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PALEONTOLOGY:

VOLUME IV, PART I.

CONTAINING DESCRIPTIONS AND FIGURES OF THE FOSSIL BRACHIOPODA

OF THE UPPER HELDERBERG, HAMILTON, PORTAGE AND CHEMUNG GROUPS.

1862-1806.

BY JAMES HALL,

ALBANY, N. Y.

PRINTED BY C. YAN BENTHUYSEN AND SONS.
MARCH, 1867.

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■

TO HIS EXCELLENCY REUBEN E. FENTON,

Governor of the State of M~ew-T@rh,

Sir :

I have the honor to submit to your Excellency Volume IV., Part
I., of the Report upon the Palaeontology of New-York, containing the
descriptions and figures of the Brachiopoda of the Upper Helderberg,
Hamilton, Portage and Chemung groups. The species are illustrated by
figures drawn and engraved from original specimens collected by myself
or under my direction, or those derived from other authentic sources.

. The completion of the printing has been delayed much longer than I
could have anticipated, and the volume should properly have been issued
in the early part of 1865.

The plates of this volume, which number sixty-two, with several
intercalated ones, are not yet completed, and some time will elapse
before they can be finished.

The manuscript, containing descriptions of the Crinoidea, Crustacea,
Gasteropoda, Cephalopoda, etc. of the higher rocks, forming the fifth
volume of the work, was delivered to the custody of the Commissioners
having charge of the work in September of last year.

I have the honor to be,

with great respect,

your obedient servant,

Albany, March. 1867.

JAMES HALL.

CONTENTS OF YOL. IV.

Preface . . . . . ^ . . vii

Introductory remarks upon the Upper Helderberg, Hamilton, Portage and Che¬
mung groups, with list of genera noticed in the volume . 1- 4

Genus Lxngtjla and descriptions of species of the genus . 5 - 15

“ Discina “ “ « . . . 15 - 26

“ Crania “ « “ of the genus. . . . 26- 30

“ Pholidops « “ « “ . . 31-32

“ Orthis “ “ “ « . 33-63

“ Streptorhynchus “ “ “ . . . . 64- 75

“ Strophomena “ “ “ . . . . 76-77

“ Strophodonta “ « « . . . 78-114

“ Chonetes : observations upon and descriptions of species of the genus 115 - 145
“ Productus and Strophalosia : observations upon the genera. ...... 146 - 153

Subgenus Produotella and description of species . 153-185

Genus Spirifera and descriptions of species of the genus . . 186-257

Subgenus A^iboccelia and descriptions of species . . . . . 258 - 262

Genera Cyrtia and Cyrtina : observations upon . 263-265

Descriptions of species of Cyrtina . . . 265-271

Genus Trematospira and descriptions of species . . . 271-276

“ Rhynchospira and description of species . 276-278

“ Nucleospira “ “ . 278-281

“ Athyris and observations upon . 282-285

“ “ descriptions of species of . . . 285 - 294

“ Meristella and observations upon . 295 - 299

“ “ descriptions of species of . 299-

Subgenus Pentagonia. . . . . . . . 309 -

Genus Atrypa and descriptions of species . 312-327

“ Ccelospira and description of species . 328-330

Family Rhynchonellid^e . . 331

Genus Rhynchonella. . . . . 332 - 334

Subgenus Stenocisma . . . 335

« “ descriptions of species . 335 - 354

Genus Leiorhynohus and descriptions of species . 355 - 364

“ Leptoc(ELIA and description of species . 365-366

« Camarophoria “ “ . . . 367-368

Observations on the Genera Pentamerus, Pentamebella, Stricklandinia,

Amphigenia, RensseljERIA, etc. . . . . . 369 - 374

CONTENTS.

vi

Genus Pentamerella and description of species . . . 875 - 879

“ Gtpidula “ « 380-381

“ Amphigenia “ “ . 382 - 884

« Renssel^ria “ “ . . . 385

“ Terebratula “ “ . 386 - 391

“ Crtptonella “ “ . 392 - 398

“ Centronella “ “ 399-404

“ Tropidoleptus “ ‘‘ . . . 404 - 409

« Yitulina “ “ 409-411

PREFACE.

The present volume contains descriptions and figures of all the well
determined species of Brachiopoda of the Upper Helderberg, Hamilton,
Portage and Chemung groups of New- York. Some few extra-limital species
have been introduced in illustration of the character of neighboring but
identical or analogous geological formations, and all these are from well
authenticated positions. In several examples of this kind, the same spe¬
cies has subsequently been obtained within the limits of the State ; and
we have every reason to believe that most of those, until now known
only in Ohio and Canada West, will ultimately be found within the
State of New York. In some instances, forms previously described as
distinct species have been united under a single specific name. It may
perhaps, hereafter be necessary to pursue the same course in regard to
a few other examples, when the collections shall become sufficiently
extensive to enable us to determine the changes produced by physical
conditions, or by the geographical and geological distribution of species.

Although the larger part of the collections used for this volume were
made many years since, much new material has been obtained during the
past few years. The number of new species, however, is not large, and
probably no considerable number will be added to the list of those
already known. These later collections have been of great importance
for the better determination of the geographical distribution of species,
and have confirmed some views on this subject advanced by the author
many years since.

While the calcareous formations carry essentially the same fauna
from Eastern New- York throughout the length of the State, through
Canada West and the State of Ohio, till these limestones disappear
beneath the higher formations on the border of Indiana, we find impor¬
tant changes supervening in the fauna of the sedimentary strata.

viii

PREFACE.

In Eastern New- York, the coarser sediments of the Hamilton group
present proportionally few Brachiopoda ; and in some localities are com¬
paratively barren of all fossils. The Lamellibranchiata, which are the
characteristic fossils of the coarser sediments of this group, gradually
diminish in number as the finer materials supervene, and the addition
of a larger proportion of calcareous matter is accompanied by the advent
of great numbers of Brachiopoda, together with Corals and other fossils
which are unknown in the eastern part of the State. So great is this
change, that were a collection of fossils from the Hamilton group in the
counties of Albany and Schoharie to be compared with a collection from
the same group in Genesee and Erie counties, the number of species com¬
mon to both would be less than has been sometimes indicated as passing
from one geological formation to another.

The same conditions hold true in a more marked degree in the Che¬
mung group, which, in the counties bordering the Hudson river, is
nearly destitute of animal fossils, but contain many plant remains.
Farther to the westward, a few lamellibranchiates and brachiopods
appear, and their number constantly increases to the central counties of
the State, beyond which the Brachiopoda greatly predominate over all
the other organisms. Nor is this all ; not only do the Brachiopoda
increase in number of species and of individuals, but the species are
almost entirely distinct from those in the more eastern localities of the
group. We notice, moreover, that in these western localities within the
State the prevailing fossils present a “carboniferous aspect,” or are of
generic and specific forms much resembling the prevailing fossils of the
acknowledged Carboniferous rocks of the West. We find also among them
a few forms which might readily be mistaken for Carboniferous species ;
and in one or two instances, there is scarcely room for specific separa¬
tion. Here again, in a more emphatic sense, do we find the fauna of the
same physical group of strata so entirely unlike at points three hundred
miles distant, that there are probably no identical species. At the same
time, the entire Chemung fauna of the western counties of New-York
presents more analogy with the fauna of the so-called Carboniferous

PREFACE.

ix

rocks in the West, than it does with that of the strata of the same absolute
age in Eastern New York and in the adjacent portions of Pennsylvania.

Having already, many years since, presented these views, it is not neces¬
sary to go farther into the discussion in this place, but merely to remark
that further observations and the examination of more extensive collections
have confirmed the opinion then expressed, namely, that the distinction
between the Devonian and Carboniferous systems is one of geographical
rather than geological difference.

In the study of the . Brachiopoda, a few changes have been found neces¬
sary, beyond what has already been published in the Annual Reports upon
the State Cabinet; and some additions have been made to our knowledge
of the characters of established genera. In the Genus Chonetes, the
observations first made by Count Keyserling (but subsequently doubted) of
the oblique direction of the tubular spines as they penetrate the substance
of the shell along the cardinal line, have been confirmed.

In the shells of productoid form, which are sometimes referred to
Productus and sometimes to Strophalosia, it has been shown that the narrow
area and other external features of the latter genus are accompanied by
the vascular imprints of the former. The numerous forms of this character
give, to the fauna of the Chemung group, an expression quite similar to
that of some of the Carboniferous rocks of the Mississippi valley.

Some additional knowledge has been obtained, regarding the structure
of the internal spires in the Genera Athyris, Meristella, and allied forms.

It has appeared desirable to separate, under the sub-generic term
Stenocisma, many of the species hitherto referred to Rhynchonella ; and
the Genus Leiorhynchus has been adopted for certain forms heretofore thus
referred.

Under the pentameroid type it has been found necessary to propose, as
distinct genera, Pentamerella, Gypidula, Anastrophia and Amphigenia,

2*

PREFACE.

while the Genus Stricklandinia is retained for certain forms. It is also
proposed to distinguish these allied genera, together with Oamarophoria, as
a family Pentameridas.

The Genus Cryptonella has been sustained by the character of its in¬
ternal loop ; while the strophomenoid form, Tropidoleptus, is found to be
more nearly allied with the Terebratulidse than with any other family of
the Brachiopoda.

Of the genera described or discussed under the several families, nearly
one-half are those which have been proposed from the study of American
species of Brachiopoda, and it is believed that they are well-founded in the
characters of the typical species. In some of the genera here named, much
yet remains to be done in the study of their internal structure, before we
shall be prepared to assert positively their entire characters and relations.

The printing of this volume was begun in 1862 ; but delays beyond the
control of the Author have prevented its appearance until now. The
plates of the volume are still unfinished at this date, and some considerable
time will elapse before their completion. It is hoped that these illustrations
may prove acceptable to the student in Palaeontology. With the exception
of a few plates, the lithography has been executed by Mr. P. J. Swinton,
whose ability and long experience have enabled him to present the work
in a very superior manner. The drawings have been- made with great care
and fidelity by Mr. B. P. Whitfield, who has excelled both in the accurate
delineation of the character and markings of the species, and also in the
preparation of specimens to illustrate the internal structure.

I am greatly indebted to Mr. John Paterson, for his careful supervision
of the volume as it has been passing through the press, and more especially
for his kind attention to this matter during some periods of my personal
absence.

My acknowledgements are due to many gentlemen for the use of
specimens given or loaned to me for study,* while the work has been in
progress, and of some of these, mention has been made in the body of
the work. It is especially gratifying to me to acknowledge the liberality

PREFACE.

of Dr. G. A. Williams, formerly of Hardy county, Virginia, now of Boon-
ville, Missouri ; and of Dr. James Knapp, of Louisville, Kentucky. Dr. C.
Rominger, of Ann Arbor, Michigan, has very liberally given me the use of
many specimens illustrating the internal structure of species ; and he has
placed at my disposal his collection of European and American Brachiopoda
for further use in completing an introduction to the study of American
Palaeozoic Brachiopoda, which is already advanced, and will appear as a
supplement to the present volume. I/have been indebted to Mr. S. S. Lyon,
of Jeffersonville, Indiana, for the means of illustrating the interior of Meris-
tella, (S. G. Pentagonia), as well as for other specimens. I have received
from Mr. 0. H. St. John, of Waterloo, Iowa, interesting specimens of
Brachiopoda, from the Hamilton and Chemung groups of that part of the
country. For the illustration of several forms among the Spiriferid/E, I
have been permitted the use of specimens from the collection of Col. E.
Jewett. From Mr. Joseph Sullivant, of Columbus, Ohio, I have received
specimens from the Corniferous limestone of that vicinity ; and to the late
Dr. Mann, of Milford, Ohio, I have been indebted for many interesting
specimens. Through the kindness of Prof. Wright, of Hamilton and Mr.
J. De Cew, of Cayuga, Canada West, I have received many specimens of
interest from the Corniferous limestone of that region.

It has been to me a great satisfaction, that through many years, I expe¬
rienced the uninterrupted liberality and kind interest of the late Ledyard
Lincklaen, of Cazenovia, whose devotion to geological science never ceased ;
and it is with a sad heart that I here record this memento of one whose
noble manhood was everywhere acknowledged, and whose quiet, but per¬
sistent advocacy of an advancing science, has produced many good and
permanent results, and has exerted an influence not to be forgotten.

March, 1867.

Note. — Iu the earlier pages of this volume, printed in 1862, a few species of the
genera Lingula and Discina were described from the Waverly sandstones of Ohio, there
having been at that time no sufficiently well marked limit established between the western
extension of the Chemung Group and these beds. Farther comparison of species of other
genera led to a doubt of the propriety of uniting these formations on zoological considera¬
tions alone, and some species from the Ohio formation, previously described by me, as well
as others at that time under investigation, were omitted from the volume for this reason.
It is true, however, that certain species found in the Waverly sandstones and associated rocks
of Eastern Ohio, are apparently identical with forms occurring in the Hamilton and Chemung
Groups of New York ; but these are comparatively so few, that their recurrence can only
be regarded as due to a repetition of the same or similar physical conditions in the two or
more epochs.

At a later period, I have compared the molluscan fauna of the Waverly sandstones with
that of some of the conglomerates, at or near the summit of the Chemung Group in Alle¬
gany county, New York, and the adjacent parts of Pennsylvania, which contain numerous
lamellibranchiate shells. But in all these cases a farther investigation has proved the
occurrence of Spirifera Verneuilii, a characteristic fossil of the Chemung Group in the same
association, while the lamellibranchiate forms, with few exceptions, are altogether of distinct
species. In the collections of the Geological survey these fossiliferous conglomerates were
arranged as a part of the Chemung Group, while the coarser non-fossiliferous rocks of sim¬
ilar character in Allegany and Cattaraugus counties were considered as outliers of the car¬
boniferous conglomerate. We have since learned, however, that the conglomerate of the
southwestern counties of the State is a constituent member of the Chemung Group. The
red shaly and arenaceous strata, sometimes observed beneath the conglomerate, are merely
subordinate beds of little significance and in no way related to the red rocks of the Catskill
Group, to which they have sometimes been referred. The red sandstone, or fine conglom¬
erate, sometimes becoming an impure iron ore, which at one time was referred to as the
probable attenuate extension of the red sandstone of Tioga, belongs, for the most part or
entirely, to the Chemung Group.

From late investigations in the Geological Survey of Ohio, Dr. Newberry has shown
that the beds containing Spirifera Verneuilii do actually pass beneath all the strata bearing
the characteristic fossils of the Waverly sandstones, and are separated from them by a
black shale. This position established, puts at rest any doubts as to the relation of these
beds, and until we possessed some ascertained fact of this kind, all discussion upon the ques¬
tion could lead to no definite result.

PALEONTOLOGY OF NEW-IORI.

The descriptions and illustrations of the fossils in the third volume of
this work include those from the Lower Helderberg group and the Ori¬
skany sandstone ; while the first part of the present volume, following
the formations in the ascending order, will embrace the Brachiopoda of
the following rocks and groups :

CHEMUNG GROUP ;

PORTAGE GROUP, The Genesee slate, forming beds of passage;

Cauda-galli grit, which rests upon the
Oriskany sandstone.

The Cauda-galli grit is almost a non-fossiliferous rock ; a few frag¬
ments of plant-like fossils, and the peculiar surface markings of the slaty
laminae, from which the name is derived, being the only objects resem¬
bling organic bodies which have fallen under my observation. A single
specimen of Platyceras, similar to P. tortuosum of the Oriskany sand¬
stone, has been found in this rock.

The passage from the Oriskany sandstone to this “ Grit,” ' or ( as it
usually occurs in many localities) arenaceous shale, or shale, is very
abrupt and strongly defined. The rock itself is usually a dark or nearly
black slaty grit, weathering to a grayish or brownish gray color, with
strong lines of jointing or lamination nearly at right angles to the bed-
[ Paleontology IV.] 1

PALAEONTOLOGY OF NEW-YORK.

9

ding ; and these being often close and well defined, while the lines of
bedding are obscure, give it the appearance of nearly vertical stratifica¬
tion. This character prevails even when distant from any metamorphic
influences. These features distinguish the rock from any other in the
series; and even in its smaller outcrops, the vertical lamination has
been found a valuable guide in its identification.

In the upper part we find a gradual increase of calcareous matter, with
a diminution of the argillaceous material ; and it passes, by almost im¬
perceptible gradations, to the Schoharie grit, which is marked by the
presence of numerous fossils. The upper beds of the Cauda-galli grit, and
also the lower beds of the Schoharie grit, preserve those peculiar mark¬
ings which have been termed Fucoides cauda-galli.

From the base of the Schoharie grit, we begin our investigation among
the fossils. In this rock we find, for the first time, a small number of
species which pass upward through the limestones of the Upper Helder-
berg group, and are more abundant in the Hamilton group (:). At the
same time, also, we find a few species which are apparently identical
with some which we have known in the preceding rocks. These, however,
are so few, and being comparatively rare, the large number of n,ew spe¬
cies of the same genera makes them inconspicuous, and we have essen¬
tially a new fauna.

One of the most marked features of the change of fauna at this period
is the introduction, or appearance for the first time, of numerous species
of the Genera Cyrtoceras, Gyroceras, etc., with strongly lamellose or
fluted surfaces, and which are often ornamented by nodes or spines.
Some of the Orthoceratites are marked by sharp lamellose rings, and
some of the Gasteropoda are spiniferous. The Trilobites of the Genera

(1) Among those which begin their existence in this rock, occurring likewise in the Upper
Helderberg limestones and passing into the Hamilton group, Orthis vanuxemi ?, Streptorhyn-
chus chemungensis , Strophomena demissa, S. perplana — S. crenistria, Spirifera Jimbriata*,
Atrypa impressa =• a variety of the A. reticularis ? while a larger number of species are
common to the grit and to the limestones above.

* Two individuals of this Species have been found in the Oriskany sandstone.

PALEONTOLOGY OF NEW- YORK. 3

Dalmania and Phacops are remarkable for their spiniferous character ;
while the Lichas and Acidaspis, yet known only in fragments, are of
the most extravagant forms of those genera.

Whatever may be the ultimate decision relative to the line of separa¬
tion between Silurian and Devonian systems, the base of the Schoharie
grit offers a much more decided limitation below, than does the Oriskany
sandstone. The new fauna bears less relation to the preceding, and many
of the new types are of a strikingly distinct character. In the Oriskany
sandstone, we have a considerable number of species which first appear
in the Lower Helderberg group ; and the connection between these two
formations is much more intimate than between the Oriskany sandstone
and the Schoharie grit.

Since the faunae of the Schoharie grit and of the succeeding forma¬
tions, more especially as far as the Hamilton group inclusive, have so
many features in common, I have grouped the fossils together, with a
view to a more perfect zoological arrangement ; and, in the first place,
I introduce the Brachiopoda of all these formations, designating under
each description, as well as in the title of the plate, the rock from which
they have been derived.

In arranging the plates, I have followed to some extent the order in
which the fossil genera appeared in time, taking care nevertheless to
preserve the proper zoological arrangement. The following pages, there¬
fore, with the accompanying plates, will present a pretty full illustration
of the Brachiopoda now known in these groups, before named, within
the State of New- York.

I have sometimes found it necessary to go beyond the limits of the
State, to secure specimens fit for the illustration of species known to
occur within its limits ; and a few extra-limital species have been intro¬
duced for the purposes of comparison. In doing this, however, I have
taken great care, as I have always heretofore done, to avoid deriving
specimens from any portion of the country, or any State, where surveys
have been going on, in which a department of palaeontology has been
organized, and whence we might have reasonable expectation of seeing
the fossils described and illustrated.

4

PALEONTOLOGY OP NEW-YORK.

The following list, in the order in which they are described, embraces
all the genera of Brachiopoda at this time known to me in the rocks and
groups previously noticed on the first page, and from which species are
described in this volume.

LINGULA,

DISCtNA,

CRANIA,

PHOLLDOPS,

ORTHIS,

STREPTORHYNCHUS,
STROPHOMENA,
STROPHODONTA,

CHONETES,

PRODUCTUS = PRODUCTELLA,
SPIRIFERA,

CYRTIA and CYRTENA,

TREMATOSPIRA,

RHYNCHOSPIRA,

RETZIA?,

NUCLEOSPIRA,

ATHYRIS,

MERISTA,

*** There are one or two other generi
the list occurring in these formations.

MERISTELLA,

ATRYPA,

CCELOSPIRA,

RHYNCHONELLA,

STENOCISMA,

LEIORHYNCHUS,

LEPTOCCELIA,

CAMAROPHORIA,

PENTAMERUS,

PENTAMERELLA,

GYPIDULA,

AMPHIGENIA,

RENSSELERIA,

TEREBRATULA,

CRYPTONELLA,

CENTRONELLA,

TROPIDOLEPTUS,

YITULINA.

i, which may be ultimately included in

LINGULJE OF THE UPPER HELDERBERG ROCKS.

5

&Jenus Lingula (Bruguiere).

Up to the time of commencing the printing of this volume, I do not
know of more than a single species of Lingula in the Schoharie grit,
and but two in the Upper Helderberg limestone.

' Several species occur in the limestones of the Lower Helderberg group,
and which have been already described ; but none are known to occur
in the Oriskany sandstone, and but three species between that rock and
the Marcellus shale or base of the Hamilton group. Collections of con¬
siderable extent have been made, and Qver a large area of country ; and
judging from these, the shells of this genus were extremely rare in the
early epochs of the Devonian period in this country, ^he species are for
the most part rare in the Hamilton group, so far as my examinatons have
extended, and one only is known to be abundant.

LINGULAE OF THE UPPER HELDERBERG GROUP.

Lingula ceryx (n. s.).

PLATE II.

A single specimen has been obtained, three-fourths of an inch in length
by half an inch in breadth. Yery little of the shell is preserved; merely
sufficient to show that it was marked by fine concentric striae, with the
cardinal margin thickened. The cast has a distinct oval impression a
little above the centre, showing the mark of a muscular callosity at that
point.

This species resembles in form the L. densa of the Hamilton group, but has not
the strong radiating striae of that species, while the subcentral muscular callosity
is also different.

Except that this is the only representative of the genus known to me in the
Schoharie grit, I would not have thought it worth while to designate the species
from a single imperfect specimen.

Geological formation and locality. In the Schoharie grit : near Clarksville,
Albany county, New- York.

6

PALAEONTOLOGY OF NEW-YORK.

Lingula desiderata (n. s.).

PLATE II.

Shell robust, elliptical, convex, tbe width equal to about four-sevenths
of the length, the greatest width being above the middle of the shell.
Surface marked by fine and closely arranged concentric striae; the
interior of the shell, and the cast, showing strong radiating striae.
Length a little less than half an inch.

The specimen is apparently a dorsal valve, which is truncate, and perhaps a
little imperfect at the beak. In its general form it resembles L. ligea, but is wider
above the centre and more convex, while it is larger than any specimens of that
species in the collection. The presence of radiating strise has not been observed
in L. ligea. Other ^specimens are required for a satisfactory determination of its
character.

Geological formation and locality. In the Corniferous limestone of the Upper
Helderberg group, at Lapham’s mill, Ontario county, N. Y.

Lingula issanm (n.s.). •

PLATE II.

Shell somewhat obovate, the cardinal end being narrower and rounded ;
gradually expanding in width for more than two-thirds the length,
becoming slightly narrower below, with the baso-lateral angles very
abruptly rounded : basal margin nearly straight. Surface marked by
fine close concentric strise, which are scarcely elevated above the
smooth glossy surface. Shell thin : valves nearly flat.

One specimen measures three-fourths of an inch in length by half an
inch in its greatest width, while the width one-third the length below
the posterior end is three-eighths of an inch.

Two separate valves are all that have been seen of this species, but it differs
sufficiently from all the others in these strata to be readily recognized, This and
one other are the only species of Lingula, at this time known to me, in the lime¬
stones of the Upper Helderberg group.

The specimens were received from Dr. R. P. Mann, of Milford, Delaware county,
Ohio.

Geological formation and locality. In limestone of the age of the Upper Hel¬
derberg limestone, in Delaware county, Ohio.

LINGULJE OF THE HAMILTON GROUP.

7

LINGUL2E OF THE HAMILTON GROUP,

INCLUDING THE HARCELLUS SHALE.

Lingula exilis.

PLATE I.

Lingula exilis : Hall, Thirteenth Report of. the Regents on the State Cabinet, 1860, p. 76, f. 2.

Shell broad-ovate, moderately convex, length little greater than the
width ; apex obtuse ; cardinal margin obtusely rounded ; sides regu¬
larly curving ; base broadly rounded. Surface lamellose, with irregular
rugae or lines of growth.

The specimens obtained are imperfect at the beak, or in some other part. The
shell is very broad ; and the great width at the apex, and broadly rounded cardi¬
nal extremity, distinguish it from all other forms of the Hamilton group, or of
the rocks of New- York. In the normal condition, the umbo appears to have been
quite prominent ; but the specimens occurring in the thinly laminated strata are
much flattened.

It is associated with Discina and Conularia, similarly with those of the Tren¬
ton group in New-York.

Geological formation and locality. In the Marcellus shale, near Bridgewater ;
and an imperfect specimen has been found in the shales of the central part of the
Hamilton group, in Schoharie county, New-York.

Lingula ligea.

PLATE I.

Lingula ligea : Hall, Thirteenth Report of the Regents on the State Cabinet, I860, p. 76.

Shell narrow elliptical ; length equal to twice the width ; sides regu¬
larly curving; extremities subequal ; margins of the valves thickened.
Surface marked by fine concentric striae, and by a few obscure or obso¬
lete radiating striae. The more convex valve shows, along the inner
margin, a narrow shallow groove as if the edge of the opposite valve
closed just within its margin.

8

PALAEONTOLOGY OP NEW-YORK.

The shell is of more equal width throughout and more symmetrically oval, and
also much larger than the L. sjpatulata of the Genesee slate. It is likewise more
prominent along the centre of the upper half of the shell. One valve (the ventral ?)
appears to have been more convex- than the other.

Geological formations and locality. In the shales of the upper part of the
Hamilton group, on the banks of Seneca lake.

lingula ligea, var.

PLATE II.

The specimens from the lower part of the Portage group are larger
than those from the Hamilton group, and have the sides somewhat
straighter; while the cardinal extremity, is not so rounded, and slopes
in nearly a right line on each side of the beak. The surfaces are not so
well preserved as in those of the Hamilton group. This may ultimately
prove to be a distinct species.

Geological formation and locality. In the arenaceous shales of the Portage
group : at the falls below Trumtmsburgh, New-York.

lingula palaeformis.

PLATE I.

Lingula palceformis : Hail, Thirteenth Report of the Regents on the State Cabinet, p. 76.

Shell broadly subovate ; sides sloping in a nearly straight line from the
beak to half the length of the shell, convex at the umbo and depressed
below, the length a little greater than the greatest width, rapidly
expanding for about two-thirds the length of the shell, below which
it is abruptly rounded : shell thick. Surface marked by strong concen¬
tric lamellose striae, and, in the exfoliated surface, by fine radiating
striae.

This species, in general foTm, resembles the L. sjpatiosa of the Lower Helder-
berg group, but differs conspicuously in the surface striae ; and among a conside¬
rable number of specimens, the dimensions are the same as the specimens figured,
being nearly two-thirds the length of the Lower Helderberg species.

Geological formation and locality. In the shales of the Hamilton group ; asso¬
ciated with numerous known fossils in a loose fragment of rock, found in the
valley south of Cayuga lake.

LINGULJE OF THE HAMILTON GROUP.

S>

Lingula leana ( n. s.).

PLATE II.

Shell robust, ovate, subattenuate towards the beak ; margins gradually
expanding and curving from the beak for about two-thirds the length,
where the shell has its greatest width. Lower half of the shell very
depressed -convex, becoming more convex towards the beak. Shell
comparatively thick, lamellose.

Surface marked by fine concentric strise and faint interrupted radiating
striae, which are more conspicuous and continuous in the exfoliated
shell. The length of an apparently full grown individual is eight-tenths
of an inch, and the greatest width eleven-twentieths of an inch.

This species is conspicuously distinct from any others in the Hamilton and
Chemung groups, except L. palceformis , from which it differs in its greater propor¬
tional length and more attenuate form towards the beak. So far as known to me, it
is a rare species.

Geological formation and locality. In some calcareous layers in the Hamilton
shales, in Bristol, Ontario county, N.Y.

Lingula maida ( n. s.).

PLATE II.

Shell linguiform, elliptical, greatest width a little more than half the
length, narrowing gently towards either extremity, obtusely rounded
and produced below, and more acutely converging towards the beaks.
Surface very gently convex below and a little more convex on the umbo,
marked by fine threadlike strise which are sometimes crowded in fa¬
scicles. No radiating strise are preserved in the specimen.

The specimen described is apparently a ventral valve, and preserves some remains
of the muscular impression. In form it resembles the L. ligea , but is less convex,
and the lower part of the shell is more produced, so that the strise make a more
extended curve than on that species; and they are likewise coarser.

The typical forms of L. ligea are about half an inch in' length and one quarter of
an inch in width; and the L. maida has a length of more than three-fourths of an
inch, with a width of nearly half an inch.

Geological formation and locality. In the Moscow shales of the Hamilton group :
at Moscow, N.Y.

[ Paleontology IV.] 2

PALAEONTOLOGY OF NEW-YOKK.

Lingula punctata ( n. s.).

PLATE I.

Shell subelliptical, length and breadth as three to two ; sides parallel ;
base subtruncate ; cardinal slopes abrupt, and but little curved ; um-
bones prominent, somewhat flattened in the middle below the longitu¬
dinal centre, the flattened space expanding towards the base. Ventral
valve a little more convex than the opposite.

Surface marked by concentric wrinkles ; the entire structure punctate
or subpunctate, sometimes corrugate, with extremely fine strise. Mus¬
cular impressions, in the cast or partially exfoliated shell, subcordate
below, with numerous diverging foliate imprints above.

The length of the shell varies in different individuals from one-half to three-
fourths or even seven-eighths of an inch, and the width of the larger specimens is
half an inch. The surface marking is peculiar and characteristic, the apparent
punctate structure being caused by two sets of concentric or irregularly wrinkled
strise, leaving minute pits between them. In this character, which is preserved more
or less even upon the casts or exfoliated surfaces, the species is readily identified.

It resembles in general form the L. rectilateris of the Lower Helderberg group,
but is less rounded on the cardinal slopes and less convex on the lower half of the
shell, while the base is much more abruptly truncate.

Geological formation and locality. In the shales of the Hamilton group : Mon-
teith’s Point, on Canandaigua lake; and near Summit in Schoharie county, N.Y.

Lingula uuda ( n. s.).

PLATE II.

Shell subelliptical ; length nearly twice as great as the width ; sides
subparallel, very slightly curving, the greatest width near the centre ;
base truncated ; cardinal slopes rounded, the ventral valve a little
more pointed and more convex than the dorsal valve. Dorsal valve
nearly flat. Ventral valve, in exfoliated specimens, marked by a de¬
pressed line down the centre, with indications of foliate muscular
impressions upon each side. Surface marked by fine concentric striae,
which, on the margins, are crowded and wrinkled.

LINGULAE OF THE HAMILTON GROUP.

11

This shell resembles L. punctata in form, but is proportionally narrower : it is
truncate in front in the same manner; the umbo is a little narrower, and it has not
the flattened space below the middle so distinctly indicated. The surface marking,
however, is always a more distinctive character. The largest specimen examined,
little exceeds half an inch in length.

Geological formation and locality. In the shales of the Hamilton group, asso¬
ciated with L. punctata : near Monteith’s Point, on Canandaigua lake.

Lingula densa ( n. s.).

PLATE II.

Shell subelliptical ; sides almost exactly parallel for more than half the
length of the shell, abruptly curved at the basal angles, and the base
nearly straight or slightly curving ; cardinal margins gently curving.
Middle and upper part of the shell prominent and rounded ; one valve
.(ventral?) showing a slight longitudinal depression when exfoliated,
with fine wrinkled muscular impressions. Yalves somewhat abruptly
flattened and compressed below the middle.

Shell comparatively thick, compact, and very closely and finely striated
concentrically, with undulating striae, the exfoliated shells showing
radiating striae.

This species has nearly the same form as L. punctata , but is more robust and more
abruptly elevated along the middle of the upper half of the valve : the flattening
is only near the lower extremity, and does not extend upwards in a triangular form
as in that species. The absence of puncta, and the close scarcely elevated fine striee,
are distinguishing features.

Geological formation and locality. In the upper part of the Hamilton group,
near Summit, Schoharie county; occurring in large numbers in some semi-arenaceous
layers on the small stream flowing in a gorge known as “ Bear Gulf.”

PALAEONTOLOGY OF NEW- YORK.

12

Lingula della ( n. s.).

PLATE II.

Shell elliptical, twice as long as wide ; sides gently curving ; base very
regularly rounded ; cardinal slopes abrupt, nearly straight : substance
of the shell very thin. Surface marked by extremely fine concentric
striae, and, below the centre of the shell, by numerous undulations,
which are stronger on the middle and become obsolete on the sides.

In the ventral? valves, a strongly impressed linear indentation marks the
centre of the shell from near the beak more than halfway to the base.
This feature is observed in the best preserved specimens seen, as well
as in partial casts. An apparently adult specimen measures nine-tenths
of an inch in length, and five-tenths in the greatest breadth.

This species differs conspicuously from all others of the Hamilton and Chemung
groups, except the L. maida , which is proportionally shorter, with more attenuate
cardinal extremity and stronger surface strise.

In general form, this species bears some resemblance to Lingula ovata of McCoy
(British Paleeozoic Fossils, PI. 1 L, f. 6), having the same slender form; but the
sides are not so straight, and the front is more curved. It has not, however, the
robust form of that species as represented in figure 1, Plate hi, of the Synopsis of
the Palaeozoic Fossils of Ireland.

Geological formation and locality. In the shales of the upper part of the Hamil¬
ton group, near Canandaigua lake.

Lingula alveata ( n. s.).

PLATE II.

Shell subelliptical ; sides curving, broader below the middle, somewhat
abruptly expanding and curving from the beak for more than one-third
the length of the shell.

Two separate valves examined (one of them a cast), are flat, and have a
somewhat elevated or thickened border, extending from the beak,

LINGULyE OP THE HAMILTON GROUP.

13

within which is a distinct groove nearly parallel with the margin an d
reaching half the length of the shell : the centre is marked by a longi¬
tudinal linear impression for more than half its length ; and the cast
of one specimen preserves the mark of a thin septum, which extends
from just beneath the beak three-fourths the length of the shell.

One specimen is nearly an inch and a half long, and the other one inch and one-
eighth. The thickened border and thin median septum are distinguishing features.

There are some peculiarities in these specimens, which lead me to suppose that
a full knowledge of their characters and interior structure may authorise their
separation from the ordinary forms of Lingula.

Geological formation and locality. In the shales of the Hamilton group, Ludlow-
ville, Cayuga county; and in a sandstone near Fultonham, Schoharie county.

lingula spatulata.

PLATE I.

Lingula spatulata : Geological Reports of the Third and Fourth Districts, N.Y., 1842 8t 1843.

Shell small, subspatulate or subelliptical, moderately convex, attenuate
towards the beak, the ventral valve being more acute ; greatest width
across the middle of the shell ; length (which is scarcely three-tenths
of an inch) about twice as great as the width. Surface marked by fine
concentric striae, and, in the exfoliated shell, by faint radiating striae.

This little shell, without any very conspicuous features, is usually recognized
without difficulty by its small spatulate form. It is frequently abundant in the Ge¬
nesee slate, and, so far as known, is confined to that rock; though its associate, the
Discina lodensis , occurs in the black slaty layers in the Hamilton group below.

Geological formation and locality. In the Genesee slate, near Lodi and Bigstream
Point on Seneca lake; and near Ogden’s Ferry, on Cayuga lake.

14

PALAEONTOLOGY OF NEW-YORK.

LINGULAE OF THE CHEMUNG GROUP.

Lingula melie ( n. s.).

PLATE i.

Shell elliptical ; length and breadth about as three to two, the width
often a little greater ; moderately convex, the umbo prominent, and
below it begins a narrow flattened space, which, very gradually wide¬
ning, reaches to the base. ( This feature is noticed on the ventral valves.)
Sides curving, the margins flattened or a little recurved. Beak of the
ventral valve extended and acute ; and in partially exfoliated speci¬
mens there is a depressed sublinear area reaching more than one-third
the length of the shell, and margined on each side by a sharp line.
The specimens, which appear to be the ventral valves of the same species,
are obtuse at the cardinal extremity, and proportionally wider towards
the base. The most extreme example of this kind is shown in fig. 3,
while fig. 4 is the extreme of the other form. The surface characters
are the same in all the specimens, and, on the exterior shell, consist of
fine concentric striae which are crowded at intervals into ridges, giving
an undulating surface. On the exfoliated fossil, the concentric wrinkles
are preserved with faint impressions of the striae ; and obscure radia¬
ting coarser striae mark the surface, becoming stronger towards the
margins, and terminating just within the edge in minute depressions
or puncta.

This species, in some of its forms, resembles the L. spatulata , but is larger, and
also very distinct in the details of its surface markings.

This species occurs at Chagrin Falls, Ohio, in strata of the age of the Chemung
group.

LINGULJ3 OF THE CHEMUNG GROUP.

15

Lingula cuyahoga ( n. s.).

PLATE i.

Shell subelliptical ; length and breadth about as five to three ; sides
nearly parallel, narrowing a little towards the cardinal margins ; beak
obtuse ; cardinal slopes very little inclined ; base abruptly rounded.
Surface marked by fine concentric striae, and, on the exfoliated surface,
by fine obscure radiating striae.

A single valve ( ventral ? ) is very convex along the middle for two-thirds
of the length ; the front rather depressed, and the entire margin, from
the cardinal extremities, flattened. This specimen is in sandstone.
Another imperfect specimen in soft shale has nearly the same pro¬
portions, but is flattened, and the cardinal slopes less nearly rectangular
to the axis.

The species is a well-marked and very distinct form, occurring in the thin arena¬
ceous layers at Cuyahoga Falls, and in the green shale at Akron, Ohio, in strata
referred to the upper part of the Chemung group of. New-York, or Waverly sand¬
stone group of Ohio.

GEKUS Discim ( Lamarck).

This genus, though occurring in the Lower Helderberg group and in the
Oriskany sandstone, is at present known to me in a single species only,
in the Schoharie grit and in the Upper Helderberg limestones. It is known
in two species in the Marcellus shale : one species is very abundant in
the Hamilton group, and another in the Genesee slate ; while the other
known species are not of frequent occurrence.

IS

PALAEONTOLOGY OF NEW-YORK.

DISCING OF THE HAMILTON GROUP.

Discina iiiinuta.

PLATE I.

Orbicula minuta : Hall, Geological Report on the Fourth District, 1843, p. 180.

Shell minute, subcircular, plano-convex. Dorsal valve moderately con¬
vex, except near the apex, which is more abruptly elevated ; apex of
the dorsal valve excentric, and directed forward. Y entral valve flat ;
foramen excentric, with sometimes a slight sinuosity in the margin on
.that side of the shell. Surface marked by fine crowded and wrinkled
striae.

In well-preserved specimens the surface is black and shining, but this
condition is not always maintained.

The specimens have usually the greater diameter one-twentieth, varying to three-
twentieths of an inch. The species is extremely abundant in some layers of the
Marcel lus shale, but is not known to have any great vertical or horizontal range.
Its extreme minuteness distinguishes it from any other species known to me in the
New- Yorkv formations.

Geological formation and locality. In the Marcellus shale : near Avon, N.Y.

Discina humilis ( n. s.).

PLATE II.

Shell of medium size, circular or subcircular, very depressed-convex on
the dorsal side ; apex subcentral. Ventral valve flat, with apex sub¬
central ; foramen apparently submarginal.

Surface, from the apex halfway to the margin, marked by fine concentric
striae, and outside of this by a few comparatively distant sharp elevated
striae, with the intermediate spaces scarcely perceptibly striate.

Two specimens only of this species have been recognized : the larger of these
has a diameter of more than an inch ; and the smaller one, about three-fourths
of an inch. They are more nearly circular than any other species in the Marcellus
shale and Hamilton group, except the D. minuta. The D. lodensis is sometimes
circular ; but its prevailing form is broad oval, and it is always closely and fine¬
ly striated, and, in this feature, very distinct from the present species. .

DISCING OF THE HAMILTON GROUP..

17

Geological formation and locality. In the Marcellus slate, near Bridgewater ;
and in the shales of the Hamilton group, on Canandaigua lake.

Discina grandis.

PLATES I & II.

Orbicula grandis* : Vanuxem, Geological Report Third District, 1842, p. 152-3, f. 4.

General form broadly and transversely elliptical, plano-convex or
concavo-convex. Dorsal valve sometimes extremely elevated ; apex
subcentral, a little on one side of the transverse axis. Ventral valve
usually moderately concave ; foramen reaching from the centre or near
the centre towards one side, but varying somewhat in different indivi¬
duals.

Surface marked by fine concentric striae, crowded near the centre, and
more distant and sharply elevated towards the margin.

This species is recognized by its large size, and in the ventral valve by the
direction of the foramen being in the shorter diameter of the shell. This valve
is somewhat unequally concave, and, on the side of the foramen, often a little
convex. The dorsal valves of two specimens, which appear to be of this species
(one of them with ventral valve attached), are very different in their degree of
convexity, and may prove distinct.

In different specimens, this species has a transverse diameter of one inch and
a quarter to one inch and five-eighths, with a longitudinal diameter of one inch
and an eighth to one inch and a quarter.

The original figure of Vanuxem, given below, is of the ventral valve. A single
specimen retaining the two valves in connexion, has been observed ; while a
separate valve of this, or an allied species, has been found in the same associa¬
tion. So far as the collections yet obtained furnish evidence, this species is. very
rare ; and but a single fragment (and this may be questioned ) has been found
to the west of Cayuga lake.

* This name was overlooked at the time of describing the species in the Oriskany sandstone, and will be
superseded for that species, the one under consideration having precedence. I propose for the Oriskany
form the name Discina ampla.

[ Palaeontology IV.] 3

18

; PALAEONTOLOGY OF NEW- YORK.

Discina grandis (Vanuxem).

Geological formation and locality. In the compact arenaceous shales, at Caze-
novia, and at Pratt’s falls in Onondaga county ; and a single fragment has been
found near Moscow, Genesee county.

Discina randalli ( n. s.).

PLATE II.

Ventral valve circular or nearly circular, gently concave within the
margin : foramen large, marked, by a broadly oval depression on the
exterior surface, which reaches half the distance from the apex to the
margin.

Surface marked by strong rounded concentric ridges with sharp depres¬
sions between, and sometimes with finer concentric striae upon the
coarser ones ; all of them crossed, on the posterior margin of the shell,
by fine radiating striae or vascular impressions, which enter into the
substance of the sheik On the anterior half of the shell, the concentric
striae become partially obsolete. From a constricted ridge, which exter¬
nally marks the place of a median septum in the muscular impression,
there diverge strong rounded radiating ridges, separated by narrow
abrupt depressions which extend nearly or quite to the margin of the
valve.

The single specimen known is a partially exfoliated exterior surface of a ven¬
tral valve : the margin of the anterior portion is somewhat broken and worn
away. Certain appearances indicate that the dorsal valve lies beneath this ventral
valve, imbedded in the matrix, and the two pressed closely together.

This species is a large and remarkable form ; the transverse diameter is nearly
three inches* and from the apex to the posterior margin is one inch and a half,

DISCING OF THE HAMILTON GROUP.

1©

The anterior side being broken off, we infer, from the ordinary proportions of
these shells, that it has been at least as long as the posterior part, which gives a
longitudinal diameter of three inches. The concentric striae are stronger than in
any of the other species in these rocks, and the strong radiating ridges are a
very distinguishing feature.

This is the largest well-authenticated Discina that I know; though I have a
discoid fossil under consideration, possessing the general appearance of Discina,
which in its greatest diameter is four inches.

Geological formation and locality. In the arenaceous shales of the Hamilton
group : near Schoharie.

Discina doria ( n. s.).

PLATE II.

Shell subcircular or oblate, the transverse diameter usually the greater.
Dorsal valve convex; apex elevated, subterminal. Ventral valve flat
or concave, the apex excentric ; foramen comparatively large, oval,
with margins depressed. Shell thin.

Surface marked by fine concentric striae, and the cast by folds or wrin¬
kles in the same direction.

This species closely resembles the D. newberryi , from Cuyahoga falls, Ohio; but
that shell is somewhat thicker and stronger, with the apex of the dorsal valve
more elevated. The specimens of the present species observed are likewise
smaller. The presence or absence of the radiating striae on the cast, which are
probably caused by the soft parts of the animal, cannot be relied upon as cha¬
racteristic. The length of the largest specimen is about three-tenths of an inch,
with a width of seven-twentieths of an inch.

The most characteristic specimens of this species which have been seen, are
adhering to other fossils ; and its identity with Discina might be questioned, but
for the preservation of four individuals (one of them a ventral valve) upon a
specimen of Pleurotomaria sul comar gin at a. The same species occurs in Canada
West, attached to Spirifeu.

Geological formation and locality. In the Hamilton group : at Hamilton ; on
the east shore of Seneca lake, N.Y. ; and in Canada West.

PALAEONTOLOGY OF NEW-YORK.'

m

Discina seneca ( n. s.).

PLATE II.

Dorsal valve broadly oval ; apex about one-third from the posterior
margin, and, in a specimen six-tenths of an inch in length, is elevated
one-tenth of an inch above the plane of the margins.

Surface marked by concentric, somewhat regular folds or wrinkles in
the larger specimens, and, in a smaller one, the surface is similar, but
less uneven ; the concentric markings being more like undulations of
the surface, than the ordinary striae of Discina.

Two specimens of dorsal valves only have been seen : they have the same form
as D. media and D. lodensis; bnt the apex is much more elevated, and the surface
striae are not of the same fine and regular character, though, the specimens being
partial casts, this feature may be somewhat obliterated. One of the specimens has
a length of six-tenths of an inch, with a width of five-tenths ; while the smaller
one has a length of one-fifth, and a width of one-sixth of an inch..

These specimens occur in the same shale with the other species, which are al¬
ways flattened, while both the old and young of this maintain their proportions
as described. With the single larger specimen, I hesitated to characterize the
species ; but finding a small one of the same form and character, I can scarcely
indicate it as a variety of either of the other species which it resembles in general
form.

Geological formation and locality. In the upper part of the Hamilton group :
on the east shore of Seneca lake.

Discina media ( n. s.).

PLATE II.

Compare Discina lodensis) pa. 22, pi. 2.

Shell broadly elliptical or subcircular, variable in form. Dorsal valve
very depressed-convex ; apex excentric, pointed, and inclined towards
the posterior border. Ventral valve flat, or a little convex just anterior
to the foramen ; foramen narrow, directly in the longitudinal axis of
the shell, or often a little oblique.

DISCING OF THE HAMILTON GROUP.

21

Surface finely and evenly striated by fine regular elevated striae, distant
from each other more than twice their width. The apex of the dorsal
valve is about one-third, and sometimes less than one-third the length
of the shell from the posterior margin. Perforation of the ventral valve
narrowly oval or sublinear, about one-third the length of the shell from
the posterior margin, and extending towards the edge of the shell.
This species resembles in form the D. lodensis of the Genesee slate ; but it is
more coarsely and distantly striated, and does not present the radiating folds or
undulations observed in that species. The position and relations of the apex and
foramen are similar to those of the D. lodensis; and it is possible that conditions
of the sediment, and other physical causes, may have affected the external cha¬
racters, and that we have, only a well-marked variety of that species. The species
is not uncommon in the Hamilton group, both in the bluish shales and in the
dark slaty beds, which are of the same character as the Genesee slate.

A single specimen of a ventral valve, found in the upper part of the Chemung
group in Steuben county, possesses characters so entirely similar to those of the
Hamilton group, that I can find no means of separating it.

.The oval form and excentric position of the apex are sufficient to distinguish
the species from others of these groups. The elliptical specimens measure half
an inch, or more, in length, with a width of nine-twentieths of an inch.

Geological formation and locality. In the Hamilton group, on the shores of
Seneca lake near Ovid, and in the upper part of the group on the shores of the
Canandaigua lake ; and in the green shale of the Chemung group in the south
part of Steuben county, at Troupsburgh.

Discina (sp.?).

PLATE II.

A small nearly circular specimen of a ventral valve, occurring in the
Marcellus slate, is marked by fine crowded and scarcely distinct striae :
the apex is excentric, being scarcely more than one-third the length of
the shell from the posterior margin ; with a short, narrowly oval
foramen.

This specimen is unlike any other one before me, and maybe a distinct species;
but I hesitate to designate it without more material.

Geological formation and locality. In the Marcellus slate : near Bridgewater ,
N.York.

PALAEONTOLOGY OF NEW-YORK.

Discina tullia ( n. s.).

PLATE II.

Dorsal valve elliptical ; apex excentric, elevated above the plane of the
margins of the shell nearly one-eighth of an inch ; length half an inch,
and breadth little more than three-tenths of an inch.

Surface marked by fine crowded strise.

A single specimen of the dorsal valve only has been seen, but its proportions
of length and height distinguish it from any other species in the rocks of New-
York.

Geological formation and locality. In the Tully limestone near Ovid, Seneca
county, N.Y.

Biscina lodensis.

PLATE II.

Orbicula lodensis : Hall, Geological Report Fourth District, p.223.

— — ; Vanuxem, Geological Report Third District, p. 168.

Shell broadly oval-ovate or subcircular, narrower towards the posterior
end. Dorsal valve very depressed -convex ; apex minute, excentric,
less than one-third the length of the shell from the posterior margin.
Yentral valve flat towards the margins, and somewhat abruptly ele¬
vated at the apex ; foramen linear, extending more than halfway from
the apex to the margin, and sometimes causing an undulation of the
edge, or slight emargination.

Surface finely striated concentrically by close crowded and little elevated
strise, and, on the anterior half of the shell, by faint radiating folds or
undulations. In partially exfoliated specimens, radiating marks of the
vascular impressions are perceptible. Specimens rarely show the con¬
centric strise to be crenulated by delicate radiations, a character which
undoubtedly existed in all perfect shells.

In the partially exfoliated shells, the apex of the dorsal valve shows a

DISCING OF THE HAMILTON GROUP.

narrow indentation on the anterior slope ; and in ventral valves in
similar condition, there is sometimes a lobed muscular impression -^just
anterior to the foramen.

This species is very abundant in certain localities of the Genesee slate. The
oval-ovate forms rarely or never exceed nine-twentieths of an inch in length, by
eight-twentieths in the greatest width. The largest subcircular form obtained has
a length a little less than half an inch, with a width of full half an inch in its
greatest diameter, the posterior end being truncate.

In form and proportions, this shell scarcely differs from the D. media , hut is
smaller than the generality of that species, the striae much finer and closer, and
it possesses the faint radiating folds which do not appear in that species.

Geological formation and locality. In the Genesee slate, above the Hamilton
group : near Lodi and Bigstream point, Seneca county, N.Y.

©isciiia truncafa ( n. s.).

PLATES I & II.

Shell ovate, the anterior end broader : valves depressed-convex. Dorsal
valve with the apex near the posterior margin, and directed backwards ;
posterior margin very abruptly rounded or truncate. Ventral valve
with the apex submarginal ; foramen extending nearly or quite to the
posterior margin, which is indented.

Surface marked by fine concentric striae and faint radiating undefined
lines.

This little species scarcely ever exceeds two-tenths of an inch in length ; while
the greatest breadth, which is anterior to the middle, is nearly the same. The
dorsal valve has the appearance of a Lingula, with flattened margin extending
beyond the beak : the ventral valve shows a submarginal foramen. The muscular
impressions (which are faintly preserved ) differ from the ordinary Discina, but
are too obscure to afford means of separating it from the genus.

In some specimens the posterior margin is abruptly rounded, while in others it
is straightly truncate. It may, perhaps, have been an elongated form of this shell
which is. figured as Lingula concentrica in the Geological Report on the Fourth
District.

Geological formation and locality. In the Genesee slate : near Lodi, and at
Bigstream point, Seneca county;

34

PALAEONTOLOGY OF NEW-YORK.

DISCING OF THE CHEMUNG GROUP.

Discina neglecta ( n. s.).

PLATE I.

Shell elliptical. Dorsal valve convex : elevation of the apex above the
plane of the margins about one-twelfth of an inch ; apex situated about
one-third the length of the shell from the posterior margin.

Surface marked by crowded wrinkled concentric striae.

A single specimen of the impression of the dorsal valve measures seven-tenths
of an inch in length, with a width of six-tenths of an inch. The dorsal valve of
another specimen of similar character is more nearly circular, the concentric
strim are thin and elevated, and the interior shows a linear muscular impression.

Other specimens are required for a full determination of the characters of the
species. It is a more robust form, with the apex more elevated, than the D. lo-
densis ; and the specimens maybe compared with D. seneca.

Geological formation and locality. In the arenaceous shales of the Chemung
group, from the Inclined Plane at Ithaca, Tompkins county, N.Y.

©iseiiia elmira ( n. s.).

PLATE II.

Dorsal valve very convex, transversely broad-oval ; breadth about seven-
tenths of an inch, and length half an inch : apex excentric, or about
one-third from the posterior margin. Ventral valve unknown.

Surface marked by extremely fine crowded striae.

This specimen of the dorsal valve only, is noticed in anticipation of obtaining
materials for a full illustration. In the elevated dorsal valve, position of apex,
and fine strim, it bears some resemblance to the dorsal valve of D. grandis.

Another specimen of similar character, but with the apex a little more de¬
pressed, has a length of half an inch, with a transverse diameter of about one
inch. This specimen is essentially a cast in sandstone, and its surface markings
are not clearly preserved ; but it shows no important difference from the pre¬
ceding one, and for the present I unite the two under the same designation.

Geological formation and locality. In the shales of the Chemung group : near
Elmira, N.Y., and in sandstone of the same group near Wellsborough, Pa.

DISCING OF THE CHEMUNG GROUP.

25

Discina alleghania.

PLATE I.

Discina alleghania : Hall, Thirteenth Report on the State Cabinet, p. 77.

Shell broadly elliptical or nearly circular. Dorsal valve depressed conical;
anterior side broadly and equally convex ; apex placed at a little more
than one-third the length from the posterior end of the shell, slightly
inclined backwards ; the posterior slope concave, and the shell flattened
* towards the margin.

Surface marked by fine regular concentric lamellae, which are distant
from each other two or three- times their width.

This large species is one of the finest and most beautiful of the genus, nearly
equal in size to the D. ampla of the Oriskany sandstone, and differing from that
one in the posterior position of the apex and the more abrupt sloping on the
posterior side, while the concentric stride are much finer and more closely ar¬
ranged. It differs from the large circular form D. discus of the Lower Helderberg
group, in the greater elevation of the dorsal valve, and absence of radiating strise.

This species differs from the D. grandis of the Hamilton group in the position
of the apex of the dorsal valve, and in the direction of the foramen relative to
the greatest diameter of the shell.

Geological formation and locality. In the Chemung group, Hobbieville, Allegany
county, N.Y.

Discina alleghania.

Discina newberryi ( n. s.).

PLATE I.

Shell subcircular or broadly ovate, sometimes oblate : apex situated near
[ Paleontology IV.] 4

2©

PALAEONTOLOGY OF NEW-YORK.

the posterior margin or less than one-fourth the length of the shell
therefrom, prominent, being from less than one-eiglith to one-quarter
of an inch above the plane of the margins. Ventral valve slightly con¬
cave ; apex excentric ; foramen large, oval, with the margins deeply
depressed. Shell comparatively thick and strong.

Surface marked by fine concentric lines, which are very faint in young
shells, but become stronger and rise into distinct sharply elevated striae
in older specimens.

Where partially exfoliated, the shell shows intermediate fine radiating
striae ; and in older specimens, the interior of the shell, and likewise
the cast, is marked by strong radiating vascular impressions. The
structure of the shell is strongly lamellose. The casts of the dorsal
valve show a narrow longitudinal muscular impression on the anterior
side of the beaks. The length varies from one-eighth to one inch.

For these specimens, I am indebted to Dr. J. S. Newberry.

Geological formation and locality. Abundant in a ferruginous band about 110
feet below the Conglomerate at Cuyahoga falls, and in the green shale and shaly
sandstone at Akron, Ohio.

Genus Crania (Retzius).

Up to the present time, the Genus Crania has not been recognized in the
New-York collections, from any rock below the Schoharie grit.

The extensive and long continued explorations in the Lower Helder-
berg group, which resulted in the discovery of many rare and obscure
fossils of that formation, we may suppose would have brought to light any
species of this genus which might have lived in the area of investigation.
Still we are far from being warranted, by this negative information, in
the inference that this genus, did not exist in the preceding periods in the
New-York strata, since We know of its occurrence in rocks of the age of
the Niagara group in Indiana. At this time we know of but two indivi¬
duals in the Schoharie grit, notwithstanding that collections have been
made from that rock during the past twenty-five or thirty years.

CRANLE OF THE HELDERBERG AND HAMILTON GROUPS. %7

CRANIA OF THE UPPER HELDERBERG GROUP.

Crania aurora ( n. s.).

PLATE III.

A cast of Trochoceras, from the Schoharie grit, preserves the impres¬
sions of two individuals of a species of Crania, which were apparently-
adhering to the interior of the shell of the outer chamber of this cepha-
lopod.

Ventral valve subquadrate, approaching a circular form ; lateral margins
slightly curved, and the two extremities abruptly rounded, the posterior
one least curved : margins thickened. The impressions of the anterior
muscles are nearly united in a transversely subelliptical scar : posterior
adductor scars distant, not well defined in the specimens.

No other specimens of this or any other species of the genus are known to me,
at this time, from this formation.

Geological formation and locality. In the Schoharie grit, in the town of Knox,
Albany county.

CRANIA] OF THE HAMILTON GROUP.

Crania liamiltonise.

PLATE III.

Crania hamiltonia : Hall, Thirteenth Report on the State Cabinet, p. 77 ; and f. 4 & 5, p. 76.

Shell broadly oval or subcircular. Dorsal valve subconical ; apex sub¬
central or excentric, pointed in well-preserved specimens, often worn
or decorticated. Exterior surface of dorsal valve marked by concentric
lamellose stride. Ventral or lower valve marked by four strong impres¬
sions of the adductor muscles, which are variable in form : the poste¬
rior ones are distant the anterior ones approximate, diverging above
and assuming’ a somewhat cordiform appearance, the pit for the pro¬
tractor muscles occupying the space between. Vascular impressions
Strongly digitate.

28

PALAEONTOLOGY OP NEW-YORK.

This species is found adhering to valves of Athyris , Tropidoleptus, Strophodonta ,
Spirifer, Avicula , Orthoceras, etc., and separated valves are also free in the shales.
The form of the shell is very much influenced by the form of the body to which
it adheres. The dorsal valve is often regularly oval and symmetrical, rising to a
low subconical form, with the apes excentric on the posterior side. Some speci¬
mens are irregularly subcircular, with the surface wrinkled and uneven.

In a single specimen adhering to a Tropidoleptus, the form of the plications of
that shell are carried into the dorsal valve of the Crania, conforming in part to the
curvature of its margin as the shell increased in size. The form of the ventral
valve is influenced not only by the contour of the body to which it adheres, but
by the small bodies growing upon the same surface. In a single example, the
central ’portion of the posterior margin is produced in a narrow extension be¬
tween two Spirorbides, which prevented the shell from growing in that direction.

The dorsal valves are not unfrequently partially covered by an adhering
Aulopora- like body ; and the small Spirorbis angulatus is likewise found adhering
to them.

In some of the specimens, the form and character of the interior of the ventral
valve resembles that of the C. obsoleta of Goldfuss, from the Eifel, which is of
Devonian age.

Geological formation and locality. In the shales of the Hamilton group, in the
region of Canandaigua lake and on the shores of Seneca lake ; at Bethany and
Covington, Genesee county ; Richmond and Bristol, Ontario county ; and in Erie
county. Likewise at Cazenovia and Hamilton in Madison county, and elsewhere
in New- York, as well as in the Hamilton group in Maryland and Virginia.

Crania crenistriata.

PLATE III.

Crania crenistriata : Hall, Thirteenth Report on the State Cabinet, p. 78.

Dorsal or upper valve very depressed-conical, subcircular ; apex central
or subcentral, a little inclined.

Surface marked by sharp elevated crenulate striae, reaching almost to
the apex (which is quite smooth), and increasing by interstitial addi¬
tions.

This species is rare, and four specimens only of the dorsal valve are known at
this time. The character of the striae gives the fossil, when partially obscured by

CRANLE OF THE HAMILTON GROUP.

29

adhering shale, the appearance of the exterior of the small funnelshaped fronds
of Fenestella. The strim are similar to those of Crania ( Pseudocrania ) divaricata
of M'Coy, a Silurian fossil ; but the form and position of apex is very distinctive.

The ventral valve of this species has not yet been discovered, unless it may
occur among the imperfect and obscure specimens which have been referred to
C. hamiltonicR.

Geological formation and locality. In shales of the Hamilton group : Alexander
in Genesee county ; on the shore of Canandaigua lake in Ontario county ; and at
Eighteen-mile creek on Lake Erie, N.Y.

Crania gregaria ( n. s.).

PLATE III.

Shell small, obliquely very depressed-conical,, subcircular or oblate, nar¬
rower at the posterior end ; apex at the posterior third of the shell.
Surface apparently smooth.

This small species occurs from the size, of a pin’s head, to those having a
transverse diameter of a little more than a tenth of an inch, with a longitudinal
diameter a little less than one-tenth of an inch. On a single valve of a large
bivalve shell, nearly forty individuals of this species can be seen, together with
the remains of several ventral valves of one of the larger species.

It may be possible that these small fossils are the young of C. hamiltonice , which
have commenced their existence upon the same body which sustained the parent
shells.

Geological formation and locality. In the shales of the Hamilton group, in
Bristol, Ontario county.

PALAEONTOLOGY OF NEW-YORK.

30

CRANIzE OF THE CHEMUNG GROUP.

Crania koiii.

PLATE III.

Crania leoni : Hall, Thirteenth Report on the State Cabinet, 1860, p. 78.

Shell subcircular, transverse or slightly elongate. Dorsal valve convex.
Ventral valve concave, variable in form, more abruptly recurved to¬
wards the margin. Hinge-line straight, equal to a little- more than one-
third the greatest width of the shell. Muscular impressions of the
posterior adductors in the dorsal valve near the cardinal angles ; the
anterior ones near together and a little behind the centre, with two
minute impressions a little anterior to the centre, marking the place
of the retractor muscles. Ventral valve with. the posterior adductors
corresponding to those of the dorsal valve ; the anterior adductors
occupying a subcircular area, and barely separated by an elevation
marking the place of the protractor muscle.

This species is known only, in the condition of casts of the interior. The
dorsal side is moderately convex ; the apex apparently a little excen-
tric on the posterior side.

A single cast of a dorsal valve among the specimens is more regularly
elliptical, a little more convex, and without the straight hinge-line :
this one may perhaps be a distinct species.

There are, likewise, in the rocks of the Chemung group, some other specimens
of the character of Crania ; but, unfortunately, I have at this time no specimens
in a condition to admit of their being satisfactorily described.

Geological formation and locality. In the Chemung group : Leon, Cattaraugus
county, N.Y.

PIIOLIDOPS.

SI

&EATS PlIOLlDOPS ( Hall).

All the known species of this genus are small shells, usually occurring
as single scale-like valves or discs, and in two instances only have I seen
specimens with the valves conjoined. The specimens appear not unlike
the dorsal valves of a small species of Discina ; but' being calcareous, they
have not the corneous lustre of those shells ; and when conjoined, there
is no evidence of a foramen in either valve. The interior shows a strong
muscular callosity, and the casts bear a strongly marked impression of
the same.

Pholidops areolata ( n. s.).

PLATE III.

Shell broadly subovate or scarcely circular, wider on the posterior third,
broadly rounded behind and more narrowly rounded in front.

The cast of one valve (the dorsal valve?) shows a deep ovate or sub-
cordiform muscular scar, which is nearly surrounded by an elevated
areola, and partially divided by a median ridge from above. The opposite
( ventral ? ) valve has a larger muscular scar, which is auriculate above,
with the surrounding areola divided at the lower or anterior margin.
Surface somewhat abruptly flattened on the posterior side, and more
gently sloping on the front of the valve.

One specimen has a length a little less than one-fourth of an inch, with
a width across the middle nearly the same. The only specimens known in
the Schoharie grit are casts, and we have not therefore seen the exterior
of the shell. In casts of two individuals, the muscular impressions present
some differences in form, and in the depth of the impressions of the
parts, probably indicating the characters of dorsal and ventral valves.
This species closely resembles one, in the Oriskany sandstone, from which it

33

PALAEONTOLOGY OF NEW-YORK.

differs in being more ovate, as well as in tlie form and division of the muscular
scar, and more depressed posterior side*.

Geological formation and locality. In Schoharie grit : at Clarksville and Knox,
Albany county, N.Y.

Fholidops liamiltonise.

PLATE III.

Pholidops hamiltonia : Hall, Thirteenth Report on the State Cabinet. 1860, p. 92.

Shell regularly and uniformly ovate, broader near the posterior end :
apex excentric, little elevated, and slightly inclining to the posterior
side.

Substance of the shell thin, and flattened towards, the margins. Surface
marked by fine closely arranged lamellose strise. Interior smooth,
except an ovate, somewhat auriculate, and sometimes slightly bilobed
prominence beneath the apex, which marks the muscular impression.
The casts of the interior show a comparatively large muscular impres¬
sion, which is shield-shaped or subovate and somewhat auriculate, or
with a deeper impression on each side above the middle. In one (dorsal?)
valve, the impression' is a little bilobed near the lower end ; and in
another, which appears to be the ventral valve, there is a faint radiating
or digitate impression on the lower half of the muscular scar. The
surface, when magnified, shows indications of minute interrupted ra¬
diating striae.

This species is the smallest of any described ; having a length of fourteen-
hundredths of an inch, with a width of twelve-hundredths in the widest part.
It is not rare, but we find only separated valves..

The observations upon this genus, under the generic description, will show
the facts regarding the known species, and their geological range (See Introduc¬
tion to this volume).

Geological formation and locality. In the shales of the Hamilton group at Darien
in Erie county, at Moscow in Livingston county, and other places in Western
New- York.

For a description of the Oriskany sandstone species, P. arenarius, see Addenda to this volume.

ORTHIDES OF THE UPPER HELDERBERG ROCKS.

33

Genus Obtiiis ( Dalman).

ORTHIDES OF THE UPPER HELDERBERG GROUP.

There are three, or perhaps more,' species of Orthis occurring in the
Schoharie grit, which are the lowest beds of the group ; but since the
specimens are almost invariably in the condition of casts of the interior,
a satisfactory determination of their specific characters is attended with
many difficulties. It has been only by preserving the casts of the interior,
with such impressions of the exterior surface of the shell as could be
obtained, that the characteristic features of two species have been pretty
well ascertained. One of these occurs in considerable numbers, while the
other is extremely rare : the first resembles a species found in the lime¬
stone above the grit, but known only in few examples ; while the other
is quite distinct from any known above the horizon of the grit. A third
species, of peculiar characters, has been seen only in a single specimen of
the cast of the ventral valve ; while some impressions of the exterior of
a shell have not been identified with either of them,

In the limestones above the Schoharie grit we have at least five well
marked species, in addition to those just mentioned.

The Orthides of this group of strata do not present any important
differences, in general features, from those of the group below : they are,
however, far less numerous, both as species and individuals. Two of the
species are of the type of Orthis oblata ; and two others are of the type of
O. subcarinata of the Lower Helderber’g group, while Orthis propinqua of
the Upper Helderberg limestone resembles Orthis multistriata of the Upper
Pentamerus limestone of the same group.

In the details of form, surface markings, area, and muscular impressions
of these different species, there are sufficient means of identification, and
of distinction from those before described.

Some of the species in the limestones of this group have a wide geo¬
graphical distribution, but no one of them has proved to be of common
[ Palaeontology IV.] 5

34

PALAEONTOLOGY OF NEW-YORK.

occurrence in the State of New-York. This limestone formation, within
the limits of the State, being for the greater extent a firm and subcrystal¬
line rock, has yielded few specimens of as great perfection as those of the
Lower Helderberg group.

A. Species ol tne type of O. eJegamuia and U. subcarinata, with the dorsal valve nearly
flat :

Orthis peloris, Orthis lenticularis,

Orthis peloris ( n. s.).

PLATE IV.

Shell plano-convex ; the dorsal valve nearly flat, and subcircular or
slightly transverse : ventral valve somewhat semielliptical, very con¬
vex on the umbo, the middle regularly convex and sloping to the front
and sides ; cardinal line equal to or greater than two-thirds the greatest
width of the shell. Area of moderate height, the beak of the ventral
valve extending little beyond the area line.

Surface marked by fine somewhat evenly bifurcating striae, which curve
towards the margins, and a few terminate on the area line of the
ventral valve.

The specimens are casts of the interior, with impressions of the exterior : from
these latter, casts have been taken, which have served for the description of the
exterior surface of the shell.

The internal cast of the ventral valve is highly convex; the greatest convexity
being above the centre, sloping gently to the front and more abruptly to the sides.
The muscular impression is comparatively small, subelliptical in form, the lon¬
gitudinal being a little greater than the transverse diameter, deeply bilobed by
the callosity of the adductor muscle, and the sides somewhat distinctly lobed in
about three divisions. The surface of the cast, below the muscular impression, is
faintly marked by the vascular impression, and the margin strongly striated.
The distance from the beak, or filling of the rostral cavity, to the lower side of
the muscular impression, is less than half the length of the cast.

The cast of the dorsal valve is nearly flat, with an oval muscular area which is
deeply divided in the centre from the pit made by' the cardinal process and its
extension along the interior of the shell, whence it becomes bifurcate. The mu¬
scular impression is transversely divided by a ridge, extending on each side from
the median line, as in species of the type of Orthis elegantula.

ORTHIDES OF THE UPPER HELDERBERG ROCKS.

35

The casts of these two valves, which I have placed under one designation,
have not been found in actual connexion ; but the character of the ventral valve
requires a dorsal valve of the form described, and vice versa; while the two oc¬
curring in the same locality, and of equal rarity, I can feel little hesitation in
considering them of the same species.

Geological formation and locality. In the Schoharie grit : at Clarksville and
Knox, Albany county, N.Y.

Orthis lenticularis.

PLATE Y.

Orthis lenticularis [? ] Vanuxem, Geological Report Third District p. 139, f. 4.

Compare Orthis solitaria of the Hamilton group.

Shell suborbicular or subquadrate, sometimes suboval, greatest width
above or below the middle, subplanoconvex : hinge-line equalling or
greater than two-thirds the greatest width of the shell ; cardinal extre¬
mities rounded. Dorsal valve varying from very depressed-convex to
moderately convex in the upper part, more or less abruptly depressed
towards the cardinal extremities, which are a little deflected ; gently
curving towards the middle of the sides, and the centre marked by a sinus
which begins at the beak and expands so as to produce a broad depres¬
sion in front : area linear, the beak projecting a little beyond the area
line. Ventral valve very convex, sometimes obtusely subcarinate along
the centre ; greatest convexity near, or a little above the middle of the
valve, curving very abruptly to the front and to the sides (or, when
carinate, it is irregularly depressed), and curving more gently towards
the • beak : area of moderate width, a little incurved ; foramen com¬
paratively large, wider than high ; beak incurved over the foramen.

Surface finely striated with rounded subequal radiating striae, which bi¬
furcate at intervals, and sometimes every fifth, sixth, or seventh one
is more prominent than the others : about sixteen to twenty-two striae
in the space of two lines, the striae wider than the spaces between them,
and crossed at unequal distances by subimbricating lines of growth.
Entire surface finely papillose, and, on the worn surfaces, punctate.

PALAEONTOLOGY OF NEW-YORK.

3®

The interior of the ventral valve preserves very strong dental lamella,

and a strong callosity for the attachment of the cardinal muscle.

I refer this species to the 0. lenticularis of Yanuxem with some little doubt,
since the original specimen in the State Collection has been lost. The form de¬
scribed by Mr. Yanuxem is similar to that of figs. 1 and 2 of Plate y, which is
subquadrate, the front being sometimes rounded and sometimes straight. The
other forms ( figs. 3, 4 and 5), which I find myself compelled to refer to the same
species, are more robust, with the greatest width below the middle, and a much
greater convexity of both dorsal and ventral valves.

In form, this species resembles the 0. subcarinata of the Lower Helderberg
group ; but the striae are finer, the area larger, and the muscular callosity and
dental lamellae are stronger ; while the narrowing towards the hinge in the more
robust forms is a character not observed in that species.

The specimens ordinarily seen have a length and breadth of a little more or
less than half an inch, with a depth of about one quarter of an inch ; while the
largest specimens have a length and breadth of three-fourths of an inch, with a
depth of about half an inch.

Geological formation and locality. In the Corniferous limestone of the Upper
Helderberg group : at Leroy, Genesee county ; near Caledonia, Livingston
county ; tAvo miles south of Yienna, and at Shortsville, Ontario county, N.Y.

B. Species of the type of Orthis hybrida and O. oblata, with the dorsal valve more
convex than the ventral :

Orthis alsus, Orthis ( sp. ? ),

Orthis mitis, Orthis vanuxemi?

Orthis livia, Orthis semele,

Orthis cleobis.

Oithis alsus ( n. s.).

PLATE IY.

Shell somewhat semielliptical in outline : cardinal line equal to, or
more than two-thirds the greatest width, which is near or just below
the middle. Dorsal valve more convex than the ventral, the greatest
convexity being about the middle, sloping almost equally to the sides
and front, and less rapidly to the beak, while it is flattened or concave
towards the cardinal angles. The centre is marked by a sinus from the

ORTHIDES OF THE TJPPER HELDERBERG ROCKS. $7

beak, which gradually expands to the base of the shell. Ventral valve
depressed - convex, and nearly flat in the middle of the lower half :
beak small and neatly defined, projecting slightly beyond the area-line ;
area narrow sublinear, a little inclined ; foramen partially filled by the
strong cardinal process of the opposite valve. Area of the dorsal valve
comparatively large, equal to two-thirds the width of the area of the
ventral valve, flat or lying in the plane of the margins of the valve.
Surface marked by fine, somewhat unequal, bifurcating striae, about
eight or nine in one-fifth of an inch, much curved on the upper lateral
margins.

The casts of this species are of the character of 0. oblata of the Lower Helder-
berg, and others in the Hamilton group ; but the hinge-line and area are much
more extended, distinguishing this species from any in those strata with similar
muscular impressions.

The cast of the dorsal valve, when the impression of the area is not preserved,
is not readily distinguishable from some <3f those mentioned ; though in well-
preserved specimens, the depression down the centre, and also across the middle
of the muscular impression, is more strongly marked than in those species.

The muscular impression of the ventral valve is proportionally small, being
usually less than half the length of the valve ; but it is almost always strongly
defined, which, with the long hinge-line, are marked features.

This species occurs . in the Schoharie grit in the condition of casts of the inte¬
rior, with impressions of the exterior surface, usually as separated valves, and
rarely with the impression of both valves in their natural relation. From one of
these specimens, a cast in sulphur has given the exterior form and proportions of
the fossil, as well as the surface markings ; and a single dorsal valve, retaining
the shell, has been found among the entire collection from this rock.

Geological formation and locality. In the Schoharie grit : at Clarksville, Knox,
and other places in the Helderberg mountains in Albany county, and also in
Schoharie.

©rtSiis mitts ( n. s.).

PLATE V.

Shell suborbicular, of moderate convexity ; area about half the width of
the shell ; length and width about as four to five ; cardinal extremities
rounded. Surface somewhat coarsely striated.

38

PALAEONTOLOGY OF NEW-YOKK.

The cast of the ventral valve is depressed-convex above, depressed along
the centre below, with a median groove from the adductor scar nearly
to the front of the shell. Muscular impression elliptical, occupying less
than half the length of the valve, and about one-third the width :
lower half of valve marked by strong vascular impressions.

Two specimens in the State Collection, having respectively the length of about
one-half and five-eighths of an inch, are referred with hesitation to this species.
The cast of the ventral valve possesses characters which distinguish it from any
species of which I know the interior. It is possible that these may he the young
of 0. livia, of which I do not know the interior at this time.

Geological formation and locality. In the Schoharie grit; in Albany and Schoharie
counties, N.Y.

Orthis livia.

PLATE Y.

Orthis livia [? ] Billings, Canadian Journal of Industry, Science and Art, No. xxvii, p. 269, 1860.

A single well-preserved specimen, measuring one inch and one-tenth
in length by one inch and two-tenths in width across the middle, presents
the following characters :

Shell suborbicular, front and sides rounded : cardinal line and area equal¬
ling nearly half the width of the shell ; cardinal extremities rounded.
Dorsal valve of medium convexity, most convex above the middle, and
curving gently and evenly towards the front and lower lateral margins,
more abruptly sloping and scarcely concave towards the cardinal ex¬
tremities ; without perceptible mesial fold or depression : dorsal area
small, flat or lying in the plane of the margins of the valve, about one-
half as wide as the ventral area ; dorsal beak projecting slightly beyond
the edge of the area, but not incurved. Y entral valve moderately con¬
vex, the greatest convexity about one-third the length from the beak,
flattened or depressed below, and slightly concave towards the front
and sides : ventral area of moderate size, inclined backwards ; ventral
beak neatly defined, incurved, and projecting slightly beyond the area
line.

ORTHIDES OF THE UPPER HELDERBERG ROCKS.

3®

Surface marked by fine subangular strise, which increase by bifurcation,
and are strongly curved on the upper margins : spaces between the
striae wider than the ridges, and, when exfoliated, showing finer striae.
Six to eight striae in the distance of two lines.

This fossil presents so many characteristics of 0. livia ( loc. eit.), that I have
referred it to that species ; though in some respects it exhibits differences, which
may indicate a doubt of its identity. The dorsal valve, which appears to retain
its normal form, has its greatest convexity above the middle, and the ventral
valve is more depressed towards the front ; but these are characters which I
conceive may be subject to variation, without indicating specific differences. In
the specimen described, the ventral valve has been accidentally compressed.

Compared with 0. vanuxemi , the dorsal valve is not so convex ; nor does it
show a mesial sinus so common in that species, while the beak is shorter, not
rising so nearly to the same height as that of the ventral valve ; a character
common in good specimens of that shell. It differs from 0. leucosia in the same
respect, and in having the area of the dorsal valve flat ; while in that species it
is slightly incurved, and the form is narrow towards the beak. Orthis penelope is
more oblate, the beaks of the two valves more nearly equal, and the striae in
this, and the two other species are finer and more rounded.

The 0. livia has been very elaborately described iff the Canadian Journal, 1. c.
Geological formation and locality. In the Corniferous limestone of Western
New-York.

Orthis sp.?

PLATE Y.

Shell orbicular or transversely subelliptical, the length and width about
as six to seven : cardinal line less than half the greatest width of the
shell ; extremities rounded and curving outwards, the lateral margins
abruptly rounded, and the basal margin broadly rounded. Dorsal valve
moderately convex, somewhat flattened in the middle, the greatest
convexity a little above the middle, curving regularly to the lateral
and basal margins ; dorsal area very narrow. Yentral valve less convex
than the opposite, the greatest convexity near the beak, sloping gently
towards the front and sides, becoming slightly concave towards the
margins.

40

PALEONTOLOGY OP NEW-YORK.

Surface marked by even rounded striae, which, at intervals, show small
tubular openings, while the intermediate space is minutely papillose or
punctate according to the condition of the surface.

The specimen described has been a little compressed, but it appears to have
possessed a broad shallow sinus on the ventral valve, very similar to 0: oblata
of the Lower Helderberg group : the striae are stronger and more rounded than
in that species.

The length of this specimen is nearly six-eighths of an inch, and its width
seven-eighths of an inch ; but it is probably not an adult individual, and, without
more material, I hesitate to characterize it, since it belongs to a group of Orthides
of which there are numerous closely allied species.

Geological formation and locality . In the Corniferous limestone of Western
New- York.

Orthis vaimxemi?

PLATE Y.

Orthis vanuxemi, Hall. See the same under Hamilton group.

A single specimen of a ventral valve, from the limestone, possesses
characters undistinguishable from those of 0. vanuxemi. This specimen,
however, is the only one of the species which has come under my ob¬
servation from the limestone. Numerous imperfect casts and exfoliated
shells bear close resemblance to the species, and may prove to .belong to
the same.

Geological formation and locality. In the limestone of the Upper Helderberg
group, near Caledonia, Livingston county, N.Y.

Orthis semele ( n. s.).

PLATE V.

Some imperfect specimens showing the interior of the ventral valve,
and also a small specimen of the ventral valve, possess characters ap¬
proaching very nearly to 0. vanuxemi. From the same locality there have
been obtained casts of a dorsal valve, which are more elevated in the

ORTHIDES OF THE UPPER HELDERBERG ROCKS.

41

middle, with the apex more produced than in that species. These casts
give indications of a median sinus with an elevation on each side of it,
and thence an abrupt slope to the cardinal extremities, and curving to
the front and lower lateral margins.

In this, character, they more nearly resemble the dorsal valves of Orthis leucosia;
while the muscular impressions of the ventral valves, from the same locality,
are broader than in that species. The hinge-line of a ventral valve is three-fifths
the greatest width of the shell, which is greater than in either 0. vanuxemi or O.
leucosidy while the strise are also: much coarser. This specimen occurring with the
others, while no other form of ventral valve has been seen in the same association,
indicates the probable relations of' the other specimens.

Although the material in my possession is too imperfect for a complete de¬
scription, I have indicated the prominent features of the species, in order to call
attention to the occurrence of this form in the limestones of the Upper Helder-
berg group.

Geological formation and locality. In the Onondaga limestone : near Clarence
hollow, Erie county, N.Y. I have seen a similar form from the limestone near
Columbus, Ohio.

Orthis cleoMs ( n. s.).

PLATE Y.

Shell broadly semielliptical or subquadrate, the cardinal line being
straight, and extending fully two-thirds the width of the shell ; cardinal
extremities rounded. Dorsal valve having a little more than the medium
convexity ; the greatest elevation about the centre, from which it
slopes almost regularly to the beak, the front, and the lower lateral
margins ; while towards the cardinal angles it is more abrupt, and
becomes slightly concave.. Ventral valve depressed-convex above, flat¬
tened at the sides, with a broad shallow sinus which becomes deeper
towards the margin.

Surface finely striated ; the striae much curved upwards at the sides.

In the cast of the dorsal valve, the distance from the beak to the lower edge
of the muscular impression is about one-half the length of the' valve : the area
is in the plane of the lateral margins, comparatively large, having a width of
[ Paleontology IV.] • 6

42

PALAEONTOLOGY OF NEW-YORK.

about ’18 of an inch. The cast of the ventral valve shows a large flabelliform
muscular impression, from the base of which to the apex of the cast is about
two-thirds the entire length, while its width is about three-fifths the width of the
shell. The cicatrix for the cardinal muscle is very strong ; and below it is a nar¬
row sinus, indicating the existence of a strong median ridge. The ventral area is
unknown, but it has probably been considerably larger than that of the dorsal
valve.

The description is drawn from the casts of two valves, which, in some parts,
preserve a little of the shell.

The long hinge-line is a characteristic feature of the shell ; while the large
area of the dorsal valve, and its well-marked muscular impression, distinguish it
from nearly all the other species. The muscular impression of the ventral valve
is remarkably large and rigidly flabelliform, with the margins strongly defined.

The casts are associated in a thin band of limestone of peculiar character,
leaving no reasonable doubt of their being of the same species ; while another
ventral valve; referred with some doubt to this species, was likewise found in the
same horizon, in the lower beds of the series.

This species, in its large muscular impression, is similar to Orthis musculosa of
the Oriskany sandstone ; but the dorsal valve is not so convex, the hinge-line is
much longer and the dorsal area much larger.

Geological formation and locality. In the Onondaga limestone : near Williams-
ville and Clarence, Erie county, N.Y*

Orthis bias.

PLATE Y.

Orthis equivalvis : Hall, Tenth Report of the Regents on the State Cabinet, 1857, p. 109.

Shell subcircular ox* subquadrate, the hinge-line equalling two-thirds
the greatest width ; sides somewhat straight ; front broadly and re¬
gularly rounded, the greatest width a little below the middle. Dorsal
valve moderately convex, the greatest convexity above the middle,
with a shallow sinus from the beak for half the length of the shell, and
curving very gently to the front and lower lateral margins, sloping a
little more abruptly in the upper part, and the surface becoming con¬
cave towards the Cardinal angles : dorsal area on a plane with the
margins of the shell ; cardinal process large and strong. Y entral valve

ORTHIDES OF THE UPPER HELDERBERG ROCKS.

43

convex in the upper part of the centre, depressed in the middle, and
concave towards the base and lower lateral margins ? cardinal angles
deflected : ventral area inclined backwards, of medium height ; fora¬
men wider than high ; ventral beak projecting a little beyond that of
the opposite valve.

Surface marked by subequal rounded radiating striae, which bifurcate
two or three times before reaching the margin. There are about ten
striae in the space of two lines near the beak, eight in the middle of
the shell, and five or six near the margin. Length of specimen a little
more than an inch and a half ; greatest width about an inch and three-
fourths.

This species is extremely rare, and I have but one good example. In this the
depression of the ventral valve below the middle may be in part due to accident,
and I have indicated this by an interrogation in the description. It is readily
distinguished from any other species in these strata, by the long straight hinge¬
line and subequal valves.

In form and general aspect it resembles a Streptorhynchus, to which genus it
• may possibly belong, though the strise have the character of those of an Orthis.

Geological formation and locality. In the Corniferous limestone at Williamsville,
N.York.

C. Species of the type of Orthis resupinala, O. multistriata, etc., with the dorsal valve
extremely convex.

Orthis propinqmi.

PLATE Y.

Orthis propinqua : Hall, Tenth Report on the State Cabinet, 1857, p. 110.

Shell somewhat transversely elliptical or subquadrate, the front truncate
or emarginate, and the sides little curved, varying from moderately to
extremely gibbous : hinge-line equalling or a little greater than half
the width of the shell. Dorsal valve the larger and much the more
gibbous ; the greatest convexity a little above the middle of the length,
curving abruptly to the sides and beak, and a little more gently to the
front ; sometimes a little concave just within the cardinal angles :

44

PALEONTOLOGY OP NEW-YORK.

area inclined to the area of the opposite valve, and about one-half or
two-thirds as wide ; dorsal beak full, broad and rounded or obtusely
pointed, extending a little beyond and slightly incurved over the area.
Ventral valve less gibbous than the dorsal, very prominent on the
umbo, sloping very abruptly to the cardinal angles and more gently
towards the lateral and baso-lateral margins, flattened in the centre ;
the lower half marked by a gradually increasing, broad, and undefined
sinus, which gives a strongly curved outline to the front margin : beak
more acutely pointed and incurved ; area elevated and incurved, its
length equalling or greater than half the width of the shell. The beaks
of the two valves are approximate.

Surface marked \>y fine unequal striae which increase by interstitial
additions, and are crossed by fine equal concentric striae, and, at un¬
equal intervals, by stronger imbricating lamellose lines of growth. In
certain conditions of the surface, the striae show tubular openings at
the concentric lamellose lines. There are from eight to ten of the larger
striae in the space of two lines ; and by counting the finer intermediate
striae, there are sometimes from thirteen to eighteen in the same space.
The cast of the dorsal valve shows a subquadrate or quadrate-ovate
muscular scar, with a deeply marked border and longitudinal median
groove : a groove passes from the centre of the median line obliquely to
the lower lateral angles, dividing the adductor muscular scar. The va¬
scular impressions radiate from the muscular impression in broad bands,
dividing several times before reaching the margin of the shell.

This species approaches so closely the 0. multistriata of the Upper Pentamerus
limestone of the Lower Helderberg group, that it is very difficult to distinguish
them, the form and surface charactess being generally almost the same. Some¬
times, however, the ventral beak and area in this species is a little more arcuate
than in 0. multistriata , and the dorsal valve is usually more gibbous, while in¬
ternally they present well-marked differences. In this shell, the vascular im¬
pressions bifurcate once, twice, or even three times, before reaching the border ;
while in 0. multistriata , they pass down the front without bifurcation.

The Orthis tulliensis of the Tully limestone is another form very difficult to
be distinguished from this one ; but it is generally more gibbous, and presents
internal differences ; the divisions of the vascular impressions pass down the

ORTHIDES OF THE HAMILTON GROUP.

45

front of the dorsal valve nearly parallel to each other, or slightly converging ;
while those of the present species, as well as of 0. multistriata , are divergent.

Geological formation and locality. Limestone of the Upper Helderberg group :
New- York and Ohio.

ORTHIDES OP THE HAMILTON GROUP.

The Hamilton group, throughout the extent of its calcareous shales, is
every where marked by the presence of one or more species of Orthis.
The 0. vanuxemi is the most abundant, while two allied species are of
frequent occurrence. In the more eastern localities in the State of New-
York these fossils are less common, and are usually in the condition of
casts of the interior; affording, however, specimens not less instructive
than those where the shells are entire.

In some localities in Western New- York, the prevailing species often
occur in a profusion equal to the more common forms in the Lower Hel¬
derberg group in Eastern New-York.

A. Species of the type of Orthis elegantula, Orthis perelegans, etc., with the ventral
valve nearly flat or depressed-eonvex.

Orthis lepidus, Orthis solitaria.

Orthis solitaria.

PLATE YI.

Orthis solitaria : Hall, Thirteenth Report on the State Cabinet, 1860, p. 60.

Compare Orthis lenticularis, Yanuxem, page 35, this volume.

Shell subcircular, a little transverse : valves unequally convex ; hinge-
. line about two-thirds the greatest width of the shell. Ventral valve
highly convex in the middle and above : beak small, prominent, slight¬
ly incurved ; area low and well defined. Dorsal valve depressed-convex,
most prominent near the umbo, with a broad shallow mesial sinus at
the front, which rarely extends beyond the middle of the valve : beak
small, not prominent ; area linear.

Surface marked by fine radiating bifurcating strise and strong concentric
lines of growth.

46

PALAEONTOLOGY OF NEW-YORK.

At the time of describing this species, I had no authentic specimens of Orthis
lenticularis ; nor was I aware of the variety of forms which I have since obtained
and examined, and referred to that species.

The Orthis solitaria is probably only a variety of. form, or rather a greater
extreme of the subquadrate forms figured on Plate Y of this volume. With a
single individual for examination (no other of the same having been obtained),
there may remain some doubt as to the positive identity ; and I have therefore
permitted the description to remain, the plate having been engraved before those
forms of 0. lenticularis were collected.

Geological formation and locality. In the shales of the Hamilton group : at York,
Livingston county, N.Y.

Orthis lepidus.

PLATE VI.

Orthis lepidus : Hah, Thirteenth Report on the State Cabinet, 1860, p. 78.

Shell small, transversely subelliptical, somewhat ventricose : cardinal
line little less than the greatest width of the shell ; area proportional¬
ly large ; beaks distant. Ventral valve very convex, regularly curved
from beak to base : ventral beak prominent, pointed and slightly in¬
clined. Dorsal valve depressed-convex, marked by a distinct mesial
depression, which, in some specimens, extends nearly to the beak :
dorsal beak small, pointed, hut little incurved.

Surface marked by fine radiating striae, which are crossed by concentric
striae and a few stronger lines of growth.

This is the smallest species of Orthis yet known in the Hamilton group, and
is easily distinguished by the great transverse diameter, the large area, the
prominent ventral beak, and the distinct dorsal sinus. It is of the type of the
preceding species, but differs in its greater width, more elevated ventral beak,
and larger area. The specimens observed do not exceed a quarter of an inch in
width.

The species bears some resemblance to the young of 0. perelegans; but the
beak is more elevated, and the area larger. It is an extremely rare form, having
been found in but a single locality and in few individuals.

Geologial formation and locality. In the shales of the Hamilton group, on the
shore of Canandaigua lake, Ontario county, N.Y.

ORTHIDES OF THE HAMILTON GROUP.

47

B. Species of the type of Orthis hybrida and Orthis oblata.

Orthis vanuxemi, Orthis leucosia, Orthis penelope, Orthis cyclas.

Orthis vairaxemi,

PLATE VI.

Orthis vanuxemi ; Hall, Tenth Report on the State Cabinet, 1857, p. 136.

Shell subcircular or transversely suboval, compressed : hinge-line very
short ; margins of the valves crenulated within from the external striae ;
interior minutely punctate. Dorsal valve convex : beak scarcely dis¬
tinct from the cardinal border, not incurved ; cardinal process promi¬
nent ; area flat or slightly inclined to the ventral area, and about two-
thirds as wide. Ventral valve nearly flat or a little concave towards the
front, moderately convex in the umbonal region : beak small, extending
little beyond the opposite beak, arched, and rarely incurved over the
area ; area very small, less than half the greatest breadth of the shell,
arcuate ; foramen comparatively large, triangular, and partly filled by
the cardinal process of the other valve : teeth prominent.

Surface marked by fine, closely arranged, radiating tubular striae, which
are perforate at intervals, increasing both by implantation and bi¬
furcation, and are crossed by very fine indistinct concentric striae, and,
at greater intervals, by more distinct, concentric, imbricating lines of
growth : entire surface granulate or punctate, under a magnifier. Striae
from twelve to sixteen in the space of two lines near the beak, and
from seven to nine in the same interval near the margin.

The interior of the dorsal valve shows a. strong cardinal process, which
is continued in a prominent rounded median ridge for half the length of
the shell, where it sometimes divides, or gradually becomes obsolete :
there are sometimes visible low transverse ridges, which divide the
muscular impression. The crural processes are prominent, and sustained
below by strong oblique ridges. In the interior of young specimens, the
marks of the external strise are visible nearly or quite to the muscular
impression ; while in older specimens these marks extend little beyond
the margin.

48

PALAEONTOLOGY OP NEW-YORK.

The interior of the ventral valve is marked by a large flabelliform
muscular impression, which reaches from one-half to two-thirds the length
of the shell. The central or adductor impression is sometimes simple,
and sometimes longitudinally divided by a slight median ridge which is
stronger below. In the older shells, the ovarian spaces are pustulose. The
dental lamellae are strong and divergent, supported below by the ridge
which margins the muscular impression. Vascular impressions are rarely
seen, extending beyond the muscular area. Under a lens, the interior
surface is distinctly punctate. In all well preserved specimens, the exte¬
rior shows minute tubular openings in the striae ; and when the striae are
much worn, these also are seen to be tubular; while a farther wearing of
the surface shows more distinctly the minutely punctate character of the
shell.

This species resembles the figures of 0. michilini of Laveille; but, compared
with European specimens thus labelled, it presents many points of difference.

The 0. vanuxemi is the most common and abundant species in the Hamilton
group. The largest specimens have a length of about one inch and one-eighth,
with a width of an inch and a quarter.

Geological formation and locality. In the calcareous and arenaceous shales of
the Hamilton group, in Central and Western New-York. Among the best locali¬
ties, are the shores of Cayuga, Seneca and Canandaigua lakes ; Moscow; Darien,
and Eighteen-mile creek ; ranging through nearly the entire thickness of the
group. In the more arenaceous shales farther east, it is common in the form of
casts. It has been recognized in Maryland and Virginia; and specimens from
Iowa have not been proved distinct from this species.

Ortliis leucosia.

PLATE VI.

Orthis leucosia. : Hall, Thirteenth Keport on the State Cabinet,, 18G0, p. 80.

Shell broadly ovate, greatest width below the middle, somewhat obtusely
pointed at the beak ; cardinal area short and small, being less than
half the width of the shell : beaks approximate. Dorsal valve much
the more gibbous, the greatest convexity above the middle, longitudi¬
nally marked by a median depression which is sometimes obsolete ;

ORTHIDES OF THE HAMILTON GROUP.

49

area scarcely more than half as wide as the ventral area, slightly in¬
clined inwards. Yentral valve gibbous towards the umbo, depressed-
convex in the centre and flattened towards the front ; the front margin
straight, or without sinus ; area less than a line in width ; foramen
very broad, nearly twice as wide as high ; beak slightly incurved and
neatly pointed.

Surface marked by fine, radiating, bifurcating striae, which are crossed
by finer concentric striae, and by more distant subimbricating lamellose
lines of growth. Minute tubular openings are observed upon the surface
of the striae in nearly all conditions of preservation, sometimes giving
a subimbricated appearance to the lines. Besides these, well preserved
specimens show minute pores or puncta, distinct from the punctate
structure oflHhe shell ; while the shell about the margins of these ap¬
pears to have been extended, to form slender seta, the bases of which
are sometimes preserved. In weathered specimens, or in those where
the striae have been partially dissolved by the decomposition of iron
pyrites, these characters do not appear.

The interior of the dorsal valve shows a prominent cardinal process,
which is continued in a strong median ridge for about half the length of
the valve, below which are sometimes seen a few vascular markings. The
impressions of the adductor muscles are, rarely, faintly separated by a
transverse undefined elevation.

The muscular imprint in the ventral valve, which extends for two-
thirds or more of its length, is somewhat broadly oval, flabellate, and
deeply marked by the adductor muscular scar. The external striae usual¬
ly mark the inner margins of the valves, and, in young shells or thin
specimens, are visible as far as the muscular impression.

This species is closely allied to the 0. vanuxemi , and may perhaps prove only
a .variety of that species. In authentic specimens the shape is more ovate, the
cardinal extremities less rounded, and the sides sloping almost directly to near
the middle of the shell ; the dorsal valve is more gibbous, and the umbo and
area are more inclined inwards, as maybe seen by comparing the profiles of figs.
3 e and 3 k, Plate vi, with a corresponding figure 3 e on Plate vii. The yentral
[ Paleontology TV.] 7

5© PALEONTOLOGY OF NEW- YORK.

valve is also more gibbous, and the separated valves are conspicuously deeper
than in 0. vanuxemi.

This form is comparatively rare, occurring in few localities and having a li¬
mited range, while the other has a wide geographical and great vertical range.
In one locality, great numbers of this species have been found limited to a ver¬
tical range of a few inches ; while the other species occurs in the beds above
and below at the same place, with scarcely an individual mingled among these.

Geological formation and locality. In the shales of the Hamilton group, at
Eighteen-mile creek, Erie county ; on the shores of Canandaigua lake, Ontario
county, New- York ; and Cumberland, Maryland.

Orthis penelope.

PLATE YI. *

Orthis penelope : Hall, Thirteenth Report on the State Cabinet, 1860, p. 79.

Shell large, oblate, proportions of length and breadth usually as four to
five, plano-convex ; hinge-line about two-fifths the width of the shell ;
cardinal extremities regularly rounded. Dorsal valve regularly convex,
the greatest convexity about the centre, with a very slight mesial de¬
pression or flattening along the centre : beak small, rising but little
beyond the general outline of the shell ; area little more than half as
wide as the ventral area, not incurved, and lying nearly in a plane
with the anterior margin of the valve. Ventral valve depressed-convex
above, sometimes a little gibbous towards the umbo, flat or often con¬
cave in the middle and below, the front without sinuosity : area in
the larger specimens nearly one-eighth of an inch in width ; foramen
broad, twice as wide as high, and nearly filled by the strong cardinal
process of the opposite valve ; ventral beak obtusely pointed and
scarcely incurved.

Surface marked by fine radiating bifurcating striae, which are strongly
arched upwards near the cardinal extremities, and crossed by fine
concentric lines, giving a slightly rugose appearance in well-preserved
specimens, and beside these are closely arranged lamellose lines of
growth. The radiating striae have often the appearance of being broken

ORTHIDES OF THE HAMILTON GROUP. 51

or interrupted,' from the peculiar manner in which the pores open upon
the surface.

Interior of the ventral valve marked by a subcircular or broadly ovate
flabellate muscular impression, which occupies more than half the
length and breadth of the valve, and, in old specimens, is extremely
thickened from its anterior margin nearly to the border of the palleal
impression ; the ovarian spaces distinctly pitted, pustulose or rugose,
in curving ridges. Dental lamellae strong and prominent, merging below
into the raised border of the muscular impression.

Interior of the dorsal valve showing a strong prominent cardinal process,
which is continued in a median ridge sometimes nearly to the front of
the shell. In some specimens, low transverse ridges separate the ad¬
ductor muscular scars ; while in other specimens, and particularly the
older ones, this division is scarcely distinct, and the muscular impres¬
sion is broadly oval, with its lower margins showing foliate impressions
as in the muscular impression of the ventral valve.

This species reaches a larger size than 0. vanuxemi ; often measuring more than
one inch and three quarters in transverse diameter, while the largest specimens
of 0. vanuxemi seldom measure more than one inch. It differs also in the character
and strength of the radiating strise ; the muscular imprint in the ventral valve is
usually broader and more strongly marked ; the cardinal and brachial processes
of the dorsal valve are stronger, and directed towards the opposite valve; while
these, in 0. vanuxemi , are inclined forwards, or into the cavity of the shell.

In specimens of the larger and medium size, the ventral valve is quite flat or
concave below the middle. The tubular character of the strice is more strongly
developed than in 0. vanuxemi or 0. leucosia; while in the finer punctate texture
of the shell, there is no distinction perceptible. In all the authenticated specimens
of this species, the cardinal line of the dorsal valve is straighter, and the beaks
not approximating. The strong similarity between the three species above named
will render it difficult in many cases to determine them.

Geological formation and locality. In the calcareous shales of the Hamilton
group, at Eighteen-mile creek and Hamburgh, Erie county; Alexander and
Pavilion, Genesee county; York and Moscow, Livingston county; and on the
shores of Canandaigua and Seneca lakes.

52

PALAEONTOLOGY OF NEW-YORK.

Ortliis cyclas.

PLATE VII.

Orthis cyclas : Hall, Thirteenth Report on the State Cabinet, 1860, p. 78.

Shell small, varying from subcircular to transversely subelliptical, mo¬
derately convex : beaks appressed, not distant ; cardinal line rather
less than one-half the greatest width of the shell. Ventral valve convex,
most gibbous near the umbo : beak small, slightly incurved ; area ra¬
ther low. Dorsal valve the less convex, sometimes marked by a shallow
depression : beak very small, slightly projecting beyond the cardinal
line ; area narrow.

Surface marked by strong sharp prominent striae, which are both bi¬
furcated and implanted, often appearing fasciculate near the margin
of the shell.

The largest specimen of this species which I have seen is a little more than
half an inch in length, and aboye six-tenths of an inch in width in its greatest
diameter. The length of the area is about one-third of an inch. The distinguishing
features of this shell are its usually nearly circular form, the sharply prominent
striae, and the comparatively great length of the cardinal line.

Geological formation and locality. In the shales of the Hamilton group at York
in Livingston county ; Pavilion, Genesee county ; near Bellona; and on Canan¬
daigua lake in Ontario county, N.Y.

• Ortliis idonens ( n. s.).

PLATE VII.

Shell subcircular, a little wider than long, both valves convex and nearly
equal in length : hinge-line a little more than one-third the greatest
width of the shell ; the extremities rounded into the general contour
of the shell, which is a little oblate. The dorsal valve is regularly
convex above the middle, with a scarcely perceptible flattening along
the median line, and becoming flattened below : beak small ; not in¬
curved ; area flat, about half as wide as that of the ventral valve.

ORTHIDES OF THE HAMILTON GROUP.

53

Ventral valve convex near the beak, becoming broadly flattened below
the middle, and sometimes (perhaps from pressure) a little concave
towards the margin ; front without (or with a scarcely perceptible) si¬
nuosity ; area of moderate width, a little concave, and the beak slightly
incurved : the foramen is large, and nearly filled by the cardinal process
of the opposite valve.

Surface marked by fine bifurcating subangular striae, which are marked
by poriform openings upon the surface, and with the intermediate space
finely punctate. There are a few lamellose lines of growth in the midde
of the shell, and a larger number on the margin.

This species is one of the type of 0. oblata and 0. vanuxemi , differing from the
latter as 0. discus does from the former. Although its measurements differ but
little from 0. vanuxemi , its expression is that of a more nearly circular shell, and
it has maintained this form from its earlier stages of growth. Owing to this
feature, the striae along the hinge-line curve a little more abrupt upward.

This species differs more distinctly from 0. vanuxemi than either 0. leucosia or
0. penelope; though it is not easy to point out these distinctions, or illustrate
the same in figures. It is probably identical with the species described from the
Corniferous limestone on page 39, and figured on Plate v, f. 5 ; but that one is
a little distorted by pressure.

Geological formation and locality. In the Hamilton group at Moscow, and at
Eighteen-mile creek on Lake Erie.

In species so similar as some of the Orthides of this and other groups,
it is difficult to point out characters by which they may be distinguished.
The measurements of proportions, although often valuable, will be of
little use if too far relied upon ; while the degree of fineness or coarseness
of the striae, or the number of striae within a certain space, will serve to
distinguish species when there is considerable difference in the strength
of these features, but I do not consider that this can be relied upon in
species approaching each other.

I have given below some measurements of proportions of parts, and
of number of strise, of authentic specimens of several species, for the
purpose of showing the degree of variation observed. I should mention,

PALAEONTOLOGY OP NEW-YORK.

54

however, that in the measurement of strise in the space of two lines, on
some of the more finely striated species, it is scarcely possible to include
the same number of striae between the points of the compasses at any

two places upon the surface.

Species. Length. "Width.

Depth.

Length of arei

Striae in the

i. Rear beak.

s space of

Middle.

two lines*

Near front.

Orthis ALSUS - 1.18

1.23

.40

.79

if

8

8

1

« « 1.08

1.24

—

—

AO

8.

. A

* Orthis livia - 1.12

1.21

.40

.57

i

f

6

Orthis idoneus . . 1.07

1.23

.45

.55

if

'11

1

« « .. .80

.96

—

.40

it

11

If

Orthis semele .. 1.24

1.40

—

.88

—

8

8

1 Orthis vanuxemi, 1.03-

1.10

.43

.45

Ah.

AA

2 “ “ .. 1.15

1.28

.55

.60

11

11

V-

8 “ « 1.18

1.23

.46

■ .47

If

To¬

X

4 « “ .. 1.00

1.09

—

.47

If

ll

I

oo

00

1.03

.37

.44

11

H

f

1 Orthis penelope, 1.37

1.59

—

.65

If

11

1 '

2 « “ .. 1.33

1.58

—

.58

11 '

11

1

3 « “ .. 1.43

1.60

—

.73

11

11

X

4 “ “ 1.15

1.36

—

.58

11

11

f

5’ « « .. 1.17

1.39

—

—

If

If

f

6 « “ 1.17

1.31

—

.54

AS.

AS

8.

1 Orthis leucosia, 1.02

1.04

.52

.46

11

TO

T

2 « « .. 0.79

0.83

.40

.31

11

If

t

3 “ “ .. 0.88

0.95

.40

.37

If

If

f

4 “ .. 0.95

1.02

.‘48

.34

A4

±2

f

Orthis idas . 1.53

1.71

.40

1.14

If

f

m

1 Orthis lenticularis, .77

.77

.47

.54

S"2

T4=is

2 “ “ .. .59

.62

.28

.44

M.

ft

TT^T8

Orthis propinqua, .83

.98

.62

.55

-■ -

TO

I

1 “ « .

lf+

AA*

If

2 “ “ .

—

If

— ‘

* In these three columns, the upper figures indicate the dorsal valve, and the lower the ventral valve,
f Besides several finer intermediate ones. J Counting the intermediate ones.

ORTHIS OF THE TULLY LIMESTONE.

