Cnisma, 442

Coccocrinus, 199

Coccophyllum, 101

Coccoseris, 112

Coccoteuthis, 687

Cochlearia, 538

Cochloceras, 650

Cochlodesma, 467

Cochlolepas, 542

Codakin, 486

Codaster, 168

Codechinus, 278

Codiacrinus, 221

Codiacystis, 155

Codiopsis, 277

Codoceras, 612

CodoTiaster, 168

Codonites, 169

Coelastarte, 472

Coeliocrinus, 223

Coelocentrus, 527

Coeloceras, 662

Coeloclema, 328

Coeloconus, 343

Coelocorypha, 59

Coelocrinus, 187, 196

Coelocystis, 154

Coelodon, 467

Coeloeanlus, 525

Coelogasteroceras, 605

Coeloraa, 766

Coelomactra, 497

Coelonautilus, 604

Coelopleurus, 281

Coeloptychium, 67

Coelosmilia, 100

Coelospira, 417

Coelostylina, 537

Coenagrion, 811

Coenites, 114

Coenocyathus, 95

Coenocystis, 157

Voenograptus, 130

Coenothyris, 407

Coleoloides, 572

Coleolus, 572
j CoUina, 662
1 Collonia, 529
I Collyrites, 292

Colobocentrotus, 283
Coloceras, 604
Colospongia, 71
Colpocaris, 751
Colpoceras, 595
Columbella, 556
Columbellaria, 553
Collumbellina, 553
Columbites, 640
Columnaria, 87
Columnastraea, 101
Columnopora, 114
Colus, 559
Colymmatina, 55
Connarocystites, 151
Comastrocrinus, 234
Comatulina, 237
Comatulithes, 237
Comaturella, 237
Combophyllura, 82
Comelicania, 418
Cominella, 556
Comoseris, 104
Composita, 418
Composocrinus, 194
Compressidens, 509
Compsoinetra, 237
Coniptonia, 250
Conactaeon, 566
Conchicolites, 139
Conchidium, 394
Conchocele, 487
Gonchodon, 453
Concbolepas, 558
Conchopeltis, 520
Condylocrinus, 189
Condylopyge, 710
Confiisastrea, 101
Congeria, 463
Conocardium, 446
Conoceras, 597
Conoclypeus, 284
Conocoryphe, 713
Conocrinus, 229
Conolampas, 291
Conorbis, 564
Conoteuthis, 684
Cönotreta, 376
Conotuligera, 321
Conradella, 522
Conradia, 373
Constellaria, 334
Conularia, 572
Conulus, 284
Convexastrea, 101
Cophinoceras, 603
Coptostyllus, 548
Coralliochama, 480
Coralliophaga, 472
Coralliuin, 76, 110
Coraster, 296
Corbicella, 487
Corbicula, 474
Corbis, 486, 486
Corbnla, 499
Corbulamella, 499
Corbnloniya, 499
Corburella, 470
Cordillerites, 633
Cordylocrinus, 199
Corimya, 467
Coineöcyclas, 475 '
Cormicaprina, 479
Cornulites, 139
Comuspira, 37
Coroniceras, 655
Coronida, 768
Coronocrinus, 191
Coronula, 747
Corydocephalus, 721
Corylocrinus, 153
Corymhocrinus, 190
Corymbopora, 321
Corynella, 70
Corynotrypa, 319
Coscinella, 345

Coscinium, 346
Coscinopora, 64
Coscinotrypa, 346
Cosmiolithes, 112
Cosmoceras, 668
Cosmocrinus, 221
Cosmogyria, 658
Costidiscus, 653
Cottaldia, 277
Cotylecrinus, 241
Cotyiederma, 241
Cotyledonocrinus, 201
Cranaena, 403
Crangopsis, 757
Crania, 378
Craniella, 378
Craniops, 379
Craniscus, 379
Craspedites, 664
Craspedochiton, 513
Craspedophyllum, 85
Craspedopoma, 540
Craspedosoma, 792
Craspedostoma, 529
Crassatella, 474
Crassatellina, 474
Crassatellites, 474
Crassina, 472
Crassinella, 472, 474
Craterella, 54
Craterina, 150
Craticularia, 63
Cremacrinus, 213
Crenatula, 447
Crenella, 468
Creniceras, 658
Crenipecten, 457
Crepidophyllum, 85
Crepidula, 542
Crepipora, 328
Crescentilla, 754
Crescis, 326
Creseis, 570
Creusia, 747
Cribrilina, 350
Cribroblastus, 171
Cribrostomum, 29
Cricopora, 820
Crinocystis, 160
Crioceras, 670
Crisia, 318, 570
Crisidia, 318
Crisina, 320
Cristellaria, 30
Cromus, 723
Cromyocrimis, 224
Cronicns, 809
Crossopodia, 141
Crossostoma, 529
Crotalocephalus, 724
Crotalocrinus, 216
Crucibulum, 542
Cruratula, 407
Cryphaeus, 726
Cryptabacia, 102
Cryptacanthia, 402
Cryptaenia, 524
Cryptangia, 98
Cryptaulax, 549
Cryptaxis, 108
Cryptoblastus, 172
Cryptocaris, 754
Cryptoceras, 605
Cryptochiton, 513
Cryptochorda, 562
Cryptoclymenia, 628
Cryptocoelia, 71
Cryptocoenia, 101
Cryptoconus, 563
Cryptocrinus, 157
Cryptodictya, 61
Cryptodon," 487
Cryptoglena, 825
Cryptolithus, 711
Cryptomya, 499
Cryptonella, 402

INDEX

827

Cryptoplax, 512, 513
Cryptoplocus, 549
Cryptopora, 4(X>
Cryptoporus, 400
Cryptoschisma, 169
Cryptozoe, 751
Crystallocystis, 152
Crytopora, 341
Ctenobolbina, 738
Ctenocephalus, 713
Ctenoceras, 599
Ctcnocrinns, 190
Cteuodonta, 440
Ctenopterus, 784
Ctenostreon, 460
Cuccoceras, 648
Cucullaea, 442
Cucullaria, 442
Cucullella, 440
Culicocrinus, 199
Cultellus, 496
Cumingia, 495
Cuinulipora, 351
Cnpellaecrinus, 199
Cuphoselenus, 551
Cupressocrinus, 210
Cupularia, 351
Cupulocrinus, 215
Curculioides, 789
Cuixuliopsis, 805
Curticia, 371
Curtonotus, 472
Cuspidaria, 469
Cuvieriiia, 571
Cyatliaxonia, 81
Cyatliidium, 241
Cyathocrinus, 220, 221
Cyathocystis, 159
Cyathodonta, 467
Cyathophora, 101
Cyathophycus, 61
Cyathophyllum, 84
Cyathoseris, 102
Cybele, 724
Cyclas, 472, 475
Cyclaster, 297
Cyclidia, 533
Cydina, 492
Cycloceras, 599, 660
Cycloclymenia, 628
Cydocoelia, 381
Cycloconcha, 470
Cyclocrinus, 72, 160, 232
Cyclocystoides, 159
Cyclolites, 103
Cyclolituites, 601
Cyclolobus, 642
Cydomops, 552
Cyclonema, 530
Cyclonssa, 557
Cyclophorus, 540
Cyclophthalanius, 788
Cyclophyllum, 86
Cyclopora, 347
Cycloporella, 347
Cycloporidiiim, 121
Cydojiorina, 341
Cyclorhina, 397
Cyclospliaei'onia, 758
Cyclospira, 410
Cyclostoina, 540
Cyclostomiceras, 611
Cyclostreina, 532
Cyclotliyris, 398
Cyclotrypa, 329
Cyclotus, 540
Cydus, 372, 773
Cylichna, 568
Cylicocrinus, 195
Cylindra, 560
Cyliiidrites, 566
Cylindrobullina, 560
Cylindromitra, 560
Cylindrophyma, 56
Cyllene, 557
Cymaceras, 658

Cymaclyinenia, 628
Cyniatoceras, 607
Cymatocliiton, 512
Cymatophlebia, 810
Cymbites, 657
Cymbiutn, 561
Cymbopliora, 498
Cyviella, 469
Cymia, 558
Cynodonta, 560
Cypellia, 64
Cypellocrinus, 199
Cyphaspis, 721
Cyphocrinus, 187
Cyphon, 805
Cyphosoiiia, 280
Cyphotrypa, 334
Cypraea, 553
Cyprella, 741
Cypresis, 741
Cypricardia, 472
Cypricardinia, 471
Cypricardites, 442
Cypridea, 740
Cypridella, 741
Cypridellina, 741
Cypridina, 741
Cypridinella, 741
Cyprimeria, 492
Cyprina, 472
Cypris, 740
Cyprosina, 741
Cyrena, 474
Cyrenella, 487
Cyreuoida, 487
Cyricardella, 471
Cyrtactinoceras, 609
Cyrtendoceras, 596
Cyrtia, 412
Cyrtidocrinus, 203
Cyrtina, 412
Cyrtocalpis, 44
Cyrtoceras, 611
Cyrtocerina, 597
Cyrtochilus, 654
Cyrtoclymenia, 628
Cyrtocrinus, 240
Cyrtodonta, 442
Cyrtodontopsis, 445
Cyrtolites, 521
Cyrtolitina, 521
Cyrtopinna, 446
Cyrtopleurites, 648
Cyrtopora, 322
Cyrtorizoceras, 610
Cyrtotheca, 413
Cyrtulus, 559
Cystaster, 159
Cystechinus, 294
Cystiphyllum, 87
Cystispongia, 68
Cystocidaris, 299
Cystodictya, 346
Cythere, 739
CytJierea, 493
Cythereis, 739
Cytherella, 740
Cytherellina, 740
Cytheridea, 739
Cytherideis, 739
Cytherodon, 440
Cytheropteron, 739
Cytinopsis, 413
Cytis, 323
Cytocrimis, 190
Cytodaria, 500
Cytograptus, 132

Dactylioceras, 662
Dactylocrinus, 205
nadylorystin, 156
DadyloU'.utMs, 682
Dadyhis, 565
Dadocrimis, 232
Daedalus, 141
Dalila, 439

Dallina, 406

Dabnanella, 382

Dalnianites, 726

Dalmanitina, 726

Dalmatites, 64«

Danilia, 532

Danubites, 647

Daonella, 448

Daphnella, 564

Daphnites, 648

Daraelites, 633

Darellia, 658

Dasyceras, 652

Davidaonella, 372, 389

Davidsonia, 385

Daviesiella, 389

Davila, 498

Davousti, 452

Dawsonoceras, 599

Dayia, 409

Dazieduszyclia, 410

Deacanemos, 237

Dearbornia, 376

Decadocrinus, 223

Decadopeden, 457

Defranciopora, 326

Deiphon, 725

Deiroceras, 609

Dejanira, 534

Dekayella, 333

Dekayia, 333

Delgadella, 372

Delphinula, 529

Delphinulopsis, 534

Deltacrinus, 213

Delthyridea, 406

Delthyris, 408

Delthyris, 411

Deltoceras, 600

Deltocyathus, 95

Democrinus, 229

Denckmannia, 660

Dendracis, 108

Dendraster, 288

Dendricopora, 342

Dendrocrinus, 215

Dendrocystites, 151

Dendrograptus, 128

Dendrophyllia, 106

Dendropupa, 576

Dendrostrea, 450

Denkmannia, 401

Dentalina, 30

Dentalium, 509

Deocrinus, 188

Derbya, 386

Derniatomya, 469

Dertnatopora, 349

Deroceras, 662

Deshayesia, 543

Desmidocrinus, 194

Desmoceras, 667

Desmograptns, 128

Desoria, 296

Detocrinus, 225

Deutocystites, 150

Diabolocrinus, 188
i J)ia(ievui, 277

Diadiploceras, 605

Diamenocrinus, 189
! Diamesopora, 347

Diannlites, 335
[ Diaphana, 568

Diaphorites, 662

Diaphorostoma, 541

Diaphragnms, 390

Diapora, 123

Diastema, 537

Diastopora, 319, 319, 320

Diastoporina, 320

Dicaniara, 416

Dicollogi-aptiis, 130

Diceras, 477

Dicerocardium, 454

Dichocrinus, 201

Dichograptus 129

Dicliotrypa, 346
Dicoelosia, 383
Dicranella, 738
Dicraniscus, 387
DicranograptuH, 130
Dicranopora, 345
Dicranurus, 722
Dicroloma, 551
Dictyoceras, 599
Dictyoconites, 680
Didyocrinites, 72
Dictyocrinus, 72, 160
Dictyograptus, 128
Dictyomitra, 44
Dictyonella, 396
Dictyonenia, 128
Dictyopleurus, 282
Dictyospongia, 60
Dictyothyris, 404
Didacna, 490
Didynntes, 642
Didymograptus, 129
Didymopora, 329
Dielasma, 402
Dielasmina, 403
Dielasmoides, 403
Diempterus, 551
Digitari, 472
Dignomia, 374
Digonioceras, 607
Dikelocephalina, 720
Dikelocephalus, 720
Dilobella, 738
Dimerella, 399
Dimerocrinus, 187, 205
Dimorion, 612
Dimorpharaea, 103
Dimorphastrea, 104
Dimorphina, 31
Dimorphites, 639
Dimorphoceras, 637
Dimorphocrinus, 169
Dimorphograptus, 132
Dimorphosoma, 551
Dimya, 459
Dimyodon, 459
Dinarella, 401
Dinarites, 648
Dineura, 806
Dinobilus, 373
Dinocystis, 159
Dinopilio, 791
Dinoplax, 513
Dinorthis, 382
Diodoceras, 607
Dionide, 711
Dionites, 648
Dioristella, 416
Diorugoceras, 604
Diphragmoceras, 595
Diphyites, 403
Diphyphyllum, 84
Dipilidia, 478, 482
Diplacomoceras, 671
Diplagnostus, 710
Dipleura, 724
Diplocenis, 595
Diplocidaris, 274
Diploclema, 321
Diploconus, 683
Diplocraterion, 141
Diplocrinus, 233
Diplocteninm, 100
Diplodonia, 487
Diploepora, 112
Diplograptus, 130
Diplomoceras, 654
Diplopodia, 277
THplopKwa, 342
Diploporaria, 342
Diploria, 99
Diplosirenites, 648
Diplospirelhi, 418
üiplostoina, 71
Diplotheca, 571
Diplotrypa, 338

