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CONTENTS.

THE NORTH AMERICAN CRINOIDEA CAMERATA. By CHARLES WacusmutH and
FRANK SPRINGER. Chapter 1-IX. Page 1-359.

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state

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Memoirs of the Wuseum of Comparative Zoologu

AT HARVARD COLLEGE.

“VoL. XX.

THE NORTH AMERICAN

CRINOIDEA CAMERATA.

By CHARLES WACHSMUTH anp FRANK SPRINGER.

IN TWO VOLUMES WITH EIGHTY-THREE PLATES.

VO

a

CAMBRIDGE, U.S. A.:

Printed for the Museum.
May, 1897.

Co the Memory

bOULS AGASslZ

TO WHOSE INFLUENCE AS TEACHER, EXPOUNDER, AND INVESTIGATOR, NATURAL
; HISTORY IN AMERICA IS SO DEEPLY INDEBTED,

AND WHO FIRST INSPIRED AND ENCOURAGED US IN OUR EARLIER STUDIES,
Chis CHork
IS GRATEFULLY DEDICATED BY

CHARLES WACHSMUTH.
FRANK SPRINGER.

NOTE.

THE Manuscript of this work in its present form was received at Cam-
bridge for publication September 1, 1894. Although in press ever since
then, no part of it has been published until now, and the date of the work,
for bibliographic purposes, will be that which appears on the title-page.
During the long time that has been consumed in the printing of the plates
and letter-press work since the completion of the text, many new species
of Crinoids have been described by American authors, among which some
of those herein mentioned as new are included, and thus anticipated. No
attempt has been made to cover these cases by modifying the text, nor
have any questions arising upon publications appearing subsequent to the
above date been considered here. In a work of this size while in press
changes could not be made to keep pace with current researches, and the
date of delivery of the Manuscript for publication was therefore taken by
the authors as final, so far as they were concerned.

It is a source of extreme regret that my learned colleague and long-time
friend, Dr. Charles Wachsmuth, did not live to see the publication of this
Monograph, to which he had devoted so many years of assiduous labor.
Never a robust or healthy man, his last few years were almost a continual
struggle against disease. His strength gradually failed, and he passed away
on February 7, 1896, at the age of sixty-seven years.

Dr. Wachsmuth was a native of Hanover, Germany. He came to the
United States in 1852, and soon after engaged in mercantile pursuits at
Burlington, Iowa, which became his permanent home. Failing health in
time compelled him to relinquish business, and for the last thirty years he
applied himself to the study of the Crinoids, first as a recreation and to—
secure outdoor exercise, and. afterwards as his life work, with all the ardor
of a scientific devotee. His keen powers of observation, sagacious judgment,
and indefatigable energy have left their impress upon the works which have
been brought out by us. While his death is a loss to Science not easily
repaired, it is to none so great—aside from his family — as to the friend
with whom he had worked in pleasant collaboration for so many years. It
is with a melancholy pleasure that I avail myself of the opportunity afforded
by the appearance of his last work to pay this slight tribute to his memory.

FRANK SPRINGER.

Las Vegas, New Mexico, 1897.

INTRODUCTION.

Tue present work is the outgrowth of studies begun over twenty years
ago under the encouragement of Prof. Louis Agassiz, and prosecuted con-
tinuously ever since. During that time, we made two very large crinoidal
collections, of which the original one, in 1873, was secured by Prof. Agassiz,
for the Museum of Comparative Zoédlogy. Upon this collection one of the
writers, while an assistant at the Museum, laid the foundation of the present
work. Since 1877 the investigations were conducted by us jointly, and
during that time we have built up together the extensive collection which
is known as the collection of Wachsmuth and Springer. The advantage of
residing, for a time both of us, at Burlington, a locality so well known for
the wealth of its crinoidal remains, gave us excellent opportunities to study
the Crinoids in all stages of preservation, and being in the field ourselves, we
could pick up such material as would help us in the study of minute details.

Since the publication of our first paper on the Crinoids, it has been our
alm to direct our special attention to studying the morphology of the vari-
ous groups as they appeared to us, with a view to future classification, and
to revise the work of the previous writers. The various classifications which
had been proposed were not based upon. strictly morphological principles, and
in many cases widely distinct forms were placed together in the same group.

It early became evident to us that we could not hope to gain a correct
understanding of the fossil forms except by studying their living represen-
tatives. The publication of Carpenter’s two Challenger Reports, and De
Loriol’s important Monograph on the Mesozoic and later Crinoids of France,
opened to the working paleontologist a new field of. research, and enabled
him to study the relations between paleeozoic and neozoic Crinoids, which
had been altogether misunderstood. It had been the general opinion, ever
since the time of Johannes Miiller, that all palzeozoic forms were widely
distinct from the later ones, a view also held by us until 1890.

Before the publication of the first Challenger Report, the attention of
paleontologists had been directed almost exclusively to the structure of the
dorsal or abactinal side of the calyx; that of the ventral side had been very

much neglected, and scarcely any attempt had been made to homologize the
1

2 INTRODUCTION.

plates of the tegmen in the different groups. The first attempt in this
direction was made by Wachsmuth in 1877, and the subject was taken up
again in our Revision of 1879. Dr. P. Herbert Carpenter discussed the
question more elaborately in 1884, when it became manifest that our views
differed radically upon several important points, and especially as to the
identification of the oral plates. The progress of our studies on this and
other questions was published from time to time in the Revision, and in
short papers. This was done for the double purpose of making known the
results of our own studies, and of stimulating inquiry by others upon points
that were still obscure.

Whatever may be the merits or demerits of the Revision — and that the
latter are many and serious none are better aware than we— it accom-
plished one of its purposes. It induced research and provoked discussion
upon new lines and with an activity unprecedented in this field. The
contributions to the knowledge of the subject, resulting directly from these
controversies, have been of incalculable value to us, and none the less so
because some of our own theories have been from time to time exploded.
As the most important result, it has now become clear that the Crinoids
were most intimately connected from the Silurian down to the present
time, and that only the Camerata—a highly specialized type — became
extinct at the close of the Carboniferous. It was not until this fact was
realized that the way was opened to a better understanding of the whole
Crinoid group, in which, as so often found in Nature, the simpler forms
persisted, and led down to present types. Although it seems plain enough
now, it was only by slow steps, and after long and patient research, that
this result was reached.

After a large amount of preliminary work had been done, we proceeded
to prepare for publication in permanent form such part of it as we could
reasonably hope to finish, and to that end we began the preparation of the
illustrations in 1887. The work has grown upon our hands to such an
extent that we found it necessary to limit it to the Camerata, the largest
and most remarkable group among Paleozoic Crinoids. Thus limited, we
could hope to give a reasonably full account of this group, and in connec-
tion with discussion of the morphological and systematic relations of the
other groups, to give some account of the Crinoids generally.

The most of the drawings were made under our personal supervision in
our Museum at Burlington; a few were made in Washington. Thirty-five

INTRODUCTION. a

of the plates were drawn by Dr. Charles R. Keyes, the present State geolo-
gist of Missouri; thirty-three by Mr. A. M. Westergren, so well known for
his drawings for Lovén’s great work on the Echinoids; the remaining
twelve by Mr. John R. Ridgway, artist for the United States Geological
Survey. The execution of the plates occupied about six years, and we
avail ourselves of this opportunity to express our thanks to all of these
gentlemen for the fidelity and earnestness with which they performed
their work.

When the work began to assume a definite shape, Mr. A. Agassiz, on
being made acquainted with the extent to which it had progressed, kindly
offered to undertake its publication asa part of the Memoirs of the Museum
of Comparative Zology at Harvard College. No words of thanks would
at all express our sense of the obligation under which this has laid us, not
merely for the facility of publication through so desirable a medium, but
for the mark of appreciation which this offer implies. If the work shall be
found sufficiently useful to science to merit, even in a small degree, the
indorsement thus given, we shall deem it the best return we can make.

During the studies that led up to this Monograph, we enjoyed the privi-
lege of continued communication with our lamented friend, P. Herbert
Carpenter, up to the time of his decease. We had some energetic con-
troversies in print, and a far greater number in private correspondence that
never saw the light. ‘To his incisive and suggestive mind is due the over-
throw of more than one promising but untenable theory; and we take a
melancholy pleasure in recording here our appreciation of his high attain-
ments, and our sense of the great loss which Science has suffered through
his untimely death.

It has been our purpose to give descriptions of all American species of
the Camerata known up to this date, and those that could be recognized
have been described anew, with the aids derived from the material brought
to light since the original descriptions were made. Many of the species
were defined from very imperfect specimens, and often without illustrations.
In the latter cases we have, when practicable, figured the type specimen,
and when necessary and possible have given figures of additional specimens.

During the preparation of the work we have had access to most of the
type specimens in the United States and Canada, which were placed in our
hands for comparison, study, and illustration. A few only of Prof. Hall’s
types in the New York State Cabinet of Natural History at Albany, and
some of S. A. Miller’s later species, we were unable to procure.

4 INTRODUCTION.

Not the least of the pleasure we find in bringing our work toa conclusion,
is the opportunity it affords us of acknowledging our obligations to the men
of science and collectors of America, for their liberality and personal con-
fidence shown to us, by placing in our hands — often for indefinite periods
— original, unique, and priceless collections, without the use of which this
work would have been impossible. It would be difficult to express in fitting
terms of acknowledgment the full measure of our indebtedness to them, and
we can only venture the hope that they may find in the work itself some
small return for the valuable contributions they have made toward it.

To Mr. Agassiz we owe a lasting debt of gratitude: first of all for his
personal encouragement and valuable counsel, and next for the use of the
magnificent collection of the Museum of Comparative Zodlogy. This has
been placed at our disposal without restriction, not only for examination at
Cambridge, but for removal to Burlington of all specimens we desired, with
liberty to use them as if they were our own. Only those who are acquainted
with the character and value of this unrivalled collection can appreciate our
obligation for such a use of it. It contains the original collection of De
Koninck, of the Belgian Carboniferous Crinoids, and the Schultze collection
from the Devonian of the Hifel,—by far the finest collections that have
ever been made of the rare Crinoids of those interesting localities. There
are also the collections made by Hon. B. J. Hall, Prof. W. H. Barris, and
the original collection of Wachsmuth, all from the Burlington limestone,
which include the types of a large number of the species described by Hall,
White, and Meek and Worthen. In addition to these is the fine collection
made by C. B. Dyer, from the Hudson River group, of Cincinnati, con-
taining many types of species described by Meek in the Ohio report, besides
most excellent material from Waldron, Crawfordsville, and other celebrated
localities of the West; also the Walcott collection from New York.

A full account of the various collections made use of by us would
exceed the limits of a preface, but we cannot refrain from making par-
ticular mention of some of them: —

The collections in the American Museum of Natural History at New
York, containing many of the type specimens of the New York Palzonto-
logical Reports, have been at all times accessible to us through the courtesy
of Prof. R. P. Whitfield, who has been prompt to send us such specimens as
we needed for illustration or comparison, and to give us any desired infor-
mation obtainable from the extensive material under his charge.

INTRODUCTION. Ss

During the lifetime of Prof. Worthen, the eminent Director of the
Illinois Geological Survey, and afterwards under the administration of his
accomplished successor, Dr. Josua Lindahl, we enjoyed the privilege of
unrestricted facilities in the use of the type and other specimens in the
State Museum of Natural History at Springfield. The private collection
of Worthen, containing a large number of the types of the earlier species
described in Hall’s Iowa Reports, was packed up and inaccessible while he
held the position of State Geologist; but after his death, when the col-
lection was acquired by the State of Illinois and incorporated in the State
Museum, we were permitted through the courtesy of Dr. Lindahl to
examine it, and were given full use of the valuable type specimens. As
a mark of our personal esteem, and in justice to the memory of this
pioneer collector and geologist, we have inserted the name of Worthen in
the notation of such of his type specimens as are now in the State Collection.
These types are of great value, as they are the only types of the early Bur-

lington and Keokuk species still in existence, so far as we know, with the ~

exception of a few in the Shumard collection. We have been unable to
obtain any information as to the types of Owen and Shumard’s descriptions
in the Report for Iowa, Wisconsin, and Minnesota, in 1852, — the first Sub-
carboniferous Crinoids described from the West. A considerable part of the
collections made during the first Iowa Geological Survey are said to have
been destroyed by fire, either at Burlington or Keokuk, and it is supposed
that a number of type specimens were lost in this way. McChesney’s types
were all lost in the great Chicago fire.

The collections in the Canada Survey Museum at Ottawa, containing
the types of all of H. Billings’s Lower Silurian species, and the later ones of
Whiteaves, have been freely open to us under the authority of Sir Alfred
Selwyn, and through the unremitting courtesy of Prof. J. F. Whiteaves.

Through the attention of Dr. C. A. White and Prof. C. D. Walcott, we
obtained the use of the types of some of Meek’s descriptions in the National
Museum at Washington.

Prof. S. H. Williams of Ithaca, New York, had the goodness to furnish
us for examination the types of species described by him, from the Museum
of Cornell University, and some of the types from the Colonel Jewett
collection. , ;

Through Prof. A. H. Winchell we had the use of the specimens in the
collection made by Dr. White, now in the University Museum at Ann Arbor,
containing the types of a number of well known Subcarboniferous species.

6 INTRODUCTION,

To Dr. G. Hambach of St. Louis we owe the facility of examining the
type specimens in the Shumard collection at the Washington University.

We are under special obligations to Prof. Borden, of Borden Institute at
New Providence, Indiana, for the opportunity of examining the original
collection of Dr. Knapp, of Louisville, from the now exhausted Bear Grass
locality near Louisville, containing some of the types of species described by
Lyon, Shumard, and Yandell, which now form a part of the Museum of the
Borden Institute. | ,

To Prof. S. Calvin we are indebted for the loan of fine specimens from
the Hamilton of Iowa and New York, from which we made descriptions of
several species. |

Our thanks are also due to Prof. W. H. Barris, of Davenport, Ia., who
gave us the use of his type specimens and other valuable material from
the Hamilton group of Iowa and Michigan, which were under his charge in
the Museum of the Davenport Academy of Science.

We also avail ourselves of this opportunity of expressing our high appre-
clation of the favors extended to us by Dr. G. Lindstrém, of the National
Museum of Sweden at Stockholm, in which are deposited the magnificent
collections of Crinoids from the Upper Silurian of Gotland that formed the
basis of Angelin’s descriptions. Not only has he at all times allowed us the
privilege of having special drawings made from unique specimens in
the Museum, but on one occasion, on learning of the difficulty under which
we labored from want of adequate material to study the genus Crotalocrinus,
he sent us, without solicitation, a series of specimens, including some of
Angelin’s originals, with liberty to retain them as long as might be necessary
for the examination we desired to make.

We have also to acknowledge our indebtedness to Mr. Walter R. Billings,
of Ottawa, Canada, for the loan of types of Trenton species in his own col-
lection, and also for his good offices in securing for our use the collections
of Messrs. Stewart and I. F. Sowter. Besides this, Mr. Billings has from
time to time furnished us valuable notes in relation to many rare and inter-
esting forms, often illustrated by exquisite drawings from his own hand.
We extend our thanks to Mr. John Stewart and Mr. I. F. Sowter, of Ottawa,
Canada, for the use of their specimens, — Mr. Stewart having at one time
sent us his whole collection for study.

To the owners of private collections in the United States our obligations
are so numerous and varied that we cannot attempt to express In proper
terms of appreciation our indebtedness to each one.

INTRODUCTION. "

It is especially difficult for us to express our obligations to Mr. Victor
W. Lyon, of Jeffersonville, Ind., who with the utmost liberality placed his
own collection at our disposal, and also that of his father, the late Major
Sidney 8. Lyon, through which we secured the use of all the types of the
species described by Major Lyon himself, and by Lyon and Casseday. _

Mr. Lisbon A. Cox, of Keokuk, Ia., gave us access to his extensive
and unique. collection from the Keokuk limestone, containing the types of a
large number of species described by Worthen in Vol. VII. of the Illinois
Reports. |

Mrs. Yandell, of Louisville, Kentucky, has sent us for examination some
rare types in the collection of the late Dr. L. P. Yandell. We tender our
special thanks to this venerable lady for the efforts she made to serve us.

To the naturalists and collectors of Cincinnati and vicinity we are
indebted for great facilities in studying the crinoidal fauna of the Lower
Silurian of that region. Mr. I. H. Harris, of Waynesville, Ohio, placed at
our disposal the species of his magnificent collection of Hudson River Cri-
noids. Mr. S. A. Miller favored us with the loan of his valuable types of
Lower Silurian species. Mr. EH. O. Ulrich, of Newport, Ky., has sent us for
examination the types of his species, and besides other instructive speci-
mens. He also used his influence in our behalf with Messrs. Oeh and
Vaupel, who placed some of their finest specimens in our hands.

Dr. E. N. S. Ringueberg, of Lockport, N. Y., has sent us the types of
his species of the Niagara group of Western New York, with liberty to use
them as we might find desirable.

To Prof. J. M. Clarke, of Albany, N. Y., we are indebted for the use
of valuable type specimens from the Hamilton group of New York, then in
his private collection, but since passed into the New York State Cabinet.

Mr. Thomas A. Greene, of Milwaukee, Wis., placed in our hands a
large collection of natural casts from the Niagara group, including types of
the Waukegan species; and Mr. W. C. Egan, of Chicago, a similar collection
from near Chicago, containing the types of the species described from that
locality. |

Mr. F. A. Sampson, of Sedalia, Mo., gave us the use of his collection,
containing the types of a large number of species described by S. A. Miller
in the Missouri and Indiana Reports; and Prof. Rh. R. Rowley, of Louisiana,
Mo., furnished us the types of his species.

We are also indebted for the use of specimens and friendly acts in vari-

8 INTRODUCTION.

ous ways to Mr. Asa 8. Tiffany, of Davenport, Dr. C. C. Washburn, of Wal-
dron, Ind., Dr. Moses Elrod, of Hartsville, Ind., Rev. H. Herzer, of Berea,
Ohio, Rev. John Davis, of Louisiana, Mo., Mr. D. H. Todd, of Kansas City,
Mo., Mr. G. M. Nickels, of Sparta, Ill, Mr. E. Brown, of Belfast, N. Y., and
others.

To Dr. Horace G. Griffith, formerly of Burlington, now of Philadelphia,
we express our grateful acknowledgments for his intelligent and unremitting
efforts to aid us in the prosecution of this work, and for his steadfast devo-
tion to our interests manifested upon every occasion.

We also bear in kindly remembrance our former townsman, Mr. James
Love, whose fine collection was always at our disposal, and which, together
with one made by Mr. J. W. Giles, afterwards passed into our hands.

Dr. Charles R. Keyes has at all times exhibited a lively interest in the
progress of our work, and we owe to him not only the procurement of some
valuable specimens, but other friendly offices.

Nor do we forget our good friend, Orestes St. John, whoge keen eye and
rare judgment, and no less his skilful pencil, have always been at our ser-
vice. We have from him some unsurpassed structural drawings, and he
presented us several unique Crinoids from the Coal Measures of Kansas. —

Our thanks are due to Mr. Wm. F. E. Gurley, of Danville, Ill., for the
use of specimens from Waldron, and to Mr. A. C. Benedict, of Indianapolis,
for the use of specimens obtained by him at St. Paul, Ind.

In addition to the facilities above mentioned, we have had during the
preparation of this work our own collection, which contains authentic speci-
mens of nine-tenths of the species of Crinoids described from the United
States, and two-thirds of all the European species. From many of the typical
localities we have been able to obtain, either by purchase of local collections,
or by personal exertions, large series of specimens, by means of which it has
been possible to study in many cases, and among different genera, the indi-
vidual variation existing in the limits of a species, and the modifications due
to growth.

In looking over the descriptions it will probably surprise some of the
authors to find so many of their species placed in the synonym lists, but
we were obliged to do so after careful study and comparison with authentic

specimens.
CHARLES WACHSMUTH.

FRANK SPRINGER.

Buriineton, Jowa, May 1, 1894.

Received at Cambridge, September 1, 1894.
ALEXANDER AGASSIZ.

TABLE OF CONTENTS.

INTRODUCTORY PART.

Pace

INTRODUCTION oO ari Ea a eth eae A Sak coud yak” tigen. te ae any eat aca TAN

FRSTORICARS “Nth Me 4 2iRe hie Geek he. eee G0 a eet ae caine et eat ele eee OE en ere OT

TERMINOLOGY 4 ora ht, eet ek ae are Ete alee ats aru Saenger ee ORO

MORPHOLOGICAL PART.

PRIMARY AND SUPPLEMENTARY Piates 388 | Tue Sip iiwieawreae PEA RHSe) ae 105
Tue PLATES OF THE ABACTINAL SystTEM 38-88 The distribution of the Plates iid
The Stem and its Appendages . 38-52 their relations to the different

Basals and Infrabasals . . . . 52-73 STOUDS =n o. ye we NOd=123

He RVAC tolGrears = lomuniee so eee ee eS (5 The Anal Plates and “aie Anus... 124-139

The Arms and Pinules. . . . 73-88 | InTeRNAL Caviry or THE Catyx 140-142
THe Puates oF THE AcTINAL System 88-104 The Chambered Organ and _ the

Phe Orals: o 4 Spar weeny) AxiahCanals: 2 ae 2 re aeeee lA)

Mouth and dcntiaitons lO etree tre POO The Convoluted Organ. . . . . 148

SYSTEMATIC PART.

CLASSIFICATION . . . . «. © = 144-172 Phy lacoeriniusr a ek oe eee ES
Definition of the Crinoidea and their Didboloerinusie o t.4 ne eee ee
Primary Subdivisions. . . . 169 ATCHEOCHINUS 5.1 ugar OD
Analysis of the Families . . . . 170 Rhaphanocrinus: 22 2 i, 4. Sees
Geological and Geographical Distri- TEyPiOCriMUS” 2. i.e eee
bution of the Camerata . . . 172 | Metoorintpazn . . f 8 ete 2OASB 9
DESCRIPTIVE. " Analysis of the Canons eee 264
RETEOCRINIDAR G1 pa) eos fy bi —137, Geological and pees Distri-
Analysis of the Genera. . . . . 178 (OUNGTOM Necks ene as Say a eee Oe
Geological and is a ae Dis- Meloerimites. | .2+ 92° Go % pee ae recom
CPiDUCION “se: Met ee ets Gly PtOCrIUS: in Wo. 8 os ene ee eel
WVetCOCtIANS 7 hie may Git ee yn ere ele Periclypltocrimus: 255 254s. eal
NEMOCKIMUS a) oe pe. wee een een OW Stelidioerinus hs =). tras ban ern)
AA OCHUMUS YS c.g5 Wales Pao te FOO Niariacrinusi pe. foe ar sale nee
THYSANOCRINIDAE . . . . . . 188-214 MacrOstylocrinuss 21 pertatee ae oo
Analysis of the Genera. . . . . 188 Meloctinus:<.. 7 St ee ee Be
Geological and Geographical Distri- Dolatocrimitesin= see eee ee
OMMTON NS 2) Behr ce re ree OS Technocrinus 2.55. eer 0 ee OE
AU ySa nO CHIMUG *o- ees co ice ee ATTOCHIMUS 5) (Raa aes See eee 0
RinchOecunitis S55 aise he eee erie eeal on Centrocrinus: 2 aero et aS
Hyptioerimus 2 .s. a ke 00 DolatocriniSsan 22-1 sae ee oO)
LGi@ GRIMS Sys, eee er ee re) Stereocrinusr 1 5-5. a oe
PampterOcnimuss que: oe ty ee Or FrACO CLINGS: en ay eens ee 327
Siphonocrinus . -. . . . . .--209-| CALyprocrInIpAn ne _ 380-359
RHODOCRINIDAE. . . . . .« .« 215-263 Analysis of the Cone: ee 330
Analysis of the Genera. . . 215 Geological and Deeg cee ier
Geological and Geographical Bae bution. 7. . <2 000
IS UEGIONGL Ae rep fe0r ors et= et eres ING Bucalyptocrinus’ = 0. 23.9. i ee
RUROGOCHIBUSE es us oie ceuntl eee NO Callicrinus.-"i <2— 3) 52 ane veo

Gilbertsocrinus-_ =. «92°. « « ‘Zoo

THE

CRINOIDEA CAMERATA OF NORTH AMERICA.

INTRODUCTORY PART.

FT HISTORICAL.

Tue first reference to Fossil Crinoids, according to De Koninck, was
made by Agricola in the second half of the sixteenth century. He distin-
guished between Trochites, Entrochus, and Hncrinus. The former name he
applied to all detached stem-joints; Hntrochus to a series of joints, and
Finerinus to the calyx of Enerinus liliformis, at that time the only Crinoid
in which a crown had been found in connection with the stem. As early
as the seventeenth and eighteenth centuries the crinoidal remains received
the attention of a large number of writers, some of whom regarded them as:
plants, others as animals. | ; :

Rosinus, who lived at the beginning of the eighteenth century, was the
first writer to show that the Crinoids were not plants, as before then gene-
rally supposed, but were closely related to the Asterids, and especially to
the group which afterwards received the name Euryale. He also supposed
that the Trochites and Entrochites were parts of Enerius, and not inde-
pendent bodies. |

An important advance in the knowledge of the Crinoids was made by
Guettard,* who described the first recent Stalked Crinoid that ever came to
Kurope. He gave this species, which was afterwards known as Pentacrinus
caput-medusce Lamk., the popular name ‘‘ Palmier marin,” and took it to be
the type of all fossil Crinoids with pentagonal stem, as opposed to those
with a round stem, of which he thought the living type had not been dis-
covered. He gave a moderately fair description of its structure; but added

* Mémoire sur les Encrinites et les piérres étoilées, dans lequel on traitera aussi des Entroques. (Mém.
de Acad, Roy. Soc. de Paris, 1755 (published 1761), pp. 224-318.

12 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

little as to the systematic position of the Crinoids generally, stating, how-
ever, that they were neither Polyps nor Starfishes.

Linné, throughout all the editions of his “Systema Naturae,” placed
the Crinoids among the corals. Blumenbach” has the credit of having been
the first writer who ranked them with the Asteroids and Ophiurids among the
order “ Vermes crustacei,” which corresponds approximately to our pres-
ent Echinoderms. Lamarck, in the first edition of his “Systéme des Ani-
maux sans vertébres,” published in 1801, ranged them among the “ Polypes
A rayons coralligénes,” along with Gorgonia, Umbellula, and Pennatula; but
he afterwards modified this opinion, and in 18127 referred the Crinoids to
the “ Polypes flottants,’ which he arranged next to the Radiata. In 18164
he placed the Encrinites (Stalked Crinoids) among the Polyps, but the
Comatule (Free-floaters) among the Echinoderms. Schweigger § directed
attention to the close resemblance that he found to exist between the arm
structure of stalked Crinoids and Comatule, and he considered the two
forms to be closely related. Cuvier in 1817,|| and again in 1830, placed
the Crinoids among the Echinoderms.

The name “Crinoidea,” with the rank of a family, was proposed in 1821
by J. S. Miller, for the lily-shaped, radiate animals which theretofore had
been known as E’ncrinites and Pentacrinites. He restricted the group to the
-Brachiate forms, and to those provided with a stem, as appears by the follow-
ing definition: ** “An animal with a round, oval or angular column, com-
posed of numerous articulating joints forming a cup-like body containing
the viscera, from whose upper rim proceed five articulated fingers.” This
description includes neither Blastoids nor Cystids, which were placed by
Miller’s successors as subordinate groups under the Crinoids. It also ex-
cludes the Comatule and the genus Marsupites, which have no stem, and
which probably for this reason were referred by him to the “Stelleride.”
Among the latter he recognized four divisions: “Comatule, Euryale,
Ophiura, and Asteria,” and he placed Marsupites in the same group with
Euryale. Miller knew little of the structure of the Comatule, but enough

* Handbuch der Naturgeschichte, 1780.
+ Extrait du cours de Zodlogie du Muséum d’histoire naturelle sur les Animaux sans vertebres, etc:
1812.

+ Histoire naturelle des Animaux sans Vertebres, etc., 1815-1822.

§ Handb. der skeletlosen, ungegliederten Thiere, Leipzig, 1820, p. 528.

| Le Régne animal, 1817 (17°), Vol. IV., p. 12.

q Op. cit. (Hid. of 1830.)
** A Natural History of the Crinoidea, Bristol; 1821, p. 7.

HISTORICAL. 13

to be struck by the resemblance they bear to the crown of Pentacrinis, and
he pointed out that the pentagonal plate at the base of the subglobose body
of the Comatule occupies the position of the first column joint of the
‘¢ Crinoidea.” .

Miller subdivided the Crinoidea into four groups: the ARTICULATA, to
which he referred the genera “ Apiocrinites, Encrinites and Pentacrinites ;”’ the
SEMIARTICULATA with “ Potertocrinites;” the INARTICULATA with “ Cyathocri-
nites, Actinocrintes, Rhodocrinites, and Platycrinites ;’’ and the CoapUNATA with
“ Hugemacrintes.’ His primary groups were based upon the mode of union
between the stem and calyx, and between the latter and the arms; his
genera upon the number and arrangement of the plates in the dorsal cup.
Considering that in 1821 only about twenty-five species of Stalked Crinoids,
recent and fossil, were known, and many of them only from fragmentary
specimens, we cannot help admiring the genius of Miller, who brought —
order out of chaos, and laid the foundation of the present classification of
the Crinoidea. His genera have been generally accepted, and are now rec-
ognized as the types of well-marked families.

Miller introduced an elaborate terminology, but unfortunately did not
always apply his terms to the same parts. In some of his genera he gave
the term “pelvis” to the proximal ring of the plates within the calyx, in
others to the plates of the ring above. In Apiocrinus and <Actinocrinus he
called the radials “ first costals;” the succeeding ones “ second costals,” and
the first axillaries “scapule.” In Platycrinus, however, and in Potertocrinus
and Cyathocrinus, the radials are his scapule, and are followed by arm plates.
Platycrinus, according to Miller, has no costals at all; but in the dicyclic
Cyathocrinus and Poteriocrinus costals are said to be represented by the plates
of the interradial basal ring.

A year after the appearance of Miller’s work, Schlotheim published the
first part of the Supplement to his Petrefactenkunde,* reproducing therein
Miller’s figures together with his own, and adopting his generic and specific
names. A year later, however, in the second part of that work, he withdrew
Miller’s generic names, and referred all Stalked Crinoids back to Encrinus and
Pentacrinus respectively.

Goldfuss in his great work adopted Miller’s classification and termi-
nology. Cumberland # did not consider Miller’s name “ Crinoidea” appro-

* Nachtrage zur Petrefactenkunde, 1822-1823 (2 Bande, mit 37 Kupfer-Platten),

+ Petrefacta Germanie, Diisseldorf, 1826-1833.
£ Reliquie conservate, Bristol, 1826.

14 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

priate, as not a single Eucrinus or Pentacrinus resembled in the smallest
degree a lily, either in stem, root, flower, or bud. Nor did he think it
absolutely proved that they were animals instead of coraline sensitive
plants.

In 1825, Say * described three new species under the genus Pentremites,
which he made the type of a new family of the Crinoidea, and proposed for
it the name Blastoidea. He also described the genus Caryocrinites, which he
took to be intermediate between Cyathocrinus and Actinocrinus. In the same
year two additional species of Pentremites were described by G. B. Sowerby.

In the years following up to 1840, a number of new species of Crinoids
were described by Mantell (1822), Pander (1830), Steininger (1831, 1837,
and 1838), Goldfuss (1832 and 1838), Zenker (1833), Phillips (1835-1836),
F. A. Roemer (1836 and 1839), Heisinger (1837), Sedgwick and Murchison
(1837), D’Orbigny (1837), Miinster (1838-1846), and others; but they added
little to the general knowledge of the Crinoids.

L. Agassiz, in his ProdrOme d’une Monographie des Radiaires ou Echino-
dermes,t referred the Crinoids to the “order” Stellerides, together with the

b)

“genera” Comatula and Marsupites, which, as he stated, differ from the
Crinoids only in not having a stem..

J. V. Thompson, in 1836, discovered { that the small species, which he
had described in 1827 as Pentacrinus europeus, loses its stem at a more
advanced stage of growth, and changes into a free-floating Comatula.
Thompson also discovered the ovaries along the pinnules.

Other important discoveries in relation to the anatomy and development
of recent Crinoids were made by Adams, Heusinger, Savigny, Delle Chiaje,
Blainville, and Dujardin. D’Orbigny in 1839 described the remarkable
recent genus Holopus,§ a Crinoid not attached by a jointed stem, but by the
lower end of the calyx. |

In 1840 appeared the classical work of Johannes Miiller, “Ueber den
Bau des Pentacrinus caput-meduse,” || which marked a new era in the history
of the Crinoidea, and threw a flood of light upon the whole group. Miiller
in this work discussed the relation between the Pentacrinites and Comatule,
and pointed out the anatomical differences in the structure of Crinoids and

* Journ. Acad. Nat. Sci. Phila., Vol. IV., pp. 292-296.

+ Mémoires de la Société des Sciences Naturelles de Neufchatel, 1835, Tom. I, p. 168.

t Memoir on the Starfish of the genus Comatula (Edinburgh New Philos. Journ., Vol. 20, p. 295.
§ Wiegmann’s Archiv fiir Naturgeschichte, I, p. 185, Taf. 5, Figs. 2~7.

|| Read before the Berlin Akademie der Wissenschaften, April 30, 1840.

HISTORICAL. i

Asterids. He also introduced a more rational terminology for the plates of
the calyx, which is still used by Zodlogists and Palzsontologists. He proposed
the name “ Basaha” for the pelvis plates of Miller, and “ Radiaha” for Mil-
ler’s scapulee and costals, including the first axillary. When the rays are
free above the first radial, the axillary supports the arms; but when that
plate forms a part of the calyx, it is followed by the “ Distichalia,” and these
by the “ Palmaria.’ For the supplementary plates he introduced the terms
“ Interradiahia, Interdistichaha and Interpalmaria.” |

Miiller divided the Crinoids into three great groups: the “ Orinoidea Arti-
eulata,’ the “ Crinoidea Tessellata”’ and the “ Crinoidea Costata,’ which he
defined, and of which he gave a list of the principal genera. | |

Of the Articulata, to which Miiller referred Pentacrinus, Apiocrinus, Enerinus,
and the Comatulee, he said that the rays develop directly from the base of the
calyx, and the lower ray plates are united laterally by a skin, which is either
naked or paved with irregular plates; that this skin 1s-continued to the ven-
tral disk, closing the ventral side of calyx and arms; and that the radials
consist of three successive plates, of which the first and second, and the
axillary and the first arm-joint, are united by muscles.

Miiller’s Tessellata combine Miller’s “ Semiarticulata,’ and “ Inarticu-
lata,” and include the Blastoidea, Cystidea and the Cretaceous genus Mar-
supites. The calyx is composed of 3, 4 or 5 basals, which are sometimes
separated from the radials by a ring of “ parabasals.” Between the radials
there may be “interradials,” and between the distichals and palmars, “ in-
terdistichals,” and “interpalmars.” The “Scheitel” (ventral disk) covers
the whole ventral surface; it is constructed of solid plates, united at their
edges. : |

The Tessellata were subdivided by Miiller into two groups: Crinoidea
with arms, and Crinoidea without arms. To the former he referred all true
Crinoids and the Cystid genus Caryocrinus, forms having no separate anal
opening and no “ Tentakelfurchen ” (food grooves) upon the disk, and none
probably upon the arms. The armless Crinoids comprise the “ Pentremites”
(Blastoidea) and “ Sphaeronites” (Cystidea), forms with separate mouth
and anus. Ee

Miiller’s classification, although a great advance upon that of Miller, was
not accepted by the French and English writers succeeding him; but it was
revived later on by Ferd. Roemer and von Zittel.

In 1842 a classification was proposed by Thos. Austin and Thos. Austin ©

16 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Jr.,* who made the Crinoidea in the widest sense a class of the Echinoder-
mata, to which they gave the name “ Pinnastella.” Among the latter they
placed as orders : —

I. CIONACINETI (Stalked Crinoids). Il. LIBERIA (Free-floaters).
Families : Apiocrinoidea, Gnathocrinoidea.
Poteriocrinoidea, Astracrinoidea.
Encrinoidea. ~ Comastella.
Pentacrinoidea.

Marsmpiocrinoidea.
Platyerinoidea.
Actinocrinoidea.
Dimerocrinoidea.

Only the Platycrinoidea and Poteriocrinoidea ft were defined.

To the former they referred the genera: Platycrinus, Dichocrinus, Hexa-
crinus, Caryocrinus, and Cyathocrinus ; to the latter: Poteriocrinus, Symbatho-
erinus, Hutracrinus, and Pentacrinus. Their Encrinoidea include: Lncrinites,
Eucalyptocrinites, Cupressocruutes, and Kuryocriutes ; their Marsupiocrinoidea :
Marsupiocrinites and Crotalocrimtes ; the Actinocrinoidea : Actinocrinites, Rho-
docrimtes, Melocrinites and Tetracrintes. The Austins placed the Blastoidea
with the Sphaeroidocrinoidea, and the Periechinide under the Columnida.

D’Orbigny in 1852¢ undertook to subdivide the Crinoids (including
Blastoids and Cystids) into twelve families, which contain most heterogene-
ous elements. For description he divided the plates of the calyx into.
zones, without reference to their radial or interradial position.

The next classification was that of Ferd. Roemer, who wrote in 1855, §
and divided the Crinoidea into three great groups : —

I. Actinotdea, or true Crinoids, having large, pinnule-bearing arms.

Il. Cystidea, Crinoids in which the arms are feebly developed or wanting, and mouth
and anus are separate.

III. Blastoidea, Crinoids without arms, the soft parts of the animal enclosed within a
calyx, which is closed from all sides, leaving only a few openings.

The Actinoidea embrace :

A. The Astylida, Actinoidea, Crinoids without jointed column.
a. Attached by the lower face of the calyx.
Holopocrinide and Cyathidiocrinide.
b. Calyx free.
Astylocrinidz, Marsupitide, Saccocomide, and Comatulide.

* Ann. and Mag. Nat. Hist., first series, Vol. X., pp. 108 to 109.

+ Recent and Fossil Crinoids. Thos. Austin and Thomas Austin, Jr., London, 18438.
+ Cours élémentaire de Paléontologie, II.

§ Lethaea geognostica (Ausgabe III.), 1855, pp. 210-285.

HISTORICAL. 17

B. Stylida, Crinoids with a jointed column.
a. The tegmen formed of a skin.
Pentacrinide, Apiocrinide, Hugeniacrinide, Encrinide, Cupressocrinide, Cya-
thocrinide.
b. Lhe ventral surface covered by heavy plates, invmovably united.
Poteriocrinide, Rhodocrinide, Platycrinide, Actinocrinide, Melocrinide,
Ctenocrinide, Sagenocrinide, Anthocrinide.
ce. The arms wmperfectly developed.
Haplocrinide and Gastrocomidee.

Roemer’s families are natural groups, except his Cyathocrinidew, among
which he united a number of widely different forms. But this is partly due
to Miller, who had included with Cyathocrinus forms which were afterwards
referred even to different orders. Roemer, believing that Miller’s typical
species, Cyathocrinus planus was a Poteriocrinus, made his second species
Cyathocrinus tuberculatus, which Phillips in 1843 had made the type of
Taxocrinus, the type of Cyathocrinus.

Together with the Classification was published Roemer’s classical memoir
on the Cystidea and Blastoidea, of which especially that of the latter fur-
nished most valuable additions to our knowledge of the morphology of that
group.

In 1845 appeared the Memoir of Leopold von Buch on the Cystidea. He
gives excellent descriptions of several genera, and places the group at equal
rank with the Blastoidea and Crinoidea.

De Koninck and Le Hon, in 1853,* described a number of new species
from the mountain limestone of Belgium, and proposed certain changes in
the terminology of the calyx plates. ‘The proximal ring of plates he calls
“basals,” whether the species is monocyclic or dicyclic; those of the second
ring in dicyclic forms ‘‘ sous-radiales.” The radials comprise all plates up to
the first axillary; and the succeeding plates of the rays, when parts of the
calyx, are “articles brachiaux,” otherwise arm plates. The term “ inter-
radiales ”’ is applied only to the plates of the four ee sides ; those of
the posterior side are “ piéces anales.”

Another classification was brought out by Pictet, in 1857, who divided
the Crinoids into nine families. The first and ninth of his families contain
almost exclusively Neozoic forms. The former embraces the Comatule and
Marsupites, to which was added the Paleeozoic Astylocrinus (Agassizocrinus) ;

* Recherches sur les Crinoides du Terrain Carbonifére de la Belgique.
{ Traité de Paléontologie, par F. J. Pictet, Paris, 1857, Tom. V., pp. 278-345.
3

18 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the latter family, to which he applied the name “ Pycnocrinidées,” is divided
into four Tribus, — the “ Hugeniacriniens, Encriniens, Apiocriniens, and Pen-

99

EEO ene His second and third families comprise “ Blastoides” and “ Cys-
tidées ;”’ the remaining ones, the ‘“‘ Tessellata”’ of Miiller.

It is somewhat curious that Pictet, while placing Cupressocrinus, Rade.
lyptocrinus, and Crotalocrinus each in a separate family, referred all the
other Palaeozoic Crinoids to only two families, — the “‘ Haplocrinides” and
“‘Cyathocrinides.” His Haplocrinides embrace Haplocrinus, Coccocrinus, Cera-
mocrinus, Myrtilocrinus, Epactocrinus, and Gasterocoma ; all the other Paleocri-
noidea were placed under the Cyathocrinides. It is difficult to understand
upon what ground Pictet’s families were based. His ‘“ Polycrinides,”’ with
Eucalyptocrinus, have closer affinities with Melocrinus and Dolatocrinus than
these with Cyathocrinus ; while Cupressocrinus agrees closer with the Haplo-
crinides than many of the Cyathocrinides among themselves. —

Pictet subdivided the Cyathocriniens into four tribus,— the “ Cyatho-
criniens,’ the “ Actinocriniens,’ the “ Carpocriniens,’ and the “ Platyeri-
niens,’ — of which the first are dicyclic, the last monocyclic; while the
Actinocriniens and Carpocriniens are in part monocyclic and in part dicyclic.
He did not discriminate between genera in which the lower brachials form
part of the calyx and those in which they are free, nor did he pay the least
attention to the presence or absence of anal plates.

The classification of Pictet, although not so satisfactory as that of Roemer,
was accepted by Dujardin and Hupé.* The latter, however, changed the

995

sequence of the families, making the “ Cystidees the first family, and
placing the “ Comatulides ” last.

In America, up to 1858, little attention had been at to the study of
Crinoids. Of the fourteen hundred American species that are now described,
only about seventy were then defined. In 1843 and 1851, Hall had de-
scribed a moderate number from the Silurian in the Palseontology of New
York, Vols. I. and IL, and a few additional ones through the Regent’s
Reports at Albany. Owen and Shumard, in 1852, United States Geological
Report of Wisconsin, Iowa, and Minnesota, described nineteen species from
the Subcarboniferous of the Mississippi Valley, mostly from the Burlington
group; and Shumard, in Swallow’s Missouri Geological Report of 1855,
twelve species from the same horizon. The few remaining species had been
described by Conrad, Roemer, Casseday, and Yandell and Shumard.

* Histoire Naturelle des Zoophytes Echinodermes, par M. F. Dujardin et M. H. Hupé, Paris, 1862.

HISTORICAL. 19

About the year 1858 the interest of the American Palzontologists was
aroused by remarkable discoveries of Crinoids in the Southern and Western
States. Troost, at the meeting of the American Association for the Advance-
ment of Science, in 1850, reported the acquisition of eighty-six new species,
with sixteen new genera, from the State of Tennessee.* This discovery, how-
ever, was totally eclipsed by the wonderful finds in the Northwest, where, at
Burlington alone, upwards of three hundred species were obtained, which for
beauty and excellence of preservation surpassed anything that had ever been
seen before. ‘This one locality furnished a greater number of species than
had been described from America and Europe together up to 1857; and
while before, with a few exceptions, only calices had been obtained, now
hundreds of specimens were found in which arms, stem, and occasionally
the root, were preserved. The collections which were made at that time
by Wachsmuth, Barris, Dr. Thieme, and Hon. B. J. Hall, of Burlington,
and which were afterwards secured by Prof. L. Agassiz for the Museum of
Comparative Zodlogy, give testimony to the energy and enthusiasm with
which collecting was carried on in those days. The same interest, often
mingled with jealousy, was manifested by the men of science, who, anxious
to publish the new forms, and fearing they might be preceded by competi-
tors, brought out preliminary descriptions to secure priority for their species.
These descriptions, in many cases, were so indefinite that the identification
of the species was almost impossible, and this created considerable Eva see
and labor to later writers. |

About the same time other large deposits of Crinoids were discovered in
Indiana. Crawfordsville furnished upwards of thirty species, Waldron and
Hartsville nearly twenty. At the latter places large collections were made
by Dr. Moses N. Elrod and Dr. C. C. Washburn. At Louisville and sur- —
rounding country a large number of new species were found by Lyon,
Yandell, and Dr. Knapp; at Keokuk, Iowa, by Dr. Kellogg, who afterwards
discovered also the rich Crinoid bed at Richfield, Ohio. Still more success-
ful as a collector in the Keokuk rock was L. A. Cox, who found two local
deposits of finely preserved Crinoids,— one at Keokuk, the other at the
opposite side of the river, which produced nearly forty new species. Dr.
Roeminger discovered the Crinoid bed in the Hamilton group at Alpena,
Michigan ; Springer that of Lake Valley, New Mexico, in the Burlington

* These genera and species were described by Troost in a monograph. The manuscript was deposited

at the time of his death in the Smithsonian Institute, but was never published, and he did not receive the
credit which is probably due to him. \

Daa THE CRINOIDEA CAMERATA OF NORTH AMERICA.

group. Among the pioneer collectors must be mentioned also Mr. Anthony,
U. P. James, and C. B. Dyer, of Cincinnati; I. H. Harris, of Waynesville ;
J. Kelly O’Neall, of Lebanon, Ohio; Thomas A. Greene, of Milwaukee ;
W. C. Egan, of Chicago, — who all made large local collections which have
furnished many type specimens.

Within the last ten years three most remarkable finds were made in the
West: — the first at Le Grand, near Marshalltown, Iowa, in the Kinderhook
group; the second on Indian Creek, ten miles from Crawfordsville, Indiana,
in the Keokuk group; and the other in the Upper Coal-measures at Kansas
City. The Le Grand bed furnished about twenty-three new species, not
counting the Blastoids. Of the latter, two species of Orophoerinus are repre-
sented, and in quite a number of their specimens the stem and pinnules are |
preserved. Most of the Crinoids have arms and stems, and some of them
roots. The crinoidal layer, which is but an mech or two thick, furnished
many excellent slabs. We have one in our cabinet about a yard in diam-
eter, on which ninety-five specimens are exposed, both sides of it being
thickly studded. eR}

The Indian Creek locality was discovered by the late Charles 8. Beachler
while collecting for us. It proved to be a local deposit in the bed of the
creek, not over twenty feet in diameter, and covered over a foot deep by
water. Too much credit cannot be given to Mr. Beachler, who obtained
under the most trying circumstances several thousand specimens, repre-
sented by nearly forty species. ‘The specimens in places were so plentiful
that more than half of them had to be sacrificed to save the others. ‘The
preservation is excellent, and in some respects surpasses that of any other
locality.

The bed at Kansas City is in the heart of the city. It was discovered by
Sidney J. Hare in the excavation for a large building. Only seven species of
Crinoids were found, but they are of exquisite beauty, and being embedded
in a soft clay, are of most excellent preservation. Good collections were
made here by David H. Todd, Sidney J. Hare, S. A. Howe, and E. Butts.

Almost as fast as new discoveries were made the species were described,
and in 1865 the number of American Crinoids had increased to six hundred
species. In 1858 appeared the Iowa Report, Vol. L, by James Hall, in
which he described over ninety species of Crinoids, not counting the Blas-
toids, and in the following year, in a Supplement to that Report, seventy-
four additional ones. In 1861 Hall issued a paper entitled “ Description of

HISTORICAL, 21

New Species of Crinoidea, Albany, 1861,” in which he gave on eighteen
pages preliminary notices of one hundred and eleven species. A large num-
ber of these descriptions remain in that shape to this day, while some of the
species were redescribed by him in the Boston Journal of Natural History,
Vol. VII. In the Paleontology of New York, Vol. III., Hall described
twenty-six species from the Helderberg groups,— some of them, however,
from arm or stem fragments, — and from eighty to ninety additional ones
through the ditterent Annual Reports of the New York State Museum.

A large number of species were described by Meek and Worthen,
and after Meek’s death by Worthen; they amount to two hundred and
seventy species, with ten new genera, all well illustrated. Another lot was
described by Lyon and Casseday, and by Lyon individually ; in all thirty-one
species, with six new genera. Dr, C. A. White described thirty-five species,
and made three new genera. In Canada, E. Billings described some forty
species from the Trenton and Hudson River groups, with seven new genera.
In later years the most prolific species-maker was S. A. Miller, who increased
the number of species quite considerably. Many of his species have proved
to be synonyms, and while some of his new genera will be accepted by
every writer, others will go into oblivion. Additional species were described
by Whitfield, Wetherby, Ulrich, Barris, S. H. Williams, Whiteaves, Ringue-
berg, Wachsmuth and Springer, Walter R. Billings, Keyes, Rowley and
Hare, and others.

The American Paleeontologists followed the termmology of De Koninck,
and their descriptions, as a rule, are concise and readily understood. But
few writers besides ourselves discussed morphological questions, and S. A.
Miller, Prof. Chapman, and we, are the only ones who attempted to classify
the Crinoids.

Billings, like most of the earlier writers, believed that the opening in the
disk of Paleeozoic Crinoids represented mouth and anus combined.* He
pointed out that the grooves and galleries, passing out from the centre of
the disk.at the inner floor, are connected with the ambulacral system, and
communicate through the arm openings with the arm grooves, but do not
enter the tegminal aperture, which he found to be interambulacral. When
Billings took up this question again in 1869,f presuming that the aperture
represented the mouth, he concluded that in the earlier Crinoids, in Blas-

* Geol. Surv. of Canada; Decade IV. pp. 14 to 17.

+ Notes on the Structure of the Crinoidea, Cystidea and Blastoidea en Journ. of Sci. and Arts (2d
Series), July, 1869, and J anuary and September, 1870.

22 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

toids and many Cystids, the mouth was disconnected from the ambulacra;
and that in those Cystids in which more than one opening is represented,
the lateral one is the mouth, and not the central one, as had been generally
supposed. |

A different interpretation of the opening was given by Schultze, Sir
Wyville Thomson, Dr. W. B. Carpenter, Dr. Liitken, Lovén and Wachs-
muth, who maintained that the mouth of all Echinoderms was located in
the centre of radiation, and insisted that the interambulacral opening was
the anus. Schultze * could not understand how a Crinoid with an interam-
bulacral mouth could be sufficiently provided with food, even if the arms
were prehensile organs, which they were not. He stated that Billings’s im-
portant discovery, that the ambulacra enter the mouth by the arm openings,
left but little doubt that the mouth of the older Crinoids was subtegminal
and central; that the food entered the body through the arm openings, and
was carried underneath the tegmen to a common oral centre. His views
were corroborated by Meek,} who saw Wachsmuth’s famous specimen lel
V., fig. 10), and found the ambulacral tubes intact beneath the tegmen.
These observations were confirmed by Wachsmuth,{ who had discovered
additional specimens with the ambulacra preserved, and most instructive
natural casts, in which the course of the ambulacra is indicated by ridges
upon the surface. ;

In England, for a long time, very little attention was paid to the study
of fossil Crinoids, and many well known forms are undescribed to this day.
Among the earlier English writers were Mantell, Cumberland, Parkinson,
Phillips, McCoy, Sedgwick, and the -Austins. Their descriptions in many
cases are so primitive that neither genera nor species can be identified.
They were followed by the writings of Rofe and Grenfell, and those of
Dr. P. H. Carpenter and F. A. Bather, whose excellent work attracted the
attention of every earnest student of Crinoids, and opened a new era in the
history of paleontological research. In France but little work was done
upon Palseozoic Crinoids. Oehlert described a number of interesting De-
vonian forms, and among them several new genera. De Loriol, so well
known for his Monographs on the Crinoids of Switzerland and France,
directed his attention exclusively to Neozoic forms.

* Monogr. Hchinod. Hifl. Kalk., Wien, 1867, p. 7.

t Notes on some points in the Structure and Habits of the Paleozoic Crinoidea, by F. B. Meek and

A. H. Worthen (Proc. Acad. Nat. Sci. Phila., 1869, p. 323).
{ Amer. Journ. Sci. and Arts, Vol. XIV., August, 1877.

HISTORICAL. 23

In Germany the principal writers on fossil Crinoids were: Goldfuss,
Miiller, the two Roemers, Minster, Steiniger, Sandberger, Quenstedt, Bey-
rich, Schultze, v. Meyer, v. Zittel, Follman, Walther, Kunisch, Wagner,
Steinmann, Neumayr, and Jackel. The Belgian Crinoids were described
by de Koninck, and by Fraipont; those of Russia by Eichwald, Grewingk,
Volborth, F. Schmidt, and Trautschold ; a few Indian specimens by Waagen,
and those from Australia by Etheridge, Jr., and McCoy.

In the year 1879 appeared the first volume of von Zittel’s Handbuch der
Paleontologie, with a chapter on the Crinoids. He made the latter a class
of the Echinodermata, with three orders: the Eucrinoidea or Crinoidea
sensu stricto, the Blastoidea and Cystidea. The Eucrinoidea were divided
into three suborders: Tessellata, Artieulata, and Costata, in which he followed
Miller. His Tessellata were separated by him into twenty-six families,
which comprise all the Palaeozoic forms, and the Cretaceous genera Marsupites
and Uintaerinus ; the Articulata into seven families, all Mesozoic and recent
forms ; the Costata comprise only the Jurassic Saccocoma.

The Tessellata were defined by him as having thin, immovable calyx
plates, united by suture with smooth faces; “interradials” rigid; mouth |
subtegminal and anus excentric. Among the families he discriminates
between forms in which the tegmen consists : —

A. Exclusively of five large orals, or in addition to them small covering
pieces closing mouth and food grooves. The orals forming a pyramid or a
so-called Consolidations-Apparat.” Arms simple: Haplocrinide, Pisocrinde, and
Cupressocriude. ; | ie

B. Tegmen composed of small plates; the mouth closed by five orals,
which either are tegminal, or placed underneath the tegmen; the anus
excentric. Dorsal cup formed of three (rarely two) zones; the base gen-
erally dicyclic. Arms strongly developed ; their ambulacra covered by two
or three pieces: Hybocrinide, Cyathocrinde, Taxocrinde, Ichthyocrinide, Cro-
talocrimde and Cheirocrinide. | pa

C. Tegmen ventricose or balloon-shaped, composed of numerous thin
pleces; mouth subtegminal. Anal tube long and heavy, the anal opening
near the base. Arms strongly developed and pinnule-bearing : Heterocrinide,
Potertoeruude and Marsupitide. | ) | | Ears

D. Tegmen composed of heavy, frequently nodose plates; the middle
portion covered by seven larger pieces. Mouth subtegminal, communicating
with the arms through plated tubes. Anus often extended into a long pro-

24 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

boscis with the opening at the upper end: Gasterocomide, Platycrimde,
Carpocrimde, Briarocrinde, Dimerocrinde, Barrandeocrinide, Actimocriude,
Stelidiocriude, Melocruudee, Polypeltide, Umtacrinde, Glyptocrimde and Lho-
docruudee.

K. Tegmen bottle-shaped, narrower at the top; composed of large,
polygonal plates, regularly arranged. Arms not extended beyond the calyx,
biserial ; placed between rib-like projections, or occupying closed compart-
ments: Calyptocrinidee.

The Articulata were defined by Zittel as follows: Plates of the dorsal cup
generally very heavy, the articular faces excavated or smooth. Base mono-
cyclic, and formed of five pieces; exceptionally dicyclic. Tegmen, as a
rule, composed of a skin-like perisome, rarely plated; mouth and food
grooves exposed. The mouth central; anus excentric; orals present or
absent. Plates of the dorsal cup perforated by axial canals, passing out
from the dorsal organ, and continued along the solid parts of the arms to
the ends of the pinnules.

To the Articulata he refers the following families: the Enerinidw, Eugenia-
ertmdce, Holomde, Pheatocrimdce, Apiocrinde, Pentacrinde and Comatulde.

Examining the characters upon which Zittel separated the Tessellata
from the Articulata, it appears that not one of his distinctions holds good
throughout the families of either group. The “Taxocrinide” and “Ichthyo-
crinide,’ which he refers to the Tessellata, have a more flexible disk than
either the Encrinidxw or Apiocrinide, and even than many of the Penta-
erinide ; and, besides, have an open mouth and open food grooves. The
Poteriocrinide have a flexible disk, and well defined muscular articulations
between the radials and costals. The interbrachials of Guettardicrinus and
Apiocrinus roissyanus are as heavy and rigid as those of any Actinocrinus, and
the plates of the dorsal cup in EHwpachycrinus and Hrisocrmus are perforated
by axial canals, a character which was supposed to occur only among the
Articulata. Neither is it true that the Articulata are “rarely dicyclic” ;
the reverse would be more nearly correct, for most of them had small infra-
basals in early life, which gradually fused with the stem. No doubt Zittel’s
groups marked A and E form excellent divisions, but B, C, and D comprise
widely differing types, and some of their families include monocyclic and
dicyclic forms. As a whole, Zittel’s classification marks a great advance
over those of his predecessors, and he is the first writer who gave a good
definition of the. families, and who arranged them systematically. —

HISTORICAL. 25

In 1879, a month or two after the appearance of von Zittel’s Handbuch,
we published Part I. of our Revision of the Paleocrinoidea, embracing the
Ichthyocrinide and Cyathocrinide ; and in 1881 Part IL, containing the
Spheroidocrinid. In both parts we gave a review of the genera then
known, which were redescribed and systematically arranged. We also gave
with each genus a list of the species and their synonyms so far as then
known. No effort was made by us to subdivide the three groups, because,
as we thought, the knowledge of fossil Crinoids had not been advanced
sufficiently to justify it. We waited for the publication of the Challenger
Report, which we hoped would solve certain important morphological
questions. It seemed to us that a revision of the genera, many of which
had been incorrectly, others insufficiently, defined, and the arranging of
them systematically among a few large natural groups, was preferable to
a classification based upon unreliable data. We separated the Crinoids into
Paleocrinoidea and Stomatocrinoidea,* the latter to include all Mesozoic
and later forms.

The name “Paleocrinoidea”” had been introduced by Wachsmuth in
1877 as a subdivision of the Crinoidea,f to include those forms in which the
disk is roofed by a second integument, which he supposed to exist in all
Paleozoic Crinoids. He recognized among the Paleocrinoidea three dif-
ferent plans: —

A. The Actinoerinus plan: Tegmen rigid; composed of heavy, rather
large, immovable plates, forming a free arch. |

B. The Taxocrinus plan: Tegmen flexible, consisting of minute, movable,
plates.

C. The Cyathocrinus plan: Tegmen at the four regular sides composed
of a large interradial plate, the posterior side extended into a tube or sac;
mouth and food grooves covered by small plates.

The differentiations in the tegmen he thought were accompanied by im-
portant modifications in the composition of the dorsal cup, and he expressed
the opinion that the construction of the tegmen afforded excellent charac-
ters for subdivisions. These divisions were actually made by us in the
Revision, Part III., and they form practically the foundation of our present
classification, notwithstanding that our views respecting the tegmen itself
have since then undergone considerable changes.

* In place of Stomatocrinoidea we afterwards adopted Carpenter’s preferable name “ Neocrinoidea.”

+ His paper “On the Construction of the Summit and its Value in Classification.’? — Amer. Jour. Sci.

and Arts (3d series), Vol. XIV., September, 1877.
4

26 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Among the questions discussed by us in Part IL, the most perplexing
one was that respecting the orals. As these plates are developed among the
first in the larva, it seemed to follow that they must be present also in the
Paleocrinoidea ; but the difficulty was to determine which of the various
plates in the summit represent them. The median portion of the tegmen
in most of those Crinoids is covered by from seven to ten asymmetrically
arranged, more or less prominent plates, consisting of a central one of larger
size, four others nearly as large directed anteriorly, and five others placed
posteriorly. We regarded the central plate as an element unknown among
the later Crinoids, which occurred only in forms with a closed mouth, and
that it actually covered the oral opening. The orals, we thought, were
represented by six plates: four large and two smaller ones, the two latter
jointly representing the posterior oral, broken up on account of anal plates.

Part II. of our Revision appeared in 1885. It contains the genera which
had not been considered before ; and we also completely revised Parts I. and
_II., making important changes in the classification. The Paleocrinoidea
were subdivided into three sub-orders: the CammraTa, the InapuNaTa, and
the ARTICULATA, which we distinguished by the mode of union between the
plates of the calyx, and the condition of the arms, whether free above the
radials, or partly incorporated into the cup. The origins of these groups
date back to a time of which we have no paleontological record, they
being already highly differentiated among the earliest known Crinoids.
We divided them into twenty-six families. |

The Crinoidea Camerata were separated into Reteocrinide, Rhodocrinida,
Thysanocrinide, Glyptasteridx, Melocrinide, Actinocrinide, Platycrinide,
Hexacrinide, Eucalyptocrinids, Barrandeocrinide, and Acrocrinide.

The Crinoidea Articulata were subdivided into Ichthyocrinide and Cro-
talocrinidee. |

The Crinoidea Inadunata were subdivided into ;— A. Crinoidea Larviformia,
with Haplocrinide, Cupressocrinide, Gasterocomidx, and Stephanocrinide ;
B. Crinoidea Fistulata, with Hybocrinide, Heterocrinide, Anomalocrinide,
Belemnocrinida, Cyathocrinide, Calceocrinids, Catillocrinide, Poteriocri-
nidee, Enerinidse, and Astylocrinide.

Most important from a morphological point of view was the discovery
of a fixed law respecting the orientation of the stem, which enabled us to
ascertain the presence of infrabasals in many species in which these plates
are hidden by the column. By means of this law we were led to the con-

HISTORICAL. 27

clusion that by far the majority of the Neocrinoidea are built on the dicyelic
plan, and either have small infrabasals, or had them in their larval state.
We continued to use the term “vault” as opposed to disk, believing that
the tegmen of Paleozoic Crinoids differed morphologically from the disk of
later ones. Respecting the oral question our views had undergone consid-
erable changes, owing to the discovery that the two smaller plates, which
we supposed represented together the posterior oral, are radially disposed
instead of interradially, and we inferred that the central plate alone repre-
sented the oral pyramid of other Crinoids, a view afterwards strongly con-
tested by Dr. P. H. Carpenter. |

In 1884 Carpenter’s Challenger Report on Stalked Crinoids came out,
and in 1888 that on Comatule. In the former the author discussed among
other things the morphological relations between Palxozoic and Mesozoic
forms, and replied to some points which we had brought out in the Revision.
With regard to the structure of the tegmen he argued that some Platycri-
nide had a “vault”; but that the ventral covering of others did not differ —
essentially from the disk of the Neocrinoidea. He believed that the Pal-
eeozoic Crinoids differed essentially from the later ones by means of. their
irregular symmetry, caused by the introduction of anal plates; and upon
this and other grounds, to which we allude in another place, he made the
Paleozoic and later Crinoids independent orders. In his classification he
fell back upon Leuckart’s almost forgotten name ‘“‘Pelmatozoa,’ which he
made a branch of the Echinodermata, with Crinoidea, Blastoidea, and Cys-
tidea as classes, and the Palwocrinoidea and Neocrinoidea as orders. He
also discussed the oral question, adopting the view which we had brought
out in 1881, but abandoned in the following year. He assumed that the
so-called central plate represents the dorso-central at the abactinal side,
the six proximals (his orals) the basals, and that the latter are homologous
with the genitals of the Urchins. In the second Challenger Report, that
on the Comatulx, we were criticised very severely for asserting that prob-
ably the Comatule had infrabasals in the larva, which were actually dis-
covered by Bury before the Report was published.

Among the many interesting papers written by Dr. P. H. Carpenter,
none attracted more attention than the one in which he discussed the rela-
tions of the basals in monocyclic and dicyclic Crinoids* He proved that

* On the *‘ Oral” and Apical Systems of Echinoderms (Quart. Journ. of Microsc. Sci., 1878, pp. 351-
383). |

28 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the proximal ring of the latter represents an independent element, and that
their second ring of plates corresponds morphologically to the proximal one
in monocyclic forms. This is now accepted by almost every writer. Another
important contribution to the knowledge of Crinoids was made by a paper
on Allagecrinus,* a Carboniferous genus, in which the ventral surface is cov-
ered completely by five oral plates, thus retaining persistently the structure
of the Autedon larva.

The progress in the knowledge of fossil Crinoids was paralleled by that
among recent ones, of which a great number of new forms were obtained by
the dredging expeditions. Until about 1860 we possessed of Stalked Cri-
noids only a few specimens of Pentacrinus caput-meduse, and one or two of
Holopus Rawsom; but since then new discoveries followed in rapid succes-
sion. In 1864, Sars described the genus Riizocrinus; Jeffreys, in 1872, a
new species of Pentacrinus from the Bay of Biscay ; de Pourtalés, in 1874,
a second species of Rhiizocrinus. 'The dredgings by the “ Blake” under the
supervision of A. Agassiz in the Gulf of Mexico brought to light the new
Comatulid genus Afelecrinus, and a large number of specimens of Penta-
crinus ; those of the “ Albatross” in 1891, off the Galapagos Islands, the
remarkable genus Calamocrinus. The largest results, however, were obtained
by the “Challenger” expedition, which produced three new genera of
Stalked Crinoids, and one of Comatule. Progress in morphology and em-
bryology in later years has been as rapid as the discovery of new species ;
in proof of which we need only refer to the works of Allman, Goette, Sars, —
Greeff, Ludwig, Pourtalés, Bell, Barrois, W. B. Carpenter, Wyville Thomson,
Perrier, Bury, P. H. Carpenter, Vogt and Yung, and A. Agassiz.

The oral question was finally solved in 18887 by our discovery of the
remarkable specimen of Tuxocrinus, which proved conclusively that in forms
with large plates around the oral centre, asymmetrically arranged, the orals
are represented not by the central plate alone, as we had supposed, nor by
the four large and two smaller proximals, as claimed by Dr. Carpenter, but
by the so-called central plate together with the four large proximals; the
disturbance in the arrangement of the plates being due to the introduction
of anal plates. It was further proved that in specimens in which the whole

* On Allagecrinus, the Representative of a new family, ete. By P. H. Carpenter and R. Etheridge, Jr.
(Ann. and Mag. Nat. His., April, 1881, pp. 281-297).

+ Discovery of the Ventral Structure of Taxocrinus and Haplocrinus, and Consequent Modifications in

the Classification of the Crinoidea; by Charles Wachsmuth and Frank Springer (Proceed. Acad. Nat Sci.
Phila., 1888, pp. 337-361).

HISTORICAL. 29

tegmen consists of five large pieces, as in Haplocrinus, etc., these plates are
orals, and not supplementary pieces as we had supposed.

The logical consequences of these conclusions were taken up by us in
1890,* when we undertook to prove that the so-called vault of Paleozoic
Crinoids is not a structure swt generis, but a highly differentiated disk; that
their large, rather regularly arranged interbrachial and interambulacral
plates represent morphologically the smaller irregular pieces between the
rays and ambulacra of later forms, and that the Paleozoic and Neozoic
Crinoids do not differ so essentially from one another as we had supposed.
It also appeared that neither the closure of mouth and food grooves, nor
the presence of anal plates, is a constant character among the older Cri-
noids, and we were compelled in 1888 to abandon the Paleocrinoidea and
Neocrinoidea as systematic groups.

That the two groups could not be upheld, was proved also by Neumayr,t
who claimed that none of the characters by which they had been separated
was persistent ; and he proposed in place of them a primary division based
upon the condition of the mouth and ambulacra, whether sudtegminal or
suprategminal, Viz. : |

I. Hypascocrinoidea. Mouth, ambulacral vessels, and Saumplittchen (the latter if pres-
ent) beneath the tegmen.

1. Spheroidocrinacea. Cup mostly, tegmen always, constructed of a large number of
plates immovably connected among themselves. Generally several of the arm
plates incorporated into the calyx by means of interradial pieces. Tegmen roof-
ing the whole ventral surface. Among its plates are readily distinguished a
central one, and four and two interradial proximals. Anus either directly piercing
the tegmen, or placed at the terminal end of a plated tube. (This group agrees
with our Camerata.)

2. Huplocrinacea. Cup and tegmen composed of a small number of immovable pieces.
The former having but one radial, and no interradials except an anal. Tegmen
with a central plate. (Our Larviformia.)

3. Ichthyocrinacea. Cup and tegmen composed of very numerous, somewhat movable
pieces; the former having two basal rings and more than one order of radials.
(Our Ichthyocrinide.)

II. Epascocrinoidea. Ambulacra not covered by the tegmen; their furrows exposed or
closed by Saumplattchen.

1. Cyathocrinacea. Base generally dicyclic. Cup without interradials at the four
regular sides. Tegmen, so far as known, composed of five orals, which support at
their edges the ambulacra; the latter covered by Saumplattchen. Anus within the
ventral sac. (Our Fistulata.)

* Perisomic Plates of the Crinoids (Proceed. Acad. Nat. Sci. Phila., October, 1890, pp. 345-375).
+ Die Stamme des Thierreiches, Wien und Prag, 1889, pp. 438-460.

30 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

2. Pentacrinacea. Calyx with a well defined basal ring; infrabasals wanting or rudi-
mentary. Ambulacral furrows and mouth (in all of them?) exposed. Tegmen
phable with movable Saumplattchen, or with five large orals and without Saum-
plattchen. (Pentacrinide, Apiocrinide, Plicatocrinide, Bourguetocrinide, Kugenia-
crinide, Holopide, and Comatulide.)

Neumayr’s primary divisions are partly based upon incorrect observation.
Among the three groups which he refers to the Hypascocrinoidea, the
Saumplittchen are subtegminal only in the Haplocrinacea. In the remain-
ing groups they may be subtegminal or exposed among species of the
same genus. ‘The Ichthyocrinacea even have an open mouth and open
food grooves. On the oral question he agreed with Carpenter, and took
the six proximals to be representatives of the orals.

Neumayr ranked the Crinoidea, Blastoidea, and Cystidea as independent
classes, and believed that the two former are derived from the Cystidea,
which to some extent combined the characters of the three groups.

Dr. Steinmann * adopted our classification of 1885, with Paleocrinoidea
and Neocrinoidea as.primary groups.

Two other classifications were proposed in America, —one by Prof.
K. J. Chapman, the other by S. A. Miller. The former? is to a large
extent hypothetical, being founded upon characters of which nothing, or
almost nothing, is known among Paleozoic Crinoids. His classification is
based mainly upon the presence or absence of a canaliculation within the
calyx and arm plates for the occupation of axial cords. He recognizes
three leading divisions : — |

I. Emedullata. Calyx plates and arm plates without internal canals.

I]. #stulata. Arm plates with dorsal canal. Calyx plates imperforate.

Ill. Canatculata. Calyx plates traversed from the basals upwards by
delicate radiating canals. The arm plates canaliferous dorsally. —

The classification of S. A. Millert may perhaps facilitate elementary
studies, but has no value from a morphological point of view. In forming
his families he made the number of basals the most important character for
division, next the presence or absence of “subradials,” and after this the —
structure of the “azygous side and other parts.” His classification is a
reminiscence of that of Angelin,§ who divided the Swedish Crinoids into

* Elemente der Paleontologie, Leipzig, 1888.

tT A Classification of Crinoids, by Professor E. J. Chapman, Toronto, 1882.
{ American Geologist, Vol. VI., 1890, pp. 275-286, and pp. 840-357.

§ Iconogr. Crinoid. Sueciz, 1878.

HISTORICAL. 31

Trimera, Tetramera, Pentamera, and Polymera. The fallacy of this plan is
well shown if we consider that the smaller number of basals is simply the
result of anchylosis of two or more of the original five plates; and that in
“many cases it brings together the most diverse forms, while forms which
naturally belong together are widely separated. We need only refer to
the highly differentiated Calceocrinide, of which some species have four
basals, and others but three. In the genus Platycrinus the normal number
is three; but in many cases they are anchylosed into a solid disk, leaving
no trace of suture lines. Under Miller’s classification many species, and
often individuals of the same species, would have to be referred to different
families. |

The most important recent European writings on Paleozoic Crinoids are
those of Mr, F. A. Bather of the British Museum, who has done much
valuable work in systematizing the terminology. His descriptive work has
been chiefly confined to the Fistulata of the Wenlock limestone of England,
and its equivalent in Sweden; but we should like to see it extended to
include the Carboniferous Crinoids of England, of which careful study is
greatly needed. His admirable Monograph on the Crinoidea of Gotland,
Part I.,* arrived too late to be considered in this work as fully as would be
desirable ; in it, however, he has rendered a great service to all students by
bringing order out of the confusion in which the splendid Swedish collec-
tions had become involved by reason of Angelin’s fictitious illustrations and
restorations. We hope nothing will occur to prevent the completion of
his work.

* “The Crinoidea Inadunata,” with ten photographic plates, published by the Royal Swedish Academy
of Sciences.

II, TERMINOLOGY.

Tue following terminology may be regarded as the result of a two years’
correspondence with the late Dr. P. H. Carpenter, carried on with a view
to securing greater uniformity and precision in the morphological nomen-
clature of the Crinoids; and we mutually agreed to adopt it in our future
writings. On some points, Dr. Carpenter defined his own position in a paper
which appeared about a year before his death.*

Mr. I. A. Bather, in 1890, alsot agreed to accept this terminology with
very slight modifications, and applied it practically in his earlier descriptions
of British fossil Crinoids, but renounced it in 1892,+ and proposed in its
place a new one, which will be discussed later on. Many of the terms which
are explained below are familiar to every student of Crinoids; but as some
of them have been used in different senses by different authors, we include
them for the sake of completeness. A few of them are new; others, though
used by foreign authors, have never been introduced in American Crinoid
literature. We believe that the terms are adapted equally well for the
description of recent and fossil Crinoids, pinnulate as well as non-pinnulate.
There are a few additional terms, not of such general application, which
will be found explained in their proper places.

The Crinoids, Blastoids and Cystids, with perhaps a few exceptions,
differ from all other Echinoderms in being at some stage of their life pro-
vided with a stem for attachment to other objects. This structure gives
rise to a difference in habit, by which they live upon the aboral side, instead
of creeping about mouth downward in search of food.

The skeleton or test of a Crinoid consists of the stem or column, and the
crown. If the stem is provided with lateral appendages, these are called
cirrt. ‘Those of the distal end are the radicular cirri, and form the root.
The stem is constructed of the stem joints, of which the larger, and all cirrus-

* “On some Points in the Anatomical Nomenclature of the Echinoderms ;” Ann. and Mag. Nat. Hist.,
1890 (July number).

+ British Fossil Crinoids; ibid. (April number), pp. 306 to 330.
+ Suggested Terms in Crinoid Morphology; ibid. (January), pp. 51-66.

TERMINOLOGY. 35

bearing ones, constitute the nodal joints, and those interposed between them
the azternodal joints. The term dorsocentral is used for the enlarged terminal
joint of the stem, by which the young Crinoid is attached to other objects ;
and centrodorsal for the modified, cirrus-bearing top joint of the Comatule,
as well as for the plate within the infrabasal rmg of the Marsupitide. The
longitudinal canal, passing through the centre of the stem, is the azial canal,
In speaking of the form of the stem, allusion is made to the transverse
section.

The crown consists of calyx and arms; the former encloses the visceral
cavity; the latter constitute the free appendages, passing off from, and con-
necting with the calyx.

The calyx is composed of the dorsal cup, and the ventral disk or tegen, the
arm regions forming the line of demarkation between them. The dorsal
cup conforms in a general way to the apical or abactinal system of the
Kchinoderms, the ventral disk to the oral or actinal system. |

The dorsal cup, in its simpler form, is constructed of basals, infrabasals,
when present, and radials ; to which must be added the anal plates, which,
however, are not always represented. In the more complex form it includes
also some of the lower brachials, which have been incorporated into the
walls, either by lateral union among themselves, or by means of interradial
and interaxillary plates; the last mentioned plates, in that case, also form-
ing part of the cup. All Crinoids belonging to the simpler form are dis-
tinguished as Crinoidea Inadunata ; those of complex form, when the calyx. is
rigid, as Crinoidea Camerata, but when flexible, as Crinoidea Articulata.

The dase, or part next to the column, may be composed of one or two
rings of plates, which are distinguished as dasals and infrabasals. The basals
adjoin the radials and alternate with them, being interradial in position.
The infrabasals, when present, are radially disposed below the basals. Cri-
noids in which the base consists of a single ring of plates are called mono-
cyclic; those with two rings, dicyclie.

The radials consist of the first plate of each ray, and all plates beyond
this in radial succession are brachials; fixed brachials so far as they take
part in the calyx, free brachials or arm plates when they do not. In some of
the earlier Crinoids one or more of the radials are bisected transversely, in
which case the two parts are distinguished as super-radials and infer-radials.

The arms may be simple or branching. When the divisions are of equal

size, and rise to the same general height, they are regarded as parts of the
5

34 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

arms proper; but when smaller and shorter than the main arms, they are
called armiets. If there are small lateral appendages, given off alternately
from opposite sides of the arms, they receive the name pinnules. The arms
are uniserial when their joints extend through to both sides of the arm;
biserial when they do not, but interlock from opposite sides.

The brachials succeeding the radials (the first axillary included), whether
free or fixed, are called costals, or primary brachials; those of the second
order distichals, or secondary brachials; those of a third order palmars; and
all succeeding brachials, whether there are additional divisions in the ray
or not, receive the name post-palmas. When in the description of a species
it is necessary to specify any of these plates, they are distinguished as
brachials of the fourth, fifth, or sixth order, and so on to the last bifurcation.
We also find it convenient occasionally to refer to them as the plates be-
yond the fourth, fifth, or sixth axillary ; or, when free, as plates of the first,
second, or third division of the arms. The plates of the different orders,
according to their rank, are distinguished as first, second, or third costals,
distichals, palmars, etc., and the bifurcating plates as the azillaries of their
respective orders. All these appellations, however, are not applied to the
divisions formed by the armlets and pinnules, although the plates which
support them are in fact axillary, and each armlet or pinnule is morpho-
logically the homologue of a whole dichotom. |

When two or more arm joints meet transversely by a rigid suture, and
only the upper one is pinnule-bearing, those joints form a syzygy, whether
the apposed faces are radiated, dotted, or smooth; the lower joint bearing
no pinnule is called the hypozygal joint, the upper one the epizygal.

The spaces between the rays and their subdivisions are filled by supple-
mentary plates. ‘Those between the rays proper are designated by the
general term ¢terradials, whether they belong to the dorsal cup or to
the ventral disk. Those of the dorsal cup, which are interposed between the
brachials, are distinguished as interbrachials, and those of the ventral disk,
which lie between the ambulacra, as dnterambulacrals.. Plates between the
radials at all five sides are only found in dicyclic Crinoids, but in most of
the Paleozoic Crinoids there are one or more such plates at the posterior
side — the so-called anal plates.

The anal plates form the base of the anal structures, and consist of the
special or first anal plate, which, when present, invariably rests upon the
truncated upper face of the posterior basal, and between two radials. Most

TERMINOLOGY. 35)

of the Camerata also have auxiliary anal plates, which may be present even
when the special anal is wanting; they are interposed between the inter-
brachials, following the median line of the posterior area. Another plate,
the so-called “second anal plate” of American authors, which only occurs
in the Inadunata and Articulata, is now called the radianal. It rests within
the re-entering angle of two adjoining basals to the right of the first anal
plate, and is the lower half of a bisected radial, which only in some genera
assumes anal functions.

Certain groups have interaxillary plates, which occupy the spaces within
the axil of the distichals and palmars; the plates between the former are
the iterdistichals ; those between the latter the interpalmars.

The ventral disk embraces the disk ambulacra, the mouth, and the anus.
It is formed by the orals, the ambulacral and interambulacral plates. The
posterior side of the disk in certain forms of the Inadunata, to which we
have given the name Jnadunata Fistulata is extended upward into a large sac
or tube, which is called the ventral sac or ventral tube. This tube is frequently
perforated by pores or slits, which probably promoted respiration. Other
forms of that group do not have these pores through the sac, but have
a single, rather large, profusely perforated plate upon the disk proper, be-
tween the sac and the mouth, — the so-called madreporite. The disk in most
of the Camerata has small respiratory pores or slits near the arm bases, pierc-
ing the sides of the plates. In recent Crinoids, and probably in the Articu-
lata generally, in which the pores penetrate the body of the plates, the
perforated plates have received the name an-ambulacrals.

The anus is interradial in position; its opening may be either central,
subcentral, excentric or marginal; placed at the distal end of a tube, or
opening directly through the disk. : |

The “anal” tube must not be confounded with the “ ventral” tube of the
Fistulata, which often does not contain the anus, but when it does, the
opening is generally on the anterior side.

The mouth occupies the centre of radiation, and is fegminal or subtegminal.
If it is ¢egnunal, the opening is surrounded either by the orals and the ends
of the ambulacra, or, when the orals are absent, by interambulacral plates,
which form a lip around it. If swbtegminal, it is completely closed, either by
the orals or interambulacral plates, which form a roof over it.

The ambulacra diverge from the mouth to the tips of the rays, following
the ventral furrows of arms and pinnules. When subtegminal, they enter

36 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the calyx by means of the ambulacral or arm openings at the upper edge of
the dorsal cup; when tegminal, they follow the surface of the disk. They
contain the food-groove, the ambulucral vessels, the ovarian tube, and the axial
canal. 'The food-groove forms the upper passage. It is followed in descending
order by the subtentacular canal, the genital canal, and the avial canal. The
axial canal contains the awial cords, which communicate with the chambered
organ at the dorso-central basin of the calyx. The axial canals, in most of
the Palseozoic Crinoids permanently, and in the Antedon larva temporarily,
are mere grooves at the bottom of the ventral furrow, but in the mature
recent Crinoid, and in a few Palsocrinoidea, are separated from the furrow
_by a limestone partition.

The ambulacral plates consist of the ad-ambulacral or stde-pieces, and the
covering plates, or Saumpliitichen; the former, when present, constitute the
outer, the latter the inner rows of the plates. The covering pieces form
a roof over the food grooves, and are generally represented by two alternat-
ing rows of small, more or less regularly arranged plates, which in all
Crinoids are movable upon the arms and pinnules, but upon the disk only
in those in which the mouth is exposed. In some of the Camerata the
plates are so highly differentiated, that they have been regarded as alto-
gether different structures, and were called radial dome plates. We retain
' this name as a conventional term for the large isolated plates of that group
to distinguish them conveniently from the ordinary covering pieces.

The orals consist of the five large interradial plates which surround the
_ mouth or cover it, and are either symmetrical or asymmetrical. They are
symmetrical when of nearly the same size and form; asymmetrical when
the posterior plate is pushed in between the other four. In some species
they occupy the entire ventral surface of the calyx; in others, only a com-
paratively small space in the middle; or they may be completely resorbed
in the mature individual.

The «terambulacral plates occupy the spaces between the ambulacra,
their main trunks as well as their branches. We also apply the term to the
plates covering the ambulacra, and to those encroaching upon them from the
sides, as in many species of the Camerata in which the disk ambulacra are
subtegminal or partly so.

The term perisomie plates is given to all plates which are originally devel-
oped from simple, cribiform films of limestone. They comprise the inter-
radials and interaxillaries, the anals, and all ambulacral and interambulacral
plates.

TERMINOLOGY. j oak

The plates of a Crinoid are united either by suture or by muscular
articulation. The former may be a close suture, a loose suture, or an anchy-
losis. A close suture is nearly or perfectly rigid; the apposed faces are flat,
and may be smooth or striated. In a loose suture the faces are more or less
concave or excavated, lodging bundles of ligament, so as to give to the
plates a considerable amount of mobility. An anchylosis is a modified close
suture, in which the lines of union have been obliterated by subsequent
limestone deposit. In a muscular articulation, the apposed faces are per-
forated, and provided with a transverse ridge, or a sort of ball-and-socket
joint.

The orientation is based upon the natural position of the Crinoid, @. e.,
the arms uppermost, viewing the specimen from the anal side. The anal
interradius will then be posterior, the radius opposite to it anterior, and
right and left will correspond with the right and left of the observer. Next
to the anterior ray are the two antero-lateral rays,* and adjoining the anal
interradius the right and left posterior rays. Corresponding appellations are
applied to the interradial spaces, which consist of the two anterior, the two
antero-lateral, and the posterior or anal, interradii.

In illustrating the plates of the calyx, the dorsal view is figured with the
anal interradius wp, and the ventral view with the anal side down. Right and
left remain the same in both cases. ,

The terms proaimal and distal ave reckoned from the chambered organ, so
that the infrabasals and the top-stem-joint are the proximal elements of
crown and stem respectively. In the crown, the outer surface of a plate
represents the dorsal side, its lower edge the proximal face, its upper edge
the distal face, and the faces at the sides are the lateral faces. In the stem,
however, the wpper face is the proximal, and the lower one the distal.

* These rays are called by Mr. Bather the right and left “anterior” rays. The term is objectionable
because we have already the anterior ray proper.

MORPHOLOGICAL PART.

PRIMARY AND SUPPLEMENTARY PLATES.

_ Tue plates of the Crinoids fall naturally into two categories, viz., primary
plates, and secondary or supplementary plates. The primary plates are the first
parts developed in the larva. They are represented in every group of the
class, and undergo comparatively few modifications in geological time. The
supplementary pieces appear in the growing Crinoid, but are unrepresented
in some of the groups. They are interposed between the primary plates,
and help to increase the capacity of the visceral cavity. They are very im-
portant in point of classification, offering by their presence or absence, their
position and distribution in the calyx, their arrangement and multiplication,
excellent criteria for natural divisions.

The primary plates may be subdivided into two classes: plates of the
abactinal system, and plates of the actinal system. The former are developed
on the right larval antimer, and include all plates connected with the cham-
bered organ and the axial cords.. The latter are developed on the left anti-
mer, and communicate with the mouth and the annular vessels surrounding
it. The abactinal plates are represented by the stem joints, the basals,
infrabasals, radials, and the plates forming the dorsal parts of arms and
pinnules; the actinal plates by the orals and ambulacral plates to the ends
of the brachial appendages. The remaining plates will be treated by us as
supplementary pieces.

I. THE PLATES OF THE ABACTINAL SYSTEM.

A. The Stem and its Appendages.

The length of the stem in some Mesozoic Crinoids must have been enor-
mous. Quenstedt traced that of a Jurassic Pentacrinus to 70 feet without
reaching either end. This is in striking contrast to its length in Palzxozoic
forms. Among them the two longest stems observed by us have a length of

MORPHOLOGICAL PART. 89

about three feet, — one, not quite complete, being that of a large Megistocrinus
Evansi, the other, which is perfect, of a Strotocrinus regahs, two of the largest
known species. That seems to have been about the maximum length, and
it may be safely asserted that the stem in the majority of the older Crinoids
was not much over a foot long. Some stems are proportionally wider at the |
top, and taper all the way to the root; others are larger at the distal end
than at the proximal; while still others are widest in the middle.

The root is even more variable. Its form was evidently accommodated
to the conditions of the place of its attachment. When attached to a solid
substance, it was flattened at the distal face, the radicular cirri spreading
out horizontally; but when growing on an oozy bottom, it gave off long
vertical and lateral branches, entering the mud.

The stem is either circular, elliptic, pentangular, stellate, semilunate, or
quadrangular, changing from angular to round on approaching the root. It is
composed of joints, which vary often considerably in size. Certain of these
joints, which have been denominated “ nodal” joints, are separated from each
other by intervals of different lengths, which are filled by internodal growth.
The nodal joints are not only longer than the internodal ones, but also
wider, and, as a rule, increase in length downward. Their diameter is
greatest in the upper part of the stem, where in some species of the Came-
rata it is often twice, and exceptionally three times, that of the internodal
joints. The projecting margins are sometimes knife-like, the edges occa-
sionally crenulated, spinous, or nodose. The greater amount of length
which characterizes these joints, however, does not extend to their full
thickness, but is more or less restricted to the projecting margins, the
middle part at both ends being depressed, so as to enclose wholly or in
part the adjacent internodals.

In the growing Crinoid, the stem constantly imereased in length by the
production of new joints, introduced either directly beneath the calyx, or at
some distance from it. The joints which are formed at the proximal end of
the stem gradually developed into nodal joints, and all those intervening
comprise the internodal joints. The nodal joints of the Inadunata and
Camerata, and also of many of the later and recent Crinoids, were intro-
duced directly beneath the basals and infrabasals respectively, so that the
uppermost joint was always the youngest joint of the stem. But in the
young Comatula, in which the top joint subsequently develops into a centro-
dorsal, in the recent Mesozoic Jdleriermus, and probably in the recent Rivzo-

40 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

crmus and Calamocrinus, and in all Ichthyocrinidse, so far as observed, the
new nodal joints were formed beneath the top joint, and the latter remained
permanently attached to the calyx. In Apzocrinus, in which for some dis-
tance the upper end of the stem is greatly inflated, and the proximal joints
extremely long, it 1s possible that the nodal jomts were introduced below
the inflated part, for there appear to be no immature segments between the
upper joints.

The internodal joints, as stated, are placed between the nodal ones; and
the spaces which they occupy, and which continually increased in length and
width in the growing Crinoid, are the internodes.

The increase in the length of the internodes took place gradually in a
downward direction — as may be seen by comparing the stem of a young
specimen with that of an older one — and pari passu with the formation of
new joints just below the calyx. Hence in the upper part of the stem there
is a yarlable number of premature internodes. Those nearest the calyx are
the shortest, and consist of the smallest number of joints; while the inter-
nodes in the lower part of the stem all contain the same number of pieces,
and all joints have approximately the same proportions. The joints of the
upper part vary in the same internode from a growing leaflet, invisible in a
side view, to an almost fully developed joint; and the upper internodes fre-
quently consist of single pieces. But they are followed more or less rapidly
by internodes of two, three, or as many more ossicles as it required to com-
plete the maximum number of the species, the younger joints being inserted
next to the older ones, which are distinguished by their greater prominence.
In the upper part of the stem, the joints of subsequent growth are readily
recognized, in some species more so than in others; but toward the terminal
end, where all ossicles attain almost an equal size, it is often difficult. The
stem matured from the root up, and remained at the upper end permanently
in a state of immaturity.

The maximum number of internodal joints varies considerably among
the species. There may be only one or two to the internode throughout
the stem, or many more. The largest number observed in Paleozoic Cri-
noids is about fourteen ; but among recent Pentacrinide as many as forty-
five have been counted, and as many as seventy in Mesozoic species.

The internodes of some species begin at quite a distance from the calyx,
while others have no internodal joints at all. The former is manifestly the
case in certain genera of the Ichthyocrinidx, in which the upper part of the

MORPHOLOGICAL PART. 4]

stem is enlarged somewhat as in Apiocrinus, except that the joints of the en-
larged part in the Ichthyocrinide are very short, and increase but ver y
slightly in length downward. These plates, which have no internodals inter-
posed, extend to the full length of the inflated part, and their number varies
in different species from about twenty to fifty, but is constant, or nearly so, -
in the same species. They are followed distally by a large prominent
joint, from which the internodes begin. The latter are formed in the usual
way, larger and smaller joints following each other at intervals, and the
nodal joints are rather prominent.

The stem of a Platycrinus has generally no internodes, and all young joints
were introduced next to the basals. The joints are elliptic, and the apposed’
faces of the joints throughout this genus are provided with articular ridges,
which follow their long diameters. A similar structure occurs in the recent
Lthizocrinus and Bathycrinus, and both of them are apparently destitute of
internodals. The Silurian Marsupiocrinus, however, with a circular stem,
which is otherwise most closely allied to Platycrinus, always has well defined
internodes ; and this forms perhaps the best distinction between the two
genera.

The absence of internodals is not confined to specimens with elliptic
stems, or to those with articular ridges. They are wanting also in Mespi-
focrinus with a round stem, and in which the joints rapidly attain a length of
from three to four times their diameter (Plate IL, Fig. 3). In Rhodocrinus
there is, so far as observed, but a single ossicle to each internode, and
throughout the stem a larger plate alternates with a smaller one.

In a few Paleozoic Crinoids, the whole stem is divided longitudinally, its
joints being either quinque- or tri-partite. The former is the case in Ohjo-
ermus, Hetenocrinus, Barycrinus,, Anomaloerinus, and probably others; while a
tri-partite stem has been observed only in Heterocrinus. The stem segments
alternate with the proximal plates of the calyx; 7. ¢., they are interradial
in dicyclic, and radial in monocylie Crinoids.

Most Crinoids are provided with cirri, which are given off from the nodal
joints at intervals, either throughout the whole length of the stem, or only at
its distal end. The former is more generally the case among the later Cri-
noids, while in the majority of Palsozoic forms the cirri are restricted to the
lower part. In Neocrinoids they are more regularly distributed, and occur
in whorls; in Paleeocrinoids they are generally arranged singly, and at irregu-

lar intervals. The Pentacrinide have five cirri to each nodal joint, which
6

iD THE CRINOIDEA CAMERATA OF NORTH AMERICA.

are invariably radial in position; or three cirri from one node, and two
from the adjoining ones, so arranged that the cirri of two joints corre-
spond in position to the five of the one joint. The size of the cirri varies
among species, some being much stouter than others and also longer; but as
a rule, they increase somewhat in length downward, and taper to the end.
They move rapidly, according to A. Agassiz,* quicker than the arms, and are
used ‘as hooks to catch hold of neighboring objects, and on account of their
sharp extremities are well adapted to retain their hold.”

The functions of the cirri in Paleozoic Crinoids were probably more
limited than in recent ones, for in most of them any rapid movement
would be incompatible with the structure. This is especially the case
with those of the Camerata, and it may be a question whether these
appendages should not receive a different appellation.

The cirri of the Camerata, except perhaps those of certain species of
Dichocrinus, are mere branches of the stem, and were obviously capable of
very little motion. They occur only in the lower part of the stem, and in
many cases were probably restricted to the root. They rest within sockets,
formed at the sides of the stem by a truncation or excavation of one or more
stem joints. In Platycrinus, in which we have observed the complete stem
more frequently than in any other genus, they generally occupy from one-
fourth to one-third of its length, and, being given off invariably from the
longer diameter of the stem, they follow its twist. In some of the species,
each successive joint is cirrus-bearing, either at both sides of the stem or one
side alternately. In others, the cirri are given off at irregular intervals, and
vary considerably in length and width. Throughout this genus they are at-
tached to one stem-joint only, which, when the base of the cirrus is larger
than the usual length of the joint, is lengthened on that side to accommo-
date it. The radicular cirri are larger than the others, and are generally
provided with numerous small branchlets. The distal end of the stem also
terminates in a sharp point.

In stems with internodal joints, the cirri do not rest alone against the
nodals, but the adjoining internodals share in the formation of the cirrus
sockets. In some species the sockets involve only the adjacent joint above
and below ; in others, two or three of them; but the cirrus canal invariably
communicates with the axial canal of the stem through the nodal joint. The

* Letter No. 5, on the Dredging Operations of the U. 8. Coast Survey steamer Blake, from December,
1878, to March 10, 1879. Bull. Mus. Comp. Zoél., Vol. V., p. 296.

MORPHOLOGICAL PART, | 43

cirri, although they may be arranged singly at wide intervals, are located
radially in dicyclic Crinoids, and interradially in monocyclic ones. This is
readily perceived on pentangular stems, in which the cirri rest within the
retreating angles of the joints, so as to alternate with the salient angles, and
hence are in line with the salient angles of the axial canal.

The length of the cirri among Camerate Crinoids was very variable, and
they were in some species quite formidable. We have in our collection a
fragment from the lower part of the stem, apparently of Batocrinus grandis
(Plate L, Fig. 2), measuring 11 cm. in length, and tapering from a diameter
of 10 mm. at one end to 7 mm. at the other. It gives off numerous cirri, of
which those of the thicker or upper end are but little thinner than those of
the lower. Three of the lower cirri are preserved to a length of 16, 154, and
15 cm. respectively, and may have been much longer, as they taper but
little, still having at their ends a thickness of 2} to3 mm. Five other cirri
are broken at a length of from 11 to 37 mm., and eight consist of only two
to five joints ; while the sockets of three others are empty. The sockets are
deeply excavated, and extend to nine joints, the surface being radiated. The
distal faces of the joints are slightly concave, the proximal joints shorter than
the distal, and the central perforation is round and of moderate size. Two
of the cirri in this specimen have a remarkable cyst of 14 to 18 mm. in
length by 9 mm. greatest width, one forming the distal end of the longest
cirrus, the other commencing about 8 mm. from the stem. The two thickest
joints in the inflated part of the one are nearly 4 mm. long, while the length
of the joints above and below the inflation does not exceed 11 mm. Similar
cysts are frequently found along the stem, but have not before been ob-
served to occur on the cirri. They resemble the Myzostoma cysts, which
occur along the arms of recent Comatule, and like them were evidently
caused by parasites.

In another stem fragment from the Upper Helderberg of Louisville, Ky.,
every joint is cirrus-bearing, and most of them have five large cirri — some
four or three — which almost touch those above and below. ‘The cirri are
preserved to a length of 35 to 40 mm., and were probably much longer
(Plates, Mig. 23)),

The cirri of the Actinocrinide generally extend to one third the height of
the stem. They vary greatly in size, and are arranged at rather wide inter-
vals. The same structure probably prevailed in the Ichthyocrinide, at least
in Onychocrinus and Taxocrinus ; while in the Calyptocrinide cirri occur only

4a THE CRINOIDEA CAMERATA OF NORTH AMERICA,

at the distal end, where they form a large root with hundreds of small, very
delicate branchlets.

In Dichoerinus the distribution and length of the cirri are extremely vari-
able. In some species they only occur at the lower part of the stem, where
they are short and arranged far apart. In others they continue up to near
the calyx, and are quite long. The former is the case in D. inornatus, in
which they are singly arranged, and rather slender. In D. parvulus and
D. delicatus, however, they follow the whole length of the stem, and are
arranged in sets of two or more, which are so long that the tips of the upper
ones reach up to the arms. But the most remarkable cirri occur in the
Carboniferous Camptocrinus myeledactylus (Plate LXXYV. Figs. 1 and 2) and
C. cirrifer (Plate LX XVI. Figs. 13 a, 6, c), in which they begin at a short
distance from the calyx. The stem, as usually found in these species, is
coiled around the crown; the joints are circular at the top, but gradually
become crescent-shaped, the concave side of the crescent directed to the
inner side of the coil, and both its horns giving off extremely long cirri from
alternate sides. Very similar cirri occur in the Fistulate genus Herpetocrinus,
from the Silurian of Europe.

Glyptocrinus apparently had no cirri at all, not even at the distal end,
and the stem was probably attached like that of the Comatule in their
larval state by means of a dorso-central, i. e., the enlarged terminal plate.
Rhodocrinus nanus and KR. Kirbyt have a few scattered cirri at the lower end,
singly arranged.

The cirri of the Inadunata, so far as observed, are not only more slender,
but were apparently more flexible than those of the Camerata, and they
pass up more frequently to the top of the stem. The latter is often the case
among the Poteriocrinidx, especially in Scaphiocrinus and Gtraphiocrinus, in
which the nodal joints have variously from one to five rather delicate cirri.
That these appendages were highly flexible is shown by the fact that they
bend in all directions, — some being straight, others curling, some directed
upward, others downward, —a feature very different from that shown in the
Platycrinide, Actinocrinidx, and Batocrinide.

Belemnocrinus jflorifer has very long and slender interradially disposed
cirri, which extend to the full length of the stem. It has three or four from
each nodal joint, the upper ones directed upwards, and extending to half the
height of the arms. J. typus, on the contrary, has no cirri to a length of
13% cm., and the stem is circular instead of stellate.

MORPHOLOGICAL PART. 45

In the Cyathocrinidee the structure at the lower part of the stem is only
known in BLarycrinus. In Cyathocrinus we have examined the stem to a
length of 10 cm., and in Parisoerinus to about 18 cm., without finding any
traces of lateral cirri. Neither have these been observed, so far as we know,
among the Anomalocrinidse or Hybocrinide; but in Homocrinus scoparius
they occur at the lower half of the stem.