•55

ORTHIS OF THE TULLY LIMESTONE.

There is a single species of Orthis, the 0. tulliensis, which is quite cha¬
racteristic of the Tully limestone. It is unknown in the Hamilton group
in New- York, or in any rock below. Though of the type of 0. multistriata
and 0. propinqua, it is usually readily distinguished from either of these in
its exterior characters, but more particularly in its muscular and vascular
impressions. Its geographical distribution is very restricted, so far as
known. It occurs in Onondaga and probably in Madison county, and in
Cayuga and Seneca counties ; while it is not found on Canandaigua lake,
or at any point west within the State of New- York. The Orthis iowensis
of the Hamilton group in Iowa is a very similar and perhaps identical
species, its differences being possibly due to physical causes and wide
geographical separation.

OrtSiis tulliensis.

PLATE VJI.

Orthis tulliensis : Vanuxem. Geol. Report Third District New- York, 1843, p. 163.

Compare Orthis iowensis, Geol. Report of Iowa, Part ii,' p. 488.

Shell rotund, transverse or nearly subcircular, the length and breadth
about as seven to eight or eight to nine, the depth varying from two-
thirds to seven-eighths of the length ; hinge-line and area a little less
than two-thirds the width of the shell. Dorsal valve the larger and
very gibbous, the greatest gibbosity a little above the middle, sloping
very abruptly to the beak, and more broadly curving to the front and
• sides : front sinuate in older specimens ; the area inclined towards the
- area of the opposite valve, and the beak distinctly incurved, extending
slightly beyond the limit of the area. Ventral valve somewhat gibbose
above the middle, becoming gradually depressed, and marked by a
broad undefined sinus which gives a more or less curved outline to the
front according to the gibbosity of the shell : area elevated and slight-

m

PALAEONTOLOGY OF NEW-YORK.

ly incurved, the beak gently incurved over the area (and, in some

specimens, more incurved than is shown in the figures) ; the beaks of

the two valves are approximating.

The surface is marked by fine equal or subequal striae, and a few
scarcely lamellose concentric lines of growth, the bifurcations of the
striae producing scarcely visible inequalities. The texture of the shell is
punctate. The number of striae in the space of two lines varies from
twelve to sixteen.

The cast of the dorsal valve shows a broadly ovate muscular impression,
which is slightly divided by a longitudinal depression : from the lower
part of this muscular impression the vascular markings extend in a
narrow band, slightly spreading and diverging below. In this respect it
differs from the 0. propinqua and 0. multistriata, where the muscular im¬
pression is usually more quadrate, and the vascular impressions are al¬
ways diverging from the muscular area and are more divided. In some of
the younger specimens of O. propinqua , the muscular impression of the
dorsal valve is more ovate than that given fig. 39, Plate v.

The muscular impression in the ventral, valve of this species is narrow
ovate-lanceolate, with the limits strongly defined.

Externally this species differs from 0. propinqua in its finer and more even
strise, as well as in its external form ; the greatest width in that species being
below the middle, while the margin thence, towards the hinge-extremities, is
more direct. In 0. tulliensis, the greatest width is about the middle, and the
outline is pretty regularly curved.

The figures on Plate vii illustrate the usual form and character of adult speci¬
mens. The younger ones are less gibbous, but they are usually in such imperfect
condition that my collections have not afforded specimens fit for illustration.

Geological formation and locality. In the Tully limestone at Tully and Tinker’s
falls, Onondaga oounty, and at Ovid in Seneca county.

ORTHIDES OF THE PORTAGE AND CHEMUNG GROUPS.

57

ORTHIDES OF THE PORTAGE AND CHEMUNG GROUPS.

In the Report on the Fourth Geological District of New- York, I de¬
scribed one species of Orthis from the Portage group, and two species
from the Chemung group, and identified a third with a European species.
The specimen from the Portage group consists of a partial cast, which is
finely striated, resembling the surface-characters of Orthis ; but a farther
examination proves it to belong to a distinct genus : and the Portage
group, therefore, has not thus far furnished to the collections any species
of Orthis.

In the Chemung group, within the limits of this State, we know several
species of this genus, which occur more commonly in beds of the lower
and central parts of the formation. In the higher beds of this group, we
have at this time few evidences of the occurrence of Orthis ; while several
species of Productus and Spirifer are seen in the central and higher beds
more frequently than in the lower part of the group.

In their geographical distribution, the larger and more conspicuous
species appear to be comparatively limited, since I have not found them
in the eastern prolongation of the group in Delaware county; nor
have they been often found in Chautauque county. One or more of the
species are common in many localities in Tioga, Chemung, Steuben
and Allegany counties, and less frequent to the westward ; while some
smaller forms are not uncommon in the neighborhood of Leon, Randolph
and Conewango in Cattaraugus county. So far as investigations have
progressed, it has not been found practicable to identify the individual
beds containing these fossils to the west of Cattaraugus county ; and at
localities Still farther west, we find a different association of fossils in
beds which appear to be in the same horizon.

Note. The investigations in the Chemung group are unfinished, and we may
obtain farther information before the close of this volume. In the mean time, the
necessity of printing obliges me to send the descriptions of these species to the
press.

[-Palaeontology IV.] 8

38

PALEONTOLOGY OP NEW-YORK.

Orthis caiiiiatao

PLATE VIII

Orthis carinatd : Hall, Geol. Report Fourth District New-York, 1843, page 267, f. 1.

Shell transverse, often much wider than long, subplano-convex : hinge-
line nearly or quite equal to three-fourths the greatest width of the
shell, and about equal to its length ; cardinal extremities rounded. The
dorsal valve is very convex or gibbous, with a deep rounded sinus in
the median line, abruptly curving towards the cardinal line and some¬
what more gently to the front, depressed and scarcely flattened at the
cardinal extremities. Ventral valve nearly flat, or rising from the base
to the umbo with little convexity : median line carinate, with a strong
and defined angular ridge, front abruptly sinuate ; area comparatively
narrow, a little curved near the beak : foramen wide.

Surface marked by fine radiating striae, which increase by bifurcation
and interstitial additions, and are strongly curved upwards to the
hinge-line : texture punctate. The specimens are mainly casts, and the
lines of growth are obscure.

The cast of the dorsal valve shows a wide subquadrate muscular im¬
pression, divided by a rounded median ridge, and transversely by a low
ridge on either side, after the manner of 0. elegantula and others of that
type. The socket plates are strong and very divergent, and the cardinal
process is apparently triplicate : the area is narrow and flat.

The cast of the ventral valve is nearly flat on the sides, with a defined
angular carina along the median line. The muscular impression is sub-
quadrate, deeply bilobed below, and slightly lobed at the sides. The dental
lamellae are strong and triangular.

In specimens which have suffered no compression, the length is about
three-fourths the width ; but in some individuals, the width is nearly
double the length. The specimens are usually more or less distorted by
pressure, and are likewise mostly in the condition of casts ; so that all
the characters of the species cannot be given. The dorsal valve is more
convex than others of this type of Orthis, and the median sinus more
strongly developed.

ORTHIDES OF THE PORTAGE AND CHEMUNG GROUPS.

In many of its characters this species assimilates with the following, and it is
possible that intermediate forms may connect them, though I have not at present
the means of making this comparison fully.

Geological formation and locality. This species occurs in some beds of brown
sandstone near Paintedpost, New-York, and has not been obtained in any other
locality.

Ortliis tioga ( n. s.).

PLATE VIII.

Referred to Orthis interlmeata, Sowerby, in Report on the Fourth Geological District New-York, p. 268.

Shell transverse, broadly elliptical, about two-thirds as long as wide :
length of hinge-line a little greater than half the width of the shell ;
the extremities rounded into a general curved outline. Dorsal valve
convex, the greatest elevation near or above the middle on each side
of a well-marked mesial sinus ; sometimes a little flattened at the sides,
and regularly curving to the front. Ventral valve very gently convex,
with sometimes a slight mesial elevation : area of medium width, with
the beak slightly incurved ; foramen wide.

Surface striated : striae angular, often fasciculate, curving upwards on
the hinge-line.

The shell is rarely preserved ; but when it is seen, the striae are an¬
gular, and every second one in the upper part of the shell, and every
third or fourth one in the lower part of the shell, are stronger and more
prominent : concentric striae fine and closely arranged. In the casts, the
character of the striae is tolerably well preserved in the fasciculate ar¬
rangement, and in the curving upward at the sides and on the hinge-line ;
while on the margin, they are much more strongly impressed than on the
middle of the cast. When the cast is preserved in fine shale or shaly
sandstone, the surface is minutely punctate ; and the shell, when pre¬
served, has the same character.

The muscular impression in the dorsal valve is usually but faintly
defined in the casts, which preserve the impression of a strong cardinal
process, bifid at the extremity. The socket plates aue strong and widely
diverging, and the area is extremely narrow. In the cast of the ventral

PALAEONTOLOGY OP NEW- YORK.

m

valve, the muscular impression is subpentagonal, deeply bilobed below ;
the bases of the divisions rounded, and the sides slightly indented. The
area is narrow, incurved in the middle, and extends about two-thirds the
width of the shell.

This species resembles Orthis carinata; but among numerous specimens col¬
lected, none of them are more than two-thirds the length and breadth of the
specimens of that species known to me. The dorsal valve is not so gibbous as in
0. carinata , nor the sinus so well defined ; while the striae are much stronger upon
the surface of the cast. Notwithstanding these differences, however, I am prepared
to find specimens which may show the unity of these forms as one species.

This species occurs in the shaly sandstone and shale, and sometimes in semi-
calcareous bands, near Factoryville in Tioga county, along the Cayuta creek, at
Chemung-narrows, near Elmira, at Horseheads, and at Buck’s quarry. It occurs
also in Allegany county at Philipsburgh, and near Leon and other places in
Cattaraugus county, New- York.

Ortliis imprcssa.

PL ATE VIII.

Orthis impresses : Hall, Geol. Report Fourth District New-York, 1848, page 268, and fig. 2, p. 267.
Compare Orthis tulliensis, Vanuxem, Geol. Report Third District, p. 55.

Shell rotund. Dorsal valve very gibbose, wider than long, sinuate in
front : hinge-line about two-thirds the width of the shell. Ventral
valve moderately convex at the sides, somewhat flattened on the umbo,
with a broad undefined sinus which becomes deeper towards the front,
the margin of the shell being sometimes abruptly incurved : area of
moderate height, a little incurved at the beak.

The surface is very finely and evenly striated, and the texture of the
shell is minutely punctate.

The cast of the dorsal valve shows a strong, somewhat quadrilobate
muscular impression, limited by strong and widely diverging socket-
plates, with the vascular impressions somewhat narrow and extending
below it to the margin of the shell. The surface of the cast preserves fine
even striae. The cast of the ventral valve is broadly sinuate in the middle
below, with a triangular or subovate deeply bilobed muscular impression,
which is subject to considerable variation in form and proportions.

ORTHIDES OF THE PORTAGE AND CHEMUNG GROUPS.

61

This species has many characters in common with Orthis tulliensis; differing
chiefly in the broad flattened or depressed ventral valve, which has a broader and
more defined sinus along the centre, and also a large and deeply divided muscular
impression which is sometimes lobed. It is possible that these characters, which
are subject to variation in the specimens before me, maybe only differences caused
by the conditions of life in the 0. tulliensis at a later geological period.

The Orthis tulliensis occurs in the Tully limestone in the central part of the
State, principally in Onondaga and Cayuga counties. It has not been found in the
Hamilton group ; and in the thin bands of Tully limestone it is associated chiefly
with Rhynchonella suicuboides , a fossil restricted, as far as known, to that horizon.

Between the Tully limestone and the Chemung group we find interposed the
Genesee slate and Portage group, which together make a thickness of eight
hundred to one thousand feet : in these beds, no species of Orthis is at present
known.

The species of this type, from the 0. multistriata of the Lower Helderberg
group to this one from the Chemung group, bear many characters in common, and
under some circumstances it might be difficult to distinguish them. The 0. multi¬
striata has subequal striae, approaching in this character to the 0. tulliensis , which
it likewise resembles in form ; but the beak of the ventral valve is more produced,
and the area is less divergent from the plane of the longitudinal axi§ : while the
dorsal area is not so high, and the sinus in front is more abrupt. These features
are shown in figs. 2 a - 2 i of Plate xv, Vol. iii, Pal. N.York. In the same species,
figs. 2 k - 2 r, the muscular areas are similar to those of 0. tulliensis; that of the
ventral valve being a little more strongly lobed and more angular in outline, while
that of the dorsal valve is but slightly different in form. The vascular impressions
proceeding from the base of the muscular area are, however, quite distinctive in all
the casts seen, and may be compared in figs. 2 l, o, p ( loc . tit.), with fig. 5 of Plate
vii, Yol. iv, which, represents the constant character of 0. tulliensis as well as of
the western form, 0. iowensis. The differences between the 0. tulliensis and 0.
propinqua have already been pointed out, and, in a considerable number of indivi¬
duals, these characteristics are reliable 5 but when we find crushed and distorted
specimens of the two species, they are not easily distinguished.

The Chemung specimens are never entire : they are generally distorted, and the
shell is rarely preserved to any extent. In the distorted specimens, the muscular
impressions of course participate in the abnormal appearance ; but in several well
preserved specimens of the ventral valve, there is a much greater variety of form
and proportions of this part than has been observed in any one of the species
before described.

62

PALAEONTOLOGY OP NEW-YORK.

Geological formation and locality. This species occurs in the shaly sandstone
and semicalcareous bands of the Chemung group, at Ithaca and Cayuta creek ; at
Chemung-narrows, and near Elmira ; also at Philipsburgh in Allegany county, and
at Leon and elsewhere in Cattaraugus county.

Ortliis leonensis ( n. s.).

PLATE VIII.

Shell transverse, somewhat broadly elliptical. Dorsal valve with a dis¬
tinct longitudinal sinus, and having the base more or less distinctly
truncate in the middle ; the sides, for a little way below the beak, are
sometimes straight, but usually curved. Ventral valve regularly convex
in the middle and upper part, sometimes a little depressed towards the
base and elevated along the median line : muscular impression oval
or ovate, and sometimes visibly lobed. The area is much shorter than
the width of the shell. The surface is marked by rather strong strise,
which are more or less preserved upon the cast.

The strength of the muscular markings, as well as of the striae, vary
considerably, depending on the thickness or strength of the original shell.

The species bears some resemblance to the young of 0. tioga; but the muscular
impressions are different, and the sinus in'the dorsal valve is quite unlike that one.
A considerable number of specimens have been found, but among them there are
no large individuals, and it would appear that the species never attained a large
size.

Figs. B, 4 & 5 of Plate vill are illustrations of the dorsal valve.

Figs. 6 & 7 are the ventral valves.

Fig. 8 represents the surface of a larger ventral valve which may possibly be of this species,
as it occurs in the same association.

Fig. 1, O. leonensis? is an enlargement of a cast of the ventral valve, where the muscular
impression is much stronger than usual, and the surface below is much flattened ; a
feature which may possibly have come from great thickening of the shell, or it may
be a different species.

Geological formation and locality. In the arenaceous beds of the Chemung
group, near Leon, Conewango, and Randolph in Cattaraugus county.

ORTHIDES OP THE PORTAGE AND CHEMUNG GROUPS.

03

Orthis thiemei ?

PLATE VIII.

Orthis thiemei? White, Journal of the Boston Soc. Nat. History, Yol. vii, p. 231.

Among the Orthides from Cattaraugus county are some casts, that
bear a very close resemblance to this species of the arenaceous beds at
Burlington, Iowa. The ventral valve is flattened or depressed in the
middle below the muscular impression, and the sides are narrowed to¬
wards the hinge-line, which is shorter than the width of the shell.

The casts of ventral valves referred to this species occur in the same beds with
0. leonensis; and it is not impossible that the dorsal valves like fig. 5, Plate viii,
may belong to the same.

Geological formation and locality. Arenaceous beds of the Chemung group, near
Leon, Napoli and New-Albion, Cattaraugus county.

Orthis leucosia?

PLATE VIII.

Compare OrthiMeucosia , Plate vii, p. 48, this volume.

Figs. 9 and 10 are representations of the exterior of the shell of a
dorsal valve, and the cast of a ventral valve, which occur in a specimen
of olive shaly sandstone, labelled as from Steuben county. The specimen
contains, besides these, the impression of a Productus and of Leiorhyn-
chus, giving the character and aspect of the Chemung rocks ; but it is
the only specimen in which this Orthis has been observed, and it seems
to me possible that it may have been derived from some of the higher
and more arenaceous beds of the Hamilton group in the eastern part of
the State, where the lithological characters of the two formations are
very similar.

64

PALAEONTOLOGY OF NEW-YORK.

GENUS StREPTORIIYACIIUS (King).

The Genus Streptorhynchus was published in 1850 by Prof. King, to
include some peculiar forms of strophomenoid shells ; one conspicuous
character of which is that the umbone of the larger valve is irregularly
twisted. The genus possesses features somewhat intermediate to Orthis
and Strophomena ; and for want of a full understanding of these charac¬
ters, the species have been referred, first by Davidson, and after him by
other authors, to the Genus Orthisina. Regarding the twisted or distorted
beak as one of the essential features of the genus, there are regular forms
having internal characters corresponding with the typical species of the
genus, which on the one side have been forced among the Orthis, while
others have been placed among Strophomena. -

As at present constituted, the genus will include such forms as I have
described in the third volume (Pal. New-York) under the names Stropho¬
mena woolworthana and S. radiata, which are probably identical species.
Going back to the Niagara form S. subplana, we find that it also may be
included under the Genus Streptorhynchus ; and among the Lower Silu¬
rian forms, Strophomena recta, S. defleda, S. filitexta* and some others, may
be included in the same group ; these latter showing the lowest indica¬
tions of those features of the hinge-structure which are more strongly
developed in the species of later geological periods.

The shells of this genus are semicircular or semielliptical, concavo-
convex or plano-convex, and sometimes with both valves convex : they
are externally striated with rounded bifurcating threadlike strise, which
are crossed by fine concentric lines ; and in some forms the stronger
striae are distant, with finer radiating and concentric striae Gancellating
the intermediate spaces. The ventral beak is sometimes produced and
bent or twisted, and the fissure beneath the beak is closed or partially
closed by a solid deltidium, while the area is subject to great variation.
A narrow area often exists on the dorsal valve, but this is not a constant
character.

* See Sixteenth Report on the State Cabinet, 1863. ,

GENUS STREPTORHYNCHUS.

63

I shall endeavor to show, in another place, that the species now refer¬
red to this genus may be arranged in three natural groups, though it may
be questioned whether this limitation can always be determined by the
exterior characters of specimens.

In the Report on the Fourth Geological District (1843, p. 266), I de¬
scribed, under the Genus Strophomena, three species ( S. bifurcata, S .
arctostriata and S. pedinacea) which now prove to belong to the Genus
Streptorhynchus. These determinations and descriptions were made from
few specimens, but the characters were unlike, and were deemed suffi¬
ciently constant to entitle them to specific distinction. Larger collections
of specimens have enabled me to make more extensive comparisons, and
I am now convinced that these forms graduate into each other, and even
take a much wider range than was exhibited in the specimens illustrated.
I am moreover satisfied that the Strophomena chemmgensis of Conrad is a
Streptorhynchus, and specifically identical with those just enumerated,
having precedence in point of time.

In the Tenth Report on the State Cabinet (1857), I described Orthis
perversa , which belongs to the Genus Streptorhynchus ; and in the Report
for 1860, I described Orthisina arctostriata and 0. alternata, both of which
are of the Genus Streptorhynchus. In the same year, Mr. Billings
described the Streptorhynchus pandora of the Corniferous limestone ; an
appropriate name, perhaps, when we reflect that this is but another form
of a species to which all those just mentioned must be referred.

More extensive collections have shown that it is quite impossible to
accumulate any considerable number of specimens of any one of these
types, without encountering variations which lead to other forms lying
intermediate to that one and the other most nearly allied form, until
finally it becomes impracticable to draw lines of specific distinction
between them.

To begin with the oldest form at present included in this group, the
S. pandora , which occurs in the Schoharie grit and Corniferous limestone,
we have usually, but not always, a symmetrical form, differing but little
(if at all) from S. woolworthana of the Lower Helderberg group. We are
able to trace this form in the Hamilton group, where, although rarely
[ Paleontology IV.] 9

PALAEONTOLOGY OF NEW-YORK.

attaining the dimensions which it has in the limestone below, it possesses
nevertheless all the essential characters of that one in its symmetrical
form, and can also be traced into the unsymmetrical forms where the
area is unequal and the beak distorted, but where no two individuals are
precisely alike. From these unsymmetrical forms which I have termed
S. ( Orthisina ) arctostriata, to those where the striae are more unequal, the
gradation is imperceptible ; and the S. ( 0.) alternata, in its typical form,
is not more abundant than are the intermediate varieties.

In the Chemung group, we have a much greater degree of variation
among those which I have referred to the same species. The symmetrical
forms, like S. pandora of the Corniferous limestone, can be traced every¬
where ; and in the arenaceous beds, they sometimes so much resemble
those of the Schoharie grit, that specimens laid together might not be
readily separated. We find among these a greater or less degree of pro¬
minence in the muscular impressions, or of the ridge dividing the mu¬
scular impressions, and also of the cardinal process, which may have a
greater or less extension, and the small ridge between the two branches
of this process may be prominent or otherwise. From these forms there
is a very simple gradation to such as S. bifurcatus , where the strise are a
little stronger and more regularly bifurcating : these are often nearly,
but rarely quite, symmetrical. The type of S. pectinacea is readily reached
by a partial suppression of some of the striae and a greater development
of others ; leaving the larger and more prominent ones with two, three or
more smaller ones between them.

Such forms as S. arctostriatus have the striae nearly equal, and quite
thin and sharply prominent ; but even in these there are finer inter¬
mediate striae, but the interspaces are so nearly equal that the surface
presents a pretty uniform aspect, though there are many gradations.
Specimens of this kind have usually broad convex dorsal valves, which
are sometimes depressed in the centre.

In the form of S. pectinacea, we have a near approach to the Orthis in-
equalis of the sandstones beneath the Burlington limestone in Iowa and
elsewhere. The Burlington specimens are usually very symmetrical ; but

STREPTORHYNCHUS.

©7

the general form, and the alternation of coarser and finer stria©, corre¬
spond very nearly with the specimens in the Chemung group of New-
York ; and with the materials before me, I can find no specific distinc¬
tion.

The variety of forms heretofore described as species have been studied
at different times and under different circumstances ; and it has only
been after the entire series from the successive formations were brought
together, with large accessions of individuals, that their true relations
could be established.

Two other species of Streptorhynchus have been described from the sandstone
of Burlington, Iowa. One of these, in a single specimen examined, presents some
marked differences ; but having no extensive collections from that place for com¬
parison, I do not know what variation either of them may present on farther
examination.

Streptorhynchus cliemungensis.

PLATES IY, IX & X.

Strophomena chemungensis : Conrad, Jour. Acad. Nat. Sciences, Vol, viii, pa. 357; pi. 14, f. 12. 1843.
Strophomena bifurcata : Hall, Geol. Rep. 4th Dist. New- York, p.266, f. 2. 1843.

Strophomena arctostriata : Hall, Ibidem, p.266, f. 3. 1842.

Strophomena pectinacea : Hall, Ibidem, p. 266, f. 4. 1842.

Orthis perversa : Hall, Tenth Report on the State Cabinet, p. 97. 1847.

Streptorhynchus pandora : Billings, Canadian Journal, [N.S.], No.xxvii, p.226. 1860.

«< “ Billings, Geology of Canada, p.369. 1863.

Orthisina arctostriata : Hall, Thirteenth Report on the State Cabinet, p. 80. 1860.

Orthisina alternata : Hall, Ibidem, p. 81. 1860.

Orthis inequalis and Orthis pfavus : Hall, Geol. Report of Iowa, Part ii, pa. 49, pi. 2, f. 6.

The following is the description of the species given by Mr. Conrad :
“ Semiorbicular. Inferior valve ventricose : superior valve slightly con-
“ cave, with a prominent umbo ; radii very numerous, prominent, sub-
“ equal ; umbo of inferior valve ventricose, summit not prominent ;
“ hinge-angles nearly rectangular ; margins extending in a very regular
“ curve from the cardinal extremities.

“ Locality : Chemung-narrows, New-York. Devonian.”

This description is applicable to many of the specimens of the Chemung group,
but the figure given is proportionally longer than those among my collections.
There is, however, no other species in the Chemung group to which the description
applies.

@8

PALEONTOLOGY OF NEW-YORK.

Var. A. Strcptorliyiiclms pandora.

PLATES IY & IX.

Streptorhynchus pandora : Billings, Canadian Journal, p. 226. 1860.

•< “ Billings, Geology of Canada, p.369. 1863. '

Compare Streptorhynchus [Sir oph omen a] woolworthana, Hall, Tenth Report State Cabinet, p. 8. 1857.
“ “ “ “ Hall, Pal. New York, Vol.iii, pa. 192, pi. 16,

f. 1 & 2. 1859.

This shell, in its symmetrical form is somewhat semioval, the length and
width being about as four to five. A well-formed specimen, of one inch
in length, measures one and a quarter inches in width : hinge-line
equal to the greatest width of the shell, and forming right angles
with the sides, which are usually nearly straight ; the front broadly
rounded : cardinal extremities sometimes a little salient, and some¬
times rounded. Ventral valve convex on the umbo, the greatest con¬
vexity being at the apex, from which the surface slopes in a regular
plane to the sides and middle of the shell, becoming slightly concave
below the middle and along the front : area large triangular, extending
the entire length of the hinge-line, and inclining over the dorsal valve
at an angle of about 110°. The foramen has been large, about twice as
wide at the base as the height, and is closed by a convex deltidium.
Dorsal valve moderately convex, a little flattened towards the cardinal
extremities, and curving towards the sides and front ; area narrow and
linear.

Surface striated by numerous fine strongly elevated striae, which are
increased by bifurcation and interstitial additions, and crenulated by
fine closely arranged concentric striae.

The interior of the ventral valve is marked by strong dental lamellae
and a broad flabellate muscular impression, which, in well-preserved
specimens, shows the cordiform imprint of the adductors, and a short
low mesial septum in the upper part.

The interior of the dorsal valve preserves deep dental sockets, with
thick socket-plates which support the duplicate cardinal process, each
division of which is grooved at the extremity. There is likewise a small

STREPTOftHYNCHUS. 69

process between the two branches of the cardinal process ; and below
the hinge-line, the flabelliform muscular impression is divided by a low
rounded mesial longitudinal ridge or obsolete septum.

The ordinary size of specimens, in the Corniferous limestone, is about
one inch in length by one and a quarter inches in width ; while others
measure one inch and an eighth in length, by an inch and a half in width.
The largest individual observed is a cast in Schoharie grit, which mea¬
sures nearly two inches in width.

I have referred this species to the S. pandora of Billings, with which it cor¬
responds in general form and character; though the author remarks that “Our
“ shell closely resembles S. crenistria in external form, but differs in not having
“ the radiating striae crenulated, and further in the form of the occlusor muscular
“ impressions in the dorsal valve. According to Davidson’s figure, there is a small
“ process between the two branches of the cardinal process, which does not exist
“ in ours.”

The radiating striae, in all this group of shells that have fallen under my ob¬
servation, are crenulated by concentric striae ; and in well preserved specimens of
this species, these crenulating striae are very distinct. The median process is well
preserved in our specimens, and forms one of the slight distinguishing features
between it and S. woolworthana; though I am not disposed to regard this as a
constant character, or one of specific importance.

Externally there is very little difference between the S. woolworthana of the
Lower Helderberg, and the species under consideration in its symmetrical forms.
Among the few differences observable are the slightly depressed apex of the ven¬
tral valve, giving the greatest elevation a little below that point in the Lower
Helderberg species ; while the area is narrower on that valve, and a little wider
on the dorsal valve. The striae are perhaps a little finer in S. pandora , but these
characters are subject to much variation. In the interior, the muscular impression
of the ventral valve of S. woolworthana is proportionally a little larger, and that
of the dorsal valve perhaps not so distinctly defined ; but this feature may vary
from difference in the thickness of the shells. In the dorsal valve of S. pandora , the
socket-plates are stronger than in the Lower Helderberg species, and are thickened
about the base of the cardinal process, projecting beyond the line of the area,
while the processes are not (usually) each doubly grooved as in S. woolworthana;
and while in that one there is no median process, the Upper Helderberg species
preserves that feature very distinctly, often reaching as high as the lateral divisions
of the cardinal process.

7 O

PALAEONTOLOGY OF NEW-YOKK.

Notwithstanding these slight differences, I feel disposed to recognize the
two as distinct ; though, adopting the line of argument which has been used in
regard to the Lower and Upper Helderberg Strophodontm*, I should be compelled
to regard the S. pandora as identical with S. woolworthana. There will be found,
moreover, among the species of several genera of the Brachiopoda from ihe Lower
and Upper Helderberg formations, a like degree of similarity as I have already
shown to exist between the Niagara and the Lower Helderberg species.

The conditions prevailing during the epoch of the Upper Helderberg formation
were very similar to those during the Lower Helderberg, the two being separated
by the Oriskany sandstone and Cauda-galli grit. There was, during the older period,
a greater amount of shaly matter deposited than during the later period, which is
almost wholly calcareous, and we have in the entire fauna an adaptation to these
conditions.

The S. pandora first appears in the Schoharie grit, where it occurs in considerable numbers,
although generally in the condition of casts. It has, in this part of the formation, attained a
diameter of nearly two inches in some of the larger specimens. Figs. 11 - 19 of Plate iv
represent its usual condition in this rock. Fig. 12 is drawn from a cast of a ventral valve,
made in a natural mould in the stone. Figs. 11, 15 & 16 ar casts of the dorsal valve, while
13 & 18 are casts of the ventral valve. Fig. 14 is an artificial mould of the interior, from a
cast in stone, and does not fully represent the cardinal process. Fig. 19 represents a specimen
with the sides more regularly curved than usual.

The figures on Plate ix, from 18 to 25 inclusive, are of specimens from the Corniferous
limestone ; showing the dorsal, ventral, and profile views of a symmetrical specimen, with the
interior of the two valves, hinge-line, etc.

The figs. 19 - 23 of Plate x are illustrations of the casts of symmetrical forms from the
Chemung group, and which differ in no essential degree from the S. pandora of the Corni¬
ferous limestone.

The casts from the Schoharie grit show stronger muscular impressions, owing to the thicker
shell ; while the Chemung forms, having lived among sediments containing little calcareous
matter, have had a thinner shell, and consequently the muscular imprints are less conspicuous
in the cast.

Geological formation and locality. In the Schoharie grit at Schoharie, Knox¬
ville, Clarksville and other places, and in the Corniferous limestone at Clarksville
and Schoharie; at Eastman’s quarry south of Utica; in Ontario county, and at
Clarence-hollow and Williamsville in Western New-York ; and in Canada West;
being coextensive with the Limestone formation in this State and Canada.

Billings in Canadian Journal, July, 1861.

STREPTORHYNCHUS.

71

Var. B. Streptorhynchus arctostriata.

PLATE IX.

Orthisina arctostriata : Hall: Thirteenth Report on the State Cabinet, 1860.

Shell, semicircular or semielliptical, frequently unsymmetrical, the
proportions of length and breadth varying in different individuals :
hinge-line straight, nearly or quite equal to or greater than the greatest
width of the shell ; sides nearly rectangular to the hinge-line, or
curving inwards. Ventral valve more or less convex towards the umbo
and sometimes in the middle, curving downwards or flattened towards
the front and sides of the shell : beak often distorted ; area vertical
or inclined forwards or backwards, usually unequal on the two sides of
the foramen, which is closed by a strong convex deltidial plate. Dorsal
valve depressed convex, sometimes nearly flat and sometimes very
convex, with a narrow linear area : socket-plates strong, and supporting
the cardinal process, which is double and has sometimes a faint ridge
between the two divisions, which are themselves very short.

Surface marked by sharp close radiating crenulated striae, which increase
mainly by interstitial additions.

The shells which I have heretofore referred to this species are represented by
individuals varying from one-fourth to three-fourths of an inch in length, and having
a width of from one-fourth to one-third greater than the length.

The examination of a larger collection than I had before me when the species
was first described, has shown that the convexity of the ventral valve is very
variable : the extent of the area is likewise subject to much variation; and the
beak is sometimes symmetrical, and varies from extreme distortion to a scarcely
perceptible obliquity of the apex. In some specimens there are strong lamellose
lines of growth, and in others these lines are scarcely visible. The dorsal valve
varies from nearly flat to very convex ; and in some, specimens the length and
breadth are almost equal, while the cardinal process is scarcely developed beyond
the plain socket-plate, which is bent outwards, and sometimes scarcely divided
at the apex. The surface strise are, in some specimens, more rounded and pretty
equally developed, while in others they are very sharp and unequal. Finally, we
can trace the gradation from the unsymmetrical and distorted specimens, to those
which are not distinguishable from well-marked specimens of S. pandora as it
appears in the Schoharie grit. •

72

PALEONTOLOGY OP NEW-YORK.

These variations are illustrated on Plate ix, where figures 1 & 2 are typical forms of the
species, in some of which the area is inclined forwards.

Pigs. 3, 4 & 5 are views of dorsal valves which are proportionally longer, but have a regular
convexity.

Figs. 6 & 7 are of a larger dorsal valve of similar form, but more irregular exterior.

Pigs. 8 & 9 are the dorsal and ventral valves of a slightly distorted specimen.

Fig. 10 is a ventral valve which is slightly unsymmetrical.

Pig. 11 is a symmetrical ventral valve, which has the form of area and muscular impression
of S. pandora.

Pig. 12 is an enlarged figure from a cast in arenaceous shale. The striae appear coarser than
in the softer shale.

In a slab with numerous specimens, the apices of some are a little distorted, and others are
quite symmetrical.

Geological formation and locality. This variety occurs in the Hamilton group,
at York, Moscow, Pavilion, Darien, Canandaigua lake, and Bristol, Ontario county ;
and near Tully, Onondaga county.

Var. C. Streptorhynchus perversa.

PLATE IX.

Orthis perversa : Hall, Tenth Eeport on the State Cabinet, 1857, p. 97.

Orthisina alternata : Hall, Thirteenth Eeport on the State Cabinet, 1860.

Shell subelliptical, wider than long ; the cardinal extremities rounded,
and the hinge-line less than the width of the shell. Length and width
about as two to three ; the sides curving shortly, and the front broadly
rounded. The ventral valve is very convex at the umbo and the beak
distorted, somewhat depressed below the umbo, and nearly flat or un¬
equally depressed-convex on the middle and lower part : area nearly
vertical, with the apex inclined or arcuate ; foramen closed by a pro¬
minent convex pseudo - deltidium. Dorsal valve rounded, convex or
sometimes gibbous; the greatest convexity above the middle, and
sloping abruptly to the hinge-line, sometimes flattened or a little de¬
pressed in the middle towards the front.

Sueface marked by distant elevated striae which increase mainly by
interstitial additions, and the intermediate spaces are crossed by ele¬
vated concentric undulating strise.

In my description of this species, I remarked that it “is of the type of Orthis
“ umbraculum , and presents the irregularities of form common to that shell,”

STREPTORHYNCHUS.

*3

The species described as Orthisina alternata is not distinct from this ; and al¬
though without larger collections of specimens, it is impossible to draw lines of
specific distinction, yet the prevailing forms may be separated into two groups ;
leaving a few which are not so readily referred to either of them, or which may
be intermediate forms, uniting the two and likewise including S. pandora.

I have adopted the name S. pandora as applicable to the symmetrical forms of
the Schoharie grit and Corniferous limestone, and some of those in the Chemung
group ; while the S. arctostriata and S. perversa are more characteristic of the
Hamilton group.

Figs. 18 & 14 are examples of the dorsal valves of this variety.

Fig. 15 is an irregular form of the same.

Fig. 16 is an intermediate form of the ventral valve, with the striae intermediate in distance
and the cardinal angles but little rounded,

Fig. 17 is the dorsal valve, which is quite symmetrical in form, but with distinct striae and
rounded hinge-extremities.

Fig. 26 is a very convex dorsal valve with slightly rounded cardinal extremities, and having
comparatively distinct striae. The umbo is very prominent ; below which it is
flattened in the middle, and slightly depressed towards the front of the shell.

Geological formation and locality. This variety occurs on Seneca and Cayuga
lakes, Moscow and Hamilton, in the Hamilton group. Fig. 17 is from the same
group, in the village of Fabius, Onondaga county. Fig. 26 is from the Corniferous
limestone at Williamsville, Erie county. In the latter, the striae are more nearly
equal.

Var. D. Streptorhynclms pcctinacea.

PLATE X.

Strophomena pectinacea and S. bifurcata : Hall, loc. cit.

Shells usually symmetrical, often unsymmetrical, semioval, with the
hinge-extremities sometimes a little salient, often truncate and some¬
times rounded.

The dorsal valve is moderately convex, or sometimes gibbous. The
surface is marked by distant, very prominent striae, with two or three
finer ones between them. The hinge, and other features of the shell, are
the same as in other varieties of the species.

The well-marked specimens are usually small or of medium size.
[ Paleontology IV.] 10

PALAEONTOLOGY OF NEW-YORK.

74

Among a large number, the gradations to S. bifurcata, where the striae are
regularly bifurcating and of nearly equal size, are almost imperceptible.
It is apparently as the individuals become larger that there is an increase
in the gibbosity of the dorsal valve,, while at the same time the striae
become somewhat regularly alternating in size, and in some specimens
nearly equal, but retaining a sharpness of outline not observed in
specimens from the limestone.

It was to those specimens with sharp equal strise and gibbous dorsal valves that
I originally gave the name Strophomena arctostriata (Report of Fourth District).
Specimens of this kind approach, both in form and expression, the figures of
Streptorhynchus crenistria , illustrated by Mr. Davidson ( Monograph of British
Carboniferous Brachiopoda), where figs. 2 & 8, Plate xxvii, maybe compared with
figs. 8, 11 & 14 of Plate x of this volume. The British Carboniferous specimens
are larger than ours of the Chemung group.

The gradations of form and character are pretty well shown on Plate x. Figs.
1-6 are of the smaller forms, having the prevailing- surface-marking characteristic
of S. pectinacea . The ventral valve fig. 2, and the cast of ventral and dorsal valves
respectively figs. 3 & 5, are more like S. bifurcata.

In figs. 7 & 8 we have gibbous dorsal valves, somewhat depressed towards the
front, and with the striae subequal or alternating ; and fig. 10 is the ventral valve
of similar character.

In the figs. 11 - 17, we have specimens with somewhat unequally convex dorsal
valves : the ventral valves are irregular towards the umbo, and the beaks more
or less distorted ; while the area presents much variety in its degree of elevation.

In fig. 18, we have a ventral valve with .the strise as regular and even as thQse
from the limestone ; and in the casts, figs. 19 - 23, we have symmetrical forms with
even strise, and with form of muscular impression undistinguishable from those of
the Schoharie grit, the only distinctive feature in those from the Chemung group
being the tenuity of the shell.

The varieties illustrated on Plate x are common and often abundant in the
Chemung group, having a considerable vertical range, and in horizontal range are
almost coextensive with the formation within the limits of the State. They are
most abundant and present greatest variety of form in Chemung, Allegany and
Cattaraugus counties.

Following the comparison of the New-York Chemung species with similar forms
of the Waverly sandstone* of Ohio (which I have regarded as of the same age).

• The term “ subcarboniferous” has been applied by some authors to these sandstones. This is a very
pernicious nomenclature, as the term is equally applicable to all rocks below the Carboniferous period.

STREPTORHYNCHUS.

7S

I am unable to find any characters by which the specimens from the two localities
may be separated into distinct species or even marked varieties. In my collections
from Ohio, the specimens of Streptorhynchus are comparatively less common than
in similar collections made in the Chemung group of New-York. In the rock still
farther to the west, the sandstones of the “Knobs” near New-Albany, I find a
Streptorhynchus of similar form and proportions, varying chiefly in the more
distinct crenulation of the striae. This feature, however, appears to me oftener due
to the nature of the matrix in which the fossil is imbedded, than to any original
difference in the shell itself.

Whether these forms can be traced into the large species of the upper sand¬
stones of the Knobs and of the Keokuk formation ( Orthis keokuk, which Mr.
Davidsojn has identified with Streptorhynchus ( Orthis ) cr'enistria of Europe), re¬
mains still undetermined. My collection does not furnish intermediate forms suf¬
ficient to justify such a conclusion at the present time.

The large specimens from the higher part of the sandstone and the concretio.
nary bands of limestone near New-Albany have always a thin median septum in
the ventral valve, extending from the apex more than one-third the length of the
shell. The cardinal process of the dorsal valve has, moreover, at its base, on one
side, a short vertical ridge; while between these, and immediately below the
process, the valve is a little thickened on the inner side. The dental sockets are
nearly filled up, leaving a thin accessory ridge on each side of the cardinal pro¬
cess. The shells have been so thin that the casts show very little muscular marking-
The illustrations of S. crenistria of Europe, which I have seen, do not presenl
the distinct median septum in the ventral valve, which is seen in the large speci¬
mens referred to. »

Specimens from the Keokuk limestone show a large muscular impression in the
ventral valve, which is divided by a longitudinal septum reaching to the base of
the imprint. The same feature exists in specimens of all dimensions from the Coal

measures.

PALAEONTOLOGY OF NEW- YORK.

T«

Genus Strophomena (Rafinesque).

The Genus Strophomena of Rafinesque has for its type the S. rugosa =
S. rhomboidalis, W ahlenberg ; a species which ranges from the Lower Si¬
lurian to the base of the Carboniferous system inclusive, appearing under
various aspects in the successive geological stages. The species has been
already fully illustrated in the preceding volumes of this work, and it is
only necessary to give the more important among the varieties of form
in the succeeding formations.

Restricting the genus to such forms as may properly be grouped with
the typical species, we find no species of Strophomena proper in the
Devonian ; and indeed it may be doubted whether any other species of
this genus occurs above the Middle Silurian.

strophomena rhomboidalis.

PLATE XII.

Dritte Anomiten art mit breiter schlosskante : Hupsch, Naturgeschichte des Niederdeutschland. 1781,
Vol.i, pa. 15. pl,l, f. 7 & 8.

Jlnomites rhomboidalis : Wahlenberg, Acta Soc. S. Upsaliensis, 1821, Vol.viii, pa. 65, n° 7.

Producta depressa ; Sowerby, Genera of Shells ; & Min. Conchology, 1825, Vol.v, pa. 86, pi. 459, f.3.
Producta dapressa : Hisinger, Vet. Acad. Handlingar, 1826, p. 33.

Productus depressus : Defrance, Diet, des Sciences naturelles, 1826, Vol.xlvii, p.353.

Leptcena rugosa, : Dalman, Vet. Acad. Handlingar, 1827, pa. 106, pi. 1, f. 1.

Leptcena depressa : Id. Ib., pa. 107, pi. 1, f. 2.

Strophomena rugosa : Bronn. Leth. geognostica, 1835, Vol. 1, pa. 87, pi. 2, f. 8.

Producta depressa : Phillips, Geol. Yorkshire, 1836, Vol. ii, pa. 215, pi. 8, f. 18.

Productus depressus : Deshayes, Lamarck animaux sans vertebres, 2d edition, Vol. viii, p. 380.
Leptcena rugosa and L. depressa : Hisinger, Leth. Suecica, 1837, pa. 69, pi. 2, f . 2 & 3.

Orthis rugosa : Von Bucii, Ueber Delthyris, 1837, p. 30.

Leptcena : Fischer, Oryct. du Gouvernement du Moscou, 1837, p. 142.

Leptcena depressa : J. Sowerby, in Murchison Sil. System, 1839, pa. 623 & 636, pi. 12, f. 2.

L. tenuistriata [?] : Id. Ib., pa. 646, pi. 22, f. 2 a.

L. rugosa : Id., Trans. Geol. Soc. London, 1840, 3d series, Vol.v, pi. 56, f. 4.

Orthis rugosa : Eichwald, Sil. System in Esthland, p. 162. «

Leptcena rugosa : Phillips, Pal. Fossils, 1841, pa. 57, pi. 24, f. 95.

Leptcena depressa : De Koninck, Desc. An. fossiles de Belgique, 1842, pa. 215, pi. 12, f. 3 - 6; and
pi. 13, f. 6.

Leptcena depressa : G. B. Sowerby, Conch. Manual, 1842, pa. 71 & 300, f. 206.

Orthis rugosa : D’Archiac et De Verneuil, Trans. Geol. Society London, 1842, 2d series, Vol. ii,
part 2, p. 396.

STROPHOMENA.

77

Strophomena depressa : Vanuxem, Geol. Report Third District New-York, 1842, pa. 79, f. 5.

S. undulata : Id. Ib., p. 139, f. 3.

S. depressa .• Hall, Geol. Report Fourth District New-York, 1843, p. 77, f. 5; and p. 104, f. 2.

Orthis rugosa : F. C. Rcemer, Rhein. Uebergangsgebirge, 1844, pp. 85 & 90.

Leptcena depressa : De Verneuil, Geol. Russ, and the Ural, 1845, Yol. ii, pa. 234, pi. 15, f. 7.
Leptcena tenuistriata : Hall, Palseontology of New- York, Yol. i, p. 108.

Leptcena depressa : Hall, Palseontology of New-York, 1852, Yol. ii, p.257.

Strophomena rhomboidalis : Davidson, Intr. Nat. Hist. Brachiopoda.

«• << ; Ib., Monograph of the British Carboniferous Brachiopoda, p. 119. 1860.

Strophomena rugosa * : Hall, Palseontology of New-York, Yol.iii, p. 195. 1859.

The shell is more or less semielliptical or subquadrate, varying greatly
in its proportions of length and breadth : hinge-line straight ; car¬
dinal extremities sometimes rounded, sometimes acute and slightly
produced. The valves are geniculated, and the proportions of the flat¬
tened part or disc and the recurved part of the shell are very variable,
insomuch that the geniculation is sometimes little more than one of the
strong concentric wrinkles.

The surface of the flattened portion is marked by concentric (and
sometimes interrupted) wrinkles, which, following the curve of the
outline, are bent outwards, and often become obsolete on the cardinal
angles. These concentric wrinkles are very variable in number, being
from six to fifteen or sixteen upon specimens from the same rock. The
entire surface is covered by radiating threadlike striae.

In young specimens there is usually a round foramen in the apex of
the dorsal valve, which becomes closed at a later period. The triangular
foramen of the ventral area is partially closed by a deltidium and the
apex of the ventral valve.

This species is not of frequent occurrence in the Schoharie grit, but is found
everywhere in the Corniferous limestone. The principal varieties are illustrated in
figures 16, 17 & 18 of Plate xii, the two latter being essentially casts of the
interior. In all the collections made in New-York, we have no specimens of this
species from the Hamilton or Chemung groups.

* I adopted the name S. rugosa in the third volume of the Palseontology, recognizing it as the typical
species of the genus, and thus named by Rafinesque. The name of Wahlenberg has precedence in
time, and will include those lower Silurian forms described as Strophomena or Leptcena tenuistriata.

T8

PALAEONTOLOGY OP NEW-YORK.

&EAUS STROPHODOKTA ( Hall).

The Genus Strophodonta was originally proposed for strophomenoid
shells, having a crenulated hinge-line, without foramen in the area of
the ventral valve. The internal characters were not at that time fully
known, and therefore could not be included in the description.

In S. demissa, which was regarded as the type of the genus, the area
of the ventral valve is free from any indication of foramen ; the dental
lamellae are partially or essentially obsolete, and the divaricator muscular
impressions are spreading flabelliform without limitation by an elevated
ridge. In the dorsal valve, the cardinal process is bifurcate from its origin,
and is directed backwards beneath the area of the ventral valve. On the
lower side of this ventral area there is a bilobed callosity or process
which is more or less prominent and embraced by the divisions of the
cardinal process of the opposite valve ; thus strengthening the articulation
of the valves, or assisting in keeping them in position. The divisions
of the cardinal process often extend so far beneath the area as to form
conspicuous pits in the substance of the shell within the umbonal cavity.

The valves are so closely articulated by the interlocking of these pro¬
cesses, that the separated ventral valves are usually broken in the mid¬
dle of the area : this happens also to other species, and it is compara¬
tively rare to find the inner margin of the ventral valve entire. This
accident is probably caused by the pressing or crushing of the dorsal
valve into the cavity of the ventral valve, while the central portion of
the two, remaining firmly united, carries away the middle of the ventral
area, which is thinner on each side of the median.

In the S. reversa of Iowa, this bilobed process of the ventral area is
very conspicuous ; and „ in some specimens of this and of S. lepida, the
central process remains very prominent, while the margin of the area
on either side is indented by the branches of the cardinal process of the
opposite valve. In these species we not only have no evidence of trian¬
gular foramen, but there is an absolute thickening on the lower side and

STROPHODONTA.

7 9

a process extending therefrom, which, in its indented front margin,
leaves a space for the protrusion of a minute pedicle.

The question of the presence or absence of a foramen, or the smooth
or crenulated hinge-line, might not alone or together be of sufficient
importance to indicate a distinct genus ; but taken collectively with the
form of the muscular impressions and other points, we find so wide a
difference from the typical species of Strophomena, that it appears to me
the separation is required. Were we to unite typical Strophomena with
the forms I have designated Strophodonta, we could, with equal pro¬
priety, unite many of the Streptorhynchus in the same group.*

The distinction among the genera or subgenera of the strophomenoid
shells does not, in all cases, appear to be satisfactorily determined ; and
we may be often disposed to regard a newly -'observed feature as characte¬
ristic and reliable for generic determination, when the same may be
found in species where the associated characters are incompatible.
Among other examples we find one or more forms with crenulated hinge¬
line, where the area is well defined on both valves, with the triangular
foramen closed by a convex deltidium, but otherwise resembling Strep¬
torhynchus.

It may be doubtful how far the presence or absence of dental lamellae
should influence our considerations in determining the generic relations ;
and whether the form of the cardinal process, its extension backwards
or inclination forwards, should influence the decision.

Among the forms which I have designated Strophodonta, we have a
group of species, following the typical form in their internal characters,
in which we may enumerate S. demissa , S. inequiradiata , S. concava, S.
hemisphemca, S. nacrea, and some others.

In another group of nearly flat species, we find the partial or entire
absence of foramen and dental lamellae, with broad spreading muscular

•In the Canadian Journal of July 1861, Mr. Billings, in endeavoring to prove the identity of Stro-
~ phodonta and Strophomena, has given as an illustration of the latter genus the S. filitexta , which is a
Streptorhynchus. If the characters of the recognized Genera Strophomena and Streptorhynchus are
so similar as to deceive this acute observer, it may be supposed that differences of equal value between.
Strophodonta and Strophomena may have escaped notice.

m

PALAEONTOLOGY OF NEW-YORK.

impressions, as S. perplana, S. textilis, S. alveata , and in the Lower Helder-
berg group the S. beckii.

There are still some other forms which make a distinct natural group,
in being all'resupinate, and in having the dental lamellae continued in
an elevated border which nearly surrounds the divaricator muscular
impressions. We have but two representatives of this group in the higher
formations, the S. ampla and S. viduus, the former of which is perhaps
identical with S. headleyana and S. punctulifera of the Lower Helderberg
group. The S. leavenworthana, which is a very marked species, belongs to
the same group ; and by a little extension of the characters, the S. striata
of the Niagara group may be included : the two latter have a cardinal
process more like Streptorhynchus. By a farther step, we may include
the species I have described as Strophodonta semifasciata, which has an area
on both valves, and on each one a triangular foramen closed by a convex
deltidium. With all these features of Streptorhynchus, together with a
cardinal process similar to other species of that genus, I have found
that the hinge-line is crenulated for one-third the length on each side of
the centre. The principal ground on which this one could be separated
from Streptorhynchus is the crenulated hinge-line ; although the striae
are somewhat dissimilar, and we do not fully know the ventral muscular
impressions. Were we to admit that Streptorhynchus may have a crenu¬
lated hinge-line, then going one step further,- and taking the form of
muscular impression and cardinal process, leaving out of consideration the
closed area, we may include in the Genus Streptorhynchus other species
enumerated in this group. This would leave for Strophodonta a more na¬
tural assemblage of species than are at present united under that genus.

In every one of the characters used to distinguish Strophomena, Stro¬
phodonta, Lept^na, and Streptorhynchus, there are gradations or varia¬
tions on the one side or the other, which ally the species so far that it
becomes often no easy task to indicate the limits of the genera ; and the
additional information obtained from the internal structure of numerous
species has not served to clear up the difficulties.

STROPHODONTJE OF THE UPPER HELDERBERG GROUP.

$1

STROPIIODONTiE OF THE UPPER HELDERBERG GROUP.

Stiopliodonta demissa.

PLATES XI & XII.

For description and references, see the same species under Hamilton group, p. 101.

This species, which has been made the type of the genus, first appears in
the Schoharie grit, where it is not of unfrequent occurrence.

The figures 14, 15 and 16 of Plate xi, are illustrations of specimens found in this rock. The specimens
usually occur as casts of the interior and impressions of the exterior of the shell. The coarse ma¬
terial of the rock prevents the preservation of the muscular impressions with that degree of
distinctness which we find in the same species in the Hamilton group, where the material is finer.
At the same time it is probable that the shell has been thinner in the Schoharie grit than in the
higher formations, since the striae are more strongly marked on the casts.

Figure 15, Plate xi, is a cast of the interior of a ventral valve, and figure 14 shows the character of
the exterior shell of the same from a cast made in the natural mould.

Figure 16 is a dorsal valve, which is very thick and strong, occurring in a more calcareous portion of
the rock.

Figure 17 is a cast of the interior of a ventral valve, showing the muscular impressions.
Commencing in the Schoharie grit, the species occurs in the Corniferous lime¬
stone in the form and condition represented on Plate xii, figs 1 - 5 : it is rarely
seen of larger dimensions. It attains its maximum development in the Hamilton
group, occurring in great numbers, and sometimes attaining a length of one and a
half by one and three-fourths inches in breadth. It continues in the Che¬
mung group, where, in the arenaceous beds, it exhibits a character similar to
specimens from the Schoharie grit.

Strophodonta alveata.

PLATE XI.

Strophodonta alveata ; Hall, Sixteenth Report on the State Cabinet, p. 36. 1863.

This species is known only as casts of the interior and impressions of the
exterior. In the young shells, the casts of the ventral valve are slightly
convex ; while in older specimens they are flat or slightly concave, with
the margin more or less recurved. The form is semi-elliptical, and the
[Paleontology IV.] 11

8S

PALAEONTOLOGY OF NEW YORK.

hinge-line is sometimes a little longer and sometimes a little less than the
width of the shell.

The occlusor muscular imprints are small and deeply marked, and the
impressions of the divaricator muscles form together an elongate-ovate scar,
with the sides nearly straight, and each division showing two or three lobes.
Near the exterior margin of the valve there is a depression reaching from
the hinge-line entirely around the front of the shell, indicating a callosity
upon the interior of the valve, which is marked by striae and by vascular
impressions in well preserved specimens.

The cast of a dorsal valve, of the same form, and associated with the
ventral valves, shows the imprint of the submarginal callosity, with vascu¬
lar markings and a crenulated hinge-line : the cardinal process is bifurcate,
and directed outwards as in other species of the genus.

The length of the shell is from one-half to three-fourths of an inch, with
a somewhat greater breadth.

Figure 3, Plate si, is a young individual in which the ventral valve has a slight convexity, and the
muscular impression, is but faintly defined in the lower part; while in fig. 2, an older specimen, it is a
little concave, with a strongly defined muscular impression.

The characters of the species, as represented in the figures of the ventral valve,
are constant in as many as nine or ten individuals under examination, and they
show no near approach to any other species in the collection. Fig. 1 is the inte¬
rior of a dorsal valve, which has been referred to this species from its association
and similarity of form, while the vascular impressions also correspond in the
two valves.

Geological formation and localities. In the Schoharie grit at Clarksville, and at
Knox, Albany county, N. Y.

Stropliorionta callosa.

PLATE XI & XX.

Strophodonta callosa : Hall, Sixteenth Report on the State Cabinet, p. 36. 1863.

Casts of the ventral valve are semi-elliptical, longer than wide or with

nearly equal length and breadth, very convex or gibbous ; across the

STROPHODONTJE OF THE UPPER HELDERBERG GROUP.

83

middle of the valve, the width of the shell is greater than at the hinge¬
line. The area is comparatively wide and much elevated in the centre;
the hinge-line strongly crenulated. Muscular impressions comparative¬
ly large and deeply marked, separated by a rather wide groove which
reaches more than halfway to the base of the shell.

The entire margin of the valve (in the casts) is elevated in a narrow
band, within which it is abruptly depressed ; and the space between the
callosity and the muscular impression is marked by punctate vascular
impressions.

In five well-marked individuals, like fig. 9 a, b, of Plate xx, the casts are rarely more
than half an inch in length, and are readily recognized by their great convexity, nar¬
row elevated border, and comparatively short hinge-line.

A dorsal valve found associated with the ventral valves is represented on Plate xi, fig. 4,
which is enlarged from a mould in the gritstone : it has the margin abruptly recurved,
with a callosity extending along the border. The cardinal process is slender and bi¬
furcate.

In comparing a larger number of specimens, it appears that the well-marked
S. callosa may pass by several gradations into another form which is even more
numerous in individuals than the form described. In the absence of the shells, it
may be impossible to decide satisfactorily ; but it appears not improbable that
the S. callosa (as originally described ) is an extreme variety of a more regularly
convex shell which is proportionally shorter, and sometimes possesses the callo¬
sity near the margin in a moderate degree, but is often free from such marking.

The prevailing form is the following :

Stropliodonta callosa, wr.

PLATES XI & XV.

Shell semielliptical. Ventral valve regularly convex, the greatest con¬
vexity about the middle of the shell : hinge-line straight, strongly
crenulated, varying from a little less to a little more than the width of
the shell ; apex elevated above the hinge-line ; area of moderate width.
In the casts there is a narrow longitudinal mesial depression, often
reaching more, than halfway to the base ; the apex is distinctly bilobed ;
the marks of the occlusor muscles make two well-defined prominences ;

PALAEONTOLOGY OP NEW-YORK.

84

and the divaricator muscular impressions are broad, spreading, and some¬
what truncate on their lower margins. The lateral and basal margins are
usually a little more strongly marked by the impressions of the surface
striae ; and sometimes there is a partial or entire elevation of the part,
or a callosity more or less defined.

Figures 6 & 7, Plate xi, are of the natural, size of the shells.

Figures 9 & 10 of Plate xi are illustrations of an extreme form of the cast of this shell,
where the median depression is much wider than usual, and the lateral margins show
a partial callosity,

A cast taken from an impression of the dorsal valve, which occurs in the same association
with the ventral valves, gives the characters shown in figure 8 of Plate xi, differing
hut slightly from figure 4 : this difference may be owing to the imperfect preservation
of the parts in a coarse material.

Among the collections are two or three specimens, which, preserving the shell
more or less completely, have the size and form of the casts. In one of these, where
the shell is apparently entire, the surface of the middle and lower part of the shell
is marked by distant elevated striae with wide interspaces, which do not show
radiating striae, but are marked by concentric striae. On the umbo, the surface is
marked by wide ‘radiating bands without distinct striae.

In another partially exfoliated specimen, the surface near the margin of the
shell shows minute striae between the coarser ones ; and the same characters are
partially shown in one or two other specimens.

In the collections before me there are about thirty specimens with the characters
described, and all these are of nearly the same size ; nor can I trace any connexion
between these and any of the larger forms. Notwithstanding, therefore, that I am
opposed to creating new species where it can be avoided, and knowing that the
species of this genus have been unnecessarily multiplied, I must regard this as a
distinct and well-marked form. In its dimensions, it corresponds with the next
described species, but differs in its surface markings and form of muscular im¬
pressions. It is nearly of the same size as S. nacrea , but differs in the greater
convexity of the ventral umbo, and in the form of the muscular impressions as
well as in the surface-markings.

The illustrations on Plate xv show the form of muscular impression, surface

striae, etc.

ue;j! .

Geological formation and locality. In the Schoharie grit at Clarksville and Knox
in Albany county. The species is not at present known in the Corniferous limestone.

STROPHODONT^E OP THE UPPER HELDERBERG GROUP. 85

Stropliodonta parva.

PLATES XI & XV.

Strophodonta parva : Hall, Sixteenth Report on the State Cabinet, p. 37. 1863.

Shell small, subhemispheric, a little wider than long : hinge-line equal¬
ling or shorter than the width of the shell; cardinal extremities
rounded. Ventral valve gibbous : umbo elevated above the area-line;
apex incurved ; area linear.

Surface marked by few rounded or subangular costae, which are simple
on the upper part of the valve, but each one dividing into two or three
above, or in the middle of the shell, and are often farther divided on the
margin ; those of the ventral valve often increase by subdivision,
while those of the dorsal valve increase by intercalation. The larger
striae are covered by fine undulating or interrupted longitudinal striae,
and are sometimes marked by a sharp elevation along the middle.

The casts of the interior of the ventral valve rarely show the muscular
impression with much distinctness ; the surface being marked as if by
fascicles of fine striae, with sometimes a sharp elevated one between. The
apex is bilobed ; the occlusor impressions small and well marked, and
the divaricator muscular imprints are broad and spreading.

Impressions of the exterior of the dorsal valve are common, and are
readily distinguished by the strong subangular costae on the upper part,
while they become grooved and increase by intercalation on the lower
part of the mould.

In exfoliated specimens, the surface has the aspect of those with fa¬
scicles of striae and sharp elevated striae between.

The form and proportions of the species seem to be pretty constant,
rarely exceeding and usually less than half an inch in width. The ordinary
condition of the specimens is that of casts, or of impressions of the ex¬
terior shell ; while in the more calcareous part of the rock, specimens
preserving the shell have been obtained.

m

PALAEONTOLOGY OP NEW-YORK.

The form and proportions are not materially unlike those~of S. callosa ; but the
strife are much stronger, the muscular impression of different form, and the surface
of the cas^s much more distinctly marked by the impressions of strife.

Figure 5 of Plate xi is from the impression of a dorsal valve ; and figure 11 of the same
plate is a east of the ventral valve enlarged two diameters, showing the muscular impression
and marks of the striae. Farther illustrations are given on Plate xv.

Geological formation and locality. In the Schoharie grit, at several localities in
Albany and Schoharie counties.

Strophodonta crebristriata.

PLATE XI.

? Strophomena crebristriata : Conrad, Jour. Acad. Nat. Sciences, Vol.viii, pa. 254, pi. 14, f. 3.

Shell semielliptical ; length and greatest width nearly as two to three.
Ventral valve convex or moderately gibbous, more elevated in the
centre : hinge-line straight, with the extremities usually a little sa¬
lient ; area linear and finely crenulated ; the beak slightly prominent,
and a little incurved. Dorsal valve concave, following the form of the
ventral valve.

Surface marked by fine crowded striae which regularly bifurcate from
their origin, or sometimes in fascicles of threes which again subdivide.
Mr. Conrad’s description of S. crebristriata is as follows :

“ Semi-orbicular, with fine crowded bifurcating radii ; inferior valve ventricose,
“ slightly depressed or flattened in the middle ,; sides depressed or concave to-
“ wards the hinge margin, the extremities of which are slightly salient and not
“ very acute ; summit of the umbo elevated above the hinge-line.” This species
is cited as occurring both in the Schoharie grit and in the limestone above.

The specimens described are all from the Schoharie grit. The smaller ones are
about half an inch in length, and the larger ones of the same character are an
inch in length by one inch and a half in width. In the younger specimens, and
those of medium size, the cardinal extremities are a little salient, and this charac¬
ter prevails in nearly all the specimens.

I had referred the smaller specimens, with some hesitation, to the Strophomena
crebristriata of Cornad ; but the gradations to those of larger size are quite im¬
perceptible, and all must be included under one designation.

STR0PH0D0NTJ3 OF THE UPPER HELDERBERG GROUP.

87

Figure 12 represents a young individual, and figure 13 is twice enlarged.

The figures 18 & 19 are ventral and profile views of a large individual, and the fasciculate
striae upon the inner surface of the shell are shown in figure 20.

The specimen figure 21 is a larger individual, with similar crowded striae and rounded
cardinal angles.

In the well-marked specimens of this form, I have not been able to learn the
character of the muscular impressions ; and in one small specimen only I have
seen a short bifurcating cardinal process.

Among some obscure specimens from the same localities are some casts of dorsal
valves which are much elevated, or obtusely subcarinate along the centre, with
duplicating striae. One of these shows a cardinal process and muscular impression,
as illustrated in figure 23 of Plate xi. This may be identical with the preceding
form.

Geological formation and locality. In the Schoharie grit at Clarksville and Knox
in Albany county, and at Schoharie.

8tropiiodonta inequiradiata.

PLATES XI, XII & XIII.

Strophodonta inequiradiata : Hall, Tenth Report on the State Cabinet, p. 113. 1857.

Shell semielliptical or semicircular, more or less gibbous, approaching a
hemispheric form : cardinal extremities sometimes salient, but often
rounded, and the cardinal line less than the width of the shell below.
The ventral valve varies from moderately convex to gibbous, often
forming a somewhat regular arch from beak to front, usually with the
greatest convexity above the middle, depressed and often concave be¬
tween the umbo and the cardinal extremities, which (in perfect shells)
are somewhat salient : beak a little elevated above tlie hinge-line, and
incurved ; area very narrow, linear and finely crenulate. The dorsal
valve is concave, often in a less degree than the convexity of the
ventral valve ; the disc sometimes very slightly concave, and abruptly
deflected or almost geniculate towards the front.

The surface presents much variety of character and aspect, both’ in the
original shell and in its partial or entire exfoliation. The strise on the
ventral valve are often coarse and uneven, somewhat fasciculate, and

88

PALAEONTOLOGY OF NEW-YORK.

often rising in ridges which in the exfoliated shell do not show the divi¬
sions. Some specimens have the striae sharp and slender, and nearly
equal, with wider plain intermediate spaces. On the dorsal valve the
striae are pretty uniform ; the stronger ones being distant, sharp and
elevated, with wide intermediate spaces marked by extremely fine regular
striae, from the midst of which, as the shell increases, the elevated striae
arise, dividing the space in which the smaller striae are constantly in¬
creasing by intercalation.

The modifications in the expression of the surface striae, in the specimens, are represented
bii Plate xi, figures 25, 29, BO & 31, and on Plate xm, figures 6-8. In the lattter
figures the striae are uneven, and rise in ridges with irregular interspaces.

In figure 29, Plate XI, which is a cast of the ventral valve, there are regular interspaces
between the fine elevated striae, a character more usually observed ir^the dorsal valve.

The muscular impressions of the ventral valve show narrow elongate scars for the occlusor
muscles, and the divaricator muscular impressions are spreading, flabelliform, and deep¬
ly striated. In many of the casts, the lower part of the specimen is marked By strong
vascular impressions, which are shown in figures %6 & 27 of Plate xi. The muscular
impressions of the dorsal valve are narrow and elongate, and the cardinal process is
usually comparatively slender. The interior surface of the valves is granulose or pu-
stulose.

This species approaches the S. pp,tersoni; and in some specimens, it is not easy
to decide the specific differences. In the latter species, the muscular impressions
of the ventral valve are smaller and shorter, while the wide interspaces between
the stronger striae on the ventral valve are characters not observed in any of the
numerous authentic specimens of S. inequiradiata : at the same time, there are
many obscure specimens in the Schoharie grit and Corniferous limestone, which
it is difficult to refer satisfactorily to either of the species described.

The S. inequiradiata is entirely distinct from the S. inequistriata of Conrad, with
which it has been sometimes united*, as will be shown under the description of
that species in the Hamilton group.

Geological formation and locality. In the Schoharie grit in Albany and Scho¬
harie counties ; and in the Corniferous limestone of the Helderberg mountains,
Schoharie, Cherry-valley, and other places.

It is perhaps unfortunate that the nanie has the same signification.

STROPHODONTJS OF THE UPPER HELDERBERG GROUP.

80

Stropliodonta patersowi.

PLATES XII & XIII.

Strophomena ( Strophodonta ) patersoni : Hail, Tenth Report on the State Cabinet, p. 114. 1857.

Shell semioval. Ventral valve convex, becoming gibbous in the middle,
somewhat deeply deflected at the sides and front ; sometimes marked
by a few radiating undulations or folds, which affect both ventral and
dorsal valves towards the front : hinge-line straight ; extremities often
salient.

Surface marked by distant elevated radiating striae, and the intermediate
spaces by undulating fine striae, and crossed by short abruptly arching
wrinkles which are interrupted by the strong radiating striae. The
finer radiating striae on the ventral valve are from three to ten or
twelve between the stronger ones ; while on the dorsal valve the spaces
are wider, and there are from ten to twenty finer striae between the
stronger ones. The finer striae are crossed by equally fine concentric
striae, giving the entire surface a delicately cancellated appearance.
The ' short interrupted arching wrinkles vary extremely in strength ;
usually becoming obsolete towards the front of the shell, and in some
specimens are scarcely‘or not at all perceptible.

In young shells the cardinal extremities are very salient, the ventral
valve moderately convex, usually becoming more so as the shell increases
in size, but sometimes continuing of moderate convexity till more than
half grown ; but in such specimens, the margin is sometimes abruptly
inflected. Older specimens become very gibbous, and sometimes longitu¬
dinally wrinkled.

In one specimen partially preserving the shell (fig. 2, Plate xm), the
muscular impression of the ventral valve is of the same form as in S.
inequiradiata, but smaller. In a cast preserving the striae upon the margin,
as in characteristic specimens of the species, the muscular impressions
are likewise small, but exhibit the same form as the one figured. In a
[ Paleontology IV.]

12

9©

PALAEONTOLOGY OF NEW-YORK.

single dorsal valve, recognized as of this species, the cardinal process is
slender, the parts narrowly diverging, and continued in a narrow rounded
elevation to the middle of the valve. No defined muscular impressions
are visible in this specimen.

The figures 9, 10 & 11, Plate XII, and figures 1 - 5, Plate xm, illustrate some of the
usual forms and the preceding characters of this species.

Notwithstanding that these characters can be traced through the various stages
of growth offering differences from the ordinary forms of S. inequiradiata, there
may still remain some doubt whether a large collection may not show intermediate
forms which will unite the two.

The Leptcena stephani of Barrande has a similar wrinkled surface in some of the
individuals, though the intermediate finer striae are not shown in the figures. In
these two shells, the muscular impressions are quite distinctive ; and the figure 7 b ,
Plate x, Barrande, approaches in character to some varieties of S. inequiradiata.
Some varieties of the species under consideration may be compared with S. cor-
rugata , Portlock sp. (not of Conrad).

The species differs in form of shell, character of striae, and muscular impressions,
from the S. inequiradiata.

Geological formation and locality. Rarely in Schoharie grit, but not uncommon
in the Corniferous limestone, in the Helderberg mountains, Schoharie ; in Ontario
county ; and at Stafford in Genesee county and Williamsville in Erie county. It
has likewise been recognised among the collections made at the Bake-oven on the
Mississippi river, in Illinois.

i

Strophodonta hemispherica.

PLATE XIV.

Strophomena ( Strophodonta ) hemispherica : Hall in Tenth Eeport on the State Cabinet, p. 113. 1857.

Shell subhemispheric, semielliptical in outline : binge-line equalling or
greater than the width of the shell ; cardinal extremities sometimes
salient and auriculate ; length and breadth about as four to five : in
the larger specimens the length is about two inches, with a breadth
of two and a half inches. Ventral valve gibbous, the elevation of the
curvature being often equal to half the length of the shell, sometimes
very abruptly declining to the front : umbo moderately, or sometimes
more extremely elevated ; apex incurved ; area narrow ; margin ere-

STROPHODONTiE OP THE UPPER HELDERBERG GROUP.

91

nulated. Dorsal valve moderately concave on the upper and middle part
of the shell, and abruptly deflected or geniculate towards the front.
Surface marked by fine radiating striae, which are somewhat unequal on
the upper and middle portions of the ventral valve, but are fine and
regular towards the margin. In some specimens of the dorsal valve,
the striae show a tendency to the alternation of three or four finer ones
with a distinctly stronger one between ; hut in the greater number of
specimens, the striae are fine, close, and mostly equal in strength. The
radiating striae, when perfect, are crenulated by extremely fine con¬
centric striae : sometimes a few obscure concentric wrinkles mark the
umbonal region, and some specimens show undefined longitudinal folds.
In the ventral valve, the occlusor muscular impressions are strongly
marked in elongate semielliptical imprints ; while the divaricator muscu¬
lar impressions are elongate flabelliform, often reaching half the length
of the valve. The specimen figured on Plate xiv is shorter than usual.

In the dorsal valve' the muscular impressions are strongly marked, and
divided by a low median ridge, which is continued above as a rather
strong bifurcate cardinal process : hinge-line rather coarsely crenulated.

This shell differs from S. inequiradiata, in attaining a larger size, and in being
more gibbous on the ventral valye. The strige are finer and more equal, and the
muscular impressions larger ; while the vascular impressions, so common in casts
of that shell, have not been observed in this one.

Its fine and nearly equal strige, as well as its greater gibbosity, distinguish it
from S. patersoni. It approaches very nearly the S. concava of the Hamilton group ;
and the two have so many characters in common, that I have hesitated to continue
them as distinct species. A larger collection of the limestone specimens are
needed, before a satisfactory comparison can be made.

The figure 2 a on Plate xiv illustrates the exterior of a dorsal valve, where the cardinal
extremities are auriculate. The profile view, figure 2 b, is a little less gibbous than
usual.

The interior of the dorsal valve is shown in figure 2 c ; and the cardinal view, figure 2 d,
shows the muscular impressions of the ventral valve;

Geological formation and locality. This species occurs in the Schoharie grit in
Albany and Schoharie counties, and not rarely in the Cornifereus limestone in
nearly all localities of this formation throughout the State ; and I have a specimen

92

PALAEONTOLOGY OF NEW-YORK.

from Port Colborne, Canada West, which is apparently identical with it. The finest
and best characterized specimens which I have seen are from the Falls of the
Ohio; and it occurs in almost equal perfection at Columbus and Sandusky, Ohio.

Strophodonta perplana.

PLATES XI & XII.

Strophomena perplana : Conrad, Jour. Acad. Nat. Sci. Philadelphia, Vol. viii, p.257. 1842.

Strophomena crenistria : Hall, Geol. Rep. 4th District, p. 171, f. 4.

For description and references, see the same species under the Hamilton group.

A comparison of large numbers of specimens of this species, from the
base of the Lower Helderberg to the Hamilton and Chemung groups
inclusive, embracing those described under -several different names, has
satisfied me that they must all be referred to a single species. There
is, however, a similar species in the Tully limestone, which in the cha¬
racter of its surface strife, the pustulose or punctate interior surface of
the valves, and the form of the muscular impressions, is very distinct
from this one.

This species begins its existence, so far as at present known, at the commence¬
ment of the Schoharie grit, where it is not infrequent. It occurs as casts of the
interior ; those of the dorsal valve being the more common. It appears in the
Corniferous limestone, where it attains large dimensions. It was a ventral valve of
this species imbedded in limestone, having the surface rather better preserved
than usual, to which I originally gave the name of S. crenistria.

The figure 22 of Plate xi is a cast of the ventral valve from the Schoharie grit.

Figures 13 & 14 of Plate xir are a small and large specimen of the shell, with nearly
even striae, as it occurs in the Corniferous limestone.

Figure 15 is a cast of the same species, where the muscular impression is very large.

Geological formation and locality. In the Schoharie grit, at Clarksville and
Knox, Albany county and at Schoharie, in the limestone at Williamsville and
Clarence-hollow, Erie county ; at Louisville, Kentucky; and in Indiana.

STROPHODONTiE OF THE UPPER HELDERBERG GROUP.

93

StropSiodonta ine<pi§triata*

PLATE XII.

Strophomena inequistriata : Conrad, Jour. Acad. Nat. Sci. Phila., Vol. viii, pa. 254, pi. 14, f. 2.

This species was originally described by Mr. Conrad from the Moscow
shales of the Hamilton group, where it occurs in considerable numbers.

Among the collections from the Corniferous limestone are a few specimens
quite undistinguishable from those of the Hamilton group, and which I have
referred to this species.

The figures 6 & 1 of Plate xii are ventral and dorsal views of a well-marked indivi¬
dual, which is of the ordinary size of the species.

Figure 8 is a profile view of a very gibbous specimen, which has a more strongly
marked surface, resembling S. patersoni ; but the specimen is much more gibbous
than any authentic individuals of that species.

Farther illustrations are given on Plate xvm.

Geological formation and locality. In the Corniferous limestone, near Cale¬
donia, Livingston county.

Strophodonta ampla.

PLATE XIV.

Strophomena ( Strophodonta ) ampla : Hall in Tenth' Report on the State Cabinet, p. 111. 1857.
Strophomena ampla : Billings in Canadian Journal.

Strophomena ampla : Geological Report of Canada, p. 368. 1863.

Compare Strophodonta headleyana, S. punctulifera, and S. cavumbona : Pal. New York, Vol.iii,

pp. 186- 188.

Shell large, broad, semioval or subsemicircular; length from two-
thirds to three-fourths as great as the width; hinge-line equalling or
longer than the width of the shell below, with extremities often a
little salient. Ventral valve concave, with a slight convexity about
the umbo, and very rarely a mesial elevation extending from the beak
nearly to the front of the shell. Dorsal valve convex in the middle,

94

PALAEONTOLOGY OF NEW- YORK.

sloping to the margin, and flat or concave upon the umbo : hinge
extremities often slightly deflected to the dorsal side.

Area of the ventral valve from one to two lines in width, and variously
inclined to the plane of the lateral margins of the shell, transversely
striated and the inner margin crenulated for about half the distance
from the centre to the cardinal extremity ; the remaining portion
marked by a narrow groove (the latter feature not always distinct).
The foramen is closed, a smooth triangular space marking its place,
with a narrow callosity along its centre. Area of the dorsal valve
narrow and linear throughout.

Surface marked by angular subequal interrupted or rugose striae, which
are often made to appear more equal and uniform by the partial exfo¬
liation of the shell. The striae are bifurcated two or three times before
reaching the margin, and they are sometimes increased by intercala¬
tion. As usually preserved, they rise at intervals into sharp ridges
or elongate nodes; and in well-preserved specimens, these are pro¬
duced into short spines.*

When the shell is exfoliated, the surface between the striae is marked
by minute pores or tubular openings, which communicate with pustulose
elevations on the interior surface of the shell. In the entire cast, these
pores mark the surface with considerable regularity, varying in size, and
uniformly larger below the middle where the valve is more abruptly
deflected.

The muscular impressions of the ventral valve are very large and broad,
and the margins distinctly limited by a curving elevated border. It is
divided in the middle by a more or less developed septum, which termi¬
nates in a prominent callosity beneath the place of the foramen : this
callosity gives a bilobate character to the cast of the rostral cavity. The
place of the occlusor muscles is strongly marked, and that of the divari-
cator muscles distinctly lobed. The muscular imprints are about two-
thirds as long as wide, and the width is often nearly equal to half the

• This feature is rarely preserved in parts of the surface in our specimens; but Mr. Billings has figured
a specimen with the entire surface covered with short spines ( Canadian Journal, loc. cit.).

STROPHODONTiE OF THE UPPER HELDERBERG GROUP.

95

width of the shell. The muscular impressions of the dorsal valve are
narrow and elongate, and are separated by a rounded median ridge which
divides above and continues in two diverging processes, the full extent of
which is not shown in any of our specimens.

This species, of the Upper Helderberg group offers no important differences from
the S. headleyana of the Lower Helderberg rocks, although that species has not
been observed in the intermediate formation of the Oriskany sandstone. It may
be doubtful, moreover, whether a more extensive series of specimens would not
show that this form, the S. headleyana , S. cavumbona, and S. puncfulifera are all of
one species presenting variations of size, degree of convexity, width of area, and
differences of surface markings, due to the influence of the sediment and other
surrounding conditions which affect the development of animal life.

In the Lower Helderberg specimens of S. headleyana , so far as observed, the
concavity of the ventral valve is usually uniform ; and only in two specimens from
the Corniferous limestone have I observed an elevation along the middle, which,
in one specimen, is raised into an angular ridge. The muscular impressions of the
specimens in the Corniferous limestone are always proportionally larger than those
of the Lower Helderberg formation.

The figures 1 «-ion Plate xiv illustrate the gradations in size, from a specimen three-
fourths of an inch to one of two inches and a quarter in length.

Figure 1 b is an impression of the dorsal valve, showing the punctate surface and the
cavities of the cardinal process.

In figure 1 g the triangular space indicating the usual position of the foramen is diffe¬
rently tinted, and the narrow callosity is shown along the middle. The striated or
crenulated portion of the area is likewise limited, as shown in the figure, though
less distinctly in the specimen. The inner edge of the area is indented on each side
of the middle, corresponding to the branches of the cardinal process, as shown in
figure 1 h, while the callosity beneath the centre protects that portion which is
more prominent.

The figure 1 * is a cast from the Schoharie grit.

Geological formation and locality. In the Schoharie grit, in Albany and Scho¬
harie counties ; and in the Corniferous limestone in the Helderberg mountains-
and at Schoharie ; at Cherry-valley ; Onondaga-hollow ; Clarence-hollow : Wil,
liamsville ; and in all localities of the limestone.

PALAEONTOLOGY OF NEW-YORK.

9©

STROPHODONTA OP THE HAMILTON GROUP.

As already indicated, several species of Strophodonta pass from the
Schoharie grit and Corniferous limestone to the Hamilton group. The
principal among them are the S. demissa, S. perplam, S. inequistriata and
S. nacrea : of these, the two first pass into the Chemung group. It may,
perhaps, be questioned also whether the S. hemispherica of the Corniferous
limestone may not assume the form to which I have given the name S.
concava in the Hamilton Group.

Those species which begin their existence below the horizon of the
Hamilton group, and pass into the Chemung group, have their greatest
development in the Hamilton group, in number of individuals, in size,
and in development of parts, with perhaps the exception of the extrava¬
gant forms of S. perplana in the Chemung group.

Strophodonta concava.

PLATE XYI.

Strophomena ( Strophodonta ) concava : Hall in Tenth Report on the State Cabinet, p. 140. 1857.

Also S. concava : Idem, p. 115. 1857.

Shell large, from two to three and a half inches wide on the hinge-line,
concavo-convex or subhemispheric, broadly semielliptical or subcircu¬
lar, sometimes subtriangular from becoming narrowed in front. The
proportions vary from nearly equal length and breadth to a width one-
fourth to one-third greater. The hinge extremities are sometimes
salient, but often rounded.

Ventral valve varying from moderately to extremely convex, and be¬
coming gibbous in the middle, rounded upon the umbo and little elevated
above the hinge-line, with beak small and scarcely incurved : in some
specimens, the centre of the valve is elevated in a median ridge.
Dorsal valve usually almost flat or slightly concave in the upper and
central portions, becoming suddenly deflected towards the margin ; in
some specimens, regularly concave.

STROPHODONTJE OF THE HAMILTON GROUP.

97

Area of the ventral valve nearly on* a plane with the axis of the shell,
about a line in width, gently narrowing towards the extremities, ver¬
tically striated, with the margin crenulated for more than half the
distance from the centre to the extremities. Area of the dorsal valve
almost rectangular to that of the ventral valve, very narrow and nearly
linear throughout, sometimes narrower in the middle, striate and cre-
nulate as in the opposite valve ; with a small, smooth triangular space
beneath the apex.

The surface of the ventral valve is marked by sharply elevated, strongly
crenulated striae, between which are sometimes one or two less eleva¬
ted striae similarly crenulated, and still finer striae between the latter.
In other specimens there are wider spaces of finer equal striae between
the stronger ones ; and, in still other examples, the striae are nearly
all strong and sharply elevated, with few finer ones, which soon rise
to the strength of the others. Close undulating concentric striae cover
the whole surface. The dorsal valve is marked by distant sharp ele¬
vated striae, between which there are from three to six and rarely ten
finer striae, which are very finely crenulated by concentric striae.

In some specimens the ventral valve is marked by an irregular fold or
ridge down the middle, and there are sometimes a few incipient plica¬
tions on one or both sides towards the margin of the shell. These plica¬
tions likewise affect the dorsal valve.

The interior of the valves is finely pustulose. The divaricator muscu¬
lar impressions of the ventral valve are large and spreading, about as
wide as long, extending nearly half the length of the valve, and deeply
striate ; while the occlusor impressions are elongate-ovate or cordiform,
and strongly marked. The muscular impressions of the dorsal valve are
strong and divided above by a rounded ridge which supports the strong
bifurcate cardinal process, each division of which is bilobed, and the sur¬
faces roughened for the muscular attachment.

Some of the more characteristic form» of this species are illustrated on Plate xvi. In a
large number of specimens, the convexity of the ventral valve is less than in the
figure given.

[ Palaeontology IV.] 18

98

PALAEONTOLOGY OF NEW-YOKK.

This species is closely allied to the S. hemispherica, differing in the surface
marking, and to some degree, in the muscular impressions ; and it is impossible
to determine how far these modifications may extend, without a large series of
specimens in better preservation than usually found. In the Hamilton group, the
species is subject to considerable variety of form and convexity, but is always
readily recognized among the other species of the group. In the collections there
ifc a single example of a dorsal valve, which is moderately concave for a little more
than half its length, with some obscure concentric wrinkles ; beyond this, it is
deflected almost at right angles to the plane of the upper part of the shell. The
muscular impressions are shorter and wider than usual, and the cardinal process
is shorter and stronger. In comparison with the prevailing forms, this might have
been regarded as a distinct species.

Geological formation and locality. This species occurs rarely in the Cornife-
rous limestone in New-York, and is very common in the soft shales of the Hamil¬
ton group in all the localities from Cayuga lake westward to Lake Erie. It is
apparently limited to the upper beds of the group, or to the Moscow shale, and
is comparatively rare below that horizon. At the present time, it is unknown to
me in any position higher than the Hamilton group.

Strophodonta perplana,

PLATES XI, XII, XVII & XIX.

Strophomena perplana : Conrad, Jour. Acad. Nat. Sciences, Vol. viii, pa. 257, pi. 14, f. 11. 1842.
Strophomena pluristriata : Conrad, ut sup. p. 259.

Strophomena delthyris : ut sup. pa. 258, pi. 14, f. 19.

Strophomena crenistria : Hail, Report Fourth Geological Dist. New-Yorlc, p. 171, f. 4. 1848.
Strophomena ( Strophodonta ) fragilis : Hall, Tenth Report on State Cabinet, p. 143. 1857.
Strophodonta fragilis : Hall, Report Geological Survey of Iowa. pa. 496, pi. 3, f. 6a, 6c. 1858.

Shell semielliptical ; the length varying from two-thirds to three-fourths
the width, which is from half an inch to two inches ; slightly concavo-
convex, and often nearly flat : hinge-line equalling or often a little
greater than the width of the shell below ; the extremities usually
somewhat salient, except in extremely old shells. Margins of the shell
often a little contracted just below the hinge-extremities, making the
width less than below ; but the sides are frequently nearly straight
for half their length, and the front broadly rounded with the margin
attenuate.

STROPHODONTiE OF THE HAMILTON GROUP.

99

Ventral valve very little convex, the greatest convexity above the
middle of its length, with frequently a few obsfeure concentric wrinkles
near the apex, and sometimes upon the body of the shell : apex
scarcely rising above the hinge-line, and slightly incurved. Dorsal
valve gently concave, and often nearly flat.

Area of the ventral valve usually less than a line in width, inclined at
an angle of 40° to 50° to the plane of the margins and curved in the
upper part, vertically striated in its whole extent and crenulate on
the inner margin ; sometimes a flat triangular space in the place of a
foramen, with a narrow callosity in the middle, but this feature is not
always observable. Area of the dorsal valve about half as wide as that
of the ventral, gently curved outwards, leaving an angle between the
two of more than 90° : the centre is marked by a narrow callosity or
an impressed space.

Surface covered by fine subequal striae, those of the ventral valves being
the finer, extremely sharp and often gently undulating, increasing
both by bifurcation and intercalation, and crossed by fine, even
concentric striae. In some specimens the longitudinal striae rise at fre¬
quent and regular intervals into minute granules, evidently the bases
of minute spines, which have covered the surface of the ventral valve.
The dorsal valve is marked by fine even rounded striae which are can¬
cellated by close concentric striae, and the same obscure concentric
undulations as are observed on the surface of the ventral valve. Very
rarely there is some interruption to the regularity of the striae, appa¬
rently owing to an injury which has often caused the concentric striae
to curve towards that point, and the radiating striae to converge, ma¬
king a kind of seam or cicatrix.

In specimens of the same species from Illinois and Iowa, the striae on
the ventral valve are less sharp, and arranged in fascicles of four to six
finer ones between the stronger and more elevated striae. In the speci¬
mens from the Chemung group, the striae are often very irregular, rising
at intervals into elongate pustulose elevations, and again subsiding to
delicate lines.

/

im

PALEONTOLOGY OF NEW-YORK.

The interior of the ventral valve is marked by large flabelliform di-
varieator muscular impressions, extending more than half the length of
the shell; narrow above, with sides nearly' straight, curving below and
deeply divided in front, each division showing four or five lobes. The
occlusor impressions are two semioval elevated spots a little below the
apex, the centre becoming a thickened ridge or process lying beneath
the place of the foramen, with a cavity on each side for the insertion of
the bifurcate dorsal cardinal process. The muscular impression is exca¬
vated in the substance of the shell, the margin in the upper part being
elevated and marked by a row of pustules. In young shells the muscular
impressions are often indistinctly limited, but in the older shells are
very well defined. The muscular impressions of the dorsal valve are dis¬
tinctly but not strongly marked : these are separated above by a median
ridge which divides in the bifurcating cardinal process, and this is
supported on each side- by an oblique pustulose ridge which gradually
merges into the surface of the shell.

In general, the shell is readily recognized by its nearly flat form and
fine nearly equal striae. In the muscular impressions of the interior, it
resembles S. beckii of the Lower Helderberg group, but is never so strongly
wrinkled. The smoother specimens of that species in limestone are not
easily distinguished from the ordinary forms of this one as they occur in
the Corniferous limestone.

The original of S. perplana of Conrad was from the Onondaga limestone of the
Upper Helderberg group, a specimen about five-eighths of an inch in width.

The S. pluristriata of the same author was described from an impression of the
ventral valve in arenaceous shale ; and similar specimens from the same vicinity
as the original show that it does not differ from the S. perplana, while casts of
that species occur in the same association. The S.fragilis, Hall, was described
from specimens in the calcareous shale of the Hamilton group in Western New-
York, and from the same horizon at Rock island in Illinois.

The Strophomena delthyris of Conrad, from the Chemung group, is doubtless a
large individual of S. perplana , since I find that similar large casts of this species
occur in the same formation.

STROPHODONTJE OF THE HAMILTON CROUP.

101

The figures of Plates xi & xn have already been referred to, pages 81 & 87.

Figures la-ld Plate xvii are of the ordinary forms of the species from the Hamilton
group of New-York.

Figure 1 c shows an enlargement of the area.

Figure If represents the surface characters of the Illinois and Iowa specimens.

" Figures l<g and 1A are interiors of the ventral valve.

Figure \l is a cast of the ventral valve of a large specimen.

The figures Ik, u are of the interior of the dorsal valve enlarged.

Figures 1 n-o are enlargements of the striae of New-York and western specimens.

On Plate xix, figures 15-19, are illustrations of the species as it has been observed in
the Chemung group.

Geological formations and localities. This species is found in the Schoharie grit
of Albany and Schoharie counties, in the condition of casts of the interior with
impressions of the exterior surface. It is found in the Comiferous limestone, usually
smaller than the medium size of specimens in the Hamilton group, but rarely in
larger forms : occurring in the Helderberg mountains ; at Schoharie ; at Cherry-
valley, and at Williamsville, N.Y. ; and near Columbus, Ohio ; and at the Falls
of the Ohio river.

In the Hamilton group, it is found at numerous localities throughout the extent
of the outcrop. In the eastern part of the State, it usually occurs in the condition
of casts of the interior with impressions of the exterior. In the calcareous shales
on Cayuga and Seneca lakes, at Moscow, York, Pavilion, Darien, and at Eighteen-
mile creek, the shell is preserved in great perfection. We find the species in the
same horizon at Rock island, Illinois ; and near New-Buffalo, Iowa.

In the Chemung group, it is found at Chemung-narrows ; along the line of the
Blossburg railroad, and at other places.

Strophodonta demissa.

PLATE XVII.

Strophomena demissa : Conrad, Journal Acad. Nat. Sciences, Philadelphia, Vol. viii, pa. 258, pi. 14,

f. 14. 1842.

Strophomena ( Strophodonta ) demissa : Hall in Tenth Report on State Cabinet, p. 137. 1847.
Strophodonta demissa : Hall, Report Geological Survey of Iowa, pa. 495, pi. 3, f. 5. 1859.

Strophomena demissa : Billings, Canadian Journal, 1861.

“ « « Geology of Canada, p. 367. 1863.

Shell semielleptical, usually wider than high, length and breadth often
nearly equal : hinge-line equalling or greater or less than the width
of the shell below, abruptly contracted beneath the extremities,
which are often auriculate ; in some specimens the sides are nearly
straight, and parallel for more than half the length of the shell.

1©£

PALAEONTOLOGY OP NEW-YOEK.

Yentral valve regularly convex, often gibbous; greatest elevation
nearly central, and sometimes subangulated along the middle : umbo
small and prominent, with the apex slightly incurved and extending
beyond the plane of the area ; surface a little concave towards the car-
’ dinal angles, which are slightly deflected. Dorsal valve moderately
concave, rarely following the convexity of the opposite valve ; some¬
times an undefined median depression extends from beneath the apex
to the front of the shell.

Area of ventral valve variable, usually of moderate width, from yf o to
t&o of an inch wide in the centre, having a low triangular outline, con¬
cave in the middle and for a considerable distance on each side of the
beak, strongly striated transversely and more faintly longitudinally,
sometimes marked along the middle by a subangular elevation ; inner
margin crenulated for nearly its entire length. There is no foramen,
but sometimes a smooth triangular space beneath the beak. Dorsal
area narrow and usually linear, sometimes wider and sometimes nar¬
rower in the middle, and the margin for a short space free from crenu-
lations. The planes of the two areas are inclined so as sometimes to give
less than a right angle between them, but generally a greater angle,
and along the middle the two are often nearly in the same plane.

Surface marked by numerous crowded striae, about nine or ten of which
are much stronger and more elevated on the umbo of the ventral
valve, with finer ones coming in between and on either side : striae
frequently increasing by intercalation and bifurcation, until they
become very numerous and much finer at the margin. On the
dorsal valve, the striae are similar to those of the ventral valve. In
well-preserved specimens, fine concentric striae cover the entire sur¬
face, but the greater number of specimens do not preserve these mark¬
ings. The coarser striae are sometimes seen separated on the middle
of the shell, each one presenting the appearance of a fascicle of striae,
which, spreading, cover the lower part of the shell with extremely
fine crowded striae.

STROPHODONTiE OF THE HAMILTON GROUP.

103

The interior of the ventral valve, and casts of the same, show a large
flabelliform divaricator muscular impression, which is somewhat widely
separated in front, and each division distinctly lobed. The occlusor
muscular impressions occupy a semielliptical space on each side of a
narrow central depression, the marking on either side being double in
well-preserved specimens. The upper extremities of this impression are
close under the arch of the umbo, and separated by a smooth space from
the divaricator impressions.

Beyond the muscular impressions, the interior surface is minutely
pustulose, the points being more prominent just without their limits ;
beyond which, the course of the vascular impressions can be distinctly
traced.

In the dorsal valve, the anterior and posterior occlusor muscular
impressions are very conspicuous and deeply marked, and often limited
by an elevated ridge, a narrow longitudinal ridge dividing the two pairs.
On each side, and below the muscular impressions, the surface is marked
by small pustules or tubercles ; and beyond these the surface is minutely
pustulose, the vascular impressions becoming distinct towards the
margin. The cardinal process is divided from the base, the divisions
strongly diverging.

The varieties of form and gradations of size usually observed in this species
are illustrated on Plate xvii. In the greater proportion of New-York specimens,
the hinge-line is usually extended very little, if at all, beyond the width of the
shell below ; but in the western specimens, figs. 2 h and 2 i, the extremities are
much produced. In these specimens the striaa do not diminish towards the margin,
as in those from more eastern localities.

In figure 2 r the area is purposely broken away to show the extent of the
occlusor muscular impressions. The absence of foramen, or callosity marking its
place, is shown in several of the figures.

Beginning its existence in the Schoharie grit, this species there attains its full
size ; but its muscular markings are rarely well developed in the specimens from
that rock, probably owing to the tenuity of the shells.

In the Corniferous limestone, the specimens (as far as they have come under
my observation) do not reach the full dimensions of the species, but are thick
and robust, having a high degree of convexity.

1®4

PALAEONTOLOGY OF NEW-YORK.

It is common and even abundant in many localities of the Hamilton group,
where it reaches a perfection and degree of development not elsewhere observed.
In the eastern part of New-York, in the arenaceous portions of the group, it is
usually seen in the condition of casts of the interior ; and its more perfect deve¬
lopment is in the calcareous shales beyond the Genesee valley. In Illinois and
Iowa, in the calcareous shale of the same horizon, it is abundant. It Occurs in the
Chemung group at several localities in Western New-York, but is by no means a
conspicuous fossil.

Geological formations and localities. This species is found (as already observed)
in the Schoharie grit, Corniferous limestone, Hamilton and Chemung groups. In
the Hamilton group, some of the principal localities are Darien in Genesee county,
and Eighteen-mile creek in Erie county ; likewise on Seneca and Cayuga lakes,
and at some more eastern localities.

It has been found in the same horizon in Pennsylvania, Maryland and Virginia ;
at Rock island (Illinois), New-Buffalo and Pine creek (Iowa).

Stropliodonta nacrea.

PLATE XVIII.

Strophomena ( Strophodonta ) nacrea : Hall, in Tenth Regents’ Report on State Cabinet, p. 144. 1857.
Strophomena lepida : Hall, Geol. Report Iowa, Vol.i, part 2, pa. 493, pi. 3, f. 3 a, b, c. 1858.

Shell small, semielliptical, having a brilliant nacreous lustre* : hinge¬
line crenulated, equalling or a little less than the greatest width of
the shell below, and sometimes terminating in more or less distinct
angles. Dorsal valve concave. Ventral valve sometimes regularly con¬
vex, flattened at the margins, often depressed-convex in the umbonal
region and abruptly arched towards the front : beak very small and
depressed : area very narrow, linear, without foramen. The area of the
dorsal valve is often nearly as wide as that of the ventral valve.
Surface apparently smooth, but under a lens showing very faint con¬
centric lines of growth, with sometimes obscure traces of radiating
lines.

The muscular impressions in the ventral valve extend more than half
the length of the shell. The divaricator muscular imprints are deeply

* The shell has often a brownish or coppery metallic lustre, probably owing to the staining of the
surface from the decomposition of iron pyrites.

STR0PH0D0NTJ3 OF THE HAMILTON GROUP.

105

depressed, elongate-ovate, narrowing above and somewhat widely sepa¬
rated below ; while the occlusor impressions are narrow-ovate spots on
the thickened portion of the shell, and below these extends a narrow ele¬
vated band separating the other impressions. In the dorsal valve, the ante¬
rior and posterior occlusor muscular impressions are small and not
strongly defined. The cardinal process is slender, bifurcating, with a
narrow rounded ridge extending from its base down the middle of the
valve. The interior of the shell, excepting the muscular impressions, is
studded with prominent scattered granules or papillae. The crenulations
on the hinge-line are rather distant, but conspicuous.

Even in fragments this species may be always distinguished from its
associates by the peculiar lustre.

This species bears some resemblance to Orthis lepis of Bronn, but is much less
distinctly striated than well-preserved specimens of that shell, and the crenula¬
tions of the hinge-line are only about half as many as in the European species.
The generally smooth surface and strong lustre of the two, in specimens before
me, give a similarity in external appearance, which is not confirmed by a compa¬
rison of the details. Observations of a larger number of specimens has shown
that there are no constant characters by which -the New-York and Iowa forms
can be separated from each other, and the S. lepida therefore becomes a synonym.

Geological formations and localities. In the shales of the Hamilton group on the
shore of Lake Erie, at Darien, York, and on the shore of Canandaigua lake. It
occurs in the same formation -at Rock island, in Illinois ; and is cited by Mr.
Billings, as having been found in the Hamilton shales in the town of Bosanquet in
Canada West. It also occurs in the Corniferous limestone at East-Yictor and at
Lapham’s mills in Ontario county, New-York.

[ Palaeontology IV. ]

14

1©®

PALAEONTOLOGY OF NEW- YORK.

Strofiliodonta inequistriata.

PLATE XVIII.

Strophomena inequistriata : Conrad, Jour. Acad. Nat. Sciences, Philadelphia, 1842, Volviii, pa. 254,

pi. 14, f. 2.

Strophomena inequistriata : Hall, G’eol. Rep. 4th District, 1843, p. 290, f. 4.

Compare Orthis interstrialis : Phillips, Pal. Fossils, 1839, pa. 61, pi. 25, f. 103 o, 6, c. d.

Strophomena ( Strophodonta ) inequistriata : Hall, in Tenth Report on the State Cabinet, p. 142. 1857.

Shell semioval or somewhat semicircular in outline : hinge-line extended
beyond the width of the shell below ; extremities acute, sometimes
auriculate. Rarely the sides are nearly straight below the auricu-
late extremities, and the basal curve rather straightened on each side
and produced in a subnasute extension in the middle.

Ventral valve usually regularly convex, and often more gibbous in the
middle and abruptly arched towards the hinge-line, depressed-convex
on the disc, with the margin towards the front more abruptly curving ;
sometimes gently sloping towards the front and abruptly constricted
on the sides below the cardinal extremities, which are deflected to the
ventral side : the beak is small, scarcely prominent on the hinge-line.
Dorsal valve moderately concave, often more deeply concave ; some¬
times moderately concave in the upper and middle part, and suddenly
deflected towards the front.

Area of the ventral valve narrow-linear, extending to the extremities
of the hinge-line, striate vertically, with the inner margins crenulate
from one-half to two-thirds the length from the beak to the extremi¬
ties : foramen none ; a slight linear elevation extends across the
area. Dorsal area scarcely more than half as wide as the ventral area,
and, in very perfect specimens, having a narrow elevated ridge cross¬
ing it in continuation of that of the opposite 'valve.

Surface of the entire shell marked by slender distant elevated striae,
which are increased by interstitial additions ; the interspaces occupied
by much finer closely arranged striae, which are scarcely visible to the
naked eye, and crossed by fine concentric striae.

STROPHODONTiE OF THE HAMILTON GROUP.

im

In the interior of the ventral valve, the occlusor muscular impressions
occupy a narrow subquadrangular elevated space just beneath the apex ;
while the divaricator muscular imprints occupy a short broad space on
each side, and are limited by nearly vertical or slightly curving ridges
which have in some degree the appearance of dental lamellae : within
the limits of these ridges, the muscular imprints are not strongly marked.
In the dorsal valve, the posterior occlusor imprints are broad and extend¬
ing far towards the cardinal line, and often limited externally by a low
pustulose ridge : the anterior impressions are small and narrow, sepa¬
rated by a narrow mesial ridge and margined by diverging elevated
ridges, which, above the impression, are united in the mesial ridge from
which proceeds the bifurcating cardinal process : the divisions of this
process are broad and somewhat flattened vertically or a little obliquely,
and sometimes grooved on the inner side and distinctly bilobed at the
extremities.

The condition of the muscular imprints is subject to considerable
variation; for in some specimens those of the anterior occlusors are
raised in two prominent processes to a height greater than the enclosing
ridges, and sometimes the imprints remain depressed, and the enclosing
ridges are extremely elevated, arching over and nearly enclosing the
muscular area. Just without the muscular areas, in both valves, the inte¬
rior surface is rather strongly pustulose, and beyond this it is finely
pustulose in lines corresponding to the external striae; while the dorsal
valve, more often than the ventral, is marked by strong vascular
impressions.

This species bears such a close . resemblance to the figures of Prof. Phillips
cited above, that in my Report of the Fourth Geological District of New-York I
regarded the two as identical. I am now disposed to doubt the propriety of 'this
reference. It varies much in the convexity of the ventral valve p being in some
individuals extremely gibbous, and in others very moderately convex. The area
is subject to some variations' in width, perhaps owing to compression; and in
some specimens, the area of the dorsal valve is nearly as wide as the ventral area.

The general surface character of the convex valve is much like that of good
specimens of Strophomena alternatu of the Trenton limestone, .but it does not

108

PALEONTOLOGY OF NEW- YORK.

appear to be subject to such extreme variations in respect to the striae. It resem¬
bles very closely, in its surface markings, the S. textilis, but is always smaller, with
a more extended hinge-line, and never so flat as that species. In the same respects
it is not very dissimilar to some of the other species of the Upper Helderberg and
Hamilton groups ; and it has been confounded with S. inequiradiata, which is a
much larger shell, with different internal characters. Its surface striae are more
delicate than any of the other species, and its muscular impressions are peculiar
in form and details, and entirely unlike those of any other species, as shown in
figures 2 h, i, k, on Plate xvin.

The general characters of the species and varieties* of form are shown in figures
2 a-k, on Plate xvm.

After critical comparison of all the other species of the Hamilton group, I am
convinced that the species of Mr. Conrad is the one I have here described and
illustrated, although not entirely corresponding with the original description.

Geological formations and localities. This species occurs in the Corniferous lime¬
stone somewhat^ rarely, but is common in the Hamilton group, and is at present
unknown in any higher position. It is common in localities along the shores of
Seneca, Cayuga and Canandaigua lakes; at Moscow; York; Pavilion; Darien;
Eighteen-mile creek, and numerous other places in the Hamilton group. Its locali¬
ties in the Corniferous limestone have already been enumerated on page 88.

Strophodonta textilis.

PLATE XVIII.

Strophomena ( Strophodonta ) textilis : Halx., in Tenth Report on State Cabinet, p. 141. 1847..

Shell very thin, nearly flat, transverse, semioval, sometimes nearly as
long as wide, the length being from two-thirds to four-fifths the width ;
hinge-line equalling or sometimes a little greater than the width of
the shell below, with salient angles.

Ventral valve slightly convex. Dorsal valve gently concave.

Area of the ventral valve narrow, almost linear, and extremely narrow
towards the extremities, vertically striated, with a narrow callosity in
the centre ; the inner margin crenulate for about two-thirds its length.
Area of the dorsal valve linear, scarcely half as wide in the middle as
that of the opposite valve.

STR0PH0D0NT2E OF THE HAMILTON GROUP.

S 09

Surface marked by distant slender elevated radiating striae, which are
increased by interstitial additions ; and the interspaces are marked by
five, six or more extremely fine striae, which are cancellated by finer
concentric striae. There is apparently no essential difference in the
surface markings of the two valves.

In the ventral valve, the occlusor muscular impressions occupy very
narrow spaces just beneath the beak : the divaricator muscular impres¬
sions are large flabelliform, each one divided into several lobes, and
margined on each side for a part of their extent by a pustulose ridge ;
while the anterior limits are not usually well defined. In the dorsal
valve, the posterior occlusor imprints are large semioval and concave,
defined by a slight thickening of the shell, and separated by a rounded
mesial ridge which divides below ; the marks of the anterior occlu-.
sors being at the lower extremities of this divided ridge. The cardinal pro¬
cess is bifurcate from its origin, and comparatively slender.