828

TEXT -BOOK OF PALE0NT0L0C4Y

Dipterocuris, 754
Diptvcliocci-as, (yh'.i
Disciiidi's, rüO
Disciiia, ;i7S
Disciiiiscii, 378
Disciiiocaris, 754
Discinolepis, 376
Discinopsis, 377
Ducites, 604
Discitocems, 604
Discocavea, 325
Discoceras, 600, 655,
Discoclynienia, 628
Discocyathus, 95
Discocystis, 159
Discocytis, 323
DisccKlermia, 55
Di.scofacigera, 321
Discohelix, 527
Discoidea, 283
Discophyllites, 651
Discorbina, 32
Discors, 490
Discoscapliites, 670
Discosuinis, 609
Discosparsa, 319
Discotarbus, 791
Discotrochus, 94
Discotropites, 638
Discotypa, 337
Disculiiia, 404
I)isjectx)pora, 124
Distichites, 648
Distichoceras, 659
Distortrix, 555
Ditaxia, 325
Dithyrocaris, 753
Ditremaria, 525
Ditretus, 549
Dittniarites, 648
Dittopora, 339
Di Varicella, 486
Dizygocrinns, 196
Dochinostoma, 290
Dolatocrinus, 191
Dolichocrinus, 229
Dolichopteron, 444
Dolichopterus, 783
Dolium, 555
Domatoceras, 606
Donacicardium, 484, ■
Donax, 496
Dorateuthis, 688
Dorsetensia, 660
Dorycrinus, 196
Dorydenna, 57
Dosinia, 492
Douvilleia, 566
Douvilleiceras, 669
Douvillina, 385
Dreissenia, 463
Dreissensiomya, 463
Drepaiiella, 738
Drepanites, 648
Drepanopterus, 784
Urillia, 563
Droinia, 765
Dryinadusa, 799
DryvMtryjKi, 340
üualina, 439
Dumortieria, 657
Duiicanella, 82
Durga, 454
Dux, 438
Dylmvskielld, 329
TJyeria, 530
Dysagrion, 811
Uysaster, 292
Dyscolia, 404
Dystack'lla, 438

Eastonia, 498
Eatonia, 397
Kburna, 556
Eccylioiiiphalus, 527

Eccyliopterus, 527
Echiiiarachnius, 2SS
Bcliinaster, 252
Ecliinasterella, 251
Kchinohrissus, 289
Echinocardium, 297
Echinocaris, 751
Echinochama, 478
Echinocorys, 292
Ecliinocrei)is, 298
Echinocyamus, 286
Echinocyphns, 282
Echinocystites, 157, 299
Echinodiscus, 288
Echinoencrinus, 154
Echinognathus, 783
Echinolampas, 291
Echinometra, 283
Echinoneus, 289
Echinopsis, 276
Kchinospatagus, 294
Echinosphaerites, 152
Echinostrephus, 282
Echinothuria, 278
Echinus, 281
Ectenocrinus, 212
Ectenodesvm, 444
Ectolcites, 648
Ectomaria, 525
Edaplioceras, C07
Edeiitula, 447
Edmondia, 439
Edrioaster, 159
Edriocrinus. 206
Edwardsocrinus, 199
Egeria, 496.
Egeta, 474
Ehrenbergina, 29
Eichwaldia, 396, 396
Eileticus, 793
Elaeacrinus, 171
Elasmostoma, 71
Elcana, 798
Eider, 761
Eldonia, 313
Elea, 324

Eleutherocaris, 752
Eleutherocrania, 379
Eleutherocrinus, 170
Eligmus, 451
Elkania, 372
Ellipsactinia, 120
Ellipsocaris, 754
BUipsocephalus, 717
Ellipsoidina, 29
Elliptocephala, 714
Elpe, 741
Elymella, 439
Elymocaris, 752
Emarginula, 526
Embla, 469
Embolus, 570
Emeraldella, 776
Emileia, 663
Emmelezoe, 752
Emmonsia, 114
Emperoceras, 654
Enallhelia, 95
Enallocrinus, 216
Enantiosphen, 400
Enclimatoceras, 603
Encoiloceras, 606
Encope, 288
Encrinurus, 723
Encrinus, 225, 233
Endoceras, 595
Kndolohus, 605
Endothyra, 33
Bndoxocrinus, 233
Engonoceras, 671
Enicliaster, 294
Ennalaster, 294
Ennmcystis, 153
Enopleura, 150
Enoplocera.s, 606
Enoplochiton, 513

Enoploclytia, 763
Eiisis, 496
Entalina, 510
Entdliopsis, 509
Entalis, 509
Entalium, 508
Entalophora, 230
Enteletes, 383
Enteletoides, 383
Entodesma, 468
Entolium, 458
Bntomidella, 741
Entomis, 741
EntoMocaris, 7ö0
Eiitomoconchus, 742
Eobuthus, 788
Eocicada, 815
Eocidaris, 300
Eocyclina, 492
Eocystites, 151
Bodiadenia, 276
Eodiscus, 711
Eoharpes, 711
Eoluidia, 255
Eooholus, 372
Boorthis, 381
Eophrynus, 791
Eophyton, 134
Eopteria, 439, 733
Eoscorpius, 788
Eosphaeroma, 758
Eospirifer, 411
Eostrophomena, 384
Botrochus, 543
Eotrophonia, 137
Bozoon, 37
Epactocrinus, 219
Ephemera, 809
Ephippioceras, 604
Ephippium, 461
Ephippodonta, 488
Epiaster, 294
Epicyrta, 4Ü7
Episageceras, 633
Episiphon, 509
Epismilia, 97
Epithyris, 402, 403
Epitonium, 538
Erato, 554
Eremites, 648
Eremoceras, 611
Eretmocrinus, 195
Erettopterus, 785
Erichthus, 769
Eridophyllum, 84
Eridorthis, 381
Eridotrypa, 329, 335
Ennocystis, 155
Eriphyla, 472
Eriptycha, 567
Brisocrinus, 225
Erodona, 499
Brvilia, 498
Erycina, 488
Erycinella, 488
Eryma, 763
Eryon, 762
Eryx, 498
Esoasona, 735
Eschara, 350
Esclmrites, 324
Escharopora, 345
Estheria, 734
Estheriella, 734
Esthoniopora, 336
Estonioceras, 607
Etallonia, 566, 703
Etheria, 455
Etheridgaster, 251
Etheridgia, 68
Etheridgina, 391
Ethviophyllum, 105
Etisus, 767
Etyns, 767
Bubleptus, 796
Eucaenus, 801

I Bucalathis, 404
Eucalytocrinus, 192
Eucluirii^, 469
Eucluisma, 439, 733
Euchilotheca, 571
Eiichirocrinns, 213
Euclirysalis, 538
Euciroa, 469
Eucladia, 255
Eiicladocrinus, 200
Euconactaeon, 566
Euconia, 525
Eucorystes, 765
Eucratea, 348
Encrinus, 187
Eucuclodema, 381
Eucydus, 530
Eucymba, 561
Eucyiditium, 44
Encystis, 155
Eiicythara, 564
Eudea, 69
Budesella, 388
Budesia, 406
Budesicrinus, 241
Eudoxocliiton, 513
Bugeniacrinus, 239
Eugereon, 817
Bugyrina, 55
Bulielia, 95
Bulimella, 537
Euloma, 715
Eulophoceras, 672
Eumegalodon, 454
Eumetria, 414
Eumicrotis, 448
Eunella, 402
Eunema, 530
Bunicites, 139
Bunoa, 377
Euubolus, 871
Euomphalopterus, 527
Buomphalus, 527
Bupachycrinus, 224
Eupatagus, 297
Eupera, 475
Buplienius, 523
Euphoberia, 798
Buphyllites, 652
Euproöps, 774
Eupsaininia, 105
Euractinella, 418
Euraphia, 747
Burhodia, 290
Euryale, 255
Burycare, 715
Eurychilina, 738
Burydictya, 345
Burymya, 462
Burynoticeras, 667
Buryocrinus, 205
Burypneustes, 282
Burypterella, 783
Eurypterus, 782
Eurysoma, 783
Burystomites, 600
Busarcus, 783
Eusiphonella, 70
Euspilopora, 345
Buspira, 543
Buspirocrinus, 218
Eustoma, 550
Bustylus, 537
Eutaxocrinus, 205
Eutermes, 804
Buthemon, 255
Buthria, 557
Eutliydesma, 439
Exdhyris, 417
Eutonioceras, 646
Eutrephoceras, 607
Butiocbocrinus, 196
Euzonus, 792
Evactinopora, 346
Exapinurus, 777
Exelissa, 549

INDEX

829

Exogyra, 450
Kxtnwrinus, 232

Fcabella, 488
Fabulariu, 3!'
Falcilituites, 60(»
Ftihmla, r»08
Faorina, 2ltO
Fasciciilipora, 321
Fascinella, 543
Fasciolaria, 559
Fascipora, 321
Fasciporina, 821
Faunus, 548
Favia, 98
Favicella, 330
Favistella, 87
Favositella, 328
Favosites, 113
Felania, 487
Fenestella, 341
Fenestralia, 341
Feiiestrapora, 341
Fenestrella, 341
Fergensia, 320
Fibula, 549
Fibularia, 287
Ficula, 555
Fieldia, 750
Filicea, 323
Filier isla, 318
Filicrisina, 320
Filifascigera, 322
Filisparsa, 319
Fiinbria, 486
Fimbriella, 487
Fimbriothyris, 407
Finkelnburgia, 381
Fincherid, 474
Fissidentaliuin, 509
Fissirostra, 406
Fissurella, 526, 526
Fissurellidea, 526
Fissuridea, 526
Fissur irostra, 406
Fistulana, 500
Fistulipora, 329
Flahi'Uocrinus, 225
Flahfllothvris, 406

Flabellum, 94, 570

Fleniingia, 531

Flemingites, 645

Foordiceras, 005

Floridina, 351

Fl.ustrelluria, 350, 351

Forbesia, 545

Forbesiceras, 671

Forbesioerinus, 204,
205

Fordilla, 439

Fordinia, 371

Forficula, 800

Foricula, 324

Fortisia, 567

FoRsariofsis, 534

Fossarulus, 545

Fossarns, 540

Fragilia, 494

Fragum, 490

Frenuhi, 406

Frenulina, 406

Frieleia, 400

Froiidi(nilaria, 30

Fulgoraria, 5(51

Fulgoridmm, 819

Fulgur, 557

Fungia, 102

Fungocystites, 156

Fuselia, 410

Fusinus, 559

Fusisi)ira, 538

Fustiaria, 509

Fusulina, 34

Fusus, 559

Gadila, 510

Gadinia, 573
dadns, 510
Gafrariuni, 493
Gtüaten, 474
Galathea, 7<'i4
Galaxea, 100
Galenopsis, 766
Galeoda, 554
Galeonnna, 488
Galerites, 284
Galeropygus, 285
Galerus, 542
Gainmarocrinus, 240
Gainmarus, 759
Gamophura, 570
Gampsonyx, 756
Ganymeda, 237
Garantiana, 664
Gargantua, 351
Garnieria, 672
Gasocaris, 756
Gaspesi, 385
Gasterocoma, 219
Gastrana, 494
Gastrioceras, 636
Gastrochaena, 500
Gastrocrinus, 221
Gaiidryceras, 652
Gaudryina, 29 •
Gazacrinus, 187
Gecarcinus, 767
Geinitzella, 335
Geinitzia, 803
Geisonoceras, 598
Geniellaria, 348
Genuna, 494
(jemviellana, 479
Gemniellaroia, 392
Gemmipora, 108
Genabacia, 103
Genea, 557
Genicopatagus, 297
Gennaeacrinus, 195
Genota, 563
Geocoma, 237,. 256
Geocrinus, 194
Geophilus, 793, 139
Geoteuthis, 687
Gephyroceras, 631
Gephyrocrinus, 238
Geralinura, 788
Geraphrynus, 791
Geratarbus, 791
Geroneura, 797
Gervillia, 447

Geyerella, 387

Geyero(;eras, 652

Gibbula, 532

Gigantoceras, 608

Gilbertsocrinus, 188

Girtyella, 403

Gisortia, 554

Gissocrinus, 220

Glaharis, 455

Gladiograptus, 132

Glandulina, 30

Glaphurus, 723

Glaphyrocystis, 155

Glassia, 409

Glassina, 415

Glaucomya, 494

Glauconiyacidae, 494

Glauconia, 546

Glaueonome, 342, 343

Glenotremites, 237

Globigerina, 31

Glohoblastus, 171

Gloria, 439

Glossina, 374

Glossites, 439

Glossoceras, 597

Glossograptus, 130

Glossothyris, 404

Glossotrypa, 330

Glottidia, 374

Glycimeris, 443, 499, 500

Glyphaea, 762
Glyphidites, 648
Glyphioceras, 636
Glyphis, 526
Glyphocypluis, 282
Glyphostonia, 564
Glyptaster, 187
Glyptechinus, 282
Glypticus, 276
Glyptobasis, 531
Glyptocardia, 439
Glyptocidaris, 280
Glyptocrinus, 189
Glyptocystites, 154
Glyptodesma, 444
Glyptograptus, 130
Glyptopora, 346
Glyptosceptron, 110
Glyptoscorpius, 785
Glyptosphaerites, 156
Gnathia, 758
Gnathodon, 498
Gnoriinocrinus, 205
Goldius, 720
Gomphoceras, 613
Gomphocystites, 156
Gomphoides, 810
Gonambonites, 392
Gongylospongia, 60
Goniacrinus, 218
Goniasteroidocrinus, 188
Goniastrea, 99
Goniobasis, 548
Gonioceras, 609
Goniocidaris, 273
Goniocladia, 346
Gonioclymenia, 628
Goniocoelia, 416
Goniocora, 97
Goniodiscus, 711
Gonioloboceras, 631
Goniomya, 466
Goniophora, 462