The stem of Baryerinus is quinque-partite, and enlarges gradually to the
root, where its diameter in extreme cases reaches from 30 to 40 mm. The
root consists of five main rami, which branch into smaller ones, so located
that the longitudinal sutures of the stem bisect the rootlets, and the large
central canal, which is sharply pentangular in the stem, becomes elliptic or
linear within the branches; the latter is also the case in Ancyrocrinus, of
which we shall speak presently.

The axial canal is central, and extends to the full length of the stem,
giving off branches to the cirri, The main canal is circular, angular, or pen-
talobate ; that of the branches sometimes elliptic, the long diameter vertical.
If pentangular, the angles are directed radially in dicyclic Crinoids, and
interradially in monocyclic, thus alternating with the projecting angles of
the stem joints. ‘To this rule, however, there are two exceptions, and, so far
as we know, only two. In Pentacrinus,and the monocyclic Glyptocrinus Forn-
shelli S. A. Miller, the axial canal has the same orientation as the outer angles
of the stem. This is very remarkable, and we shall consider it further in
discussing the basals and infrabasals. The canal in some species is quite
minute, in others very wide; while in still others the central canal is sur-
rounded by three, four, or five peripheral canals, as in the case of Cupresso-
crinus, in which pentamerous symmetry in the stem is the exception.

In recent Crinoids the innermost part of the central canal is the internal
vascular axis, and consists of five peripheral vessels arranged around a cen-
tral one. The former are downward extensions from the chambers of the
quinquelocular organ at the base of the calyx, which are connected with the
axial vessel of the chambered organ. Whether such vessels also existed
in the stem of Paleozoic Crinoids, of course cannot be ascertained from
the fossil; but that a quinquelocular organ, with upward extensions to
the. arms, was present in some of them, is indicated by the structure of
Eupachycrinus, Catillocrinus, and Agassizocrinus, where the inner floor of the
basals and radials is apparently perforated. Carpenter* thinks it probable

* Journal of Anatomy and Physiology, Vol. XII., p. 44.

46 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

that the peripheral canals of Cupressocrinus, which consist variously of three,
four, or five separate passages, correspond to the peripheral vessels of Penta-
crinus, Riuzocrinus, and other recent Crinoids. He directed attention to the
fact that there 1s among different individuals of the same species considerable
variation in the isolation of these vessels. In some species, in which the
canals appear to be continuous, there is but one large tri- or tetra-partite
perforation at the base of the calyx and throughout the stem, which he
thinks enclosed the four, five, or six separate vessels of other specimens.
This may be so, although we cannot quite understand how the three or four
peripheral canals, where they exist, can be extensions of a quinquelocular
organ.

The variation in the size of the axial canal among Paleozoic Crinoids is
most remarkable. In Platycrinus the canal is sometimes no larger than the
point of a needle; while in Barycrinus, Crotalocrinus, Enallocrinus, Megistocrinus,
Pervechocrinus, etc., it is often from one half to even three fourths the width
of the joints, and is either round or pentangular. In some of them the walls
within appear as if built up of thin lamin with spaces between, sometimes
pectinated and variously sculptured, producing a great multiplication of
exposed surfaces. In Barycrinus, with a quinque-partite stem, and a sharply
stellate canal, of which the projecting angles are directed radially toward
the suture lines, the trigonal inward extensions of the canal are pierced
by one or more rather large pores, which pass through the body of the
plates, so as to enter the outer faces of the stem, as shown on Plate I.
Figs. 6 and 8 a, 6. Five other series of pores follow the longitudinal suture
lines, and these also communicate with the central canal.

In the Crotalocrinidse and Periechocrinites, in which the central cavity is
proportionally still larger than in Barycrinus, the inner structure appears to
have been less complex ; but its extreme size in both groups, compared with
that of other Crinoids, and especially with recent ones, seems to imply that it
was not a mere axial canal, but performed additional functions.

We have in our collection the root of a large Barycrinus (Plate I.
Fig. 7), which must have been attached to a smooth, solid substance, for
the lower surface of the root is perfectly flat. In this root only two of the
five primary branches were developed, and these are but partly preserved,
but enough is seen to show that they had been placed on a level with the
truncated lower face of the main trunk. The development of the other
three cirri seems to have been checked by contact with the bottom, but their

MORPHOLOGICAL PART. 47

outlines are faintly mdicated along the edges of the specimen. The middle
part of the truncated lower face is perfectly flat, and there are no traces
shown of an axial canal, But in an outward direction we find grouped
around a closed centre numerous small canals connecting with the interior.
These canals form upon the surface well defined ramifying grooves, which
pass out to the periphery, and seem to communicate with the surrounding
water. In another detached root, likewise with a flat bottom, the rami-
fications at the distal end were not exposed in the specimen, but were
opened out by grinding. The specimen has two root trunks of equal size,
which are united at the bottom by an irregularly formed limestone deposit,
and around the projecting truncated lower end there are a number of
small openings, which connect with the canals from the two rootlets.
Whether the cirri of all Paleozoic Crinoids open out at their ends, will
perhaps never be satisfactorily ascertained. We may state, however, that
the finest hair-like branches which have come under our observation are
perforated at their extremities.

When in the Revision we directed attention to the variations in the size
and complexity of the axial canal (Part I., p. 15), we suggested that the
column was probably in some cases, and perhaps in all Paleozoic Crinoids,
subservient to respiration. To this Dr. P. H. Carpenter* replied that he did
not think it unlikely that the pores near the base of the column may have
served to admit water into the stem, and thence into the coelom; but he
doubted if the canals opened at the ends of the rootlets, concealed as
they were below the surface of the ooze, as the water introduced to the
stem by these passages could not have been very useful for respiratory
purposes. Neumayry regarded the stem of the Crinoids a greatly medi-
fied organ, whose original form could only be explained by the structure of
certain Cystids; and he thought it was primitively, as it is in that group,
a sac-like extension of the calyx, and was plated in a similar manner. In
corroboration of bis views, he alludes to our observation that in Crinoids
with pentangular stems the faces and angles of the stem occupy a definite
position to the proximal ring of the plates in the calyx.

Similar views were expressed by A. Agassiz.t He says: ‘‘ That the pen-
tagonal stems hold a definite relation to the calyx has been clearly shown

* Quart. Journ. of Geol. Soc., 1880, pp. 555-557.
+ Stamme des Thierreiches, p. 430.
+ Calamocrinus: Mem. Mus. Comp. Zool., Vol. XVIL., p. 63.

48 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

by Wachsmuth and Springer, and goes far to prove that the stem must
originally have had a far more intimate connection with the calyx than its
representatives of to-day have ; and the fact that in a number of Paleozoic
Crinoids the axial canal is very wide, compared with that of recent types,
seems to indicate an additional function to that of the axial canal, which, as
Neumayr suggests, we cannot explain from recent representatives.”

The apposed faces of the stem joints, with a few exceptions, are marked
by a series of more or less well defined angular ridges and alternating fur-
rows, which radiate from the opening of the central canal toward the dorsal
margin of the joints, but occasionally are restricted to their marginal por-
tions, The principal ridges alternate with smaller ones, which do not extend
as far inward as the others, and all ridges of one joint meet corresponding
furrows of the apposed joint, which gives to the suture its serrated outline.
The faces of the joints are flat, or slightly curved, the nodal ones having
sometimes a slight crest around the canal, which fits into a corresponding
depression of the apposed internodal. This indicates that the motion of the
stem was quite limited, and, as Carpenter remarks, “only of a passive char-
acter, due to the current of the water, etc., and independent of the will of
the animal.” On coming in contact with other animals it was capable of
bending sideways, and of returning to its natural position when the obstruc-
tion was removed.

In Platycrinus and Bourgueticrinus, in which the faces of the stem joints
are elliptic, their surfaces are provided with a well defined transverse ridge
following the long diameter of the joints, with. fosse at both sides, and
surrounded by a marginal reticulation. The ridges follow the twist of the
stem downward, admitting motion in all directions. In these families there
seems to have been a sort of rudimentary articulation between the suc-
cessive joints, while in the other families there was only a loose sutural
union.

As to the habits of Crinoids, very little is yet known, even of the recent
ones. We know that in their pedunculate state the Comatule were fixed
by means of a large plate, the so-called dorso-central; and this led to the
belief that all Stalked Crinoids were permanently attached in a somewhat
similar manner, But this has never been satisfactorily proved, and, as we
know now, is not always the case with the recent Pentacrinide. The distal
end in most Paleeocrinoidea tapers rapidly and uniformly to a point, and the
terminal branches are given off from several joints, and not from a single

MORPHOLOGICAL PART. 49

one, except In a very ‘few cases. In the Hudson River group of Cincin-
nati we occasionally find crinoidal disks, attached to pieces of coral, which
closely resemble the dorso-central of Antedon. These disks have a pit or
depression at the middle of the upper face, sometimes enclosing a small
stem joint. They are irregularly round, and some of them have small pro-
cesses passing outward from the sides, which seem to represent primitive
cirri (Plate I. Figs, 9, 10). It is now worthy of note, that we find in
the same beds some remarkable crinoidal stems, with their lower ends wound
around some stem fragment or other object, almost as neatly as thread
upon a spool, the column gradually tapering as it coils, and becoming very
small at the end.* It has always seemed to us that these stems and the
terminal plates belonged together, and were separated during the life of the
Crinoid. Detached roots are found in considerable numbers at Burlington
and Waldron, and in almost every case the root parted from the stem a little
above the radicular cirri; but it is curious that hardly ever are parts of
the crown found associated with them. From these facts we may infer that
the stem, at least in some cases, became detached from the root, so that the
Crinoid could change its place of attachment. A detachment of this kind
actually took place in a large number, if not in all, recent Pentacrinide, as
shown by Sir Wyville Thomson, P. H. Carpenter, and others. The former
describes this structure in Pentacrinus Wyville-Thomsoni as follows: “ All the
stems of mature examples of this species end inferiorly in a nodal joint
surrounded by its whorls of cirri, which curve downwards into a kind of
grappling root. The lower surface of the terminal joint is in all smoothed
and rounded, evidently by absorption, showing that the animal had for long
been free. I have no doubt whatever that this character is constant in the
present species, and that the animal lives loosely rooted in the soft mud,
and can change its place at pleasure by swimming with its pinnated arms;
that it is, in fact, intermediate in this, respect between the free genus
Antedon and the permanently fixed Crinoids.” Carpenter found a number
of other species of Pentacrinus, and some of Metacrinus, in the same condition.
Roots apparently of Pentacrinus, and belonging to mature or almost mature
specimens, are occasionally found on telegraph cables, but so far as we know,
minus the crown and main part of the stem; and it is quite probable that
all Pentacrinide were able to detach themselves and float about.
* 8. A. Miller: Journ. Cincin. Soc. Nat. Hist., Vol ITI. Plate 7, Fig. 32.

+ The Depths of the Sea, pp. 449-444.
7

S10) THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Carpenter * further states that in Pentaerinus Wyville-thomsoni the nodal
joint from which the separation takes place “sometimes loses its ordinary
characters altogether, becoming much enlarged and rounded below so as to be

y)

almost hemispherical in appearance.” And in a foot-note he says: “The un-
usual enlargement of the nodal joint suggests the idea that the structures
which have been described by Hall under the name Ancyrocrinus | may be the
detached stems of a Paleeocrinoid in the semi-free condition,” —in which we
fully agree with him. Aneyrocrinus has the form of an anchor, with four hook-
like processes around a central ascending stem, which at its distal end is
provided with a small, rounded tubercle, closing the opening of the central
canal exactly as in some cases of Pentacrinus. That this stem is morphologi-
cally in the same condition as that of Pentacrinus, nobody will deny after
examining the specimens. The four lateral extensions were doubtless radi-
cular cirri, whose joints were obliterated by calcareous overgrowth, as in the
lower part of its tetramerous stem.

Something similar to this may have taken place in other Paleozoic Cri-
noids; and it is quite probable that the terminal end, as it appears in the
specimens, is in many cases not homologous with the part by which the
young Crinoid had been formerly attached, but is a product of later growth.
We suspect this to be the case in the Actinocrinids, Platycrinide, and other
forms in which the terminal part tapers rapidly to a point, and cirri are
given off from the sides. It would not be a great departure from the
structure of the Comatule, if we bear in mind that their centro-dorsal is
a modified stem joint, bearing cirri upon its outer surface. The only
essential difference would be that in the Paleocrinoid the stem separated
at its dower end, and in the Comatule at the wpper.

That the young Palaocrinoid in its early life was attached by a dorso-
central, we may fairly infer from what we know of the development of the
Comatulz, and from paleontological evidence. The indications, however,
leave it somewhat doubtful if the fixation was permanent. We believe that
in the majority of cases among the older Crinoids the stem was afterwards
separated from the root, and that the animal subsequently led a free
life. In only two instances do we know that Paleozoic Crinoids were
attached by what appears to have been originally a dorso-central plate: in

* Challenger Rep. on the Stalked Crinoids, p. 19, and foot-note.
{ Fifteenth Ann. Rep., N. Y. State Cab. Nat. Hist., 1862, pp. 89, 90.

/

MORPHOLOGICAL PART 51

“ Cheirocrins” clarus,* and in Eucalyptocrinus crassus,t both described by
Hall. In the former the plate is fixed to a stem fragment, and closely
resembles the plate figured by us on Plate I. Figs. 9, 10, having like that
small budding cirri. The Lucalyptocrinus is a young specimen, which may
have perished before reaching the free stage. Detached roots of this species
have been found in large numbers, even larger ones than that figured by
Hall. In some localities they are so abundant that they lie in contact in the
rock ; but they are very rarely associated with pieces of the stem proper, or
with parts of the crown. These roots seem to have been derived from a
central disk (dorso-central), from which the numerous branches were given
off in a similar manner as the immature cirri from the terminal plate of
“ Cheirocrinus”’ clarus. 3

Among recent Crinoids, such terminal plates have been found in connec-
tion with fragmentary stems in Calamocrinus Diomede Agassiz, and in Penta-
crinus naresianus Carpenter,§ in which the stem increases in width downward :
but it is uncertain in both cases whether the stem is fractured or had been
cast off by the animal. Different is the structure in a specimen of Rhizo-
crinus Rawsoni, figured by Carpenter, || in which it seems as if the dorso-central
is unrepresented. There are given off from the sides of the last stem joint a
few irregular cirri, directed downward, and the distal end of the joint is
closed, as in the case of semi-free Pentacrinoids. The last joint differs in no
other way from the joints above, and has the same form and length as the
preceding one.

Among Paleeozoic Crinoids we have seen the complete stem in upwards
of thirty specimens of various genera, but none of them had a dorso-central,
or a surface for attachment; the stems invariably terminate in a point. The
terminal portion, however, forms no part of the primitive stem, but is of
later growth, and probably served the same purpose as the lateral cirri.

Now if it is true that the young Crinoid was attached by a dorso-central,
as we may suggest from the ontogeny and phylogeny of the group, then all
these specimens are morphologically in about the same condition as the semi-
free Pentacrinide, and not essentially different from that of the free floating
Comatule. This interpretation seems far more reasonable than the sup-
position that these Crinoids were permanently attached. |

* New York State Cab. Nat. Hist.; Fifteenth Rep., Plate I. Figs. 17 and 18.

+ New York State Museum Nat. Hist.; Twenty-eighth Rep., Plate 17, Fig. 5.

¢ On Calamocrinus; Mem. Mus. Comp. Zoél., Vol. XVII. Plate 28, Figs. 2, 3, 4.
§ Chall. Rep. on Stalk. Crin.; Plate XXX. a, Fig. 4.

|| Ibid. Plate LIII. Fig. 7.

52 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

A permanent fixation of the Crinoids would perhaps restrict the geo-
graphical range of the species, whereas we know that some of them have
a very wide range. A majority of the species from the Lower Burlington
group at Burlington are found almost unaltered in the southwestern part of
New Mexico, and some in Arizona, and many species of the Keokuk group
have been traced from southern Iowa as far down as Alabama. And we find
in Scotland and eastern Russia, with but slight modifications, the same forms
which flourished in the Mississippi Valley during the epoch of the Kaskaskia

group.
B. Basals and Infrabasals.

The base of a Crinoid consists either of one or two rings of plates, to
which the terms “ basals” and “infrabasals” are applied. In dicyclic forms,
the infrabasals constitute the proximal ring of the calyx; the basals the next
circlet above. The former are radially disposed, the latter interradially.
The plates of either ring are in contact laterally, except the basals in a few
species of Zeacrinus and Calpioerinus, where the truncated lower angles of the
radials, and occasionally the radianal, reach down to the infrabasals. The
basals are followed directly by the radials, except in the Acrocrinids, in
which they are separated from the latter by a belt of auxiliary pieces, which
occupy a large part of the dorsal cup.

The term “basals” was applied by the earlier writers invariably to the
proximal ring of the calyx, and when there were two rings, the plates of the
upper one were called “subradials” by some authors, while others called them
‘‘parabasalia.” To Dr. P. H. Carpenter * belongs the credit of having been
the first to point out that in dicyclic Crinoids the so-called “ subradials”” —
and not the proximal ring — are the homologues of the basals in the mono-
cyclic base, and that the lower ring in the dicyclic forms is an additional
element in the calyx. He demonstrated that from a morphological point of
view the same set of plates cannot be interradial in one genus, and radial in
another, and he considered the basals, which alternate with the radials, to be
the representatives of the genitals in the Urchins. The force of his argu-
ment has been generally acknowledged, and the American authors writing
since 1879 have adopted Carpenter’s method, with the exception of S. A.
Miller, who still clings tenaciously to the old terms. Carpenter called the
plates of the proximal ring “ under-basals,” for which the term “ infrabasals ”

* “Oral and Apical Systems of Echinoderms.” Quarterly Journ. of Microscop. Sci., Vol. VIII.,
pp- 351-383. .

MORPHOLOGICAL PART. 7 53

has been substituted, at the suggestion of Prof. Zittel. But Zittel,* and the -
German Paleontologists generally, while admitting the homology, and the
name “ infrabasalia,” adopted the term “ parabasalia”’ for the upper ring of
plates in the dicyclic base, claiming that the word “ basals,” if applied to
the dicyclic base as well, might lead to confusion.

The practice of giving different names to sets of plates which are ad-
mitted to be homologous was justly criticised by Carpenter,t and. serious
difficulties arise as to which term should be applied in certain groups, where
infrabasals exist In some species and are wanting in others. Such a case is
presented by the Apiocrinida, among which de Loriol discovered rudimen-
tary infrabasals in two species of Mdlericrinus.t This family was previously
supposed to be monocyclic, and the base is described by Zittel as consisting
of five dasals, whereas in the two species above mentioned, the five corre-
sponding plates would be parabasals. There is a similar case among the Penta-
crinide, in which infrabasals are represented in one genus, — Hetracrinus.
In the Comatulee, in which, according to Bury,§ small infrabasals occur in
the ciliated larva, but disappear in the Pentacrinoid stages, the very same
plates would be “ parabasals”’.in the earlier stage, and basals in the later.
Carpenter is clearly right when he says that this terminology, instead of
making it easier to students, as claimed by the German Palzontologists,
would be the source of endless confusion.

A different interpretation of the basal plates was given by Dr. J. Wal-
ther.|| He accepts Zittel’s terms for descriptive purposes, but homologizes
the infrabasals with the basals of the Monocyclica, the “ parabasalia”’ with
the monocyclic radials; and he takes the radials of the Dicyclica to repre-
sent an entirely new element in crinoid morphology. This recalls the idea

99

of Lyon,** who took the basals of the Blastoids for “ primary radials,” and

the forked plates for “‘ secondary radials.” As Walther’s views are alto-
gether out of keeping with the facts of Paleontology, and also, as we now
know, with those of the embryology of recent Crinoids, any further discus-
sion of the subject is unnecessary.

The Comatulz have basals only in their earlier stages; during the later

* Handbuch d. Palaeontologie, Vol. I., p. 327.

+ Ann. and Mag, of Nat. Hist., July 1890, pp. 5-11.

+ Paléontologie Frangaise, Tome XI., Part I., pp. 553, 566.

§ “The Early Stages in the Development of Antedon rosacea.” Report of the Fifty-seventh Meeting of
the British Association at Manchester, 1887, p. 735. |

|| Untersuchungen tiber den Bau der Crinoideen, Paleontographica, 1886, Bd. XXXII., p. 189.
** Geol. Rep. Kentucky, Vol. III. p. 469.

54 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

period of Pentacrinoid life they are transformed into the “ rosette,’ which
closes the upper opening of the centro-dorsal cavity lodging the chambered
organ. The Hugeniacrinidx have no basals in the adult, and Carpenter sup-
posed that they were anchylosed with the radials, while Zittel and Jaekel
think they were enveloped by exuberant growth of the radials.

In all dicyclic Crinoids the basals, without exception, consist of five
plates, and the infrabasals either of five, three, or a single piece. The basals
of monocyclic Crinoids vary in number from one plate to five.

The proximal ring, whether consisting of one, two, three, or four pieces,
whether basal or infrabasal, is divisible into five elementary plates; and the
smaller number, where it exists, is produced, as we shall presently show, by
anchylosis of two or more of the primary segments, accompanied by a more
_ or less complete obliteration of the suture lines.

The earliest dicyelic Crinoids had five infrabasals, and the first mono-
cyclic ones five basals. Before the close of the Lower Silurian, there ap-
peared two monocyclic genera with four basals, both having a special anal
plate interposed between the radials. The quadripartite base reached its
culmination in the Upper Silurian, and disappeared before the close of the
Devonian.

The earliest genera with a tripartite base occur in the Upper Silurian ;
some of them have an anal plate, and others not. When that plate is
represented, the basals are of equal size; when absent, two of the basals
are equal, and the third about half smaller. The two forms continued to
exist side by side to the end of the St. Louis group of the Carboniferous,
when both became extinct.

The bipartite base is restricted to the Carboniferous. It occurs from the
Kinderhook group up to the Coal Measures, but is found only among genera
with a large anal plate.

It is evident from these observations that the number of basals was orad-
ually reduced in Paleozoic times, and that in the Camerata the anal plate
was introduced after the quadripartite base had made its appearance. It will
now be shown that this diminution of number was the result of fusion of two
or more of the five original plates, and that by the introduction of the anal
plate the base underwent further modifications. The manner in which the
modifications in the number of basals and infrabasals were effected, may be
best understood by reference to the diagrams on Table A.

Looking at these diagrams, the transmutation in the Camerata from five

MORPHOLOGICAL PART. 55

TABLE A.

Ichthyocrinide. Fistulata. Fistulata.

20

Rhodocrinide. Thysanocrinide. Apiocrinide (young). Apiocrinidz (adult).
DIAGRAMS ILLUSTRATING THE EVOLUTION OF THE BASALS AND INFRABASALS.

All figures represent the anal side at the top; a= posterior basal; 4 and e=postero-lateral basals; c and d= anterior
basals ; 7, g, 2, 7, = infrahasals.

56 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

basals to a less number, is readily understood among genera in which the
anal plate is wanting. When the base is quadripartite, it is invariably the
two anterior plates of the elementary five which are consolidated (Fig. 2).
In the tripartite base there is a fusion of the posterior with the left postero-
lateral basal, and another between the right posterior and adjoining antero- _
lateral-plate (Fig. 3). The figure shows that a bisection of the two larger
plates will reproduce the original five pieces, interradially disposed.

The case is not so simple in genera with an anal plate, where the form
of the basal disk is changed from pentagonal to hexagonal (Fig. 4), as a
bisection of the larger plates would produce six plates instead of five. This
difficulty, however, is overcome if we consider that the introduction of the
anal plate into the ring of radials necessitated corresponding modifications
among the basals, as otherwise these plates would lose their interradial posi-
tion. It required either the introduction of a basi-anal plate, or an increase
in the size of the original pieces. That the latter occurred among the Came-
rata is clearly shown by the diagrams, and the evidence leaves no doubt at
what part of the base the extra width was inserted.

Taking first the quadripartite base, and comparing Fig. 2 of the diagrams
with Fig. 8 — one pentangular and the other hexangular — we find that in
the latter the posterior basal has doubled in size (Fig. 7), without materi-
ally changing the orientation of the plates, or disturbing their general
arrangement. |

In the tripartite base the change was accomplished in a different way.
There w is added to plate ¢ (Figs. 9 and 10), and the plates ab and ed have
coalesced, and hold relatively the same position as in Fig. 3.

The bipartite base is probably derived from the tripartite (Fig. 4), which
preceded it in time, and x, which in the latter constituted a part of ¢, is
united with ed, and ab with ¢ (Figs. 11 and 12). |

Now, taking up Fig. 7, and eliminating 2, so that the side of plate a rests
against the plate e, we obtain Fig. 2, and by a similar procedure we are
enabled to transform Fig. 9 into Fig. 8. The hexagonal base is thus re-
stored to its primitive pentagonal form without disturbing the orientation
of any plate, compound or simple.

A most beautiful confirmation of these observations is furnished by an
abnormal specimen of Teleiocrinus umbrosus in our collection, in which the
regular anal plate is wanting. edeiocrinus has normally three equal basals,

but in this specimen the basal plate to the left of the anterior ray is reduced

MORPHOLOGICAL PART, 57

to one half its normal size, leaving the basal disk exactly like that of forms
which are normally without the anal plate.

It is very remarkable that while in all Crinoids with an unequally tri-
partite, monocyclic base, the smaller plate is located to the /e/t of the anterior
radial, this plate in the base of the Blastoids lies invariably to the right
(Fig. 6).

Among monocyclic Inadunata, in most of the genera, the changes among
the basals are not so readily traced as in the Camerata, owing to the asym-
metry of the radials, which more or less affected the form of the basals.
Most of them have five basals, but there are some genera with three and
four. Anomalocrinus, so remarkable for its asymmetry, has five basals, but
there is frequently a small additional plate interposed beneath the extremely
large left posterior radial. As this plate 1s only occasionally represented,
it is probably not of much morphological importance. Storthingocrinus and
Symbathocrinus have three unequal basals, arranged like those of the Platy-
crinidw. The Calceocrinide have three or four basals of a decidedly irregu-
lar arrangement. Belemnocrinus is the only known monocyclic genus with
five basals in which the regular anal plate is represented; but the plate is
quite narrow, and affects but slightly the symmetry of the plates of the
proximal ring. In the Hybocrinids, a large radianal is interposed between
the radials, and the basals consist of five plates of a rather irregular form.

That the smaller number of basals is a modification of the original five
plates, is indirectly shown by the fact that in many species of Platycrinus the
plates are so closely anchylosed that no vestige of suture lines can be seen.
In some of them the lines are marked by grooves, while in others even the
sutures are plainly visible. The sutures are always better defined in a
young specimen than in the adult, and in some species can be seen the out-
lines not only of three, but of five plates. It is further significant that in
all Platycrint of the Warsaw and St. Louis groups, the suture lines are ele-
vated, and transformed into ridges by excessive deposit of limestone matter.

The case of Pisocrinus is very interesting. The Silurian species plainly
show five basals, while those from the Devonian of the Hifel, which have
been referred by Schultze to Zriacrinus, very often have but three. A care-
ful examination of a large number of Eifel specimens leaves not the least
doubt that in some of them there are still five plates, while in others of the
same species the number is reduced by anchylosis to three. Among recent

Crinoids also, Carpenter and others have noticed a fusion of the basals in
8

58 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Hyocrinus and Riuzocrinus, and it is possible that the former has really but three
basals; but in Rhizocrinus the fusion was not complete, as Count Pourtalés
proved by inserting a needle in the central canal, whereupon the base sepa-
rated into five pieces.”

The foregoing facts are of considerable importance as to classification.
For if the smaller number of plates is merely a modification of the original
five, the number of basals cannot be regarded as a good character for sepa-
rating the Crinoids into primary groups, as was practically done by Angelin,
and afterwards by 8. A. Miller.

The basals of dicyclic Crinoids, as we have stated, invariably consist of
five pieces, but their form differs in different groups. In the Rhodocrinide
(Fig. 17) they are all heptagonal; while in the Thysanocrinidx the posterior
one is heptagonal, and the four others hexagonal (Fig. 18)— the former
supporting a supplementary plate at each interradius, the latter at the anal
side only. In the Fistulata, all five plates are hexagonal when there is no
anal plate, as in the Encrinide; but in the Cyathocrinidew, whenever that
plate is represented, four of the basals are hexagonal, and the fifth hepta-
gonal, precisely as in the Thysanocrinide. In the Poteriocrinidse, and all
other families in which in addition to the regular anal plate a radianal is
represented, only three of the basals are hexagonal, and the posterior and
right postero-lateral basals are heptagonal (Figs. 15 and 16).

The same variations occur among the basals of the Ichthyocrinide.
Those of Ichthyocrinus agree with the basals of the Encrinide; those of
Mespilocrinus, Taxocrinus, Forbesiocrinus, and Calpiocrinus, with the plates of the
Cyathocrinidee; while the basals of Lecanocrinus, Gnorimocrinus and Sagenocrinus
are in a similar condition to those of the Poteriocrinide.

Three infrabasals have been observed only among the Fistulata and’
Articulata. They are represented sparingly among the former, but are the
rule among the Ichthyocrinide, and are represented in the larva of the
Comatulz. Wherever they occur, they consist of two large plates and a
smaller one, which are differently arranged in the various groups. In the
Fistulata, according to Bather, the position of the small plate is not constant ;
we have always found it located anteriorly below the suture between the
two anterior basals, and the plates f and g and 7 and & fused together
(Fig. 16). In the Ichthyocrinide, however, the small plate rests below the
suture between the posterior and right postero-lateral basal, and f and g and

* Memoirs Mus. Comp. Zodl., Vol. IV., p. 29.

MORPHOLOGICAL PART. 59

i and 7, respectively, are united (Fig 13). As this structure is apparently
constant in the latter group, we regard it as of some importance as regards
classification. |

The introduction of the anal plate did not affect the basals of dicyclic
Crinoids in the same manner as in the monocyclic. While in the latter,
when the plate is represented, the orientation of the basals is slightly dis.
turbed, in the dicyclic forms it remains unaltered. The anal plate of the
latter rests invariably upon the truncated upper face of the posterior basal
(see Figs. 14 to 18); while in monocyclic Crinoids it is supported by the
basals a and e (Figs. 10 and 12), or occasionally by a and « (Fig. 8).

The infrabasals are completely anchylosed in the Cupressocrinidex, Gas-
terocomide, and in Stemmatocrinus, where they form an undivided disk, which
Carpenter and others have regarded as representing the top stem joint, as in
the case of the Apiocrinide and Comatulee. Ayassizocrinus, in its pedun-
culate younger state, had five well defined infrabasals; but after losing its
stem, the suture lines became gradually obliterated by limestone: deposit
upon the surface. The same is the case with the basals of the monocyclic
Hdriocrinus.

Mr. Bather discriminates between Dicyclica, Pseudomonocyelica, and
Monocyclica vera.* To the Pseudomonocyclica he refers those forms in
which infrabasals are obsolete in the adult, but were represented in early life.
They embrace most of the Mesozoic and recent Crinoids, and may be sub-
divided into two classes: (1) forms in which the infrabasals gradually
become anchylosed with the top stem joint, and (2) those in which they
were resorbed in the adult. In the former, which among other groups
include the Aplocrinide and Comatule, the new stem joints are formed below
the centro-dorsal; while in the latter, which are typified by the Pentacri-
nide, the top stem joint is the youngest joint of the stem. We shall
presently show that both these forms, although the infrabasals may have
disappeared, still retain the characteristics of dicyclic Crinoids.

Several years ago we discovered ¢ that among the Paleocrinoidea there
is a regular alternation in the arrangement of the successive parts below the
radials, and that the orientation of the stem is essentially different among
monocyclic and dicyclic forms. We found that the salient angles of the stem
itself, and the projections of the axial canal, are reversed in the two groups,

* Ann. and Mag. of Nat. Hist. (sixth series), Vol. V., April, 1890, p. 316.

+ Revision, Part III, Section I, p. 7 (Proceed. Phila. Acad., 1885, p. 229), with a most unfortunate
transposition of terms, which was corrected in the appendix. Also 1888, Proceed. Phila. Acad. p. 351.

60 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

and that the cirri, which in dicyclic Crinoids are radial, are interradial in the
others. By employing this rule we were enabled, in many cases where the
infrabasals are hidden beneath the column, to determine their presence. The
law of alternate arrangement of the successive parts is shown by the follow-

ing table : —

Basals.

' Infrabasals.

Column.

Column.

Exterior angles of.

Sections of.
Sutures.

Sides.

Cirri, when present.

Axial canal.

Dicyclic.

Interradial.

Radial.

Interradial.

Interradial.

Radial.
Radial.
Radial.
Radial.

Monocyclic.

Interradial.

Radial.
Radial.
Interradial.
Interradial.
Interradial.

Interradial.

This law is only applicable, to its full extent, in species with pentangular
or pentapartite stem and canal; but we infer, from analogy of these forms,
that the circular stem, wherever it occurs in dicyclic Crinoids, is also practi-
cally interradial, and in those of monocyclic type radial. Our observations
were founded upon Paleozoic Crinoids, among which we had met with no
exception; but on applying them to Mesozoic and later Crinoids, we were
surprised to find that in most of the so-called monocyclic forms the relative
positions of the column and cirri were reversed, so that they were exactly as
in dicyclic Paleocrinoids. Though universally considered to be monocyclic
Crinoids, they were built on a dicyclic plan; and this led us to inquire
whether all those forms might not be dicyclic, whose infrabasals were hidden,
or had existed in their larval state.

This seemed to be confirmed by another observation which we made
among certain Paleozoic forms. In some genera, notably in Graphiocrinus,
which was originally described as monocyclic, the infrabasals are so extremely
small that they are completely covered by the upper stem joint, and only the
basals are visible. These Crinoids are practically in the same condition as
Millericrinus, Apiocrinus, and Pentacrinus, for the stem occupies the same posi-

MORPHOLOGICAL PART. 6]

tion toward the proximal ring of plates visible in the calyx as that of Milleri-
crinus and Apiocrinus, except that in the two latter the space above the top
stem joint 1s vacant, while in Graphiocrinus it is filled by very small infrabasals
(compare Fig. 17 with Fig. 20 on Table A).

Small infrabasals are known to exist in the base of the Pentacrinoid genus
Extracrinus, and de Loriol has discovered similar plates in two species of
Millericrinus (Plate VI. Figs. 1 a, 6, and 2a,6). Those of M. polydactylus he
describes as follows:* “Je distingue trés nettement, sur deux individus,
cinq pigces extrémement petites, A peine distinctes & Tceil nu, qui sont
logées au centre de l’article basal, chacune reposant sur le sommet de l’une
des carénes, dans une direction radiale, au centre se trouve, une petite
dépression qui forme le fond de la cavité. Ces petites piéces, que je
n’avais jamais encore observées, jouent évidemment le role de piéces infra-
basales, mais 4 l’état tout a fait rudimentaire.” Similar pieces were dis-
covered by him in his M. Orbignyi, of which he says: + “Elles ne peuvent
absolument se voir que lorsque, par un hasard heureux, l'article basal peut
se dégager du calice. Il me parait indubitable que se sont la de petites
pieces infrabasales rudimentaires semblables a celles que j’ai signalées dans
le MW. polydactylus.” aes

Admitting these plates to be infrabasals, it is certainly quite improbable
that other species of AMlericrinus having a pentangular stem, and those with
‘a round stem, and the species of Apiocrinus, —a genus which, according to de
Loriol, is very closely allied to MiWlerierinus and Guettardicrinus — should have -
possessed no infrabasals. In all species of JAericrinus, the column, unless
it is round, has interradial angles (Plate VI. Figs. 1%, 3, 4°, 5), exactly as in
M. Orligiayi and all dicyclic Paleeocrinoids; and hence, if the genus were not
dicyclic, this structure would be at variance with that of other Crinoids. We
come to the same result if we examine the vacant space within the basal
ring. This is radial, and disproportionate in size to the axial canal of the
stem, which is small and circular ; whereas if it represented the axial canal
of a monocyclic Crinoid it should be interradial. The space is large enough
to have contained, besides the canal, additional plates, which, if present,
would have occupied the same position as the infrabasals of I. Orbignyi.

The column of dicyclic Crinoids abuts either entirely against the infra-
basals, or partly also against the basals. The latter is the case with the top

* Paléont. Frang., le série, Animaux Invertébrés, Terr. Jurassic, Tome XI. Premitre Partie, Crinoides,
Paris, 1882-1884, p. 553, Plate 110. Figs. 1 and 2.
+ Ibid., p. 566 (Plate 116, Fig. 1, 4, ¢, d).

62 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

stem joint of Millericrinus Orbignyt and M. polydactylus ; while in other species
of the Apiocrinide in which infrabasals are unrepresented, the column
touches the basals only. It rests against the owfer (dorsal) surface of the
plates, whose /ower margins are bent up, so as to form an inverted pentan-
gular concavity, radially disposed. This cavity, which is occupied and
completely filled by the top stem joint, is generally grooved at the inter-
basal sutures, and produces upon the upper face of the joint five angles,
which fit into the grooves, and interlock with the basals (Plate VI. Figs. la,
14, and 5). The outer edge of the joint at the upper end has also a more or
less radial outline ; while its lower end follows the orientation of the stem,
and is interradially disposed when that is pentangular. !

We mention these particulars, because Carpenter, in criticising our gen-
eralization,* undertook to prove by the an gularities at the upper face of the
stem that in those species of the Apiocrinide in which the stem is round,
the latter was radially disposed, and not interradially; and that those
species, according to our own rules, were monocyclic and not dicyclic. He
overlooked the fact that the top joint rests against the turned up dorsal’
(outer) surface of the basals, and not against their znferior faces. The surface
to which the “centro-dorsal” is attached, represents morphologically the
surface of the concavity for the reception of the column in Paleozoic Cri-
noids; the inferior faces are those which meet the infrabasals, and in M. Or-
agnyy and M. polydactylus actually support them, but in most of the Apio-
crinidee they enclose a vacant space. If this space was filled by infrabasals,
as we think it was in the young Crinoid, the columnar concavity and the
upper face of the stem would be in exactly the same condition as in the
Ichthyocrinidz, in which similar angularities occur on the upper face of the
stem (Plate Hl. Fig. 4b). The upper face of the column in all Crinoids
adapts its form to the shape of the plates to which it is attached, and if their
suture lines are grooved, it will be correspondingly ridged. We thus believe
that Carpenter misunderstood the structure, and that he overlooked our
statement that it is the longitudinal angles along the column which alternate
with the proximal ring of plates in the calyx, and not the angularities or
ridges of the upper face.

In Rizocrinus the condition of the base is apparently similar to that of
the Apiocrinide. The genus, however, was described by Carpenter as

* Ann. and Mag. Nat. Hist., March, 1886, p. 286.
t Chall. Rep. Stalk. Crin., p. 246.

MORPHOLOGICAL PART. 63

monocyclic, and the uppermost stem joint as the last formed plate of the
stem. But he seems to have changed his opinion afterwards, for in a letter
to us, dated November 28, 1890, he writes as follows: “I have spent this
morning studying my material of Riizocrinus, including some fresh specimens
which I found among my father’s collection, and I conclude that you are
right in considering the top-stem-joint as a centro-dorsal like that of Bour-
gueticrmus and the Apiocrinide. It is, however, always the smallest, 7. e.,
thinnest joint of the stem. But it is distinctly marked into five fossee for the
basals by radial ridges, and this is sometimes very apparent in the younger
individuals. See Chall. Rep. Plate X. Figs.'7 and 8. It is more marked in
fe. Rawsoni than in R. lofotensis. The pentagonal space in the centre, Plate’
X. Fig. 5, is nothing but the axial canal.” He then continues; “ Bathycrinus
is a very different form, with its very numerous thin joints at the top of the
stem (see Plates VI. and VIII), and I have been thinking for some time
past that it must be removed from the Bourgueticrinide and made the type
of a new family. The ten arms, and the trifascial articulation are also good
characters, as the latter replaces the syzygies of Riizocrinus.”

Except in one point, we fully agree with this. Examining Plate X of
the Challenger Report, we find in Rhizocrinus the space within the basal ring
very different from the axial canal in the stem joints (see our Plate VI. Figs.
Ta, b), the former being fully twice as large, and pentangular, while the canal
is oval. The space between the basals is radially disposed, as in the A piocri-
nid, and we believe that Rhizocrinus is also pseudomonocyclic. Its structure
is altogether different from that of Bathycrinus and Hyocrimus, which in our
opinion are true monocyclic forms. They have no centro-dorsal, and the
uppermost joint is the last formed plate of the stem. The open space within
the basal ring is interradially disposed, and has the form and size of the
stem canal. |

Our observations on the Apiocrinide led us in 1885* to the conclusion
that most of the Neocrinoidea may have possessed rudimentary infrabasals in
their larval state. This rather startling statement was unfavorably received
by Carpenter, and severely criticised by him.t He held at that time that
with the exception of Hnecrinus, Extracrinus, Marsupites and Uintacrinus, all Meso-
zoic and recent Crinoids were monocyclic. His objections, however, did not
seem to us convincing, and in Section II. Part III. of the Revision, pp. 294-

* Revision, Part III., Section I., WWOaf ala
t Bibliogr, Notices. Ann. and Mag., November, 1886, p. 408.

64 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

299, we asserted that not only the majority of Stalked Crinoids, but also-the
_Comatulse, were built upon the dicyclic plan, and probably had inirabasals
in their larval state.

The centro-dorsal at the Pentacrinoid stage of the Comatule, as may be
seen by examining Plate VI. Figs. 18 and 19, agrees closely with that of the
Apiocrinide. It is interradially disposed at the proximal face, and also at
the distal face, so that its angles correspond with the angles of the basals, as
in those dicyclic Crinoids whose infrabasals are hidden by the column; and
even in its free floating stage the centro-dorsal retains its interradial
position.

So strongly were we impressed with the conviction that the Comatulee
are dicyclic Crinoids, — although no traces of infrabasals had ever been
found by Wyville Thomson, the two Carpenters, Goette, and others who had
extensively studied the embryology of Antedon, — that we urged European
investigators to make fresh search for these plates.

It was therefore with no little satisfaction that we learned from Dr.
Carpenter in July, 1887, that infrabasals, whose existence we had predicated
upon paleontological evidence, had actually been found by Mr. H. Bury.
This important discovery was announced at the Manchester meeting of the
British Association, and communicated by Mr. Bury in a paper on “ The
early stages in the Development of Antedon rosacea,’* ‘The plates appear in
the ciliated larva, and consist of three unequal pieces, which in the Penta-
crinoid stage are fused together with the top-stem-joint (centro-dorsal), so as
to form together with the latter one large plate, with five angles, radial in
position. One of the plates is smaller, and has but one salient angle, the two
larger ones having two, —a structure which suggests that the two latter may
represent a pair of anchylosed plates. Three similar plates, but with a some-
what different orientation, persist throughout life in the Ichthyocrinide, but
the smaller plate of Anfedon rosacea, if we understand Mr. Bury, is placed
anteriorly ; while that of the Ichthyocrinide is directed posteriorly (Table
A, Figs. 14 and 16).t

It is of considerable importance that the infrabasals of all Carboniferous
Ichthyocrinidsz are coalesced with the top-stem-joint (centro-dorsal) similar
to those of Antedon. In specimens in which the column has been detached
from the crown, the small infrabasals generally adhere to the top-stem-joint

* Philosophical Transactions of the Royal Society of London, 1888, pp. 257-800.
+ The orientation of this plate was incorrectly given by us in the Revision, Part III. Plate 6, Fig. 3.
_ Since then we have found out that it is located in all Ichthyocrinide to the right of the posterior basal.

MORPHOLOGICAL PART. 65

(Plate II. Fig. 4 4), being in some cases perfectly fused with that plate (Plate
VI. Fig. 11). The condition is the same as in the two species of Millericrinus
in which infrabasals have been recognized, and we conclude from analogy
that a fusion of those plates eventually took place in all groups in which the
new stem joints are not formed directly beneath the calyx.

The case is different among the Pentacrinidx, in which the new stem
Joints constitute the upper part of the stem. Of the principal genera which
have been referred to this family, one — L2tracrinus — has small infrabasals
persistent through life; while in the other two — Pentacrinus and Metacrinus
—no trace of them can be found in the adult. The dicyclic nature of
Pentacrinus and Metacrinus is indicated by the orientation of the stem and
cirri, the angles of the stem in both of them being interradially disposed,
and the cirri radially. But what became of their infrabasals? That they
fused with the upper stem joint, like those of the Ichthyocrinide, need not
be considered in this family, as that would necessarily prevent the formation
of new joints at the top. They may have been resorbed in the erowing
animal; but it appears to us more probable, from paleontological evidence,
that the plates gradually diminished in size, and finally disappeared alto-
gether in the group. The structure of the Pentacrinidx is very different
from that of the Comatule and Apiocrinids, and it appears to us that Cri-
noids in which the upper joint of the stem is the youngest, cannot be derived
from those in which the top of the stem is fused with the infrabasals, and the
two groups should be widely separated. The Apiocrinide ‘and Comatule
which have a centro-dorsal,—7. e., in which the infrabasals are fused with
the upper stem joint,—should be placed together with, or close to, the
Ichthyocrinidx ; while the Pentacrinide, which in many points agree with
the structure of the Poteriocrinids and Encrinidex, we think might be safely
referred to the Inadunata Fistulata.

It is very singular that while in £2tracrinus and Metacrinus the projections
of the open space within the basal ring, and the axial canal of the stem, are
radially disposed (Plate VI. Fig. 9), both are decidedly interradial in Penta-
crinus (Plate VI. Fig. 8). This anomaly, if we may so call it, was regarded by
Carpenter * as a proof that our generalization upon the stem is not applicable
to the Neocrinoids. This, indeed, seemed at first to be indicated also by the
orientation of the stem; but Bury’s discovery of infrabasals in the Comatula
larva changed the whole aspect of the case. The discovery of these plates,

* Bibliogr. Notices, Ann. and Mag. Nat. Hist., March, 1886, p. 287.
9

66 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

whose presence we had inferred from the orientation of the larval stem and
centro-dorsal, showed that our observation must be one of wide signifi-
cance. ‘The aberrant structure of the canal in Pentacrinus does not invalidate
the law as we have found it, but simply points to the existence in some
groups of transition forms intermediate between Monocyclica and Dicyclica.
Such transition forms must have occurred at some time in the developmental
history of the two groups, if one was evolved from the other. Which form
is the older has not been satisfactorily proved, but the evidence of Palxontol-
ogy points to the Dicyclica as the ancestral type. In the Camerata the evo-
Jution was apparently complete at and before the Silurian, but it is probably
still going on in some of the later groups. In the Pentacrinidex, the diminu-
tive size of the infrabasals in Evtracrinus may be the first step toward the
monocyclic base, their non-representation in Metacrinus and Pentacrinus the
next, and the change in the orientation of the axial canal another important
step in that direction.

We have discovered a case almost parallel to that of the Pentacrinids in
the Lower Silurian monocyclic genus Glyptocrinus, which has a radial stem *
‘ and an interradial canal, except in G. Fornshelli, in which canal and stem
both are radial (Plate XXI. Fig. 5).

Glyptocrinus belongs to a series of monocyclic and dicyclic Crinoids, which
are so closely intermingled and intimately related that it is extremely difficult
to separate them generically, and one is inclined to place in the same family
monocyclic and dicyclic forms, There is perhaps no other group so likely to
throw light upon the derivation of the Monocyclica. The base of Glyptocrinus
has been variously described as consisting of one or two rings of plates. Hall
originally defined the genus as having basals only, but a few years later
thought he had discovered within the basal ring in some of the species indi-
cations of five additional pieces, which were also observed by Meek, and
called by him “sub-basals” (Plate VI. Fig. 12). S. A. Miller described the
base as consisting of but one ring of plates, but he included in the genus
several species with two rings. We described the genus as dicyclic in Part
II. of the Revision, but in Part III. placed it among the Melocrinids, after
throwing out those species in which rudimentary infrabasals could be satis-
factorily traced.

* The nucleus of the stem in @. decadactylus and G. Dyeri is obscurely pentangular at the upper end ;
the projecting edges of the joints, however, give it a circular outline. The axial canal in both species is
sharply stellate.

MORPHOLOGICAL PART. 67

The case of Gilyptocrinus Fornshelli is very remarkable. The orientation
of the stem points to a monocyclic base, that of the axial canal to a dicyclic.
Besides, the species is closely related to others in which the canal is inter-
radial, and the stem radial. It is quite evident that the rule which governs
the relations of the parts below the base does not hold good in G. Fornshelli,
as we find it in the fossil state; but we think this proves nothing more than
that in this species the monocyclic stage was as yet incompletely developed.
It should be stated that while the aberrant canal of G. Fornshell! is radial
throughout the whole length of the stem, that of Pentacrinus is interradial
only at the upper portions; it soon turns to circular, and where the cirrus
vessels enter, it is as radially disposed as that of Metacrinus.

Among the Reteocrinid, also, a strictly Silurian family, we find a variety
of transition forms. In Reteoerinus the species from the Trenton group have
large infrabasals, those from the Hudson River group quite rudimentary
ones; while in Xenocrinus and Tanaocrinus the infrabasals are altogether un-
represented. The axial canal of Reteocrinus is radially disposed, that of
Xenocrimus and Tunaocrinus interradially. The three forms are very closely
related, and if we were to separate them upon the structure of the base, it
would be to the exclusion of other characters of manifest importance.

The examples given indicate that there is a most intimate relation
between dicyclic and monocyclic forms, and that probably the latter were
derived from the Dicyclica by a gradual decrease in size and final oblitera-
tion of the infrabasals in geological time.

Bather believes with us that dicyclic Crinoids preceded the monocyclic,
but he states that so far as the Fistulata are concerned he has found no geo-
logical evidence to prove it, at least not among the Fistulata. He alludes to
the Hybocrinid as being probably monocyclic, but he regards the Hetero-
crinidee and Anomalocrinids as true Monocyclica. As to Hybocrinus, he quotes
the earlier part of the Revision, in which we stated that rudimentary infra-
basals might possibly be present in the genus. This supposition is not veri-
fied by further study of the specimens, which show satisfactorily that no
such plates are represented. Hybocrinus is a true monocyclic genus, as much
so as Heterocrinus and Anomalocrinus. This, however, does not exclude the idea
that all three forms may have been derived from the Dicyclica, and there
are good reasons to believe that it was so. The dicyclic pseudo-cystid genus
Porocrinus is so intimately related with Aybocrinus that it is doubtful if the
two should not be placed in the same family. Close relations also exist

68 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

between Merocrinus and Locrinus, and between Oftawacrinus and Heterocrinus, —
dicyclic and monocyclic forms respectively.

While the evidence thus points to the probability that the one group was
derived from the other, it is difficult to explain the change in the orientation
of the stem. That the whole crown passed through a revolution of 36° is
highly improbable. The change probably took place in the body of the
stem, modifying its form to suit the condition of the base. The stem is
round in most of the earlier Crinoids; but we find occasionally within the
same family quadrangular stems from a quadripartite base, together with
pentangular stems from a quinquepartite base, which goes to prove that the
stem, to some extent at least, adapted its form to the conditions of the base.
In a similar manner interradial stems may have changed into round stems,
and these into radial stems. This, however, does not explain the change
in the orientation of the canal, and that of the cirri. The latter are
directed to the angles of the axial canal, through which they communi-
cate with the chambered organ. i

The only writer, besides Bather, who has discussed the derivation of the

two groups is Dr. J. Walther,* who takes it for granted that the simpler —
monocyclic —form is the ancestral one. His arguments were suggested from
his study of the pentacrinoid larva of Antedon, and are extremely hypo-
thetical. They are based upon his peculiar interpretation of the basals and

infrabasals, which, as he now will himself admit, cannot be upheld since Bury:

discovered infrabasals in the larva of Anfedon.

C. The Radiais.

The term “ radials”’ is applied by us only to the first plate of each ray.

All succeeding plates in a radial direction, whether free or incorporated into:

the calyx, are brachials. The name was given by Miiller to all plates up
to, and including the first axillary, and all pieces beyond were regarded by
him as armplates. The same view was taken by Roemer, de Koninck, and
other European authors. The American Paleontologists applied the term

not only to the plates of the first order, but to all plates of the rays that take

part in the calyx. They distinguished those of different orders as primary,
secondary, and tertiary radials, according to rank.

* “Untersuchungen tiber den Bau der Crinoideen.” Paleontographia, 1866, Bd. XXXIL., pp. 180-
199:

Peg ae

~s

MORPHOLOGICAL PART. 69

Miiller’s interpretation of these plates was somewhat modified by
Schultze,* who assumed that the arms begin invariably with the first well-
defined articular facet. He held that in Actinocrinus and Rhodvcrinus, which
have no articulation above the (first) radials, the arms commence above the
first axillary; but that in Crinoids in which the rays are free above the first
plate, the arms begin with the second plate of the ray.

Zittel,t who accepted Schultze’s views and applied them to the later
Crinoids, describes Hnerinus, Pentacrinus, and Millericrinus with one radial
followed by two brachials; Apiocrinus, however, with three radials. He evi-
dently supposed that in the latter the first articulation occurred on the axil-
lary, which is not the case, as shown by Carpenter, + who found in several
species of that genus at the upper face of the (first) radial a transverse ridge
with muscular fossee above it. A similar structure, he believes, exists in all
Aplocrinide, perhaps with the exception of Gluettardicrinus, which, according
to de Loriol,§ has no articular facets on either of the three “radials,” nor |
even on the distal faces of the axillary, so that it cannot be determined in
this genus what plate of the ray bears the first facet. This shows that
Schultze’s rule does not readily apply in this group. Still more serious diffi-
culties arise among the Paleocrinoidea. In most of the Camerata, all plates
of the calyx up to the top of the distichals, and often much higher, are
closely and immovably united, and the lowest articulation or mobility occurs
at the base of the arms. |

Applying Schultze’s definition to the Camerata, it is quite evident that all
the plates of the dorsal cup in a radial direction had to be called radials,
and not merely those up to the first axillary. This we did in our earlier
writings; and instead of making the lower facet the division between
radials and brachials, we took the calyx for the boundary line, and referred
to the radials all plates of the rays which take part in the calyx, and to
the brachials the plates of the free arms. We thus recognized among the
Camerata an indefinite number of radials, while their number was reduced
in the Inadunata to a single ring of plates, a course which was afterwards
adopted by 8S. A. Miller, S. H. Williams, and Prof. Worthen, against Hall,
Meek, and others, who included in this group the first order of brachials.

The Ichthyocrinide, in which the lower branches of the rays take part

* “ Monographie der Echinodermen des Eifler Kalkes,” 1866, Wien, pp. 5 und 9.
+ Handbuch der Paleontologie, Vol. I., p. 339.

¢ Ann. and Mag. Nat. Hist., Ser. 6, Vol. VI., p. 12.

§ “ Paléontologie Frangaise,Jurassique,” Tome XI., Pt. I., p. 215.

70 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

in the calyx, were treated by us in the same way as the Camerata. Schultze,
however, described Yazocrinus as having but one radial, in which he was
correct from his standpoint, for the succeeding plates seem to be united
among themselves, and with the radials by loose suture or a sort of rudimen-
tary articulation. Carpenter described Pentucrinus and the Comatule, which
are in a similar condition to the Ichthyocrinide, as having three radials in
all cases, whether the plates are enclosed by perisome or not, and he distin-
guished the rami as primary, secondary, and tertiary arms. According to
him, Rhzoerinus Rawson, with ten arms, has three radials; while R. lofotensts,
like Cupressocrinus, Pisocrinus, and all Crinoids with but five arms, have one
radial, followed by brachials. He thus made the second plate of the ray a
second radial in the former, and a first brachial in the latter, giving to parts
which are undoubtedly homologous different appellations, while distinct parts
were thrown together. The methods of treating these plates heretofore
adopted were not only empirical, but inconsistent with the principles of
morphology; and the want of uniformity among the different writers,
respecting the terms, must have been perplexing to the student when con-
sulting their works.

In 1881,* and again in 1885,+ we expressed the opinion that the arms
fundamentally begin with the second plate of the ray, and that all Crinoids
have but one ring of radials. In support of this we stated that only the
lower ring could be homologized with the oculars of other Echinoderms;
that in the simpler form—the Inadunata —the arms were free from the
(first) radials, and that in the remaining groups the lower arm plates were
incorporated gradually in paleontological time. We refrained, however, at
that time from changing the terminology, finding it convenient for purposes
of description to continue the old terms.

Our interpretation of the plates was accepted by Carpenter in 1884,+
- who confirmed it by the developmental history of the plates. The “outer
radials,” he says, “commence as imperfect rings, which soon become filled up
with lengthening fasciculated tissue, just as is the case with the stem joints
and later brachials;”’ but “the jirst radials, like the basals and orals, com-
mence as expanded cribiform films.” He further alluded to the fact that the
so-called primary radials of Metacrinus are pinnule-bearing, —a thing which
we have observed in exceptional cases among the Poteriocrinide also.

* Revision, Part IT., p. 10. ty libide Part: Maia,
{ Challenger Rep. on the Stalked Crinoids, p. 48.

MORPHOLOGICAL PART. yi

Upon commencing the present work, we had an interchange of views
with Dr. Carpenter as to the best plan to be pursued respecting these plates,
especially as to whether it would not be better to change their terms, which
we considered meaningless from a morphological point of view, for others
more appropriate. We proposed to restrict the term “radials” to the first
ring of plates of the rays, and apply to the succeeding ones the terms “ pri-
mary,’ “secondary ” and “tertiary brachials,” according to their rank, in
all cases, whether the plates were free or not. He replied that he appre-
ciated the great advantages of the proposed nomenclature, and was willing
to adopt it in principle; but he thought the terms “ primary,” “secondary,”
and “ tertiary brachials” were too long and cumbrous, and he proposed in-
stead of them the terms “ costals,” “ distichals” and “ palmars,” respectively ;
which we finally agreed to accept. Carpenter announced our agreement
in a paper “On certain Points in the Anatomical Nomenclature of
Kchinoderms.” *

In the earlier Inadunata and Articulata, — not in the Camerata so far as
observed, — the radials are frequently compound, ¢. ¢., constructed of two
segments or parts, which are closely united by a horizontal suture, and in
the organization of the Crinoid count as one plate.t Among the Fistulata,
compound radials are found in the Heterocrinidw, Anomalocrinidee, Hybocri-
nidze and Dendrocrinide. In some of these families they are restricted to
the right posterior ray, in others they occur also in other rays. We know of
no case in which the compound structure extends to all five radials, at least
two of the plates being always simple. Among the Heterocrinide, as a rule,
the right posterior, and the right and left antero-lateral radials, are compound,
— exceptionally the anterior one in place of the left antero-lateral; — while
Anomalocrinus and Ohioerinus have but two, and Locrinus, Merocrinus, Hybocrinus
and LHoplocrinus only one. It is further worthy of note, that when there are
several compound radials, the corresponding parts are of nearly equal size;
while the segments vary considerably among themselves in the different
genera. In LHeterocrinus, Ohiocrinus, Tocrinus, Merocrinus, Hybocrinus and Hybo-
cystis, the lower portion, —the so-called inferradials, — are considerably
larger than the upper or superradials. In Anomalocrinus and Dendrocrinus
the two plates are of nearly equal size; while in Ectenocrinus (Helerocrinus)
simplex the upper ones are three or four times as large as the lower. In

* Ann. and Mag. Nat. Hist., Ser. 6, Vol. VIL, pp. 11-18.

tT We gave a full description of these plates in a paper “On the Perisomie Plates,’ Proceed. Acad. Nat.
Sci. Phila., October, 1890, pp. 378 and 379.

72, THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Anomalocrinus the left posterior radial, which is the largest plate in the calyx,
is sometimes bisected longitudinally, but this is not constant.

The gradual increase in size of the upper segments, and the disappearance
of compound plates in other rays than the pesterior, indicates that in these
Crinoids there is a transition from three compound plates to one, and also
from compound to simple plates; and we think it may be safely assumed
that there was a time in the early history of the Crinoids when the arm-
bearing section was altogether unrepresented. This was apparently the case
in Baerocrinus, in which two of the radial plates are non-arm-bearing, and as
these plates occur in the same rays as the compound plates of Anomalocrinus,
we may infer that Baerocrinus is the ancestral form, lower in its development
than either Anomalocrinus, Hoplocrinus or Loerinus.

The later Fistulata have no true compound radials; and although the
lower segment of the posterior radial is still represented in many of them, that
plate does not bear the same relation to the arm-bearing plate that it did in
the earlier forms, but assumes the functions of an anal plate. As such, it will .
be considered by us in its proper place. )

Among the Larviformia, true compound radials occur in Haplocrinus, which
has three of them: in the right posterior, and the right and left antero-lateral
rays, — the same rays in which they occur in the Heterocrinide. The com-
pound plates of the Ichthyocrinide will be discussed in connection with. the
anal plates.

_ In groups in which the radials are simple, the five plates are approxi-
mately of the same size; but when compound, they often differ considerably
in size and form. This is most apparent in Calceoerinus, Catillocrinus, Haplocri-
nus, and Prsocrinus. Among the Poteriocrinide also, when the inferradial is
represented, the right posterior one is smaller than the others, and of some-
what different form. In some Palaeocrinoidea, the radials are separated by
supplementary plates; while in all later Crinoids, with the exception of the
- recent genus Z’hawmatocrinus, they are in contact all round. In the Rhodoeri-
nide, and curiously enough in Thaumatocrinus, they alternate with large inter-
radial plates, with which they form a ring of ten pieces. In the Thysanocrinids,
Actinocrinids, Batocrinidew, Acrocrinids, Dichocrinide, and in most of the
Vistulata and Ichthyocrinide, a special anal plate is interposed between the
two posterior radials. In the Reteocrinidx, they are separated by numerous
small, ill-defined plates at the four regular sides, with the addition of an anal
plate at the posterior side. In the Melocrinide, Eucalyptocrinide, Platycri-

MORPHOLOGICAL PART. 79

nide, and in a few of the later Fistulata, all five radials are in contact
laterally.

The radials, both among each other and with the basals, are united by
close suture, the apposed faces being generally smooth, but occasionally

wrinkled or striated.

D. The Arms and Pinnules.

Admitting that the arms begin with the first plate above the radials, all
plates of the rays, from the second one up, are brachials. As before stated,
we adopt the terms costals, distichals, and palmars, for the first, second, and
third order of brachials, respectively. When there are further divisions in
the rays, the plates are designated as postpalmars, or, when greater detail is
required, as brachials of the fourth, or fifth, order, and so on. We also dis-
criminate between fixed and free brachials, meaning by “fixed” that the
plates so designated take part in the formation of the calyx, and by “free”
that they do not.*

* This is a slight modification of the plan proposed by Carpenter, who reserved the term “ Sree bra-

chials”’ for the plates of the terminal branches alone. He also differed from us in calling the postpalmars,
when there are more than four bifurcations to the ray, ‘‘ postpalmars of the first, second, or third order.”

Aes ae

EXPLANATION OF TABLE B.
‘THE PLATES OF THE RAYS IN DIFFERENT GENERA.

Part of ray of Marsupiocrinus ; costals, distichals, first and second palmars — of the latter only those of
the two outer sides of the rays — abutting against the radials.

Scaphiocrinus. Arms uniserial; pinnulated ; dichotomizing; the joints cuneate.

Belemnocrinus typus. Arms uniserial, giving off armlets at intervals.

A ray of Periechocrinus Whitfeldi. Arms biserial, branching in the free state.

Proximal part of a ray of Steganocrinus sculptus. Arms biserial, given off alternately from opposite sides
of tubular appendages.

Proximal part of a ray of Crofalocrinus pulcher ; the lower brachials arranged as in Fig. 1.

Part of ray of Onychocrinus ramulosus. Arms uniserial; the main branches giving off branchlets in
clusters. |

Left section of a ray of Strotocrinus regalis. The arms given off from the proximal plate at alternate
sides within the calyx.

Symbathocrinus Wachsmutht. Arms uniserial, composed exclusively of costals; the joints arranged
parallel.

The following symbols are used in the figures: R, = radials; I = primary brachials or costals; I] =

secondary brachials or distichals ; I1I = tertiary brachials or palmars ; IV = fourth order of brachials ; V =

fifth order of brachials; and so on; p. == pinnules; a. = armlets.

79

MORPHOLOGICAL PART.

TABLE B.

OE, ny

ae \) cm aE AN NE -
Ree a s*
ys ein :

Lee Ss
- S _ ey eS OR 4 ‘
aN Paige Aly =. : > ceneece Hy]
A ee 2 seed eA Ty |
NENG SEE uae “td ie Pr EI
Wer Sesest Denys & Sao it im ae .
t S Saate Las —— Ne 6) 2 , AS CEE SOR SOP eS NY
as = = Cl ap ; > pe ~ LT = C47? fe i] wIY a ;
an = Nate Sen SF STERN ND 5) TTL | el fe :
. COO E mene, ONS g ee eA si Cords

as Foss
a Ge

UT]

5 em
Coe »

pura

Se ae me

76 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

The. above terms which were accepted by Mr. Bather in 1890,* and used
in his earlier papers “On the British Fossil Crinoids, were in January, 1892 +
abandoned by him and substituted by others. He stated that he found
certain difficulties in their application to Paleozoic forms, and proposed in

place of them the following terms : —

Primibrachs = our primary brachials, or Costals.
First primibrach = first costal,
Second primibrach — “ second costal.
Primaxil =. “axillary costal:
Secundibrachs = secondary brachials, or Distichals.
Secundaxil = “axillary distichal.
Tertiobrachs = “ tertiary brachials, or Palmars.
Quartibrachs = “ brachials of the fourth order
Quintibrachs = “ brachials of the fifth order Postpalmars.
Sextibrachs = “ brachials of the sixth order

Ete. Ete.

This nomenclature is based upon the same principle as our own, and
even the names are not so very different considering that the terms “cos-

»)

tals,” “ distichals,” and “ palmars” are proposed as equivalents of “ primary,
secondary, and tertiary brachials ;” but Bather proposed these terms for the
pinnuleless forms only, and brought out another terminology to be applied to

pinnule-bearing arms, viz.: —

Monostichals (First Order). Tetrastichals (Third Order).
First monostichal. Tetraxil (Third Mainaxil).
Second monostichal. Octastichals (Fourth Order).
Monaxil (First Mainaxil). (Fifth Order).

Distichals (Second Order). (Sixth Order).

Distaxil (Second Mainaxil).

That the branching of pinnuliferous arms, as supposed by Bather, is
almost quite regular, is by no means the case. We frequently find among
Camerate Crinoids rays with three, five, six, seven, nine, and ten arms,
instead of two, four, or eight. In S¢rotocrinus, there are rays with thirty
arms in the calyx, and the “Finials,” which here comprise the plates
of the free arms, although given off from the fourteenth axillary, are
“Triacontastichals.” Still more complicated is the case in Steganocrinus,
Lucladocrinus, Ripidocrinus, and Melocrinus, in which, to the full length of their
rays, from the costals or distichals up, the brachials are developed into rigid

* Ann. and Mag. Vol. V. p. 318. Tt Ibid., Vol. IX. pp. 54-61,

MORPHOLOGICAL PART. T7

calycine tubes, and the original pinnules into alternately arranged pinnule-
bearing arms. This shows that the second part of Bather’s terminology
cannot be carried out practically, and we see no good reason why the former
terms could not be used for all Crinoids, pinnulate or non-pinnulate.

The costals of the Camerata, as a rule, consist of two plates to the ray ;
exceptionally of one or three. Platycrinus has generally but one; but two
of its earlier species have two, and it is quite probable that the genus origi-
nally had two costals, which later on were united into one. This seems to
be confirmed by the fact that some of the species have transverse grooves at
the dorsal face of the plates, and that in multibrachiate species, the distichals
and succeeding orders are composed of two pieces. Sereocrinus also has but
one costal, which has the proportions of the combined first and second plates
of Dolatocrimus, with which it has very close affinities. The same structure is
found in Anthemocrinus and Hadrocrinus. Dichocrinus has two costals, which
form a syzygy, the epizygal supporting an arm. The allied Tularocrinus and
Pterotocrinus, however, have but one. In Batocrinus, and in most of the Bato-
crinites, the first costal is very short, and is frequently anchylosed with the
second in one or more of the rays. Three costals occur among Camerate
Crinoids only in Reteocrinus stellaris, and in Hall’s imperfectly known
Schizocrinus.

Among the Articulata the number of costals is more variable, and often
differs among the rays of the same individual. Sorbesvocrinus Agassizi* may
have two or three costals in all its rays, or four only in one or two of them.
Calpocrinus and Mespilocrinus have two, Ichthyocrinus and Taxocrinus two to
three, and Amsocrinus but one; while Onychocrinus has from three to six.

The number of costals is still more variable in certain groups of the
Fistulata, in some of which such irregularity is the rule. This is the case in
Cyathocrinus and Partsocrinus, in which one ray may have two, the adjoiing
one three, and the next perhaps five or six. Codiacrinus has two to three,

Atelestocrinus from two to six. Less variable among the rays, but still numer-

* We are of the opinion that Forbestocrinus nobilis, de Koninck’s type of the genus, is generically iden-
tical with Onychocrinus Lyon. We recently obtained from Tournai, Belgium, a fine specimen with arms,
which clearly shows that it has a small anal tube resting upon the first anal plate. The rays are free above
the first costal, and are extremely heavy to the fourth distichal, whence they branch off into numerous small,
curving armlets, exactly as in Onychocrinus exsculptus Lyon. De Koninck stated that in his species the
plates of the anal side, which were imperfectly shown in the specimens, were probably more numerous than
those of the other sides, whereas the fact is the opposite; and this statement, no doubt, led Hall and others
to refer Forbesiocrinus Agassizi and allied forms, in which that actually is the case, to de Koninck’s genus.
If, therefore, de Koninck’s type is that of Onychocrinus, the latter name may have to be abandoned, and
a new generic name proposed for such forms as F. Agassizt.

78 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

ous, are the costals of Dendrocrinus and Homocrinus, in which we have counted
as many as seven; focrinus has four, Anomalocrinus from two to four in the
same species. Most of the other Fistulata have one or two. When there is
but one plate, it is generally twice as long as the two, the latter forming »
a syzygy. We find this in the majority of the Poteriocrinide, except in
the anterior ray, which in some species has as many as twelve costals, while
in others it has no bifurcation at all, and the arm is composed of costals only.
A few of their species have from five to eight costals in each ray, and Potert-
ocrimus missouriensis from ten to fourteen. In the Hybocrinide, and in the
Larviformia as a rule, the arms are formed exclusively of costals (Fig. 1);
and only occasionally in Allagecrinus, in one or two of its rays, the radials
are axillary and in the absence of costals support two rows of distichals.

From these facts it is obvious that the number of costals does not consti-
tute a reliable character for classification, as heretofore supposed, and that in
some groups their number is of but little value for specific distinction. This
is even more markedly the case with regard to the higher divisions of the rays.

The distichals are borne upon the axillary costal, which splits the ray
into two divisions, and all succeeding bifurcations take place from one or
both of these divisions. To this rule, however, there are a few exceptions:
Steganocrinus sculptus, a few species of Melocrinus, Hyocrinus and Calamocrinus,
have no regular distichy, and all their branches are given off from one
trunk. A similar structure is found among the Poteriocrinide in the pos-
terior ray. In most of their species with two arms to the ray the posterior
ray has but one trunk, and in multibrachiate forms the first bifurcation of
the posterior ray corresponds with the second in the other rays. Branching
takes place either alternately from opposite sides, or by means of dichotomy.
The former is very frequently the case among the Camerata, and is the rule
in the Actinocrinide.

The arms are composed of one or two rows of plates. The uniserial
arms are composed of either rectangular or cuneate plates, the former being
the most archaic form. The cuneate plates are alternately arranged, and
gradually pass into a biserial arrangement. Arms are called “ biserial”
when the plates interlock, and do not reach to the full width of the arm.
This explains why in biserial arms the pinnules are given off from every
plate at each side of the arm, while in uniserial arms every second plate at
each side bears a pinnule.

That the biserial arms represent the higher form is clearly shown by

MORPHOLOGICAL PART. 79

their mode of growth, and their gradual introduction in geological time.
In the young dicyclic Crinoid, as we had occasion to observe especially well
in the genus Platycrinus (Plate LXXUI. Fig. 10, and Plate LXXV. Fig. 11),
the arms are uniserial throughout, their outlines waving, the plates decidedly
wedge-shaped, the pinnules proportionally large and given off alternately as
in true uniserial arms. In somewhat older specimens, the plates at the tips
gradually interlock, and the new ones still forming at the distal end are
strictly biserial. With advancing maturity the interlocking gradually ex-
tends to the proximal ends, until finally in the adult Platyerinus the whole arm
becomes biserial, except perhaps as to a few plates near the calyx, which
permanently retain their larval condition. Similar modifications occurred
in geological time. In the Lower Silurian the arms of monocyclic Camerata
are uniserial, almost without exception. In the Niagara group and Wen-
lock limestone, however, they rapidly change into biserial. It is very signi-
ficant that among the species of that epoch we find as persistent characters
all the phases through which the arms of the individual Crinoid pass in early
life. This is well shown in the case of the Batocrinide.* The arms of
Habrocrinus and Desmidocrinus are uniserial; but while the plates of the
former are always rectangular, those of the latter in some species are de-

cidedly cuneate. The same modifications can be observed among the arms |
of Patelliocrinus and Stehdiocrinus, but in some of their species the cuneate
plates already begin to turn into biserial by interlocking. We thus find in
the same genus, and almost contemporaneously, all the variations from uni-
serial arms to biserial; and, what is most significant, the arms of all Devo-
nian and later Batocrinide are strictly biserial. Turning to the Platycrinide,
we find that the Upper Silurian Cordylocrinus has uniserial arms, formed of
rectangular or cuneate joints, while in Marsupiocrinus, Culicocrinus, and Platy-
erinus they are biserial. We may note also the case of the Hexacrinide, in
which the development of the arms took place at a later period. The arms
of the Devonian genus Hexacrinus are uniserial, and also those of the earlier
species of Dichocrinus. ‘The plates of the latter are rectangular in all Kinder-
hook species, and also in about half of those from the Burlington and Keokuk
groups; in most of the others they are wedge-shaped, and in a few of them
the arms fairly enter the interlocking stage. All species, however, of the
Kaskaskia group have biserial arms, and likewise the contemporaneous
Talarocrinus and Pterotocrmus. Among the Melocrinide, Glyptocrinus and

* We have separated the Batocrinide from the Actinocrinide, referring to them only those genera in
which the anal plate is followed by three interbrachial pieces, instead of two as in the latter family.

80 TITE CRINOIDEA CAMERATA OF NORTH AMERICA.

Compsocrinus, — both from the Lower Silurian, — have uniserial arms; Peri-
gyptocrinus, and probably all later Melocrinide, biserial. Among dicyclic
Camerata, we find well defined biserial arms already in the Trenton and
Hudson River groups, along with uniserial, the former being perhaps in the
majority ; but the latter are continued to the lower part of the Devonian by
two species,” and these, together with the species of Dichocrinus, are, so far
as we know, the only representatives of the Camerata with a single row of
arm plates that survived the close of the Silurian.

In the Fistulata, the biserial arm structure was introduced just before the
close of the Carboniferous, but only in a limited way. True biserial arms
only occur in Graphiocrinus,- Hupachycrinus, Cromyocrinus, Hydreionocrinus,
Erisocrinus, Stemmatocrinus, and Enermus, but the majority of species have
either quadrangular or cuneate arm plates, and in some of them only the
tips of the arms begin to interlock. In this group the biserial stage at no
time became a constant character, not even in the Triassic. Enerinus lihi-
forms has perfectly biserial arms, while the arms of Hnerinus gracilis are
uniserlal, and composed of quadrangular plates.

The arms of the Articulata, not only in Paleozoic pinnuleless forms,
but also in the Neozoic pinnule-bearing ones, are uniserial without exception.

The pinnules, as happily expressed by Carpenter, are repetitions of the
arms on a small scale; and in their organization morphologically, and to
a large extent physiologically, closely resemble ordinary arm _ branches.
They are short branchlets given off along the sides of the arms, but rarely
reaching their tips, and are usually more slender, and composed of longer
joints. The pinnules differ from arms in containing the fertile portions of
the genital glands, while the arms lodge the genital cords. Like the arms,
they have ambulacral furrows fringed with cilia, by means of which particles
of food coming in contact with them are carried along the grooves to the

* Oehlert’s new genus Diamenocrinus, and ‘“‘ Rhodocrinus” gonatodes Miller (both from the lower
Devonian), which perhaps belong to one genus, have dichotomizing arms, composed of short, quadrangular
te It is doubtful if the name Graphiocrinus can be retained, according to the general rules adopted by
naturalists, as it was incorrectly defined by de Koninck and Le Hon. The type has small infrabasals hidden
by the column, and the position of the anal plate is materially different from that given by the Belgian
writers, which probably was not known to Trautschold when he proposed the genus Phialocrinus. The anal
plate of Graphiocrinus encrinoides, de Koninck’s type, rests directly upon the truncated posterior basal, as
we observed in a fine specimen in our collection, exactly as in Phialocrinus. There is, however, a slight ob-
jection to Trautschold’s name, which was preoccupied by Hichwald (Lethea Rossica I, p. 578), but the
genus was founded merely upon fragments of column. That Phcalocrinus patens has two costals, and Graphio-

erinus encrinoides but one, may not be of generic importance, as the two plates of the former are equal to the
one of the latter, which evidently form a syzygy.

MORPHOLOGICAL PART. 81

mouth. In their normal condition the pinnules are arranged alternately on
opposite sides from every second joint, so that each joint bears a pinnule.
When the interval between the pinnules is greater, which is frequently the
case at certain parts of the arms, especially among recent Crinoids, this has
been called a syzygy. The term was applied by Johannes Miiller* to
the immovable union of two arm joints, of which only the upper one is
pinnule-bearing. The two plates, to which the names “hypozygal” and
“epizygal”’ were given, — the later for the pinnule-bearing one, — count in
the alternation of the pinnnles as one joint. Their apposed faces are not
necessarily striated, as indicated by Miiller, being sometimes dotted or
smooth. Smooth syzygial faces have been observed in recent Crinoids only
in a few Comatuls, but they occur quite frequently among Paleozoic species.
In the latter, we also find occasionally a succession of two or three hypozygal
joints in the same syzygy.t

Syzygies do not occur among Paleozoic Crinoids at irregular intervals as
in recent ones. Hither they have a continuous series of syzygies through-
out the whole arm, as in the Heterocrinide and a few genera of the Came-
rata, or there is one syzygy in each order of brachials, which is formed
by the two proximal plates. The latter is frequently the case among the
Poteriocrinidx, Enerinidex, and also in the Camerate genus Dichocrinus. In
Dichocrinus, the suture between the syzygial plates is very close, and the line
of union more faint than the lines of adjoining plates. In the Poteriocrinidee
either the apposed surfaces are flat, or the hypozygal plate is slightly ex-
cavated, and the epizygal correspondingly convex. In Enerinus hiiformis the
corresponding faces are dotted so as to make a very close union. The Poterio-
crinide may have one or two costals within the same genus. In species with
two, both plates together take the form and size of the one; and this rule
applies to the proximal distichals as well. That the two plates of the costals,
as well as those of the distichals, form a syzygy, is practically shown by the
pinnules, which in species with but one costal begin with the first plate after

* Ueber den Bau des Pentacrinus caput medusee (Abhandl. d. K. Akademie der Wissenschaften, Berlin,
1843, p. 215).

+ The term “ syzygy”’ has also been used by some writers for the immovable union of the nodal stem-
joints with those next below them, as in the case of Pentacrinus. This, we think, is not in accordance with
Miller’s definition, who proposed the term for two arm-joints of which only the upper is pinnule-bearing,
and not for a special mode of union between plates generally. Radiated and dotted surfaces do not always
imply a syzygy. Such faces are found among Paleozoic Crinoids very frequently on the ordinary arm plates,
and even, as in Crotalocrinus, between the plates of the dorsal cup. The union between the syzygial joints is
nothing but an ordinary close suture, which may have striated or smooth surfaces.

It

82 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the axillary; while in species with two costals the first pinnule is given off
from the second distichal. In the Heterocrinide, in which the syzygies pre-
vail throughout the whole arm, they are formed in most of the species by
more than two plates. While Hpactocrinus grandis has but one hypozygal,
Heterocrinus has two or more, followed by the epizygal bearing the pinnule,
which in this group might be properly called an armlet. A similar arm
structure is found among the later Calceocrinide, and also in the Belemno-
crinids. In Epactocrinus grandis the syzygies are especially well marked, the
epizygal joints being wedged-shaped, the hypozygal quadrangular, and
arranged parallel to the distal faces of the preceding epizygal.

In some groups of the Fistulata it is exceedingly difficult to discriminate
between pinnules and armlets. As arule, pinnules are more delicate, and
are given off, except in cases of syzygy, from successive joints; while most
of the armlets are arranged at more or less irregular intervals along the sides
of the ordinary arms, and are usually branching. . We find armlets among
the Heterocrinidsz, Belemnocrinidx, in Barycrinus, Botryocrinus, and the later
Calceocrinidses. The Cyathocrinidx have long filiform arms, which frequently
dichotomize, but have neither armlets nor pmnules. The Anomalocrinide
have branching arms with pinnules. The latter are given off in rows from
every joint at one side of the arm only —not alternately from opposite
sides — from one axillary to another, reversing their position in the succes-
sive divisions. The Hybocrinide, which represent one of the most primi-
tive forms of the Fistulata, possess but one arm to the ray, and have neither
pinnules nor armlets. The Catillocrinide have numerous simple, pinnuleless
arms, given off directly from the radials, without the interposition of
axillaries.

In the Camerata the lower brachials take part in the calyx. That these
plates were free in the early larva, and were gradually incorporated, is
clearly indicated by the ontogeny of recent Crinoids, as well as the phy-
logeny of fossil ones. In the early Pentacrinoid larva of Antedon the
arms are free from the radials up, and the costals and distichals are sub-
sequently drawn into the calyx by the gradually increasing perisome. This
was evidently the case in the Camerata also. But while in the former the
perisome consists of soft tissues encrusted with limestone particles, the peri-
some of the latter is formed of well-defined plates. Our knowledge of the
ontogeny of Camerate Crinoids is of course limited; all we know is that
smaller specimens have a less number of interbrachial plates, that the number

MORPHOLOGICAL PART. 83

increases with the size of the specimens, and that with the increase of the
latter additional brachials are incorporated into the calyx. We have found
a number of young specimens in which the arms are free from the first
axillary, but, as yet, no Actinocrinus or Rhodocrinus in which there is not at
least one interbrachial.

. We find among the Camerata a large number of transition forms in
which the costals do not form a part of the dorsal cup, and the first inter-
radials, to a large extent, are interambulacral in position. Such is the case in
the Platycrinide, Hexacrinide, Acrocrinidse, and Crotalocrinide. In Platy-
ermus the distal ends of the radials are provided with a horse-shoe-shaped
excavation, which closely resembles the facets of the Inadunate Cyatho-
crinide. This facet, which in some species extends down to two-thirds the
length of the plate, rarely takes up more than half its width. It is occupied
by the costals, or, when these are very small, in part also by the first dis-
tichals. The costals are narrow, and resemble in form and general appear-
ance the free brachials of Inadunate Crinoids.. They are, however, not free
in the sense of these, but the proximal ends of one or both plates are sutur-
ally connected with the plates of the tegmen, so as to be immovable, and
only their upper ends are free from the calyx.

It has been generally supposed that there was in Platycrinus and Dicho-
crmus an articulation or loose union between the radials and costals. This
seemed to be confirmed by the presence of the facet, and by the fact that in
some species this is provided with a sort of imperforate transverse ridge, or
angularity. We have no doubt that these costals were movable at some
period of life, probably in the larva before the perisome made its appearance,
and the orals still rested upon the beveled edges at the outer ends of the
radials. But it is equally certain that the plates were immovable in the
adult, owing to the rigidity of the interradial and covering pieces, with which
they are suturally connected. The systematic position of the Platycrinide is
intermediate between the Inadunata and the typical Camerata. They repre-
sent phylogenetically an early stage of Actinocrinus, Batocrinus, and their
congeners; but are nevertheless true Camerate Crinoids, for their lower
brachials are fixed, retaining, however, permanently to a large degree the
characteristics of free arm plates. In Cudcocrinus and Pterotocrinus, the one
a Platycrinoid, the other a Hexacrinoid, the Camerate type is somewhat
more advanced, as their costals practically enter the dorsal cup; and there
are a few species of Platycrinus in the same condition (Plate LXXI., Fig. 16).

84 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

So there is an almost uninterrupted series of forms from the Inadunata to
the most completely developed Camerata.

It has been stated that in Dichocrinus the various orders of brachials, to
the last bifurcation, consist of two plates each, and that the plates of each
order form a syzygy, the epizygal bearing an arm instead of a pinnule. A
similar structure is found in most species of Platycrinus from the costals up,
and although the union between these plates may have been less close than
in Dichocrinus, they evidently form a syzygy, except in cases in which the
first plate of the order is pinnule-bearing, as in P. Huntsville and P. Sare.
It is very significant that in both these species, and a few others, the first
pinnule is given off from the first distichal, and the second on the same side
from the first palmar, thus showing that the arm partakes of the alter-
nation of the pinnules; and this suggests the question whether all arm-
branches are not enlarged pinnules. In Lucladocrinus, which is actually a
highly differentiated Platycrinus, the branches are given off alternately from
every second joint up to the end of the rays, exactly like the pinnules in
cases of syzygy; but while in Platycrinus the axillaries are in their normal
condition, —the superior faces equally divided,— in Hucladoerinus they are of
irregular form. They resemble enlarged pinnule-bearing plates, of which
the side supporting the next order of brachials is much wider than that
giving off the arm (Plate LXXIV).

There can be but little doubt that in Hucladocrinus the lateral arms in the
young Crinoid were pinnules; and there is abundant proof that this was
also the case with the arms of other groups, as is well shown by Gilyptocrinus
Dyeri. In most species of Glyptocrinus, for example, G'. decadactylus,* the
second bifurcation takes place from the second distichal. In G. Dyer, how-
ever, this plate gives off from one side in place of an arm a large pinnule,
more than twice the size of an ordinary one; and a second pinnule, but
little smaller, starts off from the fourth distichal on the opposite side. Both
pinnule-bearing joints have nearly the shape of true axillaries, and what is
most remarkable, the arm bends outward, forming an angle, as if a true bifur-
cation took place. (Place XX., Fig. la, 4,c). The four or five proximal
pinnules of this species are incorporated into the calyx, and it is quite evi-
dent that the growth of the armlets— or pinnules, whichever they are —
was arrested by the rapid upward growth of the perisome. All succeeding
pinnules are small, and given off alternately from successive joints.

* This species has twenty arms, and not ten as indicated by the name.

MORPHOLOGICAL PART. 85

The structure of this species is a very strong indication that the arm
branches are modified pinnules; and this suggests that non-pinnule-bearing
brachials, whether fixed or free, may form a syzygy whether the succeeding
axillary supports an arm ora pinnule. Carpenter pointed out* that among
recent Crinoids, with but few exceptions, “ the first two joints beyond every
axillary of the dividing rays are united to one another in the same man-
ner, elther by syzygy or bifascial articulation.” This rule seems to hold
good also for most of the Paleozoic Crinoids, with the exception that we
find among them only syzygies, and no articulation.

The Actinocrinide, as we have stated, represent an advanced stage of
the Camerate type. Not only their costals, but also their distichals, and
generally several more orders of brachials, participate in the formation of
the calyx, and all the branches are given off alternately from opposite
sides of the main trunks. In the genus Actinocrinus, + only every second
or third brachial of each order in the calyx supports an arm (Plate LX.,
Fig. la); but in Cactocrinus, Physetocrinus, Teleocrinus, and Strotocrinus, an
arm originates from each successive plate (Plate LXV., Figs. 1a and le), and
the arms alternate like the pinnules. In Actinocrinus occasionally, and in Am-
phoracrinus generally, branches are also given off at irregular intervals from
the free arms; but these evidently made their appearance after the arms
had become biserial. In Stegancerinus the branching is continued to the top
of the rays, as in Hucladocrinus (Plate LXI., Figs. 1a and 1d), and each order
of brachials consists of one, two or three plates, which are formed into tubular —
appendages of the calyx, giving off biserial, pinnule-bearing arms. Accord-
ing to our interpretation, we have in Actinocrinus and Steganocrinus a series
of syzygies, in the former extending to the top of the calyx, in the latter to
the top of the rays; as opposed to Cuctocrinus, Strotocrinus, etc., in which
each order of brachials consists of a single plate, which is axillary.

The pinnules of the Actinocrinide differ from those of other families in
being provided with prominent hooks, directed obliquely upward and out-
ward. These hooks are arranged in rows parallel to the sides of the arms,
and those of one pinnule overlap the corresponding ones of adjoining pin-
nules (Plate LVI, Figs. 1 and 7a, 4, ¢), so as to give to the mass of pinnules
the appearance of a highly complicated network.

* Chall. Rep. I., p. 49.

+ We subdivide the genus dctinocrinus, as heretofore recognized, into Actinocrinus proper, and Cacto-
crinus ; referring to the former only the lobed species with two or more brachials to each order; and to the
latter those in which the free arms are arranged equidistant around the calyx, and each order of brachials
above the costals consists of but one plate.

86 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

In the Batocrinids, we find an arm structure such as occurs in no other
group. While in all other Camerata the ambulacral openings of the calyx
give origin to but a single arm, those of the Batocrinites frequently bear two,
elther from every opening or from any less number of them, and this, which
is very remarkable, even in the same species. Thus the specimens may have
eighteen arm openings and but eighteen arms, or any number from eighteen
to thirty-six. This mode of multiplying the number of arms is found only
among the later forms, and it is evident from the structure that the second
arm, where it occurs, was introduced in the nearly mature individual after the
arms became biserial, and the lower orders of brachials had been incorporated
into the calyx. The bifurcation takes place in the same manner as in free
biserial arms, there being no true axillary, and the plate taking its place
is no larger than the succeeding arm pieces.

In the Batocrinide, all branching in the calyx is by means of dichotomy,
and the number of arm openings in the three anterior rays rarely exceeds
four; but there may be only two or three, and in the posterior rays, the
arms next to the anal interradius may bifurcate once or twice again, so that
two of the rays have five or six arm openings. In some genera the number
of arm openings varies considerably among the rays, the anterior, or occa-
sionally the antero-lateral ones, being generally the least developed. This is
not the case in the Actinocrinide, in which normally, with one or two excep-
tions, the number of arms is equally divided among the rays. In the Peri-
echocrinites, which we made a subdivision of the Batocrinidx, the free arms
almost always branch in their biserial stage ; while they remain simple in
the Batocrinites.

In Melocrinus a very peculiar arm structure occurs, somewhat similar to
that of Steganocrinus and Hucladocrinus; but while in the latter the two divi-
sions of the ray form independent appendages, all the way from the calyx
up, those of Melocrinus, either for some distance or to the full length of the
rays, are laterally connected, and form together but one appendage, from
which the arms are given off at intervals from opposite plates in the ray,
and from one side only of each half.

In most of the Rhodocrinide and Thysanocrinide, the arms branch in
their free stage, whether uniserial or biserial. The arms of Ripidocrinus are
given off at both sides of the main rays, as in Steganocrinus sculptus. Those of
Gilbertsocrinus are very delicate, and frequently pendent. The latter is the
case also in some species of Acrocrinus, and the Swedish genus Barrandeo-

MORPHOLOGICAL PART. 87

crinus, 11 Which they completely envelop the calyx, exposing their ventral
surfaces. !

The mobility of the arms in the Camerata must have been limited, as we
nowhere find at the apposed faces of the various brachials any trace of a
muscular attachment. Those brachials which take part in the calyx are,
like the other calyx plates, united with one another and with adjoining
plates by close suture, the apposed surfaces being flat and generally smooth,
rarely striated ; and the plates are immovable. The first indication of any
kind of articular facet occurs on the highest plate of the calyx; 7. e., that
bearing the free arms. This plate is usually more or less concave, often
striated, sometimes having a sort of ball-and-socket arrangement, or being
provided with an obscure transverse ridge; and in a few cases it is perfo-
rated. The faces of the higher arm plates are smooth or striated, and but
little concave; yet there must have been a considerable amount of mobility
even among them, for the tips of the arms are frequently curved inward, and
in some cases the arms are decidedly spreading. |

The mode of union between the brachials of the earlier Fistulata was
similar to that of the Platycrinide. The Dendrocrinide and Cyathocrinidx
have more or less well developed facets upon the radials, and the arm
plates are united among themselves and with the radials by ligaments
only, so as to admit but little motion. In the later Fistulata, however,
notably the Poteriocrinids * and Encrinidx, there is a muscular articula-
tion between the axillaries and the joint succeeding them, as in recent
Crinoids.

The Larviformia, so far as they are known, have a well differentiated
muscular articulation, with transverse ridge and fossee between the radials
and costals, but not between the succeeding brachials. Cupressocrinus, Allage-
crinus, and Symbathocrinus have large muscle plates connected with the radi-
als; while the other brachials are so closely united one to another that it
appears as if the whole arm had moved rigidly upon the radials.

In the Ichthyocrinide all the brachials, whether fixed or free, are mov-
able. ‘The calyx was pliable from the radials up, as is shown by the apposed
faces of the plates, which are deeply hollowed out; not only those of the
brachials, but the interbrachial plates as well. The cavities, which evi-
dently lodged large bundles of ligament, contain small elevations with stri-

* It is unfortunate that the genus Poteriocrinus has been made the type of this family. It is the only

genus of the Poteriocrinide in which the facet supporting the arms is horse-shoe-shaped, and the costals do
not occupy the full width of the radials, which is so characteristic of the family.

88 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

ated faces. Those of the fixed brachials form irregular ridges, which proceed
from both sides of the plates toward the middle without meeting. The
apposed faces of the free arm plates have been rarely observed, but so far as
known they are more or less concave, and we have found on some of them
indications of transverse ridges. The lines of union between the brachials
generally have a waving outline, and many of the species have a sharp pro-
cess projecting from the distal end of the plates, which fits into a shallow
depression upon the outer face of the plate below. In some species, especi-
ally the larger ones, this projection forms a separate plate. The arms of all
Ichthyocrinide are uniserial, the joints quadrangular, and they are destitute
of pinnules. |

Il. THE PLATES OF THE ACTINAL SYSTEM.
A. The Orals.

THe orals are not always represented in the adult Crinoid. When
present, they surround the mouth or cover it; and they may occupy the
whole face of the ventral disk, or only its median portions. In the former
case they rest upon the edges of the radials; in the latter against the peri-
some. In Crinoids with a regular pentamerous symmetry they consist of five
pieces, interradially disposed, and occupy the centre of the disk. When the
symmetry is irregular, they are pushed more or less toward the anterior side.
The former condition prevails among the recent Crinoids, and in the Larvi-
formia ; the latter is the general rule among Paleozoic forms. When asym-
metrical, the posterior oral is pushed in between the four others, and is
generally larger (Plate II., Figs. 11, 17, 18, 20, 21, 22, and 23),

The orals are among the earliest plates developed in the larva. They
make their appearance simultaneously with the basals, upon which they rest
until the radials are introduced, when they occupy the beveled upper edges
of the latter plates. In the larva of recent Crinoids they form a pyramid,
composed of five nearly equal pieces, which at first are laterally united and
closed at the top; but they soon open out, and expose the tentacular vesti-
bule. Ata more advanced stage the orals are carried inward by perisome,
until finally in most of the species they become resorbed, and are replaced
by upward perisomic growth. In only a comparatively few recent forms do
they persist through life, and in these cases they occupy the median portions
of the disk, and enclose the oral opening (Plate III., Figs. 9 and 10).

MORPHOLOGICAL PART. 8g

While thus among recent Crinoids the orals are readily recognized, their
identification among Palzozoic forms has been the subject of much contro-
versy. Allman* in 1863 expressed the opinion that the group of plates in
the centre of the vault of many Palzeocrinoids is a representative of the sim-
ple oral system of the young Comatula ; but as those plates often consist of
more than five, it was not made clear to which particular ones his homology
applied. In most Paleozoic Crinoids there is no oral opening, and the
arrangement of the plates at the summit is irregular and quite variable.
This is the case particularly among the Camerata, in which the median
portions of the disk “are generally occupied by a large, centrally located
plate, surrounded by eight or nine others, of which four are large and
similar in form and size. These four larger plates are directed toward
the anterior side of the disk, forming at their outer edges re-entering
angles, which are filled by three rather large plates, radially disposed ;
while the four or five smaller plates of the proximal ring are directed
posteriorly, and are followed by numerous more or less irregular pieces,
directly or indirectly connected with the anus (Plate IIL, Figs. 17, 18, 20,
21, 22, and 23). Occasionally the larger plates are separated from one
another by small, supplementary pieces (Plate III., Fig. 23). This is the
case in some of the larger species, in which the small pieces were intro-
duced in the growing Crinoid. There are also species in which the larger
plates are not represented at all, and the whole ventral disk is composed
of minute pieces without definite arrangement, leaving only an opening
for the anus (Plate III., Fig. 24).

The interpretation of these plates has proved the more difficult because
in other groups, notably the Larviformia, the tegmen consists of but few
pieces, which have a different arrangement. In Allagecrinus and Myrtilo-
— ertmus (Plate HI., Fig. 13), the whole ventral surface is covered by five large
interradial plates, resting upon the superior edges of the radials, exactly as
the orals in the Pentacrinoid larva of Antedon. Huaplocrinus (Plate IIL, Fig.
14) has five similar plates, which were at one time supposed to surround a
small central plate. Symbathocrinus (Plate III., Fig. 25) has a pyramid of
five large plates, four of them resting upon the edges of the muscle plates of
the radials, and partially surrounding a larger one, wedged in from the pos-

* Trans. Roy. Soc. Edinb. Vol. XXIITL., pp. 245-251.
+ Our supposed discovery of this plate in a specimen of Haplocrinus mespiliformis proved afterwards to
be a mistake, due to the peculiar fractures in the specimen. Carpenter, to whom we submitted the specimen,
12

90 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

terior side to a nearly central position. The description of the ventral plates
of this genus in the Revision, Part III., p. 37, was incorrect as to the small
pieces around the five summit plates, the appearance of which was produced
by cracks and not sutures. Specimens of better preservation show positively
that the ventral surface is occupied exclusively by the five large plates.
Pisocrinus, as shown by a specimen of P. pilula in our possession from Dudley,
England, has a similar structure. Among the Camerata five large summit
plates are known to exist only in Coecoerinus and Culicoerinus, the plates
of the former being equal (Plate IIL, Fig. 14), those of the latter slightly
unequal.

As the large central plate, when it occurs, occupies approximately the
same position as the oral opening of recent Crinoids, it seemed plausible that
the orals, if present at all, should be looked for in the Camerata among the
plates of the proximal ring; but on examining the structure, it was found
that only the four larger plates could be compared with the five orals of
recent forms; so the question arose, what had become of the corresponding
fifth plate ?

Wachsmuth, in 1877,* directed attention to the two plates of the same
ring adjoining the four larger ones, and suggested that these two plates
taken together were probably equivalent to one, being split into two by the
anus, and that the six plates represented morphologically but five. The
plates were not, however, regarded by him as the orals; he thought the
whole ventral covering of the earlier Crinoids was structurally distinct from
the disk of recent ones.

A similar view of the subject was taken by us in the following year.t
We assumed that the plates of the dorsal cup and those of the tegmen were
parallel structures; that the central plate was represented in the dorsal cup
or abactinal side by the infrabasals, the six proximals by the basals, and that
other plates of the tegmen represented the radials and interradials. No
comparison was then made by us of these plates with the plates in the disk
of recent forms; but this was done in 1881,+ when we suggested that the six
proximals represented the orals.

Dr. P. H. Carpenter, like ourselves, recognized in the Camerata a central
plate, for which he proposed the name “oro-central,” and six proximals

verified our observation, and held the plate to be homologous with the so-called central plate of the Camerata,
(Chall. Rep. on the Stalked Crinoids, p. 158).