The interior surface, beyond the muscular impressions, is marked by
somewhat distant minute elongate papillae which are arranged in lines
in the direction of the striae. The interior of a single dorsal valve shows
also prominent radiating folds ; but this feature may not be constant.

This species may be readily distinguished by its nearly flat form and large
size. The surface strise .are similar to those of S. inequistriata , and to those of the
dorsal valve of S. concava and of S. inequiradiata. The muscular impressions of the
ventral valve are similar to those of the S. perplana ; but the interior of the dorsal
valve of that species exhibits a shorter cardinal process, and a different disposi¬
tion of the muscular impressions. The latter are very similar to those of the
dorsal valve of S. inequistriata , as is shown in figures 2 h and d of Plate xvm ;
while there is a great contrast in the ventral valves of the two species, as shown
in the cast of S. texhlis, figure 4, and the interior of S. inequistriata , figure 2 k of
the same plate.

Figures 3 a, b, c, of Plate xvm illustrate the usual forms of the species ; while
figure 4 is unusually extended on the hinge-line.

Some farther illustrations of the interior are given upon Plate xix a.

Geological formations and localities. This species is known in the Hamilton group
on the shores of Seneca and Cayuga' lakes ; Mud creek and West-Bloomfield,
Ontario county; York and Moscow, Livingston county; Bethany, Covington and
Darien, Genesee county ; and the shore of Lake Erie. It occurs also in the Tully
limestone ; and a single dorsal valve has been seen from the Corniferous limestone.

11©

PALAEONTOLOGY OP NEW-YOEK.

STROPHODONTaE OP THE CHEMUNG GROUP.

* Strophodonta cayuta (n. s.).

PLATE XIX.

Referred, to S. interstrialis of Phillips,. Geol. Rep. 4th District New-York, p. 266. 1843.

Shell semielleptical ; length and breadth about as three to five, while
in some specimens the length is nearly equal to the width ; sometimes
the width on the hinge-line is twice as great as the length : cardinal
extremities usually more or less produced, and often auriculate.
Ventral valve usually of moderate convexity, sometimes but slightly
convex on the upper half of its length, and abruptly inflected towards
the front; while there is frequently a longitudinal ridge down the
middle. In the shaly beds, this valve is compressed and only gently
convex. The dorsal valve is usually very gently concave.

Area of the ventral valve narrow-linear, and the inner margin crenu-
lated for more than half its length. The dorsal area is barely a crenu-
lated line.

Surface marked by distant sharp elevated striae, • between which are
four, five, six or more extremely fine striae, which are increased by
interstitial additions.

The interior of the ventral valve, as shown in casts, is marked by a
broad bilobed divaricator muscular impression, , which is wider than long,
spreading from the apex, and surrounded by an elevated rim. The occlu-
sor muscular impressions are minute spots just below the apex of the
umbonal cavity. The divisions of the muscular impression are deeply
striated, in the cast, and often show subordinate lobes near the margin.
The surface around the muscular impressions is papillose.

This species bears much resemblance to S. mequistriata of the Hamilton group
in its external characters, but the ventral valve is not so regularly convex, and
the dorsal valve is less concave ; while in the muscular impressions it differs con¬
spicuously. In the coarser sandstones of the Chemung group, the specimens of this
shell are usually smaller and more convex ; while the striae are not so regular and
even as in those from the more shaly portions of the formation. It is scarcely

STROPHODONTiE OP THE CHEMUNG GROUP. HI

known except in the condition of casts, the. shell being rarely preserved in any
of the specimens obtained.

The figures 1-5 on Plate xix show the ordinary forms of casts of the ventral
valve ; no casts of dorsal valves in a condition to be illustrated, have been
found up to this time. '

Geological formation and localities . In the Chemung group, on Cayuta creek;
near Elmira ; along the line of the Blossburgh railroad ; near Bath in Steuben
county, and in other localities in the southern counties of the State.

Strophodonta mucrpnata.

PLATE SIX A.

Strophodonta mucronata : Conrad, Jour. Acad. Nat. Sciences, Philadelphia, Vol. viii, p.257. 1842.

The description of Mr. Conrad is as follows : —

“ Winged : inferior valve convex-depressed, with crowded unequal
“ radii, and very fine transverse wrinkles; umbo flattened; apex on
“ a line with the hinge-margin ; hinge extremities acutely angulated.”
The species which I have identified with this one is a semioval shell,
the proportions of length and breadth varying considerably, the hinge¬
line often extended beyond the width of the shell. The ventral valve is
very depressed-convex, and the dorsal valve nearly flat. The area of the
ventral valve is extremely narrow, and the inner margin crenulated for
about half its length. The surface is marked by distant sharp elevated
striae, with the interspaces occupied by numerous finer undulating striae.
The muscular impressions are faintly marked ; those of the occlusOr
muscles occupy a minute space near the apex of the cast ; and the diva-
ricator muscular impressions are elongate and spreading, and partially
limited by an oblique pustulose ridge on each side, in form and cha¬
racter like those in S. perplana, but less strongly defined. The cardinal
process of the dorsal valve is slender, and supported at its ’base by an
oblique ridge on each side, between which the muscular markings are
faintly impressed.

This shell has the general form and the tenuity of S. perplana ; but the muscu¬
lar markings are not proportionally as large in the ventral valve, and the cardinal
process of the dorsal valve is much more slender and less diverging. The surface

112

PALAEONTOLOGY OF NEW-YORK.

strige are of the character of S. inequistriata, S. textilis and others, a condition
sometimes assumed by S. perplana in the Hamilton shales of Iowa ; hut we have
that species in the same association with this one, showing its characteristic
muscular impressions, with a somewhat wider area than S. mucronata , and the
surface striae even or raised at intervals into elongate' nodes, but never having
the elevated strige and equal interspaces with finer strige shown by this species.

Although it is not always (and in some localities not often) . produced at the
hinge-extremities, it is the only form which I can identify with Mr. Conrad’s
description. The S. elmira is too convex on the ventral valve, and moreover rarely
occurs except in casts which give the strong muscular impression a prominence
that would not have been overlooked in the description.

Figures 5 and 5 a, Report ( p. 266) of the 4th District of New- York, are of this species,
and not identical with 5 b, c, which are of the S. cayuta.

The figure given by Mr. Vanuxem (Geol. Report of the 3d District, page 174, figure 1)
is of this species, found in the neighborhood of Ithaca.

Geological formation and localities. In the Chemung group, at Chemung-narrows ;
at the Inclined plane of the railroad near Ithaca ; near Elmira and Bath ; and
also at Cortlandville and many other localities in the central and southern parts
of the State.

Strophodonta coelata (n. s.).

PLATE XIX.

Shell resupinate, semielliptical or semicircular ; the cardinal extremities
extremely produced.

The cast shows that the ventral valve is concave, being moderately
convex upon the umbo, and sloping gently downwards to below the
middle ; beyond which, the anterior portion is abruptly deflected.

The area is of moderate width, flat and striated, with the margin crenu-
lated for nearly its entire length ; the crenulations elongate and a
little oblique.

The divaricator muscular impressions form a broad flabelliform scar,
which is once and a half as wide as long, and has been nearly surrounded
by an elevated rim. Each division is marked by eight or nine distinct
lobes. The occlusor impressions occupy semioval spots in the upper part
of this area, and are separated by a narrow ridge, which becomes broader

STROPHODONTiE OP THE CHEMUNG GROUP.

above and is truncate at its extremities. Outside of the muscular impres¬
sion, the surface is punctate or papillose ; and from the commencement
of the abrupt curvature, it is marked by strong vascular impressions.
The cast of a convex dorsal valve found in the same strata shows the
marks of a strong nearly vertical cardinal process, with remains of socket
plates and strong impressions of the occlusor muscles.

Since we know but this species in the Chemung group with a concave ventral
valve, it is inferred that the convex dorsal valve may belong to the same species.
The specimens are illustrated in figures 7 and 8 of Plate xix.

Geological formation and locality. In some arenaceous beds of the Chemung
group, to. the northwest of Elmira.

Stropliodonta perplana var. nervosa.

PLATE XIX.

Strophomena .nervosa : Hall, Geol. Report of 4th District, p. 266, f. 1.

Strophomena delthyris : Conrad, Jour. Acad. Nat. Sci. Philadelphia, Vol. viii, pa. 258, pi. 14, f. 19.

Shell very depressed, subplano-convex ; semielliptical, with hinge-
extremities often extremely produced.

Ventral valve very slightly convex ; and dorsal valve barely concave.
Surface marked by sharp elevated undulating striae, which are irregu¬
larly bifurcated, and often swelling at unequal intervals into node-like
expansions.

The casts, as far as observed, are undistinguishable in character from
those of S. perplana.

In describing from the general form of the shell and surface characters, no one
would suspect this to be of the same species as the regularly striated S.
perplana of the Hamilton group and Corniferous limestone. A comparison of
numerous imperfect specimens retaining some portion of the shell, as shown in
figures 15 and 16, together with casts of the interior of the same, has left no
doubt as to the propriery of referring them to S. perplana.

Figure 14 is from the original specimen of S. nervosa, and is a cast of the ventral-
valve in soft olive shale ; while figure 15 is part of a specimen retaining the shell
essentially entire.

[ Palaeontology IV.]

15

114

PALAEONTOLOGY OF NEW-YORK

The casts figures 17, 18 and 19 preserve the usual characters of the casts of
the ventral valve of S. perplana; the marks of strife, as far as seen, being more
regular than those of the shell figure 15. These casts I infer to be similar to the
specimen from which Mr. Conrad described Strophomena delthyris , loc. cit.

Geological formation and localities. These specimens present the usual aspects
of this species and variety in the Chemung group in Tioga county ; near Ithaca,
and along the line of the Corning and Blossburgh railroad. The more characte¬
ristic forms of those designated S. nervosa were found near Bath, and at
Campbelltown in Steuben county.

Strophodonta demissa.

PLATE XIX.

[ Described page 101 of this volume, Hamilton group.]

The condition of this species, in the Chemung group, is illustrated in figures
8-12. Figure 8 is a somewhat distorted cast of a ventral valve which shows no
muscular markings. Figure 10 is a similar cast, a little more extended on the
hinge-line; while figure 9 is extremely extended at the cardinal extremities.
Figures 11 and 12 are views of a cast of a ventral valve scarcely differing in
condition from the better preserve*! specimens in the Hamilton group.

The casts and impressions of this shell in the Chemung group frequently show
broad radiating folds, as partially illustrated in figure 9.; and the central portion
is often produced into a nasute extension.

Geological formation and localities. This species occurs oil Chemung creek and
at Chemung-narrows ; also near Jefferson in Steuben (Schuyler) county, and near
Bath ; and in Cattaraugus and Chautauque counties.

Strophodonta subdemissa.

The species described by me as Strophomena ( Strophodonta ) subdemissa, in the
Tenth Report on the State Cabinet, is only a variety of the S. demissa, as I sug¬
gested at the time. The conditions existing in the specimens then examined have
been found in a greater or less degree, and connected with other modifications, in
nearly all the specimens from Illinois and Iowa.

Strophodonta plicata.

Strophodonta plicata : Hail, Thirteenth Report on the State Cabinet, p. 90. 1860.

This species, which was founded on a well marked specimen from rocks of the
age of thejJIamilton group at Iowa city, has been obtained at Independence,
Iowa, and a specimen kindly forwarded to me by Mr. Orestes St.John.

CHONETES.

SIS

GENUS CHONETES ( Fischee, 1837).

The Genus Cponetes, having the general form of Strophodonta or
Strophomena and LEPT.®NA,-is distinguished externally from those forms
by the tubular spines on the outer margin of the ventral area ; and from
Productus by the manner in which these spines are disposed. In some
species, however, in addition to these, the surface of the shell is studded
with small spines as in Productus. Internally it has been shown by Mr.
Davidson to possess characters which ally it with Productus; and it
connects more nearly, by form and general features, the families of
Strophomenid^e and Production. .

In the ventral valve, the area is narrow but well-defined, with a
distinct foramen which is partially closed by a pseudo-deltidium, and the
remainder of the space is filled by a cardinal process from the opposite
valve. In the bottom of the cavity there is a longitudinal median ridge,
and on each side and close to it are the occlusor muscular impressions :
the divaricator impressions occupy a wider space, and usually are not
very well defined in their limits, though having the same general form
and features as those of Strophodonta.

In the dorsal valve, the teeth-sockets are well marked. The cardinal
process is entirely unlike that of the preceding genera, being simple at
its base, and bifid or grooyed at the extremity ; while the lateral divi¬
sions usually reach nearly as far as the central portion of the process,
and are separated from that by a groove more or less distinct. Sometimes
the lateral or accessory lobes are distant from the extremity, and sepa¬
rated in like manner by a groove.

In one or more of the slender forms of the process, these lateral lobes '
are situated at some distance from the apex, and appear like minute
processes on the sides. At its base, the cardinal process is continued in
a slender median ridge. The double occlusor impressions are small, and
from between them proceeds an elevated vascular marking which
assumes a reniform shape; this being a distinguishing feature of the genus,
which allies it with Productus.

11©

-PALAEONTOLOGY OF NEW-YORK.

The interior of the shells are strongly pustulose or papillose : the
little granules are arranged in the direction of the strise and along the
grooves of the exterior striae, which often become defined elevations
upon the inner surface of the shell.

So far as we at present know the species in the rocks of this coun¬
try, the genus begins its existence in the shales of the Clinton group,
where a single species has been found. There is no species known in the
Lower Helderberg group, and but a single one in the Oriskany sand¬
stone. Two species are known in the Schoharie grit, and three others
are common in the Corniferous limestone ; while others are added to the
number in the Hamilton and Chemung groups. Several species are known
in the Carboniferous limestones and in the Coal measures.

For the most part the species are of small size, and, when well pre¬
served, it is not very difficult to distinguish them ; but in their various
conditions of preservation, such as partially exfoliated and more or less
worn shells, casts of the interior and impressions of the exterior, in a
matrix varying from pure limestone to calcareous shale, and through the
arenaceous shales to a nearly pure sandstone, the specific relations often
become difficult of determination.

In a very large proportion of the specimens coming before me for
investigation, the cardinal spines cannot be seen, or are but imperfectly
preserved. Their comparative strength or direction often furnishes means
for specific distinction ; but I have not been able to satisfy myself that
the number of spines on the hinge-line is of specific importance, for
these are sometimes unequal on the two sides of the apex, and their
development seems often to be promoted or retarded by the irregular
growth of the shell. The number of these appendages does not depend on
the size of the shell; some of the larger species having only three or
four spines on each side of the beak, while in the smallest specimens of
the group in our rocks ( C . lepida), I am able to count six spines on each
side ; and in C. scitula, as many as six or seven, the bases only of many
of them being preserved in the substance of the shell as tubular
openings.

CHONETES.

117

In many specimens the spines can be se§n to originate near the inner
margin of the area, or along the hinge-line, and can he traced in the
substance of the shell in an oblique direction inwards, at first nearly
parallel with the margins of the foramen ; and it is only after becoming
free, that they take a vertical or obliquely outward direction.

The nature of these tubes penetrating the substance of the shell, has
been pointed out by Count Yon Keyserling*, and shown in his illustra¬
tions of Chonetes comoides ; but this function has been doubted by Prof.
De Koninck, who regards their obliquely inward direction as a con¬
trary indication.f In many of our specimens, however, I am able to
trace these tubes through the substance of the shell from the hinge-
margin (their opening into the interior being a little within the
margin), beginning near the triangular foramen, and penetrating the
shell to the upper edge of the area in lines parallel to the sides of the
foramen. Those nearest the centre are more closely arranged than those
at a greater distance : the former appear on the exterior as minute pus¬
tules, sometimes very close to the apex of the shell ; and in receding
from the centre, they become more prominent, and attain the character
of spines. In some examples, the obliquity of the tubes within the sub¬
stance of the shell is seen to become less and less on receding from the
apex, and they are often curved outwards before reaching the surface ;
but the connexion of these tubes with the spines is unmistakable.

In numerous examples of the casts left by the destruction of the ven¬
tral valve, the form of the tubes is well preserved in the infiltrated
matter ; and in these casts we often find evidence of the tubes near the
centre, where no spines are visible on the exterior surface of the shells
of the species, as in Chonetes logani and C. scitula.

* Geognostiche Beobachtungen auf einer Reise in das Petschora-land : By Count Alexander Von
Keyserling, 1846.

t “ These grooves do not appear to me to be produced by the cardinal tubes, as Mr. De Keyserlino
thinks, because iri this case they should take an opposite direction : I am led to believe that they depend
solely on the successive growth' of the shell.” Recherces sur les Animaux Fossiles, p. 190.

118

PALEONTOLOGY OF NEW- YORK.

CHONETES OF THE UPPER HELDERBERG AND HAMILTON GROUPS.

Clionetes liemisplierica.

PLATE XX. Fig. 6.

Chonetes hemispherica : Hall, Tenth Report on State Cabinet, p. 116. 1857.

Compare Strophomena gibbosa, Conkad in Annual Geol. Report, 1841, p. 54.

Shell transverse, semielliptical or somewhat semicircular, the greatest
width being on the hinge-line, which is often much extended and
conically auriculate at the extremities.

Ventral valve very ventricose or subhemispheric, excluding the extre¬
mities ; the umbo prominent, rising considerably above the hinge-line,
with the apex incurved. The hinge-line is marked by three, four or
more spines on each side of the middle.

Dorsal valve unknown.

Surface marked by numerous regular rounded striae, some of which
bifurcate near their origin and then continue simple throughout their
length ; a few bifurcate on the middle of the shell, and near the margin
there are sometimes intercalations of other striae.

The cast of the ventral valve preserves the striae with almost the same
distinctness as the exterior shell ; and the depressions between them
are marked by distant oblong pores, which indicate papillae of the same
form on the interior of the shell.

In a specimen of ordinary size, there are about 50 to 54 rounded
striae, and 7 to 9 (and rarely 12 or 14 in young specimens) in the
space of two-tenths of an inch, so few of which bifurcate that the gene¬
ral aspect is that of simple striae.

Some specimens, which appear to be younger individuals , of this
species, are of moderate convexity, and the striae* are finer and a little
more angular than in the larger and older specimens.

The figures 6 a, b, represent the ordinary forms of this species.

CHONETES OF THE SCHOHARIE GRIT.

119

The description of Strophomena gibiosa, given by Mr. Conrad* is as follows :
“ Sub trigonal ; inferior valve with back and umbo very prominent and the sides
“ compressed; surface with numerous equal slightly undulated strise which
11 bifurcate on the umbo ; hinge-extremities prominent and angulated .Locality :
“ Helderberg, in Onondaga limestone.”

The striae in C. hemispherica are not undulated, and they rarely bifurcate on
the umbo.

Geological formation and locality. In the Schoharie grit, in the Helderberg
mountains and at Schoharie, .and rarely in the Corniferous limestone.

Chonetes arena; ta.

PLATE XX.

'Chonetes arcuata .- Hall, Tenth Report on the State Cabinet, p. 116. 1857.

Shell semielliptical or approaching to semicircular ; the cardinal extre¬
mities often extended and auriculate.

Ventral valve arcuate, extremely gibbous or ventricose, with usually a
shallow undefined longitudinal sinus extending from the umbo to below
the middle or near the front of the shell, often constricted near the
cardinal extremities : umbo more or less gibbous, and raised in a
gentle elevation above the hinge-line, with the beak incurved. Hinge¬
line, in casts, apparently crenulate ; and on the exterior margin are
ten or twelve tubular spines, directed obliquely outwards.

Dorsal valve profoundly concave, following nearly the convexity of the
opposite valve, and having the centre a little elevated, corresponding
to the mesial depression.

Surface marked by fine even rounded strise, which increase both by
bifurcation and intercalation, crossed by extremely fine concentric
strise, with sometimes stronger subimbricating lines of growth.

The surface of the cast in the ventral valve is marked by closely
disposed oblong pits Or pores, from the papillose inner surface of the
shell. There is a constricted line extending from the apex, gently rece¬
ding from the hinge-margin and curving inwards at some distance from
the cardinal extremities, and thence to the front of the shell, leaving the
portion outside of this a little more elevated.

ISO

PALEONTOLOGY OF NEW-YORK.

The muscular impressions consist of a narrow central scar just below
the apex of the beak, for the occlusor muscles, with a central elongate
oval scar marking the place of the divaricator muscles ; while there are
two elongate ovate or pyriform scars, one on each side of the apex, and
spreading laterally just within the limit of the constricted line, figure 7 /.
The figures 7 a -f illustrate the usual form and convexity of the species. The character of
the cast of the ventral valve is shown in figures 7 e,f, where the marks of the internal
tubes of the area are conspicuous.

The cardinal spines are rarely visible, owing to the incurved margin which usually leaves
these appendages imbedded in the stone. In one specimen, however, five or six spines
are seen on one side of the apex. The shell of the area is penetrated from the interior
by numerous comparatively large cylindrical tubes, some of which terminate in elon¬
gate spines upon the exterior margin. In one specimen, fifteen of these tubes may be
counted on one side of the apex. In the casts or partial casts of the shell, these tubes
give the appearance of coarse crenulations.

This species is distinguished from C. hemispherica by being a little less promi¬
nent on the umbo, and by the shallow sinus, as well as the more numerous and
much finer strise. The cast does not preserve the marks of the striae so conspicu¬
ously, while the surface is more abundantly pitted, without being sensibly
arranged in distinct lines.

Geological formation and locality. This species has been found only in the Cor-
niferous limestone, near Williamsville and Clarence-hollow in Erie county, N. Y.

Clionetes acutiradiata.

PLATE XX.

Strophomena acutiradiata : Hall, Geol. Report 4th District New York, p. 171. 1843.

Chonetes acutiradiata : Hall in Tenth Report on the State Cabinet, p. 117. 1857.

Shell nearly semicircular, sometimes a little more than twice as wide
as long; the cardinal extremities produced.

Ventral valve moderately convex, sometimes a little gibbous in the
upper part, and frequently flattened or depressed at and below the
middle : umbo little elevated above the hinge-line ; greatest convexity
above the middle, from whence it curves gently to the front, somewhat
abruptly depressed towards the cardinal extremities, which are subau-
riculate and nearly flat. In two individuals, there is a distinct longi¬
tudinal sinus in the middle of the valve.

. CHONETES OF THE CORNIFEKOUS LIMESTONE.

mi

Dorsal valve unknown.

Surface marked by regular subequal rounded or subangular striae, which
are often irregularly bifurcated towards the margin or increased by
intercalations, and sometimes are nearly simple throughout their
length below the umbo, those of the cardinal extremities being very
irregular or nearly obsolete. Hinge-line marked oh each side of the
centre by four or five strong tubular spines which are directed obliquely
outwards.

The sinus ip the ventral valve is not uniform, and though evidently a
normal character where it occurs, it cannot be relied upon for characte¬
rising the species.

This species resembles the C. hemispherica ; but the form of all the specimens
is nearly semicircular, the cardinal extremities nearly flat, and it is never so gib¬
bous on the umbo, while the striae are finer and the cardinal spines more oblique.

In the surface markings, this species is more nearly like C. coronata , but its
form in the specimens known is quite distinctive.

Geological formation and locality. In the Corniferous limestone, near Williams-
ville ; Clarence-hollow ; and Stafford, New-York ; and in the same limestone at
the Falls of the Ohio.

Chonetes lineata.

PLATE XX.

Strophomena lineata : Vanuxem, Geol. Report of the 3d District New- York, p. 139. f. 6. ( The figure
6 is placed by mistake at the side of a section of Ichthyodorulite, f. 7.)

Chonetes glabra Hall in Tenth Report on the State Cabinet, p. 117. 1857.

Compare Strophomena crebristriata, Conrad, Jour. Acad. Nat. Sciences, Philadelphia, Vol. viii, pa. 254,

. pi. 14, f. 3.

Also Chonetes scitula, Tenth Report on the State Cabinet, p. 147.

Also Strophomena lineata, Conrad, Annu 1 Report, 1839, p. 64.

Shell subhemispheric, semioval in outline, with the cardinal line
equalling or greater than the greatest width of the shell below.
Ventral valve very convex, often ventricose, a little flattened in the
middle, regularly curving to the front and lower lateral margins, more
abruptly depressed at the sides, with the cardinal angles somewhat
flattened and often a little deflected to the ventral side.

[ Palaeontology IV.]

16

1S3

PALAEONTOLOGY OP NEW-YOEK.

Dorsal valve concave, the concavity less than the convexity of the
opposite valve. The area is narrow, that of the dorsal valve being a
bare line : the ventral area is twice as wide in the middle as near the
extremities. Cardinal spines small, and usually but slightly oblique to
the hinge-line, rarely more than two or three visible on each side of
the beak.

Surface marked by numerous slightly elevated rounded striae, a few
of which are more prominent near the beak, and increase by bifurca¬
tion and intercalation till the number on the margin becomes from
fifty-four to sixty or more. The striae towards the cardinal angles are
less conspicuous, and sometimes from exfoliation are not at all visible.
The entire surface in well preserved specimens is marked by extremely
fine concentric striae.

The cast is a little constricted within a line about two-thirds the
length from the beak, the middle being more gibbous, while it is a little
expanded beyond this line. The surface of the cast is punctate, moderately
marked by striae, becoming more strongly marked at the constriction
and from thence to the margin. The interior of the valve preserves
similar markings, the surface being papillose or pustulose. The muscular
impressions of the ventral valve are sometimes defined, and there is a
median longitudinal ridge. The interior of the dorsal valve is pustulose
in lines corresponding to the striae. The muscular impressions and base
of cardinal process are not defined in any specimens observed.

After an examination of a large number of individuals, I find the variation in
number of strite too great to offer any reliable character for specific distinction.

The species is doubtless the one figured by Mr. Vanuxem (loc. cit.); and I am
disposed to believe that the Strophomena crebristriata* and S. lineata of Conrad
(loc. cit.) may be the same species. It is most nearly allied to. C. yandellana, and
may perhaps be regarded as identical with that species. There are, however, cer¬
tain differences which are constant in all the specimens examined. The C. lineata
is always more gibbous ( See figs. 3/ and 4 d, Plate 20) : in C. yandellana the cavity
of the ventral valve is more regularly concave, and less distinctly constricted

* I have already referred with doubt a species from the Schoharie grit to S. crebristriata of Conrad ;
but since that description has been printed, I have had reason to question the correctness of my refe¬
rence. It is impossible to determine positively the species to which some of these descriptions refer.

CHONETES OF THE CORNIFEROUS LIMESTONE.

123

than in C. lineata. In the dorsal valve of the former, the muscular impression,
base of cardinal process, etc. are strongly defined, while they are not so in C.
lineata.

This species differs from C. pusilla in its much finer and more numerous strise ;
while it is smaller and more rotund than C. scitula of the Hamilton group.

The characters of the species are illustrated in figures 3 a-f, on Plate xx.

Geological formation and localities. In the Corniferous limestone at Oneida
falls, and abundant between Jamesville and Manlius in Onondaga county, and in
the north part of Seneca county. It is less abundant in the eastern localities of
the Corniferous limestone, and also in the extreme western localities ; but it has
been found on the Indian Reservation near Buffalo.

Chonetes yandellana.

PLATE XX.

Chonetes yandellana : Hall in Tenth Report on the State Cabinet, p. 118. 1857.

Compare C. lineata, ut sup. page 121.

Shell semioval, more or less gibbous : binge-line equalling the greatest
width of the shell.

Ventral valve regularly convex, abruptly depressed towards the cardinal
angles, which are nearly flat and very slightly deflected to the ventral
side.

Dorsal valve with the concavity a little less than the convexity of the
opposite valve.

Area of the ventral valve parallel with the longitudinal axis of the shell,
nearly twice as wide in the middle as near the extremities : foramen
comparatively large, with margins projecting, and the opening filled
by the cardinal process of the opposite valve. Dorsal area extremely
narrow, being barely a defined line.

Surface marked by fine somewhat equal striae, which increase by
bifurcation and intercalation till there are from sixty to seventy on
the margin of the shell. The cardinal margin of the ventral valve
bears three or four short oblique spines on each side of the centre.

The interior of the ventral valve shows strong dental lamellae, and the
muscular impressions are pretty well defined. The dorsal muscular

124

PALEONTOLOGY OF NEW-YORK.

impressions are well defined, and between them there is a strong mesial
ridge which is extended in a bidentate cardinal process. The lower half
of the surface is strongly papillose.

In general form, this species differs little from C. lineata (compare figures 3
a-f and 4 a-g , Plate 20). It is less gibbous, and not flattened on the middle of
the ventral valve ; while the interior presents more strongly defined markings.
In a collection of more than twenty specimens entirely separated from the lime¬
stone, which were sent me by the kindness of Dr. James Knapp, of Louisville,
Kentucky, the general form and moderate convexity are preserved, and it is
rarely that more than three spines are seen on one side of the centre ; but this
feature is subject to variation, and the spines are sometimes unequal on the two
sides of the same specimen.

All the differences indicated between this and the preceding species, I can
readily believe may be produced in the same type by the different conditions
of sea bottom, geographical distance, and other causes.

Geological formation and localities . In the hydraulic beds of the Corniferous
limestone, at the Falls of the Ohio, Louisville ( Kentucky), and Jeffersonville
(Indiana).

CSsonetes mucronata.

PLATES XX & XXL

Strophomena mucronata : Hall, Geol. Report 4th District New-York, p. 180, f. 3. 1843.

Chonetes laticosta : Hall in Tenth Report on State Cabinet, p. 119. 1857.

Shell small, semioval, moderately convex, nearly flat (often flattened in
the shale and gibbous in the limestone) : cardinal line equalling or a
little greater than the width of the shell below; the extremities
sometimes salient.

In the original specimens of this species from the Marcellus shale, the
ventral valve is slightly convex or nearly flat, one-fourth to one-third
wider than long : the hinge-extremities are rarely a little produced,
but the spines lying in the direction of the hinge-line often give it the
appearance of extreme extension.

The dorsal valve is very moderately concave or nearly flat.

The surface is marked by twenty to twenty-four or twenty-six nearly
simple subangular striae, which are not so wide as the spaces between
them. Sometimes one, two or three of these striae are bifurcated towards

CHONETES OF THE HAMILTON GROUP.

125

the margin. The radiating striae are crossed by extremely fine concentric
elevated striae.

The cardinal margin shows two and rarely three spines on each side
of the centre, which are abruptly bent outwards so as to lie nearly
parallel to the hinge-line, and the outer one extending much beyond the
cardinal extremity. The area is very narrow.

The figures 1 a-g, Plate xxi, are of this species from the Marcellus shale; the profile
view is from a specimen which is much more convex than usual.

When destitute of the cardinal spines, this species resembles the young of
Tropidoleptus carinatus ; but is readily distinguished when the cardinal spines are
present, and their' direction is a characteristic feature of the species.

The shell described as Chonetes laticosta occurs in the Corniferous limestone
and in the Hamilton group : the form is similar to C. mucronata of the Marcellus
shale. The ventral valve is often quite gibbous, regularly rounded in the middle,
suddenly depressed towards the cardinal angles, which are flattened and rarely
extended beyond the width of the shell. The dorsal valve is moderately concave,
sometimes very gently concave in the upper part of the valve and more abruptly
curved towards the front.

The surface is marked by from twelve to twenty usually simple rounded or
subangular striae, a few of which bifurcate towards the margin, or are increased
by intercalation of one, two or three others towards the margin, and have a
greater or less space between them. This gives considerable variety of aspect to
the surface ; and in all the individuals in the limestone, the striae are fewer and
stronger than in those from the Marcellus shale. The specimens from the Hamil¬
ton group more nearly resemble those from the limestone.

The cardinal margin is marked by two or three spines on each side of the
apex, with rarely indications of a fourth spine nearer the apex. These spines are
bent abruptly downwards, and directed outwards almost parallel to the hinge¬
line, and in some instances the outer one appears to be. a continuation of the
cardinal extremity (see figures 1 a-c, Plate 20; and figure 'I a-g, Plate 21).

The area of the ventral valve is narrow and linear, and the dental lamellae
are prominent. In the interior there is a strong median angular ridge or septum
reaching more than half the length of the valve. The dorsal area is scarcely more
than the thickness of the shell. The cardinal process is narrow and scarcely bifid
at the extremity, and is supported on each side at its base by an oblique ridge,
and continued in a median longitudinal ridge.

IS©

PALAEONTOLOGY OF NEW-YORK.

The interior of both valves is strongly pustulose, but the muscular markings
are not defined in the specimens examined.

In many of the smaller specimens from the Corniferous limestone, there are
but from twelve to sixteen strong rounded striae, and tfie ventral valve is very
gibbous (figure 2, Plate 20). In some specimens the cardinal extemities are con¬
siderably produced, but this is not a common feature. The species is sometimes
associated with C. lineata and C. lepida in the same fragment of stone. In the
Hamilton group, it has been found more* frequently in the harder semicalcareous
beds.

The great variation in convexity, number of striae and general aspect, leads
me to suspect that the following ( C . deflecta) may perhaps be only another phase
of the same species.

Geological formation and localities. In the Corniferous limestone of Manchester,
Ontario county; at Williamsville and Clarence-hollow; and on the Indian
Reservation to the southeast of Buffalo in Erie county. These localities furnish
the gibbous forms with strong striae designated C. laticosta. In the Marcellus
shale, the species is found at Avon in Livingston county, at Crooked creek near
Darien in Genesee county, and at Alden in Erie county. It occurs in the Hamil¬
ton group at Pratt’s falls, and in other localities in Onondaga and Madison
counties.

Chonetes deflecta.

PLATE XXL

Chonetes deflecta : Hall in Tenth Report on State Cabinet, p. 149. 1857.

Chonetes gibbosa : Id. Ibid. p. 145. 1847.

Shell semielliptical ; length and width as four to five or eight to nine,
but rarely proportionally wider.

Ventral valve extremely gibbous, regularly arched, the greatest eleva¬
tion being about the middle of the length ; abruptly depressed towards
the cardinal angles, which are flattened, with the extremities deflected
to the ventral side. The umbo is a little elevated above the cardinal
margin, and the minute apex (in perfect specimens) projects a little
over the area.

Dorsal valve deeply concave, but not equalling the convexity of the
ventral valve.

Area of the ventral valve narrow, with the exterior margin declining in
a gentle curve to the extremities : the triangular foramen is partially

CHONETES OF THE HAMILTON GROUP. 127

closed by a pseudo-deltidium, and the aperture occupied by the cardi¬
nal process of the opposite valve. Dorsal area more than half as wide
as the ventral, and marked in the middle by a wide triangular
callosity.

Sukface of the ventral valve marked by from twenty-six to thirty or
thirty-four subangular or sometimes rounded striae, which are often
irregularly increased by bifurcation or intercalation towards the
margin. In those with fewer striae, they are sharper, more abruptly
elevated, and only half as wide as the interspaces ; while in those
with a larger number, the -striae and interspaces are equal, but some¬
times the striae become fuller and more rounded, and the interspaces
proportionally less in width. The striae on the dorsal valve correspond
essentially with those of the ventral valve, and there is a considerable
space at the cardinal angles of each valve destitute of striae. Fine
closely arranged concentric striae are visible on the surface of well-
preserved specimens.

The interior of the dorsal valve shows a slender elongate cardinal
process which is scarcely bifid at the extremity, and has on each side, a
little below the apex, a minute lateral process for muscular attachment.
The dental sockets are limited on the upper side by a narrow ridge, .-and
on the lower side by a stronger oblique ridge which supports the base of
the cardinal process. The two pairs of occlusor muscular imprints are
distinctly marked; and outside of these, the vascular impressions are
pretty well defined. Beyond the vascular impressions the surface is
covered by elongate papillae, the marks of the striae being scarcely
distinct.

The interior of the ventral valve shows strong dental lamellae ; a some¬
what broad and angular median ridge terminates above the middle of the
valve. The occlusor muscular impressions have not been observed ; and
those of the divaricator muscles are wide and spreading, but not dis¬
tinctly defined. The cavity of the shell is abruptly rounded below, and
the shell abruptly deflected at the sides, leaving the cardino-lateral
margins nearly flat. The surface is finely pustulose in the middle, a little

128

PALEONTOLOGY OF NEW-YORK.

more coarsely pustulose along the deflected line, and nearly or quite
smooth towards the margins.

In the examination of a large number of specimens, the varieties are so
extreme that it seems to me difficult to indicate reliable characters for separa¬
ting this from C. mucronata or C. laticosta ; the most distinctive feature being the
finer strige.

In the specimens referred to C. deflecta there are usually a larger number of
strias, and in some specimens nearly twice as many as the prevailing number
in well marked specimens of C. mucronata. The area of the dorsal valve is like¬
wise much wider in the former than in the latter ; while the interior of the dorsal
valve shows stronger muscular imprints, and the surface is not definitely marked
by the strise.

The original of C. gibbosa is a large very convex specimen, with numerous
regular even rounded striae (fig. 8 b, c, Plate 21), and is more extended on the
hinge-line than the usual forms of C. deflecta (fig. 7 a , 6, c, Plate 21).

The illustrations on Plate xxi, figures 7 a- g and 8 a-c, present the usual varieties of
form observed in these shells.

Geological formation and localities . In the Hamilton group, on Canandaigua
lake ; and at Ludlowville and Kidder’s ferry on Cayuga lake ; at Moscow, York,
Covington and other places in Western New- York.

Chonetes pnsilla.

PLATE XXI.

Chonetes pusilla : Hall, Tenth Report on the State Cabinet, p. 149. 1857
Compare Chonetes deflecta and C. mucronata.

Shell small, semielliptical, the length and width being about as two to
three ; the hinge-line usually about equals the greatest width of the
shell below.

Ventral valve gibbous, regularly convex on the umbo and in the middle
and lower part of the shell, more abruptly depressed towards the
hinge-extremities, which are obtuse and rarely a little extended :
area narrow.

DorsAL valve with the concavity nearly corresponding to the convexity
of the opposite valve : area linear, scarcely exceeding the thickness
of the shell.

CHONBTES OF THE HAMILTON GROUP.

tm

Surface marked by somewhat regular even rounded striae, which are
little elevated, and become obsolete on the cardinal margins : from
twenty to thirty striae may be counted on the margin of the shell, and
in most of the individuals they are apparently simple throughout the
greater part of their extent. In some specimens the striae are conspicu¬
ously bifurcated, and also increased by interstitial additions. In well-
preserved surfaces, fine crowded concentric striae cross the radiating
• striae. The cardinal margin exhibits bases of two or three and rarely
four spines on each side, their extent or direction unknown.

Interior of the valves unknown.

This small Chonet.es was referred by Messrs. Norwood and Pratten to C.
armata, but it does not correspond with the figures and descriptions of De
Koninck.

In general aspect of form, and convexity of the ventral valve, this species
resembles C. deflecta; but all the specimens I possess are smaller, and the strise
more depressed. I am disposed to believe, however, that a larger collection of
specimens from western localities may prove that this form is but another phase
of the same species, induced by geographical and physical conditions, and
that in reality the eastern and western forms are but varieties of one and the
same type.

Geological formation and locality. In limestone of the age of the Hamilton
group, at the Bake-oven, Illinois.

Chonetes setigera.

PLATE XXI.

Strophomena setigera : Hall, Geol. Report 4th District New York, p.180. 1843.

Chonetes setigera Hall, Tenth Report on the State Cabinet, p. 150.

Shell semielliptical ; the cardinal line equalling the greatest width of
the shell, and rarely extending beyond.

Ventral valve moderately convex, rarely a little gibbous in the middle ;
umbo scarcely rising above the hinge-line ; the greatest elevation is
above the middle of the shell, and gradually sloping to the front and
baso-lateral margins ; while it is a little more abruptly depressed in
the upper lateral portions, and flattened on the cardinal angles. The
cardinal margin is furnished with three slender tubular spines on each
[Palaeontology IY.] ' 17

ISO

PALAEONTOLOGY OF NEW-YORK.

side -of the apex : these are bent a little outward as they leave the
shell, and then rise almost vertically, or with a slight curve from the
direction of the hinge-line.

The surface is marked by from 86 to 40 or 50 slender rounded or sub-
angular strise on the outer margin. In the upper and middle portions
of the shell, the striee are increased by bifurcation and intercalation.
The radial striae are crossed by fine concentric striae.

This species occurs in the same black . shale with C. mucronata , and may be
distinguished from it by the more numerous and more frequently bifurcating
striae, which are*likewise more angular. The direction of the cardinal spines, when
present, is always a characteristic feature.

At one time I compared this species with C. scitula; but it is a very marked
and distinct species, and not readily confounded with any other. In the con¬
centric striae it resembles C. logani , but the laminae are closer, less undulating,
and apparently do not affect the entire structure of the shell as in that species.

Numerous specimens of casts and impressions of the exterior shell in the Che¬
mung group appear to be of this species : these will be illustrated on Plate 22.

Geological formation and localities. In the thinly lamenated black Marcellus
shale, at the base of the Hamilton group near Caledonia, N. Y. ; and in the higher
beds of the same group, as well as in the Genesee slate, on the outlet of Crooked
lake ; but it has not proved an abundant species in any of the localities examined.

Chonetes scitula.

PLATE XXL

Chonetes scitula : Hall in Tenth Report on the State Cabinet, p. 147. 1857.

Compare Chonetes lineata, etc. this Vol. p. 121.

Shell transverse, semioval : hinge-line often not quite equalling the
greatest width of the shell ; cardinal angles rarely a little salient.
Ventral valve moderately gibbous in the middle, and regularly curving
to the front and basal margins; the gibbous portions narrowing
towards the hinge-line, and the umbo little elevated ; abruptly depres¬
sed towards the cardinal angles, which are nearly flat and sometimes
a little deflected at the extremities.

Dorsal valve with a concavity less than the convexity of the opposite
valve; the cardinal angles flat.

CHONETES OF THE HAMILTON GROUP.

1131

Area of the ventral valve narrow and distinctly wider in the middle,
the exterior margin gently curving : foramen partially closed by a
convex deltidium, and the aperture filled by the cardinal process of
the opposite valve. Dorsal area linear, half as wide as that of the
opposite valve.

Surface marked by fine subequal striae, which are often alternated in
“size towards the margin. Of these, from 15 to 20 may be counted near
the beak, while from bifurcation and intercalation there are from 50
to 60 on the margin, becoming obsolete towards the cardinal extre¬
mities. The striae are sometimes sharp and angular, and sometimes
rounded : fine concentric striae are visible on well-preserved specimens.
The cardinal margin of the ventral valve is furnished with two or
three spines on each side towards the extremities, and as many more
towards the beak, so that the bases of five can be readily counted, and
sometimes six ; while there is a minute point on each side of the apex,
which may be another spine; and this, if preserved, would give twelve
or fourteen spines on the cardinal line.

The interior of the dorsal valve is strongly pustulose, with a somewhat
broad depression along the centre, in the middle of which there is a
slender mesial ridge. The muscular impressions are not strongly defined,
but the limits of the vascular impressions are clearly seen. The cardinal
process is short, and the inner margin of the hinge-line is thickened and
rounded. The ventral valve shows a slender median ridge and two strong
dental lamallse. The muscular impressions are not strongly defined in
specimens seen.

This species is closely related on the one side to C. lineata and C. yandellana,
and on the other to C. lepida. With the latter it is frequently associated ; differing
from it, however, in its large size and the uniformly convex surface of the ventral
valve, while that one has a depression along the middle. The striae are more pro¬
minent than in C. lineata , and there is no flattening of the umbo and central por¬
tions of the ventral valve. It is nevertheless desirable to make more extensive
comparisons of the interior structure than I have been able to do with my
materials.

Geological formation and localities. In the Hamilton group, on the shores of
Cayuga and Seneca lakes ; at Ludlowville, on the shore of Canandaigua lake, at
Moscow, at Hamburgh on the shore of Lake Erie ; abundant near Oneonta, and
other localities.

133

PALAEONTOLOGY OF NEW-YORK.

Chonetes lepida.

PLATE XXI.

Chonetes lepida : Hall in Tenth Report on the State Cabinet, p. 148. 1857.

Shell small, scarcely transverse, semielliptical, subhemispherical :

hinge-line about equalling the width of the shell below.

Ventral valve more or less gibbous, with a longitudinal depression along
the centre in well-marked specimens ; curving abruptly to the front
and sides, with cardinal angles scarcely flattened.

Dorsal valve following the curvature 'of the opposite valve, with a lesser
concavity.

Area of the ventral valve narrow, distinctly wider in the middle, and
sloping with a gentle curve to the cardinal angles. The foramen is
small, partially closed by a pseudo-deltidium, and filled by the cardi¬
nal process of the opposite valve. The dorsal area is scarcely equal to
the thickness of the shell.

Surface marked by slender angular bifurcating striae, of which there
are ten or twelve near the umbo and twice as many on the margin,
and in some specimens a larger number. Two of the striae, on each side
of the centre near the beak of the ventral valve, are larger and more
prominent than the others : the space between them is depressed and
occupied by two or three smaller striae, which are given off from the
larger ones on each side. The larger striae are more prominent near
the beak than on any other part of the valve, and. give an almost
bicarinate aspect to the umbo, with a' distinct sinus which becomes
obsolete near the base of the shell.

The hinge-line usually shows two or three spines on each side of the
centre ; but in some individuals, the bases of five spines can be distinctly
seen on each side of the beak.

The interior of the dorsal valve shows a longitudinal depression, and
the course of the striae is well defined and strongly papillose.

The cardinal process has not been seen in its connexion with the
dorsal valve. Some casts of the ventral valve show a gibbous centre,

CHONETES OF THE HAMILTON GROUP.

133

which is constricted along its upper and lateral margins, -and is marked
by a longitudinal depression indicating the place of the median ridge
and muscular impressions, while they are depressed towards the lateral
and basal margins.

The original specimens designated as C. lepida are very small shells of almost
hemispheric form, and one of the characteristics is the mesial depression of the
ventral valve. The strise are rather strong, angular, and, from dividing below,
have the appearance of being fasciculate. More extensive collections have brought
together a large number of individuals; and while the characteristic features are
preserved in most of the specimens, there are others of the same size which seem
like the young of C. scitula ; but the well-marked specimens 'of this species have
a convexity which precludes them from acquiring by growth the foi’m and con¬
vexity of C. scitula in its characteristic phases.

Geological formation and localities . In the Marcellus shale near Darien in Erie
count}’', and in the Hamilton group at Ludlowville and Ogden’s ferry on the shore
of Cayuga lake : it is often abundant at the outlet of Crooked lake, and at
Hamburgh on the shore of Lake Erie, and occurs also in numerous other localities.

Chonetes coronata.

PLATE XXI.

Strophomena carinata (Scrive coronata ) : Conrad, Jour. Acad. Na. Sci.Phila., Vol. viii, p. 257, 1842.
Not Strophomena carinata , Conrad, Annual Report on the Palaeontology of New-York, p. 64. 1839.
Strophomena syrtalis : Conrad, Jour. Acad. Nat. Sci. Philadelphia, pa. 254, pi. 14, f. 1. 1842.

Compare Chonetes littoni, C. maclurea , C. tuomeyi and C. martini, Norwood and Pratten on the Genus
Chonetes, pp. 25, 28 and 29, pi. 2, f. 4, 8, 9, and 10. 1855. Journal Academy of Nat. Sciences,
Philadelphia, Vol. iii. 1854-5.

Shell transverse, somewhat broadly elliptical, the hinge-line being
sometimes shorter than the width of the shell and the cardinal angles
rounded : in others it is often equal to the greatest width of the shell,
and its form is semioval, with the lateral margins nearly rectangular
to the hinge-line, the width being about once and a half as great as
the length. The cardinal angles are sometimes produced in short acute
auriculate extensions.

Ventral valve varying from moderately convex in the younger shells,
to very gibbous in the older ones ; often a little flattened below the
umbo, and this plane space gradually widening to the front. Sometimes
there is a shallow undefined depression along the middle bf the valve.

134

PALAEONTOLOGY OP NEW-YOEK.

The outline of the valve presents a very regular convexity, while it is
abruptly depressed towards the cardinal extremities, which are flat¬
tened and a little deflected to the ventral side.

The dorsal valve is variably concave, sometimes following nearly the
contour of the ventral valve, but often very moderately concave or
nearly flat in the middle and upper part, and more suddenly deflected
towards the front and lateral margins, flattened at the cardinal extre¬
mities, and a little concave just below the hinge-line.

The surface is marked by numerous closely arranged slender subequal
striae, which are bifurcated or increased by intercalation, and are con¬
tinued on the cardinal extremities to within a little distance of the
hinge-line ; beyond which, the surface is marked by lamellose con¬
centric striae. In well-preserved surfaces, the radiating striae are crossed
by undulating concentric striae ; but in the greater number of speci¬
mens, these are not preserved, and the radiating striae have a fibrous
appearance.*

The cardinal margin of the ventral valve is furnished with five, six or
seven oblique tubular spines on each side of the apex, though usually
only three or four are visible. The ventral area is usually narrow, subli-
near, though often perceptibly triangular; the foramen is of moderate
size, partially closed by a convex pseudo-deltidium, and the lower part
occupied by the cardinal process. The dorsal area is linear, often more
than half as wide as the ventral area, with a triangular space in the
middle occupied by the cardinal process.

The interior of the ventral valve shows strong, very diverging dental
lamellae, a narrow median ridge with narrow oval occlusor muscular
impressions, while the divaricator muscular impressions are wide and
spreading; sometimes lobed or striate, and not very strongly limited
on the distal margins. Outside of these, are the broader vascular areas ;
beyond which, and sometimes within their limits, the surface is strongly
pustulose. The casts show the reverse of these features in a median
depression and widely diverging dental impressions ; the surface being

* Probably from a partial solution of the surface by iron pyrites.

CHONETES OF THE HAMILTON GROUP.’

135

deeply pitted outside of the vascular markings, and the margin strongly
striate. In other specimens, the marks of striae and the pitted or punc¬
tate surface extend over the larger part of the surface, the striae sometimes
continuing to the apex.

The interior of the dorsal valve shows deep dental sockets, with small
occlusor muscular imprints and wide vascular areas which are but faintly
marked ; while outside of these the surface is strongly pustulose. There
is a slender median ridge joining the base of the strong cardinal process :
this process is deeply grooved in the middle, both on the inner and the
exterior face, and the lateral process on each side is separated from
the central one by a similar groove on the exterior or cardinal face.
There is considerable difference in the length of this process in different
individuals, and it is sometimes constricted below the lateral process;
and in other specimens, the parts are equal. The surface is more or less
marked by the exterior striae, depending on the thickness of the shell ;
and not unfrequntly the concentric striae are beautifully preserved upon
the interior surface.

In the character of the surface striae, there are many minute diffe¬
rences among a large number of individuals. Sometimes an entire surface
will be seen to have the striae all bifurcating, or with few intercalated
ones ; while others have all or nearly all the increase by intercalation.

The figures 10 a-g illustrate the principal varieties of form of this species, as it occurs
in the calcareous shales of the Hamilton group in Central and Western New- York.
Figures 9, 11 and 12 are from the typical specimens of C. tuomeyi, C. martini and
C. madurea of Norwood and Pratten, given for comparison with those of New-
York.

The species described by Mr. Conrad as Strophomena syrtalis (loc. cit.) seems
to me not specifically distinct from C. coronata. It is known in the eastern -and
central parts of the State, occurring in some harder layers, usually much com- .
pressed or lying in great numbers together. The shell is generally partially exfo¬
liated, or presents the interior surface, giving the character described by Mr.
Conrad of “ minutely tuberculated ribs.” The extreme flattening of the shells,
packed together in great numbers, is due mainly to pressure ; and in the same
localities, a shell or cast found in softer shale outside of the mass, preserves a
moderate convexity. Under these different aspects, it is not surprising that this

as©

PALAEONTOLOGY OF NEW-YORK.

form should have been regarded as a distinct species. The casts show the impres¬
sion of a strong cardinal process and widely diverging dental lamellae, with
deeply pitted surfaces towards the exterior margin. Some of these forms are illu¬
strated on figures 13 d-d on Plate 21 ; and some of the larger individuals on
Plate 22.

In these specimens, the cardinal extremities are often extended beyond the
width of the shell below, as shown in figure 13 b, c; but the greater number
preserve a form similar to that given by Mr. Conrad.

I have before me at this time, through the kindness of Dr. Norwood, the origi¬
nal specimens from which C. martini, C. maclurea and C. tuomeyi were described,
as well as others corresponding to C. littoni; together with a considerable col¬
lection made by myself at the same locality from which they were obtained.
After careful comparisons of all those from the western locality,* I am unable to
recognize any specific difference among them ; and they correspond as closely
with C. coronata of New-York, presenting the same varieties of form, hinge-exten¬
sion, convexity, and flattening or depression of the middle of the ventral valve,
and the same variety in the bifurcation and intercalation of striae. I feel compel¬
led, therefore, to regard them all as varieties of the eastern type.

The C. konincki of Norwood and Pratten, I am disposed to believe only a
variety of the same form. A specimen from the original locality, near Jonesboro*
Illinois, labelled by Dr. Norwood, presents no reliable characters for separation
from some of the specimens from the Bake-ove.n.

The original of C. tuomeyi , figure 9 a, b, of Plate xxi, may be compared with
the young of C. coronata , figures 11 a, b, of the same plate; and C. maclurea , figure
11, maybe compared with C. coronata , figure 10 A, and others of the same;
while C. martini, figure 12, may be compared with C. coronata in figure 10 e, or
with figure 13 e. The C. littoni is intermediate in size between C. tuomeyi and C.
maclurea, and may be compared with C. coronata, figure 10 g.

The general aspect of all the western specimens, which are in limestone, is
that of having coarser and stronger striae than the C. coronata of the soft shales
of the Hamilton group in New-York. A careful measurement of the strise on diffe.
rent parts of the shell, in a number of specimens from the central and western
counties of this -State, shows that they range from 9 to 15 strise in the space of
two-tenths of an inch ; the majority being from twelve upwards in the centre,
and from nine upwards near the front and basal margin of the shell. As a rule,
the smaller specimens have the finer strioe.

Specimens of C. tuomeyi give from 9 to 12 strise in the space of two-tenths of
an inch : C. maclurea, which is larger than C. tuomeyi, gives 10 and 11 striae in

* The Bake-oven, Illinois, on the Mississippi river.

CHONETES OF THE HAMILTON GROUP.

137

the same space; and C. martini, 12 and 13 in the middle and 9 on the front.
Specimens which were recognized by Messrs. Norwood and Prat-ten as C. coronata,
from the same locality with the preceding species, give from 9 to 12 striae in the '
space of two-tenths of an inch ; in four specimens, the number 9 occurring four
times, 10 four times,, 11 twice and 12 once.

Chonetes syrtalis of Conrad gives from 8 to 15 striae in the same space, one
large individual (figured on Plate 22) giving 6 in front, 8 in the middle and 9 at the
side. The smallest specimen measured, gave 14, 15 and 16, while the larger.ones
gave fewer striae (8 - 12) in the same space. These measurements, if of any value
at all, serve to confirm the view that all these varieties are but a single species.

Geological formation and localities. This species in its typical forms, occurs in
the calcareous shales of the Hamilton group on the shores of Cayuga, Seneca and
Canandaigua lakes ; at Moscow and York, Livingston county ; at Darien and
Eighteen-mile creek, Erie county, and at other localities. In the form denominated
C. syrtalis , it occurs in the harder shales at Cazenovia and Hamilton in Madison
county, in Otsego county at several places, and at Pultonham and Summit in
Schoharie county. It occurs in large numbers, associated with other known fossils
of the Hamilton group, at the Bake-oven on the Mississippi river in Illinois.

CSiouetes logani, var. aurora.

Chonetes logani : Norwood and Pratten, Jour. Acad. Natural Sciences, Philadelphia, Vol. iii. 1855.

(Memoir, pa. 30, pi. ii, f. 12, a, b, c.)

The following description is given as above :

“ Shell small, transverse ; having its greatest breadth near the cardinal
“ border. Dorsal valve inflated; without a sinus ; covered with about
“ thirty rugose ribs. Ears small and scarcely separated from the dorsal
“ vault ; beak rather large and recurved. Ribs flattened and crossed
“ by fine lines : many of them are dichotomous. Area and ventral
“ valve unknown. Traces of tubes can be seen on the cardinal edge,
“ but the number cannot be ascertained. Dimensions : length, 6 milli-
“ metres; breadth, 9.”*

* The fossil is cited as occurring in the middle portion of the Mountain limestone series; hut I have
been informed that this, is an erroneous reference, and I have since received specimens, labelled by Dr.
Norwood, from the Oolitic beds of Burlington, Iowa. The species is probably limited in its upward range
to the lower calcareous beds of Burlington, and to the same horizon in the Mississippi valley. I have given
a very different: species under this name in the Iowa Geological Report, having accepted labelled specimens
as authentic,, without relying on the description and figure, cited.

[ Paleontology IV.] • 18

138

PALAEONTOLOGY OF NEW- YORK.

In the Tully limestone of N$w-York, we have a Chonetes which I am unable
to distinguish by any positive specific characters from the C. logani of Burlington
and other western localities..

The shell is moderately concavo-convex, semielleptical, the length
and breadth being about as 6 or 7 to 9 ; the cardinal angles scarcely
extended beyond the width of the shell. The ventral valve is moderately
convex, sometimes gibbous a little above the middle, with the umbo
prominent, regularly curving to the front and abruptly depressed towards
the cardinal angles. The dorsal valve is regularly and moderately con¬
cave in the middle and lower part, and flattened towards the cardinal
extremities.

The surface is marked by from twenty to forty low rounded costae,
many of which are dichotomous towards the margin. These costae some¬
times become obsolete towards the cardinal angles, but are often distinct
nearly to the hinge-line. The entire surface is marked by elevated undu¬
lating concentric striae which are sometimes equal to the space between
them; but, when partially exfoliated (and sometimes in other condi¬
tions), are narrower than the intermediate spaces.

The margin of the cardinal area preserve four (or six ?) somewhat
strong oblique spines ; the area is harrow. The interior of the dorsal
valve is papillose, with a short cardinal process. Casts of the ventral
Valve are very convex in the upper part, with a narrow slit marking the
place of the median septum, and, below this, preserving the marks of the
bifurcating striae, and sometimes the concentric striae are visible near
the margin.

In the shaly and calcareous rocks of Medina county, Ohio, there is a
similar form of Chonetes, undistinguishable by any external characters
from the specimens from the Tully limestone, except that the cardinal
angles are sometimes a little more produced than is usual in that rock. In
one specimen, equal in size to the largest from the Tully limestone, there
are about forty costae on the margin, and these are crossed by elevated
striae of precisely the same character. In numerous casts of the ventral
valve, in the same association, there are characters similar to those
noted in the Tully limestone specimens ; the central or upper convex

CHONETES OF THE HAMILTON GROUP.

IS®

portion being distinctly limited, while towards the margin the imprints
of striae are a little more definite than in the others. These slight diffe¬
rences between specimens occurring in limestone, and those in arenaceous
beds, are almost universal in other examples of identical species occur¬
ring in the different sediments.

In the yellow sandstone of Licking county, Ohio, there are similar
casts of Chonetes ; and I have a piece of sandstone from near Bedford,
Ohio, preserving several casts of the same species. These specimens from
the several localities show, along the area line, the casts of five or six
tubes on each side ; the three inner ones are parallel to the sides of the
foramen, while the others are less oblique. The three nearest the apex
are not known to be produced into spines, but probably form minute
pustules on the margin of the area.

In authentic specimens of C. logani from Burlington, there is great
variation in the convexity of the ventral valve ; the smaller and younger
being moderately convex, while the older ones are ventricose. The num¬
ber of costae varies from twenty to forty. There are two spines (and rarely
indications of a third) on each side of the beak. The area shows evi¬
dence of the oblique tubes observed in the casts.

The interior of the dorsal valve is papillose, with the striae more or
less strongly marked. The muscular and vascular impressions are often
pretty well preserved. The cardinal process is short, and supported on
each side, by an elevated ridge, with or without an obsolete median ridge,
giving the appearance presented by the cardinal process in some of the
species of Streptorhynchus.

We have, therefore, a species of Chonetes, so far as we can judge by all visible
features, ranging from the Tully limestone to the base of the Burlington lime*
stone ; or from the top of the Hamilton group to beds directly in conjunction with
the base of the Carboniferous limestones, as known in Iowa and the Mississippi
valley.

I have been indebted, in the first instance, to Ledyard Lincklaen, Esq., of
Cazenovia, for species of this fossil from DeRuyter; and subsequently it was
found by Mr. Whitfield at Tully.

Geological formations and localities. In the Tully limestone, at Tully, Onondaga
county, and at DeRuyter, Madison county, New-York; in Cuyahoga, Licking and
Medina counties, Ohio. The typical forms of the species occur at Burlington,
Iowa, and at Quincy, Illinois.

14©

PALEONTOLOGY OF NEW-YORK.

CHONETES OF THE CHEMUNG GROUP.

In certain localities of the Chemung group, within the State of New-
York, there are numerous specimens of Chonetes; but they occur in the
condition of casts of the interior, or of impressions of the exterior of the
shell. The strata containing them present all the phases of argillaceous and
arenaceous admixtures, sometimes a soft evenly laminated shale, and
sometimes a coarse ferruginous sandstone. The fossils therefore present
a great variety of aspect, and very different degrees of perfection and of
prominence in the characteristic markings.

This condition, moreover, renders it the more difficult to make satis¬
factory comparisons with specimens retaining the shell, and occurring
in other kinds of sediment. Notwithstanding these difficulties, I have,
after much labor, satisfied myself that the greater part of all the speci¬
mens found in the Chemung group may be referred to three of the forms
described from the Hamilton group : these are C. scitula , C. lepida and
C. setigera. The two former, which I have sometimes been disposed to
regard as perhaps identical species, maintain in the Chemung group the
same differences that they show in the Hamilton group. There are a few
obscure remains which do not appear referable to the preceding, having
more numerous striae than C. scitula and approaching in character C.
Illinois ensis.

In the higher strata of the Chemung group in Chautauqua county, and
in similar beds at Meadville, Pa., a very marked and distinct species of
Chonetes has been found. In its larger examples it equals in size and
has the general form of C. coronata of the Hamilton group, but is readily
distinguished by having a truncate apex and the surface studded with
slender spines.

In extending our. researches beyond the limits of the State of New-
York, we find in the shales and sandstones of Eastern Ohio (which in
part I regard as representing the Chemung group), one or two species
not known in New-York : these, however, are associated with the Cho-

CHONETES OP THE CHEMUNG GROUP.

14a

netes logani, which I have shown to occur in the Tully limestone of New-
York ; and although distinct species, are not in themselves evidence of
a higher geological position.

From the fact that the three species first indicated have this great
vertical range, we might infer that they would also show a wide geogra¬
phical range ; but this does not seem to hold true regarding them, in the
line of exploration which has been followed.

The Chonetes coronata which is known in Eastern, Central and Western
New- York in the Hamilton group, is also known in the same horizon in
Illinois and Iowa ; but it has not been recognized in the Chemung group
of New-York, Pennsylvania or Ohio, nor elsewhere in that horizon.

If we regard the Chonetes pusilla as a variety of C. laticosta or C. defteda,
that species has a wide geographical range, since it occurs on the Missis¬
sippi river in Illinois; but it has not been found in New-York or else¬
where above the horizon of the Hamilton group. On the other hand, the
C. logani , which begins its existence in the Tully limestone or the upper
limit of the Hamilton group, ranges on the west to the base of the Car¬
boniferous limestone, though unknown in the Chemung group of New-
York.

I may, in the subsequent pages, call attention to other similar examples, in
reference to geological and geographical distribution of species.

Chonetes scitula.

PLATE XXII.

[ Reference page 130 of this volume.]

This species, in the shaly beds, preserves impressions of the exterior
and casts of the interior, showing the characteristic surface markings, the
spines of the area margin, etc.

In the coarser sandstones it is somewhat larger and coarser in its mark¬
ings; and sometimes the striae are nearly equal, presenting a character
of surface observed in the Hamilton group.

The casts of the ventral valve show the filling of the minute tubes
which correspond to those seen in the shell of the specimens from the
Hamilton group.

tm

PALEONTOLOGY OF NEW-YORK.

This species occurs in the lower beds of the Chemung group near Trumans-
burgh, and at the Inclined Plane near Ithaca ; at Painted-post and along the line
of the Blossburgh railroad to Pennsylvania ; at Grass-valley and Connewango in
Cattaraugus county; at several localities in Chautaqua county, New-York,-and
at Meadville, Pennsylvania.

Chonetes lepida.

PLATE XXII.

[Chonetes lepida, p. 132 of this volume.]

This species occurs in the Chemung group, mostly in the condition of
casts ; and is distinguished from the casts of C. scitula by its smaller size
and mesial depression.

In one or two localities it has been found with the shell preserved,
and will probably be found in this condition in many places in the
freshly quarried stone, beyond the influence of the weather.

The principal localities where it has been observed in this group are
Great-valley and Connewango in Cattaraugus county, and Forestville in
Chautauqua county. Rarely it has been observed in the specimens from
Meadville, Pennsylvania.

Chonetes setigera.

PLATE XXII.f

[Chonetes setigera, p. 129 of this volume.]

This species, which occurs in the Marcellus and Genesee slates, has
not been found among the collections from the Chemung group in New-
York ; but it occurs associated with C. scitula, and other fossils of the
Chemung group, at Meadville, Pennsylvania.

The specimens consist of casts of the ventral valve and impressions of
the exterior of both valves. When the cardinal spines are present, the
species is readily identified ; but it may be distinguished from C. scitula
by its greater proportional length, and by the rounded coarser striae, and
usually greater convexity of the ventral valve towards the apex.

CHONETES OF THE CHEMUNG GROUP.

14®8

Chonetes muricatas (n. s.).

PLATE XXII.

Shell of medium size, semielliptical, moderately or sometimes deeply
concavo-convex : hinge-line usually less than the width of the shell,
with the cardinal angles rounded.

Ventral valve moderately and regularly convex, sometimes gibbous;
sides often nearly straight or a little inclined towards the hinge-line ;
the front broadly rounded, somewhat flattened towards the cardinal
extremities which are indistinctly auriculated, frequently obliquely
truncated on the umbo, with the apex slightly raised above the hinge¬
line. Area narrow, sometimes attaining a greater width, and extend¬
ing to the cardinal extremities.

Dorsal valve moderately or deeply concave and following essentially
the contour of the opposite valve, being a little shorter on the hinge¬
line, which is marked by a very narrow linear area ; apex obliquely
truncated, corresponding with the ventral valve.

The surface of the ventral valve is concentrically striated (probably
only by the lines of growth) and with wrinkles along the cardinal mar¬
gins, which become more or less obsolete on the body of the shell. The
cardinal margin of the ventral valve is usually marked by a row of about
four to six spines on each side of the apex, while the folds on the ears
are similarly ornamented. On the body of the shell, the spines seem to
have been more sparsely distributed ; but towards the basal and baso-
lateral margins they are closely disposed in concentric rows. The spines
on the body of the shell are slender, and apparently of moderate length.

I have not been able to discover spines upon the dorsal valve, though
concentric wrinkles mark the cardinal angles in the same manner as on
the ventral valve, and the exterior is indented by fossets which cause
pustules on the inner surface of the shell.

The specimens consist of casts or impressions of the interior and
exterior ; and the characters are drawn from these, and from wax im¬
pressions taken in the natural mould.

144

PALAEONTOLOGY OF NEW-YORK.

The cast of the ventral valve shows a sub-linear or low angular area,
with a narrow foramen which has been covered by a pseudo-deltidium.
The apex is bilobed, and there are cavities made by the teeth; and
proceeding a little obliquely from these are gradually decreasing grooves
diverging a little from the hinge-line, indicating an oblique ridge in the
shell. From the outer extremity of these marks, a curving line parallel
to the lateral margins of the shell indicates the limits of vascular impres¬
sions. The occlusor muscular imprints are two narrow elongate subtri-
angular or semioval scars, and directly below are some minute vascular
markings which separate the wide flabelliform divaricator muscular im¬
pressions : these are faintly striate, and, when well preserved, are dis¬
tinctly lobed, though usually not well defined on the exterior limits. The
entire surface is striato-punctate.

The interior of a dorsal valve retaining the shell is papillose, becoming
punctate on exfoliation, and showing pustules on the anterior margin.
The impression of the exterior sometimes shows a truncate apex and
the imprint of a cardinal process which is bilobed, and each division
again divided (as shown in the figure).

A cast made from a mould of the interior of the dorsal valve (fig. 00)
shows a slender median septum, which terminates in the cardinal pro¬
cess (the two principal lobes only being shown in that view). From near
the base of the process on each side proceed the reniform vascular
markings. The occlusor muscular imprints are minute elevations on each
side of the median septum. The entire inner surface is striato-punctate.

The larger specimens are usually moderately convex ; but some smaller
ones are rather gibbous, possessing otherwise the characters of the larger
individuals.

This species has the general form and proportions of Chonetesfischeri; but is
distinguished by the broadly truncate apex, the wrinkles on the ventral and dor¬
sal valves, and more especially by the presence of spines on the ears and upon
the body of the shell : it has likewise a more distinct area on the ventral valve.
The C. fischeri has the apex of the ventral valve often somewhat unequally de¬
pressed, and sometimes apparently a little irregularly produced and sub truncate;

CHONETES OF THE CHEMUNG GROUP.

145

while its surface markings, when entire, consist of fine closely arranged striae,
and in a partially exfoliated condition it is marked by two sets of excentric
lines crossing each other, which give a very peculiar aspect ; while the absence
of spines upon the surface readily distinguishes it.

I have seen that species' only from the beds below the Burlington limestone, at
Burlington ; and we do not know what modifications may take place in its cha¬
racters in distant localities.

The Chonetes muricata, in its truncate apex and spiniferous surface, has the
external aspect of Strophalosia ; but a careful examination shows all the dis¬
tinctive features of Chonetes. A single specimen, partially preserving the shell
on the hinge-line, shows an area on the ventral valve of nearly a line in width in
the centre, the dorsal area being about one-third as wide.

Geological formation and localities. In the arenaceous and semicalcareous beds
of the Chemung group, at Ellington in Chautauqua county, New- York ; and at
Meadville, Pennsylvania.

In addition to the species which are clearly recognised in the Chemung group,
there are casts of the interior and impressions of the exterior of one or two
others which cannot be satisfactorily referred to any known forms, and which
are not in a condition to be described as distinct species.

In the eastern part of Ohio there is a species of Chonetes occurring in beds
from sixty to one hundred feet below the Carboniferous conglomerate, and in a
position somewhat higher than the beds from which the principal part of the
fossils in New-York are obtained, which bears a close resemblance if not identity
with the C. illinoisensis. It occurs in association with C. logani, and is distinguished
by its larger and more gibbous form and finely striated surface, having from 80
to 120 fine subequal striae upon the surface of the ventral valve. When exfoliated,
the surface is finely and regularly punctate between the striae. The cardinal
margin bears three or four slender diverging spines on each side of the beak (not
“ five or six oblique spines on each side of the beak,”) as in C. illinoisensis.

Paleontology IY.

19

PALAEONTOLOGY OF NEW-YORK.

im

REMARKS ON THE GENERA PRODUCTUS AND STROPHALOSIA.

Among the genera of the Family Production, there are recognized at
the present time the following : Chonetes, Productus, Strophalosia and
Aulosteges ; the two latter being considered by Mr. Davidson as sub¬
genera of Productus.

The Genus Chonetes has already been noticed in the preceding pages ;
and from its marked characters, there is usually little danger of con¬
founding it with any other of the Productidse. The Genus Productus, in
its typical and varied forms, is characteristic of the Carboniferous period :
a few species are known in the Permian, while other similar forms in the
Devonian, which were formerly considered as Ppoductus, have lately
been referred to the genus or subgenus Strophalosia of Prof. King.

Productus, which is the oldest established genus, includes species
described as semicircular or semioval concavo-convex shells, with spini-
feroiis exterior surface, straight hinge-line, without an area on either
valve, and without teeth or sockets. The interior characters, though with
a general resemblance to Strophodonta, have in addition certain other
points by which they are distinguished. Notwithstanding that the spe¬
cies of Productus have usually the shell more or less closely studded
with spines, and generally a row of spines just below the hinge-margin
of the ventral valve, there are some species referred to this genus which
are nearly destitute of spines, and others upon which no spines have
been detected except on the ears or near the cardinal margin. Species
having this exterior character are usually more extremely gibbous or
ventricose in the ventral valve than any species of Leptnna, Stropho¬
donta or Chonetes, and the dorsal valve is more deeply concave.

Strophalosia is described as differing externally from Productus in
sometimes having a truncate apex, and by the presence of an area of
greater or less extent on each valve, with a foramen which is more or
less closed by a deltidium. In the interior, it is said to be characterized
by teeth in the ventral valve and teeth-sockets in the opposite valve ;

GENERA PRODUCTUS AND STROPHALOSIA.

147

while the disposition of the reniform vascular impressions of the dorsal
valve is a distinctive feature.

In reference to the Genus Productus, Mr. Davidson remarks as fol¬
lows :

“ All well authenticated species of Productus, hitherto examined, have shown
“themselves to be edentulous; but whether this character was general and
“ without exception, may remain a question for further consideration : anyhow,
“ the dorsal valve must have turned on its hinge-line with as much precision as
“ in Chonetes, which possessed regularly articulating teeth. It has been often
“ asserted and believed that Productus might be distinguished from its subgenera
“ by the total absence of an area ; and although this is the prevalent character
<£ of the genus, still in certain species, such as P. sinuatus, a perfectly developed
“ area is generally present in the ventral valve. There exists also an occasional
tl tendency to the formation of hinge-area in several species ; as may be seen, for
“ example, in the remarkable example of P. semireticulatus , of which a repre-
“ sentation is given in Plate xliii, fig. 5.”*

These observations of Mr. Davidson are of later date than his “ Intro¬
duction to the Natural History of the Brachiopoda.”

One of the important features of distinction between Productus and
Strophalosia has been stated to bo the different disposition of the reni¬
form vascular impressions in the dorsal valve. The accompanying figures
represent this character in two species of the latter genus, as given by
Mr. Davidson in his Introduction.

In examining the species occurring in the higher formations of the New
York rocks, which I had supposed might be referred to the Genus Stropha-

Monograph of British Carboniferous Brachiopoda, p. 136. 1861.

148

PALEONTOLOGY OF NEW-YORK.

losia, I find evidence of a narrow area with small teeth and sockets in
the greater number of the species; although these features do not usually
appear, except upon the most critical examination. The disposition of
the reniform vascular impression, however, does not correspond with
that of Strophalosia ; but in all the species where this feature has been
observed, it is similar to that shown in figures 5 and 6.

5 6

Fia. 5. Proddctella onusta. Fia. 6. Productella striatula.

B C. Tooth-socket and socket plate. ( Enlarged to two diameters) .

J. Cardinal process. O. Anterior and posterior occlusors. V. The reniform vascular'impressions.

V*. This letter refers to the faint diverging impression proceeding from the extremity of the mesial sep¬
tum of P. onusta. A similar marking has been observed in another species, but no connexion with the
reniform vascular impressions has been observed.

Neither of these species are known to have the apex of the ventral
valve truncated. In another species, with extremely gibbous and arcuate
ventral valve and deeply concave dorsal valve, the disposition of the
reniform impression is precisely like those illustrated ; and in none of
the species under investigation have we seen the least evidence of reni¬
form impressions like those of figures 3 and 4, which are illustrations of
Permian species of Strophalosia.

It is clear, therefore, that this character could not be relied on for
distinguishing the genus, if we were to include in it our Devonian spe¬
cies ; for in the three species referred to, the imprint has the same direc¬
tion and termination as shown in Aulosteges, except perhaps that the
muscular scars may be a little nearer the hinge-line ; and in this respect
it is not very dissimilar to some species of Productus, as shown in P.
costatus (figure 7).#

* Productus longispinus and P. pustulosus have a similar form of the reniform impression. See David¬
son^ Monograph of British Carboniferous Brachiopoda.

GENERA PRODUCTUS AND STROPHALOSIA.

tm

I have moreover ascertained that the American forms of P. costatus
have often a well defined area on the ventral valve, and a narrow area
on the dorsal valve, extending nearly the entire length of the hinge-line ;
and in some specimens, this is as distinct as the area of Strophodonta or
of Chonetes. There is of course a foramen, which is open in the examples
observed ; though in Mr. Davidson’s figure of P. semireticulatus, cited
above, the foramen is closed by a deltidium. The specimens of ventral
valves of Productus, which I have been able to examine, have no true
teeth or extensions from the margins of the foramen ; but sometimes a
callosity extends obliquely backward and unites with the interior of the
shell, being in fact as much a representation of dental lamellae as we
have in some species of Strophodonta.* The accompanying figure 8 illus¬
trates the hinge-area of P. costatus ; and figure 7 is of the interior of a
dorsal valve, showing the muscular and vascular impressions.

7 - 8

Fig. 7. Productus costatus. Fig. 8. Productus costatus.

Interior of the dorsal valve to stow the reniform Dorsal view of a specimen showing

vascular impressions, cardinal process and the the hinge-area,

oblique callosity C.

Thus we see that the species referred to Productus may have all the
characters of Strophalosia except the hinge-teeth and sockets, and the
disposition of the reniform impressions ; while the New-York species,
possessing teeth and sockets, have not the disposition of the reniform
vascular impressions which are given by European authors as characte¬
ristic of Strophalosia.

In glancing at the species of Productidse illustrated on Plates 28, 24,

* See Strophodonta demissa, S. reversa, S. nacrea and others.

15®

PALEONTOLOGY OF NEW- YORK.

25 and 26 of this volume, one cannot fail to be impressed with the pre¬
vailing greater width on the hinge-line, and consequent modification of
form in the American Devonian species, as compared with the Stropha-
losia of the Permian system in Europe. But while the greater part, and
perhaps all of these, have a narrow cardinal area and small hinge-teeth
and sockets, I conceive that their exterior character and expression are
much more like true Productus than are the Permian species of Stropha-
losia ; and one of the most marked features consists in the conspicuous
ears with rows of spines, as in Carboniferous Producti ; while their
anterior extension and highly arcuate forms assimilate them much more
with Productus than with Strophalosia.

In the Upper Helderberg group, the Productidse of this character
make their first appearance in the American geological series, and con¬
tinue with increasing numbers through the successive formations to the
Carboniferous limestone. There are a few individuals of two species in the
Corniferous limestone, and more in numbers of individuals and of other
species in the Hamilton group ; but it is difficult to find specimens in a
condition favorable for satisfactory investigation. A few specimens have
been obtained entirely separated from the rock ; but nearly all are
imbedded, with the ventral valve adhering to the matrix so that the
hinge and interior structure can rarely be seen ; while the dorsal valves
almost uniformly adhere by their exterior surface, leaving only their
interior for examination.

In the Chemung group, the specimens occur mostly as casts of the
interior and impressions of the exterior, and these are frequently much
distorted. In some of the softer compact shales of this group, we find the
shell partially preserved, but still in such condition that the entire cha¬
racters cannot be discovered ; and it is only in some fresh exposures of the
semicalcareous bands that we are able rarely to obtain specimens of more
natural appearance and better preserved surface.

Under circumstances of so much difficulty, it is with much hesitation

GENERA PRODUCTUS AND STROPHALOSIA.

151

that I approach the final disposition of the species of this character in
our formations.*

It would appear that the Genus Strophalosia has been founded upon
characters derived entirely from Permian species, in which the interior
structure has been well preserved. Of the few European Devonian species
of this genus which are cited, I have seen no illustrations of the interior ;
and these have probably been referred to the genus from the generally
similar form, the presence of a narrow area, and minute teeth and sockets,
which are characters found in identical or similar forms in the American
strata. It is probable, therefore, that had the interior of these species
been observed, they would not have been placed among the Permian
STROPHALOSiiE, but rather among the Producti, to which they seem more
nearly allied.f

It appears to me that we have in the Devonian period the incipient
manifestation of the productidian type, which became modified in the
later Carboniferous period, where, with conditions favorable to its exces¬
sive development, it has assumed extravagant forms and proportions,
but here and there indicating the characters of its prototype in the
presence of an area and foramen, among species of a genus which is cha¬
racterized by the absence of these features. In the still later Permian
period, with changed conditions, we have an approximate return to the
earliest forms of the species, or to the prototype ; and in reality the
foundation of the genus lies in the Devonian forms which have been
referred to Strophalosia.

It would appear that the presence, rather than the absence of charac¬
ters, should be the foundation of generic description and determination ;

* Those who have the best right to criticise the work, from having themselves labored in a similar field,
will appreciate the difiiculties to be encountered ; and they will only need to be assured of my earnest
intention to dispose of the species without prejudice or partiality to previously expressed opinions. With
larger collections before me than I had when originally describing the species under the preceding genera,
I have seen cause to modify in some instances the views formerly maintained, and I believe I have shown
no leniency towards species proposed by myself on insutficient materials ; but I am quite unable, at the pre¬
sent time, to reduce the species of this type from these formations, to the limits indicated by European
authors who have examined American collections.

t Prof. De Koninck, iii his “ Recherches des Animaux fossiles,” has not recognized the Genus Stro-
phalosia; and the Devonian forms similar to those of our rocks are by him placed under Productus.

153

PALAEONTOLOGY OF NEW-YORK.

and in that view Productus possesses fewer characters, and in the absence
of hinge-area, teeth and sockets, is less complete than the forms pos¬
sessing these appendages. Nevertheless the great development of forms
and number of species constituting the Genus Productus during the
Carboniferous period, has acquired for it the importance and distinction
which it must retain ; and any subdivisions proposed must have reference
to the characters of this genus as established.

On a critical examination of the genera of the Family Productidse,
we shall find that Chonetes is distinguished by well-marked and impor¬
tant characters : having an area on each valve and a row of spines upon
the margin of the area of the ventral valve, which is one of the distin¬
guishing external features, though it has been ascertained that spines
sometimes occur upon the body of the shell.

The separation of the genera or subgenera Strophalosia and Auloste-
ges from Productus is based upon less important differences. The former
has an area on each valve, a foramen in the ventral valve covered by a
deltidium, with teeth and sockets, while the reniform vascular imprints
have a different direction and termination. The latter has a wide area
on the ventral valve, a foramen closed by a pseudo-deltidium, with no
teeth and teeth-sockets, and with the reniform vascular impressions
extended far towards the anterior margin of the valve, and sometimes
abruptly recurved* The typical species of Aulosteges is very similar to
Strophalosia in external form. Both are from the Permian system, and
the differences between them consist in the presence or absence of teeth
and sockets, and the different direction of the reniform impressions.

While the typical and fully developed forms of Strophalosia in the
Permian System have a large area on the ventral valve, with a narrow
area on the dorsal valve ; all the New- York species have a very narrow
area on each valve (often so narrow as to be no greater than the thick¬
ness of the shell), with the other general differences pointed out. These fea¬
tures alone might not be sufficient to. indicate a distinct group ; and a

* The disposition of the reniform impressions is not essentially different ftom that of some species of
Psoductus ; and the presence of an area and covered foramen, and the absence of teeth and teeth-sockets
are the distinguishing features.

GENERA PRODUCTUS AND STROPHALOSI i.

153

little extension of the characters of Productus or of Strophalosia might
include them; but while Strophalosia and Aulosteges remain dis¬
tinguished by such small differences, these forms also, I conceive,
should be separated from the former, both on account of the ex¬
ternal differences and from the direction of the reniform vascular
impression, which has been regarded as an important feature in the
Productidse. These differences I consider as scarcely less important
than those upon which the other subgenera have been separated; and
from their external form and internal structure so nearly resembling
Productus, I would propose for the Devonian species having narrow
hinge-areas and small toeth and sockets, with reniform vascular impres¬
sions of the form of those illustrated, the name Productella.

Sul»«*enii§ Productella (n. s.g.)

Shells having the general form of Productus, but uniformly with a nar¬
row area on each valve, a foramen or callosity on the ventral area,*
small teeth, and more or less distinct teeth-sockets.

The reniform vascular impression, rising from between the anterior
and posterior occlusor muscular impressions, curves gently outwards,
and following a curvature somewhat parallel with the margin of the
shell to below the middle of its length, is abruptly recurved, and the
extremity turned a little backwards teminates about half way between
the margin and the anterior extremity of the mesial septum.

The cardinal process, seen from the inner side, is bilobed, and from
the exterior side each of these divisions is usually bilobed.

These shells differ from Strophalosia in the extremely narrow linear cardinal
area, greater extension of the hinge-line, more extreme arcuation or ventricosity
of the ventral valve in many or most of the species, and especially .in the direc¬
tion and termination of the reniform vascular impressions, which resemble those
of Aulosteges and of some species of Productus. It differs from Productus in the
constant presence of an area, hinge-teeth and sockets.

* In the specimens affording the most satisfactory evidence of area, etc., the foramen is ojen; but in
some specimens the impression only remains, and there is the appearance of a narrow indentation below
the beak, so that it is impossible to determine whether the foramen has been open, or closed by a
deltidium.

[ Paleontology IV.]

20

154

PALEONTOLOGY OP NEW-YORK.

PRODUCTELLE OF THE CORNIFEROUS LIMESTONE AND HAMILTON
GROUP.

Productella sulfaciileata.

PLATE XXIII.

Produdus subaculeatus : Murchison, 1840, Bull, dela Soc. Geol. de France, Yol. xi, pa. 255, pi. 2, f. 9 a,b,c.

Leptcena fragaria : J. de C. Sowerby, 1840, Transac. of the Geol. Society of London, 2d series, Yol. v,

pa. 704, pi. 56, f. 5 and 6.

- obionga? : Idem, Ibid, pi. 53, f. 29; not Pander.

Produda - : Phillips', 1841, Pal. Foss, of Cornwall, pa. 59, pi. 25, f. 100.

Produdus spinulosus (partim) : De Koninck. 1843, Desc. des Anim. foss. du terr. carb. de Belgium.

p. 1?3 (fig. exclusis) ; not Sowerby.

- subaculeatus (partim) : De Yerneuil, 1843, Russia and the Ural Mountains, Yol. ii, pa. 282, pi. 16,'

f. 9, a, b, c.

- (partim) : De Keyserling, 1846, Reise in das Petschora-land, pa. 203, pi. 199 (fig. ex.).

Strophalosia subaculeata : King, 1846, Ann. and Mag. of Nat. History, Yol. xviii, p. 28.

Produdus subaculeatus : De Koninck, 1846, Mem. de la Soc. royale des Sci. de Liege, Yol. iv, pa. 249,

pi. 16, f. 4 a-d.

“ “ De Koninck, Recherces sur les Anim. fossiles, 1847, pa. 142, pi. 16, f. 4 a, b, c, d.

Ventral valve gibbous; length and breadth about as seven to eight :
hinge-extremities angulated, and the margins being contracted a little
below form small ears, while below this contraction the sides are
regularly curved and the front is broadly rounded. The umbo is con¬
siderably elevated above the hinge-line, and the apex incurved.

Surface marked by closely arranged concentric strife, and studded with
slender rounded spines. On the upper part of the shell, and on the
ears, these spines are round at the base, and rise directly from the sur¬
face. On the middle and lower part of the valve, there is a slight ele¬
vation of the surface a little above the base of the spine, but not a de¬
fined ridge. The number of spines on the individual figured has been
sixty or more.

The following is the description of this species^ given by De Koninck :
“ Shell small, semiglobose, rounded. Dorsal valve not sinuate, very

“ gibbous, rather regularly arched. The surface is ornamented with a

“ great number of very faint strife of growth, and scattered over with

“ tubes of which there usually remains only the circular or slightly elon-

PRODUOTELLJE OF THE CORNIFEROUS LIMESTONE.

133

“ gated bases. The distribution of these tubes has no regularity : they
“ are cylindrical, rather short, and appear to have followed a direction
“ parallel to the curvature of the' va<lve : they are more closely arranged
“ towards the little ears than upon other parts of the surface, and, upon
“ each side of the beak, form a range af four or five tubes directed back-
“ wards, extending a little distance beyond the cardinal line. The ears
“ are very small and fragile, and are terminated exteriorly in an obtuse
“ angle. The cardinal line is shorter than the transverse diameter. On
“ careful examination, we observe an extremely narrow area, divided in
“ the middle by a triangular opening which is obliterated and hidden by
“ the beak when the shell is placed upon its dorsal valve. Nevertheless
“ the beak is very short and little prominent, although gibbous at a
“ little distance from its extremity, and neatly separated from the
“ ears by a sudden curve. The ventral valve is entirely embraced
“ by the dorsal valve, in which it is deeply inserted, and which it fol-
“ lows in all its contour : it is garnished with some concentric wrinkles,
“ somewhat strongly defined upon the ears and upon the sides. Little
“ rounded fossets are irregularly distributed, and correspond to the ori-
“ gin of the tubes of the other valve.”

“ Dimensions. Average length, 16 millimetres. Proportions of length,
breadth, height and thickness=100 : 113 : 65 : 20. The total number of
tubes varies from 25 to 50.”

Prof. DeKoninck remarks that this species is known in America by the name
of Strophomena lachrymosa. The Strophomena lachrymosa of Conrad was described
from the Chemung-narrows in New- York, and is a larger shell, with different cha¬
racters from any one known to me in the Corniferous limestone of New- York or of
the West, and does not at all resemble the figures of P. subaculeatus given by this
author.

Geological formations and localities . This species has been cited by M. DeVer-
neuil as occurring at Charleston landing and Lewis creek in Indiana, and as tra¬
versing the Hamilton, Portage and Chemung groups. The specimen figured on
Plate xxiii is from the Corniferous limestone at Jeffersonville, Indiana ; and I pre¬
sume is identical with specimens from Charleston landing.

I am unable to identify it with any species in the Hamilton and Chemung
groups of New-York, though resembling some of those which I have placed under
P. shumardiana. A larger collection of specimens may possibly show a passage
from the one to the other.

156

PALAEONTOLOGY OP NEW- YORK.

Productella navicella.

Productus navicella : Hall in Tenth Report on the State Cabinet, p. 172. 1857.

Shell small, subelliptical ; length greater than width : hinge-line a little
less than the greatest width of the shell.

Ventral valve extremely gibbous in the middle, arcuate : beak very
much incurved and projecting a little below the hinge-line. The umbo
is elevated above the hinge-line about equal to one-third the length of
the shell : sides sometimes nearly parallel for one-half their length
below the hinge-line, sometimes gradually curving outwards. Dorsal
valve extremely concave.

Surface marked by fine undulating concentric striae, which are some¬
times interrupted by irregular lamellae. On the umbo and the cardinal
extremities there are numerous minute cylindrical spines which rise
almost directly from the surface, or with a scarcely perceptible ele¬
vation of the surface just above them. Below the umbo, the ridges
above the spine-bases become more elongate and conspicuous, while
on the middle and sides of the valve, and towards its lower margin,
these become elongate costae ; and from them rise rounded spines, some¬
times interrupting the continuity of the costae, which at other times
continue below the spine with some abatement of their strength.
There are rarely spines rising from between the costae, and sometimes
the latter continue for some distance without spines.

The specimens referred to this species are distinguished by the narrow elon¬
gate form and extreme arcuation. No area, teeth or teeth-sockets have been
observed, as the specimens are not in a condition to admit an examination of
these parts.

The typical specimen is from the Hamilton group, and I have referred to the
same species several specimens of similar form and proportions from the Cornife-
rous limestone, which are more distinctly marked by continuous radiating costse,
some of which are bifurcated on the sides. All the individuals now referred to
this species are small shells ; and though we might suppose the conditions in the
Corniferous limestone to have been favorable to their development, yet no speci¬
mens have been found larger than those figured on Plate xxm.

PRODUCTELLiE OF. THE CORNIFEROHS LIMESTONE.

137

One or two specimens of larger dimensions in the Hamilton group have a simi¬
lar surface-marking, but a different form.

Geological formations and localities. In the Corniferous limestone in Schoharie
county, and in the Hamilton group at Moscow and Pavilion, Newport.

Procluctella shumardiana.

PLATE XXIII.

Productus shumardianus : Hall, Geol. Report of Iowa, Vol.i, Part ii, pa. 499, pl.iii, f.9, and pi. vii, f.l.
Productus spinulicostus [in part] ; Hall, Tenth Report on the State Cabinet, p. 173, 1857.

Productus concentricus : Hall, Tenth Report on the State Cabinet, p. 180.* Geological Report of Iowa,

Vol. i, part ii, p. 517.

Productus pyxidatus [partim vel totum] : Hall, Geological Report of Iowa, Yol. i, part ii, p. 498.

Shell concavo-convex, subhemispherical, wider than long : hinge-line
nearly or quite equalling and sometimes greater than the width of the
shell below.

Ventral valve very convex, gibbous in the middle and on the umbo,
which is abruptly narrowed towards the beak, and the apex incurved
over the hinge-line ; the sides abruptly depressed towards the cardinal
extremities, which are flattened and more or less auriculate. In one
specimen observed, the apex is minutely truncate, and there is a
barely perceptible line at the junction of the two valves, which indi¬
cates an area.

Dorsal valve concave, often corresponding essentially with the ventral
va^ve ; but sometimes nearly flat in the upper and central portions, and
abruptly deflected towards the margin.

The surface of the ventral valve is marked by intermittent radiating
ridges, gradually rising from the surface and terminating below in
elongate spines ; while upon the upper part of the shell, about the
umbo, there are scarcely perceptible elevations of the surface above
the bases of the spines. There are sometimes one, two, or more spines
upon the ears, but this does not appear to be a constant character :
the entire surface is marked by close concentric undulating striae.

* The Geological Report of Progress referred to in this and one or two other instances was communi¬
cated to the Governor as the law required, but it was not published, and the matter was incorporated in
the volumes cited.

158

PALEONTOLOGY OF NEW-YORK.

The dorsal valve is marked by few or many interrupted radiating

ridges, but no spines have been observed attached to them.

The specimens are usually from half an inch to six-tenths of an inch
wide ; one well-formed specimen measures inch in length and -f a inch
in width.

The interior of the dorsal valve is often pretty regularly convex, and
sometimes nearly flat in the upper part and abruptly deflected towards
the front. The surface is marked by interrupted ridges and fine concen¬
tric striae, with a bilobed or bifurcate cardinal process and faint indica¬
tions of teelh-sockets.* The muscular impressions have not been dis¬
tinctly observed ; but the reniform vascular impressions in the Iowa
specimens are similar to others of the genus. The interior of the ventral
valve is unknown.

After a careful comparison of specimens from the Corniferous limestone and
Hamilton group, with those from Burlington in Iowa and the town of Louisiana
in Missouri, I am unable to find any differences which I believe to be of specific
importance ; and am therefore compelled to regard those of New-York as identi¬
cal with those of the West. A specimen from the Corniferous limestone of Ohio is
scarcely distinguishable by any character of form, or even in the color of the rock,
from specimens of the Oolite limestone at Burlington in Iowa ; and a well-formed
specimen (figure 35, Plate 23) from the limestone of the Marcellus shale is dis¬
tinguished from the Iowa specimens only by its dark color. In each, the surface
striae and the ridges at the base of the spines, as well as the form and measure¬
ments, correspond. It may be observed, however, that the prevailing form of the
specimens from Burlington is somewhat broader than those from the Corniferous
limestone, and that in the latter the ears as well as the spiniferous ridges are
often more pronjinent.

In comparing a considerable number of specimens of Productus shumardianus from
Burlington, Iowa, I find the form of the shell pretty constant ; but there are
sometimes more or fewer spines on the umbo, while in some specimens this part of
the shell has scarcely any spines. There is a similar irregularity in the distribu¬
tion of spines upon the body of the shell, and not unfrequently we find it almost,
destitute of these appendages, and scarcely -separable from the .forms I have de¬
scribed as Productus pyxidatus. The same differences are observable upon the
dorsal valves of which we usually have the interior surface exposed ; sometimes
few, and sometimes numerous nodes, indicating the fossets of the exterior.

* In the greater number of individuals examined, it is impossible to determine that teeth-sockets do
exist; the appearance, even under a lens, indicating their absence.

PRODUCTELLffE OF THE HAMILTON GROUP.

159

Specimens of this species, both from Iowa and New-York, have in some instances
shown a very minute truncation at. the apex ; and in one or two individuals
there is a barely perceptible indication of an area, which extends on either side
half-way from the apex to the extremities.

This species has usually been referred to P. murchisonianus of De Koninck
(which is also represented as having a narrow area, and belonging properly to the
Genus Strophalosia). In the comparison of numerous forms which have been
described as distinct species, and which he refers to this one, Prof. De Koninck
remarks as follows :

“ The greater number of these species have been established only upon imper-
“ feet specimens, and require a rigorous revision by their authors. The P. mur-
“ chisonianus to which we must refer, according to M. De Yerneuil, the Strophe-
“ mena pustulosa of Mr. Hall, is easily distinguished from the preceding species*
“ by its area,f by the less profound insertion of its ventral valve, by the less con-
“ siderable number of its tubercles, and by its transverse .wrinkles. It is not
“ always so easy to separate it from the P. subaculeatus.”

The species described by me as Strophomena pustulosa has been alluded to
under the preceding species, and appears to me to be the dorsal valve of a smaller
species of Productella, the P. truncata . I can scarcely suppose that such extreme
variations occur in the same species, as are shown in these two forms ; and if so,
we must confess that we have very feeble means of discriminating species among
this group of shells. In the eastern part of the State, where the P. truncata is
abundant, I have not seen the larger forms, though they occur in the same asso¬
ciation on the shore of Lake Brie ; yet in that locality we have at least fifty of
the smaller .forms where we find one of the larger, and but rarely an individual
which might be doubtfully regarded as in an intermediate stage of growth.

Geological formations and localities. It will be observed that this species ranges
from the Corniferous limestone to the Oolitic limestone, at the base of the Bur¬
lington limestone in Iowa. It occurs at Williamsville in the Corniferous limestone,
and in the same rock in Ohio and in Illinois. It is found in the limestone of the
Marcellus shale on the shore of Lake Erie above Buffalo, and in the shales of the
Hamilton group at the same place ; at Pratt’s falls in Onondaga county ; at Mos¬
cow in Livingston County, and other places. It occurs in the same horizon at

* Productus gerardi.

f Among the illustrations of this species by Prof. De Koninck, pi. xvi, fig. 3 /, shows a narrow area and
minute foramen; while figs. 3 b and 3 e, which are similar views of other specimens, do not show an area,
and have every external appearance of being true Productus. The Strophomena membranacea of Yan-
uxem, supposed by that author to be identical with Leptcena membranacea of Phillips, is also cited by
Prof. De Koninck as one of the synonymes under Produetus murchisonianus . The species referred to by
Yanuxem is illustrated under Productella hirsuta of the Chemung group, and is certainly very distinct
from either of those in the Hamilton group or Corniferous limestone.

1©®

PALAEONTOLOGY OP1 NEW- YORK.

Hamburgh (Illinois) and in the town of Louisiana (Missouri), and in the calca¬
reous beds at the base of the Burlington limestone at Burlington (Iowa).

In the Tully limestone there is a very extreme form, which, after careful com¬
parison, I can only regard as a variety of this species, having the front greatly
produced. The beak is extremely incurved, and can only have been minutely if at
all truncated.

Froductella spinulicosta.

PLATE XXIII.

Productus spinulicosta : Hali, Tenth Report on the State Cabinet, p. 173. 1857.

Shell broad, semielliptical or somewhat orbicular ; hinge-line generally
a little less than the greatest width of the shell.

Ventral valve varying in shells of different size, from moderately to
extremely gibbous in the middle, with the beak strongly incurved.
Dorsal valve moderately concave in its upper part, and becoming more
concave or arcuate towards the front.

Surface marked by fine strong concentric striae, which are sometimes
crowded and wrinkled on the body of the shell. There are several rows
of interrupted ridges or spine-bases, which in entire specimens support
slender spines. The ears are strongly wrinkled, and support a row of
four or five spines just below the hinge-line.

The distinction between the species and the authentic specimens of P. shu-
mardiana is not such as to entirely satisfy me of their specific difference. The
specimens originally referred by me to this species are smaller than the prevailing
size of P. shumardiana at Burlington, Iowa, and some of the younger individuals
are somewhat broadly truncated at the apex. The spiniferous ridges are usually
longer and more prominent than in the Burlington specimens.

Geological formation and localities. In the calcareous bands of the Marcellus
shale and in the shales of the Hamilton group, on the shores of Lake Erie, Cayuga
and Seneca lakes and other places;

Froductella truncata.

PLATE XXIII.

Productus truncatus : Hall ip Tenth Report on the State Cabinet, p. 171. 1857.

Strophomena pustulosa : Hall, Geol. Report 4th District New-York, p. 189, f. 4. 1843.

Not Productus pustulosus : Phillips.

Shell small, concavo-convex : hinge-line equalling or less than the
greatest width of the shell.

PRODUCTELLJE OF THE HAMILTON GROUP.

101

Ventral valve gibbous in the middle, broadly truncate on the umbo,
regularly curving to the front, abruptly depressed at the sides, and
forming narrow flattened ears at the cardinal extremities. A narrow
linear area, and a perceptible foramen or callosity under the beak.
Dorsal valve moderately concave, minutely truncate at the apex, with
a thickening of the hinge-line in well-marked specimens.

Surface of ventral valve wrinkled at the hinge-line, marked by a greater
or less number of spiniferous ridges, supporting slender spines. of mode¬
rate length. There is usually a row of two or three spines on the ears
just below the hinge-margin, and they are often closely arranged about
the limits of the truncation on the umbo, and more sparsely on the
middle and lower part of the valve. The dorsal valve is wrinkled along
the hinge-line, and the surface covered by numerous elongate spinife¬
rous pustules, bearing, when 'perfect, long slender spines. The entire
surface of both valves is marked by fine closely arranged concentric
striae. Interior of the dorsal valve wrinkled and pustulose, with a con¬
spicuous depression at the umbo, and a short bifurcating cardinal
process.

-This little shell is extremely abundant in the calcareous bands of the Marcellus
shale, the individuals sometimes lying in absolute contact or close proximity through
layers of considerable extent. They vary in size from the diameter of less than
one line to a quarter of an inch, and rarely to three-eighths of an inch. Notwith¬
standing the great numbers of specimens, I have not yet been able to trace them
to any larger size than those illustrated, though they may attain greater dimen¬
sions. In the larger specimens they very much resemble the young of Productus
(Productella) shumar dianus ; but they are much more gibbous, the truncation is
broader, and the area more conspicuous.

The species described by me as Strophomena pustulosa from the Marcellus shale,
is apparently the dorsal valve of this' species, some of the specimens being illus¬
trated on Plate xxm. Some of these valves are larger than any of the ventral
valves which have been elsewhere seen; but since we know no other species in
that association, I have referred them to the same.

On the authority of M. De Yerneuil, the S. pustulosa has been referred to the
Productus (i Strophalosia) murchisonianus of De Koninck, which is likewise regarded
as identical with the species I have described as Productus shumardianus.

[ Paleontology IV.] 21

i m

PALEONTOLOGY OP NEW-YORK.

The illustrations on Plate XXIII, figures 18, 19 & 20 are enlarged three diameters, and
those from 12-17 are enlarged two diameters. The interior of the dorsal valve show¬
ing the cardinal process, is enlarged sis diameters.

Figure 28 represents the impression left in the stone by a dorsal valve, with the area
and minute foramen of the ventral valve. This one is a little less broadly truncate,
and presents other slight differences from the ordinary forms of this species.
Geological formation and localities. This specie's occurs principally in the calca¬
reous beds of the Marcellus shale, and in the shale itself. It is found in large num- '
bers near Schoharie, and also near Manlius in Onondaga county, at Avon in Liv¬
ingston county, and on the shore of Lake Erie above Buffalo. It occurs also in the
shale of the Hamilton group near Tully in Onondaga county.

Prodiictella duinosa.

PLATE XXIII.

Productus dumosus : Hall, Fourteenth Report on the State Cabinet, p. 99. 1861.

Compare Productus spinulicosta : Hall in Tenth Report on- the State Cabinet, p. 173. 1857.

Compare Productus shumardianusi : Geol, Report of Iowa, Yol. i, part ii, pa. 499, pi. 3, f. 9, and pi. 7

f. 1 ; and this volume p. 150.

Body of the shell subovate, and, including the ears, somewhat hemi¬
spheric ; length and width about equal ; the hinge-line usually a little
less than the greatest width of the shell.

Ventral valve extremely gibbous or ventricose in the middle, contracted
at the umbo, which is prominent, with the beak strongly incurved
over the hinge-line. The middle and lower part of the shell is regu¬
larly arching, and almost vertically depressed at the sides of the umbo
to the narrow flat ears. Dorsal valve more or less deeply concave, cor¬
responding nearly with the opposite valve.

The surface of the ventral valve is marked by numerous slender spines,
the bases only of which are usually preserved. The spines on the umbo,
and a row on the ears, rise almost vertically from the surface ; while
below this the surface is marked by short rounded ridges, each of
which terminates in a slender spine. Towards the front of the shell
the ridges are continuous, being only slightly interrupted by the
growth of the spines. The bases of the spines are more or less distinctly
arranged in concentric rows, and vary greatly in their number and
proximity to each other. The entire surface is marked by closely

PRODUCTELLiE OF THE HAMILTON GROUP.

fl63

arranged undulating concentric striae. The dorsal valve, in its upper
part, is marked by rounded fossets, while on the middle and lower
part the depressions become, elongate grooves. No spines have been
observed.

A careful examination of the hinge-line of the ventral valve has shown
a narrow area, with foramen and small teeth. In one specimen, preserv¬
ing the two valves, there is a barely perceptible separation of the mar¬
gins for a short distance along the middle of the hinge-line ; while in
another similar specimen, there is no such separation perceptible.

This species is from half an inch to an inch in length and diameter. The varia¬
tions in its different stages of growth, and the variable number of spines upon
its surface, render it difficult, with the materials before me, to point out the cha¬
racters which separate some of the smaller specimens, on the one hand from P.
navicella, and the other from some forms of P. shumardiana.

Geological formation and localities. This fossil occurs in the Hamilton group,
at Tinker’s falls and Delphi falls in Onondaga county; at Bellona in Yates coun¬
ty ; on the shore of Canandaigua lake ; at Moscow in Livingston county ; and
near Hamilton in Madison county, New-York.

Productella exanthemata.

PLATE XXIII.

Productus exanthematus : Hall in Tenth Report on the State Cabinet, p. 174. 1857.

The original of this species is a moderately concave dorsal valve, the
interior of which is closely studded with pustuliform elevations, indi¬
cating fossets on the exterior of the shell. Near the umbo these eleva¬
tions are nearly round, becoming oval below, and sometimes forming
short oblique wrinkles. The cardinal process is distinctly bilobed ; and
there are obscure indications of teeth-sockets.

The characters are dissimilar to those of the interior of valves of well-marked
specimens of P. shumardiana , 'though many of the dorsal valves of that species
show numerous short ridges on the interior surface^; but I have not been able to
find a gradation to this character, Among the collections from the Corniferous
limestone; there are several other dorsal valves with a similar cardinal process,
and round pustuliform elevations in the upper part of the shell, while they

I ©4

PALAEONTOLOGY OF NEW-YORK.

become elongated below, with numerous oblique wrinkles. It is equally difficult
to unite these with typical forms of P. shumardiana, though ultimately all these
varieties may be found to constitute only phases of a very variable species.
Some examples of dorsal valves, similar to the typical forms of P. exanthamata,
have been found in the Chemung group ; but all these are moderately concave,
and never approach the form of typical P. shumardiana.