Gouiophorus, 279

Goniophylluni, 87

Goniopygus, 276

Goniosoma, 472

Gonioteuthis, 682

Goniotrypa, 345

Gonocrinites, 154

Gonodactylus, 768

Gonodon, 486

Goodallia, 472

Gorgonella, 110

Gorgonia, 110

Gorgonoceplmlus, 255

Gosavia, 561

Gosseletia, 445

Gosseletina, 524

Gothocrinus, 215

Gothograptus, 132

Gotlandia, 373

Gouldia, 474, 493

Graeophonus, 788

Grammatodon, 441

Grammoceras, 658

Grammysia, 439

Granatocrinus, 171

G-raphiocrinus, 222, 225

Graphoceras, 658

Graphularia, 110

Graptacnie, 509

Graptodictya, 345

Grasia, 292

Grateloupia, 492

Greenfieldia, 415

Gresslya, 464

Griesbachites, 639

Gripliodictya, 61

Grossouvria, 663

Grotriania, 472

Gruenewaldtia, 409

Gryllus, 799

Gryphaea, 450

Gryphaeostrfa, 450

Gryphochiton, 512

Grypoceras, 602
Gualtieria, 297
Guembelites, 648
Guerangeria, 452
Guettardia, 64
Guettardicrinus, 232
Guilfordia, 528
Gundlacliia, 575 •
Gwynia, 405
Gymnites, 645
Gynniocrinus, 240
Gyninotoceras, 647
Gypidia, 394
Gypidula, 395
Gyronema, 530
Gyropleura, 478

Habelia, 776
Habrocrinus, 194
Hadentomum, 806
Hadrocrinus, 191
Hadrophylluui, 82
Haenleinia, 447
Hagenowinella, 349
Halia, 561
Halicardia, 468
Halilucites, 646
Haliotis, 523
Haiiris, 469
Hallicystis, 154
Halliella, 738
Hallina, 408
Hallirhoa, 54
Halloceras, 603
Hallodictya, 61
Hallopora, 337
Halloporina, 337
Halobia, 448
Halomitra, 102
Halonynipha, 470
Halorella, 399
Halorites, 639
Halysiocrinus, 214
Halysites, 117
Haniinea, 567
Hamites, 653
Hammatoceras, 660
Hamulina, 654
Hamulus, 508
Hamusina, 531
Hanleya, 512
Hapalocrinus, 199
Hapaloptera, 807
Haplaraea, 105
Haploceras, 661
Haplocorius, 721
Haplocrinus, 208
Haplocystis, 159
Haplohelia, 95
Haplooecia, 321, 324
Haplo-phragmium, 26
Haplopleuroceras, 660
Haploscapha, 447
Haplosmilia, 101
Haplostiche, 26
Harmocrinus, 189
Harpa, 562

Harpactocarcinus, 767
Harpagodes, 552
Harpax, 459
Harpeä, 711
Harpina, 711
Harpopsis, 562
Harpoceras, 658
Harttina, 402
Hastlniinia, 785
Hastula, 562
Hauericeras, 667,
Hauerina, 38
Hauerites, 635
Haugia, 060
Haustellum, 558
Hautkenia, 547
Hebertella, 381
Hedenstroeniia, 634
Hederella, 320

830

iiriviu'.i, vtn

HrU-lnll, :VJO
Helcioiiiscus, '>-H)
Helcionopsis, 5'20
HelianthasttT, 'Jöl
Heliasttn-, 251
Helicanlax, 551
Helicoceras, (554
Helicodictya, GO
Helicodonta, 576
Helicophanta, 576
Helicopora, 341
Helicoryptus, 532
Helicotonia, 527
Helictites, 648
Heliocrinus, 152
Heliolites, 112
Heliophyllum, 84
Heliopora, 111
Heliotrypa, 345
Helix, 576
Helmersenia, 372
Helminthochiton, 512
Heloceras, 599
Heionyx, 510
Helopora, 342
Hemiarthrum, 512
Hemiaspis, 777
Hemiaster, 295
Hemicardium, 444
Hemicellaria, 324
Hemicidaris, 275
Heniicosmites, 152
Hemicrinus, 240
Hemicystites, 159
Hemidiaderaa, 275
Hemidonax, 484, 496
Hemifusus, 557
Hemigyraspis, 719
Hemimactra, 498
Heminajas, 452
Hemipatagus. 294
Heniipedina, 277
Heinlphragma, 338
Hemiphragmoceras, 612
Hemiplethorhynchus, 39
Hemiplicatula, 461
Hemipneustes, 293
Hemipronites, 393
Heraiptychina, 403
Heraisinus, 548
Hemithyris, 399
Hemitrypa, 341
Hejikulactylus, 552
Heptastyiis, 106
Heraclites, 648
Hercoceras, 605
Hercocrinus, 188
Hercoglossa, 603
Hercynella, 573
Hermatostroma, 123
Hernodia, 320
Herpetocrinus, 212
Herpetolitha, 102
Hertha, 237
Hesperagrion, 811
Hesperiella, 524
Hesperites, 648
Heteraster, 294
Heterastridiuin, 2, 121
Heterelasma, 403
Heteroblastus, 172
Heterocanlia, 498
Heterocentrotus, 283
Hetcroceras," 654
Heterocrinus, 212, 212
Heterocystites, 153
Heterodiadema, 277
Heterwlicerds, 477
Heterodictya, 344
Heterodoiiax, 495
Heteroncnia, 318
Heterophyllia, 87
Heteropora, 326
Hoterosalt'iia, 21\>
Heteroschisiiia, 168, 509

TEXT -BOOK OF PALEONTOLOGY

TIcterostegina, 35
Heterotypa, 333
Hdtangia, 484
Hexacrinus, 200
Hexagonella, 330
Hexalwcystis, 152
Hexameroceras, 612
Hiatella, 499
Hibemula, 237
Hibolithes, 682
Hildoceras, 658
Himantopterus, 783
Hindella, 415
Hilldia, 56
Hindsiella, 488
Hinnites, 458.
Hippagus, 469
Hipparionyx, 386
Hippochrenes, 552
Hipponichariou, 735
Hippoiüx, 542
Hippopodium, 462
Hippoporina, 352
Hippopus, 490
Hippurites, 482
Histioderma, 141
Histricrinus, 200
Hochstetteria, 449
Hodotermes, 804
Hoemesia, 447
Holaster, 293
Holasterella, 62
Holcodiscus, 667
Holcospongia, 71
Holcostephamis, 664
Holectypus, 284
HoUandites, 647
Hollina, 738
Holmia, 714
Holmiceras, 601
Holocrinus, 232
Holocystis, 101, 150
Hologyra, 533
Holopea, 530, 539
Holopella, 538
Holopneustes, 282
Holopus, 241
Holorhynchus, 395
Holothuria, 313
Homaloceras, 601
Homalocrinus, 203
Homalonotus, 724
Homarus, 764 .
Homelys, 761 ;
HoDierites, 639
Homocrinus, 217
Homocystites, 154
Homoeosolen, 323
Homoeospira, 414
Homolampas, 297
Homomya, 466
Homotrypa, 332
Homotrypella, 332
Hoplites, 668
Hoplitoides, 671
Hoplocrinus, 211
Hoplolichas, 722
Hoploinytilus, 449
Hoploparia, 764
Horioceras, 659
Horiostoina, 541
Hormotoma, 525
Hornera, 324
Huddlestonia, 658
Huenella, 392
Hiighmillcria, 785
Hiui;4antcs, MG
Hurdia, 750
Huronia, 609
Hustedia, 414
Hyalaea, 570
Hyalostelia, 62
Hyalotragos, 58
Hyattechiiius, 301
llyatfclht, 415
Uyattidiiia, 415

Hyboclypeus, 292
Hybocrinus, 211
Hybocystis, 211
Hybocystites, 154
Hyboechinus, 306
Hydatina, 567
Hydnoceras, 60
Hydractinia, 120 .
Hydreiouocrinns, 223
Hydriocrinus, 222
Hydriodictya, 60
Hydrobia, 545
Hymenocarls, 750
Hymenocydus, 36
Hyiuenophyllia, 99
Hynniphoria, 407
Hyocrinus, 238
Hyolithellus, 572
Hyolithes, 571
Hypagnostus, 710
Hypalocrinus, 234
Hypanthocrinus, 192
Hypecliinus, 282
Hyperammina, 25
Hyperlioceras, 658
Hyperocrinus, 196
Hyphautaenia, 61
Hyphasmopora, 344
Hypocladiscifes, 643
Hypocrinus, 157, 219
Hypodiadeina, 275
Hyponome, 160
Hypothyridina, 398
Hypothyris, 398
Hypotrema, 461
Hypsipleura, 537
Hyptiocrinus, 187
Hysocrinus, 208
Hystatoceras, 672
Hystricurus, 716

Ichthyocrinus, 204

Ichthyosarcolites, 480

Idalina, 39

Idiocrinus, 187

Idiostroma, 124

Idiotrypa, 335

Idmonea, 320

Idonearea, 442

Jgoceros, 541

Ilariona, 290

Illaenus, 719

Illycrinus, 230

Ilyodes, 793

Imbricaria, 560

Indoceras, 671

Infraclyi^eus, 292

Infulast(!r, 294

Inocellia, 812

Inoceranius, 447

Fntrapora, 345

Inversaria, 324

Inyoites, 646

[ocrinus, 212

Iphidea, 370

Iphidella, 370

Iphigenia, 496

Iridina, 455

Iridometra, 237

Isanda, 532

Isaster, 294

Isastrea, 98

Iscanotia, 494

Ischadites, 72

Ischnochiton, 513

Iscliyrina, 733

Ischyrodonta, 442

Isidora, 575

Isis, 233

Ismenia, 405, 408

Isoarca, 443

Lsobuthus, 788
I Isoeardia, 491
I Lsocliilina, 737

Isocrania, 379
I Isocrimis, 206, 233

Isoculia, 439
Isodonta, 496
Isogonomon, 447
Isogramma, 389
Isonema, 538
Isopleiira, 553
Isorhaphinia, 57
Isorhynchus, 393
Isoteius, 719
Isotrypa, 341
Isoxys, 735
Itieria, 549
Ivania, 524

Jaculella, 25
Jaekelocystis, 154
Jahnites, 670
Janeia, 438
Janiceps, 418
Janira, 457'
Japonites, 637, 645
Jerea, 54
Jereica, 58
Joannisella, 487
Joannites, 642
Jodamia, 482, 482
Jonesella, 738
Jonesina, 738
Jouannetia, 501
Jovellania, 610'
Jovites, 639
Juglandocrinus, 153
Julopsis, 793
Julia, 464
Julus, 792
Jupiteria, 815
Juvavella, 401
Juvavellina, 401
Juvavites, 639

Kampecaris, 793
Kanilla, 565
Kanopliyllum, 82
Karpinskya, 409
Katharina, 513
Kayserella, 386
Kayseria, 418
Keilostoma, 537
Kelaeno, 688
Kellia, 488
Kelliella, 489
Keramosphaera, 40
Keyserlingia, 376
Keyserlingina, 387
Keyserlingites, 647
Kingena, 406
Kingia, 406
Kionoceras, 600
Kirkbya, 738
Klipsteinia, 648
Kloedenella, 738
Kloedenia, 738
Knemiceras, 671
Kochia, 444
Koenenites, 631
Kokenella, 524
Kokenia, 522
Koninckella, 419
Koninckia, 107
Koninckina, 419
Koninckites, 645
Koninckoceras, 606
Koninckocidaris, 301
Koninckodonta, 419
Koninckophyllum, 85
Kraussia, 408
Kraussina, 408
Kreischeria, 791
Kustarachne, 789
Kutorgina, 371
Kymatites, 644

Labechia, 124
Labiduromma, 800
Labiosa, 498
Lacazella, 366

I

INDEX

831

Lacazella, 388
Laatzind, 38
Lachesis, 5G3

-5 Lacuna, 540

f Lacuiiella, 540

Lacuiiina, 539
Laevicardiuni, 490
Laevidentaliuni, 509
Lagauum, 286

r; Lagena, 29

I lAujeniocrinus, 209

Laguncula, 544
Lahuseniocrinus, 189
Lakhmirux, 372
Lamanskya, 384
Lambi-QS, 766
Lampania, 550
Lampterocrinus, 187
Lanceolites, 635
Lanieria, 284
Lapeirousia, 482
Lapillocystites, 150
Lapparentia, 545
Lapworthura, 255
Ijaqueus, 406
Lartetia, 545
La.saea, 488
Lasiograptus, 131
Laternula, 466
Laterocava, 320
Laterocea, 323
Latirus, 559
Latomeandra, 98
Latusastrea, 97
Latzelia, 793
Laubella, 524
Leaia, 734
Leanchoilia, 732
Lebedictya, 60
Lecanites, 644
Lecanocrinus, 203 •
Lecanocrinus, 205
Lecythiocrinus, 221
Lecythocrinus, 221
Leda, 441
Leila, 455
Leiochonia, 59
Leiocidaris, 273
Leioderma, 561
Leiomya, 469
Leioniyalina, 449
Leiopedina, 278
Leiopteria, 448
Leiorhynchus, 398
Leiostoma, 559
Leiostracosia, 67
Lejopyge, 710
Lenita, 288
Lenticeras, 672
Lenticulites, 35
Lepadocrinus, 154
Lepadocystis, 154
Lepas, 745
Lepeditta, 734
Leperditella, 737
Leperditia, 737
Lepeta, 520
Lepetella, 520
Lepetopsis, 520
Lepidaster, 251
Lepidechiuus, 306
Lepidesthes, 306
Lepidocentrus, 301
Lepidocidaris, 300
Lepidocoleus, 743
Lepidoderma, 782
Lepidodistis, 159
Lepidopleurus, 612
Lepidolites, 72
Lepidospongia, 67
Lepidurus, 733
Lepisma, 819
Lepocrinus, 154
Lepralia, 352
Leptaster, 250
Leptaena, 384