* Amer. Journ. Sci. and Arts (series 3), Vol. XIX. pp. 186-187.

+ Revision, Part I., p. 28.

¢ Revision, Part II. p. 17 (Proceed. Acad. Nat. Sci. Phila., p. 191).

MORPHOLOGICAL PART. 9]

surrounding it. He regarded the former as the actinal representative of the
dorso-central or terminal plate of the stem, and the latter the representatives
of the basals. He took the proximals to be the orals, believing with us that
the posterior oral was divided into two plates. He said:* “The proximal
dome plates rest directly against the calyx interradials, that on the posterior
side being represented by two small plates with the anus between them;
while there is a more or less tubercular ring of radial dome plates outside
them. These proximal dome plates thus correspond exactly to the orals of
Symbathocrinus and Haplocrinus, covering in the peristome, and resting against
the calyx plates, which in Platycrinus are the interradials, and not the upper
edges of the radials, as in the simpler forms. . . . I cannot see what other
view can be taken of the proximal dome plates which immediately surround
the oro-central, than to regard them as orals; 7. ¢., as the actinal representa-
tives of the basals, like the corresponding plates in Symbathocrinus. If this
be admitted, it follows that the proximal dome plates of all Platycrinide,
Actinocrinidge and Rhodocrinide are also homologous with the orals of Neo-
crinoids.”’ f+ Carpenter’s oral theory was based almost entirely upon the
hypothetical oro-central, — a plate before unknown in Echinoderm morpho-
logy, —and the six proximal plates, which he assumed to be orals, although
their morphological relations had never been established.

The same view of the question was also taken by Etheridge and Car-
penter,t and afterwards by Neumayr;§ while Zittel|| supposed the orals
to be unrepresented in all Platycrinids, Actinocrinide, Rhodocrinide, and
Calyptocrinide ; though admitting their presence in some of the other
groups.

The above theory was laid aside by us in 1885, when we ascertained that
the two smaller proximals, which we had supposed to represent the posterior
oral, occupy a radial position, and therefore could not be orals, The struc-
ture shows that these plates undoubtedly represent the two posterior radial
dome plates, pushed to a position among the plates of the proximal ring by
the anus, the three anterior ones retaining their position within the re-
entering angles of the four larger proximals. This discovery was announced
by us in Part III of the Revision, p. 47, and we designated the respective

* Chall. Rep. Stalk. Crin., pp. 170 to 171.

+ Dr. Carpenter’s views on this subject are fully set forth in the Chall. Rep. Stalk. Crin., pp. 158
to 184. |

t+ 1886. Catalogue of the Blastoidea, pp. 66 to 75.

§ 1889. Die Stamme des Thierreiches, p. 448.

|| Handb. der Paleont., I, p. 382.

92 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

plates by the letters “7x” in the accompanying diagrams.* There now re-
mained among the plates of the proximal ring but four which could possibly
be taken for the orals; and this led us to inquire whether the central plate
alone might not be a coalesced representative of the five orals of recent forms.

From internal casts we observed that this plate occupies the centre of
radiation, and that not only the ambulacra, but also the nerve cords, meet
beneath it. It was this structure principally which led us to the assumption
that the central plate represented the five orals collectively, and that the
four large proximals, and two smaller ones, were interradial “ vault” plates,
corresponding with the first interradials of the abactinal side. This seemed
to us the more probable, as in the dorsal cup a division of the first interra-
dial into two halves by an anal plate is a frequent occurrence among Palseo-
zoic Crinoids. It also seemed to explain why in Haplocrinus and allied forms,
in which there is no anal plate, the central piece seemed to be surrounded
by five plates instead of six, supposing, as before stated, that Haplocrinus had
a small oral surrounded by five interradial plates, and Adlagecrinus, Coccoerinus,
and Culecocrinus five interradials, but no orals. In this we differed from Gétte,
Carpenter, Zittel, and Neumayr, who all agreed that the Scheitelplatten were
the orals.t

This was the state of the question in 1888, when we came into posses-
sion of a very large number of fine specimens of Haplocrinus mespiliformis
in various stages of preservation, and found to our astonishment that
such a thing as a “central” plate does not exist in the genus. We now
saw that the ventral disk consists of but five large plates; that we had
mistaken a mere fracture for a suture; and that the part which we sup-
posed to be a separate piece was a tongue-like prolongation of the posterior
plate, projecting in between the other four plates, and sometimes surmounted
by a small node (Plate HI., Fig. 124). This discovery left no room for doubt
that the large ventral plates of Haplocrinus, and of the Laviformia generally,
actually represent the five plates composing the unopened oral pyramid of
the Pentacrinoid larva before it moved away from the radials, as had been
contended by Carpenter and Gcette.

So long asa central plate was recognized in Haplocrinus, we saw good
reason to believe in the existence of a similar plate in other groups of the

+ Revision, Part III. Plate VII. Figs. 2, 3, 4, 5, 6, 8, 9, 10, and Plate VIII. Figs. 1 and 2.

+ Our theory of the relations of the summit plates, in conformity with these views, was discussed in the

Revision, Part III. pp. 44 to 59, and afterwards in greater detail in our paper on the Summit Plates, in the
Proceedings of the Academy of Natural Sciences, Philadelphia, March 29, 1887.

=

MORPHOLOGICAL PART. U3)

Palzocrinoidea; but as soon as it appeared that there is no such plate, it
occurred to us that the plate, so apparently central in many Platycrinide
and Actinocrinidz, might be a posterior oral, pushed inward to a central
position by anal structures. This interpretation seemed to us one of the
greatest force, more likely than any other to answer the conditions of a valid
homology, and to remove the principal objections that had been brought
forward by Carpenter and ourselves respectively to other theories.

The idea of referring the plate to the orals was not altogether new. We
had already taken it into consideration before we knew the real structure of
Haplocrinus, and alluded to it in the Revision, Part III, p. 56, as follows: “A
far less objectionable interpretation of the central plate than that given by
Carpenter would be to regard it as a posterior oral. In this case the orals
would be represented by five plates, and not by six; the anus would be
placed outside the oral ring, and the radial dome plates would occupy the
same position towards the orals as the calyx radials toward the basals. But
it would place the mouth underneath the posterior oral, and it offers no
explanation of the central piece in Haplocrinus.’ The last of these diffi-
culties which then seemed so serious was met by the elimination of the
mythical plate in Haplocrinus ; and the first was destined to be perfectly
cleared up by the recovery of a new fragment from the scattered pages by
which Nature unfolds her paleontological story to us. |

While writing up the observations which we had made on Haplocrinus, we
made another still more unexpected and striking discovery, which in our
opinion settled the oral question in conformity with the last mentioned sug-
gestion beyond all controversy. Up to that time the ventral structure of
the Ichthyocrinidse had been almost totally unknown. By extraordinary
good luck we obtained a specimen of the genus Zaxocrinus with the ventral
disk in almost perfect preservation, and after carefully cleaning the speci-
men, we found that it had an external mouth, surrounded by five parted oral plates,
with the ambulacra converging to wt, and passing in between the orals. (Plate III.,
Digit |

The middle of the disk is occupied by five rounded or very obtusely
polygonal plates, interradially disposed, rather oval in outline. The two
antero-lateral plates are tolerably good-sized, and the postero-lateral ones
slightly smaller. The posterior plate is nearly three times as large as any

* A full account of this unique specimen was given by us in a paper, “ Discovery of the Ventral Struc-
ture of Tarocrinus and Haplocrinus, and Consequent Modifications in the Classification of the Crinoidea.”
Proceed. Acad. Nat. Sci. Phila., Nov. 27, 1888.

94 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

of the others, and almost twice as long as wide, extending well in between
the two postero-lateral plates.

The positions of these plates are relatively identical with those of the five
plates at the summit in certain forms of Platycrinus, such as are illustrated on
Plate III., Figs. 16 and 17, except that the plates of Taxocrinus do not meet
in the centre, but leave a slightly excentric, obtusely pentagonal oral open-
ing, transversely elongated, its longest side next to the posterior plate. ‘Into
this opening, which is deep, the ambulacra converge, and turn downwards at
the five corners. |

That the five plates of this specimen, although somewhat unequal in size,
represent morphologically the five orals of the recent genera Riizocrinus,
Hyocrinus, and Holopus, nobody will deny after seeing the specimen. Anda
comparison of these plates with the so-called central plate and four large
proximals in Platycrinus, Actinocrinus, etc., leaves no room for doubt that these
are likewise true orals, The arrangement of the plates in the different
groups is practically the same ; the only difference is that in some they are
less symmetrically disposed than in others. In TYazocrinus, the anus is well
removed from the oral centre, which accounts for the fact that the arrange-
ment of its orals is rather more symmetrical than in most of the Camerata,
in which the anus is more or less subcentral, and surrounded by heavy, rigid
plates. That the amount of asymmetry depends upon the condition of the
anus 1s clearly shown by the figures on Plate III. When the anus is excen-
tric, and its plates are small, the arrangement of the orals is comparatively
symmetrical ; but when it is subcentral, and especially when it is extended
into a large tube, the orals are pushed over to the anterior side. In Haph-
erimus, in which the anus penetrates the orals, and in Coccocrinus, in which it
occupies the arm regions, the oral pyramid is naturally about symmetrical. It
is now easy enough to understand how a set of five plates, symmetrically dis-
posed over the mouth, could be so altered by the introduction of anal plates
as to bring the mouth and centre of radiation beneath the posterior plate.
By the encroachment of the anal plates the posterior oral was pushed to a cen-
tral position, and thereby the mouth came to be placed beneath that plate.

The above explanation of the orals in the different groups met the
prompt approval of Carpenter, and this ended a long controversy which
had been going on between us for over six years. The orals were found
at last to consist of four of the proximals which he had claimed, with the
addition of the so-called central plate which we had contended for.

MORPHOLOGICAL PART. — 95

It remains to consider the views of Neumayr. As already stated, he
agreed with Carpenter that the Scheitelplatten of Haplocrinus, and the six proxi-
mals of the Camerata, represent the orals. He also believed in the presence
of a central plate within the oral ring in both groups. But he differed
both from Carpenter and us as to the plates representing the orals in the
Cyathocrinide.

The structure of the ventral disk of Cyathocrinus exhibits considerable
variability, and a comparison of the various plates among the different
species is by no means an easy matter. As a rule, there are four large
interradial plates located ventrally, resting upon the inflected upper edges
or limbs of the radials, and at the posterior side two narrow longitudinal
strips, which enclose a large, perforated madreporic plate lying in front of
* the ventral sac, and whose lower (outer) edge is in contact with the sac.
The plates are laterally united by suture, and leave five well defined grooves
which are occupied by the ambulacra. Within these plates, towards the oral
centre and covering it, there is a variable number of other large plates, often
of the most irregular arrangement, varying in form even in the same species,
and in some cases exhibiting the asymmetry of the orals in the Camerata.
The difficulty of ascertaining the morphological relations of these plates in
the different forms is increased by the fact that the surface of the outer
plates — those nearest the radials —is covered by numerous minute peri-
somic pieces, interposed between the ambulacra. The ambulacral plates
consist of side plates and covering pieces.

Neumayr * speaks of only one ring of plates, resting against the radials .
and surrounding the mouth, and he assumes that the disk of Cyathocrinus
is morphologically in the condition of Haplocrinus, except that the ambu-
lacra in the latter are subtegminal, but tegminal in the other. We have
illustrated on Plate III the ventral structure of Cyathocrinus by a series
of specimens of different geological ages, and in various stages of preser-
vation, which show that the disk is composed of two sets of plates, the
one within the other, and that in cases where but one ring is visible the
plates of the second are covered by other structures, or have been resorbed,
or are not preserved in the specimen. It is evident that Neumayr has in
some instances confounded the plates of one ring with those of the other.

HKxamining first the two specimens of (C. Golesi (Figs. 1 a, 6), there appears
to be but one ring of plates, and these rest against the radials. In Fig. la

* Die Stamme des Thierreiches, pp. 449-452.

96 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

those plates are completely exposed, in Fig. 14 partly covered by marginal
pieces ; but in both of them there is at the middle of the disk a moderately
large vacant space, which in perfect specimens is tightly closed by additional
plates. C. brevisacculus, Fig. 2, has two rings of plates: an outer one, com-
posed of five subtrigonal pieces, of which the posterior one is largest and per-
forated, and an inner one, composed of five pairs of plates nearly as large as
the former but of variable size and form, which meet in the centre, so as to
close the mouth and peristome. The ambulacra are exposed all along the
plates of the outer ring, but are covered by the plates of the inner. In
C. nodosus, Fig. 3, and C’. multibrachiatus, Fig. 4, the four large interradial plates
above the radials, which in the preceding figures are wholly or partly exposed,
are completely hidden from view by small marginal pieces. The middle of
the disk is covered by a number of rather large pieces, even more irregular ~
in their arrangement than those of C. brevisaceulus. ‘The ventral disk of Luspi-
rocrinus spiralis, Fig. 5, has at four sides a very large, convex interradial plate,
and at the posterior side an unusually large ventral sac, with a small madre-
porite at its base; the ambulacra are tegminal; and the median portions of
the disk are closed by moderately small, elongate plates, arranged in rows
with the side pieces, which meet in the centre. Very different is the disk of
Cyathocrinus alutaceus, Fig. 6, which has at the summit five large plates, in form
and arrangement resembling the orals of Platycrinus. The posterior one is
largest, subcentral in position, and pushed in between the other four, There
are no grooves along the lateral margins of the plates, the ambulacra being
subtegminal; but the re-entering angles at the lower end enclose five well
proportioned radial dome plates.

Comparing the summit structure of C. alutaceus with that of the Camerata,
it is quite evident that the five large plates of Fig. 6 represent the so-called
central plate and the four larger proximals. This was also the opinion of
Neumayr ; but while we take all five plates to be orals, he clung to the idea
of a central plate, and recognized six orals, assuming that two of the radial
dome plates represented the posterior oral. We do not see how these plates,
which occupy the median portions of the disk and cover the mouth and ends
of the ambulacra, can be the morphological representatives of the plates
which in Figs. 1, 2, and 5 rest upon the radials. Neumayr took the two
structures to be equivalent, while we believe that the plates of the former
represent the orals, and that the latter are accessary pieces of a similar
origin to the interradial plates of the Platycrinide.

MORPHOLOGICAL PART. 97

According to Neumayr, the disk of Cyathocrinus is composed of five large
plates, which, like the Scheitelplatten of Haplocrinus, abut against the radials.
The plates, he thinks, are in sutural contact laterally, but leave at the sum-
mit a large space for the mouth. The ambulacra are exposed upon the sur-
face, resting within the deep grooves, formed along the lateral margins of the
plates. They extend from the mouth to the bases of the arms, and are cov-
ered by small plates, which project inward over the peristome, and close the
mouth externally. The small marginal plates, which, as he states, in some
species extend over the whole disk, he takes to be “ eine secundiire Wuche-
rung” of the side and covering pieces.

His description does not agree with our idea of Cyathocrinus ; it comes
closer to the structure of Huspirocrinus spiralis, from which it was probably
made. ‘The latter really seems to have but one set of large plates upon
the disk, which touch the radials, and enclose at the summit moderately
small plates, which may be ambulacral pieces; but the former are not orals.
Cyathocrinus Gilest, as represented in our figures, has also but one ring; but
there is a large vacant space at the middle, which was evidently closed in
more perfect specimens by an inner ring of plates, as in the other species.
C’. brevisacculus has an outer ring of plates and an inner one, and the ambu-
lacra, which are exposed upon the former, are hidden by the latter. In C.
multibrachiatus the outer ring is covered by marginal plates, the inner rep-
resented by a few irregular, large pieces, scattered upon the surface, and
intermingled with ambulacral pieces. This specimen was illustrated by
Neumayr on page 473, from our figure in Part III of the Revision, and he
must have taken the irregular inner pieces for the orals, for only in this
way can we understand the explanatory remarks accompanying the figure.
He says: “ Wachsmuth and Springer figure a most remarkable example of
Cyathocrinus multibrachiatus, in which, as they show, the orals (summit plates)
are In process of resorption, and in part replaced by small plates.” In
C. alutaceus also, he took the inner plates, which in this species are un-
usually large and regular, for the orals, and for the homologues of the
outer plates of C. malvaceus,* C. Giles, and C. brevisacculus.

* Neumayr gave (Stamme des Thierreiches, p. 450), after Meek and Worthen, two figures of the ven-
tral surface of this species: Fig. 2, representing the ‘“ Kelchdecke ”; Fig. 3, “Dieselbe, nach Entfernung
der Deckplattchen.” The former has five large interradial plates, with a vacant space in the centre, much
larger than that of C. Gilesi, and the ambulacral grooves are exposed. In the latter the centre is closed by
seven plates, almost as large, and as regular in their arrangement (a central plate surrounded by six proxi-
mals), as in C. alutaceus. That he took these plates, contrary to those of C alutaceus, for covering pieces,
extensions from the ambulacra, and not for orals and central plate, is clearly indicated by the explanation of

the figures.
13

98 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Neumayr’s interpretation of the plates meets with serious difficulties.
There are in Cyathocrinus undoubtedly two sets of plates; the one occupy-
ing the centre of the disk, and covering completely mouth and peristome,
without grooves, and with the ambulacra subtegminal; the other occupying
the outer margins of the disk, grooved, the ambulacra tegminal, and covered
over by perisome which extends inward and closes the mouth. He under-
took to explain these difficulties by paleontological development, but over-
looked the fact that in the ontogeny of recent Crinoids the perisome is
introduced above the radials, and between the orals, and that the latter are
carried relatively inward. The same mode of development we find in the
phylogeny of fossil forms; the orals, with the introduction of interradial
plates, are moved to the centre of the disk, and either cover the mouth
or wunmediately surround it. That is the case in the Camerata and the Articu-
late Ichthyocrinidex, and there is no reason to doubt that it is the same way
in the Cyathocrinide. In the Larviformia, however, in which there is no
perisome, the orals rest against the radials, but also cover the mouth, as
they do in the Pentacrinoid larva.

We believe with Neumayr that the differentiations among the species
which we have noticed in the disk of Cyathoerinus are modifications due to
paleontological development. It seems to us that the orals throughout this
genus are more or less in a state of resorption, more advanced in one species
than in another, and even varying in degree in the same species. From this
we conclude that the Silurian C. alutaceus, in which the orals are almost or
wholly intact, represents the more primitive form of the genus, and C. malva-
ceus, etc., a later stage; and that Luspirocrinus, in which the orals are appar-
ently completely removed, and the ambulacra thereby brought into view
upon the disk, represents a more advanced stage than either species of
Cyathocrinus.

For proof that a resorption took place in the same species, we refer to the
specimen of C. alutaceus, Fig. 7, which differs essentially from Fig. 6. It is
also proved by numerous specimens in our collection,* which show distinctly
that the orals are proportionally larger, and more regular in their arrange-
ment in young specimens than in the adult. In one of the specimens, not
larger than a good-sized pea, they occupy fully two-thirds of the disk, being

* We have from sixty to seventy specimens in most excellent preservation, representing five species, in

which we exposed the disk by removing the arms. Most of them came from Indian creek, Ind. (Keokuk
group), though some are from Burlington, and a few from Crawfordsville.

MORPHOLOGICAL PART. 99

thus considerably larger than the plates occupying its outer margins, which
are also exposed in that specimen.

We thus find persistent among Paleeozoic Crinoids all the phases through
which the orals pass in their individual growth in recent forms, from the
early Pentacrinoid larva of Antedon to the adult Hyocrinus (Plate III, Fig. 10)
in which they are very large, and Calamocrinus * in which they are extremely
small; and we find the plates in process of resorption and entirely removed
from the system.

We further find that the orals in all Crinoids, recent and fossil, when
represented, occupy the centre of the disk, immediately surrounding the
mouth or covering it, and that the orals of the earlier forms differ from those
of the recent only in their asymmetrical arrangement, caused by the greater
rigidity and more extensive development of the anal structures.

B. Mouth and Ambulacra.

The presence of a single aperture in the disk of Palxozoic Crinoids
induced the earlier writers to suppose that this opening, although interradi-
ally disposed, served both as mouth and vent. Later observations, and
a better knowledge of the general structure of recent Crinoids, their mode
of feeding and the nature of their food, have shown conclusively that this
opening is not the mouth, but the anus, and that the mouth in most Palso-
zoic forms was subtegminal.

The mouth of all Crinoids is directed upwards, being placed in the centre
of radiation, but does not in all of them occupy the centre of figure. It is
very frequently subcentral, and may be altogether excentric. The latter is
the case in the asymmetrical genus Actinometra, and to some extent in all
Fistulata, in which the posterior side of the disk is extended into a large
tubular or sac-like prolongation. It is subcentral in most of the Camerata,
and central in all known recent forms, Actinometra excepted.

The ambulacra occupy the grooves along the ventral side of the arms,
and extend from the tips of the pinnules to the mouth. Their proximal
ends are either exposed upon the disk, or covered wholly or in part by
plates of the tegmen. Entering the mouth there are five main trunks,
which ramify so as to give a branch to every arm and pinnule, The upper
face of the ambulacra is occupied by the food grooves, which are roofed over

* A. Agassiz, Memoirs Mus. Comp. Zoél., Vol. XVII, Plate 6, Figs. 1 and 2.

100 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

by the covering plates, and frequently bordered by small side pieces; the
former arranged alternately with each other and with the side pieces. In
the living animal the food grooves are lined by cilia, which are kept in a
continual vibratory motion so as to produce currents of water, by means
of which any particles of food that happen to fall upon the grooves are
transmitted toward the mouth. Beneath the food groove lies a nervous
band, and beneath that a blood vessel, which in turn is followed by the
genital canal, and this by the subtentacular canal; the genital canal, which
is quite small, occupying only the median portions. The subtentacular
canal, also known as the ambulacral canal proper, from which branches are
given off to the tentacles, communicates with the annular vessel situated in
the lip around the mouth. Beneath the ambulacra is the axial canal,*
which occupies the bottom of the arm grooves, frequently piercing the body
of the plates. This canal is connected with the chambered organ at the
lower part of the dorsal cup, and contains the axial cords, which, as now
generally admitted, control the movements of the arms and pinnules; while
the nervous apparatus beneath the food grooves has no connection with
the muscles, and no influence upon the movements of the skeleton.

The ambulacra of fossil Crinoids are rarely observed, and their presence
is usually only indicated by the open grooves within the arm skeleton. In
some cases, however, the side and covering pieces of the disk, and occasionally
those upon the arms, are preserved.

In all recent Crinoids the covering pieces are movable from the tips of
the pinnules to where they enter the mouth, but they: are rigid upon the disk
in Paleozoic species, with perhaps a few exceptions. In the Camerata, and
especially among the Platycrinide, they are often heavier and larger than
the interambulacral plates ; while in other groups, and chiefly among Silurian
forms (Plate III. Fig. 11), they are quite small. The larger the plates, the
more irregular they are in their arrangement, and the smaller the most
regular. It is also noteworthy that the ambulacra may be tegminal or sub-
tegminal in the same genus. Those of the Platycrinide, asa rule, are tegmi-
nal, those of the Actinocrinide generally subtegminal ; but also the opposite
is the case in genera of both groups.

There is considerable variability in the extent to which the ambulacra
are exposed upon the surface. In the Camerata they never extend out. to
the centre of the tegmen, their proximal ends being always hidden by the

* This canal is also known as the “ Dorsal” canal, and as the “ Celiac ” canal.

MORPHOLOGICAL PART. 101

orals, and when these are wanting, by some of the interambulacral plates ;
or by both, in which case only small portions of them are seen near the arm
bases. In the Fistulata, the disk ambulacra are either altogether tegminal,
or their ends are covered by the orals. In the Ichthyocrinids, so far as
observed, and in recent Crinoids, they extend to the mouth, whether orals
are represented or not; but while in Tuzocrinus (Plate III. Fig. 11) they
are in the same plane with the orals, and are attached to them laterally,
in recent forms, in which the orals are opened out, they are deeply in-
serted between the interambulacral plates, so as to be almost obscured.

The disk ambulacra of the Camerata, if tegminal, form a component part
of the tegmen, being suturally connected with the interambulacral plates, and
with the orals. In the Cyathocrinidx, however, and probably in other Fis-
tulata, they rest upon large interradial plates, and between the small margi-
nal pieces which cover the surface of the latter. In the Ichthyocrinide and
recent Crinoids, they are separated by minute interambulacral pieces.

The ambulacra of the Camerata rarely have any side pieces, these being
represented, so far as known, only in Megistocrinus (Plate XLVII. Figs.
7 and 8a, 6), in Cactocrinus (Plate LVI. Figs. 7 a, 0), and in Lyriocrinus
(Plate XI. Fig. 4c). They are present, however, in most Fistulata, but
absent in the Larviformia. |

That the covering pieces in the disk of Cyathocrinus, as suggested by
several writers, were movable, so as to expose the food grooves, seems to
us improbable, although there is no serious objection to it from a morpholo-
gical point of view ; but the perfect preservation of the plates in so many of
our specimens seems rather to indicate that they were rigid. They may
have been movable in groups in which the mouth is opened out, but where
it 1s closed they were probably rigid throughout the disk.

In some of the Camerata in which the primary arms are developed into
tubular appendages, and secondary arms are given off at the sides, as in
Eucladocrinus (Plate LX XII. Fig. 3, Plate LXXIV. Fig. 4), and Steganoerinus
(Plate LXI. Fig. 1 e), the covering plates of the main arms are almost rigid
to the full length of the ray, and only those of the side arms and their pin-
nules were movable. But it must be remembered that these appendages are
practically extensions of the calyx.

Subtegminal ambulacra, so far as we know, occur only among the
Camerata and Larviformia. In the former there are frequently along the
inner floor of the tegmen deep grooves or ducts, which are formed either by

102 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

a folding of the test or a thickening of the plates, and which proceed from
the middle of the floor to the arm openings (Plate V. Figs. 13, 14, 15, 16,
and 17). Within these grooves are lodged the ambulacra, which are repre-
sented by a skeleton of radiating tubes, following the inner surface of the
disk (Plate V. Figs. 1 and 10; Plate IV. Fig. 8). The tubes are composed
of four rows of plates, two below and two above, both alternately arranged,
the former probably representing subambulacral pieces, the latter covering
plates. The skeleton has never been found completely preserved, but
enough is shown to indicate that the tubes do not extend out to the centre,
but meet in an annular vessel surrounding the mouth. This at least seems
to have been the structure of Macrocrinus verneulanus, in which an almost
circular vessel has been observed beneath the centre of the disk at some
distance from the inner floor (Plate V. Fig. 8). No ambulacral tubes are
attached to it in the specimen, but it has five openings in a radial direction,
which evidently communicated with the ambulacral vessels. The ring is
rather large, and is placed around the contracted upper part of the con-
voluted organ, which is also preserved in the specimen.

The direction of the ambulacral tubes and _ their branching is well
observed in natural casts, in which, after the calcareous parts are removed,
the ducts of the tubes are represented by filiform elevations upon the
surface (Plate IV. Figs. 1, 2, 3, 4, 5), sometimes even showing impressions
of ambulacral pieces. It also appears from these casts that the ambulacra
in some cases rested directly against the tegmen, and in others lay at a dis-
tance from it, only touching the test at the arm bases. The latter was
undoubtedly the case in the interesting specimen of Platyerinus (Plate IV.
Fig. 6), in which the ambulacral plates are clearly marked near the margins
of the disk, while no traces are found of their inner portions. If the ambu-
lacra had touched the inner floor, the delicate markings of the disk plates
would not be in sight, but instead of them traces of the tubes would
appear upon the surface. This is corroborated by the cast of Dorycrinus
(Plate IV. Fig. 5), in which the ambulacra are visible to the outer edges of
the orals, but disappear underneath them. Also in the beautiful specimen
of Cactocrinus proboscidalis (Plate V. Fig. 10), where the tubes are removed
from the floor,* and in Teleiocrinus (Plate IV. Fig. 1), and in Cactoerinus glans

* Neumayr, who knew this specimen from Meek and Worthen’s figure, expressed the opinion that a
settling of the tubes probably took place after the death of the animal. He based this Opinion upon the
structure of the casts, in which he supposed the ambulacra were always exposed at the surface, which, as we
have stated, is by no means the case.

MORPHOLOGICAL PART. 103

(Plate IV. Fig. 8). That they were attached to the tegmen in many of these
Crinoids, and probably in the majority of them, is also suggested by the
presence of the so-called radial dome plates.

The name “ radial dome plates” was given by us to a set of large plates
in the tegmen, radially disposed, and occupying the regions between the
orals and the arm bases. ‘The plates are generally larger than the surround-
ing ones, and quite frequently nodose. They were regarded by us, and also
by Dr. P. H. Carpenter, until quite recently, as the actinal representatives of
the radials, but later investigations prove they are highly differentiated cov-
ering pieces. The plates are either followed by two series of regular cover-
ing pieces, and pass out from between the angles of the orals, or they are to
a certain extent isolated, surrounded by other plates, and succeeded by simi-
lar plates of higher rank. The former is the case in most of the Platycrinide
and Hexacrinidee, the latter among the Actinocrinidse and Rhodocrinidex with
subtegminal ambulacra. That the plates in the former case are simply cover-
ing pieces, is readily perceived by examining those species in which the
plates are but little disturbed. Taking Platycrinus and Dichocrinus, we find
in both genera certain species in which two series of small, almost regularly
arranged, alternating pieces pass out from the orals to the arms. Such is the
case in Platycrinus synunetricus (Plate LXIX. Figs. 1 4, c), in Dichocrinus poly-
dactylus (Plate LX XVII. Fig. 10), and in D. lachrymosus (Plate LXXVII.
Fig, 2c). Similar plates under similar conditions also occur in the Silurian
- Marsupiocrinus (Plate VIII. Fig. 15, and Plate LXXV. Figs. 16 4 and 18), and
among Silurian genera of other groups. There are no large plates next to
the orals, and hence no radial dome plates, unless they are represented by
the small proximal plates. From this structure to that of Platycrinus dis-
coideus (Plate LXVI. Fig. 10 4), and P. Halli (Plate LX XII. Fig. 7 a), there
is but a short step. The plates in question are comparatively larger, espe-
cially the proximal ones, and arranged alternately, although not so regularly
as in the former species. In Plalyerinus burlingtonensis, however (Plate L.XIX.
Fig. 3c), and P. Yandelt (Plate LXVIII. Fig. 3c), there is generally a large
plate followed by smaller ones, and the alternate arrangement of the plates
actually commences at the arm bases. If we had only the latter species, we
might perhaps be justified in regarding those proximal plates as independent
structures; but comparing them with those of other species in which the
arrangement is more regular, it becomes evident that they are all nothing

104 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

but covering pieces, which gradually in geological time changed their
character. |

The “radial dome plates” of the Actionocrinide# and allied forms are
generally larger than any of the surrounding plates, often nodose, and some-
times extended into long spines. They are not followed immediately by
covering pieces, as already stated, and are placed at some distance from
the orals, — occupying in the simpler forms with but two arms to the ray
almost the outer margins of the tegmen (Agaricocrinus), — directly over the
point at which the bifurcation of the ambulacra takes place. When there are
four arms to the ray, they are removed relatively further inward, and are
followed by two similar but smaller plates of higher rank. But when there
are three arms to the ray, there is only one such plate, which is directed to
the side where the bifurcation is, the opposite side of the plate being followed
by the regular covering pieces of the arms. |

From this structure we may infer that the so-called radial dome plates
with subtegminal ambulacra are axillaries, and if they represent, as we have
reason to believe, modified covering pieces, that they are the plates from
which the ambulacra bifurcate. In this view it is quite suggestive that the
axillary plates of the ambulacra are frequently protuberant. In Lucladoeri-
nus millebractatus (Plate LX XII. Fig. 1), they are all along the main arms
strongly nodose, and if the ambulacra of this species had been covered by
other plates, the tips of the axillaries naturally would project above them
and be exposed upon the disk. In this way the radial dome plates may have
originated, so that afterwards the upper portions developed to larger size, and
finally become independent plates. This explanation seems to us most prob-
able, and it was favorably received by Carpenter.

The Paleontological evidence indicates that in the earlier Camerata, as in
the young specimen at some time, the ambulacra were exposed upon the
disk. In most of the Silurian forms they took part in the tegmen, and their
covering plates, as a rule, were more regular in their arrangement than in
those of later epochs. In. the Carboniferous, with the exception of the
-Platycrinide, Hexacrinide and Acrocrinide, the ambulacra are almost
exclusively subtegminal, and the whole disk assumes that extravagant
form which led at one time to the belief that it represented an entirely
different structure.

MORPHOLOGICAL PART. 105

Til. SUPPLEMENTARY PLATES.

A. The Distribution of the Plates, and ther Relations in the Different Groups.

The supplementary plates comprise all limestone particles between the
basals and orals, and intervening between the rays and their subdivisions.
They are divided into interradial, interaxillary, and anal plates. The inter-
radial plates, comprise as a general term all plates between the basals and
orals, interradially disposed. Some of them are distinguished as inter-
brachials, others as interambulacrals. The interbrachials are confined to
the dorsal cup. The interambulacrals occupy the spaces between the am-
bulacra. The interaxillaries, consisting of the interdistichals and inter-
palmars, are located within the axils of the second, third, and succeeding
orders of brachials respectively. The anal plates are restricted to the
posterior interradius supporting the anal tube. Another system of small
plates occurs in the Acrocrmide, where they form a wide belt inter-
mediate between the basals and radials.

In nearly all Crinoids, recent and fossil, in which the free arms do not
start directly from the radials, the lower arm joints are incorporated into the
calyx, either by soft tissues or by means of plates. The latter are exceed-
ingly variable in form and character, being in some groups well developed
and rigid ; while in others they are irregular, ill-formed pieces, or mere lime-
stone particles, resting within soft tissues. The great variation observable in
the structure of the plates among different groups led to the belief that the
rigid and regularly arranged pieces, which are so characteristic of the Came-
rata, did not belong to the same system of plates as the irregular, small
pieces which unite the rays of recent Crinoids; and Dr. P. H. Carpenter
applied to the former the term “calyx” interradials, as opposed to the
interradial plates of the “disk.”

A somewhat similar distinction was made respecting the plates which form
the ventral pavement. The heavy, rigid pieces of Palzeozoic forms were
called “vault” plates; and the small, irregular pieces of later and recent
Crinoids, “ perisomic”’ or “disk” plates. The term “vault” was generally
applied in cases where the mouth and food grooves are permanently closed,
and “ disk,” where the mouth and food grooves are open.

In the Camerata, the interbrachials are nearly always arranged on a

definite plan, and are stout, large, and united by close suture, making the
3 14

106 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

whole test, to the bases of the free arms, extremely rigid. The interbrachial
plates of the regular sides generally commence with one plate, which in most
families rests upon the radials and between the costals. It is usually fol-
lowed by two in the second row, and two, three, or four, according to spe-
cles, In any succeeding ranges there may be. The posterior interradius is
frequently wider, and divided vertically into two halves by a continuous
or interrupted series of anal plates; but it may be constructed like the other
four. In the Platycrinide and Hexacrinidex the first row consists of three
pieces, which are for the most part neither entirely interbrachial nor entirely
interambulacral. In the Rhodocrinide the first plate interradially disposed
goes down to the basals, thus separating the rays to their full length. This
first plate is therefore not strictly interbrachial in position, as it lies below
the horizon of the lowest brachials ; nevertheless it unquestionably belongs
to the same system of supplementary plates, which in this group extend
down to a position between the radials. There is some variation in the
extent to which the radials are parted by these intervening plates. In some
species of the Rhodocrinide, exceptionally, the radials are only separated to
half their length, the variation occurring among different specimens of the
same species, and even in different areas of the same specimen. We find it
convenient to call these plates interposed between the radials “ first interra-
dials” where it will avoid circumlocution. The interbrachial and interaxillary
plates of the Reteocrinidx, contrary to those of all other Camerata are ill-
formed, and irregularly arranged.

The interradial plates occupying the ventral side of the calyx are as rigid
as those of the dorsal side, but are as a rule less regularly arranged. They
either extend up to the orals, or, when these are not represented, and the
ambulacra are subtegminal, they cover the whole tegmen, leaving no opening
except the anus.

At the inner floor of the teemen, we find in most of the Actinocrinidx
and Batocrinidz shallow grooves or open galleries, which are well shown by
the natural casts figured on Plate IV. Figs. 1, 2, 4,5, 6, and 7, in which they
are represented by the elevations. These galleries pass out from near the
centre to the arm bases, and lodge the ambulacral tubes. Alongside of them,
and sometimes covering them, there is frequently in both families — but, so
far as observed, only in certain genera — what appears to be a second integu-
ment (Plate V. Figs. 13, 15, 16, and 17), lying parallel to the inner floor,
which was formerly supposed to represent the ventral disk. The outer

MORPHOLOGICAL PART. 107

integument was regarded as a structure sui generis, to which the term “vault”
was applied. ‘The inner integument appears at first sight as if composed of
independent, ill-formed pieces; but on closer inspection it is found that
these so-called plates are extensions from the plates above, and continuous
with them. ach lower part is connected with the corresponding upper one
by small surfaces or pillars, and joining by its edges with other like plates,
leaves open spaces or meshes along the sides. The inner portions constitute
a kind of internal lining or network, extending from the first costals and first
interbrachials uninterruptedly to the margins of the orals. In some speci-
mens only the pillars are preserved, the lateral extensions of the plates being
wanting ; while in others the floor is almost entirely smooth. The latter is
the case in Caclocrinus proboscidalis (Plate V. Fig. 10); while in Teleiocrinus
rudis (Plate V. Fig. 16), and in the specimen of Doryerinus (ibid. Fig. 18), the
grooves are formed into well defined tunnels. <A further indication that there
were probably two integuments in some of the Camerata at least, seemed
to be presented by the ventral structure of Stphonocrinus armosus from the
Niagara group (Plate XIX. Figs. 3 a, 6,c). This species, so well known from
natural casts, has a large, trumpet-shaped, subtegminal anal tube, which
crosses the mouth, overlies the upper ends of the ambulacral tubes, and is
continued subtegminally all the way to the anterior side of the calyx, even
beyond the arm regions, where it bends outward. The case is best illus-
trated if we imagine the disk of a recent Crinoid, with an anal tube like
that of <Antedon regalis (Chall. Rep. on the Comat., Plate XLVI. Fig. 2),
extended all the way out to the arm bases of the anterior ray, and covered
by a vault.

It seemed hard to account for the facts presented by these cases, except by
the presence of two distinct structures covering the body cavity; and upon
these specimens principally we formed the opinion, in the first instance, that
the Camerata had a vault and a subtegminal disk, and that the vault was
a structure without a parallel in recent Crinoids. The evidence appeared
to be conclusive that the disk was subtegminal, in some groups at least, and
this, which had been generally acknowledged by leading authors, led us to
believe that in all Camerata the disk was roofed over by a vault.. In fact
this conclusion seemed to be corroborated by the nature of the plates, which,
although varying considerably in size and number, are arranged in all these
Crinoids on the same general principle, forming in all of them a compact,
rigid test, with the mouth and food grooves perfectly closed.

108° THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Carpenter * held the same opinion as to the vault of the Actinocrinide,
but he believed that the “vault” of a Platycrinoid “ corresponds collectively
to the orals, interradials, ambulacral and anambulacral plates of Neocri-
noids.” He agreed with ust that the calcareous network beneath the
“vault” of an Actinocrinus “corresponds to the limestone particles on the
surface of the internal casts, and represents the anambulacral plates de-
veloped in the perisome of recent Crinoids.” He also admitted “the com-
plete resemblance between the ventral perisome of a recent Crinoid and the
upper surface of the body beneath the vault of an Actinocrinus.’ “The vault
and ventral disk,” he said, ‘‘are to my mind entirely distinct structures.”
Of the vault, he said further (p. 172): “TI believe the oral or actinal system
forming the vault of Actnocrinus to have been developed on the left larval
antemer, in exactly the same way as the apical or abactinal system is
developed on the right; but the oral system, instead of being limited to five
oral plates, as in Neocrinoids, reached a very extensive development, so that
in its completest form it represents such a parallel to the apical or abactinal
system as is to be met with in no other Crinoid.” From these passages and
others in the Challenger Report, it appears that Carpenter, as well as we,
supposed that in Actinocrinus all plates of the calyx up to the arm bases were
abactinal, and all constituting the ventral side actinal; not only the orals
and radial dome plates, but also the so-called interradial dome plates or
interambulacral pieces.

‘We retained the above mentioned opinion until 1881; but afterwards
our views were materially changed respecting the interradial dome plates,+
which we no longer regarded as actinal structures, but took to be con-
tinuations of the interradial plates of the dorsal cup, and as fundamentally
identical with them. In considering the matter in the first place, we had
not overlooked the fact that in many of these Crinoids, throughout different
groups, the covering plates of the ambulacra are exposed at the surface, and
as such would form a part of the “ vault.”

It is a striking fact, in the Crinoids as elsewhere, that some characteristics
which are of the greatest importance from a morphological point of view,
prove to be of comparatively little value for classification. This is the case
in a marked degree with the ambulacra of the Platycrinide and Actino-
crinidx, which are found to be tegminal and also subtegminal. In the Platy-

* Chall. Rep. Stalked Crinoids, pp. 172-180. |

+ Chall. Rep. Stalked Crinoids, pp. 165, 166.
+ Revision, Part III. pp. 16-27 (Acad. Nat. Sci. Phila., pp. 238-249).

MORPHOLOGICAL PART. 109

crinidz, the covering pieces are generally exposed in the calyx, while in the
Actinocrinids they are as a rule hidden from view. But occasionally the
opposite is the case, and even among species of the same genus. Aclinocrinus
stellaris, from Belgium, has well defined covering pieces passing out from the
outer edges of the orals; while almost every other species of Actinocrinus has in
place of them radial dome plates of the first, second, and third order, accord-
ing to the number of bifurcations in the calyx. Physetocrinus, which is but a
modified Actinocrinus, has in some species orals and radial dome plates; while
in others the whole ventral surface is covered with small, irregular pieces.
In Actinocrinus multiradiatus, the entire tegmen consists of only a few unusu-
ally large interradial plates, which interlock with those of the dorsal cup.
But the interradials in most of the Actinocrinide pass insensibly into the
tegmen, there being no dividing line; while in Batocrinus generally, but
not always, the interradials of the dorsal side are distinctly separated from
those of the ventral side by the arching brachials, — a structure which led us
at first to suppose that the plates of the two hemispheres were morphologi-
cally distinct.

Similar variations occur among the plates of the tegmen in the Platy-
erinide and Hexacrinide. In some 6f their species the pavement is made up
entirely of massive plates, in others of comparatively thin pieces; while in
still others the ventral surface is occupied almost exclusively by the orals.
In both groups it is absolutely impossible to draw a dividing line between
interbrachials and interambulacrals. The plates constituting the first row,
which generally consist of three pieces, are peripheral and partly interam-
bulacral, and those of the succeeding rows strictly ventral. The plates of the
second and higher rows, when such are present, interlock with those of the
first row, like the interradial plates of the dorsal cup in an Actinocrinus.

The condition of the ventral pavement in the Melocrinidxe, Rhodocrinide,
and Thysanocrinide is similar to that in the Actinocrinide. Their lower
interbrachials are definitely arranged, and there is no line of demarkation
between the plates of the two hemispheres, except that produced by the
arms, which pass out between them. In the Reteocrinide, as in most of the
other Silurian Camerata, the whole ventral surface is covered by minute,
irregular pieces, and similar plates, with a few somewhat larger ones scattered
among them, are interposed between the rays from the basals up.

It seems to us perfectly clear from the structure that all interradial and
interaxillary plates, not only in the Camerata, but also in all recent and fossil

110 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Crinoids, where they exist, are auxiliary pieces, which increase by multipli-
cation in the growing animal, filling up spaces between the rays and their
subdivisions. They increase primarily in an upward direction, but partly by
intercalation, secondary plates being introduced between the primary ones.
It is owing to the intercalation of these secondary pieces that the arrange-
ment of the interradial plates in the upper rows is less regular than it might
otherwise be. In the simpler forms such pieces are wanting, or only occur
close to the arm bases. In some species, however, they are quite numerous
in the dorsal cup, as well as in the tegmen, and in the Reteocrinide they
constitute the greater part of the interradial and interaxillary areas. In this
family small pieces continually formed in large numbers in the growing
Crinoid along the margins of the radials and brachials, and between the
primary interradials, so as to isolate these from their fellows and from the
plates of the rays (Plate IX. Figs. 1 e, 5c). |

The interradial plates, as already stated, are continued into the tegmen.
This may be readily perceived in species which have but one or two bifurca-
tions in the calyx; but in the more complex forms the primary structure is
frequently obscured by the introduction of secondary pieces, giving the im-
pression that the plates of the two hemispheres were structures morpholo-
gically independent. Looking at a specimen of Sérotocrinus, with a broad
flanging rim, its hundred and more arms crowded around it, and its thousands
of minute “vault” plates, growing smaller outward, and not connected with
the interradials of the dorsal side, it is not surprising that such an impression
should be created.

To understand the structure of Strotocrinus, we may refer to that of the
allied genus Steganocrinus, in which in like manner the arms branch off alter-
nately like pinnules from the two main divisions of the rays; but while in
Strotocrinus the lower parts of the arms are incorporated into the calyx, and
form a continuous rim from which the free arms start off, in Steganocrinus
the two divisions of the rays, bearing their small alternate arms, remain per-
manently free, and extend out laterally as tubular appendages of the calyx.
It is now very significant to find that in Steganocrinus the interradials of the
dorsal cup meet those of the tegmen in such a manner that it is absolutely
impossible to draw a line between the plates of the two hemispheres ( Stegano-
crinus pentagonus, Plate LXI. Fig. 30). This case is the more instructive,
because Sfeganoerimus, with its free arms, may be regarded as representing
an early stage in the developmental history of Strotocrinus.

MORPHOLOGICAL PART. Sh

A structure similar to that of Steganocrinus is found in all Camerata in

which the arms are free from the distichals up ; and from this condition all
gradations can be traced to the complex structure of Strotocrinus. The plates
of the dorsal cup and those of the tegmen are undoubtedly parts of one ele-
ment; and although they are introduced respectively at the actinal and
abactinal sides of the calyx, the plates of the one side cannot be regarded
as strictly abactinal, nor those of the other as actinal.
Referring again to Platycrinus, Carpenter * said that the series of inter-
radials found in the peripheral portion of the vault (tegmen)— by which he
meant the zone between the proximal dome plates (summit plates) in the
centre and the calyx interradials (of the dorsal cup)— belong to the same sys-
tem of interradial plates as the single large interradial in Oyathocrinus. And he
continues: “I do not myself think that the vault of a Platycrinite was exactly
of the same nature as that of an Actinocrinite, 7. e. that it covered in the whole
of the visceral mass and the ambulacra on its upper surface. For if the
alternating dome plates represent the covering plates of recent Crinoids, as
Wachsmuth suggests, then all the periphery of the dome, outside the apical
dome plates (orocentral and orals), must be the real ventral surface of the
body, and not a ¢egmen calycis as in Actinocrinus.” And in alluding to the teg-
men ot Marsupiocrinus, he said: + “I have a very strong impression that the
so-called vault of this genus is really the strongly plated ventral perisome, in
the centre of which the remains of the orals (apical dome plates) are perhaps
to be found. I cannot see any such essential difference between it and the
plated disk of Pentacrinus Wyville-thomsoni or of many Antedons (Plate XVII.
Fig. 6; Plate LV.) as would lead to the supposition that the homologue of
the latter is to be sought for beneath the vault of Marsupicerinus.” He then
alluded to the closure of the’ mouth, and to the covering pieces of the ambu-
lacra, which may have been immovably closed down over the food grooves,
saying: “They were thus converted into tunnels, but were still ‘external,’ in
the sense of not being covered by a ‘tegmen,’ as those were which formed
the tubular skeleton beneath the vault of the Actinocrinids.” That is to
say, In short: Vault and disk are entirely distinct structures; and the
ventral surface of one Palsxocrinoid represents a disk because the am-
bulacra are external, while that of another is a vault because they are
subtegminal.

* Chall. Rep. Stalked Crinoids, p. 178.
+ Chall. Rep. Stalked Crinoids, p. 176.

ab THE CRINOIDEA CAMERATA OF NORTH AMERICA.

We have already pointed out that the covering pieces are exposed not
only in the Platycrinidz, but frequently also in other families of the Came-
rata, — exceptionally even in the genus Actinocrinus. If it were true that in
Crinoids in which the disk ambulacra are subtegminal, the integument which
covers them is a “ vault,’ and, on the contrary, in those with ambulacra ex-
posed, or “external,” a disk, it seems to us that the two forms should be
separated as distinct orders, and it would follow that our present classi-
fication of the Crinoids is arbritrary and worthless. These ‘considerations
produced in our minds a firm conviction that the integument in both cases
must represent the same thing, being either a vault or a disk, — the plates
either all vault pieces or all perisomic.

In some species of Platycrinus the ambulacra make their appearance, not
at the margins of the summit plates, but at some point intermediate between
the orals and the arm bases, from beneath the upper ring of the interradial
plates. In these species, applying Carpenter’s interpretation, the lower inter-
radials would be perisomic, for they expose the ambulacra; but the upper
ones vault plates, because they do not. In Péerotecrinus, the last survivor of
the Hexacrinide, a very highly differentiated form, the tegmen, according to
Carpenter,* “seems to have had a closer resemblance to that of Actmocrinus
than is the case in most Platycrinidex, for it had radial dome plates of the
first, second, and even occasionally of the third order.” In other Platycri-
nidz the oral system, he says,f sooner or later came in contact with the
alternating series of ambulacral plates. “There was a membranous disk,
the radial regions of which were traversed by the ciliated food grooves
beneath the ambulacral skeleton above ; while the interpalmar regions sup-
ported the interradial plates of the vault.” Further on he explains that
the vault of the Platycrinide is not a true vault, or tegmen calycis, like that
of the Actinocrinide, but corresponds collectively to the orals, mterradials,
ambulacral and anambulacral plates of Neocrinoids; contrary to the vault
of Actinocrinus, which not only covers in the food grooves themselves, but
also their skeleton of alternating plates, together with the origin of the
ambulacra and the plated interpalmar areas of the disk. .

We never imagined that Platycrinus had anything but a membranous
disk, which, we thought, was continued underneath the interradial plates
all the way to the arm bases. Neither did we suppose it had any further
plates above the food grooves than the alternating pieces; nor that the

* Chall. Rep. Stalked Crinoids, p. 177. + Ibid., pp. 179-180.

MORPHOLOGICAL PART. 113

latter were true vault plates, as Carpenter inferred we did. We held that
while in the vault of the typical Acéimocrinus the interradial dome plates
meet: over the ambulacra, in Platycrmus these plates opened out so as to
expose the covering pieces, and that these were gradually incorporated
into the vault. In a typical Platycrinoid, the covering pieces are so
modified as to lose almost their original character, being as large and
nearly as heavy as the surrounding plates, and they are united with one
another, as well as with the latter, by close suture. In some of the later
Platycrinide they even may have been separated from the food grooves,
for in the internal casts they left no impressions; while in casts of Actino-
crinus from the same localities, and in casts of certain Silurian Platycrinide,
the outlines of the ambulacra are generally sharply delineated (Plate LXXV.
Fig. 14).

Carpenter probably supposed the ventral structure of the Melocrinidx
and Rhodocrinide to be in the same condition as that of the Actinocrinidee
and Platycrinide respectively, that is, a disk when the ambulacra are ex-
posed, a vault when they are concealed. He alluded to Glyptocrinus in
connection with the Reteocrinide and Ichthyocrinide, in all of which the
ventral pavement is composed of an immense number of very minute,
irregularly arranged pieces. In the Ichthyocrinide these plates are trav-
ersed by regular rows of alternating pieces, passing out from the oral centre
to the arms; in the two other families, however, such alternating plates,
when present at all in the tegmen, are found only close to the arm bases.
Carpenter says respecting these groups,* “ I venture to think that in the case
of Glyptocrinus, Reteocrinus, Xenocrinus, and also of the Ichthyocrinide, the re-
semblance to the Pentacrinide, Apiocrinidw, and Comatule, is such as to
leave no reasonable doubt that the so-called vault of these Paleeocrinoids is
homologous with the ventral surface of the body in the Neocrinoids.” This
is true enough as to Zuaocrinus and Onychocrinus, and probably the Ichthyocri-
nid generally, in which mouth and food grooves are exposed, as we have
found out from actual observation; but in the case of Glyptocrinus and Reteo-
erimus, there is nothing to prove it beyond a superficial resemblance of the
plates. Carpenter’s argument loses much of its force, considering that
among the Actinocrinidse: within the same genus some species have large
plates, others very small ones, and the evidence seems rather to prove
that either these plates are all disk plates, or none of them are.

* Chall. Rep. Stalk. Crin., p. 185.
15

114 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Essentially different is the ventral structure of the Fistulata, which have
no interradial plates in the dorsal cup, the anal piece excepted; but those
plates are extensively developed in the tegmen. Four of the interambu-
lacral spaces are raised but little above the level of the arm bases; while the
posterior area is extended abruptly upward, and formed into a sac or tube of
various forms, frequently rising beyond the tips of the arms. This sac,
which may be regarded as a greatly extended anal area, and probably
lodged a large portion of the visceral mass, must not be confounded with
the anal tube of the Camerata, which contains simply the rectum. The
sac is tubular, balloon-shaped, spiral, or club-shaped, and is generally com-
posed of longitudinal rows of hexagonal plates, which are often pitted at
their sides, or perforated by pores.*

The structure at the four other sides of the disk is rarely observed ex-
cept in the Cyathocrinidse, in which it was probably more substantial than in
the other families. In Cyathocrinus it 1s well shown in our figures on Plate
Ill. Figs. 1, 2, 3, 4, 6, 7, 8, to which we drew attention in our chapter on
the orals. There are six plates, interradially disposed, resting against the
inflected upper edges of the radials, their lateral margins covered by the
ambulacra. Four of them are larger, cordiform, and of equal size; the two
others, which lie at the posterior side, are quite narrow, and enclose a large
perforated plate to which we have applied the term madreporite. The sur-
faces of the four larger plates in perfect specimens are roofed over by num-
erous delicate pieces; while the perforated plate is completely exposed
to view.

As to the relations of these plates various conflicting views have been
expressed. Wachsmuth, in 1877, supposed that the plates collectively con-
stituted a kind of consolidating apparatus, like that described by Roemer
and others in Cupressocrinus. We afterwards, supposing that there were five
plates, suggested that they were structurally identical with the deltoids of
the Blastoids, which at that time were regarded as homologous with the orals
of the Crinoids. Similar views were expressed afterwards by Carpenter,

* Mr. Bather is of the opinion that the ventral sac of the Fistulata is not perforated, but only pitted
(Geol. Magazine, May, 1891, p. 228, and elsewhere). This may be true as to Cyathocrinus, Euspirocrinus,
and possibly the Cyathocrinide generally, in which very likely the madreporite performed the functions of the
tube-pores ; but we have the most complete evidence that among the Poteriocrinide, in many cases, the pores
pass through the test. In some specimens in which the lateral edges of the plates were exposed perfectly
free from the matrix, we have been able to trace the ducts of the pores to the full depth of the plates. They
are well shown on Plate VII. Figs. 24, 5, 7, 8,9. That the openings are not visible in most of the speci-
mens is due to their small size and probably also to the mode of petrifaction. )

MORPHOLOGICAL PART. 115

Zittel, and Neumayr, who all regarded the plates as orals. Plausible as this
theory appeared to us at first, it involves serious morphological difficulties ;
and in 1883, on discovering that the plates consist of seven pieces instead of
five, we abandoned it, in which we were followed by Carpenter. Since then
we have taken the plates to be interradials, although with some hesitation,
for they are not interbrachial, nor, strictly speaking, inter-ambulacral, but in
part sub-ambulacral, and sub-tegminal. In their position they resemble
the first interradials of Plalycrinus, but the ambulacra of that genus rest
against the edges of the plates, and only the covering pieces are exposed.
In the Cyathocrinide, not only the ambulacral plates, but also the ambulacral
vessels rest upon solid plates, and the small marginal plates on top of these
plates sustain toward the side- and covering-pieces the same relation as the
interradial plates of the Platycrinids toward their covering pieces.

The presence of three plates at the posterior side, as against one at the
other four, would seem to indicate that they may be homologous with the
first row of interbrachials of the Batocrinide ; but upon closer examination
it appears that the two structures are not exactly parallel. We have no
doubt that also in Cyathocrinus, as in the case of Batocrinus, the posterior
plate is broken up into two pieces by the middle plate; but this plate in
Cyathocrinus is a madreporite, while that of Batocrinus is a supplementary
anal. ‘The former constitutes the uppermost plate of the posterior inter-
radius, being separated from the first anal plate by the full length and
depth of the sac; the plate of Batocrinus, however, which rests directly
upon the anal, represents the lowest plate of the area.

Obscure also are the relations of the small marginal plates, which in
Cyathocrinus overlie the larger ones, and which occur only at the four smaller
sides of the disk, leaving the surface of the madreporite at the fifth side ex-
posed to view. The only plausible explanation we can find for this structure
is that these plates represent the higher disk plates, which for want of space
overlapped, and gradually covered the larger ones; while those of the pos-
terior side, instead of overlapping, were carried upward, and formed into a
sac or tube.

The large interradial plates of the Cyathocrinids apparently have close
affinities with the deltoids of the Blastoidea, and Carpenter and Bather*
proposed to apply also to the plates of the former temporarily the term
“deltoids.’ The plates of both groups rest upon the radials and support

* Ann. and Mag. Nat. Hist., 1892, p. 64.

116 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the orals; but while those of the Cyathocrinide enclose a madreporite, those
of the Blastoids enclose an anal piece. The conditions are thus not exactly
alike, and we do not see why that term is any more appropriate than “ in-
terradials ”” — a term which has the advantage of being more general,

In the Hybocrinidew the posterior side of the disk is less elevated than in
the Cyathocrinide, rising but little above the level of the other four sides.
The ambulacra are tegminal, and apparently rest upon the lateral margins
of the four large interradial plates. There are no orals, the median portions
of the disk being occupied by large covering pieces.

The ventral pavement of the Anomalocrinide, which we examined in
a fine specimen from the Museum of Comparative Zodlogy, differs essentially
from that of the two preceding families. It consists of rather large, moder-
ately thick, irregular pieces, five or six deep, which decrease in size toward
the centre and cover the peristome; no orals being distinguishable. The
outer of these plates rest against the large incurved limbs of the radials,
forming a wide and deep sinus for the reception of the ambulacra, which are
on a lower level than the other disk plates, and in the Cambridge specimen
of a different color, and thereby readily recognized.

The tegmen of the Poteriocrinide has never been found in perfect pres-
ervation. We hoped to find it by dissecting a number of finely preserved
specimens, but the sacrifice was only rewarded by finding in a single instance
a few small, scattered plates; from which we conclude that the covering was
of very fragile construction. The form and size of their ventral sac is ex-
tremely variable; extending in some cases beyond the tips of the arms, in
others consisting of merely a short cone. In some of the genera it is tubu-
lar, in others club-shaped ; in some balloon-shaped ; in some even spiral, the |
whorls of the coils either united or free; but in all cases, so far as we know,
the plates are arranged in vertical rows, which sometimes diverge at intervals,
and apparently in all of them the edges of the plates — not their substance
— are perforated by pores or clefts.

A porous sac is also found in the Belemnocrinida, and probably exists in
the Heterocrinidx, but nothing is known of the other disk plates in these
families. |

In the Encrinide, according to Wagner,* the ventral disk rises to about
the height of the second costals, where it contracts abruptly to one half. its
diameter at the base, and is surmounted by a small cone. The peripheral

* Zeitschr. d. Deutsch. Gesellsch., 1887, pp. 822 to 828.

MORPHOLOGICAL PART. 117

part consists of small limestone particles, or irregular plates, and was evi-
dently flexible ; while the conical part, which is composed of larger pieces,
appears to be almost rigid. Nothing is said about ambulacra, which were
probably not visible in the specimen. That the cone represents a short
ventral sac, and that the affinities of the Encrinide are with the Fistulata,
and not with the Apiocrinide and other Neozoic Crinoids as heretofore,
supposed by Miller, Miiller, Zittel and Carpenter, is clearly shown from
Wagner’s description.

Among Apiocrinide de Loriol observed the tegmen in Apiocrinus roissy-
anus,” a species with large, massive plates interposed between the rays, and
in which the plates of the cup gradually pass into the tegmen, which consists
of rather heavy plates. The interbrachial plates were regarded by Carpenter
as “calyx ”’ interradials, 7. e. homologous with the interbrachials of the Acti-
nocrinidx, the plates of the tegmen, however, as “ disk” plates, — a position
which was controverted by us.t We asserted that if those plates were
“calyx” interradials, they should be followed by a “vault;” but if the
tegmen was a disk, then the plates between the rays also had to be con-
sidered as disk plates. We came to this conclusion upon ascertaining that
the plates of the tegmen form a continuation or extension of those in the
cup. The plates of the two hemispheres in most cases pass imperceptibly
from one into the other, and have the most intimate relations. |

Apiocrinus is not the only Neocrinoid genus as to which there have been
doubts respecting the homologies of the interbrachial plates. Guettardicrinus
is morphologically in exactly the same condition, and the recent venus Thau-
matocrinus has five large plates interposed between the radials, resting upon
the basals, and followed by very minute, irregular pieces, which gradually
pass into the tegmen. Also in many of the Ichthyocrinide the plates be-
tween the rays are large and heavy; while those of the tegmen are ill-formed
and unusually small. Glyptocrinus has minute, irregular pieces in the teg-
men, and well defined and regularly arranged plates in the cup. In all these
cases Carpenter took the larger plates to be “ calyx interradials,” but called
the others “disk plates,” although the former occupy relatively the same
position as the smaller ones, and as the disk plates of the Comatule, Calamo-
crinus, and the Pentacrinide. Our recent studies show plainly that neither
the condition of these plates, nor the presence or absence of the ambulacra

* Paléont. Franc., lre série ; Anim. Invert., Crinoides, p. 272.
{ Revision, Part ITI., pp. 63, 72, and 137. \

118 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

in the tegmen, enables us to discriminate between perisomic and vault pieces;
and this led us to inquire whether such a distinction actually exists in any
group.

After 1t was demonstrated that the ventral surface of Taxocrinus is a true
disk, we became convinced that our views respecting vault and disk would
have to be modified as to other groups also, or be altogether abandoned. The
latter was done in 1892, in a paper on “The Perisomic Plates,” * in which
we endeavored to show that the so-called “vault’’ of the older Crinoids
is a modified disk. This interpretation has since been accepted by Agassiz,
Carpenter, and Bather, who agree that the use of the term “vault” should
be abandoned in a morphological sense. The modifications that took place
are most apparent among the Camerata, in which there is a marked increase
in the size and rigidity of the plates, which reached its culmination among
Carboniferous forms.

The tegmen of Palseozoic Crinoids is often formed into ridges, which
diverge from near the centre to the arm bases. These ridges, which are
best defined, and occur most frequently, among Silurian Camerata, are formed
either by covering pieces or the interambulacral plates. Such ridges also
occur upon the disk of the Comatule, but they are formed exclusively by
the ambulacral plates. Among the earlier forms ridges of this kind have
been observed in Actinocrinus quinquangularis,t Habrocrinus ornatus,t Marsu-
procrinus depressus,§ Marsupiocrinus radiatus (Plate VIII. Fig. 15); and
Platycrinus symmetricus (Plate LXIX. Fig. 16); in all of which the mouth
is closed either by the orals, or in their absence by the uppermost covering
pieces, which interlock with those of adjoining rays. Very prominent ridges
occur also upon the disk of Taxocrinus intermedius (Plate IT. Fig. 11), in
which, contrary to the preceding forms, mouth and food grooves are opened
out. The ventral structure of this species bears a remarkable resemblance
to that of the young Platycrinus symmetricus (Plate LXIX. Fig. Ic); all
that is required to convert the “vault” of this Platycrinus into a disk like
Taxocrinus, is that its orals should be parted enough to let the ambulacra
pass in to the centre between or over their edges. Its resemblance is equally
striking to the recent Calamocrinus and Hyocrinus ; a slight receding of the
posterior oral and movable covering pieces would bring the three forms sub-
stantially into the same condition, all of which shows that the closure of the

* Proceed. Acad. Nat. Sci. Phila., pp. 345-375.

+ Iconogr. Crin. Suec., Plate XVI. Fig. 28. t Ibid., Plate XXVII. Fig. 5.
§ Ibid., Plate X. Fig. 16.

MORPHOLOGICAL PART. 119

mouth in the older Crinoids is not accomplished by any additional set of
plates, but by the plates which in recent Crinoids surround the mouth,

Cases in which the ambulacra enter the tegmen from beneath what
were formerly called the interradial dome plates, are found in almost
every family of the Camerata. They occur more frequently among genera
in which the ventral surface is paved by small irregular pieces, such as
Glyptocrinus, Reteocrmus and Archeocrmus ; but also in others. A most
instructive case of this kind is presented by a rather young specimen of
Megistocrinus nobilis (Plate XLVII. Figs. 8a, 6), in which not only covering
pieces, but well defined side pieces enter the calyx. The ventral pavement
consists of moderately large, irregularly arranged plates, which gradually
decrease in size toward the arms. The tegmen is perfectly flat, except near
its outer margin, where it is distinctly plicated to form the large openings
for the ponderous arms. At the inner flat portions the ambulacra are con-
cealed, but at the plicated outer part both covering- and side-pieces come to
the surface, and are visible for some distance. It is now quite instructive
that in another more adult specimen of the same species (Plate XLVII. Fig.
6) the parts of the ambulacra which in the former specimen were exposed,
are roofed over from both sides by interambulacral plates of subsequent
growth. This observation throws important light upon the development of
the so-called vault of the Camerata generally. It shows that the same system
of plates, which in a young specimen is in part inter-ambulacral only, may
gradually become supra-ambulacral in another.

We find a somewhat different structure in a finely preserved adult speci-
men of Megistocrinus Hvansi (Plate XLVII. Fig. 14), in which in three of its
rays two series of large, nodose, alternating plates pass out from near the
orals in the direction of the ambulacra. The series are frequently inter-
rupted by small, flat pieces, which are interspersed among the larger
ones. In some places the arrangement of the larger plates, which are
evidently covering pieces, is as regular as in any Platycrinus ; but at
others, owing to the interference of the smaller plates, quite irregular,
especially in the two rays to the right of the anus, where scarcely any
two of those plates are continuous. It is most remarkable that in no
two specimens of this species is the arrangement of the covering pieces
alike. In some of them, only the five large bifurcating plates, the so-called
radial-dome pieces, are in view, followed by ten others of a second order.
The ventral structure of this species not only offers a good proof that the

120 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

so-called radial dome plates, as before suggested, are extravagantly developed
covering pieces, but indicates that the “vault” was formed by a gradual
extension of the interambulacral areas along the line of the ambulacra, either
covering them entirely, or encroaching upon them and leaving the more
prominent plates exposed. |

_In Glyptocrimus and Reteocrinus the tegmen is essentially in the same
condition as in Megistocrinus nobilis, but no orals are distinguishable, and
the whole ventral surface, including the median portions, is covered by
minute granular pieces. ‘The middle part is evenly convex, but toward
the periphery there are ridges leading to the arm bases, and on top of
these ridges the covering pieces are exposed. In the median portions the
ambulacra were evidently subtegminal, being roofed over by superimposed
inter-ambulacral plates, which form a continuous integument over them.

A careful study of the different tegmens which are found among the
various families of the Camerata shows that the ambulacra, as a rule, are
subtegminal in species with a high dome or bulging at the arm bases, but in
species with a flat or depressed surface they are generally tegminal, or
become tegminal before entering the arms. They are exposed in forms like
“ Actinocrinus”’ quinquangularis, Habrocrinus ornatus, Marsupiocrinus depressus,
and. Gilyptocrinus ornatus, — species with a low disk; but they are necessarily
subtegminal in genera such as Cactocrinus, Siphonocrinus, etc., in which the
tegmen is high and conical. The condition of the ambulacra, therefore,
whether tegminal or subtegminal, does not represent an essential structural
feature, but is a natural consequence of differences in the form and construc-
tion of the tegmen in the respective species. |

Now if it is true that a plated integument was formed in Glyptocrinus
and Megistocrinus by the profuse development of the interambulacral plates,
and their gradual fusion along the line of the ambulacra over a part of the
disk, it would seem to follow that the more substantial vaults of Actinocrinus,
Batocrinus, and Physetocrinus may have originated in a similar way, and that
the body of these forms also was covered by a single set of plates. This
seems to be confirmed by a very instructive specimen of Physetocrinus, in
which the delicate structure at the inner floor is shown in excellent preser-
vation (Plate V. Fig. 14). The specimen has the great advantage of being
free from any silicious coating, such as obscured the structure in previ-
ous specimens of this kind. The outer surface of the tegmen is composed
of moderately large, smooth pieces, of irregular form, closely fitted together

MORPHOLOGICAL PART. 121

at all sides. There are no orals, but near its outer margin there are radial
dome plates of a first and second order, which are readily recognized by
their large size and greater convexity. Other ambulacral plates are not
visible. Examining the inner floor, we find the same arrangement of plates,
and actually the same plates as at the outer side, but the general aspect is
totally different. They look lke sharply delineated stars, with as many rays
as there are sides to the plates. ‘There are abrupt depressions between the
star-rays, which on meeting corresponding depressions of adjoining plates,
form deep, sometimes cavernous pits, more or less undermining the plates,
and which seem to have communicated with one another by imbedded pas-
sages all along the tegmen. The star-shaped plates extend over both the peri-
stome and ambulacra, being occasionally interrupted by small, supplementary |
pieces, apparently solid. Thus the tegmen of Physetocrinus is not composed
of two distinct sets of superimposed plates, as heretofore supposed, but of one
set only, of which the plates are solid externally, and perforated or honey-
combed throughout their inner portions. The presence of but one set is
further confirmed by the position of the ambulacra, which follow the inner
floor. This is of importance, for if the upper or solid part, as was supposed
to be the case in the allied Batocrinus and Actinocrinus, represented a vault,
and the inner part a disk, the ambulacra should lie between them; whereas
in this case, lying below them both, they would be covered by two integu-
ments, first by the overlapping interambulacral plates, and then by a vault,
—an arrangement in the highest degree improbable. The ambulacral skele-
ton itselfis not preserved in the specimen, but the place it occupied is clearly
indicated by shallow grooves, formed by a thickening of the plates all along
the interradial spaces.

The internal structure of Physetocrinus gives us the key to that of Bato-
crinus, Dorycrinus, Actinocrinus, Teleiocrinus, and of the Camerata generally,
in all of which, as we no longer doubt, there is but a single integument ;
and the part which we have heretofore regarded as a disk forms a portion
of the same set of plates, which are perforated at the inner floor so as to
produce the numerous caverns and passages. above described. These pas-
sages and pits may have served for the free circulation of water, and we
think it highly probable that the older Crinoids had a very complex vascular
water system, extending all the way from the interradial plates of the dorsal
cup to the top of the ventral disk. This complex system was probably

not required in recent Crinoids, in which many of the plates are perforated
16 |

122 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

throughout, by means of which the surrounding water is brought in direct
contact with any part of the body.

There are good reasons for believing that in the Camerata the water for °
respiration was introduced near the arm bases through small openings, de-
scribed by us as respiratory pores, and then followed the canals and passages
along the test. Such openings have been observed not only among the Actino- |
crinide and Batocrinide, but also among the Melocrinide and Rhodocrinide.
In the genus Dolatocrinus, they are large and slit-like as in Ophiurids, in Bato-
crinus and Actinocrinus round, and in Gulbertsocrinus at the outer end of long
tubes. The openings are always located between the rays and their main
divisions, a little above the arm regions. Some species of Dolatocrinus have
from four to six to each interradius, and two to four to each interdistichal
space, all arranged horizontally. In Dolatocrinus this vascular system prob-
ably extended only over the peripheral portions of the disk, for the inner
floor at the middle portion is perfectly smooth in the specimens. In Bato-
crinus and Teleiocrinus it probably extended to the outer margins of the orals
(Plate V. Figs. 16 and 17); while in Physetocrinus, when the orals are un-
represented, it apparently occupied the whole tegmen.

We now come to the ventral structure of Siphonocrinus. It will be
remembered that in S. armosus not only the ambulacra, but large portions
of the anal tube, are subtegminal, and that the latter lies across the mouth
and covers portions of the ambulacra. The tube, however, in two other
species of this genus opens out centrally, thus showing that the subtegminal
condition of the tube had no important bearing upon the general structure
of the disk. As we understand the case, the anal tube, which is actually
the outer end of.the hind gut, in place of becoming free and piercing the
central part of the disk as in the other two species, was roofed over in
S. armosus by the interambulacral pieces in a somewhat similar manner to
the calyx ambulacra of Megistocrinus. |

Now if it is true that in forms like Physetocrinus, Batocrinus, Actinocrinus,
and Siphonocrinus, there is no second integument, it may be considered as
proved that a “vault,” as an mdependent structure, did not exist in any of
the Camerata, nor, in fact, in any of the other groups, and that the structure
to which the term has been applied in these forms was evolved phylogenet-
ically from the disk of the primitive types, of probably Pre-Silurian time.

The disk of the Fistulata also experienced notable changes in its palseon-
tological development, but these took place on different lines. The plates

MORPHOLOGICAL PART. 123

of the tegmen at no time attained the rigidity and large size of that in
the Camerata, nor did those of the dorsal cup, with the exception of
the anal plates, undergo any material alterations. It was the ventral sac
which gave to this group its characteristic feature. The sac in the earliest
forms was quite small, but it soon attained such enormous dimensions that
already in the Silurian it constituted the greater part of the calyx. At the
close of the Carboniferous, however, it dwindled down almost as rapidly to
its former insignificance, so that it 1s represented in Cromyocrinus, H’upachy-
crinus, E’risocrinus, and Enerinus by a very short cone. The respiration of
the Fistulata was apparently directly through the test, but only at the
posterior side of the calyx. It took place either by means of pores along the
sac, or by a madreporite placed in front of the sac. The respiratory pores
of the Fistulata only pierce the edges of the plates; while the water pores of
recent Crinoids pass through the whole plate. The mode of respiration of
the Larviformia is unknown. They had apparently no openings in the
calyx except the anus, but they possessed pores along the arms at the sides of
the covering pieces, which may have served respiratory purposes.

Most of the Ichthyocrinide have interbrachial plates, which im some
species are large and massive, in others small; and some are regularly
arranged, others irregularly. The mouth is opened out, the ambulacra are
tegminal, and rest in an integument of very small, ill-formed pieces,* which
extend to the interradial plates in the cup, and those at the sides of the
brachial appendages. The small plates form pouches or sacs, which some-
times reach to the second or third bifurcation. The median lines of these
pouches are occupied by the ambulacra, which converge to the mouth, sepa-
rating the orals.

Here we have among Palseozoic Crinoids a tegmen, which has all the
characteristics of the disk of living species, down to an uncovered mouth and
open food grooves, thus demonstrating conclusively that the disk as a ventral
structure is not confined to the Neocrinoidea. The discovery of this fact led
to entirely new ideas touching the derivation. of these groups. Before, it
had been supposed that the “ vault’ ceased to exist in Neozoic times, or was
reduced to the orals. It may now, we feel assured, be considered as estab-
lished that the structure of the tegmen in the oldest Paleozoic Crinoids,

* We carefully removed the arms in several well preserved specimens of Onychoorinus Ulricht and
O. diversus, and in several instances found portions of the ventral disk imbedded in the dorsal cup, lying upon

the inner floor of the plates. The disk of these species must have been extremely pliable, and probably con-
sisted in part of soft tissues.

124 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

although the mouth in most of them remained closed throughout life, was
not morphologically distinct from that of the Crinoids of existing forms, and
that the so-called “vault” has been developed gradually from the disk.
The Camerata, therefore, cannot be the progenitors of recent Crinoids ; they
represent a side group, which in the course of Paleozoic time departed
essentially from the primitive type, reaching the culmination of extravagance
in form and size in the Carboniferous, and becoming extinct at the close
of that epoch.

B. The Anal Plates and the Anus.

The Anal plates bear a most important part in the phylogeny of Paleo-
zoic Crinoids, and are also of high importance in respect to classification.
Some writers apply the term “anal plates”’ indiscriminately to all interradial
plates of the posterior area, while others restrict it to the plates directly or
indirectly connected with the anus. We apply the term to the latter plates,
but only to such of them as take part in the dorsal cup; the others being
plates of the anal tube or ventral sac.

The anal plates in all Camerata, when present, occupy the median line of
the posterior area, so as to divide the interbrachial plates into two equal
sets; and in rows containing an odd number they have the effect, as it were,
of breaking up the middle plate into two, even in cases where no anal plate
is inserted between the segments. The latter is the case in the Actino-
erinidx, in which the first interbrachial row at the posterior side always
consists of two plates, in place of one as in each of the others; though all
have an anal plate between the radials, and an extra plate in the second
interbrachial row. In the Batocrinidsze and Thysanocrinide there are two
interbrachial pieces above the first anal, which enclose a second anal piece.
The Hexacrinide have but one large anal plate resting upon the basals.
The Eucalyptocrinide have no anal plate at all, the five interbrachial areas
being perfectly symmetrical. Such is the case also in Dolatocrinus, Stereo-
crinus, Centrocrinus, Allocrinus, and Patelliocrinus ; while the typical Melo-
crinide have.an anal plate in one or more of the upper rows. Similar
variations occur among the Rhodocrinids, in which anal plates may be
either present or absent. The Platycrinide have no special anal piece, but
the middle plate of the proximal row at the posterior side is considerably
enlarged, and evidently united the functions of an anal plate with those of

the regular interradial.

MORPHOLOGICAL PART. 125

It thus appears that the anal plates vary considerably in their position
and distribution, and in some groups are absent altogether. As a general
rule, they are largely represented in species with a strong tube, or a protrud-
ing lateral opening; while in forms in which the anus 1s central, as in the
Eucalyptocrinids, or comparatively small, they are either wanting or but
feebly represented. The anus, although more or less influencing the whole
posterior area, did not necessarily require the introduction of anal plates,
and when the tube was small, an enlargement of the regular interbrachial
plate sufficiently increased the width of the area. The anal plates, therefore,
do not appear to constitute an essential element of the Crinoids, but seem
to be supplementary pieces, introduced when the space was insufficient to
accommodate the tube.

Among the Fistulata, the term “anal plates” has been applied to two
plates of different origin, the one radial, and the other interradial. The
latter is the homologue of the “ special” or “first” anal plate of the Came-
rata, and rests upon the truncated posterior basal. When there are two
plates in the species, as in most of the Poteriocrinide, and occasionally in
~ other families, the second — which is actually the first or lowest in point
of position — is located obliquely to the right of the first, so as to encroach
more or less upon the proximal face of the right posterior radial. Its lower
angle rests upon the upper sloping faces of the adjoining basal, its upper
face supporting the first plate of the tube, which in some of these genera is
partly enclosed in the calyx. To understand the position of the lower plate,
it should be noted that throughout the modifications which took place in
the posterior interradius in geological time, this plate always retained its
alternate arrangement with the basals, and occupied a radial position from
the beginning. Its form was changed, and to some extent its relation to
surrounding plates, by the increasing width of the ventral sac, which caused
a displacement of the arm-bearing plates. The oblique position which the
plate holds toward the posterior basal and the regular anal plate, and the
latter toward the first plate of the tube, gives to these pieces a sort of
alternate arrangement, which is continued throughout the tube.

The changes that took place among the anal plates in the various groups
of the Fistulata have been discussed by us at different times,* from which it
appears our views have undergone considerable modification as the result of

* 1879, Revision, Part I., pp. 71 and 72; 1883, Amer. Journ. Sci., Vol. XXVI., pp. 365 to 377; 1885,
Rev. Pt. III, Sect. I, pp. 11, 12, 40; and 1886, ibid., Sect. II., pp. 196 and 210.

126 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

further research. The subject was also discussed by Dr. P. H. Carpenter in
his paper “On the Relations of Hybocrinus, Baerocrinus and Hybocystites,*
and lately by Mr. F. A. Bather in a paper “On the British Fossil Crinoids.”’+
Bather agrees with us and with Carpenter that the radially disposed plate
is a posterior inferradial, which in some groups took on anal functions.
He gave it the name “radianal,’ which we have accepted, but we
apply the term only when the plate actually serves as a support of the
tube. Respecting the origin of the other plate, which we take to be a
special interradial, he advances views from which we regret to be obliged
to dissent. His idea is that this plate “ originated as a plate morphologically
corresponding to an ordinary brachial,” and he undertakes to prove that in
its paleontological development it passed down from above the radials to the
basals, and between the radials. He calls it a “ brachianal,” —a term which
becomes meaningless if it proves to be interradially disposed. To this plate
we apply the general term “anal plate,” as we take it to be the homologue
of the anal plate of the Antedon larva, and structurally identical with the
first anal plate of Actinocrinus.

We give, on Table OC, a series of diagrams to illustrate the development
of the anal plates, in which the “brachianal”—of Bather—is marked 2.
The radials are designated by the letter R, and when compound, the lower
section — the inferradial, which is also the “radianal’’ when it helps to
support the tube —by &’. The tube plates are called ¢.

To the Plate &’ we have already alluded in the chapter on the radials,
discussing those forms in which it represents a part of the radial, and lies
In a vertical line with &. Let us now consider those forms in which it serves _
as anal plate. Among these forms, of which Poteriocrinus may be regarded
as the type, four of the five radials are simple, and the Plate 2, which is gen-
erally represented, rests upon the basals. The ventral sac, which in the ear-
lier forms was rather insignificant, had rapidly increased in size at the close
of the lower Silurian, in such a manner that the sloping upper faces of the
radials were insufficient to support it, and certain changes in the structure of
the dorsal cup became inevitable. It thus happened that the two posterior
radials, which had previously been in contact laterally (Locrinus, Fig. 9) were
now parted, and the Plate x was introduced to fill the vacant’ space (Den-
drocrinus, Fig. 13). These modifications, however, did not affect the position

* Quart. Journ. Geol. Soc. London, Vol. XXXVIIL., pp. 298-312.
7 Ann. and Mag. Nat. Hist. (6th Ser.), Vol. V., April, 1890, pp. 319 to 334.

MORPHOLOGICAL PART. ey /.

of the inferradial, which retained its place between the upper sloping faces
of two basals, only changing its outlines to conform to the shape of, and fit
in between, adjoining plates. In the Carboniferous, in which the ventral sac
attained its greatest dimensions, and the lower faces of the costals frequently
fill up the whole width of the radials, leaving no space upon their distal faces
for an attachment of the tube, the superradial, &, was shifted to the right,
into a position almost directly above the right postero-lateral basal, and
obliquely against the inferradial A’ (Poteriocrinus, Fig. 2), Finally toward
the close of the Carboniferous, when the tube was. reduced to its primitive
-Insignificance, the anal plates gradually disappeared, and the five radials re-
sumed their normal position as in EH’risocrinus, Stemmatocrinus, and Encrinus.

This is entirely different from the interpretation of Mr. Bather, who
reaches the conclusion that the anal plate « was primitively derived from a
brachial, and that in geological time it passed down from above into the
dorsal cup. He regards (op. cit., p. 329) “those forms as primitive in which
the radianal is more of a radial and less of an anal, in which it is not in an
asymmetrical position but corresponds to the other lower brachial plates.
Such forms are Jocrinus, Heterocrinus, Ectenocrinus, Anomalocrinus, and Mero-
crinus. Now in all these forms x is supported by R, and does not touch R’.
Obviously then x is not derived from R’, but originates above R, and on its
left side. By parity of reasoning we assume the next stage to be repre-
sented in such forms as Hybocrinus (?), Ottawacrinus, Dendrocrinus, and Homo-
crinus, since in them #’ is rather more asymmetrical. In these a has
passed down from above F, and now rests with its lower half between the
right and left posterior radials, being supported partly by R’ and partly by
the basal. Carabocrinus, Botryocrinus, and similar forms are, as all acknowl-
edge, the next stages in the shifting of the radianal; in these 2 has sunk
still lower into the dorsal cup, and is now entirely in a line with the radials.
.. . In Parisocrinus and Euspirocrinus among pinnuless forms, and in the
Poteriocrinites, another change has taken place; the radianal has passed
through a revolution of 90°, and the lowest plate of the ventral sac (t) has
sunk down between R and z.”

Before inquiring into the validity of this argument, it will be well to ascer-
tain whether the plates of the different genera which Bather calls x are
structurally the same thing, for an error in this respect would be fatal to the
whole theory. The question is, is his plate x in Jocrinus and Merocrinus,
which rests upon the one marked by him R or O, and that resting upon FR’

128 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

in Hybocrinus, and R in Anomalocrinus, homologous with the plate of Den-
drocrinus, Homocrinus, ete., which is supported by R’ and partly by the
basals, and also with the plate of Poteriocrinus, which rests upon the basals
and against the radianal #’? This question was not discussed by Bather,
though we had expressed views different from his respecting the plate x in
focrinus and Merocrinus. That plate was regarded by us, in both genera (in
focrinus as early as 1879),* as a plate of the tube, and, so far as we know,
we never made any statement from which he might infer that we thought it
represented the plate z ; yet he quotes us in his diagrams as if we had done
so in 1879.

Instead of commencing with the earliest forms, as Bather did, we begin
with the simplest, and select as a starting point the genus Cyathocrinus, which
is so well known to every paleontologist. Cyathocrinus has simple radials,
and but one anal plate, which, as all writers agree, represents the plate x. It
rests upon the truncated upper face of the posterior basal, between two ra-
dials, and is generally followed by three plates of the tube (Fig. 3), of which,
as in the Batocrinide, the two at the sides rest to an equal extent against
—or rather upon — the sloping upper faces of adjoining radials. The
structure of Graphiocrinus de Kon. and Le Hon, as amended by us in 1879, is
similar to that of Cyathocrinus. This genus also has only the plate x repre-
sented, but here it is angular at the upper end instead of truncated, and
supports but two equal plates of the tube. This produces a sort of bilateral
_ symmetry in the posterior side of the tube, each plate supporting a vertical
row of hexagonal or subquadrangular pieces.

Next in order we take Dendrocrinus, in which the right posterior radial
is compound, and its two plates are in line vertically. This genus is an
intermediate form between the earlier and later Fistulata, and its struc-
ture throws important light upon the phylogeny of the group, especially
as to the anal plates. Contrary to the rule in most of the earlier Fistulata,
the plate x is well represented, but the inferradial, ft’, is not in a position to
perform anal functions.

Let us examine the form represented by Dendrocrinus Casei, from the
Lower Silurian of America (Fig. 13), a species with rather narrow, horse-
shoe shaped radial facets, and an extremely large ventral sac. The two
posterior radials are widely separated, and the plate x is succeeded, as in
Cyathocrinus, by three plates, ¢, ¢, t, of which the middle one rests upon the

* Revision, Pt. I., p. 65.

MORPHOLOGICAL PART. 129

truncate upper face of plate z. The plate to the right lies at a somewhat
higher level than the one to the left, and does not touch w, owing to the
greater length of the compound radial, while that to the left touches it
slightly. The three plates form part of the free tube, and each one is fol-
lowed by a vertical row of other tube plates.

Comparing this structure with that of Heterocrinus (Fig. 10), Ectenocrinus
(Fig. 11), and Hybocrinus (Fig. 8), we find that the plate ¢ in all these forms
takes practically the place of the three plates (¢¢¢) in Dendrocrinus. In
either case the plates constitute the lower tube plates, and rest — the one
as well as the three — upon the sloping upper faces of the two posterior
radials; but while the three plates of Dendrocrinus are supported by a special
anal plate, the radials of LHeterocrinus, etc., meet underneath, and the anal is
unrepresented. In Dendrocrinus, which has an extremely large anal tube,
the anal « is well represented ; while in the three other genera, in which the
tube is narrow, and the outer edges of the radials are sufficient to support
it, that plate is wanting. If it were true that the plate ¢ in Heterocrinus
represents the plate z, and sunk down in paleozoic times to the basals, as
supposed by Bather, the plate « would be represented twice in Dendrocrinus
Casei, once by x, and again by #, both plates being present and in place.

Bather makes the statement (p. 331) that the “ brachianal ” and the
plates succeeding it in regular series, are to be regarded as brachials, but
that the remaining plates of the sac are nothing more than plates deposited
in an extension of the ventral perisome, and in conformity with this he
has called the superradial of Jocrinus an axillary plate. The term “ axillary ”
in Crinoid terminology is given exclusively to plates of the rays, and every
axillary is followed necessarily by a branching of the arm. Bather in using
that term must have supposed that the so-called brachianal, and the plates
succeeding it, are parts of a modified arm, which in geological time became
incorporated into the sac, for in no other way could we understand why he
called it an axillary. He has probably been misled by the angularity which
occurs upon the upper face of the superradial, or by the form of the plates
succeeding it to the left, and the slanting position of the posterior arm to the
right. In that case he overlooked that the radials in Actinocrinus also have
sloping upper faces, and yet that those plates are not axillaries, supporting
as they do at one side a costal, but an interbrachial at the opposite side;
and it did not occur to him that such might be the case also in Jocrinus.

Examining the anal interradius as it appears in the Camerata among the
17

130 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

various families, we find in the Batocrinide directly above the plate x a
supplementary anal, and an interbrachial at each side of it, exactly as in
most species of Cyathocrinus and Dendrocrinus, except that the interbrachials
of the two latter — 1. ¢., the plates corresponding to them — are incorporated
into the tube, but those of the Batocrinide into the cup. Turning to the
Actinocrinide, the plate « supports a supplementary anal in the second inter-
brachial row, but none in the first, a structure recurring in Graphiocrinus,
in which « is followed by two tube plates which take the place of the two
interbrachials of Actinocrinus. In the Dolatocrinites, however, in which z is
wanting, and the first row of the anal interradius is formed of a single plate,
this rests upon the sloping faces of two radials, thus occupying almost the
same position as the plate ¢ (# of Bather) in Ectenocrinus, Hybocrinus, and
focrinus. That the plate ¢ in some of these forms is somewhat irregular in
position, leaning more to the right than to the left, is due to the asymmetry
of the right posterior radial. :

From these observations it appears that there is a close agreement be-
tween the anal plate and tube plates of the Fistulata on one side, and the
anal plate and interbrachials in the cup of the Camerata on the other ; and
we are led to believe that those plates respectively are homologous. Admit-
ting this, we have a much more satisfactory explanation of the anal plates of
the Fistulata than that given by Bather, whose views are totally at variance
with the structure of the Camerata, and are based upon premises which are,
to say the least, hypothetical.

After agreeing upon the structure of Dendrocrinus and Iocrinus, that of
the other Fistulata is readily understood. Anomalocrinus is in a condition
similar to that of Jocrinus, but it has two compound radials instead of one
(Hig. 12). The plate is unrepresented, and the tube, which is narrow,
rests within a notch formed by the sloping upper faces of the two posterior
radials. Nearly the same structure is found in Heterocrinus and Ectenocrinus
with three compound radials, and in Hyboerinus with but one, and in all of
them the plate x is wanting. How Mr. Bather could conclude from the
structure of Hectenocrinus, Tocrinus or Hybocrinus, three of the most primitive
forms, that « originated as a plate “ morphologically corresponding to an
ordinary brachial,” and that ¢ could sink down to the basals, we do not
understand. It appears from his own diagram that the plate which he calls
x in Eetenocrinus is placed symmetrically between the two posterior radials,
resting as much on the one plate as on the other, but not touching the basals,

MORPHOLOGICAL PART.

TABLE C.

i Gone

ey

ey

Y

=>P

Ss

S

©

NS

IN THE DEVELOPMENT OF THE ANAL

SIDE IN THE INADUNATA.

DIAGRAMS ILLUSTRATING THE CHANGES

5. Haplocrinus clio; 6. Sym-

3. Cyathocrinus ; 4, Pisocrinus ;
9. locrinus ;

2. Poteriocrinus ;

7. Baerocrinus ;

1. Locrinus subcrassus ;

bathocrinus ;

ll. Eetenocrinus ;
16. Ceriocrinas ;

10. Heterocrinus bellevillensis ;

8. Hybocrinus ;

13. Homocrinus ;
19. Allagecrinus.

radials ;

17. Uloerinus ;

15. Poferiocrinus ;

12. Anomalocrinus ;

Nes

14. Dendrocrinus ;

Frisocrinus ;

; [=costals; ¢= tubeplates; o=orals.

special anal plate

inferradial; «=

dea

6=basals: R

t32 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

See our diagram (Fig. 11). So also the plate ¢ of Heterocrinus bellevillensis
(Fig. 10), though less symmetrically disposed, rests upon both radials, and
not on the plate to the right only, as figured by Bather. |

We now pass to those forms in which the inferradial R’ performs the
functions of an anal plate. The first step in this direction is shown by
Homocrinus (Fig. 14), Botryocrinus, Oncocrinus, and Barycrinus, in which the
superradial # has shifted slightly to the right, and is connected with the
inferradial by an oblique suture; contrary to the case of Dendrocrinus,
in which the two plates are arranged vertically (Fig. 18). The plate ¢ in
those forms rests upon A without touching A’, and the plate 2, which is
comparatively large, rests against both sections of the compound radial.

Bather explains the evolution that took place in these forms by “the
shifting of the radianal,” and that “z has sunk still lower into the dorsal
cup, and is now on a line with the radials.” Nothing of this kind is indicated
by the specimens, which clearly show that the radianal throughout the
Fistulata retains the same position, whether it constitutes a part of the radial
or serves as anal plate. It only changes its outlines so as to conform to the
shape of contiguous plates. As the tube became larger, the radials spread
out, and the vacant space thus formed was filled by a new plate, zx. There
was no sinking of the plate ¢, which never moved from its place above the
radials.

Another stage in the developmental history of the anal area among the
Fistulata is presented by Parisocrinus, Atelestocrinus, H'uspirocrinus, and the
typical Poteriocrinide. Bather, in alluding to them, makes the following
statement: “In the Poteriocrinites (see our diagram Fig. 2) another change
has taken place; the radianal has passed through a revolution of 90°, and the
lowest plate of the ventral sac (¢) has sunk down between R and x.” If we
understand what this means, he assumes that the lower section of the radial
moved to the left; while in fact, as the specimens show, it was the upper
section of the plate that moved away, shifting to the right and leaving
a space for &’ and ¢ to meet. Thus it was that z came to rest against R’,
but not against £, from which it was separated by the plate ¢. An increase
of width in the anal area became necessary, as the surface for the support of
the tube was insufficient to hold it. In Homocrinus and Dendrocrinus, the
costals occupy only a comparatively small part of the radial, and a. rather
large portion of the latter serves as a support for the tube. In the Poterio-
erinide, however, and in Parisocrinus, Huspirocrinus, and Atelestocrinus, in

MORPHOLOGICAL PART. 133

which the brachials fill up the greater part, or all of the distal face of the
radials, it required additional surfaces for the accommodation of the large
tube.

From the structure of the typical Poteriocrinidze we come to that of
Ulocriuus, Graphiocrinus, Ceriocrinus, Hrisocrinus, and Stemmatocrinus, which
we regard as transition forms toward Hnerinus. The ventral tube, which in
the latter of these forms dwindled to a short cone, did not require as large a
support in the dorsal cup, and as the anal plates gradually became obsolete,
the posterior radials resumed a symmetrical form. In Ulocrinus (Fig. 17)
the plate was crowded out by the large radianal; while in Graphiocrinus
and Ceriocrinus (Fig. 16) only the former is represented. In Graphiocrinus,
with a wide ventral sac, the anal plate is large; in Certocrinus it is reduced
to a small piece, and the posterior basal is considerably elongated. Lriso-
crinus (Fig. 18), Stemmatocrinus, and Hnecrinus have no anal plates at all, the
cup being perfectly symmetrical; and the tube rests entirely upon the
edges of the radials, whence it started in Aybocrinus, Ectenocrinus, and
allied forms.

. In view of these facts, it seems to us that Bather’s theory of a “ brachi-
anal” is based upon a wrong interpretation of some of the plates. If it
were true that the plate of Jocrinus to the left of the supraradial passed
down in later forms to the basals, it would mean nothing less than a partial
revolution of the entire tube. This, however, is disproved by the structure as
well as the paleontological development of the tube, which latter is generally
composed of longitudinal rows of hexangular pieces, alternating in adjoining
rows. In the earlier and simpler forms the tube consists of only five series,
one to each interradius, that of the anal side resting upon plate ¢. Later on,
as the tube grew larger, a new row of plates was introduced with plate 2 sup-
porting it. When there are three series, as in Dendrocrinus, the third generally
rests upon one side of the left posterior radial. The arrangement of the
plates within the rows is so regular that if a sinking of the plate ¢ had taken
place, it would certainly be indicated by some disturbance among the lower
plates in the tube. In species where the tube has more than three rows, one
or more of the primary rows dichotomize at some distance from the cup.
The fact that the increase of the tube phylogenetically took place by the
introduction of new rows of plates, is a strong argument in favor of our idea
that the plate x is also a supplementary piece, and was introduced in the
same manner as the plates which it supports.

134 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

The symmetry of the Crinoids, as a rule, is bilateral, and the anal area
occupies the median axis. The asymmetry which occurs in many Fistulata,
and in certain Ichthyocrinidx, is caused by irregularities in the radials.
Wherever these attain a regular form, the plate x takes its median position,
and the plates of the ventral tube are arranged on a strictly bilateral plan.

Whether the symmetrical calyx, as represented in the Silurian and later
Cyathocrinidee, was evolved from the asymmetrical form, we are unable to
ascertain. It may be that the two had a common symmetrical ancestor, or
that all these Crinoids were primitively asymmetrical, and that the lower
section of the posterior radial became early resorbed in some cases. Against
the former theory it may be said that in the Lower Silurian Fistulata, so far
as we know without exception, the right posterior radial is compound, and
that the symmetrical form occurs with the other in the same families; against
the latter, that the symmetrical form is already well represented in the
Upper Silurian.

We have made no reference here to the Calceocrinide and Catillocrinide,
as we have not at present the material to study the older forms; but we feel
quite certain that their structure in this respect shows no material departure
from that of the older Fistulata.

The anus of the Crinoids is located in the disk, and is either central, sub-
central, or marginal, —din the latter case sometimes coming down to the
arm region. In some species there is merely a simple opening passing out
directly through the disk ; others have a tube with an opening at the distal
end or along the side. The size of the tube is quite variable. In some
genera it rises to a height of several inches beyond the arms; while in
others it is less than half their length. The tube is composed of heavy,
generally nodose, wedgeform pieces, admitting but little mobility in the
structure. When there is no tube, the anus is generally situated within the
centre of a wart-like inflation, composed of very minute pieces, which
possibly were movable, and could be drawn in by the animal, like those

y)

in the “ proboscis” of recent Crinoids, so as to open or close the aperture.
There has been some difference of opinion whether or not species with
an anal tube should be separated generically from those with a simple
opening. Considering the slight differences upon which many genera have
been founded, it would seem that the tubular structure ought to be of
sufficient importance to justify a separation; but considering that various

groups, after being carefully restricted with reference to all other characters,

MORPHOLOGICAL PART. ESS

include both forms, its value as a full generic character might well be
doubted. It was probably this that led Meek and Worthen to establish
subgenera for these forms. We finally concluded to make them full genera,
finding considerable objection among naturalists to subgeneric divisions.
Only in Platycrinus and Melocrinus were we obliged to retain both forms
under the same generic name, as we are unable to separate them. Their
tegmens are rarely preserved, and among the species of Platycrinus espe-
cially are found all possible gradations from a simple opening to a good
sized tube.

As a rule, a tube occurs more frequently among species in which the
arms form a continuous series around the calyx; while species in which they
are arranged in clusters often have a simple opening. Most of the latter
forms have a wide, more or less depressed space along the disk, between the
two posterior rays, for the foecal matter to pass out; but when the tube is
long, and the arms in close contact all around, the excretions were dis-
charged above the arms.