Geological formation and localities. In the shales of the Hamilton group, on the
shore of Seneca lake ; and at Tinker’s falls, Onondaga county.

Productella tullia ( n. s.).

PLATE XXIII.

Shell broadly ovate, subhemispheric ; hinge-line equalling or a little
less than the greatest width of the shell.

Ventral valve ventricose with the apex extremely incurved, and much
produced in front.

Dorsal valve more or less gibbous, often moderately concave in the
upper and middle portions, and abruptly deflected and produced in
front.

Surface of ventral valve marked by scattered slender spines. Specimens
of the dorsal valves are nearly all of the interior, strongly wrinkled
on the hinge-line, with numerous pustuliform elevations, ‘which be¬
come elongated on the front of the valve. Between these stronger eleva¬
tions are numerous fine and sometimes coarser radiating striae which
become more distinctly visible as the shell is exfoliated from the
inside, showing that they pertain to the exterior surface. The cardinal
process is bifurcate, and of considerable length.

The interior of the dorsal valve is recognized by numerous pustuliform ridges
and distinct intermediate striae, the latter a character not observed in any other
species.

The figures 41 -44 illustrate the usual form and features of this species as it occurs in the
Hamilton shales.

Geological formation and localities. In the Hamilton group, near Tully and
Delphi falls in Onondaga county. A single dorsal valve of larger size and mode¬
rate convexity is from the Tully limestone.

PR0DUCTELLJ3 OF THE HAMILTON GROUP. 165

Productella subalata.

PLATE XXIII.

Produdus subalatus : Tenth Report on the State Cabinet, p. 174. 1847.

“ ■ “ Geological Report of Iowa, part .ii, pa. 500, pi. 3, f. 10.

Shell semielliptical or semicircular, usually much wider than high ;
hinge-extremities equalling or less than the width of the shell. Ven¬
tral valve ventricose in the middle, gibbous on the umbo and towards
the beak ; extended, flattened and auriculate at the hinge-extremities :
beak incurved over the hinge-line. There. is a distinct narrow area
extending for more than half the length of the hinge-line.

The surface is marked by fine concentric striae, with indications of radia¬
ting striae within the substance of the shell. The cardinal margins and
the ears are marked by strong wrinkles which are often visible on the
body of the shell. The spines are variable in number, often crowded
together on the ears and adjacent portions of the shell, and irregularly
scattered upon the middle and anterior part of the valve.

This species is noticed in this place from its great similarity to the P. rarispina
of the Chemung group of New-York. The specimen figured (PI. xxiii, f. 49) is a
ventral valve above the prevailing size, with a greater extension of the hinge-line
than usual.

Geological formation and locality. In the calcareous shales of the Hamilton
group at Rock island, Illinois.

Product us ! - (sp.).

PLATE XXIII.

A single dorsal valve, of comparatively large size, occurs with P. spi-
nulicosta, near Bellona in Yates county. When entire, it has had a length
of about one inch and a quarter, with a width of an inch and a half. The
interior of the shell is exposed, but the cardinal process is broken off,
and there are no teeth-sockets visible. The surface is marked by slender
pustuliform ridges, which become more elongate as they recede from the
hinge-line, and on the middle and lower part of the shell are bifurcated,
and show finer ridges between.

This specimen cannot be clearly identified with any described form ; but in
the absence of other material, I hesitate to indicate it as a distinct species.

Geological formation and locality. In the shales of the Hamilton group, near
Bellona, Yates county.

tm

PALAEONTOLOGY OF NEW-YORK.

PRODUCTELLJ3 OP THE CHEMUNG GROUP.

Prodnctella hirsuta.

PLATE XXIV.

Strophomena membranacea : Vakcxem, Sep. 3d Geol. Dist. New-York, p.168, f. 4 and 5.

Not Leptcena membranacea : Phillips, Pal. Fossils, p.60, f. 101.

Not Productus membranaceus : Hall in Tenth Report on the State Cabinet, p. 175. 1857.

Shell semielliptical, concavo-convex : hinge-line equalling or a little
less than the width of the shell ; length and breadth about as 8 to 10
or 12, or as 9 to 11, and, from natural or accidental causes, varying to
length and breadth equal.

Ventral valve convex in the middle, gibbous on the umbo, gradually
curving to the front and lower lateral margins, and abruptly depressed
towards the cardino-lateral margins, which are nearly fiat and broadly
auriculate, with extremities usually rounded. Dorsal valve moderately
- concave, flattened towards the cardinal extremities, which are always
rounded.

Surface marked by fine imbricating concentric striae. On the ventral
valve there is a row of somewhat strong, diverging, nearly straight
spines on each side just below the hinge-margin ; and the entire sur¬
face (except sometimes the umbo and more prominent portions of the
valve) is covered by numerous slender spines, the bases of which form
small elongate pustules on the surface. There is some evidence of an
extremely narrow area on the ventral valve, and of teeth-sockets in the
dorsal valve.

In a cast of the ventral valve, the occlusor muscular imprints are nar¬
row and semioval, but no distinct impressions of the divaricator muscles
have been observed. There is doubtful evidence of the presence of hinge-
teeth. The interior of the dorsal valve is marked by numerous fine elon¬
gate papillae, and towards the margin these are very closely arranged,
giving a peculiar striated aspect to the surface (a feature more percepti-

PRODUCTELLJE OF THE CHEMUNG GROUP.

167

ble in specimens from the skaly beds than in those from the arenaceous
portions of the group). In the midst of these are the coarser pustules
indicating the spine-bases of the exterior surface. The cardinal process
is short and strong, bilobed at the extremity, with each division less
deeply lobed. The process is supported at the base by an oblique ridge,
which is often not visibly separated from the hinge-margin, but in rare
examples has shown obscure evidence of teeth-sockets. There is a slender
median septum, which is not always preserved, on the interior surface
of the dorsal valve.

This species is subject to considerable variation in form, being often much
extended on the hinge, and nearly once and a half as wide as long, while in other
examples the length is nearly equal to the breadth : those with the length and
breadth nearly equal, are the most gibbous in form. Not unfrequently the
shell appears to have been unequally developed on the two sides of the apex.
The species is distinguished from its associates by its wide moderately convex
form, concentric striae and very slender spines, the bases of which are usually
but little extended on the surface. The interior is more finely papillose than the
other species.

I believe this to be the species which Mr. Vanuxem regarded as identical with
Lepton a membranacea of Phillips, and which has been recognized as Productus
( Strophalosia ) murchisonianus by De Koninck. I am quite unable, however, to find
corresponding characters, and am therefore constrained to adhere to the specific
designation applied by me in 185*7.

Figures 1-9 illustrate the prevailing forms of this species. The dorsal valves all show
the interior surface, while the ventral valves partially preserve the exterior, hut in
many of them Hie shell is more or less removed by maceration and solution. The
spines on the surface are rarely preserved, but in some specimens the row of long
spines near the hinge-margin is seen in part, as illustrated in two of the figures. Fig¬
ure 9 is a ventral valve, which is more rotund and. shorter on the hinge-line than
usual.

Geological formation and localities. This species is of common occurrence in
the green arenaceous shales of the Chemung group at Philipsburgh and Rockville
in Allegany county; along the line of the Corning and Blossburgh railway;
and at Covington, Pennsylvania.

168

PALAEONTOLOGY OP NEW-YORK.

Productella hirsuta, var. rectispina.

PLATE XXIV.

A group of figures at the lower part of this plate were originally sepa¬
rated, under the impression that they were a distinct species ; but later
examination has induced me to unite them with this as a variety, till
more positive differences can be ascertained. They occur in a fine fissile
and almost slaty sandstone in the Chemung group in the south part of
Steuben county, and a few specimens from other localities have the same
characters : these hold a somewhat higher position in the series than
those from Philipsburgh. The condition of their preservation in a coarse
matrix has given a somewhat different aspect to the surface markings,
and the spines on the hinge-line, when preserved, are vertical ; while
in the specimens from Philipsburgh and the Blossburgh railroad, the
spines are always directed obliquely outwards. The same feature of dis¬
tortion or inequality on the two sides of the beak prevail in all the spe¬
cimens from this locality in Steuben county, as well as in those of Alle¬
gany county and other places. The casts or impressions in this rock
have a more Coarsely pustulose or wrinkled surface ; and in some imper¬
fect specimens of the same type from Meadville ( Pennsylvania), the
valves have had a diameter of more than two inches, and the surface is
strongly wrinkled on and near the cardinal margins.

A single individual in a setnicalcareous matrix from Troup’s creek near the
Pennsylvania line, in the vicinity of the sandstone specimens, preserves the sur¬
face characters in greater perfection than any specimen elsewhere observed. An
enlarged view of a portion of this shell is given in one of the figures.

PRODUCTELLiE OF THE CHEMUNG GROUP.

109

Productella feoyiiii

PLATE XXIV.

Produdus boydii : Hall in Tenth Report on the State Cabinet, p. 179. 1857.

Shell of medium size or larger, transverse, varying from semielliptical
to broad-oval from the rounding of the cardinal extremities ; cardinal
line less than the width of the shell.

Ventral valve varying from moderately convex to gibbous in the middle
and towards the umbo, with a more or less* defined mesial depression
extending from the umbo to the front of the shell, which is sinuate,
somewhat gently curving to the front and baso-lateral margins, abruptly
depressed on the cardino-lateral slopes, and extended into wide ears
which are more or less distinctly rounded at the extremities.

Dorsal valve moderately concave, with a distinct longitudinal mesial
elevation corresponding to the depression of the ventral valve, and
giving the basal margin a sinuate outline. Cardinal extremities round¬
ed, and the cardinal line much shorter than the width of the shell.
Surface concentrically striated, and marked by numerous elongate pus-
tuliform spiniferous ridges supporting slender elongate spines, while
there are one or two rows of stronger curving spines on the ears. The
interior of the dorsal valve is marked in like manner by pustuliform
nodes, indicating fossets on the exterior surface, which sometimes
have their length transverse to the shell, or producing short transverse
wrinkles. In some specimens, faint radiating strise mark the surface of
the shell.

The casts of the ventral valve show the marks of the occlusor mus¬
cles near the apex on each side of the mesial depression, which, on the
interior of the shell, would be an elevated ridge. The divaricator muscu¬
lar impressions are deeply striated, wide and spreading, extending nearly
to the middle of the length of the shell. The interior of the dorsal valve
shows a narrow mesial septum, but the cardinal process has not been
determined. The whole interior surface is papillose or punctate.

[ Palaeontology IV.] 22

17®

PALAEONTOLOGY OF NEW-YORK.

T This species is distinguished by the prominent and rather distant spiniferous
tubercles, by the shallow median depression of the ventral valve, and also, by the
strong curving spines on the cardino-lateral margins. In an examination of twenty
or thirty individuals of this species, I am unable to find any variations or grada¬
tions that would indicate an approach to any other species. The shell appears to
have been very variable in form in its normal Condition, and this variation has
been increased by pressure during the consolidation of the matrix. The form of
the valves .does not vary greatly from those of P. hirsutus, but it is usually pro¬
portionally shorter on the hinge-line.

The specimens, though occurring in considerable numbers, have not afforded
satisfactory means of determining the character of the hinge, or the presence or
absence of an- area.

Geological formation and locality. In the Chemung group at Philipsburgh in
Allegany county, and near Elmira.

Productella rarispina.

PLATE XXIV.

Produdus rarispinus : Hall in Tenth Report on the State Cabinet, p. 178. 1857.

Shell semielliptical ; the proportions of length and breadth as 6 to 8,
as 7 to 10, or sometimes equal; hinge-line equalling or a little greater
than the width of the shell.

Ventral valve ventricose, somewhat flattened or slightly depressed in
the middle, curving abruptly to the front, and a little more gradually
to the baso-iateral margins, abruptly depressed on the cardino-lateral
slopes and expanded into ears which are strongly deflected at fhe
extremities.

Dorsal valve deeply concave in the middle, flattened or slightly concave
on the cardinal angles.

Surface marked by fine concentric striae, and sometimes, in partially
exfoliated shells, there are appearances of radiating striae. The ears
are strongly wrinkled, and support several comparatively strong round¬
ed spines, and others of similar character are scattered over the sur¬
face. These spines rise directly from the shell, with a pustule-like
elevation on all sides, but not raised in elongate nodes as in most of
the species. The dorsal valve also bears marks of a few similar spines.

PRODUCTELLiE OF THE CHEMUNG GROUP.

171

A careful observation of the hinge-line of the ventral valve discloses
an extremely narrow flat space, which may be regarded as an area with
a narrow open aperture ; but so obscure are these features, that, unless
examined with great care, they may be readily overlooked.

The cast of thp ventral valve shows elongate semioval imprints of the
occlusor muscles on the umbo, and wide spreading strongly striate diva-
ricator muscular impressions.

In the interior of the dorsal valve we find a slender mesial septum
which terminates in a bilobate cardinal process, the shell being some¬
what thickened at the sides, and probably having minute dental sockets ;
but these have not been distinguished. The entire interior surface of both
valves is minutely papillose, and these points become more elongate on
the middle of the shell, and finally towards the front are extended in
extremely slender striae, which are likewise impressed upon the cast.

The figures 19 - 23 of Plate xxi v illustrate the usual form and condition of this spe¬
cies ; one specimen preserving two of the spines, and showing the bases of others on
the surface of the valve.

This species occurs in the same beds with P. hirsuta and P. loydii, and is rea¬
dily distinguished from either of these by its greater gibbosity and fewer spines ;
while the casts may be recognized by the extremely fine papillae, and their exten¬
sion in capillary striae. In general characters, it resembles P. subalata of the Ham¬
ilton group at Rock island, Illinois ; but it is much more convex, and the ears less
extended than the usual form of the specimens from the western locality. The
specimens before me are not in a condition for satisfactory comparisons of the
two forms in all their parts ; but I would suggest that such comparisons be insti.
tuted, with a view to determine the relations of the species.

Geological formation ~and localities. In the arenaceous shales of the Chemung
group at Philipsburgh in Allegany county, and on the line of the Corning and
Blossburgh railroad.

172

PALAEONTOLOGY OP NEW-YORK.

Productella lachrymosa.

PLATE XXV

Strophomena lachrymosa : Conrad, Jour. Acad. Nat. Sciences Philadelphia, Vol. viii, pa. 256, pi. 11, f. 9.

Shell ovoid or subhemispheric, semielliptical in outline ; the propor¬
tions varying from nearly equal length and breadth, to width nearly
once and a half as great as the length : hinge-line equalling or less
than the width of the shell ; extremities angulated or rounded.

Ventral valve varying from moderately gibbous to very ventricose ;
the umbo sometimes a little elevated above the hinge-line and often
extremely elevated and incurved, often flattened in the middle, more
or less regularly arching from beak to base, abruptly depressed at the
sides of the umbo, and spreading into more or less expanded ears,
which are usually deflected, and rarely extend beyond the width of
the shell below : basal margin regularly arched, or sometimes nearly
straight in the middle.

Dorsal valve moderately or more deeply concave, following in some
degree the curvature of the opposite valve. In some specimens it is
nearly flat in the upper and middle portions, and abruptly deflected
at the margin.

Surface of ventral valve (where the shell is partially preserved) marked
by fine concentric striae, and, upon the ears, by strong concentric
wrinkles, which become obsolete or are but faintly marked on the
body of the shell. There is a row of four or five round spines rising
from a little below the cardinal margin on each side of the beak ; and
surfaces of the casts are marked by numerous slightly elongate spini-
ferous tubercles, from which rise somewhat slender spines. These spi-
niferous tubercles are sometimes principally arranged in lines along
partially continuous ridges. The dorsal valve is strongly wrinkled on
the hinge-line, and sometimes these marks are continued across the
valve in considerable strength; but the specimens examined do not
show spine-bases. The casts or impressions of the exterior show pus¬
tules which indicate fossets on the exterior surface of the shell.

PRODUCTELLiE OP THE CHEMUNG GROUP.

173

The interior of the valve is finely papillose and papillose-striate, so
that some of the casts have a minutely interruptedly-striate surface.
The cast of the ventral valve preserves irregular and somewhat elongate
semioval imprints of the occlusor muscles, and the impressions of the
divaricator muscles are deeply striated, wide spreading, reaching the
inner margin of the wings, and extending for more than one-third the
length of the valve. The cardinal process of the dorsal valve is bilobed
in the middle, and each lobe is again divided, leaving a quadruple imprint
on the stone.

This shell is subject to much variation in the. convexity of the ventral
valve, and also in the distribution of the spiniferous tubercles. The larger
number of specimens are ventricose, a little flattened and rarely depres¬
sed along the middle.

Mr. Conrad has described the ventral valve of S. lackrymosa as '*♦ ventricose,

“ depressed towards the hinge-extremities; disc slightly flattened in the mid-
“ die, marked with numerous elongated tubercles arranged in radii which
“ profoundly bifurcate ; hinge-line not salient at the extremities, angulated, •
“ sub-margin with prominent tubercles ; umbo ventricose ; summit above the
“ cardinal line. Locality : Chemung-narrows, New-York, Devonian shale.”

The specimens in my collections from the Chemung-narrows are usually not
extremely ventricose, and the spiniferous tubercles are more elongate than in
most other species in the collection, sometimes becoming costae towards the
front of the shell. This feature is shown in some of the figures on Plate xxv,
while other figures illustrate the prevailing forms of those which I have Referred to
this species from Cattaraugus county and farther west.

Notwithstanding the variable character of the species, it is for the most part
readily recognized among the others of the group ; and it certainly has no very
close resemblance to any of the forms in the Corniferous limestone or Hamilton
group. /

The casts show faint indications of an area, and of teeth in the ventral valve ;
but teeth:sockets are not visible in the dorsal valves of any specimens I have
thus far examined.

Geological formation and localities. In the Chemung group, near Pactoryville
and Chemung-narrows, Chemung county ; at Painted-post, and near Bath in Steu¬
ben county; near Conewango and Randolph in Cattaraugus county, and near
Ellington in Chautauqua county.

174

PALAEONTOLOGY OF NEW-YORK.

Productella lachrymosa, var. lima.

PLATE XXY.

Strophomena lima : Conrad, Jour. Acad. Nat. Sciences, Philadelphia, Yol. viii, p. 256.

This species is described by Mr. Conrad as follows :

“ Semiorbicular ; lower valve ventricose, depressed in the middle, most
“ profound towards the base ; surface with numerous elliptical tubercles
“ disposed somewhat in quincunx order ; umbo ventricose ; superior
“ lateral spaces much depressed. Locality : Occurs with the preceding
“ species [ i. e. P. lachrymosa, at Chemung-narrows]. Differs from the
“ last in the depressed middle, much more numerous shorter tubercles,

“ etc. The size is nearly the same.”

Among the collections, and associated with P. lachrymosa , are specimens cor¬
responding with this description ; but I find so many intermediate forms, that
with my present sources of information I cannot regard them as of a distinct spe¬
cies. Characteristic specimens of these are figured in connexion with P. lachry¬
mosa. The well-marked specimens are distinctly depressed in the middle, giving
the front a sinuate aspect ; while the dorsal valves present a corresponding ele¬
vation ; the latter showing as a depression in impressions of the interior of the
valves, which are often the only condition in which we have them.

In these characters the shell approaches P. boydii; but the ventral valve is
usually more gibbous, the depression is much broader and becomes obsolete,
while the character of the spiniferous tubercles is very distinctive.

Geological formation and localities. In the Chemung group, associated with P.
lachrymosa , at Randolph and South-valley in Cattaraugus county ; Ellington in
Chautauqua county, and other places.

Productella lachrymosa, var. stigmata.

PLATE XXY.

Shell subovoid or hemispheric.

Ventral valve ventricose, regularly rounded on the surface, sometimes .
nearly flat towards the front; hinge-line less than. the width of the
shell ; umbo rounded and much elevated above the hinge-line ; apex
closely incurved.

PRODUCTELLiE OF TJIE CHEMUNG GROUP. 175

Dorsal valve large, somewhat regularly and sometimes deeply concave,
but with barely any indication of sudden deflection to the front.
Surface of the casts of the ventral valves finely striate or puncto-striate
longitudinally, the puncta more marked towards the base of the valve.
The ears are strongly wrinkled, with the bases of several spines upon
the folds ; these wrinkles extend in obscure undulations across the body
of the shell in its upper part. The entire surface is marked by narrow
elongate fossets which indicate the places of the spines, the slender
bases of which sometimes remain in the depression : in some indi¬
viduals, there are oval pustules in place of the fossets. There is no
appreciable tendency to elongation of these pits or ridges towards the
•front of the shell ; nor does the surface become costate towards the
margin, as those which I have referred to P. lachrymosa proper, from
Chemung-narrows.

The dorsal valves, associated in the same beds, are strongly wrinkled
on the ears, with the folds faintly marked on the body of the shell, which
is studded with numerous scattered shallow depressions corresponding to
the spines on the opposite valve. The cardinal process is distinctly
four-lobed.

This is one of the largest forms among the Chemung species ; and I am inclined
to believe that it may ultimately be proved specifically distinct from P. lachrymosa.

Geological formation and localities. In the light-colored sandstones of the Che¬
mung group, near Olean ; and in a similar rock at Conewango, and in some de¬
composing semicalcareous layers at Randolph and East-Randolph, Cattaraugus
county, New-York.

Productella speciosa.

PLATE XXV.

Prod'uctus speciosus : Hail, in Tenth Report on the State Cabinet, p. 176. 1857.

Shell broadly ovate, subhemispheric ; hinge-line less than the greatest
width of the shell, the extremities obtusely angular.

Ventral valve ventricose : umbo much elevated above the hinge-line,
with the apex closely incurved, regularly arcuate from beak to base and
more rapidly curving to the sides, abruptly depressed on the sides of
the umbo, and concave between it and the narrow short ears.

17©

PALAEONTOLOGY OF NEW-YORK.

Dorsal valve moderately or deeply concave, and more abruptly curving
to the front.

Surface of ventral valve marked by fine concentric striae, and, on the
ears, by a few short wrinkles which become obsolete on the sides #of
the umbo. There are marks of four or five spines on each of the ears
just below the hinge-line, and a row of tubercles or spine-bases along
the summit of the wrinkles as far as they extend. The body of the
shell is covered with as many as twenty-five concentric rows of spi-
niferous tubercles from beak to base : these are closely arranged, and
only become a little irregular towards the front of the shell. The sur¬
face of the cast is minutely punctate.

The interior of the dorsal valve is strongly wrinkled on the hinge-
margin ; and these wrinkles are indistinctly continued across the valve,
and studded with numerous concentric ranges of tubercles, which indi¬
cate the place of fossets or of spines on the opposite side : the interme¬
diate space .is marked by distantly disposed papillse. The cardinal process
is strong at its base, and bilobed above. There are obscure evidences of
teeth-sockets.

This species resembles some of the forms of P. lachrymosa ; but the spiniferous
tubercles are smaller, more closely arranged and more numerous, while the umbo
of the ventral valve is narrower and somewhat abruptly attenuate. The dorsal
valve is studded with numerous tubercles on the interior surface ; while in that
species the surface is papillose, with indistinct wrinkles and some distant eleva¬
tions. In P. lachrymosa , the divisions of the cardinal process are more divergent,
and each division is again bilobed ; while in this the divisions appear to be
simple.

The species was originally described from a well-formed ventral valve ; the same
fragment of stone containing a dorsal valve of corresponding character. Numerous
individuals among later collections preserve a similar form and expression of
ventral valve, but none of them are quite so extremely arcuate. This feature,
however, is probably characteristic of the older shells, while the younger ones
would acquire this form from continued growth. A careful examination of all the
specimens from different localities has shown constant and reliable characters for
the determination of the species.

The illustrations show the prevailing differences of form and character among
the specimens of this species.

PRODUCTELLiE OF THE CHEMUNG GROUP.

177

Geological formation and localities. The original specimens are from the Che¬
mung group, on Twenty-mile creek in Chautauque county. It occurs at Leon and
New- Albion in Cattaraugus county ; and west of Olean in Allegany county, New-
York.

Productella striatula ( n. s.)

PLATE XXV.

Body of the shell subovate ; outline semielliptical, the length equalling or
greater than the width : hinge-line equalling, or sometimes a little
greater than the width of the shell.

Ventral valve deeply convex, ventricose in the middle and on the
umbo, abruptly depressed at the sides and the cardino-lateral angles,
'forming small ears; regularly arching towards the front, which is
more or less produced : umbo elevated above the hinge-line, and the
apex closely incurved.

Dorsal valve somewhat deeply concave ; the upper part, to near the
middle of its length, often slightly concave, and abruptly deflected
towards the front : the deflected portion is sometimes more than half
the length.

Surface of ventral valve, where the shell is entire, finely striate con¬
centrically, strongly wrinkled on the ears, and the folds usually be¬
coming obsolete on the middle of the shell, but sometimes they are
retained in considerable strength. Numerous slender spines are dispo-

• sed in somewhat regular concentric ranges along the front and middle
of the shell, while they are often irregularly disposed and sometimes
absent from the umbo and upper middle portions of the shell, but are
always present on the ears. When the shell is partially exfoliated, the
surface is marked by fine closely arranged radiating striae. Where the
shell is entire, the spines rise almost vertically from* the surface, with
scarcely elongate ridges at their base, while in the exfoliated surface
they leave oval depressions around the spine-bases ; but this character
is subject to variation from -the nature of the matrix.

The interior surface of the dorsal valve only is known; this is finely
[ Paleontology IV.] 23

178

PALEONTOLOGY OF NEW-YORK.

papillose or papillose-striate, without evidence, or with very slight evi¬
dence of any inequalities of the exterior. (A few gentle pustule-like ele¬
vations have been observed in one specimen.) The cardinal margin is
wrinkled, and the extremities rounded. There is a short bilobed cardinal
process and a slender mesial septum, which reaches half the length of
the shell. The occlusor muscular impressions are distinctly visible ; and
from between them, on each side, proceeds the reniform vascular impres¬
sion, which is at first slightly inclined forward, and, then curving down¬
wards about half the length of the valve, is again shortly recurved, ter¬
minating in a broader expansion, about halfway from the mesial septum
to the lateral margin of the valve..

In the specimens examined, this is a neat and well-marked species. The ventral
valve, when having few spines, somewhat resembles the young of P. rarispina ;
but it is a more delicate shell, with more slender spines. The shell is thin, easily
exfoliated, and presenting a very finely striate surface beneath, or on the partially
exfoliated portions. The greater proportion of individuals have the surface pretty
evenly studded with spines.

The dorsal valves associated in the same specimens of the rock with the ven¬
tral valves are presumed to belong to the same species, and are known by their
abrupt deflection towards the front, the finely papillose-striate surface, and ab¬
sence of pustules or nodes indicating fossets or spine-bases on the exterior surface.

Geological formation and localities. In some semicalcareous bands in the Che¬
mung group at Cherry creek, Chautauqua county; and at New- Albion, Cone-
wango and Coldspring in Cattaraugus county, New-York.

Productella Iiystricula (n. s.).

PLATE XXYI.

Shell small, concavo-convex, semielliptical : binge-line rarely equalling
and usually somewhat less than the width of the shell.

Ventral valve gibbous or ventricose, somewhat hemispheric, regularly
arching, sometimes a little flattened in the middle, abruptly depressed
towards the cardinal extremities, and produced in small scarcely
defined ears. The umbo is a little elevated above the hinge-line ; the
apex is often perceptibly truncated, and there is an extremely narrow

area.

PR0DUCTELLH3 OF THE CHEMUNG GROUP.

1179

Dorsal valve moderately or deeply concave, often nearly flat in the
upper part, and more abruptly deflected towards the front.

Surface of the ventral valve, near the cardinal angles, marked by a few
comparatively strong wrinkles, which are sometimes continued across
the body of the shell, or appear as imbricating lines with finer inter¬
mediate striae. These wrinkles are studded with very small slender
spines, giving a row along the hinge-margin, and extending in nume¬
rous concentric lines over the entire surface of the shell. The inner
surface of the dorsal valve is marked by concentric wrinkles and
numerous ranges of pustules ; but no spines have been observed.

The cast of the ventral valve shows a very narrow area, with a minute
central callosity and a bilobed apex, beneath which are cavities from the
removal of the teeth. The imprints of the occlusor muscles are narrow
elongate scars, and the wide divaricator muscular imprints are rarely
faintly preserved.

The spine-bases are seen in the casts as minute pustulose elevations,
which become more elongate towards the front of the shell.

The impressions of the exterior of the dorsal valve frequently show a
truncation of the apex (more conspicuously than some of the ventral
valves, in which the truncation is beneath the arch of the umbo) ; but
this feature does not appear to be constant. There is a pretty strong
bilobed cardinal process, with teeth sockets on each side ; but no median
septum has been observed. The cardinal process, in its exterior impres¬
sion, shows that each division is grooved, or again lobed. The interior
of the valve is minutely papillose, the papillae becoming elongated
towards the front of the valve.

The figures illustrate the prevailing form and size of this species, which occurs in great
numbers. Figure 6 is in part a restoration ; giving, however, the ordinary length
and proportions of the spines. The interior of the dorsal valve, figure 7, is enlarged
two diameters.

Geological formations and localities. This species occurs in some hard arena¬
ceous bed, at Forestville in Chautauque county; in a friable sandstone at Cone-
wango, and in some semicalcareous layers at East-Randolph, Cattaraugus county,
New- York.

18®

PALAEONTOLOGY OF NEW- YORK.

Prodiictella costatula (n. s.).

PLATE. XXVI.

Shell subovoid, more or less elongate and often extremely arcuate :

hinge-line equalling or less than the width of the shell.

The ventral valve varies from a semielliptical moderately gibbous form
in the young, to extremely arcuate in the older shell. The young
shells are wider than long, and the older are much longer than wide,
but varying greatly in proportions of length and breadth, some of them
being extremely narrow.

The surface of the ventral valve is wrinkled on the ears, and closely
striate concentrically on the body of the shell. The umbo and upper
part of the valve are marked by numerous and regularly disposed elon¬
gate spiniferous nodes, which support slender spines. These nodes
gradually become more elongated, and, below the middle, the surface'
is marked by continuous slender costse, from which, at intervals, rise
slender spines. In the young shells, and the upper half of the older
ones, the costse are not present, and a few small but extremely arcuate
forms scarcely preserve this marking on the cast ; but in the larger
specimens, the casts exhibit the costse in a very marked degree. The
casts of the' ventral valve are finely puncto-striate.

The dorsal valves which we find associated with the ventral valves
described, have been deeply concave; in the upper part they are
moderately concave, and more abruptly deflected towards the front. The
interior surface only is known, and this presents a short bilobed cardinal
process and short slender median septum. The cardinal line is scarcely
equal to the greatest width of the shell, and is terminated in short small
ears. There are three, four, or five somewhat strong wrinkles on the car¬
dinal margin, which scarcely reach the centre of the shell. The entire
inner surface is finely papillose-striate, and shows concentric striae ;
while it is thickly studded with pustules, indicating fossets on the exte¬
rior surface. These in the upper part of (the valve are oval, gradually

PEODUCTELLJE OF THE CHEMUNG GROUP.

181

elongating, and finallyJ)ecoming continuous ridges towards the anterior
margin of the valve. The area, if existing, is not greater than the thick¬
ness of the shell, and no evidence of teeth has been observed.

This species has some resemblance to P. dumosa of the Hamilton group ; but
the costse are more slender, with fewer and more slender spines. The dorsal valve
is very distinctive in its numerous fine pustules on the inner surface. The form of
the dorsal valve resembles that of the preceding species (P. striatula) in its form,
but is at once distinguished by its numerous minute pustules on the inner surface.
No reniform impressions have been observed.

In numerous specimens from several localities, this species is very constant and
well-marked in its characters.' There are, however, a few individuals from a diffe¬
rent locality, similar in form, but broader and somewhat flattened or depressed
along the middle of the ventral valve, while the surface is much more coarsely
pustulose.

Geological formation and localities. This species occurs at Chemung-narrows in
Chemung county ; Randolph and East-Randolph, Napoli, Conewango, New- Albion,
and other places in Cattaraugus county, New-York.

Productella costatula, var. strigota.

PLATE XXVI.

Ventral valve wide, a little flattened along the middle from the umbo
to the front of the shell, extremely arcuate, broad and rounded near
the umbo ; the apex closely incurved.

Surface of the upper part strongly pustulose in the cast ; the pustules
elongated in the middle, and becoming continuous costse towards
the front. The dorsal valve, in its interior and casts, is narrowly
deflected towards the front, coarsely pustulose above, and costate
towards the margin.

These forms approach to P. arctirostrata in the ventral valve ; but the. dorsal
valve found associated with that species is very distinct in form and characters.
The species, and this variety, bear much resemblance to P. arcuata of the sand¬
stones and calcareous beds below the Burlington limestone : the costse in the
ventral valve of that species are stronger and continued nearly to the apex ;
while the dorsal valve is more nearly flat, and interruptedly costate in its upper
part, the deflected portion longer, with the costse continuous.

Geological formation and locality. This form occurs in some sandy beds of the
Chemung group, near Cadiz in Cattaraugus county, New-York.

182

PALAEONTOLOGY OF NEW- YORK.

Productella arctirostrata.

PLATE XXVI.

Productus arctirostratus : Hail in Tenth Report on the State Cabinet, p. 177. 1857.

Compare Productella shumardiana of the Hamilton group, page 157 of this volume.

Shell subovate, extremely ventricose, the proportions of length and
breadth variable : hinge-line usually a little less than half the width
of the shell.

Ventral valve gibbous or ventricose : umbo very prominent and arching
over the hinge-line, flattened or slightly depressed in the centre, ab¬
ruptly depressed at the sides, and extended into short ears at the car-
N dinal extremities.

Dorsal valve moderately concave in the upper part, abruptly deflected
towards the front, and following the curvature of the ventral valve.
Surface covered by close concentric striae, with a few strong wrinkles
on the ears ; and these are more or less distinctly shown, extending
across the shell, or marking the surface of the cast. The bases of a few
spines are usually seen on the ears of the ventral valve, and the umbo
and upper part of the shell are marked by short spiniferous ridges.
These ridges become elongated in the lower part of the shell, and
are finally almost or quite continuous towards the front. The dorsal
valve is similarly marked; the concentric wrinkles extends across
the shell, and the spine bases, which are mere nodes in the upper part
of the valve, become elongated towards the front.

The casts of the dorsal valve show a bilobed cardinal process, but its
character cannot be fully made out. The casts of the ventral valve show
small cavities, from the removal of the dental lamellae, and there is an
extremely narrow area visible.

The figures 19-21, illustrate the ordinary form of the ventral valves as they occur
in casts in sandstone. Figures 16 and 17, are of the interior, and a profile view of a
dorsal valve.

Figures 22 and 23, are of a ventral valve and profile of the same, which is a large and
somewhat extraVagant form. The flattening of the upper part of the valve is continued
in a broad depression to the lower part of the shell.

PRODUCTELLiE OF THE CHEMUNG- GROUP.

183

This species bears some resemblance to the more extreme forms of Productella
shumardiana of the Hamilton group, but it is a larger and stronger shell and
marked by strong concentric wrinkles. The material at my command is not suffi¬
cient to make full comparisons.

Geological formation and localities. In the. Chemung group, at Jasper in Steu¬
ben county, and south of Cadiz.

Productella Malveata (n. s.).

PLATE XXYI.

Shell subovate or subhemispheric ; the hinge-line about equalling, or
sometimes a little greater than the width of the shell below.

Ventral valve varying from moderately convex to extremely gibbous or
ventricose ; the greatest elevation being in a vertical line from a point
just below the hinge-margin when the shell lies with the opening of
the valve downwards, leaving the longest curve of the outline between
this point and the front. The umbo is prominent, with the apex closely
incurved over the hinge-line. Between the umbo and the cardinal
angles the outline is abruptly sloping, or sometimes so depressed as to
leave a concave outline at the sides of the umbo. The ears are broad
and not strongly defined. In well-marked specimens there is a sinus,
which is wider and well-defined on the lower two-thirds of the valve,
and can be traced to the umbo.

Dorsal valve moderately concave, and marked by an elevation on the
lower half of its length, corresponding to the depression in the ventral
valve.

The surface of the ventral valve (judging from the casts) has been essen¬
tially free from striae, except the lines of growth. The ears are marked
by two or three of more wrinkles and as many spines, while the body
of the shell shows no indications of spines till we approach the margin,
where there are or two or three rows of scattered spiniferous tuber¬
cles. The dorsal valves examined are not in a condition to enable us
to determine whether fossets have existed, corresponding to the spines
of the ventral valve.

184

PALAEONTOLOGY OF NEW- YORK.

This species is quite distinct from any of those already described. In its mesial
sinus, it resembles the P. boydii; but it is usually a much more convex shell, and
in all the specimens has fewer spines on the ears, and none upon the middle of
the shell. The spines and spiniferous tubercles are likewise of a different charac¬
ter, while the form and expression of the shell is very different. Occurring only as
casts in sandstone, the entire characters cannot be ascertained.

Geological formation and locality. In sandstone of the age of the Chemung
group, at Meadville, Pennsylvania, associated with Spirifer disjunctus and other
fossils of the age of the Chemung group.

Productella oniista (n. s.).

PLATE XXVI.

Shell large, broadly semielliptical in outline, the length and breadth
about as four to five : hinge-line about equalling the width of the
shell, the convexity nearly hemispheric.

Ventral valve regularly convex, depressed-convex in the smaller indi¬
viduals and ventricose in the older ones, regularly rounded and curv¬
ing to the front and baso-lateral margins. Body of the shell abruptly
curving towards the umbo, which is elevated above the hinge-line,
and the apex closely incurved ; abruptly depressed, and concave be¬
tween the umbo and the cardinal extremities, which are produced in
ears comparatively wide, nearly flat, and usually a little rounded at
the extremities.

Dorsal valve broadly and deeply concave, corresponding to the ventral
valve, with the hinge-line comparatively a little shorter.

Surface of the ventral valve with obscure radiating and concentric strise
and a few wrinkles on the ears, which are partially extended to the
body of the shell. These wrinkles of the cardinal margins are studded
with the bases of slender spinesf and the entire surface is marked by
concentric rows of similar but smaller spiniferous tubercles. On the
shell, these rise almost directly from the surface without any elonga¬
tion ; but where the shell is exfoliated, the remaining pustules are
elongate.

The partially exfoliated ventral valve is peculiarly punctate or pitted,
as if by the most minute corrugation. The entire cast is puncto-striate,
presenting an unusual marking.

PRODU CTELLiE OF THE CHEMUNG GROUP.

185

The occlusor muscular impressions are well defined, semielliptical
and of moderate breadth, appearing to be duplicate ; the surface imme¬
diately below them is transversely corrugated over a small oval space.
The cardinal muscular impressions are wide and comparatively short,
flabelliform and deeply striated. The cast of the rostral cavity is grooved
on the upper side, and its extremity simple ; showing on each side, be¬
neath the apex, cavities made by the removal of the dental lamellae,
while the cardinal line presents no evidence of an area beyond the thick¬
ness of the shell.

The interior of the dorsal valve is papillose above, becoming papillose-
striate towards the margin. There is a slender mesial septum, which
becomes stronger above, and terminates in a short cardinal process : on
each side of this are slightly oblique socket-plates, and between these
and the hinge -line are narrow teeth-sockets. The cardinal process is
distinctly bilobed, and each division is slightly divided or grooved at
the extremity. The occlusor muscular impressions are small oval-ovate
spots, but are not well-preserved in any specimen seen, yet the reniform
vascular impressions are sometimes strongly marked. In addition to the
ordinary vascular impression, which terminates abruptly at some dis¬
tance from the median septum, there is sometimes another mark of
similar character beginning at a little distance within the termination
of the reniform impression, and curving forward to the termination of
the median septum, and thence recurving it terminates on the other
side in the same manner as it began, describing part of an elliptic curve.

This shell has a very symmetrical form, and is the largest among the species
of this subgenus. It is readily distinguished from all others by its regular wide
form and equal convexity, as well as by its distantly disposed and very slender
spines, by the peculiar punctate structure of the exfoliated shell, and the striato-
punctate surface of the cast.

The form and chai’acter of well-preserved" specimens are shown in figures 36, 37 and 38,
which give the outline, cardinal and profile views of a ventral valve. Figures 39 and 40
are cardinal views of the casts of ventral valves, showing the muscular impressions, and
one of them showing on eaqh side of the beak the cavities made by the dental lamellae.

Figures 30 and 31 are of the interior of two dorsal valves ; and figure 32 is a cardinal
view, showing the contour of the interior.

Geological formation and localities. This species occurs in the arenaceous and
semicalcareous beds at Conewango, at Napoli, and near New-Albion, Cattaraugus
county.

[ Palaeontology IV.]

24

im

PALAEONTOLOGY OF NEW-YORK.

CrEKUS &PIRIFERA (Sowerby).

The Genus Spirifera, established by Sowerby in 1815, embraces a very
natural group of shells, which are for the most part very readily distin¬
guished by their external form and characters. The presence of internal
spires is not alone sufficient to distinguish them, since these organs are
common to other very distinct genera.

The prevailing and characteristic form of the shells of this genus is
somewhat trigonal ; but they vary to subelliptical, ovoid and subcircular
in outline. The hinge-line may be shorter or longer than the greatest
width of the shell, and the cardinal extremities are sometimes obtusely
rounded, and often produced into wing-shaped extensions which termi¬
nate in acute points. The surface is smooth, or marked by radiating
costae, presenting a great variety of aspect and ornament ; and the centre
of the valves is usually marked by an elevated fold on the one valve,
with a corresponding sinus in the other : this feature, however, is
more or less obsolete in some of the species. The shell-structure is
fibrous.

The valves articulate by means of teeth and sockets. The beak of the
ventral or larger valve is more or less elevated above the other, and may
be straight or recurved. The area or space beneath the beak may be nar¬
row or large, flat or concave, or inclined forwards. This area is divi;
ded by a triangular fissure, which is often more or less closed in its
upper part by a pseudo-deltidium. In the dorsal valve the area is narrow,
usually linear, with a wide fissure, which is partially filled by the car¬
dinal process.

In the ventral valve the triangular fissure is bounded by vertical
shelly plates, which extend from the beak to the bottom of the valve,
and support, on each side at the base of the fissure, a short and usually
strong hinge-tooth. These fissure-walls are usually short diverging plates ;
but they are sometimes nearly parallel throughout their length, and reach
to the middle of the valve. They sometimes converge so as nearly to

GENUS SPIRIFERA.

coalesce, and again diverge, extending into the interior of the valve and
partially surrounding the muscular area. It often happens that the
pseudo-deltidium constitutes the exterior indication of the filling of the
rostral cavity ; and in old individuals, at least, this portion of the shell is
quite solid. The occlusor muscular impressions are usually marked upon
the inner surface of the shell, and upon the cast, by a mesial longitudinal
oval scar; while the divaricator muscular markings occupy a wider
space on each side, which is often deeply and beautifully striated. The
general interior surface, beyond the muscular impressions, is usually
nearly smooth, or marked by the impressions of the external costae. It
not unfrequently ‘occurs, however, that the papillose surfaces, indicating
the ovarian spaces, are strongly marked.

There is usually a slight median crest separating the muscular impres¬
sions; and in some species this becomes a distinct septum, reaching from
the base of the muscular area to the apex of the fissure, as seen in S. odo-
costata* (Pal. N. Y. Yol. iii, p. 205).

In the interior of the dorsal valve we have the distinct dental fossets
just without the deltoid fissure, which is limited by the bases of the
crura proceeding from the cardinal muscular process. The crura, converg¬
ing at a short distance from their bases, are bent backwards into the cavity
of the valve, and again recurved, making several turns, until they are
produced into two large conical spires which- nearly fill the interior of
the shell, the apices being directed towards the cardinal angles. The
double occlusor muscular markings are often well preserved in the cavity
of the valve and upon the cast of the interior. The impressions of the
divaricator muscles are marked upon the median cardinal process, or, in
the absence of a distinct process, upon the apex of the notch or upon
either side (See Plate 36).

Besides the forms referred to the Genus Spirifera proper, there are at
least three modifications of the type which are recognised by Mr. David-

* Mr. Davidson has regarded the presence of a septum dividing the muscular area as characteristic
of Spiriferina. In the example cited above, the shell is silicified, and it is not easy to decide positively
its texture, hut it appears to he fibrous. Should it prove to he punctate and a Spiriferina, it would
carry this genus hack to Silurian times.

188

PALAEONTOLOGY OF NEW- YORK.

son as subgenera : these are Spiriferina, Cyrt^ena and Suessia. Of the
first and last of these, we have no recognised species in our Devonian
rocks : the Genus Cyrta;na is recognised in two or more species.

The Genus or Subgenus Martinia was proposed by Prof. M£Coy to
include species of the type of Spirifera decora, S. elliptica, S. glabra, and
others of similar form, having a short hinge-line and rounded cardinal
extremities.* ** In the interior of some species of this type, I have recog¬
nized some peculiarities in the dental lamellae ; but the wafit of speci¬
mens for comparison leaves the question undetermined.

The Genus Amboccelia was proposed by me in 1360, for certain forms
having one valve flat or concave, and the other extremely convex. There
appear to me to be, in the typical species, some peculiarities in the mus¬
cular impressions, which I regard as of importance. The fibrous texture
of the shell exhibits some peculiarities ; but I find, that in this respect,
it corresponds with a small doubly convex form resembling S. lineata from
the Hamilton group. These forms will be noticed more at length after
the descriptions of Spirifera proper.

The following species are arranged upon the plates, as nearly as prac¬
ticable, in their geological order ; beginning with those of the Schoharie
grit, and ending with those of the Chemung group. Since many of the
species are common to the Schoharie grit and Corniferous limestone, and
few of the species pass into the succeeding formations, I shall follow the
apparent natural or chronological order in describing them.

* Mr. Davidson remarks, that “ Prof. M'Coy’s Genus Martinia was proposed for those species
“ in which the hinge-line was shorter than the width of the shell, and dorsal edges of the cardinal area
“ obtusely rounded with a smooth surface, and small spiral appendages; but the length of the hinge-

** line is so very variable, even in specimens of the same species, that on such a character it
“ seems very unsafe to found a genus. The species are also both smooth and plicated, and the
“ disposition of the spiral appendages does not appear to he distinguishable from that of other Spirifers.
“ It will, therefore, be preferable to postpone the adoption of the section Martinia, until some more
“ tangible differencee can be pointed out” (Introduction, p. 81, 1854). The same opinions are main¬
tained by Mr. Davidson in his later publications.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

18®

SPIRIFER^ OF THE UPPER HELDERBERG GROUP.

Spirifer duodenaria.

PLATE XXVII & XXVIII.

Delthyris duodenaria : Hall. Geol. Report 4th District New- York. p. 171, f. 5. 1848.

Spiriftr duodenaria : Hall, Catalogue in Report on State Cabinet.

Spirifera duodenaria. cited by Billings, Canadian Journal, p. 256. 1861.

(( “ Geology of Canada, p. 372. 1863.

Shell transverse, semicircular : hinge-line equalling the greatest width
of the shell ; cardinal extremities obtuse or acute, rarely acuminate.
Valves subequally convex; area very narrow. Surface plicated.
Ventral valve moderately gibbous, arcuate, compressed towards the
cardinal extremities. Mesial sinus of moderate width and depth,
rounded or slightly flattened on the bottom ; umbo prominent, the
beak small, neatly curved over a wide triangular fissure, and reach¬
ing to within half a line of the umbo of the opposite valve : area con¬
cave, sublinear, a little wider on each side near the centre.

Dorsal valve regularly convex, a little gibbous in the middle, and flat¬
tened or sometimes slightly concave at the cardinal extremities. Mesial
fold rather narrow, rounded, prominent and strongly defined, some¬
times a little flattened on the middle. The surface is marked by six
and rarely, seven strongly rounded ribs on each side of the mesial fold
and sinus. The ribs gradually decrease in size and prominence from
the centre, and the outer ones are often scarcely elevated in young or
medium-sized individuals.

The entire surface is marked by lamellose concentric striae, giving a
papillose or subfimbriate aspect at their junction. It usually happens,
however, that the surface is smooth from partial exfoliation.

In the Schoharie grit, the cast of the ventral valve shows a somewhat
narrow muscular area, with the sides subparallel for half their length
and contracting below. There are faint indications of a median crest.

In the interior of a ventral valve from' the Corniferous limestone,
Plate 28, fig. 23, the muscular area is broad and rounded, with a distinct

tm

PALAEONTOLOGY OP NEW-YORK.

median crest. A cast of the dorsal valve shows rather shallow teeth-
sockets, with a strong callosity between them and the fissure, while the
apex is marked by muscular impressions.

This species has ordinarily a width on the hinge-line of an inch to an inch
and a quarter, sometimes reaching an inch and a half ; with a length of about
three-fourths of an inch, and rarely of larger dimensions. It presents little variety
of form and proportions ; the younger individuals observed having three or four
ribs on each side of the mesial fold and sinus. The cardinal extremities are rarely
more extended than in the specimen figured.

In many of its features this species resembles the 8. cycloptera of the Lower
Helderberg group, but it is usually more extended on the hinge-line, with narrower
area and less conspicuous surface strife. In casts of the dorsal valve, however, the
two are scarcely distinguishable. It is of the type of 8. sjpeciosa of Schlotheim,
with a narrower area and more ribs than the Eif'el specimens, but corresponding-
in this respect to the English Devonian specimens figured by Mr. Davidson.

Geological formations and localities. This species begins its existence, so far
as at present known, in the Schoharie grit, in which it is common in the form of
casts throughout the eastern part of the State. In the Corniferous limestone, it is
known through all the extent of the formation within the State, and occurs in
Canada West, and in Ohio. It is unknown to me in the Hamilton group.

Spiiifera macra.

PLATE XXVII.

Spirifer macro. : Hall, Tenth Report on the State Cabinet, p. 134. 1857.

“ u New Species of Palaeozoic Fossils, p. 94. 1857.

Shell transverse, semielliptical, semicircular or subtriangular ; hinge¬
line equalling or greater than the width of the shell below, the cardi¬
nal extremities produced into mucronate extensions : valves unequally
convex.

Ventral valve more convex than the dorsal, gibbous, above the middle,
sometimes regularly convex or arcuate, but often less convex on the
lower half; compressed towards the cardinal extremities : mesial
sinus of moderate width, shallow, but sharply defined at the margins ;
beak much elevated and slightly incurved over the large fissure ; area
high, triangular, concave.

SPIRIFERiE OF THE UPPER IIELDERBERG GROUP.

191

Doesal valve convex, often somewhat flattened, particularly at the sides,
and becoming concave towards the cardinal extremities : mesial fold
prominent and strongly defined, often much expanded in front ; beak
small, little elevated, area linear.

Sueface marked by from ten to twenty slender well-defined plications
on each side of the mesial fold and sinus. In the youngest specimens
examined, there are no more than six or eight plications on either
side. The entire surface is marked by lamellose concentric striae, which
at intervals are crowded into imbricating lines of growth.

The casts of the ventral valve show the existence of strong short den¬
tal plates enclosing a comparatively narrow muscular area. In the middle
of this area, in well preserved specimens, are two narrow and much
elongated occlusor impressions, with a slight crest between ; but these
features are often entirely absent or obsolete. Tli3 casts of the dorsal
valve show large teeth-sockets, and a distinct prominence in the centre
for the muscular attachment.

This species has the general aspect of S. mucronatct , but the plications are a
little more prominent, and the concentric stria? less strongly imbricating : the
principal point of difference, however, is in the elevated and incurved area of the
ventral valve.

The specimens from which the original description was made, were casts of
small and poorly preserved individuals ; but a larger and more extended collec¬
tion has shown all the gradations of form, size and condition illustrated on Plate
27, figure 17 being one of the smaller symmetrical specimens. Individuals from
the Schoharie grit, and from the limestone, often present considerable differences
in the relative convexity of the- valves ; and the area, either from compression or
other causes, shows some apparent variations in its height, as seen in figures 21
and 28, plate 27. In all cases, however, the height of the area is a distinguishing
feature. The casts in the Schoharie grit are usually very imperfect and unsatis¬
factory. The illustrations figures 22, 23 and 24, are from some of the better pre¬
served specimens.

Geological formations and localities. This species occurs in the Schoharie grit
in the Helclerberg mountains, Albany county, and at Schoharie ; and rarely in
the Corniferous limestone in tho eastern part of the State. It is not uncommon in
the Corniferous limestone at Williamsville and other places in the western part
of the State, and I have a single specimen from Ohio. Its associates in the Scho¬
harie grit are the S. duodenaria and S. raricosta .

192

PALAEONTOLOGY OP NEW-YORK.

Spiilfera raricosta.

PLATE XXYII & PLATE XXX.'

Delthyris raricosta : Conkad, Journ. Acad. Nat. Sci. of Philadelphia, Yol. viii, p. 262, pi. 14, f. 18. 1842.
Dellhyris undulatus : Vanuxem, Geol. Report Third District New-York, p. 132, f. 3. 1842.

Shell subquadrate, semicircular or ovate, gibbous : hinge-line equalling
the width of the shell or often less ; cardinal extremities rounded.
Surface strongly plicated.

Ventral valve most gibbous in the upper half, and sloping abruptly to
the cardinal angles, which are rarely a little extended and subauricu-
late : beak much elevated, and always incurved over the area which
is variable in elevation, sometimes being barely perceptible, while
in others it has a width of from one to two lines, and is marked lon¬
gitudinally by a few strong striae. The mesial sinus is a broad rounded
depression, and reaches with the adjacent plications quite to the apex.
Dorsal valve gibbous, most convex in the middle, flattened or a little
concave towards the cardinal angles. The mesial fold is very promi¬
nent and rounded or a little flattened in the middle, regularly arcuate,
and forming the small beak which is arched over the linear area.
Surface marked by two to four strongly elevated rounded or subangular
ribs on each side of the mesial fold and sinus. In one specimen, I have
seen a fifth plication towards the cardinal angle. The entire shell is
covered by strong lamellose or imbricating concentric striae, which
are undulated upon the ribs and the intermediate depressions. These
concentric lines are sometimes quite regularly equidistant, but often
crowded and irregular in their distribution, and more or less promi¬
nent at their edges. There are a series of fine closely arranged radia¬
ting striae crossing the concentric lamellae, and giving in very perfect
shells a fimbriate aspect.

The surface is usually more or less worn, and only the stronger con¬
centric lamellae are visible ; and even these are often partially or entirely
obliterated. In some specimens, where the. shell is well preserved, the
plications are rounded and not very prominent ;• while they become more

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

193

distinct, with a subnodose character, on the exfoliation of the shell. The
mesial sinus, is usually very wide at its base, sometimes equal to half
the length of the shell.

The proportions of the shell are extremely variable, the length being
sometimes greater than the width, while usually the width is somewhat
greater than the length ; and in some individuals the length and breadth
are as two to three.

The casts of the ventral valve show a small rostral cavity with short
strong dental plates ; the muscular area being small, quadrangular, and
divided through the middle by a distinct septum.

The interior of the shell of the ventral valve shows short strong hinge-
teeth and very short incurving plates below, while the bottom of the
cavity is divided by a distinct elevated septum.

The dorsal cast shows marks of dental sockets, with strong muscular
markings at the apex of the fissure.

This species is nearly allied with S . joerlamellosa of the Lower Helderberg
group, and is not always readily distinguished from that one. It is, however
usually proportionally shorter on the hinge-line, and more quadrate in form,
while it is not known to have as many plications as the older species.

The dimensions vary from half an inch in length and breadth, to an inch and
a half in length and breadth ; while other specimens are an inch and a half in
width by an inch in length.

This species is not common in the rocks of New York, though having a pretty
wide distribution.

Geological formations, and localities. This shell occurs at the Helderberg
mountains and Schoharie, in the Schoharie grit ; and in the same region, in the
Corniferous limestone. It is known in the latter rock at Stafford, Caledonia, Wil-
liamsville in Western New- York ; Columbus, Ohio ; Falls of the Ohio river ; and
in several localities in Canada West.

[ Paleontology. IV.]

25

194

PALAEONTOLOGY OF NEW-YORK.

Spirifera grieri.

PLATE XXYII & PLATE XXYIII.

Spirifer grieri : Hall, in Tenth Report on the State Cabinet, p. 127. 1857.

“ 1 New Species of Palaeozoic Fossils, p 87. 1857.

Shell gibbous, transversely oval or subquadrilateral, sometimes longitu
dinally ovate, the proportions of length and breadth being very varia¬
ble ; hinge-line usually shorter than the width of the shell, with the
cardinal extremities rounded : valves subequally convex.

Ventral valve gibbous or ventricose, most convex above the middle and
nearly opposite the center of the hinge-line, and sloping very abruptly
to the lateral margins; sometimes regularly arcuate in the entire
length, and often arched in the upper part and nearly straight below.
Umbo prominent and much elevated above the hinge-line : beak more
or less extremely incurved over the high arcuate area, which has a
length of from one-half to nearly two-thirds the width of the shell ;
mesial sinus wide and deep, subangular in the lower part.

Dorsal valve regularly arcuate, the greatest convexity near the middle
and regularly curving to the lateral margins : mesial fold prominent,
sometimes rounded, but usually more or less distinctly angular ; beak
small, slightly incurved over a nearly vertical narrow area.

Surface marked by six, eight or ten more or less rounded simple plica¬
tions on each side of the mesial fold and sinus ; while there are three
or four distinctly bifurcating or dichotomous plications upon the fold
or sinus, giving six or seven at the margin of the shell. In perfect
specimens, the surface is covered .by fine concentric lamellose striae,
which are crossed by delicate radiating striae.

This species is distinguished from most of the allied forms by its simple strong
plications on each side of the mesial fold and sinus, while those occupying the
latter are smaller and bifurcating. Sometimes the middle plication on the summit
of the mesial fold is simple, in which case the fold is quite angular ; while in
other instances it bifurcates, leaving a longitudinal depressed line on the middle,
giving it a more rounded outline. It is only on specimens which have suffered no
injury by wearing or exfoliation, that the fimbriate appearance of the concentric
markings is visible.

SPIRIFER.ZE OF THE UPPER HELDERBERG GROUP.

195

In some of the larger or older individuals, the plications are low and gently
rounded : in other specimens they are more prominent, while from exfoliation they
often become angular and more conspicuous ; and the same appears to be true of
the dichotomous plications of the mesial fold and sinus. In two or three instances,
I have noticed in the casts a partial bifurcation of one or two of the lateral plicae
turns. In some of the casts, or partial casts, the plications on the fold or sinus
appear to be partly or entirely obsolete. The interior of the valves is unknown.

The specimens before me vary from less than three-fourths of an inch in height
and width, to an inch high by an inch or an inch and a half wide. I have seen a
single specimen two inches wide, and another of more than an inch and a half in
height and width. The illustrations, from figure 17 to figure 23 on plate 28, are
of the prevailing forms observed. Figure 29, plate 27, is of a cast from the Scho¬
harie grit.

Geological. formations and localities. This shell occurs rarely in the Schoharie
grit in the eastern part of the State, and in the Corniferous limestone at Clarence
and Williams ville in the western part of the State. I have seen a specimen from
Canada West, and it is known to occur at Sandusky and Columbus, Ohio ; while
the better specimens have been obtained from the neighborhood of Dayton, Ohio,
and were given me by Judge Grier of that place.

Spirifera gregaria.

PLATE XXVIII.

Spiri/er gregaria : Clapp, MS.

“ “ Hill, in Tenth Report on the State Cabinet, p. 127. 1857.

Spirifera gregaria : Clapp, Billings in Canadian Journal, p. 128. 1857.

Shell ventricose, subglobose, semioval or subquadrate in outline : hinge¬
line equalling or less than the width of the shell ; cardinal extremities
truncate or rounded. Surface plicated.

Ventral valve the more gibbous, regularly arcuate from beak to front,
the greatest convexity at or a little above the middle, and curving
somewhat abruptly to the sides and more gently to the front : beak
much elevated, and the apex closely incurved over the fissure ; area
high, concave, and extending to the cardinal angles, where it is some¬
times more than half a line high, often distinctly striated; mesial
sinus rounded or subangular, and much produced in front.

L orsal valve very convex, with a strong mesial fold, either angular or
somewhat flattened along the summit, and sometimes marked by an

196

PALAEONTOLOGY OP NEW-YORK.

indistinct groove : beak often considerably elevated and slightly incli¬
ned over the hinge-line ; area narrow except in the centre, where it
perceptibly widens.

Surface marked by from six to ten strong rounded ribs on each side of
the mesial fold and sinus ; the entire surface with undulating concentric
striae, which, towards the front, become strong zigzag imbricating
lines.

The interior of the ventral valve presents a well-defined oval muscular
impression with a low crest in the centre. The dental plates are often
much thickened, filling the entire rostral cavity and encroaching upon
the muscular area.

The width of the species ranges from one-half to seven-eighths of an inch, and
the length is sometimes a little greater but usually a little less than the width. In
the more gibbous specimens, the beak of the ventral valve is so extremely eleva¬
ted that one-half the length of the valve is above the cardinal line. In the majority
of specimens, there are about six or seven plications on each side of the valve.
The variable gibbosity of the shell gives an apparent variation in the height of the
area, the beaks of the two valves sometimes approaching close to each other.

Some silicified casts of specimens from Indiana, which I have referred with hesi¬
tation to this species, have a very symmetrical form : the beak of the ventral valve
is moderately elevated ; while the mesial fold is marked by a distinct longitudinal
groove, and there is a distinct angular elevation in the bottom of the sinus. The
specimens are extremely abundant in a mass of rock associated with Strophodonta
per plana ; and in their mode of occurrence have all the appearance of the species
as it is found near Louisville, Kentucky.

Geological formation and locality. This species occurs rarely in Upper Hel-
derberg limestone, in Eastern New York, and becomes common in Genesee and
Erie counties. It occurs at several localities in Ohio, and at the Falls of the Ohio,
both in Indiana and Kentucky. This species has been found in Canada West, and
has been described by Mr. Billings among the Devonian fossils from that regipn.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

197

Spirifera oweni.

PLATE XXIX.

Spiri/er oweni : Hall, in Tenth Report on the State Cabinet, p. 129. 1859
“ “ Description of New Pal. Fossils, p. 89. 1857.

Shell more or less ventricose in its different stages of growth, somewhat
transversely oval, semielliptical or subquadrate : hinge-line about
equal to the width of the shell ; cardinal extremities rounded or sub-
angulated. Surface plicated.

Ventral valve scarcely so gibbous as the dorsal valve, its greatest con¬
vexity above the middle of its length, and curving regularly to the
margins : beak much elevated above that of the opposite valve, and
arching over the fissure, but scarcely incurved ; mesial sinus shallow,
concave, usually well defined and reaching distinctly to the apex. Area
high, concave, elevated and continuing to the hinge-extremities ; fora¬
men large, reaching to the apex, and sometimes partially filled by the
thickening of the dental plates.

Dorsal valve the more gibbous, the greatest convexity in the middle,
and curving regularly to the front and lateral margins, and usually a
little flattened or sometimes concave towards the cardinal extremities :
mesial fold prominent, rounded, with a longitudinal depressed line
along the middle. Area narrow, vertical or in the plane of the longi¬
tudinal axis.

The surface is marked by from fifteen to seventeen rounded or suban-
gular plications on each side of the mesial fold and sinus ; and these are
crossed by distinct concentric striae, which become strongly imbricating,
or are marked in strong imbricating lines of growth towards the margin.
In well preserved specimens, there are distinct radiating striae. In many
of the silicified specimens, however, both the radiating and concentric
striae are partially or entirely obliterated.

The interior of the ventral valve shows two short and rather strong
teeth, with the rostral portion quite solid. The dental plates, reaching
to the bottom of the cavity of the shell, curve slightly outwards and

PALAEONTOLOGY OP NEW- YORK.

198

partially enclose an oval muscular area, which in its upper part is divi¬
ded by a short prominent median crest. In some silicified specimens, the
conical spires are partially preserved. The crura are widely separated at
their bases, and, converging somewhat abruptly, curve into the dorsal
valve, making twelve or more turns, and producing a short strong spire.

In well preserved specimens, the mesial fold and sinus are usually
sharply defined ; but in some of the more gibbous forms, the sinus is
very broad, and one or two. of the plications on each side are involved
in the sides of the depression : at the same time the mesial fold is very
prominent, rounded, and sloping almost imperceptibly into the general
contour of the convexity of the valve.

This species is abundant in the neighborhood of Louisville and other western
localities. It has generally been referred to S. Icevicosta , Lamarck sp. ( Terebra -
tulites ostiolatus , Sciilotheim), from which it differs in being less gibbous with a
greater number of plications, and in having a depressed line along the mesial fold
of the dorsal valve. It may be easily distinguished from S. euruteines of Owen,
with which it is associated, by its narrower and much more arcuate area and less
angular plications. Some specimens show remains of a faint impressed line along
the centre of each plication.

Geological formations and localities. Limestone of the age of the Upper Hel-
derberg : Falls of the Ohio, Charleston landing and other places.

Spirifera acuminata.

PLATE XXIX.

Delthyris acuminata : Conrad, Annual Report of the Palaeontology of New York, p. 65., 1839.

Spirifer acuminutus .• (Conrad,) Hall in Tenth Report on the State Cabinet, p. 135, 1857.

Compare Spirifer cultrijvgatus, R<emer in Das Rhenische Uebergangsgebirge, p. 76. pi. iv, f. 4, a, b,c. 1844
Also ? Spirifer cultrijvgatus : (RceSier) Schnur Palseontographica, Vol. iii, pi. xxiii, f. 1.

“ (Rcemer) Davidson’s Monograph of British Devonian Brachiophoda, p. 35.

Also Delthyris prora : Conrad, Jour. Acad. Nat. Sci. Philadelphia, Vol. viii, p. 263. 1842.

“ D. acuminata. Shell subcordate, dilated transversely ; valves with [radiating
“ sulci : superior valve very prominent and carinate d in the middle ; carina
“ not sulcated, slightly arcuate in length ; lateral extremities rounded ; base
“ emarginate ; inferior valve profoundly bilobed ; sulci not deeply impressed ;
“ beak approximate. Length 2\ inches. Locality : Helderberg, in limestone.
“ It resembles Atrypa acuminata (Sowerby).

SPIRIFER2E OF THE UPPER HELDERBERG GROUP.

199

Shell large, ventricose, transverse, with the hinge-line usually less than
the width of the shell ; cardinal extremities rounded or truncate, hav¬
ing a subelliptical or subquadrate outline ; mesial fold and sinus ex¬
treme. Surface plicated.

Ventral valve variably convex on the two sides, with a wide mesial
sinus, which is well defined in the upper part, becomes wider and
deeper and less distinctly defined in the middle of the shell, and is
produced in front into a long triangular extension ; gently or more
abruptly curving from the greatest convexity to the sides and cardinal
angles : umbo prominent, with the apex incurved over the wide tri¬
angular fissure ; area extending to the cardinal angles, with the mar¬
gin rounded except towards the extremities.

Dorsal valve gibbous, highly elevated in the middle into a strong angu¬
lar mesial fold, and curving from the sides of the fold to the margins
of the shell, except at the cardinal angles, where it is a little flattened
and projecting, so as to give a minute auriculate appearance; summit
of the mesial fold regularly arcuate from beak to base ; apex slightly
incurved over the narrow nearly vertical area.

Surface, on either side of the mesial fold and sinus, marked by from
sixteen to twenty plications, about four or five of which nearest the
centre are dichotomous from below the middle of their length ; ribs
low, and rounded above, flattened below the middle, those towards the
margin very slender : the first ten or twelve ribs on each side occupy
the greater part of the valve. The entire surface is marked by delicate
concentric striae, which are often crowded into imbricating lamellose
lines towards the front of the shell. In very perfect specimens, these
concentric striae are papillose Or fimbriated by fine radiating striae.
These fine surface markings, however, are usually nearly or quite
obliterated.

The interior of a ventral valve shows but a partial thickening of the
shell in the rostral cavity : the teeth are strong and short; the dental
plates spreading and margining the upper part of the ovate muscular

PALAEONTOLOGY OF NEW-YORK.

area, which is broader above, and sometimes very much resembles this
feature in S. striatus.

The casts preserve strong and prominent marks of the muscular im¬
pressions, and sometimes vascular markings outside of the muscular
area ; while in other individuals, the papillose ovarian markings are
very distinctly preserved. In the cast of the dorsal valve there are some¬
times strong impressions of the occlusor muscular markings, and the
apex also shows the striae of the cardinal muscular attachment.

It does not appear, from Mr. Conrad’s description, that he recognized
the dichotomous ribs; but this feature is often obscure or scarcely recog¬
nizable in the specimens from the Corniferous limestone in New York,
owing to partial exfoliation or other causes ; and in most of the smaller
specimens^it does not exist, the division usually taking place below
the middle of the length. In full grown individuals, when the surface is
pretty well preserved, the duplicate character of the plications is a con¬
spicuous feature. Somewhat rarely we observe a partial division of one
or more of the plications on different parts of the shell towards the
margin.

A Spirifer in the Hamilton group, which I have identified as the
Delthyris pr or a of Conrad, is clearly identical with this one of the Corni¬
ferous limestone. The dichotomous character of the ribs, however, is
more conspicuous, and the division often begins above the middle of the
shell (See fig. 24, pi. 34), and becomes a conspicuous feature in specimens
of medium size ; while in those of similar dimensions from the Cornife¬
rous limestone, this character is scarcely perceptible.

This species is readily distinguished from all the other Spirifera in our strata,
by the extremely elevated angular mesial fold and deep sinus, which are bounded
by the dichotomous plications. In an imperfect condition, it might be sometimes
mistaken for 8. macrothyris , which, in its hinge-area and the upper part of the
mesial fold, sometimes simulates the 8. acuminatus.

The young of this species are but moderately convex, with a broad depression
in front, as shown in fig. 9, pi. 29. From this condition, there are all degrees of
variation to the more ventricose and extreme forms as shown in figs. 12, 13 and
14, of Plate 29.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

201

The casts show considerable variation in the form and proportions of the mus¬
cular area, two examples of which are shown in figures 15 and 16, Plate 29.

The cast of a ventral valve, Plate 34, figure 25, illustrates the character of a
well-preserved specimen from the Hamilton group.

This species has been recognised by Dr. F. Rcemer and M. de Verneuil as
identical with the 8. cultrijugata of Europe. Without the means of comparing spe¬
cimens, I had supposed the American and European species to be identical ;
but Mr. Davidson has recently called attention to the existence of bifurcating ribs
in the American species, while “ in all the figures published by Rcemer, Schnur,
“ and Sandberger of 8. cultrijugatus , the ribs on the lateral portions of the shell
“ are simple, and do not exceed about twenty on each valve ; but in a specimen so
“ named in my possession from the Falls of the Ohio near Louisville, in America,
“ and which I received likewise some years ago from Herr F. Rcemer, the ribs are
“ small, and in some places bifurcated, and numbering about twenty-four in each
“ valve.”

The original figures of Dr. Rcemer represent the species with simple strong
rounded ribs on each side of the mesial fold and sinus ; while the elevation in
front is triangular as in our specimens. In the figures of Schnur,* the sinus in
front is not triangular, but the sides approach to parallel, and the summit is
arched rather than angular. It appears to me, however, that M. Schnur has indi¬
cated something like a bifurcation, or a depression along the centre of the larger
plications, in figures 1 a, b ; though it must be confessed that the general expres¬
sion of the figures is somewhat different from our shell. The figures given by Mr.
Davidson (loc. cit.), and referred with doubt to this species, have “six or seven
“ strong simple ribs on each of the lateral portions of the valve.” This feature
would preclude its association with our specimens, and indicates a nearer approach
to some of the forms which I have referred to 8. macroihyris.

Mr. Conrad has given the length of 8. acwninatus as inches. The specimens
before me vary from one inch to two and a quarter inches in width, and from
three-fourths of an inch to an inch and seven-eighths in length.

Geological formations and localities. This species is not known below the Cor-
niferous limestone, where it has been found in Albany and Schoharie counties, as
well as at several localities in the central part of the State, and at Williamsville
and Clarence-hollow in the western part of the State. It occurs in the same forma¬
tion at Sandusky and Columbus, Ohio ; at the Falls of the Ohio both in Louisville
and Jeffersonville, and at Camp creek, Indiana. It is found in the Hamilton group

* Palaeontographica, T. iii, pi. xxxiii, f. 1, a, b, c.

[ Paleontology IV.]

26

202

PALAEONTOLOGY OF NEW- YORK

in Schoharie and at Hamilton, Cazenovia and Madison ( Madison county) ; but is
unknown in this formation in the western part of the State. There is a cast of this
species in- the cabinet of Marietta College, Ohio, which, I infer from its character,
has been derived from the southwestern extension of the Hamilton group, perhaps
in Virginia.

Spirifera macrothyris.

PLATE XXX.

Spirifer macrothyris : Hall, Tenth Report on State Cabinet, p. 132. 1857.

“ “ Description of New Pal. Fossils, p. 92. 1857.

Shell large, moderately gibbous, transverse, semielliptical, the width a
little more or less than twice the length : hinge-line equal to the
greatest width of the shell ; cardinal extremities rounded or angular,
and produced. Surface plicated.

Ventral valve less gibbous than the dorsal, regularly arcuate from front
to beak, and curving gently to the lateral and cardinal margins : sinus
well defined above, and reaching to the small and neatly incurved
beak, becoming wider and deeper below and much extended in front.
Area concave, of moderate width, and extended to the cardinal extre¬
mities ; margin angular : fissure very large.

Dorsal valve the more convex, the greatest convexity about the middle
of its length : mesial fold prominent, angular in its upper part and
rounded towards the front, giving a highly arcuate outline to the mar¬
gin ; umbo much elevated and rising nearly as high as that of the
opposite valve ; beak incurved over the nearly vertical area, which is
about a line in width.

The surface is marked by about ten or twelve strong low rounded pli¬
cations on each side, which are simple from their origin, becoming less
prominent towards the margin of the shell : the first five or six on each
side of the fold and sinus occupy the greater part of the anterior margin.
In well preserved specimens the surface is marked by fine closely
arranged concentric striae, which are finely papillose from radiating
striae. The cast of the ventral valve presents a large ovate bilobed mus¬
cular impression.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

203

This is a fine robust species, of which I have before me a dozen specimens in
various states of preservation, and presenting, in some respects, variations which
make me hesitate in referring them all to the same. In some which appear to be
well preserved, the area is comparatively narrow, while in others it has a pro¬
portionally greater width. The plications also appear to be of variable strength,
and in some of the casts are much stronger than in the shells. In the larger indi¬
viduals, the general characters are strongly defined, as shown in figures 16, 17
and 18, Plate 30 ; while the individual figure 19 was for a long time placed among
specimens of 8. acuminata , owing to its prominent angular mesial fold, and form
of area, which correspond to that species ; but in the curved instead of angular
sinus in front, and in the -details of the plications, the two are quite distinct. In
the more minute surface markings, the concentric striae of 8. acuminata are
coarser, and the radiating striae more frequently interrupted ; but this feature may
not prove constant. In its entire form and full proportions it is not likely to be
confounded with any other species of the higher formations.

In some of the casts of this species, we have very nearly the characters repre¬
sented in the figures of 8. cultrijugata given by Mr. Davidson,* except that the
area is not so elevated in the middle.

Geological formation and localities. This species occurs in the Corniferous or
Upper Helderberg limestone at Williamsville and Clarence-hollow, New- York ;
and near Columbus, Ohio.f It is unknown to me in the eastern part of the State of
New York.

Spirifera uniea (n. s.).

PLATE XXX.

Shell semielliptical ; length and breadth about as seven to ten. Surface
.finely plicated.

Ventral valve moderately gibbous, with a broad deep sinus which is
undefined at its margins ; umbo prominent, much elevated above the
hinge-line, with the beak extremely incurved : outline curving gently
from the umbo to the front, and more abruptly to the lateral margins,
being concave between the umbo and the cardinal extremities. Area
rather low, concave, and scarcely extending to the cardinal angles.

* Monograph of British Devonian Brachiopoda. Plate viii.
t Specimens were obtained from Dr. R. P. Mann, of Milford, Ohio.

204

PALAEONTOLOGY OF NEW-YORK.

The surface is marked by about twenty or twenty-one somewhat slen¬
der low rounded simple plications on either side ; while the mesial fold
has seven or eight plications in its upper part, which bifurcate, and
become twelve or fourteen at the anterior margin. The entire surface is
marked by fine radiating striae, and imbricating lines of growth near the
margin.

This species has been observed only in a single imperfect ventral valve ; but
its characters, in the individual, are quite distinct from any other species in this
formation ; the lateral plications are more numerous than in any other, with a low
strea, while the bifurcating plications of the sinus furnish ready means of distin¬
guishing it from any other except the iS. arenosci , which has a much more shallow
sinus with less elevated beak and broader umbo. The plications are likewise more
slender than those of that speciesdn the Oriskany sandstone, and the surface is
marked by fine radiating striae, a feature which I have not observed in that one.

This species differs from S . divaricata (which has likewise plications in the sinus)
in the general contour of the shell, the deeper sinus and the simple plications on
the lateral portions of the shell, as well as the more minute surface marking,
which is quite distinctive.

Geological formation and locality. In the Corniferous limestone, near Clarence
hollow, Erie county, New-York.

Spirifera disparilis.

PLATE XXX.

Spirifer disparilis ; Hall, Tenth Report on the State Cabinet, p.134. 1857.

“ “ Description of New Species Pal. Fossils, p. 94. 1857.

Shell small, somewhat semielliptical ; length and breadth about as two
to three or three to four : hinge-line a little less than the greatest
width of the shell ; cardinal extremities rounded.

Ventral valve gibbous, extremely elevated towards the umbo, abruptly
curving to the front, and sloping in a nearly straight or slightly
concave line to the cardinal extremities : sinus deep and angular ;
beak extremely elevated, and abruptly incurved over the high nar¬
row fissure. Area high, triangular; margin rounded, the width about
twice the height.

SPIRIFERJE OF THE UPPER HELDERBERG GROUP. 205

Dorsal valve moderately convex or nearly flat, with beak little elevated
and not incurved : area narrow and straight ; mesial fold smaller than
the adjacent plications.

The surface is marked by five or six obtusely subangular plications on
the ventral valve, there being sometimes an unequal number on the two
sides. The plications of the dorsal valve are broader and rounded, not
reaching to the apex ; the mesial fold being smaller than the adjacent
plications, depressed below their plane, and the sinus on each side wider
than the fold itself. The plications on each side of the sinus of the ven¬
tral valve are much stronger than the others, and reach to the beak,
while the others do not. The finer surface markings are unknown, all
the specimens seen having been exfoliated.

This species is readily distinguished from all the others in our strata, by the
extreme disparity of the valves, and the broad and short plications, while at the
same time it has not the characters of Cyrtina.

The figures of this species are enlarged to two diameters.

Geological formation and locality. This species is only known to me in the
Corniferous limestone in the neighborhood of Williamsville and Clarence-hollow,
Erie county, New-York.

Spirifera varicosa.

PLATE XXX.

Spirifer varicosus : Hail, Tenth Report on the State Cabinet, p. 130. 1857.

“ “ Description of New Pal. Fossils, p. 90. 1857.

Shell somewhat semicircular or semielleptical ; length equalling or less
than half the width : hinge-line equal to the greatest width of the
shell, and terminating in salient angles or mucronate extensions. Sur¬
face plicated.

Ventral valve much the more convex; greatest elevation at the umbo,
and regularly curving to the front and lateral margins : mesial sinus
strongly defined, rather flat in the bottom ; beak slightly arcuate. Area
high, nearly flat below and slightly concave towards the apex.

Dorsal valve moderately convex, with a prominent abruptly elevated
mesial fold, which is flattened on the summit and sometimes slightly

206

PALEONTOLOGY OF NEW-YORK.

depressed along the centre ; the beak projecting a little above the

hinge-line, and with a narrow area gently incurved.

The surface is marked by from eight to ten simple and somewhat
abruptly elevated plications on each side of the mesial fold and sinus :
these are crossed by strong lamellose imbricating lines of growth, which
give a varicose character to the surface, and where the shell is exfolia¬
ted the plications are nodose.

In some specimens, distinct fine radiating striae can be observed.
There is often a retral curving of the concentric striae in the centre of
the mesial sinus, and sometimes a slight elevation along that line.

The original specimens of this species were obtained from a western locality ;
but there are forms in Western New-York, which, though differing slightly from
the originals, seem nevertheless referable to the same species.

,In comparing this with other generally similar forms, I remarked in my original
description that this species differs from 8. euruteines of Owen, in being smaller
and more transverse, with more angular plications and stronger concentric lines of
growth ; also, in the greater prominence of the two plications bounding the
sinus, as well as the abrupt and angular mesial fold. It differs from 8. segmenta in
its fewer and more rugose plications, as well as in the more abrupt mesial sinus,
and in the inclination of the area.

The figures 1-4, Plate 31, are of typical forms of this species, of which I have
more than a dozen individuals before me, all preserving the same characters with¬
out material variation.

Geological formation and locality . In limestone of the age of the Upper Hel-
derberg limestone at Charleston landing, Indiana ; at Williamsville, etc., New-
York.

Spirifera varicosa, var.

PLATE XXXI.

Shell having the general characters of S. varicosa, but larger and more
gibbous ; area higher, but similarly arcuate in the upper part. There
are ten or more plications on each side, which are rugose from strong
imbricating lamellae, and become somewhat nodose on partial or entire
exfoliation. Unfortunately only a few specimens of this variety have
been seen in New-York.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

Figure 23, Plate 31, illustrates the ventral valve of an individual of this spe¬
cies. From the conditions of preservation, it does not represent the full length of
the valve in proportion to the width. Mr. Billings has recognized a similar form
in Canada West, which he compares with S. mucronata. Our specimens are very
unlike $. mucronata.

Geological foi'mation and locality. In the Upper Helderberg (Corniferous)
limestone, near Williamsville, New-York.

Spirifera segmenta.

PLATE XXXI.

Spiri/er se> mentus : Hall in Tenth Report on the State Cabinet, p. 131. 1857.

“ “ Description of'New Pal. Fossils, p. 91. 1857.

Shell transverse, semioval ; length less than half the width : hinge-line
equalling the greatest width of the shell, and terminating in salient
angles. Surface plicate.

Y entral valve much elevated, subpyramidal, most prominent at the
beak, which is not incurved : sinus strongly defined, shallow and
nearly flat in the bottom, with the sides straight, giving a triangular
form, in which the sides are about once and a half as long as the base.
Area very large with sharply angular margins, a little inclined for¬
ward, and nearly of the same size as the exterior of the valve : the
fissure is high and large, being nearly of the same dimensions as the
mesial sinus.

Dorsal valve depressed convex, and flattened towards the cardinal extre¬
mities, larger than the ventral valve, semielliptical in form, with a
low but sharply defined mesial fold which is barely flattened upon the
summit. The proportions in height of area, length of dorsal and length
of ventral valves, is about as five, six and seven.

Surface marked by twenty or more simple rounded (or subangular) pli¬
cations on each side of the mesial fold and sinus, the lateral ones of
which do not reach the beak, but run out along the margin of tl: ®

In its perfect condition the shell has been marked by- fine concentric
striae, traces of which are still preserved, together with stronger imbri¬
cating lines of growth.

208

PALAEONTOLOGY OF NEW-YORK.

This species is associated with 8. varicosa ; but may be distinguished from that
one by the more numerous and smoother plications ; a more depressed, smooth
and rounded mesial sinus ; the anterior inclination of the area, and the propor¬
tionally greater length of the ventral valve, (which is a little greater than the dorsal
valve in that species,) and much greater than the height of the area.

It also bears some resemblance to 8. eurut&ines of Owen ; but in that one the
area is vertical and considerably less in height than the length of the ventral valve,
and the latter is longer than the dorsal valve ; and although a smaller shell, the
8. segmenta has more numerous plications than 8. euruteines. Its nearest analogue
is the 8. angusta of the Hamilton group.

The figures 5, 6, 7 and 8, Plate 31, illustrate the form and proportions of this
species : the cardinal extremities have been broken off.

Geological formation and locality. In limestone of the age of the Upper Hel-
derberg, at the Falls of the Ohio, and at Charleston landing, Indiana.

Spirifera arctisegmenta.

PLATE XXXI.

Spirifer arctisegmentus : Hall, Tenth Report on the State Cabinet, p. 131. 1857.

“ “ Description of New Pal. Fossils, p. 91. 1857.

Shell transversely semioval ; length less than one-third the width :
hinge-line equal to the greatest width of the shell, and terminating in
mucronate points.

Ventral valve the more convex, most prominent at the umbo, from
which it slopes regularly to the anterior and lateral margins : mesial
sinus angular, and distinctly defined quite to the apex of the shell ;
beak not incurved. Area flat, a little inclined forwards, striated longi¬
tudinally ; fissure narrow and open to the apex.

Dorsal valve depressed convex, scarcely flattened towards the cardinal
extremities : the beak and central portion of the shell, together with
the linear area, slightly incurved.

The surface of the ventral valve is marked by eight or nine angular
plications, which are slightly curved towards the front, and about three
of them only reaching the apex ; the remainder coalesce with an eleva¬
ted ridge which borders the area. The plications on the dorsal valve are
pretty direct, the greater part of them terminating in the margin at a

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

209

distance from the beak. Fine close concentric undulating striae mark
the entire surface.

This shell may be distinguished from the last, as well as from other somewhat
allied forms, b}^ its larger and more anguM* as well as less numerous plications,
and in having a distinct linear ridge along the margin of the area of the ventral
valve : its foramen is likewise narrower, and the sinus deeper and more angular
than in S. segmenta.

The individuals observed are too few to determine what changes may supervene
from age and surrounding conditions ; but with our present knowledge, it cannot
be united with any other similar form described.

Figures 9 and 10, Plate 31, are illustrations of the original specimen described.

Geological formation and localities. In limestone of the age of the Upper Hel-
derberg group, at Stafford, Genesee county ; and at Shortsville, Ontario county,
New-York.

Spirifera ciiruteines.

PLATE XXXI.

Delthyris ( Spirifer ) euruteines : Owen, in Report of Geological Explorations in Iowa, Wisconsin and
Illinois for 1859,* p. 74, f. 9, Plate 12.

Spirifer euruteines : Owen, Geological Survey of Wisconsin, Iowa and Minnesota, p. 586,Tab.iii (exclu¬
ding figures 2 and 2 a), figures 6, 6 a, b.

Shell semielliptical ; length and breadth about as six to ten : hinge-line
equal to the greatest width of the shell. Surface plicate.

Ventral valve subpyramidal, the elevation being nearly equal to half
the width, curving abruptly and equally to the front and lateral mar¬
gins ; the distance from the apex to the cardinal extremity and to the
front of the shell being about equal. Apex sometimes projecting slightly
over the area : mesial sinus shallow, well defined, and reaching to the
apex, sometimes a little flattened in the bottom. Area extremely ele¬
vated, nearly flat or slightly concave above ; fissure large and open
to the apex, the length of the sides being about once and a half the
width at the base.

“ * Report of a Geological Exploration of Part of Iowa, Wisconsin and Illinois, made under instructions
from the Secretary of the Treasury of the United States in the autumn of 1839 ; with charts and illus¬
trations. By David Dale Owen, M. D., Principal Agent to explore the mineral lands of the United
States. Ordered to be printed, by the Senate of the United States, June 11, 1844.”

[ Paleontology IV.] 27

310

PALAEONTOLOGY OF NEW-YORK.

Dorsal valve moderately and evenly convex with a well-defined low
rounded mesial fold ; beak, and margin of the valve in the middle,
slightly arched. Area narrow at the sides, but having the width of a
line in the middle.

Surface marked by from sixteen to twenty plications on each side of the
mesial fold and sinus : these plications are rounded and well defined ;
about eight of them reach the apex on the ventral valve, and the re¬
mainder coalesce with the angular border of the area. In perfect spe¬
cimens the entire surface has been covered by fine concentric undula¬
ting striae, which are crossed by fine radiating' striae. The remains of
these, upon some of the silicified specimens, give a granulose surface.
The length of full grown individuals is a little more than three-fourths
of an inch, with a width of about an inch and three-eighths : the height
varies from three-fourths of an inch to a little less.

I have before me more than a dozen specimens from near the Falls of the
Ohio or from Charleston landing, among which there is very little variation in the
general features. The smallest individual of these has a length of a little more
than half an inch.

Dr. Owen first noticed this species in his Report in 1839. In 1841, I re¬
ceived specimens from him with this name attached ; and during many years, so
far as I know, the specimens from the Falls of the Ohio and from Charleston
landing were the only ones distributed under this name. In his Catalogue of Spe¬
cies, appended to the Geological Report of Wisconsin, Iowa and Minnesota, page
628, Dr. Owen cites as localities “Pine creek; Davenport; below Rockingham;
New-Buftalo ; Rapid creek ; Wapsinonox ;” and “ elsewhere in the United States,
Columbus, Ohio ; Charleston landing, Indiana ; Falls of the Ohio.”

The figures 6 a, b ( ut cit.) appear to me to be of the typical form, and may have'
been made from Indiana or Ohio specimens ; but certainly figures 2 and 2 a are
not of the same species. I have not seen specimens from Pine creek er elsewhere
in Iowa, which I regard as identical with those of Charleston lauding, although
such may occur. I can only suppose that the similarity of form may have misled
Dr. Owen, and induced this reference ; but I believe it will be more just and
more satisfactory to retain the name 8. euruteines for the species to which it was
originally applied by Dr. Owen himself.

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

211

Figures 14, 15, 16 and 17 of Plate 31 represent the characteristic features of this spe¬
cies from the localites cited below.

Figure 18 is a ventral valve with the dorsal valve' removed, except at the apex, and
showing the disposition of the crura and spiral arms.

Figure 19 is a cardinal view of a smaller individual.

Geological formation and localities. In the limestone of the age of the Upper
Helclerberg group, at Columbus, Ohio ; Falls of the Ohio (Louisville and Jeffer¬
sonville), and at Charleston landing, Indiana.

Spirifera eumteines, var. fornacula.

PLATE XXXI (figures 11, 12 and 13).

Sp-.rifer fornacula : Hall, Tenth Report on State Cabinet, p. 154. 1857.

“ “ Description of New Pal. Fossils, p. 114. 1857.

This species possesses the essential characters of J$. eurateines , with the area a
little more arcuate in the upper part ; while the relative strength of the plications
offer no characters of specific importance : there are, in one specimen, nine, and
in another ten, in the space occupied by eight plications in iS. eumteines proper.

In casts of this variety, the mesial fold is flattened on the summit and grooved
towards the upper part, and the sinus is more distinctly flattened on the bottom.
In one specimen the cardinal angles are produced and mucronate ; but this may
likewise occur from the different surrounding conditions.

The figures 11, 12 and 13 are representations from a specimen heretofore de¬
scribed under the name of S. fornacula.

Geological formation and locality. This form occurs in limestone of the age of
the- Hamilton group, and perhaps also in Corniferous limestone, at the Bake-oven,
on the Mississippi river, Illinois.

Spirifera manni.

PLATE XXXI.

Spirifer manni : Hall in Tenth Report on the State Cabinet, p. 128. 1857.

Shell semielliptical or subquadrate; valves very unequally convex:
hinge-line equal to the greatest width of the shell ; cardinal extremi¬
ties angular, and sometimes produced in acute extensions.

Ventral valve subpyramidal, the height often nearly equal to two-thirds
the length ; greatest elevation at the apex, and thence curving to the
front and lateral margins ; mesial sinus angular above, and rounded or

SS1S

PALAEONTOLOGY OF NEW-YORK.

flattened toward the front ; margins angular and sharply defined. Area
large and high, flat and inclined a little backwards or slightly concave ;
foramen large and open to the apex.

Dorsal valve more or less gibbous and sometimes only moderately con¬
vex, curving to the front and lateral margins, and a little flattened at
the cardinal extremities; mesial fold moderately elevated, strongly
defined, and flattened or concave on the summit : the beak and adja¬
cent portion of the margin is more or less arcuate, and the area is
concave for more than half its length on each side of the centre.

The surface is marked by ten or twelve plications on each side of the
mesial fold and sinus ; the plications rounded or subangular, and some¬
times subnodose on exfoliation. Portions of the shell preserved on some
of the specimens show strong lamellose concentric striae, with faint
radiating striae.

All the s Decimens which have come under my observation are more or less
imperfect, and in the condition of partial or entire casts.

The figures 20, 21 and 22 are from a typical specimen of this species, from
which the shell has been mainly exfoliated.

Figures 24 and 25 are of a specimen from near Williamsville, New-York, which
has similar proportions and the same number of plications ; but these are suban.
gular and a little nodose, while the mesial fold is more distinctly depressed in the
centre.

In some respects this form resembles 8. varicosa ; but though much larger, it
has fewer plications.

There is another form much less gibbous and more extended on the hinge-line
than the two preceding specimens ; of this, a large individual is illustrated in
figures 26-30. The proportion of area and length of shell are similar, the mesial
fold is flattened or concave on the summit, and the number of plications is the
same : it differs only in the lesser gibbosity of the dorsal valve and the greater
extension of the hinge-line.

Geological formation and localities . The specimens from which this species
was originally described were from Ohio, occuring at Sandusky and near Colum¬
bus. In New-York, it is found at Williamsville, in the Comiferous limestone.

SPIRIFER^E OF THE UPPER HELDERBERG GROUP.

£S3

Spirifera divaricata.

PLATE XXXII.

Spirifer divaricatus : Hall, Tenth Report on the State Cabinet, p. 130. 1857.

“ “ Description of New Species Pal. Fossils, p. 93. 1857.

Spirifer venustus : Hall, Thirteenth Report on State Cabinet, p, 82. 1860.

Shell ventricose, somewhat rhomboidal or quadrilateral (looking upon
the ventral valve). Dorsal valve semielliptical : hinge-line less than
the width of the shell ; cardinal extremities obtuse or rounded ; area
large.

Ventral valve most convex above the middle, extremely arcuate from
the umbo to the base, abruptly curving to the sides : beak abruptly
arching over to the area ; sinus plicated, shallow above and becoming
rapidly expanded below, with the margins undefined and terminating
in a broad triangular extension in front. Area high, flat below, abruptly
arcuate above, and reaching to the cardinal extremities : foramen
large.

Dorsal valve regularly and strongly convex, with an angular mesial
fold, which is narrow above and expands towards the front, with bifur¬
cating plications ; sides regularly curving, and sometimes a little flat¬
tened towards the cardinal extremities. Area rather wide, with the
beak and central portions of the valve arching over it.

The surface is marked by numerous fine bifurcating rounded or sub-
angular plications ; the mesial sinus having on either side a stronger
plication, which bifurcates on one or on both sides. At the beak there is
a single plication in the bottom of the sinus, which sometimes continues
simple nearly or quite to the base ; while the accessions take place
mainly from those on the sides of the depression, till they reach the
number of ten, eleven or twelve within the limits of the sinus near the
base. In a specimen of ordinary size, where the surface is well preserved,
there can be seen sixty or more plications with their divisions at the
margin of the shell. In some specimens from the Corniferous limestone,

914

PALAEONTOLOGY OF NEW-YORK.

where the surface is partially or entirely exfoliated, the bifurcating cha¬
racter of the striae is not observed ; and in one specimen, they appear
to have been nearly simple throughout.

The plications are crossed by fine imbricating lamellose striae, which
are abruptly arched backwards.

A cast of the ventral valve shows a large oval muscular area, which
is deeply divided by a rounded median crest, and strongly striated on
the lateral portions.

After examining all the collections that have been made, I am unable to point
out any specific difference between the specimens originally described by me as
8. divaricatus , and those subsequently described as 8. veniistus, from the Hamil¬
ton group. The specimens then before me were in the condition of the one figured
on plate 32 figure 1 ; while the Hamilton specimens, illustrated in figures 2-6,
offered at first view very little similarity with those of the limestone, and were
regarded as a distinct species. Other specimens from the limestone have a nearer
approach to those of the Hamilton shales.

This shell, in its proper form and proportions, is one of the finest Spirifers in
the whole series, and is readily distinguished from all others by the bifurcating
plications and sharp zigzag concentric striae. The largest specimen seen has a
width of nearly three inches with a length of two inches, and a depth of one inch
and an eighth.

Geological formations and localities . In the Corniferous limestone at Scho¬
harie ; at Stafford in Genesee county; at Williamsville and Clarence in Erie
county. In the Hamilton group, at York, Livingston county. I have seen a frag¬
ment of this species from the limestone near Port Colborne, Canada West.

Spirifera fimbriata.

PLATE XXXIII.

Delthyris fimbriata : Conrad, Jour. Acad. Nat. Sciences Philadelphia, Vol. viii, p. 263. 1842.

Spirifer fimbriata : Conrad ; Billings in Canadian Journal, p.'259. 1861.

Shell transversely subelliptical, gibbous : hinge-line less than the width
of the shell ; cardinal extremities rounded.

Ventral valve gibbous in the upper half, regularly curving to the front
and sides ; sinus well defined, usually shallow and rounded, sometimes
deep and angular, and much produced in front ; beak small and
incurved over the area, which is high and concave and extending

SPIRIFERiE OF THE UPPER HELDERBERG GROUP.

£13

• . about half the entire width of the shell : foramen often limited by a
sharp elevated border, which appears to be a projection of the dental
plates.

Doksal valve gibbous, regularly convex on the sides, a little flattened at
the cardinal extremities ; mesial fold abruptly elevated in the lower
part, often but little elevated or scarcely defined in the upper part ;
beak small, slightly arched over the sublinear area, which is somewhat
concave.

Surface marked by from three or four to eight or nine low, rounded,
often obscure plications on each side : these are crossed by imbrica¬
ting lamellose striae, which are sometimes wide or distant, and often
crowded. The concentric striae are studded with elongated nodes or
tubercles, which are thus arranged in parallel bands, more or less con¬
tiguous, according to the distance of the concentric stiae.

The elongate tubercles may perhaps more properly be regarded as
interrupted radiating striae, which, in the perfect condition of the shell,
have doubtless extended in slender spines or setae. (They are termed by
Mr. Conrad short longitudinal striae.)

The area is strongly striated vertically.

It has been impossible to obtain the means of a satisfactory study of the interiors
of these shells. A cast of the ventral valve from the Schoharie grit has a deep and
sub angular sinus and the costas rather strongly marked, with a subovate muscular
area which is depressed in the centre with linear elongate occlusor imprints, and
cavities at the sides showing short strong dental plates.

In another cast from the Hamilton group the muscular area is narrower, the
dental plates longer and thinner, with faintly marked ribs, and there is evidence
of a distinct median septum. The surface of the cast in both valves is strongly
marked by vascular impressions.

This species begins its existence (so far as we know) in the Oriskany sandstone,
where it has been rarely observed. It occurs in the Schoharie grit, and reaches its
greatest dimensions in the Corniferous limestone ; having often a width of nearly or
quite two inches, with a length of an inch and a quarter. It is often well preserved
in the Hamilton group ; but in this formation, it rarely attains a width of an inch
and a half. It is not known in the Chemung group, though there is a representa-

916

PALAEONTOLOGY OF NEW- YORK.

tive form in that epoch. The species has a wide geographical range, being known
throughout New-York, Canada West, Ohio, in the Mississippi valley, and as far
south as Virginia.

The 8. fimbriata is the first of this type in our formations, but is represented
by similar forms* to the close of the Carboniferous period.

In the illustrations of these species, the fragment 1 is from the Oriskany sandstone
the figures 2, 3 and 4 are from the Schoharie grit ; figures 5-11 are from the
Corniferous limestone : the remaining figures are from the Hamilton group.
Geological formation and locality. This species occurs in the Oriskany sand¬
stone at Saugerties in Ulster county, and at Knox in Albany county, and probably
in Schoharie. It is found in the Schoharie grit in Albany and Schoharie counties,
and in the Corniferous limestone in the same region ; and at Cherry- valley ;
Westmoreland, Oneida county ; Onondaga-hollow, Onondaga county ; Stafford,
Genesee county ; Williamsville, Clarance, and other places in Erie county ; in
Canada West, and at Columbus and other places in Ohio.

In the Hamilton group, it occurs on the shores of Seneca and Cayuga lakes,
and upon Canandaigua lake ; at York and Moscow in the Genesee valley ; and at
Darien; at Eighteen-mile creek, and other places in Erie county. Also in the same
group in Maryland and Virginia ; and at Davenport and New-Buffalo, Iowa ; at
Hock-island, Illinois ; and elsewhere in the Mississippi valley.

Spirifera mucronata.

PLATE XXXIV.

Delthyris mucronata : Conrad, Ann. Report on the Geology of New-York.

“ “ Vanuxem, Geol. Report Third District, p. 150. 1842.

“ “ Hall, Geol. Report Fourth District, p. 198. 1843.

Spirifera mucronata : Billings, Canadian Journal, May, 1861.

Shell more or less gibbous, semicircular, semioval, or triangular in out¬
line ; cardinal angles sometimes truncate but usually extended, and
often extremely prolonged into mucronate points, giving a length of
binge-line two, three or four times as great as the shell ; sides straight
or curving, the front straight or concave.

Ventral valve often scarcely more convex than the dorsal, but in very
gibbous forms becoming more unequal, gently curving to the lateral
margins. The beak is small, and incurved over the narrow linear area,
the mesial sinus is sharply defined quite to the apex, and limited by
angular plications which are Stronger than the adjacent ones. The

* S. pseudolineata and S. setigcra. see Geology of Iowa, pp. 645 and 705.

SPIRIFERiE OF THE HAMILTON GROUP. 217

prevailing form of the sinus is shallow and rounded in the bottom : it
is sometimes flat and sometimes with a fold in the centre (See figure
11), and again it is angular (as in figures 19 and 20).

Dorsal valve moderately convex, sometimes becoming gibbous. The
sides are gently curving, and usually flattened towards the cardinal
margin : the mesial fold prominent and well defined, flat or rounded
above, sometimes with a median groove and again angulated in the
middle. The beak is incurved, and the area extremely narrow, about
one-third as high as that of the ventral valve.

Surface marked by from eight or ten to twenty or more subangular pli¬
cations on either side of the mesial fold and sinus : the plications are
not very prominent but usually well defined, the outer half of the
number not reaching the beak, but terminating in the callosity along
the area-margin. The plications are crossed by numerous fine lamellose
striae, which become'crowded together and closely imbricating towards
the front of the shell, sometimes presenting several interrupted lines
of growth.

The proportions are extremely variable, the length being in some
specimens about two-thirds af great as the width ; while in others more
extreme, the width is three inches or more, measured on the hinge-line,
and the length is scarcely three-fourths of an inch. In one specimen
before me, with a width rather more than four inches on the hinge-line,
the length- is less than three-fourths of an inch : this great lateral exten¬
sion is not due to age. Some of the younger shells are extremely mucro-
nate, as shown in figure 3 ; while in figures 1, 8, 10 and 11, showing
gradations in size, there is comparatively little extension on the hinge¬
line.

The interior of the ventral valve shows short and rather strong teeth,
with scarcely any extension of the dental plates, and a small striated
muscular area, in the centre of which are the elongate occlusor muscular
markings.

In the dorsal valve, the cardinal process or callosity is well preserved,
[ Paleontology IV.] 28

218

PALAEONTOLOGY OF NEW- YORK.

and the teeth-sockets are large, while the bases of the crura are often
distinctly seen. The interior surface is usually papillose.

Geological formation and localities. This species begins its existence in the
Marcellus shale (figure 3) ; and is abundant everywhere in the Hamilton group,
sometimes constituting thin layers to the exclusion of every other fossil. In the
eastern part of the State, in the arenaceous shales of this group, it occurs in the
form of casts ; and this is its usual condition in Schoharie, Otsego and Madison
counties, while from Cayuga lake westward it retains the shell. In some places in
Canada West it is found to be the prevailing fossil, while scarcely any other
Spirifer occurs in the same association. I have received specimens of this shell,
said to have been found near the Falls of the Maumee river. It occurs likewise
in Maryland and Virginia.

In the Drift of Ohio, Indiana and Illinois, this species occurs more frequently
perhaps than any other fossil.

The Spirifer a bimesialis ( Geol. Report of Iowa, page 507, plate 4, figure 6 ) is
closely allied to S. vmcronata , differing mainly in the much wider area and more
elevated beak of the ventral valve. The S. subattenuata and S. inutilis of the same
volume (pages 504 and 505, plate 4, figures 3 and 4) have similar external cha¬
racters, with a shorter hinge-line and higher area than S. bimesialis. These two
species are represented in form and proportions (except the extreme narrow area)
by S. mvcronata, Plate 33, figures 19, 20 and 21 of this volume.

Spirifera twllia ( n. s.).

PLATE XXXV.

Shell gibbous, subelliptical ; length and width about as two to three, or
as three to four : hinge-line equalling or greater than the width of
the shell ; cardinal extremities truncate or auriculate.

Ventral valve gibbous, the greatest convexity above the middle of the
shell, regularly arcuate from beak to base, curving abruptly to the
sides and a little flattened at the cardinal extremities ; beak strongly
incurved : sinus sharply defined quite to the apex, not deep, rounded
in the bottom. Area high, flat in the lower part and extending to the
hinge-extremities, concave in the upper part.

219

SPlRIFERJS OF THE HAMILTON GROUP.

Dorsal valve moderately convex ; the mesial fold strongly defined, wide
below and narrow above, flattened and sometimes depressed upon the
summit ; the lateral portions of the shell curving gently to the sides,
with the cardinal extremities flattened.

Surface marked by from sixteen to eighteen comparatively wide flat¬
tened or low rounded ribs on each side of the fold and sinus ; the ‘
exterior ribs fine and obscure. In exfoliated specimens, and sometimes
in others, the ribs are subangular. The entire surface ( including the
mesial fold and sinus, and particularly the intervals between the pli¬
cations) marked by fine continuous radiating strise ; while faint con¬
centric striae are visible on the fold and sinus, as well as obscurely on
the costae, and more decidedly upon the cardinal extremities; but
these are subordinate to the radiating striae.

The casts show the muscular area of the ventral valve to be elongate,
and margined above by long dental plates which are comparatively strong
as shown in figure 8. In another specimen, figure 9, there has been an
elevated median crest in the muscular area.

The figures 1 and 6 of Plate 35 illustrate the prevailing character.

In general aspect this species resembles S. medialis ; but it is more gibbous
and proportionally less in width than the young of that shell, while the radiating
strife are a distinctive feature. The area also is more arcuate than in any forms of
8. medialis.

It is with hesitation that I propose a new species of Spieifera, while I am com¬
pelled to unite several that have hitherto been regarded as distinct ; but in this
one the characters seem to be distinguishing, and irreconcilable with any of the
species heretofore described.

Geological formations and localities . In the shales of the ^Hamilton group, on
the east side of Skaneateles lake, Owasco lake, Borodino, and in loose masses of
the rock near Tally, Apulia arid other places in Onondaga county. It is not at
present known from more western localities.

23©

PALAEONTOLOGY OF NEW-YORK.

Spirifera formosa.

PLATE XXVIII.

Spirifer formosa : Hall, Tenth Report on the State Cabinet, p. 154.

Shell semielliptical or subquadrate, more or less ventricose : v. ives
about equally gibbous ; hinge-line equal to the greatest width of the
shell, with the extremities sometimes a little salient. Surface plicate.
Ventral valve most prominent above the middle and towards the umbo,
with the sides regularly curving to the margin ; the beak small, and
neatly incurved over the area. Area rather high, continuing to the
cardinal extremities, concave, and striated longitudinally ; fissure
large, wider than high : mesial sinus shallow, of moderate width, and
sometimes with an obscure depression along the centre.