Leptaenalosin, 391

Leptaenisia, 385

Leptagonia, 384

Jjeptastraea, 98

Leptella, 384

Leptembolon, 372

Leptesthes, 474

Leptobolus, 372

Leptoceias, 653

Leptochiton, 512

Leptocoelia, 417

Leptocrinus, 194

Leptodesma, 444

Leptodomus, 439

Leptodus, 387

Leptograptus, 130

Leptomaria, 524

Lepton, 488

Leptophragma, 64

Leptophyllia, 103

Leptopoina, 540

Leptoria, 99

Leptosolen, 496

Leptospisula, 498

Leptostrophia, 385

Leptoteuthis, 687

Leptotrypa, 334

Leptoxis, 548

Leskia, 297

Leuconia, 574

Leucozonia, 560

Leuctra, 808

Leuroceras, 604

LeveiUeia, 524

Lewisiella, 532

Libiiina, 472

Lichas, 721

Licheiialia, 347 "

Lichenocrinus, 160

Lichenocystis, 157

Lichenoides, 157

Lichenopora, 325

Licheuotrypa, 330

Liebea, 449

Ligula, 467

Lillia, 660

Lima, 460

Limacine, 570

Limaea, 460

Limanomia, 461

Limatula, 460
Limnaeus, 574
Limnocardium, 490
Liraopsis, 442
Limoptera, 448

Limuloides, 777
Liimilus, 774
Linearia, 494
Lindstroemaster, 248
Lindstroemella, 378
Lingula, 374
Lingularius, 374
Lingulasma, 374
Lingulelasma, 374
Lingnlella, 372
Lingulina, 30
Lingulipora, 374
Lingulobolus, 371
Lingulficaris, 751
Lingulodiscina, 377
Lingulops, 374
Linnarssonella, 377
Linnarssonia, 376
Linthia, 296
Linuparus, 763
Lioceras, 658
Lioclema, 336
Lioclemella, 336
Liolophura, 513
Liopeplum, 561
Liopistlia, 469
Lioplax, 544
Liospira, 525
Liothyrina, 365, 404
Liothyrift, 404
Liotia, 529

Liparoceras, 656, 657
Lisgocaris, 754
Lispoceras, 604
Lispodesthes, 551
Lissoceras, 661
Lissochilus, 534
Lissopleura, 401
Lithactiiiia, 102
Lithagrion, 811
Litharaea, 106
Lithobius, 793
Lithocampe, 42
Lithocardium, 490
Lithocrinus, 204
Lithodendron, 99
Lithodomus, 463
Lithodryas, 815
Lithogaster, 762
Lithoglyphus, 545
Lithophagus, 463
Lithophylax, 766
Lithopoma, 528
Lithostrotion, 86
Litiopa, 540
Litoceras, 600
Litoricola, 766
Littorina, 539
Littorinella, 545
Lituites, 601
Lobantale, 509 •

Lobites, 641
Lobocarcinus, 767
Lohocrinus, 196
Lobolühus, 160, 190
Lobopora, 353
Lobopsammia, 106
Locularia, 322
Loculipora, 341
Loczyella, 388
Lodanella, 150
Loftusia, 120
Louchodonias, 712
Longobardites, 634
Lonsdaleia, 86
Lophoblastus, 172
Lophoceras, 607, 658
Lophocrinus, 221
Lopholepis, 322
Lophonotus, 793
Lophophyllum, 84
Lophoseris, 103
Lophosmilia, 100
Lophospira, 525
Lorica, 513
Loricella, 513
Loricites, 512
Loricula, 744
Loriolaster, 251
Loripes, 486
Lotorium, 555
Lovenechinus, 303
Lovenia, 297
Loxoceras, 608
Loxonema, 536
Loxopteria, 444
Lucapina, 526
Lucapiiiella, 526
Luciua, 485, 486
Ludwigia, 658
Lumbricaria, 139
Lunihricites, 139
Lunatia, 543
Lunulicardium, 444
Lunulites, 350
Lutetia, 489
Lutraria, 498
Luzouia, 470
Lychnocanium, 44
Lycodes, 453
Lycophoria, 394
Lycophrys, 36
Lymnaea, 574
Lynceites, 735
Lyonsia, 468
Lyonsieila, 4G8
Lyia, 406, 560

Lyriocrinus, 189
Lyriopecten, 457
Lyrodesnia, 455
Ijyropora, 341
Lysactinella, 60
Lysiosquilla, 768
Lysis, 558
Lysocystites, 157
Lytoceras, 652
Lyttonia, 387

Macamlrevia, 406
Macarobrinus, 194
Maccoya, 303
Maeha, 495
Machilis, 819
Machomya, 466
Mackenzia, 118
Maclurea, 527
Maclurina, 527
Macoina, 494
Macraster, 294
Macrocallista, 493
Macrocaris, 751
Macrocephalites, 663
Macrocheilus, 536
MacrocMlina, 536
Macrocrinus, 195
Macrocypris, 740
Macrocystella, 157
Macrodon, 441
Macronotella, 738
Macropneustes, 297
Macroscaphites, 653
Macroschisma, 526
Maciostylocrinus, 191
Mactra, 497
Mactrella, 497
Mactroderma, 497
Mactromya, 466
Mactropsis, 498
Mactrotoma, 497
Madrepora, 107
Maeneceras, 630
Magalompliala, 522
Magas, 407
Magasella, 407
Magellania, 408
Magila, 763
Magnesia, 277
Mala, 766
Maiocercus, 791
Malacostronia, 124
Malaptera, 551
Malletia, 441
Malleus, 449
Malocystis, 151
Mammites, 669
Mandaloceras, 612
Mangilia, 564
Mannia, 408
Manticoceras, 631
Maragnicrinus, 222
Maretia, 297

Margarites, 532, 638, 640
Margarya, 544
Marginaria, 349
Marginella, 560
Marginifera, 390
Marginulina, 30
Mariacrinus, 190
Marmolatella, 533
Marsipella, 24
Marsipocrinus, 199
Marsupiocr-inus, 189, 199
Marsupites, 235
Martesia, 501
Marti nia, 412
Martiniopsis, 412
Mastigocrinus, 220
Matercula, 444
Matheria, 442
Matheronia, 477
Mathilda, 537
Matthewia, 571
Matuta, 765

832

Mazza, 560
MiizziUirui, 560
Mecochirus, 763
Mecynoflon, 471
M«-(llicottia, 633
Mcdusaster, 251
Meekechiims, 307
Meekella, 387
Meekoceras, 645
Meekocytis, 154
Meekopora, 330
Medusites, 134 ^
Megacystites, 150
Megalanteris, 402
Megalaspis, 718
Megalithista, 57
Megjilodon, 453
Megalograptus, 783
Megalomastoma, 540
Megalomus, 454
Meganeura, 809
Meyanteris, 402
Megaphyllites, 641
Megapodagrion, 811
Megaptera, 445
Megaraphidia, 812
Megarhiza, 59
Megarhynchus, 392
Megatebennus, 526
Megateuthis, 682
Megathyris, 405
Megerlea, 405
Megerlina, 408
Megistocrinus, 195
Meiocardia, 491
Melanipus, 574
Melanagrion, 811
Melania, 547
Melanopsis, 548
Meleagrina, 448
Melia, 600
Meliceritites, 324
Meilita, 288
Melo, 561
Meloceras, 611
Melocrinus, 190
Melonechinus, 304
Melonella, 56
Melongena, 557
Melanites, 304
Melonoceras, 611
Membranipora, 349, 350
Membraniporella, 350
Meneghiniceras, 652
Menipea, 348
Meniscopora, 353
Menophyllum, 84
Mentzelia, 412
Meoma, 297
Meretrix, 493
Merista, 516
Meristella, 415'
Meristina, 415
Meristocrinus, 204
Meristospira, 415
Meiocrinus, 215
Mero'e, 492
Mesalia, 546
Mesenterijmra, 319
Mesidotea, 758
Mesite.% 156
Mesoblastus, 172
Mesoceras, 597
Mesocrinus, 229
Mesocystis, 156
Mesodesma, 498
Mesograptus, 130
Mesoleuctra, 808
Mesonacis, 714
Mesoneniura, 808
Mesothyra, 753
Mesotreüi, 377
«Mesotryf);i, 333
Mospilocrinus, 203, 232
Mesuropetala, 810
Metablastus, 170

TEXT-BOOK OF PALEON TOLOGY

Metacoceras, 605
Metacrinus, 234
Metalia, 297
Metaplasia, 412
Metaporliinus, 202
Metasibirites, 639
Metatirolites, 648
Metengonoceras, 671
Metichthyocrinus, 205
Metoiceras, 671
Metopaster, 250
Metoptoma, 520
Metriophylliun, 84
Metiila, 557
Michelinia, 115
Mickwitzella, 371
Mickwitzia, 370
Micrabacia, 103
Micraster, 296
Microblastidium, 67
Microceras, 521
Microconchus, 138
Microcrinus, 237
Microcylus, 82
Microcyphus, 282
Microderoceras, 656
Microdiscus, 711
Microdoma, 531
Microdon, 471
MicrOinaia, 766
Micromelania, 545
Micromitra, 370
Micropedina, 278'
Micropocrinus, 241
Micropora, 351
Microporella, 351
Micropsis, 280
Microschiza, 537
Microseris, 102
Microsolena, 104
Microthorax, 766
Microthyris, 406
Microtropites, 638
Mila, 444
Miliola, 38
Miliolina, 38
Millepora, 119
Millericrinus, 231
Milneria, 476
Miltha, 486
Miltites, 639
Miiuoceras, 629
Mimocystites, 157
Mimulus, 387
Miocidaris, 272
Mischoptera, 813
Miskoia, 136
Missouricrinus, 215
Mithracites, 765
Mitoclema, 321
Mitra, 560
Mitraefusus, 557
Mitraster, 250
Mitrocystella, 150
Mitrocystites, 150
Mixosiphonoceras, 610
Mixotermes, 797
Mizalia, 790
Mohergia, 375
Modelia, 529
Modiella, 449
Modiola, 463
Modiolaria, 463
Modiolodon, 462
Modioloides, 439
Modiolopsis, 462
Modiomorpha, 462
Mogulia, 523
Mohrensternia, 545
Moira, 296
Mojsvarites, 651
Molaria, 776
Moltkia, 110
Monachocrinus, 230
Monia, 461
Monmorella, 373

Monobolina, 377

Monoceros, 558

Monocondylaea, 455

Monodacna, 490

Monodonta, 531

Mouograptus, 132

Monoi^hyllites, 650, 651

Monopleura, 478

Monoprion, 132

Monopteria, 448

Monorakos, 727

Monotls, 448

Monotrypa, 339

Monotrypella, 336

Monticulipora, 381

Montlivaltia, 96

Moorea, 738

Moorefieldella, 398

Mopalia, 513

Morio, 554

Mormolucoides, 811

Morphoceras, 664

Mo7-risia, 405

Morfeoii iceras, 672
Mourlonia, 524
Mucronella, 352
Muehlfeldtia, 405
Muelleria, 455
Muensterites, 648
Muensteroceras, 636
Mulinia, 498
Mulletia, 447
Multicavea, 326
Multitubigera, 322
Multizonopora, 326
Muniericeras, 669
Murchisonia, 525
Murex, 558
Musculus, 403
Mutela, 455
Mutiella, 487
Mya, 499
Myacites, 464
Myalina, 449
Myalinodonta, 448
Myalinoptera, 449
Mycetopoda, 455
Mycocrinus, 214
Myelodactylus, 212
Myocaris, 754
Myochama, 467
Myoconcha, 402
Myodora, 467
Myonera, 470
Myonia, 566
Myophoria, 456
Myophoriopsis, 457
Myoplusia, 440
Myopsis, 466
Myrianites, 141
Myriopora, 353
Myriozoum, 353
Myristica, 557
Myrtea, 486
MyrtillocrinuH, 210
Mysidia, 449
Mystrophora, 393
Mytilarca, 445
Mytilops, 449
Mytilopsis, 463
Mytilus, 463

Nacella, 520
Naiadites, 451
Naites, 141
Nannites, 637
Nanno, 596
Nannogouiphus, 810
Nanocrinus, 219
Nanthacia, 799
Naranaio, 494
Naraoia, 733
Narthecoceras, 596
Nassa, 556
Natica, 542
Naticella, 533