Occasionally, among species with a slender tube, we find specimens in
which during the life of the animal the tube was broken at the base, and
the fractured edges upon the disk were rounded off by calcareous growth,
so that it appears like a simple opening. From this we conclude that the
tube had no important bearing upon the general organization of the animal,
aud that the Crinoid could live without it. This is also indicated by speci-
mens in which the anal tube was obstructed, and a new passage formed
at another place. Abnormal passages of this kind occur along the tube,
upon the disk, within the dorsal cup, and even within the basal ring.
They are more or less restricted to the posterior side, but are not neces-
sarily in a vertical line with the anus, as we formerly supposed. When
it occurs within the basal ring, the opening is located anteriorly, but
turns to the right whenever it enters the sides of the dorsal cup. It is
located posteriorly — or nearly so—close to the arm bases, but above the
calyx if may occur on any side of the tube. The Museum of Comparative
Zodlogy has a very interesting specimen of Batocrinus longirostris, in which
a new tube of the same size as the original one has been formed just
above the calyx. In this instance apparently the second tube also became
obstructed, and a third one was in process of formation. A similar case is
presented by our specimen of Batocrinus laura (Plate IV., Fig. 14). The
tube m the specimen of Hutrochocrinus Christyi (Plate IV., Fig. 16) gives off

136 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

a small branch horizontally at a short distance from the disk. In another
specimen of that species (Plate IV. Fig. 17), in which the tube is broken above
the arms, it was replaced by another, which starts off somewhat obliquely
from the top of the stump. A tube in a similar condition was observed in
a specimen of Lobocrinus pyriformis, but there the recuperation made but
little progress, for the new part did not attain one third the width of the
old tube at the point of fracture. In the specimen of Macrocrinus jucundus
(Plate IV. Fig. 15), a small branch starts from the tube close to the calyx,
while in another specimen of our collection a branchlet is given off near the
end of the tube. In Fig. 12 of the same plate (Steganocrinus pentagonus),
and in Fig. 11 ( Teleiocrinus wmbrosus) a second tube was formed at the top
of the disk, in the former occupying the median line of the posterior area,
and in the latter directed slightly to the right. In the remarkable specimen
of Hutrochocrinus Christyi (Plate IV. Fig. 13) all the arms of the right pos-
terior ray, and the outer arm of both adjoining rays, were destroyed, and the
break in the test was closed by irregular new plates, which support a con-
spicuous second tube. A still more remarkable instance of recuperation is
presented by a specimen of Batocrinus subequalis (Plate IV. Fig. 10), in which
an enormous tube breaks forth above the basals. It occupies the whole
length of the dorsal cup, and involves the plates of the posterior interradius,
as well as of the posterior ray, and even some of the arm openings. The
plates bulge outward almost at right angles to the sides of the cup, and form
the lower part of the tube. Fig. 9 has a very large opening between the
basals leaning somewhat toward the anterior side, which we think performed
the functions of the anus in that specimen. |

Passing now to the Inadunata Larviformia, it must be stated that, so far
as observed, the anal v is unrepresented throughout this group (see Figs. 4,
5, 6, and 19 of the preceding diagrams), and we know of no case in which the
anal tube, where it exists, is supported by an inferradial. This is explained
by the absence of interbrachial and interambulacral plates, and the position
of the anus intermediate between the radials and orals, or piercing the latter.

Pisocrinus,* Phimocrinus, and Symbathocrinus have a long slender tube be-

* The tube of Pisocrinus was observed by Bather, and described by him in his late work on “ The
Crinoidea of Gotland,” Part I. p. 22). It rests upon the truncated limbs of the compound radial and the
large simple one to the left; but not upon the two supported by the plate &’. Bather refers the proximal
plate of the tube to the anal 2, although the plate rests, like ¢ in Eetenocrinus and Hybocrinus, upon the
radials, and takes no part in the composition of the cup. So also the corresponding plate in Symbathocrinus
is a tube plate, and not an anal as we stated in our earlier writings.

MORPHOLOGICAL PART. 137

tween the arms to their full length, which in Symbathocrinus is composed of
elongate quadrangular pieces. ‘The tube rests upon the upper faces of the
posterior radials, and extends to the tips of the arms. Haplocrinus, as we
understand it, has a simple anal opening, piercing the upper half of the
posterior oral. Cupressocrinus, has a well-defined aperture between the
muscle plates of two adjoining radials.

The anus of the Inadunata Fistulata has been observed in but a few
instances, and then only in the Cyathocrinide, the Poteriocrinidx, and in
the embryonic Hybocrinus and Carabocrinus. In all of these cases, the open-
ing was apparently covered by a rather large, rounded pyramid of eight or
more pieces, which resembles the anal pyramid in the Cystids. In Carabo-
ermus, in which the ventral disk remains permanently in the larval state,

IS
co Xp.
eee aes
(i Uh DB
: ea? Es
ears a,
R x
Rt
Fie. 1. Fre, 2.
Carabocrinus. — Fig. 1. Ventral aspect. Fig. 2. Dorsal aspect.

R=radials; &’ = radianal; « = anal; 2p = anal pyramid; o = orals.

having five large orals similar to those of the Larviformia, and subtegminal
ambulacra, the pyramid is excentric and directed upwards (Figs. 1 and 2 of
the accompanying diagrams).* A similar anus was observed by W. R. Billings
in Hybocrinus conicus. In Cyathocrinus we have observed the anal pyramid
in several species, and found it located in all of them at the end of the tube,
directed anteriorly (Plate VII. Figs. 11 ab and 124s). The anus of the Pote-
riocrinidz, which we have seen in Poteriocrinus, Decadocrinus, and in several
species of Scytalocrinus and Scaphiocrinus, is located at some distance from
the top of the ventral sac, and invariably at the anterior side, sometimes

* These diagrams were made after drawings by Mr. Walter R. Billings. The specimen of Fig. 1 is in

the collection of Mr. J. Stewart, that of Fig. 2 in his own collection.
18

138 THE CRINOIDEA CAMERATA OF NORTH AMERICA. -

very low down in the sac (Plate VII. Fig. 1a). An anal pyramid has never
been found in place in this family, but that it existed, at least in some of the
species, seems very probable from the form and large size of the opening
(Plate VII. Figs. la, 2a,6, 3, 4, 7, 8). There are other Poteriocrinids, and
especially among species with an inflated, balloon-shaped sac, which have no
openings in the sac, and we are inclined to suppose that in these cases, and
also in many other Fistulata, the anus was located in the disk proper between
the sac and the mouth. In the remarkable Aulocrinus represented on Plate
VIL Fig. 9, there is a large spout-like tube passing out from the huge sac
between the arms on the anterior side, half way down, like the simple
opening in Figs. 7 and 8. We have found this extraordinary tube pre-
served in five other specimens of this species, and its form and position
are very constant.

The anus of the Ichthyocrinidee has been observed only in Zaxocrinus and
Onychocrinus (forbesiocrinus de Kon. and Le Hon). Both genera have a small
tube, of which the posterior side consists of a vertical row of subquadran-
gular, comparatively large plates. Its anterior side is composed of a large
number of very minute pieces, forming a kind of pouch, widest at the
proximal end, which gradually passes into the disk. At the anterior side
the tube leans considerably to the right, and it may be suggested from this
that Taxocrinus and Onychocrinus are derived from the asymmetrical Gnori-
mocrinus, which apparently had a similar tube. The arrangement of the
anal plates in the Ichthyocrinids is substantially the same as in the Fistu-
lata. In some of their genera only the plate # is represented, in others R’ ;
while still others have no anal plate at all. Bather makes no reference to
the anal plates of the Ichthyocrinidx, but regards the anals of the Camerata
as morphologically distinct from those of the Fistulata. On page 319
(op. cit.) he says: “it may be pointed out that, as interradials do not
enter into the composition of the dorsal cup in any Fistulata, none of
these plates can well be the homologues of interradials: in many of the
Camerata actual interradials are present in the anal area, but in the Fis-
tulata at least we must look elsewhere for the origin of the so-called
‘anal’ plates.” Now if it is true that the anals of the Camerata re-
present something different from those of the Fistulata, because they
possess no interbrachials, it must be the same also with the anals of the
Ichthyocrinide, among which interbrachials are represented. But what
would be the result? Some of their genera have interbrachial plates, and

MORPHOLOGICAL PART. 139

others not. In Lecanocrinus Billingst* there is at the posterior side an anal
a, together with a radianal; while at the other four sides the radials and
costals of adjoining rays meet laterally. Lecanocrinus macropetalus Angelin
(not Hall),f on the other hand, with exactly the same arrangement of anal
plates, has a large interbrachial plate at the four regular sides. The case is
even more perplexing in Zaxocrinus Thiemei, of which some specimens have
one or three interbrachials, while others have none. We thus find within
the same genus, and even within the limits of the same species, interbrachials
present or absent, and according to Bather’s theory the anal plates of one
specimen would be homologous with the anals of the Fistulata, and those of
the other structurally distinct. He seems to have regarded the anal plate
in the larva of Antedon as the homologue of the plate x in the Fistulata,
because the genus has no interbrachials. He says: “it is not an interradial ;
for the so-called ‘interradials’ that some observers claim to have seen are
only perisomic plates of no morphological importance; further it is a most
gratuitous assumption to make Antedon the only form with an interradial in
the anal area, while devoid of true interradials in the other interradii.” In
assuming that Antedon has no interradials, he employs the term in the
narrow sense in which it has been used heretofore; but since then we have
learned that all plates interposed between the rays and the ambulacra con-
stitute parts of the same element, and the same plates morphologically may
be interbrachial in one group, and partly or wholly interambulacral in
another. |

Thaumatocrinus is the only recent genus which has a tube, such as we
find among the Paleocrinoidea. This tube rests upon a large interradial
plate, which, however, is not a special anal, for a similar plate is interposed
between the radials of the other four sides, exactly as in the Rhodocrinide.
This seems to us a further proof that the plate x is not a primary element,
but a supplementary plate, and was introduced only in cases where the
structure of the anus required it.

* Tconogr. Crin. Suec., Pl. XXII. Fig. 25.
tT Ibid., Pl. XIX. Fig. 4.

140 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

INTERNAL CAVITY OF THE CALYX.

A. The Chambered Organ and the Axial Canals.

A striking feature in the organization of the Comatule is the quinquelo-
cular organ, situated in the cavity of the centrodorsal, and placed at right
angles with the central axis. This organ was first noticed by Heusinger,
who in 1828 described it as the central organ of the blood vascular system.
Muller also took it to be a heart-like organ in connection with a system
of membranous tubes. Dr. W. B. Carpenter regarded the membranous
tubes of Miiller as solid fibrillar cords, proceeding from a similarly con-
stituted envelope around the chambered organ, and he came to the con-
clusion.that this fibrillar sheath, and the cords proceeding from it, constitute
the central nervous system of the Comatule. This was afterwards confirmed
by experimental evidence, and is now generally admitted by zodlogists.

The organ in question is a sac, divided into five radial compartments,
enclosed by a thick envelope in connection with the axial cords. From the
dorsal surface of this envelope processes are given off to the cirri, and from
its margin arise interradially five short primary cords, which, passing up-
wards and outwards, bifurcate into right and left branches between the
centrodorsal and radials. The ten secondary cords diverging from one
another, enter the substance of the radials, and either unite in pairs, the
right branch from one interradial meeting the left branch from the adjoining
one (Higs. 3 and 4), or the two branches, as in Enerinus liliiformis (Hig. 5),
without touching each other, proceed on separately to the costals. On
reaching the first axillaries the two cords open out into two branches, right.
and left, and after traversing the plates, enter the right and left arms,
respectively. In addition to the above connections, there is a circular or
_pentangular commissure, which, immediately after entering the radials, con-
nects the various branches among themselves, and additional connections
between the branches within the axillaries supply the arms (Figs. 3 to 4)..
The axial cords along the arms lie in tubular channels piercing the calcareous
part of the various arm joints, each cord giving off penned right and
left branches, which enter the pinnules.

Chambered organs have been observed also in Stalked Crinoids, but the
position is not quite the same as in the Comatule. While in the latter the

MORPHOLOGICAL PART. 141

organ is lodged within the centrodorsal, and is covered by the rosette,* it is
in Pentacrinus, which has no centrodorsal, contained in a cavity formed by
the radials above and the basals below. The five chambers of Pentacrinus
are not closed at the bottom, but are continued down the stem as five vessels,
systematically arranged around a central axis. ‘These vessels were regarded

Fig. 3, position of the axial cords in the young Antedon rosaceus (after W. B. Carpenter); Fig. 4,
their position in the adult (after A. M. Marshall); Fig. 5, in Excrinus liliiformis (after Beyrich).

ed = centrodorsal; ¢ = infrabasals; 46 = basals; # = radials. The dark lines show the arrangement
of the canals in the dorsal cup.
by Dr. P. H. Carpenter as homologous with the five openings around a single
one on the underside of the calyx, and along the stem of Cupressocrinus, Myr-

tulocrinus, and Gasterocoma. Among recent Stalked Crinoids a chambered

* In most of the Comatule, the embryonic basals are metamorphosed into the structure known as the
“rosette,” which is enclosed within the radial pentagon, so as to be not visible externally.

142 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

organ has been observed in Ahizocrinus, Bathycrinus, and Holopus, and it
existed probably in the other genera. Among Jurassic and later fossil
Crinoids, axial canals, piercing the body of the calyx plates, are known to
exist in the Apiocrinidee and Kugeniacrinide (Holopide Jaekel), and they
are readily recognized in the Triassic L’ncrinus, in ' some of the later Palao-
zoic Poteriocrinide, and in Mycocrinus and Catillocrinus ; but we have found
no trace of them in the Camerata, except in Steganocrinus pentagonus (Plate
LXI. Fig. 3), in which, so far as observed, the five or six proximal plates of
their tubular appendages are pierced by a canal. Such canals occur upon
the radials in some of the Cyathocrinide, the Cupressocrinidx and Gastero-
comide, and we may suppose that a chambered organ existed in these and
other groups, if not in all Crinoids. In cases where grooves or canals for
the reception of cords are not apparent, the cords may have rested against
the inner wall of the plates.

B. The Convoluted Organ.

In the abdominal cavity of Palseozoic Crinoids, the only organic structure
that under very favorable conditions has been observed, is a peculiar skeleton
which occupies the greater part of the cavity.

It is a large convoluted body, in its outlines resembling the shell of
a Bulla, open at both ends. Its upper part rests directly beneath the origin
of the ambulacra, the lower end within the basal ring without touching the
plates. It is dilated above, contracted below, its lateral faces placed parallel
to the inner walls of the calyx; the bottom truncated. In some species it is
subcylindrical, with the vertical axis the longer, in others globose or even
depressed globose. In coiling around its axis, the partition walls do not
meet each other, but leave more or less wide interspaces. The convolutions
vary in number from 2 to 4 according to species, and are, as they pass out-
ward, directed from right to left. The walls in the usual preservation are
thick, and perfectly solid, as they were described by Hall; but in transverse
sections they frequently appear as if composed of two partitions closely fitted
together, and closed along the edges. In some specimens, however, the
walls are simple, and constructed of an extremely fine and delicate filigree
work, composed of minute pieces or bars, with intervening meshes, which
do not intersect at any uniform angle, but anastomose so as to impart a kind
of irregular regularity to the form and size of the meshes. No such structure
has ever been observed in the other specimens, in which the pores or meshes

MORPHOLOGICAL PART. 143

seem to have been obscured by heavy incrustations of silicious matter at
both sides, and these incrustations may have produced the apparent dupli-
cation of the walls (Plate V. Figs. 1, 4, 9, and 12).

Among the many beautiful examples in the Wachsmuth collection at the
Museum of Comparative Zodlogy, in which the convoluted organ is pre-
served, there are two unique specimens (Plate V. Fig. 11 and Fig. 10); the
former showing the delicate porous texture, the other its position beneath
the ambulacral skeleton. The collection contains also the remarkable speci-
men of Macrocrinus verneuilianus (Plate V. Fig. 8), in which the upper end
of the organ is surrounded by a large annular vessel with five radial and five
interradial openings. In this species the end of the outer fold turns into
a narrow thickened strip, which ascends spirally toward a place in the
direction of the anal tube. This structure differs somewhat from that of
Telewocrinus and other genera which have a thickened edge along the lower
margin of the outer fold passing upward (Plate V. Figs. 1, 3, 12). Ina
specimen in our collection, either of Strotocrinus or Teleiocrinus, we succeeded
in removing at one side the two outer folds, and exposed the third or inner
fold (Plate V. Fig. 4), which has the form of a spindle, thicker at the middle
and tapering to both ends. It seems that the innermost cavity in all cases is
spindle-shaped, and that the inner end winds spirally upwards like a screw
the so-called “collar” of Meek and

with rather sharp, roughened edges,
Worthen. A connection with the ambulacra has not been satisfactorily
observed in the specimens; neither the upper part of the organ, nor the
ends of the ambulacral tubes, have been found in perfect preservation.

The function of the convoluted organ can only be conjectured, as no
similar structure has been observed in recent Crinoids; but from its position
it seems probable that it was connected with, or formed a part of, the
digestive apparatus. If the latter was the case, the thickened outer end,
leading toward the anus, may represent the hind gut.

SYSTEMATIC PART.

A. Classification.

In our classification of 1885,* under the belief that the Brachiate
Crinoids were divisible into two groups so widely different in their ventral
structure as to entitle them to rank as distinct orders, we adopted the name
Pelmatozoa as a collective term to include the Crinoids, Blastoids, and
Cystids. In so doing we followed the lead of Dr. P. H. Carpenter, who t
brought forward this name as one which had been introduced by Leuckart
in 1848; with the difference, however, that whereas Carpenter used it to
designate the Stalked Echinoderms as a “ branch”’ of the “ phylum” Echino-
dermata, and to include the Crinoidea, Blastoidea, and Cystidea as classes of
equal rank, we proposed to treat the same collective group as a “class” of
the Echinodermata. We subdivided the Pelmatozoa into two subclasses,
the first to contain the “orders” Cystidea and Blastoidea, the second the
Crinoidea. ‘The latter we divided into Palzocrinoidea and Neocrinoidea.

It has been shown by Agassiz ¢ that the name Pelmatozoa, although used
by Leuckart at various times to include the Cystids and Crinoids, — presum-
ably including in the latter Blastoids also, —can hardly be considered as
well established ; that it was not adopted by any writer on Crinoids before
Carpenter, except Sir Wyville Thomson, and that Leuckart himself, from
1848 to 1879, used Crinoidea or Pelmatozoa indiscriminately in the same
sense.

The term “Pelmatozoa,” as having reference to the pedunculate condi-
tion, is objectionable, because in all three groups — Cystids, Blastoids, and
Crinoids — there are many forms in which no stem is found, and some that
apparently never had any. The latter is probably the case, among Crinoids,

* Revision, Part ITI. p. 78. |

t Challenger Report on the Stalked Crinoids, p. 198 e¢ seg.
t Calamocrinus Diomede, p. 8.

SYSTEMATIC PART. 145

in Marsupites and Uintacrinus ; while Agassizocrinus, Edriocrinus, and the
Comatulz are stemless in the adult. Among Blastoids, the stem is wanting
in Pentaphyllum, Tricelocrinus and Hleutherocrinus ; and this is the case also
in a large number of Cystids. The three divisions undoubtedly are nearer
related to each other than to any of the other groups of the Echinoderms,
not so much by reason of the stem, as because their habit of life is with the
mouth upward, the body lying on its back or growing on a stalk, in contrast
with the habits of Starfishes, Ophiurids and Urchins, which crawl about
mouth downward, and the Holothurians, which swim with the mouth side-
wise. Upon these characters, perhaps, the Echinoderms might be conveni-
ently separated into three great groups; but in that case a new name should
be adopted in place of “ Pelmatozoa.”

We are now prepared to accept the Crinoids, Cystids, and Blastoids as
separate groups of independent rank; but what may be their exact relative
importance, that is to say, what should be the exact size of the compartments
to be provided for them in the scheme of classification, is purely a matter of
opinion, and not of great consequence. The tendency of authors is more
and more toward recognizing them as groups well distinguished from each
other, and they are now ranked generally as independent classes.

There is in our opinion not the slightest doubt that the “ Crinoidea,” as
proposed by J. S. Muller in 1821, were limited to Brachiate forms, or, to
be technically accurate, to the Stalked Echinoderms with “articulate arms.”
This is clearly shown by his definition,* already quoted by us in a previous
chapter. While including among his species both recent and fossil forms,
Miller did not refer to his Crinoidea a single Cystid or Blastoid, although
both must have been known to him. Cystids are abundant at the Dudley
locality, from which he described some Crinoids, and a Pentremites had been
ficured in 1808 by Parkinson in his “Organic Remains,’ —a work with
which Miller was no doubt familiar. The name “ Crinoid,” in the strict sense
thus employed by Miller, has been sanctioned by the usage of practical natur-
alists ever since, and in our opinion all attempts to strip the term of its
familiar signification, either by enlarging or restricting its meaning, will
prove abortive. If von Zittel, instead of a new name for the Crinoids, had
proposed some appropriate term for the larger group, —to include the
Crinoids, Cystids, and Blastoids, — it would have been a very desirable im-
provement, and we believe would have been generally accepted.

* Natural History of the Crinoidea, p. 7.
19

146 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

While adhering, therefore, to the original definition of Miller for the
Crinoids, and recognizing the Blastoids and Cystids as distinct groups, of
relatively equivalent rank, we have to admit that the three types are con-
nected by a number of remarkable intermediate forms, and that it is ex-
tremely difficult in many cases to ascertain whether certain forms are Crinoids
or Cystids, or Cystids or Blastoids. It has been stated that Crinoids and
Blastoids are distinguished from Cystids by their distinct pentamerous sym-
metry; that the Blastoids and Cystids, as opposed to the Crinoids, have no
true arms; that the Blastoids have hydrospires, the Cystids calycine pores,
etc.; but the best of these characters meet with exceptions. We find in
certain Blastoids, and also in Tiaracrinus from the Devonian, and Zophocrinus
from the Upper Silurian, only four radii; and even as late as the Mesozoic
there are among the Plicatocrinide species with three, four, and six rays.
Porocrinus has the calyx and arms of a Crinoid with calycine pores of a
Cystid. Hybocystis has stumps of arms with recurrent ambulacra on three
of its rays, and on the other two rays calyx ambulacra, which pass down
the cup as far as the basals. The genus was described by Wetherby as a
Cystid, by Etheridge and Carpenter as a transition form between Crinoids
and Blastoids; while we have regarded it a Crinoid with strongly persist-
ent Cystidean characters. Caryocrinus, which has always been considered
a Cystid, has segmented pinnule-bearing arms like a Crinoid; but it has
calycine pores and hydrospires, and according to Carpenter six rays. Codaster
was made a Cystid by E. Billings, by Etheridge and Carpenter a Blastoid.
Stephanocrinus was placed by Roemer among the Cystids, by Etheridge and
Carpenter among the Blastoids, and we take it to be a Crinoid. Asteroblastus
has calycine pores like a Cystid, and ambulacra and pinnules like a Blastoid.

These, and other facts that might be adduced, point to a common origin ;
but what may have been the exact line of derivation between the three
groups is a problem that is difficult to solve. They are found side by side
in the Lower Silurian; but while the Cystids ceased to exist at the end
of the Devonian, and the Blastoids at the close of the Carboniferous, the
Crinoids survived to the present day. From this it seems to be evident that
the Cystids, as the lowest in rank and earliest in time, were the ancestral
type, and the progenitors of the other two; butit is possible that the Crinoids
preceded the Blastoids, although the latter became extinct before the close
of Palzeozoic time.

That the origin of the Crinoids must have dated back far beyond the

SYSTEMATIC PART. 147.

Silurian and perhaps Cambrian age, is indicated by the high state of develop-
ment which some of their forms had acquired as early as the Trenton
group, when they had in some cases almost completely thrown off their
Cystid characters. A striking example of this among the Camerata is seen
in the genus Glyptocrinus, in which we find associated with certain primitive
characters a high degree of perfection. It is less perceptible among the
Inadunata, in which, notably in the Hybocrinid, Cystidean features are
strongly intermingled with the characters of the larval Crinoid. But even
among them it is impossible with the knowledge we have, or are likely to
obtain, to form a conjecture as to the group of Cystids from which they are
originated, and this is readily explained if we consider that the two types
followed independent lines of development, and departed from one another
more and more in geological time.

The general tendency of the Crinoid type, taken as a whole, has been
toward pentamerous symmetry, and in this they differ essentially from most
of the Cystids. But the pentamerous tendency had to struggle with other
tendencies, which in various ways from time to time carried one or the other
of the subordinate groups far off in other directions. A disturbance of this
kind was caused by the introduction of anal plates, by means of which the

pentamerous symmetry was temporarily disturbed by a bilateral one, which |

for a time threatened to overshadow the former, until finally after the elimi-
nation of those plates the pentamerous symmetry was permanently restored.
The phases through which the anal plates pass in geological time in the
various groups are well represented by individual growth in the larva of
Antedon, and have proved to be excellent characters for family and generic
divisions.

The earliest fossil Crinoids have no special anal plate, and were more or
less strictly pentamerous. Among the Lower Silurian Camerata the anal
x is represented only in the Reteocrinide and in the abberrant genus Comp-
socrinus ; in all others the plate is wanting. It is absent also in the genus
Ichthyocrinus, one of the earliest forms of the Articulata, and, as we think,
the precursor of a large series of genera with anal plates. It probably
was represented earlier in the Fistulata than in the other groups, as might
be expected, for among them all tendencies toward further development
seem to have been exhibited upon the posterior side.

But there were other influences, not due to the anal plates, and not di-
rectly traceable to anything shown by embryology, which not only disturbed

148 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the radial symmetry, but the bilateral as well, and strongly suggest that
the Crinoids had to wrestle for a long time with the tendencies derived from
their Cystid antecedents, manifesting themselves in a variety of irregular-
ities, which from time to time characterized special groups. Such are the
presence of compound radials in one or more rays; the variations in the
form and composition of the proximal ring in the base; the non-arm bearing
radials of Baerocrinus, Atelestocrinus, and TZribrachiocrinus ; the irregular
number of radials — more or less than five — of the Plicatocrinide; and
the almost complete obliteration of symmetry among the Pisocrinide and
Calceocrinidee. |

The division of the Crinoids into two orders: “ Paleocrinoidea” and
“ Stomatocrinoidea”’ was proposed by us on account of the apparent differ-
ence in the conditions of the actinal portions of the calyx, whereby mouth
and food grooves, and the ventral disk generally, of all Paleeozoic Crinoids,
without exception as we supposed, was covered by a special integument —
the “vault”’ of antecedent literature — instead of being external and exposed
to view. With the knowledge we then had this seemed to be a character
morphologically of extreme importance, and it was so regarded by others.
Under the order Palzocrinoidea we placed all Crinoids with covered mouth
and closed food grooves, and under the Stomatocrinoidea those in which
mouth and food grooves are exposed. The two groups were accepted by
Carpenter, but he changed the name of the latter into “ Neocrinoidea.”

Another classification was introduced by Neumayr,* who proposed the
name “Hypascocrinoidea” for all Crinoids in which mouth, ambulacral
vessels, and Saumpldttchen (the latter if present) are beneath the tegmen ;
and the “ Hpascocrinoidea”’ for those forms in which the ambulacra are not
covered by the tegmen, but have external grooves, which are either exposed
or closed by movable Sawmpldttchen. Under the latter he arranged all recent
Crinoids with our Fistulata; under the former the Ichthyocrinide and Haplo-
erinide together with our Camerata. It is surprising that Neumayr’s classi-
fication, while based like ours upon the condition of the mouth and surround-
ing parts, led to such different results. This must be attributed largely to
the interpretation which he gave to the disk of Cyathocrinus, in which he
took the vacant space found in the centre of imperfect specimens for the
mouth, and to the fact that he was unacquainted with the ventral structure
of the Ichthyocrinide.

* Die Stamme des Thierreiches, 1889, p. 462.

SYSTEMATIC PART. 149

When we discovered that the ventral surface of Taxocrinus, and probably
of all Ichthyocrinide, is covered by a disk almost like that of recent Crinoids,
and that it possesses an open mouth and open food grooves, it was instantly
apparent to us that a division upon the line of Palzozoic and Neozoic
Crinoids could no longer be maintained. The moment this truth was
recognized, it was found to be reinforced by other considerations which were
fully set forth by us at the time.* It might have seemed practicable to ~
retain the two grand divisions upon the same characters as before, by trans-
ferring the Ichthyocrinidez to the division containing the recent Crinoids ;
but this would have made a change of the names unavoidable. Besides, the
fact that those characters go back as far as the lowest Silurian was enough
to suggest the gravest doubts whether the particular condition of the ventral
covering was morphologically as important as we had supposed.

About the same time we came into possession of specimens of the
Camerate genus Platycrinus with orals almost perfectly symmetric, and the
covering plates of the ambulacra most regularly arranged. Considering that |
in this same genus there are species in which the tegmen 1s composed of as
heavy plates as in any Actinocrinus with subtegminal ambulacra, the con-
clusion forced itself upon us that the plates of the tegmen in all these forms
represent the same element, and that the most rigid “vault”’ of Palaeozoic
Crinoids is but a modified disk.

The change in our views was announced in our paper on “The Perisomic
Plates,’ in which we gave up the Palexocrinoidea and Neocrinoidea as
natural groups, and proposed in place of them the Camerata, Inadunata, and
Articulata.

A separation of the older Crinoids into three divisions was attempted by
us as early as 1877, and all that we have since learned, whether through our
own observations or those of others, has tended to confirm their validity.
Now that we have got rid of the imaginary line between Palzozoic and
later Crinoids, we can better realize the importance of these groups, espe-
cially since we find that they can be applied to all Crinoids, recent as well
as fossil.

We regard as the most important characters for dividing the Crinoids
into orders : —

1st, the condition of the arms — whether free above the radials, or partly incorporated
into the calyx. wa)

* Proc. Acad. Nat. Sci. Phila., 1888, p. 350, ef seg. t Ibid., p. 345.

150 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

2d, the mode of union between the plates of the calyx — whether movable or
immovable.

od, the condition of the stem — whether the young joints were formed beneath the
proximal ring of the calyx, or beneath the top stem joint.

The morphological importance of these characters is shown by the fact that
among the earlier Crinoids they appear as well defined as among those of
later epochs, which indicates that the origin of the three groups dates back
to a much earlier time.

The Crinomza InapUNATA represent the simplest form, their dorsal cup
being composed invariably of only two rings of plates, or three when infra-
basals are present. It has no supplementary plates, except an anal piece,
but this is not represented in all of them. The radials at four sides of the
cup are in lateral contact, and the arms are free from the radials up.

In the structure of the ventral disk we recognize two different plans;
the one exhibiting the utmost simplicity, being composed exclusively of five
large oral plates forming a pyramid; the other showing considerable com-
plexity at the posterior interradius, which is drawn out into a sac or tube.
Upon these two plans we divide the Inadunata into two subgroups: The
InaDUNATA LAryirormiA, and the InaApuNATA FisruLata, both embracing
monocyclic and dicyclic forms.

The calyx of the Larvifornua consists of but few plates; viz.: basals
— occasionally infrabasals — radials and orals, the latter forming a closed
pyramid which rests against the radials; the mouth is closed, and the am-
bulacra are not exposed to view. The arms are simple, non-pinnulate, one
to each ray, and they are composed of long, quadrangular joints which,
except upon the radials, are united by close suture. The anus is excentric,
either piercing the posterior orak or situated between the orals and radials,
and is sometimes extended out to the end of a long, narrow tube. One can
scarcely imagine a more complete parallelism than there is between these
ancient Crinoids and the larval state of recent ones, and it was this that
suggested the name of the group, which, as we believe, represents the most
primitive type of the Crinoids generally. That we do not find the Larvi-
formia prior to the Niagara, but only subsequent to the advent of the other
groups, may be accounted for by the small size of their species. The calyx
of Allagecrinus Austinit from the Scotch Carboniferous is no larger than
a small grain of sand, and it is very possible that the earliest forms were
altogether microscopic. The total absence of supplementary plates, and the

SYSTEMATIC PART. 151

compound nature of the radials in the earlier forms, are other primitive
features characteristic of this group.

The Fistulata, in a general way, agree in the structure of the dorsal cup
with the Larviformia. But while in the latter the disk is simple in the
extreme, that of the Fistulata is highly specialized by means of the extrava-
gant development of the posterior interradius, forming a tube or sac which
often is drawn out to the full length of the arms. The sac rests upon the
radials or 1s supported by the anal z, and frequently — not always — con-
tains the anus. Owing to the large size of this sac, and the disturbances
thereby produced, the whole calyx acquired a marked irregularity, which
was still further increased in species with compound radials, so that the
pentamerous symmetry, and the bilateral also, were often supplanted by
asymmetry. ‘The other interambulacral areas are but feebly developed, and
are pushed over toward the anterior side. The anal opening is situated
near the top of the sac, or at some place along its anterior side, and some-
times in front of the sac close to the mouth. The sac, at least in some
groups, is pierced by pores, which we think had respiratory functions,
similar to the water pores of recent Crinvids, in which also they are more
profusely distributed at the posterior area than at any of the four other sides.
In some groups, in which the sac is not perforated, we discovered upon the
disk, directly behind the mouth, a poriferous plate, a sort of madreporite,
which probably performed the same functions as the pores in the others.

The Crrvomea Camerata have a large number of supplementary pieces,
which are distributed almost equally throughout the five sides of the calyx,
by means of which the proximal arm plates for some distance are incor-
porated into the calyx, thereby increasing the capacity of the visceral cavity.
All plates of the calyx are heavy and immovable, being united by close
suture. The symmetry of the dorsal cup is either strictly pentamerous or
sub-bilateral; we never find that asymmetry which is so characteristic of
some of the Fistulata. The base is monocyclic or dicyclic, and mouth and
food grooves are perfectly closed.

The CriInoIpEA ARTICULATA agree with the Camerata in that their lower
brachials take part in the calyx, and help to enclose the visceral mass; but
their plates from the radials up are movable. The incorporation of the
brachials took place by lateral union among themselves, by the introduction
of supplementary plates, or by means of an incrusted or naked skin; and
mouth and food grooves are exposed upon the disk. The base is dicyclic,

152 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

but the infrabasals are fused with the top stem joint, which throughout this
order is not the youngest joint of the stem,

To the Articulata we refer the Ichthyocrinide, and all Mesozoic and later
Crinoids — recent and fossil — in which the new stem joints are introduced
beneath the top jomt. They are divisible into two suborders : —

I. The ArticuLata Impinnata, to include the Ichthyocrinids which are
destitute of pinnules.

Il. The ArticuLaTa PinnaTa, to include those families in which pin-
nules are present.

That there exists a close resemblance between the Ichthyocrinide and Coma-
tulee — especially their earlier stages —is well shown by our illustrations
on Plate VI. Figs. 13 to 20, and it is worth mentioning that no other form
has changed so little in geological time as the genus Ichthyocrinus, which
survived from the Lower Silurian to the Coal Measures, and which may be
regarded as the ancestor of all Articulata. |
The name “ Articulata” was proposed by J. S. Miller, and adopted by
Johannes Miiller for a subdivision of the Crinoidea. The former referred to
it Apiocrinus, Hncrinus, and Pentacrinus, to which Miiller added the Coma-
tule. He defined the group as one in which the lower ray plates are con-
nected laterally by a skin, which may be naked, or paved with irregular
plates. From this definition we judge that his ideas of the group were
substantially the same as ours, and we believe if Miiller had known the
Ichthyocrinide, he would have placed them together with the Apio-
crinidze and Comatule, His definition, however, is not complete enough,
and it admits forms which in our opinion are widely different. We al-
lude to the Encrinide and Pentacrinidse, which differ from the Apio-
crinides and Comatule in having the uppermost joint of the stem the
youngest joint, whereas in the latter two it is not. That Miiller admits
Pentacrinus into this group we can understand — its lower brachials actually
are united by a skin— but it is difficult to see why he added the genus
Enermus, in which the rays are free from the radials up. The Pentacrinide
have through the Encrinide close affinities with the Poteriocrinide, and are
probably their descendants; but if they are Inadunata, they represent an
aberrant type, for their lower brachials, as stated before, are enclosed in the
calyx. This departure from the Inadunate plan may perhaps be explained
if we consider that the calyx of the Pentacrinidew, owing to the reduction of

SYSTEMATIC PART. eye

the ventral sac, was incapable of holding the visceral mass without incorpor-
ating the lower brachials. As such the Pentacrinide may represent the last
survivors of an exhausted type, or they are the progenitors of a new group.

After eliminating from the Articulata the Encrinids and Pentacrinide,
and all Crinoids in which the top stem joint is the youngest joint of the stem,
we have a well-defined group; but it may be asked whether the name
Articulata can be retained for a group thus restricted and redefined. The
name is most appropriate, and as the group is based largely on the character
of Miiller, we think it is just to the author to adopt his name. In case, how-
ever, other writers conclude that this course is inadmissible, we propose the
name “ Articulosa”’ to take the place of Articulata, to meet the contingency.

That our primary divisions are natural groups is further confirmed by the
orientation of the base, which, when the proximal ring of the base is un-
equally tripartite, varies among the different groups. Comparing the
base to the dial of a clock with the anal side at 12, it may be said that in
the Impinnata the smaller infrabasal points to 2 o’clock; in the dicyelic
Fistulata,* so far as observed, and in the Antedon larva, according to Bury,
to 6 oclock; and that the small basal in monocyclic Crinoids generally
points to 7 o'clock, contrary to all Blastoids, in which it points to 5 o’clock.
We have no explanation of these facts to offer, but they doubtless have an
important bearing upon the derivation of the groups.

It is now well established that the value of a character for classificatory
purposes is not always in proportion to its physiological importance; but
depends more on its constancy throughout groups, and its correlation with
other characters. The characters of any group are not fixed and rigid, but
we must always be prepared to find as to one or more of them variations or
departures from the typical form, indicating a transition toward, or con-
nection with, some other group through that particular feature. We cannot
expect absolute persistence of any one character, whether specific, generic,
or ordinal, and the larger our collections the less persistent and fixed will we
find the separate characters. But if we are reasonably happy in our identi-
fications, we may expect to find greater reliance to be put upon the corre-
lation of characters, so that while one or more of them will show a tendency
to departure, the sum of all will exhibit a predominance which will hold the
form in question within the given group. There is no hard and fast rule by
which it may be determined that a certain character is of “family” or
“generic” importance. It-may be the one or the other according to cir-

* This does not hold good for the Fistulata since Mr. Bather — Crinoidea of Gotland, Vol. I. p. 152—
has found that the position of the small infrabasal is not constant in the Gotland species of Gissocrinus.
20

154 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

cumstances, and about all we can say of the “value” of any character is
that its value is proportional to the extent to which it tends to combine
subordinate groups. As a rule we may say that a character which passes
down to earlier geological epochs, is of greater value in classification than
one dating from a later period. |

It has been stated that the supplementary plates afford excellent charac-
ters for dividing the Crinoids into primary divisions; but they are also of
great importance in the separation of families. It may appear singular that
plates whose chief function it is to fill up spaces between other plates, and
which are of but secondary importance morphologically, should have so
great a value in classification; but such is undoubtedly the case. The elimi-
nation of those plates from the calyx would reduce all Crinoids to a single
group, and these would all be Larviformia. The introduction of supple-
mentary plates into the simplest Inadunate type produces the Fistulata,’
Camerata, and Articulata, and all in their individual development necessarily
passed through the Larviformia stage.

Among the supplementary plates, the anals unquestionably take the first
rank. ‘The absence of anal plates, their introduction into the calyx, and the
relations they bear to adjoining plates — whether introduced between the
radials or brachials, or between both of them — has been regarded as very
important ; but the same characters have not the same classificatory value
in every group. ‘The differentiations produced by the anal plates have been
considered of family importance among the Camerata, but among the Fistu-
lata and Impinnata appear to be of generic value only.

The nature of the base, whether composed of one ring of plates or two, is
a valuable character for distinguishing families, but we thought it expedient
to make an exception to this rule in the case of the Reteocrinids, under
which we have united monocyclic and dicyclic forms. The number of basals
and infrabasals is of generic value only.

The occurrence of inferradials among Inadunata and Articulata, and the
modifications they undergo paleontologically, and their final disappearance,
have furnished good generic characters.

Somewhat less important from a classificatory standpoint is the number
of costals, although it was made a generic character among the Camerata;
while in the Fistulata it has in some cases no significance at all.

The general structure of the disk affords good characters for dividing the
Crinoids ito ordinal and subordinal groups. It was the total absence of

SYSTEMATIC PART. 155

perisomic plates in the disk that suggested the Larviformia, and the sac-
like prolongation of its posterior area the Fistulata; all Camerata have
a rigid disk, contrasting therein with the Articulata in which the disk is
pliable.

The condition of the ambulacra, whether resting upon the tegmen or
being incorporated into it by means of their covering pieces, or whether
constituting open furrows upon the disk, is of more than family importance ;
but the exposure of the covering pieces, and their concealment wholly or in
part by the encroaching perisome, are not even reliable generic characters.

The presence or absence of orals, and their greater or less symmetry or
asymmetry, have very little classificatory value, except in the Larviformia,
in which they are the only plates of the disk.

The condition of the anus, whether in form of a simple opening directly
piercing the calyx, or situated at the end of a tube, has been generally
regarded as of generic value: , |

Of considerable importance is the presence or absence of pinnules, which
is correlated with other characters by which very large families are dis-
tinguished, e. g., the Cyathocrinide from the Poteriocrinide; and it is the
name-giving character of the Pinnata and Impinnata.

The condition of the arms, their simplicity, their mode of branching, and
the arrangement of their plates— whether uniserial or biserial — afford
useful characters for distinguishing genera; but as all biserial arms are
derived phylogenetically, as they are embryologically, from the uniserial
ones, it must be expected that at a certain time both structures occur side
by side in the same genus.

The construction of the stem, the form of the joints, the length of the
internodes, have comparatively little value in the classification of Paleozoic
Crinoids, and are of generic value only in rare cases. Perhaps if the stems
were oftener and more completely preserved, it would help in the identifica-
tion of species.

With regard to species, their recognition is to a considerable extent the
expression of the individual opinion of the observer, and in large collections
it is often difficult to distinguish between species and variety. So long as we
have to deal with new forms, represented by unique specimens, the task is
sunple enough. But when large numbers of specimens are brought together,
in different states of preservation, presenting different conditions of growth
and size, and exhibiting the various shades of individual variation, it is not so

156 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

easy to discover and define the points by which certain assemblages of these
individuals agree with each other, and differ from others, with sufficient con-
stancy to be called species. With but a single specimen in hand, and this
imperfectly preserved, as is often the case, it is impossible to decide whether
we have a good species or a mere variation, whether it is the young or the
adult; and whether or not the distinguishing character represents a mere
abnormal condition of some established species. In describing new species,
therefore, the utmost caution is required, especially since the number of
described species in America alone has increased to almost fifteen hundred.
That a specimen comes from virgin soil, distant from any other known
locality of the same horizon, does not make it a different species. The
geographical range of species is much wider than formerly supposed, and
careful comparison with authentic specimens of allied forms must always be
made before a form can be recognized as a valid species. Among the char-
acters to be considered as most important for distinguishing species, we
recognize the form and proportions of the calyx; the relative proportions of
the plates and their ornamentation; the number of arms and arm openings,
the direction of the latter, and their distribution around the calyx, whether
continuous or separated by the supplementary plates; the form and position
of the orals, whether flat or tumid, symmetrically or asymmetrically arranged ;
the presence of “radial dome plates” or regular covering pieces, and other
characters of a more specialized nature; not forgetting that some of them
depend on the more or less adult condition of the specimen, and its preserva-
tion, and that in certain groups some of them are wholly worthless.

That a given character may be good in one group, and without any
value for classification in another, is a fact so fully recognized at the present
day that there is no need of citing instances to prove it. Every working
naturalist has encountered striking illustrations of its truth.

To facilitate the identification of species among genera containing .
a large number of forms, we have arranged our descriptions so as to place
species which are most closely related next to each other, thereby en-
abling the student to make satisfactory comparison with allied forms. In
Platycrinus, which contains an unusually large number, we have arranged
the species into subordinate groups.

It is not our intention to go into details upon the classification of the
Inadunata, but a short review of them will be necessary for this work.

We have stated that we divide the Inadunata into Larviformia and

SYSTEMATIC PART. 157

Fistulata. The former embrace the families Haplocrinide, Pisocrinide,
Symbathocrinid, and Cupressocrinide; the latter the Hybocrinidx, Hetero-
crinidz, Anomalocrinidsz, Belemnocrinide, Gasterocomide, Catillocrinide,
and Calceocrinids of monocyclic forms, and the Dendrocrinids, Cyathocri-
nidz, Poteriocrinide, Astylocrinide, Encrinide, and Pentacrinide among
dicyclic forms. The arrangement is substantially the same as that proposed
by us in 1885, in Part III. of the Revision, except that we withdraw the
Gasterocomide from the Larviformia, and place them among the Fistulata.
This change was announced by us in 1890,* when we restricted the Larvi-
formia to those Inadunata in which the orals rest against the radials, and the
ventral surface is covered exclusively by the orals, i. e,, Gumorde which
remain persistently in the larval state.

A different division of the Inadunata has been lately proposed eeu Mr.
Bather,t who subdivided the Inadunata into “ Monocyclica” and “ Dicyc-
lica;” but whether they should be ranked as suborders, he leaves as yet in
doubt. In alluding to the Larviformia and Fistulata, Bather says these divi-
sions “cannot well be maintained. Many genera hitherto included in the
Larviformia have quite as good a ventral sac as some acknowledged Fistu-
lata.” We do not know of any group to which this remark can be applied,
unless Mr. Bather undertakes to homologize the narrow anal tube of Symbatho-
crinus and Pisocrinus with the ventral sac of the Fistulata. Symbathocrinus
has no ventral sac, but simply an anal tube, nor has it an anal plate, or
perisomic pieces as we once supposed; its asymmetrical oral pyramid rests
directly upon the radials, and its anal tube is supported by the radials and
orals together. Bather further says: “they (W. and Sp.) excluded Hetero-
crmus and Calceocrinus, in which it has at all events never been proved
that other plates beside orals occur in the tegmen.’ We supposed it was
now admitted that the ventral sac represents morphologically the highly
developed posterior inter-palmar area of the disk, as was proved by the
position of the anus, which is situated either at the anterior side of the sac,
or not within the sac at all, but in front of it (toward the oral centre) in the
main part of the tegmen. Admitting this, the presence of the sac proves
that the Heterocrinide had a complicated disk.

The case is very similar in the Calceocrinide and Catilloemniden Both
agree with the Larviformia in having no anal plate, at least no anal 2; but

* Proceed. Acad. Nat. Sci. Phila., 1891, p. 355.
t The Crinoidea of Gotland, Part I., with ten plates (Stockholm, 1893), p. 20.

158 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

there are resting upon the radials what we take to be plates of the tube.
These plates, which are crescent-shaped and extremely heavy, are longitu-
dinally arranged, and pass up to near the top of the arms. The relation of
these plates is not altogether clear, but they probably represent the heavy
and solid plates of Jocrinus, which constitute the ridge along the posterior
side of the sac; and we believe that the open groove at the anterior side was
in the animal filled, as in the case of Jocrinus, by small disk plates, which
may or may not have been perforated. This interpretation seems to us”
the most probable, and upon the strength of it we have placed both families
under the Fistulata.

Bather’s definition of the Monocyclica is short: “Inadunata with no
infrabasals.” But notwithstanding its brevity it meets with two exceptions :
Cupressocrinus and Myrtilocrinus, which Bather referred to the Monocyclica
with some doubt; both have an infrabasal disk. It will not help the matter
to say that the plate in both groups is a top stem joint (centrodorsal), for the
condition of the plate in Cupressocrinus, as well as in Myrtilocrinus, is very
different from that under which the centrodorsal occurs in the Apiocrinide,
Comatulz, and Ichthyocrinide. Wherever that plate occurs, it is in dicyclic
Crinoids, and the infrabasals are fused with it. When the fusion is complete
there appears in place of the infrabasals a vacant space at the inner floor of
the calyx between the basals; nothing of which is found in these two genera.
Besides, the plate does not rest against the outer faces of the basals, as it
should do if it were a top stem joint, but against their inferior faces, like
the infrabasals of true dicyclic Crinoids.

Mr. Bather alludes to a structural peculiarity, which he thinks has “more
weight in the classification than the varying extent of tegminal develop-
ment.” He says: “It will be seen from the ensuing remarks on Pisocrinus,
Calceocrinus and Herpetocrinus, that a very large number of Inadunata Mono-
eyclica closely resemble one another, either in the horizontal bisection of
certain radials, a character which in Dicyclica is entirely confined to the
right posterior radial, or in the greater development of certain other radials.”
He overlooks the dicyclie Tribrachiocrinus, which has three compound radials,
and we find on examining the genera which he referred to the Monocyclica,
that among the twenty-four only eight have three compound radials, and
sixteen have not. Among the latter there are three with two compound
radials, Anomalocrinus, Ohiocrinus, and Baerocrinus,* and three with a single

* Tn the latter, as we understand the structure, only the inferradials became developed, but not the arm-
bearing section.

SYSTEMATIC PART. 159

one; the remaining ten genera have simple radials throughout. Neither do
we find any remarkable development of certain radials, except when these
are compound. All this is seriously in the way of making the presence or
absence of infrabasals a subordinal character. |

Bather claims that among the Dicyclica departures from the pentamerous
symmetry of the cup plates occur only in the right posterior radial. Excep-
tions to this, however, are found in Atelestocrinus and Nanocrinus, in which
the symmetry is disturbed by the anterior radial, and in the latter genus by
the right antero-lateral together with the anterior. |

Bather’s researches were largely devoted to the Dicyclica of the Niagara
and Wenlock age, which he divided into three principal families: the ‘ Den-

b)

drocrinide,” the “ Cyathocrinids,” and the “ Decadocrinide ;”’ and in addi-
tion to them he recognized two smaller families, the “ Kuspirocrinide”’ and
“ Carabocrinide,’ the latter unrepresented in Europe.

The Dendrocrinidz are defined by him as follows: “ Dicyclica, with R’
alone, or with anal x alone, or with FA’ and anal x, or with a radianal, anal
z and one plate of the tube, in the anal area of the dorsal cup; with broad
radial facet ; with dichotomous arms, that may or may not develop pinnules;
with a tegmen composed of small plates, and with a ventral tube that is
unusually long and transversely flattened.’ He states that the family is
distinguished from the Decadocrinids by the continuous dichotomy instead
of the single bifurcation of the arms; that their anal x, unlike that of the
Cyathocrinidex, is always associated with other anal plates; that the radials
have a wide, slightly specialized facet; and that their texmen is more
delicate. The Dendrocrinids are said to be represented in America in
the Hudson River group by Dendrocrinus, in the Devonian — both in this
country and in Hurope — by Homocrinus, and in the Carboniferous by Pari-
socrinus, Poteriocrinus, and Scaphiocrinus, which agree in the structure of the
anal area; the three latter with pinnules, the former without them. The
presence or absence of pinnules, and the structure of the arms, he makes the
leading characters for distinguishing the genera.

He defines his second family, the Cyathocrinidee, as having “no radianal
or tube plate in the anal area of the dorsal cup; with anal x either pres-
ent in the cup or raised above it; with five arms, simple and dichoto-
mous; with tegmen rather solid.” He refers to it Cyathocrinus, Gissocrinus,
and their descendants, with the subdivisions Cyathocrinites, Achradocrinites
and Codiacrinites, of which the latter have no anal at all, and some of their
genera have an inferradial, or a radianal, while others have not.

160 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

The Decadocrinidx, his third family, are defined as follows: “Dicyclica,
in which the arms bifurcate; each main branch bearing armlets or pinnules;
with from none to three anal plates in the dorsal cup, supporting a tube in
which the lumen is usually flattened transversely, and the plates plicated ;
with a tegmen composed: of numerous small plates, very rarely distinguish-
able.” The family is said to embrace such forms as Botryocrinus, Bary-
erinus, Atelestocrinus, Scytalocrinus, and finally Oncocrinus, Eupachycrinus,
Stemmatocrinus, and Encrinus, —in our opinion the most heterogeneous as-
semblage of genera imaginable. It is not even true that they all have ten
main arms; some of them have but five, others seven, nine, twelve, or even
fourteen; and these modifications apparently occur within the limits of
a genus, — proof enough that the number of arms is a most unreliable char-
acter in classification.

Another objection is that the family includes forms with pinnules and
without them. Bather’s views respecting the pinnules are rather peculiar.
He expresses the opinion* that the development of pinnules by itself
cannot be taken as a character indicative of divergence, and he under-
takes to prove this by the genus Botryocrinus, of which he asserts that
“the Swedish species have armlets and not pinnules,” but “the common
Dudley species undoubted pinnules.” That the appendages of the latter are
pinnules and not arms, he probably deduced from the fact that the branches
of this species are somewhat smaller and arranged regularly from alternate
joints. In discussing the evolution of the arms, Bather assumed} that
armlets preceded the pinnules, and that when finally the armlets became
small, ceased to branch, and were regularly placed on alternate sides of
successive joints, they were called pinnules. This explanation is not satis-
factory, as it would indicate that the smaller appendages are derived from
the larger ones. It seems to us more probable that the armlets are true
arm branches whose development was arrested; and we believe that every
species of Botryocrinus has armlets, and that pinnules are not represented in
any of them. Botryocrinus decadactylus we take to be morphologically in
a similar condition to Steganocrinus araneolus (Plate LXI. Fig. 2a); and we

think that in both of them every joint of the main arms bears an armlet,
whereas those species of Botryocrinus in which the armlets are given off at

intervals are in the condition of Steganocrinus sculptus (Plate LXI. Fig. 1 a).

* Ann. and Mag. Nat. Hist., May, 1890, pp. 373-376.
7 Ibid., p. 374.

SYSTEMATIC PART. 161

But while the armlets of the Silurian Botryocrinus bear no pinnules, those of
the Subcarboniferous Steganocrinus give off pinnules from the armlets.

Bather’s classification and theories respecting the evolution of the arms
are open to many criticisms, and are certainly not confirmed by a study of
the Carboniferous Fistulata. He cannot put together certain Poteriocrinide
with the Dendrocrinidex, and others with the Decadocrinidaw, nor place the
non-pinnulate Homocrinus and Parisocrinus in a family with pinnule-bearing
forms. His classification is based principally upon two things: the presence
or absence of infrabasals, which he makes a subordinal character, and the
relations of the plates at the anal side among themselves and toward adjoin-
ing plates, upon which he separates the families. He was perhaps not aware
that in Barycrinus the radianal may be present or absent in the same species,
and that Parisocrinus would be substantially identical with Cyathocrinus but
for the presence of the radianal. As family characters he also relies upon
the mode of branching in the arms, and the structure of the tegmen, which
latter he has been able to observe in only a few genera. The remarkable
development of the posterior area into a ventral sac, which in 1890 was
regarded by him as an excellent ordinal character, is omitted altogether in
his present classification.

While therefore we cannot agree with Mr. Bather upon his classification,
we fully acknowledge the excellence of his specific and generic descriptions
in his late work on the Swedish Inadunata, and the many fine observations
which he has brought out. His discoveries upon the orientation of the radials
in the Pisocrinide and Calceocrinide are of the utmost value, and have
thrown new light upon these difficult groups.

We regard as the best family distinctions among the Fistulata the
presence or absence of infrabasals, the presence or absence of pinnules,
and the relative size of the ventral sac. The structure of the tegmen, if we
knew more about it, might perhaps also afford good distinctions; but the
modifications that occurred at the anal side of the cup, and the mode of
branching of the arms, can be utilized only for distinguishing genera. The
biserial arm structure did not obtain a foothold among the Inadunata until
near the close of the Subcarboniferous, and at no time became a constant
character. More important for generic separation is the mode of union
between the radials and brachials, and the form of the facet — whether
horse-shoe shaped or forming a straight line; also the form of the ventral
sac, and whether one or more of the radials are compound.

21

162 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

The least departure from the structure of the Larviformia toward the
Fistulata is found in the genus Carabocrinus, in which the tegmen is com-
posed of five asymmetrical orals, meeting laterally and by their inner
ends, four of them resting against the radials, the posterior one being
separated from them by a number of irregular perisomic pieces, which
enclose a short anal pyramid. Somewhat higher differentiated is the
tegmen of Cyathocrinus alutaceus Angelin —C. ramosus Bather — (Plate III.
Fig. 6), whose ambulacra are subtegminal, but the orals are separated
from the radials by a narrow belt of perisome; contrary to other species of
Cyathocrinus, in which the ambulacra rest upon the tegmen, and the orals
are, or seem to be, in a state of resorption. In Hybocrinus, the ventral sac is
as small as in Carabocrinus, and it has large orals resting against the radials;
but the lateral edges of the plates are covered by the Saumpliittchen. The
Cyathocrinide have a large ventral sac, and in the tegmen a madreporite,
which was probably unrepresented in the Poteriocrinide, in which the sac
itself is perforated. The ventral sac made its appearance in the Hybo-
crinidxw, Carabocrinide, and Anomalocrinidsy as a very Insignificant protuber-
ance; in the Heterocrinidx, Belemnocrinids, and especially in the Cyatho-
crinide, and Poteriocrinide, it attained enormous dimensions, but dwindled
down in the Encrinidx to almost nothing, although some of them still have
well defined anal plates. We do not restrict the Encrinide to forms without
anal plates, such as Mucrinus, Stemmatocrinus, and Erisocrinus ; but include
among them the genera ELupachycrinus, Cromyocrinus, Ceriocrinus, and Oncocrinus,
in which the anal area passes through all possible transition stages. We
make the reduced size of the sac, and the highly differentiated articulation
between the radials and brachials, the distinctive characters of the family.

The Camerata constitute a compact and well limited natural group, and
they are a highly specialized type, which by extraordinary development
reached a stage of extreme differentiation, and produced a ventral structure
apparently so different from that of other groups, that it was for a long
time found impossible to homologize its plates with those of the other
Crinoids. They represent a type of rapid culmination and development,
possessing already in the earliest known forms well defined pinnules, and the
biserial arm structure in most of their families being permanently established
at the close of the Silurian. The organization of the Camerata may not be
intrinsically higher than that of the other groups, but they very clearly
represent a higher state of development than Haplocrinus or Symbathocrinus,

SYSTEMATIC PART. 163

in the sense that Actinocrinus 1s a more advanced. type than Platycrinus. The
two former represent the larval state of the Camerata, while Platycrinus is
a sort of transition form, in which the Camerate stage has not reached its
full development.

The Camerata existed at the beginning of the Silurian, and survived
to the close of the Subcarboniferous, with a feeble reminiscence in the Coal
Measures. But although they developed some very remarkable and short-
lived forms in the Silurian — such as the Calyptocrinids and Crotalocrinids
—the type is pre-eminently a Subcarboniferous one. In that age they
reached an extraordinary development, not only in the abundance with
which they flourished, both as to numbers and variety, but also in extrava-
gance of form and size in every one of their leading families. In the lower
Carboniferous the Camerate type seems to have achieved the summit of
its possibilities, for extinction followed rapidly after, and at the close of the
Keokuk epoch there was scarcely a remnant of the typical section left, and
at the end of the Kaskaskia the whole group, so far as Paleontology informs
us, was practically extinct. |

The Camerata fall naturally into two sections : —

I, Those in which the lower brachials and interradials form an important
part of the dorsal cup.

II. Those in which the brachials retain the form and small size of arm
plates, and the interradials are almost exclusively confined to the tegmen.

The first of these represents the typical Camerata, of which an Actinoerinus
is a characteristic example. It includes the Reteocrinide, Rhodocrinidx, Thy-
sanocrinide, Melocrinidx, Calyptocrinide, Batocrinids, and Actinocrinide.
This section reached its culmination among the Actinocrinide in the genus
Strotocrinus, of which in some species the rays are incorporated as high as the
twelfth order of brachials.

The second, or non-typical, section represents a stage in which the modi-
fication of the Inadunate type by Camerate tendencies only progressed to
a limited extent, as shown by Péatycrinus and allied forms. It includes the
Platycrinidz, Hexacrinids, Acrocrinide, and Crotalocrinids. In this section
the Camerate type was not perfectly attained, but its development was
checked. This may have been due to the large size of the radials, and the
comparatively small size of the succeeding brachials, which retained perma-
nently the condition of free arm plates. The species of this group are inter-
mediate between the Inadunata and the typical Camerata, their lower arm

164 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

joints taking part in the composition of the calyx by means of plates which
combine the functions of interbrachials and interambulacrals, and which,
properly speaking, are plates of the disk. Another peculiarity characteristic
of this section is the presence of a large facet upon the radials, in which
the lower brachials are buried, and a brachial of higher rank meets the
interradials, and sometimes the radials,

The question has been asked whether the Crotalocrinide should not
be placed under the Inadunata, instead of the Camerata. They certainly
represent an intermediate form, having some characters even of the Articu-
lata. But their lower brachials are more or less connected with plates of
the calyx, and the covering plates of the ambulacra, unlike those of the
Inadunate Crinoids, are rigidly incorporated into the tegmen. They are
morphologically in the same condition as the other families of this section,
except for the dicyclic base, and represent, as we conceive, only a different
degree of departure from the Inadunate plan.

The typical section of the Camerata appears to have been the first in
time. It was well defined in the Lower Silurian, where it was represented
both by dicyclic and monocyclic forms, — the Rhodocrinidse on the one hand,
and the Batocrinide on the other. They flourished about the same period,
culminated together in the Burlington epoch, and disappeared almost simul-
taneously, the one in the Keokuk group, the other in the Warsaw limestone.
In the Lower Silurian there was another family — the Reteocrinidee — in
which the structure of the base seems to have been subordinate to other
characters, and we found it advisable to include among them monocyclic and
dicyclic forms; it was short-lived, not surviving the Hudson River group.
The Thysanocrinide and Calyptocrinide, the former dicyclic, the latter
monocyclic, came to light in the Upper Silurian, with a very small beginning
for the former in the Hudson River; they existed for a time in considerable
abundance, but perished soon, only a few straggling forms surviving to the
Devonian. Of the monocyclic families, the Melocrinids were the earliest,
ranging from the Trenton to the Hamilton, where they seem to have been
abruptly cut off. The other great monocyclic family, the Actinocrinide,
appeared, culminated, and disappeared in the Subcarboniferous.

The non-typical section made a good beginning in the Upper Silurian
with its only dicyclic family — the ephemeral Crotalocrinides — and the
Platycrinide, represented by five genera, of which four expired before the
close of the epoch. The surviving Platycrinide had a feeble representation

SYSTEMATIC PART. 165

in the Devonian, but during the Subcarboniferous attained in the genus
Platycrinus a wealth of forms which had no equal before or afterwards in any
other group. The struggle for existence was kept up in this section by the
Hexacrinide long after the last typical Camerate Crinoid had disappeared,
and the expiring effort of an exhausted type is seen in the Coal Measures in
the form of the diminutive Acrocrinus Wortheni.

It appears, therefore, that the typical Camerata do not represent the last
of them in point of time, but that either their final efforts at perpetuation
were carried on in connection with a tendency to revert to the Inadunate
type, or the greatest persistence was manifested by that form of the Came-
rata which had departed from it the least.

The change from the pentamerous to the bilateral symmetry consequent
upon the introduction of an anal plate into the ring of the radials, was per-
haps the most important modification that took place during the palaeonto-
logical history of the Camerata, and it occurred within the range of our
knowledge of the group. The symmetry of the dorsal cup, which through-
out the Trenton group had been more or less perfectly pentamerous, was
disturbed in the Hudson River group, in both dicyclic and monocyclic forms.
In the former, four of the truncated, heptagonal basals of the Rhodocrinidx
were reduced to pointed hexagons in the Thysanocrinide, and the inter-
radial plates separating the radials disappeared from four sides, that at the
fifth retaining its position, and serving as an anal plate. The Rhodocrinide
were a long-lived family, appearing in the oldest Silurian, and persisting to
the climax of the Camerata in the Subcarboniferous, — the strange, extrava-
gant Gulbertsocrinus being their last survivor; while the Thysanocrinide
scarcely survived the Silurian.

Among monocyclic forms the disturbance of symmetry was caused by the
interposition of an anal plate between the posterior radials, which converted
their pentagonal base into the hexagon of the Batocrinide and Hexacrinide.
The pentagonal base, though reinforced in the Niagara by the Calypto-
crinidee, disappeared from the typical Camerata with the Melocrinide in the
Hamilton; while the hexagonal base, with its accompanying anal plate,
continued with great vigor in the Batocrinide and their offshoot, the Actino-
crinidee, throughout the period of greatest development of the group, and
until the extinction of the typical section in the Subcarboniferous.

In the non-typical section, we have among dicyclic forms no example of
a symmetrical base, the Crotalocrinide having a truncated posterior basal

166 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

supporting an anal plate. But among monocyclic forms the anal plate is
unrepresented in the Platycrinids, in which the base forms a pentagon.
The introduction of the anal plate occurred in the Hamilton group, and
produced the hexagonal base of the Hexacrinide. The two groups thence-
forward flourished side by side to the middle of the St. Louis group, when
the Platycrinids: became extinct ; while the Hexacrinidsx and their offshoot,
the Acrocrinidx, continued until the extinction of the Camerata.

We have not attempted to construct a genealogical tree for the Crinoids,
or a branch of one for the Camerata, because such representations are
generally unsatisfactory, and in this case the tree would have to be con-
structed too much upon imagination. Besides, our task is an humbler one.
We have rather preferred to content ourselves in this respect with giving
the general facts which our investigations seem to pretty well establish, and
such interpretation of them as appears to us reasonably consistent therewith.
Within these limits we have hoped that our generalizations may help to
form a stable foundation upon which others may raise more ambitious
structures. |

There is no doubt that the Crinoids, by reason of their great geological
range, and capacity for individual variation due to their complicated struc-
ture, offer one of the most inviting fields for demonstrating the principles of
evolution. They afford a good illustration of the principle that individual
development finds a parallel in a general way, in the phylogenetic history
of the group. But while recognizing this truth, and confirming it by the
many interesting proofs which our studies disclose, we must beware of ex-
pecting to find lineal succession, or of assuming that a form found flourishing
in any given epoch is necessarily more highly organized than those occur-
ring in previous epochs. The Paleozoic Crinoids represent in a broad sense
the larval stages of recent Crinoids; but there are many cases in which the
tendency seems to have been one of retrogression instead of progression.
Haplocrinus, with its closed pyramid of five orals, is probably the most primi-
tive type found in our collections, and yet it is a Devonian genus. The
great family of the Ichthyocrinide, whose oral condition is substantially on
a par with that of many recent Crinoids, occurred abundantly in the Silurian.
It is also impossible to tell, except perhaps in a very general way, which one
of a number of variations marked the line of succession; or in other words
which was for the time being the racial characteristic carrying all others:
along with it, even though many of them may seem more important. For

SYSTEMATIC PART. 167

the same reason we cannot point out the exact consanguinity of groups
which are apparently related by one or more characters. For we find that
when a type starts on a career of development on a specialized line and
runs its course, other characters for the time being subordinated to it follow
in more or less parallel successions. So that it may come to pass that at
a certain time we find two types apparently belonging to different lines of
development, which have reached a concurrent condition in some other
important character, and we cannot say through which of them the thread
of consanguinity has been carried. For instance, in the non-typical Camerata
we have the Platycrinidz without an anal plate accompanied and succeeded
by the Hexacrinidx, in which that plate is present. In the typical section
the Melocrinidze are followed by the Batocrinidse and Actinocrinide in
similar succession. But (according to our paleontological record) the sym-
metric Platycrinide appear at a somewhat later period than the symmetric
Melocrinidee ; — and as we do not find in the non-typical section any sym-
metric predecessors of the Platycrinide, we would be inclined on this
ground to infer that they were derived. from the Melocrinide. But here
we are met by a greater difficulty, for this involves the illogical supposition
that the Platycrinide — a family of the least development of the Camerate
type — are derived from one much more highly organized in that particular
line.

The trouble is that all our generalizations are necessarily based upon the
Crinoids as they are represented i our museums, and not upon the Crinoids
as they actually existed in geological time, which is a very different thing.
It is like trying to reconstruct a book from detached fragments of the
chapters, some of them written in hieroglyphics for whose decipherment the
key has not yet been found. We are accustomed to speak of the imper-
fection of the geological record, but it is doubtful if in our practical studies
we always bear in mind what this really means. To say nothing of the
periods antedating the Silurian, in which substantially all vestiges of life are
obliterated by metamorphism; of the accumulations of fossiliferous strata
which have been destroyed by erosion during periods of elevation of the sea
bottom; of the strata which over three fifths of the earth are submerged
beneath the ocean; of the great regions unexplored, or covered with ice,
snow, or sand; of the equally extensive areas in which the fossiliferous
rocks of one formation are buried under those of succeeding ones ; — leaving
all this out of consideration, how much do we actually know of the life |

168 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

represented in the rocks accessible to us? Nearly all the known Silurian
Crinoids come from the outcroppings of the strata at two localities in Kurope,
and three or four in America. The Devonian exposures producing well
preserved specimens are even more limited. The Lower Carboniferous col-
lections are better and more widely distributed, but are insignificant after
all. Take the Burlington and Keokuk limestones, which in a few localities
have produced more Crinoids in number and species than any other forma-
tion. They consist of several hundred feet of strata almost entirely composed
of the comminuted remains of countless myriads of Crinoids — fragments
which are worthless to the Paleontologist. It is only rarely that a thin
layer is found in which the calcareous skeletons are preserved well enough
for study ; — little basins of limited extent, in which, during a period of tem-
porarily quiet waters, the Crinoids lived, died, and were imbedded at suffi-
cient depths to escape the detructive effects of shore action. If the collector
happens to be present when one of these colonies is uncovered by the
quarrymen, the specimens may be rescued for the benefit of Science. But
it is an even chance that they will be buried in the debris of the quarry,
broken up for ballast, or walled up in the foundation of a building, and thus
be lost again. Out of the thousands of square miles in which these rocks lie
nearest the surface, all the collections that have ever been made represent
only the imperfect gleanings of not more than a few acres. If it be sup-
posed that we get, even in this way, a fair representation of the crinoidal
life of that period, the answer is that almost every new discovery of “nests”
or “colonies” of good specimens brings to light new forms, and that species
or genera hitherto very rare are often suddenly found within a limited space
quite abundantly. In the Upper Coal Measures, to judge from our books
and museums, one would suppose that Crinoids were well-nigh extinct.
Searcely a dozen species are known, and most of them only by their lower
calyx plates. Yet there are many beds in this formation which extend over
hundreds of thousands of square miles from the Missouri Valley far into the
Rocky Mountains and tilted up along their flanks, which are completely
filled with fragments of Crinoids. Suddenly the collectors at Kansas City,
who have studied these rocks for years, discover an abundant deposit of well
preserved specimens in a shale so soft that a few minutes rain dissolves
them into unrecognizable fragments.

The importance of these observations, as a practical matter, is sufficiently
shown by the fact that the discovery of a single specimen may sometimes

SYSTEMATIC PART. 169

throw new light upon important questions, and require the undoing of
much previous work ;— as was illustrated in the case of the disk of the
Ichthyocrinids, and by de Loriol’s discovery of small infrabasals in two
species of Mfillericrinus, which made important changes in the classification

imperative.

DEFINITION OF THE CRINOIDEA AND THEIR PRIMARY DIVISIONS.
Class CRINOIDEA.

Echinoderms which during part or all of their life were attached to other
objects, either by means of a stem or directly by the abactinal side of the
calyx. The visceral mass enclosed by a limestone test or calyx, constructed
of plates symmetrically arranged, and giving off well defined, free arms
from the sides. Mouth directed upwards.

I.

Crinoids in which the arms are free above the radials. The top
(OMItRcerrOUneest im GME: Suem: tapes © enlue ders: kets Order INADUNATA.
A. Disk composed of orals only. Ambulacra subtegminal Suborder Larviformia.

B. Posterior side of the disk extended into a sac. Am-
bwlaerd-suprachee ming. wo 2 0 eg ke es Ase Suborder Fistulata.

iG I

Crinoids in which the lower brachials take part in the dorsal cup.
All plates of the calyx united by close suture. Mouth and .
food-grooves closed. The top joint the youngest in the stem. Order CAMERATA.

ITT.

Crinoids in which the lower brachials are incorporated into the
calyx either by lateral union with each other, or by supple-
mentary plates, or a calcareous skin, All plates from the
radials up movable. Mouth and food-grooves exposed. The
top stem joint fused with the infrabasals, and not the youngest

HOMME OF theasbenn= ltt eS es arate oe meee ee ae ec ee Order ARTICULATA.
A. Arms non-pinnulate “2°. 2. <i esa ye suborder Impmnata.
Be: Arms spminilace ¢ 2 teen a os ee a ek oe Suborder Pinnata.

22

170 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

CAMERATA.

Analysis of the Families.
Ib. TYPICAL SECTION.

Lower brachials and interbrachials forming an important part of the

dorsal cup.

A. INTERRADIALS ILL DEFINED.
The lower plates of the rays more or less completely separated
from those of other rays, and from the primary interradials,
by irregular supplementary pieces. Anal interradius divided
by a row of conspicuous plates. (Dicyclic or Monocyclic) . RETEOCRINID A.
B. INTERRADIALS WELL DEFINED. |
1. Dicyeute.
a. Kadials in contact except at the posterior side . . . . . THYSANOCRINIDS.

b. Radials separated all around . 9. 1 + ee ws RHODOCRINIDS.
2. Monocyciic.

a. Radials in contact all around.
Symmetry of the dorsal cup, if not strictly pentamerous,
disturbed by the introduction of anals between the
IoEA CIMA Se OLIV), <-. bor sates yim h ent yhen elyante ey ale om MELOCRINIDA.
Arms borne in compartments formed by partitions attached
tothe tegmen. Dorsal cup perfectly pentamerous. Plates
of calyx limited toa definite number . . . . . . . CALYPTOCRINID#.
6. fadials in contact except at the posterior side, where they
are separated by an anal plate.
First anal plate heptagonal, followed by a second between
Ew/Osiiben DRae Dial sere tserta.™ call Ms tee, clea ora pies Dean oe, a BATOCRINIDA.
First anal plate hexagonal, followed by two interbrachials
without a second anal. Arms branching from two main
crake Dy alterna bikurcabiom jen Gels ec 9s 9s ACTIN O@cuiN ma

II. Non-Typrcan Srcrron.
Brachials and interbrachials but slightly represented in the dorsal cup.

1. Monocyctic.

a. Ladials in contact all around. Base pentagonal. . . . PLATYCRINID.&.
6. fadials separated at posterior side by an anal plate. Base
hexagonal.
Basals directly followed by the radials. . . . . . HEXACRINID#.
Basals separated from radials by accessory pieces. . ACROCRINID&.

2. Dicyctic.
Liadials in contact except at the posterior side. . . . . OROTALOOCRINIDR.

THE CRINOIDEA CAMERATA OF NORTH AMERICA. lye!

GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION OF THE CAMERATA.
Open figures indicate American Species, those marked (), European.

NUMBER OF SPECIES.

Formations. TYPICAL Form. Non-TYPIcAL Form.
8 g ;
aS 8 ; s , ee . ;
Approximate S = = i & = | s & &
General. American. European a} 8 z ‘A 8 5 an 8 = ‘a |g
Equivalents. | 8] § 8 e = "2B Saas B Bs
Sales s S) = S See Sas Hts! S38
eer eh si i) 2 = ‘BS Oa ae Roe
me} A | & = i) Fa ls eet [cree BN lhe | ax
a { Upper Coal Measures ia 52 sap Sig legged eeteorcell” invele Meas ene es) commis nade kate eres akc eoe eetaee | eee
ae
a8 (Kaskaskia. . . . MOSCOW o5) +|becil >, syise ls aucsccly 25 We lh este een lege ey | reed aepee ee |rewie cpl elletecail
Or
| eesti v a aw? ig! gui il peel Societe eb vont | ney Meemrcpea eee esti tecg ie, oh eal iota een ate eam Feaae
zi pee Legos her RAMAN REA Here mente fn! oud eel oo Gil eeenilas ce endl aes
)
a Kee Oak aio hee Se ne eae Te : Sic Seale alae ee 41 De | ipo ERG
fy ;
Z U er . Lee ee 6 OO iG ee @ 42 18 2 6 14 7
e) ; PP Mountain
5 eee Pe aes SU (Q)ee ok oils tang)
a | Lower See tan d* See OMI O) 28 | 6
oO
im .
iB | Kinderhook ) .
Waverly opaes BUTS ub ck a cencdlt leh ales pile oe eae teases 8 cles Shsl eetced OMS
|
Chouteau J
(Chemungs. "3% digthige’ suo" at's “cleeleibit ister: [rate UBER Wheperl oh tant Desweer font usterel'a| elas tt [maura tem nae
5 Hamilton... . | Peper. fie a tas ar eg cs eal eae ms bss ta eer tooo 8
: Devonian §
Nd Upper Helderberg . Birfels ee Me. (AD SiC) ye | a ((B yal eee (2)) uted) eee
is]
A Oriskanys vs. % = « Gia aekey Ee (ly) see)
5 ( Lower Helderberg . shes eee to WIM, omer esoiceml bets || tbo, | ow!
a :
Z ss) Niagara ou Sana Gotland f .. [14 (7)]8 (3)/16 (15)|/21 (18)|8 (48)| . . | (4) 13 (5)
4
= i Hudson River . . Sug ay. 6| 2 1 5 Saar 2
s 5 SErentom \wpnirora in. Wee Denar, 1/8 8 6
ai
Potat American. 21000. <2. 464-7216 35 54 21 Pode OL | cerns (moGy Os k3
Total European. . .). 219 |../ (7)/(17)| (84) | (19) | 62) | (20)! (4) | (38)| (83)]..
a

Grand Total Species. . . 683

R
Fes D SUBCARBONIFEROUS CARBON: 3
ean EVONIAN. ; IFEROUS. S,
Lower. Upper. :
PELL SS Se ——————<_S —r—m—Xm""—™/
=
ae ee eo ae a ee
eer Meee oh ate “ree O Oy SUS ue NON ee ee ee ie
B, ge a — OD = eee = Ar OM S @ iS >
sre s ekg on Cenc are eee. Bee ae :
2S =} oe 0g WO Se Ee Q
5 os eck eS sy) common ce ee mee SO g
ee _— “<q oO =) Je S ©) fo) 9 (oe) (S) bo
—_ G °.
cle 2. ° = < si =} 2, ©, iS
< = oD hI 5
g ® g eae Se eek
so So
oS ® a)
4 Ue = Ss
oS : Zo 2 a oa
woe “— — Ss
‘ ws IN
as lel lol Sas S ton Srert
fo) eS Qa! ‘ 5 oy So © oO ve a's
at, So Pas S Be Set eee BRS
=p |=) S — © Oo OD fs) ot < 9°
i a BR Be os Se as
ES s po" oe ee yg Bee
0
or re = = =) : aww a =
a il
sa aed

Ce eee re

Se
a |

mae

7

oy iakae

7?++++—

Reteocrinidae.

Thysanocrinidae.

Rhodocrinidae.

Melocrinidae.

Calyptocrinidae.

Batocrinidae.

Actinocrinidae.
Crotalocrinidae.

Platycrinidae.

Hexacrinidae.

Acrocrinidae.

Cupressocrinus.
Myrtillocrinus.

Haplocrinus.
Symbathocrinus.
Allagecrinus.

Pisocrinus.
Hybocrinidae.

Heterocrinidae.

Anomalocrinidae.

Calceocrinidae.

Catillocrinidae.

Belemnocrinidae.

Gasterocomidae.

Cyathocrinidae.

Poteriocrinidae.

Codiacrinidae.

Encrinidae.

Astylocrinidae.

Zophocrinus ?

Ichthyocrinidae.

‘VIIVN
-NIGW]

(“IyoIdaZ)

(‘TVOIdA.L-NO NT)

“VINUOMIAYV'T

‘VILVIOLSLT

*STLOT}EULIO

VLVURNVo

LA TEED

ViLVYNOGVNI

SE en a Oe

VIVIO
OILY V

SCIONIGO OLOZOWTVd CHL HO HONVA TVOIDOTOUD AHL ONIMOHS WIEVE

B. Descriptive.

RETEOCRINIDAD W. and Sp. (1885).

THE LOWER PLATES OF THE RAYS MORE OR LESS. COMPLETELY SEPARATED FROM THOSE
OF OTHER RAYS, AND FROM THE PRIMARY INTERRADIALS, BY IRREGULAR SUPPLE-

MENTARY PIECES. ANAL INTERRADIUS DIVIDED BY A VERTICAL ROW OF CONSPICU-

POUS PLATES. (Dicyciic or Monocyctic.)

Analysis of the Genera.

Arms uniserial.

a. Radials separated all around.

Dicyclie. Infrabasals 5. Column pentangular. ... . RETEOCRINUS.

Monocychie..- Basals 4. Column square. “240. 2 asi . XENOCRINUS.
b. Radials separated only at anal side. |

Monocyclic. Basals 5. Column obscurely pentangular . . . . . TANAOCRINUS.

Geological and Geographical Distribution.

Number of known species. Only known in America.

Formation. RETEOCRINIDZ.
American. Reteocrinus. Xenocrinus. Tanaocrinus.
Hudson River. 3 2 1
Trenton. 1. ~ -
Total species .. . 7 4 2 1

Remarks. — This family was established to receive a little group of Lower
Silurian Crinoids, distinguished from all other known forms by the irregular-
ity and absence of definite arrangement in the interradial plates, caused by
the intercalation of minute supplementary pieces. These small pieces were

174 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

introduced in the growing Crinoid in great numbers among the primary
interradials and interdistichals, and between these and the basals, radials,
and brachials. The interradial and interdistichal spaces throughout this
group are greatly depressed, and the plates succeeding the radials folded
into conspicuous ridges. This structure, combined with the more or less
rudimentary character of the interposed plates, is so unique and remarkable,
that all other characters, some of
which in other groups are charac-
teristic of very distinct families,
appear to be subordinated to it,
and we are compelled to unite
under this family both monocy-
clic and dicyclic forms; those in
which the radials are all sepa-
rated, and those in which they
are in lateral contact at four sides.
We think that few, after seeing
a large number of specimens, will
doubt the propriety of this course ;
for the structure in question pro-

duces a habitus so distinct and
predominant, that it is only by

Fie. 6. Refeocrinus Onealli.

means of these characters that the
three genera of this family can be separated.

In our classification of 1885,* we proposed the genus Canistrocrinus wpon
two species, which according to the descriptions differed from all genera
previously known. In defining the genus we relied upon the correctness of
the figures; but these have proved to be misleading in some very important
points, and we are compelled to withdraw it. As to “Canistrocrinus” Richard-
sont (Glyptocrinus Richardsoni Wetherby), we are now convinced that it is
a Glyptocrinus, and identical with Glyptocrinus subglobosus Meek. It has well
defined interradials, and the anal plate rests upon the radials, and not between
them. The other species, “ Canistrocrinus’” Patterson (Glyptocrinus Patterson
S. A. Miller), may also prove to be a Glyptocrinus. The type specimens,
which Mr. Miller was kind enough to send us for comparison, are not in
a condition to make out the structure satisfactorily, being covered to a large

* Revision, Part III., p. 88.

RETEOCRINID&. 175

extent by hard matrix; and we are unable to say at present to what genus
they belong.

S. A. Miller, in his arrangement of the Lower Silurian Camerata in
1883,* united Reteocrinus and Xenocrinus with Archeocrinus, Cupulocrinus,
Glyptaster, Glyptocrinus, and Lampteroerinus in one family, under the “ Glypto-
erinide.” It is not clear to us upon what this classification was based, since
the author did not discriminate between the presence or absence of infra-
basals as a family distinction, nor between a regular or irregular arrange-
ment of the interradials; nor did he give attention to the structure of the
anal side, upon which most writers, and Miller himself, have relied for
excellent family characters. In a later paper on Glyptocrinus and allied
forms,f he states that the presence or absence of “subradial” plates, the
presence or absence of “secondary radials,’ the structure and form of the
column, and the presence or absence of a “ proboscis,” are the principal
characters upon which “ the genera of this special group” have to be separ-
ated. All of these rules are in a greater or less degree infringed by Miller
himself. His “ Glyptocrinus” parvus has infrabasals ; his “Glyptoerinus Forn-
shelh, a pentangular stem instead of round as in the typical species. A “ pro-
boscis,” such as occurs among the Actinocrinide, does not exist at all in this
group, or at least has not been observed. Neither do we find that the
proximal distichals are ever free arm plates, as Miller claims to be the case
in “ Pycnocrimus.’ The specimens which he refers to this genus, and which
he kindly sent us for comparison, have from one to two interdistichals, and
necessarily had “secondary radials.”

In Miller’s classification of 1889,+ the “Glyptocrinide” embrace the
genera Archeocrinus, Glyptocrinus, Compsocrinus, Pycnocrinus, and Schizoerinus,
which, as we think, are representatives of almost as many families. He
there makes Xenocrinus the type of a distinct family, refers Glyptaster and
Lampterocrnus to the Glyptasteride, and places Gaurocrinus, Reteocrinus,
Raphanocrinus, and Thysanocrinus under Gaurocrinide.

The Reteocrinidx are restricted to America, where only seven species
have been discovered.

* Amer. Paleeoz. Foss. (ed. 2), p. 276.

t Dec., 1883; Journ. Cincin. Soc. Nat. Hist., pp. 218-219.
+ North Amer. Geol. and Paleont., pp. 214 to 215.

176 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

RETEOCRINUS Bitt1ves.

1859. KH. Brunines; Geol. Rep. Canada, Decade VI., p. 68.
1881. W. and Sp.; Revision Paleocr., Part IT., p. 191 (Proceed. Acad. Nat. Sci. Phila., p. 365).
1883. P. H. Carrunter; Phil. Trans. Royal Soc. (Part III.), pp. 929-932.
1883. W. and Sp.; Amer. Journ. Sci. and Arts, Vol. XXV., pp. 255-268.
1883. 5. A. Mituer; ibid., pp. 105 to 113.
1885. W.and Sp.; Revision Paleocr., Part III., p. 87 (Proceed. Acad. Nat. Sci. Phila., p. 309).
1889. 8S. A. Minter; North Amer. Geol. and Paleont., p. 277.
Syn. Glyptocrinus (in part) — Haiti; 1872, 24th Rep. N. York State Cab. Nat. Hist., p. 206, Plate
5, Figs. 18 & 19.

Syn. Glyptocrinus (in part) — WetuErsy ; Journ. Cincin. Soc. Nat. Hist., Vol. II., Plate 16, Fig. 1.

Syn. Glyptocrinus (in part) —S. A. Miter; 1881, Journ. Cincin. Soc. Nat. Hist., Vol. IV, p. 83,
Plate 1, Fig. 5, and 1881, ibid. Vol. VI., p. 227.

Syn. Gaurocrinus (in part) —S. A. Minter; 1883, ibid. Vol. VI., pp. 228, 229.

Calyx obconical, its symmetry decidedly bilateral, interradial and inter-
distichal spaces profoundly depressed; the plates all along the rays distinctly
folded, so as to produce strong, rounded ridges upon their outer surfaces,
and deep grooves at the inner. The ridges branch upon the axillaries, and
follow the distichals to the arms. Other branches proceed from the middle
of the radials to adjoining basals. _ |

Infrabasals five, variable in size; sometimes barely protruding beyond
the column. Basals five, large, protuberant, hexagonal, the upper angles
truncated, and the ends somewhat inflected to meet the deep depressions of
the interradial spaces. Radials separated all around, sharply angular at the
lower faces. Costals two to three; their axillaries closely resembling the
radials, but angular above instead of below. Distichals numerous; all, or
nearly all of them, take part in the calyx, and the upper ones retain the
form of tree arm joints. The proximal pinnule occurs on the second dis-
tichal. Arms ten at their origin, but generally bifurcating ; composed of
rectangular or slightly cuneate pieces. The interradial and interdistichal
spaces filled by primary and secondary plates ; the latter very minute, inde-
finitely arranged, ill-formed, and interposed between the others, and along
the sides of the basals, radials, and brachials. The anal interradius wider, and
longitudinally divided into two equal parts by a row of very prominent anal
plates, which lie in a straight line from the basals to the anal opening.
Ventral disk depressed convex, composed throughout of minute irregular
_ pieces, which form a continuation from the interbrachials and interdistichals.
Ambulacra subtegminal. Anal opening excentric, at the top of a small
protuberance.

Column large, pentagonal; the axial canal of medium size.

RETEOCRINID A. 177

Distribution. — Age of the Trenton and Hudson river groups. Restricted
to America. | ,

Lemarks. — According to Billings, the calyx of Reteocrinus stellaris, the
type of the genus, consists of a reticulated skeleton, composed of incomplete
or rudimentary plates, each consisting of a central nucleus, with three to
five stout processes radiating from it. Of such plates he describes three
rings of five each, corresponding in position with infrabasals, basals, and
radials of other Crinoids, and he states that the genus in general structure
agrees with Cyathocrinus, Dendrocrinus, and allied forms.

It would seem at first sight that this description does not apply to
“ Glyptocrinus”’ Onealli and the other species that have been referred to this
genus, as they have numerous interbrachials and interdistichals which Bil-
_ lings failed to notice. These plates, however, are actually present in the
type specimens, having been exposed by additional cleaning. Looking at
Keteocrmus Onealli in its usual preservation, with its deep interradial areas
covered by matrix, it corresponds well with the original description. The
specimens in that state seem to have but three rings of plates in the calyx,
and free brachials from the radials up.

Miller refers to Retecerinus only Billings’ two typical species, placing the
other three under Gaurocrinus. We cannot discover any ground for generic
separation of the Ohio and Canada species. It is true Reteocrinus stellaris has
a third costal, but Miller himself did not attach much importance to this
character, for he grouped Reteocrinus fimbriatus with but two costals, along
with £. stellaris, which has three.

In amending the genus Refeocrinus in 1881,* we referred to it the follow-
ing species: Glyptocrinus Baert Meek, Glyptocrinus cognatus Miller, Reteocrinus
Jimbriatus Billings, Reteoerinus gracilis Wetherby, Glyptocrinus Onealli Hall,
Glyptocrinus Richardsoni Wetherby, and Reteocrinus stellaris Billings. We
afterwards + withdrew Reteocrinus Baert, which we found to be a Xenocrinus,
and Retescrinus Richardson’, which we placed under Canistrocrinus ; and we
added Gauroerinus magnifieus S. A. Miller. Reteocrinus cognatus is probably
a large A. Onealli, and R. gracilis a synonym of Ptychocrinus parvus.

* Revision, Part IT., p. 192.
t Revision, Part III, p. 96.

23

178 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Reteocrinus stellaris Bitirwes.

Plate LX. Figs. 3a, b, ¢.
1859. H. Bituines; Geol. Rep. Canada, Decade IV., p. 64, Plate 9, Figs. 4a, 8, e.
1877. S.A. Mrutzr; Catal. Amer. Paleoz. Foss., p. 90.
1881. W.and Sp. Revision Paleocr., Part IT., p. 193.
1889. S.A. Minter; North Amer. Geology and Paleont., p. 277.

Calyx proportionally larger than in any other species of the genus,
embracing all the distichals and portions of the palmars.

Infrabasals and basals unusually large; the former projecting distinctly
beyond the column, each plate forming a good-sized pentagon. Basals
heptagonal, slightly truncated and folded inward at the upper ends; four
of them of equal size, that facing the anal side larger, and the truncation
wider. The surface of the basals is marked by prominent keel-like pro-
cesses, meeting in the centre of the plates; one of these proceeds to the
radials and costals, two others to the infrabasals. At the sides of the pro-
cesses there are deep depressions, five of them in a radial direction, formed
by the inflection of the lower angles of the radials and the upper lateral
margins of the basals; five others, somewhat smaller, triangular in outline
and interradial, by the basals and infrabasals. The posterior basal, at its
upper face, has three ridges instead of two, of which the median one is
continuous with that formed by the anal plates. Radials about one half
longer than the costals. Costals three; the first and second quadran-
gular, the third pentangular. Distichals five to seven or more, decreas-
ing in width upwards, the upper ones taking the form of free arm plates.
Above the distichals are two more divisions, but only a few of the palmars
take part in the calyx. The arms are extremely short, and taper rapidly ;
they are composed of rather long, quadrangular joints. Interbrachial and
interdistichal areas profoundly depressed, paved by numerous irregularly
arranged and ill-formed pieces, with a slightly stellate surface. Anal in-
terradius twice as wide as the others; divided by a longitudinal row of anal
plates, somewhat narrower than the costals, but resembling them in height
and curvature. Construction of tegmen, position of anal opening, and
arrangement of pinnules unknown, Column obscurely pentangular, at the
upper end composed of very thin, knife-like joints.

Horizon and Locality. — Trenton limestone; City of Ottawa, Ontario,
Canada.

Our figures were made from the type specimens in the Canada Survey
Museum.

RETEOCRINID&. 179

Reteocrinus fimbriatus Brxu1nes.
Plate IX. Fig. 4.
1859. EH. Britines; Geol. Rep. Canada, Dec. IV. p. 65, Plate 9, Fig. 3.
1877. S.A. Mrtuer; Catal. Amer. Paleoz. Foss., p. 90.
1881. W. and Sp.; Revision Paleocr. Part IT., p. 193.
1883. W. and Sp.; Amer. Journ. Sci., Vol. XXV., p. 266.
1889. 8S. A. Minter; North Amer. Geol. & Paleont., p. 277.

A small species of the type of Reteocrinus magnijicus. Dorsal cup to the
top of the costals subpyramidal ; slightly more spreading from there upward.
The plates forming the rays rounded, and elevated conspicuously above the
interradial spaces.

Infrabasals small, their upper angles and the adjoining lower angles
of the basals depressed into small pits surrounding the column. Similar
pits are formed in a radial direction by the basals and lower margins of the
radials. Costals two, as large as the radials. Distichals eight or more,
narrower than the costals, the lower one longer than wide, the length of the
succeeding ones gradually decreasing upwards. Six of them apparently are
included in the calyx, the others free arm plates. The upper distichal is
axillary, and supports two arms, one of which remains simple, while the other
bifurcates once more. The arms decrease but little in size; they are cylin-
drical, composed of rather long pieces, quadrangular in outline, with nearly
parallel faces. Pinnules decidedly tapering to their distal ends. Inter-
radial spaces deep, paved by a large number of very small, slightly convex
pieces, without definite arrangement. There is generally but one plate in
contact with the basals, but its outlines are very irregular, and that is still
more the case with the succeeding plates, and the numerous interdistichals.
Form of ventral disk, and construction of the anal side unknown. Column
at its upper end sharply pentagonal, with re-entering angles.

Florizon and Locality. — Hudson River group; Charleton Point; Anticosti.
Type in the Canada Survey Museum.

Reteocrinus Nealli (Hazz).
Plate LX. Figs. La-f.

1872. Glyptocrinus Nealli — Hat; 24th Rep. N. Y. State Cab. Nat. Hist., p. 206, Plate 5, Figs.18 & 19.
1873. Glyptocrinus Onealli — MuzEK; Geol. Rep. Ohio, Paleont., I., p. 34, Plate 2, Figs. 3a, 4, c.

1881. Reteocrinus Onealli — W. and Sp.; Revision Paleocr., Part II., p. 198.

1882. Glyptocrinus Nealli—S8. A. M1LLER; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 37.

1883. Reteocrinus Onealli —W. and Sp.; Amer. Journ. Sci., Vol. XXV., p. 260.

1883. Gaurocrinus Nealli —S8. A. MitLER; Journ. Cincin. Soc. Nat, Hist., p, 229.

180 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

1885. Reteocrinus Onealli — W. and Sv.; Revision Paleocr., Part IIL. p. 86.
1889. Gaurocrinus Nealli—S. A. Mitter; North Amer. Geol. & Paleont., p. 247.
Syn. Glyptocrinus cognatus—S8. A. Mitinr; 1881, Cincin. Journ. Nat. Hist., Vol. IV., p. 75, Plate
1, Figs. 5, 5a.
Syn. Gaurocrinus cognatus —8. A. Mitten; 1881, Cincin. Journ. Nat. Hist., Vol. VI., p: 229.
Syn. Reteocrinus cognatus— W. and Sv.; 1881, Revision Paleocr., Part I1., p. 1938.

Calyx obconical; interradial and interaxillary spaces deeply depressed,
producing a pentagonal outline below the distichals, and decagonal above
them.

Infrabasals small, but projecting beyond the column. Basals large, their
lateral margins deeply impressed, forming an elongate pit in which the upper
angles of the infrabasals and the lower angles of the radials are involved.
The radials, costals, and lower distichals are folded abruptly inward, their
sides extending to the bottom of the interradial and interdistichal spaces,
leaving a very narrow surface exposed, not more than the width of the
arms. JDistichals ten to fourteen, of which six to seven are located within
the calyx walls, the others free. Of the fixed plates, the three or four
proximal ones are larger and especially longer than the succeeding ones,
which are nearly as short as the free plates. A second bifurcation takes
place in the free arms, giving twenty arms to the species. Arms long,
cylindrical, gradually tapering, and composed of short, wedge-formed pieces.
The first pinnule, which is given off from the second distichal, 1s more erect,
and considerably stouter than any of the rest. The second pinnule, which
occurs on the opposite side at the fourth plate (the third bears no pinnule),
is smaller than the first, but larger than the third, which is of the ordinary
size. The three proximal pinnules are incorporated into the calyx, the
succeeding ones free. Interbrachials and interdistichals very numerous,
exceedingly small, and of very irregular form and size; the marginal pieces,
as a rule, being smaller than the others. Anal side marked by a conspicuous
median ridge. Tegmen low-hemispherical, decagonal in outline; the spaces
overlying the food grooves slightly elevated. Anal opening excentric, almost
marginal, placed in the middle of a small protuberance. Column pentan-
gular, the outer faces slightly impressed ; composed alternately of thin and
somewhat thicker plates, the latter protruding considerably beyond the
others. |

Horizon and Locality. — Upper part of the Hudson River group; Warren
~Co., O.; rare at Cincinnati.

Type specimen formerly in the collection of J. Kelley O’Neall, now in the
collection of Wachsmuth and Springer.

RETEOCRINIDA. 181

Remarks. —The peculiarity that the smallest interradials are marginal
and lie next to the radials and basals, instead of diminishing in size upward,
as is usually the case, leads to the conclusion that these plates were intro-
duced between some of the older pieces, and are secondary plates which
cannot be homologized with the primary interradials of the Actinocrinide.
The structure is well shown in our figure, Plate IX. Fig. 1/, which represents
the inner floor of a fine specimen in which the arrangement of the primary
interradials is very little disturbed, being 1, 2, 3, all of them isolated and
surrounded by small supplementary pieces. We shall discuss this subject
further in our remarks upon Xenocrinus penicillus and X. Baer.

We have had no opportunity to examine the type specimen of Glyptocrinus
cognatus 8, A. Miller, in the collection of Dr. R. M. Byrnes of Cincinnati, but
from the description and the figure we are strongly inclined to regard it as
a large specimen of Leteocrinus Onealli, and not a variety of that species, as
suggested by Miller.

Reteocrinus magnificus (MitteRr).
Plate IX., fig. 2.

1883. Gaurocrinus magnificus —8. A. MittER; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 280, Plate 11,
1885. Ca magnificus — W. and Sp.; Revision Paleocr., Part I1I., p. 94.
1889. Gaurocrinus magnificus —8. A. Mitten; North Amer. Geol. and Paleeont., p. 247.

A larger species than Feteocrinus Onealli. Calyx subovoid ; section pen-
tancular; the interradial and interdistichal spaces deeply depressed; the
radial ridges broad, flattened at their upper faces, and branching from the
middle of the radials to adjoining basals.

Infrabasals small, almost covered by the column. Basals of medium size,
somewhat convex, their upper ends inflected toward the impressed inter-
radial areas, the interbasal suture lines deeply grooved, and forming with
the lower end of the radials a lozenge-shaped concavity. MRadials a little
narrower at the top than at the bottom. Costals two, narrow, as long as the
radials, and without lateral extensions. Distichals very variable in number,
from two to fifteen, the three or four lower ones almost as large as the
costals. When there are but two distichals, which is apparently exceptional,
there is an additional bifurcation in the calyx; while in the other cases there
is only one more bifurcation, which takes place in the free arms, and the
second distichals support a very large pinnule. Arms stout, rounded and

182 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

constructed of extremely short, slightly convex, cuneate pieces. Pinnules
composed of five or more joints; long, slender, and not in lateral contact.
The first pinnule is borne upon the second distichal, above which every
joint, the axillaries excepted, is pinnule-bearing. JInterradial areas more
substantial than in the preceding species, the plates stouter, and the median
portions rather convex than concave. Each area contains from twenty-five
to thirty pieces, some larger than others, of all possible shapes, and indis-
criminately arranged. The construction of the anal side is not known. The
interdistichal areas apparently extend to the top of the fifth distichals, are
comparatively flat, and composed of similar pieces to those of the interradial
spaces. Construction of disk and anus unknown. Column near the calyx
distinctly pentangular; the nodal joints longer, slightly projecting and
rounded at the margin; the internodal ones shorter, and provided with
sharp edges. |

Horizon and Locality. — Hudson River group, Warren Co., Ohio.