Dorsal valve regularly convex, a little flattened or sometimes concave
towards the cardinal extremities : mesial fold but little elevated, flat¬
tened upon the summit, and sometimes a little depressed in the middle
and continuing distinctly to the neatly incurved beak. Area distinct
of moderate height, and nearly parallel with the longitudinal axis of
the shell.

The surface is marked by from fifteen to seventeen slender rounded
plications on each side of the mesial fold and sinus ; and these are
crossed by fine concentric undulating strise, which often become dis¬
tinctly imbricate and stronger towards the margin. In well-preserved
specimens, remains of extremely fine radiating striae are found.

This is a neat symmetrical species, with a gracefully curved outline and salient
angles. In profile, the beak of the ventral valve projects but little beyond that of
the dorsal valve. The mesial fold, which is usually flat in the middle and lower
part of the shell, is often distinctly grooved along the centre in the upper part,
and this depression sometimes continues to the base.

Geological position and locality. In limestone of the age of the Hamilton group1
Bake-oven, Illinois.

SPIRIFERiE OF THE HAMILTON GROUP.

221

Spirifera sculptilis.

PLATE XXXV.

Delthyris sculptilis : Hall, Geol. Report of Fourth District New-York, p. 202. 1843.

Shell gibbous ; valves subequally convex, semielliptical or subtriangular :
hinge-line longer than the width of the shell, and prolonged into
mucronate extensions; length about half the width on the hinge-line.
Surface coarsely plicated.

Ventral valve regularly convex, arcuate; beak arcuate over a sublinear
area of moderate height, extending to the limits of the cardinal line ;
mesial sinus strongly defined, subangular.

Dorsal valve regularly convex, the greatest convexity in the middle
and regularly arcuate from beak to base; mesial fold abruptly and
strongly elevated, with the summit flattened or 'grooved ; beak in¬
curved : area very narrow.

Surface strongly marked by three, four or five abruptly elevated angular
plications on each side of the mesial fold and sinus, leaving a some¬
what wide corrugated space at the cardinal angles. The plications
bordering the sinus are stronger, more elevated, and continuing dis¬
tinct quite to the apex. . The shell is concentrically marked by strong
imbricating lamellose striae, which are abruptly bent backwards and
much elevated in crossing the plications, giving them a subnodose
character. In the bottom of the sinus, these lamellose striae have often
a distinct retral bend, with a slight elevation indicating an incipient
plication which corresponds with the depression in the mesial fold.

This species is readily recognized by its few strong plications, and the wide
space at the cardinal extremities marked only by the concentric stri®. Compara¬
tively few specimens have been found, and these are partially exfoliated.

In the figures illustrating this species, the dorsal valve is a cast.

Geological formations and localities. This shell, in its characteristic form,
occurs in a calcareous layer in the Hamilton shales, at Eighteen-mile creek. It is
found at Ludlowville in Cayuga county ; on the east and west shores of Seneca
lake, and at York in Livingston county.

222

PALAEONTOLOGY OF NEW- YORK.

Spirifera ziczac.

PLATE XXXV.

Dclthyris zigzag : Hall, Geol. Report Fourth District, pp. 200 and 201. 1843.

Spirifer clio : Hall, in Thirteenth Report on the State Cabinet, p. 93. 1860.

Shell transverse, gibbous or ventricose, semielliptical in outline, with
the hinge-line equalling or greater than the width of the shell below ;
the cardinal extremities truncate or auriculate. Surface plicate.
Ventral valve the more convex, the greatest convexity being somewhat
above the middle, arcuate from beak to front ; sides regularly curving
to the lateral margins : sinus deep and wide towards the front, rounded
* or flat in the bottom, produced in front, and sharply defined by the
adjacent angular plications, which are stronger than the others ; beak
incurved. Area elevated, concave, with the margin angular and curv¬
ing to the cardinal extremities.

Dorsal valve moderately convex at the sides ; the mesial fold abruptly
elevated, rapidly expanding below, flattened upon the summit, and
usually marked by a mesial depression. The lateral portions of the
shell curve towards the front, and are flattened or concave towards
the cardinal extremities.

Surface plicated by about eight, ten, or even twelve strong angular
costae, those towards the cardinal extremities being less elevated and
often obscure. The entire shell is marked by fine concentric striae,
which at intervals appear to be crowded together into stronger imbri¬
cating lamellae, sharply arched and elevated upon the costae and upon
the mesial fold, and usually having a slight retral curve in the bottom
of the sinus. In well preserved specimens, fine radiating striae are
visible.

The teeth are short and not very strong. The dental plates form a
ridge along the margin of the fissure, and extend to the bottom of the
cavity in its upper part, and margin the muscular area for only a short
distance.

SPIRIFERiE OF THE HAMILTON GROUP.

£28

This shell resembles S. smlmmik} but it is more gibbous and has a larger num¬
ber of plications, extending quite to the auriculate cardinal extremities ; the sinus
is also wider and the front more elevated. Usually only the coarse lamellae are
conspicuous upon the surface, the finer striae being obscure or covered by adher¬
ing matter.

' Figures 13 and 14 of Plate xxxv offer characters which are apparently inter¬
mediate, having coarser lamellae than the original specimens of Sjpirifera zigzag ;
and it was from specimens of similar form that I described 8. clio.

This species varies in dimensions from half an inch to an inch and a quarter in
width, with a' length two-thirds to three-fourths as great.

Geological formations and localities. In the Hamilton group, at Moscow, York,
Geneseo, Darien, and Eighteen-mile creek, and less frequently on Seneca and
Cayuga lakes.

Spirifera grauulifera.

PLATES XXXVI & XXXVII.

Delthyris granulifera : Hall, Geol. Report Fourth District New-York, pp. 206 & 207, f 1. 1843.

“ congesta : Id. Ib. f. 2.

Spirifer heteroclitus ; Marcotj’s Explanatory Text, etc. PI. 8, f. 7.

<« granulifera : Hall, Tenth Report on State Cabinet, p. 163.

Compare S. clintoni, Id. Ib. p. 157.

«« S. duplicate,, Conrad, Jour. Ac. Sciences, Philadelphia, Vol. viii, pa. 261, pi. 14, f. 16.

<« S. arcta i Hall, Tenth Report on the State Cabinet, p. 161.

Shell semicircular, semielliptical or subcircular, ventricose, often be¬
coming gibbous ; binge-line generally equal to the greatest width of
the shell j cardinal extremities obtuse, or sometimes rounded, rarely
extended : valves subequally convex ; surface plicate.

Ventral valve less ventricose than the dorsal, most prominent near the
umbo, gradually sloping to the cardinal extremities ; beak moderately
elevated, somewhat pointed and incurved. Area of moderate height,
divided in the centre by a rather large triangular foramen which is
about as high as wide. Mesial sinus distinct and subangular in the
upper part, becoming a broad deep rounded depression in fropt, and
often having a slight groove along the centre, with sometimes an in¬
dication of one or two small faintly-marked plications just within the
margins.

SS4

PALEONTOLOGY OF NEW-YORK.

Dorsal valve generally the most ventricose, the greatest convexity a
little above the middle, curving abruptly to the sides, and often a little
depressed just within and below the cardinal angles, which are there
slightly inflected. Mesial fold very prominent, rounded, and marked
along the middle by a distinct rounded depression which is sometimes
very deep, though in rare examples it is represented by only a flat¬
tening of the fold : beak rather prominent and well marked. Area
somewhat large, extending to the extremities of the hinge-line.
Surface marked by about twenty or twenty-two simple low rounded
plications on each side of the mesial fold and sinus, often becoming
quite flattened near the front margin of old or full-grown individuals.
The entire surface of the plications, fold and sinus, is covered by
extremely fine interrupted longitudinal strise, which form numerous
minute pustules or short slender spines, giving a strongly granulose
aspect to the shell. The striae are seen only on extremely well pre¬
served surfaces ; while the granulose character is a common feature,
except on exfoliated or worn specimens. Numerous concentric lines of
growth and finer concentric striae cross the plications, and often be¬
come crowded near the front margin of adult specimens.

Interior of the ventral valve with a broad and somewhat quadrangular
muscular impression, which varies much in size in different individuals,
and is often marked in the upper part with strong transversely radia¬
ting striae, and in the lower part with longitudinal striae. The upper
part of the impression is bounded by strong dental lamellae; which
unite with the broad teeth above. The upper part of the valve is
thickened, the shelly matter often filling the rostral cavity, and ex¬
tending as a transverse septum in the bottom of the fissure for one-third
or one-half its length. In the interior of the dorsal valve, the muscular
impressions are often well defined, with a faintly marked mesial sep¬
tum through the centre.

This species is subject to considerable variation ; some specimens being but
moderately convex, and others extremely ventricose. In some the mesial fold is
scarcely flattened, while in others the central groove is nearly half the depth of the
fold. There is also much difference in the height of the area and in the incurving
fo the beak; while in some individuals the cardinal angles are extended consider¬
ably beyond the sides of the shell, and in others they are shorter and rounded. -

SPIRXFER2E OF THE HAMILTON GROUP.

225

Sjpirifer congestd (Geol. 4th District) is a specimen of this species having a short
hinge-line and very obtuse cardinal extremities, a narrow area, incurved beak, and
a mesial fold simply flattened instead of the usual groove ; while the granulose
character of surface is scarcely perceptible. Sjpirifer dintoni (10th Rep. on State
Cabinet) was founded upon small specimens of this species occurring in a band of
limestone, and having the granulose surface entirely removed by exfoliation, while
the plications and sinus have a. sharper and more angular expression, and the car¬
dinal extremities are more extended than usual ( See Plate xxxvti).

The specimens figured on Plate xxxvi illustrate the prevailing forms observed
in the calcareous shales of the Hamilton group in Western New- York. Smaller
specimens than figure 1 are extremely rare, while it is not often observed of greater
dimensions than fig. 10. The elevation of the beak of the ventral valve as shown
in figures 3 and 7 is the prevailing character; though in specimens like fig. 6 ( 8.
congesta , ut cit.), the umbo of the dorsal valve is much more elevated, while the
beak of the ventral valve is less extended. The interior characters of the dorsal
and ventral valves of well-formed and full-grown individuals are shown in figures
11 & 12. Some casts of this and allied forms are figured on Plate xxxvm a.

Geological formation and localities. This species is known in the Hamilton
group in Schoharie, Otsego and Madison counties, usually in the condition of casts.
It is coextensive with the Hamilton group in the State of New-York, occurring
on the shores of Cayuga, Seneca and Canandaigua lakes; at Geneseo, Moscow
and York in Livingston county; at Pavilion and Darien, Genesee county, and at
Eighteen-mile creek in Erie county, as well as numerous other places. The variety
with more angular extremities and mesial fold, which I have designated as S.
dintoni, is known only in a calcareous band at Eighteen-mile creek. The species
likewise occurs in Pennsylvania, Maryland and Virginia.

[ Paleontology IY.]

29

226

PALAEONTOLOGY OF NEW- YORK.

Spirifera mami.

PLATE XXXYII.

Spirifer marcyi : Hall, Tenth Report on State Cabinet, p. 158.

Shell semicircular or subelliptical in outline, gibbous or moderately con¬
vex ; cardinal extremities extended, sometimes submucronate : valves
subequally convex. Area variable in height. Surface plicated.

Ventral valve scarcely deeper than the opposite, except in young indivi¬
duals ; very regularly arcuate, with sides sloping somewhat gradually
from the beak to the cardinal extremities : beak usually prominent
and pointed, sometimes incurved. Area variable in height, more or
less incurved, often nearly flat, strongly striated longitudinally, the
inner portion finely marked by vertical striae ; fissure higher than
wide, one-third or more of the upper part closed by a strong transverse
plate or septum. Mesial sinus distinct but not deep, rounded dr flat¬
tened in the bottom, with subangular margins in the upper part which
become more rounded near the front.

Dorsal valve varying from moderately convex to gibbous, a little flat¬
tened near the cardinal extremities in some specimens. Mesial fold not
very prominent, rounded on the top, distinctly defined at the margins.
Area of moderate width.

Surface marked by from twenty-four to thirty simple rounded plications,
which are little elevated and of moderate strength, crossed by fine
concentric lines, and marked (in some of the larger specimens) by a
fine longitudinal groove along the middle, or otherwise longitudinally
striated : this is not a constant feature. In both valves the surface is
marked by very fine elongate pustules, which become crowded towards
the front in old individuals. This gives a very marked and reliable
character when preserved as shown in fig. 18, Plate xxxvn.

The species presents considerable variations in height of area in the ventral valve,
which in some specimens is large with an arched beak, and in others narrow with
the beak much incurved : in the latter variety, the valve is more gibbous. In
the original specimens described, the area is nearly flat, with its exterior margin
sharply defined and the beak little incurved. The shells vary also in the gibbosity
of the valves, in the extension of the cardinal extremities, and somewhat in the
strength of the plications.

SPIRIFERiE OF THE HAMILTON GROUP.

227

The figures 10 - 16 illustrate the prevailing form and characters of this species.

Fig. 17 is of the interior of the dorsal valve : the interior of the ventral valve is unknown.
Fig. 18 is an enlargement of the surface.

Geological formation and localities .- The original specimens described were
from the Hamilton group at Covington in Genesee county. It has since been found
among collections from the shores of Cayuga and Seneca lakes; at Dresden in
Yates county; on the shore of Canandaigua lake, and at Geneseo and York in
Livingston county.

Sphifera medialis.

PLATE XXXVIII.

Delthyris medialis : Hall, Geol. Report Fourth District New-York, p. 208, f. 8. 1843.

Spirifer medialis : Hall, Tenth Report on State Cabinet, p. 164.

Compare Delthyris audacula, Conbad, Jour. Acad. Nat. Sciences, Philadelphia, Yol.viii, p.262.

Shell sub triangular, semicircular or subelliptical : valves moderately
convex in young specimens, becoming ventricose in old shells ; hinge¬
line usually extended beyond the width of the shell below, sometimes
mucronate at the extremities : surface plicate.

Ventral valve usually deeper than the dorsal : beak prominent, more
or less incurved. Area generally of more than medium height, longi¬
tudinally striate and divided in the middle by the deltoid fissure, which
is twice as high as wide, and reaches to near the apex of the valve.
Mesial sinus of moderate width, reaching to the apex, rather deep,
generally rounded at the bottom, but sometimes a little flattened ; the
margins subangular and distinct.

Dorsal valve moderately convex or gibbous, the greatest convexity
above the middle : beak small and slightly incurved. Area linear and
well defined ; the lateral extremities of the valve a little deflected
along the hinge-line. Mesial fold prominent, rising abruptly at the
sides, rounded or slightly flattened on the top.

Surface marked by from twenty to thirty simple plications on each side
of the mesial fold and sinus. These are of medium size in full-grown
shells, being either low rounded, flattened, sharply rounded, or sub-
angular in different individuals ; the principal ones are frequently
marked along the centre by a fine threadlike groove, a feature most

PALAEONTOLOGY OF NEW-YORK.

common on the ventral valve. Numerous strong concentric lines of
growth mark the surface, and are very closely arranged near the front
in full-grown specimens, giving a strongly imbricate character to that
part of the shell.

Interior of the ventral valve marked by a somewhat quadrangular me¬
dium sized muscular impression, which is bordered in the upper part
by strong dental lamellae : teeth prominent, of moderate strength. The
-fissure is usually partially or entirely covered by a pseudo-deltidium,
and the upper part of the rostral cavity is often filled and solid, with
a strong plate or septum closing the bottom of the fissure for one-third
or one-half its length. In a single individual, the deltidial covering was
observed to be composed of successive arching and imbricating plates,
which, in the lower part, apparently consist of a double alternating
series. The muscular impressions of the dorsal valve are less strong
than those of the ventral, but often well marked, with a distinct
median ridge ; teeth-sockets projecting into the cavity of the valve ;
lateral portions of both valves strongly marked by the plications.

This shell is subject to many and extreme variations in the extent of hinge-line,
convexity of the valves, height of area, and incurving of the beak : the plications
also vary in number and strength. It is an abundant form, coming next in number
of individuals to the-N. mucronata . The following species, described by me in the
Tenth Report on the State Cabinet, is probably only a variety of this Species with
fewer and stronger ribs. In its ordinary or prevailing form and features, it is a
species readily recognized : it is only since larger collections have been examined
from numerous and widely-separated localities, that these extreme variations have
been observed.

Geological formation and localities. This species is found in casts in the coarser
shales of Otsego and Madison counties, and becomes common on the shores of
Cayuga and Seneca lakes and on the outlet of Crooked lake. It is found on the

SPIRIFERiE OF THE HAMILTON GROUP. *

shore of Canandaigua lake, and at Geneseo, Moscow and York in Livingston
county; at Covington and Darien in Genesee county, and at Eighteen-mile creek
in Erie county. It is extremely rare, if occurring at all, in more western localities-

Spirifera medialis, var. eatoni.

PLATE XXXVIII.

Spirifer eatoni : Hall, Tenth Eeport on State Cabinet, p. 157.

Shell robust, semicircular or sub elliptical, extremely ventricose ; binge¬
line equalling or less than the width of the shell below : valves sub-
equally convex : surface plicate.

Ventral valve much elevated in the umbonal region, sloping gradually
to the cardinal extremities, which are either obtusely pointed or
rounded. Mesial sinus moderately wide, not deep, flattened on the
bottom, angular at the sides, and reaching to the beak. Area high,
straight or but little incurved, with a narrow deltoid opening reach¬
ing to or near the apex of the valve : beak small, pointed, slightly
incurved.

Dorsal valve convex, a little flattened or slightly inflected near the
cardinal extremities : mesial fold well marked, rising abruptly at the
sides and flattened on the top. Area narrow linear.

Surface marked by from fifteen to eighteen simple rounded plications
on each side of the fold and sinus, with sharply defined narrow spaces
between, and crossed below the middle by strong imbricating lines of
growth.

Interior of the shell unknown.

There is probably no sufficient reason for retaining this variety as a species, and
perhaps a large number of individuals will show an insensible gradation from the
typical forms of 8. medialis to the more robust and ventricose forms with short
hinge-line and fewer plications.

Geological formation and localities. In the Hamilton group, on the shore of
Seneca lake; at York in Livingston county, and probably at other places.

23©

PALAEONTOLOGY OF NEW-YORK.

Spirifera angusta.

PLATE XXSYIII A.

Spiri/er angusta : Hall, Tenth Report on State Cabinet, p. 164.

Shell very depressed pyramidal, extremely extended transversely ; car¬
dinal extremities attenuate, acuminate : valves very unequally convex,
with surface finely plicate.

Yentral valve proportionally very deep, forming nearly the entire thick¬
ness of the shell : beak elevated and pointed, or slightly incurved at
the apex ; the cardinal margins sloping very regularly to the hinge-
extremities. Area extremely elevated and inclined forward ; the full
height equal to the length from the beak to the front of the valve ;
longitudinally and vertically striate, divided in the middle by a fora¬
men which is but little more than half as wide as high, and distinctly
grooved on the sides for the reception of the deltidial plate.

Dorsal valve very depressed-convex, with a narrow and low mesial fold
which is somewhat flattened at top : beak small but distinct, projecting
but little beyond the line of the hinge. Area extremely narrow, and
nearly rectangular to the area of the ventral valve.

Surface marked by about twenty-four to twenty-eight fine simple rounded
plications on each side, few of which reach to the beak. The plications
are crossed by very fine concentric rugose striae, which are slightly
arched upwards on the plications and on the mesial fold.

Interior of the valves unknown.

This species is usually readily distinguished by its extreme lateral extension, and
by the elevated and more or less receding area, which is usually nearly as high or
higher than the length of the ventral valve. There is frequently a slight incurvation
at the apex of the ventral valve, and sometimes the area is nearly vertical. In this
condition it approaches in general form to the young of S. medialis, which has
always a proportionally longer ventral valve.

The specimens of this species have usually a length of an inch or an inch and a quarter (as
in the accompanying figure) ; while the largest individual observed is that figured on Plate
xxxviil A, which has a width of more than two inches. •

SPIRIFER2E OF THE HAMILTON GROUP.

281

This species may be compared with S. segmenta of the Corniferous limestone;
but I have not been able to identify the two as a single species.

Geological formation and localities. This species occurs in the Hamilton group
at Geneseo and York in Livingston county, and at Covington in Genesee county.

Spirifera macronota.

PLATE XXXYIII A.

Delthyris macronota : Hall, Geol. Report Fourth District New-York, p. 206, f. 5. 1843.

Spirifer macronotus : Hall in Catalogue in Report on State Cabinet. 1859.

Shell transverse, subtrianguldr or broadly semielliptical ; hinge-line
much extended, extremities often mucronate : valves unequal in depth ;
area large ; surface plicate.

Ventral valve elevated at the beak, abruptly sloping to the front and
lateral margins, with but little convexity : slope of the cardinal border
very regular to near the extremities. Area one-third as high as long ;
more usually straight or very slightly arcuate, and longitudinally
striate : fissure about twice as high as wide, reaching to the apex of
the valve ; beak minute. Mesial sinus rapidly widening, shallow, flat¬
tened at bottom, with margins subangular especially in the upper part.

Dorsal valve varying from depressed-convex to gibbous, most convex
above the middle ; lateral extremities often inflected ; beak incurved,
not prominent : area linear. Mesial fold well marked, usually flattened
on the top, sometimes strongly rounded.

Surface marked by from twenty-five to thirty-five slender simple ra¬
diating plication! on each side of the fold and sinus ; these are either
flattened or rounded : three or four only on each side reach to the
beak, while the remainder are lost on the margins of the area. The
valves are crossed by numerous strong concentric imbricatingTines of

PALAEONTOLOGY OP NEW-YOEK.

growth, which give an irregular margin to the area, and are often
crowded near the front of the shell, causing an abrupt truncation of
the extremities of the ventral area.

Interior of the ventral valve with comparatively small but well-marked
muscular impressions ; that of the dorsal valve not satisfactorily deter¬
mined. The margins of the interiors of the valves are usually crenu-
lated by the plications and the stronger concentric lamellae of growth.
The fissure is sometimes partially covered by a pseudo-deltidium, and
closed by a solid septum for one-tliird of its length from the apex.
The characteristic features and expression of the fossil are shown in the ac¬

companying woodcut.

SflBIFERA MACRONOTA.

Geological formation and localities. This species occurs on the shore of Seneca
lake; at Bristol, Ontario county; at Geneseo and Moscow in Livingston county;
at Darien, Genesee county, and at Hamburgh and Eighteen-mile creek in Erie
county. A

The three preceding species ( Spirifera medialis, S. angusta and S. ma-
cronota ), in what may be termed typical specimens, are so clearly dis¬
tinguishable one from the other, that we have no difficulty in designating
them. It is only in large collections of specimens that we find individuals
which are not readily referable to either of them. The young of S. me¬
dialis are often much extended at the cardinal extremities ; and though
generally distinguishable from the young of S. macronota by the lower and
more arcuate area, yet there are gradations which often seem to unite the
two. A similar difficulty occurs when we attempt to separate S. angusta
frpm the young of S. macronota ; and there are numerous individuals, not
always, it is true, in a perfect state of preservation, which it is nearly
or quite impossible to refer with satisfaction to either of the species.

SPIRFFERiE OF THE HAMILTON GROUP.

Add to this resemblance in general form, proportions of area, etc., the
great-similarity of surface characters, and the question seems scarcely to
admit of a solution without uniting all these as one species.

Regarding S. angusta as the young condition, we need only a less
development and arcuation of the area, with coarser plications, to make
it undistinguishable from a young S. medialis. Carrying on the develop¬
ment in the same direction, shortening the cardinal extremities and
increasing the gibbosity of the valves, we have the S. medialis in its
typical form. Going still farther in the same direction, the cardinal
extremities may become rounded, the valves ventricose, and the area
arcuate, with still stronger plications, giving the var. eatoni.

In the younger forms we have those with the area slightly arcuate,
vertical and receding. If we regard these features as only conditions of
the same species, we may have those with the vertical areas developed
in the same direction, while the cardinal extremities continue much
extended, until we have the typical form of S. macronota. These forms
continuing, the area vertical or slightly inclined but scarcely arcuate,
may have the cardinal extremities shortened and the shell becoming
ventricose, presenting form and characters which it is equally difficult to
refer to either S. medialis or S. macronota. Again, we find here and there,
among the collections of Hamilton Spirifers, a form where the area is
vertical as in S. macronota, but the lateral extensions much less, and the
ribs fewer and perhaps a little stronger, suggesting a relation to S. euru-
teines and S. manni of the Corniferous limestone.

I am not at present prepared to assert the identity of all these forms ;
but I can easily believe that larger and more extended collections, made
over geographical areas not yet explored, may show a much closer rela¬
tion than we have supposed to exist between them.

I have endeavored, in Plates xxxvm and xxxvm a, to show all the
important varieties of form, selected from a collection of several hundred
individuals, and in which the specimens readily referable to S. medialis
are at least ten times as numerous as those which can be referred to either
of the other species.

[ Paleontology IV.]

30

334

PALAEONTOLOGY OF NEW-YORK.

Spirifera acuminata.

PLATE XXXV : Fig. 24.

Spiri/er acuminatus : Conrad, See page 198 of this volume.

Delthyris prora : Conrad, Jour. Acad. Nat. Sciences Philadelphia, Vol.viii, p. 263.

“ Upper valve trigonal, profoundly ventricose ; ribs double, not very
“ prominent, eighteen or twenty in number ; mesial fold profoundly
“ prominent and acutely angular ; hinge-line shorter than the width
“ of the shell : length one inch and five-eighths ; width two and a
“ half inches.”

The only species in the Hamilton group corresponding with Mr. Conrad’s de¬
scription, is one which I have identified with 8. acuminata y the dorsal valve of
this is shown in figure 24, Plate xxxv. The ribs are more conspicuously bifurca¬
ting than in those from the limestone, and the muscular impression is larger; but
both these features are variable, and therefore cannot be relied upon for specific
distinction.

The localities in the Hamilton group have been cited on page 202.

Spirifera snbumbona.

PLATE XXXII.

Orthis subumbona Hall. Tenth Report on the State Cabinet, p. 168. 1857.

Jlmboccelia subumbona : Id. Thirteenth Report on the same, p. 71. 1860.

Shell small, more or less gibbous or ventricose ; cardinal extremities
rounded : surface smooth, or finely striated concentrically.

Yentral valve ventricose in the middle, regularly curving towards the
basal and lateral margins : umbo much elevated above the opposite
valve, and beak abruptly incurved over the high area, which has its
lateral margins rounded or rarely defined, and sloping towards but not
reaching the cardinal extremities ; more or less arcuate, and the eleva¬
tion apparently variable. The foramen is higher than wide, and open
to the apex in all the specimens observed. There is usually a narrow
but not always distinct mesial sinus, reaching from the apex to the
base of the valve, where it becomes wider but without defined limits.

SPIXtIFERiE OF THE HAMILTON GROUP.

235

Dorsal valve less gibbous than the ventral, somewhat regularly convex
in the middle, and curving towards the front and baso-lateral margins ;
a little depressed or flattened towards the abruptly rounded cardinal
extremities : umbo slightly elevated above the hinge-line ; area linear.
There is often a faint impressed line extending from the beak to the
base of the valve.

Surface marked by fine concentric lines of growth, which are sometimes
crowded into imbricating folds towards the front of the shell. In par¬
tially exfoliated specimens the surface is finely and distinctly punc¬
tated, as if in its original condition it had been covered by closely
arranged spinules. The texture of the shell is fibrous, but yet differing
from the fibrous texture of ordinary Spirifers.

This species is a miniature of the S. lineata of the Upper Carboniferous beds,
having the same general aspect and characters of sui’face marking : it is, however,
usually a little more extended laterally, and the area continues more nearly to the
cardinal extremities. The punctate markings are comparatively finer, and it has
not the regular concentric undulations which often mark the carboniferous species.
It has likewise a distinct impressed line or narrow sinus in the dorsal valve.

The ventral valve alone has much the appearance of Amboccelia, and I had thus
referred the species from some crushed and imperfect specimens. Farther exami¬
nations have brought out specimens in their true form and proportions; not only
from the calcareous beds near the base of the Hamilton group, but also from the
Tully limestone we have specimens un distinguishable from this one.

Geological formation and localities. In the calcareous bands of the Hamilton
shales, on the shore of Lake Erie; in the Tully limestone near Tully, and from
the same rock in Seneca county.

Sjpirifera arata.

Svirifer arata : Hail, Tenth Report on the State Cabinet, p. 161. 1857.

I have already referred to this species under S. granulifera. The original speci¬
mens designated as S. arata , upon re-examination, do not offer satisfactory means
for separation from S. grgnulifera ; and therefore it becomes unnecessary to con¬
tinue the name.

@36

PALAEONTOLOGY OP NEW-YORK.

Spirifera duplicata.

Delthyris duplicata : Conrad, Jour. Acad. Nat. Sciences Philadelphia, Vol. viii, -pa. 261, pi. 14, f. 16.
“ “ ; Id. Ib., referred to under S. granulifera. page 223 of this volume.

Since the preceding pages were sent to the press, I have observed, among some
specimens from the coarser shales of the Hamilton group, the cast of a Spirifer
with duplicate mesial fold and angulated ribs, corresponding to the original de¬
scription of S. duplicata. The material at hand is not sufficient to determine its
specific value.

Spirifera carticosa.

Spirifer corticosa : Hall, Tenth Report on the State Cabinet, p. 160. 1857.

Of this species, I have not obtained sufficient material to satisfy me of its claim
to specific distinction. A well-marked ventral valve, which I have referred to this
species, still remains unidentified with any other species ; while two other well-
marked individuals*, originally referred to the same, prove to be quite distinct
from this and every other species;, so that in the present state of knowledge, I
propose to leave the specimens'without illustration, and subject to future revision.

Spirifera tenuis.

Spirifer tenuis : Hall, Tenth Report on the State Cabinet, p. 162. 1857.

The specimens on which this species was originally founded are silicified in whole
or in part, and it is impossible to know satisfactorily what effect the silicification
and partial solution of the shell may have had in removing or modifying surface
characters. This species is therefore left undetermined for the present.

Spirifera pertenuis.

Spirifer pertenuis : Hall, Tenth Report on the State Cabinet, p. 163. 1857.

The specimens of this species are in a condition similar to the last, and are
consequently left for farther study.

These are probably not from the Hamilton group, though given to me as authentic.

SPIRIFERiE OF THE PORTAGE AND CHEMUNG GROUPS. 237

SPIRIFERiE OF THE PORTAGE AND CHEMUNG GROUPS.

.The shales and sandstones of the Portage group, within the limits of the
State of New- York, are generally very deficient in Brachiopoda, and but
a single species of Spirifer is at present known to me in this formation.
This one is more like the European Carboniferous Spirifera glabra, than
any of the Devonian species figured by Mr. Davidson in his Monograph
of British Devonian Brachiopoda.

In the Chemung group, Brachiopoda are abundant, and Spirifera is
very conspicuous among the other genera. Notwithstanding however its
abundance and wide distribution in this group, there are few species
known in the State, and of these, one only is common, the Spirifera verneuili
— S. disjuncta and its varieties, which extends from the southeastern
counties quite to the western limits of the State, and is equally abundant
in the adjacent portions of Pennsylvania along the southern and western
borders of New-York.

I have heretofore recognized, with doubt, the Spirifer mucronata* in
the Chemung group in the southern part of New-York; but a critical
examination of all the specimens from authentic localities of that forma¬
tion has shown that the fossils thus referred belong to the S. mesacostalis,
and no true example of S. mucronata is yet known to me from the Che¬
mung group.

It may be remarked in this place that the shaly sandstones or arena¬
ceous shales of the Hamilton group in the southeastern part of the State
are lithologically similar to some of the Chemung beds, and not always
readily distinguishable therefrom. In these coarser beds of the Hamilton
group, the S. mucronata is often abundant in the condition of casts.

Delthyris mucronata ? Geological Report of the Fourth District of New-York, p. 271.

338

PALEONTOLOGY OF NEW-YORK.

In the upper part of the Chemung group, and sometimes apparently
near the summit of the formation, there is a grayish or ferruginous con¬
glomerate, often charged with fossil shells, among which there are usually
few Brachiopoda; and in some localities the general aspect of the fauna
is more nearly like that of the W averly sandstone of Ohio, some of the
species being apparently identical with those of that formation and the
western extension of the same. I have, however, detected in this con¬
glomerate casts of Spirifera mesacostalis and S. verneuili — S. disjuncta, as
well as other forms which show its intimate relation with the Chemung
group.

These are the beds which I have heretofore indicated as those which
may become expanded in their western extension,, and constitute in part
the fossiliferous sandstones and shales of Eastern Ohio ; while the Portage
and Lower Chemung beds, which do physically extend into that part of
Ohio, are less fossiliferous than in New- York, and their presence has
been overlooked by some observers. At the same time, there is a dis¬
position not only to claim for the higher portions a distinct place in the
series, but to refer these beds to a distinct system. By whatever name,
however, they may be termed, they apparently constitute part of the great
group of argillaceous and arenaceous shales and sandstones which began
their deposition with the Marcellus shale, and terminate with the red
shales and sandstones of Pennsylvania, or at the base of the conglome¬
rate of the Coal measures, as that formation exists on the borders of
southern New-York and the adjacent counties on the south and west*.

* I had intended, before the completion of the volume upon the Brachiopoda, to have made personal
investigations to determine more accurately the relations of these formations ; but have been for two
years prevented from accomplishing any field work of importance.

SPIRIFERiE OF THE PORTAGE AND CHEMUNG GROUPS. 939

Spirifera laevis.

PLATE XXXIX.

Delthyris Icevis : Hall, Geol. Report Fourth District New-York, p.345, f. 1. 1843.

Shell ventricose, subcircular or semielliptical, with the cardinal extre¬
mities rounded : length and breadth as two to three, or three to four ;
not plicate.

Yentral valve subventricose ; the greatest convexity above the middle,
from whence it curves gently to the base and suddenly towards the
beak, which is% abruptly attenuate and arching over the area : sinus
variable, often shallow, gently concave and scarcely defined; sometimes
becoming deep, subangular, and very broad in the. lower part. Area
extending to the hinge-extremities, of moderate height at the sides
and rising abruptly towards the middle ; foramen partially closed by
an arching, very convex pseudo-deltidium.

Dorsal valve depressed or moderately convex, with a wide and usually
undefined mesial fold which is much expanded below, leaving the an¬
terior margin sinuate : sides of the shell somewhat regularly curving,
and a little flattened at the .cardinal extremities.

Surface usually smooth, or marked only by concentric lines of growth.
In older shells there are sometimes a few obscure and undefined ra¬
diating folds.

The interior of the ventral valve shows strong short teeth with the
dental lamellae much thickened, filling up the rostral cavity and ex¬
tending along the sides of the upper part of the muscular impression •
the muscular space is small or of moderate size, deeply marked, and often
preserving a distinct median crest.

In the dorsal valve the muscular impression is small and narrow, and
usually not deeply marked. The cardinal process is strongly striated, and
this character is distinctly preserved in the cast.

This species, though occurring in considerable numbers at one locality and less
commonly in another, has nevertheless been seen only as imperfect or distorted

@4©

PALAEONTOLOGY OF NEW- YORK.

specimens, or in the condition of casts. All the specimens which have the two
valves attached are more or less crushed, as shown in figure 3.

The specimens figured illustrate the usual condition of the species.

Figures 1 & 2 are casts of a dorsal and a ventral valve of small size.

Figure 3 is a dorsal view of a specimen having the shell crushed.

Figure 4 is a cast of a large dorsal valve.

Figures 5 & 6 show the area and interior of the ventral valve.

Figure 7 is the exterior of a large ventral valve preserving the shell, and showing a remark¬
ably wide subangular sinus, with obscure plications on the sides of the shell.
Figures 8-11 show the characters of the muscular impression.

Geological formation and localities. In the shale of the Portage group, near
Ithaca; and in a shaly sandstone of the same age, near Cqrtlandville, Cortland
county, New-York.

Spirifera mesacostalls.

PLATE XL.

Delthyris mesacostalis : Hall, Report of the Fourth Geol. District, p. 269, f. 9. 1843.

Delthyris acuminata : Id. Ib. p. 270, f. 5.

Hot Delthyris acuminata, Conrad, cited on page 198 of this volume.

Shell variable in form, more or less gibbous, semioval or subquadrate ;
cardinal extremities usually a little salient : surface plicated. Tile
width varies from once and a half to three times the length.

Ventral valve ranging from semielliptical and moderately convex, to
subquadrate and ventricose. In the less gibbous and more extended
forms the convexity is pretty regular in the upper part of the shell,
curving more abruptly towards the front, and nearly flat towards the
cardinal extremities. The beak is small, and the upper part only ab¬
ruptly incurved over the area, which is of moderate height : the sinus
is angular, varying in depth, and marked by a single defined fold in
the bottom, which is usually distinctly angular, but rarely rounded or
depressed. The fissure is higher than wide, and usually not closed by
a pseudo-deltidium.

Dorsal valve very gibbous in the middle and pretty regularly convex
from beak to base, depressed towards the cardinal extremities, and

SPIRIFERiE OF THE CHEMUNG GROUP.

941

becoming quite flat in the more extended forms : mesial fold usually
strongly defined, rising abruptly above the surface on either side, and
marked along the centre by a deep groove. The area is narrow-linear.
Surface marked by from ten to fourteen rounded or subangular plications,
those on either side* of the mesial fold and sinus bejng usually stronger
than the others. When the shell is fully preserved, and sometimes in
partial casts, the surface is marked by strongly arching lamellose strise
or lines of growth, which become much crowded towards the margin
of the valves.

Little is known of the interior structure of this species. A cast of the
ventral valve shows extended and not greasly divergent dental lamellse,
with a strong longitudinal median crest or septum in the muscular im¬
pression.

The specimens under examination are nearly all in the condition of partial casts
or with the shell more or less exfoliated; while all are in single valves, adhering
to the sandstone or shale in which they are imbedded.

The species is well marked and quite distinct from any other in this formation,
though showing a wider range of variation in forms and proportions than I had
originally supposed. The short forms with extremely extended and mucronate car¬
dinal extremities, which are figured in the Report of the Fourth District, p. 270,
f. 5 & 5 a, prove, by several gradations of form, to be of the same species. This
variety resembles the Spirifera mucronata , for which it has no doubt sometimes
been mistaken.

Among specimens from Ithaca (N.York), there are numerous small individuals
of this species, which, on a cursory examination, might be regarded as the young
of S. mucronata. The specimens are for the most part casts, and the dorsal valve
shows the duplication of the mesial fold; but there is no (or scarcely any) in¬
dication of the plication in the bottom of the sinus, although there is unmistaka¬
ble evidence of a longitudinal septum extending from the beak to near the base
of the muscular impression, a feature not known to exist in S. mucronata. The
specimens are usually semielliptical and little extended on the hinge-line, but in
some individuals there is a great extension of the cardinal extremities. From
.these small individuals there is an almost insensible gradation to the larger forms,
as shown in the illustrations on Plate xl. In the laterally extended forms the area
is low, while in the shorter and more rotund forms it is more elevated, as shown
in the figures. The more gibbous forms have been found in a compact sandstone on
the Genesee river, while the smaller and attenuated ones are from more easterly
[ Paleontology IV.] 31

•3 12

PALAEONTOLOGY OP NEW- YORK.

localities. The species has been collected in the shaly beds in the higher part of
the group near the southern limits of Steuben county, and it occurs in a coarse
sandstone and conglomerate in the upper part of the formation near Olean in
Allegany county.

Geological formation and localities. In the Chemung group at Ithaca, and at
Bald hill south of Ithaca, Tompkins county; at Philipsburgh near Angelica, and
at Rockville in Allegany county; near Paintedpost on the Chemung river; at
Troupsburgh in Steuben county, near Olean in Allegany county, and at Randolph
in Cattaraugus county.

Spirifera mesastrialis.

PLATE XL.

Delthyris mesastrialis : Hall. Geol. Report Fourth District, p.269, f. 1. 1843.

Shell large, semielliptical, more or less gibbous, with the cardinal angles
rounded or produced into mucronate extensions : surface plicated.
Yentral valve variable in its convexity, being gibbous or subventricose
in the upper part, curving gently to the front and baso-lateral margins,
while it is depressed or nearly flat towards the cardinal extremities.
Beak incurved over the area, which is of medium height and continued
to the cardinal extremities : mesial sinus rapidly expanding and be¬
coming very wide below, in some specimens being of moderate depth
and in others very deep, and rounded in the bottom, with the margins
well defined.

Dorsal valve moi;e or less gibbous, often with a very regular convexity
when the cardinal extremities are not extended. In other examples
the central portion is somewhat regularly convex, and depressed or
flattened towards the extremities, which may be rounded, slightly au-
riculate, or prolonged into mucronate points. The mesial fold becomes
rapidly expanded in its lower part, with the summit broadly rounded.
Surface plicate with about sixteen to twenty rounded ribs, which are
sometimes low and nearly flat, or become more strongly elevated, in
some of the larger individuals. There are usually from eight to twelve
ribs on each side, which are conspicuous, while the remainder are at¬
tenuate and obscure. The plications, together with the mesial fold and

SPIRIFERiE OF THE CHEMUNG GROUP.

£43

sinus, are conspicuously marked by fine regular radiating striae, and,
in rare examples, these have been observed to be cancellated by con¬
centric striae.

Little is known of the interior of the shell, beyond the presence of
strong teeth and straight diverging dental lamellae.

The species presents considerable variety in its form and proportions; but there
is usually little difficulty in distinguishing it by the external characters, from any
other species in this formation. In its more rotund forms, it approaches the 3.
granulifera ; but the presence of longitudinal striae may usually be recognized
in the casts, while the broad rounded mesial fold withght a depression, is a dis¬
tinguishing feature.

Geological formation and localities. This species has been found in Schoharie
and Delaware counties (New- York), several hundred feet above the base of the
Chemung group. Fine robust specimens occur hear Cortlandville in Cortland
county, and a more delicate variety in the greenish shales north of Elmira. The
stronger forms, with extended cardinal angles, occur on Cayuta creek in Tioga
county.

Spirifera disjuncta.

PLATES XLI & XLII.

Spirifera disjuncta : Soweeby, Trans. Geol. Society, 2d series, Vol. v, pi. 63, f. 8; pi. 64, f. 12, 13. 1840.
« calcarata : Id. Ib., pi. 63, f. 7.

•• extensa : Id. Ib., pi. 54, f. 11.

<* gigantea : Id. Ib., pi. 55, f. 1 - 4.

>< inornata: Id. Ib., pi. 53, f. 9.

•« protensa : Phillips, Pal. Foss, of Cornwall, Devon & West-Somerset, pa. 69, pi. 28, f. 118

<< calcarata & S. disjuncta : Id. Ib., pi. 29, f. 128, 129. [1841.

«* disjuncta : Id. Ib., pi. 30, f. 129.

«« gigantjea : Id. Ib., pi. 30, f. 130.

«« grandceva : Id. Ib., pi. 30, f. 131.

« distans : Phillips (not Soweeby), Ib., pi. 29, f.,127.

“ verneuili :■ Muechison, Bull. Soc. Geol. France, Vol. 11* pa. 252, pi. 2, f. 3. 1840.

*< archiaci : Id. Ib., pi. 2, f. 4.

«« lonsdalei : Id. Ib., pi. 2, f. 2. ' [1845.

Spirifer disjunctus : Muechison, De Veeneuil and Keyseelino, Geol. Russia, Vol. 2, pa. 157, pi 4, f. 4
<« archiaci : Id. Ib., pi. '4, f. 5. 1845. [1845.

<« murchisonianus* : De Koninck, De Veeneuil & Keyseelino, Geol. Russia, Vol. 2, pi. 4, f. 1.

# I have cited the synonymy to a great extent from Mr. Davidson’s British Devonian Brachiopoda,
where the Spirifera murchisoniana ( De Koninck) is given as one of the synonyms of S', disjuncta.
I have not observed the explanation which allows this species to be a synonym of S. disjuncta, and at
the same time a Cyrtia, Oyrtina (Davidson, Quarterly Geological Journal, Vol. ix, pa. 355, pi. 15,
f. 6 - 9); but it appears to me that the species figured in the Geology of Russia is distinct from the
Chinese specimens figured by Mr. Davidson.

@44

PALEONTOLOGY OF NEW-YORK.

Spirifer disjunctus : Davidson, Quar. Jour. Geol. Society, Yol. 9, pa. 354, pi. 15, f. 1 - 5. 1853.

« verneuilii : M'Coy, Brit. Pal. Fossils, p. 376. 1852.

“ disjunctus: Murchison, Siluria, 2d edition, p, 299, f. 4. 1859.

«« barumensis: Sowerby, MSS.; Salter, Jour. Geol. Society, Yol. 19, p.480.

Spirifera disjuncta: Davidson, Monograph Brit. Dev. Brachiopoda, p. 23, 1864.

Delthyris perlata .- Conrad, Ann. Rep. on Palaeontology of New-York, p. 54. 1841.

•« chemungensis : Conrad, Jour. Acad. Nat. Sciences of Philadelphia, Yol. 8, p.263. 1842.

<< disjuncta ? Phillips; Hall, Geol. Rep. 4th Dist. New-York, p. 269, f. 3. 1843.

<< cuspidata: Hall (not Martin), lb., p. 270, f. 1. 1843.

«< acanthota: Id.. Ib., p. 270, f. 2, 2 a. 1843.

“ inermis : Id. Ib., p.271, f. 4, 4 a; p.270. 1843.

Compare Spirifer whitneyi, Hall, Geology of Iowa, pa. 502, pi. 4, f. 2. 1859.

Shell variable in shape, semioval, semicircular or subrhomboidal 1 hinge¬
line usually as long as the width of the shell (rarely shorter), with the
cardinal angles slightly rounded, moderately or extremely extended
into long attenuated or mucronate points. Valves convex, or more or
less gibbous : entire surface, including mesial fold and sinus, plicated.

Ventral valve more or less convex, usually with a regular convexity on
the sides, but sometimes concave between the margins of the sinus and
the extremities. The sinus is more or less deeply concave, rarely quite
shallow, usually rounded but sometimes angular in the bottom, and
the margins clearly defined : beak elevated and produced, moderately
incurved over the area, which is flat or concave and of variable height.
The fissure is often partially closed by an arching pseudo-deltidium.

Dorsal valve moderately convex, sometimes a little concave towards the-
cardinal angles : mesial fold distinctly defined, usually of moderate
elevation and convexity, sometimes, subangular, and often divided by
a furrow down the centre : area very narrow.

Surface marked by from twenty to., forty or more simple rounded or
subangular ribs on each side, with nearly equal interspaces. The mesial
fold and sinus are each marked by about ten, sometimes twelve or
fourteen ribs near the front, which proceed from the bifurcation of two
Or three at the apex of each valve*.. When the shell is perfectly pre¬
served, the entire surface is marked by fine contiguous concentric
striae.

♦ Mr. Davidson says the increase is by intercalation ; but strictly this is rarely true of our specimens.

SPIRXFERiE OF THE CHEMUNG GROUP.

S45

The interior of the ventral valve shows the presence of more or less
extended dental lamellae : these are sometimes short and divergent,
enclosing a pretty broad muscular space, and often less divergent and
reaching nearly to the front of the shell ; and the muscular imprint is
sometimes pushed very far forward, and enclosed in a narrow space.
The muscular markings are often well defined in the casts, but in some
of them the markings of the ribs are shown over the muscular space.
The fissure is closed for one-third or more of its length from the apex by
a thickened plate or septum, with the rostral cavity more or less ex¬
tended behind it. In casts of the dorsal valve, we have the imprints of
the cardinal muscles and the cavities made by the bases of the crura.

This species has been recognized by European authors as Spirifera
disjuncta, and identical with S. verneuili, etc., as shown in the synonymy.
From comparison of ours with European specimens of that species in my
own collection, I can find no important distinction ; indeed the differences
in a few indviduals are not as great as those among our own specimens
recognized as belonging to the same species. It is regarded in Europe as
a very characteristic Middle and Upper Devonian species ; but in the
State of New-York, it is not known out of the Chemung group.

The Spirifera whitneyi is from beds of the age of the Hamilton group
in Iowa, and bears a very close resemblance to the S. archiaci as figured
in the Geology of Russia (ut cit). Some specimens of this form more
recently examined^ show a variation in aspect and general characters
which induce the conclusion that this one also is only a variety of S.
disjuncta, occurring at a lower horizon in the west than yet known in
New York ; thus giving it a vertical range equal to the Middle and Upper
Devonian of Europe.

I have heretoforef given some of the varieties of this species under
distinctive names, which have been abandoned after the study of larger
collections. I have also been able to satisfy myself with regard to the

* Specimens received from Mr. 0. St. John, of Waterloo, Iowa,
t Geological Report of the Fourth District of New-York, pp. 270, 271.

24©

PALAEONTOLOGY OF NEW-YORK.

identity of our species with those given by Sowerby and Phillips under
different designations, and have adopted the synonymy given by David¬
son, De Koninck, De Verneuil, Sowerby and others, under this species.
It has a wide geographical extent and great vertical range in the Che¬
mung group, and presents a variety of form and proportions which it
would be quite impossible fully to illustrate* The more important phases
I have endeavored to show in the figures on Plates xli and xlii : the
greater number of these are of casts.

The predominating characters of the casts of ventral valves are shown in 1 - 4
and 7, 8, 10, 13, 19 & 20 of Plate xli.

In figure 5 we have a form where the dental lamellae are extremely extended
towards the front of the shell, and fig. 15 is somewhat similar. This extreme cha¬
racter has been observed more frequently in the small gibbous forms, but it like¬
wise occurs in the large and less convex ones. The extremely extended forms with
mucronate extremities are less common than the others; but in some localities,
nearly all the individuals found have that character.

The form represented by figures 19 and 20 of Plate xli, and by figure 19 of
Plate xlii, is that described by Mr. Conrad as Delthyris perlatm*, and is cited
by Mr. VanuxemI as Delthyris prolata. The Delthyris chemungensis\ of Conrad
is thus described :

“ Delthyris chemungensis. Triangular, ventricose, with numerous slender ribs;
upper valve with the mesial fold wide, convex or rounded and ribbed like the
sides, except that the ribs bifurcate, about thirteen in number; area of inferior
valve very wide; mesial fold profound. Length, one inch; width, one inch and
a half. Locality, Chemung-narrows, New-York : in Devonian shale.”

There is no other Spirifer known to me in the locality cited, or in the Chemung
group, which will correspond with the description, except the Spirifer a disjuncta.

One of the remarkable features in the dorsal valve is the duplication of the
mesial fold, or the marked longitudinal furrow along the centre. This feature can
be observed in all gradations; and while in some localities there is scarcely a
specimen to be found having this character, in other places it prevails in the larger
number of individuals; This depression is usually narrow and sharp, but in some
individuals it is broader, as shown in figures 13, 15, 16, Plate xlii. The fold is

* Annual Report on the Palaeontology of New-York, p. 54. 1841.

f Report on the Third Geological District of New-York, pp. 179, 185.

t Journal of the Academy of Natural Sciences of Philadelphia, Vol. viii, p.263. 1842.

SPIRIFERJE OF THE CHEMUNG GROUP.

very rarely narrow and angular, as shown in fig. 17. The easts usually preserve
more or less distinctly the marks of the plications, and are rarely almost smooth.

The following figures are those which were given in the Geological Report of
the Fourth District, and have not been repeated in the plates. They offer some
little variety of form and proportions from those' already referred to.*

Geological formation and localities. This species occurs in the Chemung group
throughout New-York, and in that part of Pennsylvania adjacent to the south¬
western counties of this State. Among the particular localities may be mentioned
several places in Broome county; Cayuta creek in Tompkins and Tioga counties;
Factoryville, Cheipung-narrows, Chemung, Paintedpost and Elmira, in Chemung
county; near Angelica, Van demark’s creek, Clean, and other places in Allegany
county; Troupsburgh, near Bath, and elsewhere in Steuben county; at Sala¬
manca, Allegany station, NeW-Albion, Napoli, Randolph, Connewango, Great-
valley, Leon, etc. in Cattaraugus county; at Ellington, Twenty-mile creek, and
other places in Chautauque county.

In Pennsylvania, I have collected this species -from Covington and localities
to the north of Blossburg, and Mr. R. P. Stevens has sent me specimens from near
Bradford. It is abundant at Meadville and vicinity.

* The illustrations in wood cuts were given in the Geological Report of the 4th District as 1 Dd-
thyris cuspidata, 2 and 2a; D. acanthota, 4 and 4a; D. inermis.

248

PALAEONTOLOGY OF NEW-YORK.'

Spirifera alta ( n. s.).

PLATE XLIII.

Shell semipyramidal, triangular in form from the ventral or cardinal sides,
and semioval in a dorsal view ; cardinal line equalling the greatest
width of the shell, and sometimes produced in short auriculate exten¬
sions : surface plicate.

Ventral valve extremely elevated, subtriangular ; height and width
about as three to five : sinus broad rounded in the bottom, and ex¬
tended from beak to front. Area very large, triangular, acute, inclining
forward or nearly rectangular to the general plane of the dorsal valve,
strongly striated vertically. The fissure is large but comparatively
narrow, being more than twice as high as its width at the base, and is
closed by a concave transverse septum for two-thirds of its length from
the apex. The margins of the fissure are grooved, as in other species,
for the reception of a pseudo-deltidium.

Dorsal valve large, somewhat semioval, depressed-convex or but mode¬
rately convex at the sides, with a broad and well-defined mesial fold :
the cardinal angles are sometimes obtusely rounded or truncate, and
sometimes a little produced. Area comparatively wide, and strongly
striated vertically.

Surface of the dorsal valve plicated by about twenty-five to thirty or
more low rounded ribs on each side of the mesial fold : in the casts,
half the number are often quite obscure towards the extremities. The
mesial fold and sinus are plicated, and the ribs are faintly preserved,
or sometimes barely visible in the casts. In casts of the ventral valve,
the plications are scarcely preserved except towards the margin.
There is a distinctly ovate muscular impression in the ventral valve,
with indications of a low crest in the centre ; while the dental lamellae
are only extended for half the length of the muscular space, yet they
continue to form the walls of the fissure to its base ; but we have no
evidence of the teeth, except in the character of the teeth-sockets in

SPlRIFERiE OF THE CHEMUNG GROUP.

249

the opposite valve. The casts of the dorsal valve show the marks of a
deeply striated cardinal process and elongate teeth-sockets, while the
muscular impressions are sometimes strongly marked.

This species is known to me only in the condition of casts of the interior, and
its usual appearance is illustrated in the figures on Plate XLin. Its general aspect
is much like that of the European Spirifera cuspidata, Martin; but there are
important differences by which it may be distinguished : these are, the plications
on the mesial fold, the larger area of the dorsal valve, and the shorter extension
and greater divergence of the dental lamella} by the sides of the muscular im¬
pression. Some of these characters, I conceive, are not likely to change to those
shown by 8. cuspidata. In the concave septum closing two-thirds of the fissure
from above, it resembles that species as described by Prof. M‘Coy, who mentions
the presence of a “ deep-seated pseudo-deltidium.”* In one of the figures given by
Mr. Davidson and referred with doubt to this speciesf, the cast shows a tubular
perforation in the filling of the fissure; and a gutta percha impression from the
same shows the mark of a foramen, but there is no positive evidence of a septum
which is so conspicuous in our specimens, and which I suppose to be the feature
characterized by Prof. M‘Coy as a deep-seated pseudo-deltidium. In our species, I
have not been able to discover any corresponding perforation; the only indication
of this being the semicylindrical impression along the centre of the fissure (in the
cast), showing a callosity of the septum behind the exterior wall.

In form and proportions, this species bears a very close resemblance to one in
the Waverly sandstone of Ohio, and also to one in the fine-grained sandstone of
Burlington, Iowa; but of neither of these have I the necessary material for satis¬
factory comparison. It differs from the S. subcmpidata% of Schnur in the plications
on the mesial fold and sinus, and the wider area of the dorsal valve; and also in
the same characters it differs from the 8. textns of the sandstone and argillaceous
limestone near New- Alb any, Indiana.

Geological formation and locality. This fossil occurs in finegrained ferruginous
sandstone of the Chemung group, at Meadville, Pennsylvania ; associated with
Spirifera disjuncta , 8. prcematura, 8 treptorhynchus chemungensis var. pectinacea,
Chonctes muricata , C. 9, Productus ( Productella ) lachrymosa , etc.

* * * * * . triangular opening very large, often displaying the internal deep-seated pseudo-

deltidium (without perforation, leaving the only opening to the shell at its base) ; * * *. McCoy,
British Palaeozoic Fossils, p. 426.

t Monograph of British Carboniferous Brachiopoda, Plate ix, f. 1 & 1 a.

t Spirifer subcuspidatus, Hall, Geological Report of Iowa, pa. 646, pi. 20, f. 6, is a distinct species,
and apparently identical with S.-textus, Hall, Tenth Report on the State Cabinet, p. 160 : 1857. See
Nineteenth Report on the State Cabinet, for remarks on this, species.

[Paleontology IV.] 32

@5©

PALAEONTOLOGY OF NEW- YORK.

8pirifera praematura ( n. s.).

PLATE XXXII.

Compare Spirifer pseudolineatus, Hall, Geology of Iowa, pa. 645, pi. 26, f. 4. 1859.

Compare Spirifer hirtus, White & Whitfield, Proc. Bost. Nat. Hist. Society, Yol.viii, p. 293. 1862.

Shell transversely oval or suborbicular ; hinge-line shorter than the
width of the shell, with the cardinal angles rounded : surface not
plicate.

Ventral valve moderately convex, sometimes sub ventricose, with abroad
and rather shallow sinus, the margins of which are not strongly de¬
fined : beak moderately elevated and incurved ; area small, the lateral
margins undefined.

Dorsal waive regularly and moderately convex, with a scarcely defined
mesial elevation, which becomes broad and more conspicuous towards
the front of the shell.

'Surface marked by numerous regular subimbricating concentric lines,
crossed by coarse radiating strise : these are often continuous, but
always more conspicuous on the concentric lines or ridges, sometimes
giving a pustulose appearance to the surface.

The casts or partial casts sometimes preserve the radiating strise more
distinctly than the concentric lines. In the perfect shell, the radiating
striae were doubtless produced from the concentric ridges into minute
spinules.

The casts of the ventral valve show the cavities of rather slender but
sometimes considerably elongated dental lamellae. The muscular area is
somewhat narrow, and only rarely are the parts well defined. There is
always a longitudinal impression indicating a median crest or low septum
from the apex of the rostral cavity.

The condition of the specimens is not such as to enable me to give a full de¬
scription of the species. They are either casts in friable ferruginous sandstone, or
partial casts preserving some of the surface markings; while some specimens in a
shaly bed have been macerated till the surface characters are obscured. It clearly
belongs to the group of Spirifers of which /S. lineata is the type, and is closely

SPIRIFERiE OF THE CHEMUNG GROUP.

251

allied- to S. pseudolineata of the Keokuk limestone. The specimens of S. hirtus in
my possession are very imperfect, and do not afford fair means of comparison; but
I am much inclined to the opinion that an examination of a larger number of the
Burlington species with ours will prove them identical. Both are known to me
only in casts, and those from the western locality do not offer sufficient grounds for
a satisfactory specific distinction. I shall nevertheless indicate this as distinct for
the present; hoping to obtain material to show the identity of 8. pseudolineata,
S. hirtus , and 8. prmmaiura.

This species is associated with great numbers of 8. disjuncta, Streptorhynchus
chemung ensis var. pectinacea , Pro ductus lachrymosa var., Chonetes muricata, C.
setigera , and a Chonetes with about fifty fine striae, with regular intermediate
puncta as in C. illinoisensis.

The lower line of figures on Plate xxxn are of this species in its condition of
casts, the smaller one partially retaining the shell.

The small figure above (fig. 32) is the ventral valve of a young individual, having
the beak unusually extended and the concentric undulations strongly marked.

Figures 32 and 33 are dorsal valves of this species.

Figures 34 and 35 are the casts of ventral valves, showing, in the space between,
the dental plates and extent of muscular impression.

Geological formation and locality. In the Chemung group at Meadville, Pa.,
and among specimens lately received from Oil Creek, associated with Spirifera
disjuncta.

Some important considerations are suggested by the study of Spirifera prcemor
tura, Spirifera alta , and their associates.

The species which I have here designated as Spirifera prcematura exhibits no
external markings which enable one to say that it is distinct from 8. hirtus of the
sandstones at Burlington, Iowa; nor does it present differences from 8. pseudo-
lineata which may not be reconciled with geographical influences, and with a
habitat nearer to the shore line and the essential absence of calcareous matter in
the sediments deposited. Its associates, however, are of different species from those
in the western locality; but still among the more conspicuous of these is Spirifera
alta, Productus lachrymosa var., and Chonetes muricata , which have a carboniferous
aspect; and were it not for the presence of Spirifera disjuncta and one or two
others, the general aspect of the fauna might be termed carboniferous.

If again we look at the characters of Spirifera alta , an analogue or representa¬
tive of Spirifera cuspidata, we have many points of similarity with one or more
species in the rocks of the West and Southwest which are usually referred to a

PALAEONTOLOGY OP NEW-YOKK.

higher position. The high area and the transverse concave septum, which is not a
true pseudo-deltidium, allies it with Sjpirifera textus, in which we find similar fea¬
tures. In the 8. alta there has probably been an external convex pseudo-deltidium,
and between this and the septum closing the fissure there has been a narrow space.
This septum, which is an extension of the dental lamellse, has been thickened or
expanded on the inner side, as shown by the casts of the ventral valve; and in
several specimens there is a narrow semicylindrical depression extending nearly to
the beak of the valve.

In comparing this species with Sjpirifera textus , we find similar conditions, or
more properly an extension or amplification of the same features. In that species
there is a convex arching pseudo-deltidium, though rarely preserved in the speci¬
mens. Beneath this there is a concave septum, and upon the inner face of this there
is a tubular callosity; or, in other words, the inner laminte of the septum become
fistulous, and enclose a cylindrical or subcylindrical space, which extends from the
base of the septum to near the apex of the valve*. But more usually the laminae
appear to be separated, and, extending inwards, are recurved, their edges some¬
times joining to form a tube; but more frequently perhaps the margin of each one
is recurved upon itself, leaving the tube with a slit along the lower side. In some
instances, however, these extensions from the inner face of the septum continue to
the bottom of the cavity, and, joining the external shell, leave a quadrangular tube
instead of a cylindrical one.

It is evident from what has been said, as well as from the illustrations given,
that there is a near approach to this character of 8. textus, or an incipient step
towards it, in. Sjpirifera alta ; but the feature has not become fully developed. We
have the concave septum with a semicylindrical callosity on its inner face, but this
ridge has apparently remained solid. The concave septum, however, must not be
confounded with the pseudo-deltidium : the latter is apparently an independent
growth of shelly (or sometimes perhaps scarcely solid shell ) matter, forming an
exterior plate from the apex of the fissure, covering to a greater or less extent the
opening, but apparently not connected with, nor a part of the dental lamellse or
substance of the area, while the septum is an outgrowth or lateral extension of the
dental plates.

In the case of Sjpirifera alta, the extension of the septum is so great, that when
connected with the general form of the shell, its nearest analogue appears to be
Sjpirifera textus ; which, so far as I can now determine, is identical with the one
described by me as 8. subcusjpidatus in the Geological Eeport of Iowa. The latter
is a carboniferous species from the Keokuk limestone, and closely allied to the

* It is upon this feature, or one of similar character, in its full development, that I understand Prof.
Winchkll proposes to found the Genus Syringothyris.

SPIRIFERiE OF THE CHEMUNG GROUP.

253

Spirifera cuspidatus of Europe; and the Chemung species thus reminds us of the
Carboniferous one, or has a carboniferous aspect.

If, in its full development, the presence of a septum and internal tube be re¬
garded as of generic value, then we have in Spirifera alta the same appendages
in part, or in a partially developed condition; the distinct tube only being wanting.
But had we the means of examining the internal characters of the ventral valves
of all the species of Spirifers, we should probably find gradations from the solid
filling of the rostral cavity, with a greater or less extension of shelly matter in the
form of a septum in the fissure occupying a narrow space in its apex, till we reach
the development observed in S. alta and S. textus.

To a considerable extent, we are able to prove this supposition. In the separated
valves of Spirifera radiata of the Clinton and Niagara groups, there is a filling of
the rostral cavity, and a thickening of the dental lamellae which are extended for
half the length of the valve. The narrow median crest of the muscular impression
is expanded and thickened towards the apex of the valve, but there is no evidence
of a septum. In Spirifera niagarensis there is a filling of the rostral cavity and a
thickening of the dental lamellae, which are distinctly separate, but no appearance
of a septum; and there is a low median crest in the muscular impression.

In the Lower Helderberg group, the Spirifera macropleura has the rostral
cavity filled to a greater or less extent, and the dental plates extremely thickened
at their bases; while there is an obscure low median crest in the muscular impres¬
sion, which sometimes becomes thickened and expanded above; and occasionally
there is a little filling of the upper part of the fissure, resembling the incipient
stages of growth of the septum. In Spirifera cycloptera the rostral cavity is more
or less filled and solid, with diverging dental lamellae; while the crest dividing
the muscular impression is very unequally developed, and there is no appearance
of a septum. In Spirifera perlamellosa the rostral cavity is filled to a greater or
less degree, the dental lamellae are short and strong, and there is a sharp elevated
median crest or septum in the muscular impression; but ( there is no indication of
the transverse septum. In Spirifera octocostata the dental lamellae are thickened,
and there is a vertical septum reaching from the apex of the rostral cavity to the
base of the muscular impression. In Spirifera marylandica of the Oriskany sand¬
stone, there is sometimes a partial filling of the rostral cavity, with a reversed
conical crest in the upper part of the muscular area. Spirifera arenosa has strong
dental lamellae; a filling of the rostral cavity in old shells; a low crest dividing
the muscular impression, which becomes thickened in its upper part; a distinct
pseudo-deltidial covering of the fissure, but no transverse septum.

Among the Spirifers of the Upper Helderberg group, Spirifera acuminata has
usually only a moderate thickening of the rostral portions, divergent lamellae of

254

PALEONTOLOGY OP NEW-YORK.

moderate strength, and no transverse septum. In Spirifera oweni the rostral cavity
is partially filled; the dental lamellee are thickened; there is a reversed conical
callosity at the apex of the cavity, the attenuated continuation of which divides
the muscular area : the fissure is closed by a thickened plate or septum for one-
half its length from the apex. In Spirifera raricosta the rostral cavity is filled;
the dental lamellee are short and thick; the fissure is closed by a solid filling for a
part of its length, while from the bottom of the cavity there rises a thin vertical
septum which extends to Avithin one-third the length of the front of the valve. In
Spirifera gregaria the rostral cavity is more or less filled with thickened dental
lamellae, and sometimes the incipient growth of a transverse septum is perceptible.

In several of the Spirifers of the Hamilton group the septum is well marked,
while in others there is an incipient development of the same character. In Spiri¬
fera granulifera the upper part of the rostral cavity is filled with shelly matter,
and this apparently encroaches upon the space below with the advancing age of
the shell. The fissure becomes partially filled, and a thickened plate projects a
little in advance of- the solid filling of the beak; leaving behind it, or on the inner
side, a conical cavity directed towards the apex of the shell. The muscular area
is divided by a low longitudinal' crest, which, in its extension towards the beak,
becomes wider, and is often much thickened towards its junction with the solid
shelly matter filling the rostral cavity. Looking at this from the apex of the shell,
it presents a subconical form, and is more or less abruptly attenuated towards the
centre of the muscular impression. This callosity sometimes becomes so prominent
as to produce an emargination or indentation in the apex of the cast, and a similar
feature is sometimes observed in the casts of other species of Spirifera.

Regarding the S. granulifera alone, there is little to attract especial notice,
beyond the general fact of a partial filling of the rostral cavity with the exterior
portion prolonged between the dental lamellae, but so much thickened as scarcely
to merit the term septum. In Spirifera marcyi this development of shelly matter
has the character of a true septum, closing one-third or more Of the length of the
fissure from above, aad leaving an open rostral cavity behind it. In Spirifera
medialis and S. macronota there is a thickened transverse septum extending from
one-third to one-half the length of the fissure from the apex, and this feature is quite
independent of the pseudo-deltidium. The rostral cavity lies behind this septum,
and may be open or free from the accumulation of shelly matter to a greater or less
extent; but it is not uncommon to find nothing more than a thickening of the base
of the dental plates and a partial filling of theP'Yostral cavity. This condition
changes to a greater or less extent during the growth of the shell; but a partial
filling of the fissure at its apex is probably more common than otherAvise, parti¬
cularly in full-grown individuals.

SPIRIFERiE OF THE CHEMUNG GROUP.

‘253

In the Spirifers of the Carboniferous rocks which I have been able to examine,
this feature is variably developed. In S. plena of the Burlington limestone, the
septum extends for more than half the length of the fissure; while it is less de¬
veloped in 8. grimesi , and scarcely at all in 8. increbescens and 8. opima.

The shell texture of Spirifera is usually regarded as fibrous, and this is true
of all those I have examined in the older strata, though in some of the species of
the higher formations, characters have been observed, which, with imperfect means
of investigation, seem to be irregularly distributed ducts penetrating the shell. I
have not been able to examine the shell of Spirlfera alta , to learn whether any
changes have taken place in its texture, not observed in other species of Spirifera;
but in 8. textus,* where the septum and tube are developed, the shell is penetrated
by numerous pores or ducts which are somewhat coarser than the ordinary punctate
structure of some other Brachiopoda; and though not in actual contact, are often
arranged in regular order and frequently in close proximity to each other, not
essentially differing from those ef Spiriferina as given by Dr. Carpenter. The
intermediate spaces have a distinctly and beautifully fibrous or prismatic structure,
differing in no respect from ordinary Spirifers or Athyris.

It should be observed, in this connexion, that the dental plates, both in Spiri¬
fera alta and 8. textus , reach to the bottom of the cavity, and partially surround
the muscular impression, which is precisely like that of ordinary Spirifers.

In these remarks, I have not intended to express an opinion of the generic value
of certain characters; but merely to show, as it appears to me, a gradual or suc¬
cessive development in certain parts, which finally becomes so wide a departure
from the characters of typical forms of Spirifera, as to deserve especial attention.
Nor can we deny that this progressive development of the septum and its mo¬
difications keeps pace and corresponds with the geological succession; reaching its
extreme state, so far as now known, in the Carboniferous period, where it is con¬
nected with a punctate texture of the shell.

In our investigations of the Chemung group in its more easterly extension in
the State of New-York, it has proved, throughout the greater part of its thickness,
to be comparatively barren of animal organisms, though often containing an abun¬
dance of the remains of land vegetation. As we progress westerly, the coarser
sediments have given place to finer materials, or are more or less intercalated with
shales or slialy and calcareous beds, while the coarser beds exhibit less resemblance
to shore deposits, and we find an increasing number of animal remains both of the

* In this species, and in Spiriferina spinosa of Norwood & Pratten, the pores or ducts are un¬
equally distributed ; being, in some parts of the shell, closely crowded, while in others they are more
distant and often following the line of growth, though frequently irregularly disposed.

Prof. W inchell remarks, of the proposed Genus Syringothyris, that “ the shell is impunctate
in all conditions and under high powers.”

£56

PALAEONTOLOGY OP NEW-YORK.

Bracliiopoda and Lamellibranchiata, though there are usually few of any other
class. But these are not equally distributed, either vertically or horizontally.

There is one fact, however, which can scarcely fail to impress the collector of
fossils in this group of strata; which is, that in going westward, certain forms
which are abundant in some localities become rare or disappear altogether, so that
sometimes localities not very far removed from each other give almost entirely a
different set of species. Certain species which are common in Schoharie, Broome,
Tioga and Chemung counties, I have not seen in Cattaraugus and Chautauque
counties; while many species which are common in the western counties are quite
rare' or unknown to me in Tioga, Tompkins, and the counties east of these. Al¬
though we may attribute this view in some part to our imperfect collections, it is
nevertheless in a great degree true.

Reasoning upon the nature and origin of the sediments, as well as upon these
observed conditions, we might expect to find a changing fauna as we recede from
the ancient coast line furnishing these materials, and which were then swept
into the wide ocean to the westward. While in some of the more eastern localities
we find species of the Hamilton group apparently mingling with those of the
Chemung group, the higher beds of Cattaraugus and Chautauque counties give
us an association of fossils having a more carboniferous aspect than those of the
higher beds in the eastern counties of the State.

As we proceed farther to the westward, these differences become more and more
marked; and in connexion with the contemporaneity of the sedimentary forma¬
tions in distant localities holding dissimilar species, we must consider the gradual
lithological changes which have affected the character of the fauna. There can be
no longer any question that the higher arenaceous and argillaceous formations of
New-York and the adjacent portions of Pennsylvania and Ohio, when traced in a
southwesterly direction, become intercalated with calcareous bands; while the
coarse sediments give out, or are replaced in a great degree by calcareous or
argillo-calcareous deposits, containing some of the same species of fossils, with
an accession of other forms adapted to the changed conditions of life.*

In the extreme southwestern extension of the Pakeozoic series, the interval
between the Upper Helderberg group and the Coal Measures, which in the North
is occupied by the Hamilton, Portage, Chemung and Catskill formations con¬
stituting so marked a feature in New-York, Pennsylvania and Ohio, is there filled
by calcareous accumulations that have been considered as belonging exclusively to

* I have already shown a similar condition existing at the period of the Coal Measures ; where some
calcareous bands of a few feet thickness in Ohio, Pennsylvania and Virginia, become expanded so that,
together with the associated calcareous shales, they embrace almost the entire formation towards the
Rocky Mountains and in the far west and southwestern regions of the United States and in Mexico.

SPIRIFERiE OF THE CHEMUNG GROUP.

237

the Carboniferous system; so that the limestones of this age are supposed to rest
directly upon the Silurian rocks, or with a thin intervening Devonian limestone.
But we can scarcely suppose that the lapse of time required for the northern
sedimentary formations remained unrecorded by fauna of some kind, while the
interval is filled by an accumulation of a thousand or more feet of calcareous
deposition.

It here becomes a matter of grave interest to decide what shall constitute the
fauna Devonian , and what may be regarded as th % fauna Carboniferous. Looking
at the great number of Productus (for although I have used the term Productella
as indicating certain distinctions, the fossils are in all essential respects Productus)
in the central and western portions of the State, they alone would give a Carbo¬
niferous aspect to the fauna. But when we find Spirifera disjuncta , and other fos¬
sils of acknowledged Devonian age, we instinctively allow less than the due
importance to the Carboniferous evidence. Nevertheless we are forced to admit,
even within the State of New- York, a gradual diminution of the Devonian type,
and an augmentation of the carboniferous type, in the same beds as we go westward.
And finally, we have every reason to believe that in those sedimentary formations,
between the Hamilton group and the Coal measures in the east, and between the
same group and the Burlington (Carboniferous) limestone in the west, the Devo¬
nian aspect of the fauna on the one hand, and its Carboniferous aspect on the
other, are due to geographical and physical conditions, and not to difference in
age or chronological sequence of the beds containing the fossils.

This view of the case, which is consonant with the facts observed, will account
for the coming in of forms which we term Carboniferous, as we pursue our inves¬
tigations to the westward.

The same opinions seem gradually to be obtaining ground in Great Britain, but
the idea is not new with me. It is now about fifteen years since I expressed simi¬
lar opinions in a review and comparison of the Palaeozoic groups and systems of
Europe and America.

In some of the concluding paragraphs of the eighteenth chapter of Foster &
Whitney’s Report on the Lake Superior Land District, after having made a com¬
parison of the species cited as common to the Silurian and Devonian and to the
latter and the- Carboniferous system, I have said :

“ The arenaceous and argillaceous deposits, which we trace uninterruptedly over
so wide an area, and which present to us such gradual and almost imperceptible
changes in the fauna when studied' continuously, would, if broken up and isolated
so that they could not be traced consecutively, present the same phases which are
exhibited by the systems in Europe to which they are related. From all these
facts there seems to be but one conclusion, and that is, in the British Islands par¬
ticularly, either there are remarkable exceptions to the general law in the con¬
tinuation of species from one to another, or there is no foundation for a dis¬
tinction between the Devonian and Carboniferous systems.”

[ Paleontology IV.] 88

S58

PALAEONTOLOGY OF NEW-YORK.

SfJBGENUS AMBOC(ELIA.

In the Thirteenth Report on the State Cabinet*, I proposed the name
Amboccelia as a generic designation for several species of fossils, of which
Orthis umbonata of Conrad was regarded as the typical form. This fossil
bears much resemblance to Spirifer urii, Fleming = S. unguicidus , Phil¬
lips ; but I do not regard the identity of the two as demonstrated at the
present time. The European species has been placed by King and M‘Coy
under the Genus Martinia of the latter ; the typical species of which,
mentioned by M‘Coy its author, are Spirifer a decora, S. elliptica and S.
glabraf. These European species are not more nearly related to Orthis
umbonata than are some of our own species, in which we observe the
ordinary characters of the Genus Spirifera.

But there are a few points* of distinction between these and the form
I have proposed to designate Amboccelia. Whether these are of generic
importance, may remain a question ; but they differ from those on which
the Genus Martinia was founded, and the allied species Spirifera urii =
S. unguiculus was only included under the genus at a later period^: ; so
that if that one be proved generically distinct from Spirifera, it could
not supersede the type of the genus indicated by M‘Coy.

In the ventral valve, the thickened margins of the fissure are produced
in short strong teeth ; but there is scarcely any extension of the dental
plates into the cavity, or below the inner margin of the fissure.

In the dorsal valve, the bases of the crura continue attached to the
inner surface of the valve for more than one-third of its length, before
becoming free. There is a lateral projection from these crural bases,

* Thirteenth Annual Report on the State Cabinet of Natural History, pp. 71 & 72. I860,

t Synopsis of the Carboniferous Fossils of Ireland, p. 139(1844). Mr. Davidson, in his Monograph
of British Carboniferous Brachiopoda, places S. decora as a variety of 5. glabra, and S', elliptica as a
variety of S. lineata ; while Martinia oblata, M. obtusa and M. symmetrica are regarded as simply
tarieties of Spirifera glabra, and Martinia mesoloba and M. stringocephala as varieties of S. lineata.

X British Palaeozoic Fossils, p. 377. 1855.

AMBOCCELIA OF THE HAMILTON GROUP.

259

bounding the teeth-sockets. The cardinal process is elongate, lying be¬
tween the crura, and is distinctly bifurcate or bilobed at the outer ex¬
tremity as in Cyrtina. The muscular impressions are below the middle
of the valve, often near the front, and are usually distinctly quadruple.
The dorsal valve being depressed-convex, flat or concave, the spires lie
in the cavity of the ventral valve : no peculiarity has been observed in
those appendages.

With these remarks, I shall for the present leave the following species
under the designation of Amboccelia.

Amboccelia umbonata.

PLATE XLIV.

OrtJiis umbonata : Conrad, Jour. Acad. Nat. Sci. Philadelphia, Vol. viii, pa. 264, pi. 14, f. 21.

“ “ : Conrad; Hall, Tenth Report on the State Cabinet, p. 167. 1857.

Amboccelia umbonata : (Conrad sp.) ; Hall, Thirteenth Report on State Cabinet, pp. 71 & 72. 1860.
Orthis nucleus : Hall, Geol. Report Fourth District, pp. 180 8c 181.

Amboccelia nucleus : Hall, Thirteenth Report on the State Cabinet, p. 71.

Shell plano-convex, somewhat semiorbicular or obliquely subconical,
rather wider than long ; hinge-line equal to the width of ' the shell or
rarely a little less, the cardinal extremities rounded.

Ventral valve gibbous, with the umbo extremely elevated and- a com¬
paratively large incurved beak : mesial sinus distinct, extending from
the beak to the front of the shell ; the area rather large, arched and
of considerable height, extending conspicuously to the cardinal ex¬
tremities. The fissure is partially arched over by a pseudo-deltidium.
Dorsal valve semielliptical, depressed-convex in the upper central por¬
tions, concave below the middle and at the sides : apex scarcely ele¬
vated above the hinge-line ; area equalling the thickness of the shell.
There is no perceptible mesial fold, furrow or impressed line in this
valve.

Surface marked by very fine radiating and concentric striae ; the latter
sometimes becoming crowded, lamellose and imbricating towards the
front of the valves.

The interior of the ventral valve shows a comparatively strong tooth
on each side at the base of the fissure, which is continued in a callosity

2©0

PALAEONTOLOGY OP NEW-YORK.

along its inner margins. ’I have not observed any extensions of dental
lamellse into the cavity of the shell. (There appear to be no proper dental
plates, but simply a thickening of the margins of the fissure.) The mus¬
cular impression is in the upper part of the valve.

The interior of the dorsal valve usually presents a quadruple muscular
imprint towards the front of the shell, with the bases of the crura at¬
tached along the inner surface for a considerable distance, and a bilobed
cardinal process.

The casts of the ventral valve sometimes show a median depression
in the upper part, and impressed lines slightly limiting the muscular
imprints, as if made by a blunt ridge in the shell ; but more frequently
there are no marks of this kind.

The small shell in the Mar.cellus shale which I originally designated as Ortkis
nucleus , is, I conceive, only a smaller form of this species, in which the median
sinus is often very conspicuous, being narrow and sharply depressed. It sometimes
occurs in the compact calcareous beds of the Hamilton group in great numbers, of
a similar diminutive size; and in these the dorsal valve is more convex than usual.
In the shales of the Hamilton group this fossil is often extremely abundant, and
in a fine state of preservation. The illustrations of the interiors of the valves are
of specimens from this group.

2 3 4 -5 6

Figs. 1, 2, 3. Dorsal, ventral and profile views of Ambocce.Ua umbonata. natural size, from the shales of
the Hamilton group.

Fig. 4. The interior of the ventral valve showing foramen, area, etc. enlarged.

Fig. 5. Interior of the dorsal valve enlarged, showing the foveal plates, dental sockets, and the quadri¬
partite muscular impression; the valve slightly distorted.

Fig. 6. A similarly enlarged dorsal valve, showing some variations from the preceding.

Geological formations and localities. In the Marcellus shale, at Avon and other
places. In the Hamilton group, it occurs everywhere from Schoharie county to Lake
Erie : among the principal localities may be mentioned the shores of Seneca and
Cayuga lakes; the shore of Canandaigua lake; Geneseo, Moscow, York, Covington,
Darien; and on the shore of Lake Erie at Hamburgh and Eighteen-mile creek.

AMBOCCELIA OF THE CHEMUNG GROUP.

2®1

Amboctelia umbonata, var. gregaria.

PLATE XLIV.

Orthis unguiculus : ( Phillips sp.) ; Hall, Geol. Report Fourth District, pp. 267, 268. 1843.

Ambocalia gregaria ; Hall, Thirteenth Report on the State Cabinet, p. 81. 1860.

The shell occurring in the Chemung group, and indicated by me as a
distinct species of this genus, possesses so many characteis in common
with the Hamilton forms that I hesitate to continue the specific designa¬
tion.

The ventral valve is often more elongated, and the margins of the
mesial sinus are subangular. The dorsal valve is depressed convex, with
a distinct median sinus as shown in the casts. The casts of the interior
of the ventral valve show a longitudinal median crest in the muscular
impression, which is also often limited at the sides by a linear obtuse
impressed line, as if By some callosity on the interior of the shell.

Some of the specimens in the Chemung group attain larger dimensions
than any of those in the Hamilton, being often nearly half an inch in
diameter.

This form, with its convex dorsal valve, bears much resemblance to the Spirifera
urii * of Europe, which, according to Mr. Davidson, passes from the Devonian
through the Carboniferous, and occurs in the Permian system. It is described by
Mr. Davidson as having a narrow mesial furrow in the dorsal valve, which is
“ nearly flat or slightly ♦convex”. This author remarks : “The external surface,
where perfect, is covered with small spinules”. Although the shell of this fossil in
the Hamilton group is apparently in a very perfect condition, I have been quite
unable to discover any evidence of the existence of spinules or their bases, a
chai*acter observed in Spirifers allied to S. lineata.

Geological formation and localities. This variety occurs in the shales and shaly
sandstones of the Chemung group, near Binghamton, at Chemung and Chemung-
narrows; near Elmira, at Corning, Paintedpost, and along the Corning and Bloss-
burgh railroad; at Jasper in Steuben county; near Olean in Allegany county; at
Randolph, Albion, and Connewango in Cattaraugus county; Gerrytown-corners,
Cherry-creek, Ellington and other places in Chautauqua county.

*Atnjpa unguiculus, Sowerby == Spirifera unguicula, Phillips, is regarded as a synonym of N. urii.

239

PALAEONTOLOGY OP NEW-YORK.

Ambocaifa praumbona.

PLATE XL1Y.

Orthis prceumbona : Hall, Tenth Report on the State Cabinet, p. 167. 1857.

Jlmboccelia prceumbona : Hall, Thirteenth Report on the State Cabinet cited, p. 71. 1860.

Shell obliquely semiglobose or ovoid, the hinge-line less than the width
of the shell; -cardinal extremities rounded : surface without plications.
Ventral valve extremely convex or ventricose, with a shallow impressed
line which has nearly the character of a narrow shallow sinus : beak
large and incurved; area of moderate dimensions, proportionally high,
with the lateral margins not defined ; fissure partially covered by an
arching pseudo-deltidium.

Dorsal valve moderately and evenly convex, usually without mesial fold
or sinus, the cardinal extremities rounded. Sometimes there is a narrow
impressed line down the centre of the valve.

Surface essentially smooth, or marked only by concentric striae, which
are sometimes crowded into imbricating folds. In rare examples, I have
observed towards the margin a kind of punctate marking, which does
not belong to the texture of the shell, and may indicate the bases of
seta ; but the evidence is unsatisfactory.

Little is known of the interior of the valves. The cast of the ventral
valve has a large often pustulose muscular area, margined by a thick¬
ening of the shell ; without evidence of dental plates. The dorsal valve
has a bilobed cardinal process, with the bases of the crura extended along
the inner surface of the valve.

In many specimens of this shell the length and width are nearly equal, the
dimensions being about three-fourths of an inch. In some individuals there is an
extreme elongation of the ventral valve, as shown in figure 5 a of Plate xliv. Its
greater size and absence of mesial sinus, and proportionally shorter hinge-line,
distinguish this species from Ambocodia umbonata..

Geological formation and localities. This species occurs in the soft shales of the
Hamilton group, on the shores of Seneca and Cayuga lakes, and upon Canandaigua
lake. Though sometimes abundant in certain layers in a few localities, it is far from,
having the wide geographical range of the Ambocodia umbonata.

GENERA CYRTIA AND CYRTINA.

CYRTIA of Dalman, and CYRTINA of Davidson.

Following the general external characters of certain spiriferoid forms, as
described by Dalman in his definition of Cyrtia, those with semiconical
or semipyramidal ventral valves, high flat areas, with a narrow fissure
closed by a convex pseudo-deltidium, have been referred to that genus.
In some of these, there is a round perforation in the upper part of the
pseudo-deltidium ; but this feature may be present or absent, and has
not been regarded as of generic significance. The types of Dalman’s genus
are the Cyrtia exporrecta and C. trapezoidalis, both of which are Silurian
species. Since the genus was proposed, several other European fossils
have been referred to it, and some American species have been added to
the list.

As early as 1853, Mr. Davidson, in his General Introduction to the
Study of the Brachiopoda, had expressed some doubt as to the value of
Dalman’s Genus Cyrtia ; but it was not till 1858 that he proposed the
separation of certain species which had been referred to that genus, on
the ground of a want of correspondence in their parts with the typical
species of Cyrtia. These species, the Cyrtia heteroclita, C. demarli and C.
septosa, were found not only to possess the high area with closed fissure,
but also to show a peculiar modification of the dental plates of the ven¬
tral valve, and the shell-structure is likewise punctate ; while in the
types of Dalman’s genus the shell is impunctate, and the dental plates
are similar to those in Spirifer.

In Cyrtina, as described and illustrated by Mr. Davidson, we have
small spiriferoid shells with the valves very unequal, the ventral valve
being extremely elevated and semipyramidal, with high area and narrow
fissure closed by a convex pseudo-deltidium, presenting the same aspect
with those heretofore referred to Cyrtia; the dental plates converge
from the inner margins of the fissure, and uniting, form a single. plate or
septum which reaches to the bottom of the interal cavity, thus dividing
it into two parts.

S64

PALEONTOLOGY OF NEW-YORK.

This arrangement leaves an enclosed triangular tube between the
pseudo-deltidium and the converging dental plates. To these characters
may be added the punctate texture of the shell, which, so far as now
known, is accompanied in these forms by the external character and
internal arrangements described.

Besides these features, several. of our species have a median septum
in the fissure, in continuation of the central septum below the
junction of the dental plates. This septum is visible when the pseudo-
deltidium is removed, as shown in figures of C. rostrata *, and as seen in
many specimens of C. dalmani, as well as in C. biplicata and in C. hamil-
tonensis. This central septum, both above and below the junction of the
dental plates, may have the same origin : the coalescing of these
plates allows the exterior laminae of each to unite, and extending inward
form the septum dividing the cavity ; while the inner walls of the dental
plates are united and recurved, turning outwards to form the septum
dividing the triangular space beneath the pseudo-deltidium.

The several species which I have heretofore described as Cyrtia have
all a punctate structure, and, so far as examined, they have the arrange¬
ment of the internal parts described in Cyrtina. It was not until after
the completion of the third volume of the Palaeontology of New-York
in 1859, that I received that part of Mr. Davidson’s Monograph of the
Carboniferous fossils containing his arguments for the separation of the
genera and his description of Cyrtina. The characters of Cyrtina, as
given by Mr. Davidson, show its near relations with Spiriferina ; the
principal differences, as illustrated in figures of the latter genus, being
that the dental plates do not coalesce before reaching the bottom of the
cavity, the high median septum rising unsupported nearly to the plane
of the area.

In that volume I have described two species under the name of Cyrtia,
both of which have the structure of Cyrtina ; and in one of these I men¬
tioned the discovery of the spiresf , a feature which Mr. Davidson had not

* Palaeontology of New-York, Vol. iii, pi. 96, f. 2 d, 3 a & 4 d.
t Cyrtia rostrata , Pal. New-York, Vol. iii, p.429.

CYRTINA OF THE UPPER HELDERBERG GROUP.

265

observed at the time lie published his description. In specimens of three
species ( Cyrtina rostrata, C. hamiltonensis and C. dalmani ), the spires are
oblique to the direction of the valves, their apices terminating in the
rostral part of the ventral valve. This feature is likewise common to
some species of Spiriferina, as has been beautifully shown by M. E.
Deslongchamps in his “ Etudes Critiques sur lets Brachiopodes nouveaux ou
peu connus ,” in S. rupestris, S. pinguis and S. hartmanni. The form of the
spirals is also more cylindrical than ordinarily observed in Spirifera,
and in this respect also resembling those of CyrtinA. The spiral coils in
some species of Spirifera are oblique to the axis of the shell, and this
feature has been shown by Mr. Davidson in Spirifera bisulcata ( British
Garb. Brachiopoda, PL vi, fig. 17), and by Geinitz and Gutbier in a spe¬
cies of Spirjfera referred to S. cultrijugatus of Rcemer.* So far as at
present known to me, this genus does not extend below the horizon of
the Niagara group.

In view of these facts, it becomes necessary to make the following
corrections and references to previously described species.

Cyrtina pyramidalis.

Spirifer' pyramidalis : Hall, Palaeontology of New-York, Vol.il, pa. 266, pi. 54, f. 7. 1852.

This species is from the shale of the Niagara group.

Cyrtina dalmani.

Cyrtia dalmani : Hall, Tenth Report on the State Cabinet, p. 64. 1857.

“ « .- Idem, Palaeontology of New-York, Vol. iii, pa. 206,. pi. 24, f. 2.

From the shaly limestone of the Lower Helderherg group.

Cyrtina rostrata.

Cyrtia rostrata : Hall, Tenth Report on the State Cabinet, p.64. 1857.

“ << : Idem, Palaeontology New-York. Vol. iii, pa. 429, pi. 96, f. 1 - 6.

From the Oriskany sandstone.

# Die -V ersteinerUngen des Zechsteingeberges und Rothliegenden, oder des Permischen Systems in
Sachsen : yon Hanns Bruno Geinitz, Dr. Phil., und August Yon Gutbier, Konigl. Sachs.- Major.
Heft I by Dr. H. B. Geinitz, Tab. v, fig. 9.

[ Paleontology IV.]

34

26©

PALAEONTOLOGY OF NEW-YORK.

Cyrtina Mplicata.

PLATE XXVII.

Cyrtia biplicata Hall, Tenth Report on the State Cabinet, p. 165. 1857.

Shell semipyramidal ( semielliptical in the dorsal view ) ; length and
breadth about as two to three, with a height of area less than the length
of the shell : hinge-line equal to the greatest width of the shell.
Yentral valve extremely elevated, semipyramidal, curving abruptly to
the front and sides : the length from the apex to the cardinal extremity
is often about the same as from the apex to the front of the shell.
Mesial sinus somewhat deep, subangular in the bottom, and defined at
the margins by a strong fold or plication : apex elevated, sometimes
attenuate and slightly incurved over the high area, which ^s either flat
or slightly arcuate ; fissure narrow and partially or entirely closed by
a convex pseudo-deltidium.

Dorsal valve depressed-convex, and sometimes nearly flat towards the
cardinal extremities : mesial fold moderately elevated, and strongly
defined by a furrow on each side ; area extremely narrow.

Surface marked by numerous fine radiating strias, and sometimes by
distinct and even strongly marked imbricating lines of growth. The
entire shell-structure is punctate.

Where the shell is preserved, the mesial sinus is bounded on each side
by a distinct elevated fold having a depression on the outside of it, and
this feature is often shown in the casts. The median septum extends for
one-third or more of the length of the ventral valve, and its extension
is shown in the fissure beneath the pseudo-deltidium. From the little
that can be seen of the spire, in specimens examined, it is arranged as
in Spirifera. In this example the spire may be displaced so as to appear
in a transverse position. In two species where the position of the spires
are clearly determinable, they are directed towards the apex of the ven¬
tral valve; but in these species the transverse extension is less than the
elevation of the valve, and I can conceive it probable, that in species of
the genus having a low area, with considerable lateral extension of the

CYRTINA OF THE HAMILTON GROUP.

267

valves, the spires may be directed towards the cardinal extremities as
in Spirifera.

The original specimen described was too imperfect to admit of a full description,
but the characters indicated have been observed in all the specimens obtained.

The illustrations, Plate xxvn, figs. 5-10, represent the prevailing features of
the species.

. Geological formations and localities . This species occurs in the Schoharie grit,
in Albany and Schoharie counties; and in the Corniferous limestone, at Williams-
ville in Erie county. I have also a specimen from the same rock in Michigan, re¬
ceived from Dr. Rominger of Ann-Arbor. Although having so wide a geographical
range, this species is a rare fossil.

Cyrtina crassa ( n. s.).

PLATE XXVII.

Shell depressed-pyramidal (semielliptical in a dorsal view) ; length and
breadth about as three to four ; hinge-line equal to the greatest width
of the shell, with the extremities slightly rounded.

Ventral valve depressed-semipyramidal, convex, regularly arching from
the beak and cardinal area to the front ; sinus broad and rounded in
the bottom ; beak extended and slightly incurved over the area, which
has a height about equal to half the length of the valve.

Dorsal valve moderately convex, a little inflected or concave towards the
cardinal extremities; mesial fold broad, moderately elevated, rounded
above and strongly defined : area linear.

Surface marked on each side of the mesial fold and sinus by about four
strong, low, rounded plications, .which are crossed by fine threadlike
concentric striae and a few imbricating folds. Shell-structure punctate.
A single specimen only of this species has been seen; but its great lateral ex¬
tension, comparatively low ai’ea, and few strong plications, preclude its union with
any of the previously described species.

The figures 11 & 12 of Plate xxvii are a dorsal and ventral view of this species.
Geological formation and locality. In the Corniferous limestone, near Vienna,
Ontario county.

268

PALAEONTOLOGY OF NEW-YORK.

Cyrtina Iiainiltonensis.

PLATES XXVII &. XLIV.

Cyrtia hamiltonensis .- Hall. Tenth Report on the State Cabinet, p. 166. 1857.

« << : Billings, Devonian Fossils of Canada West (Canadian Journal), p. 263. 1861.

Compare Cyrtia acutirostra, Shumard, Geol. Report Missouri, Part i, pa. 204, pi. c, f. 3. 1854.

Shell more or less triangular-subpyramidal ; hinge-line equal to the
greatest width of the shell ; proportions of length, breadth and height
variable, but frequently the width is equal to the length of the ventral
valve, and the height of area is equal to the length of the dorsal valve :
surface plicate.

Ventral valve quadrilateral in outline, obliquely subpyramidal, most
prominent at the beak, which is very variable in elevation and straight
or a little arched over the area, and not unfrequently attenuate and
distorted or turned to one side ; mesial sinus wide and strongly defined,
rounded or subangular in the bottom : area variable, large and elevated,
plane or arcuate in different degrees with the lateral margins angular,
distinctly striate in both directions ; fissure narrow, closed by a con¬
vex pseudo-deltidium, which is perforated above by an oval or narrow¬
ly ovate foramen.

Dorsal valve depressed-convex, with a broad more or less prominent
mesial fold, which is bounded by broader furrows than those between
the plications, and is sometimes extremely elevated in front ; beak
scarcely rising above the hinge-line : area narrow linear, but quite
distinct.

Surface marked by about six to eight (rarely one or two more) simple
rounded plications on either side of the mesial fold and sinus, and these
are crossed by very fine concentric lines of growth, which at intervals
become crowded and subimbricate, especially towards the margins of
older shells. The finer surface-marking is minutely grknulose or papil¬
lose, and the shell-structure distinctly punctate. In some of the larger
individuals there is an obscure elevation on each slope of the sinus,
resembling an obsolete plication.

The longitudinal median septum extends for more than half the length

of the ventral valve, and is continued into the cavity beneath the pseudo-

CYRTINA OF THE HAMILTON .GROUP.

269

deltidium. These features are shown in the casts and in transvers sections
of the valve. The dorsal valve shows a double or bilobed cardinal process,
with the strong crural bases supporting spiral arms, which are directed
into the two compartments of the ventral valve, and, making numerous
turns, terminate in the rostral part of the shell.

I have heretofore compared this species with Cyrtina heteroclita ( = Calceola
heteroclita , Defrance; $ 'pirifera heteroclita, Yon Bitch, &c.); but in that one the
plications are described as angular, and generally less numerous than in ours;
though the variety multiflicata, Davidson, has more numerous plications; and
this, with other characters, shows that the fossil undergoes variations similar to
our own, and that it is a closely allied form holding a similar geological position.

The specimens in the Hamilton group of New- York are usually small, measuring
about half an inch in length and breadth; the largest one seen by me being a little
more than fb of an inch in width, and about in length from the apex to the
front of the valve. In some Canadian specimens, the length and widtli are about

of an inch. The species has a wide geographical and considerable vertical range;
being known in the Schoharie grit (Plate xxvii, f. 1, 2 & 13), Corniferous lime¬
stone, Hamilton and Chemung groups.'

Figures 3 and 4 of Plate xxvii are. from the Corniferous limestone of New
York.

I am indebted to Dr. James Knapp of Louisville, Kentucky, for the specimen illustrating
the spires, which is figured on Plate xliv, fig. 50. This one is from the Corniferous lime¬
stone, and presents six or seven turns of the spire ; while some specimens from the Hamilton
group have shown, on being cut through, ten or eleven turns of the spire.

The figures 26 - 33, Plate' xliv, present the usual aspect of the species in the Hamilton
group in New- York, while 37 - 40 are of a larger individual.

Figures 34 - 36 are of a variety where the area is flat, and the plications more angular
than usual.

Figures 41 & 42 are of a large individual from the Hamilton shales of Canada West.

Figure 51 is of a specimen of this species from the Hamilton group of Iowa, received from
Mr. 0. St.John ; and I have similar forms from near Iowa city.

The transverse and. longitudinal sections, showing the interior structure, are of speci¬
mens from the Hamilton shales of Canada West. j

Geological formations and localities. This species occurs in the Schoharie grit,
in Albany and Schoharie counties , and in the Corniferous limestone- of. Eastern
and Central New- York, and at St.Marys and Cayuga in Canada West. In the Ha¬
milton group, it occurs on the shores of Cayuga, Seneca and Canandaigua lakes,
at Moscow, York, Darien, Hamburgh and Eighteen-mile creek in New-York; near
Cumberland in Maryland; abundantly at Widder station in Canada West; at
Independence, Rockford and Waterloo in Iowa.

n tke Chemung group, the var. recto. occurs at Philipsburgh in Allegany co.

27©

PALAEONTOLOGY OF NEW-YORK.

Cyrtina liamiltoiiensis, var. recta.

PLATS' 5LIV.

Figures 36 an d37 of Plate xyii illustrate tliis form, which has a plane
flat area, without incurvation of the beak, and with angular plications.

This form is not uncommon in the Hamilton group, and was for a long time the
only one known to me in the Chemung group ; hut very recently I have received,
among a collection of Spirifera disjuncta from the southern part of the State,
a specimen which indicates that the species may have in this horizon the same
variations which it has in the formation below.

Cyrtina curvilineata [ ? ]

PLATE XLIV.

Compare Cyrtia curvilineata, White : Proceedings of the Boston Society of Nat. History, Vol.ix, p. 25.

Shell rather large, obliquely subpyramidal : hinge-line equalling or
slightly less than the greatest width of the shell; length of dorsal
valve less than its width, and one-third greater than the height of
area of the ventral valve. Entire surface plicate.

Ventral valve obliquely subquadrilateral in outline, the apex turned to
the left : area much elevated, inclined backwards, slightly incurved.
The fissure has apparently been closed in the lower part, but the
pseudo-deltidium is broken away, and there is no evidence that the
upper iwo-thirds of the fissure has been closed at any recent period of
the animal’s life.

Dorsal valve semielliptical, convex in the middle and flattened at the
cardinal margins ; mesial fold prominent towards the front.

Surface marked by about twelve or thirteen rounded plications on either
side of the mesial fold and sinus. The mesial fold has four or five low
rounded plications near the front, while there are four corresponding
folds on the sinus.

This species has the general form and proportions of the C. liamiltonensis , and
occurs with that species in rocks of the age of the Hamilton group in the west.
It differs slightly in some of its proportions from the prevailing eastern forms of
that species, but not more than is observed among specimens of the same in col¬
lections from New-York, Canada West, and the Western States. The distinguishing-
feature is in the presence of plications on the mesial fold and sinus. The presence

GENUS TREMATOSPIRA.

271

or absence of a pseudo-clelticlium coveifiiig Hie fissure I should not regard as of
specific importance, and the distortion of the beak of the ventral valve is a feature
common also to the C. hamiltohensis.

This species is probably the one described by Dr. White ; but he speaks of the
shell as small, while the one under examination is large for one of the genus. It
has also a greater number of plications, both on the fold and sinus as well as on
the sides of the shell. These differences may be due to age and condition.

The figures 53-55, Plate 44, illustrate the characters of this species. The sinus is unequal
in depth, but its limits are not quite sufficiently defined in the figure, and I have added a
dotted line (. . . .s) beneath, indicating the limit of the sinus on the right side.

Geological formation and locality. In beds of the age of the Hamilton group
near Iowa city, Iowa.

Gem s Trematospira.

Trematospira : Hall, in Third volume of Pal. New-York, p. 207.

“ “ in Twelfth Report on the State Cabinet, p. 27. 1859.*

This genus was originally proposed by me to embrace a few forms,
having a general resemblance to Spirifera, but without the extended
hinge-line and area ; or with the latter feature uncertain or undefined,
and wanting in the characters of a true area. Such at least is the cha¬
racter of the specimens originally examined ; some of which approach
in extended form to Rhynchonella.

Up to this time, comparatively few species are known; and of the
greater part of these, few individuals have been obtained, so that our
knowledge of the interior structure is still imperfect. In all the species
possessing the peculiarities of external form noticed, we find a punctate
structure of the shell ; a character which alone is sufficient to separate
them from Spirifera proper, or from Rhynchonella.

The genus was founded originally upon species from the Lower Hel-
derberg group of New-York, including a single species from the Niagara
group. I have, since that time, observed similar external features in
specimens from the Lower Silurian rocks of Ohio and elsewhere ; while
a single species from the Hamilton group, first described by me as Atrypa

*The description of this and other genera of Brachiopoda, printed in Yol. iii, Palaeontology of New-
York, in the years 1857 and 1858, were first published in the Twelfth Report on the State Cabinet
in- 1859.

272

PALAEONTOLOGY OF NEW-YORK.

hirsuta, has been found to have a punctate structure, with spires arran
ged as in Spirifera, and otherwise possessing the characters of Trema-
tospira ; and another species from the group has been added to the
number.

Desirous of avoiding too great a multiplication of genera, I at first
included under this designation species which it has since been found
necessary to separate on account of marked difference in form, and also
in the character of the hinge appendages. These latter species, under the
name of Riiynchospira, seem to me sufficiently distinct from Retzia to
he recognized at least as a subgenus.

In the present state of our knowledge of the heterogeneous assemblage •
of material known under the name Retzia, it is quite impossible to
define the limits of that genus with any precision. Farther investiga¬
tions, with better material, are required for this purpose ; for the deter¬
mination by external form alone is not satisfactory. In the mean time, I
refer the following forms to the genera under which they are placed
according to the best information we have been able to obtain of their
structure and affinities.

Trematospira gibbosa.

PLATE XLY.

Trematospira gibbosa : Hall, in Thirteenth Report on the State Cabinet, p. 82. 1860.

Retzia eugenia [ ?] Billings, Canadian Journal, p. 147. 1861.,

Shell more or less gibbous : valves subequally convex, transversely
subelliptical, about once and a half as wide as long ; hinge-line less
than the width of the shell ; strongly plicate.

Yentral valve less gibbous than the opposite, somewhat abruptly
arcuate towards the apex, which is truncated by a circular foramen :
this is completed on the inner side by what appear to be depressed
deltidial plates, which at the same time form a flattened triangular
space or false area. ' Mesial sinus abruptly depressed in old shells, and
less conspicuouly in younger ones.

TREMATOSPIRA OF THE HAMILTON GROUP.

273

Dorsal valve gibbous, more convex than the opposite : beak abruptly
incurved, and concealed within the cavity of the ventral valve. Mesial
fold more or less conspicuous, sometimes scarcely raised above the
adjacent plications.

Surface marked by nine or ten strong angular plications : three of these,
in the centre of the dorsal valve, are more approximate and smaller
than the others, giving the character of a mesial fold which is some¬
times scarcely elevated above the general contour of the surface ;
while the two central plications on the opposite valve are much smaller
than the adjacent ones, and abruptly depressed. The concentric
lamellae of growth, in crossing the plications, give a series of zigzag
lines ; and these often become crowded and very conspicuous on the
front of the shell. Entire surface finely granulose, and the shell struc¬
ture punctate.

The interior of the dorsal valve shows a bilobed cardinal process, with
obscure indications of the crural bases. There is a distinct mesial septum
in the .upper part of the valve. The muscular impressions have not been
satisfactorily observed.

The largest specimens of this species are about half an inch long and
five-eighths of an inch wide, while the depth in gibbous specimens is
little less than the length.