Naticopsis, 533
Natiria, 533
Naumacliocrinus, 230
Nautilus, 607
Neaera, 469
Neatretia, 400
Nebalia, 749
Necrocarcinus, 765
Necrogammarus, 759
Necroscilla, 768
Necrotaulius, 814
Nectotelson, 756
Neithea, Abi
Nemagraptus, 130
Nemapodia, 141
Nemastomoides, 791
Nemataxis, 344
Nematocrinus, 214
Neinatopöra, 343
Nematotrypa, 344
Nematura, 545
Nemertites, 141
Nemodon, 442
Neobolus, 372
Neocatillus, 447
Neocatopygus, 290
Neocomites, 668
Neocrinus, 233
Neocystites, 160
Neohindia, 56
Neolampas, 291
Neolenus, 716
Neoliuiulus, 776
Neomegalodon, 454
Neorthophlebia, 813
Neoschizodus, 456
Neothyris, 408
Nephriticeras, 604
Nephrops, 764
Neptocarcinus, 767
Neptnnea, 557
Neptunus, 767
Nereites, 141
Nerinea, 549
Neriuella, 549
Nerita, 534
Neritaria, 534
Neritina, 534
Neritodomus, 534
Neritoma, 534
Neritomopsis, 533
Neritopsis, 534
Neumayria, 603
Neusina, 26
Neverita, 543
Nevvberria, 401
Nicliolsonella, 334
Nicholsonia, 112, 345
Nicomedites, 645
Nieszkowskia, 725
Nileus, 719
Ninella, 529
Nipterclla, 57
Nipterocrinus, 204
Nisusia, 380
Nodelea, 324
Nadicrescis, 326
Nodosaria, 30
Noetia, 443
Noetlingia, 394
Nomismoceras, 631
Norella, 399
Norites, 633
Normann ites, 663
Nothoceras, 613
Nothozoe, 751
Notothyris, 403
Novaculina, 495
Nubecularia, 37
Nucleatula, 401
Nucleocrinus, 171
Nucleolites, 289
Nucleospira, 415
Nucula, 440
Nuculana, 440
Nuculina, 441

INDEX

833

NiirahinUna, 36
NummuUtes, 35
Nuttaliua, 513
Nyassa, 452
Nyctilochus, 555
Nyctopora, 114
Nymphaeoblastus, 172
Nymphaeops, 703
Nyniphalites, 815
Xympliaster, 250
Xystia, 545

OliliqodDi, 452
Obolella, 875
Oholellhm, 373
Obolus, 371
Ochetoceras, G5S
Ücinehrn, 55S
Octoiiaria, 730
Octotremacis, 111
Oeulina, 95
Oculospongia, 71
Odaraia, 750
Odontocems, 6(59
Odontoperna, 447
Odontopleura, 722
OdontotTjipa, 330
Odostomia, 537
Oecoptycliiiis, 665
Oecotraustes, 658
Oedisclila, 798
OchlerteUa, 377
Oesia, 141
Offa, 742
Offaster, 203
Oiiygid, 718, 719
Ogygiocaiis, 718
Ogygites, 710
Ogygopsis, 718
Ohiociinus, 212
Olcostephanus, 664
Oldhaniia, 388
Olenelloides, 714
Olenellus, 714
Olenikites, 647
Olenoides, 716
01«ims, 715
OUcjiicrinus, 206
Oligoponis, 304
Oligotoina, 563
Oliva, 562
Oliv(Hiite'<, 171
Olivella, 562
Ollucriiius, 188
Onuilaxis, 538
Ombonia, 38(;
Ompholia, 546
Omphalocirrns, 527
Omplialophyllia, 10:?
Omphalopteru.s, 543
Oniplialotroclnis, 528
Ompliyiiia, 85
ünchoiiietüpus, 710
Oncliotrocluis, 04
Oncoceras, 611
Oucocliilus, 534
Oncocnnus, 203
Oncodoceras, 606
Oiicomo, 552
Oucopaiia, 7t'i3
Oncophora, 404
Oncospira, 531
Onithochitou, 513
Onycliastor, 255
Onychia, 444
Onychocella, 350
Onychocrinus, 20*!
Onychopterus, 782
Ooceras, 610
Oonia, 537
Oonoceras, 610
Opabinia, 732
Opevculina, 35
Ophiceras, (J45
Ophidioceras, (iOl
Ophileta, 527

VOL. I

Opliioceras, 655
Ophiücoma, 256
Ophiocrinus, 180
Ophiocnnus, 212, 221
I Ophiocten, 256

Ophioderma, 256
j Ophiolepis, 256

Ophiomusium, 256
I Ophlrapliidites, 51
Ophiurella, 256
Ophiurites, 237
I Ophlura, 256
I Opthalmidiimi, 38

Opiliotarbus, 791
I Opis, 473
j Opisoiiia, 473
i Opisthoptera, 445
I Oplophorus, 761

Oppelia, 658
I Oppelismilia, 07

Orbiceila, 08
! OrhiceUa, 377
j Orbiculina, 30
I Orbicnloidea, 377
j Orbignyella, 331
I Orbignyia, 482
\ Orbipecten, 457
' Orbipora, 336
I Orbitoides, 36
Orbitolina, 27
Orbitolites, 30
Orbitremites, 171
Orbulina, 31
Oreaster, 251
OHoi^foma, 528
Oriskania, 401
Ormoceras, 609
Ornithaster, 296
Ornithella, 406
Orocystites, 152
Oropliocrinus, 169
Orozoe, 752
OrtJuiinhonites, 381
Orthaulax, 553
Ortliidium, 385
Orthis, 381
Orthiffina, 392
Ortlioceras, 598
Orthocidaris, 274
Orthocriuus, 187
Orthodesnia, 462
Orthodontiscus, 470
Orthograptus, 130
Orthoidea, 407
Orthonoimiea, 408
Orthonota, 462
Ortlionychia, 541
Orthophlebia, 813
Orthopora, 344
Orthopsis, 276
Orthoptf/chus, 479
Orthorhynchula, 396
Orthostoma, 566
Orthostropliia, 382
Orthotetes, 386
Orthotheca, 571
Oiihothete.% 386
Orthothetina, 387
Orthothrix, 391
Orthotichia, 383
Orthotoiua, 406
Orthotropia, 305
Ortonia, 139
Orusia, 381
Oryctocephahis,
Osculipora, 322
Osiliiius, 531
Osniyliis, 813
Ostracotenthis, 683
Ostrea, 450
Otoceras, 646
OtopoTiia, 540
Otostoma, 534
Ottawacrimis, 215
Ottoia, 141
Otusia, 380

•16

Ovula, 554
Ovulactaeon, 566
Owenella, 521
Owenites, 637
Oxyclymenia, 628
Oxydiscus, 522
Oxygyrus, 536
Oxynoticeras, 660
Oxystele, 531
j Oxytoina, 448
Oxyuropoda, 757

Pachastrella, 51
Pachinion, 59
' Pachycardia, 452
Pachyclypeus, 285
Pachydictya, 346
i Pachydiscus, 667
I Pachydomella, 740
1 Fachydon, 499
i Pachygyra, 101
; Pachylasnia, 747
Pachylocrinus, 222
Pachymagas, 407
I Pachymegalodon, 454
' Pachymytilus, 463
i Pachyphyllum, 86
! Pachypouia, 528
Pacliypora, 114
Pachypteria, 459
1 Pachyrhynchus, 407
I Pachyrisma, 454
Pachystroma, 123
' Pachyteichisma, 65
j Pachyteuthis, 682

Pachytylodia, 71
I Paedeumias, 714
Pagurus, 764
Palaeacis, 106
Palaeacmaea, 520
Palaeamutela, 452
Palaeanodonta, 452
Palaeastacus, 764
Palaeaster, 248
Palaeechinus, 303
Palaega, 758
Palaeinachus, 765
Palaemysis, 757
I Palaeoblattina, 820
' Palaeobolus, 371
Palaeobrissus, 297
Palaeocaiupa, 793
; Palaeocardita, 475
Palaeocaris, 755
Palaeocarpilius, 767
, Palaeochrysa, 813

Palaeoclymenia, 600
! Palaeocöma, 251
! Palaeocorbis, 487
Palaeocorystes, 765
Palaeocrania, 379
Palaeocreiisia, 747
I Palaeocrinus, 217
Palaeocyclus, 82
Palaeocypris, 740
Palaeocystites, 152
Palaeodiscus, 290
j Palaeogainmarus, 759
Palaeogoiiiatites, 630
i Palaeograpsus, 766
' Palaeolampas, 291
! Palaeonianon, 56
I Palaeomya, 484
' Palaeouarica, 533
' Palaeonautüus, 600
' Palaeonectria, 249
I Palaeoneilo, 440
Palaeonisa, 537
Palaeophiura, 254
Palaf'ophoiius, 787
Palaeopinna, 446
Palaeopneustes, 295
Palaeoporites, 112
Palaeopsylla, 817
I Palaeorchestia, 756
: Palaeosaccus, 61

Palaeosceptron, 110
Palaeosolen, 496
Palaeostella, 249
Palaeostonia, 297
Palaeothrip.s, 800
Palaeotropus, 297
Palasterina, 251
Palasteriscus, 251
Paleanatina, 438
Palearca, 442
Palenarthrus, 793
Paleocardia, 445
Paliiigenia, 809
Palinurina, 763
Pallium, 457
Palmocystis, 155
Paltodus, 140
Paltopleuroceras, 659
Paltorhynchus, 805
Pahidiim, 544
Panda, 576
Pandora, 467
Panomya, 500
Panope, 500
Panopea, 500
Panopeus, 767
Papliia, 493, 498
Papyridea, 490
Paracardium, 439
Paraceltites, 640
Paracochloceras, 650
Paractinoceras, 609
Paracyathus, 95
Paracyclas, 485
Paradoxechiniis, 282
Paradoxides. 714
Paragyninites, 645
Parajurvavites, 629
Parakymatites, 644
Parala'nipas, 290
Paralecanites, 644
Paralegoceras, 636
Parallelodon, 441
Parambonites, 393
Paramelania, 548
Paramya, 499
Parannites, 637
Paranomia, 461
Parapachydiscus, 667
Paraparchites, 737
Paraphorhvnchus, 39S
Paraphyllites, 630
Parapopanoceras, 641
Parapronorites, 633
Pararca, 439
Pararcestes, 642
Parastarte, 494
Parastropliia, 394
Parathisbites, 648
Paratropites, 638
Parazyga, 414
Parichthyocrinus, 206
Parisoerinus, 218
Parkeria, 120
Parkinsonia, 665
Parmophorus, 526
Parodoceras, 631
Paroniceras, 657
Paropsis, 448
Parotermes, 804
Paryphostoma, 537
Pasceolus, 72, 160
Passyia, 488
Patella, 520
Patellina, 33
Patelliocrinus, 191
Patellostiuni, 522
Pateiiaria, 322
Pateriiia, 370
Paterula, 372
Patrocardiiun, 444
Pattersonia, 62
Paronaria, 110
ParotuMijera, 322
Paxillosi, 682
i Peachella, 714

3 H

TEXT-BOOK OF PALEONTOLOGY

Peccliiolia, 469
Pecten, 457
Pediilum, 447
Pedicularia, 554
Pedina, 278
Pedinopsis, 277
Peduiii, 458
/Vt,N;/iot'cm,s, üOl
J'fUuiia, 323
Polagodiscus, 378
Pelagothuria, 313
Pelanechinus, 278
Peltairon, 533
Peltastes, 279
Peltocaris, 754
Peltoceras, (565
Peltura, 715
Peniphix, 762
Peiieroplis, 39
Pennutulites, 110
Pemiii-ftepora, 343
Pentaceros, 251
Pentacrinus, 232, 233
Pentactinella, 418
Pentadid, 224
Pentagoiiaster, 249
Peiitagonia, 416
Pentainerella, 395
Pe.ritame.rocenis, 612
Pentamenis, 395
Pentaphylluin, 84
Pentastere, 8!>5
Peiitata, 439
Pentephyllum, 172
Pentremites, 169
Pentremltidea, 169
Pephricaris, 752
Peregrinella, 399
Peieiraea, 552
Perganiidea, 449
Pergensella, 320

Pericosimis, 296

Pericyclus, 636

Periechocrinus, 194

Periglyptocrimis, 190

P«Timecturu.s, 768
Perijietoceras, 606

Peripleurites, 649

Periploina, 467

Periplomya, 466

Peripneiistes, 297

Peripora, 321

Perischocidaris, 306

Perischodomus, 306

Perispliinctes, 663

Peri Stern ia, 560

Perla, 808

Periia, 447

Pernoiieeten, 457

Peniostrea, 447

Pernnella, 69

Peroniceras, 672

Peronidella, 69

Peronoceras, 6(>2

Peroiiopora, 332

Peronopsis, 710

Pwplicaria, 560

Persona, bbb

Petalfixis, 86

Petaloconchus, 547

Petalocrinus, 217

Petalograptus, 130

Petalopora, 324

Petalospyris, 44

Petalotrypa, 337

Petersia, 553

Petigopora, 333

Petigiinis, 718

Potraia, 72

Petrosfer, 248

Petricola, 494

Petricolaria, 494

Petrocraiiia, 378

Pexidella, 418

Phacites, 35

l'hacoceras, 604

Phacoides, 486
Phacopidella, 726
Phacops, 726
Pliaenopora, 345
Pliaenoschisiiia, 168
Plialacroma, 710
Phalangella, 320
Phalaugiotarbus, 791
Phanerotinus, 527
Pharella, 496
Pharetra, 374
Pharetrella, 571
Pliaretriuin, 508
Pharostoma, 724
Phasganocaris, 751
Phasianella, 529
Phasiamis, 529
Phenacoceras, 632
Phenacolepas, 526
Phenacolestes, 811
Phialocrinux, 225
Phidolophora, 353
Philhedra, 378
Philine, 568
Philippiella, 459
Piiilis, 487
Phillippites, 647
Phillipsastrea, 87
Phillipsia, 721
Phillipsocrinus, 197
Philobrya, 449
Philocrinus, 223
Phimocrinus, 209
Phloioceras, 604
Phoenicocrinus, 194
Pholadella, 465
Pholadocaris, 754
Pholadoinya, 466
Pholas, 501
Pholidechinus, 302
Pholidocidaris, 300
Pholidophylluni, 84
Pholidops, 379
Pliolidostropia, 385
Plionnedites, 648
Phormopora, 324
Phormosella, 60
Phorniosoma, 278
Phorus, 543
Plios, 556
Phractopora, 346
Phragmatoecites, 815
Pliragnioceras, 613
Phragmodictya, 61
Phragmolites, 522
Phragmosfoma, 523
Phragmoteutliis, 684
Phragniotlieca, 571
Phreatura, 739
Phrynocrinus, 230
Phryniis, 788
Phryssonotus, 793
Phthonia, 438
Phycticeras, 658
Phyllacanthus, 273
Phyllangia, 98
Phyllobrissus, 290
Phylloceras, 652
Phyllocoenia, 101
Phyllocrinus, 240
Phyllodictya, 346
Pliyllodocites, 141
Phyllofrancia, 322
Phyllograptus, 129
Pliyllonotus, 558
Phyllopoi-a, 341
l'hyUa)K)ri7ia, 340
Phyllosmilia, 100
Phylloteuthis, 688
Phyloblatta, 803
Phyniatella, 54
l'hymatifer, 527
Pliyniechiiins, 277
Pliysa, 574
Pliysetocrinus, 197
Pliysocaris, 751