The type specimen now in the collection of Wachsmuth and Springer.

XENOCRINUS S. A. Mitter.

1881. 5. A. Mrtrur; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 72.
1881. W. and Sr.; Revision Paleocr., Part II., p. 184.

1883. W.and Sp.; Amer. Journ. Sci., Vol. XXV., p. 266.

1884. P. H. Carpenrer; Philos. Trans. Royal Soc., Part JII., p. 980.
1885. W. and Sp.; Revision Paleocr., Part III., p- 94.

1885. W. and Sr.; Proceed. Acad. Nat. Sci. Phila., p. 317.

1889. S.A. Mitten; North Amer. Geol. and Palzont., p. 287.

Xenocrimus resembles Reteocrinus, but is without infrabasals. Basals four,
forming a low cup, which is decagonal at the upper end; five of its sides
supporting ‘the five radials, the five others the interradial and anal plates.
This arrangement gives to the basals, owing to their abnormal number, a
very irregular form, no two of the plates being alike.
Radials generally a little larger than the costals. Costals
two, the sides bending abruptly inward and forming highly
elevated ridges; the distichals to about the fifth or eighth

plate form part of the calyx. The lower of these plates

are larger, and more or less resemble the costals, while the
hie Ve upper ones are more like free arm plates. Arms ten,
simple, rather stout; composed of very short cuneiform

pieces, which at the tips of the arms slightly interlock.

RETEOCRINIDZ&. 183

Interradial spaces deeply impressed; composed of numerous minute
pieces without definite arrangement; they rest upon the basals, separating
the rays from their bases up. Anal interradius wider than the four others;
divided longitudinally by a row of folded plates, which like the radials have
a prominent ridge upon the outer surface, and a groove at the inner floor.
The ridge ends in a small protuberance containing the anal opening, which
points upwards. Interdistichal spaces also deeply depressed, and filled by
irregular, minute plates, which like those between the main rays pass imper-
ceptibly ito the disk. Ventral disk comparatively flat, composed through-
out of very small pieces; orals being unrepresented, and the disk ambulacra
subtegminal. |

Column quadrangular, with pentangular central canal, the angles of
which are directed interradially.

Distribution. — This genus, so far as known, is limited to the upper part
of the Hudson River group of Ohio.

Type. — Xenocrinus penicillus Miller.

Remarks. — We place in this genus Glyptocrinus Baeri Meek, which, as we
have discovered, has a quadrangular stem and four basals. Xenocrinus is the
only monocyclic genus in which interradials come in contact with the basals
at all sides, but we doubt if its interradials separated the rays as completely
as in the case of the Rhodocrinids. In a specimen of X. Baert from the
collection of Mr. I. H. Harris (Plate IX. Fig. 5c), in which portions of the
inner floor are exposed, it is plainly seen that the lower ends of adjoining
radials touch each other, and after a careful study of the structure we are
inclined to believe that the small accessory pieces, which seem to separate
the radials, rest upon the lower outer margins of the plates, and not between
the plates.

Xenocrinus penicillus Mixxer.
Plate IX. figs. 6a, 6.

1881, §. A. Mittzr; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 72, Plate 1, Fig. 3; and ibid., p. 176,
Plate 4, Fig. 6.
1883. W. and Sp.; Amer. Journ. of Sci., Vol. XXV., p. 266, and 1885, Revision Paleocr. Part III.,
Dp) JG.
A small species. Calyx elongate, once and a half as high as wide, ob-
conical at the lower end, then rising almost vertically to the free arms; the
radials and brachials highly elevated, folded lengthwise with rounded back;

the interradial spaces deeply impressed, the plates somewhat nodose.

184 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Basals forming a small basin, which at the bottom is slightly excavated
for the reception of the column. Radials and costals of nearly equal size,
one third longer than wide, their lateral faces distinctly convex, so as to give
to the sides a sort of scalloped appearance. Distichals free from the ninth
or tenth plate; the four or five lower ones elongate, in form and size re-
sembling the costals; the succeeding ones gradually decreasing in length;
and the upper ones as short as the free arm plates. Arms ten, apparently
short; composed of low cuneate pieces with somewhat rounded outer edges.
The first pinnule starts from the second distichal; it is stronger than the
others, and, like the three or four succeeding ones, incorporated into the
calyx. ‘The free pinnules are more slender and longer; they consist of six
to seven joints, twice as long as wide. Interradial spaces deepening toward
the middle, and deepest in their upper portions. They are composed of
a very large number of minute pieces, are irregularly arranged, tuberculous
and slightly stellate. Similar plates fill up the spaces between the distichals.
Anal interradius wider; divided by a longitudinal row of fifteen or more
large anal plates, which in form and size resemble the lower brachials, and
their sides are scalloped in a similar manner. The row terminates in a small
protuberance near the margin of the disk, which contains the anal opening.
Ventral disk hemispherical, pentangular in outline, the surface slightly ele-
vated in the direction of the food grooves; composed of hundreds of minute
pieces; the ambulacra subtegminal. Column quadrangular, its sides dis-
tinctly concave. Axial canal pentangular. |

Horizon and Locahty. — Hudson River group; Warren Co., O.

Types in the collection of Mr. I. H. Harris of Waynesville, O.

Remarks. — Among the specimens examined, there is a very interesting
small one, in which the interradials do not touch the basals. In this speci-
men it is most remarkable how the interradials vary in size. Three of them
are tolerably large, but they are isolated from each other, and from the
radials and basals, by numerous small, almost microscopic pieces, smaller
than the corresponding plates in more mature specimens. The larger plates
occupy approximately the position of the first and second row of inter-
brachials in the Actinocrinide, and undoubtedly represent them, being
pushed out of position by the development and intercalation of supplemen-
tary pieces. |

RETEOCRINID&. 185

Xenocrinus Baeri (Meek).
Plate LX. Figs. da-d.

1872. Glyptocrinus Baeri — Murex; Amer. Journ. Sci., Vol. III. (8d ser.), p. 260.
1873. Glyptocrinus Bueri —MerEx; Geol. Rep. Ohio, Paleont., Vol. I., p. 37, Plate 2, Fig. 1.
1880. Glyptocrinus baeri —8. A. MitumR; Journ. Cincin. Soc. Nat. Hist., Vol. IIL., Plate 7, Fig. 4.
1881. Reteocrinus Baeri — W. and Sp.; Revision Paleocr., Part II., p. 193.
1883. Reteocrinus Baeri — W. and Sp.; Amer. Journ. Sci., Vol. XXV., p. 266.
1883. Glyptocrinus baeri—S8. A. Mitter; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 226.
1885. Xenocrinus Baeri — W. and Sv.; Revision Paleocr., Part III., p. 96.
1889. Xenocrinus baerti —S. A. Minter; North Amer. Geology and Paleont., p. 288.
Dorsal cup higher than wide; subovoid; depressed at the interradial
spaces, but not so much so as in X. peneillus ; cross-section pentangular.
Basals small, only their upper angles visible in a side view. Radials and
costals elongate, formed into conspicuous rounded ridges, which occupy
almost the entire width of the plates. Distichals free from the fifth or sixth
plate ; the two proximal ones as large as the costals, the third somewhat
shorter, and the upper ones but little longer than the free plates. Arms
ten, simple, long, rather stout; composed of very short, transverse joints,
with slightly convex outer faces. The lower arm joints rectangular, followed
by cuneate pieces, which slightly interlock. Interradial areas deepest in the
middle; composed of numerous very small, convex pieces, with a somewhat
corrugated surface. Anal side divided by a longitudinal row of anal plates,
shaped like the radials and costals. Ventral disk low-hemispherical; plates
very minute; the position of the anus unknown. Column quadrangular,
with obtuse angles; the joints extended outward into long knife-like edges.
Fhorizon and Locality. — Hudson River group; Warren Co., O., and Rich-
mond, Ind.
The specimens figured are from. the Collection of Wachsmuth and

Springer, and that of I. H. Harris, Esq., of Waynesville, O.

TANAOCRINUS (nov. gen.), W. and Sp.
(ravads, Slender; xpivov, a lily).

Resembling Reteocrinus, but without infrabasals, and the radials in lateral
contact except at anal side. Symmetry decidedly bilateral. Arms long and
slender. | |

Basals small; the posterior one truncated at the upper end, and followed

by a large anal plate. Costals two, narrower than the radials, and folded
24 |

186 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

like arm plates. Distichals numerous, for the most part incorporated into
the calyx. Arms branching once or twice beyond the calyx.

Interradial and interdistichal areas deeply depressed, filled by numerous
minute, irregular pieces. Anal side wider than the other four, divided by
a median longitudinal row of large anal plates, folded like the costals.
Structure of the disk and position of the anus unknown. Column round
or obscurely pentagonal.

Distribution, etc. — Restricted to the Hudson River group of America.

Type of the genus: — Tanacerinus typus W. and Sp.

Tanaocrinus typus (nov. spec.), W. and Sp.

Plate IX. Figs 7a, 6, ¢.

A small and slender species. Calyx elongate; broadly truncate at the
lower end; plates without ornamentation.

Basals five, plainly visible in a side view; forming a short cup, which is
slightly excavated at the bottom. The upper faces in four of the plates sharply
angular, that of the posterior side narrowly truncate. Radials the largest
plates of the calyx, much narrower at the top than at the bottom, rounded
at the lower face. They are connected laterally, forming a wide and deep
notch for the reception of the interradials, except at the anal side where the
first anal plate rests directly upon the basals. Costals two, as long as the
radials but narrower; folded and elevated in the middle, the lateral margins
on a level with the interradials. Distichals seven to eight; all, or nearly
all of them, incorporated into the calyx; the lower ones as long as the costals,
but a little narrower; the upper ones gradually growing shorter, and taking
the form of free arm joints. Palmars.twelve or more, all of them free. The
arms branch two or three times; they are long, cylindrical, and taper gradu-
ally to the tips, where they become very delicate and thread-like. They are
composed of short, cuneate pieces which do not interlock. The first pinnule
is given off from the second distichal ; it is more than twice as large as any
of the others, and it, as well as the three or four succeeding ones, is enclosed
in the calyx. Interradial and interdistichal spaces deeply depressed, the
plates very small and without definite arrangement. Anal side twice as wide
as the other four, and divided longitudinally by an anal ridge of five to six
large plates, which closely resemble the radials and costals. ‘The first anal
plate, which rests upon the basals, is nearly as large as the radials, and like

—

RETEOCRINID&. 187

them narrower above than below; the succeeding ones are a little smaller
than the costals. Ventral disk not visible in the specimens. Column com-
paratively large and obscurely pentagonal, the nodal joints larger, and with
slightly undulating edges.

Florizon and Locality. — Upper part of the Hudson River group, Warren
Coz, 0;

The fype specimens, which are in our collection, were presented to us by
Dr. 8. 8. Scoville of Lebanon.

THYSANOCRINIDA W. and Sp.

(GLYPTASTERIDA W. and Sp. 1885).

Dicyciic. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART OF
THE DORSAL CUP; INTERBRACHIALS WELL DEFINED, RADIALS IN CONTACT EXCEPT
AT THE POSTERIOR SIDE, WHERE THEY ARE SEPARATED BY AN ANAL PLATE.

Analysis of the Genera.
Infrabasals 5.

A. ANAL SIDE SLIGHTLY ELEVATED. ANUS WITHOUT A TUBE,
1. First anal plate followed by three plates.
_ a Dorsal cup deep. |
EAMG UNISSD ID Okan, etn ey ek eee ee OHLOGRENT Sy
Arms biserial, erect, ten totwenty . . . . . . . . THysanocrINus.
6. Dorsal cup short, almost flat.
Arms pendent, posterior oral and radial dome plates
G [OURO MOUS fas ety ed es eee HYPTIocrINus.
2. All interbrachial spaces having a single large plate . . . . IpIocRINUS.
B. ANAL SIDE BULGING. ANUS AT THE END OF A TUBE,
1. First anal plate followed by three small plates.
Lays produced into tubular extensions.
Infrabasals large ee eee eae
2. First anal plate followed by three large plates.
fiays branching in the regular way.
Epiivaljasalessmeliy ls 40 etc). * ye We eins © ho OIE HONOCHINUS:

LAMPTEROCRINUS.

Geological and Geographical Distribution.
Number of known species.

(Open figures indicate American, those marked ( ), European.)

Formation. | THYSANOCRINIDA.

Approximate
General. American. European
Equivalents.

Ptychocrinus
Thysanocrinus.

| Idiocrinus.
- | Lampterocrinus.
eo | Siphonocrinus.

Dudley
Gotland.

Lower| Huds. River. “

| Upper Niagara.

SILURIAN.

Total species

THYSANOCRINID&. | 189

Remarks. — We have changed the name Glyptasteridz, which we pro-
posed in 1885,” into Thysanocrinidx, because we found it necessary to give
up Hall’s genus Giyptaster. We also discard Dimerocrinus Phillips, and £u-
crus Angelin, and arrange the species of both under Thysanocrinus.t That
Phillips figures of Dimerocrinus were insufficient for generic identification, is
shown by the fact that the genus has been referred by Roemer and Dujardin

ae BS io wR on
SOO BOaL es:
SOOO HOGS Com

2. Oo B
aux a ae
Fie. 8. Thysanocrinus. Fic. 9. Lampterocrinus.

and Hupé to the Cyathocrinidx, while Zittel made it the type of a mono-
cycle family. Glyptaster and £ucrinus were placed by Zittel along with
Lampterocrinus, Archeeocrinus, and Glyptocrinus under the Glyptocrinidx ; in
which he was followed by S. A. Miller, who added Reteoertnus and X enocrinus,
but withdrew them again in 1889. Thysanoerinus was placed at first by both
authors under the Rhodocrinidex, from which afterwards Miller removed it to
the Glyptasterida.

The Thysanocrinide have their closest affinities with the Rhodocrinide.
Both are dicyclic, but in the Rhodocrinidsx the interradials at all five sides
are in contact with the basals, thus, as a general rule, completely isolating
the radials laterally ; while in the Thysanocrinide the radials are in contact
all around except at the posterior side, where the anal plate overlies the
basals. This bilateral symmetry in the arrangement of the plates of the
dorsal cup is accompanied by a marked asymmetry in the general form of
the calyx, and especially of the ventral disk, which is more or less enlarged

* Revision, Part III., p. 89. + See under Thysanocrinus.

190 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

posteriorly in most of the species of the Thysanocrinidw. In the new genus
Idwocrinus, in which there is but one interbrachial plate to each of the five
sides, there is no special anal plate, and the posterior interradial, which is
larger and rests upon the basals, serves as the anal.

The family is confined to the Silurian, and is composed of six genera,
with twenty-three species, of which sixteen are from America, and seven
from the upper Silurian of England and Sweden.

THYSANOCRINUS Hatt.

1836. Dimerocrinus — Puiturrs; Murchison’s Silur. Syst., p. 674, Plate 17, Figs. 4 and 5.
1841. Dimerocrinus — MisttER; Monatsber. Berlin. Akad. d. Wissensch., p. 208.

1850. Dimerocrinus — p’OrBieny ; Prodréme LI., p. 46.

1852. Glyptaster — Haut; Paleont. N. York, Vol. II., DeekSi/-

1852. Thysanocrinus — Hat; Ibid. p. 190.

1852. Dimerocrinus — d’OrBIeNny; Cours élément., Part IL, p. 142.

1855. Dimerocrinus — Roumur; Lethea Geognost. (Ausg. 3), p. 237.

1857. | Thysanocrinus — Prorer ; Traité de Paléont., Vol. IV., pp. 317 and 318, Plate C, Fig. 13.

Dimerocrinus
1859. Dimerocrinus — Murcurson ; Siluria (3d ed.), p- 5385, Plate 13, Figs. 4 and 5. Z
1862. | Ng) Nee amine — Dusarpry and Hurt; Hist. Natur. des Zoophytes, pp. 128 and 131.
Dimerocrinus
1863. Glyptaster — Hat; Trans. Albany Inst., Vol. IV., p. 202.
1873. Dimerocrinus — Sauter; Catal. Geol. Museum, Cambridge, p. 120.
1878. Glyptaster — Hatt; 28th Rep. N. Y. State Mus. Nat. Hist. (ed. 2), pp. 181 and 133.
1878. Hucrinus — Ancxttn; Iconogr. Crin. Suecie, p. 24.
Thysanocrinus )

1879. Pe HIG — Zitren; Handb. d. Paleont., Vol. I., pp. 868 and 375.

Dimerocrinus

Hucrinus

CULE) Wi ond Sp, § Revision Paleoer, Part AL, po 498 to 199. Ais di Pac
Tes Dimerocrinus TUL; p. 101.
Hucrinus

Thysanocrinus (syn. of Dimerocrinus).

Glyptaster )

1889. Hucrinus — 8. A. Minter; N. Am. Geol. and Palzontology.

Thysanocrinus y

Syn. Dimerocrinus Pups.
Syn. Glyptaster Wau.
Syn. Hucrinus ANGLIN.

Calyx subglobose, urn or bell-shaped; the rays marked by a more or less
conspicuous ridge; the general surface of the plates smooth or variously
ornamented. Infrabasals five, small, barely protruding beyond the column,
or entirely hidden by it. Basals five, four of them equal, angular above; the
fifth truncated, and supporting a large anal plate. Radials considerably
larger than the costals, their lower sides distinctly angular, the lateral faces
comparatively short. Costals two. Arms ten or twenty, rather strong and

THYSANOCRINIDZ. 191

biserial; pinnules long. The first interbrachial large, resting upon the
sloping upper corners of two radials and against the costals. There are two
plates in the second range, and often smaller ones above, which connect with
the plates of the disk. The anal side considerably wider; the first plate
large, hexagonal, resting upon the posterior basal; the second range contain-
ing three plates. Some species have an uninterrupted row of anal plates all
the way to the anal opening. Interdistichals generally represented and rather
large. Structure of the ventral disk and position of the anus only known
in one species. (See Thysanocrinus inornatus) column round or obtusely
pentangular.

Distribution. — Restricted to the Niagara group of America, the Wenlock
group of England, and its equivalent in Sweden.

Type of the genus. — Thysanocrinus hliformis Hall.

Remarks. — We have reduced Dimerocrinus, Glyptaster, Thysanocrinus
and Hucrinus to one genus, finding it utterly impossible to distinguish them
generically. There is some doubt, however, by what name the genus should
be known. The name Dimerocrinus was applied by Phillips to two species
from Dudley, D. decadactylus and D. icosidactylus. Both were figured but
not described, and the figures were poor and did not reveal the character-
istics of the genus. A meagre description was given by Miller, who men-

y)

tioned “a pelvis,” succeeded by 3 X 5 radials, and two series of arm plates.
D’Orbigny described it with three basals, succeeded by three rings of plates.
From such vague and incorrect descriptions, Hall could not suspect that
a species with five basals and infrabasals would be generically identical with
species described as possessing three basals and no infrabasals, and we believe
he was justified in proposing for his species a new genus. Pictet and
Dujardin and Hupé, who accepted both genera, placed them near together.
Zittel, however, even refers them to distinct families. We were the first to
point out the generic identity of Thysanocrinus with the forms which are
held to represent Dimerocrinus decadactylus and D. icosidactylus, but dis-:
criminated in favor of the older name Dimerocrinus, which we now think
was scarcely fair to Hall. Besides, we accepted Glyptaster and Hucrinus,
though with some hesitation, making the latter a subgenus of the former.
The name Glyptaster was proposed for a solitary specimen, described as
G. brachiatus, in which all the plates of the calyx were obscured by matrix,
but showing ten spreading biserial arms without visible pinnules, and it
was principally upon the absence of pinnules, it seems, that the genus was

192 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

founded. Through the kindness of Prof. Whitfield we were permitted to
examine this specimen, and to free it from the surrounding matrix, when we
found the pinnules well developed, and the plates of the calyx arranged as
in the typical form of Thysanocrinus (Plate XVII. Fig. 4).

Hiucrinus was separated from Thysanocrinus on account of having twenty
arms, as against ten in the latter. A bifurcation or two, more or less, cannot
be regarded as a good generic distinction, and we therefore place Angelin’s
species: Hucrinus interradialis, EL. levis, E. ornatus, EB. quinquangularis and
Li, speciosus, under Thysanocrinus ; but not his H. minor or EH. venustus, which
are types of a different genus. Ahodocrinus quinquelobus Schultze, which we
formerly placed under Hucrinus, is a Rhodocrinoid. Thysanocrinus (Rhodo-
crinus) mucrobasilis, and Th. (Rhodocrinus) pyriformis Billings, have been re-
ferred by us to Archwocrinus ; Th. immaturus to Idiocrinus. Thysanocrinus
aculeatus and Th. canaliculatus are named from arm fragments. Dimerocrinus
oligoptilis, and its synonym D. aptilis from Russia, belong to Tavocrinus.
Glyptaster pentangularis Hall is described from internal casts, and is, to say
the least, a doubtful species. Cyathocrinus waldronensis 8. A. Miller (Dimero-
crinus waldronensis W. and Sp.) cannot be identified from the description and
figure, but may be a young Thysanocrinus inornatus. Neither can Glyptaster
figant 8. A. Miller, which is described from a fragmentary specimen.

Thysanocrinus liliiformis Haz.

Plate XVHI. Fig. 4.

1852. Thysanocrinus liliiformis —Hati; Paleont. N. York, Vol. II., p. 188, Figs. la-/.

1881. Dimerocrinus lilitformis — W. and Sr.; Revision Palwocr., Part Il., p. 199, and Proceed. Acad. Nat.
Scho initen p78.

1889. Lhysanocrinus likiiformis —8. A. Mittur; N. Amer. Geol. and Paleont., p. 286.

Form of calyx apparently globose (the exact shape cannot be ascertained
owing to the somewhat crushed condition of the type specimen); the plates
ornamented by elongate nodes or interrupted strie, which give to the surface
a corrugated appearance.

Infrabasals small, scarcely visible in a side view. Basals nearly as large
as the radials; that of the anal side even larger and broadly truncate, the
others angular above. All plates in a radial direction provided with a low,
almost flat, obscure ridge, following the median line of the plates, and
covered by longitudinal strise which are continued into the arms. Radials
wider than long, but slightly angular below; their lateral faces short, leaving

THYSANOCRINIDZ. 193

a deep notch for the reception of the first interbrachials. Costals about of
equal size, considerably smaller than the radials. Arms ten, rather stout, the
two lower plates, which are included in the calyx, longer than the free plates ;
the latter short, arranged in two series, with a few cuneate interlocking joints
at the proximal end. Pinnules long, closely packed; composed of about six
remarkably long joints, which are thickest at the ends. First imterbrachials
as large as the radials; succeeded by two much smaller plates, and a few
still smaller ones above. Anal plate large, resting upon the truncated basal ;
succeeded by three plates in the second row. Structure of disk and position
of anal opening unknown. Column round, strong, the nodal joints wider and
longer, rounded at their edges.

florizon and Locality. — Niagara group; Lockport, N. Y.

Type in the Museum of Cornell University at Ithaca.

Thysanocrinus inornatus (Hatz).
Plate X VIII. Figs. 6a, 6, c, d, and XIX. Fig. 8.

1863. Glyptaster inornutus — aux; Trans. Alb. Inst., Vol. IV., p. 205; also 28th Rep. N. Y. State Mus.
Nat. Hist. (1879, Ed. IT., p. 184), Plate 14, Figs. 1-6; also 11th Rep. Geol. Surv. Indiana,
1881, p. 268, Plate 13, Figs. 1-6.

1881. Glyptaster inornatus — W. and Sp.; Revision Paleocr., Part IT., p. 196.

Calyx somewhat urn-shaped, the sides slightly convex; cross-section at
the top of the costals pentagonal, the angles corresponding to the rays;
across the distichals decagonal.

Infrabasals very minute, only the extreme points of the plates visible
beyond the column.* The ornamentation consists of single series of broad,
ill-defined radiating ridges or elevations. Some of the more prominent ones
follow the median line of the rays; while others take a lateral direction,
radiating from the centre of the plates to the margins, where they meet
with similar ridges from the interbrachials and basals.

Basals large, their lower margins thickened and expanded into nodes —
one to each plate — which stand on a level with the top stem joint, and
form a marked pentalobaté rim around it. Radials larger than the basals,
and wider than long. First costals considerably smaller and quadrangular,

* Prof. Hall described the ‘ basals”— the infrabasals of modern terminology — as “ much developed,
distinctly pentangular, with a double or triple node on each plate, and spreading beyond the column.” From
this description we suspect that the author took the nodes at the lower end of the dasais for plates, and over-
looked the small infrabasals which are rarely observed. We draw attention to this, because Hall, in compar-
ing this species with his “ @lyptaster”’ occidentalis, makes ‘“‘the greater development of the basal plates”

a specific distinction.
25

194 THE CRINOIDEA. CAMERATA OF NORTH AMERICA.

the second about as large as the first. Distichals four in the calyx, the rows
separated by from one to three interdistichals. The second distichal bears
a pinnule, which is for the most part incerporated into the calyx. Arms
unknown. Interbrachial spaces deeply depressed, so as to give to the calyx
at the arm bases a decidedly lobed appearance; the first plate nearly as
large as the radials, the two of the second row slightly smaller, followed by
much smaller ones in the third and fourth rows. Anal interradius consider-
ably wider, more depressed, and longitudinally divided by a row of elongate,
hexagonal anal plates, which form a conspicuous, rounded ridge reaching to
the anal opening. The plates at each side of the ridge consist of about the
same number, and are arranged in a similar manner as the interbrachials of
the four other sides. Anal opening subcentral, in the middle of a small pro-
jection. Ventral disk depressed. Orals pushed to the anterior side; four of
them much smaller, and arranged in a slightly curving row around the
posterior one, which rests against the anal protuberance. Covering pieces
of the ambulacra exposed at the surface; they consist of two series of very
short transverse pieces, alternately arranged, forming highly elevated ridges,
which gradually decrease in width as they approach the arms. Interambu-
lacral plates continuous with the interbrachials; they are small, irregular, and
form deep depressions upon the surface, which contrast strongly with the
elevations along the ambulacra. Column round; axial canal above medium
size; the outer edge of the top joint beautifully crenulated.

Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.,
and Racine, Wisc.

Types in the American Museum of Natural History, New York.

Thysanocrinus occidentalis Hatt.
seh LON HET SPNGS we kG.

1863. Glyptaster occidentalis— Hau; Trans. Alb. Inst., Vol. IV., p. 204 (Abstr. p. 10); also 28th Rep.
N. York State Mus. Nat. Hist. (ed. 2.), 1879, p. 133, Plate 13, Figs. 7-11; also 11th Rep.
Geol. Surv. Indiana, 1881, p. 262, Plate 12, Figs. 7-11.

1881. Glyptaster occidentalis — W. and Sp.; Revision Paleocr., Part II., p. 196.

A somewhat larger species than the preceding. Calyx broadly sub-
turbinate, abruptly spreading from the infrabasals; sides slightly convex ;
plates thin, The brachials of the calyx have on their outer or dorsal surface
a prominent rounded ridge, covered by indistinct longitudinal strie, and
their inner or ventral side has a deep, semi-circular groove. From both

THYSANOCRINID &. 195

sides of the ridge, small radiating lines pass out to the interbrachials, form-
ing triangles of whieh the intervening spaces are granular or covered with
fine striations. Stronger ridges pass from the radials to adjoining basals,
where two of them meet, and proceed as a single ridge to the infrabasals.
The latter ridges form around the column a sharply defined pentagon, whose
salient angles lie in a radial direction.

Infrabasals of moderate size, forming a narrow belt around the column,
which is visible in a side view. SBasals large, without nodes, rapidly spread-
ing. Radials larger than the costals, second costals narrower than the first.
Arms apparently ten, of which in mature specimens the six or seven lower
plates are incorporated; arm plates comparatively large, elongate, and
slightly wedge-form. Interbrachial plates large; arranged: 1, 2, 3, 3, with
a fifth row at the level of the arm bases. Anal interradius considerably
wider, having three plates in the second row, and four in the third ; —there
being no continuous row of anal plates or any sort of elevation. Interdis-
tichals five to seven. Ventral disk unknown. Column round; axial canal of
moderate size; pentalobate, the lobes directed radially.

Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.

Types in the American Museum Natural History, New York.

Ltemarks. — This species differs from Thysanocrinus inornatus in the larger
size of the intrabasals, the arrangement of the plates of the anal side, the
absence of an anal ridge, and in the general ornamentation of the plates.

Glyptaster occidentalis (var.) increbescens is, in our opinion, not sufficiently
distinct to be ranked as a variety.

Thysanocrinus brachiatus Hatt.

Plate XVIII, Fig. 7.

1852. Glyptaster brachiatus — Haut ; Paleont. N. York, Vol. IT., p. 187, Plate 41, Fig. 4.
1881. Glyptaster brachiatus — W. and Sp.; Revision Paleocr., Part II., p. 196 (Proceed. Acad. Nat. Sci.,
Phila., p. 370).

Calyx subglobose, having very strong radial ridges which bifurcate at
both ends. The lower branches proceed to the basals, and produce a well
defined pentagon, subdivided into five nearly equal fields by another row of
ridges; the upper branches follow the distichals, and pass into the arms.
The general surface without ornamentation.

Infrabasals small, but exposed beyond the column, and visible even in
a side view. Basals of moderate size. Radials deeply notched for the

196 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

reception of the first interbrachial, their lateral faces comparatively short.
Costals smaller than the radials. Arms ten, long, slender, somewhat flattened
on the back; the three proximal plates take part in the calyx, are curved
like the free plates, and are but little larger. The first free brachial is rectan-
gular, but the succeeding ones gradually turn into cuneate, interlock, and
finally change to biserial, with the upper and lower faces parallel. Pinnules
long and closely packed. Interbrachials: 1, 2, 2. Anal side wider, the
plates in three ranges, divided by a vertical row of anal plates; the lower
one of the same size as the radials; the others smaller, decreasing in size
upwards. Structure of the ventral disk, and form of the anus, unknown.
Column pentangular.

FHlorizon and Locality. — Niagara group; Lockport, N. Y.

Remarks. — Our description and figure are made from Hall’s typical
specimen * in the American Museum of Natural History, New York, after
clearing away the matrix, which brought to light the pinnules and exposed
the calyx plates. That Glyptaster 1s generically identical with Thysanocrinus,
nobody will doubt after comparing our figure (Plate XVIII. Fig. 7) with that.
of Thysanocrinus hluformis (Plate XVIII. Fig. 4).

(?) Thysanocrinus Halli (Lyon).

Plate XITI. Figs. 9a, b.

1861. Rhodocrinus Halli Lyon ; Proceed. Acad. Nat. Sci. Phila, p. 412, Plate 4, Figs. 5a, 0.

1881. (2) Rhodocrinus Halli — W. and Sv. ; Revision Paleocr., Part II., p. 212.

A large species. Calyx vasiform, a little wider than high, rounded below,
the sides convex; the interradial spaces slightly flattened, and the radial
plates rather sharply elevated, which gives to the cross-section a subpentan-
gular outline. Surface of the plates smooth, the suture lines distinct but not
channeled.

Infrabasals visible beyond the column; the columnar attachment large,
circular, its outer margin surrounded by well-defined radiating striz. Basals
large, a little convex; four of them pentangular or nearly so, the upper
angles almost meeting the interbrachials, sometimes slightly touching them ;
the fifth plate pentangular, broadly truncate above. Radials and costals
wider than high, gradually decreasing in size upwards. Of distichals only
two are preserved, and only in one division of two of the rays. There are only

* Figured by Hall. New York Paleont., Vol. Il., Plate 41, Fig. 4.

THYSANOCRINIDZ. 197

six interbrachials shown, arranged: 1, 2, 3; but there were probably others
above. The anal interradius apparently has two plates in the second row,
but the middle one of the next row extends half way down into the second.
FHHorizon and Locality. — Niagara group (?); near Louisville, Ky.
Remarks. — The type specimen, which was said to be in the Knapp col-
lection, cannot be found. ‘The two specimens here figured, from the.
Borden Institute of New Providence, Ind., are both somewhat abnormal and
quite fragmentary, and leave some doubt as to the generic relations of the
species. Not only is the anal plate followed by only two plates, but the first
regular interbrachial occasionally touches the basals. |

PTYCHOCRINUS W. and Sr. (Emend.).

1885. W. and Sp.; Revision Paleocr., Part III., p. 99; also Proceed. Acad. Nat. Sci. Phila., p. 321.
Syn. Glyptocrinus (in part) — Harn, 1872, 24th Rep. N. York State Cab. Nat. Hist., p. 207; also
Miller and Dyer, 1878, Journ. Cincin. Soc. Nat. Hist., Plate 1, Fig. 10.
Syn. Gaurocrinus (in part) —S. A. Minter; 1888, Journ. Cincin. Soc. Nat. Hist., p. 228; and 1889
N. Amer. Geol. and Paleont., p. 276.

Specimens small; in form and mode of ornamentation resembling Glypto-
crinus. ‘The radial plates marked by a well defined ridge, which passes up
and down the median line of the plates, giving to the interradial spaces
a somewhat depressed appearance.

Infrabasals five, small, but generally visible beyond the column. Basals
five, large; four of them hexagonal, the posterior one heptagonal, truncate
above. Radials and costals of nearly equal size. Costals two. Distichals
varying in number, curved like arm plates. Arms ten to twelve, rather
delicate, and uniserial. Pinnules strong. Interbrachials and interdistichals
not numerous, the plates definitely arranged. Posterior side with a longi-
tudinal row of anal plates forming a ridge. The first anal plate in a line
with the radials, and always succeeded by a row of three plates, — a second
anal and two interbrachials. Structure of ventral disk imperfectly known.
Column cylindrical; axial canal large, pentalobate, the lobes directed
radially.

Distribution. — Restricted to the Trenton and Hudson River eroups of
America.

Type of the genus: Ptychocrinus splendens (8. A. Miller).

Remarks. — Ptychocrinus differs from Thysanocrinus in having delicate
uniserial arms; from Reteocrinus in the definite arrangement of its inter-

198 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

radial plates, and in having these resting against the radials; from Glypto-
crinus in having infrabasals, and an anal plate in contact with the basals.

S. A. Miller, in 1883, arranged a number of species under a proposed
genus Gaurocrinus, which, like his Glyptocrinus, embraces a variety of forms,
containing species of Seteocrinus, Glyptocrinus, and a third form, for which
we proposed the name Péychocrinus, with Miller’s “ Gaurocrinus”’ splendens
as type. We should have preferred to accept for the latter Miller’s name
Gaurocrinus, if he had not expressly selected as the type of his genus Hall’s
“ Glyptocrinus”’ Oneal, which is a typical Reteocrinus.

“ Glyptocrinus”’ priscus K. Billings, which Walter R. Billings supposed to
have infrabasals, and which we placed provisionally under Ptychocrinus, has
since been referred by us to Periglyptocrinus.

Ptychocrinus splendens (S. A. Mizizr).
Plate X VILL, Figs. 8a, b.

1883. Gaurocrinus splendens —S8. A. MitteR; Journ. Cincin. Soc. Nat. Hist., Vol. VL., p. 230, Plate 11,
Tritech pala splendens — W. and Sv.; Revision Paleocr. Part III., p. 101.
1889. Gaurocrinus splendens —S. A. Mittur; N. Amer. Geol. and Palexont., p. 247.

Calyx elongate, obconical; cross-section pentangular with concave sides.
The plates of the rays folded along the median line, so as to form broad,
rounded ridges, from which branches proceed to the basals, meeting there
smaller ridges from the infrabasals. Surface of plates studded with rather
conspicuous, elongate tubercles, of which a transverse one passes over the
suture of two adjoining radials without touching the radial ridges. The first
interbrachials have seven tubercles, a central one surrounded by six others ;
the latter occupying the outer margins, resting in part upon adjoining plates.
The higher interbrachials have only a central tubercle.

Infrabasals small, only their extreme upper points visible in a side view.
Basals large, higher than wide ; the posterior one broadly truncated. Radials
a little larger than the basals, about as long as wide. First costals some-
what longer than wide, and hexagonal; the upper angles of the axillaries not
truncated, the interdistichals not touching them. Distichals twelve to four-
teen, of which the three to four lower ones take part in the calyx, the
succeeding ones being free arm plates; the upper one gives off two arms,
which remain simple. Arms delicate, gradually tapering to a slender point;
composed of a single series of rather long, wedgeform joints. Pinnules

THYSANOCRINID &. 199

stout, widely separated. ‘The first pinnule, which is fixed, more erect, and
stronger than the others, is given off from the outer side of the second dis-
tichal, the second from the inner side of the fourth plate; all succeeding
plates except the axillaries being pinnule-bearing. Interbrachial spaces
deeply depressed; the first plate large, followed by two smaller ones, and
these by three in the third row, and others above. Anal side wider, some-
what angular along the median line; the first anal plate resting upon the
truncate basal. Interaxillaries three, in two ranges; each one marked by
a small, central tubercle. Construction of disk and form of anus unknown.
Column round, slightly tapering; the nodal joints at their outer edges
faintly crenulated ; axial canal large, pentalobate.

Horizon and Locality. — Trenton group; Cape Girardeau, Mo., and
Alexander Co., III.

Types in the collection of 8. A. Miller, Cincinnati.

Ptychocrinus parvus (Ha411).
Plate XVIII, Figs. La, b and 2.

1872. Glyptocrinus parvus— Haun; Descr. New. Crin., e¢c., Plate 1, Fig. 17 (without description); also
24th Rep. N. Y. State Cab. Nat. Hist., p. 207, Plate V., Fig. 17.

1873. Glyptocrinus parvus —Mxrx; Paleont., Ohio, Vol. L, p. 36, Plate 2, Figs. 4a, 4.

1879. Glyptocrinus angularis— MitieR and DyER; Journ. Cincin. Soc. Nat. Hist., Plate 1, Fig. 10.

} Glypiocrinus parvus a and Sp.; Revision Paleocr., Part IT., pp. 188, 189; and Amer.

1881. 4 Glyptocrinus anguluris Journ. Sci., 1883, Vol. XXV., pp. 255-268.

Reteocrinus gracilis
1881. Reteocrinus gracilis — WETHERBY; Cincin. Journ. Nat. Sci., Vol. IV., Plate 2, Fig. 2.
1883 Glyptocrinus parvus } — 8. A. Miter, Journ. Cincin. Soc. Nat. Hist., Vol. VI., pp. 224 and
, i Gaurocrinus angularis 229; and 1889, North Amer. Geol. and Paleont., pp. 247 and 248.

1885. Py chocrinus ras ae ; — W. and Sp. ; Revision Paleocr., Part III., p. 100.
Ptychocrinus anyularis

Of small size. Calyx obconical, with slightly convex sides; the radial
plates marked with prominent rounded ridges, which extend to nearly the
full width of the plates; interbrachial spaces flat, plates very slightly con-
vex and without ornamentation.

Infrabasals minute, only the outer angles of the plates visible beyond
the column. Basals large, higher than wide; their surfaces strongly convex.
Interbasal sutures deeply depressed, and the depression continued to the
radials, of which the lower ends bend inward. Radials somewhat larger than
the first costals. The second costals of similar form to the radials, only
reversed, being angular above instead of below. Distichals 2 X 10, about as
wide as long, the upper one axillary. Arms four to the ray, free from

200 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the first or second palmar; composed of wedgeshaped joints, which are as
long as wide, and rounded on the back. Pinnules stout, well separated.
Interbrachial spaces depressed, flat; the first plate of the regular sides as
large as the costals; followed by two plates in the second row, and a number
of others, which, though well defined, are more or less irregular in their
arrangement. Anal side wider, divided by a longitudinal row of hexagonal
plates; the plates at each side of this row about as numerous as the whole
series of plates of the four regular sides. Interaxillaries five or more. Con-
struction of the ventral disk unknown. Column round; axial canal of
medium size.

LTorizon and Locality. — Hudson River group; Cincinnati, O.

feemarks. — Glyptocrinus (Gaurocrinus) angularis Miller, and Reteocrinus
gracilis Wetherby, are undoubtedly synonyms of Hall’s “Glyptocrinus” par-

vus. Mr. Miller was good enough to send us two specimens, which he had

himself identified as “ Gaurocrinus” angularis, and Mr. Vaupel kindly loaned
us the type of Reteocrinus gracilis. Both specimens are figured on Plate
XVUI., and a comparison of them with Hall’s type of “ Glyptocrinus” parvus
will prove that they all represent one species.

HYPTIOCRINUS W. and Sp.
(vrrvos, bending back; xpévov, a lily).
1892. W.and Sp.; Am. Geologist, Vol. X. (September), p. 188.
Syn. Cyphocrinus 8. A. Mrtrur (October 26, 1892); Adv. Sheets, 18th Rep. Geol. Surv. Indiana,
p. 56. }

Name referring to the character of the arms, which hang downward.
Calyx depressed, wheel-shaped. JInfrabasals five, small. Basals five, four of
them equal, angular at the upper end; the posterior one truncated by
the anal plate. Radials comparatively small, all heptagonal. Costals two.
Fixed brachials rather large, except the first costals, which are quite short,
and quadrangular. Distichals one, the distal face broadly truncated; fol-
lowed by several sharply cuneate pieces, which interlock, and of which the
two ‘or three proximal ones (in the type) take part in the calyx. Arms
stout, probably biserial, and pendent, to judge from the arm openings, which
are directed obliquely downward. First interbrachials of the regular sides
very large, succeeded by several rows of smaller pieces. Anal plate touching
the basals and rising above the radials; supporting three much smaller
plates and others above. Ventral disk depressed ; the posterior oral and the

THYSANOCRINID &. 201

radial dome plates spinous; the anus excentric and at the top of a large
protuberance.

Instribution. — So far as known, restricted to the Niagara group of
Indiana.

ftemarks. — The genus has its closest relations with Zhysanocrinus, from
which it differs in the depressed form of the calyx, the pendent arms, and
in the spine-bearing disk.

Hypticcrinus typus W. and Sp. (nov. spec.).
Plate XIX, Figs. 6a to e.

1892. W. and Sp.; Am. Geologist, Vol. X. (September), p. 1388.
Syn. Cyphocrinus Gorbyt 8. A. Mitirr (October 26, 1892). Adv. Sheets 18th Rep. Geol. Surv.
Indiana, p. 51, Plate 7, Figs. 14, 15, 16.

Specimens of medium size. Calyx wheel-shaped, nearly once and a half
as wide as high. Dorsal cup broadly obconical to the top of the costals, then
flanging outward and somewhat downward. Arm regions not lobed, but the
upper margins of the interbrachial and interdistichal spaces formed into
sharp edges by means of corresponding depressions in the dorsal cup and
tegmen. Costals and distichals marked by rounded, longitudinal ridges,
following the median line of the plates. Ventral disk a little higher than
the dorsal cup, its lateral margins slightly bulging, the lower edge some-
what projecting over the upper margin of the dorsal cup. Plates flat, their
surface in well preserved specimens densely covered by fine granules,

Infrabasals small, hidden by the column; forming a flat pentagonal disk.
Basals rather large, about as wide as long; curving abruptly upwards; the
posterior one slightly truncated at the upper end; the interbasal suture lines
distinctly grooved. Radials twice as wide as long, their proximal ends dis-
tinctly angular. First costals much shorter and narrower than the radials;
quadrangular. Second costals longer and a little wider than the first; their
lateral faces short; the sloping upper faces making a right angle. First
distichals as large as the axillary costals, followed by two or three cuneate
plates in the calyx, which slightly interlock. Structure of the free arms not
observed, but they were apparently biserial and quite heavy and pendent.
First interbrachials of the regular sides the largest plates of the calyx, rising
to the height of the first distichals, and being succeeded by two rows of two
plates each. The anal plate a little higher than the radials, supporting three,

two, and two,smaller plates. Interdistichals one, small. Posterior oral nearly
26

ae THE CRINOIDEA CAMERATA OF NORTH AMERICA.

central, large, and extended into a heavy, short spine; the other four orals
proportionally small and almost flat. Radial dome plates represented by
plates of a first and second order, those of the latter by two or three plates
to each division, alternately arranged; all large and spine-bearing. The
spines near the outer margins of the disk project obliquely outward, and are
visible from a dorsal view of the calyx. Interambulacral plates numerous, of
the size of the smaller orals, and irregularly arranged. Anus excentric, at
the top of a large ovoid protuberance, rising conspicuously above the general
plane of the disk.

Horizon and Locahty.— Niagara group; St. Paul, Shelby Co., Ind.

Type in the collection of Wachsmuth and Springer.

IDIOCRINUS W. and Sp. (nov. gen.).
(idtos, peculiar; xptvov, a lily).
1892. W. and Sp.; Am. Geologist, Vol. X. (September), p. 135.
Syn. Gazacrinus 8. A. Mitten (October 26, 1892); Adv. Sheets, 18th Rep. Geol. Surv. Indiana,
p- 49.

Infrabasals apparently five, extremely small, placed at the bottom of
a more or less deep concavity, and completely hidden by the column. Basals
five, very large; the posterior one truncated by the anal plate. Radials quite
large; three of them heptagonal, the two adjoining the anal side hexagonal.
Costals two, very short; the first quadrangular; the second pentangular,
the upper angle rather obtuse. Distichals two in the calyx; short. Inter-
radial areas at all sides composed of a single large plate, which rises to the
top of the dorsal cup ; that of the anal side resting upon the basals, the four
others upon the sloping upper faces of the radials. Ventral disk quite vari-
able in form; covered by a large, probably anchylosed oral pyramid. The
ambulacra tegminal; the interambulacral spaces formed of single plates,
of which the posterior one is perforated by the anus, which is excentric.
Arms and column unknown.

Type. — Idrocrinus elongatus.

Distribution. — So far as known, restricted to the Niagara group of
America.

Remarks. — This genus differs from all other dicyclic Camerata in having
a single plate in the anal area, in its central, undivided oral pyramid, and in
having but one interambulacral plate to each side of the disk.

THYSANOCRINID.2. 203

Idiocrinus elongatus W. and Sp.

Plate X VITI, Figs. Sa to c.

1892. W. and Sp., Am. Geologist, Vol. X. (September), p. 136.
Syn. Gazacrinus inornatus 8. A. MittER; Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 49, Plate
5, Figs. 9, 10, 15, 16, 17 (published October 26), 1892.

A small species. Calyx obconical; the ventral disk almost on a level
with the upper margins of the dorsal cup; the cup deeply excavated at the
bottom, the basals forming a large funnel-shaped pit. Plates without orna-
mentation and flat, except the radials, which are a little convex, and rise
slightly above the plane of the cup. Suture lines not grooved.

Infrabasals minute, const#tuting the bottom of the basal concavity. Basals
extremely large and elongate, the lower end curving abruptly inward, and
forming a sharp edge around the bottom of the calyx; the exposed part of
the plates rising to more than one third the length of the dorsal cup. Radi-
als once and a half as wide as long, distinctly angular at their lower faces ;
the two posterior plates hexagonal, being distinctly truncated by the anal
plate. Costals together less than half the size of the radials; the first linear;
the second a very little longer, and its upper angles quite obtuse. Dis-
tichals two, somewhat higher and wider than the costals; the upper semi-
free. Interbrachials one, those of the four regular sides resting upon the
deeply sloping sides of the radials, the anal one upon the narrowly truncated
basal; all extending to the upper end of the calyx, and all longer than wide.
Arms apparently ten, their dorsal faces flat. |

Ventral disk but slightly elevated, consisting of five large, oblong, trian-
gular plates, one to each area, which do not meet in the centre, but leave
a moderately large, pentalobate open space at the summit. The sides at the
lower ends of the plates to two thirds their length are not in contact, but
leave elongate spaces, which were apparently occupied by the ambulacra;
the lateral edges are slightly serrated, and bend outward for the reception of
the covering pieces. Near the summit, the plates meet in a similar manner
as the deltoids of the Blastoid genus Pentremites, by means of lateral pro-
cesses, and these are converted into grooves which communicate with the
vacant space in the centre. The structure is such as to indicate that the
ambulacra followed these grooves before entering the peristome, and that
the centre was covered by an oral pyramid, as in the allied Idocrinus ventri-
cosus, in which the pyramid was found in position. The posterior inter-

204 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

ambulacral plate is somewhat wider, and perforated by the anus to such an
extent as to leave only a narrow skeleton at the lateral margins.

Gazacrinus Miller is identical with Jdiocrinus, the latter name having
priority. Miller described the genus as monocyclic instead of dicyclic, and
he speaks of a “ vault sustained by a specialized frame work with ambulacral
canals connecting the arms with the central orifice.” This is misleading, for
the plates exposed at the oral surface are true plates of the disk, and the
open spaces which appear in the specimens were closed by orals and ambu-
lacral plates. There was no central orifice, the peristome being covered as
in all other Camerata.

Horizon and Locality. — Upper part of Niagara group; St. Paul, Shelby
Co., Ind. |

Type in the collection of Wachsmuth and Springer.

Remarks. — Mr. Miller, in describing the arm plates of this species,
states they are long, and their edges “are transversely serrated on the
inside, half the depth of the plates.’ We observed this structure in our
specimen, and were at first inclined to regard the edges as formed of small
side pieces, and so described them in the “ American Geologist.” Since then
on further cleaning the specimen, we have become convinced that the parts
in question are mere extensions of the arm plates, which are short, and that
the line of union is slightly gaping to facilitate motion.

Another point in Miller’s description should be noticed. He says: “There
are three longitudinal furrows on the inside of each radial series, shown at
the top of the secondary radials; this gives fifteen furrows at the top of the
secondary radials, one in the middle of each plate, and the other at the

9?

suture;” and he alludes to this as a peculiarity entirely new to him. He
evidently misunderstood the structure, for our specimen clearly shows but
one furrow to each brachial, of which those from the distichals unite upon
the axillary costals at the extreme edge of the disk. The supposed marginal
furrows do not enter the disk, and are mere depressions at the lateral margins
of the distichals, formed by the highly projecting serrated edges of the

ambulacral furrows at each side.

THYSANOCRINID.ZA. 205

Idiocrinus ventricosus W. and Sp. (nov. spec.).
debate Xo Vl igs Oa

A very small species. Calyx as wide as high; height of dorsal cup about
equal to that of the tegmen; the former bowl-shaped, the cup obtusely
pyramidal. Plates smooth; the radials and costals somewhat longitudinally
convex, causing a small depression of the interbrachial spaces. Suture lines
slightly grooved.

Infrabasals extremely small, and completely covered by the column ;
placed at the bottom of a small circular cavity, formed by the lower ends of
the basals. Basals of moderate size, their lower ends incurving and forming
the sides of the concavity, their upper angles slightly bending upwards.
Radials once and a half as large as the two costals together, and twice as
wide as long; three of them heptagonal, the two posterior ones hexagonal.
First costals quadrangular, much narrower than the radials, and three times
as wide as long; the second of nearly the same width as the first, but longer.
Distichals narrower and shorter than the second costals. Interbrachials large,
subelliptical; that of the anal side a little wider, and slightly truncating the
posterior basal. Oral pyramid convex, a very little tumid, extremely large
for the size of the species, perfectly closed at the summit, and the inter-oral
sutures obsolete. ‘The outer surface of the pyramid is covered with well
defined radiating ridges, which proceed from the middle of the plate to the
outer margins, increasing in height and width as they pass outward. Ten of
these ridges are prominent, and project outward around the circumference,
thus giving to the plate the aspect of a ten-rayed star. The inner floor is
excavated centrally, and there are five deep grooves passing out in a radial
direction. “The interambulacral plates long, slender and cuneate, attached
with their sharp upper ends to the inner margins of the orals. They project
outward so as to form at their sides open spaces for the reception of the
ambulacra. Other parts unknown.

Horizon and Locality.— Upper part of Niagara group; near St. Paul, Ind.

Type in the collection of Wachsmuth and Springer.

ftemarks. — The oral pyramid of this species, which is found occasionally
detached from the body, was regarded by Miller, Benedict, and ourselves, as
probably representing the ventral structure of a Pisocrinus. This appeared
quite plausible, as it was expected from analogy that in Pisocrinus, as in the

206 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

allied Symbathocrinus, Allagecrinus and Haplocrinus, the ventral disk consisted
of orals only, and the plate fitted approximately upon the cup of one of the
species, which occurs in the same bed. A well preserved oral pyramid of this
genus is figured on Plate IIL. Fig. 15, which may belong to this species.

(?) Idiocrinus immaturus (Hatt).

Plate X VILL, Figs. 10a, b, c.

1851. Thysanocrinus immaturus — Wau; Paleont. N. York, Vol. IL, p. 191, Plate 42, Figs. 4a-f

This small species, so far as known, in its general habitus so closely
resembles Jdiocrinus that we are inclined to regard it as belonging to this
genus. It is more depressed than L. edongatus, the sides of the cup are more
convex, the base more concave, and the costals proportionally higher.
Neither arms nor ventral disk are known.

forizon and Locality, — Niagara group ; Lockport, N. Y.

(?) Idiocrinus tennesseensis (WorTHEN).

Plate X VILL, Fig. 11.

1890. Centrocrinus tennesseensis — WortHENe Geol. Rep. Illinois, Vol. VIIT., p. 95, Plate 14, Fig. 1.

Dorsal cup apparently obconical. Plates almost flat, and without orna-
mentation; suture lines indistinctly grooved.

Infrabasals three, forming a slightly projecting rim around the bottom of
the calyx. Basals rather large, fully as high as wide, three of them pentan-
gular, the others being covered by matrix. Radials one fourth wider than
long, the lower faces distinctly angular. Costals two, narrower than the
radials; the first quadrangular and extremely short, more than three times
as wide as long; the second a little longer than the first, and obtusely an-
gular above. Distichals two in the calyx; the proximal one as long as, or
longer than, the axillary costal; the second a little wider than the free arm
plates, but not higher. Arms two from the calyx, moderately stout; com-
posed of rather long, quadrangular joints, branching (at least in one of the
arms) from the fourth free plate. Interbrachials, as seen at two sides, subel-
liptical, extending to the full height of the first distichals, slightly grooved
longitudinally at the median line. Stem round, the nodal joints high, the
outer faces convex and somewhat projecting. All other parts of the species

unknown.

THYSANOCRINID. 207

Horizon and Locality. — Niagara group; near Clifton, Wayne Co., Tenn.

Type in the Illinois State collection, Springfield.

Remarks. — We refer the above species to this genus with considerable
doubt, although it has close affinities with it in the structure of the dorsal
cup; but it differs from the typical form in having three rather large,
projecting infrabasals — that having apparently five — and the plates are
completely covered by the stem. Whether it has the same sort of ventral
disk cannot be ascertained from the specimen, nor do we know anything
about the structure of the anal side. Worthen referred the species to the
monocyclic genus Centrocrinus, and apparently took the infrabasals for a
projecting rim of the basals.

LAMPTEROCRINUS Roemer.

1860. F. Rozmzr; Silur. Fauna. West. Tenn., p- 37.
1863. Hati; Trans. Albany Institute, Vol. IV., p.:202.
1866. Suum.; Trans. Acad. Sci. St. Louis (Cat. Paleeoz. Foss., p. 378).
1868. Harn; 20th Rep. N. York State Cab. Nat. Hist., p. 328.
1879. Zirren; Handb. der Paleontologie, Vol. L, p. 375.
1881. W. and Sr.; Revision Paleoer., Part II., p. 199 (Proceed. Acad. Nat. Sci., Phila. 1881, p. 373).
1882. Dx Lorion; Paléont. Francaise, Tome XI. (Crinoides), p. 59.
1885. W. and Sp.; Revision Paleocr., Part III., p. 101 (Proceed. Acad. Nat. Sci. Phila., p. 323).
1889. S.A. Minter; N. Amer. Geol. and Palsont., p. 257.
Syn. Balanocrinus — Troost, 1850 (not Agassiz, 1846), Cat. Foss. Tenn., p. 60.

Calyx unsymmetrical, elongate-obpyramidal, the rays formed into tubular
appendages bearing the arms. Ventral disk greatly inflated posteriorly, and
extended into a large tube, pushing the centre of radiation to the anterior
side of the calyx. |

Infrabasals anchylosed, forming a large spreading cup. Basals five. ver

Wi ) Ss ge sp g cup ’ Wi
large, four of them equal, angular above; the posterior one considerably
higher, and truncated at the upper face. Radials very large. Costals two,
the first hexagonal, the second supporting at one side a lateral arm, at the
other the distichals. The higher orders of radials, from the distichals up,
are curved like arm plates, and with the covering pieces form a rigid tube,
from which small arms are given off alternately at intervals. In the typical
species the distichals consist of three short pieces, the upper one axillary,
supporting at one side the second arm, at the other the palmars, of which
only the first plate has been observed.

Interbrachials large, passing uninterruptedly from the dorsal cup into

the tegmen; there is one plate in the first row, followed by two in the

208 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

second. At the anal side, which is somewhat wider, the first anal plate
rests upon the basals, and supports three small plates in the next range,
which are succeeded by three plates, and others above. Ventral disk asym-
metrical, strongly bulging at the posterior side, and supporting a large
central tube. Orals large, excentric.

Column pentangular; axial canal small.

Mistribution. — Niagara group of America.

fvemarks.— We only recognize Roemer’s typical species. Hall’s Lamp-
terocrinus iflatus (Balanocrinus sculptus Troost MS.) has never been described,
and the figure* was made from a natural cast, of which the anal side is
not seen. Lampterocrinus parvus t was also described from very imperfect
material.

Lampterocrinus, by its asymmetry, and the position of its anal tube, is

very closely allied to Siphonocrinus ; but it is readily distinguished by its arm
structure.

Lampterocrinus tennesseensis Roemer.
Plate el TG sah On), Od

1860. Rormer; Silur. Fauna West. Tenn., p. 37, Plate 4, Figs. la, 0.
1881. W. and Sp.; Revision Paleoer., Part II., p. 201.
Syn. Bulanocrinus sculptus Troost (Catalogue name).

Calyx elongate, more than once and a half as high as wide, decidedly
asymmetrical. Dorsal cup higher than wide, spreading abruptly to the
middle of the radials, where it attains almost its full width; cross-section
pentangular. Plates convex, their surface ‘ornamented with conspicuous
radiating ridges, passing from the centre of one plate to the centre of an-
other — there being one ridge for each side of the plates — dividing the
surface into well marked, deeply impressed areas. The ridges are angular,
knife-like, their edges more or less serrated; those from the infrabasals to
the basals, and thence to the radials, and between radials and costals, and
to the first interbrachials, are more prominent than those of the higher in-
terbrachials, but the centre of the latter is raised into a small, sharp node.

Infrabasals five, completely anchylosed, forming a small cup; the suture
lines obliterated by extraordinary secretion of calcareous matter, and raised
into sharp ridges, passing out from the angles of the column to the lower

* 98th Rep. N. York State Museum Nat. Hist., Plate 10, Fig. 6.
+ llth Rep. of Geol. and Nat. Hist. State of Indiana, Plate 15, Fig. 6.

THYSANOCRINID 2. 209

angles of the basals; the truncated part sharply pentangular, and com-
pletely occupied by the column. Basals very large, as long as wide, and
angular above; the posterior one considerably longer, and its upper face
truncated. Radials fully twice as large as the first costals, and somewhat
larger than the basals. Second costals smaller than the first, and facing out-
ward, the sides slightly incurving; their sloping upper faces unequal, the
shorter side bearing a lateral arm, and the longer one a row of distichals.
The higher orders of brachials, which are roofed over by rigid covering
pieces, are formed into tubular appendages, from which at intervals armlets
are given off alternately. The second arm starts from the third distichal,
and it is probable that each succeeding arm is given off from the third plate
of successive brachials. ‘The appendages are preserved in the specimens
only to the first palmar. Interbrachials: 1, 2,3; the first as large as the
first distichal; those of the second and third row much smaller. Anal side
a little wider and bulging from below the base of the free rays upwards; the
anal plate, which is even larger than the first radials, is followed by three not
very large plates, and these by successive rows of three plates each, which
pass into the anal tube; the plates of the middle row are marked by a con-
spicuous angular ridge, which extends from the angles of the column to the
base of the anal tube, and runs parallel to the ridges upon adjacent radials
and costals. Ventral disk elevated; composed of few rather large, con-
vex or slightly nodose plates, which are continuous with the interbrachials.
The anal tube is constructed of similar somewhat smaller plates; it is cen-
tral, but bends abruptly to the anterior side of the calyx; its length not
known. Orals not larger than the other plates of the tezmen; they are
excentric, being pushed completely to the anterior side. Column near the
calyx sharply pentangular, with a small node at the angles of each joint.
Horizon and Locality. — Upper part of the Niagara group; Decatur and
Wayne Cos., Tenn. — | |
Types in the Mineralogical Museum at Breslau, Germany.

SIPHONOCRINUS &. A. Mittzr (redefined, W. and Sp.).

1888. Mitiur; Amer. Geologist, Vol. I., p. 263; and 1889, Amer. Geol. and Paleont., p. 281.
Syn. Eucalyptocrinus (?) —McCuzsyny, 1859; Descr. New Species, p. 95.
Syn. Glyptocrinus — McCuusney; Chicago Acad. Sci., 1868, Vol. I., p. 23; and Hall, 1861; Rep.
of Progr. Geol. Surv. Wise. for 1860, pp. 21 and 22; and Hall, 1867; 20th Rep. N. York State
Cab. Nat. Hist., p. 328.

27

210 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Known only from natural casts and impressions from the natural moulds
in the rock. Calyx large, oblong, its form extremely asymmetrical. Dorsal
cup deeply depressed interradially, the rays projecting so as to give to the
calyx a strongly lobed outline. Ventral disk generally as high as the dorsal
cup; its posterior side inflated from below the brachial zone to the summit,
forming a conspicuous helmet-shaped protuberance, which at the arm regions
not only occupies the whole width of the posterior interradius, but encroaches
largely upon the left posterior ray, not involving the ray to the right, from
which it is separated by a deep groove. This protuberance, as seen from the
casts, grows narrower at the summit, and the upper part either bends directly
upwards, in the form of a central tube, or is continued across the summit to
the anterior side, where it opens out to the exterior at — or even beneath —
the arm bases.

Infrabasals five, elongate, variable in form; four of them, as a rule,
angular above; the posterior one broadly truncate, supporting the first anal
plate. Radials decidedly angular below. Costals two; the first generally
hexagonal. Distichals varying from two to four in different rays, there being
generally two in the anterior rays against three or four in the posterior ones.
The interbrachials, which are numerous and of rather large size, pass unin-
terruptedly from the dorsal to the ventral side of the calyx, and are in
contact with the interambulacrals. The first plate of the regular sides rests
deeply between the sloping upper faces of two radials, its lower angle excep-
tionally touching the basals; there being two plates in the second row, and
generally three in the third. Anal side wider and larger throughout; the
first anal plate placed upon the truncated basal, supporting three plates in
the first row, and three or more in all succeeding rows. The ventral surface
of the casts is marked by well defined ridges, converging from the arm bases
to a pentangular, somewhat elevated space behind the anus, the centre of
which is represented by a small cone. These converging ridges are open
grooves or galleries at the inner floor of the disk for the reception of subteg-
minal ambulacra, and the pentangular space in front of the anus represents
the peristome, of which the mouth occupies the median part. Anal opening
placed at the distal end of a tube, which is either erect and passes outward at
the summit of the disk, giving to the mouth an excentric position, or is con-
tinued beneath the plates of the disk to the anterior side of the calyx, where
it opens out interradially or interdistichally at — or below — the arm regions.
Ventral disk covered with comparatively large plates, forming a sort of vault,
in which neither orals nor covering pieces can be distinguished.

THYSANOCRINID 2. Di

Distribution. — Only known from the Niagara group of America.

Type of the genus. — Siphonocrinus armosus (McChesney).

Remarks. — This genus, by its asymmetrical form, is closely allied to
Lampterocrinus, from which it differs as stated under that genus.

S. A. Miller, in proposing the genus, described it as having three infra-
basals. We have examined more than eighty specimens, from the collections
of Mr. W. C. Egan of Chicago, and Mr. F. A. Greene of Milwaukee, and
satisfied ourselves that they all have five plates in the proximal ring.

In studying the figures, it must not be overlooked that most of them
represent natural casts of the internal surface of the test, the plates them-
selves having been dissolved by chemical action, and that on these all eleva-
tions represent depressions of the inner floor. Only in the figures made
from casts in the natural moulds does the surface represent the true external
surface of the plates.

Siphonocrinus armosus (McCuzsyey).
Plate XIX. Figs. 8a, b, c.

1859. Hucalyptocrinus armosus —McCursney; Descr. New Paleoz. Foss., p. 95.

1867. (?) Glyptocrinus armosus — McCuxsney; Trans. Acad. Sci. Chicago, p. 23, Vol. I., Plate 7, Figs.
6a, 0.

1881 (?) Glyptaster armosus — W. and Sv.; Revision Paleocr., Part II., p. 196.

1882. Glyptocrinus armosus — WHITFIELD; Geol. Surv. Wis., Vol. IV., p. 284, Plate 16, Fig. 11.

1888. Siphonocrinus armosus —S8. A. MitueER; Amer. Geologist, Vol. I., p. 264.
Syn. Glyptocrinus siphonatus —Hatu; Rep. of Progr., Geol. Surv. Wis., p. 22; and 20th Rep.

N. York State Cab. Nat. Hist., Plate 10, Fig. 11.

A large species, only known from internal casts. Calyx subovoid. Dorsal
cup generally higher than the ventral disk, its sides decidedly convex, sub-
elobose ; section across the arm bases slightly lobed.

Infrabasals small, forming a shallow cup. Basals as large as the first
costals, the upper angles unusually sharp, exceptionally touching the inter-
brachials. Radials larger than the costals; the first costals larger than the
second, and hexagonal. Distichals and palmars in series of two each. Arms
four to the ray, their structure unknown. The plates of the regular inter-
brachial spaces generally consist of four rows, arranged: 1, 2, 2, 3; the first
plate as large as the first costal. Anal interradius considerably wider, greatly
bulging from below the arm bases; the first anal higher than the radials,
succeeded by three plates in the second and third rows, and numerous irre-
gular, rather large plates at the disk. The latter plates together form

a trumpet-shaped inflation, apparently representing a subtegminal anal tube,

212 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

which crosses the mouth, overlies the upper part of the anterior ambulacra,
and is continued subtegminally all the way to the anterior side of the calyx,
even beyond the arm regions, where it bends outward. The ambulacra, as
seen from the converging ridges upon the casts, vary considerably in length
in some of the rays, the posterior ones being much longer, especially those
to the left, which are quite conspicuously displaced. The excentric position
of the mouth, and the irregular arrangement of the ambulacra of this species
remind us of the Comatulid genus Actinometra.

Horizon and Locality. — Upper part of Niagara group; Racine, Green-
field and Waukesha, Wisc., and Chicago, IIls.

Siphonocrinus nobilis (Hatz).
Plate XIX. Figs. La, b, and 2a, }, ce.

1861. Glyptocrinus nobilis — Hain; Rep. Progr. Geol. Survey Wisc., p. 21; also 1867, 20th Rep. N. York
State Cab. Nat. Hist., Plate 10, Figs. 9, 10.

1881. (2) Glyptocrinus nobilis — W. and Sp.; Revision Paleocr., Part IT., p. 189.

1882. Glyptocrinus nobilis —- WuiTFIELD; Geol. Wisconsin, Vol. IV., p. 282, Plate 16, Figs. 9, 10.

1888. Siphonocrinus nobilis —S. A. MitueR; Amer. Geologist, Vol. I., No. 5, Fig. 265.

Calyx as large as in the preceding species, and of similar form; but the
ventral disk proportionally higher, and the anal tube directed upwards, not
_ being conducted subtegminally to the anterior side of the calyx. The orna-
mentation ——- as observed in gutta percha casts taken from natural moulds
in the rock ——is characterized by sharp radiating ridges, passing from the
centre of each plate to adjoining ones, and presenting upon the surface
of each a well defined stellate figure with a slight elevation in the centre,
A similar style of ornamentation, but less distinct, occurs upon the plates of
the disk and anal tube.

Infrabasals and basals as in 8 armosus ; the latter with sharp upper
angles reaching far up between the radials, and sometimes meeting the first
interbrachials. Costals smaller than the radials. Distichals three, large;
succeeded by several palmars, which are but little larger than good sized
arm plates. There are four arm openings to the ray, arranged in pairs,
with a shallow depression between each pair, and a somewhat wider and
deeper one between the pairs of different rays, the latter extending quite
a distance into the ventral surface, and forming deep grooves along the
margin. Arm structure unknown. Interbrachials: 1, 2, 2,2, 3; succeeded
in the disk by comparatively large, less regularly arranged plates, which

THYSANOCRINID &. 218

completely cover mouth and ambulacra, apparently without the assistance of
orals. Anal side greatly protruding, forming an immense projection, which
begins in the dorsal cup, and extends to over one third of the whole sur-
face of the disk, giving to the specimen an exceedingly irregular form.
The projection resembles an inflated sac, which toward the upper end
grows decidedly smaller, and on approaching the summit turns abruptly up-
wards in form of a good sized tube. The first anal plate rests upon the
broadly truncated posterior basal, and is followed by three plates in the
second, and three or more in the succeeding rows. Interdistichals eens
the lower plate resting upon the upper sloping faces of the second distichals.
The inflation upon the disk, as appears from the impressions, was covered by
a large number of plates without definite arrangement. There were a few
large plates, surrounded by smaller ones, all slightly convex and ornamented
in a similar manner. Mouth excentric, marked in the casts by a stellate
protuberance, from which the ambulacra pass out to the arm openings.
Column unknown.
Horizon and Locality. — Same as last.

Siphonocrinus pentagonus W. and Sp. (nov. spec.).

Plate XIX. Figs. 4a, 0.

A large species, of the type of S. nobilis. Calyx decidedly asymmetrical,
about as high as wide, strongly lobed at the arm regions; the depressions
deep and wide. Posterior side of the calyx enormously inflated from the top
of the anal plate to the summit of the disk, the bulging involving the lett
posterior ray, which projects more conspicuously than the others. Dorsal
cup obconical, the sides evenly spreading to the top of the costals, thence
more rapidly to the arms. The upper angles of the basals and lower angles
of the interbrachials more obtuse than in the preceding species, and never
in contact. Radials, costals, and interbrachials of nearly uniform size; the
first costal somewhat larger than the second. The first distichal as large as
the upper costal, the two following considerably smaller, the succeeding ones
free arm plates. Arm structure unknown. Interbrachials 1, 2, 3, followed
by interambulacrals. The anal plate is succeeded by three and four plates,
the latter supporting the plates of the anal protuberance, which on approach-
ing the top of the disk contracts rapidly, and turning abruptly upward, forms
a tube at the summit. Ventral disk one fourth shorter than the dorsal

214A THE CRINOIDEA CAMERATA OF NORTH AMERICA.

cup; the mouth quite excentric, and the posterior ambulacra considerably
longer.

horizon and Locality. — Same as last.

Type in the collection of W. and Sp.

ftemarks.— This species is readily distinguished from the preceding
species by having but two arms to the ray from the calyx, which, however,
may branch in their free state.

RHODOORINIDAD Roemer (1855).

Dicyctic. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART OF
THE DORSAL CUP. RADIALS SEPARATED ALL AROUND BY AN INTERRADIAL PLATE
WHICH IS FOLLOWED BY WELL-DEFINED, REGULARLY ARRANGED INTERBRACHIALS.

Analysis of the Genera.

Infrabasals 5. Basals 5.

A. ANAL INTERRADIUS GENERALLY WITH ADDITIONAL PLATES.
1. Arms uniserial.
a. Arms not branching.
Basals exposed ina side view . . . . . . . . . RHAPHANOCRINUS:.
2. Arms biserial.
a. Arms branching.
Calyx obovate; anus without a tube; interbrachials
numerous, two in second row; interdistichals gen-
erally present i.) 1-4: a. sw ps oe olay (ue he en CRUMIOORInaUISE
Calyx depressed globular, anus at end of a tube, first
interradials frequently separated from basals by
supplementary pieces. No interdistichals. Arms
probably given off from brachial prolongations of
the Calyk ig ow See ee eee ee EBOMOUR NUS:
Calyx globose, flattened or concave below ; two or three
interbrachials in second and succeeding rows; no
interdistichals.
Ventral disk narrower than dorsalcup. . . RHODOCRINUS.
Ventral disk equal to, or exceeding dorsal cup;
tubular appendages suspended from mar-
ein of disk’ 4-5 i. «5 @ 45 e0>. = OEE ERISOCR mnie
6b. Arms not branching.
Calyx globose, arms long and heavy; interdistichals
MUMeEPOUSs- 40 40 we We ne a Becomes
B. ANAL INTERRADIUS WITHOUT ADDITIONAL PLATES.
1. Arms biserial.
a. Arms not branching, dorsal cup broadly truncate at the bot-
tom, radials sometimes not all separated; arm facets

directed Tpwatd.«, i. is¢ w- Sgn s pean a ea ee LyYRI0CRINUS.
6. Arms branching.
One costal; interdistichals few. . . . . . . . . ANTHEMOCRINUS,
Two costals; rays produced into long trunks giving off
armlets from Opposite sides’ =." =. .) 5 8 ss RIPIDOCRINUS.

C. ANAL INTERRADIUS UNKNOWN.
Arms uniserial, branching frequently; infrabasals very small . D1AmENOcRINUS,

216 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Geological and Geographical Distribution.
Number of known species.

(Open figures indicate American, those marked (), European.)

FORMATION. RHODOCRINIDA.
q D wD ‘ 2 D 5 3 S
A - o i) cal a
ir American. 4 ae 2 S S = a 2 = SI 5
o Cues a= ® = fo) 4 = S) BS eB)
= BOs |S lea-le tes iele|eieis
o) Sine < sleet aes aes | Meet ela n Siey e e cette | etd ee
4504 eke ch a (SS Psat a reas fon) ie |) tec eft aa =)
4 | Keokuk. | 3 | 2
© ASS Cae oe Lee rs ee ° ees | Lae nk eS a ORE pt | te Sok go eee eee Se eee Cee (ae ey
oS a 4 Sie
: Upper Burlington. EE (5) | (4)
Bee gE |_| | | —_|-—
= | Lower Burlington. 5 4 Do. 4
(as) = =
3 po] Pei tat An Ce, PPat ay eles a ae ae en eel eg ae | ra
a Kinderhook. 33
& Hamilton. Up. Devon. here alt @)
4
Se eee ee SS eS
E Upper Helderberg. | Hifel bed. (2) GE) eds)
ira eee grr ge aaa eae en ire Gaol er ee ica cr eee cle a
YE Gee Gotland, (1) | @)
: Hudson River. 1
te Trenton. al 4 a
a he 36 2 4. 2 ee AO al 2
Total species 54 |
: (18) CHIONRO NRO RRCMECOREES,

Remarks. — When Roemer established the Rhodocrinide, he was ac-
quainted only with the genus Rhodocrinus, in which he included also the
species which were afterwards referred to Ripidocrinus and Gulbertsocrinus.
He omitted Acanthocrinus, which he had himself proposed in 1850, probably
having discovered its identity with Mhodocrinus.

The earlier French writers, d’Orbigny, de Koninck, Pictet, and Dujardin
and Hupé, placed Rhodocrinus with the Cyathocrinide.

The Rhodocrinidse of Zittel and de Loriol embrace Rhodocrinus, Olla-
crinus, Acanthocrinus, Ripidocrinus, Hadrocrinus, Trybliocrinus,* and Thysano-

* We have not seen Geinitz’s description, but judge from Zittel (Handb. der Paleont., Vol. I. p. 377)
that it is a doubtful or imperfectly defined genus.

RHODOCRINIDZ. QA

erinus. S. A. Miller in 1889 added Zyriocrinus, and adopted Lyon’s name
Goniasteroidocrinus in place of Ollacrinus. He amended this in the following
year by leaving out the monocyclic Hadrocrinus, and adding Archeocrinus
and Raphanocrinus.

To the genera which we arranged under this family in 1885,* we add the
genus Diabolocrinus, which we have proposed for a species that had been
previously referred by us to Archeoerinus. ,

The Rhodocrinidse are nearest related to the Thysanocrinidsx, but are
readily distinguished by the complete lateral separation of the radials? by
the interradials ; the radials of the Thysanocrinide bemg in lateral contact
except at the anal side. The marked asymmetry in the ventral disk, so
characteristic of the latter family, is not ob-
servable in the Rhodocrinids, in which the
whole calyx, as a general rule, is remarkably
symmetrical.

The family has a great stratigraphic range,
extending from the Lower Silurian to the
middle of the Carboniferous and becoming
extinct in the Keokuk group. The ancestral
type is probably Archeoerinus in the Trenton
group, of which Diabolocrinus is an offshoot.

The evolution of these forms through Lyrio-
crinus in the Niagara, Thylacocrinus and Ripi- Fie. 10. — Rhodocrinus.
docrinus in the Devonian, to the profusely

developed Lhodocrinus in the Carboniferous, is by easy gradations. Nor
is the step from &hodocrinus to the highly specialized Giulbertsocrinus a
difficult one, because there are transition forms in which the characters of
the two genera are toa great extent merged. Laphanocrinus in the Trenton,
and Anthemocrinus from the Upper Silurian of Gotland, apparently repre-
sent variations toward the Thysanocrinide.

The Rhodocrinidz are by far the most important dicyclic family of the
Camerata, being composed of ten genera and fifty-four species, of which
thirty-six are from America, and eighteen from Europe.

* Revision, Part IL, pp- 96 to 99. (Proceed. Acad. Nat. Sci. Phila., pp. 318-321.)

+ There is an occasional exception to this in the genus Lyriocrinus, where the radials are sometimes

connected by a narrow strip, except at the anal side. This occurs quite frequently in Z. dactyius from the

Niagara of New York; while in Z. melissa, L. juvenis, and an undescribed Lyriocrinus from Dudley, England,
the radials are widely separated.

28

218 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

In the descriptions of the Rhodocrinide, the plate which is interposed
between the radials is called the first interradial as a matter of convenience,
and those following it in the dorsal cup interbrachials, although, as elsewhere
explained, they all belong undoubtedly to the same system of plates.

RHODOCRINUS Mutter.

1821. Murer (in part); Nat. Hist. of the Crinoidea, p. 106.

1835. Agassiz; Mem. Soc. Sci. Neuchat., Vol. L, p. 196.

1841. Mier (in part); Monatsber. d. Berlin. Akad., p. 209.

1843. Austin; Ann. and Mag. Nat. Hist., Vol. X., p. 109.

1850. D’Orpieny; Prodr. de Paléont., Vol. I., p. 104.

1853. De Konrncx and Ln Hon (in part); Recher. Crin. Carb. Belg., p. 108.

1855. Roxrmer (in part); Leth. Geogn. (Ausg. 3), p. 240.

1855. (?) Mtrrer (Wirtgen and Zeiler); Verh. Naturhist. Verein f. Rheinl., Vol. XII, p. 11.

1857. Picter; Traité de Paléontologie, Vol. IV., p. 314.

1858. Hatt; Geol. Rep. Iowa, Vol. I., Part II., p. 556.

1861. Hain; Bost. Journ. Nat. Hist., Vol. VIL., p. 322.

1868. Murx and WorrneEn; Geol. Rep. Illinois, Vol. TIL, p. 476.

1875. GreyreLt; Proceed. Bristol Naturalists’ Soc., Vol. I., Part IIL, p: 480.

1879. Zirren; Handb. d. Paleontologie, Vol. I., p. 376.

1881. W. and Sp.; Revision Paleocr., Part II., p. 209 (Proceed. Acad. Nat. Sci. Phila., p. 383).

1883. WortHEn; Geol. Rep. Ilinois, Vol. VII., p. 305. .

1885. Quenstepr (in part) ; Handb. d. Petrefactenkunde (Ausg. 3), p. 958.

1889. W. and Sp.; Geol. Rep. Illinois, Vol. VIII., p. 180.

1889. 8. A. Minter; N. Amer. Geol. and Paleont., p. 277 (not Fig. 417).

(Not Rhodocrinus Goldf., 1826, Petref. Germanix, Vol. L., p. 212; nor McCoy, 1844, Carbonif.
Foss. Ireland, p. 180; nor F. Roemer, 1851, Verh. Naturh. Verein f. Rheinl., Vol. AVGDEES
p. 358; nor Billings, 1859, Geol. Rep. Canada, Decade IV., p. 61; nor Lyon, 1861, Proc.
Acad. Nat. Sci. Phila., p. 409; nor Hall, 1863, Trans. Albany Inst., Vol. IV., p- 198, and 1876,
Ist edit. of 28th Rep. N. Y. State Mus. Nat. Hist., p. 139; nor Schultze, 1867, Mon. Echin.
Hifl. Kalkes, p. 53; nor White, 1880, Proc. United States National Mus., p. 259.)
— Syn. Acanthocrinus F. Ronmer, 1850. Neues Jahrb. f. Mineralogie, p. 79; Miller, 1855, Ver

handl. Naturh. Verein, Vol. XII., p. 8; Hall, 1862 (Subgenus of Rhodocrinus), 15th Rep.
N. Y. State Cab. Nat. Hist., p. 125.

Calyx more or less globose, the dorsal cup generally somewhat flattened
or concave at the base, and constricted in the upper part. Plates flat or
convex, nodose or spiniferous, their surfaces smooth or striated. Infrabasals
five, small, sometimes merely occupying the bottom of the columnar con-
cavity. Basals five, large, all truncated at the upper end. Radials, as a rule,
larger than the costals, but smaller than the basals. Costals two, not unfre-
quently coalesced, so as to form practically a single plate. Distichals free in
part; rarely more than one, and never exceeding three, take part in the
calyx. Arms arranged in pairs and bifurcating ; biserial, either directly from
the calyx up, or from the last bifurcation; joints short; the pinnules in
contact. The first interradial plate is followed by several rows of inter-

RHODOCRINID&. | 219

brachials, the second row consisting either of two or three pieces. When
there are two plates at the regular sides, the anal side has always three, but
when the former has three, there is no additional plate at the anal side.
Ventral disk narrow, rising but little above the dorsal cup; composed of
irregularly arranged plates, none of which can be recognized as orals. Disk
ambulacra subtegminal. Anus excentric, sometimes marginal. Column
round; the axial canal pentagonal or stelliform; the internodes frequently
consisting of but one joint.

Distribution. — Rhodocrinus first appears in America in the Hamilton
group; it attains its climax in the Kinderhook and Burlington beds, and
becomes extinct at the end of the Keokuk epoch. Specimens, as a rule, are
rare. In Europe the genus occurs in the Ahemisch Uebergangsgebirge, and it
is represented by several species in the Mountain limestone.

Type of the genus: Rhodocrinus verus Miller, from the Carboniferous of
England.

Remarks. — Rhodocrinus verus, according to J. S. Miller, occurs in the
Mountain limestone of Yorkshire, and also in the Wenlock limestone of
Dudley, England, and it was said to have three basal plates, Miller con-
founded two very different types, which have since been recognized as
distinct genera. The Carboniferous form, which took Miller’s specific name,
is universally regarded as the type of the genus Lhodocrinus, having five
infrabasals instead of three, and biserial arms; the Silurian form from Dud-
ley, with three infrabasals and single arm joints, was described by Phillips as
Sagenocrinus expansus. |

The genus Lhodocrinus, as we understand it, includes species with smooth,
nodose, and spiniferous plates. For a certain species with spinous plates
from the Devonian, Roemer proposed the genus Acanthocrinus. We have
carefully examined the figures of A. longisminus, as given by Wirtgen and
Zeiler,* but have failed to discover any characters by which this form can
be separated even subgenerically. Spinous projections on the basals and
radials occur quite frequently also among Carboniferous species in all possible
variations. It is possible that ‘“ Rhodocrinus gonatodes”’ Miiller belongs to
Oehlert’s new genus Damenocrinus. -

We have referred Lhodocrinus microbasilis and R. pyriformis, both of
Billings, to Archeocrinus ; R. vesperalis White to Diabolocrinus ; R. melissa
Hall to Lyriocrmus ; R. Halli Lyon to Thysanocrinus ; R. stellaris de Koninck

* Verh. d. Naturhist. Verein, Jahrg. XII., Tab. IT.

220 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

and Le Hon to Gulbertsocrinus. The following species are too little known to
be recognized: &. spinosus Hall, R. gracilis Hall, R. varsoviensis Hall, and
ft. rectus Hall.

Rhodocrinus Wortheni Hatz.
Plate XI. Fig. 6, and Plate XII, Figs. 7a, b, e.

1858. Hain; Geol. Rep. Iowa, Vol. I., Part II., p. 556, Plate 9, Figs. 82, 4, c.
1881. W. and Sp.; Revision Palewocr., Part II., p. 218.

A small species. Calyx depressed-globose, a little concave at the bottom;
plates delicate, flat and perfectly smooth. Infrabasals of- moderate size, the
tips slightly projecting beyond the column; forming a pentagon. Basals very
large, a little wider than long. Radials nearly as large as the basals, angular
below, narrowly truncated above ; their lateral faces parallel. Costals two,
generally anchylosed, the two together smaller than the radials, and only
half their width; the first quadrangular. Distichals 2 X 10 in the calyx,
those of the lower row nearly as large as the costals, the upper smaller, and
excavated to form the arm bases, which do not project. Ambulacral open-
ings small, slitlike, directed upwards, and arranged in pairs around the disk.
Arms delicate and cylindrical; they branch twice above the calyx, and are
uniserial to the first bifurcation, then turning into biserial, with short inter-
locking pieces. The five plates interposed between the radials are consider-
ably smaller than the basals, and but little larger than the two succeeding
interbrachials, which are followed by two rows of two small plates. At the
anal side, the first interradial plate is larger than those of the regular
sides, and followed by three plates. Ventral disk very small, and following
the general curvature of the calyx. Column small, round; the upper joints
rounded at their edges; the axial canal minute. |

Horizon and Locality. — Lower Burlington limestone, Burlington, Iowa.

Type in the Hlinois State collection, Springfield.

femarks. — Specimens apparently of this species, are found in the
Waverly group of Cuyahoga Co., O., as natural moulds; the calyx, however,
appears to be more depressed, and larger in proportion to the length of the
arms. Similar specimens, but decidedly more urn-shaped, occur in the
Burlington beds of Lake Valley, New Mex., for which we propose the name
Rhodocrinus Wortheni, var. urceolatus (Pl. XII. Figs. 8, b). The typical form
resembles &. watersianus W. and Sp., and R. Wachsmuthi Hall; from which

RHODOCRINID 2. UG)

it differs in the mode of branching of the arms, and the fact that the latter
has convex calyx plates; also in its basal concavity being much deeper,
the column larger, and calyx higher.

Rhodocrinus Wortheni, var. urceolatus W. and Sp.
Plate XII. Figs. Sa, b.

Differing from the typical form of &. Wortheni in the form of the calyx,
which is urn-shaped instead of globular, higher than wide and rounded at
the bottom, while that is flattened. ‘lhe infrabasals are convex, and on
a level with the basals. The greatest width of the calyx is across the first
costals, whence it contracts rapidly to near the arm bases, which slightly
project outward, giving to the tegmen a decidedly pentangular outline.
Ventral disk almost flat, wider than in the typical form, and the plates less
numerous. Anus subcentral, and not protuberant. The plates of the calyx
flat and without ornamentation.

Horizon and Locality.— Age of the Lower Burlington limestone, Lake
Valley, New Mexico.

L'ypes in the collection of Wachsmuth and Springer.

Rhodocrinus watersianus W. and Sp.
Aerie OIE. fig. 9.
1889. W. and Sp.; Geol. Rep. Illinois, Vol. VIIT., p- 184, Plate 17, Fig. 16.

A small species of the type of Rhodocrinus Wortheni, from which it differs
in the more concave base, the proportionally smaller size of the basals, in the
more elongate form of the calyx, and in the arm structure. Calyx from
sub-globose to sub-ovoid, truncate at the bottom and narrowly concave ;
plates very slightly convex, and without ornamentation.

Infrabasals small and concealed by the column. Basals moderately large,
their lower ends abruptly deflected inward, their upper portions curving out-
ward and upward. Radials somewhat smaller than the basals; as wide as
long. Only the proximal distichals take part in the calyx; they are followed
by five to six slightly cuneate free plates, of which the upper one is axillary,
and supports two arms, which remain simple. Arms twenty, rounded on the
back, slender, very little tapering, and biserial from the last bifurcation ; the
joints moderately high and a little convex. Pinnules stout for the genus.
The first interradial plate as large as the radials; followed by five to six

222 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

interbrachials in two or three rows. The anal side has the same number of
interbrachials, but these enclose a longitudinal row of three rather large anal
plates. Ventral disk small, somewhat receding from the dorsal cup, produc-
ing an offset or groove around the margin; it is convex, and composed of
small irregular plates. Column circular; the joints rounded at the edges;
the nodal joints a little wider and higher. The internodes at about three
inches from the calyx consist of six pieces, and the same number apparently
persists throughout the rest of the column. Like most of these stems, it
tapers considerably downward, and near the distal end is provided with com-
paratively stout cirri or rootlets, irregularly given off from the sides.
Horizon and Locality.— Kinderhook group, Le Grand, Marshall Co., Iowa.
Lypes in the collection of Wachsmuth and Springer.

Rhodocrinus coxanus WortHen.
Plate XIII. Figs. 6 and 7.

1883. Worruern; Geol. Rep. Illinois, Vol. VII., p. 305, Plate 28, Fig. 7.
1885. W. and Sp.; Revision Paleocr., Part III., p. 99.
Syn. Rhodocrinus polydactylus WoRTHEN; 1883, Geol. Rep. Illinois, Vol. VII., Plate 27, Fig. 5.
The two specimens figured by Worthen as Rhodocrinus coxanus and
L. polydactylus are too much crushed and distorted to admit of critical com-
parison or satisfactory description. Both appear to have smooth plates, and
these, so far as we can ascertain, are arranged substantially in the same
way; but &. polydactylus, according to Worthen’s figure, has an additional
bifurcation in one of the ray divisions, 7. ¢., five arms to the ray. Whether
this is a persistent character cannot be ascertained from the specimens,
and until this is proved we prefer to regard FR. polydactylus a synonym of
Lf. covanus:
Horizon and Locality.— Upper part of the Geode bed in the Keokuk
group ; Hamilton, Ills.
Types in the collection of L. A. Cox of Keokuk.

Rhodocrinus Wachsmuthi Hat.

Plate XIII. Figs 5a, b, c, d, and Plate XV. Fig. 7.

1861. Hat; Prelim. Descr. of New Spec. of Crinoidea, Albany, p. 18.
1881. W. and Sp.; Revision Paleocr., Pt. IT., p. 213.

Somewhat larger than the three preceding species. Calyx subovoid,
flattened at both poles, the proximal end abruptly and deeply impressed,

RHODOCRINIDZ. =) 223

forming a circular pit, which is but partly filled by the upper joint of the |
column. Plates without ornamentation, a little convex, the suture lines
slightly grooved.

Infrabasals smali, concealed by the column. Basals as large, or even
larger than the radials, their lower ends bending abruptly inward to take
part in the pit, the upper portions curving gently outward and upward.
Radials heptagonal, a little wider than long, and twice as large as the
costals, which are quite narrow. ODistichals free from the first up; the
upper faces of the latter slightly excavated to form the ambulacral opening.
The free distichals consist of about eight plates, which are very short; the
upper one axillary, supporting two arms, of which one branches again on
the eighth joint, while the other remains simple. Arms cylindrical, of nearly
uniform size, biserial above the last bifurcation; the plates very short and
transversely arranged. Pinnules rather stout and in contact; the joints
twice as long as wide, with deep ambulacral grooves. Interradial areas not
depressed ; arranged : 1, 2, 3, 2, succeeded by three or four more pieces.
‘The anal side has three plates in the second row. Ventral disk composed of
but few plates; it is somewhat elevated at the margin, almost flat in the
middle. Orals well defined ; surrounded by two rows of rather large inter-
ambulacral pieces, which meet with the interbrachials. Anus subcentral,
opening through the disk. Column round ; axial canal small and stellate.

Horizon and Locality. — Lower Burlington limestone, Burlington, Iowa.

Type in the Museum of Comparative Zodlogy, Cambridge.

Rhodocrinus Whitei Hat.

Plate XI. Figs. 1a, b, c, and Plate XV. Figs. 6a, b.

1861. Hau; Description of New Spec. Crinoids, p. 9.
1861. Hat; Bost. Journ. Nat. Hist., Vol. VII., p. 324.
1872. Han; N. Y. State Mus. Nat. Hist., Bull. I, Plate 6, Figs. 19, 20, 21.
1881. W. and Sp.; Revision Paleocr., Part II., p. 213.
Syn. Rhodocrinus Whitei, var. burlingtonensis Hatt; 1861, Bost. Journ. Nat. Hist., Vol. VIL, p. 325.

The largest known American species. Calyx depressed sub-globose, a
little wider than high; the lower portion flattened and formed into a deep.
concavity ; the sides decidedly bulging to the first costals, then contracting
to near the arm bases. All plates of the dorsal cup to the top of the cos
tals of nearly the same size, all strongly convex, and without ornamentation.

Infrabasals of medium size, slightly projecting beyond the column. Bas-

224 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

als large, lying almost horizontally, except their proximal ends, which bend
abruptly inward and take part in the concavity; the upper faces broadly
truncated. Radials hexagonal, about as wide as long. Costals as long as the
radials, but generally a little narrower. Distichals generally. represented by
only one row of plates in the calyx, which are excavated at the upper faces
to form the arm openings, of which there are two to the ray. Nothing is
known of the arm structure. The interradial spaces are occupied Diyealeo2s
3, and two large plates, followed by two or three smaller ones. The
anal interradius has a few more plates in the upper rows. Ventral disk
small, slightly convex, pentangular in outline, and composed throughout of
small, irregular, slightly convex pieces, which increase in size as they ap-
proach the arm regions. Anus subcentral, at the end of a sbort tube or
elongate protuberance, which gives to the disk an irregularly conical form.
Column small, not filling the basal concavity; it is round, and there is an
alternation of larger and smaller plates. Axial canal of medium size and
stelliform. |

Horizon and Locality.— Lower part of the Lower Burlington limestone,
Burlington, Iowa.

Types in the University Museum at Ann Arbor.

ftemarks.— We have examined a number of specimens of this rare
species, including the types, and are of the opinion that the specimen
which Hall described as var. burlingtonensis is a very large example of
f. White. That it has one or two additional interbrachials, that the
calyx 18 proportionally a little shorter and the basal concavity deeper, is
readily explained by extravagant growth. The species occurs in the low-
est layers of the Lower Burlington limestone, and the calyx sometimes

attains a size of two inches in diameter.

Rhodocrinus Benedicti S. A. Mier.

1892. Advance Sheets Highteenth Rep. Geol. Survey Indiana by Gorby, p. 15.

Calyx small and globular, except the tegmen, which is slightly conical.
Dorsal cup nearly as high as wide, widest at the middle; the sides evenly
rounded to the arm bases ; the base concave. Plates convex, some of them
angular, and the principal ones covered with radiating ridges. Suture lines
distinct.

Infrabasals small, forming a flat pentagonal disk. Basals the largest

plates of the calyx, highly convex in the central part, with ridges extending

RHODOCRINID &. 224

to adjoining plates. Radials nearly as large as the basals, but the ridges less
conspicuous. Tirst costals smaller than the second, convex; the second as
large as the first. The second distichals support the free arms, which are
not preserved. Interradial areas not depressed below the level of adjoining
brachials ; composed of the interradial plate, and about nine interbrachials,
of which the upper ones are very small. The anal area has one or two
additional plates. Ventral disk small; its diameter scarcely two thirds the
width of the dorsal cup at the widest part; composed of numerous very
small, highly convex plates. Anus subcentral. Column round.

HHorizon and Locality. — Keokuk group ; Harrison Co., Indiana.

Remarks. — We did not have access to the specimens to illustrate this
species, and were obliged to make our description after Miller.

Rhodocrinus nodulosus Hatt.
Plate XIIT. Fig. &.

1862. Rhodocrinus (Acanthocrinus) nodulosus— Haut; 15th Rep. N. Y. State Cab. Nat. Hist., p. 126;
ibid., 1872, Bull. I., Plate la, Fig. 8.
1881. Rhodocrinus nodulosus —W. and Sp.; Revision Paleocr., Part II., p. 219.

Of medium size. Dorsal cup more rapidly spreading to the top of the
second costals than from there to the arm bases; height and greatest width
about equal; interradial and interdistichal spaces depressed. Plates convex,
the surface covered with obscure radiating ridges, and the central portion in.
most of them produced into a small node.

Infrabasals small, but plainly visible beyond the column; the bottom
somewhat depressed for the reception of the column. Basals larger than
any of the other plates, longer than wide; the lateral upper faces longer
than the lateral lower; the upper faces rather narrow. Radials larger than
the costals; three of them pentagonal, the two posterior ones hexagonal ;
the costals slightly narrower and shorter. The distichals support the free
arms; five to six of them take part in the calyx, of which the three lower
ones are subquadrangular and twice as wide as long, the two or three suc-
ceeding ones cuneate, and slightly interlocking. The free distichals are less
convex and shorter than those of the calyx; the succeeding arm plates
strictly biserial, and very short. Arms rather stout at the proximal ends, but
the size decreases rapidly with each bifurcation. There are two bifurcations
in the free arms, and the branches are widely divergent. The large plates

29

226 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

interposed between the radials are followed by two, three, and three inter-
brachials at the regular sides; while the anal side has three in the second
and four in the third row. Construction of ventral disk and anus not known.
Interaxillaries three or more.

Horizon and Locality.— Hamilton group ; Canandaigua and Ontario Cos.,
Nea:

Type in the New York State Cabinet of Natural History at Albany.

fvemarks. — This form differs from the other American species, except
Rhodocrinus Kirbyi, in having interaxillary plates, and also in the details
of the arm structure. Our description was made from Hall’s figure, and
from a specimen in the collection of Prof. J. M. Clark, which is now in the
New York State Cabinet.

Rhodocrinus Kirbyi W. and Se.
TCG US TPO SIGN ON sO!
1889. Geol. Rep. Illinois, Vol. VIII, p. 180, Plate 15, Fig. 10 and Plate 16, Fig. 3.

Calyx barrel-shaped, a little longer than wide, excavated at the bottom,
slightly swelling from the middle of the basals to the middle of the second
costals, thence contracting to the margin of the tegmen. In some specimens
the sides are almost cylindrical. Surface of plates convex, covered with
obscure ridges passing from plate to plate; those following the radial series
somewhat stronger, and increasing in prominence as they approach the arm
bases, so as to give to the calyx an obscurely pentangular outline.

Infrabasals concealed by the column, small, resting within a shallow con-
cavity. Basals large; their lower margins abruptly bent inward; the
middle portion forming a sort of rim on which the calyx rests. Radials
smaller than the basals, about as wide as long. Costals two, of nearly
uniform size, about half the size of the radials. Distichals five; the two
lower ones incorporated into the calyx, smaller than the costals; the three
upper ones free, very short and rounded exteriorly; the third axillary,
giving off two branches, of which only the inner one branches again, gener-
ally from the third plate, giving three arms to each main division of the ray,
or thirty in all, with occasionally an additional arm in one or both posterior
rays. Arms cylindrical, and only tapering at the tips; they are composed
of a double series of rather short, interlocking pieces, with indented suture
lines which give to the back of the arms a file-like appearance. Pinnules

RHODOCRINID&. 22

strong, contiguous; composed of elongate joints. Interradial spaces arranged
in four rows. The plates interposed between the radials smaller than these ;
followed by two, rarely three, interbrachials, and these by two and three
others in the two succeeding rows, which gradually decrease in size upwards.
Anal side wider, with three plates in the second, and generally four in the
third row. Interdistichals from two to three, very small. Disk slightly
convex, the interradial spaces a little depressed; constructed throughout
of very small, irregularly arranged tumid plates. Anus almost central, at
the end of a wart-like, somewhat conical protuberance, composed of very
small pieces. Column round, from eight to ten inches long, nearly uniform
for about two thirds its length, whence it gradually tapers to a fine point,
with a few short cirri given off toward the end. The joints are rounded
along their edges, and the nodal ones are a little the widest and longest.