This shell has much the appearance of a broad gibbous Rhynchonella; but
the perforated beak, false area and punctate structure, serve to distinguish it
from that genus. I have referred this shell to Trematospira, from the generally
similar character of the beak and perforation, and the punctate structure of the
shell. I have not discovered the existence of spires ; but my specimens are too
few to admit of the necessary examinations.

Geological formation and localities. This fossil has been found near Bellona,
Ontario county; near Geneseo and York, Livingston county; and at Pavilion and
Darien in Genesee county, New-York.

[ Palaeontology IV.]

85

274

PALAEONTOLOGY OF NEW- YORK.

Trematospira hirsute.

PLATE XLV.

Jtrypa hirsuta : Hall, in Tenth Report on the State Cabinet, p. 108. 1857.

Trematospira hirsuta : In. Thirteenth Report on the State Cabinet, p. 101. 1860.

A thyris (?) chloe : Billings, Canadian Journal, p. 282. 1860.

Shell depressed-orbicular in the young state ; becoming subtrilobate by
the gradual development of a mesial fold and sinus, and often gibbous
in the older specimens ; valves subequally convex; hinge-line extend¬
ing about two-thirds the width of the shell.

Ventral valve usually a little more gibbous than the opposite; greatest
convexity above the middle of the shell, whence it curves regularly to
the apex, which is terminated by a circular foramen, or more often
truncated below by the summit of the opposite valve : contour, regu¬
larly curving to the cardinal and lateral margins. The mesial sinus
becomes gradually developed above the middle in full grown shells,
and is very conspicuous towards the front, having the sides curving
and rarely strongly defined. The false area is not visible beneath the
beak.

Dorsal valve regularly convex in young shells ; becoming elevated in
the centre, and a mesial fold gradually developing itself, till in old
shells it becomes very conspicuous towards the front. The sides -are
pretty regularly convex, and curving towards the margins.

Surface marked by from thirty to forty simple low rounded striae, which
are obscure towards the beaks, but become larger and more conspicuous
towards the margin : these are crossed by fine close concentric lines
of growth, and more distant imbricating lamellae. The surface ordi¬
narily preserved is granulose ; but when perfect, it is covered by
minute seta or spinules, the bases of which, remaining, give the papil¬
lose character. Entire shell structure punctate.

The interior of the ventral valve shows two strong teeth, which are
extended in low plates along the sides of the rostral cavity to the mar¬
gins of the muscular area, which is broad, flabelliform, and scarcely
defined on the front and lower lateral margins.

TREMATOSPIRA OF THE HAMILTON GROUP.

S73

The interior of the dorsal valve shows a strong deeply bilobed cardi¬
nal process, with the bases of slender crura ; the teeth sockets are large
and deep ; there is a low median crest or septum, which is somewhat
strong above, but dies out about the middle of the shell. In specimens
which have been cut to show the spires, these appendages are slender,
with about ten or eleven turns on each side.

The proportions of length and breadth are about as three to four.
The largest specimen observed is a little more than three-fourths of an
inch in length, by an inch and one-sixteenth in width ; while many of
the specimens are less than half these dimensions. A well-formed speci¬
men of about three-fourths of an inch in length by one inch, has a depth
of nine-sixteenths of an inhh. A very gibbous specimen measures three-
eighths of an inch in length, nine-sixteenths in width, and half an inch
in depth.

The general aspect of this shell is similar to T. multistriata; but the form is
usually less gibbous, the sinus more distinctly defined, and the striae are
essentially simple. It is distinguished externally from Atrypa, by the granulose
surface and punctate character of the shell.

This fossil is not abundant, though not exceedingly rare. It is principally
restricted to the western part of New- York, and has been found in Canada West.

Trematospira hirsuta (Hamilton group).

7 8 9 10

Figs. 7 & 8. Dorsal and front views of a specimen.

Figs. 9 & 10. Interior of the dorsal and ventral valves.

Geological formation and localities. This species occurs on the shores of
Canandaigua lake and at Bloomfield, Ontario county • at York and Moscow, Li¬
vingston county ; at Pavilion and Darien, Genesee county, and at Eighteen-mile
creek in Erie county, New-York. In Canada West it occurs near Widder station
on the Grand Trunk railway.

I have received this species from Dr. James Kxapp, of Louisville, collected from
the corniferous limestone at the Falls of the Ohio.

The following figures in wood are illustrations of some of the typical species of
Trematospira, from the Lower Helderberg group, described, and heretofore
given in the State Cabinet Report.

276

PALAEONTOLOGY OP NEW- YORK.

Trematospira multistriata.

12 3

Figs. 1 &. 2. Ventral and front views.

Fig. 3. The interior of a ventral valve filled with stony matter, and ground so as to show the spires

6

Fig. 4. Trematospira perforata. The upper part of the shell enlarged, showing beak of ventral
valve, perforation and triangular space below.

Figs. 5 & 6. Trematospira costata. Dorsal and front .views of a specimen.

Genus Riiynchospira (Hall).

In the third volume of the Palaeontology of New- York (page 213), I
suggested this name as a subgenus of Trematospira ; but subsequently,
from certain peculiarities of hinge-structure, general form, etc., I was
induced to propose it as a distinct genus. Although approaching the
typical species of Retzia, I am not satisfied of the identity of the two ;
and until we have better information regarding the latter genus, I pro¬
pose to place under Rhynchospira those forms which are similar to R.
formosa of the Lower Helderburg group.*

Rhynchospira lepida.

PLATE XLV.

Rhynchospira lepida : Hall, Thirteenth Report on the State Cabinet, p. 83. 1860.

Shell small, broadly suboval, with the valves subequally convex, and
the beak of the ventral valve extended.

*In the Sixteenth Report upon the State Cabinet of Natural History, pp, 53-59, I have discussed
the relations of Retzia, Trematospira, Rhynchospira, with the materials at that time accessible
to me.

RHYNCHOSPIRA OF THE HAMILTON GROUP.

277

Ventral valve broadly suboval, regularly convex, or with a scarcely
perceptible mesial depression. The beak is much elevated above the
opposite valve, gently arcuate, with the apex perforated, and the
space between it and the summit of the dorsal valve closed by two
convex deltidial plates which are excavated on their inner and upper
margins, forming an elongate oval perforation communicating above
with the opening of the beak.

Dorsal valve often nearly as wide as long, moderately convex, with the
greatest convexity a little above the centre. There is a slight depres¬
sion along the middle in some individuals, but this is an obscure or
inconstant feature.

Surface marked by about twenty-four (varying from 20 to 25) simple
regular plications, which are gradually enlarged towards the margins
of the valve. On the dorsal valve, two or three of the central plica¬
tions are depressed, causing a slight sinus in front ; but there is no
corresponding elevation on the opposite valve. The shell structure is
punctate throughout.

The interior structure is not known.

Lhave referred this species to Rhynchospira, from its generally similar aspect
to those of the Lower Helderberg group ; but the large deltidial plates and double
perforation have not been observed in those species ; though in T. rectirostra,
there are deltidial plates closing the space below the apicial foramen. It is still
desirable to examine specimens for the .presence of the spires or crura^hs these are
unknown.

The prevailing form of the specimens is that described ; but rarely there occurs
one that is more elongated. The species has the general aspect of Rhynchonella;
but it is readily distinguished by the narrow depression of two plications on the
dorsal valve, and by the. punctate structure of the shell, as well as by the foramen
and deltidial plates when these features are preserved or exposed.

Geological formation and localities. In the shales of the Hamilton group, on
the shore of Canandaigua lake, and near Bellona, in Ontario county, New- York,
RHYNCHOSPIRA NOBILIS.

Rhynchospira nobilis : Hall, Thirteenth Report on the State Cabinet, p.83. 1860.

A re-examination of the specimens has left some doubt regarding the generic
relations of this fossil, and the description is deferred to another part of the
volume.

PALAEONTOLOGY OF NEW-YORK.

The following figures are illustrations of one of the typical species of Rhyx-
CHOSPira, from the Lower Helclerberg group.

RHYNCHOSPIRA FORMOSA.

1 & 4 2 3 5 6

Fig. 1. Dorsal view, natural size. Fig. 2. Interior ot a dorsal valve, showing the cardinal process, etc.

Fig. 3. Profile of figure 2, showing the recurved cardinal process.

Fig. 4. The ventral valve of the same species.

Fig. 5. A longitudinal section, showing the articulation of the valves, the origin of one of the crura,
the spire, etc.

Fig. 6. The upper part of two valves, showing the mode of articulation.

Gems NuCLEOSPIRA* (Hall).

This genus was proposed by me to include a few small species of fos¬
sils which had heretofore been referred to Spirifer, Atrypa, Orthis, etc.,
but which do not possess the true characters of either of these genera.
Since we know the peculiarities of its internal structure and the accom¬
panying exterior, together with the punctate texture, there is no longer
.any difficulty in recognising these shells among the other Brachiopoda.

The following are the important characters of the genus, as determined
from the examination of the species' of the Niagara, Lower Helderberg
and Hamilton groups.

Shell depressed spheroidal or transversely elliptical, more or less,
gibbous or ventricose, furnished with internal spires as in Spirifera ;
hinge-line shorter than the width of the shell; cardinal extremities
rounded : valves subequal, articulating by teeth and sockets. Ventral
valve having the beak slightly extended beyond the opposite valve, and
beneath it a triangular depression or area, which has sometimes a
shallow semispoonshaped form ; on each side of which, at the base, is a
strong tooth. A narrow ridge or septum along the centre of the inner

* This genus was first described in the third volume of the Palaeontology of New- York, p. 219, and
is copied on pages 24 and 25 of the Twelfth Report on the State Cabinet.

NUCLEOSPIRA OP THE HAMILTON GROUP.

side of the valve often extends from beak to base. Dorsal valve
furnished with a strong spatulate cardinal process, which, rising verti¬
cally from the cardinal margin, is closely grasped at its base by the car¬
dinal teeth of the other valve ; and thence bending abruptly upwards,
and expanding, is projected into the cavity of the opposite beak, lying
close upon the underside of the false area. This process is grooved or
depressed in the centre of the upper side, so as to leave ' between it and
the arch of the ventral beak a narrow space for the passage of a pedicle,
a minute foramen being sometimes observed in the beak for its pro¬
trusion. From the sides of this process, above the junction of the teeth
of the opposite valve, and at the point where it bends upwards, originate
the crural processes which support the spires. A deep cavity beneath
the cardinal process extends to the dorsal beak, where originates a thin
elevated septum often extending to the base of the shell. Muscular
impressions of the dorsal valve occupy a narrow oval space ; those of
the ventral valve broader, flabelliform.

Under this genus I have described N. ventricosa, N. elegans and N. concentrica from the
Lower Ilelderberg rocks; N. pisiformis ( Orthis pisum, Pal. New-York, Yol. ii, p. 450),
from the Niagara group ; and N. concinna ( Atrypa concinna, Rep. of the Fourth Geol. Dis¬
trict of New-York, 1848, p. 200, f. 3), which are the species known to me at the beginning
of 1858.

Nucleospira concinna.

PLATE XIV.

Jtlrypa concinna : Hat/l, Geological Report Fourth District New-York,, p. 200, f. 3. 1843.
Nucleospira concinna : Hall, Twelfth Report on the State Cabinet, p.25 and p.26. 1859.

Shell depressed, subspheroidal, nearly circular in outline, the width
being usually a little greater than the length ; valves subequal.
Ventral valve regularly convex, the greatest convexity a little above
the middle, and curving regularly to the sides and front ; umbo pro¬
minent, the beak neatly pointed and incurved over the apex of the
dorsal valve, leaving a space between which sometimes exposes the
narrow area. There is usually a narrow depressed line from the beak
to the base of the valve ; but this is sometimes partially absent, or so
faint as not to be readily observed.

28®

PALAEONTOLOGY OF NEW-YORK.

Dorsal valve regularly convex, sometimes gibbous, becoming a little
depressed towards the base, the greatest convexity being a little above
the centre : there is usually a depressed line along the middle of the
valve. The hinge-line is about one-third, and sometimes half as long
as the width of the shell.

.Surface usually smooth or very finely papillose ; but in its perfect con¬
dition, it is covered by numerous fine seta which are matted together,
and the interstices being filled with clay, it has a rough appearance ;
while under a lens, these seta give a finely striate aspect. Beneath the
fine papillose surface, the texture of the shell is minutely punctate.
The interior of the ventral valve presents beneath the beak a low
depressed area, or false area, which is bordered on each side by a strong
tooth. The muscular area is somewhat broad, flabelliform, with* the
margins lobed ; the occlusor imprints in the centre are strongly marked
elongate oval spots, and there is a low median crest which often extends
to near the front of the shell. In the dorsal valve there is a strong wide
cardinal process, the inner face of which is mainly occupied by a broad
oval pad for the muscular attachment (see figure, Plate 45), extending in
a narrow callosity into the cavity below.

The teeth sockets are deep, and margined by a strong callosity which
forms the base of the process ; and from thence proceed the crura and
the slender spiral arms, which make about eleven or twelve turns in the
larger individuals. The muscular area is narrow, well defined, and lobed
below ; while the inner portions, marked by the occlusor muscles, are
two sublinear spots. A slender crest extends along the middle of the
impression. The interior of the shell is somewhat pustulose.

The figures given exhibit the variations in size and proportions usually observed
among large collections of specimens.

Figure 33 is a cast from the Schoharie grit.

Figures 34 and 35 are from the Corniferous limestone ; and the succeeding figures are of
Hamilton group specimens.

The hinge-line of the two valves has been greatly enlarged, to show the parts descri¬
bed ; and the casts of both valves have been enlarged two diameters, to show the character
and form of the muscular impressions.

NUCLEOSPIRA OF THE HAMILTON GROUP.

381

Geological formation and localities. This species is known in the Schoharie
grit, in Albany and Schoharie counties; in the Corniferous limestone at Lapham’s
mill in Ontario county, at Caledonia in Livingston county, and at Williamsville in
Erie county, New- York, and Falls of the Ohio; and in the Hamilton group, in the
vicinity of Apulia in Onondaga county, shores of Seneca and Cayuga lakes, Canan¬
daigua lake, Geneseo, York, Moscow, Pavilion, Alexander, Darien, Hamburgh,
Eighteen-mile creek, and other localities in the western part of the State of New-
York.

I have received very fine specimens of the internal casts of this species from
Dr. G. A. Williams, collected in the Hamilton group of Hardy county, Ya.; and
it likewise occurs near Cumberland, Maryland.

Note. In the arrangement of the preceding genera of the Family Spibifebiile,
I have followed what appeared to be the most natural order ; and since we pass
almost insensibly from Spieifeba to Spibifebina and Cyetina, it is scarcely pos¬
sible, from what we know, to remove the Genus Tbematospiba from the relation
in which I have placed it. The Genus or Subgenus Rhyxchospiea will therefore
follow, and all those forms referred to the Genus Retzia will come into the same
relation. I have placed in this association the Genus Nucleospiba, which may,
perhaps, be more nearly related to the following than to the preceding genera.
So far as we know, the structure of the spire ( though with some variations ) is
similar in all these, and the presence of an area or false area may be recognized
in all or nearly all of them.

By this arrangement the Genera Athyeis, Meeista and Mebistella, will be
farther removed from Spieifeba proper, while it might appear that their relation
would be more nearly with the smooth Spirifers. I have followed this order of
arrangement, beginning with the Genus Athyeis, because I had so arranged the
matter and the plates of the volume before having made the final studies of the
interior and the determination of the structure of the spires. It will be seen,
However, that the spires in Mebistella are very nearly like those of Spieifeba
proper, while those of Athyeis show a wide departure in the character of the
loop and intercalated lamellae. Regarding the Genus Mebistella in all its charac¬
ters as now determined, I wTould place it before Athyeis in its relation to
Spieifeba.

Paleontology IV.]

36

282

PALAEONTOLOGY OF NEW-YORK.

©EMUS AthYRIS (McCoy).

Athyris, McCoy, 1844. Spirigera, D’Orbigny, 1847.

The Genus Athyris was established in 1844 by Prof. McCoy, upon
certain species separated from the Terebratul,® ; and when restricted
according to the original types of that author, includes a very natural
group of shells, but which nevertheless possess many external features
in common with the later established genera Merista and Meristella,
and from which the species are distinguished by important internal
characters.

The shells of the genus are variable in form, being suborbicular,
transverse or elongate, subglobose or depressed, and -sometimes suban-
gular. The typical species are depressed suborbicular. The structure of
the shell is fibrous; the surface in most species is strongly marked by
concentric striae, and some of them are strongly lamellose, with the
lamellae becoming fimbriate or pectinate. In this aspect, as well as in
general form, these shells have a resemblance to some of the Spirifers
with short area and rounded cardinal extremities. The surfaces are
sometimes indistinctly radiatingly striated; but these striae are usually
subordinate to the concentric striae or lines of growth ; and it may be
doubtful whether any well authenticated species of the genus has con¬
spicuous radiating striae or costae.

The apex of the ventral valve is usually or perhaps always perforated
by a rounded foramen, tbe lower side of which is formed by the umbo of
the opposite valve. When the valves are separated, this foramen commu*
nicates with a triangular space, which opens into the main cavity of the
valve. This triangular fissure, which in older shells is usually occupied
by the beak of the opposite valve, has at some time during the animal’s
life been closed by deltidial plates.

The dorsal valve is furnished with a strong cardinal process, the
centre of which is often depressed and spoon-shaped, but sometimes thick-

GENUS ATHYRIS.

283

ened and convex. The crura proceed from each side of this plate ante¬
riorly ; while the posterior and lateral margins become more or less
thickened, or elevated into ridges bordering the teeth-sockets.

The muscular area is somewhat variable in form ; but in the ventral
valve it is oval or ovate, more or less flabelliform. The occlusor mus¬
cular imprints are marked upon the shell, and upon the cast, by a narrow-
elongate scar; while the divaricator muscles occupy a wider space on
each side, and are usually' strongly striated. In the dorsal valve the
muscular area is narrow, and often divided by a low longitudinal crest
or septum. The area 'outside of the muscular scars is papillose or papil¬
lose-striate, and often beautifully marked by vascular impressions. The
spires are complicated by intermediate lamellae.

The European species of Athyris (A. pedinif era, A. roissyi and A.con-
centrica ), as shown by Woodward, Davidson and others, have the spires
complicated by accessary lamellae, which, rising from the connecting loop,
are intercalated between the first and second turns of the normal
lamellae, and have their extremities free.

Although the presence of spires has been long known in the American
species, I believe no one has hitherto shown their analogy with the
European forms. In the determination of our species, however, and their
relations with Meristella, it became necessary to make a careful study
of all the internal characters upon which generic and specific distinctions
might be founded; but since all the specimens were essentially solid, it'
has been a labor of no little difficulty to determine accurately the true
character of these internal appendages. By carefully cutting down speci¬
mens of A . spir if er aides, which is very similar to the A\ concentrica of
Europe, the disposition of the spiral lamellae has been found as shown
in the following diagram, which represents only the central portion
of the spirals to the end of the first volution.

284

PALAEONTOLOGY OF NEW-YORK.

Athyris spiriferoides.

The origin of the crura, or point of attachment to the hinge-plate, is
indicated in the figure at a, from which the two lamellse proceed for a
short distance in a nearly direct line forward, but are soon bent upwards
and recurved upon themselves as shown in the figure at b, whence they
are again bent downwards into the cavity of the dorsal valve. From this
point the lamellae follow very nearly a direction parallel to the external
contour of the shell, being the exterior bands indicated by the dotted
lines to c. Farther on, these become expanded and send off from each one
a projecting process at d, and thence are united “in a solid plate at e,
forming the loop which connects the two parts of the spiral arms. It will
also .be observed that the lamellae are twisted, the exterior part at d
becoming the interior at the point of junction of the two parts. This
plate, formed by the junction of the lamellae, is sharply bent backwards
almost in the plane of the longitudinal axis of the shell ; and thence ris¬
ing nearly at right angles, becomes bifurcated at /, giving origin to the
accessary lamellae g, which are recurved in a plane essentially parallel
to the first volution of the spire, and coalesce with it at the points indi¬
cated by the dotted lines h, thus acting as an additional support to the

#I am indebted to the rare mechanical skill and artistic manipulation of Mr. R. P. Whitfield for
the preparation of specimens illustrative of this and another species of Athyris, as well as of the
spires of Meristella, etc.

ATHYRIS OF THE HAMILTON GROUP. ’

@85

primary lamellce of the spire in its first volution.* The lamellae are
represented as cut away at i, showing but a single volution. The remain¬
ing portions of the spires consist of simple volutions arranged in a conical
form.

Atliyris spiriferoides.

PLATE XLYI.

Terebratula spiriferoides : Eaton, American Journal of Science, Vol. xxi-, p. 137. "1831.

“ “ Id. Geol. Text Book, p. 46. 1832.

Mrypa concentrica : Conrad, Annual Report on Pal. New- York, pp. Ill, 112. 1838.

“ “ Hall, Report on Fourth Geol. District New-York, p. 198, f. 5. 1843.

Spirigera spiriferoides : (Eaton, sp.), Hall in Tenth Report on the State Cabinet, p. 153. 1857.

? Terebratula concentrica : Von Buch, Ueber Terebfhtula, T. 103, Berlin, 1834. Mem. Soc. Geol. France,
Vol. iii, p. 214. 1839.

Spirigera concentrica : Billings, Canadian Jour. 1861, and Geology of Canada. 1863.

Shell varying from transversely oval to suborbicular and sometimes
subquadrate, depressed or subglobose, more or less deeply sinuate on
the ventral side, with a corresponding elevation on the dorsal side :
hinge-line short ; the cardinal extremities rounded.

Ventral valve moderately gibbous, often regularly convex above the
middle, and becoming deeply sinuate towards the front, which is fre¬
quently abruptly elevated, flattened or a little concave towards the
cardinal extremities in the wider specimens : umbo gibbous, the beak
incurved, and often directed in a line nearly rectangular to the. plane
of the longitudinal axis, and covering the umbo of the opposite valve ;
apex perforate.

Dorsal valve gibbous, much more convex than the opposite valve; umbo
prominent, outline regularly convex above the middle and curving

* Although expressing no doubt regarding the investigations of European species which have shown
the free termination of the accessary lamellae, it seems to me more natural and as serving a practical
purpose in the economy of the animal, to have them attached to the primary lamellae of the spires for
the purposes of support and strength. It should not be forgotten, however, that the accessary IStmellas
are very slender near their point of junction, and may be easily separated or broken, and it requires
the greatest caution to preserve them entire. In specimens where these appendages are exposed from
natural causes, the chances would he much against their preservation entire.

S86

PALAEONTOLOGY OF NEW- YORK.

abruptly to the sides : the usually undefined mesial fold becomes
visible below the middle of the valve, and usually Very conspicuous
towards the front, which is abruptly elevated.

Surface marked by concentric lines of growth, and the lamellae often
extending and closely imbricated ; fine interrupted and scarcely dis¬
tinct radiating striae, which appear like ducts within the substance of
the shell, mark the surface in many specimens. The upper part of the
shell is sometimes nearly free from imbricating lamellae, but they
become crowded towards the front.

The interior of the ventral valve shows two strong teeth at the base
of the foramen, extending in strong plates to the base of the rostral
cavity, which is distinctly hollowed out for the reception of the pedicle.
The muscular impressions begin jult at the base of the rostral cavity,
and continue to a little below the middle of the length of the valve, as
shown in fig. 27. These features are impressed upon the cast, as shown in
figures 29 and 30 ; and the surfaces outside the muscular impression are
often beautifully and variously marked by vascular impressions which
are numerously ramified towards the margin, as shown in figure 30.
This character is often more extreme, and the ramifications are at least
tAvice as numerous as in this figure ; a feature more faintly shown in the
lower part of figure 29.

The interior of- the dorsal valve is furnished with a strong cardinal
process, the centre of which is often depressed and somewhat spoon¬
shaped, but frequently thickened : it is bounded posteriorly by elevated
socket-margins, and the crural bases diverge from either side of the
anterior portion. The muscular impression is narrow elliptical, and
divided by a low median crest. These features are shown in figure 26 ;
and the reverse or impression is well preserved in figure 28, which is a
cast of the interior of another dorsal valve.

The internal spires are often well preserved, and show about fif¬
teen turns : the two bands are connected at a point about half the length
of the shell from their commencement, by a sharply arched loop, in the
manner shown in the illustration given, and which is indicated in fig. 31.

ATHYRIS OF THE HAMILTON GROUP.

287

From this loop on the ventral side there is a bifurcation, from which
proceed accessary lamellae which are intercalated between the first and
second turns of the spire, as shown in the illustration under the generic
description.

The figures on Plate 46 present the principal varieties in form known to me in
the Hamilton group. The young individuals in this formation are usually pretty
symmetrical, as shown in figure 5. They are generally not strongly lamellose, but
sometimes acquire this character before attaining their full size, as shown in figures
6, 7 and 10.

In figure 8 we have an extremely oblate form, where the width is much greater
than the length; and figure 9 shows a subquadrate regular form. We have similar
extremes in figures 11 and 12, where the first is a little longer than wide; and the
second, having the same length, has a much greater width and less depth. These
figures illustrate the extremes of form among the young and half grown indivi¬
duals; while the full grown specimens of the oblate form are shown in figures
13 and 14.

Figures 15 - 19 illustrate the larger or apparently full grown forms of mode¬
rate gibbosity ; while figures 20-24 are of the more gibbous forms. Since these
■varieties of form occur in the same localities, both being quite common, it is pos¬
sible that they may indicate sexual differences.

Figure 25 is an extremely large form of moderate convexity and closely lamel¬
lose surface.

The casts present equally great extremes in form and proportions ; and the
muscular and other interior markings are subject to slight variation.

The dimensions of this shell vary, from specimens much smaller, than figure 5
and having a length of a quarter of an inch, to those having a length of about 20
lines with a width of 22 lines, while the depth is less than 10 lines, or about the
same as that of figures 22 and 23.

After an examination of many hundreds of specimens, showing.all the extremes
of form and character, I can find no means of specific distinction among them.

I have heretofore expressed an opinion that this species is distinct from the
Athyris concentrica of Europe, judging from the more straight hinge-line and less
prominent beak of the ventral valve, as well as that the greatest breadth is above
the middle of the shell. In the European species also, according to figures and
specimens, the ventral valve is always proportionally a little more convex than in
the American specimens. I have scarcely seen any illustration of the interior of
European specimens; but the cast of a dorsal valve given by Mr. Davidson in his
Monograph of British Devonian Brachiopoda shows a comparatively narrower
and more elongate muscular area, a form not approached in any degree by the

@88

PALAEONTOLOGY OF NEW-YORK.

numerous casts in my collection. Mr. Davidson says': “No defined septum is
“ observable in this [the dorsal] valve, but a rudimentary mesial ridge divides
“ the quadruple impressions of the adductor.” In the “ ventral valve the dental
“ plates are tolerably developed ; while the adductor leaves a small oval scar
“ towards the middle of the valves, and which scar is separated into two parts by
“ a minute mesial elevation, under and outside of which are seen the large impres-
“ sions of the divaricator .muscle.”

In our specimens there is a thin defined septum in the dorsal valve, reaching
from the apex for more than half the length o£the shell; and in the ventral valve
the dental plates are rather strongly developed, while the lower margin of the
adductor impression is considerably above the middle. These differences, there¬
fore, do not serve to change the opinion already expressed, and I shall retain for
the present the name originally proposed by Eaton ; more especially since it has
priority in point of time.

The A. concentrica is a characteristic fossil of the Upper Devonian strata of
Europe, but Mr. Davidson remarks that it is not very common in Great Britain ;
and he says he has not seen it from the Middle Devonian of Newton and Ogwell
in Devonshire, whence it has been cited by Mr. Morris in his Catalogue ; w'hich
•would leave us to infer that it is not common in that position. Our species begins
its existence at the epoch of the Corniferous limestone, and is abundant in the
Hamilton group, but I do not know of its occurrence in the Chemung group. It
must rank, therefore, rather as a Lower than an Upper Devonian species in
America.

Geological formations and localities. This species occurs in the Corniferous
limestone in Albany and Schoharie counties, and rarely in the same rocks in the
western part of the State. It is common in the Hamilton group, along Cayuga
lake, and at localities east of that line, though more often occurring as partial
casts. It is likewise common on the shores of Seneca and Canandaigua lakes, in
the Genesee valley at several localities, at Darien, Hamburgh and Eighteen-mile
creek, being more abundant in the latter place than any other locality known to
me. It occurs at Widder station and Bosanquet in Canada West, in the same posi¬
tion. It likewise occurs in Pennsylvania, Maryland and Virginia; principally, how¬
ever, in the condition of casts of the interior. From Cumberland, Md., I have
received specimens from Mr. Andrews, as well as from the collections of Mr. R.
P. Whitfield ; and I am indebted to Dr. G. A. Williams for many fine casts and
a few specimens retaining the shell, from Hardy county, Va.

ATHYRIS OF THE UPPER HELDERBERG AND HAMILTON GROUP. ^§9

Atliyris vittata.

PLATE XL VI : Figs. 1-4.

Athyris vittata : Hall, Thirteenth Report on the State Cabinet, p. 89. 1860.

Compare Athyris concentrica, A. spirif eroides , etc.

Shell ovate-subquadrate, gibbous, with the mesial fold and sinus distinct;
front conspicuously sinuate : hinge-line short : cardinal extremities
rounded.

Ventral valve gibbous above, more convex than the dorsal ; umbo pro¬
minent ; the beak incurved and truncated in the plane of the longitu¬
dinal axis by a round foramen, curving very abruptly to the cardinal
and cardino-lateral margins ; the centre marked by a well-defined
mesial sinus, which is continued nearly or quite to the beak, and
becoming much deeper and subangularly margined towards the front.
Dorsal valve a little less gibbous than the ventral, sides regularly curv¬
ing; the middle of the upper part distinctly prominent, and developed
below in a strong mesial fold which is abruptly elevated in front.
Surface marked by regularly imbricating lamellose lines of growth,
which, on the better preserved surfaces, are finely crenulate on their
edges, and the intermediate spaces striate.

Interiorly the spires of this form, in their first volution and in the
accessary lamellse, are quite distinct from those of A. spirif eroides. The
accompanying figure is an illustration of the first volution of the spires,
with the accessary lamellse.

Athyris vittata.

[ Paleontology IV.]

@9©

PALAEONTOLOGY OP NEW- YORK.

The bases of the crura are shown at a, and these projecting a short distance for¬
ward make a somewhat abrupt retral curve, turning back in the direction indicated
by the dotted lines b ; and thence descending into the cavity of the dorsal valve,
follow essentially the curvature of its outline, as indicated at c, to a point anterior
to the middle of the length of the spiral curve. Here the branches of the loop are
given off at d; and these projecting vertically into the cavity, are turned abruptly
forward, and beyond the dotted line, form a solid pointed plate which projects far
towards the anterior limits of the spires at e. The posterior portions are produced
backwards, and gradually ascending, continue parallel and in close proximity as far
as f where they diverge, sending off a fillet on each side which at g assumes
the curvature of the normal lamellae of the spire, following the same course
into the cavity of the valve, and extending forward to the origin of the
process forming the loop, they are united to the proper spiral lamellae at h, which
then continue simple as shown in their extension to i.

I had originally united this form of Athyris with A. sjpiriferoides of the Hamilton
group, regarding it only as a variety due to physical and geographical influences;
but when the internal structure presents such wide differences, I can scarcely
reconcile it with specific identity, if the distinction of species is to be preserved
upon any ground except that of arbitrary authority. In the examples before us, if
we admit such external and internal variations as incident to the species, it seems
to me very difficult to say where these variations may end, and characters of true
specific importance begin. At the present time I am not prepared to regard this
wide departure in the features of important internal organs as one of variety merely;
and while the external differences alone might not have been a sufficient reason
for specific distinction, I must regard them when thus combined, as entitled to this
consideration. Unfortunately the condition of the specimens is such as to afford
only rare opportunities of studying the interior.

The figures given (PI. 46, figs. 1-4) illustrate the general form and character
of the species as it occurs at the Falls of the Ohio. A farther comparison with
specimens from Iowa, which I have described as A. vittata , reveals no external
differences beyond the . smaller size of the last named species. Under those circum¬
stances I prefer to refer the present one to the species already described, than to
add another name to the list of species. The specimens under examination present
many external characters in common with some of the European varieties of A.
cpncentrica.

Geological formations and localities . The original specimens upon which A.
vittata was founded were from Iowa city, in rocks of the age of the Plamilton
group, and it occurs likewise at New-Buffalo in the same geological horizon. The
species of the form figured on Plate 46 occurs in the Corniferous limestone at the
Falls of the Ohio, at Charleston-landing and other places.

ATHYRIS OF THE HAMILTON GROUP.

291

Atliyris cora.

PLATE XLYII.

Atliyris cora : Hall, Thirteenth Report on the State Cabinet, p. 94. 1860.

Shell depressed suborbicular or transversely broad-elliptical, moderately
gibbous ; valves subequally convex.

Ventral valve somewhat more elevated than the dorsal, gibbous upon
the umbo and much elevated above the opposite valve ; apex incurved ;
outline regularly curving to the cardinal and lateral margins ; mesial
sinus more or less strongly defined, sometimes shallow and sometimes
subangularly depressed and reaching nearly or quite to the beak.
Dorsal valve a little less elevated than the opposite, regularly convex
and curving to the margins : the mesial fold is moderately elevated,
sometimes rather abruptly defined at its margins, and flattened or a
little concave above. Surface marked by fine concentric lines of growth
and a few stronger parallel ridges or undulations.

The specimens are in the condition of partial casts, or with the shell
partially exfoliated, so that the original exterior is not fully known. In
these specimens, when the shell is exfoliated, there is a depressed line
marking the centre of the mesial fold, and in some specimens this fea¬
ture occurs without any appreciable elevation. So far as can be observed,
the muscular impressions in the ventral valve are proportionally more
expanded than in the A. spiriferoides, and those of the dorsal valve wider.
The vascular impressions are sometimes very finely preserved beneath
the inner laminae of the shell, and the surface of the cast is strongly
papillose.

In a very symmetrical specimen, the proportions of length and width
of the dorsal valve are as eleven to fifteen, and the length of the ventral
valve of the same individual is a little more than twelve. The greatest
width of specimens is about -ff of an inch.

This species differs from the A. spiriferoides in the character of the mesial fold
and sinus, in the proportional greater convexity of the ventral valve, and greater
elevation of the umbo ; and there are probably other differences which would be
discovered in the perfect exterior, or in the entire muscular impressions.

292

PALAEONTOLOGY OF NEW- YORK.

The figures 1-7 of Plate xlyii illustrate the general features of this species.
Geological formation and locality. In the Hamilton group at Delphi, New York.
A single specimen from the Chemung group is undistinguishable from those of
the Hamilton group.

AtJiyris angelica.

PLATE XLYII.

JLthyris angelica : Hall, Fourteenth Report on the State Cabinet, p, 99. 1861.

Shell ovoid, gibbous, transverse or elongate ; proportions of length and
width variable, the prevailing form longer than wide ; deeply sinuate,
with the beak very prominent ; liinge-line short.

Ventral valve gibbous, most convex above the middle ; mesial sinus
usually extending nearly to the beak, becoming abruptly and deeply
depressed below the middle, and much expanded towards the front of
the shell ; lateral portions of the valve gibbous, and abruptly curving
towards the margins : beak much elevated and curved over the umbo
of the dorsal valve.

Dorsal valve much shorter than the opposite, gibbous, transverse or as
long as wide ; the mesial fold usually not conspicuous above the lower
third of the valve : in the upper part the surface is a little more gibbous,
and the striae along this part are more straight or a little curved back¬
wards, indicating the form during the successive stages of growth.
Surface marked by regular equidistant imbricating lamellae or lamelli-
form striae, the edges of which in perfect specimens are projecting
and slightly crenulate. These lamellae are marked by short inter¬
rupted radiating striae, as shown in figure 20.

The interior of the ventral valve shows a semicircular perforation at
the apex, opening on the lower side to a triangular fissure. The teeth are
strong, and continued in plates to the base of the rostral cavity.
The adductor imprints are strongly marked just below the rostral cavity,
and the divaricator imprints occupy an ovate space below and on each
side. Surface of cast, adjacent to the muscular imprints, strongly
papillose.

ATHYRIS OF THE CHEMUNG GROUP.

293

The muscular imprints of the dorsal valve are not well preserved in
any specimens in my collection. There is a slender longitudinal septum
extending from the beak for one-half the length of the valve.

This species is distinguished from the others here described by the great ine¬
quality of the valves, and by the lamellose strise which are not unlike those of A.
vittcita in the Hamilton group of the west. The specimens are for the most part
poorly preserved, and occur as single valves which arc usually partially exfoliated.
Casts of the interior are not unfrequent, but the material is usually too coarse to
preserve the finer markings.

The figures 9-13 of Plate xlvii illustrate the general characters presented by this spe¬
cies from several localities in Allegany and Cattaraugus counties. Figure 14 is the cast of
a small ventral valve.

Figure 15 is the cast of an elongate form of the ventral valve. Figures 16-19 are illus¬
trations of the cast of a gibbous form from the arenaceous beds in Cattaraugus county.

There may, perhaps, be some doubt whether this species will prove a true Athyris.

Geological formation and localities. This species is known to me only in the
Chemung group. It occurs in the Genesee valley at Philipsburgh and Rockville,
Allegany county ; near Great-valley, Randolph and Cadiz in Cattaraugus county ;
and at Meadville in Pennsylvania.

Athyris ? polita.

PLATE XLVII.

Atrypa polita : Hall, Report on Fourth Geological Dist. N. Y. Tables of Organic Remains, No. 65,
fig. 5. 1843.

Shell subglobose or short ovoid, more gibbous in the upper part, with a
distinct mesial fold and sinus.

Ventral valve scarcely more gibbous than the dorsal, the greatest gib¬
bosity above the middle, flattened near the beak and at about one-third
the length becoming depressed in an undefined sinus which expands
and becomes deeper towards the front ; beak closely incurved over
the umbo of the opposite valve and perforated at the apex.

Dorsal valve with its greatest gibbosity a little above the middle, and
flattened in the centre, curving abruptly to the beak and lateral mar¬
gins ; a broad mesial fold becoming defined at about one-third the
length from the apex, flattened above, and very little elevated at the
sides.

294

PALAEONTOLOGY OF NEW-YORK.

Surface, in well preserved specimens, marked by fine close concentric

striae, with indistinct radiating striae ; the concentric striae sometimes

crowded together in folds or ridges.

A gutta-percha impression from a mould of apparently the same spe¬
cies, and from which the natural cast, figures 27 and 28, was taken, is
distinctly radiatingly striate, as shown in figure 30.

The cast of the ventral valve preserves evidence of moderately strong
teeth with dental plates reaching to the bottom of the rostral cavity,
where they are distinctly limited. The muscular area is only moderately
impressed, and the adductor imprints are cordiform : the surrounding
surface is papillose above and striate below.

In the dorsal valve the muscular imprints are elongate, situated about
the centre of the valve, and separated by a median septum. The surface
of the cast is more or less papillose-striate. In some of the casts the
muscular imprints and septum are scarcely visible, but the latter, when
entirely preserved, has extended below the middle of the length of the
valve.

This is a shorter and more rotund species than either of those described, and
maintains its proportions pretty uniformly. The smallest specimen measured has
a length of four lines and a half, and the original specimen figured ( figs. 23 - 26,
pi. 47 ) has a length of eleven-sixteenths of an inch, with a width which is scarcely
less, and the depth is seven-sixteenths of an inch. A single ventral valve mea¬
sures a little more than three-fourths of an inch in length.

Figures 21 - 26 illustrate typical forms of this species. Figure 31 is a cast of the dorsal
valve ; and figures 27 - 29 are dorsal, ventral and cardinal views of a well marked specimen,
which, however, has not its characters very strongly defined on the dorsal side.

The cast illustrating the interior characters, together with the gutta-percha
impression from the mould of the same, have so much the general aspect and
proportions of the A. polita that I have hesitated to separate them. All the
original specimens of A. jpolita are more or less exfoliated, though apparently
very nearly entire, but none of them give indications of continuous radiating strise.
Although the striated surface is a departure from the prevailing surface characters
of Athykis, .the cast does not present any features incompatible with a species of
that genus.

Geological formation and localities. This species occurs in the Chemung group
at Jasper, Steuben county ; at Randolph and Albion, Cattaraugus county, and
other places in this group in Southwestern New- York.

GENUS MERXSTELLA.

S95

CrENUS MEMSTELEA* (Hall).

This genus was described in the Thirteenth Report on the State
Cabinet in 1860, for shells which had heretofore been included under
the genus Athyris and subsequently under Merista. Differing from
Athyris, they possess the general external form and characters of Merista,
but have not the internal septum so characteristic of the latter genus.f

* See note on page 297.

t In discussing the relations of this group of shells with Athyris and Merista above cited, I
have made the following observations :

Among the fossils referred for many years to Terebratula, Atrypa, etc., European authors have
separated the Genera Athyris and Merista ; shells which have many characters in common, and
which were indeed at first united under Spirigera or Athyris, until in 1851 the Genus Merista was
proposed by Prof. Suess. In my later studies of the Brachiopoda of the American palaeozoic strata,
I have referred to tbe Genus Athyris certain species which have a subglobose or ovoid form, with
lamellose surfaces, and without, or with scarcely perceptible radiating striae ; while other forms, which
are less distinctly lamelloscf and always more or less distinctly radiatingly striate with fine concentric
lines of growth, I have referred to the Genus Merista. Many of the latter have the general form and
surface characters of Merista (Atrypa ) tumida, Dalman, but are less ventricose : they all have inter¬
nal spires, and when perfect, the beaks appear to be imperforate. The radiating striae, though visible
in well preserved specimens, are still more conspicuous in the partially exfoliated shell. Atrypa tumida
of Dalman is cited by Davidson as one of the types of the Genns MerISta.

I proposed last year ( Twelfth Report on the State Cabinet ) a separation of certain Merista-like
forms, under the name Camarium, on account of the presence of an arching transverse septum in the
ventral valve. Subsequently, a more careful consideration of the characters of Merista as given by
Mr. Davidson, and an inspection of his figures, have shown me that this arching septum, in its attenu¬
ation towards the beak, is identical with the shoelifter process described as belonging to the Genus
Merista. An examination of numerous specimens of different species of those which I have referred
to the Genus Merista, shows no evidence of this process or septum ; and the deep muscular impres¬
sion below the rostral cavity, and the thickening of this part of the shell, are characters incompatible
with the existence of the septum. Moreover I conceive that this arching septum, or the extension of
the shoelifter process into the cavity of the valve, would produce such a modification of the soft parts
of the animal that the inhabitants of these shells were generically distinct from those of the large
uninterrupted cavity of the shells which I have heretofore referred to Merista.

In order, if possible, to reach a solution of the question, I have had the shell removed from a solid
specimen of M. tumida ( from Dudley, England ), which is one of the types of the genus, and there is
certainly no evidence of the septum or shoelifter process, but, on the contrary, the presence of all the
characters marking the American species which I have referred to Merista in Yol. iii, Pal. New-York.
At the same time, the Merista (Terebratula ) scalprum of Barrande [M. herculea of Barrande, or
M. scalprum of Rcemer ], in the most solid of the specimens which I possess, readily reveals the
presence of the septum.

PALAEONTOLOGY OP NEW-YORK.

The shells of this genus are oval, ovoid or suborbicular, elongate or
rarely transverse ; valves unequally convex, with or without a median
fold or sinus; beak of the ventral valve often with a circular fora¬
men, and incurved over the umbo of the dorsal valve. Area none ; valves
articulating by teeth and sockets ; surface smooth, or with fine concen¬
tric lines of growth, and with very fine, indistinct or obsolete, radiating
striae.

Since this shoelifter process, or septum, was originally described by Prof. Suess as characteristic
of his Genus Merista, and the species designated by him as the types of this genus (the M. scalprum,
M.herculea of Barrande ) “do possess this feature, the genus must he retained for the species
** with the shoelifter process.”

It would appear, therefore, that the Genus Camarium, proposed by me in the preceding Report,
possesses characters identical with Merista as originally described by Suess, but which have been
overlooked to some extent in consequence of the reference to M. tumida as a typical form of the genus.

* * * * # At the same time, as the M. tumida of Dalman, an English and Swedish species, in

common with numerous well-marked forms in our Silurian and Devonian strata, do not possess this
feature, we can no longer, with propriety, refer them to that genus.

With this restriction, the Meristas proper consist of smooth, ovoid, circular or transverse shells,
with usually a conspicuous sinus upon the ventral valve, and a corresponding wide, often undefined,
mesial fold or elevation upon the dorsal valve ; the hinge articulation being not very different from that
of Athyris, to which they are allied.

The interior of the ventral valve, however, is strongly distinctive ; and the septum or shoelifter
process is not unfrequently shown in the cleavage of the beak of that valve, in solid specimens, where
the interior is inaccessible.

The forms which I have regarded as Merista are similar to those above ; but instead of this sep¬
tum, or shoelifter process, they have a deeply marked triangular muscular area just below the rostral
cavity of the ventral valve, which is bordered on the anterior side by a callosity of the shell, and on
the two other sides by the strong dental lamellae. This feature is not conspicuous in Athyris : the
dental lamellae in that genus are shorter and less strong, and the form of the muscular impression is
different. The dorsal valve of those shells now under consideration has a longitudinal median septum j
a feature which is obsolete, or partially obselete, in the species of Athyris. In the Camarium, or
Merista proper, the exterior of the ventral valve sometimes shows what appear to be two diverging
septa, somewhat similar to those in the dorsal valve of Pentamerus, which are the margins of the
shoelifter process.

The Meristidse begin their existence, so far as we know, in the rocks of the Clinton group ; and in
this and the Niagara group there are several species, while they are more numerous in the Lower
Helderberg group : they occur likewise in the Upper Helderberg rocks, and in the Hamilton group.
Merista proper, so far as we know, appears first in the Lower Helderberg period, while Athyris is
known in two species for the first time in the Hamilton group [also in Upper Helderberg group].

Restricting, therefore, the signification of the Genus Merista to such forms as were originally
included by Prof. Suess under that name, it becomes necessary to designate those species of similar
form, but without the peculiar appendage of the ventral valve, by another generic term ; and I would
therefore suggest the name Meristella, proposed by me last year.J
t Twelfth Report on the State Cabinet, p. 78.

GENUS MERISTELLA.

297

The interior of the dorsal valve is marked by the presence of a strong
hinge-plate or cardinal process ; and from the base of this proceeds a
thin longitudinal septum, which often extends for half the length of the
valve.

The interior of the ventral valve shows a triangular fissure below the
beak, which joins a semicircular perforation at the apex. At the base of
this fissure are two strong teeth, which extend in thickened or slender
plates to the bottom of the cavity, and curve around the upper part of
the muscular area, which is broadly triangular or ovate.

There is sometimes a thickening of the shell at the base of the rostral
cavity, which abruptly limits the muscular impression; but there is
neither septum nor rudiment of one as in Merista.

In well-preserved specimens of M. haskinsi, where the apex is not too
closely incurved, the ventral beak has a circular foramen, and the triangu¬
lar space below, which is usually filled by the beak of the dorsal valve,
is closed by two deltidial pieces anchylosed in the centre. The latter
feature has been observed in M. harrisi , and probably existed in all the
species at some period of their growth.

The study of the interior has shown that the thickened bases of the
crura extend forward for a short distance, or bend abruptly to the
ventral side, but recurving, descend into the cavity of the dorsal valve,
following its contour and that of the ventral valve in their succeeding
volutions. In the bottom of the dorsal valve, the lamellae, in the course
of the first volution, are united by a loop which is produced by the
extension of a slender process from the band on each side, and these are
united at a greater or less distance from their origin. Beyond this junc¬
tion the parts of the loop again divide, and each one is produced in a
curving band which arches forward on the ventral side, and thence
returning is reunited to the sides of the. loop at or near the junction of
the parts before noticed.*

* In the Canadian Journal of Industry Science and Art, for March, 1861, Mr. Billings has under¬
taken to define the limits of the Genera Athyris, Spirigera, Merista, etc. ; strenuously objecting
to the introduction of the generic name Meristella. At the close of the same article, he proposed
[ Paleontology IV.] 38

398

PALAEONTOLOGY OP NEW-YORK.

These features are illustrated in the accompanying diagrams; fig. 1 being an oblique lateral
view of the central portion of the spires, and fig. 2 a view of the same parts from the dorsal
side.* *

Meristella arccata. Meristella arcuata.

In these figures, a indicates the origin of the crura ; b the recurvation of the lamellae,
which may be as represented, or with a simple retral -bending without recurving upon itself
in some species ; c is the continuation of the lamellae, which at d give off the processes
forming the loop, and these become united at e and continue simple to f, where they bifurcate
and continue in the direction g, returning again to the centre, and reuniting with the loop at
A, or near the junction of the two parts before mentioned.

These characters of the spires and loop have been observed in the M. la&vis , M. arcuata and
M.princeps of the Lower Helderberg group, and in thg M. barrisi of the Hamilton group;
while the M. nasuta presents a slight modification in the extension of the parts of the loop,
which ally it more nearly with Athyris.

"When compared with the spires of Athyris as shown in the figures already
given under that genus, as well as the illustrations of Davidson and other authors,
the differences are obvious. The parts of the loop in this genus, instead of curving
forward and there uniting and turning backward and bifurcating, to form the
accessary lamella, are continued from their origin obliquely backwards into the
cavity of the ventral valve, and, then recurving upon themselves, are reunited
laterally ; while in Athyris, they are intercalated between the first and second
turns of the spire, and coalesce with the lamellfe of the latter.

the generic name of Charionella ; professing to “ have ascertained the generic characters of the
so-called Jltrypa or Mhyris scitula,” a species possessing the characters of Meristella, and none,
so far a& known, which do not belong to that genus. He has subsequently united under the same name
several other species of the latter genus. It is scarcely necessary to add that the characters of hinge,
as described and illustrated in the dorsal valve of Charionella by Mr. Billings, do not exist in any
species of this family (Spiriferidse) of Brachiopoda.

* The words upwards and downwards, used in the descriptions of the spires in Athyris and
Meristella, have reference to the position of the figures only, which are represented with the dorsal
side below ; since the illustrations could be more satisfactorily given in this position. ;

MERISTELLA OF THE UPPER IIELDERBERG GROUP.

S99

At tlie same time, an examination of the Niagara species referred by me to the
Genus Meristella presents a different condition of the interior, and shows the
lamellfe of the spires united by a simple loop only.

This feature is illustrated in the accompanying diagram, which represents a single turn
of the spiral lamellae, from their origin at a , to i where the bands are cut off. The thickened
bases of the crura are represented at a; l is the point of recurvation, c the continuance of
the lamellae in the dorsal cavity, and d the expansion on the inner side into long processes
which unite at e, forming the loop.*

Meristina maria ;

Showing the first volution of the spiral lamellae.

' The same characters have also been observed with equal distinctness in M. nitida of the
Niagara group. In neither of these species is there any indication of accessary lamellae as in
Athyris, nor evidence of the extension of the loop beyond the point e; and we are there-
- fore induced to believe that the simple character of the spires in these forms will constitute
another distinction, which may conveniently be termed Meristina.

Meristella nasuta.

PLATE XLVIII.

Atrypa nasuta .- Conrad, Ann. Report on the Palaeontology of New-York, p. 18.

Meristella nasuta ( Conrad sp.) : Hall, Thirteenth Report on the State Cabinet, p. 98. 1860.
Meristella elissa : Hall, Fourteenth Report on the State Cabinet, p. 100. 1861. Fig. 21 & 22, Fif¬
teenth Report. 1862.

Meristella nasuta : Hall, Fifteenth Report on the State Cabinet, p. 160 ; figs. 17-10, p. 161. 1862.

A thyiis clara : Billings, Canadian Journal, p. 274. 1860.

Athyris clara : Geology of Canada, p. 373, fig. 397. 1863.

Shell suboval, ovate or subrhomboidal, the greatest width near or a little
below the middle ; the length equalling or greater than the width.
Valves convex, the ventral valve gibbous. A nasute or linguiform
extension of the front in old shells.

# The point of junction in these parts varies in different species ; and even in what appear to be the
same species, the points of junction are not identical in all individuals.

3©@

PALAEONTOLOGY OF NEW-YORK.

Ventral valve much the more convex, the greatest convexity being a
little above the middle, becoming gibbous and extremely arcuate in
old individuals, curving abruptly to the sides and cardinal margins,
and more gradually to the front : umbo extremely prominent; beak
neatly rounded and closely incurved, standing at a right angle with
the plane of the axis, or in old shells directed forwards. The anterior
portion is produced into a nasute or linguiform extension, usually
without a sinus or any depression of the surface. In the young or half
grown individuals, this feature does not appear.

Dorsal valve less convex than the opposite, moderately and regularly
convex in the young shell, becoming in the old shells gibbous above,
curving regularly to the sides, and often a little flattened at the baso-
lateral margins ; at about the middle of the length, or sometimes
above, the central portion of the valve becomes more gibbous, and
towards the front is abruptly elevated into a short rounded promi¬
nent fold, corresponding to the linguiform extension of the opposite
valve. The beak is moderately incurved, lying close beneath that of
the. opposite valve.

The general aspect of the surface is that of a smooth shell with a few
concentric lamellose lines. In perfect specimens, however, the entire
surface is marked by fine close concentric- strige, and usually by indis¬
tinct radiating striae, which are often more conspicuous in the partially
exfoliated shell, and still more distinct in some of the casts.

The interior of the ventral valve preserves the generic characters in
a marked degree, in the open fissure beneath the beak, which is termi¬
nated by a subcircular perforation ; in the strong dental plates, and
deeply marked muscular impression, as shown in fig. 18 of Plate xlviii.
The inner surface surrounding the muscular impression is radiatingly*
striated. The reverse of these features is shown in the casts of smaller
individuals, from the Schoharie grit, figs. 3 and 4, wher§ the muscular
impression and rostral cavity are excessively developed ; also in the
larger and more symmetrical figures 5 and 6.

MERISTELLA OF THE UPPER LIELDERBERG GROUP.

SOI

The interior of the dorsal valve shows a strong cardinal process, with
a shallow spoon-shaped depression in the centre, margined by deep teeth
sockets. The muscular area is elongate-ovate, broader above, and divided
through the centre by a thin elevated septum. These features are shown
in fig. IT ; and also in the casts of the dorsal side, figs. 1, 2, 20 and 22.

The crura apparently bend downwards from near their origin ;
thence recurving, they follow very closely the contour of the dorsal
valve, making thirteeh or more turns in an individual of medium size.
Spires, slender and simple. The spires and median septum are shown
in figure 19.

In the young shell, this species is. symmetrical and nearly circular; the
smallest measured specimen has a length and width of about half an inch.
The valves are very regularly convex, the dorsal valve becoming gibbous
in the upper part, with a scarcely perceptible undulation of the
front margin. Some specimens of an inch in length have an equal width ;
but generally as the shell becomes older, the length exceeds the width.
The nasute extension in front is at first acute in most specimens, becom¬
ing broader and linguiform in older specimens.

The figures on Plate xlviii, from 7 to 16 inclusive, show the prevailing form and features
of the genus.

The specimen illustrated in figures 23-25 is that which I have described as M. elissa ;
but this is only an extreme form of M. nasuta with an unusual linguiform extension, a
remarkably gibbous and arcuate ventral valve, and a 'dorsal valve less convex, as in some
smaller individuals.

This species first appears in the Schoharie grit, where it is sometimes very fully
developed, but frequently is only obtained in meagre casts, like figures 3 and 4.
It is more abundant in the Corniferous limestone, here presenting its greatest
extremes in form and proportions.

This shell is described by Mr. Billings, Joe. cit ., under the name of Atliyris
claret ; but the same has been long known as Atrypa nasuta of Conrad, and I
preserve that specific name as having priority.

Both in general exterior form and internal characters this species bears much
resemblance to MeristeJJa {Airy pa ) tumida , Dalman ; but in that one there is a
more distinct sinus in the ventral valve, while the umbo is more gibbous, the
beak larger and more incurved, and the entire shell is comparatively more
ventricose. The muscular area in the ventral valve is of the same shape, but
narrower than the prevailing form in our species.

PALAEONTOLOGY OF NEW-YORK.

Geological formations and localities. This species occurs in the Schoharie grit,
in Albany and Schoharie counties, usually of medium size and well marked cha¬
racters, and sometimes attaining larger dimensions. It occurs in the limestone of
the Upper Helderberg, in Albany and Schoharie counties, and at nearly all the
localities of that rock as far as the Niagara river ; particularly at Clarence and
Williamsville in Erie county. It is found at several localities in Canada West 5
also at the Falls of the Ohio and at Columbus and Millford, Ohio, and probably
at Sandusky and other localities of the Corniferous limestone in the West. Some
large imperfect valves in the Hamilton shales of Centra^ New- York may probably
be of this species.

Meriste!JaL§citiila.

PLATE XLVII.

Atrypa scitula : Hall, Geol. Report of the Fourth District New -York, p. 171, f. 1. 1843.

Not Alhyris (?) scitula : Hall; Billings in Canadian Journal (n. s.), No.xxvii, p. 278, f. 35 &, 36.

1860.

Charionella circe : Billings, Canadian Jour, (iv s.), No. xxxviii, p. 273, f. 100. 1861.

Not Terebratula circe, Barrande ( Spirigera circe, d’Orbigny), Naturwissenschaftliche Abhandl.,
pa. 393, pi. 10, f. 6 (1857), which is apparently congeneric, and a true Meristella.

Shell ovate or ovate-spatulate, compressed towards the base.

Ventral valve the more convex, sometimes gibbous above the middle,
depressed in the lower part ; umbo prominent, with the beak elevated
and incurved above the umbo of the opposite valve. The shell curves
gently to the base and baso-lateral margins, but becomes abruptly
incurved above the middle, and concave on each side for some distance
below the beak ; the proportions of breadth above are as six to five, or
seven to six.

Dorsal valve depressed convex in the lower part, more convex and
somewhat gibbous above the middle ; beak small and rather prominent.
Surface marked by fine concentric striae, which, from the usual partial
exfoliation of the shell, are often scarcely perceptible : more rarely
1 some remains of obsolete interrupted radiating striae are perceptible.
The shell, as it usually occurs, is smooth and glabrous.

This species has the usual features of others of the genus. It differs from M. doris
in being less gibbous, with a lesser arcuation of the ventral valve, the upper
■part less elongate and attenuate, and a less extensive flattening of the sides of the
shell.

MERI8TELLA OF THE UPPER HELDERBERG GROUP.

. It differs from M. harrisi , in being* less gibbous and proportionally broader. It
is more elongate than M. hasJdnsi less rounded in the outline of the lower part,
and does not present the conspicuous rounded foramen of that species. It has not
proved a common species in' the limestone, only a few specimens being known.

' ' Geological formation and localities. This species occurs in the Coruiferous lime,
stone at Williamsville and Clarence-hollow, Erie county, N. Y. .

Meristella doris.

PLATE L.

Meristella doris : Hall, Thirteenth Report on the State Cabinet, p. 84. 1860.

Charionella doris : Billings, Geology of Canada, p. 374. 1863.

Shell subovate, elongate, gibbous above and more or less compressed
below the middle, with the anterior and antero-lateral margins
attenuate and sharp ; sinuate on the ventral side below the middle,
and the front produced in a broad extension.

Ventral valve a little more or less convex than the dorsal, gibbous above
the middle : a mesial depression, often beginning about the middle of
the length, becomes broader and deeper towards the front, sometimes
affecting nearly the entire width of the shell. This sinus is sometimes
barely perceptible, and is sometimes a narrow, almost linear depres¬
sion in the upper part of the shell. The umbo is prominent and the
beak strongly incurved : an angular ridge extends from this point
obliquely bn each side to below the extremities of the hinge-line, on
which the shell is bent abruptly (and on the upper part acutely)
inwards. The central upper portion of the valve is prominent, and
between this and the oblique ridge the surface is depressed or flat¬
tened. The apex is usually apparently closed, but from accident or
otherwise it often presents a circular foramen : the triangular space
beneath is closed by deltidial pieces, or sometimes open.

Dorsal valve sometimes more convex than the opposite, usually gibbous
in the middle and above, and curving rather abruptly towards the
lateral margins, in the older shells it becomes a little flattened or even
concave near the edge. The central elevation continues to the front,
without becoming a distinct mesial fold.

S04

PALEONTOLOGY OF NEW-YORK.

Surface marked by line close concentric striae, beneath which are dis¬
tinct radiating striae, and the latter become more distinct on the
partially exfoliated surfaces.

The cast of the ventral valve shows a large rostral cavity, with evi¬
dences of strong teeth and extended dental plates. The muscular area is
narrow and elongate. In the dorsal valve, the muscular imprint reaches
half way from beak to base of the valve ; the septum scarcely reaches
so far.

This shell is usually readily distinguished from the other species of the Upper
Heklerberg and Hamilton groups by its elongate form, which is compressed
and laterally expanded towards the front ; by the remarkable arcuation of
the ventral valve, and the strong angular lateral ridge which extends from a
little above the middle to the apex, nearly in the same curve as the junction of
the valves in their anterior half.

In this feature, and in the less incurvation of the beak, it is distinguished from
some varieties of M. nasuta ; and in the same manner it is distinguished from
M. barrisi and M. haskinsi, which are always proportionally shorter shells.

The figures 2-7 illustrate the characteristic forms of this species; figures 8-10 show
the extreme features of the larger individuals. The extreme length is about one inch and
three-fourths, with a width of a little more than an inch and one-fourth. Figure ll is the dor¬
sal valve of a large individual which is much broader than usual in proportion to its length.
Figure 12 is a cardinal view of a cast of this species, showing the median septum of the
dorsal valve, and cavities made by the dental lamellae of the ventral valve.

A single specimen, figure 1, from the Schoharie grit, appears to be of this species.
Geological formation and localities. This species has been chiefly obtained
from some loose masses of the upper part of the Corniferous limestone near
Williamsville, Erie county. One specimen only has been obtained from the Scho¬
harie grit, in Schoharie county.

Meristella barrisi.

PLATE XLIX.

Meristella barrisi : Hall, Thirteenth Report on the State Cabinet, p.81. 1860.

Shell ovoid, more or less elongate and sometimes broadly ovate, gibbous :

valves subequally convex, sinuate in front.

Ventral valve gibbous in the middle, the greatest convexity a little
above the middle of its length, and abruptly sloping to the sides, flat-

MEBISTELLA OF THE HAMILTON GROUP.

805

tened below the middle, becoming depressed towards the front, which
in old shells is produced into a short linguiform extension : umbo
gibbous, the beak arching over the umbo of the opposite valve and not
closely appressed.

Dorsal valve little longer than wide, varying from moderately convex
to gibbous, the greatest convexity being about the middle of its length ;
without distinct mesial fold, but abruptly elevated near the anterior
margin, corresponding to the depression on the opposite side.

Surface smooth, or marked by regular concentric strise which are some¬
times crowded into wrinkles near the margins of the valves. The
exfoliated shells sometimes show indistinct radiating strise.

The muscular impression in the ventral valve is triangular, and usually
not deeply marked. The dorsal valve has a distinct median septum which
extends nearly half the length of the valve : muscular area narrow,
elongate.

This species presents considerable variety of form, from almost sym¬
metrically oval to broadly ovate with the greatest width below. The older
shells are for the most part gibbous, but some specimens are compressed in
the lower half of the length. The mesial sinus is not usually a very dis¬
tinctive feature in half-grown shells; but in some individuals it begins
about the upper third of the shell, and affects the lower half and ante¬
rior part of the valve.

The largest individuals have a length of about one inch and a quarter,
with a width of one inch ; in other specimens, a length of one inch and
an eighth gives a width of one inch and a depth of three-fourths of an
inch. In a gibbous and somewhat elongate form, the depth and width
are as 5 to 6, and the length 8j.

Figures 5-12, and 16 & 17, represent the most characteristic forms.

Figures 13 & 14 are of an extreme form.

Figure 20 is one of the broader forms.

Figures 21 & 22, dorsal and front views of a cast of this species.

Geological formations and localities. This species has been found chiefly in a
limestone of the Marcellas shade, near Le Roy, N. Y. It occurs in the Hamilton
group, near York in Livingston county, New-York.

[ Palaeontology IV.] 39

JI06

PALEONTOLOGY OF NEW-YORK.

Meristella haskmsi.

PLATE XLIX.

Meristella haskinsi : Hall, Thirteenth Report on the State Cabinet, p. 84. 1860.

Shell broadly ovate, more or less gibbous ; length and breadth nearly
equal, the greatest width anterior to the middle; slightly sinuate in
front. In many well-formed specimens the length and width are about
equal; when the length is greater, it is due to the extension of
the beak of the ventral valve.

Ventral valve regularly convex, often gibbous above the middle, and
curving regularly to the sides and more gently to the front, which is
sometimes a little impressed at the margin by a broad shallow sinus :
beak elevated, slightly incurved and broadly truncated by a circular
foramen. The triangular space beneath the apex is occupied by delti-
dial plates, which appear to be closely anchylosed in the centre.
Dorsal valve usually a little wider than long, moderately convex in
young shells, gibbous in the middle and above in older specimens,
curving regularly to the sides and front, and scarcely affected by the
slight elevation near the anterior margin : beak short, and neatly
incurved beneath the deltidial plates of the opposite valve.

Surface marked by fine concentric strim, which are raised and thread¬
like, and sometimes crowded together in fascicles : these appear also
to be indistinctly radiate or crenulate. In exfoliated specimens there
are sometimes distinct radiating striae upon the surface.

The rostral cavity of the ventral valve is narrow, the teeth are of
moderate strength, and the dental plates reach the bottom of the cavity
and extend forward ; the muscular area is broadly triangular and strongly
striate. In the dorsal valve the muscular area is ovate or cordiform, and
extends below the middle of the valve ; the low slender septum extends
a little beyond the muscular area.

This species is quite distinct, in its various phases, from the M. bcirrisi, which
is more gibbous, with the ventral beak more closely incurved. In well-preserved

MERXSTELLA OE THE HAMILTON GROUP.

specimens, the beak of M. haskinsi is sufficiently elevated to allow the deltidial
covering of the fissure to be visible. In specimens where the surface is well pre¬
served, the striae offer a distinguishing character.

The figures 23-35, Plate xlix, illustrate this spee'es in its principal varities of form and
size. In figures 32 & 34, the deltidial plates beneath the foramen are visible.

Figure 35 is a partial cast of the dorsal valve, showing the filling of the rostral cavity
and the form of the muscular impression.

Figure 36 is a partial cast of the dorsal valve, preserving in part the muscular impression.

The fossil figured in the Report of the Fourth District, p. 202, fig. 5, is probably an exfo¬
liated specimen of this species.

Geological formation and localities. This species occurs in the shales of the
Hamilton group, on the shores of Seneca lake, at Geneseo, York, Moscow and
Leroy, in Livingston county, and at Eighteen-mile creek in Erie county.

Meristella rostrata.

PLATE L.

Jllrypa rostrata : IIall, Report on Fourth Geol. District of New-York, p. 202, f. 2. 1843.

Shell small or of medium size, ovate, rounded below and often subat¬
tenuate above ; valves subequally convex ; length and breadth about
as eleven to eight or nine.

Ventral valve scarcely more convex than the dorsal, a little gibbous
above the middle, gradually curving to the basal and baso-lateral
margins, while above the middle the edges are abruptly incurved :
umbo prominent; beak more or less strongly incurved over the umbo
of the opposite valve; the lower part of the valve, and sometimes
f the entire length, marked by a shallow rounded sinus.

Dorsal valve regularly convex, somewhat more prominent above the
middle ; slightly or not at all elevated in front from the influence of
the sinus of the ventral valve.

Surface of partially exfoliated valves marked by conspicuous but slen¬
der and distant radiating striae : fine and closely arranged concentric
striae mark the entire surface, and towards the margins these are
crowded in strong folds.

Shells of this species are scarcely three-fourths of an inch in length
in the largest specimens observed. The proportions of length and breadth
vary considerably.

a®8

PALAEONTOLOGY OF NEW-YORK,

Figures 13 - 17 are illustrations of this species.

Geological formations and localities. This species occurs in calcareous beds iu
the upper part of the Hamilton group, at Eighteen-mile creek ; and in the Tully
limestone, near Ovid, in Seneca county.

Meristella meta (n. s.).

PLATE XLIX.

Shell subglobose, or very gibbous, short ovate ; the valves subequally
convex, marked by a conspicuous sinus in front ; hinge-line about
two thirds the width of the shell.

Ventbal valve very gibbous ; umbo prominent, with beak abruptly
nasute ; the upper part of the valve marked by a shallow scarcely
defined depression, which becomes a deeply marked subangular sinus
in front.

Dobsal valve regularly convex, gibbous in the middle and above ; ante¬
rior margin broadly sinuate, and the lower part of the valve marked
by a narrow median depression.

Sueface concentrically striated, with faint indications of interrupted
radiating striae. In the specimens examined the shell is partially
exfoliated, and the entire surface-characters cannot be ascertained.
The figures 1 - 4 of Plate xlix illustrate this species.

This fossil is referred to Mekistella from its general form, the fibrous texture
of the shell, and the form of muscular area in the ventral valve>

Geological formation and localitiy. In calcareous bands in the Hamilton group
at Delphi*, Onondaga county, N. T.

Meristella? - ?

PLATE XLVII.

The illustrations, figures 32 and 33 of this plate, are of casts of what
appeal to bo a species of Mebistella from the Chemung group, though
no exterior of a similar shell has been found in the rocks of that
formation

MERISTELLA OF THE UPPER HELDERBERG GROUP.

309

Meiistella unisiilcata.

SUBGENUS ? PENTAGONIA (Cozzens).

PLATE L.

Atrypa unisulcata : Conrad, Annual Report on the Palaeontology of New-York, p. 56. 1841.
Rhynchonella unisulcata : (Conrad, sp.) Hall in Tenth Report on the State Cabinet, p. 125. 1857.
Jltrypa unisulcata t referred with doubt to Meristella, and name Gonioc<elia proposed, in
Fourteenth Report on the State Cabinet, p. 101. 1861.

Compare Pentagonia peersii, Cozzens, Annals of the New-York Lyceum, Yol. iii, pa. 158, pi. x, f. 2 a, b.

1846.

Shell subtrigonal, quadrilateral or sometimes subhexagonal in outline,
wider in front, with the sides sometimes sloping from the beak ; and
in others, the hinge-line extended nearly straight, and the sides nearly
rectangular to it. A wide mesial depression on one side, with promi¬
nent elevation on the other.

Ventral valve with a broad deep mesial sinus which occupies nearly
the whole width of the valve, and is bounded on either side by an
angular elevation which extends from the beak to the baso-lateral
angles. The portion of the valve outside of the limitation by the sinus
is abruptly inflected upwards, often nearly at right angles ; the umbo
is prominent, and the beak is incurved over the umbo of the dorsal
valve.

Dorsal valve gibbous in the middle ; the centre occupied by a prominent
mesial fold, from which the surface slopes abruptly to the lateral
angles, becoming more op less conc&ve within the lateral and cardino-
lateral margins. The mesial fold is marked along the centre by a single
deep groove, which extends to the beak of the valve.

Surface marked by fine concentric striae, and sometimes by strong
imbricating folds. In well preserved surfaces the striae and undulations
are bent backwards in the middle of the mesial sinus, indicating a
mode of growth in the shell corresponding to the ginus in the mesial
fold of the opposite valve. There are also slight indications of inter¬
rupted radiating striae. In the spe-cimen from the Hamilton group

310

PALEONTOLOGY OF NEW-YOKK.

there are appearances of faint undefined continuous striae. The speci¬
mens from the limestone are for the most part partially exfoliated, or
have the shells silicified, by which the finer markings are obliterated.
The interior of the ventral valve shows a perforation in the beak,
opening below into an angular space which has been occupied by the
beak of the dorsal valve, and thence communicating with the main cavity
of the valve. The base of the fissure is margined on each side by a strong
tooth which, extends in strong dental plates to the bottom of the cavity,
and these are often continued in a thickened ridge bordering the muscu¬
lar impression. The imprints of the adductor muscles are opposite the
bases of the dental plates, and below and on either side are the imprints
of the broad divaricator muscle.

In the dorsal valve the cardinal process is broad and strong, the crural
bases somewhat widely diverging, and the centre abruptly depressed ;
the teeth-sockets are large, and supported by strong lamellar callosities
which extend along the inner side of the valve nearly parallel to the
exterior margin. The muscular imprints are divided by a low distinct
septum.

This shell presents considerable variation in its forms and general aspect, though
always preserving its unmistakable character. In young and half grown shells,
where the hinge-line is but little extended, it has a general triangular form, as in
figures 21 and 22 ; when the hinge-line becomes extended and the sides nearly
straight with a moderately curving base, it is quadrangular, as in figures 18 and 19..
Figure 26, upon the ventral side, is somewhat hexagonal ; while figure 33 is
decidedly pentahedral in outline. There is rarely some little elevation in the cen¬
tre of the mesial sinus, and sometimes a groove with an elevation on either side.

The beak of the ventral valve is sometimes not closely pressed upon the dorsal
umbo, but is usually so, and sometimes to such a degree that the apex is depressed
into the groove of the mesial fold.

I have heretofore ( Fifteenth Report on the State Cabinet, p. 147 ) called atten¬
tion to some peculiarities near the cardinal margin of this species. In a cardinal
view of a well preserved specimen from the Upper Helderberg limestone of New-
York (fig. 28), there is a ridge on the cardinal margin crossing the hinge-line with
slight obliquity, and occupying a space on both sides. In a specimen from the
Hamilton group, this fold is more oblique, rising from near the beak, as shoAvn
in figure 35, Plate l ; while there is a second fold on the side of the shell.

MERISTELLA OF THE UPPER HELDERBERG GROUP.

311

In a specimen from the Upper Helderberg limestones of the Falls of the Ohio
(fig. 32 of pi. l ), the fold is sharp and clearly defined, slightly oblique and
limited to the dorsal valve, being intermediate in character to the former two ;
while the specimen is more gibbous than usual.

I have heretofore proposed ( loc. cit.) to designate these varieties of Meristella
unisulcata, thus recognized, as var. uniplicatd for the specimens from the western
limestones, and as var. biplicata for the Hamilton group form.

Geological for nation and localities. This species is not uncommon in the Upper
Helderberg limestone, in Albany and Schoharie counties, and generally through¬
out the extent of that formation within the State ; though nowhere abundant. It
occurs in the same limestone at the Falls of the Ohio, and in Canada West. In
the Hamilton group, it has been collected on the shore of Canandaigua lake. Casts
of the same species have also been observed in the Oriskany sandstone.

Note. I would, in this connection, call the attention of the student to the illus¬
trations of the internal spires of Athyris, Meristella and Meristesta. The
modification of the parts are confined to the connecting loop of the crura : and
neither in these, nor in any of the genera of the Spiriferid/B, is there any
important variation in the form of the spires proper, while there are various
modifications of the loop ; and I am disposed to believe that others will yet be
found, perhaps even in the Genus Spirifera itself. These modifications of the
form and direction of the parts become exceedingly interesting when compared
with the various forms of the loop shown in the several genera of the Family
Terebratulid/E, the most of which began their existence upon the waning of the
spire-bearing forms, or acquired their fullest development in later geological
epochs where the Spiriferiile are comparatively rare or entirely unknown. This
modification of S-ura and loop in the later genera is developed more extremely
in the absence of spires, which acquired their greatest development in medial
geological times, or about the Devonian or Carboniferous periods, almost at the
same time that the terebratuloid genera began their existence.

31*

PALAEONTOLOGY OF NEW-YOEK.

Genus Atrypa (Dalman).

SPIRIGERINA (d’Oebignt) .

The Genus Atrypa was founded by Dalman in 1827, to include a group
of palaeozoic shells which he described as “ inequivolve , biconvex, hinge-line
“ rounded , beak of larger valve covering the base of smaller valve, apex
“ imperforate

Under this genus the two first named species are A. reticularis of
Linnaeus and A. aspera of Schlotheim, both of which have a perforation
in the apex of the ventral valve, though it is often concealed by the
curvature of the beak. Notwithstanding that the name in its signification
is a misnomer, it has been very generally adopted, and for a long time
it was used by some authors to include species usually referred to Tere-
bratula, but which have only a remote relation to that genus, and are
now distributed under various generic designations.

Restricting the signification of the term Atrypa to forms congeneric
with those above referred to, we have a well-defined and strongly marked
group of shells which may be characterized as follows :

Shells suborbicular, transverse or elongated; valves articulating by
teeth and sockets : beak of the ventral valve produced and incurved;
the apex truncated by a sinall round perforation, whic? is sometimes
separated from the hinge-line by a deltidium ; a false area in some
forms well-defined, but often not existing in the same species.* This
valve is more or less convex or nearly flat, sometimes with a broad and
well-defined sinus, and often with a scarcely perceptible depression.
Dorsal valve convex, often extremely gibbous; with or without a
mesial fold.

# This false area is formed by the thickening of the shell in the bottom and sides in the upper part,
and the final filling up of the rostral cavity above the line of the teeth ; the pedicel-groove being
sometimes visible to the base of the area, but there is scarcely evidence of its passage beneath it, and
the apex is apparently solid. The condition of the shells examined, however, is such that there possi¬
bly may have been a minute foramen in the living shell, which has been closed by mineralization in
the fossil.

GENUS ATRYPA.

313

Surface smooth, striate or costate, and often strongly imbricated by squa-
mose lines of growth, which are sometimes produced in foliacious expan¬
sions, nodes, or tubular spines. Structure fibrous.

In the ventral valve there is a strong tooth on each side at the base of
the broad fissure : these teeth are somewhat bilobed at their summit, with
a broad crenulated groove on the back : from the base of the teeth a curving
ridge extends forwards, and partially encloses a broad muscular area.

In the dorsal valve, the hinge-plate i^ usually or always divided in the
middle, with a distinct toothlike plate on each side, and the crura origina¬
ting on the outside of these, close to the dental sockets ; while on the outside
of the latter, close to the shell margins, there is on each side a crenulated
fold, which occupied the groove at the base of the tooth, and this appears
to be of generic significance. The spires originating from the crura form
two large hollow cones which are directed into the cavity of the dorsal
valve, their adjacent sides being flattened, and the apices brought close
together near the centre of the bottom of the cavity. The extreme gib¬
bosity of this valve in many of the older shells gives great space for the
development of the spires.

The crura are usually represented as having a pointed process from near
the base of the spires on each side, directed towards the centre. These
processes, however, unite in the cavity of the dorsal valve to form a loop
connecting the spires.*

* While this volume has been passing through the press, it has been shown by Mr. R. P. Whitfield
that the short processes usually represented near the base of the crura in the spires of Atrypa are
directed into the cavity of the dorsal valve, and are there united to form a loop, and that the character
of this loop varies in different species, or in forms recognized as simple varieties of Atrypa reticularis
(See Nineteenth Report on State Cabinet). I have also received, some time since, from Dr. C. Romin-
ger, of Ann Arbor, Michigan, a specimen of the atrypa nodostriata , showing the spires, and which by
farther cutting has revealed the connecting loop. A specimen of A. reticularis, sent me by Dr. Knapp,
of Louisville, Ky., from the Falls of the Ohio, preserves the spires and connecting loop, all heavily
covered by chalcedonic quartz ; and another specimen from the same locality has, by a careful removal
of the ventral valve, revealed the spires and loop. The same features are also shown, although in a less
perfect manner, in a silicified specimen from the Hamilton group of Iowa, received from Mr. 0. St.
John.

[Palaeontology IV.]

40

314

PALAEONTOLOGY OF NEW YORK.

The muscular area in the bottom of the dorsal valve is usually divided
by a median ridge; and in old shells of some of the species, this area
becomes very strongly defined.

The vascular impressions, in both valves, originate on each side near the
base of the muscular area, and divide into two principal trunks which
diverge towards the hinge-line and the front of the shell, and give off
numerous lateral bifurcating branches.

The prevailing and conspicuous forms of this genus have been generally referred
to two species, or rather to a single species, the Atrypa reticularis of LiNNiEus and
its varieties ; though more recently the A. • desquamata of Sowerby has been
doubtfully admitted as a distinct species. ' My own investigations do not lead to
the adoption of this view, though I admit that there are many difficulties in the
way of specific determination, especially where the shells are exfoliated or com¬
pressed ; but the examination of large numbers of individuals, together with the
interiors of many of them, has compelled me to recognize as distinct species some
of those which are usually considered as varieties . only. How far the complete
study of the interior structure, and of the spires, will sustain the separation of
species, remains yet to be determined.

In order for a satisfactory solution of all these difficulties, a series of observa¬
tions should be made upon extensive collections of individuals from widely separated
localities iu the same geological horizon, and also from different geological forma¬
tions, to learn the effect of geographical and chronological influences. I conceive
that until such investigations shall have been made, we are not prepared for a
final determination of the questions of specific difference or identity.

Two species of this genus are of common occurrence in the Niagara and one in
the Lower Helderberg group ; and though I have referred the more common form
to A. reticularis , there is usually no difficulty in recognizing the specimens from
each formation, or in distinguishing them from those of the Upper Helderberg
and Hamilton groups. The same observations are almost equally true of those in
the higher rocks ; but at the same time we find strongly marked features of dis¬
tinction iu individuals from widely separated localities of the same formation.

ATRYPA OF THE SCHOHARIE GRIT.

315

Atrypa impressa.

PLATE LI.

Atrypa impressa: Hall, Tenth Report on the State Cabinet, p. 122 (Pal. Fossils, p. 82). 1857.

Shell somewhat ovoid, often extremely gibbous ; length and breadth nearly
equal.

Ventral valve depressed convex in the lower part, becoming gibbous above,
more prominent along the middle, but without any defined elevation, and
without sinus, except in very rare examples where the extreme front
of the shell is bent upwards in the middle : beak closely incurved over
the umbo of the opposite valve.

Dorsal valve the larger, very convex, and becoming extremely gibbous in
full grown and old shells. A more or less distinct mesial elevation marks
the lower half of its length : this is often flattened, giving an obtusely
angular outline, and the centre is marked by a narrow depression : the
front is squarely truncate or impressed.

Surface marked by numerous radiating striae or costae, which are frequently
bifurcated, and crossed by numerous concentric lamellose lines of growth.
The casts of the interior, which are more abundant than any other con¬
dition of the fossil in the Schoharie grit, present considerable variety of
aspect. The cast of the ventral valve is usually a little convex, or nearly
flat outside of the muscular area, and often a little more prominent in the
middle than at the sides. The muscular area is broad flabelliform, wider
than long, depressed and smooth on each side above, with a central promi¬
nence for the attachment of the adductor muscles, from which there is
usually a sharp carina extending to the beak : there is also a less conspicuous
ridge on each side, extending obliquely from the apex to the base of the
cavity left by the teeth. Outside of the muscular area the surface is
strongly papillose, and sometimes marked by vascular impressions.

01©

PALAEONTOLOGY OF NEW YORK.

The casts of the dorsal valve present all the varieties from moderately
convex to extremely gibbous. In the younger and less convex forms, there
is usually a median depression more or less conspicuous ; the muscular area
is not sharply defined, but is distinctly bilobed, the upper parts deeply
striated, and a slender ridge in the bottom of the depression. In older
shells the muscular area becomes strongly defined and extremely prominent,
rising conspicuously above the general gibbosity of the upper parts • of the
cast. The cast of the rostral cavity is neatly defined and limited on either
side by the imprints of the crural bases, while outside of this are the char¬
acteristic crenulated impressions which mark this part of the hinge-line in
well preserved specimens of this and other forms of the genus.

This species has usually been regarded as a variety of the Atrypa reticularis ,
which is recognized as so widely distributed in several geological formations. It
may be difficult to decide what form shall be assumed as the typical Atryjpa reticu¬
laris , among those which occur in all the formations from the Clinton group to the
Chemung group inclusive. When compared with the so-called A. reticularis of
the Niagara group, the form is more robust, the ventral valve without sinus, and
the dorsal valve flattened or depressed in the middle of the lower half of its
length, while the striae are finer and less conspicuous. The same is true when
compared with the A. reticularis from the Lower Helderberg group, and also with
those of the Corniferous 'limestone and Hamilton group.

Geological formation and localities. This form of Atrypa occurs in the Scho¬
harie grit, at Schoharie, Knox, Clarksville, Coeymans and other places in New York.
It is not known to me in any other geological formation.

Atrypa reticularis.

PLATES 51-53 a.

Anomia reticularis : Linnjetjs, Syst. N&t. ed. xii, p. 1132. 1767.

Terebratula pectinatce, T. subtillissime striatce, T. cancellatce, T. minutissime striatce : Schroter, Abhan-
dlungen iiber verschiedene Gegenstande der Naturgeschichte. pi. iii. f. 11—18, and pi, iv., f. 16-26. 1777.
Terebratula pedinata : Bruguiere, Hist. Nat. Vers.; Testaces Encyc. Method, pa. 242, plate iv. 1789.
Anomites reticularis : Wahlenperg, Nov. Act, Soc. Upsal., Vol. viii, f. 65, 66. 1821.

Terebratula affinis : Sowerby, Min. Con., tab. 324, f. 2. Jan. 1822.

Spirifer sowerbyi : De France, Diet., Vol. ix, p. 295, t. Ixxvi, f. 2 (valva brachiis spiralibus omata) .
Terebratula {Magas) cancellata : Eichwald, Zool. i. 276, tab. iv, f. 11.

Terebratulites priscus : Schlotheim, Nachtragen zur Petrefactenkunde, p. xvii, f. 2. 1822.

ATRYPA OF THE UPPER HELDERBERG GROUP, &o.

317

Terebratulites explanatus : Schloth., Ibid. pi. xviii, f. 2.

Atrypa reticularis: Dalman Vet. Ac. Handl., pi. iv, f. 2. 1827.

“ 11 Hisinger, Lethe* Suecica, pi. xxi, f. 11.

Terebratula prisca : Von Buch, Ueber Terebratulen, p. 71. 1834.

Atrypa affinis : Sowerby in Murchison’s Silurian System, pi. vi, f. 5. 1839.

Delthyris prisca : Fahrenb. in Bull. Mosc., p. 788. 1844.

Terebratula (Atrypa) prisca : Phillips, Figures and Descriptions of the Palaeozoic Fossils of Cornwell.

Devon and West Somerset, pa. 81, pi. xxxiii, f. 144. 1841. •

Terebratula insperata : Phillips, Ibid, pa. 83, pi. xxxiii, f. 18. 1841.

Spirifer affinis : Sowerby, Trans. Geol. Soc. Lond. 2d series, Vol v, pi. Ivii, f. 11.

Terebratula prisca : d’Archiac et de Verneuil, Trans. Geol. Soc., Lond. 2d series, Vol. vi, p. 392.

“ ‘‘ A. Koemer, Die Versteinerungen des Harzgebirges, pi. v, f. 11-13. 1842.

“ reticularis : de Verneuil, Geol. of Russia and Ural Mts., Vol. ii, pi. x, f. 12. 1845.

Atrypa lentiformis : Vanuxem; A. affinis, and tribulis, Hall, Geology of the State of New York. 1843.
Hipparionyx consimilaris : \Vanuxem, Geol. Report of the Third District N. York, p. 132, f. 2. 1843.
Terebratula reticularis : Barrande, Ueber die Brach. Silur. Schichten von Boehmen, pi. xix, f. 8. 1847.

c' “ Bronn, Index Palseontologicus, p. 1248. 1848.

Spirigerina reticularis: d’Orbigny, Prodrome, Vol. i, p. 99. 1849.

Terebratula prisca : Quenstedt, Handbuch der Petrefactenkunde, p. 461, t. xxxvii, f. 1-4. 1851.

Atrypa reticularis : Davidson, British Fossil Brachopoda, Introduction, Vol. i, pi. vii, f. 87-93. 1853.

? Terebratula squamifera pars : Schnur, Dunker und Von Meyer’s Palaeontographica, Vol. iii, p. 181, f. 4,

“ insquamosa : Ibid, Vol. iii, p. 182, f. 5. 1853.

“ zonata [?] Ibid, Vol. iii. p. 182. 1853.

Atrypa reticularis : Morris, Catalogue of British Fossils, p. 132. 1854.

Anomia “ Sharpe, in Hanley’s “ Ipsa Linnaea Conchylia,” p. 127. 1855.

Spirigerina “ M'Coy, British Palaeozoic Fossils, p. 379. 1852.

“ “ Sandberger, Die Brach. des Rhein. Schichten. in Nassau, pa. 51, pi. xxxiii, f.l. 1851.

Atrypa “ Woodward, Manuel of the Mollusca, p. 228, f. 144, 145; and plate xv, f. 21. 1856.

“ Hall, Report on the Geological Survey of Iowa, pi. vi, pp. 4, 5. 1858.

• “ Hall, Nat. Hist, of New York, Palaeontology, Vol. iii, p. 253, pi. xlii, f. 1. 1862.

“ “ Davidson, Monograph of British Devonian Brachiopoda, part vi, p. 53. 1864.

I have heretofore referred to Atrypa reticularis a species of this genus in
the Niagara and Lower Helderberg groups, which is allied to, or identical
with one of those occurring in the Upper Helderberg and Hamilton groups.

There is, nevertheless, a character of individuality about the forms from
each of the geological periods, which serves to distinguish them from each,
other ; and whether this difference shall be recognized as specific or varietal,
is perhaps of little consequence at the present time. Taking our collections
from the geographical area of New York, we can readily recognize the
specimens from each of the successive groups or formations ; and I am not

318

PALEONTOLOGY OF NEW YORK.

sure that with our present knowledge of their interior characters, it would
not be quite as satisfactory to consider them as distinct species.

We may take a line of section from the Lower Helderberg to the Upper
Helderberg limestones within the dis nee of two miles north and south,
and where the conditions of the sediments are nearly similar; and we find
that the Oriskany sandstone has no representative of the species. The
Schoharie grit presents the forpi of A. impressa — but this is distinct from
that of the Lower Helderberg limestone, and equally distinct from that of
the Upper Helderberg. We have, therefore, three forms which, in collec¬
tions of hundreds of individuals, do not graduate into each other.

It is true, that tracing the Upper Helderberg limestone five hundred miles
to the southwest, we find the form of Atrypa reticularis changing; but it
does not approximate to that of the Lower Helderberg limestone or of the
Schoharie grit, nor do any of these forms resemble the one in the Niagara
group.

Several European naturalists, and more recently Mr. Davidson among
them (the latter with doubt), have admitted as a distinct species Atrypa
desquamata of Sowerby. So far as can be inferred from figures of that spe¬
cies, it corresponds with the Atrypa ( Hipparionyx ) consimilaris of Vanuxem,
a form occurring in our Corniferous limestone, and which we have generally
regarded as a variety of Atrypa reticularis. At the same time, Mr. David¬
son places Atrypa aspera, a much more distinct form as I conceive, as a
variety of A. reticularis.

Without attempting to represent more than a small part of the varieties of form
observed in the higher formations, I have endeavored to give a fair expression to
those occurring in the Corniferous limestone (Upper Helderberg), Hamilton
and Chemung groups.

The specimens figs. 11-13, Plate LI, from the Corniferous limestone, illustrate the character of the
.ordinary form and size of this species as it occurs in New York and -Canada West. In these forms the
ventral valve is often without mesial sinus or depression, as shown in fig. 11, while it is conspicuous in
figure 13. _The specimens of this general character seldom reach a much larger size in New York than
those above referred to, while in the west we have specimens preserving the same general aspect and
character of striae, with a much more gibbous dorsal valve, and a deep narrow sinus in the ventral
valve. Closely allied to these forms is that represented in figs. 4-6 on plate 52, where the dorsal valve
is extremely gibbous, with the anterior portion elevated in the form of a distinct fold, while the ven-

ATRYPA OF THE UPPER HELDERBERG GROUP, &c.

319

tral valve is depressed in a broad deep sinus, which is flattened in the bottom and quite unlike the
preceding ones in form. This group, represented in figs. 11-13, Plate 51, and figs. 1-6 Plate 52, is
most nearly allied to Atrypa impressa of the Schoharie grit, but the specimens do not show the flatten¬
ing of the middle of the dorsal valve, nor do we know that they have the extremely thickened shell,
allowing such depth of the rostral cavity as shown in fig. 8 of Plate 51. This peculiar feature has not
been observed ip any other of the various forms of Atrypa obtained from our rocks.

In figs. 10 and 14-24, Plate 51, we have the representation of another group of Atrypas, differing in
some small degree from the preceding. In these the young are but moderately convex, broader in
form, with the striae coarser and more regularly bifurcating. So far as observed, they do not acquire
the gibbosity of the other forms, the older shells presenting a broad undefined depression of the ven¬
tral valve, as shown in fig. 22, but never acquiring the character of a deep or abrupt sinus.

These forms are known in NewYork as occurring in the higher beds of the Corniferous limestone
near William sville, in Erie county, and are characteristic of the hydraulic beds at Louisville, Ken¬
tucky, and Jeffersonville, Indiana.

Continuing the character and mode of development observed in the specimens as
represented in the figures referred to, we pass to the forms designated by Vanuxem
as A, consimilaru* (figs. 9-12, plate 52), where the front of the dorsal valve is
often much elevated and deeply sinuate ; the ventral valve has a broad mesial
depression, and the front produced. These are the representatives of the Euro¬
pean form A. desquamata.

The varieties of form in the ventral valve are shown in figures 8, 10, 11 and 12. Figure 9 is a profile
view of another individual, and figure 7 is a dorsal view of the same.

The interior of the ventral valve of this form is shown in figure 51.

In a specimen of smaller size than figures 8 and 10, and of similar proportions, we have the muscular
and vascular impressions as shown in figure 12. There is really a considerable difference between
the parts as shown in this specimen and in the cast of the ventral valve of A. impressa as illus¬
trated in figure 9, pi. 1; but there is no important difference between figures 11, 12, except in
the proportionally greater length of the muscular impression in, the latter.

The common forms of this species in the Hamilton group are illustrated on
Plate liii, figures 3-11.

In the young specimens the beak of the ventral valve is elevated and perforated at the extremity, and
separated from the umbo of the dorsal valve, the intermediate space being occupied by a deltidium
as shown in figures 3, 4. This feature disappears in older shells, and the perforate apex is closely
appressed to the umbo of the dorsal valve. The hinge-line is longer and more nearly straight
than in specimens from the Corniferous limestone. The dorsal valve does not acquire the extreme
gibbosity, and the striae have a finer aspect. The mesial sinus usually impresses only the front of
the shell, and is but moderately developed, consequently affecting only the front of the dorsal valve.

* Hipparionyx [ Atrypa ] consimilaris, Vanuxem, Report on the Third Geological District of New York,
p. 1E2, f. 2. 1843.

320

PALAEONTOLOGY OF NEW YORK.

Figures 5-7 illustrate the more symmetrical forms of ordinary size.

The interior of the ventral valve shows a large flabelliform muscular area, which is rounded in front
and curving to the rostral cavity. Neither in the specimens from this group, nor in those from
the limestones below, have I observed any thickening of the parts adjacent to the muscular area,
nor any false area, as in those of the Lower Helderberg group. The rostral cavity is usually large
and the shell thin ; the truncation at the apex is often broad, as if for the protrusion of a strong
pedicel. This latter feature may be due to accident ; but in separated ventral valves it contrasts
strongly with the usual thickening of the parts about the rostral cavity, as observed in the same
valves of the Lower Helderberg forms.

In the dorsal valve, as shown in figure 9, we have a well defined muscular area, divided longitudinally
by a low septum which becomes thickened in its upper part. The hinge-plate is divided, and pre¬
sents on each inner margin a tooth-like plate, between which and the crural bases there is a distinct
groove. The crura originate close to the apex of the shell and diverge abruptly ; the dental sock¬
ets are deep in the lower part, and gently curving and narrowing towards , the apex. Outside of
the socket, and extending along the margin of the shell, is a crenulate callosity, separated from
the edge of the shell by a narrow groove.

These features are more fully shown in the enlarged figure 7, of A. impressa, and
the same, together with the junction of the loop and crura, are shown in the
accompanying enlarged figure of A. reticularis of the Hamilton group.

Atrtpa RETICULARIS.

Interior of the upper part of the dorsal valve, showing the bases of the crura and connecting loop.

Figures 22 and 23 of Plate 53 a, show the relation of the spires ; figure 22 represent these appendages
lying in the dorsal valve, and connected at their bases by the loop.

In figure 23 we have the ventral valve mainly removed, showing the dorsal side of the loop and the
apices of the spires which are in contact. Each cone presents about twenty-two turns of the spi¬
ral band.

In beds referred to the age of the Hamilton group at Independence, Iowa, this species, figs. 14, 15,
Plate 53, acquires a large size and presents some peculiarities, particularly in the straight extended
hinge and the suhcarinate dorsal valve. These features have not been observed in specimens from
the Hamilton group of New York, though simulated by some specimens of the Chemung group

ATRYPA OF THE UPPER HELDERBERG GROUP, &c.

S21

as in fig. 19 of Plafe 53. The specimen fig. 16, is a ventral valve of a large individual, from beds
at W averly, Iowa, equivalent to those at Independence. It is less extended on the hinge-line,
and has been broken so as to show the spires.

Figs; 12 and 13 of Plate 53, are from Lime Creek, near Rockford, Iowa, in beds which are probably
of the age of the Chemung group. The specimens are gibbous and finely striated, with strong
lamellose lines, and much resemble similar forms from the Chemung group of New York.

This form of Atrypa becomes a little more robust in the Chemung group, as
compared with those of the Hamilton group of New York, but retains generally
the same essential characters. Figure 17 is a dorsal view of a specimen from
that formation, and figure 18 is the imprint of the ventral valve in shaly sand¬
stone, a common condition of the species in these rocks. Figure 19 is a broader
and more finely striate form with straighter hinge-line.

Geological formations and localities . — In the formations under consideration,
this species occurs in the Corniferous limestone of New York, Canada West, Ohio,
Kentucky, Indiana and Illinois. It is found in the Hamilton group of New York
and Canada West ; and under an aspect similar to A. zonata of Schnur, in the
Hamilton group of Iowa and Illinois. It occurs in the Chemung group of New
York, more especially in the eastern or eastern-central portions of the State, and
also in rocks of the same age in Iowa.

Its localities are so numerous that it is scarcely necessary to name them in detail.
It is found in nearly every exposure of the Corniferous limestone from Albany county
to Black Rock, on the Niagara river. I have received specimens from Mr. Joseph
Sulliyant, from Columbus; from Dr. Mann and other sources, collected at Milford,
Ohio ; from the Falls of the Ohio, by Mr. S. S. Lyon; and very fine specimens from
Dr. James S. Knapp, of Louisville. Specimens from Iowa, have been received from
Mr. O. H. St. John, besides collections by Mr. Whitfield, myself and others ; I
have likewise obtained it at the Bake-oven in Illinois, where the Corniferous lime¬
stone is intimately connected with calcareous beds of the Hamilton group.

In the Hamilton group of New York, it is not abundant in the arenaceous shales
of the eastern counties, but is common on Cayuga, Seneca and Canandaigua lakes;
in several localities in the Genesee valley, and at Darien, Eighteen-mile creek,
Hamburg, &c., on Lake Erie shore. It is less common in the Hamilton shales of
West Williams, Bosanquet and Widder, in Canada West. It occurs at Rock Island
in Illinois, at New Buffalo, Independence, and other places in Iowa.

In the Chemung group it occurs on Cayuta creek, Ithaca, Elmira, Painted-post,
Bath, etc., but is rare or unknown in the more western localities of that formation
within the State of New York.

[Paleontology IV.] 41

322

PALAEONTOLOGY OF NEW YORK.

Atrypa spinosa, vel. A. aspera.

PLATE LIII A.

Atrypa spinosa : Hall, Report on Fourth Geological District of Hew York, p. 200, f. 1 and 2.

Atrypa dumosa : Id. Ib. p. 271, f. 1.

Compare Terehratulites aspera: Schlothem (Leonhard’s Taschenbuch, pa. 74, tab. 1, f. 7: 1813 ) ; Nach-
ti-agen Petrefaktenkunde, part 1, p. 363 (95) j part ii, 68, tab. 18, f. 3. Also T. explanata, idem.

'• Atrypa aspera: Dalman, Uppst. och Beskrif af de i Sverige funne Terebrat., Kongl. Vetens. Acad.

Handlingar, 1827 : pa. 128, tab. iv, fig. 3.

“ Terebratula aspera : De France, Diet, liii, p. 164. 1828.

'• T. reticularis .- Bronn in part, Ind. Palseontologicus, p. 1249. 1848.

“ Atrypa squamosa : Sowerbt, Trans. Geol. Soc. Lond., 2d series, Yol. v, pi. Ivii, f. 1.

“ Terebratula (Atrypa) aspera: Phillips, Pal. Fossils of Cornwall, Devon and West Somerset, p. 81,

pi. xxxiii f. 114. 1841,

“ Spirigerina reticularis, var. aspera: M'Cot, British Pal. 'Fossils, p. 379.

“ Atrypa reticularis, var. aspera : Davidson, Monograph of British Devonian Brachiopoda, part vi,

pa. 57, pi. x, f. 5-8.

Shell robust, suborbicular or oviod ; width greater or less than the length ;
radiatingly costate and concentrically lamellose or spinose ; hinge-line
often nearly straight, a little less than the width of the shell.

Ventral valve depressed-convex, becoming more convex in the upper part;
nearly flat and often a little concave towards the lateral margins, and
cardinal extremities depressed or broadly sinuate in front : beak abruptly
rounded ; apex truncate and perforate, closely appressed and overlapping
the umbo of the opposite valve.

Dorsal valve convex, becoming gibbous in old shells, flattened or slightly
concave towards the cardinal angles, regularly curving to the sides and
baso-lateral margins, and a little elevated in front, but without any dis¬
tinct mesial fold.

Surface marked by strong rounded radiating costse bifurcating at unequal
intervals, which are much stronger in the middle of the valve, and beeme
obsolete or appear as gentle undulations towards the cardinal angles. In
the middle of the valves there are about seven or eight of these costs©
in the space of half an inch. The shell is also marked by strong concen¬
tric lamellae, which are often about a line apart. In perfect shells these
lamellae, at the crossings of the costse, are often produced into tubular

ATRYPA OF THE HAMILTON GROUP, &c.

S3S

spines, which, when worn off, leave the ordinary lamellose surface. The
spaces between these projecting lamellae are marked by fine thread-like
striae.

In the separated valves, the hinge-line is often nearly straight, the mus¬
cular area of the ventral valve is short and broad, the length from the apex
being about equal to the width. There is a slight thickening of the shell
at the base of the rostral cavity. The surface around the muscular area is
papillose, and limited by a thickened border, except in front, where
it is discontinued. Fine vascular markings are sometimes visible near the
margin. In the dorsal valve there is a thickened septum in the upper part
of the muscular area.

The spires of full grown individuals about fifteen turns in each.

In casts of this species from the Hamilton group of Maryland and Vir¬
ginia, we find the same characteristic features preserved as above described.

I have adopted the name Atrypa spinosa , although I think this may be identi¬
cal with the species known as Atrypa asptra or Atrypa reticularis , var. aspera, of
European authors ; but I wish to preserve for our shell a specific designation.
Prof. M‘Coy, Mr. Davidson and other European authors adopt the opinion that
the variety A. aspera passes “ by insensible gradations” into well-marked A.
reticularis. I must insist, however, on a different status for our shell. Passing by
the specimens from the Corniferous limestone, where the shells are exfoliated and
changed by silicification (rendering discrimination not always so easy), we have
only to examine large collections from the Hamilton group to discover a constant
and well-marked distinction. I have collected and examined many hundreds of
specimens of Atrypa reticularis , from various localities of the Hamilton shales in
New York, and a smaller number of Atrypa spinosa. The former is much the
more abundant, and occurs in locality where the latter is not found, though fre¬
quently both occur in the same localities, and never for one moment will the
collector hesitate as to their distinct specific distinction.

The full-grown shells of A. spinosa are proportionally broader and more robust,
and from about twelve to twenty-five or twenty-six ribs may be counted on the
Surface of each valve, according to the size of the shell and the degree of devel¬
opment towards the margin. In specimens,of A. reticularis of similar size, more
than twice as many costse can be counted, while they do not become obsolete on the

324

PALEONTOLOGY OF NEW YORK.

cardinal extremities as in the other species. In A. spinosci the beak of the ventral
valve is shorter, the hinge-line longer and more nearly straight, the muscular area
proportionally shorter, and the adductor imprint comes down lower and is not so
clearly pointed. There are also some slight differences in the interior of the dor.
sal valve ; but the specimens examined have been too few and imperfect to render
the result satisfactory.

In the character of the internal spires the distinction is quite palpable : the
junction of the crura with the valve differs in a small degree, as does the loop and
its connection with the crura ; while we have about fifteen turns of the spire
where there are twenty-two in A. reticularis of the same size. The connecting
loop does not descend so deeply into the cavity of the valve ; and in its junction
with the crura, as well as the form of the latter, it differs from A. reticularis.

In pursuing investigations to the westward, the contrast between this species
and A. reticularis , or its representative, continues to be equally or even more
strongly marked. In specimens from Iowa, the ribs of A. spinosa or aspera are
stronger and coarser than in specimens from New York ; while the form referred
to A. reticularis has finer striae and appfoaches the A. zonata of Schnur (loc. cit).
In collections from the Hamilton group near Cumberland (Md.) and the adjacent
parts of Virginia, there are many casts and exfoliated shells of A. spinosa , but
none of them with'the finer costae, or that can be referred to A. reticularis. Although
in these species from different localities there is a palpable variation in the number
and character of the costae, the distinction between the two remains as strongly
marked as at first indicated.

In the hydraulic limestone beds, which lie mainly above the coral-bearing beds
at the Falls of the Ohio; at Columbus and other localities in the State of Ohio, as
well as in Western New York, there is a form of Atrypa which may be considered
as intermediate to the A. reticularis and A. spinosa or A. aspera. This form is
proportionally broader, less gibbous and more strongly plicated than those which
we usually refer to A. reticularis — but we do not, in any locality, so far as I know,
find these varieties graduating into each other.* These are illustrated on Plate
51, figures 10-24.

# I am not by any means satisfied that this variety may not prove a distinct species, or it may cor¬
respond with some of the forms termed Atrypa aspera or A. prisca of Europe. f It will he observed,
in the illustrations on Plate li, that the form is somewhat different, the ventral valve more expanded,

f The form here referred to resembles two large expanded specimens from Refrath in Germany, re¬
ceived under the name of Atrypa prisca.

ATRYPA OP THE CHEMUNG GROUP

325

Figures 1-7, are from the Upper Helderberg limestone.

Figures 8-14, present the ordinary forms and phases of the species in the Hamilton group; figures 8
and 9, retain the spines, and the others have them removed.

Figure 14, is of the interior of a 'well marked ventral valve.

Figure 18, presents the ordinary phase of this species in the Chemung group. There are sometimes
remains of short spines, as shown in the accompanying woodcut.

Figures 24 and 25, show the spiral cones of the interior viewed from the dorsal and ventral side re¬
spectively.