Pliysodoceras, 666
Physospoiigia, Gl
Phlltocrinuis, 2H7
Phytogyra, 102
Pictetocrlnus, 233
Pictonia, 664
Pikaia, 137, 141
Pileolus, 535
Pileopsis, 541
Püeotrypa, 329
Pileus, 285
Piloceras, 596
Pilocystites, 150
Pimentes, 662
Pinacites, 630
Pinacoceras, 636
Pinacophyllum, 101
Pinacotrypa, 330
Pinna, 446
Pinnatopora, 342
Pinnigena, 446
Pinnocaris, 754
Pionocrinus, 194
Pionodema, 382
Pironaea, 482
Pisanella, 556, 560
Pisania, 556
Pisidiuiii, 475
Pisocrinus, 208
Pithodea, 537
Placenta, 461
Placenticeras, 671
Placiphorella, 513
Placites, 636
Placocoenia, 101
Placocystites, 151
Placoparia, 725
Placophoro])sis, 513
Placophyllia, 100
Placopsilina, 26
Placosmilia, 100
Placima, 461
Placunanoinia, 461
Plaeunema, 461
Placunopsis, 461
Plaesioniys, 382
Plagioglypta, 509 .
Plagioptychus, 479
Plagiostoma, 460
Planaxis, 540
Planctoceras, 600
Planetoceras, 604
Planolites, 141
Planorbella, 570
Planorbis, 574
Planorbulina, 32
Planulina, 33
Plasmopora, 112
Plasmoporella, 112
Platidia, 405
Platyacra, 531
Platybrissus, 295
Platyceras, 541
Platychilina, 534
Platychonia, 58
Platyclymenia, 628
Platycrinus, 199
Platycystis, 150
Platynietopus, 721
Platymya, 466
Platyodon, 499
Platyostonia, 541)
Platyperla, 808
Platyschisnia, 527
Platystrophia, 381
Plaxiphora, 513
Plecotrema, 574
Plectaiiibonites, 384
Plectella, 384
Plectoceras, 601
Plectoderma, 61
Plectodermatium, 67
Plectodon, 470
Plectomya, 466
Plectorthis, 381
Pleiodon, 455

I Plesiastraea, 98
j Plesiocyprina, 472
J'lesiüdicenis, 477
Ple.siolampas, 291
Plesiosira, 791
Plesioteuthis, 688
Plesiothyiis, 407
Plethoniytiliis, 445
; Plethopora, 326
j Plethorhyncha, 397
! Plethospira, 525
! Pleurocaris, 756
i Pleurocera, 548

Pleuroceras, 548, 659
j Pleurocora, 97

Pleurucrinus, 199
i Pleurocteniuni, 710
i Pleurocystites, 154
' Pleuiodiadema, 277
! Pleurodictyum, 114
Pleuiodonta, 439, 576
Pleuiolytoceras, 652
Pleuioineris, 476
Pleuroniya, 464
Pleuronautilus, 606
Pleuronotus, 527
Pleiirophorus, 471
Pleurorhynchus, 446
Pleurostonia, 64
Pleurotoma, 563
Pleurotomaria, 524
Plicatocrinus, 238
Plicatula, 459
PI killen t, 418
J'lii'omyd, 466
Plintliosella, 55
Pliomera, 725
Pliomerops, 725
Pliorhytis, 495
Plocophyllia, 101
Plocoscvphia, 67
Pluniatella, 354
PlumafeUites, 354
PJumuIifes, 744
Plychophyllum, 85
Plychospira, 414
Poeillopora, 9ö
Poculina, 570
Podagrion, 811
Podocidaris, 281
PodoCTates, 763
Podocyrtis, 44
Poecilasma, 745
Poecilomorphus, 658
Poliniees, 543
Pollia, Ö56
Pollicipes, 745
Pollingeria, 187, 142
Polorthus, 501
Polyblastidiuni, 66
PoJycerus, 232
Polyclieles, 761
Polycidaris, 274
Polycoelid, 69, 82
Polycyclus, 649
Polycyphus, 278
Polydonta, 531
Polygnathus, 140
Polygono.sphaerite.s, 72
Polygyra, 576
PoIy.ierea, 55
PulyUpas, 745
Polymarai)hinina, 54
Polymorphina, 31
Polymorphites, 657
I Polyochera, 789
I Polyodontd, 574
j Polyosepia, 64
! J'olypeltes, 190
I Polypliemoiisis, 537
j Polyphyllia, 102
j Polyphynia, 735
j Polyi)lectu.s, 660
I Polypoi-a, 341

Polyptchite.s, 664
I Polyschide.s, 510

ä

INDEX

835

Polysolenia, 111
Polystomella, 34
Polytaxia, 325
Polytoechia, 393
Polytrerna, 326
Polytremacis, 111
Polytremaria, 525
Polytropis, 528
Polyxenus, 792
Pomatias, 540
Pomatocrinus, 231
Pamatograptus, 132
Pomatospirella, 418
Pomocystis, 155
Pontocypris, 740
Popanoceras, 641
Porcellia, 524
Porella, 352
Poricella, 353
Porina, 352
Poristoma, 353
Porites, 107
Porocidaris, 273
Porocrinus, 160, 217, 225
Poromya, 469
Porosphaera, 121
Porospongia, 65
Portlockia, 539
Portunites, 767
Posidoniella, 449
Posidonomypa, 449
Potamides, 550
Potamobius, 764
Potainomya, 499
Potamon, 767
Poterioceras, 611
Poteriocrinus, 222
Potoceras, 606
Pourtalesia, 298
Praeanaspüles, 755
Praearcturus, 758
Praecardium, 439
Praeglyphloceras, 636
Praelima, 439
Praelucina, 439
Praesphaeroceras, 662
Prasina, 464
Prasopora, 332
Preatya, 763

Preconia, 472

Prenaster, 296

Prestwichia, 774

Priamus, 561

Primitia, 738

Primitiella, 737

Priinnoa, 110

Prionastrea, 98

Prioniodus, 140

Prionomyrmex, 806

Prionotropis, 672

Priscochiton, 512

Prismodictya, 60

Prismopora, 346

Pristiograptiis, 132

Proarcetes, 642

Proavites, 644

Probeloceras, 631

Probolaenm, 512

Probolium, 726

Proboscidella, 391

Proboscina, 319

Procardia, 466

Procarnites, 635

Procercopis, 819

Procerites, 663

ProcliiKicrinus, 213

Prodromites, 634

Prodryas, 815

Producta, 390

Productella, 389

Productus, 390

Proetus, 721

Proflscheria, 474

PrographuJarifi, 110

Prohemerobius, 813

Proidotea, 758

VOL. I

Proisocrinus, 232
Projovellania, 610
Proleanites, 632
Prolibyhea, 815
Prolimulus, 774
Prolobella, 462
Prolobites, 629
Prolucina, 486
Prolystra, 815
Promacnis, 438
Promathilda, 537
Promedlicottia, 633
Promelocrinus, 190
Pronannites, 636
Pronites, 392
Pronoe, 492
Pronoella, 492
Pronorites, 633
Propeamusium, 458
Propinacoceras, 633
Proplanulites, 664
Proptychites, 645
Propygope, 404
Proricaris, 754
Prorokia, 472
Proscorpius, 788
Prosocoelus, 472
Prosodacna, 490
Prosopon, 765
Prosostheiiia, 545
Prospondylus, 469
Prosserella, 412
Protalochiton, 512
Protaraea, 112
Protaster, 254
Protasteracanthion, 249
Protaxocrinus, 205
Proteocystites, 156
Proteroblastus, 156
Proterocidaris, 306
Protetraclis, 53

Prot/cusites, 640
Protholoturia, 313
Prothyris, 438
Protichnites, 142
Proto, 546
Protobactrites, 599
Protobalaims, 746
Protocardia, 490

Protocaris, 732
Protocidaris, 306

Protocimex, 820

Protocrinites, 156

Protocrisina, 320

Protocycloceras, 599

Protocystis, 151

Protodiceras, 454

Protolimulus, 774

Protolindenia, 810

Protolycosa, 790

Protoma, 546

Protomya, 439

Protonerita, 534

Protonia, 390

Protopalaeaster, 248

Protopharetra, 105

Protophasma, 801

Protophragmoceras, 612

Protopilio, 791

Protoretepora, 341

Protorhynclia, 396

Protorthis, 380

Protoschizodus, 472

Protoscolex, 137

Protosiphon, 376

Protosolpuga, 789

Protospongia, 60

Protosycon, 71

Protowarthia, 521

Protozyga, 408

Protrachyceras, 648

Proutella, 347

Pruiiocystis, 155

Psammhelia, 95

Psamniobia, 495

Psammocarcinus, 767

Psammosolen, 495
Psecadia, 815
Pselioceras, 606
Psephidia, 494
Pseiulalaria, 549
Pseudamusium, 458
Pseudedmondia, 484
Psetbderiphyla, 474
Pseudoastacus, 763
Pseudobelus, 682
Pseudocerithium, 549
Pseudochaetets, 118
Pseudocidaris, 275
Pseudocrania, 379
Pseudocrintes, 153
Pseudocythere, 739
Pseudodiadema, 277
Pseudodiceras, 477
Pseudofossarus, 533
Pseudogalathea, 757
Pseudoglossothyris, 404
Pseudoglyphaea, 762
Pseudohornera, 340
Pseudokingena, 406
Pseudolingula, 374
Pseudoliva, 556<
Psexxdomelania, 537
Pseudometoptoma, 378
Pseudomonotis, 448
Pseudonautilus, 603
Pseudonerinea, 549
Pseudoniscus, 777
Pseudopedina, 278
Pseudoplacuna, 461
Pseudoplocoscyphia, 54
Pseudosageceras, 634
Pseudoscalites, 539
Pseudosirex, 806
Pseudosphaerexochus, 725
Pseudosquilla, 768
Pseudostichopus, 313
Pseudotoma, 563
Pseudotropites, 660

Pseudozampe, 820

Psiloceras, 655

Psilodon, 490

Psilomya, 469

Ptenoceras, 605

Pteria, 447

Pt^riiicopecten, 457

Pterinea, 444

Pterocaris, 754

Pterocera, 552

Pterocerella, 551

Pterochiton, 512

Pterocodon, 44

Pterocoma, 237

Pterocrinus, 230

Pterodonta, 552

Pteronautilus, 606

Pteronites, 448

Pteronotus, 558

Pteroperna, 448

Pterophloios, 389

Pteropora, 346

Pteropsis, 498

Pterotheca, 571

Pterotocrinus, 201

Pterygometopus, 727

Pterygotus, 784

Ptilocella, 346

Ptilocrinus, 238

Ptilodictya, 344

Ptilograptus, 128

Ptilopora, 342

Ptiloporella, 342

Ptiloporina, 342

Ptilotrypa, 345

Ptychagnostus, 710

Ptycharcestes, 642

Ptychites, 637

Ptychocaris, 752

Ptychoceras, 653

Ptychocladia, 318

Ptychocrinus, 187

Ptychodesma, 449

Ptychomphalus, 524
Ptychomya, 474, 493
Ptychonema, 339
Ptychoparia, 715
Ptychoijyge, 719
Ptychostoma, 536
Ptychostylus, 548
Ptygmatis, 549
Ptyssoceras, 605
Puella, 439
Pugiunculus, 571
Pugnax, 398
Pugnellus, 552
Pugnoides, 398
Pugnus, 567
Pulchellia, 671
Pullastra, 493
Pulsellum, 510
Pulvinulina, 33
Puncturella, 526
Pupa, 576
Pupillaea, 526
Purpura, 558, 558
Purpurina, 539
Purpuroidea, 539
Pustularia, 537
Pustulopora, 320
Puzosia, 667
Pycinaster, 250
Pycnocrinus, 189
Pycnodonta, 450
Pycnolithus, 112
Pycnomphalus, 532
Pycnopegma, 56
Pyciiophyllum, 84
Pycnosaccus, 203
Pygaster, 285
Pygaulus, 289
Pygites, 403
Pygocardia, 472
Pygocephalus, 756
Pygope, 403
Pygorhynchus, 290
Pygurus, 291
Pyramidella, 537
Pyrazus, 550
Pyrenella, 550
Pyrgia, 116
Pyrgidium, 545
Pyrgoma, 747
Pyrgula, 545
Pyrgulifer, 547
Pyrgulifera, 547
Pyricavea, 326
Pyrina, 289
Pyritonema, 62
Pyrocystites, 150
Pyrogopolon, 508
Pyrula, 555^ 557
Pythina, 488
Pythiopsis, 574
Pyxidocrinus, 194
Pyxis, 390

Quebecia, 375
Quenstedtia, 116, 494
Quenstedtoceras, 663
Quinqueloculina, 38
Quoyia, 540

Radiocavea, 326
Radiofascigera, 323
Radiolites, 481, 482
Radiopora, 326
Radula, 460
Rafinesquina, 384
Ramulina, 31
Ranella, 555
Rangia, 498
Raniella, 765
Raiiina, 765
Raninoides, 765
Rapaiia, 558
Raphidia, 812
Raphiojjhorus, 712
Raphistoma, 527