Horizon and Locality. — Kinderhook group, Le Grand, Marshall Co.,
Towa.

Types in the collection of Wachsmuth and Springer.

Ltemarks. — This species is one of the most abundant at the Le Grand
locality, where many specimens have been obtained with crown and stem
fully preserved. ‘The specimens are invariably of a very dark color, though
lying in contact with Platycrinus and other forms which are light colored, —
sometimes almost as light as those from the Burlington rocks. This varia-
tion in color of the fossils is one of the interesting facts of that locality. The
Crinoids must have been deposited there in very quiet waters; they occur
in a soft, light buff limestone, and in many cases are imbedded just as they
died. They occur in nests or colonies, and the genera and species are indis-
criminately commingled, there being of Crinoids and Blastoids upwards of
twenty-four species. It is therefore a singular fact, that while the specimens
of some species are of a pure calcareous composition, and of very light color,
those of others, under precisely the same conditions of fossilization, lying
side by side with them and often with stems and arms intertwined, are
harder, and of a very dark, brownish or even purplish grey color. The
contrast between some of them is very marked, and so nearly constant for
the species as to be quite a reliable feature for separating them. There are
intermediate shades of color between the lightest and the darkest, but as
a general thing specimens of the same species have a uniform shade. Ag
a rule, all the species of Actinocrinus, Platycrinus, Graphiocrinus, Scaphiocrinus,
Taxocrinus and the Blastoids, are of light color; Dorycrinus and Dichocrinus

998 ~~" THE CRINOIDEA CAMERATA OF NORTH AMERICA.

are dark, and Megistocrinus and Batocrinus rather intermediate; but while
fthodocrinus Kirbyi is very dark, R. nanus is light colored, and R. water-
sianus intermediate between them.

Rhodocrinus nanus M. and W.
Plate XI., Figs. 7a, b; and Plate XII, Figs. 2a, b.

1866. Murex and Wortuen; Proceed. Acad. Nat. Sci. Phila., p. 254.
1868. Mrnx and Wortuen; Geol. Surv. Illinois, Vol. IIL, p. 476, Plate 18, Figs. 2a, d.
1885. W.and Sp.; Revision Paleocr., Part II., p. 212.
1889. W. and Sp.; Geol. Surv. Illinois, Vol. VIIL., p. 182, Plate 16, Fig. 4; and Plate 17, Fig. 15.
Syn. Rhodocrinus sculptus 8. A. Minter; 1890, Descr. New Genera and Species of Hchin., p. 42,
Jdleine 7p nies Mlle
Syn. Rhodocrinus celatus 8. A. Minter; 1890, ibid., p. 43, Plate 7, Fig. 10.

Calyx subglobose, the sides regularly convex, except in specimens with
very protuberant basals, in which they appear to be nearly straight; the
base truncate and slightly impressed. The plates along the rays marked by
rounded ridges, which vary somewhat in prominence. These ridges in some
specimens are confined almost entirely to the radial series, giving to the
calyx a pentagonal outline, but in others they run to the basals, interradials
and anal plates, traversing the sutures, and passing from plate to plate. The
plates are more or less convex, and their outlines well defined.

Infrabasals small, impressed, slightly projecting beyond the column.
Basals large, a little protuberant, the calyx resting on their lower margins,
which are rounded and form a low rim around the concavity. Radials nearly
as large as the basals; the costals about of equal size, but one third smaller
than the radials. Distichals generally five, of which only the first and
larger one takes part in the calyx; the others which are of nearly uniform
size and quadrangular, except the upper which is axillary, are free arm
plates. The inner branches of the arms divide again on the third joint, and
there is also occasionally a bifurcation from the outer branch in a posterior
ray. The arms taper but little, are long, and biserial after the last bifur-
cation. The arm joints are narrower than in R. Kirbyi, and their backs more
rounded; the pinnules stronger and less closely packed than in that species.
First interradials half the size of the radials; followed by two interbrachials
nearly as large; the succeeding plates considerably smaller, and their ar-
rangement somewhat irregular. Anal interradius wider than the others, and
enclosing a continuous row of anal plates, which rest upon the truncated
upper face of the interradial. The first anal plate is as large as the radials,
but the interbrachials at both sides of it are smaller than the corresponding

RHODOCRINID 2. ‘ 229

plates of the other areas. Anal opening excentric, directed upwards, placed
within a large protuberance, composed of rather large plates. Ventral disk
convex, depressed at the interradial spaces, and constructed of small, irre-
gular, convex pieces without definite arrangement.

Hlorizon and Locality. — Kinderhook group; Le Grand, Marshal Co., and
Burlington, Iowa.

Types in the Museum of Comparative Zodlogy at Cambridge, and in the
collection of Wachsmuth and Springer.

Remarks. -— This species is nearest allied to R. Kirbyi, from which it is
distinguished by its more globose form, more slender arms, by the ridge-
like series of anal plates, and the absence of interaxillaries. In the Le Grand —
beds this species is readily identified by its color, which is invariably light ;
while all specimens of #. Kirbyi are dark colored, and those of R. watersianus
intermediate between the two.

Rhodocrinus parvus §. A. Miter.
1891. S.A. Miniter; Geol. Rep. Missouri, Bull. 4, p. 39, Plate 5, Figs. 8, 9.

Closely allied to R. nanus, but a somewhat smaller species and the calyx
more depressed. Calyx subglobose, wider than high; the plates moderately
convex, and covered in exceptionally well marked specimens by obscure:
ridges* passing from plate to plate; suture lines distinct. Infrabasals slightly
extending beyond the column. Basals the largest plates of the calyx, bend-
ing oradually upward. MRadials nearly as large as the basals. The two
costals together smaller than the radials, and frequently anchylosed. Dis-
tichals five, very small, only the first a calyx plate, the succeeding ones free;
the upper axillary, and supporting two arms, which do not branch again.
Arm openings arranged in pairs, each pair separated by a wide interspace.
Arms delicate, composed of two series of deeply interlocking, cuneate pleces,
the intervening sutures grooved. Pinnules not in contact laterally. The
plates interposed between the radials very large, especially that of the anal
side. Interbrachials 2, 3, and 2, apparently also at the anal side. The
ventral disk not exposed in the specimens.

Horizon and Locality. — Lower part of Warsaw limestone; Booneville, Mo.

Types in the collection of Mr. §. A. Miller.

* We are led to believe that the ridges in Miller’s figures are too distinct and misleading. In five speci-
mens in the Missouri State collection with Miller’s label attached, there are no ridges at all, and the surface
is smooth or slightly roughened. That this is not owing to the preservation is shown by the fact that the
other parts are sharply defined.

230 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Rhodocrinus Barrisi Hatt.
delve DLT Wigs. 3, 70, 0,0, Os 0nd oon Us

1861. Hatz; Prelim. Notice of New Spec. of Crin. (Albany), p. 9.
1861. Hatt; Boston Journ. Nat. Hist., Vol. VII. (No. 2), p. 322.
1872. Hatt; N. Y. State Mus. Nat. Hist., Bull. 1, Plate 6, Figs. 16, 17.
1881. W. and Sp.; Revision Paleocr., Part II., p. 212.
Syn. Rhodocrinus Barrisi, var. divergens Haut, 1861; Boston Journ. Nat. Hist., Vol. VIL., p.
324; and N. Y. State Mus., Bull. 1, Plate 6, Fig. 18.

A very variable species, of the style of Gilbertsocrinus. Calyx forming
a polyhedron, with slightly impressed faces and a node at each angle. Dorsal
cup broadly truncate at the bottom, widest at the middle of the radials,
whence it tapers rapidly and uniformly to the margins of the tegmen, whose
diameter is from one third to one half smaller than that of the widest part
of the dorsal cup, and less than the diameter at the truncated lower part.
Plates highly elevated, their middle portions crowned with spine-like pro-
cesses or elongate nodes, connected by well marked ridges, which traverse
the sutures and meet with the nodes of adjoining plates. The nodes upon
the basals are longer, attaining in very mature specimens a length of four to
five mm. by two mm. wide; they are directed obliquely downward, while those
from the radials, costals, and interradials point horizontally. In less mature
specimens, as a rule, the nodes are comparatively smaller. The ridges
connecting the basals form around the bottom of the calyx a well defined
pentagon, with a shallow concavity occupying the whole width of the lower
face, enclosing the infrabasals and fully one third of the basals. |

Infrabasals small, but their upper angles visible beyond the column.
Basals proportionally large ; their upper half abruptly bent upwards so as
to take part in the lateral walls, and forming a sharp edge on which the
calyx rests. Radials a little smaller than the basals. Costals very small ;
the first less than one third the size of the radials, but twice as large as the
second. Distichals eight to twelve; the plates of the first row, and some-
times those of the second, incorporated into the calyx and in contact later-
ally. ‘The tree distichals short, cuneate, and in large specimens interlocking ;
the upper one axillary, supporting two arms, of which either one or both are
branching once again. Arm openings elongate ; arranged in pairs; directed
horizontally. Arms about twice as long as the height of the calyx; cylin-
drical; somewhat divergent; the plates sharply cuneate and interlocking.

RHODOCRINID. 23%

Pinnules contiguous ; their joints as long as two of the arm plates. First
interradial followed by two rows of interbrachials of two each, except at the
anal side, which has from three to four plates in the second row; the first
almost as large as the radials ; the succeeding ones very much smaller. Ven-
tral disk slightly elevated, flattened in the middle; composed of fourteen to
sixteen rather large convex or conical plates, indefinitely arranged. Anus
marginal, directed obliquely upwards. Column short, gradually tapering ;
joints moderately high, the edges almost straight.

Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa.

Types in the Museum of Comparative Zodlogy, Cambridge.

ftemarks. — The specimen described by Hall as variety divergens is a very
mature form of this species. In the smaller specimens the branches of the
arms are less divergent.

Rhodocrinus Barrisi var. striatus W. & Sp.
Plate XII. Fig. 6.

Calyx almost cylindrical, broadly truncated at the bottom, but not exca-
vated. Plates moderately convex, without nodes. Surface covered with
well defined ridges, which meet with similar ridges from adjacent plates.
The ridges connecting the basals and those proceeding from the radials to
the adjoining basals forming a triangle, which encloses another whose ridges
are somewhat less distinct. The form and arrangement of the plates simi-
lar to those of the typical form, but the ventral disk proportionally larger,
and composed of a greater number of pieces.

Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa.

Type in the collection of Wachsmuth and Springer.

Rhodocrinus truncatus W. & Sp. (nov. spec.).
Plate XIII. Figs. 2a, b, c, d, e, f.

A rather small species. Calyx wider than high, pentangular in outline,
broadly truncated at both ends; the sides nearly parallel, a little wider at
the arm bases. The truncation of the lower end not only extends to the
greater part of the basals, but includes small portions of the radials. The
base is pentangular in outline, not excavated, except the middle part very
slightly for the reception of the column. Plates convex, a little tumid, with

232 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

obscure ridges or angularities passing out from their margins, and meeting
those of adjoining plates ; the median portions perfectly smooth.

Basals and radials of nearly the same size, both bending abruptly upward,
the former to three fourths their length, the others only at the lower ends.
Costals one or two; together about one half the size of the radials, very
frequently anchylosed, there being scar¢ely a specimen with two costals in
all five rays. Of the distichals generally but one plate takes part in the
calyx —in very large specimens sometimes two — which is as large as the
second costals. Arm openings two to the ray, facing sideways. Arms un-
known. Interradial spaces flattened, composed of 1, 2, 3 plates, followed by
two others between the arm openings; the plate between the radials not
larger than the interbrachials above; the two latter separated by a shallow
depression, which gives to the arm bases a somewhat lobed appearance, and.
to the tegmen a pentangular outline. Anal side wider, with three plates in
the second row; the plates of the median row forming a vertical ridge of five
pieces, which passes up into the tegmen. Ventral disk comparatively large,
almost flat; composed of about twenty slightly convex plates, of which
those near the margin are the largest. Anus marginal, on top of a small
protuberance.

Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa.

Lypes in the collection of Wachsmuth and Springer.

Ltemarks. —'This species resembles the two preceding, but differs essen-
tially in the form and proportions of the calyx. In those species the calyx
attains its greatest width in the lower half of the dorsal cup, and the teg-
men is proportionally narrow ; while in this species the calyx is widest at the
bases of the arms. Besides it differs in the construction of the anal side, and
in having larger costals and distichals.

Rhodocrinus tuberculatus W. & Sp. (nov. spec.).
Plate XTILT. Figs. 3, 4.

A very knobby species; somewhat larger than the preceding one,
Calyx a little higher than wide; deeply excavated at the bottom; decid-
edly bulging at the costals, whence it contracts uniformly to the margin of
the ventral disk, where the diameter is fully one third smaller —less than the
width at the lower end of the dorsal cup. All plates of the calyx, basals
and infrabasals excepted, extended into conspicuous angular tubercles, of
which those upon the radials are longest and stoutest;

RHODOCRINID&. 2a4

Infrabasals placed at the bottom of a concavity ; forming a penta-
gon, of which small portions are exposed beyond the column. Basals
smaller than the radials and without nodes or tubercles; they rest within
the lower concavity, except their extreme upper ends, which bend slightly
upwards. Radials large, forming a rim upon which the calyx rests; their
tubercles quite long, rounded at the ends, and directed obliquely downward.
Costals comparatively large, their tubercles connected with one another, and
sometimes with those of adjoining radials and interradials by obscure ridges.
Distichals one in the calyx, provided with a horse-shoe-shaped facet for the
reception of the free brachials. Arm openings elongate, facing laterally ;
structure of the arms unknown. First interradial followed by interbrachials
in succession of 2, 2, and two more between the arm openings. The anal
interradius has three plates in the second and succeeding rows, but the plates
are not formed into a ridge or placed in a straight line, their arrangement
being rather irregular. Interdistichals one, on a level with the arm openings.
Tegmen very small, flat, and of the plates only the ends of the tubercles vis-
ible from a side view; the plates large and irregularly arranged. Anal open-
ing marginal.

Horizon and Locahty.— Age of the Lower Burlington limestone, Lake
Valley, New Mexico.

Types in the collection of Wachsmuth and Springer.

Remarks. — This species, which has the general habitus of certain forms
of Gilbertsocrinus, differs from all other species of Rhodocrinus in the form of
its nodes, which cover almost the whole face of the plates. The largest
nodes occur on the radials, and not on the basals, those of the latter plates
being often wanting altogether. It also differs in the form and greater size
of the costals and distichals.

GILBERTSOCRINUS Putters.

1836. Pxrturps; Geology of Yorkshire, Part II., p. 207.

1841. Mtztuer; Berlin. Acad. der. Wissensch., p. 209.

1849. D’OrBieny; Prodrome I., p. 155.

1852. D’Orgieny; Cours élément., Vol. IT., p. 142.

1865.. Mzrx and Wortnen; Proceed. Acad. Nat. Sci. Phila., p. 166.

1872. Hann; N. Y. State Mus. of Nat. Hist., Bull. I., Plate 1a and Plate VI.

1873. Merk and Wortuen; Geol. Rep. Illinois, Vol. V., p. 389.

1875. GRENFELL; Proceed. of Bristol Naturalists’ Soc., Vol. I., Part III., p. 488.

Syn. Ollacrinus CUMBERLAND 3 1826, Appendix to Reliquieze Conservate, Plate D ; 1877, Wachsmuth ;
Amer. Journ. Sci., Vol. XIV., p. 125 5 1878, Zittel; Handb. d. Palaeont., Vol. I., p. 376 ; 188],
W. and Sp.; Revision Paleocr., Part II., p. 213; and Proceed. Acad. Nat. Sci, Phila., p. 387;
30

234 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

1885, W. and Sp.; Revision Paleocr., Part III., p. 99; and Proceed. Acad. Nat. Sci. Phila,
p- 321.

Syn. Ahodocrinus Du Kon. and Lz Hon, 1853, Recher. Crin. Carb. Belg., p. 104; Roemer, 1855,
Lethza Geognost., p. 240; Pictet, 1857, Traité de Paléont., Vol. IV., p. 314; EH. Billings, 1858,
Canada Surv., Decade III., pp. 25 & 26; Dujardin and Hupé, 1862, Hist. natur. des Zoophytes
Hichinod., p. 123; Rofe, 1865, Geol. Magazine, No. 12, p. 247. j

Syn. Goniasteroidocrinus Lyon and Cassepay, 1859, Amer. Journ. Sci., Vol. XXVIIT, Ser. 2, p. 2335
Meek and Worthen, 1869, Proceed. Acad. Nat. Sci. Phila., p. 73; S. A. Miller, 1877, Catal.
Paleeoz. Foss., p. 80, and 1889, N. Am. Geol. and Palzont., p. 249.

Syn. Lrematocrinus Hatt, 1860, Suppl. Geol. Rep. Iowa, Vol. 1., p.70,and Prelim. Notice of New
Spec. of Crin., p. 9; Meek and Worthen, 1860, Proceed. Acad. Nat. Sci. Phila., p. 383; Hall,
1861, Journ. Bost. Soc. Nat. Hist., Vol. VII., p. 825, and 1862, 24th Rep. N. Y. State Cab.
Nat. Hist., p. 128; Meek and Worthen, 1866, Geol. Rep. Illinois, Vol. II., p. 217.

Fie. 11. — Gilbertsocrinus.

1b = infrabasals, b = basals, R = radials, I= costals, II = distichals, II] = palmars, A= arms, AO=arm
openings, ir = interradials, ibr = interbrachials, [RA = interradial appendages.

Dorsal cup greatly exceeding the disk in size; the former elongate, more
or less cylindrical; the latter flat or low-hemispherical, its margin extended
into ten tubular appendages, passing outward and downward. Plates smooth

or radiated, nodose or spiniferous.

RHODOCRINID &. 239

Infrabasals five, small, pentagonal; forming a flat, impressed pentagon
at the bottom of a concavity. Basals large, heptagonal, widely truncate
above. Radials angular at the bottom. Costals two. Distichals 2 x 10 in
the calyx; the upper ones excavated to form the lower margins of the arm
openings, of which there are two to the ray,one to each main division. The
arms are in clusters, delicate, branching and biserial from the last axillary ;
they either stand erect and fold over the disk, or are pendent, their ventral
furrows exposed to view. Pinnules rather strong and closely packed to-
gether. Interradial areas large, composed of numerous plates; those alter-
nating with the radials considerably larger and frequently nodose, the
interbrachials arranged in vertical rows. Anal interradius generally not
distinct in the cup.

Ventral disk nearly flat, with five pit-like interradial depressions, of which
the posterior one is considerably the largest ; the bottom of the pits formed
by small polygonal pieces, surrounded by larger plates. In the European
species, in which the pits are less conspicuous or even wanting, the disk
plates differ but little in size. The outer margins of the disk are extended
outward, and form ten large tubular appendages, which are pendent, in some
species reaching down below the calyx. These appendages are formed either
by a single row of cylindrical joints, or by three rows of plates longitudinally
arranged, two of them ventrally disposed, the third dorsally ; but when two
of them are suturally connected, the consolidated part is composed of two
and six plates respectively. The tubes are all pierced to their full length
by a central canal, which, on entering the calyx, connects with the sub-
tegminal grooves at the inner floor of the disk. In the Kuropean species,
the ten appendages are free from their origin in the calyx, and those facing
the same interradius are separated from each other by interradial plates. In
the American forms, however, with the exception of G’. spinigerus from the
Hamilton, and G. jiscellus from the lower Burlington, the tubes meet in pairs
at midway between two rays, and are for some distance laterally connected
by a rigid suture; but, although apparently forming a single appendage,
each one from the base up has its own canal, and the two canals of the same
set connect with different ambulacra. The arm or ambulacral openings are
located beneath the appendages; they occupy the bottom of a small, funnel-
shaped pit, and are formed between the second distichals and the proximal
plates of the appendages. Anus subcentral, opening out directly through
the tegmen, and occupying the upper (inner) end of the posterior depression.

236 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Orals of rather irregular arrangement, and their identification sometimes
difficult in certain species.

Column circular ; the nodal joints considerably wider and higher, rounded
at their edges; axial canal pentalobate or stellate, the angles directed
radially. |

Iistribution. —Gulbertsoerinus occurs in America and Europe. It first. ap-
peared in the Hamilton group, reached its climax in the two Burlington
beds, and became extinct before the close of the Keokuk epoch. |

Remarks — The name Ollacrinus, the earliest name given to this form,
was proposed by Cumberland in 1826, in an appendix to the Reliquise Con-
servatz. He published no generic diagnosis or specific name, but gave an
excellent figure, by which the type is easily identified. Of the plate con-
taining this figure, however, we have been informed by the late Dr. P. H.
Carpenter that only a few copies were distributed in a private way, and that
no copy of it is to be found in the Library of the British Museum.* For this
reason it cannot be looked upon as lawfully published, and the name will
have to be given up.

Phillips proposed the genus Gilbertsocrinus in 1836. He included in it
Cumberland’s type, which he described as Gr. calearatus (Pl. XV. fig. 5). His
figures are fairly good, but the descriptions are meagre, and show no essen-
tial departures from /hodocrinus. Neither does he make any allusion to the
two different sets of openings, which are so well represented in his figures.
The arms are described as ‘ rounded and perforated in the centre.”

De Koninck and Le Hon, in 1854, declared that Ollacrinus and Gulbert-
socrinus were synonyms of Rhodocrinus. They probably arrived at this con-
clusion from their “‘ Rhodocrinus stellaris,’ which we find to be a true Gilbert-
socrinus (Pl. XV., fig. 4). Similar views were expressed by Roemer, Pictet,
and Dujardin and Hupé.

In 1859, Lyon and Casseday described a new species from the Carbon-
iferous of Kentucky, and made it the type of a new genus: Goniasteroido-
crus. The species closely resembles that figured by Cumberland and
Phillips, except that the supposed arms (appendages) are suturally connected
by their sides, in pairs, for some distance ; while those of the British species
are separate from their origin. Lyon and Casseday’s specimen was in excel-
lent preservation, the so-called arms being all in position, and it had below
and between these “arms, in the interradial fields,” as they state, clusters of

* We saw it in the Cambridge copy which was formerly in De Koninck’s library.

RHODOCRINID.&. oe

from five to seven “long pendulous cilia” bearing delicate pinnules. The
pinnulated “ cilia” they afterwards refer with a query to arms.

Hall in 1860, without making any comparison with Goniasteroidocrinus,
described under the new name Zrematocrinus, a number of species from the
Subcarboniferous, of undoubted generic identity with Lyon’s species. He
also regarded the upper appendages as arms, but doubted if they could have
performed the functions of arms. He further suggested that probably the

b]

“foramina” above the secondary radials served for the protrusion of “ fleshy

arms or tentacles.” However, a year or two later he described his 7remato-

b)

crinus spinigerus with “ summit arms” and “true arms.”

In 1865, Rofe, who apparently was not acquainted with the writings
of Lyon and Hall, while discussing certain morphological questions, asserted
that Phillips species of Gilbertsocrinus “are undoubtedly Rhodocrim.’ He
also stated that Rhodocrinus differs from most of the other Crinoids “in the
form of the arms and in the position of the ovarian apertures,” and that
“the arms have no grooves on the upper side, but are cylindrical, with a
tubular canal through the axis, and the ovarian openings placed immediately
under the base of the arms.” In reply to Billings’ supposition that the
upper appendages might possibly be spines, he said: “ their articulated struc-
ture, and the passage through the axis forbid the idea of their being
spines.”

Meek and Worthen, in 1866,* discriminated between Gilbertsocrinus and
Gomasteroidocrinus ; making the latter a section of the former. Gtlbertsocri-
mus was said by them to have the “pseudo-ambulacral appendages” located
directly over the interdistichal spaces, and Gloniasteroidocrinus over the inter-
radial ones; and they stated that these structures are not arms, that they
“differ essentially from all appendages of the body in any known Crinoid,
and seem to bear somewhat the same relations to the body, that the side
branches of the column of Pentacrinus and many Paleeozoic Crinoids do to the
column itself.” The “true arms,’ they say, connect with the calyx at
the lower openings, which Hall described as foramina in Zrematocrinus.
They gave a description and good figures both of the true arms and the
appendages,

Grenfell, in 1875, defined Gilbertsocrinus as follows: “Basals five; sub-
radials five ; radials three; brachials several, generally irregular ; the
second brachial channelled at top, and leading into an orifice which com-

Geol. Rep. Illinois, Vol. II., pp. 219-221.

238 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

municates with the perforation in the arms; axillary plates well developed ;
arms round and generally set at right angles to the body.’ He took the
upper openings, 7. ¢., the central perforation following the median line of the
appendages, to be “efferent tubes,” carrying off the water used for respira-
tion, which he thinks in other groups is performed by the anal tube.

From numerous specimens in our collection, some of them with all of the
two kinds of appendages preserved to their full length, we are enabled
to fully confirm the opinion of Meek and Worthen that the smaller, pinnule-
bearing appendages are arms, and that the stouter, tubular ones are struct-
ures unlike those of other Crinoids. What the functions of these tubes may
have been can only be conjectured, but they were probably not identical
with those of the cirri, as Meek and Worthen supposed; and we are inclined
to think, from the fact that their canals communicate with the subtegminal
galleries at the inner floor of the ventral disk, that the functions, as sug-
gested by Grenfell, were respiratory, and that the canals performed a similar
office to that of the respiratory pores of Batocrinus and the spiracles of the
Blastoids.

Meek and Worthen, in separating the European species from the Ameri-
can, were probably not aware that the coalesced appendages are actually
pairs of distinct tubes, each one having a canal of its own, and the canals
of the same pair communicating with different ambulacra, in a way similar
to that of the paired spiracles in the Blastoid genus Pentremites. It is in this
respect exceedingly interesting that in Grilbertsocrinus fiscellus the posterior
appendages are simple, and are widely separated by a row of anal plates,
exactly as in the European species; while those of the four other sides are
united at the base. The species thus represents at two of its sides the
Kuropean form of the genus, and at the other three the American.

Another interesting fact in the developmental history of the genus is
that m the species of the Burlington limestone the consolidated tubes are
composed of the single cylindrical plates of two simple tubes united laterally
by suture. In the transition beds between the Burlington and Keokuk
groups appears the rare species G. obovatus, in which the two rows of plates
composing the double tubes of its predecessors are roofed over by four more ;
and this character becomes constant in the ‘Keokuk, where the genus is
found quite abundant in some localities.

The genus Rhodocrinus, which has been so frequently confounded with
Gilbertsocrinus, has arm openings only, the tubular appendages being un-
represented ; otherwise the two genera cannot be distinguished.

RHODOCRINID &. 239

Gilbertsocrinus tuberosus (Lyon and Cass.).
Plate XV. Figs. 1a, b ; Plate XVL, Migs 1 106; Pidie XVI Pigae.

1860. Goniasteroidocrinus tuberosus — Lyon and CassEpay; Amer. Journ. Sci, Vol. XX VIII., (Ser. 2),

, 238.
1866. Gilbertsocrinus (Goniasterotdocr.) tuberosus — MuEK and WortHEN ; Geol. Re. Illinois, Vol. IL., .

220, with diagrams.
1881. Ollacrinus tuberosus —W. and Sp.; Revision Paleocr., Pt. II., . 219.
1889. Goniasteroidocrinus tuberosus —S. A. Minter; N. A. Geol. and Paleont., . 250; and 1891, Adv.
Sheets 17th Re. Geol. Surv. Indiana, . 51, Plate 9, Fig. 11.
Syn. Trematocrinus robustus Hatt; 1860, Sul. Geol. Re. Iowa, . 77.

Calyx large, a little higher than wide. Dorsal cup. subcylindrical,
slightly constricted at the arm regions, its base deeply excavated. Ventral
disk flat, with deep interradial depressions; the appendages pendent, long,
and frequently branching. Plates tumid, the radials drawn out into elon-
gate nodes or obtuse spines, directed downward.

Infrabasals small, almost completely covered by the column; forming
the bottom part of the concavity, of which the basals constitute the sides,
and the radials with large interradial plates between them form the rim
of an inverted cone on which the remainder of the calyx rests. Radials
longer than wide, considerably larger than the costals. The interradial
plates large and covered with a sharp node. Costals hexagonal and hepta-
gonal. Distichals two in the calyx, smaller than the costals, and about as
wide as long. Arm openings of the same ray widely apart, separated by
two or three interdistichals. Arms pendent, slender, branching, and with
long pinnules; there being six ultimate arms to each arm opening. Caly-
cine appendages in ten pairs, disposed interradially ; those of adjoining rays
in sutural contact to about 12 mm. from the calyx, when the pairs separate,
and the two tubes take a sharp outward turn, so that their tips meet with
those of adjacent pairs. Hach tube is composed of three rows of plates
longitudinally arranged, two of them occupying the ventral, the third the
dorsal side, so that there are six rows for the distance to which they are
united. ‘The tubes generally branch once or twice; they are long, and
taper gradually to their tips. Interbrachials arranged longitudinally in
three series of plates of nearly equal size; the anal side not distinct. Vent-
ral disk low-hemispherical, almost flat, the plates highly convex, those form-
ing the interradial depressions somewhat smaller. Orals a little larger than
the other disk plates, and rather irregular in their arrangement. Anus

240 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

slightly excentric, forming a simple opening through the tegmen, and in
most of the specimens covered by a Platyceras equilatera Hall. Column
round and rather stout.

Horizon and Locality.— Keokuk group; Crawfordsville, Ind.; Hardin
Co., Ky.; and Keokuk, Lowa.

Type in the Lyon collection.

Remarks. — This species is Lyon and Casseday’s type of the genus Gonz
asteroidocrinus.

Gilbertsocrinus dispansus W. and Sp. (nov. sp.).
Plate XV. Figs. 2a, 6, ¢, d.
Syn. Gontasteroidocrinus lyonanus —S. A. Mrttur; Geol. Surv. Illinois, Bull. 35 Ds 55, Plate 4, Fig. 4.

Of the type of Gilbertsocrinus tuberosus, but a smaller species, the arms less
numerous, and the calycine appendages proportionally larger. Calyx some-
what depressed, wider than high, truncated at the bottom, the median
portions deeply excavated. Plates convex except the radials, which are
extended into elongate nodes or obtuse spines directed obliquely downward.

Infrabasals small, placed at the bottom of the concavity, and almost
covered by the column. Basals rather small for the genus; their distal ends
curving upwards and forming together with the median portions of the
radials a rim upon which the calyx rests, while the lower portions of those
plates are involved in the concavity. Radials very large, more than twice
as large as the costals, Costals and distichals of nearly the same size,
slightly projecting over the plates of the interradial and interdistichal areas.
Interradial areas composed of 1, 3, 3, 2, 2 plates; the middle one of the
second and third rows a little larger, and raised somewhat above the level
of the two outer ones; the anal side not distinct. Interdistichals three,
longitudinally arranged. Tegmen flat, with five deep interradial depres-
sions, of which the posterior one is twice as large as the others; all of them
oval in outline, and surrounded by a series of nodose pieces. The anal open-
ing occupies the inner end of the larger depression, and in perfect specimens
appears to be closed by a pyramid of numerous very minute pieces. The
smaller depressions are paved by four or five larger plates of irregular form.
The appendages are given off in pairs from the calyx, being for quite
a distance laterally connected; they are very large, slightly pendent, and —
each pair is composed of six longitudinal rows of transverse, slightly nodose

&

RHODOCRINIDZ. 241

pieces, alternately arranged. They separate at the eighth or tenth plate,
when they bend abruptly outward in opposite directions, and each simple
tube is thence composed of three rows of pieces. Arms short, pendent, and
recumbent; they are composed of two rows of plates, and pinnulated.
There being six arms to each arm opening, three to each main division,
but rarely more than three are exposed to view, the others being covered by
the appendages. |

Horizon and Locality. —Keokuk group; Indian Creek, Montgomery Co.,
Ind., where it has been found in splendid preservation. —

Types in the collection of Wachsmuth and Springer.

Gilbertsocrinus obovatus Mezerx and WorTHEN.
Plate X VIL. figs. 4a, 6.

1869. Goniasteroidocrinus obovatus—Merrx and WortuEen; Proceed. Acad. Nat. Sci. Phila., p. 76; and
1873, Geol. Rep. Illinois, Vol. V., p. 391, Plate 4, Fig. 6.
1881. Ollacrinus obovatus—W. and Sv.; Revision Paleocr., Pt. 11, p. 219.

Calyx urn-shaped; basal concavity deep, but narrower than in any of the
other species; the sides of the dorsal cup convex, constricted at the arm
bases; greatest width across the second costals; ventral disk perfectly flat.
Plates without ornamentation, strongly convex, and of rather uniform size.

Infrabasals small, forming together with the lower part of the basals
an inverted cup. Basals larger than any other plates of the calyx, bending
abruptly upwards and exposing two thirds of their surfaces in a side view.
Radials a little longer than wide, slightly larger than the costals, the lower
faces distinctly angular; the interradial plates considerably smaller. Dis-
tichals two, larger than the adjoining interbrachials; the second smaller
than the first. Arm openings proportionally small, at the bottom of a
shallow pit. Calycine appendages confluent at the proximal end, and
interradially disposed. Hach pair, before separation takes place, is composed
of six rows of plates, and each tube pierced by a moderately large central
canal. Length of appendages unknown, as is also the form and construction
of the arms. Interradial areas elliptical, arched by the distichals and the
plates supporting the appendages; they are composed of about thirteen
plates; arranged: 1, 8, 3, 3, 3, or 1, 3, 3, 2, 2, with slight variations at the
anal side. Interdistichals six to eight, the first touching the axillary distichal.
Plates of the ventral disk rather large and strongly convex; the interradial

depressions small, embracing only one or two pieces. Orals not distinct from
31

242 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the other plates. Anal opening almost central.. Column round, filling
nearly the whole width of the basal concavity ; axial canal small and pent-
angular,

Horizon and Locality. -— Highest part of the Upper Burlington limestone,
Burlington and Pleasant Grove, Iowa. Rare.

Lype in the Museum of Comparative Zodlogy, Cambridge.

ftemarks. — In this and the two preceding species, which were the last sur-
vivors of the genus, the individual tubes are constructed of three rows
of plates instead of a single one as in all others. This species, however,
differs essentially from all others in the form of the calyx. While in G.
tuberosus and similar forms the basals form the sides of the lower concavity,
they are placed in G obovatus at the sides of the dorsal cup, which is
decidedly convex in the latter, but flat or even concave in the former.

Gilbertsocrinus typus (H4t1).
Plate XIV. igs. 1, 2, 3, and Plate XVII. Figs. Va, b.

1859. Trematocrinus typus — Wauu; Suppl. Geol. Rep. Iowa, p. 73.
1872. Gilbertsocrinus (Irematocrinus) typus— Haut; Bull. Museum Nat. Hist., Plate 6, Fig. 13.
1878. Gontasteroidocrinus typus —Musx and WortuEn; Geol. Rep. Illinois, Vol. V., p. 390.
1881. Ollacrinus typus —W. and Sp.; Revision Paleocr., Pt. II., p. 219.
1889. Gontasteroidocrinus typus —S. A. Mtttpr; North Amer. Geol. and Paleont., De 50)

Syn. Lrematocrinus papillatus Wau; Suppl. Geol. Rep. Iowa, Vol. I, p. 76.

Calyx broadly concave at the base, somewhat inflated at the middle,
contracted near the top, spreading above into a projecting rim around the
upper margin. Ventral disk low-hemispherical or slightly convex. Basals,
radials, and interradials produced into sharp central spines or elongate
nodes; all other plates convex and slightly tumid. |

Infrabasals comparatively large, forming a pentagon, of which the greater
part 1s exposed beyond the column. Basals very large, curving so that the
lower halves of the plates rest within the columnar concavity, the upper
forming a part of the lateral walls of the dorsal cup; their spines directed
downward, while those of the other plates are directed outward. Radials
much larger than the costals; the interradials one half smaller, but larger
than the interbrachials. First distichal smaller than the second, the latter
higher and axillary, supporting two arms, which branch from the third
palmar, and again on one side from the third post-palmar, making a cluster
of arms to each opening. Arms pendent, long and delicate, uniserial to the
last bifurcation, when the plates become cuneate and interlock. Pinnules

RHODOCRINID&. 243

well proportioned. The calycine appendages pendent, unusually stout and
long, and composed of cylindrical joints whose apposed faces are striated.
The joints grow longer as they decrease in width, and at the end of the
tubes are twice as long as wide; they are thicker in the middle than at the
ends, and the median part is marked by a transverse row of little nodes.
The tubes of adjacent ambulacra are united to their sixth or seventh joints,
and the plates meet alternately by a zigzag suture. Interbrachials: 3, 3, 3,
3, 2— exceptionally two in the first row—the upper row abutting against
the appendages. The anal side has an additional plate in the second row.
Interdistichals about six to each area. Ventral disk pentangular in outline,
with five interradial depressions; the posterior one, which contains the anus,
larger; the plates of nearly uniform size and all convex. Orals undetermin-
able. Anus more excentric than in the preceding species. Column large
and round; the nodal joints higher and wider, their edges, like those of
the intervening joints, slightly rounded. Axial canal sharply stellate.

Fforizon and Locahty. — Upper Burlington limestone, and Burlington and
Keokuk Transition bed : Burlington and Pleasant Grove, Iowa.

Type in the Worthen collection.

femarks. — We regard Hall’s Trematocrinus papillatus as a mere varia-
tion of this species; the spines of the plates being shorter and the calyx more
robust. In the Revision, Part II., p. 219, we erroneously placed it as a
synonym under Giulbertsocrinus tuberculosus.

Gilbertsocrinus tuberculosus (Hatt).
Plate XVII. Figs. da, b, ¢.

1859. Trematocrinus tuberculosus — Hau; Suppl. Iowa Geol. Rep., Vol.. I., p. 75.
1881. Ollacrinus tuberculosus W. and Sp.; Revision Paleocr., Part II., p. 219.
1889. Goniasteroidocrinus tuberculosus —S. A. Mitten; North Amer. Paleeont., 250.

In the form of calyx and arrangement of plates, this species closely
resembles the preceding one, but the arms are erect instead of pendent, the
appendages much shorter, and they taper rapidly to a point. Plates strongly
convex or slightly nodose, the surfaces smooth.

Infrabasals placed at the bottom of a shallow concavity, which is formed
by the lower half of the basals, the upper half curving upwards, and taking
part in the lateral walls of the calyx. Basals and radials considerably larger
than any of the succeeding plates. Costals fully one half smaller than the
radials. Distichals 410; the two lower, which are placed in the calyx, as large

244 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

as the costals; the two upper shorter and free. There are four arms to each
arm opening, the upper bifurcation taking place from the third plate. Arms
rather stout and long for the genus; they are erect, biserial from the last
axillary, and have closely set pinnules. Calycine appendages small and short ;
directed outward, almost at right angles to the calyx. They are composed
of single joints, of which the four or five proximal ones of adjoining rays are
truncated laterally on apposed sides, and connected with one another by
rigid suture; the plates interlocking. After separating, the two tubes taper
rapidly, and terminate at the end of the fourth or fifth joint. The number
and arrangement of the interradial plates is quite variable ; bat in the major-
ity of specimens the plate between the radials is succeeded by three plates ;
some, however, have but two, except at the anal side which always has
three ; there are two or three in the next row, exceptionally four at the anal
side. Interdistichals five to six. Ventral disk low-convex, with well defined
interradial pits ; the posterior one larger, and containing the anus. Column
round; axial canal sharply stellate. |

Florizon and Locality. — Upper Burlington limestone ; Burlington, Iowa.

Type in the Museum of Comparative Zotlogy, Cambridge.

ftemarks. — Readily distinguished by the upright arms, and short, rapidly
tapering tubes.

_ Gilbertsocrinus reticulatus (Hatt).
Plate XVII. Figs. La, b.

1860. iene reticulatus — Hat; Descr. New Spec. Crin., p. 9; also Boston Journ. Nat. Hist.,
Vol Villy p. 325;

1881. Ollacrinus reticulatus — W. and Sp.; Revision Paleocr., Part IT., p. 219.

1889. Gontasteroidocrinus reticulatus —S. A. Mittur; North Amer. Geol. and Palont., p. 250.

Calyx small compared with the preceding species, about as wide as high ,
dorsal cup urn-shaped with convex sides and a wide and deep concavity
at the bottom; ventral disk almost flat. Plates slightly convex, their sur-
faces marked by a series of obscure ridges, radiating from the centre of the
plates to adjoining ones. The ridges follow the rays, and those passing
from the radials to the basals are stronger and somewhat higher; the latter
producing around the basal concavity at the bottom of the calyx the well
defined figure of a pentagon with convex sides. |

Infrabasals forming a pentangular disk, of which the angles project quite
plainly beyond the column. Basals large, their upper ends curving abruptly
upwards, the lower portions of the plates to two thirds their length, together

RHODOCRINID.2%. 245

with the infrabasals and the extreme ends of the radials, forming a wide and
deep inverted basin. Radials as large as the basals, a little longer than
wide. Costals nearly one half smaller than the radials, both of the same size,
and higher than wide. Distichals 2 x 2 in the calyx, nearly as large as the
costals; the upper excavated to form the arm openings, which are large and
circular. Appendages composed of single circular joints; the proximal ones
in contact laterally. Their length and the construction of the arms un-
known. Interradial spaces wide, elliptical; the plates between the radials
smaller than the costals; the interbrachials arranged in rows of three and
two plates, which decrease but little in size upwards. The anal interradius
apparently not distinct. Interdistichals one. Column round, composed
near the calyx of very short joints; the edges of the nodal ones knife-like.

Horizon and Locahty. — Lower Burlington limestone; Burlington, Lowa,
and Sedalia, Mo.

Type in the Museum of Comparative Zodlogy, Cambridge.

Gilbertsocrinus fiscellus (Mzex and Wortz.).
Plate X Vif, figs. 2a, 0; c,d.

1860. Zrematocrinus fiscellus— Munk and Wortu.; Proceed. Acad. Nat. Sci. Phila., p. 383. |

1865. Gilbertsocrinus (Goniasterotdocr.) fiscellus — Mek and Wortu.; ibid., p. 167.

1866. Gilbertsocrinus fiscellus — Merk and Wortu.; Geol. Rep. Illinois, Vol. IT., p. 222, Plate 15, Fig. 5.
1881. Ollacrinus fiscellus — W. and Sp.; Revision Paleoer., Part II., p. 219.
1889. Gontasterordocrinus fiscellus —S. A. Mixer; North Amer. Paleont., p. 250.

A small species, smaller even than G. reticulatus, which it resembles
in general form; but the sides of the calyx are straighter, the basal con-
cavity narrower, and the ridges upon the plates less conspicuous.

Infrabasals very small, covered by the column. Basals hidden almost
completely within the lower cavity, so that the radials and first interradials
form the lower ring of plates visible from a side view. Costals as long as
wide, and but little smaller than the radials. The second distichals support
the free arms, of which the first joint is short and quadrangular. The arm
openings of the same ray are placed closer together than in any other
American species, and the tubes bordering the anal interradius are simple,
with several interradial plates interposed between them; while those of
the other sides, on the contrary, are united in pairs. Nothing further is
known of the appendages and arms. Interradial areas arranged: ‘1, 8, ‘3, 3;
3, 2; the lower plate somewhat larger. The anal side generally has five

246 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

plates in the third, fourth, and fifth rows, and two small plates above. Inter-
distichal areas composed of a rather large plate, succeeded by four or five
smaller ones. Ventral disk almost flat, with deep interradial depressions.
Some of the plates are larger and more convex, but none of them are refer-
able to orals. Anus subcentral, on top of a small protuberance. Column
unknown.

fforizon aud Locality. — Lower Burlington limestone ; Burlington, Iowa.

Type in the Museum of Comparative Zodlogy, Cambridge.

Gilbertsocrinus tenuiradiatus (M. and W.).
Plate XVIT. Fig. 8.

1869. Gontasteroidocrinus tenuiradiatus —Mernk and WortuENn; Proceed. Acad. Nat. Sci. Phila., p. 75.
1878. Goniasteroidocrinus tenuiradiatus —Mexnx and WortHEN; Geol .Rep. Illinois, Vol. V., p. 389, Plate
1881. Avan tata W. and Sp.; Revision Paleocr., Part IT, Dees

1889. Gontasterordocrinus tenuiradiatus —S. A. Mituer; North Amer. Geol. and Paleont., p. 250.

The two specimens before us are considerably crushed, and their general
form and the arrangement of the plates cannot be accurately determined.
It is a larger species than the two preceding ones, with which it is found
associated, and which it resembles in the delicacy of the plates; but in other
respects 1t is more like G. typus, of a higher horizon. The surface of the
plates is marked by a series of elevations, radiating from the middle of the
plates to adjoining ones, which, however, are not ornamented ridges, but are
produced by a folding of the plates. The basal concavity is quite shallow,
and composed almost exclusively of the infrabasals.

Basals large, curving upwards and inwards, their upper lateral faces
longer than the corresponding lower ones; they are extended into a sharp,
slender spine rising from the centre of the plates, unlike the case of G. typus,
in which the spines cover the whole surface of the plate. Radials very
large, and mounted with similar spines as the basals. Arms given off from
the second distichals; their structure unknown. Calycine appendages very
long, and tapering but slightly; their joints are strictly cylindrical and
devoid of ornamentation ; they are arranged interradially in pairs, and those
of each pair are connected laterally by zigzag sutures to the fourth or fifth
joint, when they become free and diverge in opposite directions. The
number of arms and the number and arrangement of interradial and inter-
distichal plates cannot be ascertained in the specimens.

RHODOCRINID&. DAT

Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa.

Type in the Museum of Comparative Zodlogy, Cambridge.

Remarks. —— This species is distinguished from G. typus by the form of
the spines on the basals and radials, the thinness and delicacy as well as the
folding of the plates, and by the cylindrical form and smoothness of their
appendages. |

Gilbertsocrinus spinigerus (Hatt).

Pudie MV. PAGS. 3G, 0c.

1862. Trematocrinus spinigerus — Hat; 15th Rep. N. Y. State Cab. Nat. Hist., p. 128.

1866. Goniasteroidocrinus spinigerus — Munk and Wortu.; Geol. Surv. Illinois, Vol. IL, p. 222.

1872. Gilbertsocrinus (Trematocrinus) spinigerus — Hat; New York State Mus. Nat. Hist., Bull. I., Plate
la, Fig. 9 (privately distributed).

1877. Goniasteroidocrinus spinigerus —8. A. Mittur; Cat. Amer. Paleoz. Foss., p. 80.

1881. Ollacrinus spinigerus — W. and Sr. ; Revision Paleocr., Part I1., p. 219.

1889. Gontasteroidocrinus spinigerus —S. A. Miniter; North Amer. Geol. and Paleont., p. 250.

A small species. Calyx widest across the radials, somewhat constricted
at the arm bases, expanding at the upper margin. The rays marked by
broad, rounded ridges proceeding to the arm openings, and giving to the
section across the costals a pentangular, and across the distichals a decagonal
outline; while the section at the margin of the disk, where the appendages
meet in pairs, assumes again a pentangular outline, but the angles are inter-
radial instead of radial. The plates without ornamentation, but the radials,
first costals and first interradials are extended into sharp nodes or small
spines. Basal concavity deep and wide, involving the infrabasals, basals, and
portions of the radials and interradials.

Infrabasals comparatively large, forming a regular pentagon. Basals
large ; their upper sloping faces twice as long as the corresponding lower
ones ; broadly truncate above. Radials of nearly the same size as the basals,
and deeply wedged in between them. First costals considerably larger than
the second, and but little smaller than the radials. Distichals quite small,
especially the second, which is deeply excavated to form the arm openings.
Calycine tubes confluent at four sides, those facing the anal side simple and
separated by anal plates. The appendages are short, directed almost horizon-
tally, and are composed of joints about as long as wide. Arms erect, rather
stout, the plates cuneate; they start in pairs from the calyx, branch on the
fifth plate, and again on the eighth. The plates of the interradial spaces
small, except the first which is very large; it is followed by 3, 38, 8, 3, and
two plates. Interdistichals three or more. Ventral disk flat, with deep

248 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

interradial depressions, surrounded by small nodose plates of rather irregular
arrangement. Orals tuberculous; anus excentric.

Horizon and Locality. ——- Hamilton group; Ontario Co., and Thedford,
Ontario.

Types in the New York State Cabinet of Natural History at Albany, and
in the Canada Survey Museum at Ottawa.

THYLACOCRINUS Ocstext.

1878. Onruuert; Extr. du Bull. Soe. Géol. de France (sér. 8) Tome VITI., p. 578.

1879. Zirren; Handb. d. Paleont., Vol. I., p. 375.

1881. W. and Sp.; Revision Paleocr., Part IL, p. 207 (Proceed. Acad. Nat. Sci., Phila., p. 381).

Calyx large, plates convex; anal interradius distinct from the others;
arms arranged in groups of four or more. Infrabasals five, small. Basals
five, heptagonal; their upper faces truncated, and each plate supporting an
interradial. Radials followed by two costals, and these by 2X2 distichals,
which in turn support within the calyx several brachials of a third, and
sometimes. of a fourth order. Arms heavy, long, simple throughout, and
biserial. Interbrachials numerous, arranged longitudinally in series of two
or three, with additional plates at the anal side. Interdistichals very numer-
ous, in rows of one or two; interpalmars also represented. Construction of
the tegmen and position of the anus unknown. Column, so far as observed,
pentangular with re-entering angles. |

Distribution. — Devonian; France, and Hamilton group; Western New
York.

Type of the genus. — Thylacocrinus Vannioti Oeblert.

ftemarks. — Thylacocrinus differs from Rhodocrinus in having interdis-
tichals and interpalmars; the former being very rarely, the latter never,
preserved in that genus. It also differs in the arrangement of the plates
of the anal side, in having four or more primary arms to the ray in place of
two, and in that the arms are large and simple throughout.

Thylacocrinus Clarkei W. and Sp. (nov. spec.).

Plate XIII. Figs. 11a, b.

Calyx apparently globular; the plates very gradually and uniformly de-
creasing in size upwards. Infrabasals small, and forming a pentagon with the
points of the angles slightly projecting beyond the column; column attach-

RHODOCRINID 2. 249

ment stelliform, somewhat concave, the margin surrounded by concentric striz
as in Jurassic Pentacrinide. Basals large, slightly curving upward. Radials
as wide as high, of the same size as the costals. Distichals 2x2, a little
shorter than the radials. The four lower palmars form part of the calyx,
the upper are free; the fixed plates considerably highest, but decreasing in
height upwards; the three proximal arm plates subquadrangular, the suc-
ceeding ones gradually turning from cuneate into biserial, meeting laterally
by a zigzag suture. Arms four to each ray, simple throughout, rather strong
at the bases; their length unknown. Interbrachials: 1, 2, 3, 2, etc., some-
what smaller than the adjoining brachials. Anal interradius wider, with
three plates in the second, and four in the third row. Interdistichals in
about six ranges, arranged in pairs from the first plate up. Interpalmars
three to four, arranged longitudinally in single file. Ventral disk and
anal opening unknown. Column pentangular with re-entering angles near
the calyx; the joints of nearly equal width; the salient angles of the nodal
ones bearing a small tubercle.

Horizon and Locality. — Hamilton group; Canandaigua Lake, N. Y.

Type in the New York State Cabinet of Natural History at Albany.

Remarks. — The species is described from a somewhat crushed specimen,
formerly in the collection of Prof. John M. Clarke of Albany, N. Y., in whose
honor the specific name is given.

DIABOLOCRINUS W. and Sp. (nov. gen.).
(AtaBodos, the devil; kpivov, a lily).

Syn. Rhodocrinus Gn part) — Wurrer, 1880; Proceed. National Museum, Vol. II., p. 259.

Syn. Lyriocrinus (in part) —S8. A. Minusr, 1882; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 117.

Syn. Archeocrinus (in part) — W. and Sp., 1885; Proceed. Acad. Nat. Sci. Phila. p. 320.

Syn. Archeocrinus Gn part) — W. and Sp., 1885; Revision Paleocr., Part III., p. 98.

Syn. Archeocrinus (in part) —S. A. Mittur, 1889; N. A. Geol. and Paleont., p. 225.

Calyx depressed globular, with a wide and deep concavity at the bottom,
involving the infrabasals and large portions of the basals. Infrabasals five,
small, but projecting beyond the column. Basals large, elongate; their
upper half directed horizontally or bending upwards; the upper faces broadly
truncated. Radials not in lateral contact, being separated from each other
by one or more plates, which rest upon the basals. Costals two. Arms two
to the ray, free from the first or second distichals; their structure unknown.

Arm openings very large, directed obliquely upward, and arranged in groups.
32

250 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Interradial spaces wide, composed throughout of large plates, which connect
with the disk plates, or, properly speaking, pass into the disk. The large
plates between the radials are frequently surrounded by small supplementary
or secondary pieces, which wholly or partly isolate them from the basals,
radials and costals. The second range of interradials consists of two, excep-
tionally three, pieces, the third of three; the latter forming part of the upper
margins of the arm openings. The anal interradius, which is wider than the
others, has three plates in the second, and four or more in the third row.
Ventral disk depressed conical; composed of rather large plates, none of
them conforming to the general arrangement of orals, which are probably
unrepresented. Anus almost central, and at the end of a strong tube.
Column round or indistinctly pentangular, with a large pentalobate canal.

Mstribution. — The three species herein described come from the Trenton
group of Hastern Tennessee. In the same locality we found a fourth species,
but none of the specimens so far obtained are sufficiently well preserved for
description.

Ltemarks.-- We make our Diabolocrinus perplecus the type of the genus.
Diabolocrinus has closer resemblance to Lyriocrinus and Archwocrinus than
to Rhodocrinus, but is readily distinguished from both of them. In Lyrio-
crmus the arm facets are directed strictly upwards, the arms are single
and placed in a straight line with the walls of the dorsal cup; while in
Diabolocrinus the arms were apparently given off as armlets from tubular
prolongations of the calyx, and the facets are directed obliquely outward.
Archeocrinus has a more elongate calyx, the disk consists of minute irregular
pieces, it has no anal tube, and never supplementary pieces such as we find
in D. perplecus. The latter is a feature that reminds us of Refeocrinus, Xeno-
crimus, and Acrocrinus, in which a similar intercalation of plates takes place
on a much larger scale.

Diabolocrinus perplexus W. and Sp. (nov. spec.).
Plate XI. Figs. 1a, b.

Length of calyx as compared with its width three to two; pentangular
across the arm bases; the dorsal cup more than twice the height of the
tegmen ; basal concavity wide and moderately deep, involving nearly the
whole of the basals. Plates convex, the larger ones bearing one or more
conspicuous nodes, the others a single central one.

RHODOCRINID 2%. Dom

Infrabasals completely hidden by the top stem joint. Basals large, elon-
gate, barely seen in a side view, longitudinally grooved at the median line,
which gives to the cavity a decidedly pentangular outline; the angles of the
upper face truncated for the reception of supplementary pieces, which in this
species are not only constantly represented but quite regular in their arrange-
ment. Costals less than half the size of the radials. Distichals still smaller
and free above the first. Arm openings in pairs; elongate. Interradials
1, 2, 3 in the dorsal cup; the first, which is nearly as large as the basals,
surrounded variously by from two to four supplementary pieces, two of them
abutting against the radials and basals, and two against the radials and first
costals. These plates vary greatly in size, being in some specimens very
minute, while they are comparatively large in others. In very large speci-
mens, when completely developed, the first regular interradial is surrounded
by six plates — including the two regular interradials of the second row —
and by seven plates at the anal side. In cases in which the supplementary
pieces are small and imperfectly developed, the first interradials touch the
radials and basals. Tegmen composed of rather large plates without any
regularity in their arrangement ; the interradial portions depressed, those
concealing the ambulacra quite prominent. Column small, obtusely pentan-
gular; axial canal very large.

Horizon and Locality. Trenton group, near Knoxville, Tenn.

Types in the collection of Wachsmuth and Springer.

Diabolocrinus vesperalis (Wuts).

Plate XI. Figs. 1c, d.

1880. Rhodocrinus vesperalis — Wuitn; Proceed. U. 8. Museum, Vol. II., p. 259.
1883. Rhodocrinus vesperalis —Wuite; Twelfth Ann. Rep. U.S. Geol. Surv. Terr., by Hayden, p. 199,
Plate 35, Figs. 4a, 6.

Syn. Lyriocrinus sculptilis —8. A. Miter ; 1882 (not Hall 1851), Cincin. Journ. Nat. Hist., Vol.
V., p. 117, Plate 3, Figs. 6a, d.

Syn. Lyriocrinus sculptus —S. A. Mitter; ibid. (private ed., Explanation of plate).
Syn. drcheocrinus sculptus —W. and Sp. 1885; Revision Paleocr., Part III., pp. 96-98.
Syn. Archeocrinus sculptus —S. A. MituEr, 1889; North Amer. Geol. and Paleont., p. 225.
Calyx depressed subglobose, pentangular across the arm bases; the basals
to one third their length forming a funnel-shaped concavity, of which the
infrabasals form the bottom part. Plates but very slightly convex, densely
covered by wrinkles or indistinct strize.

Infrabasals invisible beyond the column. Basals large, elongate, the prox-

De THE CRINOIDEA CAMERATA OF NORTH AMERICA.

imal portions concave; the distal portions of the plates bending upwards;
the faces supporting the interradials broadly truncated. Radials sometimes
smaller than basals and interradials, their lower faces decidedly angular.
Costals smaller than the radials; the second shorter and narrower than the
first. Distichals to the height of the second plate incorporated into the
calyx, the succeeding ones free; the plates short and semilunate. Regular
interradials: 1, 2, 3, the first nearly as large as the basals, the upper ones
considerably smaller; the supplementary pieces irregularly distributed among
the interrays, or absent altogether. Tegmen as in the preceding species.

Fforizon and Locality. —Same as last.

Type in the National Museum at Washington.

ftemarks. This form was described by White in 1880 under the name
of Lthodocrinus vesperalis, and it was stated that the specimen probably came
from the coal measures, thirty miles west of Humboldt, Kans. §S. A. Miller
redescribed the species in 1882 as Lyriocrinus sculptus,* giving “Tennessee ”
as locality, and “ Niagara group” as the probable horizon. The specimens
from which our figures are made were collected by one of us in 1883, from
rocks of the Trenton group at Knoxville, Tenn., where they were found
associated with Hybocrinus and other typical Trenton forms. We have com-
pared these specimens carefully with White’s type of Rhodocrinus vesperalis in
the National Museum, and also with Miller’s Lyriocrinus sculptus in his own
collection, and not only find the various specimens specifically identical, but
think it most probable that they all came from the same locality.

Diabolocrinus hieroglyphicus W. and Sp. (nov. spec.).
Plate X. Figs. da, b, ec.

Calyx globose ; basal portions deeply depressed, forming a narrow fun-
nel-shaped pit, of slightly pentangular outline, which encloses the whole of
the infrabasals and one fourth of the basals. Arm openings directed ob-
liquely upwards, and invisible in a dorsal view. Plates of the dorsal cup
covered with numerous elongate nodes, of irregular form, which give to
the surface an appearance suggestive of being densely covered with hiero-
glyphics. The rays are marked by conspicuous ridges following the median
line of the plates, and similar ridges pass out from the centre of the radials

* It was described in the Journal of the Cincinnati Society under the name of Lyriocrinus sculptilis ;
but Miller, on finding the name preoccupied, changed it in his private edition to L. sculptus.

RHODOCRINID.2. Zoe

to adjoining basals, the latter forming upon the surface a well defined five-
rayed star, whose salient angles alternate with the angles of the basal
concavity.

Infrabasals small, and almost completely covered by the upper joint of
the column. Basals large, elongate; spread out horizontally, except their
lower ends, which form the sides of the funnel-shaped pit. Radials large,
their lower faces sharply angular. Costals smaller than the radials; the
second considerably smaller than the first. Distichals free from the second
plate ; very short. Arm structure unknown. Interbrachials: 1, 2, 3, 2, 1,
with variations of three plates in the second, and two to four in the third
ranges ; the first plate large, being next to the basals the largest plate of the
calyx; the plates of the second row considerably smaller, especially when
there are more than two plates in that row. The supplementary interradials
are less frequently represented than in the preceding species, and rarely by
four plates to the interray ; but there is scarcely a specimen in which there
is not at least one of them introduced at one side. The plates of the third
row are placed between the arm bases; the succeeding ones form part of the
ventral disk. The anal side is wider and the plates more numerous; there
being three or four in the second row, and four or more in the succeeding
ones. Ventral disk almost as high as the dorsal cup; composed of rather
large convex plates of nearly uniform size. Orals cannot be identified, the
whole ventral pavement consisting of the same kind of irregularly arranged
plates. Anus nearly central, extended into a strong tube. Column near
the calyx apparently slightly pentangular; central canal very large and
pentalobate.

Horizon and Locality. — Trenton group ; near Knoxville, Tenn.

Types in the collection of Wachsmuth and Springer.

Ltemarks. —'This species is distinguished from the preceding one by the
different form of the calyx, the peculiar style of ornamentation, and by the
irregularity in the distribution of supplementary pieces in the interradial
series.

ARCHZGOCRINUS W. and Sp.

1881. W. and Sp.; Revision Paleocr., Part II., p. 189; also Proceed. Acad. Nat. Sci. Phila., p. 363.
1885. W. and Sp.; Revision Paleocr., Part III., p. 96; Proceed. Acad. Nat. Sci. Phila., p. 318.
1883. 8. A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. VI., jos 2s

1889. S.A. Mrnuer; N. Amer. Geol. and Palezont., p. 224.

Calyx large, obconical or subovate; plates smooth or variously orna-
mented; those in a radial direction marked along their median line by

954 — THE CRINOIDEA CAMERATA OF NORTH AMERICA.

obscure, flattened ridges, which grow more conspicuous on approaching
the arms. Infrabasals small, rarely extending beyond the column, and
resting, as a rule, within a concavity formed by the lower part of the
basals. Basals heptagonal, their upper faces truncated. MRadials in three
of the rays pentagonal, in the two posterior ones frequently hexagonal.
When there are no palmars the three to six lower distichals take part in the
calyx, and the succeeding ones are free arm plates. Arms short, slender,
branching ; composed of two rows of cuneiform pieces, alternately arranged
and interlocking. Interradial areas constructed of numerous plates; the
plate between the radials, which is much larger than the others, is followed
at the regular sides by two interbrachials in the second row, at the anal side
by three, but there is no median ridge or continuous row of anal plates.
The upper interbrachials connect imperceptibly with the plates of the disk.
Interdistichals always represented. Ventral disk, as observed in A. desideratus,
composed of small irregular pieces, which close over the ambulacra, except
near the outer margin of the integument, where their covering pieces are
exposed. Column round, the edges of the nodal joints largely projecting
over the internodal ones; axial canal large, pentalobate.

Distribution. — Probably restricted to the Trenton group of America.

Type of the genus: Archwocrinus lacunosus (Billings).

Remarks. — Archeocrinus has close affinities with Rhodocrinus, and it is
somewhat difficult to point out the structural differences. The calyx of the
former is relatively larger, the arms shorter, and it has but two interbrach-
ials in the second row; while Afodocrinus, as a rule, has three plates in the
second and all succeeding rows; and the anal interradius very often has the
same arrangement of plates as the others.

Glyptocrinus marginatus Billings, which in 1881 we placed under Archeo-
crinus, proves to be a monocyclic form, and will have to be referred back to
Glyptocrinus as a somewhat aberrant type. Whether Rhodocrinus asperatus
Billings belongs here, cannot be ascertained from the imperfect state of the
‘specimen. Lyriocrinus sculptus 8, A. Miller (Archcocrinus sculptus W. & Sp.)
is a synonym of Rhodocrinus vesperalis White, which has been placed under
the genus Diabolocrinus. -

RHODOCRINID 2%. 255

Archeocrinus lacunosus (BILLrINées).
[NGG A SEE II

1857. Glyptocrinus lacunosus— Bruuines; Geol. Rep. Canada (Rep. of Progr.), p. 261, also ibid. 1859,
Decade IV., p. 61, Plate 8, Figs. 3 a-e.
1881. <Archeocrinus lacunosus — W. and Sp.; Revision Paleoer., Part IL., p. 190.

The only known specimen is somewhat crushed, and its exact form can-
not be ascertained, but it was probably subglobose. The median line of the
rays 1s followed by ridges, which grow quite prominent upon the distichals,
and the surface of the plates is completely covered by small rugose pits and
wrinkles. |

Infrabasals very minute, not visible from a side view. Basals unusually
large, the largest plates of the calyx; their truncated upper side very wide.
Radials slightly smaller than the basals, the two facing the posterior side hep-
tagonal, the others pentagonal, all sharply angular below. Costals rather
small. The three lower distichals take part im the calyx; they are small
and curved like free arm plates. Arms ten at their origin, rounded, rather
delicate, bifurcating once or oftener, the branches divergent, and composed
of short interlocking pieces. Interbrachials large ; those between the radials,
which are almost as large as the basals, rise to the middle of the second
distichals, and are followed by two plates in the second range, and others
above ; anal side wider, plates arranged: 1, 3, 4, ee. Column round, tap-
ering considerably downward; the nodal joints very high, even those next
the calyx, which are twice as wide as the intervening ones, and thick and
rounded at the edges; the internodal joints comparatively short. At six em.
from the calyx the internodes contain five joints, and this number apparently
does not increase in the lower part of the stem.

_ Horizon and Locality.— Upper part of Trenton group; Ottawa, Canada.

Type in the Canada Survey Museum at Ottawa.

Archeocrinus pyriformis Brizurnes.
Plate X. Figs. 3a, b.

1857. Thysanocrinus (Rhodocrinus) pyriformis —H. Biuurnes ; Geol. Rep. Canada (Rep. of Progr.), p. 263.
1859. Rhodocrinus pyriformis — Hi. Brturnes; ibid., Decade IV., p. 61, Plate 6, Figs. la-d.
1881. Archeocrinus pyriformis —W. and Sp.; Revision Paleocr., Part II., p. 190.

A large species. Calyx obconical or pyriform; one fourth higher than
wide; greatest width across the second distichals, slightly contracting above.

256 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Surface of plates smooth or finely granulose; the radial plates somewhat
elevated along their median lines; sutures distinct, but not grooved.

Infrabasals larger than in any other known species of this genus, and
plainly visible from a side view, forming a shallow cup. Basals large, a little
higher than wide, upper face narrowly truncated. Radials and costals of
similar size; the former pentagonal, the two costals hexagonal, except in
the posterior rays in which the second is heptagonal. Distichals to the
height of the sixth plate incorporated into the calyx, gradually decreasing
in height; the first as large as the second interbrachials, the upper one
resembling a good sized arm plate. Arms short, delicate, twice bifurcat-
ing; composed from their bases up of small triangular interlocking pieces.
Interbrachials: 1, 2, 2, 2, etc., rarely 1, 2, 8, 8, the lower plate heptagonal,
larger than the radials; at the anal side there are three plates in the second
and all succeeding rows. Interdistichals nine or more, rather large. Struc-
ture of ventral disk and anus not- known. Column circular, slightly tapering ;
in the upper part of the stem the nodal joints project, but further down have
the same size as the others.

fforizon and Locality.— Trenton limestone ; Montreal, Canada.

Types, in the Canada Survey Museum at Ottawa.

Archeocrinus microbasalis Biturwes.
Plate X. Figs. 2a, b, ¢.

1857. Thysanoerinus (Rhodocrinus) microbasalis —H. Briurnes; Geol. Rep. Canada (Rep. of Progr.)
p. 264; also ibid., Deeade IV., p. 63, Plate 6, Fig. 2.
1881. <Archeocrinus microbasalis —W. and Sp.; Revision Paleocr., Part II., p. 190.

Smaller than the preceding species, the arms proportionally longer.
Calyx obconical, truncated at the lower end, sides slightly convex. Surface
beautifully ornamented with parallel, radiating strie, proceeding from the
middle of the plates to adjoining ones, and broad, rounded ridges, starting
from the middle of the radials and passing up the costals and distichals into
the free arms.

Infrabasals minute, forming a pentagon, which rests within the basal con-
cavity and is covered by the column. Basals large, heptagonal, more than
two thirds of the plates visible from a side view, the lower end bent inward
and forming, together with the infrabasals, a good sized concavity, with a
thickened rim around the edge; the upper faces narrowly truncated. Radials
as large as the basals, distinctly angular below; the costals somewhat smaller,

RHODOCRINID. 257

The lower distichals to the number of seven or eight take part in the calyx;
they decrease rapidly in size, the lower one being comparatively large, but
the fourth is but little larger than the free plates; the plates above are tri-
angular and interlock. Arms long, rather stout at their bases, but tapering
gradually to the tips where they are quite thin; they bifurcate twice or
oftener, and are composed of two rows of plates with parallel faces. Regu-
Jar interbrachials: 1, 2, 3, 3, followed by numerous smaller plates; the
anal side has 1, 3, 3, 4, ete. Of interdistichals as many as fourteen pieces
have been observed, the lower one resting upon the first distichals. Con-
struction of the ventral disk and form and position of the anal opening
unknown. Column round, tapering downward; the upper part composed
of alternately large and small joints with angular edges; but at about three
inches from the calyx the internodal joints reach the width and height of
the nodal ones, and the edges lose their angularity.

florizon and Locality. — Trenton limestone ; Ottawa, Canada.

The figured specimens are in the collection of Mr. John Stewart of
Ottawa. Type in the Geological Survey Museum at Ottawa.

Archeocrinus desideratus W. R. Bruines.
Plate X. Figs. 4a, 6.

1885. W.R. Biriines; Trans. Field Natur. Club, Ottawa No. 6.
1885. W. and Sp.; Revision Paleocr., Part IIL. p. 98.

A rather large species. Calyx depressed globose ; basal portions deeply
depressed, forming a broad funnel-shaped pit, much wider than the circum-
ference of the stem, and deep enough to contain five or six stem joints.
Plates convex, without ornamentation or other markings, except obscure
elevations —a kind of broad, rounded ridges — following the median line
of the rays, and branching to the basals.

Infrabasals small, hidden by the column. Basals large, twice as long as
wide; the lower half of the plates forming the sides of the basal pit; the
upper halves, which bend abruptly upward and outward, occupy the sides
of the cup. Radials pentagonal, almost as long as wide, their lower faces
forming a sharp angle, which extends down to the margin of the basal
concavity. First costals hexagonal, as wide as the radials, but shorter ; the
second shorter and narrower than the first. Distichals 4X2, all incorporated

into the calyx, and comparatively small; they are rounded exteriorly, and
33

258 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the two series of the same ray are so nearly in contact as to leave but a nar-
row space for the insertion of interdistichals. First distichals somewhat
longer than the succeeding ones, which are quite short; the fourth is axil-
lary, giving off to the outer sides a row of palmars, which are free from the
third or fourth plate ; to the inner side two palmars, of which the upper
is axillary, and supports two arms, making three arms to each side of the
ray. Arms subcylindrical, stout, very little tapering; composed at their
bases of a few quadrangular pieces, followed by cuneate ones, which deeply
interlock. Pinnules strong, given off nearly at right angles, and composed
of short joints; the first very much stouter than the others, given off from
the second distichals, and wholly or partly incorporated into the calyx.
Interradial spaces wide, the upper portions rather deeply depressed. The
plates of the two lower ranges very large, the first being the largest plate in
the calyx. There are probably five or six rows above, but the number
of plates in each row is extremely variable; the third contains variously
from three to five plates at the regular sides, and from four to six at the
anal side; the fourth row has as many as eight in some specimens. The
first plate of the anal side is somewhat larger than those of the regular
sides; it is octagonal, its upper angle being slightly truncated for the recep-
tion of a narrow anal plate, which is placed between two interbrachials.
Interdistichals from one to three, longitudinally arranged. Ventral disk
rather flat, composed of very small irregular pieces; the ambulacra subteg-
minal, except near the arm bases, but the course of the ambulacra is marked
by high ridges which diverge to the arms, and form deep depressions all
along the interambulacral spaces. Orals apparently unrepresented, the sum-
mit beimg covered by similar small plates to the rest of the disk. Anal
opening subcentral, at the top of a well defined protuberance. Column
round; axial canal large, pentalobate, the outer ends of the lobes widest
and truncated. |
Horizon and Locality. — Trenton limestone ; Ottawa, Canada.
Types in the collection of Mr. Walter R. Billings, Ottawa.

RHAPHANOCRINUS W. and Sp.

1885. W. and Sp. ; Revision, Part III., p. 98 (Proceed. Acad. Nat. Sci. Phila., p. 320).
1887. Orntert; Ann. des Sci. Géol., Tome XIX., Plate I., Figs. 10, 11.
1889. S. A. Minter; North Amer. Geol. and Paleont., p. 277.
Syn. Glyptocrinus Gn part) — Watcort; 1883, New Spec. Foss. of the Trenton group of New York,
p. 2 (Abstr. from the 35th Rep. New York State Museum Nat. Hist.).
Syn. Glyptocrinus (in part) —S8. A. Mituer; Journ. Cincin. Soe. Nat. Hist., Vol. V., p. 87, and
ibid., 1883, Vol. VI., p. 224.

RHODOCRINIDA. © 2909

Allied to Archwocrinus, but arms uniserial and not bifurcating. Radial
ridges generally well developed. Infrabasals small, not visible from a side
view, and generally completely hidden by the column. Basals large, hexa-
gonal, the upper face truncated for the reception of the first interradials.
Radials and second costals of similar form, but the former angular below,
the latter angular above. Arms ten to twenty, free from the distichals or
palmars according to species; they are stout, long, simple, and composed
of quadrangular pieces with strong pinnules, Interbrachials and interdis-
tichals numerous. Structure of ventral disk, and form of the anus unknown.
Column large and round.

Distribution. — Both American species are from the Lower Silurian. Oeh-
lert described a species from France under the name Rhaphanocrinus Wachs-
muthi, which came from the “Dévonien inférieur,” but this is apparently
not a typical form. .

Type of the genus: Lhaphanocrinus subnodosus.

\

Rhaphanocrinus subnodosus (Watcorr).
ROME RO tg

1883. Glyptocrinus (?) subnodosus — Waucotr; 35th Rep. N. York State Mus. Nat. Hist., p- 208, Plate
1885. eres subnodosus — W. and Sp.; Revision Paleocr., Part III., p. 99.

Calyx of medium size, obconical; interradial areas depressed. Radial
ridges well defined and marked by a small node in the centre of each plate;
they pass down to the middle of the radials, where they meet with similar
ridges from the two adjoining basals. The interradials have also a central
node, from which obscure ridges pass out to the margins of the plates, where
they meet with ridges from adjacent plates.

Infrabasals completely covered by the column. Basals very large, fully
as high as wide, slightly truncate above. Radials heptagonal, larger than
either one of the costals, decidedly angular below. Arms ten, rather stout,
simple, the lower plates incorporated into the calyx, the second and all suc-
ceeding ones pinnule-bearing; they are composed throughout of compara-
tively long, quadrangular joints, with stout pinnules, placed wide apart.
Interradials: 1, 2, 3, 3, and two or more rows above. Interdistichals: 1, 2.
Nothing is known of the ventral disk or of the anal opening. Column
round, very large.

260 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Horizon and Locality. — Upper portion of the Trenton limestone; Trenton
Halls, N.Y.
Type in the Museum of Comparative Zodlogy, Cambridge.

Rhaphanocrinus sculptus (Mitzer).
Plate X. Hig. 8.

1882. Glyptocrinus sculptus—S8. A. Mittrr; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 37, Plate L,
Fig. 2.

1883. Glyptocrinus sculptus —S8. A. Mitusr; ibid., Vol. VI., p. 224.
1885. Glyptocrinus sculptus — W. and Sp.; Revision Paleocr. Part III., p. 104.
1889. Glyptocrinus sculptus —S. A. Minter; N. Amer. Geol. and Paleont., p. 248.

Calyx subglobose; interradial spaces deeply depressed, especially the
upper portion; section across the second costals sharply pentagonal, across
the distichals decagonal. Radial ridges quite prominent, angular, stronger
toward the sutures than at the median portion of the plates. Somewhat
smaller ridges pass into the basals, forming deep triangular depressions along
their sides. Other ridges run from the radials and brachials to the inter-
radial plates, dividing the whole surface into numerous impressed triangular
areas.

Infrabasals almost covered by the column. Basals of medium size, pro-
duced into angular processes, which point downward for a short distance
along the sides of the upper stem joints. Radials and costals about as wide
as long. Distichals three, almost as large as the costals. The plates of the
third order support the arms, of which there are twenty; they are long,
gradually tapering, and composed of quadrangular joints which become
slightly cuneate in the upper parts of the arms. The four to five lower
joints, which are considerably the largest and sharply angular on the out-
side, take part in the calyx; the succeeding ones are free, much shorter, and
rounded. Pinnules long and slender. Interradial spaces deeply depressed
between the distichals; the plates arranged: 1, 2, 3, 3, ete. The anal side,
which is a little wider, has a few additional plates, but no anal ridge. Inter-
distichals: 1, 2, 1. Structure of ventral disk unknown. Column round,
slightly tapermg downwards, the nodal joints, near the calyx, wider and
considerably longer than the intervening ones, but at two inches below the
latter reach almost the same size.

fforizon and Locality.-- Upper part of the Hudson River group; Warren
Co., Ohio.

Types in the collection of I. H. Harris, Esq., at Waynesville, O.

RHODOCRINID&. 261

Remarks, — Rhaphanocrinus sculptus was described as monocyclic, and
referred by 8. A. Miller to Glyptocrinus. The infrabasals are only seen
as small dots around the column. The species is readily distinguished from
allied forms by having knife-like ridges upon the fixed brachials; while the
back of the free brachials is perfectly round.

LYRIOCRINUS Hatt.

1852. Hatt; Geol. Rep. N. Y, Paleontology, Vol. IT., p. 197.

1857. Prcrer ; Traité de Paléont., Vol. IV., p. 329.

1862. Dusarpin and Hurt; Hist. Natur. des Zooph. Echinod., p. 149.

1866. Suumarp; Trans. Acad. Sci. St. Louis, Vol. II., p. 379. |

1867. Harn; 20th Rep. N. Y. State Cab, Nat. Hist., p. 325.

1879. Harn; 28th Rep. N. Y. State Mus. Nat. Hist. (ed. 2), p. 189.

1881. W. and Sp.; Revision Paleocr., Part II., p. 203 (Proceed. Acad. Nat. Sci, Phila., p. 377).

1881. Harn; 11th Ann. Rep. Indiana by Collet, p. 269.

1889. S.A. Minter; North Amer. Geol. and Paleont., p. 258.
Syn. Marsupiocrinus (not Phillips) Haut; 1848, Geol. 4th Distr. New York, p. 114.
Syn. Lhodocrinus (not Miller) Hat, 1863; Trans. Albany Inst., p. 198.

Calyx depressed-globose, more or less flattened to the middle of the
radials; symmetry almost perfectly pentamerous; plates heavy, their surfaces
smooth or finely granular; ventral disk not rising above the dorsal cup; arm
openings directed upwards, placed at the upper margin of the disk. Infra-
basals five, very small, abruptly and deeply depressed and concealed by the
column. Basals five, of uniform size, either all hexagonal and supporting
upon the truncate upper face the first interradial plate; or quite frequently
one or more of them hexagonal, and angular at the top. Costals two; large.
Two of the distichals enclosed in the calyx. Arms two to the ray, rising in
a straight line with the sides of the calyx; simple, strong, biserial, two of the
interlocking plates frequently in the calyx. Interbrachials four, in three
rows: 1, 2, 1. Anal side generally not distinct, but exceptionally it has
a special anal plate in the second row. Disk flat, somewhat depressed in the
interradial regions ; composed of a great number of slightly convex, delicate
pieces, and well defined orals. Anus subcentral, probably at the end of a
small tube.

Column of less than medium size, round; axial canal small.

Inistribution.— Upper Silurian, America and Europe.

Type of the genus: Lyriocrinus dactylus Hall. |

ftemarks. — The name Lyriocrinus was proposed for a species from the
Niagara group of Lockport, which had been described under Marsupiocrinus,

262 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

and was supposed to have but one ring of plates beneath the radials.
Another species, clearly of the same genus, was afterwards referred by Hall
to Lhodocrinus. In the construction of the calyx Lyriocrinus approaches
fiyprdocrinus, which, however, differs very essentially in the arm structure.
S. A. Miller’s Lyriocrinus sculptus, which in the Revision, Part II., we placed
provisionally under Archeocrinus, belongs to Déabolocrinus, and is identical
with D. vesperalis White.

In this genus we have a good illustration of the exceptional variation
from the characteristics of a group, which may be met with among individ-
uals belonging to it. In JZ. dactylus the first interradials often touch the
basals only at the anal side, while in L. melissa, they rest upon the basals at
all five sides. Again, in the former species there is generally an anal plate
between the interradials of the second row, while in JL. melissa that plate is
scarcely ever represented. Departures of this kind within a genus in respect
to characters which have always been regarded as of the utmost significance
for distinguishing families and genera show how idle it is to expect absolute
accuracy in the separation even of very important groups.

Lyriocrinus dactylus Haut.

Plate XI. Figs. da, b, ¢.

1843. Marsupiocrinus dactylus — Hat; Geol. Rep. 4th Distr. N. Y., p. 1138.
1852. Lyriocrinus dactylus— Hatt; Paleont. N. Y., Vol. IL., p. 197, Plate 44, Figs. la-g.
1881. Lyriocrinus dactylus— W.and Sr.; Revision Paleocr., Part IL, p. 205.

Calyx semi-globose; basal regions flattened, the centre abruptly de-
pressed for the reception of the column. Surface of plates smooth or finely
corrugated. Infrabasals very small, restricted to the bottom of the colum-
nar concavity. Basals large, four of them angular above, that of the anal
side truncate. Radials wider than high, larger than the costals, slightly
touching each other laterally except on the anal side. Arms ten, simple;
heavy at their bases, tapering upwards to one half their former size. They
are composed from the calyx up of two series of alternate plates with parallel
transverse faces, and have a shallow groove along the median line; their two
proximal plates incorporated into the calyx. Interbrachials: 1, 2,1; those
of the first and second rows large ; the lower one almost touching the basals ;
the upper one smaller and somewhat. inflected at the upper end, resting
between the lower arm plates. Another small plate is placed between the
distichals so that the arms are separated at one side by an interbrachial, and

RHODOCRINID.A. 263

at the other by an interdistichal. The first plate of the anal side, which
touches the basals, is larger, and is generally followed by three plates in the
second row. Column round; composed near the calyx of moderately high,
thicker, and thinner joints.

Horizon and Locahty. — Niagara group ; Lockport, N. Y.

Types in the American Museum of Natural History at New York.

Lyriocrinus melissa (Hatt).
Plate XI. Figs. 4a, 6, ¢, d, e, f.

1863. Rhodocrinus melissa — Hatt; Trans. Albany Inst., p. 198 (Abstr., p. 4).

1879. Rhodocrinus (Lyriocrinus) melissa — Hatt; 28th Rep. N. Y. State Mus. Nat. Hist. (Mus. edit.), p.
139, Plate 15, Figs. 18-27.

1881. Lyriocrinus melissa — W. and Sp. ; Revision Paleocr. Part IT., p. 205.

Calyx depressed, nearly twice as wide as high, distinctly flattened to the
top of the radials, then curving rapidly upwards until the sides of the upper
part are at right angles to the truncated lower part. Basal portions forming
a deep pit, which is surrounded by a pentangular rim, interradially arranged,
and having a triangular node at each angle. Surface of plates flat, smooth
or finely corrugated. |

Infrabasals very small, concealed by the column. Basals elongate, gener-
ally truncated at the upper face, the lower half of the plates curved inward,
forming the sides of the concavity, the upper half horizontal. Radials large,
wider than high. Both costals hexagonal, the axillary one smaller, its upper
angle truncated, supporting a small interdistichal; the sloping faces support
2X2 large distichals, which are followed by free arm plates of the same
order. Arms ten, equidistant; they are stout, long, tapering, and composed
of short pentagonal pieces ; their pinnules long and closely arranged. Inter-
brachials: 1, 2, 1, 1; the first as large or larger than the radials, resting
against the truncate upper faces of the basals. Anal side generally not dis-
tinct; but it has exceptionally a small additional plate in the second row.
Ventral disk almost flat, barely rising above the dorsal cup. Interambu-
lacral spaces slightly depressed ; orals well developed, twice as large as any
of the other disk plates, and more convex. Anus subcentral, very wide, and
apparently connected with a tube. Column uniformly cylindrical, the edges
of the nodal joints marked by a continuous row of small nodes.

Horizon and Locality. — Niagara group ; Waldron and Hartsville, Ind.

Types in the American Museum of Natural History, New York.

MELOCRINID.A® (Ropmmr) 1855.

Monocycuic. LowsEr BRACHIALS, WITH WELL DEFINED INTERBRACHIALS BETWEEN THEM,
FORMING A PART OF THE DORSAL CUP. RADIALS IN CONTACT ALL AROUND.

Analysis of the Genera.
I.

THE SYMMETRY OF THE DORSAL CUP DISTURBED BY ONE OR MORE
PENG AMS PMA Sasori: Siete sie oat Aging ey aes are ease gl ghee a
A. BASALS FIVE; COSTALS TWO.
a. First costal hexagonal.

Arms uniserial ; interbrachials and interdistichals numer-
ous. Ventral disk composed of very small, irregular
plates. “Basalssmal wo. 4 eo ee

Arms biserial, basals very large, otherwise resembling
CL URC OCHS tras natal ney Tales IY gn Ree

b. First costal quadrangular.
Arms uniserial; interbrachials few; ventral disk com-
PAPOSE ALO lange PIAbEG ty, cok Aeack on Vee eee ete wee
B. BASALS FOUR; COSTALS TWO.
a. Furst costal hexagonal.

Arms uniserial, arranged in groups; simple or bifurcat-
ing, distichals two to four, calyx of moderate size . .

Arms long, branching often; palmars and arm joints
very short, deeply interlocking. Distichals five and
upwards. Calyx very large; lower palmars partly in-
cluded in dorsal cup, interbrachials very numerous.

The rays extended into five tubular trunks, from which
biserial arms are given off from the outer sides all the
WiclyeU Osu MeN GUI Sra te=cuiG ee ae one wae oss: a ae

C. BASALS THREE; COSTALS TWO.

Arms biserial, simple from their origin; interbrachials

few, an anal plate interposed within the first range .

1

SYMMETRY OF DORSAL CUP UNDISTURBED BY ANAL PLATES... .
A. BASALS FOUR; COSTALS TWO.
a. Arms biserial.
Arms simple; arranged equilaterally around the calyx;

arse KCRO@ OMEGA ALN RS on ae les ee oe ge oe
Arms dichotomous; basal cup inverted; interbrachials
CTT OR aeesetah co Wika caer ae Ce ne oo eerie ah ges

B. BASALS THREE, SMALL; COSTALS TWO, THE FIRST QUADRANGULAR.
a. Arms simple.

MELOCRINITES.

Glyptocrinus.

Periglyptocrinus.

Stelidiocrinus.

Mariacrinus.

Scyphocrinus.
Melocrinus.

Macrostylocrinus.

a

DoLATOCRINITES.

Technocrinus.

Corymbocrinus,

MELOCRINID2. , 265

Arms biserial. Dorsal cup subturbinate . . . Patelliocrinus.*
Arms uniserial; dorsal cup depressed; interbrachials
few, lOnelomaimally -arkaMeeden © a. 7. ss e8 een ee Allocrinus.

C. BASALS LARGE, PROBABLY THREE, ANCHYLOSED.

a. Costals two, the first quadrangular.

Interbrachials few.
Dorsal cup subcylindrical; basals and radials very large,
distichals small; arms unknown . . Centrocrinus.

Calyx depressed-subglobose; basals small, interbrachials
few, the first extremely large. Arms biserial and gen-
erally branching. Slit-like respiratory pores at the

sides of the ambulacral-openings <4 429, 9. ss Dolatocrinus.

b. Costals one; pentangular.
Otherwise resembling Dolatocrinus . .. .. .. Stereocrinus.
Interbrachials numerous, basals forming an inverted cup Hadrocrinus.

Geological and Geographical Distribution.
Number of known species.

(Open figures indicate American; those marked ( ), European.)

ForRMATION. MELOCRINID.
Melocrinites. Dolatocrinites.
S (ob) : a n
2 a: cies Bo ees
a) : ag n Ors! i BD Ss; = = 2 z f
OS American. KS eB | 8 =e 2 ai|¢i|s E 5 E a E =I Beles
Boe |e) BIS (BPS |e] ee |e] 8 | 2 ee lee lee |e
a) 2 > S) 5) fo) °c wD fe) & iS) = = S 5 3)
a oF £/s | s | a S) fe) q Se H Qa Sa Sp cs
= | © = ® S) 3 | 4 eS 2 8
Gee eo es real tra Nee eal ee
Hamilton. Up. Devon. 3 (9) 8 2
@ | Up. Helderberg. | Eifel. 1(7) 8 9
a
a ae Eras |-aenee
is “
Q | Oriskany. 2
Low. Helderberg. | Grauwacke. 2 2 (3)
: eae sa A | DRS | =
= Wenlock.
MQ | Niagara. Bohemia. (3) |3(1)) (1) [5 (4)| 6 (6) | (7) | 2
S. Gotland.
aie: 22 ees
5 | Hudson River. 4
a) Sree es. | er ree eg a | See erence eae Be
: Trent 3 2 1
3 | Trenton.
: 54 1 5 11
Total species 95 } 7 3 1 6 || 2 | (6) | (7)} 2
? (1) - (3) | (1) | ™ [(e8) eet as a fe [ac

* Excluding P. fulminatus and P. duplicatus, which probably belong to Mariacrinus, and P. chiastodac-
tylus and P. pinnulatus, which are young specimens.
34

266 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

femarks.— The Melocrinide and Eucalyptocrinide are the only mono-
cyclic families of the Camerata which have a pentagonal base, and in which
the radials are in contact all around. The latter, however, depart from the
Melocrinidz so widely in their ventral structure that there is no need of
further comparison. The Melocrinide in many respects also seem closely
related to the Actinocrinids, which followed them in time. Indeed the

Fig. 12. Melocrinus. Fig. 13. Stereocrinus.

(For the explanation of the letters, see Fig. 11.)

superficial resemblance between the two families is often quite marked, but
a Melocrinoid is always readily distinguished from an Actinocrinoid by the
absence of an anal plate between the radials, and the consequent form of its
base, which is pentagonal. The Melocrinide are among the earliest known
forms of the Camerata, being already found to the extent of six species in
the Trenton group, contemporaneously with the earliest Rhodocrinide and
Reteocrinidss. They increased in number in the Upper Silurian, but became
extinct before the close of the Devonian, before the appearance of the Actino-
crinidze, so far as existing collections show. The family includes fifteen gen-
era, of which ninety-five species are known; fifty-four from America, and
forty-one from Europe.

Some of the genera referred to this family have a perfectly pentamerous
dorsal cup, the posterior interradius being identical with the other four; but
in others there are one or more anal plates interposed between the inter-
brachials, by which the pentamerous symmetry is disturbed. If this differ-
ence were well marked and constant, it would afford a basis for separation,
founded on the more or less complete absence of anal structures from the
dorsal cup; but this being not the case, we arranged the genera only into

MELOCRINID ©. NOTE

subdivisions with reference to it, calling those in which some trace of anal
plates is found Melocrinites, and those in which they are completely absent
in the cup Dolatocrinites. We find it impossible to make these divisions
families, because they seem very intimately related in other respects, and
shade into each other too closely, —both forms being possibly represented
in species of the same genus. This is probably the case in Hadrocrinus ;
while in Allocrinus the first interbrachial of the posterior side is somewhat
larger than the corresponding plate of the other sides. |

The name Melocrinids was introduced by Roemer.* It was applied by
him, and afterwards by Angelin,7 Zittel,t and 5. A. Miller,§ exclusively to
genera with four basals, or those that were supposed to have four. Glypto-
crinus, with five basals, although closely allied to Mariacrinus and Melocrinus,
was referred by Zittel, and $. A. Miller, who substantially adopted Zittel’s
classification, to the Glyptocrinidz under which they included a variety of
genera, both monocyclic and dicyclic. In the classification of 1890, Miller ||
refers to the Glyptocrinidse Cupulocrinus, Glyptocrinus, Pycnocrinus, Schizo-
ermus, and Siphonocrinus — the first an Ichthyocrinoid ; Siphonocrinus — a
Thysanocrinoid —and both of these last dicyclic. This is the more curious
because Miller is the author of Siphonocrinus, which he described as having
three infrabasals ; while he emphatically denied the presence of infrabasals
in Glyptocrimus ; and yet in establishing the families of the Crinoidea
made the “ presence or absence of ‘ subradials’”’ next in importance “ to the
number of basals,” upon which his classification is principally based.

I. MELOCRINITES.

SYMMETRY OF THE DORSAL CUP DISTURBED BY ONE OR MORE ANAL PLATES.

GLYPTOCRINUS Hazz.

1847. Hatz; Paleont. New York, Vol. I., p. 280.

1854. McCoy; Synops. Brit. Paleeoz. Foss., p. 56.

1856. Brurines; Canad. Naturalist and Geologist, No. 1., p. 49.
1857. Brutrnes; Geol. Surv. Canada of 1853 to 1856, p. 256.
1859. Brtuines; ibid., Decade IV, p. 55. :

1873. Muzx; Geol. Surv. Ohio, Paleont., Vol. I., p. 80.

1874. 5S. A. Mitter; Cincin. Quart. Journ. Sci., p. 348.

1879. ZrrreL; Handb. der Paleeont., Vol. I., p. 375.

* Lethea Geogn., 1855 (Ausg. 3), p. 228.

+ Iconogr. Crin. Suecie, p. 19.

+ Handb. der Paleontologie, Vol. I., pp. 868-375.

§ Amer. Paleeoz. Fossils (second edit.), p. 276. ee fs

|| American Geologist, Vol. IV., pp. 275 to 286, and pp. 340 to 357.

268 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

1881. W. and Sp.; Revision Paleocr., Part IT., p. 185 (Proceed. Acad. Nat. Sci. Phila., p. 359).
1883. W.and Sp.; Amer. Journ. Sci., Vol. XXV., pp. 255 to 268. |
1883. S.A. Mituer; Amer. Journ. Sci., Vol. XXVI., pp. 105 to 118 ; and Cincin. Soc. Nat. Hist., Vol.,
VI., pp. 220 to 228.
1885. W. and Sp. ; Revision Paleocr., Part III., p. 102 (Proceed. Acad. Nat. Sci. Phila., p. 324).
1859. §S. A. Mitten; North Amer. Geol. and Paleont., p. 247.
Not Glyptocrinus D’OrBicNny, 1852; Cours élément. de Paléont., Vol. II., p. 142, nor Prodréme,

Noles, pete(
Not Glyptocrinus Hatt, 1863, Trans. Albany Inst., Vol. IV., p. 202; nor 28th Rep. N. Y. State
Mus., p. 182 = Mariacrinus.
Not Glyptocrinus Hatt, 1872; 24th Rep. N. Y. State Cab. Nat. Hist., p. 206 = Reteocrinus.
Not Glyptocrinus Haut, 1872; ibid., p. 207 = Ptychocrinus.
Not Glyptocrinus WutHERsy 3 Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 88 = Refeocrinus.
Not Glyptocrinus 8. A. MituER; ibid., Vol IV., p. 74 = Compsocrinus, nor p. 75 = Reteocrinus.
Not Glyptocrinus ETHERIDGE and Nicuotson, 1880, Silur. Foss. of Girvan Distr., p. 328.
Syn. Fossil Encrinite ANTHONY, 1838; Amer. Journ. Sci., Vol. XXXV., p. 405.
Syn. Icosidactylocrinites OwEN, 1843 (Catalogue name).
Syn. Pycnocrinus 8. A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 2381.
Calyx obconical or subglobose; plates thin, often highly ornamented; the
fixed brachials passing imperceptibly into arm plates, and the interbrachials
into disk plates; the arms rising vertically from the edge of the tegmen.

Basals five, of uniform size, forming a small cup. Radials and costals of
nearly equal size; the second costal hexagonal. Distichals varying in num-

ber, there being but two in species in which palmars take part in the calyx ;
but when the second bifurcation takes place in the free arms, they are quite
numerous, frequently six to eight or more in the calyx, followed by several
others in the free arms. When this is the case, the second distichal gives
off a large pinnule; while in the other the proximal pinnule is developed
into an arm. Arms rarely branching beyond the second bifurcation, rising
vertically from the calyx; they are long, slender, rounded on the back,
and composed of a single series of short, slightly wedge-shaped pieces,
which do not interlock. Pinnules slender, closely arranged; the proximal
ones the stoutest, and frequently incorporated into the calyx.
Interbrachials definitely arranged; the first large, resting upon the slop-
ing upper faces of the radials; there being two plates in the second row, and
two, sometimes three, in the higher ones. The anal side widest, having
generally three plates in the second and all succeeding rows. Interdistichal
spaces large, composed of numerous small plates; some species also have
interpalmars. Ventral disk depressed-hemispherical, very slightly extend-
ing above the level of the arm bases; the ambulacra subtegminal, except
near the periphery, where some of the small covering pieces are exposed,
but the course of the ambulacra is indicated by surface ridges. Plates
of the disk very minute and irregularly arranged, decreasing in size toward

; . MELOCRINID &. 269

the arms. The arrangement of the larger plates at the summit is also irreg-
ular, being unlike that of orals, which probably are not represented. Anal
opening excentric, at the summit of a small protuberance. Column round;
axial canal large, pentalobate, the lobes directed interradially, except in one
species in which the stem is pentangular and the central canal radially
disposed.

Distribution. — Glyptocrinus, as now amended, is confined to the Trenton
and Hudson River groups, and probably is restricted to America.

Type of the genus. — Glyptocrinus decadactylus.

Kemarks.—-The genus agrees in the uniserial arms and its general

structure with Muariacrinus, but that has four basals instead of five. It

resembles Compsocrinus, which has also four basals, but an anal plate in
line with the radials, which throws it into the Batocrinide. :

The European species referred to Giyptocrinus, with the possible excep-
tion of G. basils, belong to other genera. The specimens described under
the name Glyptocrinus globularis by Nicholson and Etheridge probably belong
to Archeocrmus. They evidently had infrabasals, for the interradials rest
upon the basals, and they probably had biserial arms.

The following species either are synonyms, undeterminable, or are
removed from Glyptocrinus to other genera :

Glyptocrinus parvus Haun, referred to. . . . . ee ivchoonmus:
‘ angularis MILLER and DyErR, synonym of - + « , Ptychocrinus parvus,
a gracilis WETHERBY, Synonymof .... . . . Ptychocrinus parvus.
oS flarrist Miuurr, referred to. . . . . . . . . Compsocrinus.
es Carleyi Haut, 4 iE eee oe omens
miamiensis MILLER, “ Sah a ney ICOM SOCRiiis:
be Baeri MEEK, os = OES wcelo ah Ml De Nenoeruntuss
5 expansus Puinuirs, “ - fal 6 wom se 5 agen oennniis:
a armosus McCuHEsnry, “ ib & gue Oe eh os SU MOMOCRII IS:
e siphonatus Haun, synonymof . ... . . . . Siphonocrinus armosus.
Us NOOUIS ETAT G sTCLCTLEC: (0). <t- <a. 2s ae ty ae ee oe Siphonocrinus.
a cognatus MILLER, synomymof. . .. . . . . Reteocrinus Onealli.
‘ Or Neally (Neal) Wisin, 8° a a a ereoeraias
66 lacunosus BILLINGS, cs Ss ME en Se i ACh oer ims:
it subnodosus WaucotT, “ - 23. Fe. = Rap hanocranus:
Ua sculptus MILLER, ag - os . « «is « shaphanocrinus.
te argutus WALCOTT, ei = Sie ee) nee a SSPE OCT INS
< priscus BILLINGS, eg =) ey ee = es el LOGnI MIS.

Jimbriatus Seinen inacemianan

libanus SAFForD, not defined.

plumosus Haut, detached column and arms.
quinquepartitus Brnuines, detached column and arms.
Pattersoni MituEr, adem

bo
I
=

THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Glyptocrinus decadactylus Hatt.