Geological formations, and localities. — This species occurs in the Corniferous
limestone, in nearly all the localities cited for A. reticularis. In the Hamilton
group, its principal localities are Moscow and York in Livingston county, Darien
in Genesee county, Hamburgh and Eighteen-mile creek in Erie county ; likewise
on the shores of Seneca and Cayuga lakes, and eastward of these points. It occurs
in the s.ame formation in Maryland and Virginia, in Canada West, and in Iowa
and Illinois. In the Tully limestone, it is found at Tinker’s falls, Onondaga coun¬
ty, New York. In the Chemung group, it occurs in considerable numbers on Ca-
yuta creek at Factoryville ; at Chemung, Chemung creek and Chemung-narrows,
and at Bath and vicinity ; also at Elmira and northward of that place. It becomes
rare or altogether unknown in the southwestern counties of this State.

and the costae coarser than in the Hamilton and Chemung specimens of A. reticularis ; but these dis¬
tinctions cannot be fully illustrated till we know more intimately the structure, and character of all its
parts. While these pages are going through the press, I have examined more than a hundred speci¬
mens of this form and of the finely costate species, and find no difficulty in separating them one from
the other though there are remarkable variations in individuals. In making the comparisons and
references to Atrypa reticularis, I have adopted that name for the more finely costate forms, but I am
compelled to express some doubt whether we fully understand the original of that species. After much
careful study of the interiors of several genera of Brachiopoda, including Atrypa, I still hesitate to
accept the general opinion regarding a species which is so well known, and is found abundantly in all
the formations from the Devonian to nearly the bottom of the Silurian system, and which has received
the following appellations :

Anomites reticularis, Wahlenberg, Nov. Act. Soc. Upsal, Vol. viii, p. 65.

Terebratulites priscus, Schlotheim, Petrefact., PI. lxxxvii, f. 9.

Ter ebr alula affinis, Sowerby, Min. Conch. PI. cccxxiv, f. 2, etc., etc.

If this, in all its phases, be a single species, there are many of the species designated under other
genera of Brachiopoda, which have no better claim to specific value, subject to the same rule.

3‘2<3

PALAEONTOLOGY OF NEW YORK.

Atrypa hystrix.

PLATE LIII A.

Atrypa hystrix : Hall, Report of Fourth Geological District, p. 272, f. 2; p. 271. 1843.

Shell suboval, ovate or subcircular, usually flattened: surface acutely
costate.

The shells of this species are too imperfect and obscure to admit of
detailed description. The valves are usually much flattened, and the im¬
prints are left in shaly sandstone or shale from which the shell has been
removed. The surface is marked by a few distant angular or subangular
ribs, which are sometimes bifurcated, and are crossed by strong lamellose
striae. In the perfect shell, long spines proceed from the lamellae at the
crossing of the ribs-; and when the shell is exfoliated, the ribs are nodose
from the spine-bases.

The collections furnish a single gibbous specimen of the dorsal valve, one
inch and a quarter long by about an inch and a half wide, with a depth
of about three-fourths of an inch, and other specimens of smaller size.

The young specimens of A. spinosa approach this form, as shown in figure 8 of
Plate liii a, and it is possible that this may be an extreme variety of that species.
The specimens, figures 16 and 17, occur in localities where forms like figure 18 are found, hut there
are no palpable gradations ; and among a hundred individuals like figure 18, and figure 1 of
page 325, there is no deviation which can he regarded as an approach to figures 16 and 17.
Geological formation and localities. This species is known only in the middle
and higher part of the Chemung group, and has been principally found to the
south and southwest of Bath in Steuben county.

*** From collections recently made in Iowa, we learn that in all localities the
distinction between Atrypa reticularis and the associated species is more strongly
marked than in the collections from New York, and there is nowhere any indica¬
tion of gradation from the one to the other. In the higher beds of the series in
Northern Central Iowa, which may be of the age of the Portage or Chemung
formation of New York, the species identified with A. reticularis is more finely
costate, while the other form approaches more nearly to the A. hystrix of our rocks
having a few coarse plications with spines ; these appendages, however, are
rarely preserved.

ATRYPA OP THE UPPER HELDERBERG GROUP, &c.

Atrypa psemloniarginalis.

PLATE LIII.

Atrypa pseudomarginalis : Hall, Thirteenth Report on the State Cabinet, p. 84. 1860.

Shell trilobate, wider than long; surface plicated.

Ventral valve depressed-convex, gently curving to the sides; mesial sinus
deeply depressed in the lower part, and extending for more than two-
thirds the length of the shell ; beak extending beyond that of the dorsal
valve and moderately incurved.

Dorsal valve regularly convex above, curving somewhat abruptly to the
sides ; the mesial fold becoming conspicuous at about one-third the length
from the beak and rising into a prominent rounded lobe, which occupies
more than one-third the width of the shell in front.

Surface marked by numerous rounded bifurcating plications.

This species resembles Atrypa marginalis of Dalman, but is larger and more
robust than the specimens of that species which I have seen : the beak is less
attenuate, the mesial fold and sinus broader and not extending to the beak, and
the striae coarser and not so much recurved. From the Bohemian specimens under
the same name, it differs in the greater elevation and rounded form of the mesial
lobe, and the less angular plications. It has proved extremely rare in the rocks
of New York.

Geological formation and locality. In the Upper Helderberg limestone at Scho¬
harie, New York.

328

PALEONTOLOGY OF NEW YORK.

Genus C<elospira (Hall).

The species published under the name of Leptoccdia concatia in the third
volume of the Palaeontology of New York, page 245, was subsequently
found to possess internal spires, arranged in a somewhat peculiar manner,
and connected by a strong loop. This feature rendered it necessary to
remove the fossil from the association in which I had placed it, with Lepto-
coilia imbricata and L. flabellites, and I have proposed for it the generic name
Ccelospira.*

This genus differs but little from Zygospira proposed by me in 1862, f and
it may be found desirable to unite the two under that designation, extending
the characters so as to include the types of both the genera ; but this can
only be done after the discovery and examination of other species which
may serve to unite the forms already described.

The shells of Ccelospira are concavo-convex, having the ventral valve
convex or sometimes subangularly arching over the concave dorsal valve.
The surface of the shell is striated or plicated, with the plications simple
or bifurcating, and of which two or more in the centre of the ventral valve
are more conspicuous than the others, forming a more or less defined mesial
fold ; upon the dorsal valve there is a corresponding depression. The
space between the valves leaves little room for the spires, and these append¬
ages appear to be somewhat loosely arranged, with their apices approaching
each other. These shells are apparently fibrous in texture ; and on this
account, and from the position of the spires, they approach more nearly to
Atrypa than to Trematospira, to the latter of which they are more nearly
allied in external form.

The Terebratula barrandi of the Wenlock limestone of England belongs appa¬
rently to the genus, being closely allied to C. disparilis (= Atrypa disparilis) of
the Niagara group (Palaeontology of New York, Yol. ii, p. 277), holding likewise
a similar geological position.

* Sixteenth Report on the State Cabinet, p. 60. 1863.
f Fifteenth Report on the State Cabinet, p. 154. 1862.

CCELOSPIRA OF THE CORNIFEROUS LIMESTONE.

32e>

Coelospira concava,

PLATE LIII.

Leptoca.Ua concava Hall, Pal. New-York, Yol. iii, pa. 245, pi. xxxviii, figs. 1-7. 1861.

Calospira concava : Hall, Sixteenth Report on the State Cabinet, p. 60, with figure. 1863.

The specimens from the Upper Helderberg limestone at Caledonia,
New- York, and those from the upper portion of the Lower Helderberg
group, in Oneida and Herkimer counties, do not show any differences of
specific importance, and I am therefore constrained to regard this species
as passing upwards from the Lower Helderberg formation ; unless indeed
we may infer that some of the sediments of that epoch may have exten¬
ded farther to the westward and this species have there existed, while
the superincumbent formations of limestone, in the absence of the Oris-
kany sandstone, have directly succeeded the older beds in such a manner
as to have become incorporated with them, or to have left no line of
demarcation.

A single specimen from Stafford in Genesee county is considerably
larger than any of those from other localities of the Corniferous lime¬
stone or of the Lower Helderberg group, while the sinus of the dorsal
valve is narrower and less depressed. The material at present possessed
is insufficient to characterize it as a distinct species.

Geological formation and localities. In the Corniferous limestone at Caledonia
and other places in Western New- York, and also in the same formation in Canada
West.

[ Paleontology IV.]

42

330 PALAEONTOLOGY OF NEW-YORK.

The accompanying figures illustrate the interior of Ccelospiea and Zygospira :

The Genus Uncites, which is characteristic of the European Devonian system,
has not occurred among the collections made in the State of New-York, and so
far as I know is not found in this country. Of the six genera of SpiriferidaE
enumerated in the preceding pages, which do not occur in Mr. Davidson’s list,
five of them are likewise known in the Silurian formations of this countiy. The
Genus Merista, which is cited as occurring in the Devonian of Europe, is not
known in our strata of the same age : and it is possible that the European forms
of that geological period may present the same modifications as with us, and fall
under the Genus Meeistella. Although not recognizing the Genus Retzia, which
in Europe is characteristic of the Silurian and Devonian stages, we have in Trema-
tospira and Rhynciiospira two allied genera. The other genera of this family
enumerated in Mr. Davidson’s list are characteristic of more modern formations
than those from which species are here described.

* The disposition of the spirals in C<et.ospira is not very dissimilar from the same appendages in
Roninckia, a Triassic genus of Brachiopoda.

FAMILY RHYNCHONELLIDJJ.

331

FAMILY RHYiYCIIOYELLIDJE.

The Rhynchonellid,® are distinguished from the Spiriferida: mainly
by the absence of calcareous spires; though Mr. Woodward includes
Atrypa in this family, remarking that the teeth and impressions are like
Rhynchonella, and that “ the shells of this genus differ from Rhyncho-
“ nell a chiefly in the calcification of the oral supports, a character of
“ uncertain value.” Mr. Davidson and other authors have placed Atrypa
in the family Spiriferid,®, and I see no reason for changing this disposi¬
tion of the genus. The spires are in all respects similar to those of Spi-
rifera, the direction of their apices into the dorsal valve being simply a
feature of position. The muscular imprints are as much like those of
Spirifera as they are like Rhynchonella.

Leaving out the Genus Atrypa, the Family Rhynchonellid^e will include
no genus with calcareous spires ; but from analogy with modern Rhyn¬
chonella, they are supposed to have possessed fleshy spiral arms which
have not been preserved in the fossil state. This family, in its usually
accepted limitations, will include Rhynchonella (as at present under¬
stood), Stenoctsma, Leiorhynchus, Camarophoria, Pentamerus, and
Stricklandinia ; though I think there would be great propriety in
uniting the two latter genera with some others in a separate group.

33^

PALEONTOLOGY OF NEW-YORK.

GENTS KiIYNCHONELLA (Fischer, 1809).

The species Rhynchonella loxia is made .the type of this genus by its
author. It is only within a recent period that the name has been so
extensively applied to nearly all the ovoid or subtrigonal plicated, and
some smooth shells of all geological epochs, from Lower Silurian to the
most recent formations, and it has been recognized in two existing species.

In the Introduction to the Study of the Brachiopoda (page 95 of the
English edition, page 117 of the French edition), Mr. Davidson remarks :
“ The Genus Rhynchonella is one of the oldest types of animal life,
“ having been repeated from the Silurian epoch up to the present period :
“ two species are still found alive.”

I have heretofore accepted the general views of palaeontologists
regarding this genus, and have described a number of species under it ;
but I have long been satisfied that in making such extensive application
of the term Rhynchonella, we were in danger of falling into an error of
scarcely less magnitude than that of referring all similar forms, with
many others, to the Genus Terebratula.

Unfortunately the internal characters of R. loxia do not seem to be
known : at least I have not seen them illustrated ; and though cited as
the type by Mr. Davidson, and figured upon the plate, it is not enume¬
rated in his list of eighteen examples. Mr. Woodward gives as types
R. acuta, furcellata, spinosa, acuminata , nigrescens and psittacea ; species
enumerated in Mr. Davidson’s list, but he does not cite R. loxia.

With the interior structure of the type of the genus unknown, while
the parts are illustrated from recent species, or from fossil ones supposed
to belong to the genus, we are not likely to make satisfactory progress
in the arrangement of the fossils usually referred to it. A careful study
of those fossils which have been cited as examples of genera, passing-
through all the geological stages and still existing, has proved, in some of
them at least, that the assumption was not well founded ; and I think

GENUS RHYNCHONELLA.

333

we should hold such views with reservation. In the present instance, I
must be allowed to doubt whether R. loxia will be found to possess the
characters of Lower Silurian and of existing Rhynchonella: ; nor do I
consider the characters of the existing species as congeneric with those
of the older Silurian or Devonian formations. The necessity felt for some
other designation to apply to some of these forms has induced the names
Hypothyris, Hemithyris, Cyclothyris, etc. ; but these do not appear to have
been founded on reliable structural characters. That some subdivision
will become necessary, and will be adopted, I have no doubt; but- such a
desirable end can only be consummated after the study of the interiors
of numerous specimens, with large collections for comparison.*

Although having adopted the name Rhynchonella for our Devonian species, I
have lately observed characters which appear to me to separate them so widely
from the recent species of the genus, that I am compelled to substitute some other
designation.

Among genera of the same family, we must necessarily make distinctions upon
the modifications of certain parts which they may all possess in common • and
the importance of these modifications of interior parts or appendages should not
be overlooked. Not only do the recent and fossil forms referred to Rhynchonella
possess great similarity in the ventral valve, teeth and dental plates, but they are
not very dissimilar from the same parts in genera of the Spiriferida. It is in the
dorsal valve and its appendages that we find characters the most important and relia¬
ble for generic distinction ; and it is only necessary to follow these in the genera
of the Terebratulida and Sfiriferida, to recall the most curious and interesting
modification of the parts which this valve supports. I am therefore inclined to
regard these modifications of generic importance.

Ip many of the fossil species referred to Rhynchonella, one of the most con¬
spicuous features in the dorsal valve is the strong septum, which becomes broader
and often shows indications of division at the apex, or at least evidence of a
small and shallow V-shaped pit.

* The reliance upon external forms for the determination of generic affinities or differences, although
a compulsory condition in many instances, is far from satisfactory. As an example of this kind, I may
remark that having recently occasion to compare Terebratula sappho, Barrande, with Rhynchonella
sappho, Hall, the former presented so much of a rliynchonelloid aspect as to suggest the propriety of
regarding the latter as a synonym. A careful examination of the Bohemian species, from cutting down
the solid fossil, has revealed the fact that it is furnished with calcareous spires arranged as in Atrypa >
the spires directed into the cavity of the dorsal valve, and the crura connected by a loop in a similar

manner.

334

PALAEONTOLOGY OF NEW-YORK-:

The recent species of Rhynchonella do not certainly furnish any evidence of
similar characters, so far as I have been able to examine specimens or illustrations.
The dental plates of the ventral valve are not, it is true, essentially different in
fossil and recent Rhynchonella ; but the same comparison may be made with
other genera even out of the Family Rhynchonellid.®.

With these facts before us, I propose to revive the name Stenocisma* of Con¬
rad for the species under consideration, extending the term to include the typical
species Rhynchonella formosa of the Lower Heidelberg group. This genus may
be characterized as follows :

*In his second Annual Report (page 59, 1839), Mr. Conrad, speaking of the rocks of New-York,
says : “The Genus Terebratula is wholly unknown, and the shells usually referred to that genus
“ I propose to group under the generic name of Stenocisma, derived from two Greek words signi-
“ fying narrow fissure, a character these shells possess under the imperforate apex of the larger
“ valve, and which serves to connect the genus with Delthyris, from which it differs in having no
“ cardinal area. This last-named character, on the other hand, connects it with the Genus Strygoce-
“ phalus. I refer to it the common Silurian bivalve, Terebratula schlotheimii, Yon Buch.”

Notwithstanding the assertion of imperforate apex, we have learned that many of these forms, and
probably all those which have been referred to Terebratula, have had at some period of their
growth a perforate apex. It was also a Lower Helderberg species ( Rhynchonella formosa) which was
referred by Mr. Conrad to “ the common Silurian bivalve T. schlotheimii.” I have in my possession
a lithographed plate of the fossils of the Lower Helderberg group by Sir. Conrad, with the names, in
his own hand, written beneath the figures; the species I have since designated as R. formosa having
there been identified with Terebratula schlotheimii.

Although the generic characters were not fully described, and with imperfect reference to species, I
think it preferable to adopt this name instead of introducing a new one.

The name Hemithyris, applied by some authors to certain rhynchonelloid forms, has been used to
include very heterogeneous materials ; and without citing a long list to prove this, I may mention
H. angustifrons, M'Coy, H. subundata, M‘Coy ; H. hemispherica, var. scotica, M'Coy ; all figured on
the same plate, and belonging to three distinct genera ; the first named being undoubtedly a Meris-
tella, and having internal spires. This generic term, therefore, cannot he adopted unless redefined
and very much restricted in its application.

GENUS RHYNCHONELLA — STENOCISMA.

3913

Genus or Subgenus Stenocisma (Conrad— Hall).

Shells subtriangular, ovoid or subglobose; hinge-line short : beak of
ventral valve extended, attenuate or more or less arcuate and appres-
sed against the opposite valve. A mesial sinus and fold on the ventral
and dorsal valves respectively. Surface plicated with simple or rarely
bifurcating plications.

The valves are articulated by teeth and sockets. A strong median sep¬
tum in the dorsal valve of many of the species, which becomes thick¬
ened in its upper part, with a shallow triangular pit in the centre, and
the crura supported on each side : dental sockets crenulate. The'teeth are
strong, with lamellae extending to the bottom of the valve, limiting the
rostral cavity, and sometimes partially surrounding the muscular area.

In casts of the ventral valve, the cavities made by the diverging
lamellae are very distinct; and in the dorsal valve, the place of the sep¬
tum is strongly marked, the space being wide above, and within this
cavity at the upper part there is a small angular elevation of greater or
less extent, which originally filled a depression in the upper part of the
septum.

I would by no means include all the palaeozoic so-called Rhynchonellae under this
genus, for I am satisfied that there are plicated shells of similar form which have
a different internal structure ; but it is absolutely necessary that this structure be
known, before we can make a proper disposition of the species.

Rliynclionella ( Stenocisma ) tetliys.

PLATE LIY.

? Rhynchonella tdhys : Billings, Canadian Journal, p. 270. 1860.

Shell subtrigonal ovate, usually wider than long, sometimes length and
width equal.

Ventral valve depressed convex in the upper part, nearly flat at the
sides : mesial sinus beginning above the middle, moderately depressed
in young shells, and in older ones becoming deep in front and abruptly
curving towards the dorsal valve.

336

PALAEONTOLOGY OF NEW- YOLK.

Dorsal valve moderately convex in young shells, more convex and finally
gibbous in old shells : the broad mesial elevation becoming distinct
about the middle of the length.

Surface marked by from fifteen to eighteen angular plications of which
five or six are upon the mesial fold and sinus, and about an equal
number, or sometimes six or seven, on each side : the plications on
the dorsal valve near their extremities curve very abruptly to the
ventral valve. Fine concentric striae, which are undulated in crossing
the plications, mark the surface of the shell ; but this feature is rarely
preserved. (

Some specimens from the Corniferous limestone of Western New- York -appear
to be of this species, but they are smaller than the figures of Mr. Billings. A
single large specimen from Port Colborne, Canada West, has five plications in
the sinus and six on the fold, with seven on each side.

I have received from Dr. Knapp of Louisville several fine specimens from the
limestone of the Falls of the Ohio, which I have referred to this species : one of
these has a length of eleven-sixteenths of an inch, with a width of nearly twelve-
sixteenths and a depth of half an inch. In another, the length, width and depth
are as 8, 10 and 5 respectively. A young individual has three plications in the
sinus and five on each side ; while a smaller one has but two plications in the
sinus. I have been inclined to believe that this is only a different condition of
iS. sappho of the Hamilton group.

Geological formation and localities. This species occurs in the Corniferous lime¬
stone, at Stafford, Genesee county, and Williamsville, Erie county, New-York ;
at the Falls of the Ohio ; at Port Colborne and elsewhere in Canada West.

Ithyiichoiiella ( Stenocisma ) hillings! ( n. s.).

PLATE LIY.

Rhynchonella thalia : Billings, Canadian Journal, p. 272. 1860.

Not R. thalia : D’Oebigny. 1847.

Shell small, ovoid subtrigonal, truncated in the middle of the front and
rounded on each side ; width greater than the length.

Ventral valve moderately convex ; mesial sinus beginning a little above
the middle of the length of the shell, and marked by “ three simple,
acutely angular ribs ” ; beak elevated and acute.

RHYNCHONELLIDiE OF THE CORNIFEROUS LIMESTONE. 337

Dorsal valve convex ; mesial fold beginning above the middle of the
valve, and becoming prominent towards the front.

Surface marked, by about seventeen or eighteen sharply angular plica¬
tions on each valve, of which three are in the sinus and four on the
mesial fold ; concentrically marked by fine abruptly undulating striae.
The specimens which I have examined and referred to this species are somewhat
smaller than those figured by Mr. Billings. I am not quite satisfied that the spe¬
cies is distinct from R. horsfordi of the Hamilton group ; but specimens of the
latter of the same size have a greater number of plications on the fold and sinus,
and the shell is larger. Should it prove a distinct species, the name thalia, being
preoccupied, must give way to another.

Geological formation and localities. In the Corniferous limestone of Western
New-York and Canada West.

Rliyiiclionella ( Stenocisma ) Carolina (n.s.).

PLATE LIV.

Shell ovate, moderately gibbous, a little produced in front and broadly
sinuate ; length and breadth about equal.

Ventral valve convex in the upper part, curving gently to the margins
and a little concave along the cardinal slope, sometimes nearly flat
below ; beak little incurved or nearly straight ; sinus beginning at
about one-third the length of the shell from the apex, very gradually
depressed and not abruptly incurved in front, making a broad shallow
sinus with curving sides, the limits of which are not strongly defined.
Dorsal valve moderately gibbous and regularly arcuate from summit to
base, the sides more abruptly curved ; mesial fold becoming defined
above the middle of the shell, its summit convex and the sides not
abruptly limited.

Surface marked by about twenty to twenty-five obtusely angular plica¬
tions ; those of the margins becoming obsolete and about four or five
depressed in the sinus, with a corresponding number on the dorsal fold,
which are stronger than the rest ; a single one on each side of the sinus

[Paleontology IV.]

43

338

PALAEONTOLOGY OE NEW-YORK.

and fold, partially depressed or elevated, and smaller than the others.
The shell has been marked by elevated thread-like concentric striae.

The specimens described are essentially casts, the shell being partially pre¬
served on one of them. The species differs from all the other rhynchonelloid forms
of the limestone, in the broad scarcely defined sinus, which is not abruptly eleva¬
ted in front ; and in the undefined margins of the fold, which are marked on the
slope by a less strongly raised plication. The beak is also more extended than in
the other species.

In casts of the ventral valve, there is no important distinction between this and
other forms in regard to the dental plates, etc. ; but I am induced to believe that
investigation upon more extensive material will prove the characters of the dorsal
valve to be so far distinct as to require generic separation.

Geological formation and localities. In the Corniferous limestone at Sandusky,
and near Columbus, Ohio.

Rliynchonella ? ( Stenocisma ? ) royana (n. s.).

PLATE LIY.

Shell ovate, compressed ; beaks nearly equal : valves almost equally
convex above ; the dorsal valve continuing in a pretty regular con¬
vexity, and the ventral valve depressed iu a broad undefined sinus.
The surface is marked by about twenty-four or more slender plications
on the margin, the three or four central ones on the dorsal valve bifur¬
cating once above the middle of the shell, and some of them again below
the middle : the same feature is more or less characteristic of the ven¬
tral side. The plications upon the sides of the shell are simple and
become obsolete on the cardinal slopes, which are marked only by con¬
centric striae. When perfect, the entire surface has been marked by fine
concentric striae.

The hinge-line presents obscure indications of. an area on the ventral valve,
and the species is unlike anything else known in the formation. It cannot be
referred with certainty to any known genus. It is extremely rare, and but a single
individual has been found.

Geological formation and locality. In the Corniferous limestone, north of Leroy,
New- York.

RHYNCHONELLIDJE OF THE HAMILTON GKOUP.

039

Rliyiichonclla (Stenocisma) horsfordi.

PLATE LIT.

Rhynchonella horsfordi : Hall, Thirteenth Report on the State Cabinet, p. 87. 1860.

Shell, in full-grown specimens, transversely subelliptical; rostral por¬
tion sometimes a little extended ; front nearly straight or broadly
rounded ; length and width about as five to six or seven. Young shells
ovoid subtrigonal.

Ventral valve moderately convex, flattened and incurved in front ; a
slightly depressed sinus, appearing about the middle of the length,
which is flat in the bottom and curving abruptly upwards in front :
beak moderately extended, abruptly acute and usually but little
incurved.

Dorsal valve very gibbous in old shells, sloping abruptly to the beak ;
depressed-convex in young shells. Mesial elevation defined below the
middle of the length.

Surface marked by about fifteen or sixteen to twenty-four well-defined
angular plications, of which four to six or seven mark the mesial sinus
and fold, which are deeply bifurcated in front. On the sides and
towards the cardino-lateral margins of the shell the plications are
less angular : concentrically marked by fine undulating striae, which
are seen towards the front, but rarely on other parts of the shell.

* The size varies from a quarter of an inch in length and five-sixteenths
in width to nine-sixteenths in length and thirteen-sixteenths of an inch
in width, according to age.

A specimen of half an inch in length from the limestone of the Falls
of the Ohio, sent to me by Dr. Knapp, which I refer to this species, presents
a strong interrupted line of growth above the middle’ and has about
twenty-eight plications visible, of which four mark the sinus and five
the mesial fold.

This species differs.. from the R. (/S'.) sajpjplio in the finer, more numerous and
more angular plications ; and is usually a much smaller shell. It can scarcely be
compared with any of the devonian forms of Great Britain, having only a remote

34©

PALAEONTOLOGY OP NEW-YORK.

resemblance to B. primipilaris or implexa. It is never abundant, and is often found
in a crushed and distorted condition.

Geological formations and localities. In the Hamilton group, at Moscow, York,
Geneseo and elsewhere in Western New- York; also in the Marcellus shale at
Avon and other places.

Rliynclionella (Stenocisma) sappho.

PLATE LIY.

Rhynchonella sappho : Hail, Thirteenth Report on the State Cabinet, p. 87. 1860.

Shell, in full-grown individuals, transverse, gibbous, subelliptical. Young
shells broadly subtrigonal, becoming short-ovate ; nearly straight in
the middle of the front, abruptly pointed at the beak : cardinal slopes
concave ; sides rounded to the mesial fold and sinus.

Ventral valve flabelliform, depressed-convex, rarely a little gibbous on
the umbo, flattened and depressed in the middle towards the front ;
the sinus becoming perceptible about the middle of the length : sides
nearly flat ; apex abruptly acute, and more or less incurved according
to age.

Dorsal valve gibbous, regularly arching transversely ; the mesial fold
becoming conspicuous only towards the front : in young shells only
moderately convex.

Surface marked by twenty to twenty-two or twenty-four plications
(fourteen or fifteen in the young shells), those towards the cardinal*
margin less elevated ; about four to six mark the sinus and fold. In
old shells, the plications are grooved towards the front ; and those of
the sides of the dorsal valve are very abruptly bent towards the ven¬
tral valve, with a shorter and wider groove, and all deeply bifid for the
reception of the opposite plication. The shell is concentrically marked
by fine thread-like elevated strise, which are more conspicuous and
strongly undulating towards the front of the shell, their remains being
often preserved in the casts.

Length and width, in full-grown shells, as seven to eight.

RHYNCHONELLIM OF THE HAMILTON GROUP.

341

This beautiful and symmetrical species differs from It. horsfordi in its more
robust character and stronger plications. It may be compared with the It. flexistria
= It. tumida of Phillips, a Devonian species of Europe.

Geological formation and localities. From calcareous layers in the Marcellus
shale near Leroy, Genesee county ; also in the Hamilton shales at Geneseo and
York, Livingston county ; and at Eighteen-mile creek in Erie county. A specimen
received from Rev. E. J. Bush was obtained in the vicinity of Hamilton in Madi¬
son county, New- York.

Rliynchonella ( Stenocisma ) congregata.

PLATE LIY.

Atrypa congregata : Conrad, Annual Report on the Palaeontology of New-York, p.65. 1841.

Shell robust, varying from short-ovate to subglobose ; length and width
nearly equal or a little wider than long ; front rounded or straight in
the middle ; apex pointed.

Ventral valve convex at the sides, depressed in the middle ; mesial
sinus often beginning at about one-third the length from the apex,
and becoming conspicuous towards the front : beak, in old shells,
closely arcuate over the apex of the opposite valve ; in young shells,
nearly straight or slightly incurved.

Dorsal valve gibbous in old shells, regularly convex in young specimens :
mesial fold scarcely conspicuous on the upper half of the shell, some¬
times prominent near the margin ; sides curving abruptly to the junc¬
tion with the opposite valve.

Surface ( in young shells ) marked by only nine or ten distinct subangu-
lar or rounded 'plications ; in older shells, by eighteen to twenty-two,
of which three or four occupy the mesial sinus and four or five the
mesial fold. In the two larger specimens observed, there are but three
plications in the sinus, and this is the prevailing number. Slender
concentric striae, sometimes a little imbricated in front, mark the sur¬
face of the shell.

Casts of this species are more common than the shell ; and those of
the ventral valve shpw the dental plates reaching to the bottom of the

343

PALEONTOLOGY OF NEW-YORK.

cavity, and margining the upper part of the muscular area, which is
o£ten distinctly limited by the rostral cavity. In the dorsal valve there
is a distinct septum reaching half the length of the valve, its inner
upper edge partially divided, and leaving an angular prominence which
has been the filling of the depression in the septum.

The surface plications appear to be more angular in specimens from
the arenaceous beds ; and the casts of the interior of some specimens,
which I have referred to this species, present distinctly angular
plications.

This species is readily distinguished from R. (S.) sapjoho by its more rotund
or ovoid form and more rounded plications. The ventral valve is more convex,
and never so flat at the sides ; while the ends of the plications, curving upward
to meet the margin of the dorsal valve, form a distinctive feature, apparent in the
profile views. In this respect, it bears more resemblance to some of the rotund
forms of the Lower Helderberg group, as for example the R. jpy rami data.

In some of its conditions as casts in a ferruginous argillaceous sandstone, this
species bears much resemblance to the R. (/S'.) contracta of the Chemung group ;
but that species is never so rotund, the sinus is deeper, and the plications are
angular.

Mr. Conrad’s description of Atrypa congregata is as follows : “ Suborbicular,
“ with about fifteen rounded costas crossed by wrinkled lines ; lesser valve with
“ the central part flat, slightly elevated, except towards the base, where it is more
“ prominent, wide at base and rapidly narrowed above, with four flattened ribs ;
“ inferior valve with a regularly concave depression in the middle. Locality. Conk-
“ lin’s Falls, near Apulia, Onondaga county.”

This species is spoken of as “the most abundant fossil in a formation of shale ”
(Table of formations, No. 22) ; and since the above described species of Rhyn-
chonella is the only one which is at all common in the neighborhood of the
locality named, I have referred it to Mr. Conrad’s species.

Geological formations and localities. In the condition of casts of the interior,
this species occurs abundantly in some calcareo-arenaceous or partially shaly bands
of the Hamilton group, near Fultonham and Summit in Schoharie county, at the
Unadilla forks in Otsego county and near South Onondaga. It is found in the
Tully limestone near Tinker’s falls. A single specimen, of small size, is from a
calcareous band in the Hamilton group at Alden in Erie county.

I have received several very good specimens from Rev. E. J. Bush of Hamilton
in Madison county.

RHYNCHONELLIDiE OF THE HAMILTON GROUP.

343

Rliynchonella ( Stenocisiiia ) prolifica ( n. s.).

PLATE LIY.

Shell subtriangular-ovate ; length and width about equal : front roun¬
ded, with a shallow sinus and gentle elevation, depressed in young
shells and becoming gibbous in older ones.

Ventral valve depressed-convex in the middle, elevated or a little gib¬
bous on the umbo, curving to the sides and gently depressed in a
shallow sinus below the middle : apex slightly incurved.

Dorsal valve equally convex with the ventral, sometimes a little more
convex, the difference increasing with age ; regularly convex as far as
the middle of the shell, below which the mesial fold becomes more or
less elevated, but rarely rises conspicuously above the general outline.
Surface marked by about twenty to twenty-two, sometimes twenty-four
angular plications, of which three occupy the mesial sinus and four
the mesial fold. Sometimes a few imbricating lines of growth are visi¬
ble, but the finer surface markings are unknown.

Length usually less than half an inch, and few individuals exceed this.
The casts of the interior show short and rather slender lamellae in
the ventral valve, and a short septum in the dorsal valve.

This species is a very common one in the eastern part of the State, usually
occurring in the condition of casts of the interior. It is distinguished by its slen¬
der angular or subangular ribs ; the shallow sinus which is gently curved upwards
in front, and the nearly straight or little curved beak, while the length and breadth
are usually about equal in young specimens.

In young specimens there is no perceptible sinus, and- sometimes but sixteen
plications visible. Some very young specimens from the western part of the State,
which may be of this species, have only about twelve plications. Specimens from
the Hamilton group of Iowa, received from Mr. O. St. John, are of very similar
character to those of New-York, but with more elongate beak.

Geological formation and localities. This species occurs abundantly in some
compact beds in the shales of the Hamilton group, near Fultonham in Schoharie
county ; and is equally or more abundant in some decomposing ferruginous beds
near Cooperstown in Otsego county. Small individuals (which I have referred to
this species in its young state ) occur at Moscow and York in the Genesee valley,
and elsewhere in Western New-York.

344

PALEONTOLOGY OF NEW-YOKK.

Rhynclionella ( Stenocisma ) dotis ( n. s.).

PLATE LIY.

Shell subtriangularly ovate, wider than high, rounded in front, or some¬
times truncate in the middle ; a shallow mesial depression and mode¬
rate elevation in front.

The dorsal valve is more or less gibbous, and the plications at the
sides are curved abruptly to the margin of the ventral valve.

The plications are subangular or rounded, and about eighteen may be
counted in the larger individuals. The surface has been marked by fine
concentric striae, and one or two imbricating lines of growth near the
front.

In two partial casts the plications are subnodose at the junction of
these imbricating lines, where they are abruptly incurved on the margins.

The largest specimen observed has a width of half an inch, with a
length of seven-tenths and a depth of one-quarter of an inch.

This shell resembles the preceding one in its general outlines, being propor¬
tionally a little wider : the ventral valve is a little more flattened on the sides,
the ends of the plications not so much curving to the dorsal valve, and the sinus
curving more abruptly in front. The beak is very slightly incurved.

Geological formation and localities. The most characteristic specimens of this
species have been found in a calcareous layer in the upper part of the Hamilton
group, at Eighteen-mile creek on Lake Erie ; and others from Geneseo and York
in Livingston county, New-York.

Rhynclionella ( Stenocisma ) carica ( n. s.).

PLATE LIY.

Shell round-ovate ; length and width about equal, rounded in front.
Ventral valve moderately convex above the middle, curving gently to
the lower lateral margins and abruptly to the cardinal slope, regularly

RHYNCHONELLIM OF THE HAMILTON GROUP.

345

arcuate from beak to base along the gently depressed mesial sinus,
which bears four plications in the bottom, and one on each side par¬
tially included, giving it an undefined outline.

Dorsal valve gibbous, somewhat regularly convex in the middle and
upper part, and interrupted only on the lower third by the moderately
elevated mesial fold'; the plications on the lower lateral margins
strongly curving to the edge of the ventral valve.

Surface marked by about thirty subangular plications on each valve ;
of which four and partially a fifth are depressed in the sinus, giving
five prominent and a sixth less elevated on the mesial fold. The finer
markings are not preserved in the specimen examined.

From a partial cast of the apex of the ventral valve, it appears to
have had short dental lamellae.

This species bears much resemblance in its general form to R. (S.) Carolina of
the Corniferous limestone ; but it is more rotund, the sinus less wide and not
reaching so far towards the beak, the plications less angular and more numerous.
I have a single specimen only, received from Rev. E. J. Bush, and this one has
the appearance of being an adult shell, measuring nearly three-fourths of an inch
in length and having about the same width.

Geological formation and locality. In the Hamilton group, near Hamilton,
Madison county, New- York.

The following species from the Tully limestone is given in this connexion on
account of its geological position and relations, although it does not appear to me
to be quite congeneric with the preceding and following species. Leaving it under
the Genus Rhynciionella for the present, I nevertheless believe that when its
internal characters shall be fully known, this one and a few others will constitute
a distinct genus. In its young condition this species has much the aspect of Leio-
rhynchus, and might readily be mistaken for a species of that genus.

[Paleontology IV.]

44

346

PALEONTOLOGY* OP NEW- YORK.

Rliyiielionclla venustula.

PLATE LY.

Atrypa cuboides : Vanuxem (non Sowerby), Geol. Report Third Dist. New-York, p. 163, f. 1.

«« « ? Hail, Geol. Report Fourth Dist. New-York, p. 215 and 216, f. 1.

Compare Atrypa cuboides : Sowerby, Geol. Transactions, 2d series, Yol.v, pl.lvi, f. 23.

Also “ << Philips, Palaeozoic Fossils of Cornwall and Devon, pa. 85, pi. xxxiv

f. 150. •

Also Texebratula crenulata : Id. ib. p. 85, f. 152.

Also Atrypa subcuboides, D’Orbiqny = A. cuboides, Philips (non Sowerby), Prodrome, Yol. i,

p. 93, n.884.

Shell in the young state oval or ovate, with a moderate or scarcely per¬
ceptible sinus, and few or no plications except upon the middle of the
shell ; becoming gibbous, rotund or subcuboid, with the width a little
greater than the length, and the depth from two-thirds to three-fourths
as great as the length, with a deep sinus and the surface entirely pli¬
cated ; cardinal line extending for two-thirds or three-fourths the
width of the shell.

Ventral valve in young shells a little less convex than the dorsal, and
moderately or scarcely at all depressed in the sinus. In older shells
the ventral valve is moderately convex in the middle above, and
abruptly depressed in the broad deep sinus, while it is flat or concave
towards the lateral margins. Umbo moderately elevated, with the
beak minute and closely appressed. The cardinal margins are often so
abruptly incurved as to give the appearance of a narrow area on each
side of the apex.

Dorsal valve in young shells a little more gibbous than the opposite,
and without defined mesial elevation ; becoming more gibbous with
the growth of the shell. In full-grown specimens the dorsal valve is
very gibbous, with a defined mesial fold reaching above the middle
of the shell, sharply truncate in front, and usually bearing six or seven
plicaations ; the sides of the shell curve very abruptly and almost ver¬
tically to the opposite valve. The apex is very abruptly incurved
beneath the beak of the opposite valve.

Surface in young shells marked by about four plications in the mesial
sinus ; while there are from ten to fifteen on the sides of the shell,

RHYNCHONELLIDiE OF 'THE TULLY LIMESTONE.

347

which are often obscurely defined. In old shells there are forty or
more rather broad, rounded, moderately elevated plications, of which
from six to eight are depressed in the sinus, and a corresponding num¬
ber elevated on the mesial fold. These, as well as some of the lateral
plications, are usually bifurcated above the middle, but occasionally
below. Those near the margin, and particularly on the fold and sinus,
are flattened and longitudinally grooved. The plications are crossed
by fine concentric striae which are not visibly imbricating.

The casts show a small rostral cavity, bordered by short and rather
thin dental lamellae, with an elongate-ovate muscular impression, and a
moderately or scarcely elevated septum in the dorsal valve. The surface
shows a beautiful ramified system of vascular markings, the main trunks
of which curve around the papillose ovarian spaces, and thence bifurca¬
ting are distributed according to the divisions of the plications, giving
a branch to each one, and these again usually subdivide towards the
extremities. The central and subordinate lateral groovings of the exte¬
rior of the plications correspond to the vascular markings and their
subdivisions.

The smaller specimens measure sometimes less than half an inch in
length and breadth ; while the full-grown shells measure from seven-
eighths to nearly an inch in length, with a width sometimes exceeding
an inch, and a depth frequently of three-fourths of an inch.

This beautiful fossil occurs in considerable numbers in several localities of the
Tally limestone, and in full-grown individuals is readily distinguished ; but the
immature phases are not so easily recognized.

This species was identified by Mr. Vanuxem with the Terebratula cuboides of
Sowerby ; and the same name with doubt was used in the Report of the Fourth
District. M. A. D’OrbAhvy has separated the species originally -described by
Sowerby from that described under the same name by Philips (loc. cit.), propo¬
sing the name Atrypa subcuboides for the latter, citing at, the same time the
American species as identical.

The British species has a different aspect and has more plications on the mesial
fold and sinus, which is proportionally more elevated in front ; while in the exfo¬
liated shell all the plications are more angular. It becomes necessary, therefore,
to propose a distinctive name for the American species. Although having a gene-

348

PALAEONTOLOGY 'OF NEW-YORK.

ral resemblance to some of the more gibbous forms of the Lower Helderbero-
group, this species is so distinct as to render its identification easy.

Geological formation and localities. This species occurs in the Tully limestone,
at Tully and at Tinker’s falls in Onondaga county ; at Ovid in Seneca county ; at
Benton and Penn-Yan in Yates county, New- York.

Rliyiichonella ( gtenocisma ) eximia.

PLATE LY.

Atrypa eximia : Ham,, Report on the Fourth Geol. District of Hew -York. Illustration 66,. fig- 4.

Shell ovate : valves subequally convex in young shells ; the dorsal valve
becoming gibbous in older shells.

Ventral valve moderately convex on the umbo, becoming somewhat
gibbous in older shells ; at about one-third the length from the beak,
becoming depressed in a wide defined sinus, which bears from four to
six plications, and usually not abruptly incurved in front : beak
incurved and not closely appressed.

Dorsal valve regularly and moderately convex in young shells, more
convex, or a little gibbous in the middle, in old shells ; mesial fold
becoming visible about* the middle or above the middle of the shell,
and often quite prominent near the front.

Surface marked by about twenty-six, to thirty or more, angular plica¬
tions, of which from four to six are depressed in the sinus and a cor¬
responding number elevated on the fold. The plications become
obsolete on the cardinal slopes, and gradually increase in size to the
centre. The shell is usually exfoliated, so that the finer surface
markings are not preserved.

The partial casts of the dorsal valve show the presence of a median
septum reaching half the length of the shell. The apex of the ventral
valve appears to have been perforate in the young shells.

In this species the young have the form and proportions of H. ($.) prolifica of
the Hamilton group ; but they are more finely plicated, and attain the size of the
larger specimens of that species before the sinus becomes much developed.

Geological formation and locality. This species occurs in the Chemung group,
at Ithaca ; and is mainly confined to a single stratum, in which it is abundant.

RHYNCHONELLIDiE OF THE CHEMUNG GROUP.

349

RIij liclionella ( Stenocisma ) stepliani.

PLATE LY.

Shell varying from subtriangular-ovate, with length and width about
equal, to rotund or subglobose’, with width greater than length ; more
or less deeply sinuate in front.

Ventral valve depressed-convex or but moderately convex above, curving
gradually to the lower lateral margins and more abruptly to the car¬
dinal slope, where it is a little concave ; becoming depressed in a
broad undefined sinus, which begins at about one-third to one-half the
length from the apex ; curving gradually in young shells, and very
abruptly in older ones, to the elevated front of the dorsal valve : beak
slightly incurved, except in the older and more gibbous specimens.
Dorsal valve prominently convex and regularly arcuate from beak to
base in young and full-grown shells, but becomes extremely gibbous
in old shells, with a prominent fold on the anterior half of the valve.
Surface marked by about twenty-eight to thirty -two angular plications,
of which four, five or six are depressed in the mesial sinus and a cor¬
responding number elevated on the mesial fold. The sinus and fold are
not distinctly limited, but a smaller and less elevated plication bounds
the fold and sinus on either side.

The specimens described are casts or exfoliated shells which do not
preserve the finer surface markings. The casts show the impression of
short dental lamellae in the ventral valve and a strong mesial septum in
the dorsal valve, reaching somewhat more than one-third the length of
the shell.

This species bears considerable resemblance in form and proportions to the
R. ( S .) eximia , but is more angular in its outline and more coarsely plicated.

Geological formation and localities. This species occurs ill the Chemung group
near Ithaca, associated with R. ($.) eximia ; at Philipsburgh in Allegany county,
and also in Cortland county, New- York. It is found near Bedford, Pennsylvania,
whence I have received some specimens from Dr. R. P. Stevens.

*

350

PALAEONTOLOGY OF NEW-YORK.

Rliynchonella (Stenocisma) duplicate.

PLATE LY.

Atrypa duplicata : Hall, Report on Fourth Gaologicsl District of New-York ; Fossils of the Chemung

group, Illustration lxvii, figs. 2 & 2 a. 1843.

Shell depressed-suborbicular or subquadrate ; length and width about
equal : valves subequally convex.

Ventral valve convex on the umbo, with beak strongly incurved ; sides,
moderately convex, sometimes a little flattened at the baso-lateral
margins and very abruptly incurved on the cardinal slopes : mesial
sinus beginning near the apex and becoming deep and angular below
the middle, usually marked by a single plication, and much produced
in front.

Dorsal valve convex, most prominent about the middle or below the
middle of its length, curving to the sides and produced in nearly a
direct line to the front.

Surface of the dorsal valve usually with two prominent plications sepa¬
rated by a deep groove, which is continued from the mesial fold, with
one or two obtuse plications on either side, sometimes a single one
scarcely defined. On the ventral valve there is usually one plication
only in the sinus, which is margined by angular folds ; and outside of
these there is one, and rarely more, indistinct folds or undulations of
the surface. Rarely there are two plications in the sinus, one smaller
than the other, with three of unequal size on the mesial fold.

In well-preserved specimens, the surface is marked by fine elevated
concentric striae and faint radiating striae.

Of the interior, little is known beyond the fact that the dorsal valve
is furnished with a distinct median septum, showing some peculiarities
at the junction of the crura ; while the ventral valve shows short blunt
dental lamellae. Should the entire interior characters become fully known,
this will probably prove to belong to a distinct genus.

RHYNCHONELLIDiE OF THE CHEMUNG GROUP.

351

The shell is usually about three-eighths of an inch in length and breadth, rarely
attaining the length of half an inch.

It is abundant in certain layers in a few localities ; but as far as known, it does
not occur east of the Genesee valley.

Geological formation and localities. This species occurs in the Chemung group,
at East-Randolph and Connewango in Cattaraugus county ; at Cherry creek and
at Howard on Chautauque creek, and more abundantly at Dexterville in Chautau-
que county, New-York.

Rliyiichonella (Stenocisma) contracta.

PLATE LY.

Mrypa contracta : Hall, Report on the Fourth Geol. District of New-York. Illustration lxvi,

fig. 3 a. 1843.

Not Rhynchonella contracta of D’Orbigny.

Mrypa laticosta and var. as above : Illustration lxvi, figs. 1 & 2.

Not A. laticosta of Phillips, loc. cit.

Shell transversely oval or subquadrate ; length and width about as seven
to ten, or. nine to twelve, abruptly and deeply sinuate.

Ventral valve prominent upon the umbo, with beak abruptly incurved
and closely appressed against the umbo of the opposite valve, gently
declining to the lateral and baso-lateral margins, and often nearly flat
in the last named portions ; the centre abruptly depressed into a
broad' deep sinus, with sloping sides which are free from plications ;
extremely produced in front, with a broad linguiform extension which
fills a corresponding depression in front of the dorsal valve.

Dorsal valve somewhat gibbous in the middle, regularly convex trans¬
versely ; the mesial fold becoming prominent a little above the mid¬
dle, and continuing almost horizontally, or slightly ascending, to the
front ; the sides curving more or less abruptly to the ventral valve,
according to the convexity of the shell.

Surface marked by about sixteen angular plications, varying from six-
. teen to twenty ; of which three are usually depressed in the mesial
sinus, with a corresponding number on the mesial fold. The four pli¬
cations of the fold originate as two at the apex, each becoming divided,
the two central ones being usually stronger than the two lateral ones.

352

PALAEONTOLOGY OF NEW-YORK.

The shell when preserved shows fine concentric striae, and towards the margin
a few crowded imbricating folds : the latter are frequently preserved in casts of
the interior. In many casts there ai’e no more than fifteen or sixteen plications
visible, those towards the margins being obsolete.

In young and half-grown specimens, found associated with the others, there are
sometimes but two plications in the sinus and three on the mesial fold (rarely a
single one in the sinus) ; while sometimes there are four plications in the sinus,
when the shell is only of medium size.

The casts show a distinct mesial septum reaching nearly half the length of the
dorsal valve, and in the ventral valve a short rostral cavity with short dental
lamella.

This species, though usually preserving its distinctive characters, presents con¬
siderable variety of aspect in its different conditions, and in different sediments.
The plications are usually subangular or obtusely angular ; but in some specimens
they are quite rounded above, while in others they are abruptly angular, and the
entire shell has a less expanded form. It often happens, in those forms with more
angular plications, that there are no more than five or six on each side of the
mesial fold and sinus ; and even the broader forms sometimes present this charac¬
ter. The plications on the lateral portions of the shell are sometimes grooved.

This species assumes not only the varieties of aspect represented in the illustra¬
tions on Plate lv, but many others not shown in the figures. The forms illustrated
in the Report of the Fourth District, and referred- to as varieties of Atrypa lati-
costa of Phillips, are apparently all of this species, and not identical with the
European form.

The figures of Phillips (loc. cit.), Plate xxxiv, 153 c, d, bear a more near
resemblance to some of the forms of our species ; but the figures of R. laticosta ,
Phillips, as given by Mr. Davidson,* do not correspond with our species ; while
the illustrations of R. pleurodon by the latter author, on Plate xra, figures 11, 12
and 13, resemble the prevailing form of our species : figures 12 and 13 repre¬
senting those found in the poorer greenish micaceous shales of the Chemung
group. The identifications with R. laticosta , as illustrated by Mr. Davidson, there¬
fore cannot stand ; that species being more nearly like our R. orbicularis , which
in turn presents many of the characters of the larger and more robust forms of
R. contracta. It also becomes extremely difficult to point out differences between
this species in its various phases, and some of those forms which occur abundantly
in the Waverly sandstones of Ohio, and I am at present compelled to regard them
as identical.

Monograph of British Devonian Brachiopoda, Plate xiv, figures 1-3.

RHYNCHONELLIDiE OF THE CHEMUNG GROUP.

353

Geological formations and localities. This species occurs in the Chemung group,
both in the shales and shaly sandstones of the central part of the group, and also
in ferruginous sandstones and conglomerates of the upper portions, and in nume¬
rous localities from Tioga county to the western limits of the State. It is found
near Owego, near Cortlandville, at Ithaca, on Cayuta creek, at Chemung narrows,
Elmira, Painted-post, Bath, Angelica, Rockville, Philipsburgh ; near Olean, near
New- Albion ; near Westfield, French creek, Howard’s on Chautauqua creek,
Twenty-mile creek and elsewhere ; also at Meadville, Pennsylvania, from all of
which places I have specimens before me. I have likewise received specimens
from Dr. R. P. Stevens, collected at Bradford, Pennsylvania. Specimens from
Licking county, Ohio, have the same aspect, and present all the modifications of
form, varying number of plications on fold and sinus, and other characters marking
the New-York specimens.

Rliynclionella (Stenocisma) orbicularis.

PLATE LY.

Rhynchonella orbicularis : Hall, Thirteenth Report on the State Cabinet, p. 88. 1860.

Shell suborbicular, ventricose on the dorsal valve ; width greater than
the length.

Ventral valve moderately convex, scarcely gibbous on the umbo ; beak
incurved ; outline gently curving on the lateral and baso-lateral mar¬
gins, and the centre gently depressed in a broad and strongly defined
median sinus.

Dorsal valve gibbous in the middle, arcuate from. beak to base; sides
abruptly curving to the ventral valve ; median fold beginning above
the middle of the length, and becoming more prominent towards the
front.

Surface marked by about twenty-four or more subangular or rounded
ribs, those of the central portion being strong and elevated, and those
towards the cardinal slope gradually finer and less distinct. There are
four or five plications in the mesial sinus, and from four to six on
the mesial fold, which are moderately elevated and gently curving
[ Paleontology IV.] 45

354

PALAEONTOLOGY OP NEW-YORK.

to the front. The plications on the sides are more or less abruptly
curved to the margins of the shell. The shell, when preserved, is marked
by fine close concentric striae : the specimens are usually casts.

I have referred to this species some gibbous forms with moderately elevated
mesial folds, in which the plications are subangular or rounded, and the entire
shell preserves a rotund form. The original of this species is the largest one that
has been observed, and is nearly an inch in length, with a somewhat greater breadth.
The more common forms are about three-fourths of an inch in diameter.

This species presents many features in common with JR. sappho of the Hamilton
group ; and I am prepared to find, among larger collections, a gradation from
one to the other.

Geological formation and localities. This species has been found in the higher
beds of the Chemung group ; in Chautauque county, New-York ; at Meadville, and
iu some loose masses of the group on Oil creek, Pennsylvania.

Rhynchonella (Stenocisma) sappho, var.

PLATE LY.

Specimens from the ferruginous sandstone of Licking county, Ohio,
present all the characteristic features of R. ( S .) sappho of the Hamilton
group. The specimens vary from about half an inch to three-fourths of
an inch in length, with a somewhat greater breadth. The plications vary
from obtusely angular to rounded, and often show a distinct groove
towards the margin of the shell.

This form is common and even abundant in the ferruginous sandstones known
as the upper part of the Waverly sandstone series of Ohio, and it is introduced
for comparison with the Hamilton and Chemung forms of New-York.

GENUS LEIORHYNCHUS.

U55

Genus Leiorhynchus (Hall).

Leiorhynchus : Hall, Thirteenth Report on the State Cabinet, p. 75. 1860.

The shells of this genus are ovate, circular or transverse, with valves
unequally convex, and marked by a median sinus and fold in the ven¬
tral and dorsal valves respectively.

The surface is plicated by rounded bifurcating plications which are
always more conspicuous on the mesial fold and sinus, while they
often become obsolete on the lateral portions of the shell ; concen¬
trically marked by strong lines of growth. Substance of the shell
fibrous, usually thin.

V alves articulating by teeth and sockets ; the apex of the ventral valve
perforate at some period of its growth, the lower side being completed
by deltidial plates. On the interior of the ventral valve, two short
diverging dental lamellae extend into and are joined to the sides or
bottom of the rostral cavity ; the muscular impression occupies a
narrow triangular or ovate-triangular space below the dental lamellae.
The dorsal valve has a well defined septum, often reaching below the
middle of the valve, and divided above, leaving a triangular or spoon¬
shaped depression. The hinge-plates are narrow strong processes, with
sockets embracing the teeth of the opposite valve.

Numerous examples, showing the interior to some extent, have not
developed any spiral appendages in the shells of this genus, and I am
now quite satisfied that they belong to the Rhynchonellidae. Externally
these shells differ from Stenocisma in the low rounded and bifurcating
plications, and their obsolescence on the lateral margins, while they are
never interlocked at the junction of the valves. When occurring in the
same beds, the two have a different aspect ; and Leiorhynchus is abun¬
dant in the black shales where Stenocisma rarely occurs. It appears,
therefore, desirable to continue these forms under a distinct genus.

These shells are at present known only in the Hamilton and Chemung
groups ; beginning their existence in the Marcellus shale, being quite
abundant in some dark shaly beds in the middle of the group and in the

35©

PALEONTOLOGY OF NEW-YORK.

Genesee slate, and occurring generally in the more shaly portions of the
Chemung group.

Leiorhynchus limitaris.

PLATE LYI.

Orthis limitaris : Vanuxem, Geol. Report Third District New-York, p. 146, f. 3. 1842.

Atrypa limitaris : Hale, Geol. Report Fourth District New-Tork, p.182, f. 11. 1843.

Leiorhynchus limitaris : Hall, Thirteenth Report on the State Cabinet, p. 85. 1860.

Shell ovate, suborbicular or transverse, moderately or extremely gib¬
bous, with the sinus and mesial fold more or less developed.

Ventral valve in young shells scarcely less convex than the opposite,
becoming gradually more dissimilar with the growth. In old shells
the ventral valve is rather gibbous near the beak, and gradually
depressed below, becoming deeply sinuate, produced in front and
abruptly truncate ; beak closely incurved.

Dorsal valve more convex than the opposite, gibbous in older shells,
the mesial fold becoming developed below the middle of its length ;
umbo gibbous, and often rising nearly as high as the beak of the ven¬
tral valve.

Surface marked by numerous angular or subangular plications, those of
the mesial fold and sinus distinctly bifurcating, while sometimes a few
’ of those on the sides are divided ; concentrically marked by fine striae
as in all the species of this genus.

In the youngest specimens observed, the ventral valve below the
umbo is flat or concave ; while in those a little older, the two valves are
nearly equal, and the shell is nearly circular. The illustrations oh Plate
lvi present the principal varieties of form of this species.

Geological formation and localities. This species is abundant in the Goniatite
limestone of the Marcellus shale ; and in the absence of this limestone, it is
abundant in certain layers of the Marcellus shale, always characterizing that hori¬
zon, a fact -which induced Mr. Vanuxem to give it the name limitaris. It is
widely distributed, occurring in the Goniatite limestone in Schoharie, and in the
same position at intermediate points as far as Marcellus in Onondaga county. It
is abundant in the shale at Avon, at Leroy, near Alden, and at numerous other
places within the State of New- York. I have not seen specimens from any western
locality.

RHYNCH0NEXLID2E OP THE GONIATITE LIMESTONE. . 357

Leiorhynchus mysia.

PLATE LVI.

Shell small, suborbicular ; valves subequally convex, with a few strong
plications reaching half way from the margin to the beak of the
shell.

This species is distinguished by its small size, circular form, and proportionally
much stronger plications, of which there are at least three on each side of the
fold and sinus, terminating near the middle of the shell. In a few larger indi¬
viduals, the plications have a greater extent. A single plication marks the sinus.
The length of the shell is usually less than three-eighths of an inch ; width a
little greater. One individual measures nearly a quarter of an inch in length.

In a specimen of L. limitaris of the same size, the plications are scarcely
perceptible.

Geological formation and locality. This species occurs in the Goniatite lime¬
stone of the Marcellus shale, in Schoharie, associated with L. limitaris.

Leiorhynchus qnadricostata.

PLATE LYI.

Orthis qnadricostata : Vandxeii, Geol. Rep. Third Dist. New- York, p. 186. 1842.

** “ Hall, Geol. Rep. Fourth Dist. New-York, p. 223, f. 2. 1843.

Leiorhynchus qnadricostata : Hall, Thirteenth Report on the State Cabinet, p. 86. 1860.
Compare Leiorhynchus multicosta : Id. Ib., p. 85. 1860.

SAell broadly ovate, somewhat gibbous, with distinct mesial fold and
sinus.-

Ventral valve a little gibbous towards the beak ; sides nearly flat, with
a wide mesial sinus.

Dorsal valve more gibbous than the opposite, greatest convexity in the
middle of the valve ; mesial fold prominent.

Surface of mesial fold and sinus marked by three, four or five rounded
plications, which bifurcate above. Sides of the valves obscurely marked
by rounded plications, which become obsolete towards the margin, and
sometimes this part of the shell is almost entirely free from any
markings whatever.

358

PALEONTOLOGY OP NEW- YORK.

The specimens originally referred to this species occur in the Genesee slate,
and are more or less compressed or otherwise crushed, so that the real form and
proportions cannot well be determined. The shell in this rock has been extremely
thin, and the incipient plications outside of the mesial fold and sinus are usually
almost obliterated by the pressure which has flattened the shell. In the compari¬
son of a considerable number of specimens from the black shale with those of the
bluish shales of the Hamilton group below, I am somewThat doubtful as to the
propriety of separating the L. multicosta from this species, since in that one there
is a great variation in the strength of the lateral plications, as well as in the space •
towrards the cardino-lateral margins where they are more or less obsolescent.

The cast of the interior shows an elongate narrowly ovate muscular area in the
ventral valve, and a strong septum in the dorsal valve, which is^divided above and
margined on each side by the muscular imprint. The entire interior of the shell
or cast, when preserved, is beautifully marked by the ramifying vascular impres¬
sions which enclose the papillose ovarian spaces.

The illustrations show the characteristic features of the species, as occurring
in the Genesee slate. The ordinary size of specimens is from three-fourths to one
inch in length, with a width nearly the same or a little greater. One specimen
measures more than an inch and a quarter in length and an inch and a half in
width.

Geological formation and localities. This shell occurs in the Genesee slate at
Bigstream point and other places on Seneca lake ; near Ogden’s ferry on Cayuga
lake, and at other places thence to Ludlowville ; below Ithaca and elsewhere in
the region of Seneca and Cayuga lakes.

Leloihynchus multicosta.

PLATE LVI.

Leiorhynchus multicosta : Hall. Thirteenth Report on the State Cabinet, p. 85. °1880. '

Rhynchonella ? laura : Billings, Canadian Journal, No. xxvii, p. 273. 1860.

Compare Leiorhynchus quadricostata (loc. cit.), ut sup.

Shell ovate, with the length and greatest width nearly equal (in com¬
pressed specimens the width is often greater than the length) ; sides
gently curving from the beak for about two-thirds the length, thence
curving abruptly to the front, which is truncate in the middle for the
width of the sinus.

Ventral valve gibbous on the umbo, curving to the sides, becoming
gradually depressed in the centre and forming a sinus which is broad

RHYNCHONELLIDiE OF THE HAMILTON GROUP.

339

and gently defined below the middle of the length of the shell. The
umbo is prominent, the beak small and neatly incurved over the umbo
of the opposite valve.

Dorsal valve much more convex than the ventral, the greatest gibbosity
a little above the middle, gently curving to the sides and baso-lateral
margins ; the centre elevated in a broad mesial fold.

Surface marked by numerous rounded or subangular plications, of which
from three to six or seven are depressed in the sinus and a correspon¬
ding number elevated on the fold. The plications of the fold and sinus
are always bifurcating, those of the sides simple or obscurely bifur¬
cating, and all usually becoming obsolete at one-third to one-fourth the
length of the shell from the apex; concentrically marked by raised
thread-like strise, which sometimes become squamose imbricating
folds or lines of growth.

The cast of the ventral valve shows a narrow rostral cavity and slen¬
der dental plates, with a lanceolate or lance-ovate muscular area. The
ovarian spaces are papillose-striate, and outside of these are the rami¬
fying vascular imprints. The cast of the dorsal valve shows a median
septum reaching more than half the length of the shell, divided above,
leaving a triangular pit. The muscular imprint is narrow, elongate, and
marks the surface on each side of the septum more than half-way to the
base.

This species presents considerable variety in its surface characters, varying
from specimens with few perceptible plications on the sides of the shell, to those
with six. or seven on each side, and from three to seven in the mesial sinus. In
some of the specimens in the Hamilton shales, the plications are numerous, suban¬
gular, reaching to the apex of the shell, and showing distinct bifurcations in
those of the lateral as well as the mesial portion of the valve.

In order to make a comparison with the Canadian species, I have procured
specimens from Bosanquet and Widder in Canada West ; and I find the same
variations among them as in those of New- York. In seventeen specimens examined,
there were two corresponding essentially with the figure of Mr. Billings (loc.
cit.), except that the plications are obsolete towards the beak : one of these
specimens is about an inch in length and breadth, and the other a little less. In
other specimens of nearly the same size, there are four or five plications on the

36©

PALAEONTOLOGY OF NEW-YORK.

mesial fold, while those on the sides of the shell are obscure or nearly obsolete ;
and were they imbedded in an argillaceous shale instead of a calcareous one, they
would not be very different in appearance from Leiorliynchus qucidricostatci.
Smaller specimens from Widder present almost- every phase of development in
the plications.

Altogether, accepting for the present the distinction between these forms, I
believe they will prove identical ; and I am not indisposed to unite with these
the L. mesacostalis of the Chemung group.

Geological formation and localities. This species occurs in the Hamilton group,
from Schoharie county to the western limits of the State. It is common at Fulton-
ham and Summit ; at Plainfield and Unadilla forks ; and also on the shores of
Owasco, Cayuga, Seneca and Canandaigua lakes. It is less common at York, Mos¬
cow, Darien and Eighteen-mile creek. The specimens from Canada West are less
compressed than those of New- York.

Leiorliynchus iris (n. s ).

PLATE LYI.

Shell small, subangularly ovoid, with a deep sinus and prominent mesial
fold.

Ventral valve convex on the umbo, flattened on the sides and deeply-
depressed in a median sinus below the middle ; apex elevated, perfo¬
rate, the lower side of the foramen bordered by deltidial plates with a
distinct narrow area on each side.

Dorsal valve gibbous in the middle, curving abruptly to the sides, and
strongly elevated in a mesial fold towards the front.

Surface plicated, the plications subangular, beginning at one-third the
length from the apex, some of them obscurely bifurcating; concen¬
trically marked by fine elevated strioe and a few imbricating lines of
growth.

Geological formation and locality. In the calcareous shales of the age of the

Hamilton or Chemung formations, near Rockford, Indiana. Received from Mr.

O. St. John.

RHYNCHONELLIDiE OF THE HAMILTON GROUP.

361

Leiorliynclius Kellogg! (n. s,).

PLATE LYI.

Shell ovate or suborbicular, more or less rotund, sinuate in the middle ;
length and breadth nearly equal in the younger shells, the width
becoming greater in old shells ; the middle of the front abruptly
truncate.

Ventral valve gibbous a little below the umbo, curving gently to the
sides and becoming gradually flattened in the middle, and deeply
sinuate in the lower part. Beak closely incurved over the umbo of the
opposite valve, with apex acute.

Dorsal valve regularly convex in the middle and upper part, curving to
the sides : the broad flattened mesial fold usually becomes developed
below the middle of the length.

Surface marked by low rounded plications, of which there are four, five
or six, and sometimes ten in the mesial sinus, and a corresponding num¬
ber on the mesial fold. There are six or seven plications on each side
of the mesial fold ; and both these and the central ones usually extend
no more than half-way to the apex, and sometimes not so far.. When
the shell is preserved, there are fine radiating striae upon the upper
half, which are less distinct below ; and the entire surface is marked
by fine thread-like concentric striae, which, at intervals, are crowded
into stronger wrinkles.

The casts show a narrow ovate muscular area in the ventral valve,
with a slender process filling the rostral cavity. In the dorsal valve there
is a strong septum, with narrow muscular imprints on each side, reaching
below the middle of the length.

A large individual of this species has a length of seven-eighths of an
inch with a width of one inch. A smaller specimen has a length and
width of three-fourths of an inch.

[ Paleontology IV.]

48

362

PALAEONTOLOGY OF NEW-YORK.

In some of its phases, this species approaches to the Leiorhynchus multicosta ;
but it is proportionally broader, and the plications do not extend so far towards
the beak, while the prevailing aspect is quite different.

Geological formation and locality. Specimens of this species were collected
in the northern part of Ohio, from a calcareous rock,\associated with Stropho-
donta demissa, S. perplana, Spirifera mucronata, a species of Athyris and a Meris-
tella, by Dr. G. M. KELLOGG.of Keokuk, Iowa, from whom I have received them.

I have the cast of a single specimen from the Hamilton group in Eastern New-
York, which very closely resembles this one, and is probably identical with it.

Leiorhynchus sinuatus (n. s ).

PLATE LVII.

Compare Leiorhynchus limitaris (ut sup.).

Shell ovate or orbicular, more or less distinctly sinuate from the mesial
sinus, and truncate in front.

Ventral valve moderately convex, with the sides nearly flat, depressed
in the middle and extending into a broad shallow sinus.

Dorsal valve moderately convex and sometimes gibbous, gently curving
to the sides ; the mesial fold broad and flat.

Surface marked by about twelve to fourteen or fifteen rather coarse
rounded or subangular plications, of which four or five are depressed
in the mesial sinus. The sinus and fold are not often conspicuous above
the middle of the shell. Concentric strise as in others of the genus.

It may be found that this form is only a variety of L. limitaris , existing under
other conditions and at a later epoch. The plications are coarser, and do not
extend to the beak as in L. limitaris , and the shell attains a somewhat greater size
and more robust aspect.

Geological formation and localities. This species occurs in the shales of the
Chemung group at Ithaca ; at Chemung narrows, and other places in Southern
New-York.

Leioiliynclms mesacostalis.

PLATE LVII.

Mrypa mesacostalis : Hall, Geol. Report Fourth Dist. New-York. Illustrations of Fossils of the
Chemung group, 64, f. 1 a and 1 b. 1843.

Leiorhynchus mesacostalis : Id., ThirteenthReport on the State Cabinet, p. 86. 1860.

Shell oval or ovate, more or less gibbous, sinuate towards the front.

RHYNCHONELLIDJE OF THE CHEMUNG GROUP.

363

Ventral valve usually moderately convex, gibbous on the umbo, gently
curving or flattened on the sides, depressed in the middle into a wide
shallow sinus ; apex closely incurved.

Dorsal valve convex, more or less gibbous, with the mesial fold promi¬
nent below the middle of the shell.

Surface of mesial fold and sinus marked by four, five or six well-defined
rounded plications, which reach nearly or entirely to the apex, and
are dichotomous in their upper part. Sides of the shell smooth, or
obscurely marked by low obsolete folds ; concentrically marked by
fine striae.

In the larger number of specimens, the lateral portions of the fossil
are essentially free from plications, but they are sometimes visible, and
in a single small specimen there are two plications on either side of the
sinus ; and one larger specimen shows a similar character. In others,
there are inequalities of surface, indicating the plications. It should be
recollected, however, that the specimens are usually in the condition of
partial or entire casts, and these features may have been more strongly
developed in the shell.

The cast of the dorsal valve presents the usual features of all the spe¬
cies in the longitudinal septum, which is distinctly divided on its upper
inner face.

It is not difficult to conceive how, by a gradual obsolescence of the lateral pli¬
cations of the L. qucidricostata of the Genesee slate, and by acquiring a more
robust habit in a different sediment, this form in the Chemung group may be
only a modification of that which holds a position in strata several hundred feet
below. Although retaining the specific designation for the prevailing Chemung
form, I am quite prepared to see the propriety of uniting it with the species
just named, and perhaps even with the L. multicosta of the Hamilton group.

Geological formation and localities. This species occurs in numerous localities
of the Chemung group in the central part of the State. It has been collected near
Ithaca, at Chemung and Chemung narrows, near Elmira, Bath, etc. I have not
seen the species in the western counties of Cattaraugus and Chautauque.

S04

PALAEONTOLOGY OF NEW- YORK!.

Leiorhynchus globuliformis.

PLATE LYII.

Atrypa globuliformis : Vanuxem, Geol. Report Third Dist. New-York, p. 182, f. 2. 1842.

I adopt the name applied by Mr. Vanuxem to some .gibbous forms of what
appear to be Leiorhynchus. The species is spoken of as occurring “ in myriads ”
in this group of strata in the Third District. I have nevertheless had an opportu¬
nity of examining but a few individuals, which are casts of gibbous dorsal
valves, marked along the centre by four or five strong rounded plications, which
are a little elevated above the general surface of the shell, and margined by a
narrow elongate muscular impression. It is possible that larger collections may
show the propriety of uniting these with L. mesacostalis.

Geological formation and localities. This species occurs in the Chemung group
in the south part of Otsego county, and elsewhere in the southeastern part of the
State of New- York.

Leiorhynclms duirius (n. s.).

PLATE LYII.

Shell broadly ovate, rapidly expanding in width from about the middle
of its length, and wider than long ; concave along the cardino-lateral
margins.

Valves moderately and almost equally convex ; the ventral valve scarcely
sinuate, and the dorsal valve with a slightly elevated fold near the
front.

Surface marked by twenty-four to twenty-six slender rounded plications,
of which about six are raised on the mesial fold. Length half an inch,
with the width a little greater. * ^

Of two well-marked specimens, one has^a slight fold and sinus, affec¬
ting only the front of the shell ; the other specimen is not perceptibly
marked by this feature. The plications or striae are finer than in any
other species, and extend quite to the apex of the valves.

This species is apparently from the calcareous beds of the Marcellus shale, but
the particular locality is not known.

GE'KUS LEPTOCCELIA.

365

GENUS LepT0C«ELIA (Hall).

This name was proposed in the Tenth Report on the State Cabinet
(1856, published 1857), for some forms usually referred to Terebratula
and Rhynchonella by authors. The genus was described and illustrated
in the Twelfth Report on the State Cabinet, 1859.*

I have subsequently found it necessary to separate some of the species
originally included under this genus, on account of a different internal
structure ; but the typical forms remain as first characterized. Unfortu¬
nately the- specimens have not yet yielded a full knowledge of their
interior structure.

Leptoccelia acutiplicata.

PLATE LVII.

Atrypa acutiplicata : Conrad, Annual Report on the Palaeontology of New-York, p. 64. 1841.

This species is described by Mr. Conrad as follows : “ Short, ovate
“ acute, compressed, with six to eight acute profound plicrn ; beak of
“ larger valve acute, concave beneath the apex in front ; three or four
“ strongly marked concentric impressed lines. Locality : Near Water-
“ ville, in Onondaga limestone.”

The shell is planorconvex, varying in form from ovate acute to orbi¬
cular. The ventral valve is moderately convex, with the beak slightly
incurved. The dorsal valve is depressed-convex, sometimes flat or con¬
cave from compression.

In the greater number of specimens, the plications are from six to
eight on each valve, strongly angular ; the central one on the ventral
valve depressed, and margined on each side by a larger one, while on
the dorsal valve two plications are slightly elevated, giving an abrupt
sinuosity in front. The shell is concentrically marked by strong imbri¬
cating lines of growth.

#See Twelfth Report oh the State Cabinet, p. 32; and Palaeontology of New-York, Yol. iii, pp. 345
and 447.

PALEONTOLOGY OF NEW-YORK.

Under other conditions, the plications are more numerous and rounded, the
squamose imbricating lines less conspicuous, and the shell takes a more orbicu¬
lar form, approaching to the L. flabellites ; but the beak is never so strongly
incurved as in that species. It may be doubtful whether an examination of a large
number of specimens will sustain a separation from L. {A.) flabellites ; but while a
considerable number of individuals from two or three localities sustain the charac¬
ters originally given, I shall retain it under a distinct specific name.

Geological formation and localities. This species occurs in the Upper Helder-*
berg limestone, near Waterville and at Cassville, Oneida county ; at “ Dry-lots,”
Herkimer county ; at Jamesville, Onondaga county, and at East- Victor, Ontario
county. Specimens from the same horizon at Waterloo in Seneca county have a
more orbicular form, with more numerous and less angular plications.

With our present knowledge of the characters of the Genus Lbptoccelia, the
L. flabellites, L. fimbriata and L. acutijglicata will remain as typical forms of the
genus, while Lejptocoelia concava, and L. dichotoma (Pal. New-York, Vol. iii, pp. 245
'and 452) must be referred to the Genus Coelospira ; to which may be added the
L. (Atrypa) disparilis of the Niagara group.

The species Leptoccelia {Atrypa) hemisphetdca ( Pal. New-York, Vol. n, pa. 74,
pi. xxiii, f. 10) and L. {A.) planoconvexa (Ibid. pa. 75, pi. xxiii, f. 11 ; and Vol. hi,
pi. ciii b, f. 4 and 5) are apparently true Leptoccelia, both from external form
and from what we know of their internal structure. I nevertheless regard it as
desirable to make critical examinations of the Clinton group species, in the hope
of arriving at a more satisfactory knowledge of their internal structure and
relations.

GENUS CAMAROP HOBIA.

367

Genus Camaropiioria (King, 1844).

The Genus Camarophoria is described as having the shells of sub trigo¬
nal form, with convex valves longitudinally “ divided by a sinus and
“ mesial fold. Beak entire, acute, more or less incurved ; under the
“ extremity of which a small fissure is sometimes exposed : no area or
“ deltidium. Surface generally plaited, with or without marginal expan-
“ sions : shell structure impunctate ; valves articulating by means of
“ teeth and sockets.

“ In the perforated valve , the dental plates are conjoined at their dorsal
“ margins, forming a trough-shaped process affixed to a low medio-longi-
“ tudinal plate. In the smaller valve , the space between the sockets is
“ occupied by a small cardinal muscular protuberance or boss; on either.
“ side of which two long slender processes curve upwards, to which
“ were, no doubt, attached the free cirrated spiral fleshy arms. From
“ beneath the cardinal process, a high vertical mesial septum extends to
“ a little more than a third of the length of the valve, supporting along
“ and close to its upper edge a spatula-shaped process, considerably
u dilated towards its free extremity, and projecting with a slight upward
“ curve to nearly the centre of the shell.”

The typical form, C. schlotheimi (Yon Buch sp.), has the same form and
expression of a strongly plicated Rhynchonella, and differs mainly in
the trough-shaped process formed by the union of the dental lamellae.
Authentic examples are known in Europe from the Carboniferous and
Permian systems, and Mr. Davidson expresses a belief that it will be
found in the Devonian. Unfortunately I have had no opportunity of
seeing more than a single American species which could be satisfactorily
referred to this genus, and that one has a plicated surface and rhyncho-
nelloid form. It is with much hesitation, therefore, that I refer the fol¬
lowing smooth shell of Devonian age to this genus.

In making a final examination of the obscure lind doubtful mate¬
rial of the Corniferous limestone, containing Meristella, Terebratula,

363

PALAEONTOLOGY OF NEW-YORK.

Cryptonella, etc., I have found a shell of the form of the first named
genus, in which the dental lamellae of the ventral valve are united on
the back, forming a trough-shaped process, which is supported on a thin
septum extending for half the length of the valve. In the dorsal valve
there is likewise a simple median septum extending about one-third the
length of the shell, and which, on its upper margin, is. expanded, forming
a shallow depression. No evidence of oral lamellae have been observed,
but in all essential particulars this internal structure is that of Camaro-
phoria ; and I shall thus refer the species, for the present at least.

Camapojtlioria euciiaris (n. s.).

PLATE LVII.

. Shell broadly ovate, length a little greater than the width.

V: entral valve ovate, with the beak extended and arcuate, gibbous above
the middle, curving gently to the sides, broadly flattened or a little
depressed towards the front, and terminating upwards in a broad short
linguiform extension, giving the anterior margin an abruptly rounded
or truncate aspect.

Dorsal valve gibbous in ‘the upper part, more abruptly elevated along
the middle and towards the front, slightly^oncave on each side of the
broad undefined elevation : anterior margin sinuate. Beak closely
incurved into the cavity beneath the apex of the ventral valve.
Surface marked by fine .concentric striae, which at intervals are crowded
into lamelliform ridges. Shell apparently impunctate.

The interior of the ventral valve has a narrow trough-shaped process, extending
about one-third the length of the shell, and supported on a thin median septum
which extends beyond the anterior end of the trough. In the dorsal valve, the
septum rises vertically for nearly a third of the depth of the cavity embraced by
the two valves, and has. its upper margin abruptly and narrowly expanded.

The width, in two specimens, is three-fourths of an inch, and the length a little
greater.

Geological formation and locality. This fossil was collected in the Corniferous
limestone, of Canada West, by Mr. J. De Cew.

* GENERA PENTAMERUS, &o.

2SG9

OBSERVATIONS ON THE GENERA PENTAMERUS, PENTAMERELLA, STRICKLAN-
DINIA, ANASTROPHIA, AMPHIGENIA, RENSSEL2ERIA, etc.

The Genus Pentamerus was proposed by Mr. Sowerby in 1813, to indi¬
cate the peculiar internal structure of P. knightii, which is the type of
the genus. Dalman,* objecting to Sowerby’s name, on the ground that the
shell was not five-chambered, proposed the name Gypidia as a substitute ;
but the latter has not been adopted by naturalists.

Since that time, much information has been obtained regarding the
disposition of the internal parts of the shells of this genus, through the
labors of the European palaeontologists de Yerneuil, King, Barrande,
M‘Coy, Suess, Davidson, Salter and others. In the meantime, however,
other species have been referred to the genus, which, having the general
external characteristics of Pentamerus, still possess features that render
their union with that genus incompatible ; and farther study has shown
the necessity of separating them. Among the European forms which are
regarded as strictly referable to the genus, are P. knightii ( Sow.), P.vogu-
licus (deVer.), P.galeatus (Dal'm.), P. sieberi (Yon Buch), P. pelagicus (Bar.),
and P. optatus (Bar.); while P. oblongus and P. lens have the characteris¬
tic features of the genus less conspicuous, the exterior being smooth and
the form less rotund. Pentamerus liratus andP. microcamerus have a straight
hinge-line and distinct area.

In 1859, Mr. Billings proposed the separation of certain forms from
the typical Pentamerus, under the name of Stricklandia ( Stricklan-
DiNiAf), which he describes as follows :

GENUS STRICKLANDIA = STRICKLANDINIA (Billings).

“ Generic characters. Shell usually large, elongate oval, transversely oval or

“ circular, sometimes compressed : valves nearly equal ; a short mesial septum

“ in the interior of the ventral valve supporting a small triangular chamber

* Petrefacta Suecana, in Konigl. Vet. Acad. Handl., 1827^

f In consequence of the name being preoccupied in botany, Mr. Billings has proposed to change
to STRICKLANDINIA.

[ Palaeontology IV.]

47

37©

PALAEONTOLOGY OF NEW-YORK.

“ beneath the beak as in Pentamerus. In the dorsal valve, no longitudinal sep-
“ turn, spires or loop ; the whole of the internal solid organs consisting of two
“ very short or rudimentary dental plates, which, in some species,, bear pro-
“ longed calcified processes for the support of the cirrated arms. In all the
“ species, the ventral valve has an area more or less developed.

“ This genus includes three English species, which have been loug known under
“ the names of Pentamerus lens , P. liratus and P. Icevis. All these, and the
“ three Canadian species, abound in rocks of the age of the Middle Silurian,
“ such as the Llandovery rocks of Sir R. Murchison, and the Clinton and
“ Niagara groups of the New-York geologists. No species have as yet been
“ found either above or below the Middle Silurian. On the other hand, the
“ Genus Pentamerus occurs more or less frequently in all formations from the
“ Black-river limestone to the Devonian inclusive.”

The European Pentamerus liratus undoubtedly belongs to a genus dis¬
tinct from P. knightii, having a straight hinge-line, an area on the ven¬
tral valve, with a sensible mesial depression and corresponding eleva¬
tion on the opposite valve. The species has likewise a short septum, and
supports a small triangular pit in the ventral valve; while in the dorsal
valve the hinge-plate is divided, and the parts are extended in long
lamellae into the interior of the valve. The Pentamerus microcamerus,
M‘Coy (= Spirifera? Icevis, Sowerby), belongs also to the same group,
having a straight hinge and narrow area, with a short V- shaped pit;
characters unlike those of true Pentamerus. At the same time, the Pen¬
tamerus lens and P. Icevis, which are, by Mr. Billings, united with
P. liratus under the Genus Stricklandinia, appear to me to differ very
widely from that species. They have no area, in the proper acceptation
of that term, and the hinge-line is not extended. In the ventral valve,
the long V-shaped pit is supported on a septum which sometimes extends
for nearly half the length of the valve. Moreover, the dorsal valve in
the American species of P. oblongus is marked by the presence of very
extended lamellae, which are united at their origin and spread laterally
till their free margins meet .the corresponding margins of the lamellae
forming the V-shaped pit in the ventral valve ; and running parallel
with it for nearly its entire length they then become vertical, and are

GENERA PENTAMERUS, &o.

371

continued as far as the middle of the length of the valve, where their
extremities apparently become free. In these features, there is no essen¬
tial difference between P. oblongus and P. knightii or P. galeatus.

In Pentamerus lens, or a closely allied form, from Anticosti, the dorsal
valve possesses similar characters, and there is no area on the ventral
valve. Restricting the designation to such forms as P. liratus and P. micro-
carrier us among the European species, there is good ground for the sepa¬
ration ; but the other species do not appear to me congeneric. Through
the kindness of Sir W. E. Logan, I have been permitted to examine
the American species of Stricklandinia, S. gaspensis , S. canadensis and
S. anticostensis ( Billings), and also the species referred to the European
P. lens. The first two appear to me to be congeneric with P. liratus, and
do possess the characters of the genus as described. Limiting, therefore,
the application of the term as here indicated, I think we have a well-
marked genus, which, typified by the species above named, may also
include others heretofore referred with doubt to Spirifera. I conceive,
however, that our appreciation of generic limitations will not be
enhanced by including under the same term the P. lens and P. oblongus
= P. Icevis.

Though at first restricting the genus to the Middle Silurian forma¬
tions, Mr. Billings has, at a later period, included under Strickladinia
the Pentamerus' elongatus of Vanuxem = Rensselceria elongata (Ball), a
Devonian species. This form was first placed und'er Pentamerus, from its
resemblance to P. oblongus ; and I finally referred it to RensselcEria,
from the generally similar shape, similar muscular impressions of
the dorsal valve, and the prismatic or punctate texture of the shell ;
having at that time an imperfect knowledge of the interior structure of
the ventral valve. Now this species has no area on the ventral, valve ;
but it has a V- shaped pit supported by a septum precisely as in Penta¬
merus ; while both the muscular impression of the dorsal valve, and the
structure of the hinge-plate, are precisely the same as in Rensselceria.
I cannot see, therefore, upon what good ground this shell should be asso¬
ciated with P. liratus, P. gaspensis, P. canadensis and P. anticostensis , which
have a straight hinge-line, an area on the ventral valve with a septum

372

PALAEONTOLOGY OF NEW-YORK.

supporting a short V-shaped pit, a different muscular imprint and hinge-
processes of the dorsal valve, and a fibrous or lamellose structure of
shell, and are otherwise externally marked in a very characteristic
manner.

I have taken some pains to bring together specimens of P. (P.) elonga-
tus, and we have now the means of knowing its real characters to a very
considerable extent. As before observed, the dorsal valve presents all
the characteristics of Renssel^eria in its hinge-structure and muscular
impressions : there is the same narrow foramen beneath the hinge-
plate, a pedicle-opening, and the filling of this is preserved in several
specimens of the casts ; while this portion of the separated valve shows
the same features in a most unequivocal manner, and it is quite impossi¬
ble to point out any characters by which it may be separated from the
same part of the shell in Rensselasria. The crura are free from near their
origin, and have been traced for some distance within the cavity, and
gently curving to the ventral side ; but their termination is unknown.
When, however, we examine the hinge of the ventral valve, we find a
modification of the dental plates, which are prominent in Renssel.eria
(as shown in fig. 3 g, h km, Plate cviii, Paleontology, Vol. iii), but which
are here produced anteriorly and united at their dorsal margins. The
incipient septum of the bottom of the valve of Renssel^eria becomes
developed, and sustains the united bases of the dental plates ; and we
have the V-shaped pit and central septum of Pentamerus.

In the separated valves of this species, the margins of the triangular
fissure of the ventral valve are as clearly defined, and as free from area,
as are the valves of Athyris or Meristella.

Generic significations must have some limit, and we cannot consent
to unite three so widely differing and well-marked types as P. liratus ,
P. gaspensis, etc. with P. oblongus and P. lens on the one hand, and P. elon-
gatus on the other.

There is also another type usually included under the Genus Pentame¬
rus, which may be separated with advantage. This one is represented
by P.reversus (Billings), P.verneuili and P. interplicatus (Hall), etc.

GENERA PENTAMERUS, &c.

373

In these forms the relation of the valves, as in typical Pentamerus, is
reversed, and the interior structure presents other important differences.
For these I shall propose the name of Anastrophia.

There is still a farther separation required among the pentameroid forms, or an
extension of the characters of the genus. The Pentamerus occidentals of the Iowa
Geological Report presents externally a depressed dorsal valve, with a median
fold on the lower valve ; while there is a distinct area bordering the fissure, and
this area is vertically striated as in many of the Spirifers. The ventral valve has
the trough-like pit, formed by the junction of the lame life, greatly extended and
extremely incurved, and the dorsal lamellfe or crura are divergent and present
some peculiarities.

It is doubtless unsafe to base a distinction of genera upon external characters
alone, and even with a partial knowledge of the interior structure, we may be
misled ; but this group of shells presents itself to us under an aspect that will
admit of the following arrangement :

1. Pentamerus proper, having rotund or gibbous forms, with the ventral valve prominent
in the middle, and the dorsal valve flattened or depressed towards the front ; lamellae of
the dorsal valve distinct : P. knightii , P. galeatus, P. pseudo galeatus.

2. Elongate forms with the valves subequally convex, lobed or subsinuate ; internal struc¬
ture essentially as in P. Icnightii, and of which P. oblongus, P. lens ? are typical forms.

3. Forms ovate, more or less rotund, with a sinus on the ventral valve and a mesial fold
on the dorsal valve ; internal structure of the ventral valve as in P. knightii. Dorsal
valve with the crura or lamellae of the hinge-plate conjoined so as to form a separate
trough-shaped cavity, which unites with the inner surface of the valve ; a narrow area
on each side of the fissure, and a flattened space or false area along the cardinal margin
of the valve. P. aratus and P. papilionensis are of this type. Genus Pentamerella.

4. Forms more or less elongate, lobed or with mesial fold and sinus ; hinge with an exten¬
ded area on the ventral valve : internally a short \/- shaped pit in the ventral valve,
supported by a septum. In the dorsal valve, the crura are free almost or quite from
their origin (as in Spirifera), and forming no vertical lamellae. P. liratus and P. micro-
camerus are European forms of this type = the Genus Stricklandinia of Billings ;
of which S. canadensis, S. brevis, S. gaspensis and <S. anticostensis are characteristic forms.

5. Short gibbous or ventricose forms ; the ventral valve much the larger, with or without
mesial fold, a large fissure, and elongate much incurved trough-shaped pit. Dorsal valve
depressed in front : an area on both valves ; that of the ventral valve striate as in
Spirifera : lamellae of dorsal valve separate and diverging. Genus Gypidula, of
which P. occidentalis , P. Iceviusculus and P. obsolescens are types.

6. Rotund or gibbous forms, with the valves, as in ordinary Pentamerus, reversed. The
ventral valve is the smaller, gibbous in its upper part, depressed or sinuate below, with
the \J- shaped pit sessile for nearly its entire length ; a small flattened space on each
side of the fissure. The dorsal valve is ventricose, larger than the ventral, with promi-

374

PALAEONTOLOGY OF NEW-YORK.

nent umbo. The hinge-plate is extended in gradually converging vertical lamellae which
are joined to the shell throughout their length, while the crura are extended into the
cavity in thin free lamellae. Genus Anastropria,* of which Pentamerus verneuilii,
P. interplicata and P. reversus are types.

7. Forms elongate, not lobed. Yentral valve with connected dental lamellae, forming a
trough supported on a septum. Dorsal valve with free crura : no area. Shell-structure
punctate. Genus Amphigenia : Type Pentamerus elongatus ( Vanuxem ) = A.
elongata.

These modifications of a type, of which, until recently, but two genera have
been recognized, are well marked in nature, and they seem to me to demand some
farther recognition than that of subordination to the Family Rhynchonellid.®. I
shall therefore propose the Family Pentameridve to include the genera above
enumerated, as well as the Genus Camarophoria, and probably Triplesia and
some of the species of Camarella,! and perhaps also the Genus Gypidia of Dal-
majt, making G. conchydium the type.! In this arrangement, it appears to me that
we have a well-marked family of Brachiopoda which has existed from the earliest
palaeozoic^ epoch, and has continued throughout the entire series to its close.

* I am aware that Mr. Shaler, of the Museum of Comparative Zoology at Cambridge, in a Bulle¬
tin of that Institution, has proposed the name Brachymerus for these forms ; hut since that name is
preoccupied for a genus of Coleoptera, it cannot be adopted in this relation; and my own determi¬
nation of the generic distinction of these forms having been made long since, I shall adopt the name
proposed above.

t I cannot recognize the rhynchonelloid typical species of Camarella as congeneric with many of
those more recently placed under that genus by its author.

J In the revision of the Pentameridve, I am by no means sure that the Genus Gypidia will not he
recognized. I have under consideration at the present time an American species of similar external
character, presenting certain modifications of the hinge-plate in the dorsal valve, which will require a
distinct designation.

GENUS PENTAMERUS.

873

GENUS PENTAMERUS (Sowerby),

Types P. knigktii, P. galeatus, etc.

GENUS PeNTAMERELLA (nov. gen.).

Type P. arata.

Pentamerella arata.

PLATE LYIII.

Atrypa ■ arata : Conrad, Ann. Report on the Palaeontology of New-York, page 55. 1841.

“ octocostata : Id. Ib.

Pentamerus aratus : Hall, Tenth Report on the State Cabinet, p. 120. 185T.

Shell ovate, more or less convex or gibbous, becoming arcuate-ovoid in
old shells ; the width greater or less than the length : hinge-line
variable.

Ventral valve gibbous and somewhat regularly convex in the young
shells, becoming ventricose in old shells, with a mesial sinus which is
more or less developed. In old shells, the form is extremely arcuate
and the beak strongly incurved ; in shells of medium size, the beak
is obtuse, limiting the apex of the triangular fissure. There is. a nar¬
row area bordering the fissure and the space, on either side, between
the hinge-line and its apex, is often flattened, and sometimes distinctly
limited by a faint elevation : fissure large, and nearly covered by the
beak of the opposite valve.

Dorsal valve, in young shells, more or less convex, and sometimes gib¬
bous in the upper part, and often only moderately convex in older
shells ; mesial fold usually well defined in the lower half of the valve,
sometimes reaching nearly to the apex : in young shells there is
rarely a short sinus in place of the mesial elevation.

Surface plicated by rounded or angular plications, which sometimes
reach nearly or quite to the beak, but are often only developed below

S76

PALAEONTOLOGY OF NEW- YORK.

the first third of the length : plications usually bifurcated ; the bifur¬
cations irregular or unequal.

The interior of the ventral valve has an elongate spoon-shaped pit,
the inner extremity of which is free for a considerable extent, and the
upper part supported on a central septum which usually extends less^-
than half the length of the shell from the apex.

In the dorsal valve, the crura or lamellae are conjoined at their bases,
making a V" shaped trough or pit, which is attached to the valve in its
upper part and continues sessile for about one-half the length of the
shell.

This species, in its Ararious phases of growth and development, presents much
variety of aspect' and form. In some extreme specimens, it approaches to the form
of P. knightii, but its prevailing proportions and characters are extremely dif.
ferent. In young shells the form is sometimes not unlike that of Rhtnchonella ;
but the greater gibbosity of the ventral valve and the bifurcation of the plications
offer ready means of distinction. In some of its forms it approaches in character
the Pentamerelia joapilionensis of the Hamilton group ; but the surface is usually
marked by a greater number of plications, which are usually more or less angular.

I have heretofore (Report on State Cabinet, ut cit.) identified the Atrypa arata
and A. octocostata of Conrad as different phases of this shell, and farther exami¬
nation has confirmed this opinion. With a few specimens, each of which might be
a typical form, it is not difficult to recognize three tolerably distinct varieties of
this species ; but with a larger number of specimens, they are all shown to belong
to the same type, and do not offer the means of specific distinction.

This species, in the collection before me, ranges from half an inch in length
and breadth to specimens having a length of two inches or mor.e, Avith a width of
an inch and a half.

Geological formations and localities. This fossil occurs in the Schoharie grit,
aud in limestones of the Upper Helderberg group, in Albany and Schoharie
counties, New-York. It occurs in the same limestone in Cherry valley, at
Waterville and Babcock’s hill in Oneida county, at Lima in Ontario county, at
Caledonia in Livingston county, and Leroy and Stafford in Genesee county ; and
at Clarence holloAv, and five miles east of Buffalo, in Erie county. It is known in
Canada West, and at the Falls of the Ohio.

PENTAMERIDiE OF THE HAMILTON GROUP.

377

Peiitaiuerella papiBionensis.

PLATE LVIII.

Pentamerus papilionensis : Hall, Geol. Rep. Iowa, Vol. i, part ii, cited p. 514. 1858.

“ *< Idem, Thirteenth Report on the State Cabinet, p. 86. 1860.

Shell ventricose, broadly ovate, often wider than long, more or less gib¬
bous and arcuate in old shells.

Ventral valve gibbous or ventricose above, becoming depressed in the
middle into a broad shallow, often undefined sinus, which scarcely
reaches to the beak and sometimes not much above the middle, and is
produced in front ; sides abruptly curving to the margin : beak
incurved, obtuse, arching from the broad fissure ; cardinal line exten¬
ding for more than half the width of the shell. The space above, on
each side of the fissure, is concave and wrinkled.

Dorsal valve gibbous in the middle, somewhat regularly curving to the
sides and front ; mesial fold defined below the middle of the valve.
Surface plicated, the plications rounded or subangular, becoming obso¬
lete towards the beak, and. prominent below the middle : of these there
are two or three in the mesial sinus, and usually about four on the mesial
fold, with three, four or five on either side. The plications are crossed
by fine concentric striae of growth, which at irregular intervals are
crowded into squamose imbricating lines. The entire surface is finely
papillose or punctate, and when well-preserved might be mistaken
for a punctate shell. The substance of the shell is lamellose-prismatic
and brittle.

The interior of the ventral valve shows a broad short and deep spoon¬
shaped pit, the extremity of which isrjeent abruptly to the dorsal side.
The -septum supporting the conjoined lamellae extends from one-third to
one-half the length of the valve, and in some examples may extend
still farther towards the anterior margin.

The interior of the dorsal valve is not fully known.

[ Palaeontology IV.] 48

378

PALAEONTOLOGY OF NEW- YORK.

This species bears much resemblance to P. arata, in some phases of the latter
but the plications are usually less numerous, rounded and simple, and the shell
is more regularly ovate, and never so large and extremely arcuate as in that
species.

The specimens are for the most part in a crushed and distorted condition ; and
among a hundred individuals, there is not one preserved in its perfect form.

This species resembles P. occidentalis ( = Gyjn'dula occidentalis of Iowa) in
general form ; but the plications are more numerous, and extend farther towards
the beak, which is more arcuate and less obtuse ; and the ventral valve is' marked
by a mesial elevation instead of a sinus.

Geological formation and localities. This species occurs in the shales of the
Hamilton group on the shores of Seneca and Canandaigua lakes, at Geneseo,
York and Moscow, Livingston county ; at Eavilion in Genesee county, and else¬
where in 'Western New- York.

Peiitamerella micula (n. s.).

PLATE LYIII.

Dorsal valve subcircular or transverse, regularly convex. Surface,
towards the beak, smooth or marked only by concentric lines of
growth ; the lower part of the shell marked by fifteen to twenty short
rounded or subangular plications, of which five or six in the middle
are slightly more elevated, giving indication of a mesial elevation.
Interior of the valve with the lamellae converging from their origin,
and forming a pointed sessile trough, which is contracted where
embraced by the teeth of the opposite valve, and expanded near the
hinge-line. There is a short low septum just within the apex of the
pit, with apparently a narrow area on each side of the fissure.

Two specimens of this form, from rocks of the age of the Hamilton group near
Iowa city, were received several years since : and the character of the trough or
pit in the dorsal valve induced me to regard them as belonging to a distinct
genus, but the insufficiency of the material has caused them to be neglected until
the present time. The pit is more shallow and expanded than that of P. grata.

PENTAMERIDiE OF THE HAMILTON GROUP.

379

Pentamerella ©bsolescens (n. s.).

PLATE LYIII.

Shell small, gibbous or ventricose, about as wide as long.

Ventral valve ventricose above the middle ; umbo prominent : beak
abruptly incurved over a large triangular fissure, with the shell flat¬
tened along the cardinal margin.

Dorsal valve regularly convex below, gibbous above : beak prominent,
scarcely incurved, with an apparent narrow area on each side the
fissure.

Surface smooth, or with nearly obsolete radiating folds.

Interior of ventral valve with a pit or trough supported on a short
septum ; and in the dorsal valve there is a short sessile trough made by
the converging lamellae, which reaches to about the middle of the length
of the valve.

Geological formation and locality. In shale of Devonian age : Waterloo, Iowa.
Received from Mr. O. St. John.

Pentamerella dubia.

PLATE LYIII.

Spirifer dubius : Hall, Thirteenth Report oh the State Cabinet, p.90. 1860.

Shell ovoid, ventricose ; cardinal extremities rounded ; length and width
sometimes equal, the length in young shells greater than the width :
depth of the two valves equal to two-thirds the width.

Ventral valve gibbous or ventricose, extremely arcuate, with a flattening
or subsinuation and extension of the front : umbo prominent, and
extended beyond that of the opposite valve one-fifth or more of its
length ; apex strongly incurved.

Dorsal valve gibbous, much shorter than the ventral, prominent in the
.middle above, with a more or less defined mesial fold towards the
anterior margin, which is marked by four or five plications which
coalesce and become obsolete before reaching the apex.

Surface marked by from fourteen to twenty or more plications which
show a tendency to bifurcate near the margin, and in old shells are
entirely obsolete on the upper part of the valves : plications crossed
by imbricating lamellae.

Geological formation and locality. This species occurs in rocks of the age of
the Hamilton group near Iowa city Iowa.

380

PALAEONTOLOGY OF NEW-YORK.

Genus Gypidula (n.g.).

[ Gr. yvip, vultur ; in allusion to the strongly incurved beak.]

Generic characters as given on page 373 of this volume.

Type G. occidentalis.

Gypidula occidentalis.

PLATE LVIII.

Pentamerus occidentalis : Hall, Geology of Iowa, Vol. i, part ii, pa. 514, pi. vi, f. 2. 1858.

Not “ “ Idem, Pal. New-York, Vol. ii, p. 341. 1852.

Shell subovoid, gibbous, very inequivalve ; hinge-line equalling three-
fourths the entire width of the shell.

Ventral valve arcuate, gibbous or ventricose in the upper part ; beak
extended, strongly incurved, obtuse ; fissure large and bordered by a
distinct area which is vertically striated. The spoon-shaped pit is
deep, extremely extended ‘and incurved. The middle of the valve,
below the first third, elevated into a more or less distinot mesial fold
which is marked by two or three plications.

Dorsal valve gibbous above, becoming flattened below the middle, some¬
times concave at the sides, and the front depressed into a deep and
more or less distinctly defined sinus. A narrow area extends for about
two-thirds the length of the hinge-line.

Surface plicated below by a few rounded or subangular plications which
become obsolete above ; the upper part of the valve marked only by
concentric striae.

Geological formation and locality. In strata of the age of the Hamilton group,
at Independence, Iowa.

PENTAMERIDiE OF LOWER DEVONIAN AGE.

381

Gypidula lieviiisciila (n. s.).

PLATE LVIII.

Shell varying from subcircular to broadly ovoid, gibbous in the young
state, becoming ventricose.

Ventral valve, in the young shell, regularly convex, with beak abruptly
pointed and neatly incurved, becoming more gibbous or ventricose as
the shell increases in size, with the umbo prominent and beak arcuate ;
regularly curving to the sides and front, without mesial sinus or
elevation.

Dorsal valve regularly convex in young shells ; old shells more gibbous
above, and becoming broadly depressed towards the front, without
distinct sinus. Area distinct ; beak scarcely incurved.

Surface smooth or marked by concentric striae, which are slightly undu¬
lated towards the front of the shell ; and in a large specimen, the
exfoliated surface is obscurely marked by fine striae.

The young specimens of this species have much the aspect of Nucleo-
spira ; but when the cardinal line is visible, there is a conspicuous trian¬
gular fissure with a flattened space on each side. This feature is
sometimes quite marked in the separated ventral valve. The spoon¬
shaped pit is comparatively wide and deep, and supported on a short
septum. In the dorsal valve the lamellae are divergent from their origin.

The largest specimen before me has a length of seven-eighths of an
inch, with a slightly greater width.

Geological formation and locality. Collected from strata of Devonian age, at
Waterloo, Iowa, by Mr. O. St. John, to whom I am indebted for the specimens.

PALAEONTOLOGY OF NEW-YOEK.

Genus Amphigenia (nov. gen.).

[ Gr. afx<pi, utrinque ; and yevea, generation

Shells inequivalved, oval, ovoid or subtriangular, more or less convex
or gibbous, without mesial fold or sinus. Valves articulating by teeth
and sockets, without area. The dental lamellae in the ventral valve
conjoined on their dorsal sides, forming an angular trough or pit,
which opens exteriorly by a triangular fissure beneath the beak, and
in its anterior extension is supported on a central septum. Dorsal
valve with a strong thickened cardinal process or hinge-plate, bor¬
dered by the teeth sockets, anchylosed to the bottom of the valve and
supporting the crura, which extend into the cavity of the shell.* * * *

In all the specimens examined, there is a foramen extending beneath
the hinge-plate, and ending in a perforation at the beak. The shell sub¬
stance is distinctly punctate, and, in exfoliated specimens, presents a
prisnmtic structure. So far as known, the crura terminate in slender
extensions, without appendage of any kind ; but we have had no speci¬
mens in a condition to enable us to ascertain their entire character.

The type of this genus, T. elongata, has been placed by Mr. Billings
under ihe Genus •Stricklandia = Stricklandinia, from which I regard it
as differing in having no area on the ventral valve, a more extended
angular pit, a very different hinge-plate, with a foramen in the dorsal
valve, and a punctate shell-structure.

The shells of this genus were referred by me to the Genus Rensselasria, for
reasons already mentioned. They differ from that genus in the angular pit or
trough made by the conjoined dental lamelke of the ventral valve, and (with our

* The following remarks upon the dorsal valve of Rensseiaeria ( Pal. New-York, Vol. iii, pp. 454
and 455) are precisely applicable to the dorsal valve of Amphigeria : “ In the dorsal valve, the dental

“ sockets lie between the shell proper and a strong, often much, thickened process, from the anterior

“ extension of which proceed the slender crural processes.” *****
“ The cardinal process at the base of the crura is often much thickened, and sometimes extends for-

“ ward into the shell much more than in others ; and, when it becomes thickened in old shells, is
“ often distinctly marked by two grooves upon its summit. Behind this process, and between it and
“• the beak, there is a distinct round foramen communicating beneath with the interior cavity of the

“ valve.”

GENUS AMPHIGENIA.

083

present knowledge) in the free crura of the dorsal valve without apparent appen¬
dage. The muscular impression in the dorsal valve is precisely alike in the two
genera, and the shell is punctate and externally striate in precisely the same
manner. Rensseljeria belongs to the Family Terebratulidee ; while Pentamerus
and Stricklandinia are of the Family Rhynchonellidse = Pentameridae, as usually
understood. The Genus Amphigenia, in its punctate shell and modification of the
hinge in the dorsal valve, offers absolute affinities with 'Rensselairia, while in
other features it presents characters intermediate between the Pentameridse and
Terebratulidae.

Ampfliigenia elongata.

PLATE LIX.

Pentamerus elongatus : Yanuxem, Report Third Geol. Dist. New-York, p. 132. 1842.

“ “ Geol. Report Fourth Dist. New-York, p. 34. 1848.

Meganteris elongatus : Hall, Tenth Report on the State Cabinet, p. 123. 1857.

Rensselceria elongata : Id. Pal. New-York, Vol. iii, p. 453.

“ « “ Twelfth Report on the State Cabinet, p. 37. 1859.

Stricklandia elongata : Billings, Canadian Journal, No. xxxiii, p. 268. Mav, 1861.

“ “ Id. Geology of Canada, p. 371.

Shell elongate-oval or ovate, subcylindrical, more or less convex or
gibbous, variable in form, sometimes nearly as wide as long ; the
sides curving or nearly straight ; front rounded or subtruncate.
Ventral valve usually the more convex, often abruptly elevated or
obtusely subangular along the middle ; umbo prominent : beak
abruptly attenuate and closely incurved over the umbo of the oppo¬
site valve.

Dorsal valve more or less convex or sometimes gibbous in the upper
part, often more prominent or subangularly elevated along the middle
of the upper part, and depressed-convex towards the sides and on the
lower part, without evidence of mesial fold or sinus.