3 H 2

836

TEXT-BOOK OF PALEONTOLOGY

3LM

Rajilii.st(>i
Kai-liistoinina, iVJ»
liiiphitoma, i>Oi
Rastrites, 132
Receptaculites, 72
Jieckur, 769
Recula, 797
Redlichella, 376
Redonia. 440
Regina, '431)
ReifliiiKi1>'s. t)4T
Reiiieckia, 665
Remeleoceras, 607
Remondia, 474
Remopleurides, 717
Rensselaeria, 400
liensselandia, 401
Reo])]iax, 25
Rci.taria, :5-20
R.'l.t.'l.'a, 824
Reptuciivea, 324
Reptocea, 323, 326
Reptoceritites, 324
Rpptofascigera, 320
Rt'ptoiiuilticava, 326
Rf])r()inultielausa, 325
Reptomulti.sparsa, 320
Requienia, 477
Retecava, 320
Jietelm, 325
Retenoa, 322
Reteocrinus, 186
Retepora, 353
Reteporina, 342
Reticularia, 412
Reticiilipora, 325
Retiograptus, 131
Retiolites, 132
Retusa, 568
Retzia, 414
Rhabdammina, 24
Rhabdoceras, 649
Rhabdocidaris, 273
Rhabdomeson, 343
Hhabdophyllia, 99
Rhabdopleura, 539
Rliabdosispongia, 60
Rhabdus, 509
Rliacodiscula, 55
Rhacophyllites, 652
Rhadinoceras, 604
Rhadinocrinus, 221
Rhaetina, 403
Rhagadinia, 55
Rhagasostoma, 351
Rhaphanocrinus, 187
Rhaphidonema, 71
Rhectocyma, 472
Rhinacantha, 568
Rhinecei-as, 604
Rhinidictya, 345
Rhinobolus, 373
Rhinobrissus, 297
Rhinocaris, 753
Rhinoclama, 470
Rhinopora, 347
Rhipidocardium, 446
Rhipidocrinus, 189
Rhipidocystis, 150
Rhijndogorgia, 110
Rhipidogyra, 102
Rhipidomella, 382
Rliipiodomys, 382
RhipidoiK>ra, 321
Rhizammina, 24
Rliizangia, 97
Rhizocriims, 229
Rhizophyllum, 88
Rhizoporidium, 121
Rliizopoterion, 66
Rhizostomites, 134
Rhodaraea, 106
Rliodocrimis, 188
Rhodopliyllum, 86
Rhoechinus, 806
Rhombifera, 207

Rhonibina, 741
Rhombopora, 343
Rhombopteria, 444
Rhombotrypa, 337
Rhopalocoma, 251
Rliopalocriiius, 206
Rhopalonaria, 317
Rhynchidia, 533
Rhvnchomya, 466
RliVHclionella, 398
Rhvnchonellina, 399
Kliynchopora, 398
lihynchojmrina, 398
Rhynchora, 408
Rhynchorina, 408
Rhynchorthoceras, 601
Rhynchospira, 414
Rhynchostreon, 450
Rhynchotetra, 398
Rhynchotrema, 396
Rhyncliotreta, 397
Rhyiieopygus, 290
Rhytimya, 465
Ribeirella, 732
Ribeiria, 732
Riclithofenia, 391
Ricinula, 558
Rimella, 553
Rimula, 526
Ringicula, 567
Ringinella, 567
Rissoa, 546
Rissoina, 545
Rizoceras, 610
Rocellaria, 500
Roemeraster, 251
Roemerella, 378
Roemerispongia, 61
Roemeroceras, 671
Romingeria, 116
Romingerina, 401
Rostellaria, 552
Rostellites, 561
Rostranteris, 403
Rotalia, 33
Rotella, 532
Rotellina, 532
Rotlipletzia, 541
Rotula, 288
Rouaiiltia, 563
Roudairia, 471
Rowleyelli, 403
Rima, 287
Rupertia, 33
Rustella, 370
Rutoceras, 603
Rutotia, 448
Ryderia, 469
Ryticeras, 603

Saccammina, 25
Saccohlastus, 170
Saccocaris, 751
Saccocoma, 239
Saccocrinus, 194
Saccorhiza, 25
Saccospongia, 57
Sactoceras, 608
Sagda, 576
Sageceras, 634
Sagenites, 639
Sagenina, 25
Sagenocrinus, 204
Sagitta, 135
Saintia, 461
Salenia, 279
Salicornaria, 348
Salmacis, 282
Salpingostoma, 521
Saiteraster, 249
Salterella, 572
Saniiisonocrinus, 197
Sandbergeria, 550
Sandlingites, 648
Sanguinolaria, 495
Sanguinolites, 438

Sannionites, 595
Sao, 715
Sarmaticus, 529
Saxicava, 499
Saxidomus, 493
Scaccliinella, 387
Scaevola, 531
Scalaria, 538
Scalaripora, 346
Sealdia, 484
Scalites, 527
Scalpellum, 745
Scambula, 474
Scapha, 561
Scapliander, 568
Scaplianidia, 533
Scapharca, 443
Scaphella, 561
Scaplieus, 763
Scaphiocoelia, 401
ScapMocrinus, 222, 225
Scaphites, 670
Scaphula, 443
Scarabus, 574
Scenella, 520
Scenellopora, 328
Scenidium, 393
Sceptropora, 343
Scliellwienella, 386
Schiosia, 479
Schistoceras, 636
Schistoi)hyllocera.s, 652
Schizambou, 376
Schizamhonia, 376
Schizaster, 296
Schizoblastus, 171
Schizobolus, 377
Schizochiton, 513
Schizocrania, 377
Schizocrinus, 189
Schizocystis, 155
Schizodentalium, 509
Schizodesma, 498
Schizodiscus, 524, 735
Schizodus, 456
Schizogonium, 525
Schizolopha, 525
Schizonema, 382
Schizopholis, 375
Sehizoplioria, 383
Schizoplax, 513
Schizoporella, 352
Schizoramma, 382
Schizorhabdus, 66
Schizostoma, 353, 527
Schizothaerus, 498
Schizotreta, 378
Schloenbachia, 672
Schlotheimia, 657
Schlueteria, 667
Schmidtella, 737
Schmidtia, 371
Schroederoceras, 600
Schuchertella, 386
Schuchertina, 370
Schultzicrinus, 219
Schwagerina, 33
Sclntilla, 488
Scipionoceras, 654
Sclerocrinus, 240
Scolecoderma, 141
Scoliocystis, 155
Scoliostoma, 538
Scolithus, 141
Scolocystis, 157
Scolopendra, 793
Sconsia, 555
Scrobicularia, 495
Scrupocellaria, 348
Sculda, 769
Scurria, 520
Scutella, 287
Scutellina, 287, 526
Scutus, 526
Scyllaridia, 763
Scyphocrinus, 160, 190, 215

Scytalia, 59
Scytalocrinus, 224
Sebargasia, 71
Sedgwickia, 439
Seebachia, 473
Seeleya, 525
Selenaria, 350
Selenella, 401
Selenopeltis, 723
Selenopora, 330
Seliscothon, 59
Selkirkia, 136
Sellaclymenia, 628
Semele, 495
Semicava, 326
Semicea, 323
Seniiclausa, 320
Semicoscinium, 341
Semielea, 324
Seniifascipora, 321
Semimulticavea, 326
Seminula, 395, 418
Semiopora, 346
Semiplicatula, 461
Senectus, 529
Sepia, 686
Septameroceras, 612
Septifer, 463
Septopora, 342
Seraphs, 552
Seriatopora, 96
Serietubigera, 321
Serpula, 137
Serpulites, 139
Serripes, 490
Sestromostella, 71
Setosella, 351
Shumardella, 398
Shumardia, 711
Shumardites, 642
Sibirites, 640
Sicanites, 633
Sicyocrinus, 221
Siderastrea, 103
Sidneyia, 786
Sieberella, 395
Siemiradzkia, 666
Sigaretus, 542
Sigmacystis, 151
Silbyllites, 638
Silenia, 469
Silesites, 667
Silia, 562
Siliqua, 496
Siliquaria, 547
Siluraster, 249
Silurina, 439
Simbirskites, 664
Simoceras, 666
Sinuites, 521
Sinum, 542
Siphodictyum, 324
Siphonalia, 557
Siphonaria, 573
Siphonentalis, 510
Siphonia, 54
Siphonocoelia, 69
Siphonocrinus, 187
Siphonodentalium, 510
Siphonotreta, 375
Siphoniotyphlus, 321
Sirenites, 648
Sismondia, 287
Sistrum, 558
Slimonia, 783
Smaragdinella, 568
Smilotrochus, 94
Smittia, 352
Smittina, 352
Smittipora, 351
Smittistoma, 353
Solanocrinus, 237
Solariella, 532
Solarium, 538
Solecardia, 488
Solemya, 438

INDEX

837

Solen, 496
Solenastrea, 98
Soleniscus, 538
Solenocaris, 751
Solenocheilus, 606
Solenopleura, 716
Solenopsis, 438
Solenospira, 525
Solidula, 565
Sollasella, 54
Sollasia, 71
Sonneratia, 668
Sonuinia, 660
Sowerbiceras, 652
Sowerbya, 496
Spanila, 444
Spaniodera, 798
Spaniodon, 488
Sparsicavea, 324
Sparäicytis, 326
Spatagocystis, 298
Spatangopsis, 134
Spatangus, 297
Spatha, 455
Spathiocaris, 754
Spatiopora, 329
Speo, 565
Sphaenia, 499
Sphaera, 487
Sphaeraetinia, 120
Sphaerechinus, 282
Sphaerella, 487
Sphaerexochus, 725
Sphaeriola, 487
Sphaerium, 475
Sphaerobolus, 371
Sphaerocaprina, 479
Sphaeroceras, 663
Sphaerocoelia, 71
Si^haerocoryphe, 725
Sphaerocriuus, 196, 218
Sphaerocystites, 154
Sphaeroldina, 31
Sphaeronites, 155
Sphaeropsocus, 804
Sphaerulites, 482
Sphenaulax, 64
Spheniopsis, 470
Sphenodiscus, 671
Sjihenomya, 439
Sphenopoterium, 106
Sphenotrochus, 94
Sphingites, 642
Sphyradoceras, 601
Spiloblattina, 803
Spinigera, 551
Spiractinella, 62
Spirialis, 570
Spirifer, 410
Spiriferella, 410
Spiriferina, 413
Spirigera, 417
Spirigerella, 418
Spirigerina, 409
Spirillina, 32
Spiroceras, 670
Spiroclausa, 325
Spirocolex, 141
Sjnrocyathus, 105
Spirodentalium, 508
Spiroloculina, 38
Spirophyton, 141
Spiroplecta, 27
Spiropora, 320
Spirorbis, 138
Spirostylus, 537
Spirula, 685
Spirulirostra, 685
Spirulirostrina, 685
Spisula, 497
Spondylobolus, 372
Spondylus, 459
Spongilla, 51
Spongiochiton, 513
Spoiigiomorpha, 106
Spongiostroma, 124

SpoTigites, 353
Spongophyllum, 86
Sporadoceras, 631
Sporadopyle, 64
Sporadosciuia, 66
Sportella, 488
Spyridiocrinus, 191
Spyroceras, 600
Squama, 745
Squamularia, 412
Squilla, 768
Stachella, 523
Stacheoceras, 641
Stachyodes, 124
Stachyspongia, 59
Staliola, 545
Stauranderaster, 251
Stauria, 87
Staurocephalus, 725
Staurocystis, 154
Stauroderma, 65
Staurolonche, 42
Staurosoma, 158
Stavelia, 463
Stearnsia, 474
Stearoceras, 604
Steganoblastus, 160
Steganocrinus, 197
Steganoporella, 351
Stegerhynchus, 397
Steinmannites, 648
Stelidiocrinus, 189
Stellipora, 334
StelUporella, 112
Stellispongia, 70
Stellocavea, 326
Stelloria, 99
Stemmatocrinus, 225
Stenarcestes, 642
Stenarthron, 788
Stenaster, 249
Stenochirus, 763
StenocJiisma, 396
Stenocrinus, 212
Stenodictya, 796
Stenogomphus, 810
Steuoraphalus, 558
Stenonia, 294
Stenopoceras, 606
Stenopora, 335
Stenosmilia, 101
Stenotheca, 541
Stenothyra, 545
Stephanites, 640
Stephanoceras, 663
Stephanocidaris, 273
Stephanocoenia, 101
Stephanocrinus, 207
Stephanophyllia, 105
Stereocrinus, 191
Stereopsamniia, 106
Steueroceras, 669
Stiboria, 99
Stichocystis, 152
Sticliopora, 350
Stictocella, 346
Stictopora, 345, 346
Stictoporella, 345
Stictoporidra, 346
Stictoporina, 345
Stictotrypa, 347
Stigraatopygus, 290
Stirechinus, 282
Stirjmlina, 468
Stoliczkaria, 121
Stolleya, 51
Stolopsyche, 815
Stolzen burgiella, 418
Stomatella, 528
Stomatia, 528
Stomatopora, 319, 319
Stomatopsis, 547
Stomechinus, 278
Stonionopneustes, 281
Stortingoeriiius, 209
Strabops, 781