Plate XX. Figs. 4a-e and Plate XXI. Figs. 4a, 6b.

1847. Hat; Paleont. N. Y., Vol. I, p. 281, Plate 77, Figs. la-fand Plate 78, Figs. la—u.

1873. Merxrx; Palzont. Ohio, Vol. I., p. 30, Plate 2, Figs. 5a, 0.

1879. Zittel; Handb.d. Paleont., Vol. I., p. 375, Fig. 262.

188]. W. and Sp.; Revision Paleocr., Part II., p. 188 (Proceed. Acad. Nat. Sci. Phila., p. 362).

1883. S.A. Mrzter; Journ. Cincin. Soc. Nat. Hist., Vol. VL., p. 220, Plate 11, Fig. 1.

Calyx obconical, somewhat higher than wide; the interradial and inter-
distichal spaces a little flattened, giving a cross-section pentagonal through
the costals and decagonal through the distichals. Surface beautifully orna-
mented with radiating angular ridges; those following the rays to the arms
a little the largest and most prominent. Other ridges pass sideways from
the centre of the plates, meeting with similar ridges from the interbrachials,
which divide the surface into numerous triangular impressed areas.

Basals small, their width at the top greater than the height. Radials
heptagonal, larger than the basals, and as wide as long. First costals a little
smaller than the radials, and hexagonal; the second as large as the first, but
angular above. Distichals two, comparatively large. Arms twenty, simple,
rather stout, cylindrical. The four lower plates, which in large specimens
are incorporated into the calyx, are elongate, but decrease in length upward ;
their upper and lower faces being parallel, the succeeding free plates slightly
cuneate. Pinnules long, closely arranged; the proximal ones given off from
the third palmars, there being none from the distichals. Interbrachials
numerous, gradually decreasing in size; arranged in ten to twelve ranges:
1, 2, 2, 2, e¢e., at the regular sides, sometimes with three plates in the second
row. Anal side having three plates in the second and succeeding rows; the
plates of the median series longitudinally arranged, and covered by a ver-
tical ridge similar to the ridges along the rays. Interdistichals in four to five
rows, the interpalmars in three; the former arranged: 1, 2, 2, 2, 2; the
latter placed in a single longitudinal row. Ventral disk slightly convex,
composed of irregular pieces with a small prominence in the centre. The
plates are small, and gradually decrease in size outward, those along the
margin being quite minute, and enclose some of the “ Saumpldttchen.” The
latter, which are also frequently preserved upon the arms and pinnules, con-
sist of two very small irregular rows of pieces. Anus subcentral, at the
upper end of a protuberance. Column round, of moderate size, the nodal
joints a little the widest; axial canal rather large and pentalobate.

MELOCRINID. DF

Horizon and Locality.— Hudson River group; Cincinnati, O.; Waynes-
ville, O., and Maysville, Ky.

Remarks. -—It has been supposed by several writers that G. decadactylus
had rudimentary infrabasals, but this is not the case. In a fine specimen
from which every vestige of the stem was removed, we could follow the
interbasal sutures to the axial canal, and found the latter to be interradial
and not radial, the part which had been supposed to represent the intfra-

basals being the upper stem joint.

Glyptocrinus Dyeri Mezex.

Plate XX. Figs. la, b,c; and Plate X XI. Figs. 5a, b, ¢, and Fig. 6.

1872. Megx; Proceed. Acad. Nat. Sci. Phila., p. 314.
1873. Merzx; Geol. Rep. Ohio, Paleont., Vol. I., p. 32, Plate 2, Figs. 2a, 6 (not 2c).
1881. W.and Sp.; Revision Paleocr.; Part II., p. 188.
1883. S. A. Minter; Journ. Cincin. Soc. Nat. Hist., p. 222.
Syn. Glyptocrinus Dyeri var. subglobosus —MexrK; 1872, Proceed. Acad. Nat. Sci. Phila., p. 340;
also Geol. Rep. Ohio, Paleont., Vol. I., p. 34, Plate 2, Fig. 2c.
Syn. Glyptocrinus subglobosus — W. and Sr.; 1881, Revision Paleocr., Part II., p. 189.

Syn. Glyptocrinus Richardsoni — WETHERBY ; 1880, Journ. Cincin. Soc. Nat. Hist., Vol. I., p. 245,

Plate 16, Figs. 1 and la.
Syn. Reteocrinus Richardsoni — W. and Sr.; Revision Paleocer., Part IT., p. 193.

Of the type of Glyptocrinus decadactylus, but the calyx globose instead of
obconical. It has a similar ornamentation, but the ridges are less angular,
being rounded, and those following the radial and anal plates are more
prominent; the arms are thinner, and the second bifurcation takes place in
the arms.

Basals small, much wider than long, with a sharp, almost circular rim
around the bottom, which extends slightly beyond the column. Radials and
costals a little wider than long, the latter somewhat the smallest. Distichals
nine to sixteen or more, their number varying among the rays, the five to
eight lower ones forming part of the calyx, the others being arm plates.
The two lower distichals nearly as large as the upper costals. The succeed-
ing plates decrease rapidly in size upwards. Their second plate has the
form of an axillary, giving off to the outer side of the ray a large pinnule ;
the third is quadrangular and bears no pinnule; the fourth plate bears the
second pinnule at the inner side of the ray, above which every plate is
pinnule-bearing. In large specimens, as much as six pinnules are incorpo-
rated into the calyx, and these are not only larger than the succeeding ones,
but are placed farther apart. The apposed faces of the distichals, and a ppar-

272 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

ently of all arm plates, are covered with well marked radiating striae and
grooves. The arms in their free state branch but once; they are rather thin,
especially at the upper ends, and composed of short, somewhat cuneate
pieces. Interradial spaces slightly impressed between the costals, and dis-
tinctly grooved between the distichals. First interbrachials about as large
as the radials; the plates of the second row a little smaller, supporting
a fourth plate between their upper sloping faces, and two plates in the next
two rows, followed by numerous small pieces, which enclose the fixed pin-
nules. The anal area is a little wider, having three plates in the second and
all succeeding rows up to the first pinnule; the middle series being marked
by a rather conspicuous ridge. Interdistichal spaces elongate, their median
portions deeply grooved ; the first plate large, followed by two plates in the
second row, and a number of small pieces above. Construction of the ventral
disk, and position of the anus unknown. Column round, — not indistinctly
pentangular as stated by Meek; the nodal joints somewhat larger; the axial
canal pentalobate, and moderately large.

florizon and Locality. — Hudson River group; at Cincinnati, Lebanon and
Waynesville, Ohio, and also found at Richmond, Ind.

Lype in the Museum of Comparative Zoblogy, Cambridge.

Kemarks. — This species is readily distinguished from G. decadactylus, its
nearest ally, by the uninterrupted series of anal plates. It is quite remark-
able for its large number of incorporated pinnules, of which the proximal
ones have almost the proportions of armlets. Meek’s G. Dyeri, var. globosus,
which we thought to be a good-species, judging from the figures, can hardly
rank even as a variety. We have examined the type in the Museum of
Comparative Zodlogy, and find it to have all the characteristics of G. Dyewi.
Wetherby’s G. Richardson’ also, which we once regarded as a Reteocrinus, is

based upon a somewhat aberrant specimen of this species.

(?) Glyptocrinus Shafferi Miturr.
TANGO NON PIGS 30 es f

1875. Glyptocrinus Shafferi —8. A. Miniwr; Cincin. Quarterly Journ. Sci., Vol. II., p. 277; and 1880,
Journ. Cincin. Soc. Nat. Hist., Vol. IIT., p. 238, Plate 7, Figs. 2a, 4, and 8a, 4, c.

1881. Glyptocrinus Shafferi — W. and Sr.; Revision Paleocr., Part II., p. 189.

1883. Pycnocrinus Shaffert —S. A. Mit1ur; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 231, and North
Amer. Geol. and Paleeont., p. 276.

There is but little doubt that the small specimens which S. A. Miller
described as Glyptocrinus Shaffert, and G. Shaffert, var. germanus, and for

MELOCRINID.&. | 2

which he afterwards proposed the genus Pyenocrinus, are young examples of
Glyptocrinus Dyeri. ‘The specimens have variously from nine to twelve dis-
tichals, but in place of having six to eight of them incorporated into the’
calyx, only one or two are calyx plates, the others being free. That the
specimens are comparatively smaller, the column stouter, the basals propor-
tionately larger, the interbrachials and interdistichals less numerous, the
arm joints higher, the pinnules stronger and placed farther apart, all indicate
a less mature stage of individual growth, a phase through which every
Glyptocrmus must naturally have passed.

Miller defines Pycnocrinus as follows: “ Calyx cup-shaped. Column
round. Basals five, small, pentagonal. Primary radials 3 x 5. See-
ondary radials none. Regular interradials three. Arms ten, but some-
times dividing after becoming free. Pinnules dense and strong.” This
description would apply equally well to any young Glyptocrinus. It must be
remarked, however, that both of Miller’s types have small interdistichals,
which he overlooked. The presence of these plates proves conclusively that
at least one of the distichals takes part in the calyx, and that “secondary
radials” are not unrepresented in those specimens, as Miller supposed.

Horizon and Locality. — Found associated with the two preceding species
at Cincinnati and other places.

Type in the collection of 8. A. Miller.

Glyptocrinus ramulosus Briures.

Plate XX. Figs. da, b.

1856. 4H. Brutines; Canadian Naturalist and Geologist, No. 1, p. 54; also Geol. Surv. of Canada (Rep. of
Progress), 1857, p. 258, and 1859, Decade IV., p. 57, Plate a, Fig. 2a and Plate 8, Fig. 1

1881. W. and Sp.; Revision Paleocr., Part II., p. 189.

1883. §S. A. Mitter; Journ. Cincin. S08 Nat. Hist., p. 224.

A large species. Dorsal cup obconical, somewhat rounded at the base.
Costals and distichals remarkably uniform in size; also the palmars propor-
tionally large. Plates almost flat and without any markings, except a con-
spicuous, obtusely angular ridge passing up Re rays, occupying nearly one
half their width.

Basals small, only the upper angles visible from a side view. Radials
somewhat larger than the costals, as long as wide. Distichals six, exception-
‘ally seven; the proximal one as long as the costals, but a little narrower;

the succeeding ones smaller. There are fixed pinnules from the second,
35

274 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

fourth and fifth plates (none from the third), which are long, but not as
conspicuous as in the preceding species, and they grow more obscure with
age. All brachials of the third order are free; the two or three lower ones
are longer and have parallel upper and lower faces; the others being short
and cuneiform. The arms, which branch once, are long, very slender,
rounded on the back, and provided with rather long pinnules. Interbrachial
plates large, to the fifth row nearly of equal size, and as large as the second
distichals ; arranged : 1, 2, 2, 2, 2. From the sixth row, where the pinnules
come in contact with the interbrachials, the arrangement is less regular, and
the plates gradually grow smaller. There seems to be no anal ridge, but the
posterior interradius has three plates in the third row, and frequently in the
second. The interdistichal spaces are remarkable for their great length, and
the large size of the plates; they are arranged: 1, 1, 2, 2, 3. Construction
of ventral disk, and position of anal opening unknown. Column round,
composed of short, sharply edged joints.

Horizon and Locality. — Trenton limestone; Ottawa, Canada.

Z7ypes in the Canada Survey Museum.

Glyptocrinus ornatus Biturves.
Plate XX. Figs. 6a, b.

1857. Brrztines; Geol. Surv. of Canada (Rep. of Pages p- 260; also 1859, ibid., Decade IV., p. 60,
Plate 9, Figs. 2a, d.

1881. W. and Sp.; Revision Paleocr., Part II., p. 189.

1883. 8S, A. Mizuer; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 225.

Of the type of Glyptocrinus Dyeri, but readily distinguished by its orna-
mentation, the smaller number of interbrachial and anal plates, and by
having ten arms instead of twenty. Calyx globose, the plates delicate, orna-
mented with five or six rather conspicuous, finely striated ridges, radiating
from the centre of the plates. The ridges passing up the radial and anal
plates are more prominent and broader than the others; those from the
interbrachials, which are not confluent with the ridges of adjoining plates,
forming a well defined star upon each plate.

Base short, with a projecting rim and a shallow depression at the bottom.
Radials and costals a little wider than long, the radials one third the largest.
Four of the distichals generally take part in the calyx, of which the two
proximal ones are nearly as large as the upper costal, the second pinnule-
bearing ; the two succeeding ones are much smaller, but yet twice as large

MELOCRINID &. 275
as the free brachials. Arms ten, slender, not bifurcating ; composed of quad-
rangular, moderately high joints with long pinnules. Interbrachials: 1, 2, 2,
2, decreasing in size upwards. The anal interradius considerably wider:
1, 3, 3, efc.; the middle series longitudinally arranged, and marked by a
conspicuous ridge. Interdistichals: 1, 2, etc. Construction of ventral disk
and anus unknown. Column obscurely pentagonal to judge from the top
joint; the axial canal of medium size.*

Horizon and Locality. — Trenton limestone; Ottawa, Canada.
Types in the Canada Survey Museum at Ottawa.

Glyptocrinus marginatus Bizzi1ves.
Plate XX, Hig. 2.

1856. Glyptocrinus marginatus — Vi. Bruuines; Geol. Surv. Canada (Rep. of Progress), p- 260; also 1859,
Decade IV., p. 59, Plate 9, Fig. la.

1881. <Archeocrinus marginatus — W. and Sp.; Revision Paleocr., Part II., p. 190.

1859. <Archeocrinus marginatus —S. A. Mitinr; N. Amer. Geol. and Paleont., p. 225.

A large and well marked species. Exact form of calyx undeterminable
— the only specimen being in a crushed condition — but probably subglo-
bose. Plates evenly margined by a strong elevated border crossing the
radial ridges, their middle portions smooth and very thin; the inner floor of
the plates marked by slender conspicuous tubercles. Radial ridges not very
prominent, wide and flattened.

Basals small, projecting laterally. Radials and costals as long or a little
longer than wide; the former twice as large as the costals. Distichals about
seven; all, or nearly all, incorporated into the calyx, rapidly decreasing in
size; the proximal one as large as the costals, and of similar form; the upper
axillary, and succeeded by free arm plates. Arms delicate, composed near
the calyx of moderately long (nearly as long as wide), slightly cuneate
joints. There are apparently no fixed pinnules; the free pinnules long, stout
at the base, distinctly tapering. Interbrachials: 1, 2, 2, 1, 2, 8, 2, followed
by others; their five lower ones of nearly the same size as the radials. Anal
area considerably wider, and composed of a much greater number of plates
than in any other species of the genus. It contains a middle series of anal
plates, marked by an obscure ridge, and to both sides of this ridge there are
numerous interbrachials, arranged like those of the four regular sides, but

* It is doubtful if the detached column, which Billings found associated with the type specimen, belongs
to this species.

27/6 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the plates somewhat smaller. Nothing is known of the ventral disk, the
anal opening, and the upper portions of the arms. Column strong, round ;
composed of alternate thick and thin joints, all rounded along the edges, the
former twice as high as the latter, and somewhat wider. Axial canal large,
pentalobate. |

Horizon and Locality. — Trenton limestone ; City of Ottawa, Canada.

ftemarks,— This species has a superficial resemblance to certain species
of Archeocrinus, and in 1881 we referred it to that genus. But on examin-
ing the type specimen from the Canada Survey Museum we find it has no
infrabasals, and the angles of the axial canal are interradially disposed.

(?) Glyptocrinus Fornshelli 8. A. Miurer.
Plate XX. Fig. 8, and Plate XXI. Fig. 5.

1874. §. A. Mitier; Cincin. Quart. Journ. Sci., p. 348.
1881. W. and Sp.; Revision Paleocr., Part II., p. 188. |
1883. 8. A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 227; and North Amer. Geol. and Pale-

ont., p. 248.

Calyx elongate, obconical; dorsal cup almost twice as high as wide, its
sides convex. Plates delicate and beautifully ornamented, being traversed
by sets of from five to seven small ridges, a set directed to each side of
the plate, and each set continued upon adjoining plates. The ridges of the
same set are parallel, those of different sets meeting at an angle at the
middle of the plates, and being so arranged as to form numerous rhombs,
each containing two sets of included triangles. Upon the radials and costals
the median ridge is but slightly stronger than the others, but on approach-
ing the distichals it enlarges rapidly, and at the fifth plate it attains the
proportions of an arm.

Basals small, forming a short cup; the interbasal sutures deeply notched.
Radials and costals longer than wide, their upper and lower faces unusually
narrow ; the first costal somewhat longer than the radials, the second a little
smaller generally. Of the distichals, the ten to twelve lower plates take
part in the calyx; the three proximal ones being but third smaller than
the costals; the fourth is considerably shorter, and the succeeding ones
almost as short as the free brachials. Arms bifurcating (once or oftener),
long, very slender at their tips; constructed of moderately short, cuneate
pieces with stout and long pinnules. Interradial and interdistichal areas
elongate, and composed of an unusually large number of pieces; the former

MELOCRINID.Z. ae i

arranged in one of the specimens: 1, 2, 8, 3, 3, 3, 3, 3, 4,45 the latter:
1, 2, 3, 3, 3, ete. The anal side contains three plates in the second row, and
there are other extra plates above. Nothing is known of the ventral disk or
anal opening. Column sharply pentangular ; the nodal joints the longest, their
edges flattened (not convex); internodal joints short and angular in the
upper part of the stem, but gradually growing as large as the nodal ones;
axial canal wide and slightly pentalobate, the lobes disposed radially, in the
same direction as the outer angles of the stem.

Horizon and Locality.—- Upper part of the Hudson River group; at Mor-
‘row and Waynesville, O.

Types in the collection of Mr. F. L. Fornshell.

femarks, —It is with some hesitation that we place this species under
Glyptocrinus, It differs from all other species of the genus in the pentangular
stem, and the radial position of its axial canal, a feature in which it is at
variance with all other known monocyclic Palxocrinoids. That it actually
has no infrabasals, we ascertained from a fragmentary specimen by exposing
the inner floor of the basal cup. It has in the centre a large pentangular
open space, whose angles are pointed to the interbasal: sutures, taking the
same direction as the angles of the stem. A somewhat similar departure
from the rule is claimed to exist in the recent genus Pentacrinus, in which,
however, stem and canal are dnterradial.

PERIGLYPTOCRINUS W. and Sv. (nov. gen).

Closely allied to Glyptocrinus, but having larger basals and well developed
hiserial arms; the arms of Gilyptocrinus being described by all writers as uni-
serial. The only two species known to us are our new species Periglypto-
crus Bullingst, which we make the type of that genus, and P. priscus, which
was described by E. Billings as a Glyptocrinus. Fragments of a third species
are found in Alexander County, Ills.

Distribution. — Black River shale, and Trenton limestone of Canada.

Periglyptocrinus Billingsi W. and Sp. (nov. Sp.).
Plate XXI. Figs. 1a, 0.

A beautiful and highly ornamented species. Dorsal cup elongate-obcon-
ical, higher than wide, somewhat depressed at the interradial and interdis-

278 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

tichal spaces. The plates marked by rounded ridges, one to each side of the
plates; those upon the radials and fixed brachials much wider and more
prominent. The ridges tapering to the margins of the plates, so as to form
bead-like elevations along the rays, and a well defined star upon each inter-
brachial. |

Basals large, forming an elongate cup, which is deeply grooved at the
interbasal sutures, and the sides of the plates are bordered by conspicuous
ridges, which are prolonged to the upper part of the radials. Radials and
costals large, longer than wide; the radials larger than the costals. Dis-
tichals two. Palmars free from the fourth plate. Arms twenty, simple,
long, slender, gradually tapering to their tips, and beyond the fourth or fifth
plate strictly biserial. The first pinnule is given off from the second pal-
mars, and all succeeding brachials are pinnule-bearing. Interbrachials: 1, 2,
2, 2, 2, etc.; the lower one considerably the larger. Interdistichals: 1, 1, 1;
interpalmars: 2 to 3. Anal interradius the widest, the lower plates some-
what larger than the corresponding plate of the four other sides. It con-
tains three plates in the second and all succeeding rows, the middle series
marked by a somewhat interrupted longitudinal ridge. Similar but shorter
ridges proceed from the first anal plate to adjacent radials. Construction of
ventral disk, and position of anus not known. Column slightly decreasing
in size downward; round; composed of rather long joints with convex
edges; the nodal joints considerably thickest. At three inches from the
calyx, each internode contains seven to eight joints, of which every second
or third is nearly as large as the nodal ones.

Horizon and Locality. — Trenton limestone, Ottawa, Canada.

Types in the Canada Survey Museum at Ottawa; collected by Mr. John
Stewart.

We take pleasure in dedicating this elegant species, the type of a new
genus, to our friend Mr. Walter R. Billings, the author of several important
papers on Crinoids, to whom we are indebted for many favors.

Periglyptocrinus priscus (BrLiNGs),
Plate XXII. Fig. 2.

1856. Glyptocrinus priscus — Ki. Brtrnes; Geol. Surv. Canada (Rep. of Progress), p. 287; also 1859, De-
cade IV. p. 56, Plate 7, Figs. la, 4, ¢.

1881. Glyptocrinus priscu’ —W. and Sp.; Revision Palwocr., Part IT., p. 189.

1883. Glyptocrinus priscus —8. A. Miter; Journ. Cincin. Soc. Nat. Hist., p. 225.

1883. (2) Archeocrinus priscus —W. and Spv.; Revision Paleoer., Part III., p. 301.

MELOCRINID &. 279

A small species. Dorsal cup obconical with slightly convex sides;
section across the costals sharply pentagonal, owing to the conspicuous radial
ridges, which pass from the arms down to the centre of the radials, where
they divide and are continued to the basals. The ridges, which are rounded,
grow narrower toward the middle of the plates, widening at their margins.
Surface, except along the ridges, covered with numerous small pustules
without definite arrangement.

Basals large, forming a pentagonal cup with a rim around the bottom.
Radials twice or nearly three times as large as the second costals; the first
costal larger than the second. Distichals free beyond the fourth plate; the
first and second considerably the larger; the second one pinnule-bearing,
and also the fourth (not the third), which is slightly wedge-shaped, and con-
siderably smaller than the preceding ones; from the fifth to the eighth, the
plates are decidedly cuneate, the higher ones interlocking. Arms 10, simple
throughout; thin, composed of two series of trigonal pieces. Interbrachials:
1, 2, 2, ee.; the plates large. Anal side slightly wider; the first plate
a little larger than the corresponding ones of the other sides; the succeed-
ing pieces comparatively smaller; there are three plates in the second row,
and in all the rows above. The plates of the median series are formed into
a conspicuous longitudinal ridge, which divides on the first anal plate, send-
ing a branch to the middle of adjacent radials. Nothing is known of the
structure of the ventral disk and anal opening, and nothing definitely of the
column.

Horizon and Locality. — Black River limestone; Renfrew Co., Canada.

Type in the Canada Survey Museum at Ottawa.

ftemarks.— The large columns which E. Billings figures from the Tren-.
ton group of Ottawa, and which he thought might be referable to @. priscus,
probably belong to a different species.

STELIDIOCRINUS Ancztin (Restricted by W. and Sp.).

1878. Anextin; Iconogr. Crinoid. Suec., p. 21.

1879. Zirten; Handb. der Paleont., Vol. I., p. 345.

1881. W. and Sp.; Revision Paleocr, Part II., p. 98 (Proceed. Acad. Nat. Sci. Phila., p. 272).
1835. W. and Sp.; ibid., Part ITL., p. 102 (Proceed. p. 324).

Calyx small, subturbinate, plates smooth; interradial areas depressed ;
radial plates elevated but not ridged; ventral disk composed of but few
plates.

280 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Basals five, forming an acute-angled pentagon. Radials large, wider
than long; lunate. Costals two; the first quadrangular; the second much
larger, almost as large as the radials. Distichals 2x10 in the calyx, the
others free arm plates. Arms ten, simple, uniserial, rather stout; pinnules
strong. Interbrachials: 1, 2, 1; the first very large, rising to the top of the
first costals. Anal area wider, containing three plates in the second and
third rows, and smaller ones above. Anus excentric, represented by a simple
opening, which faces laterally. Ventral disk low, the orals very large, occu-
pying in S. capitulum fully three fourths of the whole surface. Column

round. ;

Mistribution. — Witherto found only in the Upper Silurian of Gotland,
Sweden, but we now refer to this genus Walcott’s Glyptocrinus argutus from
the Trenton limestone of New York, with some doubt.

Remarks. — Angelin’s descriptions and figures are so confusing that no
uniform generic characters can be deduced therefrom, unless some are elimi-
nated, ‘Taking the first species S. capitulwm, Iconogr. Plate XVII. Figs.
o-og, and the first figures of his second species S. laevis, ibid., Plate XV.,
Fig. 20, we have the type indicated by the above descriptions; but Plate
XXVIIL., Figs. 7a, b, figured also as S. laevis, is clearly a Desnidocrinus, and
the specimen represented on Plate XXXII, Figs. 3 and 8a, is probably incor-
rectly figured, either as to the anal side or the arms. Plate ALXG, Mie 6,
figured as 8. ovalis, is a totally different thing, and probably belongs to the
Rhodocrinidw. Plate XXI., Figs. 6, 7, described by Angelin as Harmocrinus,
and considered by us (Revision, IL, p. 99) as belonging to Stelidiocrinus, has
very possibly a dicyclic base, and strongly resembles Thysanocrinus. We have
not the material to settle these questions, but by restricting the genus to the
above mentioned forms, we have something tangible. The genus, as thus
defined, ditfers widely from any other of this group, especially in the struc-
ture of the disk, which is quite remarkable. The quadrangular first costal
distinguishes it from the associated genera with five basals.

(?) Stelidiocrinus argutus (Waxcorn).

Plate XXIV. Fig. 6.

1883. Glyptocrinus argutus — Waucort; 35th Rep. N. Y. State Mus. Nat. Hist., Plate 17, Fig. 9.
1885. (2) Stelidiocrinus argutus —W. and Sr.; Revision Paleocr., Part II., p. 102.

Calyx small, somewhat pentangular; the interradial spaces depressed.
Basals five, rather large. Radials subquadrangular, the upper faces moder-

MELOCRINIDZ. 281

ately concave ; their upper corners but slightly truncated. First costals
quadrangular, not more than half the size of the radials, a little wider than
long, the lower face convex. Second costals nearly as large as the radials,
their upper faces forming an obtuse angle. Distichals one in the calyx.
Arms two to the ray; composed of rather stout quadrangular pieces. The
two or three proximal free plates about as long as wide, the others compara-
tively longer, and increasing in length upward. ‘The pinnules, which are very
stout, almost take the form of armlets; they are placed far apart, and their
joints, like those of the arms, grow longer upwards. Interbrachials three
preserved in the specimen, but having others above; the arrangement of the
plates at the anal side unknown. Column of medium size; the joints
rounded at their edges, and decreasing in height downward.

fforizon and Locality. Upper part of Trenton limestone; Trenton
Falls, N. Y.

Type in the Museum of Comparative Zotlogy, Cambridge.

ftemarks. — We refer this species with some doubt to Stelidiocrinus, which
it approaches in its general characters; but as nothing is known of the struc-
ture of its anal side, it may belong to a different genus, and perhaps to
the Dolatocrinites.

MARIACRINUS Hatt (emended W. and Sp.).

1859. Hau (in part); Paleont. N. Y., Vol. IIT., p. 104.

1881. W. and Sp.; Revision Paleoer., Part II., p. 114 (Proceed. Acad. Nat. Sci., Phila., p. 288).
1885. W. and Sp.; Revision Paleocr., Part III., p. 104 (Proceed. Acad. Nat. Sci., Phila., p. 326).
1889. S.A. Mituer; N. Amer. Geol. and Paleont., p. 259.

Calyx obconical, in general aspect resembling Glyptocrinus; interradial
and interdistichal spaces large and more or less depressed; the posterior
interradius distinguished by having three plates in the second row; the
plates of the rays marked by a strong longitudinal ridge.

Basals four, small, almost of uniform size. The one facing the anterior
side a little the largest and pentangular, the others irregularly quadrangular.
Radials and costals of similar size; costals two, the first hexagonal. Dis-
tichals two to four. The palmars, of which generally the proximal plate
only takes part in the calyx, support the arms. Arms composed of
cuneiform pieces, which either remain simple, or give off a few branches
to one side. Pinnules given off from opposite sides. Interbrachials rather

numerous; anal side a little wider, and containing additional plates. Ventral
36

282 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

disk flat; composed, so far as observed, of very minute, irregular pieces,
apparently without oral plates. Anus excentric, opening out directly through
the tegmen. Column round; axial canal of medium size, and obtusely pent-
angular, :

Distribution. — Upper Silurian of America, England, and Sweden.

Remarks. — Hall in proposing this genus made “ Mariacrinus”’ nobilissimus
the type ofa genus, which in all essential characters agrees with Melocrinus
Goldf., notably in the arm structure; the arms being given off from the
sides of tubular appendages. Among the species referred by Hall to Maria-
crmus were some with a very different arm structure, and in 1881 we recon-
structed the genus with Mariacrinus plumosus and M. Carleyi as types. The
genus, as we proposed it, includes only those species with four basals in
which the arms are given off directly from the calyx.

Zittel regards Mariacrinus, as typified by I. nobilissimus, as a synonym of
Ctenoerimus Bronn, in which we agree; but the latter genus, according to
Schultze, * is identical with Melocrinus. ,

Mariacrinus macropetalus Hall is probably a Corymbocrinus Angelin; Maria-
crinus stoloniferus Hall is described from fragmentary columns. Glyptocrinus
Hlarrisi 8. A. Miller, which we erroneously referred to Mariacrinus, not
knowing it had an anal plate between the radials, has been transferred to
Compsocrinus. Marvacrinus granulosus 8. A. Miller is too fragmentary for

identification, but certainly belongs to a very different group.

Mariacrinus Carleyi (Hatt).
Plate XXII. Figs. 2a, b, ¢.

1863. Glyptocrinus Carleyi— Haun; Trans. Albany Inst., Vol. IV., p. 203; also 28th Rep. N Y. State
Mus. Nat. Hist., 1875, p. 132, Plate 14, Figs. 7-10.

1881. Glyptocrinus Carleyi — Hawn; llth Ann. Geol. Rep. Indiana, p. 261, Plate 13, Figs. 7 to 11, and
Plate 15, Fig. 5.

1881. Mariacrinus Carleyi—W. and Sv.; Revision Paleocr. Part IT., p- 116.

Calyx obconical, higher than wide; the sides distinctly convex, section
across the costals sharply pentagonal, and across the distichals decagonal ;
the radials marked by very prominent rounded ridges; the interradial spaces
depressed. Narrower and more angular ridges pass out to the sides of the
radials, where they meet with others from the interbrachials, dividing the

suriace of the dorsal cup into numerous triangular depressed areas, which

* Monogr. Hchinod. Hifler Kalk., p. 61.

MELOCRINID&. 283

are thickly covered with fine granules, producing a most beautiful orna-
mentation.

Basals small, forming a short cup; the columnar attachment small; the
axial canal pentalobate. Radials and costals large, as wide as long. Dis-
tichals two or 3X 10, somewhat smaller. Palmars three to four in the calyx,
decreasing in length upwards; the upper plates of the two inner divisions
axillary, supporting two arms, those of the outer divisions quadrangular,
bearing a single arm from the calyx. Arm openings thirty, directed up-
wards and not visible from aside view; the arms are not preserved in any
of the specimens. Interbrachials: 1, 2, 3, 3, 3; followed by other minute
pieces, which pass into the disk. Anal side wider: I, 3, 4, 4, etc.; the first
plate larger than the corresponding plate of the other sides, and there being
no anal ridge. Ventral disk very short, almost flat; the mterambulacral
spaces depressed. Surface covered by hundreds of very minute pieces with-
out orals, the plates being so small as to be readily taken for mere granules.
Anus excentric, placed at the summit of a small protuberance. Column
unknown.

Florizon and Locahiy. — Niagara group ; Waldron and Hartsville, Ind.

Mariacrinus Warreni Rincuesere.

Plate XXII. Fig. 1.

1888. Rrveveserc; Proceed. Acad. Nat. Sci. Phila., p. 133, Plate 7, Fig. 4.

Of the type of M. Carleyi, but having two distichals instead of three, and
no palmars in the calyx. It also differs from that species in the details
of its ornamentation. Calyx obconical, slightly contracted above the second
costals. Radial ridges rounded, wide and quite prominent; the surface finely
corrugated; and there are series of smaller transverse ridges meeting those
from the interbrachials.

Basals four, forming a conical cup. Radials and costals comparatively
large, wider than high. Distichals two, rather small. Palmars two or three
in the calyx; in form resembling arm plates, but longer. Arms twenty ;
long, slender, tapering gradually to a sharp point; the joints short, quad-
rangular ; their upper and lower faces almost parallel. Pinnules delicate,
long, closely packed ; composed of joints twice as long as wide. The arrange-
ment of the interbrachials cannot be accurately ascertained from the speci-
men, but it is apparent that the proximal plate at all sides rests upon the

284 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

sloping upper faces of two radials. Neither is anything known of the con-
struction of the disk. Column round, of moderate size, slightly tapering
downwards; near the calyx the nodal joints are somewhat larger than the
internodal ones, but at a length of about three inches all joints are of nearly
equal size.

Horizon and Locality. — Niagara shale; Lockport, N. Y.

Lype in the collection of Dr. Hugene Ringueberg, Lockport.

Mariacrinus plumosus* Hatt.
Plate XXTTI. Figs. 6 and 7.

1859. Hat; Paleeont. New York, Vol. III., p. 110, Plate 3, Figs. 6-11.
1881. W. and Sp.; Revision Paleocr. Part IL, p. 116.

A. small species. Dorsal cup apparently obconical; the surface orna-
mented by strong radiating ridges, proceeding from the centre of the plates
to adjoining ones, Basals about as long as wide. Radials a little longer
than wide. Costals nearly as large as the radials and of similar form. Dis-
tichals 3 X 10, each row supporting two arms, twenty in all. Arms simple,
rather long, composed of slightly cuneate joints. In the two outer arms, the
second joint gives off a pinnule to the outer side, the third is a hypozygal
joint, and the fourth gives off the second pinnule at the inner side; all suc-
ceeding joints being pinnule-bearing. The two inner arms, according to
Hall, support no pinnules up to the eighth joint, but this needs confirmation.
Interbrachials, 1, 2, 2,2. The arrangement of plates in the anal interradius
and construction of the ventral disk unknown. Column round, compara-
tively large.

Horizon and Locality. —In the shaly layers of the Pentamerous limestone,
Wheelock’s Hill, Litchfield, Herkimer Co., N. Y.

(?) Mariacrinus ramosus* Hatt.

1859. Hatn; Paleont. New York, Vol. III., p. 147, Plate 2, Fig. 6.
1881. W. and Sp.; Revision Paleoer., Part II., p. 116.

Dorsal cup urn-shaped, the rays marked by strong ridges, which pass into
the arms. Basals small. Radials and costals higher than wide. Distichals

* We are somewhat in doubt as to the generic relations of this species, and think it possible from Hall’s
figure that it may possess infrabasals, and therefore belong to a different genus. We do not reproduce the
original figure, because it does not agree with the description, either in the arrangement of the plates in the
calyx, or the construction of the arms. We had no opportunity to see the type specimen, and only can give
an abstract of Hall’s description.

MELOCRINID &. 285

3X10, each series supporting two arms, or twenty from the calyx. The
two inner arms branch three times, the outer ones remain simple. Above
the last bifurcation, according to Hall, the arms are composed of a “ double
series of wedge-formed plates, and below these points of a simple series of
quadrangular plates,” with rounded pinnules.

Horizon and Locality. — Same as last.

Mariacrinus aureatus 8. A. Mixer.
(After Miller.)

1891. Adv. Sheets 17th Rep. Geol. Surv. of Indiana, p. 34, ‘Plate 6, Fig. 36.

Calyx very small. Dorsal cup bowl-shaped ; plates covered with angular
ridges passing out from their centres. Basals four, unequal; exposed
beyond the column. Radials the largest plates of the calyx, wider than
high. First costals a little smaller, their width greater than the length ;
pentangular or hexangular. Second costals as long as wide. Distichals two
in the three anterior rays, three in the posterior ones; the second plate of
the former axillary. Interradial areas elongate, subovate. Regular sides
composed of seven or eight plates: 1, 2, 2, 2; the first nearly as large
as the radials. Interdistichals one or two. The anal side has nine or ten
plates, there being three in the second, and four in the third row; the plates
of the upper row very small. Arm structure and tegmen not preserved in
the specimens.

Horizon and Locality. — Niagara group ; St. Paul, Ind.

MACROSTYLOCRINODUS Hatt.

1852. Hari; Paleont. N. York, Vol. IL., p. 208.
1857. Pictrt; Traité de Paléontologie, Vol. [V., p. 329.
1862. Dusarptn and Hurst; Hist. natur. des Zooph. Echin., p. 149.
1863. Hatt; Trans. Alb. Inst., Vol. IV., p. 207 (Abstr. p. 12).
1879. Hatn; Mus. edit. 28th Rep. N. Y. State Mus. Nat. Hist., p. 128.
1879. Zrrtri.; Handb. d. Paleont., Vol. I., p. 368.
1881. W. and Sp.; Revision Paleocr., Part II., p. 102; also Proceed. Acad. Nat. Sci. Phila., p. 276.
1881. Har; llth Ann. Rep. Geol. of Ohio, p. 256.
1882. Rinevesere; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 119.
1882. Dz Loriot; Paléont. Francaise, Tome XI., Crinoides, p. 56.
1883. W. and Sp.; Revision Paleocr., Part III., p. 102; also Proceed. Acad. Nat. Sci. Phila.,p. 324.
Syn. Actinocrinus (in part) — Lyon; Proceed. Acad. Nat. Sci. Phila., 1861, p. 411.
Syn. Cyathocrinus (in part) — Hai; Doc. edit., 28th Vol., N. Y. State Mus. Nat. Hist. (Hxplana-
tion of Plate 13).
Syn. Céenocrinus (in part) — Saumarp; Trans. Acad. Sci. St. Louis, Vol. IT., p. 360.

286 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Specimens small. Calyx obconical to subgtobose ; generally with promi-
nent ridges along the radial and anal plates; the surface densely covered
with very fine striz or small granules.

Basals three, large, unequal, forming a more or less deep cup; two of
the plates equal, the other one half smaller, Radials very large; their upper
corners but slightly truncated by the interbrachials. Costals two, small;
rarely more than one third the size of the radials, and in some species still
smaller. Of the distichals generally only the first plate takes part in the
calyx, but occasionally also the second. Arms ten, long, biserial, and simple
throughout. Interbrachials few. Anal area much the widest and quite
distinct. It has three plates in the first row, of which the middle one is
placed against the sloping upper faces of the two posterior radials; while
the two smaller ones at the sides, together with the first costal, occupy the
upper face of the plate, in a similar manner as the corresponding plates of
the Platycrinidse, except that those of Macrostylocrinus do not extend beyond
the limits of the dorsal cup. The middle or anal plate is generally followed
by one or two other anals, longitudinally arranged. Ventral disk low; com-
posed, so far as observed, of small irregular pieces. Column round; axial
canal small.

Distribution. — Restricted to the Niagara group of America.

Type of the genus: Macrostylocrinus ornatus Hall.

fiemarks. — This genus differs from all other Melocrinites in the number
of basals, and in having in the anal interradius three plates in the first row,
while the others have but one. The anal side of Hall’s diagram on page 130
of the 28th Rep. N. Y. State Museum is incorrectly given, and it appears
from the description that Hall was not aware that in MJacrostylocrinus the
arrangement of plates in the anal interradius differs from that of the other
sides. The basals in that diagram are represented as equal, while in fact
they are unequal, two of them being larger than the third.

Shumard regarded this genus as identical with Cfenocrinus Bronn, from
which it differs in the construction of the anal interradius — the latter
having but one plate in the first row— and also in the number of basals.

Macrostylocrinus ornatus Hatz.
Plate XXIII. Figs. Sa, b, c.

1851. Macrostylocrinus ornatus — Hau; Paleont. N. Y., Vol. I., p. 204, Plate 46, Figs. 4a-9.
1866. Ctenocrinus ornatus —Suumarp; Trans. Acad. Sci. St. Louis, p. 361.
1881. Macrostylocrinus ornatus — W. and Sr.; Revision Paleocr., Part II., p. 103.

MELOCRINID.®. ZO"

Dorsal cup about as high as wide; cross-section subpentangular ; the
median portions of the basals and costals slightly elevated ; their surfaces,
and those of the radials, covered with fine, interrupted striz, and the inter-
brachials with elongate tubercles, which at the centre of the plates become
obsolete. The suture lines well defined.

Basals not as large as in some of the other species, forming a shallow
basin with obtuse upper angles. Radials more than twice as large as the
costals, slightly spreading; the upper faces somewhat shorter than the
lower _ First costals hexagonal, their upper sloping faces much shorter than
the sloping lower ones; the second costals smaller than the first, the upper
side obtusely angular. Distichals free above the first; the three proximal
plates quadrangular, the edges of their upper and lower faces crenulated ;
_ the succeeding three or four plates cuneate, and the plates above interlocking
so as to form two rows of arm plates; the latter covered by two rounded
tubercles, transversely arranged, and placed in rows longitudinally. Arms
ten, long and rounded. Regular interbrachials three known; the lower
plate twice as large as the two upper; the latter resting against the sides of
the second costals, slightly touching the first. All other parts of the species
unknown. |

Horizon and Locality. — Shales of the Niagara group; Lockport, N. Y.

fiemarks.— We have been unable to trace the type specimen, and our
description was made from Hall’s figure in the New York Report.

Macrostylocrinus striatus Hatt.
Plate XX. Figs. 144, b,c.

1863. Hain; Trans. Alb. Inst., Vol. IV., p. 207 (abstr. p. 13).

1866. Suumarp; Trans. Acad. Sci. St. Louis, Vol. IL., p. 861 (Ctenocrinus striatus). :
1879. Hann; 28th Rep. N. Y. State Mus. Nat. Hist. (Museum edit.), p. 129, Plate 13, Figs. 1-4.
1881. W. and Sp.; Revision Paleocr., Part II., p. 103.

1882. Hatt; 11th Ann. Rep. Geol. and Nat. Hist., Ohio, p. 257, Plate 12, Figs. 1-4.

Calyx to the bases of the arms pyramidal; the sides slightly convex; the
fixed brachials formed into broad rounded ridges, which pass up to the arms;
interradial spaces somewhat concave, except at the anal side where the
median portion is slightly bulging and angular. Surface of plates covered
by fine undulating strize or series of granules, about twelve of which traverse
the lower half of the radials to the basals; another set passes up to the

costals, and a third and fourth transversely to the sides of adjoining radials.

288 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Kach line of the transverse sets meets one of the longitudinal lines at right
angles or less, and the apices of these angles fall into lines from the centre
to the corners of the plates. |

Basals large, forming a flat basin; column facet small and slightly pro-
jecting ; the upper margins distinctly pentangular. Radials large, even for
the genus. Costals curved like arm plates; the first less than one fourth the
size of the radials. The first palmar, which bends slightly outward, included
in the calyx. Structure of arms unknown, but there were apparently two
arms to the ray. Interbrachials in two ranges, composed at the regular
sides of one plate each, of which the second is considerably smaller. The
anal side, which is much wider, is composed of three plates in the first
row; the median one larger and wedged in between the sloping sides of
the radials; the second range consists of five smaller plates, irregularly
arranged, and followed by still smaller pieces.

florizon and Locality. — Niagara group; Waldron and Hartsville, Ind.

Liemarks. — This species is allied to MZ. ornatus, but differs in the propor-
tions of the plates and the absence of radial ridges. The specimen figured
by Hall in the 20th Rep. of N. Y. State Cabinet on Plate 10, Fig. 7, under
M. striatus, seems to us to differ essentially from that species in the propor-
tions of the plates, and may even belong to a different genus.

Macrostylocrinus fasciatus Hatt.
aie (XO, Pg lo:

1876. Cyathocrinus fasciatus —Haui; Doc. edit. 28th Rep. N. Y. State Museum Nat. Hist., Plate 18,
Figs. 5 and 6 (without description).

1879. Macrostylocrinus fasciatus — Hatt; Mus. edit. of same Rep., p. 180: and 11th Ann. Rep. Geol.
and Nat. Hist. Ohio, 1882, p. 258, Plate 12, Figs. 5 and 6.

Calyx subovoid ; height to width as ten to seven; rounded to two thirds
the length of the radials, cylindrical above; arm bases but little projecting ;
ventral disk almost flat. Surface of plates densely covered by fine, waving
striz, which radiate in fascicles from the basals to a place a little above the
centre of the radials, whence other bundles pass out to the interbrachials
and adjoining radials. In addition to the striw, the surface is marked by
indistinct ridges, which follow the median line of the fascicles, and produce
a well defined stellate prominence upon the basal cup and upon each radial
and first interbrachial plate. The ridges upon the costals are the most
prominent, and increase in width on approaching the arm bases.

MELOCRINID.Z&. 289

Basals large, forming a rounded cup, with a narrow columnar attachment.
Radials unusually large, fully four times the size of the costals, and about
three times as long; very little sloped to meet the first interbrachial. First
costals somewhat larger than the second. The two proximal palmars incor-
porated into the calyx, the others free. Arms ten. Interbrachials compar-
atively small, one and two at the regular sides; the anal side wider, and
composed of three plates in the first row. Ventral disk constructed of small
irregular pieces. | |

Horizon and Locality. — Same as last.

Remarks. — Hall’s figures 5 and 6, on Plate 183 of the 28th Rep. N. Y.
State Museum, are incorrect and misleading. The first costals are represented
twice as large as they actually are, and the ornamentation is also somewhat
different in the specimens. In the 20th Rep. of the same series, Plate 10,
Fig. 1, Hall figures a cast from the Niagara group of Racine, Wisc., described
on page 379 under the name of Actinocrinus (Saccocrinus) semiradiatus, which
may possibly be a large example of this species.

Macrostylocrinus granulosus (H4z1).
Plate XXII. Figs. 15a, b.

1879. Macrostylocrinus striatus, var. granulosus — Hau; 28th Rep. N. Y. State Mus. Nat. Hist. (Mu-
seum edit.), p. 129. |
1885. M. striatus, var. granulosus — W. and Sv.; Revision Paleocr., Part III., p. 109.

A more slender species than the preceding. Dorsal cup obconical; its
sides nearly straight, spreading gradually and uniformly upwards; cross-
section at the top of the costals decidedly pentangular; the basals and all
plates following the rays marked by broad, rounded ridges. Another promi-
nent ridge passes from the anus downward to the middle of the proximal
anal plate, where it bifurcates to adjoining radials. Narrower ridges connect
the radials laterally, and form a well defined boundary line between the
upper and lower portions of the dorsal cup. The general surface is covered
by fine wrinkles and indistinct stris ; those following the radials and costals
longitudinally arranged, the others meeting within the middle of the plates.

Basals and radials smaller than in the preceding species; the latter plates
about as wide as long, subquadrangular, and but very little sloped at the
upper corners. First costals less than two thirds the length of the radials,
and considerably narrower; second costals shorter and narrower than the

37

290 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

first, their upper angles acute. Arms two to the ray, free above the first
} plate, which is longer than wide. The arms, according to Hall, are long,
slender, and simple. Regular interbrachials slightly convex; arranged: 1,
2,3. Anal interradius much wider, composed of three plates in the first
range ; the middle or anal plate longer than the two at the sides and fol-
lowed by a second anal piece, of which the top is on a level with the top of
the interbrachials of the third range. Structure of ventral disk unknown.

Horizon and Locality. —Same as last.

ftemarks. — Prof. Hall made this species a variety of M. striatus. It is,
however, sufficiently different to be recognized as a distinct species, which
we believe is more nearly related to MZ. fasciatus than to W. striatus.

Macrostylocrinus Meeki (Lyon).
Plate X XIT. Figs. 16a, b

1861. <Actinoerinus Meeki — Lyon; Proceed. Acad. Nat. Sci. Phila., p. 411, Plate 4, Figs. 4a, 0.

1881. Macrostylocrinus Meeki —W. and Sp. ; Revision Paleocr., Part II., p. 103.

Calyx subglobose, about as wide as high; cross-section slightly pentangu-
lar. A well defined ridge rises from the column, follows the median line of |
the various radial plates, and passes into the arms. The ridge, which is
rather obscure upon the basals, gradually increases in size, and grows quite
prominent upon the costals. Smaller ridges proceed from the centre of the
radials to the interbrachials, and form with the larger ridges numerous
obscure triangles. The inner spaces of these triangles are occupied by fine
closely arranged strie, which form additional triangles one within the other ;
there being five such sets of triangles around the column, which extend to
the middle of the radials, and are larger and better defined than any of the
others.

Basals forming a shallow basin, rounded at the bottom; the column facet
slightly concave. Radials fully four times as large as the first costals, and as
long as wide. First costal narrower than the second, and fully twice as wide
as long; the second somewhat larger, its sides spreading rather abruptly
upwards, the sloping upper faces concave and forming an acute angle. First
interbrachial large, a little longer than wide, resting against the distinctly
sloping sides of the radials, and rising to the top of the second costals; the
succeeding plates much smaller. The arrangement of plates at the anal side
is not known; neither is the construction of the ventral disk nor the struc-

ture of the arms.

MELOCRINIDZ. 291

Horizon and Locality. — Niagara group; Jefferson Co., Ky.
Types in the Knapp collection at the Borden Institute of New Provi-

dence, Ind.

Macrostylocrinus fusibrachiatus Riyevesere.
Plate XXII. Figs. 9 & 10.

1881. Rinevesere; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 119, Plate 5, Fig. 4.
1885. W.and Sp.; Revision Paleocr., Part III., p. 102.

‘

Larger than the preceding species, and proportionally broader. Dorsal
cup apparently bow]l-shaped — the exact form not being ascertainable owing
to the crushed condition of the specimen ; interradial spaces depressed ; sec-
tion subpentagonal ; surface of plates covered by numerous small, irregu-
larly arranged granules.

Basals of moderate size, forming together a rapidly spreading pentagonal
cup; the column facet surrounded by a small rim, formed by a row of small,
closely arranged nodes. Radials large, wider above than below, subquad-
rangular; the upper corners slightly truncate. First costals quadrangular,
less than half the size of the radials, nearly twice as wide as long. Second
costals smaller than the first, and considerably shorter. Distichals free after
the second plate. Arms ten, long, massive, widest in the middle, and taper-
ing at both ends. The two fixed distichals are followed by a few much
shorter cuneate pieces, and the latter by two rows of short transverse plates,
alternately arranged and united by a zigzag suture. Regular interbrachials
five in three ranges; the first plate large and oblong; the arrangement of
the anal side unknown. Column round; the edges of the nodal joints. sur-
rounded by small nodes.

Horizon and Locality. — Niagara group ; Lockport, N. Y.

Type in the collection of Dr. E. N. 8. Ringueberg.

fiemarks. — The specimen illustrated by Fig. 10 differs slightly from the
type, being smaller, and having a more elongate cup, less massive arms,
and proportionally higher costals. But as it is of the general habitus of
this species, we take it to be a young specimen of the same.

292 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

MELOCRINUS Gotprvss.

1826. Gonpruss; Petref. Germanie, Vol. I, p. 197.
1838. Agassiz; Mém. de la Soc. des Sci. natur. de Neuchatel, Vol. I, p. 196.
1838. Goxpruss; Nova Acta, Acad. Leopoldina, Vol. XIX., I., p. 339.
1841. Mizier; Monatsber. d. Berlin. Akademie, p. 209.
1849. D’Orpreny; Cours élément., Vol. II.,p. 140.
1852. QurNstept; Handb. d. Petrefactenkunde (Ausg. I.), p. 620.
1855. Rormer; Lethaea Geognostica (Ausg. 3), p. 250.
1857. Pricrer; Traité de Paléont., Vol. IV., p. 325.
1862. Dusarpin and Huri; Hist. natur. des Zoophytes, p. 144.
1867. Scuutrze; Monogr. Echinod. Hifl. Kalk., p. 61.
1878. Anertin; Iconogr. Crin. Suec., p. 19.
1872. Zirren; Handb. d. Paleont., Vol. L., p. 371.
1881. W.and Sp. ; Proceed. Acad. Nat. Sci. Phila., p. 292
1881. W. and Sp.; Revision Paleoer., Part II., p. 118.
1882. Dx Lorton; Paléont. Francaise, Tome XI. (Crinoides), p. 58.
1885. W. and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 326.
1885. W. and Sp.; Revision Paleoer., Part III., p. 104.
1885. Qurnstept; Handb. d. Petrefactenkunde (Ausg. 3), p. 957.
1889. 5S. A. Minter; N. Amer. Geol. and Paleont., p. 261.
Syn. Crenocrinus Bronn ; 1840, Jahrb., p. 542; also Miller, 1855, Verh. naturh. Verein, Vol. XII.,
p. 16, and Neue Hchinod. Hifl., Kalk., p. 255; also Follmann, 1857, Unterdevonische Crinoideen,
p. 14.
Syn. Castanocrinus RonMER; 1855, Leth. Geogn. Vol. II., p. 252.
Syn. Martacrinus Hatu (in part) ; 1857, Paleont. N. Y., Vol. ITI., p. 104.
Syn. Cytocrinus Roumur; 1860, Silur. Fauna West. Tenn., p. 46.
Syn. Clonocrinus OEHLERT; 1879 (not Quenstedt), Soc. Géol. de France (sér. 3), Vol. VIL., p- 9.
Syn. Lurbinocrinites Troost; 1850, List of Crin. Tenn. (not defined).
Syn. Astrocrinites Conrad; Ann. Geol. Rep. N. Y. of 1840 to 1841 (not Cumberland, 1826, nor
Austin, 1842, nor Htheridge, Jun., 1876, nor Asterocrinus Minster, 1839, nor Lyon, 1857, nor
Astrocrinus Ether. and Carpenter, 1886).

Calyx obconical, subglobose or pyriform; the rays extended into free
tubular appendages bearing arms on both sides. Basals four, unequal; three
of them quadrangular, the anterior one larger and pentangular. Radials in
contact laterally; four of them heptagonal, the anterior one, which rests
squarely upon the anterior basal, hexagonal. First costal hexagonal, the
second, which is axillary, generally pentagonal; the sloping faces of the
latter may be equal and support two rows of distichals, or unequal, when
only the longer inner face is followed by distichals, the shorter outer one
giving off the proximal arm. In the former case, which is the general rule,
the distichals constitute parts of the calyx, and both series terminate in
axillaries, which give off toward the inner side of the ray in a nearly verti-
_ cal direction an indefinite number of brachials of successive orders, and
toward the outer side a sloping arm from each order. The plates of the
different orders are short and consist of two parallel series, which form two
arm-bearing trunks. The two trunks, as a general rule, meet laterally by

MELOCRINID 2. | 293

suture, and form together rigid tubular appendages, which pass out from the
calyx upwards. In some cases the connection of the appendages is inter-
rupted for short distances, but, so far as known, all of them come together,
and are united toward the upper part. From these appendages throughout
their full length, at certain intervals, and from opposite plates (not alter-
nately) are given off well defined biserial arms, bearing pinnules on alternate
sides. A slight departure in the construction of the main trunks occurs among
species in which the proximal arms are given off already from the first
axillaries, 7. ¢., from the costals. In these species the trunks at the dorsal
surface are composed of but a single series of plates, and the pinnule-bearing
arms are arranged alternately as in Steganocrinus sculptus. The ventral sur-
faces of the appendages are roofed over in all cases by rigid covering plates.

Interbrachials numerous; the first placed upon the sloping upper faces
of the radials, followed by two plates in the second row at the four regular
sides, three plates at the anal side, and a greater or less number of irregular
plates above, which meet with the interambulacral plates. Ventral disk
highly elevated or scarcely convex; the orals in some species largely de-
veloped, in others indeterminable. Anus excentric and generally — perhaps
always — extended into a small tube.

Column round, composed of alternate long and short joints; axial canal
small.

Distribution. — Melocrinus ranges from the Upper Silurian to near the
close of the Devonian, and is well represented both in America and Hurope.

’ Remarks. —The genus Melocrinus holds the same relation to Mariacrinus
that Steganoerinus does to Actinocrinus, and Eucladocrinus to Platycrinus. In
all these types the construction of the calyx remains relatively almost un-
changed, while a remarkable modification occurs in the brachial appendages,
which are extended into tubular rays with an indefinite number of semi-free
brachials, giving off arms.

Several attempts have been made to subdivide Melocrinus into two or
three genera. Roemer, in 1855, proposed the name Custanocrinus for
species with a central or subcentral anal opening, retaining Melocrinus, with
M. hieroglyphicus Goldfuss as type, for species with a lateral opening. Our
examination of the various species leads us to doubt whether such a division
can be practically upheld. We agree with Schultze * that the anus is never
central in this genus, nor in any case actually lateral, but its position is

* Monogr. Hifl. Kalkes, p. 63.

294 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

always more or less excentric. Neither can the presence or absence of inter-
distichals, unless accompanied by other distinctive characters, be considered
sufficient for generic separation, as proposed in the case of Cfenocrinus
Bronn.* Those plates are mere auxiliary pieces, which may be present
or absent in the same species.

Lurbinocrinites Troost was proposed in MS., according to Hall,t for a
species which was said to have the first anal plate on a level with the
radials; but Troost’s typical species, Melocrinus Vernewili, had no such plate,
or Hall could not have stated that the anal area was but slightly distinct
from the other four. | }

Cytocrinus was described by Roemer with three (?) basal plates — the
exact number not having been ascertained. A good specimen in our collec.
tion from Roemer’s typical locality plainly shows four plates, and we have
no doubt the species is a Melocrinus.

Phallipsocrinus McCoy is described with four basals, succeeded by seven
plates in the next ring, which shows that it is an abnormal specimen. If it
is, as we think, an Actinocrinoid, the abnormal seventh plate may have
necessitated the presence of a fourth basal.

In addition to the species herein figured and described, we note the
following : Melocrinus obpyramidalis Winchell and Marcy, M. Vernew Hall
(not Oehlert), and JZ. nodosus Hall, which were described from unsatisfactory
natural casts. Neither can M. Pratteni (Forbesiocrinus Pratteu) McChesney,
which was defined from a fragmentary specimen, or Melocrinus seulptus Hall,
of which only the basal plates are known, or I. brevidactylus Hall, which
was figured but not described, and the figure not properly published, be
regarded as good species.

* The genus Clenocrinus was at first incorrectly defined. It was described by Bronn, 1840 (Jahrbuch,
p. 542), with three basal plates, and this number was confirmed by Roemer (Lethaea Geogn., 1855, p. 251).
Subsequently de Koninck considered the genus identical with Pradocrinus De Verneuil, which actually has
three basals. Joh. Miller (Verhandl. naturh. Verein, 1855) admits more than three basals, probably five,
and in 1857 (Neue Hchinod. Hifl. Kalk., p. 255), asserts positively the presence of five basals. He com-
pared Crenocrinus with Glyptocrinus Hall, and supposed both to have “parabasalia.” Schultze afterwards, in
his Monograph, p. 63, proved from more perfect specimens that Otenocrinus typus has but four basals, and no
infrabasals, and referred that species to Melocrinus. Follman, in his article on the “ Unterdevonischen
Crinoideen,”” Verhandl. Naturh. Verein, 1887 (private ed., p. 14), revised the genus Ctenocrinus with four

basals, but pointed out no characters by which it may be distinguished from Melocrinus.
T 28th Rep. N. Y. State Mus. Nat. Hist. (Museum edit.), p. 139.

MELOCRINID %. 295

Melocrinus nobilissimus (Ht).
Plate XXIII. Figs. 1a, 2, 3.

1859. Mariacrinus nobilissimus -— Hatt; Paleont. N. Y., Vol. II1., p. 105, Plate 2, Figs. 1-4, and Plate
1881. Peas ene and Sp.; Revision Paleocr., Part II., p. 122.

A rather large species. Dorsal cup higher than wide, obconical, obtusely
pentangular above the costals owing to a depression in the upper portions
of the interradial spaces, The tubular appendages supporting the arms con-
sisting of two contiguous trunks, which are composed dorsally of two rows of
plates. Plates marked with obscure radiating ridges; the suture lines well
defined, with a shallow pit at each angle.

Basals wider than long, formed into a small subcylindrical cup, not pro-
jecting beyond the column. Radials larger than the costals, about as wide
as long. The second costals with an obtuse angle above. Distichals 3 x 10,
about half the size of the costals, the upper ones axillary and supporting
upon their outer sloping faces a lateral arm, of which the four or five proxi-
mal plates, which are longer, are incorporated into the calyx; while the inner
sloping faces are followed by a row of from six to seven palmars. The latter
form a vertical line with the distichals, and the plates of adjoming divisions
are connected laterally, except the two proximal ones of each side, between
which are interposed small irregular interdistichals. The fourth and fifth
orders of brachials consist of five plates, the sixth and all orders to the ninth
of four, the succeeding ones of three, and those near the top of but two
pieces. The brachials are arranged longitudinally, and connected suturally
with those of the opposite branch, so as to form a compound, free tubular
appendage, from which the arms are given off at opposite sides, the axillaries
supporting on their longer sides the next order of brachials, and on their
shorter ones an arm. There are about thirty arms to each side of the ray,
rising to the same general height; all composed from the second plate up of
two series of interlocking pieces, and all pinnule-bearing. Regular inter-
radial spaces narrow but long; the first plate rests within a deep notch
between two radials, and is somewhat larger than the others; the succeeding
ones are not arranged in horizontal rows, but alternate with one another;
they are hexagonal, and the upper lateral faces of the one plate rest against
the lower lateral faces of the other, thus forming two longitudinal rows side
by side, each composed of about twelve plates, which decrease in size

296 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

upward. Anal interradius considerably wider, and flattened instead of being
grooved as in the case of the other four; the first plate is the largest, and is
‘followed by three pieces in the second row, and these by three or four pieces
in the succeeding rows. Interdistichals four, rather large and longitudinally
arranged; the upper one resting between the two proximal palmars. Nothing
is known of the ventral disk, nor of the anus. Column large, round, com-
posed near the calyx of moderately long joints alternating with shorter ones;
suture lines distinctly waving.

florizon and Locality. — Pentamerus limestone; Litchfield, Herkimer
Co., N. Y., and apparently also found in the Niagara group of Western
Tennessee. | :

Types in the American Museum of Natural History, New York.

Melocrinus pachydactylus (Conran).
Plate XXIII. Figs. 4 and 5, and Plate XXIV. Figs. 4a, b.

1841. <Astrocrinites pachydactylus — Conrad; Ann. Rep. Paleont. N. Y., p. 34. Also Mather 1848;
Geol. Rep. N. Y., p. 246.
1859. Mariacrinus pachydactylus — Hauu; Paleont. N. Y. Vol. III., p. 107, Plate 3, Figs. 1-4.
1881. Melocrinus pachydactylus — W. and Sp.; Revision Paleocr., Part IT., p. 122.
Syn. Actinocrinus polydactylus Bonny (not 8. A. Miller) ; Schenectady Reflector of 1835.
Syn. Mariacrinus paucidactylus Watu; Paleont. N. Y., Vol. LIL. p. 109, Plate 3, Fig. 5.
Syn. Melocrinus paucidactylus — W. and Spv.; Revision Paleocr., Part IL., p. 122.

Smaller than the preceding species; dorsal cup shorter and with convex
sides; interradial spaces not grooved, although slightly impressed in the
upper portions; the radiating ridges upon the surface much more conspicu-
ous, and ending in a node at the centre of the plates; the arms given off at
greater intervals, and the pinnules less closely packed together than in that
species. |

Basals formed into a short spreading cup, of which the lower margin
is slightly projecting. Radials and costals of nearly equal size, as wide
as long; both covered by a broad, flattened ridge, which bifurcates on the
second costal and follows the distichals. Narrower ridges pass out to the
interbrachials. Distichals 3 X 10, smaller than the costals. The axillaries
support upon the inner sides of the ray from seven to eight palmars, which
are laterally connected; at their outer sides the proximal arms, of which
the five lower plates are considerably the longest, and form part of the calyx.
The two lower palmars of each side are longer than the upper ones, and

those of the one division are separated from those of the opposite side by a

MELOCRINID 2. 297

small interdistichal. The surface of these plates is covered by radiating
ridges and nodes; while that of the succeeding ones is without ornamenta-
tion, and the plates are transversely arranged. The brachials of the fourth
order consist of six plates, those of the succeeding ones of five, rarely four
(so far as observed) ; all transversely arranged, and suturally connected with
their fellows of opposite sides, forming five long tubular, arm-bearing trunks.
The arms of this species are more slender than in the preceding one, and
slightly more tapering, the pinnules longer; they are flattened on the back,
and the surface is corrugated. Interradial spaces composed of about twelve
plates arranged in two longitudinal rows, the plates alternating with one
another. The anal interradius and ventral disk are not visible in the speci-
mens. |

Florizon and Locality. —Schoharie Co., N. Y.; Lower Helderberg group.

Types in part in the American Museum of Natural History, New York.

Melocrinus bainbridgensis Hatt and Wuirriecp.
Plate XXII. Figs. 4a, b,c, and Plate XXIV. Fig. 6.

1875. Melocrinus (Ctenocrinus) bainbridgensis — Geol. Surv. Ohio, Paleont., Vol. II., p. 158, Plate 13,
Figs. 2 and 3.

1881. Melocrinus bainbridgensis — W. and Sp.; Revision Paleocr., Part II., p. 121.
Syn. Melocrinus Clarket Williams ; 1882, Proceed. Acad. Nat. Sci. Phila., p. 31.

Specimens above medium size. Dorsal cup as high as wide, rather rap-
idly spreading; sides somewhat convex; cross-section pentangular. Plates
slightly elevated, beveled at their margins ; the middle part a little depressed,
and covered with a system of confluent granules; the suture lines grooved.

Basals forming a low cup with a small rim around the lower margin,
which is notched at the interbasal sutures; axial canal pentalobate. Radials
and costals wider than long, decreasing in size upwards. Distichals 3 < 10,
those of the same ray in contact laterally, interdistichals not: being repre-
sented; the proximal one less than half the size of the second costal, and as
long as wide; the two others much shorter. The third plate, which is axil-
lary, supports upon its inner face the next order of brachials, at the outer
the proximal arm which is free from its origin. The brachials of the suc-
ceeding orders also consist of three pieces, which are transversely arranged,
and those of the same ray are laterally connected, forming trunks from
which arms are given off at every third plate. The trunks taper upward, and

are deeply grooved along the line of contact of the two branches. Arms
38

298 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

thin, thread-like, with closely packed pinnules. Regular interbrachials:
1, 2, 8, and others above, which gradually intermingle with the interambu-
lacrals. The first interbrachial of the anal side is somewhat the largest, and
is followed by three plates in the second row, which form an arch, and by
four pieces in the third and fourth rows. Ventral disk low, depressed-pyra-
midal, apparently surmounted by a subcentral anal tube; the plates more
or less uniform, of about medium size, and somewhat convex.

Horizon and Locality.—-In a limestone layer, six inches in thickness,
above the base of the Black Slates, Bainbridge, Ross Co., O., and at Canan-
daigua, N. Y., in rock of about the same age.

Liype in the Ohio State collection, Columbus. )

ftemarks. — Prof. J. M. Clarke of Albany had the kindness to send us
gutta-percha casts of the types of Melocrinus Clarkei Williams, which we
regard as identical with M. bainbridgensis.

Melocrinus gracilis W. and Sp. (nov. spec.).
Plate XXII, Fig. 6.

A rather small species, of the type of Melocrinus (Ctenocrinus) stellaris
Roemer. Dorsal cup obpyramidal; the radials and costals strongly curved
so as to form broad, very conspicuous longitudinal ridges with a small
tubercle at the centre of each plate, those of the axillaries being the longest
and sharpest. Interbrachial spaces depressed, giving to the section across
the second costals a sharply pentangular, somewhat stelliform outline.

Basal cup low, broadly truncate at the bottom, its lower edges slightly
projecting beyond the column; the upper angles turned abruptly upwards.
Radials and costals nearly equal in size, wider than long, but the curvature
makes them appear to be longer than wide. Distichals 2 x 10, rounded like
arm plates; short, transversely arranged, those of the same ray separated by
one or two minute interdistichals, which rest within the bottom of a shallow
pit. The arm trunks bend outward, are heavy, and composed of two rows
of short pieces. The arrangement of the arms cannot be ascertained, as in
the single specimen the trunks are preserved only to the fourth plates, and
of the arms only fragments of a single one. Interbrachials numerous,
slightly decreasing in size upward ; arranged: 1, 2, 3, 3,-efc. They are
somewhat convex and ornamented with obscure radiating ridges, which con-
nect with the interambulacral plates. Ventral disk elevated, and, so far as

MELOCRINIDA, — 299

known, composed of rather small pieces. Form and position of anus un-
known. Column round, strong; the nodal joints projecting, the intervening
ones knife-like.
Horizon and Locality. — Hamilton group; Canandaigua Lake, N. Y.
Type in the collection of Prof. J. M. Clarke, now in the State Museum at
Albany.
Melocrinus Tiffanyi W. and Sp. (nov. spec.).

Plate XXIT. Figs. 7a, b.

Calyx pyriform; the sides nearly straight from the top of the basals to
near the bases of the arms; the tegmen depressed-hemispherical ; cross-
section, as seen from above, obtusely pentangular. Surface of plates orna-
mented by faint ridges, radiating from near the centre of the plates to the
centre of adjoining ones. |

Basals projecting laterally, forming four conspicuous, elongate nodes;
the lower part somewhat excavated for the reception of the column. Radials
and costals gradually decreasing in size upwards, about as long as wide; the
second costals not more than half the size of the radials, Of the distichals
two plates are preserved; the lower one fully one half smaller than the
preceding axillary; the second short, shaped like an arm joint and curving
outwards. There are no interdistichals, all plates of the arm trunks being in
contact laterally. Interradial areas on a plane with the radials and costals:
the first interbrachial the same size as the radials, and followed in the type
specimen by two plates at three of the sides, but in the posterior and right
antero-lateral interradius by three, and these by numerous rows of from
three to four plates, which connect with the disk pieces. Ventral disk
depressed-hemispherical, the plates very uniform, rather large, having the
size of the third row of interbrachials. They are ornamented like the plates
of the dorsal cup, but are a little more convex. There are apparently no
orals. Anus excentric, probably connected with a tube. Arms unknown;
column round.

Horizon and Locality. — Hamilton group; New Buffalo, Iowa.

Type in the collection of Mr. §, A. Tiffany of Davenport.

| Billy Si

300 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Melocrinus Calvini W. and Sp. (nov. spec.).

Plate XXII. Fig. 6.

similar to the preceding species, but the sides of the dorsal cup convex,
and the general form of the calyx subovoid; the basals less projecting; the
radials, fixed brachials and interbrachials — the latter to the third row —
crowned by a large, rather conspicuous rounded node without other orna-
mentation; the upper interbrachial and interambulacral plates a little
convex.
~ Basals projecting laterally, and forming four rather conspicuous nodes
around the columnar attachment which is a little projecting. Radials and
costals longer than wide, The distichals of the same ray in contact laterally.
Regular interbrachial spaces large, but slightly depressed between the arm
trunks; the plates arranged: 1, 2, 3, 8, the upper ones insensibly connecting
with the plates of the ventral disk. Anal interradius widest, having three
plates in the second row. Ventral disk short; the plates rather small and of
uniform size; orals apparently unrepresented. Anus excentric, probably at
the end of a narrow tube. |

Horizon and Locality. — Hamilton group; Johnson Co., Towa.

Lype in the collection of Prof. 8. Calvin of Iowa City, in whose honor
this rare species is named.

Melocrinus oblongus W. and Sp. (nov. spec.).
Plate XXII. Figs. 9 and 12.

A rather slender species of less than medium size. Dorsal cup obconical ;
the sides straight to the top of the second costals, whence the rays turn out-
ward and form distinct lobes around the calyx, which give to the section
a decidedly pentalobate outline. Plates convex, a little nodose, but without
ornamentation.

Basals small, subequal, notched at the sutures; the lower face but slightly
truncate, and very little excavated. Radials and first costals generally
longer than wide, especially the former; the second costals often as wide
as long. Distichals 2 x 10, the two upper ones axillary and separated by
a small interdistichal. The arm trunks not preserved in the specimens, but
as there are two distichals, the trunks must have been formed of two rows of
plates. The first interbrachial as large as the first costal; succeeded by

MELOCRINID.&. 301

rows of 2, 3,5, and three plates, which meet the interambulacrals. Anal
interradius a little wider, with three plates in the second row, and four in
the third. Ventral disk low, irregularly convex; the ambulacral spaces
slightly elevated; the plates — orals included — almost of uniform size.
Anus subcentral; at the end of a tube.

Horizon and Locality.— Niagara group; near Louisville, Ky., and St.
Paul, Ind. |

Types in the collection of Wachsmuth and Springer.

ftemarks. — This form was regarded by Roemer* as specifically identical
with his Cytocrinus levis, which comes from the same horizon in Tennessee,
and resembles it in general form; but the arm trunks of that species are
composed of single joints, and it has a smaller number of interbrachials.

Melocrinus Roemeri W. and Sv. (nov. spec.).
Plate XXII. Figs. 11a, 6.

Syn. Cytocrinus levis — Rormur; 1860. Silur. Fauna West. Tenn., p. 46, Plate 4, Figs. 2a, b, ¢
Syn. Crenocrinus levis —SuvumMarp; 1866. Trans. Acad. Sci. St. Louis, p. 8361.
Syn. Meloerinus levis (not Goldf.) —W. and Sp. (in part); 1881. Revision Paleocr. Part IL., p. 122.
Calyx moderately small, turbinate; dorsal cup about as wide as high,
gradually spreading to the arm bases, which are formed into five very con-
spicuous lobes, giving to the calyx, as seen from above, a decidedly stellate |
outline. Plates without ornamentation, a little concave, except the median
line of the radial plates, which is obtusely angular. The radial appendages
from which the arms are given off composed of a single series of plates.
Basals rather large, subequal, forming a shallow cup, which is slightly
truncate at the lower end.. Radials twice as large as the first costals, hexa-
gonal, about as wide as long; their upper sloping faces a little larger than
the corresponding lower ones. Second costals very small and curved like
arm plates; their upper sloping faces unequal, that toward the outer side of
the ray much the longest, and supporting a distichal, the inner one the first
arm plate. The trunks, which consist of a single series of plates, give off the
arms at intervals from alternate sides, not from opposite plates as in species
with a double series. Interbrachial spaces wide, the first plate large, succeeded
by two rows of two and three plates respectively, which are followed by disk
plates. The two outer plates of the upper row curve outward and form the
sides of the lobes. At the anal side the first plate is larger, and followed by

* Silur. Fauna West. Tennessee, 1860, p. 48.

302 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

three plates in the second row, and four in the third. Ventral disk depressed,
pentagonal ; the ambulacral regions slightly raised above the general level ;
the plates without ornamentation, almost flat, and the sutures difficult to see.

The disk ambulacra are completely subtegminal; the orals apparently
unrepresented, and the anus is at the end of a large tube, which bends
toward the posterior side.

Florizon and Locality. — Niagara group; associated with Astreospongia
meniscus. Decatur Co., Tenn.

Lype im the collection of Wachsmuth and Springer.

Hemarks. — Roemer described this species as Oytocrinus levis, making it
the type of a new genus. He supposed it had three basals, and he did not
understand its arm structure, which is evidently that of Melocrinus. We
refer the species to the latter genus, but are compelled to change the specific
name, as Goldfuss in 1826 described a Melocrinus levis from the Eifel, and
propose for it Melocrinus Roemeri. Roemer originally included in his species
two forms, the typical one from the Niagara group of Western Tennessee,
and another from the same horizon of near Louisville. The latter has been
described by us as Melocrinus oblongus. The two species resemble each other
in form, but J. oblongus is considerably larger, the calyx contains many more
plates, and the radial appendages are composed of two rows of brachials in
place of one.

Melocrinus obconicus Hatt.
Plate XXII. Figs. 10a, b, e.

1863. Melocrinus obconicus —Hati; Trans. Alb. Inst., p. 206.

1875. Melocrinus obconicus —Hati; 28th Rep. N. Y. State Mus. Nat. Hist., p- 188, Plate 14, Figs. 11-14.
1881. Melocrinus obconicus — Hatt; 11th Ann. Rep. Geol. Ind. by Collet, p. 269, Plate 18, Fgs. 11-14.
1881. Mariacrinus obconicus — W. and Sr.; Revision Paleocr., Part II., p. 116.

Of medium size. Calyx obconical, about as wide as high; gradually
expanding from the top of the basals to the bases of the free appendages,
where it is distinctly lobed. Plates covered by numerous radiating ridges,
which pass out from the middle of the plates to the sides and angles, meet-
ing those of adjoining plates; the ridges passing up and down the radial
plates wider and somewhat higher. Besides these ridges the whole surface
of the plates — that of the ridges included — is finely corrugated, which adds
greatly to the beauty of the species.

Basals projecting, forming a short, indistinctly quadrangular, almost cylin-
drical cup. Radials and costals of about equal size, and all nearly as long

MELOCRINID &. | B03

as wide. Distichals two, the two divisions separated by one or two inter-
distichals. Palmars apparently not united laterally, and there may have
been two appendages to each ray. Interradial spaces depressed in the upper
portions; arranged: 1, 2, 3, with numerous plates above, which connect
with others in the disk. Anal area somewhat the widest, and with three
plates in the second row. Ventral disk almost flat; composed of very uni-
form, slightly convex pieces. Anus excentric, probably without a tube.
Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.
Type in the American Museum of Natural History, New York.

Melocrinus parvus W. and Sp.
Plate XXIT, Fig. 8.

1892. W. and Sp.; Amer. Geologist (September number), Vol. X., p. 144.

A small and very slender species of the type of Melocrinus Roemeri, hav-
ing like that species five uniserial radial appendages. Dorsal cup obpyr-
amidal, the interradial spaces deeply depressed, and the cross-section at the
top of the costals distinctly pentalobate. The plates a little convex and
covered with obscure ridges.

Basal cup almost cylindrical, its upper end slightly the widest, the lower
face completely covered by the column; the plates as high as the radials,
and the interbasal and basi-radial sutures distinctly grooved. Radials a little
longer than wide. First costals of the same proportions as the radials.
Second costals smaller, proportionally shorter, and irregularly axillary; one
of their upper faces short and giving off an arm, the other a row of distichals,
which are followed by higher orders of brachials, and arms given off at inter-
vals from opposite sides. Interbrachials three at the regular sides, and four
at the anal side, the latter having three plates in the second row against two
at the other sides. Ventral disk convex, the interambulacral spaces a little
depressed; composed of moderately large, slightly convex plates. Arms
excentric. |

Horizon and Locality. — Niagara group; St. Paul, Ind.

_Lype in the collection of Wachsmuth and Springer.

Ltemarks.— This species differs from M. Roemeri in the narrower and

less spreading base, in the proportions of the radials and costals, and in the
convexity of the plates,

304 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Melocrinus equalis 8. A. Mruter.
1892. Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 48, Plate 5, Figs. 11 and 12.

A moderately small species. Dorsal cup obpyramidal, decidedly pent-
angular at the arm bases, deeply sunken interradially. All plates of the
calyx heavy and tumid; those of the dorsal cup covered with short ridges
at their margins, one to each side, the median portions of the plates
smooth. Suture lines well marked. The radial appendages directed almost
horizontally.

Basals nearly equal, longer than wide, the sides very little expanding.
Radials as long as the basals, a little wider than long. First costals hexa-
gonal, almost as large as the radials; the second smaller and irregularly
axillary, giving off at the shorter side an armlet, and at the longer the next
order of brachials. Rays free above the costals, and evidently composed of
a single row of plates, with arms given off at alternate sides. Interradial
areas probably alike; the first interbrachial nearly as large as the adjoining
costal, followed by two and three smaller plates, of which the latter occupy
the arm regions. Plates of the teegmen very large, composed of only two
rings, the upper supporting a massive anal tube, composed of tumid or nodose
plates.

Horizon and Locality. — Niagara group, St. Paul, Ind.

Remarks. — This species resembles MZ. parvus in having simple free rays,
but differs from it distinctly in the form of the calyx, the greater convexity
of the plates, in having a much stronger anal tube, and the rays directed
horizontally.

Our description was made after Miller, and from fragmentary specimens in

our collection.

II. DOLATOCRINITES.

SYMMETRY OF THE DORSAL CUP UNDISTURBED BY ANAL PLATES.

TECHNOCRINUS Hatt.

1859. Tatu; Paleont. New York, Vol. ITI., p. 139.

1879. Zrrren; Handb. der Paleont., Vol. I., p. 372.

1881. W. and Sp.; Revision Paleoer., Part II., p. 116 (Proceed. Acad. Nat. Sci. Phila., p. 290).
1889. S$ A. Mitter; N. Amer. Geol. and Paleont., p. 286.

Calyx large; symmetry perfectly pentahedral up to the arm _ bases,
except a slight irregularity in the basal cup. Basals four, somewhat un-

MELOCRINID Z&. 305

equal, arranged as in Melocrinus. Four of the radials heptagonal, the
anterior one hexagonal. Costals two; the first hexagonal, the second gen-
erally pentagonal. Distichals 1x10, all axillary. The first palmar, and
sometimes the second, takes part in the calyx; the succeeding ones being
arm plates. Arms long, simple, straight, biserial; frmged by good-sized
pinnules, which are in contact. Interbrachials three or four, but no inter-
distichals. Structure of ventral disk and anus unknown. Column round;
tapering.

Distribution. — The genus is known only from the Oriskany Sandstone of
Maryland.

Type of the genus: Technocrinus spinulosus Hall.

Remarks. — Technocrinus differs from Mariacrinus and Melocrinus in the
perfect pentamerous symmetry of its dorsal cup, and from the former in hav-
ing one instead of three to four distichals, no interdistichals, and the arms
arranged in an almost continuous series around the calyx; while the arms of
Mariacrinus are arranged in groups. It differs from Melocrinus in having sim-
ple arms given off directly from the calyx, and not from its tubular extensions.

Technocrinus striatus and T. sculptus Hall, were described from detached
basal plates.

Technocrinus spinulosus Hatt.
Plate XXIT. Fig. 3.

1859. Hat; Paleont. New York, Vol. III., p. 140, Plate 85, Figs. 1-18.
1881. W. and Sp.; Revision Paleocr., Part II., p. 117.

Calyx subglobose, the arm bases slightly contracting. Plates of the
dorsal cup marked by a central spine or node, surrounded by smaller
nodes, which vary in number among the plates. From the nodes two to
four parallel ridges pass out to the sides, and these are continued upon
adjoining plates. Near the arm bases the ridges gradually disappear, and
the plates are marked only by a central spine.

Basals four, of medium size, forming a shallow basin with five sets of
four ridges, each set communicating with those upon the radials. Radials
and costals nearly as wide as long, decreasing in size upwards; the second
costal but half the size of the first. Distichals one to each side of the cos-
tal axillaries. The first palmar enclosed in the calyx. Arms twenty, stout,
rounded ; composed at their bases of cuneate pieces, which interlock farther

up, and gradually become biserial. Interbrachials apparently four. All
39 : |

306 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

other parts of the calyx unknown. Column slightly pentagonal, each alter-
nate joint provided with a node or short spine at the margin.

Horizon and Locality. — Oriskany Sandstone, Cumberland, Md.

Type in the American Museum of Natural History, New York.

Technocrinus Andrewsi Ha tt.
Plate XXIV. Fig. 8.

1859. Haun; Paleont. New York, Vol. IIL, p. 141, Plate 86, Figs. 1-4.
1881. W. and Sp.; Revision Paleocr., Part IL. p. 117.

A rather large species. Calyx to the arm bases hemispherical ; plates
moderately convex, surrounded by sets of short marginal ridges passing in-
ward, three to four to each side of the plate, and by small pits along the
sutures; the centre of the plates perfectly smooth. Basals wider than high.
Radials large, about as long as wide. First costals of the form of the radi-
als, but considerably smaller; the second still smaller, narrower as well as
shorter. Distichals one, axillary; supporting in the calyx two rather large
palmars, followed by several cuneate, interlocking free plates, and these by
two rows of subquadrangular pieces, united by a sharply zigzag suture.
Arms four to the ray, strong, flat, and of almost uniform width throughout.
Pinnules contiguous. Interbrachials four or five: 1, 2,1, 1, all compara-
tively large. Column round, large, tapering; the joints rather long and
slightly rounded exteriorly.

Horizon and Locahty. — Oriskany Sandstone, Cumberland, Md.

Type in the American Museum of Natural History, New York. The
species 1s described and figured from a cast made from the natural mould in
the rock.

ALLOCRINUS W. and Se.
1889. W.and Sp.; Geol. Rep. Illinois, Vol. VIII., p. 206.

Calyx small; the arms stout; symmetry of dorsal cup equilateral.
Basals three, small, unequal — the left antero-lateral plate one half the
smaller —— forming a disk, which is almost completely covered by the col-
umn. Radials large, much wider than the costals. Costals two, rounded
like arm plates. Arms uniserial, strong, simple; two to the ray, being
free from the second or third distichal. Interradial spaces composed of
two or three plates, of which the first is much the largest. Column
small, round; axial canal narrow, pentangular.

senile y grt tte - etiinin.

MELOCRINID &. aii

Distribution. — Allocrinus is restricted to America. It belongs to a little
group of Crinoids which is sparingly represented in this country, but of which
several genera with a number of species are known to have existed during
the Upper Silurian period in Sweden and England. |

Remarks. -— This genus has close affinities with Patelhocrinus and Dolato-
crinus. It differs, however, from both of them in the form and size of the —
various calyx plates, and in having uniserial arms. It also approaches Cen-
trocrinus, but this has a large and perfectly anchylosed basal disk.

Allocrinus typus W. and Sp.
Plate XXIV. Figs. 7a, 6.
1889. W.and Sp.; Geol. Rep. Illinois, Vol. VIII., p. 207, Plate XIV., Fig. 7.

Below medium size. Calyx depressed, proportionally small, sharply
pentangular in outline, the arm bases projecting, the arms massive and
proportionally stouter than those of any other Crinoid; the plates with-
out ornamentation. Basals small, forming a flattened disk, which is almost
covered by the column; interbasal and basi-radial sutures indistinct. Radials
large, abruptly curved, the lower portions forming the rim of an inverted
shallow basin, the upper half bent abruptly upward and forming together
with the plates above a shallow, spreading cup with straight sides. Costals
and fixed distichals short, curved like arm plates, producing upon the sur-
face of the calyx strong, rounded ridges, which insensibly pass into the free
arms. Arms ten, stout, uniserial, free above the second plate; composed of
transverse joints with parallel upper and lower faces. The arms much wider
midway than at either end, tapering considerably and uniformly toward the
tips, but almost as much toward the calyx. Interradial spaces deeply de-
pressed, composed of two plates vertically arranged, of which the first is the
larger and nodose, and extends to the top of the costals; while the other is
on a level with the fixed brachials, and forms, to some extent, a part of the
ventral surface. Nothing is known of the anal aperture and the structure
of the ventral disk. Column round, small; axial canal pentangular.

Horizon and Locahty. — Niagara group; Wayne and Decatur Cos., Tenn.

Types in the Worthen collection, Springfield, and that of Wachsmuth and
Springer.

308 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Allocrinus Benedicti 8. A. Mizzzr.
Plate XXIV. Figs. Sa, b.
1891. S. A. Mitner; Adv. Sheets 17th Rep. Geol. Surv. Indiana, p. 37, Plate 7, Fig. 1.

Closely resembling the preceding species, but the dorsal cup a little
smaller and less sharply angular, the plates generally more convex, and
the arms not quite so stout. Dorsal cup bowl-shaped, a third wider than
high, the lower end distinctly truncate, the sides convex, the plates elevated
and more or less nodose. |

Basals forming an equilateral pentagonal disk, which has twice the diam-
eter of the column, and occupies the bottom of a shallow concavity ; inter-
basal sutures indistinct. Radials large, curving gradually upwards, their
upper ends at right angles to the lower. Both costals together of about
the size of the radials, wider than long, the sides decidedly beveled and
forming a deep groove toward the interbrachials. First costals quadrangu-
lar, the second pentangular. Distichals one in the calyx, the others free.
Arms ten, so far as observed, moderately heavy ; their plates quadrangular.
Interbrachials one, very large, elongate, and highly convex in the middle,
beveled around the margins. Structure of ventral disk unknown.

Horizon and Locality. — Niagara group; St. Paul, Ind.

CENTROCRINUS W. and Sp.

1881. W. and Sp.; Revision Paleocr , Part IL., p. 104 (Proceed. Acad. Nat. Sci. Phila., p. 278).
Syn. Actinocrinus (in part) Lyon; 1869, Trans. Amer. Philos. Soc., p. 453.

Dorsal cup elongate, plates smooth. Basals represented, by a large
pentagonal disk, showing no traces of suture lines. Radials unusually
large, followed by two costals, which are proportionally very small. Dis-
tichals still smaller, taking the form of arm plates. Arm openings large,
directed outward. First interbrachial plates large, followed by two smaller
pieces. All other parts of the calyx unknown. Column very small.

Listribution. — Represented, so far as known, by a single species from

the Hamilton group of America. Centrocrinus tennesseensis Worthen, from -

the Niagara group of Western Tennessee (Geol. Rep. Illinois, Vol. VIII, p.
95, Plate 14, Fig. 1), has infrabasals, and is a totally different thing.
Remarks. —'The name Centrocrinus was previously proposed by the

MELOCRINIDZ. 309

Austins,* who recommended its application for certain species of Platycrinus
with “central valvate unobstrusive mouths, or mouths capable of being
withdrawn into the visceral cup.” Even substituting “anal opening” for
mouth, there is no Platycrinoid to which the above definition is applicable ;
besides the name has never been accepted by any writer, nor was it applied
to any particular species by Austin himself. Centrocrinus, as here defined,
is allied to the Platycrinide in its anchylosed large basal disk and the small
size of its costals, but differs essentially in having two rows of interbrachials
within the limits of the dorsal cup. lLyon’s figures show interbasal sutures,
but they cannot be seen in his specimens.

Centrocrinus pentaspinus (Lyon).
Plate XXV, Figs. 10a, 6, c.

1869. <Actinocrinus pentaspinus — Lyon ; Trans. Amer. Philos. Soc., Vol. XIII, p. 458, Plate 26, Figs. d
1881. oa eae pentaspinus —W. and Sv.; Revision Palzoer., Part II., p. 104 (Proceed. Acad. Nat.
Sci. Phila., p. 279).
Syn. Actinocrinus multicornus Livon; Trans. Amer. Philos. Soc., Vol. XIIt., p- 455, Plate 26, Fig.
e; and Centrocrinus multicornus — W. and Sp. (Revision, Part II., p. 105).

Dorsal cup as wide as high, subcylindrical, flat below, the sides at right
angles to the bottom. Plates without ornamentation, but the radials, and
sometimes the first interbrachials and first costals, armed with a sharp spine,
while the other plates are merely convex. :

Basal disk very large, forming a regular pentagon, whose surface is
covered by a sort of rounded collar, extending over the greater part of the
surface, leaving only the angles free. Radials almost twice as large as the
two costals together, the upper face much narrower than the lower. First
costals quadrangular, half the width of the radials, and less than half their
length; the second costals shorter than the first, pentagonal, with obtuse
upper angle. Distichals two, short, curved like arm plates; the upper ones
excavated to form the arm openings, which are large and arranged in groups
with wide interspaces. Interbrachials four; the first plate large, hexagonal,
rising to the top of the first costals, the lower angle deeply wedged in be-
tween the radials; the two of the second range are followed by a small piece,
resting between the arm bases, Ventral disk, arms and anus unknown.
Column small; axial canal apparently circular.

* Thomas Austin, and Thomas Austin, jun., 1843, Monogr. Ree. and Foss. Crin., p: 6.

310 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Hlorizon and Locality.— Upper Helderberg group; Falls of the Ohio,
near Louisville, Ky.

Zype in the Lyon collection at Jeffersonville, Ind.

ftemarks. — Actinocrinus multicornus Lyon is undoubtedly a mere varia-
tion of this species. The addition of small spinous extensions upon the first
costals and first interbrachials 1s not a sufficient reason for specific distinction.

DOLATOCRINUS Lyov.

1857. Lyon; Geol. Rep. Kentucky, Vol. IIL, p. 482.

1877. S.A. Minter; Cat. Amer. Paleoz. Foss., p. 77.

1881. W. and Sp.; Revision Paleocr., Part II., p. 124 (Proceed. Acad. Nat. Sci. Phila., p. 298).

Syn. Cacabocrinus —Hatu; 1862, 15th Rep. N. Y. State Cab. Nat. Hist., p. 137.

Calyx depressed. Dorsal cup flattened below, sometimes to the full
height of the costals; the plates generally ornamented with radiating
ridges and nodes. Ventral disk but slightly elevated, surmounted by a
large, almost central tube; the interambulacral spaces depressed. Basals
anchylosed, the lines of union obliterated. MRadials large and hexagonal.
Costals two; the first quadrangular, with convex upper and lower faces,
narrower than either radials or second costals, and wider than long; the
upper one pentangular. Distichals two to four in species with only two
primary arms; but when there are additional bifurcations in the calyx there
is but one. Ambulacral openings large, arranged in groups, with wide
interspaces, and directed upwards. Arms biserial, generally bifurcating.
Interbrachials rather numerous, there being generally three ranges. The two
proximal rows consist of a single plate each, of which the first is the largest
plate of the calyx, rising to the top of the first distichals; the upper row
connecting insensibly with the interambulacral plates. The latter plates
consist. in most of the species of a single row of from five to seven rather
large cuneate pieces — the smaller end directed downward — which, except
the three middle ones, are not in contact laterally throughout their full
length, their lower ends being slightly excavated, so as to leave narrow slit-
like openings between the plates, two 1o three to each side of the interradius,
or four to six to the whole area. Some species have two rows of interambu-
lacral plates instead of one, four to six smaller ones being placed beneath the.
others, and the upper margins of these plates are slightly pierced by the
lower ends of the slits. Above the interdistichal areas, there are rarely more
than two slits, and not exceeding four. In the dorsal cup, the arrangement

MELOCRINID &. 311

of the interradial plates is invariably the same at all sides, but at the anal
side the ventral disk has a few additional pieces, and the plates pierced by
the slits are shorter. The disk contains large orals, pushed anteriorly by
the stout, almost central anal tube, and it has well defined radial dome
plates of a first and second order.. Ambulacra subtegminal. Column large,
round ; the sides covered in some of the species by large angular processes
or ribs; axial canal very large and pentalobate.

Distribution. — Restricted to the Upper Helderberg and Hamilton groups
of America.

Type of the genus. — Dolatocrinus lacus Lyon. |

Remarks. — The complete anchylosis of the basals, the large size of the
first interbrachial and its being followed by a single plate, the large anal
tube, and the slit-like openings at the sides of the arms, together with the
perfect symmetry of the dorsal cup, form excellent characters of this genus.

Lyon described the base as composed of five pieces, while Hall mentions
three basals, but the fact is that the sutures are not visible externally in the
specimens. Mr. Victor Lyon, however, sent us a specimen in which the
presence of three plates is indicated at the inner floor, while no suture
lines appear exteriorly. |

The slit-like openings have not been noticed before. We regard them as
analogous to the respiratory pores of Latocrinus, from which, however, they
differ in number, form and arrangement. |

Hall, in 1862, described several species of the type of Dolatocrinus under
Cacabocrinus, a catalogue name of Troost, and among them Cacabocrinus
Troosti and C. lamellosus, of which we have been unable to get authentic
specimens. ‘The descriptions are too general for specific identification.

Dolatocrinus lacus Lyon.
Plate XXVI. Figs. Ga-c.

1857. Lyon; Geol. Rep. Kentucky, Vol. IIT., p. 482, Plate 4, Figs. 2, 2a—c.
1881. W. and Sp.; Revision Paleocr., Part II., p. 126.

Calyx depressed hemispheric, flattened below, somewhat tumid around
the summit. Dorsal cup more than once and a half as wide as high; the
basals and the lower half of the radials deeply incurved, and formed into an
inverted funnel-shaped concavity, which is wider than the column, the latter
touching only the bottom part. The upper half of the radials, and nearly

ee THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the whole of the first costals, spread out horizontally; while the second
costals and distichals turn straight upward. The ornamentation of the dorsal
cup consists of two or three rows of parallel ridges, which pass out from the
_middle of the plates — with or without interruption — to adjoining plates,
so as to form numerous concentric triangles. A more conspicuous ridge
passes up and down the rays. Another, equally prominent, connects the
radials laterally, and forms a pentagon around the basal concavity. The
radials, first costals and first interbrachials are each surmounted by a promi-
nent node, while the plates of the tegmen are covered with small, granular
prominences.

Basals small, almost completely concealed by the column; forming a
conspicuous cone at the inner floor of the calyx. Radials larger than first
and second costals together, their greatest width equal to their length;
their upper lateral faces shorter than the lower. First costals once and
a half as wide as long, the upper and lower faces somewhat convex. Second
costals a little longer and wider than the first. Distichals 2 x 10 in the
calyx; the lower one almost as large as the preceding axillary; the others
small, and supporting the arms of which there are two to the ray. Arm

bases projecting ; the ambulacral openings large. First interbrachials as
| large as the radials and first costals together; they rise to the height of the
first distichals, and are followed*by a single much smaller plate in the second
row, and three still smaller ones above, which support three or four plates
in the disk. Orals and radial dome plates well defined, larger than the inter-
ambulacrals. Anal tube almost central. Column round; the axial canal
large and pentalobate.

Horizon and Locality.— Hamilton group ; in the limestone bed above the
Black Slate ; Louisville, Ky. |

Lype in the Lyon collection at Jeffersonville, Ind.

Dolatocrinus Marshi Lyon.
Plate X XVI. Figs. La, OnGrer

1869. Lyon; Trans. Amer. Philos. Soc., Vol. XIII., p. 461, Plate 27, ee iy Ne Te
1881. W. ad Sp.; Revision Paleocr., Part IT., p. 126.

Calyx of medium size, wider than high. Dorsal cup basin-shaped, the
bottom deeply excavated and truncated to near the top of the second

costals; the sides gently curving upward to about a vertical position; the

Canal A Aare PONE Alay ae

MELOCRINIDZ&. Sis

arm bases slightly projecting and lobed, giving to the cross-section an
obtusely pentagonal outline. Ventral disk low-pyramidal, the interambu-
lacral spaces flat or slightly depressed, and the plates apparently without
ornamentation. In the dorsal cup the plates are traversed by a large num-
ber of very fine radiating ridges, passing from plate to plate, four to five
from each side, which are well defined near the outer margins of the plates,
but become more indistinct along the median portions. Interbrachial plates
a little convex, the plates of the rays from the margin of the basal concavity
to the middle of the second costals surmounted by keel-like, very conspicu-
ous protuberances, which rise from the lateral margins of the plates, at first
very gradually, but near the middle of the plates almost perpendicularly,
forming knife-like edges at the outer end. The ridges are continued upon
the distichals, but above the costals lose their knife-like character.

Basal disk small; restricted to the lower part of the concavity, which is
completely filled by the upper end of the column. Radials a little larger
than the costals, their lateral sloping upper faces considerably shorter than
the corresponding lower. Distichals two— sometimes three—the upper
one short and lunate, supporting the primary arms, two to the ray. First
interbrachial larger than any of the other plates, nearly as wide as long;
followed by a good sized single plate, and this by two ranges of three plates
each, which rest between the arm bases. In the tegmen there are two large
cuneiform plates to each interambulacral space, which are faced by two or
more smaller pieces with four slits. Two similar plates and two slits overlie
the interdistichal spaces. Orals large, pushed anteriorly. Radial dome
plates quite conspicuous; three of them resting within the re-entering angles
of the orals, the two others against the large anal tube.

Horizon and Locality. — Upper Helderberg group; Falls of the Ohio, near
Louisville, Ky. |

Type in the Lyon collection, Jeffersonville, Ind.

Remarks. Lyon described the basals as “horizontally disposed,” and
“not concealed in the pit.” We conclude from his type specimen that he
mistook the extended outer edges of the top stem joint for the margin of the
basal disk, and its nucleus for the column. Another specimen in the Lyon
collection shows the inner floor of the basal disk, which appears to be
tripartite.

40

314 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Dolatocrinus Marshi, var. hamiltonensis W. and Sp.
Plate XXV. Figs. 2a, 0.

A form very similar to D. Marsh occurs in the Hamilton group, which
we distinguish from the typical form as variety hanultonensis. 'The basal con-
cavity is shallower and narrower, the radial ridges knife-like, and occupy the
median line of the plates instead of being keel-shaped and rising gradually
from the outer margins of the plates. The ventral disk is considerably
lower, and but slightly convex; the orals smaller, the posterior one, which
is very short, is placed so as to form at the anterior side the base of the anal
tube. All plates of the disk covered by several well defined tubercles.

Horizon and Localty.—-Wamilton group, Bear grass quarries, Louis-
ville, Ky.

Type in the collection of Mr. Victor W. Lyon, Jeffersonville, Ind.

Dolatocrinus Lyoni W. and Sp. (nov. spec.).

Plate XX V. igs. 6a, b, c, d.

Calyx rather large, considerably wider than high. Dorsal cup more than
twice as wide as high; the basal portions deeply impressed, forming a broad
funnel-shaped cavity which includes one half the radials. The plates above
the first costals curve gradually upwards, and the two upper rows stand at
right angles to the truncated lower part of the calyx. Ventral disk low-
pyramidal, slightly grooved toward the arm bases; the plates flat, covered
with numerous small pustules. The plates of the dorsal cup are grotesquely
ornamented with a variety of prominences and depressions; some of them
elevated into sharp, very conspicuous, transversely rounded nodes, others
sharply pointed ; and from all of them somewhat irregular, subangular ridges
pass out to the margins of the plates, connecting with similar ridges from
adjoining plates. The plates of the rays have no nodes, and but few ridges
proceed upwards; those directed laterally form a well defined pentagon
around the basal concavity. In the upper part of the calyx the nodes cover
the greater part of the plates, and the ridges are merely indicated at their
outer margins.

Basals small, restricted to the bottom part of the cavity. Radials nearly
as large as the two costals together. First costals quadrangular, narrower
than the radials; the second pentangular, supporting upon one side an axil-

MELOCRINID &. Bile)

lary distichal followed by 3 X 2 palmars and two arms, upon the other three
fixed distichals, which support one arm. ‘There are three primary arms, two
and one, to the ray; two of the simple arms facing the anal interradius.
Arm openings directed obliquely upwards, less projecting and smaller than
usual in the genus. Interbrachials: 1, 1, 3, 4; the first large, rather angular
below, broadly truncate above, the upper sides a little wider than the lower ;
the second almost as large as the first, with a long transverse node. The
three plates of the third row much smaller and provided with elongate nodes.
The plates of the fourth row, which occupy the arm regions, are small and
highly convex, their upper faces pierced by the lower part of the slits. The
interambulacral plates consist of five large cuneate plates, of which the three
middle ones are larger than the others; the sides of the outer ones excavated
to form the slits, which are quite large in this species. The anal interradius
has a few additional plates in the disk, which connect with the anal tube.
Interdistichals four to the arm regions, arranged in two rows, followed by
three cuneate interambulacral plates, with two slits, while there are four slits
above the interbrachial spaces. Orals large, all of similar form and size,
surrounded by good sized radial dome plates of a first, second, and third
order. Anal tube almost central, its base formed of rather large convex
plates.

Florizon and Locality. — Upper Helderberg group; Clark Co., Ind.

Types in the collection of Victor W. Lyon, Jeffersonville, Ind.

Remarks. — This species is readily distinguished from all others of this

genus known to us by the grotesque style of its ornamentation.

Dolatocrinus canadensis WHITEAVES.
Plate XXV. Figs. 7a, b.

1887. Cy paee Geol. and Nat. Hist. Surv. Canada; Contrib. to Can. Paleont., Vol. I., p. 99, Plate 12,
gs. 3, 3d.

Of the type of Dolatocrinus Marshi, but with a different arm formula.
Calyx small, much wider than high. Dorsal cup broadly and shallowly
basin-shaped, slightly depressed along the radials, and more conspicuously at
the basals. Ventral disk lower than the dorsal cup; hemispherical; the
central portions slightly tumid. The ornamentation of the dorsal cup con-
sists of numerous parallel ridges, passing out to the sides of the plates, and
meeting those of adjoining ones. The rays along their median lines followed

316 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

by broad, keel-like processes, which form into a knot in the centre of the
radials and second costals. Another prominent ridge runs from the lower
margins of the first interbrachials to the middle of the plates, where it forms
a rather sharp node, from which two branches proceed to the upper lateral
margins. ‘The smaller ridges, of which there are three to four to each side,
are marginal, extending but a short distance into the plates.

Basals small, perfectly anchylosed, surrounded by a circular ridge, and
entirely covered by the column. Radials larger than the costals, hexagonal,
wider than long, widest above the middle and not visible from a side view.
First costals short, quadrangular; the second considerably wider, a little
longer and axillary, giving off to one side an axillary distichal, which sup-
ports a small palmar at each side, and this an arm. The opposite distichal
gives off a single arm from the second plate, thus making three primary arms
to the ray. Arm bases projecting, giving to the calyx, as seen from above,
a pentagonal outline. Structure of the arms unknown. Interbrachials: 1, 1,
_ 3; the first large; the second much wider than high; the middle plate of the
third row comparatively large; the two at the sides as long, but narrower.
Ventral disk composed of but few large plates, which are covered with several
minute pustules of irregular arrangement; the interambulacral spaces
depressed, consisting generally of only two plates, which abut against the
orals. There are no interdistichals. Orals and ambulacral plates arranged
as in the preceding species. Anus subcentral.

Horizon and Locality.— Hamilton group; near Thedford, Ontario.

Type in the Canada Survey Museum at Ottawa.

Remarks. — It is barely possible that Hall’s Cacabocrinus Troosti, from
Western New York, is identical with this species, but it is described with
four primary arms instead of three.

Dolatocrinus triadactylus Barris.
Plate XX VI. Figs 4a-d.

1884. Barris; Proceed. Davenp. Acad. Nat. Sciences, Vol. IV., Plate 2, figs. 5-7.
1885. W. and Sp.; Revision Paleoer., Part IIT., p. 105.

Of medium size. Calyx depressed, a little wider than high. Dorsal cup
broadly basin-shaped; the lower portions truncate to near the top of the
first costals, then curving rapidly upwards, a little constricted below the arm
bases; the basals moderately excavated, and the margin of the cavity

MELOCRINIDZ&. al ae

surrounded by a circular ridge; the arm bases slightly projecting. Surface
covered by numerous angular ridges, which radiate from centre to centre of
the plates, producing various geometrical figures. The ridges connecting.
the radials form a pentagon around the basal pit, which is radially disposed
and of which the sides support five triangles, each one enclosing a smaller
one. The outer triangles, together with the pentagon, form a five-rayed
star, and the spaces between the rays of this star are also formed into tri-
angles, which are followed by other triangles above.

Basals small, resting completely within the columnar depression. Radials
and costals of equal height, but the first costal narrower than the second.
The latter supports at one side an axillary distichal, followed by two small
palmars and two arms, and at the opposite side by two successive distichals and
a single arm, making three arms to the ray. Arms stout, biserial, not bifur-
cating at the lower ends; their upper parts unknown. Arm joints short,
with parallel faces. First interbrachial large, supporting a smaller, sub-
quadrangular plate, and three plates in the third row, which in turn are
followed by five cuneate plates, which extend above the level of the arm
regions. At the four regular sides, the three middle ones of these plates are
considerably larger than the outer ones, and touch the orals; at the anal
side they are followed by a few additional plates, which abut against the
anal tube. Interdistichals small, consisting of three pieces, succeeded by
two interambulacral plates forming two slits. The number of slits at the
interradial spaces cannot be ascertained from the specimens. Ventral disk
slightly tumid; the interambulacral spaces depressed, the plates almost flat,
the orals and radial dome plates, which are somewhat larger, covered with
small but sharp nodes. Anus subcentral; Column round, with crenulated
edges; axillary canal pentangular.

florizon and Locality. — Hamilton group ; Alpena, Mich.

Types in the Museum of the Davenport Academy of Sciences,

Dolatocrinus glyptus (Hatt).
JOH NON OTS Coa

1862. Cacabocrinus glyptus —Hatn; 15th Rep. N. Y. State Cab. Nat. Hist., p. 140.
1881. Dolatocrinus glyptus — W. and Sp.; Revision Paleoer., Part JE oped Dian
Syn. Cacabocrinus glyptus, var. intermedius Hatt; 1881, 15th Reg. Rep. N. Y. State Cab. Nat.
Hist., p. 141.
Syn. Dolatocrinus ornatus Mex; 1871, Proceed. Acad. Nat. Sci. Phila., p. 57.

318 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Larger than any of the preceding species. Calyx depressed-globose,
somewhat flattened to near the top of the radials; rapidly curving above, so
that the walls of the dorsal cup near the arm bases are parallel to those of
the opposite side. Plates ornamented by interrupted ridges or lines of
small nodes, some of them radiating to the angles of the plates, others to the
sides; those passing from the basal pit to the arm bases the strongest and
almost continuous, rising to angular nodes in the centre of each plate. First
interbrachial provided with a strong central tubercle, and the ridges pro-
ceeding from the radials to the first distichals more prominent than the
others. Suture lines slightly channeled.

~ Basal disk comparatively large, the upper angles projecting beyond the
column, the median portions concave, and the cavity surrounded by a cir-
cular rim. MRadials considerably wider than the costals, and also wider than
long. First costals twice as wide as long, the lower faces distinctly convex,
the upper a little concave. Second costals longer than the first, slightly
increasing in width upwards, the sloping upper faces obtusely angular.
Distichals 2 X 2; the first equal to two thirds the size of the axillary costal ;
the two of the second row not more than half the size of the first, and those
ot the second row separated by an interdistichal. Palmars two, short, lunate,
supporting the two primary arms. First interbrachial almost as large as any
two other plates of the calyx, and nearly as wide as long; followed by
a comparatively large hexagonal plate, which supports three others; the
two at the sides elongate and smaller than the middle one. Ventral disk
depressed-pyramidal. Anal tube subcentral, rising gradually from the disk.
fforizon and Locality. — Hamilton group; near Pavilion, Genessee Co.,

N. Y., and Columbus, O.

Type in the American Museum of Natural History, New York.

Kiemarks. — We regard Cacabocrinus glyptus, var. intermedius, described
by Hall, and Dodatocrinus ornatus Meek, as mere variations of D. glyptus, the
specimens only differing a little in the ornamentation. In the typical
D. glyptus, the ridges upon the plates are not continuous, but consist of
irregular series of elongate nodes; while in the specimens of D. glyptus, var.
intermedius they are generally not interrupted. D. ornatus was described by
Meek as coming from the Hamilton group of New York.

MELOCRINID 2. 319

Dolatocrinus liratus (Hatz).
Plate XX VI. Fig. 3.

1862. Cacabocrinus liratus — Wau; 15th Rep. N. Y. State Cab. Nat. Hist., > IssF
1881. Dolatocrinus liratus —W. and Sp.; Revision Paleocr., Part II., p. 126.
Syn. Cacabocrinus liratus, var. multilira — Hatt; 15th Rep. N. Y. State Cab. Nat. Hist., p. 139.

Very closely resembling D. glyptus, and probably a mere variety of that
species. The specimens referred to the latter by Hall are shorter and their
basal portions more depressed, but this may possibly be due to pressure.
They agree in the form and arrangement of the plates, and both have two
primary arms to the ray, a depressed ventral disk, ridges along the ambu-
lacra, and an almost central anal tube. The only perceptible difference is in
the style of ornamentation. The ridges, which in D. glyptus are more or
less interrupted, are continuous in D. hratus. It has, besides, large ridges
radiating from the centre of the plates to each of their angles, and three to
five smaller ridges passing out to the sides, where they join with similar
ridges from adjacent plates. The plates of the ventral disk are densely
crowded with large and small prominences, similar to those found in certain
species of Amphoracrinus.

florizon and Locality. —'The same as the preceding species.

Type in the New York State Cabinet of Natural History at Albany.

Dolatocrinus icosidactylus W. and Sp. (nov. spec.).

Plate XX VI. Figs. dad.

A large and greatly depressed species of the type of D. glyptus, but
readily distinguished by having four instead of two primary arms to the ray.
When not crushed, the calyx to the base of the anal tube only about four
fifths as high as wide, but it appears to be still shorter in the usual preserva-
tion. Dorsal cup twice as high as the tegmen, broadly cup-shaped, flattened
to the top of the costals, and the basals formed into a funnel-shaped cavity,
surrounded by a circular ridge. The median lines along the plates of the
rays to the bases of the arms elevated into prominent ridges, and the middle
of each radial and costal crowned by a small central node. The nodes are
directed longitudinally ; they are in some specimens quite conspicuous, while
the ridges are almost obsolete; in others, however, the ridges are almost as
high as the nodes. Smaller ridges, or more properly speaking, rows of elon-

320 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

gate nodes, radiate from near the middle of the radials and costals to the
larger interbrachials, the latter having generally four such ridges to each
side of the plate, arranged parallel. Toward the upper part of the dorsal
cup the ridges almost disappear, and the plates are simply tumid.

Basal disk depressed funnel-shaped; the outer rim on a level with the
radials; perforated by a large, pentalobate canal with sharp re-entering
angles, which extend deeply inward. Radials larger than the costals, their
length equal to.the width at the lower end; the truncated upper faces con-
cave; the sloping upper faces much shorter than the sloping lower. First
costals subquadrangular, narrower than the radials; upper and lower sides
convex. Second costals very little wider, but considerably longer and pen-
tangular. Distichals 1x10; all axillary; almost as large as the second
costals. Palmars much smaller, the two lower ones, which are short and
lunate, incorporated into the calyx. Arm openings arranged in groups ;
large ; directed obliquely upwards. Primary arms twenty. Interbrachial
spaces wide, the plates arranged: 1, 1, 2; the first larger than the radials;
the second almost as large as the first costals, subquadrangular; the two of
the third row much smaller. Between the arm openings are three to five
minute pieces, which are followed by two large elongate plates in the teg-
men, and several additional plates at the anal side. There are four slits to
each interradial space, and the same number to each interdistichal space.
Ventral disk low-hemispherical, surmounted by a medium sized almost cen-
tral tube; the course of the ambulacra marked by an elevation, the inter-
ambulacral spaces depressed, especially near the outer margin; the plates
completely covered with small pustules of even size. Orals and ambulacral
plates as usual in the genus. Column round, the joints with slightly waving
edges, and rapidly increasing in size downwards; the nodal joints projecting.

Horizon and Locality. — Hamilton group; Louisville, Ky.

Types in the collection of Wachsmuth and Springer, and Victor W. Lyon.

ftemarks. — This species bears some resemblance to “ Cacabocrinus ”
lamellosus Hall; but differs considerably in the form and size of the basal
depression, which in the latter species, according to Hall, is large, sub-
circular, and embraces the basals and one third of the radial plates. It also
occurs at a different geological horizon, - |

MELOCRINID&. 321

Dolatocrinus excavatus W. and Sp. (nov. spec.).

Plate XXV. Fig. 1, and Plate XX VI. Figs. 7 and &.

A very large species. Dorsal cup shallow-basin shaped, three times as
wide as high; the bottom flattened to the top of the costals; the sides
convex, rapidly curving upwards, a little constricted at the arm bases; the
radials formed into a deep, sharply pentangular, funnel-shaped pit, which
penetrates the calyx almost to the height of the arm regions. Surface of
plates — except those in the pit — covered with parallel ridges, radiating
from the centre of the plates to their sides, where they meet with similar
ridges from adjoining plates. In addition to these ridges there are keel-like
projections following the radials and costals, which grow more conspicuous
downward, and at about the top of the radials are produced into a tubercle,
which projects into the funnel-shaped pit, and gives its upper margin a
slightly stellate outline. Occasionally the carinate ridges are continued to
the higher brachials, but, as a rule, they become obsolete above the second
costals. Suture lines slightly grooved. |

Basals elongate; forming together with the radials a highly elevated
inverted cone with a large pentalobate canal. Radials large, once and a half
as long as wide; four fifths of the plates taking part in the pit, the other
fifth bending abruptly outward; upper sloping faces short; the lower faces
equal to one half the greatest width of the plates. First costals small, twice
as wide as long, their upper and lower faces convex. Second costals wider
than long and slightly wider than the first. Distichals four; the first as
large as the two costals together. Arms two to the ray, about equidistant.
First interbrachial slightly curving, larger than the radials and first costals
together, elongate, widest across the middle of the plate; angular at both
ends; the lower end bending inward so as to form a part of the pit. There
are two large plates in the second row, three smaller ones in the third, and
these are succeeded by a row of six elongate pieces in the ventral disk, and
two additional larger plates which abut against the orals. Interdistichals
one or two in the dorsal cup, followed by five or six small pieces in the
tegmen, and a larger one between the secondary radial dome plates. Slits
six to each interradial space, and four to each interdistichal one. Ventral
disk depressed, slightly tumid; the interambulacral spaces flattened, and

sometimes a little depressed, producing indistinct ridges along the ambulacra.
4] awe

o22 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Orals large ; the posterior one small and lunate, owing to the almost central
position of the large anal tube.

Horizon and Locality.— Upper Helderberg; Clark Co., Ind.

Types in the collection of Victor W. Lyon.

Remarks. — Differing from all other known species of this genus in the
great size of the calyx, the form and depth of the basal pit, in having two
secondary interbrachials, and in the number of the slits. The specimen on
Plate XXVI., Fig. 7, exhibiting the inner floor of the disk, is very interest-
ing as showing the communication of the slits with the inner cavity.

Dolatocrinus major W. and Sp. (nov. spec.).
Plate XXV. Fig. 5.

A very large species, in general form resembling the preceding, but with
a shallow basal depression, four arms to the ray, and without surface orna-
mentation. Dorsal cup depressed-bowl]-shaped, almost three times as wide as
high, flattened below; the radials and part of the costals stretched out hori-
zontally ; the basals forming a shallow concavity surrounded by a thickened
rim; the sides gently bending upwards and becoming parallel at the top of
the first distichals. The plates are smooth, with the exception of a small
rounded node upon the two costals; that of the first costal occupying the
upper end of the plate, that of the second the median part. Radials compar-
atively small, considerably wider than long; the upper and lower lateral
faces almost equal; the lower margin thickened and forming a rim around
the basal concavity. First costal as large as the radials; the upper ‘face
decidedly convex, and the lateral ones slightly, but the lower face straight.
Second costal larger than the first, broadly pentangular. Distichals 1 x 10;
large; axillary; supporting two good sized fixed palmars, and these the
free arms. Arms twenty, arranged at almost equal distances around the
calyx. Interbrachial spaces somewhat depressed at their lower ends, and
slightly receding between the arm bases; the first plate large, its upper half
considerably wider than the lower half, its upper face truncate and somewhat
concave. The plate of the second row is approximately as large as the first
costals, but higher than wide and hexagonal; the lower lateral faces parallel,
the upper lateral ones sloping. There are three plates in the third row, and
others above. Interdistichals one. Structure of the ventral disk unknown.
Horizon and Locality. — Upper Helderberg group; Falls of the Ohio.
Type in the collection of Victor W. Lyon.

MELOCRINIDZ. 320

Dolatocrinus speciosus (Hatz).
Plate XXV. Figs. 4a, 0.

1862. Cacabocrinus speciosus — Hauu; 15th Rep. N. Y. State Cab. Nat. Hist., p. 137.
1881. Dolatocrinus speciosus — W. and Sp.; Revision Paleocr., p. 126.

Of the type of D. major, but smaller; the dorsal cup proportionally
higher, and provided with a somewhat deeper basal pit; the radials instead
of being stretched out horizontally, gradually slope toward the basal con-
cavity, without actually forming a part of it. It has but two distichals, and
two arms to the ray instead of four; arranged in pairs with wide interspaces.
Cross-section below the arm regions subpentangular. Plates apparently
without ornamentation, their surfaces slightly convex; the median line of
the plates following the rays gradually rising into a keel-like projection or
carina, which passes up to the bases of the arms. ‘This carina is higher upon
the radials and costals, and thickened at the middle of each plate, where it
is formed into a conspicuous elongate node; the node of the first costals
more prominent than the others. |

Basals small, forming a shallow inverted basin, which is completely filled
by the column. Radials larger than the costals, and about as wide as long.
The first costal narrower and shorter than the second, and quadrangular ;
the second obtusely angular above. Distichals 2 X 10, comparatively large ;
followed by a lunate arm plate. Arm openings two to the ray, directed
obliquely upwards, and those of the same ray packed closely together. First
interbrachial almost as wide as long, with an obtuse lower angle, and its
upper face broadly truncated ; the second about half the size of the first, its
lateral faces parallel. The latter supports three plates, two upon its sloping
lateral sides, and one upon the truncated upper face, which are followed by
a row of interambulacral pieces. The interdistichal spaces contain two
plates. Ventral disk slightly convex, each side containing four interambu-
lacral plates, two of them larger and cuneate, touching the orals, the two
smaller ones abutting against the secondary radial dome plates. The
posterior oral is deeply wedged in between the four others, and considerably
shorter. Anus almost central.

Horizon and Locality. — Upper Helderberg group; Western New York.

The specimen figured is from the collection of Wachsmuth and Springer.

324 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Dolatocrinus tuberculatus W. and Sp. (mov. spec.).
Plate XXV. Fig. 3.

Of the type of D. glyptus Hall, but differing in the style of ornamenta-
tion. Dorsal cup not twice as wide as high; subglobose, slightly depressed
from the middle of the radials downward; central concavity small, elliptical,
formed by the basals only, and completely filled by the upper column joints.
The radials, costals and first interbrachials are each elevated into a large,
very conspicuous tubercle, and the tubercles are connected by well-marked
ridges. There are generally four parallel ridges from the interradial to the
radial nodes, and the same number between the radials and first costals,
which form five sets of four triangles around the column at some distance
from it; those of the same set concentric. The costals are connected with
the first interbrachial by two ridges, while there is but one ridge, but more
prominent, between the distichals. Other ridges connect the distichals with
the higher interbrachials. Basal disk small, almost completely hidden by
the column, and surrounded by a prominent circular rim with small nodes
interradially disposed. Radials large, almost as long as wide, much larger
than the first costals; the second costals higher and wider than the first. |
Distichals apparently two, each one provided with a short node. First inter-
brachial smaller than usual in this genus; followed by a quadrangular plate
in the second row, and three smaller plates above. Nothing is known of
ventral disk and arms.

Horizon and Locality. — Hamilton group; Clark Co., Ind.

Type in the collection of Mr. Victor W. Lyon.

STEREOCRINUS Banrzris.

1878. Barris; Proceed. Davenport Acad. Nat. Sciences, Vol. IL., p. 282.

1881. W. and Sp.; Revision Paleocr. Part IL., p. 126 (Proceed. Acad. Nat. Sciences, Phila., p. 300).

1885. Barris; Proceed. Davenport Acad. Nat. Sciences, Vol. IV., p. 103.

1889. S.A. Mirner; North Amer. Geol. and Paleont., p. 288.

In general form, ornamentation, and the arrangement of plates resem-
bling Dolatocrinus, but having one costal instead of two, and a tripartite
base. Dorsal cup depressed, truncate below. Basal disk small, pentagonal ;
composed of three pieces, of which the suture lines are generally visible.
Radials and costals nearly of equal size; the former hexagonal, the latter
pentagonal and axillary. Distichals two or three, supporting the arms.

MELOCRINIDZ&. B20

Arm openings, so far as observed, two to the ray; arms biserial. Interradial
spaces wide, containing three ranges of plates in the dorsal cup; the first
and second range composed of one plate each; the third of two or three ;
followed by large cuneate plates in the disk. Ventral disk rather flat, the
interambulacral spaces depressed, containing one or more slit-like openings
at each side of the arms. Ambulacra subtegminal, but their course indicated
by elevations upon the disk. Orals large and arranged as in Dolatocrinus.
Anus subcentral, apparently at the upper end of a tube. Column round;
central canal large and pentalobate.

Distribution. -—— This genus has been observed only in Michigan and Iowa.
The typical species came from the Hamilton group; but we have in our
collection a specimen apparently of anotber species, from rocks considered
to be Upper Helderberg, of Waterloo, Iowa; it is not, however, sufficiently
perfect for description.

Stereocrinus triangulatus Barris.
Plate XXV. Figs. Sa, b.

1878. Barris; Proceed. Davenport Acad. Nat. Sciences, Vol. IL, p. 261, Plate 11, Figs. 1, 2.

1881. W.and Sp.; Revision Paleocr., Part II., p. 127.

A rather large species. Dorsal cup shallow-basin shaped, twice as wide
as high; the truncate lower part formed by the basals, radials, the larger
half of the costals, and a large part of the first interbrachials; the lateral walls
of opposite sides nearly parallel; the extreme upper end slightly constricted,
and the interradial spaces a little depressed between the arm bases. Orna-
mentation resembling that of Dolatocrinus triadactylus, the surface being
covered by similar sets of parallel ridges, but less prominent. Only one of
each set passes from centre to centre of the plates, the others being inter-
rupted. By means of these ridges the whole surface of the dorsal cup is
divided up into numerous triangles, each one enclosing one or two smaller
ones. ‘There are five such sets of triangles around the basals, three to each
set, and similar triangles are formed in the upper part of the calyx.

Basals largely projecting beyond the column; central canal large, penta-
lobate. Radials a little larger than the costals, all wider than long. Dis-
tichals 2 X 10; the first rather large; the second short, lunate. Arm bases
projecting, arranged in pairs. Arms two to the ray; their structure un-
known, First interbrachial a little larger than the radials; the second about
half the size of the first, followed by two or three plates in the third row,

BAD THE CRINOIDEA CAMERATA OF NORTH AMERICA.

and a number of small plates in the ventral disk. Disk depressed-hemi-
spheric; the interambulacral spaces nearly on a level with the ambulacra ;
all the plates slightly convex. Anal tube large at the base, and almost
central.

Horizon and Locality. Hamilton group; Davenport, Iowa.

Types in the Museum of the Davenport Academy of Sciences.
| Remarks. — The small specimen which Barris described as variety “ lira-

tus,’ 18 In our opinion not sufficiently distinct for separation, and, it seems to

us, the differences given are readily explained by individual growth.

Stereocrinus Barrisi W. and Spe. (nov. spec.).
Plate XXV. Figs. Ia, b.

Syn. Stereocrinus triangulatus BARRIs (in part).

Of medium size. Calyx more than once and a half as wide as high,
flattened to the top of the radials, and slightly depressed at the basals; the
sides from the middle of the costals rising vertically; lobed at the arm
bases. Ventral disk short, slightly tumid, the interambulacral spaces deeply
depressed so that the ambulacral regions are conspicuously elevated. Plates
of the dorsal cup covered by similar sets of triangles as in the preceding
species, but the ridges forming them more prominent, and there is a node in
the centre of each plate; suture lines difficult to see. The column is sur-
rounded by a strong circular ridge.

Basal disk projecting beyond the column. Radials and costals nearly
equal in size, the former hexagonal, the others heptagonal. Distichals three
in the calyx; the first a third the size of the costals; the second and third
extremely short, the latter facing laterally. First interbrachial very large,
the two of the second row much smaller. Ambulacral openings large, elon-
gate. Respiratory pores four to each interradius, and two above the inter-
distichal spaces. Orals rather large, slightly tumid, pushed to the anterior ;
the posterior one resting against the base of the anal tube, which is almost
central. The plates covering the food grooves small and tuberculiform ; the
interambulacral ones somewhat larger and almost flat. Column small, round;
the axial canal large and pentalobate.

Horizon and Locality. — Hamilton group; Alpena, Mich.

Types in the Museum of the Davenport Academy of Sciences, and in the
collection of Wachsmuth and Springer.

Remarks, — This species has close affinities with the preceding one, and

MELOCRINID &. Soi

Barris apparently regarded the two forms as representing the same species.
However, on examining a large number of specimens of both types, we find
a separation necessary. In S. Garrisi the basal disk is small, extending but
slightly beyond the column, and the facet for the reception of the column is
surrounded by a heavy, circular rim. In S. triangulatus the disk is quite
large, the top stem joint occupying less than half its diameter, and it has no
rim around the facet. The interambulacral spaces of S. Barrisa are much
more depressed, the ambulacra more abruptly protruding, the orals larger,
and the interambulacral plates flat and less numerous.

HADROCRINUS Lyovy.

1869. Lyon; Trans. Amer. Philos. Soc., Vol. XIII, p. 445.
1881. W. and Sp.; Proceed. Acad. Nat. Sci. Phila. p. 8396 (Revision, Part II., p. 222).
1889. 8S. A. Mitter; N. A. Geol. and Paleont., p. 252.

Calyx very large; the dorsal cup saucer-shaped, its lower portions con-
cave. Basals small, completely covered by the column and placed at the
bottom of the cavity ; they are closely anchylosed, and their suture lines are
visible only upon the inner floor. Radials pentangular, the lower half bent
inward, the upper stretched outward. Costals one, pentagonal. Distichals.
and palmars are always represented in the calyx, and sometimes post-palmars ;
each order by two to four successive plates of the same size as the costals;
the uppermost plate excavated to form a facet, which is directed laterally,
and supports the arms. Interbrachials variable in number and irregular in
their arrangement, as large as the adjoining brachials. The anal side may,
or may not have an additional plate in the second row. Interdistichals one
to three, longitudinally arranged, as large as the interbrachials. Structure
of ventral disk, arms and anus unknown, Column very large near the calyx
(Lyon), round, tapering rapidly, and giving off cirri; axial canal circular at
the top of the column, but pentalobate farther down.

Distribution. — Only known from the Upper Helderberg group.

L'ype of the genus. — Hadrocrinus discus Lyon.

ftemarks.— The specimens are all imperfect, and no satisfactory definition
of the genus can be given. It is allied to Stereocrinus in having but one
costal to the ray, but differs essentially in the number and arrangement of
the interbrachials, and in having sometimes an anal plate. Lyon’s descrip-
tion of the column needs confirmation, being made from detached pieces.
His IZ, pentagonus is defined from a single ring of plates, and the species
cannot be recognized,

328 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Hadrocrinus discus Lyon.
dlme XV, tigen 7.

1869. Lyon; Trans. Amer. Philos. Soc., Vol. XIIL., p. 448, Plate 26, fig. a.
1881. W.and Sp.; Revision Paleocr., Part II., p. 222.

A very large species. Dorsal cup flat-saucer-shaped, the radials forming
a shallow concavity, of which the basals occupy the bottom, the radials the
sides. From the top of the radials to the second distichals the plates are
directed horizontally, and from there they proceed slightly upward to near
the arm bases, where they attain again a horizontal position. Plates moder-
ately heavy, apparently without ornamentation; slightly concave, the median
space having a shallow circular pit, sometimes two being placed close to-
gether. Basals not visible in the specimens, and judging from the space
assigned to them, they were unusually small. Radials and costals small in
proportion; the former a little the larger, their lower faces one half the
width of the upper; the upper sloping faces larger than the corresponding
lower ones. Second costals almost regularly pentagonal. Distichals 2 x 10,
larger than the radials, considerably longer than wide; the first hexagonal,
the second pentagonal and axillary. Palmars 4 X 20 in the calyx, the two
lower ones as large as the distichals and of a similar form, the two upper ~
much shorter and slightly curved for the reception. of the arms. Inter-
brachials nine or more, irregularly arranged, all nearly equal and as large as
the distichals. The anal interradius has three plates in the second row, which
are narrower than the two of the other sides. Interdistichals three, longi-
tudinally arranged, elongate, hexagonal, as large as adjoining brachials.
Structure of arms and ventral disk unknown. Columnar facet large, beauti-
fully striated. 3 |

Horizon and Locality.— Upper Helderberg group ; Falls of the Ohio,
near Louisville, Ky.

Types in the Lyon collection.

Hadrocrinus plenissimus Lyon.
Plate XXIV., Figs. 2a, b.

1869. lyon; Trans. Amer. Philos. Soc., Vol. XIII., p. 445, Plate 26, Figs. 2 1-3.
1881. W. and Sp.; Revision Paleoer., Part II., p. 222.

The specimens are fragmentary and crushed, so as to leave some doubt
as to the actual form and size of the calyx, except that it was depressed and

MELOCRINIDZ. 329

extremely large. Lower portions of the dorsal cup to the top of the costals
deeply concave, forming a large inverted cup, which extends deeply into
the cavity of the calyx; the succeeding plates spreading almost horizontally
with a slight upward curvature. The entire surface covered with somewhat
flattened ridges passing from near the centre of the plates to their sides,
where they meet the ridges of adjoming plates. There are from two to four
ridges to each side, but two of them are frequently united in the specimens,
so as to form one larger ridge with a broader surface.

Basals closely united, forming a small inverted cone, which occupies the
bottom of the dorsal cavity and is completely hidden by the column. The
inner or ventral surface of the basals is convex, decidedly wider than the
outer or dorsal surface, and marked by five well defined angular ridges,
radial in position, from which small protuberances pass out and enter the
axial canal, producing the pentalobate outline. Between these ridges and
around the axial canal, there are five shallow circular depressions occupying
two thirds of the basals, which probably lodged the quinquelocular or dorsal
organ. Radials large, somewhat variable in size, about as wide as long; the
lower faces wider than the upper; the upper sloping faces less than one half
the length of the lower ones. Costals pentangular, very much smaller than
the radials, sometimes barely one third their size. First interbrachial rising
to the top of the costals, the two of the second row elongate and but little

smaller; they are followed by other rows, but their arrangement, as well

as that of the higher brachials, cannot be accurately determined from the
specimens.

Horizon and Locality.— Upper Helderberg group; near Jeffersonville,
Ind. ;

Types in the Lyon collection.

fiemarks.— Lyon describes this species as having 2 X 2 “secondary
radials,” and several more “ orders of radials” above, each order represented
by two plates, and he mentions seven to eight “interradials” and two “ in-
teraxillaries.” He also suggested from small detached pieces, which may
possibly belong to a very different form, that this species had from eighty to
one hundred arms; all of which has yet to be confirmed by more perfect
specimens.

42

CALYPTOCRINID.

MONOCYCLIC. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART
OF THE DORSAL CUP. RADIALS: IN CONTACT ALL AROUND. ARMS RESTING IN
COMPARTMENTS, FORMED BY PARTITIONS ATTACHED TO THE TEGMEN, PLATES OF THE

_ CALYX LIMITED TO A DEFINITE NUMBER. DORSAL CUP, EXCEPT THE BASE, PERFECTLY

PENTAMEROUS.
Analysis of the Genera.
Basals 4.
1. Partitions extending to the tips of thearms . .. .. . . . EUCALYPTOCRINUS.
2. Partitions enclosing only the lower portions of thearms . . . . . . CALLICRINUS.

Geological and Geographical Distribution.
Number of known species.

(Open figures indicate American ; those marked (), European.)

ForMATION. CALYPTOCRINIDA.
Approximate
General. American. European Eucalyptocrinus. Callicrinus.
Equivalents.
Deyonian. ela (1)
Upper Silurian. Niagara. ee eee ce) 4 (8)
, 21
Total species 40 | (a9) Wee Ose Moka
Remarks. — Roemer proposed the family name “ Eucalyptocrinide ”

(Lethzea Geognos. (Ausg. 3), 1855, p. 229), which Angelin in 1878 changed
to Calyptocrinide. The latter name was accepted by Zittel, who errone-
ously included with it Lyrtocrinus Hall, which is a dicyclic Crinoid.

The Calyptocrinide agree substantially with the Dolatocrinites section of
the Melocrinidsx in the construction of the dorsal cup, but their basals occupy
the bottom of a deep concavity, and they are remarkable for having the

CALYPTOCRINIDZ. 331

Cs

i irin

He

lf]
Mh

Ant

it

Fre. 14, showing plates of the dorsal cup, the arms and their partitions.
Fig. 15, the calyx in a side view.
Fie. 16, the partition walls of Hucalyptocrinus rosaceus (after Schultze).

=basals; R= Radials; IT=costals; II a acuichale ; tbr = interbrachials; 7d = interdistichals
A=arms; irP = interradial partitions; idP = interdistichal partitions; ¢1 = first ring of plates of the
tegmen ; /2 =the second ring; 73 =the third ring; and ¢4—= the fourth or upper ring of the teemen.

plates limited to a certain number. The dorsal cup is perfectly pentamerous,
the rays being separated by interbrachials of uniform number and size, and
their main divisions by a single large interdistichal. Still more important
from a classificatory point of view is the structure of the ventral disk, which
differs from that of any other known Crinoid, recent or fossil. It is com-
posed of only four rings of large plates of irregular form, of which the two
lower ones completely cover the disk ambulacra, which are subtegminal, the
upper ones forming a long neck ‘or tube enclosing a narrow canal. Not
only do the plates of the disk, like those of the dorsal cup, consist of a defi-
nite number, but they are throughout this family unusually large, and their
arrangement does not appear to be in accordance with the pentamerous

2

332 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

symmetry of the Crinoids generally. . Another most remarkable feature,
which separates this family distinctly from all other Camerata, is the com-
partments enclosing the arms, which are formed by processes or partitions
attached to the outer sides of the disk, and are supported by the inter-
brachials and interdistichals.

The family was restricted to the Upper Silurian, with the exception of
a single species found in the lower Devonian of the Eifel. It was the lead-
ing family of its epoch in the number of species discovered, there being
twenty-one from America, and eighteen from England and Sweden, but only

two genera.
EUCALYPTOCRINUS Gotrpr.

1826. Goupruss; Petref. German., Vol. I., p. 214, and 1838, Nova Acta Leop. Vol. XIX., 1, p. 335.

1841. Mixer; Berl. Akad. d. Wissensch., p. 210.

1841. Hain; Paleont. N. York, Vol. II., p. 207.

1843. Rormer; Rhein. Uebergangsgeb., p. 62, and 1855, Lethaea Geogn. (Ausg. 3), p. 257, and 1860,

Silur. Fauna West. Tenn., p. 48.

1853. De Kontncx and Lenon; Recher. sur les Crinoides du Terr. Carbonifére de la Belgique, p. 74, with
diagram.

1857. Priore; Traité de Paléontologie, Vol. IV., p. 307.

1862. Dusarpin and Hurk; Hist. Nat. des Zooph. Echin., p. 115.

1863. Hatt; Trans. Albany Inst., Vol. IV., p. 197.

1866. ScuHuntze; Monogr. Hchin. Hifl. Kalk., p. 90.

1878. Awncrtin; Iconogr. Crin. Suec., p. 16.

1879. Harn; 28th Rep. New York State Mus. Nat. Hist., (Hd. IT.), p. 141.

1879. Zirren; Handb. der Paleontologie, Vol. I., p. 379.

1885. Quunstept; Handb. d. Petrefactenkunde (Ausg. 3), p. 963.

1885. W. and Sp.; Revision Paleocr., Part III., p. 127 (Proceed. Acad. Nat. Sci. Phila., p. 349).

1889. 8S. A. Mirzur; N. Amer. Geol. and Paleont., p, 248.

Syn. Hypanthocrinus Puiuires, 1839; Murchison’s Silur. System, p. 672, Plate 17, Fig. 3; Zittel,

1879; Angelin, 1878; S. A. Miller, 1880.

Calyx with the arms attached more or less ovate; without the arms
resembling a wine bottle with concave bottom and slender neck; the neck
surrounded by ten longitudinal partitions closed from above, and forming
ten niches or compartments into which the arms, in pairs, and to their full
length, exactly fit. Dorsal cup composed of four basals, five radials, 2 x 5
costals, 2 X 10 distichals, 1 X 20 palmars, 3 X 5 interbrachials, and 1 X 5 inter-
distichals. The basals, which form an inverted funnel-shaped cup, are not
visible from a side view, and the calyx rests upon the edges of the inflected
lower portions of the radials; the plates varying in size, the anterior one
larger than the rest. Axial canal five-rayed, the anterior basal pierced by
two of its rays. First costals quadrangular, the second pentangular unless
the upper angle is truncated by the interdistichal. First distichals larger

CALYPTOCRINID&. 300

than the second. The first palmars support the arms; they are short, trun-
cated at the upper face, and are provided with small muscle plates and
fosse. First interbrachials generally the largest plates of the dorsal cup,
more than twice as large as the two above. The two latter are of about the
same form and size, and are in contact laterally to their full length. They
rise some distance beyond the top of the palmars in square or tapering trun-
cate projections, and jointly form a support for the interradial partitions.
The interdistichals rest either within notches formed by the distichals, or
upon the truncate upper face of the second costals. ‘They resemble in form
the combined upper interbrachials, rise like these to the height of the third
arm plates, and support in a similar manner to the interbrachials @ partition
wall upon their truncate upper faces. The projections between the arm
sockets give to the specimens a very marked aspect, and serve as a reliable’
guide for generic identification in case the ventral structures of the calyx
are not preserved ; in that condition they look like cogs of a wheel.

The tegmen, or part above the dorsal cup, consists of four rings of plates
of peculiar structure. The lower ring is composed of five elongate inter-_
radial pieces which rest upon the projecting upper faces of the interbrachials,
and five plates of similar form and size supported by the interdistichals.
The middle portions of the ten plates extend outward and upward in. form of
knife-like winged processes, of which the upper end rises to near the fourth
row of plates, overlapping the plates of the second and third rows, to the
outer faces of which they are attached by suture. Interposed between these
plates are ten small trigonal pieces, arranged in such a manner that a plate
supported by an interbrachial, and one supported by an interdistichal, always
meet laterally over the top of one of the triangular pieces. The latter plates,
which are somewhat thickened at their median lines, form a sort of subpar-
titions between the arms of the various pairs, without being visible when the
arms are intact. Their edges at both sides, and also those of the larger
plates, are pierced by the ambulacral or arm openings, which are well
defined in this genus, and enter the calyx between the two plates. The
second and third rings, which form the tubular prolongation of the calyx,
are composed of four plates each; the fourth ring consists of ten pieces,
which meet around the summit. The plates of the second ring slope
upwards; two of them are wider, and alternate with the other two; the
two narrower plates are longer, and angular at the top, the others truncate.
United they form an inverted funnel, the margin surrounded by ten protu-

334 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

berances, which represent ten longitudinal ridges upon the outer surface.
The ridges meet the upward prolongations of the plates of the first ring,
with which they are suturally connected and form a solid wall; while the
alternate grooves form the inner part of the niches. The plates of the third
ring are narrower than those of the second, and like them provided with ten
longitudinal elevations, which are overlapped by certain projections passing
down from the plates of the fourth ring. ‘The plates of the upper ring are
quite remarkable as forming the upper part of the anal tube, the top of the
crown, and at the same time the encasement for the tips of the arms. They
are constructed upon a plan similar to that of the large plates of the first
ring, and, like them, have wing-like extensions, which from a ventral aspect
present a well defined decagonal star, with a vacant space at the summit.
The lower ends of these wings meet the upper ends of the wings of the first
ring, so as to form, together with the projecting surfaces upon the plates of
the two middle rings, ten continuous walls, which extend from the edges of
the dorsal cup to the top of the crown. The open space between them
represents the end of the anal canal, which is closed variously by from five
to ten small irregular pieces surrounding the anal opening, and sometimes by
additional larger plates. The anus in some species is drawn out to a tube
of great length, extending far beyond the limits of the arms, but more fre-
‘quently rises but little above the top of the compartments. Arms heavy,
arranged in pairs, each pair occupying one of the ten compartments, their
backs almost even with the edges of the partitions, their lateral faces abut-
ting against the sides. They have a wide ventral furrow, and are composed
from the third or fourth plate up of two rows of short, transverse pieces,
which are so closely united by suture, that the arms must have moved en
masse upon the calyx. Pinnules long and closely folded. The visceral
cavity is formed by the plates of the dorsal cup and the two lower rings of
plates of the disk; the plates of the two upper rings, which form the neck-
like prolongation, being, properly speaking, plates of the anal tube. The
ambulacra, on entering the calyx, follow the grooves at the inner floor, and
meet near the top of the second ring. Column moderately large, generally
round; composed of rather long joints with pentapetalous axial canal. It
has no lateral cirri, but branches at the end into hundreds of little rootlets.

Distribution.-— A leading form of the Upper Silurian, and well repre-
sented in this country as well as in Europe. A single species is known from
the Devonian: Hucalyptocrinus rosaceus from the Eifel of Germany, the type
of the genus.

CALYPTOCRINID&. 33)

Remarks. — Eucalyptocrinus was originally described by Goldfuss as hav-
ing no stem; and Phillips, who discovered another species with the stem
attached, proposed for this the genus Hypanthocrinus. Angelin and Zittel,
who accepted Phillips’ genus, describe its base as less deeply funnel-shaped,
the anal tube as extending beyond the tips of the arms, and the partition
walls enclosing the arms as being constructed principally of one piece.
Neither one of these characters is constant, and we cannot regard the two
forms as distinct generically. That the anal tube rises above the arms is of
very little structural value, if we admit that the neck-like prolongation
from the disk represents a part of that tube. The earlier writers describe
the radials as basals. Roemer discovered the true base in 1843, but he
supposed it was quinque-partite, and so did de Koninck and Le Hon. Hall in
1863 found that it consisted of but four plates, and this was confirmed by
subsequent authors.

Hucalyptocrinus 1s a most perplexing genus, owing to the peculiar struc-
ture of its ventral part, which was apparently not correctly understood by
Hall. He described the partition walls as interbrachials; while in fact they are ©
not separate plates, but the outer processes from the plates of the disk and
tube, respectively, a sort of compound structure for which we adopt the name
“partition walls.” The twenty plates forming the lower ring of the disk we
regard as large interambulacral plates meeting over the ambulacra; but as
to the relations of the plates of the second ring we are somewhat in doubt.
We have suggested in Revision, Part III., p. 132, that they probably repre-
sented four of the orals, and that the fifth was pushed upward, and consti-
tutes a part of the anal tube. This seems not improbable if we consider that
the posterior oral in all Paleeozoic Crinoids is pushed more or less out of
place by the anus; and it may be expected that this was the case to a high
degree in a genus in which the anal tube is large and strictly central.

Miller’s Zucalyptocrinus ellipticus is too young a specimen to determine its
specific relations. A similar specimen from Rochester, N. Y., is figured by us
on Plate LXXXIIL, Fig. 7.

Eucalyptocrinus tennessee, EB. Phillipsi, E'. conicus, E. nashville, E. eatensus,
E. gibbosus, L. lewis, and E. Goldfussi, all of Troost, are mere catalogue names.
i. armosus McChesney is a Siphonocrinus, and EH. cornutus, E. excavatus,
both described by Hall, and £. ramifer of Roemer, have been referred by us
to Callicrinus. |

336 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Kucalyptocrinus celatus (Ha:z).
Plate LXXXITIT. Figs. 5, 6, 7.

1843. Geol. Rep. 4th Distr. N. York, p. 118, Fig. 1, and Paleont. N. Y., p. 210, Plate 47, Figs. 4a, 0, ¢, d.
1885. W. and Sp. Gn part); Revision Paleocr., Part IIL. p. 133.
Not HLucalyptocrinus celatus Haun, 1865, Trans. Albany Inst., p. 226 (Abstr., p. 32), and 20th Rep.
N. Y. State Cab. Nat. Hist., pp. 321 to 329 (second ed., pp. 363-364), and 28th Rep., p. 142,
Plate 16, Figs. 1-10, and Plate 19, Figs. 1-3; also 11th Ann. Geol. Rep. Indiana, p. 274, Plate
15, Fig. 1, Plate 16, Figs. 1-10, Plate 19, Figs. 1-3, all of which we refer to Eucalyptocrinus
Elrodi 8. A. Miller.
Nor Eucalyptocrinus celatus Ronmer; Silur. Fauna West. Tenn., p. 48, Plate 4, Figs. 3a-e=
E.. ventricosus.
Syn. (?) Hucalyptocrinus (Hypanthocrinus) decorus Hau, 1843 (not Murchison, 1839); Geol. Rep.
4th Distr. N. York, p. 113, Figs. 2-3, and 1852, Paleont. N. York, Vol. II., p. 207, Plate 47,
Figs. 1-3, and Plate 85, Fig. 7. 3
Syn. Eucalyptocrinus papulosus Hawi; Paleont. N. York, Vol. IL., p. 211, Plate 47, Figs. 5a, 0.

Of medium size. Length of crown compared with the greatest width at
the arm bases as 3 to 1, and with the height of the dorsal cup as 8 to 2.
The cup subturbinate, uniformly spreading from the middle of the radials to
the arm bases, the bottom part somewhat rounded. The plates of the cup
densely crowded with small pustules of uniform size, and similar pustules, or
small nodes, cover the outer edges of the partition walls to half their height ;
the upper part being marked by indistinct transverse ridges.

Basal concavity small, completely filled by the upper part of the column.
Radials large, wider than long, very slightly inflected, their lower ends thick-
ened by a round, wart-like projection, which is devoid of ornamentation; the
sloping upper faces short; the upper face concave. First costals wider than
long, the sides all convex, the upper face narrower than the lower. Second
costals the size of the first, but pentangular. First distichals smaller than
the costals ; the second smaller than the first. Plates supporting the arms
smail and irregularly quadrangular. First interbrachial very large, longer
than wide, and tapering downward; the two succeeding ones together almost
as large as the first ; they rise to a level with the third arm joints, are wider
at the bottom than at the top, and unite by a vertical suture. The interdis-
tichals rarely touch the axillary costals; they are twice as long as wide, and
one third narrower than both upper interbrachials together. Partition walls
almost as thick at the upper end as at the lower, and distinctly rounded on
the back. Arms tapering upward to fully one half their greatest width.
The four proximal arm plates single and somewhat longer than the others;
the two succeeding ones cuneate, and those above arranged in two series,

which deeply interlock. The arms are covered with transverse rows of elon-

CALYPTOCRINID &. Bod

gate nodes. Anus at the end of a small tube, rising 4 to 5 mm. above the
tips of the arms. Ventral part of the calyx not visible in any of the speci-
mens. Column round, the nodal joints very long and rounded at the outer
margins, the younger joints short and narrow.

Fforizon and Locality. — Niagara group; Lockport and Rochester, N. Y.

Type specimen in American Museum of Natural History, New York.

Remarks. — It is probable that the specimens which Hall referred to
Hucalyptocrinus decorus Phillips, are identical with this species. ‘They cer-
tainly differ essentially from the English species (Plate LX XXII, Fig. 1d),
which is proportionally shorter and stouter, the plates heavier and more con-
vex, the partition walls thinner, the anal tube stronger, and the column
obscurely pentangular instead of round.
~The Waldron specimens with ornamented plates, which Hall identified
with this species, have been referred by us to Hucalyptocrinus Elrodi Miller.

Eucalyptocrinus tuberculatus Minier anp Dver.
Plate LXXXIIT. Figs. &, 9, 10.

1878. Minter and Dyer; Journ. Cincin. Soc. Nat. Hist., Vol. L., p. 36, Plate 2, Figs. 9, 9a.
1885. W. and Sp.; Revision Paleocr., Part III., p. 134.
ia a eal muralis RINGUEBERG ; 1890, Annals N. Y. Acad. Sci., Vol. V., p. 305, Plate

In its general form resembling the preceding species, but differing some-
what in the proportions of the plates. Dorsal cup obconical, nearly as high
as wide, sides slightly convex, the lower end moderately truncated. Plates
a little elevated and covered by numerous tubercles of various size, larger
ones being interspersed between smaller ones; the suture lines distinctly
grooved. Columnar concavity narrow, its depth less than the width; the
basals completely covered by the upper end of the column.

Radials considerably longer than wide, rapidly tapering downward,
rounded at the bottom; the lower end inflected to meet the basals; the
lower face very narrow, equal to one third the width of the upper, which is
rather deeply concave ; the sloping upper faces short. First costals longer
than wide, narrowest at the upper end. Second costals wider than the first,
pentangular or hexangular. First distichals from one third to one half
smaller than the costals; the second barely one third the size of the first;
the arm-bearing palmars very much smaller and triangular. First inter-

brachials elongate, once and a half as long as wide, and nearly as large
43

338 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

as the radials; they are widest next to the intercostal sutures, tapering to
both ends; the lower lateral faces convex, and longer than any of the
others; the upper faces meeting the interbrachials of the second order. The
two latter plates combined are but little smaller than the lower one, their
tips rising conspicuously above the arm facets, and very little truncated.
Interdistichals much smaller than the corresponding interbrachials, their
lower ends touching the costals or resting between the upper sloping
faces of the distichals. The remaining parts of the species are not shown
in the specimens, but it may be suggested from the condition of the inter.
brachials and interdistichals that the partition walls were unusually thin.

Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.,
Lockport, N. Y., and Racine, Wis.

Types in the Museum of Comparative Zodlogy.

Remarks. — Miller and Dyer, in their specific description, after giving
the structure of the brachials, and stating that the first interbrachials are
“nine or ten-sided,’ continue as follows: “This description applies to the
two ten-sided interradials; the other three have only nine sides, as shown
by Plate 2, Fig. 9, and differ in supporting one supraradial instead of two.”
Even if this were true, which is not the case, it would have no specific sig-
nificance, but would only indicate an abnormal condition of that specimen.
By giving the specimen some additional cleaning, we disclosed two distichals
in every ray, all supporting two extremely small palmars, as shown by our
figure (Plate LX XXIII, Fig. 9). The peculiarity that some of the inter-

brachials are nine-sided, is caused by the distichals, which in three of the
rays lean over to one side, so that one of them does not touch the interbrach-

ials. In Miller and Dyer’s second type, Fig. 9a on the same plate, which
we also reproduce (Plate LXXXIII., Fig. 8), the respective plates are all
ten-sided.

We must regard Hucalyptocrinus muralis Ringueberg as specifically iden-
tical with H. twberculatus, until better specimens are found. Of Ringueberg’s
type, which we had for comparison, only the dorsal cup is preserved, and this
is so badly crushed as to give no idea of its actual form. It is quite possible
that the base is somewhat broader than in Miller and Dyer’s types, that the
plates generally are a little more convex, and the tubercles upon the plates
somewhat less prominent, but the proportions of the plates are substantially
the same. Similar variations may be expected in the limits of any species.

CALYPTOCRINID. Daw

Eucalyptocrinus Elrodi S. A. Miter.

(Revised W. and Sp.).
Plate LXXXI. Figs. 7a, b, 5, 9, 10, 11, 12, 13.

1891. §. A. Mittur; Ad. Sheets 17th Rep. Geol. Surv. Indiana, p. 40, Plate 7, Figs. 9, 10.
Syn. Eucalyptocrinus colatus Hatt, 1865 (not 1843) ; Trans. Alb. Inst., p. 226 (Abstr., p. 382);
and (°) 20th Rep. N. Y. State Cab. Nat. Hist., p. 321 (revised edition, p. 363), and 28th Rep.,
p. 142, Plate 16, Figs. 1-10, and Plate 19, Figs. 1-3; also 11th Ann. Geol. Rep. Indiana, p. 274,
Plate 16, Figs. 1-10, and Plate 19, Figs. 1-3.
Syn. Eucalyptocrinus subglobosus 8. A. MituER, 1891, Adv. Sheets 17th Rep. Geol. Surv. Ind., p. 37,
Plate 7, Fig. 3.

Usually a little larger than £. celatus, shorter in proportion, and not
attenuate at the poles. General form from subglobose to ovate, the base
moderately excavated for the reception of the column. Dorsal cup a little
shorter than the height of the partition walls enclosing the arms. The
plates of the dorsal cup, as well as the arms, and also the outer edges of the
partition walls, marked by numerous round or elongate nodes, often two or
three of them confluent and forming straight or vermicular ridges trans-
versely or longitudinally arranged. The nodes upon the arms are in longi-
tudinal rows, there being generally two rows in the upper part of the arms,
and four at the lower end.

Basal concavity small and shallow for the genus, the plates completely
hidden by the column, forming a short cone at the inner floor. Radials mod-
erately large, the lower ends curving abruptly inward, the remaining parts
outward and slightly upward, the lateral faces rapidly tapering, the sloping
upper faces short, and the upper face concave. First costals wider than long,
the sides convex ; the second hexagonal, the upper angle truncated by the
interdistichals. First distichals once and a half as large as the second, and
the latter more than twice as large as the fixed palmars, which are subtri-
gonal. First interbrachial very large, the middle part almost as wide as long,
the upper end broadly truncated by the interbrachials of the second row:
The two latter plates together are longer than wide, having the greatest
width at one third their height, whence they gradually slant to the top,
which is truncate. The interdistichals are of a similar form, but one third
smaller than the two upper interbrachials, and rise, like them, considerably
above the level of the arm bases, each supporting also a partition. The
outer faces of the partitions are fully twice as wide at the lower end as at the
upper, and are slightly grooved. Arms gradually tapering upwards, quite

340 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

narrow at the extremities, composed of very short pieces; the three or four
proximal ones simple, the upper rather deeply interlocking. Ventral disk
minus the partitions comparatively high, owing to the plates of the first row
which are unusually large; the plates of the second row are shallow funnel-
shaped, and those of the third shorter and very heavy. The plates of the
fourth row, which form the upper end of the tube, as well as of the com-
partments, enclose six or eight moderately large plates, and these again
a little short cone of eight or ten irregular pieces, which decrease in size
inward, and close the anus more or less tightly.

FHtorizon and Locahty.— Niagara group; Waldron and Hartsville, Ind.,
and Chicago, Ills.

Types in the State Cabinet of Natural History at Albany.

ftemarks. —'The name Hucalyptocrmus Hlrodi was proposed by Miller for
a specimen from Hartsville, Ind., in which the nodes upon the surface are
exceedingly regular, and not in part confluent as usually in this species,
agreeing in other respects with the specimens from Waldron, which Hall
erroneously referred to £. celatus. The latter species, as represented at
Lockport and Rochester, N. Y., its typical localities, is much more elongate
than the specimens from Indiana; the dorsal cup is higher and obconical, the
radials longer and more nodose at the lower end, the partition walls thinner,
their outer edges convex instead of concave, and there is a small tube rising -
above the walls of the compartments. Whether under these circumstances
it is proper to accept for the typical form Miller's name LZ. Elrodi, which he
separated from it on account of slight modifications in the ornamentation,
may be questioned ; but we propose to do so to avoid further synonomy.
We therefore include in this species not only Miller’s special form, but also
the specimens from Waldron and Hartsville, figured by Hall under Z. ceelatus,
and also Miller’s L. subglobosus, which latter we regard an immature form
of this species.

Eucalyptocrinus ornatus Hatt.

Plate LXX XII. Fig. 10.

1867. Hatn; 20th Rep. N. Y. State Cab. Nat. Hist., p. 329, Plate 1], Figs. 4 and 5.
1885. W.and Sp.; Revision Paleoer., Part IIL, p. 184.
The dorsal cup, the only part known of this species, was described from
internal casts and gutta percha impressions, taken in the natural mould of
the exterior. It is depressed, as wide as high, the radials directed hori-

CALYPTOCRINIDZ.. 841

zontally, except their extreme lower ends, which take part in the basal
concavity. Costals, first distichals and first interbrachials curving rapidly
upwards, so that the sides near the top of the cup are parallel with corre-
sponding parts of the opposite side. Surface of plates, as shown from the
gutta percha impressions, beautifully ornamented with elongate nodes or
ridges passing out from the centres of the plates to their sides, but not con-
tinued to adjoining plates. |

Basal concavity narrow, and moderately deep. The radials rapidly
tapering to their lower ends and rather small, not larger than the second
costals, which are considerably larger than the first. First costals quad-
rangular, once and a half as wide as long; the second hexagonal, being
truncated at the upper end. First distichals about a third smaller than the
upper costals; the second quite small and the palmars still smaller. First
interbrachial larger than the radials, almost as wide as high, those of the
second row together smaller than the first; the interdistichal sub-rhomboidal,
the upper and lower angles truncated. |

Horizon and Locality. — Niagara group; Racine, Wisc., and Chicago, Ills.

Remarks. —The basal concavity in the casts is deeper than it appears
in the gutta percha impressions, and there are shallow grooves passing out
from it in a radial direction, which are not seen upon the impressions, and
give to the cavity in that state of preservation a decidedly pentapetalous
aspect. In specimens in which the plates are but partly dissolved, the sur-
faces generally show concentrating lines around the margins of the plates,
which probably represent mere lines of growth.

Eucalyptocrinus ventricosus W. and Sp. (nov. spec.).
Plate DXXXIIL. Figs. 11 and 12.

Syn. Hucalyptocrinus celatus, Ropmer, 1860 (not Hall 1843); Silur. Fauna West. Tenn,
p. 48, Plate 4, Figs. 3 a-e.

A small species, in its general form subovate, slightly depressed at the
poles, its greatest width a little above the arm bases. Dorsal cup low
saucer-shaped, the sides evenly rounded, its height less than half the length
of the arm compartments; the plates flat or nearly so, marked in well pre-
served specimens by irregular, delicate lines running to the sides, but not
communicating with those of adjacent plates.

Basal concavity narrow and very deep, obscurely pentangular at the

d42 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

outer margin; the basals very small, occupying only the bottom part.
Radials very long, only half their length exposed to view; the attenuate
longer half incurving and forming the sides of the concavity; the exposed
part wider than high. First costals quadrangular, their width once and a
half their length; the second a little larger and hexangular, their upper
angle broadly truncated by the interdistichals. Distichals nearly of equal
size, and almost as large as the axillary costal; the upper angle of the
second so extremely obtuse as to almost form a straight line; the fixed
palmars moderately large and quadrangular. First interbrachial large,
generally as wide as long; the upper part broadly truncated by the two
plates of the upper row, which together are as large as the first, and rise to
the second arm plate. Interdistichal rather narrow and long. Partition
walls narrow, not more than half the width of the arms, except their upper
ends which widen conspicuously toward the summit. Summit somewhat
flattened; the central space closed by a short pyramid of small plates. The
arms rounded on the back, projecting slightly over the sides of the parti-
tions; the three proximal plates single, and higher than the succeeding ones
which deeply interlock.

Horizon and Locality. — Niagara group ; Decatur and Wayne Cos., Tenn.

Lypes in the Museum of Comparative Zodlogy, and in the collection of
Wachsmuth and Springer.

ftemarks. — This species differs from ZH. celatus, to which Roemer
referred it provisionally, by the much more depressed form of the dorsal
cup, the proportionally greater length of the arms, the form and size of the
various plates, and the mode of ornamentation.

Kucalyptocrinus crassus Hatt.
Plate LXXXI. Figs. 1, 2, 3, 4, 8, 6, 14, 18.

1863. Hat; Trans. Albany Inst., Vol. TV., p. 197; also 20th Rep. N. Y. State Cab. Nat. Hist., p. 323,
Plate 11, Figs. 2, 3 (second ed., p. 365); also, 28th Rep. (second ed.), p. 141, Plate 17,
Figs. 1-11, Plate 18, Figs. 1-9, and Plate 19, Figs. 2-5.
1875. (?) Hata and Wurrrrenp; Geol. Surv. Ohio, Paleont., Vol. IT., p- 129, Plate 6, Fie. 11.
1881, Contet; 11th Ann. Rep. of Geol. and Nat. Hist. of Indiana, p. 272, Plate 17, Figs. 1-11, Plate
18, Figs. 1-9, and Plate 19, Figs. 2-5,
Syn. Lucalyptocrinus constrictus, Hatt; ibid., p. 273, Plate 15, ice
Syn. Hucalyptocrinus chicagoensis, WincH. and Marcy; 1865, Mem. Boston Soc. Nat, Hist., p. 90.

A large species; the crown sometimes reaching a length of 10 em. by
6 cm. in width; its length, as a rule, twice the width; the length of the

CALYPTOCRINIDE. 343

dorsal cup to the top of the interbrachials and interdistichals almost equal
to the height of the compartments for the reception of the arms. Dorsal
cup subturbinate, massive, broadly truncate at the lower end, and the
bottom part deeply excavated, the sides straight or a little concave ;
surface of the plates flat and without ornamentation; the suture lines
obscure.

Basals small, at the bottom of a deep, funnel-shaped concavity, and
forming with the inflected lower part of the radials, at the inner floor,
a rather large cone with a pentapetalous axial canal of moderate size.
Radials very large, much longer than wide, forming a broad, slightly
spreading cup, which extends out laterally far beyond the sides of the
column. First costals quadrangular; their length and breadth equal; the
greatest width at the base; the lower and lateral faces convex. Second
costals smaller than the first, generally pentangular, occasionally the upper
angle slightly truncated by the interdistichal. First distichals almost as
large as the axillary costals; the second but one third the size of the first.
First palmars very short and trigonal. First interbrachial almost as large
as the radials; length to width as 5 to 3; its greatest width at the inter-
costal suture line, whence it rapidly tapers to both ends; all sides concave.
The two plates of the second row either separated from the first, or lightly
touching its upper angle, and both together about two thirds the size of the
first; they rise above the arm bases in form of a square projection. ‘The
interdistichal is of a similar form as the two upper interbrachials, but one third
smaller. Ventral disk, deprived of its appendages, pyramidal, the neck-like
upper part proportionally long, widening at the top, the compartments sur-
rounding it deep. These are constructed of the keel-like partitions ascend-
ing from the back of the plates of the first row, and the wing-like extensions
of the upper row, which meet each other at the middle of the third row,
resting with their inner edges against the protruding surfaces of the plates
constituting the second and third rows. The form of the plates of the first
ring, as viewed from the inner cavity, is similar to that of the first inter-
brachials; they are as large, and also attenuate at both ends. The plates
of the second ring, which are quite massive and elongate, form a reversed
funnel with its long tube pointing wpwards; those of the third ring are
short and narrow, and those of the fourth rather long and wider above than
below. The canal within the neck widens toward the extremity, and the

top is closed by a short pyramid of small, irregular pieces surrounding the

344 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

anus, which is generally closed in the specimens. The edges of the partition
walls taper considerably upward, being quite thin above, rather thick below.
Arms flattened at the back, stout, a little tapering at the upper end. They
are composed of extremely short, tranverse pieces, which very slightly
interlock ; the four proximal joints single and resting between the protrud-
ing upper parts of the interbrachials and interdistichals. In very mature
specimens, in which these projections are comparatively longer, they some-
times enclose 5 to 6 joints. Column tapering downward, the joints much
the longest at the upper end; the nodal joints long, and wider than the
intervening younger ones, their outer margins slightly convex; the joints
near the root very short and of uniform size. The root is composed of hun-
dreds of small branchlets, most of which are run out horizontally.

Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.,
Green Co., O., and Chicago, Ills.

Types in the American Museum of Natural History at New York.

fiemarks. — This species is extremely variable in form and proportions,
but, as a rule, the cup in the older specimens is more elongate, and not
unfrequently constricted near the middle, thereby producing a slight con-
cavity at the sides. The base in some specimens is so broad as to give to
the cup a subcylindrical outline. In all specimens, however, the base extends
far out beyond the sides of the stem, and this, together with the unusual
length of the first costals, and the extreme shortness of the arm joints,
distinguishes it readily from all other American species of this genus.

Eucalyptocrinus ovalis (Troost) Hatt.
Plate LXXXIT. Figs. 1, 2, 8, 4, 5, 6.

1849. Eucalyptocrinus ovalis — Troost; Catalogue of Crinoidea.

1874. Hucalyptocrinus ovatus (in error for E. ovalis) —Hatn; first edit. 28th Rep. N. Y. State Mus. Nat.
Hist., Plate 17, Figs. 12 and 18 (the error rectified in the second edit. of the same report in the
explanation of the plates). :

1885. Eucalyptocrinus ovalis —W. and Sr.; Revision Paleocr., Part IIL., p. 184.

A small species. General form ovoid, curving regularly from base to
summit. Height to width as four to three in mature specimens, and six to
five in very small ones. Greatest width a little above the top of the dorsal
cup. Height of the cup, compared with the height of the partition walls, as
two to three. Surface of plates smooth and without ornamentation ; the
suture lines indistinct. |

CALYPTOCRINIDZ. 345

Basal concavity a little wider than the column, and rather deep, the basal
plates occupying almost its whole width. Radials curving abruptly inward
at the lower end, forming a sharp edge at the bottom of the dorsal cup; the
exposed upper part wider than long, and nearly as large as both costals to-
gether. First costals once and a half as wide as long; the second a little
wider and pentangular. First distichals almost as large as the costals, the
second one third smaller, and the arm-bearing palmars about half the size of
the second distichals and pentangular. First interbrachial large, subcircular
in outline though actually decagonal ; it meets the two succeeding plates,
which are as long as the first, and near the lower end almost as wide; the
upper parts tapering rapidly to a rather sharp point, which rises to the height
of the fourth arm pieces. Interdistichal narrower and shorter than the two
upper interbrachials ; the lower end angular and barely touching the upper
angle of the adjoining costal; the projecting upper end narrow and truncate.
Compartments for the reception of the arms deep; the partition walls thin
throughout, their width at the lower end half that of the arms, the outer faces
flat. The summit closed by a small rosette of about eight pieces without
additional plates. Arms very gradually tapering, the outer face slightly
convex ; they are composed of moderately short pieces, which interlock
from the fourth plate. With the exception of the partitions nothing is
known of the construction of the disk. Column round, the nodal joints
high and cylindrical, the younger joints a little narrower; axial canal
pentalobate. :

Horizon and Locality. — Niagara group; Waldron and Hartsville, Ind.

~ Types in the American Museum of Natural History at New York.

Remarks. — This species has such close affinities with /. crassus that it
might be taken for its younger stage; but on close inspection it will be ob-
served that the specimens have all the characteristics of an adult form. The
arms not only are biserial, but their plates are almost transversely arranged.
Moreover, the arms are placed deeply in between the projecting upper ends
of the interbrachials and interdistichals; only in young specimens the tips
are almost on a level with the distal faces of the arm-bearing palmars. It
differs from . crassus in its much smaller size, being only from 12 to 22
mm. in length by from 10 to 15 mm. in width, in the more evenly ovate
form of the crown, in not being truncated at the lower end, and in having
much shorter costals, and proportionally larger and pentangular arm-bearing
palmars.

44

346 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Kucalyptocrinus inconspectus Rineurserc.
Plate LXX XII. Figs. 1 and 2.
1884, Rinevepere ; Proceed. Acad. Nat. Sci. Phila., p. 148, Plate 3, Fig. 5.

Of rather large size. Dorsal cup deep, occupying almost one half of the
length of the crown; semi-ovoid, the sides decidedly convex, rising gradu-
ally to the middle of the second costals, thence almost vertically to the top,
so that the plates at the upper end are parallel to those of the opposite side.
Plates flat— the general curvature excepted — and without ornamentation
or other markings,* the suture lines indistinct. ;

Basal concavity narrow and filled completely by the upper part of the
column. Radials about as long as their width near the top, rapidly tapering
downward, the extreme lower end gently curving inward and taking part in
the columnar concavity; the sloping upper faces very short. First costals
as wide as long, a little narrower at the upper end, the sides slightly convex.
Second costals as long as the first, widest at two thirds their height, some-
times the upper angle slightly touched by the interdistichals. First distichals
a third smaller than the upper costal, the second very small, and the suc-
ceeding palmars still smaller and irregularly pentangular. First interbrachial
extremely large, decagonal, about a third longer than wide, attenuate at
both ends; the two of the second row shorter, and together narrower than
the first, their upper and lower ends forming re-entering angles. The
interdistichal approaching the two upper interbrachials in form, but con-
siderably smaller; its upper end squarely truncated, and rising to the third
arm plate. Partition walls narrower than the arms, and of uniform width
throughout; their outer edges flat at the proximal, and convex at the distal
end. Arms gradually tapering, rounded exteriorly ; the three lower joints
single, and a little longer than the upper, which are extremely short. Struc-
ture of disk and summit unknown. |

Horizon and Locality. —In the white limestone at the upper part of the
Niagara group; Rochester, N. Y.

fiemarks. — Nearest. to F. crassus, but the sides of the dorsal cup dis-
tinctly rounded, the base not truncated, and the basal concavity very much
smaller,

* Ringueberg described the surface as “finely rugose; ruge giving evidence of irregular radiations

from the larger plates.” We have carefully examined his type, but cannot discover any ornamentation; the
roughness upon the surface is evidently caused by weathering.

CALYPTOCRINID. 347

Eucalyptocrinus Lindahli W. & Sp. (nov. spec.).
Plate LXXXIT. Fig. 9.

1892. American Geologist, Vol. X. (September), p. 139.
Syn. Hucalyptocrinus Wortheni 8. A. Mittmr; 1894, Geol. Rep. Ill, Bull. 3, p. 53, Plate 4, Fig. 2.

Above medium size. Most remarkable for its heavy, rounded arms, which
to their full length are elevated prominently above the outer faces of the
partition walls, so that the latter form the bottom of a deep groove. Dorsal
cup semi-globose, its lower concavity not larger than the width of the stem,
and enclosing only the basals, which are hidden from view by a narrow,
round stem. Plates not distinctly ornamented, merely showing a roughened
surface. Suture lines slightly grooved. |

Radials rather large, as long as wide, rapidly sloping to the lower end ;
their lateral faces three times as long as the slanting upper ones; the
superior face concave. First costals quadrangular, smaller than the radi-
als, a little wider than long. Second costals hexangular, wider and longer
than the first; their sloping upper faces longer than any of the others; the
upper angle slightly truncated by the interdistichal. First distichals smaller
than the axillary costals, the second less than half the size of the first, and
subquadrangular. Palmars three in the calyx, transversely arranged, rounded
on the back. First interbrachial ten-sided, as large as the radials, longer
than wide, widest at the middle; the two of the second row nearly three
times as long as wide, rising to the height of the third palmars. The inter-
distichal a little shorter and narrower than the two upper interbrachials com-
bined. The walls forming the compartments taper gradually to near the
upper end, then widening rapidly, and curving abruptly inward so as to form
a flat surface at the summit on a level with the tips of the arms. Arms
rather short, very heavy, almost cylindrical. They rise above the sides of
the partitions much more conspicuously than is known to be the case in
any other species, their tips being lifted out from between them almost
completely.

Horizon and Locahty. — Niagara group; Wayne Co., Tenn.

Type in the Illinois State collection.

The species is named in honor of Dr. Josua Lindahl, the eminent Zodlo-
gist and Director of the State Museum at Springfield.

348 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Eucalyptocrinus magnus WorTHEN.
Plate LXXXII. Figs. 7, 8.

1875. Worrnen; Geol. Rep. Ilinois, Vol. VI., p. 501, Plate 25, Fig, 3.

1885. .W. and Sp. ; Revision Paleocr., Part IIL., p. 183.
Syn. Eucalyptocrinus Gorbyi 8. A. Mittmr; Adv. Sheets 17th Rep. Geol. Surv. Missouri, p. 39,

Plate 7, Figs. 5, 6. |

A large species. Dorsal cup depressed turbinate, height and width about
as seven to ten; the lower end obtusely conical, rapidly spreading from the
top of the radials to the top of the first distichals, then abruptly turning
upwards until at the upper end the sides are parallel with those of the oppo-
site side. The upper interbrachials somewhat depressed, so as to give to the
cup, as seen from above, an. obscurely pentalobate outline. Plates almost
flat; the surface smooth or finely granulose ; suture lines slightly grooved.

Basal concavity narrow, completely filled by the column. Radials, as
exposed to view, wider than long, rapidly spreading upward, their upper
faces twice as wide as the lower. First costals somewhat smaller and quad-
rangular ; the sides slightly convex. Second costals heptangular, wider and
longer than the first ; the sloping upper faces convex and unusually steep ;
the upper angle broadly truncated by the interdistichal. First distichals as
large as the axillary costal ; the second less than half the size of the first;
the arm-bearing palmars trigonal and quite small. First interbrachials the
largest plates of the cup; decagonal, but sub-rhomboidal in outline; the sides
more or less concave. The two plates of the second row together wider than
the first, with re-entering angles at the upper and lower ends. Interdis-
tichals large, elongate, rising to the height of the fifth arm plate, the sides
facing the costals concave, the upper and lower faces broadly truncated. Of
the arms only a few of the lower plates were preserved, which are extremely
short. The partition walls are broken away in the specimens, but were, to
judge from the places for their attachment, unusually heavy.

Horizon and Locality. -—Niagara group; White’s creek, near Nashville,
Tenn., and Decatur and Wayne Cos., Tenn.

Type in the collection of Prof. 8. 8. Gorby.

ftemarks. — This species is most remarkable for its large size, and is
readily distinguished from all other known species by its peculiar form.

CALYPTOCRINID 2. 349

Eucalyptocrinus depressus S. A. Miter.
Plate LXX XIII. Figs. 8, 4a, 4b.

1880. §. A. Mittur; Journ. Cincin. Soc. Nat. Hist., Vol. III, p. 232, Plate 7, Figs. 1, la, 4.

1885. W. and Sp.; Revision Paleocr., Part III., p. 133.

Of moderate size. Crown subcylindrical, twice as high as wide, a little
tapering to the upper end, distinctly flattened and concave at the poles.
Dorsal cup almost twice as wide as high, the upper part of the radials and
the extreme ends of the first interbrachials forming the truncated bottom,
the upper part of the latter and the first costals gently curving upward, the
plates above parallel to those of the opposite side. Plates a little convex,
their surface apparently rugose. Lower concavity deeply and broadly fun-
nel-shaped, the basals constituting but little more than the bottom part.

Radials slightly longer than wide; their upper half more or less hori-
zontal in position, and not visible from a side'view; the lower half forming
the slanting sides of the concavity; their sloping upper faces rather long.
First costals twice as wide as long, a little shorter than the second at the
median line; the upper end of the latter slightly truncated by the inter-
distichal. First distichals about a third smaller than the upper costals; the.
second half the size of the first, their upper angles quite obtuse; the first —
palmars very small and pentangular. First interbrachial subrotundate, as
long as wide, those of the second row as long, but together narrower than
the first, their upper ends rising to the base of the second arm plates. The
interdistichal has almost the form of the two upper interbrachials, but is
somewhat smaller. Partition walls nearly twice as long as the dorsal cup,
moderately thin, the outer edges rounded to near the top, then slightly widen-
ing and curving abruptly inward and somewhat downward, so as to form a
shallow depression around the summit. Their upper ends enclose five rather
large plates with a pentangular open space, the overlying plates being not
preserved in the specimen. The height of the calyx,as observed in the casts,
is about equal to the greatest width across the first distichals, and that of
the dorsal cup equal to that of the tegmen but narrower; the tubular pro-
longation above almost as long as the rest of the calyx, widening at both
ends. Of the arms only the proximal plates are preserved, which are com-
paratively long.

Horizon and Locality.— Niagara group; Cicero and Bridgeport, near
Chicago, Ills.

350 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

Types in the collection of W. C. Egan, Esq., of Chicago.

Remarks. — This species differs from all preceding ones in the depressed
form of the dorsal cup, the width and depth of the basal concavity, and the
position of the radials which are almost at right angles to the plates of the
upper end. It was originally described from natural casts, but Mr. Egan —
has since obtained from the same locality a specimen with the plates intact,

from which our description is made.

Doubtful species described from natural casts.*

Eucalyptocrinus splendidus (Troost) Hann and Warrriexp.

1848. Troost ; List Crin. Tenn., Proceed. Amer. Assoc. Adv. Sci., p. 60 (without description).

1875. Haxn and Wurtrietp: Geol. Surv. of Ohio, Palxont., Vol. II., p. 128, Plate 6, Fig. 12.

Closely allied to the preceding species, and perhaps identical with it.
As in that species, the general form is subcylindrical, flattened at both ends,
the arms are twice as long as the dorsal cup, and the radials are not seen in
a side view, or only their extreme upper ends; the disk, however, to judge
from the cast, is proportionally shorter, and the first costals are higher. The
basal concavity cannot be seen in the specimen, but must have included the
preater part, if not the whole, of the radials. First costals quadrangular,
nearly as long as wide; the apex of the second slightly truncated by the
interdistichal; the distichals considerably smaller than the costals; the first
interbrachial large, a little longer than wide. The proportions of the other
plates indeterminable. Disk hemispherical, the tubular canal in the cast as
long as the rest of the calyx, and funnel-shaped at the upper end.

Horizon and Locality. — Niagara group; Springfield, O.

Type in the collection of Professor Orton.

Eucalyptocrinus rotundus S. A. Mittier.
1882. 5S. A. Mitrer; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 82, Plate 3, Figs. 4 and 4 a, b,c.

Of small size. Crown globose. The inner cavity of the calyx, as seen
in the cast, much wider than high, the canal within the neck wide and of
nearly uniform width. Dorsal cup low-saucer shaped; the basal concavity
small, and apparently filled completely by the upper joints of the column.
Radials wider than long, the upper face concave. First costals twice’ as wide

* We are willing to admit that most of these forms differ specifically from one another, but we are

unable to see how the casts can be satisfactorily compared with species described from the test, especially in
a genus like Hucalyptocrinus in which the differentiations are but very slight.

CALYPTOCRINIDZ&. 351

as long. Second costals about the size of the first, a little higher at the
median line, their upper end slightly truncated by the interdistichal., First
distichals almost as large as the costals. The form of the other plates
-Indeterminable.

Fforizon and Locality.— Niagara group; near Chicago, Ills.

Types in the collection of W. C. Hgan, Hsq., of Chicago.

Remarks. —This may be a small specimen of 4. Hlrodi, with which it
agrees in the general form, and in the proportionate size of the plates.

Eucalyptocrinus turbinatus 8S. A. Miuier.
Plate LXX XII, Fig. 13.
1882. §. A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. V., p. 82, Plate 3, Figs. 5 and 5 a.

A rather large species. In the cast, the calyx is nearly as high as wide,
the dorsal cup obconical, slightly constricted above the radials, the extreme
upper end abruptly curving upwards; the suture lines are defined by angu-
larities, and the inner spaces of the plates are slightly concave. The disk
appears depressed hemispherical, with ten well-marked’ longitudinal ridges
representing the ambulacral grooves. ?

Basal concavity moderately deep and obscurely pentangular. Radials,
as exposed in a side view, comparatively small, wider than long. First
costals quadrangular, nearly as long as wide. Second costals pentangular,
a little larger than the first, the sloping upper sides steep, the upper angle
truncated by the imterdistichal. First distichals as large as the second
costal ; the second much smaller; the palmars minute. First interbrachial
a third longer than wide, barely touching the radials. The two plates above
forming a rhomb with the two acute angles truncated. Interdistichal com-
paratively short. Length of the partition walls, and the neck-like prolonga-
tion of the calyx not known.

Horizon and Locahiy. — Same as last.

Type in the collection of Mr. W. C. Egan.

femarks. — This is probably a good species. Fragmentary specimens
with the plates intact, apparently representing this form, occur in the
Niagara group of Decatur Co., Tenn. The basal concavity 1s narrow, and
the radials have a truncation at the bottom, of which the edges project
rather broadly over the sides of the column. The truncated upper faces
of the interbrachials and interdistichals supporting the partition walls are

302 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

extremely wide, the facets for the reception of the arms are surrounded by
a raised angular edge, and the plates are covered with obscure radiating

ridges or rows of small tubercles.

Eucalyptocrinus Egani 8. A. Mruer.
Plate DXXXIT. Figs. 11 and 12.
1880. 8. A. Minturn; Journ. Cinein. Soc. Nat. Hist., Vol. III., p. 140, Plate 4, Figs. 1 a-c.

A very elongate species. Height and width of calyx as 8 to 5; height
of dorsal cup, compared with the length of the arms, as 2 to 5; the length
of the neck-like prolongation to the tips of the partitions as 8 to 9—all
measurements made from the casts. Dorsal cup a little higher than wide,
obconical, the bottom distinctly truncated and not excavated in the cast,
the sides very slightly convex and projecting conspicuously over the sides
of the disk. Radials nearly as long as wide. The first costals longer than
wide, and narrower above than below; the second of the same length, and
truncated by the interdistichals. Distichals a third smaller than the costals.
First interbrachials almost twice as long as wide, widest at midway. Form
of the remaining plates indeterminable. Ventral disk but slightly tapering,
its upper margin curving abruptly to the base of the neck, which expands
rapidly upwards. It rises apparently far beyond the arms, and tapers in size
as rapidly as it increases below.

Horizon and Locality. — Same as last, and the type specimens in the same
collection.

Eucalyptocrinus proboscidalis S. A. Mizzer.
Plate LXXXII. Fig. 14.
1882. S.A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. V., Plate 9, Fig. 2.

Closely allied to the preceding species, but the calyx, to judge from the
cast, still more elongate, being to the b:se of the neck over twice as long as
wide; the sides of the dorsal cup more convex; the tegmen higher propor-
tionally, less depressed at the top, and more evenly rounded. The neck is
more constricted in the middle, and more expanding at the summit, the tube
succeeding it thicker at the base, and apparently longer, reaching in the
type a length of 43 mm. by 12 mm. in width at the base, and 2 mm. at the
upper end, tapering gradually. The plates of the dorsal cup, so far as
observed, are long, especially the first interbrachials, which are more than

CALYPTOCRINIDZ&. 353

twice as long as wide, occupying fully one half the length of the dorsal cup.
The tube in its free state was covered by large hexagonal plates, very
regularly arranged.
Horizon and Locality. — Niagara group; Pontiac, O. ,
Remarks. — Miller described this species from a plaster cast in the pos-
session of Mr. A. McCord of Oxford, Butler Co., O.

Eucalyptocrinus obconicus Hatt.

Pi Hex. igs Ao.

1867. Harz; 20th Rep. N. Y. State Museum Nat. Hist., p. 323, Plate 11, Fig. 1.
1885. W. and Sp.; Revision Paleocr., Part IIL, p. 1338.

Differing from all other American species of this genus in the arrange-
ment of the basals, which form an obconical cup instead of being placed
within a concavity. Dorsal cup very long, sometimes almost twice as high
as wide, sharply pointed at the lower end, the sides straight to near the top,
where they slightly contract. Radials once and a half as long as wide, but
very little tapering, the sloping upper faces quite small. First costals
quadrangular, as long as wide, the upper face narrower than the lower; the
second costals of about the same size as the first, but pentangular. First
distichals comparatively large, those of the same ray in contact laterally ;
the second very small. First interbrachials nearly twice as long as wide,
widest at midway; the two of the second row shorter. Interdistichals

unusually small, resting upon the sloping upper faces of the first distichals.
All other parts unknown.

Horizon and Locality. — Niagara group; Racine, Wisc., and Chicago, Ills.

CALLICRINUS p’Orsreny.

1850. D’Orsreny (Calliocrinus); Prodréme, Vol. I., p. 45.
1878. Ancextn; Iconogr. Crin. Suec., p. 14.
1879. Zrrret; Handb. d. Paleont., Vol. I., p. 378.
1881. W. and Sp. ; Revision Paleoer., Part III., p. 135 (Proceed. Acad. Nat. Sci. Phila., p. 357).
1890, Riyevesere; Annals N. Y. Acad. Sci., Vol. V., p. 302.
Syn. Eugeniacrinites Histnerr (not J. 8. Miller), 1857, Lethea Suec., p. 86.
Syn. Lucalyptocrinus (in part) Hatt; N. Y. State Mus. Nat. Hist., p. 322 (20th Rep.).

In its general aspect, in the form of the calyx and arrangement of the
plates, closely resembling HLucalyptocrinus. The calyx also has the form of
a wine bottle with long slender neck, and a deep concavity at the bottom ;

but the partition walls, instead of forming closed compartments to the full
45

354 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

length of the arms, rise only to a certain height, and are not closed from
The plates, as a rule, are highly ornamented, strongly nodose, or
The dorsal cup is constructed of the same num-

above.
extended into long spines.
ber of plates, and arranged in exactly the same manner as in Hucalyptocrinus ;
generally, however, the basal concavity is wider, and
only partly filled by the column. In the construction
of the ventral disk also, the two genera have close
affinities; the plates in both forms consist of four
rings, and in both of them the first rmg is composed
of twenty plates, the second and third of four; but
the fourth ring contains but four plates instead of ten, ©
and these have no wing-like extensions at their outer
faces; the upper parts of their arms are free, and rest
directly against the walls of the anal tube. The parti-
tion walls, of which there are twenty in this genus,
are restricted to the plates of the first ring, and rise
but little above their general height, never touching
Five of the partitions

Fie.17. Callicrinus. Side view
of calyx, showing the rudi-
mentary partitions.

1 eo
are eee TP the plates of the second ring.

distichals; 7br = interbrachi-

als; id = interdistichals; irP
= interradial partitions; idP

- = interdistichal partitions ;
ipP = interpalmar partitions;
i=the first or lower ring of
plates in the tegmen, com-
posed of ten large and ten
small subtrigonal pieces; 2 =
the plates of the second ring,
3 = those of the third ring,
4 =the plates of the fourth
ring.

are supported by the interbrachials, five by the inter-
distichals; the remaining ten are interposed between
the ten others, and rest upon the edges of two palmars.
These latter partitions are formed by wing-like exten-
sions from the ten smaller plates of the first ring;
they rise to the same height as the others, and separate
the two arms which in Lucalyptocrinus occupy the

same compartment. The plates of the second and

third rings either are flat, the general curvature excepted, or they show
The
four plates of the upper ring constitute the upper end of the anal tube,
Arms robust throughout,

some inclination to forming faces of attachment for partition walls.

which generally has a quadrangular opening.
closely folded, and composed, from the second or third plate up, of two
The partitions by which they are separated
rarely extend up higher than to one third the length of the arms. Column

rows of transverse pieces.

round; the axial canal of medium size and pentangular.

Distribution. — The greatest number of species occurs in the Upper Silv-
rian of Gotland, and there are one or two at Dudley, England. The genus
is represented in America by four species in the Niagara group.

Callicrinus costatus (Hisinger) is the type of the genus.

CALYPTOCRINID&. 305

Remarks. — Callicrmus is probably the forerunner of Hucalyptocrinus ; it
is built on the same plan, but its family characters were not, as yet, so highly

differentiated as in that genus.

Callicrinus Beachleri W. and Sp.
Plate LXXXITI. Figs. 14a, b.
1892. W.and Sr.; Amer. Geologist, Vol. X. Sept., p. 140.

The calyx has the usual form of the genus. Its height to the base of the
tube one fourth greater than the width at the top of the dorsal cup; the
height of the cup 11 mm., that of the ventral disk 16 mm., and the length of
the partition walls 8mm. Dorsal cup broadly truncated at the base; the
sides almost straight, gradually expanding upwards. The radials and costals
at the surface sharply keel-shaped, especially the former, and the angularity
continued upon the distichals, but without attaming the prominence that it
has at the lower plates; the first interbrachials slightly convex, with a small
tubercle in the centre.

Basals small and nearly of the same size, forming a concavity which is
rather small and shallow for the genus. Radials near the upper end fully as
wide as long, and twice as wide as at the lower part, which curves gently
inward to meet the basals. First costals twice as wide as long; the second,
which are longer and wider, rarely truncated by the interdistichal. First
distichals twice as large as the second, and but little smaller than the upper
costals. The palmars small and pentangular. First imterbrachials longer
than wide, a little smaller than the radials; the two above together nearly |
twice as wide as the first, their upper ends rising to the height of the
second or third arm plates. Interdistichals but little smaller than the upper
interbrachials, and projecting upward in a similar manner. Ventral disk
conical, its sides convex. The ten plates which rest upon the interbrachials
and interdistichals, respectively, and form the compartments for the recep-
tion of a pair of arms, are twice as high as the ten intervening ones, which
rest against the sloping upper faces of the palmars. There are in all twenty
partitions around the disk, and each arm occupies a separate compartment.
The partition walls are moderately thick, and slightly grooved along their
outer faces. ‘The ten larger ones rise to a lével with the upper end of the
first rig of plates in the disk, of which they form wing-like extensions;
they are sabre-shaped and pointed at the ends. The second ring of the disk

356 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

consists of four plates, which are much narrower at the top than at the
bottom, and two of them are narrower than the others. Construction of the
anal tube, its length, and the structure of the arms unknown.

Horizon and Locahty. — Niagara group; St. Paul, Ind.

Type in the collection of Wachsmuth and Springer.

Remarks. —The unique specimen from which the above description is
made, was discovered by Mr. Charles 8. Beachler, a very enthusiastic collec-
tor, in whose honor the species is named. He has since found a second
specimen at the same locality.

Callicrinus acanthinus Rinevesere.
Plate LXXXTUII. Fig. 18.
1890. Rryevesere ; Annals N. York Acad. Sci., Vol. V., p. 302, Plate 3, Figs. 1 and la.

The specimens from which this species was described are quite fragment-
ary, only showing portions of the dorsal cup, and nothing of its super-
structure, but enough is seen to indicate that the species is unlike any other
heretofore described. The dorsal cup evidently was very short, shorter even
than represented in Ringueberg’s restored figure in the Annals, Plate 3,
Fig. 1, the lower ends broadly truncated, and almost as wide at the bottom
as at the top. The cup rests upon the median part of the large radials; the
lower end of the plates curves inward to meet the four basals, and the upper
end abruptly upwards.

The basals, together with the lower part of the radials, form a deep
pentapetalous concavity, which at the inner side of the calyx is represented
by a short cone, rounded at the upper end. First costals twice as wide
as long, the suture lines convex; the second a little longer, their sloping
upper faces at right angles. The first distichals in contact laterally, some-
what smaller than the upper costals, wider than long, the upper face con-
cave; the second much smaller, and the arm-bearing palmars smaller still.
First interbrachials almost as large as the radials, a little longer than wide,
subrotundate in outline; the two plates above elongate, and together much
smaller than the first. The interdistichal very small, resting within a notch
formed by the first distichals. The faces supporting the partition walls
projecting considerably over those supporting the arms. The axillary costals
and first interbrachials are extended into long, rather sharp spines, proceed-
ing from the middle of the plates and directed obliquely upward. In addi-

CALYPTOCRINID.Z2. ? 30

ion to the spines, the plates have strong ridges or angular protuberances
passing out to the sides, where they meet with similar ridges from the
plates below. The radials have six such ridges, one proceeding to the first
costals, one to the basals, two communicate with those of the interbrachials,
and the two remaining ones, which form a well defined pentagon at the
lower margin of the cup, pass out to the adjacent radials. The smaller
plates in the upper part of the dorsal cup are convex, and slightly angular
in the middle.

florizon and Locahty. — Lower limestone of the Niagara group, Lock-
port, N. Y. |

Type in the collection of Dr. E. N. 8. Ringueberg.

fiemarks. — Differing from all other American species in the depressed
form of the dorsal cup, the surface markings of the plates, and in the num-
ber, form, and direction of their spines.

Callicrinus cornutus HALu.
Plate LXX XIII. Figs. 15, 16, 17.

1867. Hucalyptocrinus cornutus — Hatt; 20th Rep. N. Y. State Cab. Nat. Hist., p. 322, Plate 11, Figs.
1882. See idiis cornutus —R. P. WuitrrELD ; Geol. Rep. Wisc., Vol. IV., p. 285, Plate 16, Figs.
1885. (?) ee cornutus — W. and S.; Revision Paleoer., Part III., p. 183.
Syn. Lucalyptocrinus cornutus, var. excavatus Haun; 20th Rep. N. Y. State Cab. Nat. Hist., p. 322,
Plate 11, Figs. 6, 7.

Calyx, as seen from internal casts, more than twice as wide as high, dorsal
cup broadly truncated, and enormously excavated at the bottom, the sides but
very slightly expanding upwards, being almost vertical. The excavation at
the bottom extends to nearly the full width of the cup, and to two thirds its
height; the circumference is sharply pentangular with straight or slightly
re-entering sides, the inner face grooved toward the angles, which are
directed radially. The arrangement of the plates is rarely seen upon the
internal casts, and not much better in the gutta percha impressions from
the exterior. In the latter, however, it appears that the middle of each
radial bears a long spine, which passes outward and slightly upward, and
occupies the lower margin of the cup. From each side of these spines,
strong ridges proceed to the upper lateral margins of the plates, which meet
with similar ridges from the interbrachials. A somewhat larger ridge runs
to the costals, where it divides and sends a branch to the distichals. From

358 THE CRINOIDEA CAMERATA OF NORTH AMERICA.

the lower side of the spine there is but one ridge, which leads to the basals.
The ridges upon the first interbrachials culminate in a sharp node in the
centre.

Basals comparatively small, occupying but half the depth of the con-
cavity. .Radials very large, the lower half curving abruptly inward, and
forming a sharp edge upon which the cup rests. Costals very small, the
two together less than half the size of the radials; the first from two to
three times as wide as long; the second a very little higher and truncated at
the top. Distichals, palmars, and interdistichals very small; the first inter-
brachial unusually large, and as wide as long. Ventral disk stout, and to
the base of the tube twice as high as the dorsal cup; the sides rising verti-
cally to the top of the trigonal plate of the first ring, whence they slope
slightly to the summit of the ten larger ones, and more rapidly to the tube,
which near its base is moderately thick. The ten larger plates of the first
ring are longer than the whole dorsal cup, the intervening trigonal ones but
half as long. The former, as seen from gutta percha impressions, have long
spiniform appendages, which probably resembled those of Callicrinus murchi-
somanus Angelin (Iconogr. Plate 28, Fig. 14); they are a little compressed
at the sides, and are directed upwards and outwards. The trigonal pieces
also rise into spiniform partitions, but these are shorter and smaller gener-
ally. Structure of the arms unknown. 3

Horizon and Locality.— Niagara group ; Racine, Wisc., and Chicago, Ills.

Types in the N. Y. State Cabinet of Natural History at Albany.

ftemarks. — The large collections of Mr. Thomas A. Greene of Milwaukee,
and Mr. W. C. Egan of Chicago, contain a few specimens in which the dor-
sal cup is unusually expanded at the arm bases, less broadly truncated at
the bottom, and the first costals somewhat larger; while otherwise agreeing
with the rest of the specimens. These specimens do not agree with C. cor-
nutus, var. excavatus Hall, which was not accepted by Whitfield, and we think
that both these forms may be regarded as variations of C. cornutus.

(?) Callicrinus ramifer F. Rormer.

1860. Hucalyptocrinus ramifer — Roemer Silur. Fauna West. Tenn., p. 51, Plate 4, Figs. 4a, 0, ¢.
1885. Hucalyptocrinus ramifer — W. and Srv.; Revision Paleocr., Part IIL., p. 134.

This species is only known from the general form of its dorsal cup, and
there is some doubt whether it should be referred to Callicrinus or to a new
genus. It differs from the other species of that genus in the size of its bas-

CALYPTOCRINID&. 359

als, which are largely represented at the outer walls of the dorsal cup; more-
over the orientation of the pentangular basal concavity is reversed, its angles
being directed interradially, while they are radial in C. cornutus and other
species. Dorsal cup nearly as high as wide, the base broadly truncated, its
lower margin a little projecting laterally and forming a sharp edge; the
sides gently curving to near the top, where they slightly contract. The
suture lines are not shown in Roemer’s type, but we can see from a fragmen-
tary specimen in our own collection that the basals are very irregular; three
of them are quadrangular, the fourth pentangular and larger, the latter
broadly truncated and supporting a radial, which is smaller than the others
and slightly convex at the lower face. The other three basals, which rest
each one between two radials, are distinctly angular below. First costals
quadrangular, once and a half as wide as long; the second considerably
larger and pentangular, the distichals arching over its upper angle. First
interbrachial large, decagonal, almost as wide as long. The plates thin, and,
so far as observed, without surface markings, except obscure angularities fol-
lowing the median lines of the radials and brachials, and a small conical
elevation within the middle of the first interbrachial.

Horizon and Locahty. — Niagara group ; Wayne and Decatur Cos., Tenn.

Type in the Mineralogical Museum, at Breslau, Germany.

ftemarks. — If this is a true Callicrinus, it differs from all the other species
of this country, as well as of Europe, in the large size of its basals, which in
no other species are exposed along the sides of the cup.

Mates
We

iy

PUBLICATIONS

OF THE

MUSEUM OF COMPARATIVE ZOOLOGY —

AT HARVARD COLLEGE.

There have been published of the BuLurrins Vols. I. to
XXIX.; of the Memorrs, Vols. I. to XXII.

Vols. XXVIII: and XXX. of the Butuern, and Vols. XIX.
and XXIII. of the Mumoirs, are now in course of publication.

A price list of the publications of the Museum will be sent
on application to the Director of the Museum of Comparative
Zoology, Cambridge, Mass.

ALEXANDER. AGASSIZ, Director.

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