Stramentum, 745
Straparollina, 527
StraparoUus, 527
Strebljtes, 659
Streblotrypa, 344
Strenoceras, 665
Strenuella, 717
Strephodes, 87
Strepsidura, 557
Streptaster, 159
Streptelasma, 82
Streptis, 387
Streptoceras, 611
Streptocrinus, 221
Streptorhynchus, 387
Strepula, 738
Striatopora, 114
Stribalocystis, 153
Stricklandinia, 395
Strigatella, 560
Strigilla, 494
Strigocaris, 751
Strigoceras, 658
Stringocephalus, 401
Strohaeus, 536
Strobilepsis, 744
Strobilocystites, 154
Strobüospongia, 62
Stroboceras, 604
Stromatocystis, 159
Stromatomorpha, 106
Stromatopora, 123
Stromatoporella, 124
Stromatotrypa, 339
Strombodes, 86
Strombus, 552
Strongylocentrotus, 282
Strophalosia, 391
Stropheodonta, 385
Strophiceras, 603
Strophocheilus, 576
Strophocrinus, 217
Strophomena, 386
Strophonella, 385
Strophostoma, 540
Strophostylus, 530
Strotocrinus, 198
Strotopora, 330
Struthiolaria, 552
Studeria, 290
Stuorella, 524
Sturia, 637
Stylaraea, 112
Stylaster, 120
Stylastraea, 98
Stylaxis, 86
Stylina, 100
Styliola, 570
Stylocoenia, 101
Stylocora, 97
Stylocrinus, 209
Stylodictyon, 124
Stylohelia, 96
Stylonurus, 783
Stylopliora, 96
Stylophyllopsis, 97
Stylophyllum, 97
Stylotrochus, 94
Styracoteuthis, 683
Subclymenia, 604
Subemarginula, 526
Subulites, 537
Suecoceras, 595
Suessia, 413
Sulcocava, 320
Sulcuna, 741
Sunetta, 492
Supercytis, 323
Surcula, 563
Sutneria, 663
Swantonia, 392
Sycoceras, 611
Sycocystites, 154
Sycum, 559
Symbathocrinus, 209
Symphyllia, 99

Symphysurus, 719
Symphytocrinus, 239
Sympterura, 255
Synaphe, 738
Synapta, 313
Syncyclonema, 458
Syndosmya, 495
Synerocrinus, 205
Synhelia, 95
Synocladia, 342
Synodontites, 482
Synopella, 71
Syntrielasma, 383
Syntrophia, 392
Sypharoptera, 807
Syringoceras, 602
Syringocrinus, 151
Syringolites, 114
Syringopleura, 411
Syringopora, 116
Syringosphaeria, 121
Syringospira, 411
Syringostroma, 124
Syringothyris 411
Syrnola, 537
Systrophoceras, 601

Taeniaster, 249
Taeniodictya, 345
Taeniopora, 346
Tagelus, 495
Tainoceras, 605
Talarocrinus, 201
Tanaocrinus, 193
Tancredia, 484
Tanysiphon, 494
Taonurus, 141
Tapes, 493
Tarphyceras, 600
Tarsophlebia, 810
Tarsopterus, 784
Tauredon, 804
Taurinia, 556
Tauroceras, 453
Taxocrinus, 205, 206,
Taxonus, 806
Tealliocaris, 757
Technocrinus, 191
Technophorus, 733
Tecticavea, 325
Tectura, 520
Tectus, 531
Tegula, 532
Tegulifera, 391
Teinostoma, 532
Telescopium, 550
Teliocrinus, 197
Tellidora, 494
Tellina, 494
Tellinomya, 440
Tellinopsis, 439
Temnechinus, 282
Temnocheilus, 605
Temnocidaris, 274
Temnocrinus, 204
Temnopleurus, 282
Temnotropsis, 525
Tenea, 487
Tenka, 444
Tentaculites, 572
Tenthre<lo, 806
Terataspsis, 722
Terebella, 138
Terebellaria, 325
Terebellum, 552
Terebra, 562
Terebratalia, 406
Tere-bratella, 408
Terebratula, 403
Terebratullna, 404
Terebratuloidea, 398
Terebripora, 317
Terebrirostra, 406
Teredina, 501
Teredo, 501
Teredolltes, 501

838

Terquemia, 451
Tessarolax, 551
Tethyopsis, 51
Tetinka, 444
Tetracamera, 398
Tetrachela, 762
Tetracidaris, 274
Tetnicrinus, 540
Tetractinella, 418
Tetracystis, 154
Tetradella, 738
Tetragonites, 652
Tetragonoceras, 606
Tetragraptus, 129
Tetrameres, 612
Tetrameroceras, 612
Tetramorion, 612
Tetranota, 522
Tetrapygus, 281
Tetraster, 248
Tetrataxis, 29
Teiithopsis, 688
Textularia, 27
Thais, 558
Thalamopora, 33, 71
Thalas.sina, 764
ThwLdbSsites, 452
Tlialassoceras, 637
Thalassocrinus, 238
Thaleops, 720
Th'ülocrinus, 199
Thamnasteria, 103
Thamnastrea, 103
Thamniscus, 341
Thamnodictya, 61
Thamnophyllum, 84
Tliamnotrypa, 346
Thaumastocoelia, 71
Theca, 571
Thecidea, 365, 388
Thecidella, 388
Thecidiopsis, 388
Thecidium, 388
Thecocyathus, 95
Thecocyrtella, 413
Thecocystis, 159
Thecosiphonia, 55
Thecosrailia, 99
Thecospira, 419
Thecostegites, 117
Theiphusa, 767
Thenarocrinus, 215
Theoiioa, 322
Thetsitea, 552
Thiara, 547
Thiemella, 382
Thiolliericrinus, 234
Thlipsura, 739
Tholiasterella, 62, 63
Tholopora, 326
Thomasina, 374
Thomisus, 790
Thoracoceras, 600
Thracia, 467
Thrinoceras 604
Thrips, 800
Thurammina, 25
Thurmannia, 669
Thyasira, 487
Thylacocrinus, 189
TliylaccKles, 547
Thysanocenis, 652
Thymnocrinus, 187
Tliysanodictya, 61
Thysanopeltis, 720
Tkysanotus, 371
Tiaiticrinus, 158
Tiarechinus, 298
Tibetites, 635
Tibtelta, 571
Ticfiogonia, 463
Tilesia, 322
Timanites, 631
Tindaria, 441
Tinoporus, 33
Tirolites, 648

TEXT -BOOK OF PALEONTOLOGY

Tissotia, 671
Titanocarcinus, 767
Tityus, 788
Tivela, 493
Tmaegoceras, 655 '
Tolypammina, 25
Tomocheilus, 539
Tonicella, 513
Tonicia, 513
Tonna, 555
Torellella, 572
Torinia, 538
Tormocrinus, 241
Tornatella, 565
Tornatellea, 565
Tornatina, 568
Tornoceras, 630
Torynifer, 398
Torynocriniis, 240
Toucasia, 477
Tournoueria, 545
Toxaster, 294
Toxometra, 237
Toxopneustes, 282
Trachyceras, 648
Traehydermon, 513
Trachydomia, 539
Trcwhynerita, 539
Tiachyodon, 513
Trachypora, 114
Trachysagenites, 639
Trachyteuthis, 687
Tragophylloceras, 652
Trapezium, 472
Trauvmtocrinus, 225
Tremabolites, 68
Tremadictyon, 63
Trematella, 335
Trematis, 377
Trematobolus, 376
Trematoceras, 604
Trematocystis, 155
Treinatodiscus, 604
Trematonotus, 521
Trematopora, 339
Trematopygus, 290
Trematospira, 414
Tremopora, 349
Treposella, 738
Trepospira, 525
Tresus, 498
Tretaspis, 711
Tretoceras, 609
Tretospira, 539
Triacrinus, 208
Triadosialis, 811
Triainoceras, 633
Triarthrus, 715
Tribachiocrinus, 224
Tribliocrinus, 191
Triboloceras, 604
Trichasteropsis, 249
Trichites, 446
Trichiulus, 793
Trichopteridium, 814
Tricoelocrinus, 170
Tridacna, 490
Triforis, 550
Trigeria, 401, 414
Trigondictya, 346
Trigonella, 406
Trigonellina, 405
Trigonia, 467
Trigonoceras. 604
Trigonocoelia, 442
Trigonocrinus, 241
Trigonocystis, 150
Trigonodus, 452
Trigonosemus, 406
Trigonotarbus, 791
Trigonotreta, 410
Trigonulina, 409
Triloculina, 38
Trimerella, 373
Trimeres, 612
Trimerocephalus, 726

Trimeroceras, 612
Trimerocystis, 154
Trimerus, 724
Trimorion, 612
Trinacria, 442
Trineynacystis, 152
Trinucleus, 711, 711
Triodonta, 474
Triplecia, 387
Tripleuroceras, 610
Triplosoba, 808
Tripneustes, 282
Triptera, 571
Tripylus, 296
Triton, 555
Tritonalia, 558
Tritonidea, 556
Tritoniuvi, 555
Trivia, 554
Trochalia, 548
Trochammina, 26
Trochamminoides, 26
Trochiliopora, 326
Trochiscolithus, 112
Trochoceras, 605
Trochocrinus, 194
Trochocyathus, 94
Trochocystites, 150
Trochoderma, 313
Trocholites, 600
Trocholitoceras, 600
Trochonema, 530
Trochoseris, 102
Trochosmilia, 99
Trochotoma, 525
Trochus, 531
Troostocrinus, 170
Tropaeum, 653
Trophon, 558
Tropiceltites, 640
Tropidocaris, 752
Tropidoleptus, 385
Tropidomya, 470
Tropidopora, 344
Tropites, 638
Truncaria, 557
Truncatula, 323
Truiicatulina, 33
Tryblidium, 521
Tschernyschewia, 390
Tubina, 541
Tugonia, 499
Tulotoma, 544
Turbina, 531
Turbinaria, 108
Turbinella, 560
Turbinilopsis, 539
TurUnocrinus, 190
Turbinolia, 94
Turbo, 528
Turbonellina, 531
Turbonilla, 537
Turbonitella, 539
Turnus, 501
Turonia, 55
Turricula, 560
Turrilepas, 744
Turrilites, 654
Turris, 563
Turritella, 546
Turritoma, 525
Turtonia, 488
Tuzoia, 750
Tyleria, 467
Tylocrinus, 195
Tylopoma, 544
Tylopterus, 783
Tympanotoma, 550
Typhis, 558
Tyrbula, 799

Udora, 761
Udorella, 761
Uintacrinus, 236
Ulangia, 98

Ulocrinus, 224
Ulrichia, 738
Umbonium, 532
Umbraculum, 568
Umbrella, 568
Umbrellina, 321
Uncinella, 413
Uncinulina, 398
Uncinulus, 397
Uncites, 413
Undularia, 536
Ungula, 371
Ungulina, 487
Ungulites, 371
Unicardiuni, 484
Unicrisia, 318
Unicytis, 323
Unio, 454
Uniocardium, 490
Unionia, 452
Unitrypa, 341
Uperocrinus, 196
U'phantaenia, 61
Uranoceras, 608
Urda, 758
Urechinus, 294
Uronectes, 756
Ussuria, 637
Uvanilla, 528
Uvigerina, 31

Vaginella, 571
Vaginoceras, 595
Vaginopora, 353'
Vaginulina, 30
Valenciennesia, 573
Valletia, 478
Valvata, 544
Valvatina, 570
Valvulina, 29
Vanuxemia, 442
Vasocrinus, 218
Vasseuria, 683
Vasum, 560
Velates, 534
Velorita, 474
Veloritina, 474
Venericardia, 475
Venerupis, 494
Veniella, 472
Venilicardia, 472
Ventriculites, 65, 71
Venus, 492
Vermetus, 546, 546
Vermiceras, 655
Vermicularia, 546
Verneuilia, 412
Verruca, 746
Verrucocoelia, 64
Verruculina, |59
Vertebralina, 39
Verticordia, 469
Vertigo, 576
Vertumnia, 448
Vesicomya, 491
Vestinautilus, 604
Vevoda, 438
Vexillum, 141
Vibracella, 351
Vicarya, 550
Villorita, 474
Vincularia, 350
Vinella, 317
Virgatites, 664
Virgularia, 110
Vitrinella, 532
Vitulina, 417
Viviparus, 544
Vlasta, 438
Vola, 457
Volborthella, 597
Volborthia, 370
Voluta, 561
Volutella, 561
Volutifusus, 561

INDEX

839

Volutilithes, 561
Volutodernia, 561
Volutomitra, 500
Volutomorplia, 561
Volvai^ia, 566
Volviceranius, 447
Volvula, 56S
VolruUUa, 568
Vulsella, 449
Vulsellina, 449

Waagetiia, 660, t565
Waagenoceras, 642
Waagenupora, 387
Waclismiithicrinus, 205
Waehneroceras, 657
Wakiillina, 461
Waldheiiaia, 408
Waltonia, 408
Waniieria, 714

Wai)tia, 733
Watthia, 523
Welscliia, 658
Wf'slonia, .'iTl
Whiteavesia, 462
Wliitella, 442
Wliitfleldia, 415, 416
Willemoesia, 761
Williamia, 573
Wilsoiiia, 398
Wimanella, 381
Witcliellia, 660
Wiwaxia, 137
Wooclücrimis, 223
Woitheiiella, 137
Worthenia, 524
Wortlieiiopora, 347

Xantlio, 767
Xaiithopsis, 767

Xeiiaspis, 645
Xenmter, 248
Xenoeidaris, 274
Xenocrinus, 193
Xenodiscus, 645
Xeiiophora, 543
Xestoleberis, 739
Xiphidiocaris, 751
Xiplioteutliis, 681
Xylobius, 793
Xylotrya, 501

Yolioia, 732
Yoldia, 441
Yorkia, 376

Zacantlioides, 716
Zaphreiitis, 83
Zeaerinus, 223
Zeilleria, 406

Zellania, 405
Zemira, 557
Zenatia, 498
Zenkericrinus, 190
Zeuglopleiirus, 282
Zidona, 561
Zittelia, 553
Zittelisiwngia, 68
Zitteloceras, 603
Ziziphiniis, 532
Zonatiila, 326
Zonopora, 325
Zoopilu.s, 102
Zophocrimis, 158
Zugmeyeria, 403
Zurcheria, 660
Zygites, 524
Zygocriims, 172
Zygopleura, 537
i Zygospira, 408

END OF VOL. I

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