Surface covered by regular radiating flattened striae, with fine concen¬
tric lines which are often crowded into squamose imbricating ridges
of growth. When partially exfoliated, the radiating striae are only
obscurely or not at all visible, and the concentric striae appear to be
the external markings of the surface. Entire shell-structure punctate.
This fossil is extremely variable in form ; in the young state it is
often as wide as long or wider, the hinge-line extended, and the greatest

384

PALAEONTOLOGY OF NEW-YORK.

width a little below the hinge, rapidly narrowing to the front. Other
specimens of similar age are broadly ovate or oval, the dorsal valve
depressed-convex. As the shell becomes older, the convexity increases ;
though we meet with specimens of an inch and a half in length and
width, where the depth of the two valves is but three-fourths of an inch ;
and in one- specimen of a dorsal valve three inches and a half long, the
depth has been but about five-eighths of an inch. In a very symmetrical
specimen of the ventral valve about three inches long, the width is half
as great, and the depth five-eighths of an inch.

This shell sometimes reaches a length of nearly four inches ; though the pre¬
vailing size is from two and a half to three inches in length. It is frequently
crushed, and well-preserved, entire and symmeti’ical specimens are very rare.

A specimen from Michigan, received from Dr. C. Rominger, and one collected at
Mackinac from the same geological horizon, are strongly wrinkled concentrically,
but marked with similar radiating strias which are obscurely preserved.

The species described under the name Meganteris subtrigonalis ( Tenth Report
on the State Cabinet, page 123, 1857) appears to be only a variety of this spe¬
cies, and, if found of sufficient constancy, might be thus indicated.

Geological foi'mations ancl localities. This species occurs in the Schoharie grit,
where it is recognized by casts of the interiors of the valves. It is found in the
Upper Helderberg limestones at many localities between the Hudson and Niagara
rivers, and in Canada West. The principal localities from which I have specimens
before me, are Vienna, Ontario county ; Caledonia, Livingston county ; Clarence
hollow and Williamsville, Erie county. It occurs in Albany and Schoharie coun¬
ties, along the outcrop of the Upper Helderberg limestone, and at Cherry -valley,
Otsego county, and Bridgewater, Oneida county, New-York.

Aisiphigema elongata, var. umhiiata.

PLATE LIX.

✓

. Shell smaller than the preceding ; ventral valve very gibbous, and

marked by strong concentric undulations, and obscurely by fine radia¬
ting strite.

The specimens are apparently old shells and have a length of only
about an inch.

It is desirable to compare a larger number of individuals, before this form can
be entitled to specific distinction.

Geological formation and localities. In the Upper Helderberg limestone, at
Mackinac, and from Michigan : the latter received from Dr. C. Rceminger.

GENUS RENSSELiERIA.

385

CJMUS ReNSSELJGRIA* (Hall).

The following species possesses many of the important characteristics
of the Genus Renssel^iria, in the elongate-oval or subcylindrical form.
The punctate shell and the muscular impression of the dorsal valve
correspond with shells of that genus.

Reiisselseria ? johanni ( n. s.).

PLATE LX.

Shell oval or subovate, and, in full-grown individuals, elongate oval in
outline, or subcylindrical : valves subequally convex.

Ventral valve, in young specimens, more gibbous in the upper part, and
sloping to the front. In older shells the valve is regularly convex,
sometimes prominent or subangular along the middle ; the beak
closely incurved over that of the opposite valve.

Dorsal valve regularly convex ; in old shells, acquiring nearly the same
convexity as the ventral valve : in some specimens, much less con¬
vex, and extended on the hinge-line.

Surface marked by concentric striae of growth, which are at intervals
crowded into stronger ridges or imbricating folds. Shell-structure
punctate.

The cast of the dorsal valve shows muscular imprints similar to those of Rens-
SELiERiA ; while in the cast of the ventral valve, the filling of the rostral cavity
is less prominent.

In some young specimens, which appear to be of this species, the Valves are
only moderately convex, and there is an indication of area upon the dorsal valve.
' The materials in my possession are in such a condition as to prevent a satisfactory exami¬
nation of all the parts, and a positive reference of the species can only be made from an
examination of the internal structure. The form of the shell, incurvation of the ventral
valve, and general aspect are very similar to RENSSELiERIA ; but the characteristic radia-
. ting striae have not been observed upon the surface.

Should its interior structure prove it generically . distinct from that genus, I would propose
the name Rensselandia.

Geological formation and locality. In limestone of the age of the Upper Helderberg,
Waterloo, Iowa ; from Mr. 0. St. John.

# RexsselvEria, Hall : proposed and printed in Vol. iii, Palaeontology of New-York, 1858 ; pub¬
lished in Twelfth Report on the State Cabinet, p. 39. 1859.

4, [ Paleontology IV.] 49

386

PALAEONTOLOGY OF NEW- YORK.

Gems Terebratula (Llhwyd, 1696).

Among the fossils of the Up^er Helderberg and Hamilton groups,
several species present externally and internally the features of Tere¬
bratula. The shell-structure is punctate, the beak incurved and termi¬
nated by a round perforation, which is limited on the lower side by two
deltidial pieces. In other species of punctate structure, there is a certain
modification of muscular marking which has induced me to separate
them from Terebratula, under the name Cryptonella. With our present
knowledge of external forms and characters, it is not possible to distin¬
guish generically those with a short terebratuloid loop from such forms
as Centronella julia, without knowing their internal structure ; while
certain other forms, with flat or concave dorsal valve and punctate
structure, we regard as congeneric with C. glans-fagea. Unfortunately,
our specimens from the . Hamilton group, though numerous, are rarely
in q condition to show the loop or internal structure, and we are usually
forced to rely upon external form and the muscular impressions of the
casts.

In consequence of the finely punctate character and terebratuloid form
of these shells, I refer them, with little hesitation, to the Family Tere-
BRATULiDiE ; and while some of them are known to be true Terebratula:
from their internal structure, others are referred to that genus from simi¬
larity of external form and character. Among the following species placed
under this genus, four of theifi are known to possess the short terebratu¬
loid loop.

Terebratula lens.

PLATE LX.

Terebratula lens : Hall, Thirteenth Report on the State Cabinet, p. 89. 1860.

Shell ovate, broadly elliptical or lenticular below the beak, which is
abruptly tapering; moderately gibbous, the valves subequally convex,
the greatest width a little below the middle, the width about four-

TEREBRATULIDiE OF UPPER HELDERBERG LIMESTONE. 387

fifths as great as the length, and the depth nearly equal to half the
length.

Ventral valve a little less convex than the dorsal ; the beak moderately
incurved and broadly truncated by the foramen : no visible sinus or
elevation in the middle, of the valve.

Dorsal valve broadly elliptical or subcircular, somewhat regularly con¬
vex ; the beak closely aggressed below that of the opposite valve.
Surface marked by concentric lines of growth ; the shell-structure dis¬
tinctly punctate.

The length of an ordinary specimen is seven-tenths of an inch, the
width six-tenths of an inch.

I have continued this species under the Genus Terebratula, without having
any satisfactory evidence of its internal structure ; though it may hereafter prove
to belong to the Genus or Subgenus Cryptonella. This species is shorter, broader
and less gibbous than the T. (Cryjptonella) lindclceni, or the T. (O'.) rectirostra ;
and it is larger and less gibbous than the T. rcemingeri.

Geological formation and locality. This species occurs in the Corniferous lime¬
stone, at Clarence-hollow, Erie county, New-York.

Terebratula sullivanti (n.s.).

PLATE LX.

Shell elongate-ovate or subspatulate, truncate or emarginate in front,
of moderate convexity ; width and length about as four to six, or
seven to nine.

Ventral valve a little less convex than the opposite; the beak much
extended, neatly attenuate and perforate at the apex ; the cardinal
slopes rounded and a little concave near the hinge margin, usually
depressed towards the front, and sometimes a shallow sinus which
reaches one-third or one-half the length of the valve.

Dorsal valve a little more convex and considerably shorter than the
ventral valve, usually flattened and sometimes depressed along the
centre of the lower part of the valve.

388

PALAEONTOLOGY OF NEW-YORK.

Surface marked by fine close concentric striae which are neatly rounded
on well-preserved specimens, and at intervals are crowded into more
prominent ridges. Shell-structure punctate.

On cutting down a specimen of this species, it has been found to pos¬
sess a short simple loop, without appendage, as in Terebratula.

The larger specimens are about three-fourths of an inch in length.

The shell is readily dictinguished by its elongate form, moderate convexity,
truncate or sinuate front, and median depression in the ventral valve ; features,
which I have not observed in any other species in this geological formation.

Geological formation and localities. This species occurs in the Upper Helder-
berg limestone, at Columbus and Sandusky, Ohio ; and in the neighborhood of
Cayuga, Canada West.

Terebratula hanuonia (n. s.).

PLATE LX.

.Shell ovate or subspatulate, tapering somewhat abruptly to the beak,
convex in the middle and compressed at the margin^.

Ventral valve regularly arcuate from beak to front, moderately convex
in the middle, a little gibbous above and depressed-convex or slightly
concave towards the front, the upper part narrowing ; the beak much
extended, attenuate and arcuate, but not closely incurved ; apex per¬
forate, the slope to the cardinal margin scarcely concave : deltidial
plates large.

Dorsal valve moderately convex, sometimes a little more prominent
along the middle in the upper part, and depressed towards the front
and sides.

Surfa'CE marked by fine concentric lines of growth; the substance of
the shell finely punctate.

A well-marked specimen of this species has been cut down on the
dorsal side, revealing the loop, the divisions of which extend for more
than one-third the length of the dorsal valve ; the angle of return being
visible, but not the connecting portion.

TEREBRATULIDJE OE THE HAMILTON SHALES.

389

Young specimens, which I refer to this species, are more gibbous than
the older ones. The larger specimens are from six-eighths to seven-
eighths of an inch long and five-eighths of an inch wide.

This species is proportionally wider and with more extended beak than the
T. sullivanti, and more regularly arcuate from beak to base of the ventral valve :
it is, moreover, not emargiuate in front. It appears to be a well-marked species,
and, in its larger individuals, will be readily distinguished.

Geological formation and localities. From the limestone of the Falls of the
Ohio (sent to me by Dr. James Knapp of Louisville, Kentucky) ; and also from
the Corniferous limestone of Canada West : collected by Mr. De Cew.

Teretoratula rceiiiingeri.

PLATE LX.

Terebratula rczmingeri : Hall, Sixteenth Report on the State Cabinet, p. 48. 1863.

Shell ovate, more or less gibbous, truncate or slightly sinuate in front.
Ventral valve gibbous above the middle ; umbo gibbous, inflated ; beak
prominent, incurved over the opposite beak, and truncated by a round
foramen which is often mainly anterior to the apex, and completed
on the lower side by two deltidial plates : cardinal slopes rounded,
often depressed in the middle towards the front.

Dorsal valve extremely gibbous, little longer than wide ; the greatest
convexity at the middle or above.

Surface marked by fine concentric striae which are often crowded into
prominent wrinkles towards the front. Shell-structure finely punctate.
.The interior shows a short terebratuliform loop, which is abruptly
recurved at its lower extremities.

This species was first indicated from specimens sent by Dr. Rceminger, from
Thunder bay, Michigan ; but it has since proved of common occurrence in New.
York. The Michigan specimens are usually more gibbous and distinctly depressed
or sinuate in front ; while that character, though present in some of the eastern
specimens, is not constant. There is, however, no difficulty in recognizing the
characters of the species in any well-preserved specimens.

This species is the smallest of the genus, or of the family, known as occurring
in the Hamilton shales of New- York.

PALEONTOLOGY OF NEW-YORK.

Geological formation and localities. The original or type specimens of the spe¬
cies occur in beds of the age of the Hamilton group, at Thunder bay, Michigan.
It is found in the same horizon at York in Livingston county, and at Hamburgh
on the shore of Lake Erie. It has likewise been found at Waterloo, Iowa, by Mr.
E. P. Whitfield.

Terebratula elm (n.s.).

PLATE LX.

Shell ovate, arcuate on the ventral side ; beak prominent.

Ventral valve regularly arcuate from beak to base, gibbous in the mid¬
dle and above ; umbo prominent ; beak little incurved and broadly
truncate by a rounded foramen, which is limited on the lower side by
two large deltidial pieces.

Dorsal valve regularly convex, the greatest convexity in the middle,
where it is about equal to that of the opposite valve. The depth, width
and length are as two, three and four-eighths of an inch.

Surface concentrically striate, shell-substance punctate.

Geological formation and locality. This species occurs at Waterloo, Iowa, in
strata of the age of the Upper Helderberg or Hamilton group. Eeceived from Mr.
O. St. John.

Terebratula jucumla (n.s.).

PLATE LX.

Shell subcircular or very broadly ovate, the length and width about
equal, regularly rounded below and abruptly narrowing above the
middle.

Ventral valve gibbous in the middle, curving regularly to the base and
baso-lateral margins : beak obtuse, and incurved over the umbo of
the opposite valve ; apex truncated by a rounded foramen.

Dorsal valve rather regularly convex, the greatest convexity a little
above the middle, curving to the base and baso-lateral margins.
Length of specimens, a little more than three-eighths of an inch.

On cutting down from the dorsal side, the loop is visible, showing the
terebratuloid character.

TEREBRATULIDiE OF THE HAMILTON GROUP.

391

Geological formation and locality. In strata of the age of the Upper Heidel¬
berg or Hamilton group, at Waterloo, Iowa. Received from Mr. 0. St. John.

Tereliratula iiaviceila (n. s.).

PLATE LX.

Shell elliptical, subnaviform, arcuate on the ventral side, slightly lingui-
form in front.

Ventral valve extremely arcuate, flattened or subsinuate towards the
front, depressed convex in the middle, and a little prominent on the
umbo : beak extended, recurved and truncated by a rounded fora¬
men almost in the plane of the longitudinal axis; deltidial pieces
conspicuous.

Dorsal valve prominent along the middle, nearly straight from the base
to the umbo, sloping somewhat abruptly to the sides.

Surface marked by fine concentric striae which are sometimes crowded
into stronger ridges. Structure distinctly punctate.

On cutting down the dorsal side, there are some obscure indications
of short crura which are not united below; but this is a common condi¬
tion, the connecting portion of the loop having often been broken away..

Geological formation and locality. This species occurs at Rockford, Iowa, in
beds of the age of the Hamilton or Chemung group of New-York. Received from
Mr. O. St. John, and collected at the same place by Mr. R. P. Whitfield.

Tereforatula simulator (n. s.).

PLATE LX.

Shell elongate-ovate or spatulate, moderately convex ; the beak of the
ventral valve much extended, and truncated almost rectangularly to
the longitudinal plane.

A specimen received from Dr. Rceminger, collected in the Hamilton
group at Widder, Canada West, shows the crura extending for about
half the length of the dorsal valve ; but the connecting portion of the
loop is not preserved.

%Q2

PALAEONTOLOGY OF NEW-YORK.

(*ENUS CrYPTONEHA (Hall, 1861).

Ceyptonella : Hale, Fourteenth Report on the State Cabinet, p. 102. 1861.

“ Id. Fifteenth “ •< «< pp. 132 & 133. 1862'.

“ « Sixteenth “ <« <« p. 43. 1863.

Shells equilateral, inequivalve, elongate, oval or ovoid ; valves unequally
convex, without median fold or sinus, or with this character moderately
developed and principally towards the base of the shell. Ventral valve
with beak extended or incurved, perforate ; foramen terminal, the
lower side formed by two- small triangular deltidial pieces, or, in their
absence, by the umbo of the opposite valve. Shell-structure finely
punctate. Surface smooth, or with concentric striae. Valves articula¬
ting by teeth and sockets, the dental lamellae of the' ventral valve
extending downwards into the cavity of the shell. The muscular
impressions in the dorsal valve are strongly marked above, and extend
in two narrow separated impressions more than halfway to the front
of the shell : the ventral cast shows elongated muscular and vascular
impressions.

The species of this genus are more elongate than Merista and Meri-
stella, and those now known are less distinctly marked by mesial fold
and sinus ; while the beak is more attenuate, often a little flattened, and
rarely so closely incurved, as in the genera cited. The punctate structure
of the shell is a distinguishing character.

This genus was first described as above cited, and figures of the exte¬
rior form and of the interior of the valves were given in the Fifteenth
Report. The results of some farther investigations were given in the
Sixteenth Report, and an illustration of what was supposed to be the
internal appendages of the shell. About the same time it was discovered
that some punctate shells of the same general form possessed the loop of
Terebratula proper ; and it became a matter of great interest, and still
greater difficulty, to determine the internal structure of the species. I
had referred to this genus the Terebratula lens, T. lincklmni, T. reciirostra

GENUS CRYPTONELLA.

393

and T. planirostra, species described in a preceding report. Having ascer¬
tained that the internal loop in Centronella glans-fagea is essentially simi¬
lar to that of C. julia (Winchell), a species having the external form of
Cryptonella, I supposed it possible that the two genera might be merged
into one. Since that time, I am not aware that any farther investigations
have been made, tending to throw light upon this subject.

It has therefore appeared to me very desirable to learn, if possible,
the internal structure of any one of those species which I originally
referred to the Genus Cryptonella. Of two of these, C. rectirostra and
C. planirostra, I have fortunately been able to obtain an exposition of
the form and structure of the loop, as will be shown in the illustrations
of the species.

The crura have the general form of those in Waldheimia, extending
\n a long recurved loop, with long processes descending into the ventral
valve, between which and the apex the crura are united by a trans¬
verse band, differing in this respect from that genus, while the muscular
impression and .extended beak offer other distinctions.

I have thought it desirable, therefore, to continue the name Crypto¬
nella to include these two authentic species ; while the other species
are included under it from their general form.

I have continued the Terebratula lens under that genus, without knowing
its internal structure, but from its external similarity with those which
have proved to belong to that genus.

These investigations have clearly shown how difficult, or even impos¬
sible, it is to refer to their proper generic relations these fossils from
external form and character alone.

[ Paleontology IV.]

50

394

PALAEONTOLOGY OF NEW-YORK.

Cryptonella rectirostra.

PLATE LXI.

Terebratula rectirostra : Hall, Thirteenth Report on the State Cabinet,, p. 88. 1860.

“ “ Id. Referred to Cryptonella in Fourteenth Report, p. 101. 1861.

Cryptonella rectirostra : Id. Sixteenth Report on the State Cabinet, p. 44. 1863.

Shell elongate-ovate, subovate or elliptical ; the greatest width anterior
to the middle : valves subequally convex, rounded or subtruncate at
the base.

Ventral valve regularly arcuate, most convex in the middle, sometimes
a little flattened at the base : beak much extended beyond the oppo¬
site valve, moderately incurved and truncated by a round foramen,
which is completed on the lower side by two narrow deltidial pieces.
Shell abruptly inflected from the umbonal slopes to the cardinal
margin.

Dorsal valve scarcely more convex than the opposite, gibbous towards
the umbo, and regularly curving to the base and baso-lateral margins ;
beak closely incurved beneath the deltidial plates of the opposite
valve.

Surface marked by fine concentric lines of growth, and often at some
what regular intervals by imbricating lamellae. Structure finely
punctate.

In the dorsal valve, the muscular impressions are narrow and elon¬
gate ; and in the ventral valve the teeth are strong, and the muscular
imprint elongate, with strong vascular markings extending nearly to the
base of the shell. The crura are extended below the middle of the length
of the shell and then abruptly recurved, reaching backwards more than
half way to the apex : the crural processes penetrate deeply into the
ventral cavity, and between these and their origin the crura are connec¬
ted by a transverse band.

This species varies from individuals of less than half an inch in length
to those of nearly an inch and a half. In the older shells, and sometimes
in the younger ones, the lamellose concentric lines are very conspicuous.

CRYPTONELLA OF THE HAMILTON GROUP.

395

Geological formation and localities. This species occurs in the Hamilton group,
at Bellona in Yates county; on the shore of Canandaigua lake ; at York, Moscow
and Geneseo in Livingston county ; at Hamburgh on the shore of Lake Erie, and
elsewhere in Western New-York.

Cryptonella planirostra.

PLATE LXI.

Terebratula planirostra : Halt., Thirteenth Report on the State Cabinet, p. 89. 1860.

« “ Id. Referred to Cryptonella in Fourteenth Report, p. 101. 1861.

Cryptonella planirostra t Id. Sixteenth Report on the State Cabinet, p. 44. 1863.

Shell subovate or elliptical ; the front often truncate, giving a subpenta¬
gonal outline ; the greatest width near the middle of the shell ; the
length and width about as six to seven or eight. The depth of the two
valves, in well-formed specimens, is about equal to half the length.
Ventral valve in old shells gibbous, the greatest convexity above the
middle, often slightly flattened towards the beak, which is moderately
incurved and truncate by a round foramen, limited below by conspi¬
cuous deltidial pieces, abruptly inflected along the umbonal slope,
often leaving an angular ridge, and the space between it and the hinge-
margin flat or concave ; often slightly flattened below the middle, and
regularly curving to the sides.

Dorsal valve considerably shorter than the opposite, more convex or
gibbous, the greatest convexity at or a little above the centre, curving
to the sides and front where it is sometimes flattened : beak incur¬
ving beneath the deltidial plates of the opposite valve.

Surface marked by fine rounded concentric striae, which in old shells
are disposed in broader belts of imbricating lamellae. Shell-structure
punctate.

The crura reach below the middle of the length of the shell,
approaching each other very closely, and abruptly recurved for a dis¬
tance about half their length : they are united near their bases by a
transverse band.

S9©

PALAEONTOLOGY OP NEW-YORK.

The larger well-marked individuals have a length of. about one inch;
and a single specimen, apparently of this species, is nearly two inches
long.

In the young or half-grown shells, the valves are moderately convex
and the beak scarcely incurved, while there is no perceptible truncation
in front. The flattening of the umbo and umbonal slopes are not con¬
stant characters, and we have regularly ovate forms with every part
limited by curved lines.

I have received from Dr. G. A. Williams, formerly of Hardy county, Virginia,
several casts of a species of this genus, which I have referred to this. One of
those figured upon the plate is proportionally more elongate than the New-York
forms ; but the shell has been abruptly incurved on the umbonal slopes, flattened
on the lower part of the ventral valve, and obliquely subtruncate in front.

Geological formation and localities. This species occurs in the Hamilton group
on the shores of Seneca and Canandaigua lakes, at Moscow; York and Geneseo in
Livingston county, and at Pavilion in Genesee county, New-York.

Cryptonella iphis (n. s.).

PLATE LXI.

Shell elongate, subcylindrical.

Ventral valve more convex than the dorsal, regularly arcuate from beak
to base, the greatest convexity about the middle of its length, abruptly
rounded or subtruncate in front. Beak much extended beyond that of
the opposite valve, and slightly arcuate.

Dorsal valve somewhat depressed-convex in the middle, and shortly
' curving to the margins ; the upper two-thirds of the length of the
valve almost equally convex.

Surface concentrically striated, with a few strong undulations towards
the front, in the cast. Shell-structure punctate.

Length one inch ; width less than three-fourths of an inch.

The specimen is almost an entire cast, and is referred to the Genus Crypto¬
nella from the elongate form, moderately incurved beak, and character of mus¬
cular impressions. The punctate structure of the shell indicates its position among
the Terebratulidee.

Geological formation and locality. This shell occurs in the Corniferous lime¬
stone, near Cayuga in Canada West.

CRYPTONELLA OE THE HAMILTON GROUP.

S© 7

Cryptonella ? lincklseni.

PLATE LX.

Terebratula lincklceni Hall, Thirteenth Report on the State Cabinet, p. 88. 1860.

«< << Idem, referred to Cryptonella ; Fourteenth Report on the State Cabinet,

p.101. 1861.

Cryptonella lincklceni : Idem, Sixteenth Report on the State Cabinet, p. 44. 1863.

Shell ovate or subelliptical, usually broader below the middle, varying
from moderately convex to very gibbous and sometimes subcylindri-
cal ; front rounded, subtruncate, or a little depressed.

Ventral valve varying from moderately convex to gibbous, somewhat
regularly arcuate in longitudinal outline, sometimes a little flattened
towards the front or marked by a narrow mesial depression. Beak
more or less abruptly incurved, and truncate by a foramen of mode¬
rate size : umbonal slopes rounded or subangular, and concave towards
the cardinal margin.

Dorsal valve varying from moderately convex to gibbous ; the greatest
convexity about the middle of the length, and thence curving regu¬
larly to the sides and base.

Surface marked by fine concentric striae of growth, which are some¬
times crowded together towards the front, causing a thickening of the
shell. Shell-structure distinctly punctate.

The internal structure has not been determined, and I therefore refer
it with doubt to the Genus Cryptonella.

This species presents some variety of form, from subelliptical to
broad-ovate. The length of a large individual is a little more than three-
fourths of an inch, with a width of five-eighths of an inch and a depth
of three-eighths ;. while another form, which I refer to the same, has a
length and width of half an inch, with a depth of a little more than
a quarter of an inch. Some of the smaller individuals are a little more
than a quarter of an inch in length.

This species is common in certain beds ; and for the most part is readily recog.
nized. In the less gibbous speeimens, it resembles the O. jplamrostra, ■ but the beak
is more incurved, and , there is less angularity of the umbonal slope, while the
outline is more regularly rounded. In a crushed and distorted condition, it is not
readily distinguished from C. rectirostra.

398

PALAEONTOLOGY OF NEW-YORK.

Geological formation and localities'* This species occurs in the Hamilton group
at Burchard’s quarry near Hamilton in Madison county, and is of frequent occur¬
rence at Delphi falls in Onondaga county, and near Kelloggsville in Cayuga county,
whence I have formerly received it from Prof. Hopkins of Auburn. It is also found
in some other localities, and a single specimen from Thunder bay in Michigan is
of this or a closely allied species.

Cryptonella (Terebratula) eudora (n.s.).

PLATE LXI.

Shell broadly ovate, rounded in front ; apex obtuse.

Ventral valve gibbous in the central and upper part, moderately convex
in the lower part, and sometimes flattened towards the front ; tapering
abruptly to the beak, which is obtuse, little extended beyond the
opposite valve, slightly incurved, and truncated by a rounded foramen.
Dorsal valve depressed-convex, often gibbous in the middle above ; beak
incurved into the cavity below the deltidial plates.

Surface concentrically striate, with crowded lamelliform ridges towards
the sides and front. Shell-structure punctate.

The prevailing length is from one inch to nearly an inch and a half ;
the width, from three-fourths of an inch to an inch and a quarter. The
separated dorsal valves are often of equal length and width.

This species is proportionally broader than the prevailing forms in the Hamil¬
ton group, though varying little from some specimens of the C. jplanirostra,
which has a more extended beak and flattened cardinal slopes.

Geological formation and localities. This species occurs in some dark argilla¬
ceous sandstones in the Chemung group, near Ithaca, whence most of the speci¬
mens have been received. It is found also at Chemurig-narrows, Chemung county,
New-York. Specimens of similar form and proportions occur in the Waverly
sandstone of lacking county, Ohio ; and a specimen collected by Mr. Whitfield
at Bockford, Iowa, has essentially the same form and proportions.

Collections made near Ithaca, while these pages are going through the press,,
show the species to be comparatively abundant in some calcareo-arenaceous beds,
which, in their weathered decomposing portions, have left the casts of the
interior.

GENUS CENTRONELLA.

399

Genus CENTRONELLA (Billings, 1859).

Recognizing the Genus Centronella as founded on C. glans-fagea, and
taking the illustrations of the interior as given in the Sixteenth Report
on the State Cabinet, p. 47, as the true representation of the loop, we feel
warranted in uniting two or three other forms in the same generic rela¬
tion, from the general similarity of form, and compact shell substance,
which is finely punctate. With our present knowledge, the genus begins
its existence in the Schoharie grit, and is known in the Upper Helder-
berg limestone and in the Hamilton and Chemung groups. It is not
improbable that the genus may have a greater vertical range, and that if
will be found among the terebratuloid forms of the Carboniferous period.
The characteristic species, known in New-York, have the dorsal valve
flattened or concave; but th e C.julia of Winchell has an oval form and
convex dorsal valve, giving no indication, from these features, of its
generic relations.

Centronella glans-fagea.

PLATE LXI.

Rhynchonella glans-fagea : Hall. Tenth Report on the State Cabinet, p. 125. 1857.

Centronella glans-fagea : Billings, Canadian Naturalist and Geologist, pp. 131 & 132. April 1859.

« “ Hall, Sixteenth Report on the State Cabinet. 1863.

( The species illustrated and discussed on pages 45, 46 and 47.)

Shell small, broad-ovate or subquadrate ; the sides often sloping from
near the middle to the apex at an angle of about 85° ; the front roun¬
ded ; the valves very unequal.

Ventral valve much larger than the dorsal, very prominent, often sub-
carinate along the middle and curving very abruptly to the lateral
margins, regularly arcuate from beak to base. Beak much extended
beyond that of the opposite valve, strongly incurved, bringing the
apex above the plane of the margin of the dorsal valve.

4©©

PALAEONTOLOGY OF NEW-YORK.

Doesal valve usually convex in the upper part, concave in the middle
by a broad undefined sinus, which, towards the front, often involves
the entire width of the valve : beak not incurved.

Sukface smooth, or with faint concentric lines of growth : shell com¬
pact and very finely punctate. The shell varies from three-tenths to
four-tenths of an inch in length ; the width usually more than three-
fourths as much, and sometimes nearly equal to the length.

The interior of the ventral valve shows two strong teeth, at some
distance below the apex, with strong dental lamellae. The interior of
the dorsal valve shows the bases of the crura to be very thick and
strong, entirely divided at the centre, and each supporting a thin fila¬
ment, which becomes-broader below and sends off a spur into the ventral
Cavity; and thence curving inwards, the outer margins are united and
produced along the line of junction in a slender elevated carina, which
extends forward in a slender free point. The muscular imprint is oval,
and divided along the centre.

The casts of the interior preserve the impressions of the feature's
described, and are readily recognized by the slender incurved filling of
the rostral cavity.

This species presents considerable variety in its form and proportions. The
dorsal valve is often gibbous in its upper part, with or without a median sinus,
which becomes developed below the middle. In other individuals, the gibbous
upper part of the valve is marked by a narrow sinus, which becomes broader
below ; and in others, the dorsal valve is concave throughout its entire length
and breadth, except a slight convexity along the cardinal slopes. The front is
sometimes truncate or sinuate, and not unfrequently pointed from the extension
of the mesial ridge of the ventral valve, and the corresponding sinus of the dor¬
sal valve.

In a single specimen from the Schoharie grit, the dorsal valve is quite flat ;
and another from the Corniferous limestone has the ventral valve scarcely suban-
gular in the middle, and the dorsal valve regularly and gently convex.

Geological formations and localities. This species occurs in the Schoharie grit,
at numerous places in Albany and Schoharie counties, and particularly near Clarks¬
ville and Schoharie. It is likewise found in the Corniferous limestone at numerous
localities, but is usually somewhat rare in this rock in New-York. It occurs in the
same horizon in Canada West and in Ohio.

CENTRONELLA OF THE ONONDAGA LIMESTONE.

401

Centronella alveata.

PLATE LXI.

Rhynchonella 1 alveata : Hail, Tenth Report on the State Cabinet, p. 124. 1857.

“Compare Centronella hecate : Billings, Canadian Journal, May 1861.

Shell elongate-oval or subrhomboidal ; length much greater than the
width ; sloping from above the middle to the prominent beak of the
ventral valve, the included angle being about 70°. Anterior margin
subtruncate for about one-third the width of the shell.

Ventral valve prominent in the middle, from a broad, undefined, abruptly
or scarcely subangular mesial elevation : the slope thence to the sides
below the middle is scarcely convex, and above the middle the sides
are more convex, with a little flattened expansion close to the margin ;
the longitudinal outline gently arched ; the beak prominent, erect or
slightly arching.

Dorsal valve, in the upper part, convex at the sides and depressed in
the middle into a wide undefined sinus, which, below the first third
of the length, embraces the entire width of the valve, giving it a
trough-shaped aspect..

Surface smooth : shell compact, punctate.

Length of specimen, one inch.

This species, described by me in 1857, has so much the form and character of
C. hecqte, Billings, described in 1861, that I can scarcely doubt the identity of
the two ; the only difference being in the size of the specimens.

Geological foi'mation and locality. The original specimen of this species was
given to me many years since by Mr. W. H. Pease, as coming from the Onondaga
limestone ; but the particular locality is unknown.

[ Paleontology IY.]

51

402

PALEONTOLOGY OF NEW-YORK.

I

Centronella impressa.

PLATE LXI.

Centronella impressa : Hall, Fourteenth Report on the State Cabinet, p. 102. 1862.

“ « Idem, Fifteenth Report on the State Cabinet, p. 160- 161. 1862.

Shell subovate in outline, sometimes extended in front, rarely *sub-
sinuate ; width and length about as seven to nine.

Ventral valve convex, prominent or subangular along the middle and
abruptly curving to the sides; longitudinal outline slightly arched,
sometimes nearly straight : beak nearly erect and truncated by a
rounded foramen, which is limited below by deltidial plates.

Dorsal valve much shorter than the ventral, in the upper part convex
at the sides, and flattened or depressed in the middle and towards the
front, which is much produced and curves downwards to occupy the
sinuous outline of the ventral valve. Sometimes the dorsal valve is
nearly flat, with an impressed line down the centre, and sometimes
flattened in the upper part and convex in the lower part : beak not
incurved.

Surface with fine concentric striae and nearly obsolete remains of very
fine radiating striae, which are visible only under a lens. -Shell com¬
pact ; texture punctate.

The interior of the ventral valve shows a very strong tooth on each
side at the base of the fissure, and nearly one-third the length of the
valve from the apex. The interior of the dorsal valve shows the dental
sockets and a remarkably strong thickened hinge-plate, which is clmcave
in the centre, the margins extended and inclosing an oval muscular area,
which is divided by a low longitudinal septum. Outside of the muscular
area there is a low longitudinal ridge extending to the anterior margin
of the shell. [ In these features, it resembles, but is very distinct from,
the interior of the dorsal valve of C. glans-fagea.] The crura have not
been observed.

CENTRONELLA OF THE HAMILTON GROUP. 403

This species has the general form and aspect of C. glansfagea ; differing,
however, in a very characteristic manner. It has a similar compact and finely
punctate texture, and the propriety of referring it to the same genus can scarcely
be doubted.

Geological formation and localities. This species occurs in the Hamilton group :
on Coshong creek near Bellona in Yates county ; at York in Livingston county ;
at Pavilion in Genesee county ; >and at Hamburgh on the shore of Lake Erie, in
Erie county.

Centronella glaucia (n. s.).

PLATE LXI.

Shell ovate or ovoid, gibbous, with the front rounded or subtruncate
Ventral valve gibbous, highly arcuate longitudinally, more elevated in
the middle and sometimes subcarinate, curving abruptly to the sides :
beak strongly arched.

Dorsal valve convex on each side and abruptly bent downwards at the
margins, slightly depressed in the middle of the upper part, with a
more distinct sinus towards the front.

Surface marked by fine concentric striae, which at intervals are crowded
into subimbricating folds or ridges. Shell compact; structure punctate.
The cast of the ventral valve shows a deep arching rostral cavity,
and strong muscular imprints below, with deep curving dental lamellae.

The specimens are nearly three-fourths of an inch in length, with a
width of more than half an inch.

Geological formation and locality. This species occurs in some compact beds
of the Hamilton group in Schoharie county; the particular locality unknown.

404

PALAEONTOLOGY OF NEW-YORK.

In the preceding arrangement of the materials in the collections
forming the subjects of this volume, there has been comparatively little
difficulty in assigning to each genus its approximate relations; and from
the Orthides onward, there is a very natural succession among the genera.
In this arrangement, however, two genera, Tropidoleptus and Vitulina,
are left out of the series ; nor does there appear to be any place where
either one of these can be naturally introduced.

We had originally supposed that Tropidoleptus would find its place
among the Strophomenidae ; but there have been at all times some
important objections»to placing it in this relation, while later discoveries
have rendered such a reference unnatural. Notwithstanding the con¬
cavo-convex form, area, and large fissure under the beak of the ventral
valve, still the punctate structure of the shell and the character of the
crura seem to indicate its relations to be with the Terebratulidge ; and
I have accordingly placed it in an order following the authentic genera
of this family.

Genus Tropidoleptus (Hall).

[Gr. rpomc, carina; Xenroc, tenuis.']

TaopiDCLBPrus : Hall, Report on the State Cabinet. 1857.

« Id. Palasozoic Fossils. 1857.

<< Id. Twelfth Report on the State Cabinet, p. 31. 1859.

Shell transversely suboval or semielliptical, concavo-convex : hinge¬
line extended, not crenulate ; articulating by teeth and sockets.

Ventral valve convex, with a distinct area, and wide fissure beneath
the beak. Dental lamellas distinct from the margin of the fissure,
crenulate.

Dorsal valve concave, with crenulate dental fossets ; a strong cardinal
process, with diverging lobes in the interior, which support slender
crura that converge to and unite with the median crest.

GENUS TROPIDQLEPTUS.

ms

Surface plicate : shell-structure punctate.

The typical species of this genus is a concavo-convex shell, having
the general form of Lept^ena and Strophomena, and was originally
described by Mr. Conrad as Strophomena carinata. It differs from all the
genera of Strophomenidse in both external and internal characters, and,
for these reasons, has been separated. The shell is externally strongly
ribbed, and the texture is finely punctate throughout its substance. The
ventral area is well defined, narrow and linear. The fissure or foramen
is very large and wide, and is excavated above the area line, coming
quite up to the beak, and sometimes even including the apex which is
worn away or absorbed. .

The teeth, which are a little separated from the margins of the fora¬
men and not continuations from it, are strong and thickened below, while
they are deeply crenulated on the summit and exterior margins. There
is a narrow low median ridge in the cavity of the valve ; and the divari-
cator muscular impressions are broad, and flabelliform. The occlusor
muscular impressions have not been satisfactorily observed.

The dorsal valve has a narrow area, and a wide and strong cardinal
process which nearly or quite fills the foramen of the opposite valve.
This process is often simple exteriorly, above the limit of the smooth
or striated pseudo-deltidium which covers it near the hinge-line ; but
just within the valve it is broadly grooved in the middle, usually with
two small deep pits just within the external smooth callosity, and on each
side there is a groove and accessory lobe, frequently not conspicuous.
The divisions made by the median groove diverge and terminate below
in obtuse processes which have some similarity with the bases of crural
processes in Orthis, but have more analogy with the Terebratulidse. These
processes are sometimes clearly broken at their termination, but are
often smooth as if the roughened surface had been cicatrized during the
life of the animal. Below these forks of the process there is a narrow
median crest or septum which reaches beyond the middle of the valve,
and sometimes nearly to the front. From the limbs of the thickened
divergent processes there proceed slender crura which, at first bending

■imi

PALEONTOLOGY OF NEW-YORK.

slightly outwards, send off a short spur into the ventral cavity and are
thence directed forwards, and gently curving, join the median crest, to
which they are attached, forming a loop of peculiar character. The occlu-
sor muscular impressions have rarely been seen with any degree of dis¬
tinctness ; hut the depressions just at the termination of the crural
processes, and on each side of the median ridge, are striated ; and this
striation often extends in a wide flabelliform expansion, probably due
to vascular impressions. Towards the margin, the interior of both valves
is strongly pustulose.

The accompanying wood-cuts illustrate the parts referred to above.

Fig. l.

Interior of the dorsal valve.

b. Crenulated teeth-sockets.

c. Crural processes.

1. Loop..

s. Septum.

Fig. 2.

Longitudinal section of the dorsal valve

j. Cardinal process.

b. Tooth-socket.

c. Crural processes.
1. Loop.

s. Septum.

In the punctate texture of this shell, it differs from either of the Genera Lep-
xasNA, Strophomena or Strophodonta ; but this might not be an objection to
admitting Tropidoleptus into the family, were the other characters coincident.
The area is longitudinally striated, and presents a different aspect from any of
the Strophomen i dad , but has analogy with some of the Orthides. The teeth are

not extensions of the lamellae bounding the foramen, but distinct from it and
deeply crcnulate or lobed, and inserted into corresponding crenulate sockets in
the dorsal valve. The form of muscular impressions, so far as known, is not very
dissimilar to those of Strophomena or Orthis.

In comparing the form of the cardinal process and its appendages, we shall
find it almost entirely similar to that of Leptoccelia, as shown in two authentic
species (L. flabellites and L.Jimbriata), and the muscular impression of the ven¬
tral valve is quite like that of the same species.

TROPIDOLEPTUS OF THE HAMILTON GROUP.

407

The exterior extremity of the cardinal process presents considerable variety of
aspect, when a large number of individuals are examined. In some of them this
part, if stripped of the external callosity of pseudo-deltidium, would have the
main process bilobed, with a sinus a little below the apex, and an accessory lobe
on each side similar to some of the species cf Productus.

Tropidoleptus carinatus.

PLATE LXII.

Strophomma car inala : Conrad, Ann. Geol. Rep. p. 64. 1839.

Leptccna laticosta ■: Hall, 1843. .

“ «< of Owen and others.

Tropidoleptus carinatus : Hall in Tenth Report on the State Cabinet, p. 151. 1857.

Tropidoleptus : Genus described and illustrated in Twelfth Report on the State Cabinet, p 31. 1859.

Shell concavo-convex, semielliptical, the length sometimes nearly
equalling the width : hinge-line equalling, greater, or less than the
width of the shell, and the cardinal extremities sometimes rounded
so as to give the shell a broadly oval form ; the sides are sometimes
nearly straight, and the front broadly rounded.

Ventral valve convex, broadly subcarinate along the middle, and sloping
in a flattened curve to the lateral . margins and front, which is some¬
times slightly truncate or emarginate : cardinal extremities deflected,
abruptly incurved at the umbo, and the apex often imperfect from the
encroachments of the foramen. Area from half a line to about one line
in width ; its margins parallel to near the extremities, where it slopes
suddenly down from the outer margin. The area is longitudinally
striate, and indented by a very wide foramen.

Dorsal valve moderately concave, sometimes nearly flat, often with a
median depression or sinus which becomes conspicuous below the
middle of the valve : apex small, projecting a little beyond the hinge-
line. There is a narrow area, interrupted in the middle by a wide
pseudo-deltidium which covers the extremity of the cardinal process.
Surface marked by* about eighteen to twenty broad, simple, rounded
plications which are wider than the spaces between them ; the cen¬
tral one on the ventral valve is broader and more elevated than the
^others, while there is a corresponding wider and deeper depression in

408

PALAEONTOLOGY OF NEW-YORK.

the middle of the dorsal valve. In rare instances, the plications are
bifurcated. Fine undulating concentric striae cover the surface, and a
few stronger imbricating lamellae mark the form of the shell in its
stages of growth.

The interior structure has been noticed under the generic description.
Specimens from certain localities show no appreciable difference in the size of
the costae, and there is no distinct carination in the middle.

In its young state, the shell resembles Chonetes dejlecta, but usually is propor¬
tionally longer ; and the absence of spines, as well as its punctate surface, are
distinctive features.

The illustrations, figures 2 a, b, c, are of unusually elongate forms, where the median plica¬
tion is not perceptibly larger than the others.

Figures 3 a-k present the principal varieties of form and size of the species; .and figure 3 1
shows a dorsal valve with bifurcating plications.

Figure 4 .is a form with more numerous and finer plications, but in other respects does not
show important differences.

Figure 3 m shows the general aspect of the area and foramen, with the cardinal process.
The remaining figures show the interiors of ventral and dorsal valves, and the casts of the
same as they occur in the arenaceous beds.

When extremely magnified, the surface presents the structure shown in figure 3 s.

A similar or identical species has been recognized in Europe, and is published
under the name of Leptcena laticosta in the Bull, de la Soc. Geol. de France,
Tome iv, pa. 325, pi. 3 ; but it is there represented as having about thirty-two
plications, a greater number than any of our specimens, and it will probably
prove a distinct species of the same generic type.

Geological formation and localities. In the Hamilton group in Schoharie county,
and extending throughout the State of New- York from near the Hudson-river to
Lake Erie. Some of the principal localities are in Schoharie and Otsego counties ;
on the shores of Cayuga, Seneca, and Canandaigua lakes, and at Darien and
Eighteen-mile creek. It is likewise known in rocks of the same age in Illinois and
Iowa,

Tropidoleptus occidens.

PLATE LXII.

Tropidoleptus occidens : Hall in Thirteenth Ann. Report on the State Cabinet, p. 91. 1860.

Shell concavo-convex, semielliptical, about as long as wide : apex of
the ventral valve extending beyond the hinge-line. Area linear, appa-

GENUS VITULINA.

40©

rently equal on the two valves. Surface marked by twelve or fourteen
angular plications on each valve ; of these, two central ones on the
ventral valve are a little elevated, and two others on the dorsal valve
correspondingly depressed.

So far as known, this shell offers differences by which it is readily separated
from the preceding species. It may, however, prove to be only a variety.

Geological formation and locality. In limestone of the age of the Hamilton
group, at Iowa city, Iowa. From Rev. W. H. B arris.

The Genus Vitulxna was founded upon a species peculiar in form and
internal characters, and no others of the same type have yet been
observed. It presents many features in common with Orthis; and among
these may be mentioned the area on each valve, smaller on the dorsal
than on the ventral, and the wide fissure of the ventral valve, partially
filled by the cardinal process of the opposite valve. The cardinal process
itself is unlike that of Orthis, but the strongly divergent teeth-like
crura are similar ; and these, from their great divergence, would scarcely
admit of the terebratuloid loop, or of spires, unless arranged as in Atrypa.
The punctate texture is as much like Orthis as it is like Terebratula ;
while the muscular impressions are similar to those of Orthis. In its
punctate texture and papillose surface, it reminds one of Spiriferina,
but its internal structure is quite different.

With our present knowledge of its characters, I am compelled to
express a doubt as to its family relations ; and I have therefore placed
it at the end of the series.

Paleontology IV.]

52

410

PALAEONTOLOGY OP NEW- YORK.

GENUS VITALINA (Hall).

Y itulina : Hall, Thirteenth Report on the State Cabinet, p.72. 1860.

Shell plano-convex : hinge-line extended : valves articulating by teeth
and sockets.

Ventral valve gibbous, with a high area, and large triangular fissure. A
callosity or false area in the bottom of the fissure. Dental lamellaa
thick and strong.

Dorsal valve depressed-convex, with a scarcely perceptible area; a
strong cardinal process, which is conspicuous at the base of the fissure
in the closed valves.

Surface plicated, papillose : shell-structure punctate.

Vitalina pustulosa.

PLATE LXII.

Vitulina pustulosa : Hall in Thirteenth Report on the State Cabinet, p. 82. 1860.

Shell subplano-convex, semielliptical : hinge-line equalling or a little
less than the width of the shell : surface marked by a few strong pli¬
cations, and covered by minute papillae, which appear like the bases
of setae. Substance of the shell finely punctate.

Ventral valve very convex; the apex a little arcuate, subangular in the
middle above, and the elevation continued in a broad fold which is at
first flattened and then becomes grooved or duplicate below, with four
or five rounded or subangular plications on each side ; the arga much
elevated, and the margin sloping rapidly from the apex to the cardinal
extremities : foramen large and wide, being half the length of the
area, and reaching to the apex ; deltidial pieces or pseudo-deltidium
unknown.

Dorsal valve flat or slightly convex, with a wide mesial depression
which is nearly flat in the bottom, and in larger specimens has a shal¬
low groove in the middle towards the front. The plications on the
sides correspond with those of the ventral valve. There is a narrow
scarcely perceptible area.

GENUS VITULINA.

411

Surface covered by minute papillas. Substance finely punctate.

In the interior of the ventral valve, the margins of the foramen are
extended in two strong teeth, which are supported on the lower and
lateral margins by a callosity of the shell. Beneath the apex, a strong
callosity or false area extends across the valve and reaches to the base
of the teeth. This callosity is visible in the foramen, and from its lower
margin proceeds a slender median septum (fig. 1 h). On each side of this
septum, at its junction with the transverse callosity, there is a small
pit for the occlusor muscle ; and beyond this a broad flabelliform area
for the divaricator muscular attachments. These features are shown in
the cast, fig. 1 i.

In the dorsal valve, there is a strong median ridge '"or septum which
terminates in a slightly lobed cardinal process ; on each side of this are
the crural processes, and between these and the margin are the teeth
sockets.

Figures 1 a, 5, are of the largest specimens observed. Figures 1 c and 1 d are enlarged,
showing the character of the plications and the pustulose surface. Figures 1 e, f are
enlargements from an entire specimen : the profile, as given, represents the dorsal area as
proportionally too wide. The interiors of the valves and the cast of the ventral valve are
enlarged two diameters.

Geological formation and localities. This species was first observed in a single
individual among specimens collected at Canandaigua lake, and was afterwards
found at York in Livingston county. More recently, and since the engravings
were completed, Mr. Whitfield has found the fossil in considerable numbers
near Tully and at Tinker’s falls in Onondaga county.

412

PALAEONTOLOGY OP NEW-YOPK.

ADDENDA.

Trematospira ? nobilis.

PLATE.

Rhynchospira nobilis : Hall, Thirteenth Report on the State Cabinet, p. 83. 1860.

This species was omitted in its proper place, in the hope of being able
to determine its true relations ; but the result has not been quite satis¬
factory. It appears, however, to be more nearly related to the Genus
Trematospira than to Rhynchospira ; and it may be found to differ from
either of these when the internal characters shall be fully ascertained.
Shell large, broadly subovoid; surface plicated.

Ventral valve with a broad mesial sinus ; the beak large and truncated
by a large round foramen, the lower side of which is hounded by the
summits of the deltidial plates : margins of the valve subalate a little
below the beak.

Dorsal valve the more gibbous, with a broad, moderately elevated mesial
fold.

Surface marked by numerous angular elevated plications, which are
sharply crenulated on the summits ; the sides and intermediate spaces
finely and evenly striated. On the mesial fold there are from nine to
eeven plications, and a corresponding number in the sinus.

The interior of the ventral valve shows a strong tooth on each side
at the base of the fissure ; the rostral cavity is limited by a callosity,
and the muscular area is strongly marked and somewhat quadrate in
form, as far as observed.

The interior of the dorsal valve shows strong crural processes exten¬
ding from the hinge-line for a short distance, when they become slender
and flattened ; and below this they curve and send off a process towards
the centre of the shell, as in others of the genus, and similar to that of
Terebratula.

Geological foi'mcdion and locality. In the Hamilton group ; at Darien, Genesee
county, New- York.

ADDENDA.

413

Genus Pholidops (Hall.)

In 1859, I proposed the name Pholidops for some minute fossils belonging
apparently to the family Craniadai, but differing from the true Crania in
being free or unattached to other bodies, so far as is known. Since that
time my attention has been called to the figures of Crania antiquissima of
Eichwald, as given by de Verneuil, in the Geology of Russia and the Ural
Mountains, vol. ii, plate 1, figs. 12, a, b, c. These are cited by McCoy as
illustrations of typical form of Pseudocrania. In the figure 12 a, we have the
characteristic muscular impression of Pholidops; fig. 12 b, can scarcely be¬
long to the same species since the apex is subcentral. The figures of
Pseudocrania divaricata given by McCoy, ( British Paleozoic Fossils,) illus¬
trate a different type ; the exterior is represented as radiatingly striate
with a distinct area like Trematis, while the interior presents four mus¬
cular pits as in Crania, and quite unlike the Pholidops of our strata.
Prof. McCoy has cited both the above species as typical forms, but in
the present state of our knowledge I am not prepared to abandon the
• Genus Pholidops.

Pholidops arenaria, (n. s.).

PLATE III, FIG-. 10. See note, page 82.

Shell rather above the usual size, subcircular, discoid ; beak submarginal
and slightly elevated ; front margin expanded and flattened.

Surface unknown ; interior characterized by a large subcentral muscular
scar, which in the cast is much deeper on the front margin, and divided
by a narrow septum.

This species closely resembles P. oblata of the Schoharie grit, but differs in being
more nearly circular and in having a much larger area occupied by the muscular
impression. The largest specimens measure a little more than one-fourth of an
inch in length.

Geological formation and locality. In the Oriskany sandstone in the town of
Knox, Albany county, N. Y.

[Palaeontology IV.]

53

414

PALAEONTOLOGY OF NEW YORK.

Pholidops oftlata (n. s.).

PLATE III, FIG. 10.

Shell suborbicular, somewhat flattened on the upper margin, discoid or
depressed convex ; the length and width about equal ; muscular area of
the interior small, circular, and divided through the middle by a longitu¬
dinal septum. External surface unknown.

In general aspect this species somewhat resembles P. armaria , but differs very
materially in the form of the muscular impression.

Geological formation and locality. In the shales of the Hamilton group, at Car
ter’s Mills, four miles south of Aurora, Onondaga county, N. Y.

Pholidops ? liiiguloides (n. s.).

PLATE III, FIG. 11.

Shell broadly ovate, with an obtusely pointed beak, which is apparently
terminal.

Surface covered by rather closely arranged, strongly lamellose concentric
lines of growth, which reach the margin of the valve near the beak.
Length of shell sixty-two hundredths of an inch ; greatest width, fifty-six
hundredths of an inch.

This species differs from any of the described forms of the genus Pholidops in
its terminal beak and subnacreous shell. There may be some doubt regarding the
propriety of its reference to this genus, but at present no other group seems so well
adapted to its reception.

Geological formation and locality. In concretionary layers of the Hamilton
shales, on Canandaigua Lake, New York.

Strophomesia rhomhoidalis ?

PLATE XV, FIGS. 15, 16.

Specimens of shells having the characters of this species have been
obtained among a collection from Mallet’s Creek, two miles north of York

ADDENDA.

415

Centre, Medina county, Ohio, in rocks pertaining to the Waverly group.
The specimens present no characteristic differences from those of the Lower
Helderberg group, or any modifications which cannot be detected among
the collections of specimens from that group. Individuals may be selected
from any of the formations that will show strong and well marked differ¬
ences, either from these under consideration, or from each other, but a
series connecting the extremes from either the Niagara or Lower Helderberg
groups will contain individuals having the same characters with those pre¬
sented by the Ohio specimens.

The occurrence of this species in this Geological position, is the more
interesting since thus far, it has not been found in the Hamilton or Che¬
mung groups of New York.

Strophodonta subdemissa.

PLATE XVII, FIGS. 2 h, 2 i.

Strophodonta subdemissa : Hall, Tenth Report on the State Cabinet, p. 145.

Strophodonta demissa : Hall, Geological Report of Iowa, Vol. I, part 2, p. 495, pi. 5, a, b, c. d

Strophodonta dimosa ? [demissa] Owen. Geol. Survey of Wisconsin, Iowa, Minnesota. Explana¬
tion of Table III a, fig. 14.

Shell semicircular in outline, with more or less extended and sometimes
mucronate cardinal extremities.

Ventral valve depressed convex, somewhat regularly arching from beak to
base ; area narrow, crenulated.

Dorsal valve concave, nearly following the curvature of the ventral valve ;
area linear, crenulated.

Surface marked by strong radiating striae, which are increased by intersti¬
tial additions becoming finer and more numerous near the margin in adult
individuals. The striae are themselves longitudinally striate on well pre¬
served specimens, having from three to six striae on each of the larger
ones, near the middle portions of the ventral valve.

I have hesitated to continue this as a distinct species, and have so indicated on
page 114 of this volume. The Western specimens, however, show a constant dif¬
ference in form and in certain peculiarities of the striae. While the New York

416

PALAEONTOLOGY OF NEW YORK.

forms are usually longer than wide, the Western ones are as long as wide, and
sometimes wider, and the cardinal extremities are usually extended and frequently
mucronate. They are likewise less ventricose, the space between the valves being
less, and the muscular impressions not so strongly marked. In these respects,
however, the New York specimens of the Chemung group more nearly resemble
the Western ones.

Geological formation and locality. In rocks of the age of the Hamilton group,
at Rock Island, Ill., and at Independence and New Buffalo, Iowa.

Spirifera mala.

PLATE LXIII, FIGS. 6-13.

Mhyris maia : Billings. Canadian Jour. Ind. Sci. and Arts, May, 1860, p. 276.

Shell below the medium generic size, ventricose, with rounded cardinal
angles, giving a longitudinally ovate outline, with a depressed suhglobose
form ; hinge line very short ; cardinal area narrow and sometimes hidden
by the beak.

Dorsal valve suborbicular, moderately ventricose, with a distinctly elevated
rounded mesial fold.

Ventral valve more ventricose than the opposite,' with a large, tumid ?

incurved beak, and a moderate, subangular mesial sinus.

Surface destitute of plications, but marked by more or less distinct concen¬
tric striae of growth.

This species is of the type of, and in some conditions greatly resembles, S. lineata,
of the Coal measures, but differs in the projecting beak and more ventricose dorsal
valve, as also in the surface markings. It is also very similar to tS. subumbona ,
of the Marcellus shale, but is a larger form, and differs in the shorter hinge line,
larger beak and more ventricose dorsal valve, and in the surface markings.

Geological formation and locality. In the Corniferous limestone of Ohio and
Canada West. The specimens figured are from Rev. H. Herzer, of Columbus, Ohio.

ADDENDA.

417

Spirifera whitneyi.

Spirifera whitneyi: Hall. Geological Report of Iowa, p. 502, plate 4, f. 2.- 1859.

This species is referred to on page 245, as derived from beds of the age
of the Hamilton group, in Iowa. More recent observations, with pretty
extensive collections made in several localities in Iowa, by Mr. It. P. Whit¬
field in 1866, have led to the conclusion that this species, together with its
associates in the same locality, are of higher beds than those of the Hamil¬
ton group and should properly be referred to the age of the Chemung.

Some further notice of the species thus associated, will appear in the
State Cabinet Report.

Spirifera nsesastrialis.

PLATE LII, FIGS. 14-22,

This species, in its varieties of form, has heretofore been referred to the
Chemung group only. More recent collections, with better knowledge
of the limits of the Chemung and Hamilton groups in the eastern part
of the State, have shown its occurrence in the two formations. The speci¬
mens from Schoharie county are from rocks of the Hamilton group, and are
separated from those in Delaware county by almost non-fossiliferous beds of
several hundred feet in thickness. It is a little remarkable that while the
geographical range of the species is less than two hundred miles, its vertical
range should be so very great.

Miiynclionella (Stenocisma) contracta var. saxatilis.

PLATE LIY A, FIGS. 44-51.

Among the collections from Rockford, Iowa, there are some specimens of
Rhynchonella, which possess many of the characteristic features of R. con¬
tracta of the New York Chemung group, and also those of R. eximia
of the same formation. The examples figured on plate 54 A, figs. 44-49,
have much the appearance of the former species, except in size, while the
[Paleontology IV.] 54

418

PALAEONTOLOGY OF NEW YORK.

specimens, figs. 50 and 51, are of the type of R. eximia, of small size.
Although there are few examples in the collection, they still show a
gradual increase in the plications, from those having the least to those with
the greatest number, without any possible means of drawing a line of sepa¬
ration between them ; while among the New York specimens the separation
is comparatively easy. Considering these facts, the specimens are for the
present referred with some doubt to R. contracta, until more material can be
obtained, offering better means of comparison.

Tereforatula lincklrcni vat.

PLATE LX, FIGS. 32-87.

Compare T. Traversensis, Wincli. Rep. on Grand Traverse region, p. 95. 1866.

Among some Terebratuloid shells obtained from Thunder Bay, Michigan,
there are a few having some resemblance to T. lincklani, but differing in
some points which, if constant among a larger number of specimens, might
prove to be of specific importance in a group of shells of such close charac¬
ters as Terebratula. These shells are usually more ventricose in the um-
bonal region than T. lincklani, with a larger and more strongly incurved
beak, the perforation of which is also larger ; the front of the shell is likewise
much less gibbous, often being thin and somewhat flattened below the mid¬
dle, and the greatest width being above the centre instead of below, as in
that species. Taking into consideration these points of dissimilarity, it
may be desirable to recognize it as a distinct variety until more material
may show its proper relations.

Terebratula Ontario (n. s.).

PLATE LX, FIGS. 45-48.

Shell small, very broadly ovate or subcircular, with depressed convex
valves of nearly equal depth ; beak of the ventral valve incurved and
strongly truncated by a circular perforation, the lateral margin subcari-
nate.

ADDENDA.

419

Surface marked only, by distant concentric lines of growth.

This species resembles T. lens more nearly than any other in the New York
rocks, but is a little more convex in proportion to its size, and the beak is com¬
paratively higher and less incurved, while the shell is more nearly circular, and
has its greatest width nearer the front.

Geological formation and locality. In the Hamilton shales on Canandaigua Lake,

N. Y.

Centronella ovata (n. s.).

PLATE LXI A., PIGS. 47-49.

■ Shell small, oval or slightly ovate ; width and height as four to five, great¬
est width near the middle of the length.

Dorsal valve depressed convex, without perceptible sinus.

Ventral valve much deeper than the dorsal, subcarinate along the centre,
most ventricose just below the beak, which is strongly incurved ; lateral
margins of the beak slightly carinate.

Sruface marked only by concentric lines of growth.

This species resembles C. julia in form, but is a narrower shell, with a less con¬
vex dorsal valve ; the ventral valve is more ventricose and carinate along the mid¬
dle, and the beak more strongly incurved.

Geological formation and locality. In the Upper Helderberg limestones at
Cayuga, C. W.

Centronella julia.

PLATE LXI A, FIGS. 41-46.

Centronella julia : Winchell. Proc. Acad. Nat. Science, Phil. Vol. xiv., page 405. 1862.

Shell small, lenticular.

Ventral valve a little more ventricose than the opposite, scarcely carinate
along the middle.

Dorsal valve regularly convex, without sinus.

Surface unknown.

This shell closely resembles O. ovata , but differs in several particulars, as indi¬
cated above.

Geological formation and locality. In the Marshall sandstones, Point aux
Barques, Mich.

42©

PALEONTOLOGY OF NEW YORK.

Centroiiella hecate.

PLATE LXI A, FIGS. 27-29.

Centronella hecate: Billings. Canadian Journal, May, 1861, page 272.

Shell elongate, half as long again as wide, with a slightly incurved project¬
ing ventral beak.

Dorsal valve regularly arcuate from beak to base, with a moderate mesial
sinus, which is angular in the bottom.

Ventral valve sharply angular or carinate along the middle, with flattened
sides.

This species resembles C. alveata in form, but is much smaller, the sinus is less
deep and the cardinal margins not reflected while the lateral margins of the beak*
are rounded instead of being sharply angular.

Geological formation and locality. In the Upper Helderberg limestones at
Cayuga, C. W.

Meristella lenta (n. s.).

PLATE LXHI, FIGS. 19-22.

Shell small, broadly ovate, or transversely oval, with a slightly projecting
beak and very unequally convex valves.

Ventral valve nearly flat in the upper part, with sharply angular cardinal
margins becoming deeply and subangularly sinuate towards the front,
where it is slightly bent upwards.

Dorsal valve very ventricose in the umbonal portion, and subangular along
the centre, with the sides somewhat flattened.

This species differs from any described form of the genus so far as it can be
ascertained. In "the form of the ventral valve it approaches somewhat the M.
(. Pentagonia ) unisulcata, but the sinus is narrow instead of embracing the greater
part of the valve, and it differs so materially in other respects that there is no dan¬
ger of confounding the two.

Geological formation and locality. In rocks of the age of the Oriskany sand¬
stone or Upper Helderberg limestones, near Cayuga, C. W.

ADDENDA.

421

Uliyncliospira subglobosa.

PLATE LXIII, FIGS. 28-25.

Among the -collections from the Schoharie grit, there are a few specimens
of Rhynchospira which have much the general appearance of R. globosa of
the Lower Helderberg group. They differ in having a smaller number of
stronger plications, with a single, more prominent one in the middle of the
dorsal valve, and a corresponding wider depression on the ventral valve ;
while in R. globosa there are one, two or three smaller plications forming
a kind of mesial sinus on one or both valves, which is a constant and
characteristic feature of the species, as also of all those of the Genus in the
Niagara and Lower Helderberg groups.

This simple mesial plication, together with the globose form, will distin¬
guish this from any described species of the Genus.

Remarks upon the Character of the Crura and Loop of Terebrattjla and
Cryptonella illustrated in this volume.

A careful examination of the interior structure of the Terebratuloid
shells, has shown sufficient ground for the separation of the Genus Crypto¬
nella, and the external character of the shells would seem to afford the
necessary means of distinguishing the Genera. Among the species included
under the Genera Terebrattjla and Cryptonella, there are three distinct
forms of loop which are in some degree connected with an external differ¬
ence in the form of the shell.

The simplest form of loop observed is similar to that of Terebrattjla
proper, but with the anterior extension of the crura free, or not connected
by any visible extension of the calcified substance of the loop, the extremities
appearing as if broken. There may have been some connexion of the parts
by ligament or otherwise during the life of the animal. This form of loop, so
[Paleontology IV.] 55

422

PALAEONTOLOGY OF NEW YORK.

far as observed, is characteristic of the short ventricose shells, usually having
their widest portion anterior to the middle, as in T. jucunda, T. simulator,
and T. harmonia. Probably the New York forms of T. ro&mingeri would
show this feature could specimens be obtained suitable for cutting.

The second form of loop is short with the anterior portion sharply re¬
curved and twisted in the curving. As examples of this form we have T.
sullivanti in the figured specimen, and T. rcumingeri, from Thunder Bay,
Michigan. These forms are rotund or appressed.

The third form of loop is like that of Waldheimia, but has the crura
connected by a band on the dorsal side opposite the crural processes. The
external form of these species is more or less appressed in the upper part
of the shell, with a flattened beak. The principal forms known are Cryp-
tonella rectirostra, C. planirostra , and C. eximia.

The first form of loop mentioned is probably of generic importance, as
there are several species which show it clearly. The second form of loop
is the same as that of the third, with the exception of the dorsal band, the
recurved portion being quite short. It does not, therefore, differ essentially
from Waldheimia except in extent. The third form differs from Wald¬
heimia only in the possession of the connecting dorsal band.

COEEIGETsTD A

Page 13, line 15, after spatulnta, insert vanuxem.

Page 33, line 4, before beds, insert fossiliferons.

Page 36, line 7, for 1 and 2, read 1 a and 1 b.

Page 36, line 9, for 3, 4 and 5, read 2 a-d , 3 a-e.

Page 42, line 23. for Idas read eryna.

Page 45. line 20, for vi read vn.

Page 48, line 14, for Laveille read Leveille.

Page 48, line 27, for vi read vii.

Page 49, line 33, for 3 e read 4 e.

Page 52, line 23, for vii read lxiii.

Page 76, line 10, before species, insert other.

Page 78, line 25, after median, insert line.

Page 101 , line 4, for 1 c read 1 e.

Page 101, line 7, for 1 l read 1 i.

Page 101, line 8, for 1 k, u, read 1 k, l.

Page 101, line 10, for 15 read 13.

Page 108, line 21, for textilis read junta.

Page 109, line 32, dele this line.

Page 111, line 10, for xix A. read xv.

Page 111, line 11, for Strophodonta read Stropliomena.
Page 112, line 9, for elmira read cayuta.

Page 113, line 9, for 8 read 6.

Page 116, line 7, for no species read one species.

Page 136, lines 4 and 5, dele reference to Plate 22.

Page 136, line 19, for konincki read koninckiana.

Page 137, line 19, refer species to Plate xxii.

Page 138, line 12, after forty insert (including bifurca-

Page 143, line 1, for mnricatus read mnrtcata.
Page 144, line 19, for (fig. 00) read (fig. 33).

Page 156, line 1, refer species to Plate xxxii.

Page 165, line 23, for Productiis? read Productus
(JProductella) papulata (n. s.).

Page 166, line 4, insert beneath, Productus hirsulus:
hall, 10th Rep. St. Cab. p. 175. 1857-
Page 167, line 24, for 1-9 read 18-27.

Page 167, line 29, for 9 read 24.

Page 171, line 15, for 19-23 read 1-9.

Page 183, line 29, for or two, read one, two.

Page 188, lines 1 and 3, for CviSTiEXA read Cyrtina.
Page 189, line 2, for Spirifer read Spirifera.

Page 196, line 12, for species read shells.

Page 200, line 23, for 34 read 35.

Page 201, line 3, for 34 read 35.

Page 205, line 21, for xxx read xxxr
Page 207, line 30, after of the, insert area.

Page 218, line 21, for 33 read 34.

Page 223, line 22, for S. arcta read S. arata.

Page 225, line 17, dele sentence referring to casts.

Page 229, line 5, for xxxvill read xxxvm *.

Page 234, line 18, for xxxii read xxxill.

Page 241, line 11, for greasly read greatly.

Page 246, lines 10 and 17, for xli read xm.

Page 246, line 12, for 15 read 17.

Page 246, lines 18 and 33, for xlii read XLI.

Page 250, line 2, for xxxii read xxxm.

Page 251, line 13, for xxxii read xxxm.

Page 251, line 15, for 32 read 31.

Page 251, line 18, dele 2d comma, and insert variation .
Page 253, line 32, for marylandica read cumberlandia.
Page 262, line 27, for 5 a read 5.

Page 270, line 3, for xvn read xliv.

Page 271, lines 9 and 10, dele reference to dotted line.
Page 279, line 33, for xiv read xlv.

Page 287, line 9, for 10 read 8.

Page 287, line 10, for 8 read 9.

Page 287, line 11, for 9 read 10.

Page 290, line 13, after h insert (see figure on Explanation
of Plate.)

Page 299, line 18, change reference of A. nasuta to Jour.
Acad. Nat. Sci. Ph. vol. viii, p. 265. 1842.

Page 305, line 33, for shade read shale.

Page 329, line 2, for liii read Lll.

Page 329, line 10, dele may— may.

Page 343, line 2, for liv read liv A.

Page 344, lines 2 and 25, for liv read LIV A.

Page 346, line 2, for LV read liv a.

Page 349, line 1, after stepliani add (n. s.).

Page 357, line 1, after mysia add (n. s.).

Page 361, line 2, for lvi read lvii.

Page 364, line 16, for lvii read lvi.

Page 373, line 37, dele P. obsolescens.

Page 380, line 6, for lviii read lviii a.

Page 384, line 28, for lix read lviii a.

Page 385, line 7, for LX read lviii a.

Page 388, line 5, dele without appendage.

Page 397, line 1, for Cryptonella ? read Terebra-
tula.

Page 399, line 17, for lxi read lxi a.

Page 401, line 2, for lxi read lxi a.

Page- 402, line 2, for lxi read lxi a.

Page 403, line 10, for lxi read lxi a.

Page 408, line 33, for lxii read lxi a.

Page 412, line 3, after Plate add lxiii.

INDEX TO .THE GENERA AND SPECIES DESCRIBED IN THIS VOLUME.

Page

Ambocxelia . . . 258

“ gregaria . 261

“ nucleus . . 259

“ prasumbona . 262

“ subumbona . . 234

“ , umbonata . 259

“ “ v. gregaria. 261

Amphigenia .... 369, 374, 382

“ elongata . 383

“ “ v. undulata.. 384

Anasteophia . 369, 374

Anomia — reticularis . 316

Anomites — reticularis ..... 316

“ rhomboidcdis . 76

Athybis . '. . . . . 282

“ angebca . 292

“ (?) chloe . 274

“ clara . 299

“ cora . *291

“ maia . . . 416

££ (?) polita . . . , 293

“ spiriferoidos . 285

“ yittata . 289

Ateypa . 312

“ acutiplicata . 365

“ affinis . 317

“ arata . . . 375

££ aspera . 322

“ concinna . 279

“ concentrica ... . 285

“ congregata . 341

“ contractu . . 351

“ cuboides... . 346

“ duplicata . 350

“ eximia . 348

“ hirsuta . 274

“ globuliformis . 364

“ hystrix . 326

££ impressa . 315

“ laticosta ......... . 351

“ lentiformis ........ 317

“ limitaris . 356

“ mesacostalis . 362

“ nasuta . . 299

“ octocostata . 375

££ polita . 293

“ pseudomarginalis . . . 327

“ - reticularis. . 316

“ rostrata . 307

“ scitula . 302

“ spinosa vel aspera. . . 322

“ unisculata.. . . . . . 309

[Paleontology IV.]

Page

Camaeophoeia . 367

“ schlotlieimi . 367

“ i eucharis . 368

Centbonella . . . 399

“ alveata - *. . 401

" glans-fagea . 399

“ glaucia . 403

“ hecate . 420

“ impressa . . 402

“ . julia . 419

“ ovata . 419

Chaeionella — circe . 302

“ doris . 303

Chonetes . 115

“ acutiradiata . 120

“ arcuata . 119

“ coronata . 133

“ deflecta . . 126

“ gibbosa . 126

“ glabra . 121

“ hemispherica . 118

“ laticosta . 124

“ lepida . 132, 142

“ lineata . 121

ce logani v. auroj'a. . . . 137

“ mucronata . 124

“ muricata . 143

“ pusilla . 128

“ scitula . . . 121, 130, 141

“ setigera. . . . . . . 129, 142

“ yandellana . 123

Ccelospiea . 328

“ concava . . 329

Ceania . . . 26

“ aurora . 27

“ crenistriata . 28

" gregaria........... 29

“ hamiltonise . 27

“ leoni . 30

Cbyptonella . 392

“ (Terebratula) eudora 398

“ iphis . 396

“ (?) lincklseni . 397

“ planirostra . 395

“ rectirostra . 394

Cybtia . 263

“ biplicata . 266

tc dalmani . 265

<e hamiltonensis . 268

“ rostrata . 265

Cyetina . 263

“ biplicata . 266

56

Page

Cyetina crassa . 267

“ curvilineata . 270

“ dalmani . 265

“ hamiltonensis . 268

“ “ v. Tecta . ' 270

“ pyramidalis . 265

tc rostrata . 265

Delthyeis — acanthota . 244

“ acuminata .... 198, 240

” chemungensis . 244

cc congesta . 223

£C cuspidata . 244

“ disjunct a . 244

“ duodenaria . 189

“ duplicata . 236

“ jimbriata . 214

cc granulifera . 223 .

“ inermis . 244

“ Icevis . 239

“ macronota . 231

“ medialis . .227

“ mesastrialis . 242

“ mucronata . 216

“ perlata . 244

c< prisca . 317

“ prora . 234

“ raricosta . 192

“ sculptilis . . 221

<c undulatus. . 192

“ zigzag..-. . 222

Discina . 15

“ alleghania . 25

“ doria . 19

“ elmira . 24

“ grandis . 17

“ humilis . 16

“ lodensis . 22

“ media . 20

“ . - (sp.) . 21

“ minuta . 16

£C neglecta . 24

“ newberryi . 25

££ randalli . 18

“ seneca . 20

££ truncata . 23

££ tullia . 22

Gypidula . 373, 380

££ lseviuscula . 381

££ occidentalis ........ 380

Hippabionyx — consimilaris 317

Leioehynchus . 355

££ dubius . 364

426

PALAEONTOLOGY OF NEW YORK.

Page

Leiorhynchus globuliformis 364

Orthis impressa . . . . .

Page
. 60

“ iris .

... 360

“ inequalis .

. b7

“ kelloggi .

... 361

“ interlineata. . .

. 59

“ ‘limitaris .

... 356

“ lenticularis . . .

. 35

“ mesacostalis . . . .

... 362

“ lepidus .

. 46

“ ' multicosta .

... 358

“ leonensis .

.....* 62

cc mysia .

... 357

“ leucosia .

. ’ 48

“ quadricostata . . .

... 357

“ “ (?) ....

. 63

“ sinuatus .

... 362

■“ livia . . .

38

Lepton A — depressa . . .

76, 77

“ - (sp.)...

. 39

“ fragaria . . . .

... 154

limitaris .

. 356

“ laticosta .

... 407

“ mitis .

. 37

“ oblonga .

... 154

“ nucleus .

. .. 76

ce pp.lnris .......

. 34

“ tenuistriata . . . .

76, 77

“ penelope .

. 50

Leptoccelia .

... 365

“ perversa .

... 67, 72

“ acutiplicata .

... 365

“ prceumbona . . .

u pravus .

. 262

. . . 329

. 67

Liktgula . .

... 5

“ propinqua. . . .

. 43

“ alveata .

... 12

“ quadricostata .

. 357

5

cc rugosa .

, . 76, 77

.. . 15

“ semele ......

. 40

“ delia .

... 12

“ subumbona . . .

. 234

“ densa .

... 11

■ ‘ solitaria .

....'. 45

“ desiderata .

... 6

“ thiemei .

. 63

“ exilis .

... 7

“ tioga .

. 59

“ leana .

... 9

“ tulliensis .

. 55

7

ee umbonata . . . .

. 259

te v„r

.. . 8

“ unguiculus

. 261

“ ma.ida .

9

cc yanuxemi ....

. 47

cc manni .

6

« « (?) .

. 40

. “ melie .

... 14

Orthisina — alternata .

, . . 67, 72

“ nuda .

... 10

“ dr cto striata. . .

.. 67, 71

“ palseformis .

... 8

Pentagonia .

. 309

“ punctata .

... 10

ct peersi .

. 309

“ spatulata .

... 13

Pentamerella .

369, 373

Meganteris — elongatus

... 383

“ arata . . . .

. 375

Meristella .

... 295

“ dubja .

. 379

“ barrisi .

... 304

“ micula .

. 378

“ doris .

... 303

“ obsolescens . . .

“ elissa .

... 299

“ papilionensis. .

- 377

“ haskinsi .

... 306

Pentamerus .

369, 375

“ lenta...- .

... 420

“ aratus .

. 375

*• meta .

... 308

“ elongatus .

. 383

“ nasuta . . . .

... 299

“ occidentals . .

.... 380

“ rostrata .

“ , papilionensis. .

.!... 377

" scitula .

... 302

PnOLIDOPS . .

. 31, 413

“ unisulcata .

... 309

“ arenaria .

..... 413

“ (?) - - 7 (SP.) .

... 308

“ areolata .

. 31

MERISTtNA .

... 299

“ hamiltonise . . .

cc maria .

. .. 299

“ linguloides . . .

. 414

Nucleospira .

... 278

“ oblata . .

. 414

“ ( concinna .

... 279

Productella .

. 153

Orbicula — grandis. ....

... 17

“ arctirostrata. .

. 182

“ lodensis .

... 22

“ bialveata .

..... 183

<c minuta.. .

... 16

“ boydi .

. 169

Orthis .

... 33

“ costatula .

. 180

“ alsus .

“ “ v. strigata. . . . 181

“ carinata .

... 58

“ dumosa . .

..... 162

** cleobis .

... 41

“ exanthemata .

. 163

“ cyclas .

... 52

“ hirsuta . .

. 166

“ equivalvis .

... 42

“ “ v. recti spina. . 168

“ idas = O. eryna

... 42

“ hystricula . . . .

“ idoneus .

... 52

“ lachrymosa . . .

Page

Productella :

“ lachrymosa v. lima.. 174

“ “ v. stigmata.. . 174

“ nayicella . 156

“ onusta . 148, 184

“ rarispina . . . 170

“ shumardiana . 157

‘ speciosa . 175

“ spinulicosta . 160

“ striatula . 148, 177

** subaculedta . 154

“ subalata . 165

“ truncata . 160

“ tullia . . 164

Productus.. . . . . 146, 153

“ arctirostratus . 172

“ boydii . 169

“ concentricus . . . 157

“ costatus.. . ,. 149

“ depressus . 76

“ dumosus . 162

“ exanthematus . 163

“ navicella . 156

“ pyxidatus . . 157

“ rarispinus . 170

“ shumar dianus . 157

175

“ spinulicosta . 160

“ spinulosus . 154

“ subaculeatus . . 154

“ subalatus . 165

truncatus . 160

“ (?) (sp.) . 165

Rensseljeria . 369, 385

“ elongata . 383

“ (?) johanni, . 385

Retzia . 272

eugenia (?) . 272

Rhynchonella . 332

“ (?) alveata . 401

“ glans-fagea . 399

“ (?) laura . 358

“ thalia . 336

“ unisulcata . . 309

“ venustula . 346

“ (Stenocisma) billingsi. 336

“ “ carica . 344

“ “ Carolina. . . 337

“ “ ' congregata 341

*•* “ contracta. 351

“ “ v. saxatilis 417

“ “ dotis . 344

“ “ duplicata . 350

“ “ eximia . . . 348

“ “ horsfordi . 339

cc “ orbicularis 353

“ “ prolifica . . 343

“ “ royana . . . 338

“ “ sappho . . . 340

“ “ “ var. 354

“ . “ stephani . . 349

tethys.... 335

INDEX.

437

Page

Rhyncho sp ir a lepida . 276

subglobosa . . 421

Spirifera . 186

acuminata .... 198, 234

alta . 248

angusta . 230

arata . . 235

archiaci . 243

arctisegmenta . 208

calcarata . 243

corticosa . . . 236

disjuncta . 243'

disparalis. . . 204

distans . '...... 243

divaricata . . . 213

duodenaria. . 189

duplicata . 236

euruteines ......... 209

“ v. fornacula . . 211

extensa . 243

fimbriata . 214

formosa ........... 220

gigantea . : . . 243

•grandceva . . 243

granulifera . 223

gregaria . 195

grieri . 194

inornata . 243

lrnvis . . 239

lonsdalei . 243

macra . 190

macronota . 231

macrothyris . 202

maia . 416

manni . 211

marcyi. . 226

medialis . . 227

“ v. eatoni . 229

, 240

mesastrialis. . . 242, 41'

mucronata . . . 216

oweni . 197

pertenuis . 236

prsematura . 250

protensa . 243

raricosta . 192

sculptilis . 221

segmenta .....' . 207

subumbona . 234

tenuis . 236

tullia . 218

unica.- . 203

varicosa . 205

“ var . 206

verneuli . 243

whitneyi.. . . . 417

ziczac . 222

Spirifer — acuminatus. 198, 234

affinis . . . 317

angusta . 230

arata . 235

archiaci . 243

arctisegmentus . 208

barumensis . 244

Page

Spirifer clintoni . 223

“ clio.. . 222

“ corticosa . . 236

“ cultrijugata . 198

“ disjunctus.... 243, 244

“ disparilis . 204

“ •divaricatus . 213

dubius . 379

“ duodenaria . 189

ee duplicata.. . 223

“ eatoni . 229

“ euruteines . 209

“ fimbriata . 214

“ formosa....'. . . 220

“ fornacula . 211

“ granulifera . 223

“ gregaria . . 195

“ grieri . 194

“ heteroclitus . 223

“ macra . 190

“ macronotus . 231

“ macrothyris. . 202

“ manni . 211

“ marcyi . 226

“ medialis . 227

“ murchisonianus .... 243

“ oweni . \ 197

“ pertenuis . 236

“ pyramidalis . . 265

“ segmentus . 207

“ tenuis . 236

“ varicosus . 205

“ venustus . 213

“ verneuilii . 244

Spiriferina . 312, 187

Spirigera — concentrica . . . 285

“ spiriferoides . 285

Spirigerina. . . . 312

“ reticularis . 317

Stenocisma . 335

Streptorhynchus . 64

“ arctostriata . 71

“ chemungensis . 67

“ pandora . 68

“ pectinacea . 73

“ perversa . 72

Stricklandia — elongata. . . 383
Strickla-ndinta . . 369, 371, 373

Strophalosia . 146, 153

“ subaculeata . 154

Strophobonta . .

alveata .

amp la .

callosa . 82

cayuta . 110

ccelata . 112

concava . 96

crebristriata .

demissa... 81, 101, 114

fragilis .

hemispherica . 90

inequiradiata. ......

inequjstriata. . . . 93, 106

Page

Strophodonta mucronata . . Ill

“ nacrea . 104

parva . 85

“ patersoni . 89

“ perplana . 92, 98

“ “ v. nervosa. .. . 113

“ plicata . 114

“ subdemissa . 114

“ textilis=junia . 108

Strophomena . . 76

“■ acutiradiata . 120

“ arctostriata . 67

“ bifur cata . 67, 73

ct carinata . 407

“ “ scr. coronata. . 133

“ chemungensis . 67

“ crenistria . 92, 98

“ delthyris . 98, 113

“ demissa . 101

“ depressa . 77

“ fragilis . 98

“ inequistriata . 106

‘c interstrialis . . . 110

“ lachrymosa . 172

“ lepida . 104

cc lima... . 174

“ lineata . 121

“ membranacea . 166

“ mucronata .... Ill, 124

“ nervosa . 113

“ pectinacea . 67, 73

“ • perplana . 92, 98

“ pluristriata . 98

“■ pustulosa . 160

et rhomboidalis . 76

“ rugosa . 77

" setigera . 129

“ syrtalis . 133

“ textilis . 108

“ undulata . 77

Sdessia . 188

Terebratula . 386

“ affinis . 316, 317

“ cancellata . . 316

“ cancellatae : . 316

(?) concentrica . . 285

“ crenulata . 346

“ elia . 390

“ harmonia . 388

“ insperata . . 317

“ insquamosa . 317

“ jucunda . 390

“ lens . 386

“ lincklseni var . 418

cc minutissime striata. 316

“ navicella . . 391

“ Ontario . 418

“ pectinatce . 316

“ planirostra . 395

“ prisca . 317

“ rectirostra . 394

“ ■ reticularis . 317

“ rcemingeri . 389 ’

“ simulator . 391

4Ǥ8

PALAEONTOLOGY OF NEW YORK.

Page

Terebratula spiriferoides . 285

“ squamifera . . . 317

“ striata . . 316

“ subtillissime . ^16

“ sullivanti . 387

“ zonata . 317

Terebratulites— priscus. . 316

Page

Terebratulites explanatus. 317

Trematospira . 271

“ costata . 276

“ gibbosa . 272

“ multistriata . 276

“ (?) nobilis . 412

“ hirsuta . - . . 274

Page

Trematospira perforata . . . 276

Tropidoleptus . . 404

“ carinatus . 407

cc occidens . 408

Vitulina . 409, 410

“ pustulosa . 410

EXPLANATIONS AND PLATES.

EXPLANATION OF FIGURES.— PLATE 1.

Page

Fig. 1. . Lingula spatulata. . 13

1 a. A specimen of the natural size.

1 b. An enlargement of the specimen 1 a.

Fig. 2. Lingula ligea . . 7

2 a. The exterior of a valve, natural size.

2 b. The interior of a valve which shows faint indication of muscular or vascular marking about

the middle of its length.

Figs. 3, 4. Lingula melie . 14

3, 4. Show the extremes of form among a considerable number of specimens.

Fig. 5. Lingula cuyahoga..... . 15

5. A single valve of the natural size.

Fig. 6. Lingula punctata . 10

6 a. A young individual of the natural size.

6 b. An individual of the ordinary size, -which is a little wider than usual.

6 c. The ihterior of a va'lve.

6 d. An individual from which the shell is nearly all exfoliated, showing the peculiar muscular
impressions illustrated in fig. 6 e, which is enlarged two diameters. It is probably
the ventral valve.

6 /. Another individual which shows the muscular impressions of a little different form, with a
longitudinal depression. It is probably the dorsal valve.

6 g. Is an enlargement of the surface showing the texture of the shell.

Shells having these interior characters should properly be separated from Lingula.

Fig. 7. Lingula pal^formis . 8

7. A specimen (probably the ventral valve) , natural size.

Figs. 8, 9. Lingula exilis . 7

8. A specimen, natural size, with the beak imperfect.

. 9. A more convex individual which may belong to this species.

Figs. 10, 11. Discina newberryi . 25

1,0 a. A dorsal yalye of this species.

10 b- A ventral valve with the shell nearly all exfoliated.

11 a. A dorsal valve of this species.

11 b. A profile of the same.

11 c. A dorsal valve of different form, but probably of the same species.

Figs. 12, 13. Disciija neglecta . 24

12. An impression of the dorsal valve with a part of the shell remaining in the centre, and
showing the muscular impressions.

13. From a gutta-percha cast made in the impression of a dorsal valve.

B..P ."WhitfieLi , 3 el.

PLATE 1 — Continued.

Page.

Fig. 14. Discina lodensis . 22

14 a, b, c, e. Varieties of form of the dorsal valve.

14 d,f. Ventral valves of the same species.

Fig. 15. Discina truncata . 23

15 a. A dorsal valve of the natural size.

15 b. The same enlarged.

Fig. 16. Discina minttta . 16

16 a. A dorsal valve of the natural size.

16 6. The same enlarged.

Fig. 17. Discina alleghania . 25

. 17 a. The dorsal valve of a large individual.

17 6. A profile view of fig. 17 a.

17 c'. The central valve of the same species.

Fig. 18. Discina grandis. . 17

18 a. A dorsal valve which is somewhat distorted.

18 6. The interior of a ventral valve of the same species.

PLATE 2.

Page

Fig. 1. Lingula ceryx . . 5

1 . An imperfect valve in arenaceous rock.

Fig. 2. Lingula desiderata . 6

2 An imperfect valve enlarged to two diameters.

Fig. 8. Lingula manni . 6

3. A single valve of natural size.

Figs. 4-6. Lingula nuda. . . 10

4, 5, 6. Separate valves presenting the usual variety of form of this species.

Fig. 7. Lingula punctata . 10

7. Profile of a specimen retaining both’ valves in connexion.

Fig. 8. Lingula ligea var . 8

8. A specimen of this species from the Portage group, at Trumansburgh, N. T.

Fig. 9. Lingula delia . 12

9. A specimen of the natural size, showing the mark of a linear septum.

Figs. 10, 11. Lingula densa . 11

10. 11. A ventral and dorsal valve of the natural size.

Fig. 12. Lingula leana . 9

1'2. A ventral valve of the natural size.

Fig. 13. Lingula maida . 9

13. A specimen of the natural size.

Figs. 14, 15. Lingula alyeata . 12

14. An impression with the remains of the shell on the margin, showing the mark of a longitu¬

dinal septum.

15. A larger individual; the impression in shale shows what appears to have been a triple

medial septum.

Figs. 16, 17. Dtscina tullia . 22

16. Vertical view of a dorsal valve, natural size.

17. Profile of the same.

Fig. 18. Discina humilis . 16

18. View of a ventral valve.

Palajoni jt.y.VoI .4 W. HIISIt3n)3SIEI13IBB.©P3EMIEE™(o)M © (5W.mH.mS® ©a*?®

RP .'WHtfieli , 3 el .

SwxnJboii, lith..

PLATE 2 — Continued.

Page

Figs. 19-22. Discina doria . . 19

19. Vertical view of a specimen of an tipper valve; enlarged two diameters.

20. Profile of the same, from Canada West.

21. A dorsal valve of the same species, natural size.

22. A group of specimens attached to. a univalve shell.

Figs. 23, 24. Discina seneca . 20

23. Vertical view of a dorsal valve, natural size.

24. Profile of the same.

Figs. 25-28. Discina media. . . 20

25. 26. Dorsal and ventral valves, natural size.

27. A ventral valve enlarged two diameters.

28. A specimen' of the ventral valve of this species, from the Chemung group.

Fig. 29. Discina media var . 21

29. A ventral valve from the Marcellus shale.

Figs. 30, 31. Discina doria. ? . 21

30. A vertical view of a dorsal valve, which is rather more convex than usual in this species.

31. A profile of the same.

Figs. 32, 33. Discina grandis . 17

32. A profile showing the usual elevation. The line surrounding this figure gives the ele¬

vation of a specimen referred to this species, Plate 1, fig. 18 a.

33. A fragment of rock with a group of four individuals of this species.

Fig. 34. Discina randalli . 18

34. The lower side of a ventral valve, natural size.

Fig. 35. Discina lodensis . V . 22

35. A group of three ventral valves, natural size.

Figs. 36, 37. Discina truncata . 23

36. 37. Dorsal and ventral valves enlarged to three diameters.

Figs. 38, 39. Discina elmira . 24

38. A dorsal valve, vertical view.

39. Profile of the same.

40. Undetermined.

2

PLATE 3.

Figs. 1, 2. Pholidops . oyalis .

1, 2. Vertical and profile views of a specimen retaining both valves. From the Niagara group,
ol’ Waldron, Ind. Enlarged to five diameters.

Page

Fig. 3. Pholidops arenariA . (See note on 32)

A cast of the valve from the Oriskany sandstone, enlarged to three diameters. See p. 413.

Figs. 4, 5. Pholidops areolata . . . 31

4. An impression of the dorsal valve.

5. An impression of the ventral valve. The figures enlarged to three diameters.

Figs. 6-9. Pholidops hamiltoni.® . 32

6. The exterior of the shell, enlarged to four diameters.

7. The interior of ventral valve, showing the muscular impressions.

8. An impression of the ventral valve.

9. The opposite or dorsal valve of the same species, enlarged to eight diameters.

Fig. 10. Pholidops oblata . 413

10. An impression (apparently of the dorsal valve), showing the muscular impression ; enlarged

to four diameters.

Fig. 11. Pholidops ? lamellosa. . . 413

11. Ventral ? valve of the specimen; enlarged to two diameters.

Fig. 12. Crania aurora . 27

12. An impression of a ventral valve.

Figs. 13-16. Crania crenistriata . 28

13. The dorsal valve of a small individual.

14. The dorsal valve of a large individual, the margins having been crushed.

15. Vertical view of a broadly elliptical dorsal valve.

16. Profile of the same.

Figs: 17- 23. Crania hamiltoni^e . . . 27

17. Vertical view of a dorsal valve.

18. Profile of the above.

19. Two individuals attached to the surface'of a shell of Tropidoleptus, one of them having

carried the form of the ribs of the shell into its growth.

20. The interior of a ventral valve.

21 . A group of ventral valves attached to the surface of Microdon bellastriata.

22. A ventral valve having the cardinal border modified in its outline by the presence of Spi-

rorbis angulata a, a, attached to the same shell surface with the Crania.

23. An enlargement of the specimen fig. 22, Intended to show the muscular and vascular markings

more distinctly.

Paiaeont M\Y.Voi.4 TBT. m (SM^MIOT©-

( BRACKIOPODA.J

E-P.TWdteali.ael.

Swm.toiL.lith..

PLATE 3— Continued.

Page.

Fig. 24. Crania gregaria . 29

24. A large bivalve shell with humorous individuals of the Crania attached to its surface. There

are also the remains of the ventral valves of C. hamiltonite, and the smaller ones are
perhaps only the young of that species.

Figs. 25, 26. Crania leoni? . 30

25. The dorsal val.ve of this species.

26. A profile of the same.

Figs. 27-80. Crania leoni . 30

27. Dorsal valve retaining the shell, supposed to be of this species.

28. Profile of the same.

29-. The cast of a dorsal ? valve of this species.

30. The cast of a ventral ? valve of the same.

PLATE 4.

Figs. 1, 8, 9, 10. Orthis peloris .

1. The ventral valve from a gutta-percha cast of an impression in the stone.
8, 9. Natural casts of the ventral valve.

10. A natural cast of the dorsal valve.

Page

34

Figs. 2-7. Orthis alstjs . 36

2. The dorsal valve of this species ? from a gutta-percha cast of an impression of the exterior.

3. The exterior of a dorsal valve, showing a mesial depression.

4. A cast of the interior of a ventral valve.

5. A cast of the interior of a dorsal valve.

6. A cast of a ventral valve which is nearly flat.

7. A cast of a dorsal valve, the muscular impressions being scarcely defined.

Figs. 11-19. Streptorhynchus chemungensis, var. pandora . 68

11. A cast of the dorsal valve of a young individual.

12. A gutta-percha cast of an impression of the exterior of a ventral valve.

13. A cast in stone, of the dorsal valve.

14. A gutta-percha impression from a cast of the dorsal valve.

15. A cast of the dorsal valve retaining the shell on the margins.

16. The cast of a small dorsal valve.

17. The interior of a ventral valve) from a gutta-percha impression.

18. The cast of a ventral valve.

19 A ventral valve which is more finely striate than is usual with this species; probably an
extreme variety.

Palseo nt. N Y.YoJ .4

PLY

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( BRACnrOPODA.)

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PLATE 5.

Page

Pigs. 1, 2. Orthis lenticularis . . . 35

1 a, b. Dorsal and ventral views.

1 c. Profile of the above.

1 d, e. . Cardinal and front views of the same shell.

2 a, b. Dorsal and ventral views of a larger shell.

2 c, d. Profile, and front view of the same.

2 e. Interior of a ventral valve.

Fig. 3. Orthis propinqua . 43

3 a, b. Yentral and dorsal views of a small gibbous specimen, from cherty layers of Corniferous

limestone at Lapham’s mill, Ontario county.

3 c. Profile of the above.

3 d, e. Yentral, and dorsal views of a large individual, from near Columbus, Ohio.

3 f. Profile of the above.

3 g. A cast of the dorsal valve, showing muscular and vascular impressions; from Avon, N. Y.

Fig. 4. Orthis livia . 38

4 a. b. Dorsal and ventral views of a specimen from the Corniferous limestone of Western New

York.

4 c. Profile of the. above.

Fig. 5. Orthis sp. ? . 39

5 a, b. Dorsal and ventral views of a specimen.

Fig. 6. Orthis vanuxemi ? . 40

6 a, b. The exterior and interior of a ventral valve.

Fig. 7. Orthis semele . 40

7. The exterior of a ventral valve, showing the extent of the hinge-line.

8. The interior of a ventral valve. The specimen occurs in the same stone with fig. 7, but the

hinge-line is imperfect and does not appear to have been so much extended as in that

specimen.

Figs. 9, 10. Orthis cleobis. . 41

9. A cast of the dorsal valve, showing the impression of the area.

10. A cast of the ventral valve.

Fig. 11. Orthis idas.'. . 42

11 a, b. Dorsal and ventral views of the same specimen. 0. eryna, see Errata.

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PLATE 6.

Page

Fig. 1. Orthis lepidus . 46

1 a. Yentral view of a specimen, natural size.

1 b. Dorsal view, natural size.

1 c. d. Yentral and dorsal views, enlarged to two and a half diameters.

1 e,f. Profile, and front views, same enlargement.

Fig. 2. Orthis penelope..... . 50

2 a. Dorsal view of a young individual.

2 b. A ventral view of an older individual.

2 c. A dorsal view of a specimen of the ordinary size.

2 d. Dorsal view of a large individual.

2 e. Profile of the above.

2/. Cardinal view of the same.

2 g, h. The interiors of ventral valves, showing the form of the muscular impression.

2 i. The same, with the shell much thickened around the muscular impression and towards the
front.

2 k The interior of a dorsal valve, showing a thickening of the cardinal process.

2 l. An enlargement of the surface, showing the character of the striae, the ordinary puncta, and
the elongate tubular openings.

2 wi. A cast of the dorsal valve of the same species, from Cumberland, Md.

Fig. 3. Orthis vanuxemi . 47

3 a, b, Ventral and dorsal views of a young individual.

3 c. Ventral view of a specimen of medium size, presenting the ordinary form of the species.

3 d. A ventral view of another individual.

3 e. Profile of a specimen.

3 /. A ventral view.

3 g. Dorsal view.

3 h. Yentral view of a large individual — the largest which can be satisfactorily referred to this
species.

3 i. Dorsal view of the above.

3 k. Profile of the same.

3 l. Cardinal view of the same.

3 m. The interior of a ventral valve.

3 n, o. The interiors of dorsal valves.

3 p. An enlargement of the surface striae, showing the puncta and tubular openings enlarged to the
same degree as fig. 2 l, offering a comparison of the character of striae mode of bifurcations,
tubular openings, etc.

3 A cast of a yentral yalye supposed to be of this species, from Cumberland, Md.

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PLATE 7.

Page

Fig. 1. Orthis solitaria . 45

1 a. Dorsal view of the specimen described.

1 b. Ventral view of the same.

1 c. Profile of the same.

1 d. Front view of the same.

Figs. 2, 3. Orthis cyclas . 52

2 a. Dorsal view of a specimen enlarged to two diameters.

2 b. Ventral view of the same.

3. A ventral valve enlarged to two diameters.

Fig. 4. Orthis letjcosia .

4 a. Ventral view of a small specimen.

4 b. Dorsal view of the same.

4 c. Dorsal view of a specimen of ordinary size. Larger specimens have been obtained since
these figures were made.

4 d. Ventral view of the same.

4 e. Profile of the same.

4/. Cardinal view of the same.

4 g. The interior of a dorsal valve.

4 h. The interior of a ventral valve.

4 i. A cast of a ventral valve which is probably of this species, from Cumberland, Md.

48

Fig. 5. Orthis tulliensis

5 a. Dorsal view of a specimen of ordinary size .
5 b. Ventral view of the same.

5 c. Profile of the same.

5 d. Cardinal view of the same.

6 e. Front view of the same.

5/. Ventral view of a more gibbous specimen.

5 g. Profile of the same.

5 h. Front view of the same.

5 i. Dorsal view of a cast of this species.

5 fc. Ventral view of the same.

55

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PLATE 8.

Fig. 1. Orthis leonensis? .

I. Cast of ventral valve.

Fig. 2. Orthis thiemei. ? . . .

2 Cast of the ventral valve.

Figs. 3-8. Orthis leonensis .

8. A dorsal valve.

4, 5. Casts of dorsal valves.

6, 7. Casts of ventral valves.

8. Exterior of a ventral valve.

Figs. 9, 10. Orthis leucosia? .

9, 10. The exterior of a dorsal valve and cast of the ventral valve.

Figs. 11 - 19. Orthis imrressa . . . .

II, 12. Casts of ventral valves of young individuals.

13. A dorsal valve retaining the shell.

14. Cast of a dorsal valve, showing muscular impressions and vascular lines.

15. Ventral valve retaining the shell.

16-18. Casts of ventral valves of the usual forms.

19. A cast of an unusually large specimen of a ventral valve.

Figs. 20-29. Orthis tioga .

20-23. Illustrations of the dorsal valve.

24, 25. Casts of the dorsal valve retaining impressions of the surface striae.
26, 27. Ventral valves showing the mesial elevation.

28, 29. Casts of the ventral valve, showing muscular impressions.

Figs. 30-32. Orthis carinata .

30. Cast of a ventral valve of this species.

31. A dorsal valve with the shell partly exfoliated.

32. A cast of the dorsal valve showing the form of the muscular impression.

Page

02

63

62

60

59

58

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PLATE 9.

Page

Figs. 1 - 12. Streptorhynchus chemungensis var. arctostrtata . 71

I, 2. Ventral valves of young specimens where the beaks are somewhat distorted, and the strias

not alternating in strength.

3, 4. External and internal views, of a dorsal valve of similar character.

5. Interior of a dorsal valve, the striae of which are sharp and equal in size.

6, 7. Exterior and interior of a larger dorsal valve, the striae of which are distinctly alternating

in strength.

8, 9. Ventral and dorsal valves of a semicircular form, where the striae are sharp and of equal
strength. Original of Orthisina [S.l arctostriata, 13th Report on State Cabinet.

10. Cardinal view of specimen, fig. 2, showing the distortion of the beak and the covered fora¬
men ; enlarged to two diameters.

II. Interior of a ventral valve of a specimen having equal striae; showing muscular impression,

teeth and covered deltidium.'

12. Enlarged view of a cast of a specimen having sharp equal striae, and showing the imprint of
the adductor and retractor muscles very well preserved.

12. t Enlargement of surface striae, showing their alternating character.

Figs. 13-17,26. Streptorhynchus chemtjngensis var, perversa . 72

13, 14. Dorsal valves of specimens, showing the alternating character of the striae.

15. View of an imperfect ventral valve.

16. Ventral valve of an individual retaining but a portion of the shell.

17. Cast of a large dorsal valve showing the impression of the alternating striae.

26. View of a very convex finely striated dorsal valve; referred with doubt to S. perversa.

Figs. 18-25, 27. Streptorhynchus chemungensis var. pandora . 68

18, 19, 20. Dorsal and ventral views and profile of a very symmetrical specimen of the species.

21. Interior of a dorsal valve, showing the muscular impressions, cardinal process and socket
plates.

23. Interior of a ventral valve, showing muscular impressions, cardinal area and teeth.

24, 25. Casts of a dorsal and ventral valve, showing the characters of the muscular impressions.

27. Exterior of a large ventral valve.

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PLATE 10.

Pago

Pigs. 1-26. Streptorhynchgs chemungensis . 67

1. A dorsal valve of symmetrical proportions, which has a convexity a little greater than that

of the ordinary specimens of S. pandora in the Corniferous limestone. The striae are
bifurcate, and in their partially preserved condition, are unequal at the margin of the
shell; a few finer ones between the larger reaching half or two- thirds the way to the apex.

2. The exterior of a ventral valve which is nearly flat, being slightly concave below the middle;

the apex is prominent and very slightly unsymmetrical.

3. A cast of the same valve stowing the muscular impression.

4. The exterior of a dorsal valve which is regularly convex; the striae are sharply elevated and

fasciculate, there being two or three finer ones between the stronger and more elevated ones.

5. A cast of the interior of the same valve showing the muscular and vascular impressions.

6. A dorsal valve of moderate convexity with one of the cardinal extremities abruptly rounded, and

the other distorted, apparently from some accidental cause. The stria} are fasciculate,
there being one, two or three finer ones between the stronger sharply elevated ones on the
lower half of the valve, while towards the beak they are all sub-equal. This is the origi¬
nal of Strophomena pectinacea.

6 a. An enlargement of striae, from specimen fig. 6, S. pectinacea.

7. A convex dorsal valve with the cardinal extremities slightly rounded; the striae are, in some

parts, sub-equal, and in others alternating in size, and the stronger ones are sometimes
interruptedly depressed. The mesial portion of the valve is flattened The specimen
shows the striae curving upward to the hinge line in a most remarkable degree.

8. The cast of a large and very convex dorsal valve with the extremities abruptly rounded. The

surface is unequally striated. The umbo is large and very prominent, while the surface
below the umbo to the front is somewhat depressed convex, and abruptly depressed on
each side, leaving the space between that part and the hinge extremities concave. This
specimen may be compared with fig. 26, Plate 9, from the Corniferous limestone.

9. A cardinal view of fig. 8.

10. A slightly concave ventral valve where the striae are sub-equal and bifurcating, or increas¬

ing by interstitial additions. The character of striae is precisely similar to those of
the Corniferous limestone specimens of S. pandora.

11. A dorsal viewin which thestriaeare sharp and sub-equal; of the type of Strophomena arcto-

striata.

12. A specimen of similar character which is extremely unsymmetrical.

12 a. An enlargement of the striae which characterize the specimens like those from 11 to 17.

13. A ventral view of an unsymmetrical specimen.

14. A cardinal view of the preceding specimen.

15. A profile of the same.

16. A cardinal view of specimen when the apex is less extended.

17. A profile of fig. 16. The specimens 11 to 17, are of the type of Strophomena arctostriata,

showing various degrees of distortion.

-.18. A ventral valve with rather deep and coarse striae.
jl9, 20. Casts of dorsal valves of nearly symmetrical forms.

21, 22. Casts of ventral valves.

23. A cardinal view of a cast of a large ventral valve which is symmetrical on the hinge line.

-24. The cardinal process from a gutta-percha cast from specimen fig. 9.

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PLATE 11.

Page

Figs. 1-3. Strophodonta alveata . 81

1. The interior of a dorsal valve as obtained from a cast in the Schoharie grit.

2. The cast of a ventral valve.

3- A smaller ventral valve of the same species.

Figs. 4-10. Strophodonta callosa . 82

. 4. Interior of a dorsal valve, from an impression in the natural mould, showing muscular impres¬
sions and cardinal process; enlarged to two diameters.

6, 7. Casts of ventral valves, natural size.

8. Interior of the dorsal valve, from an impression in the natural mould, showing muscular

impressions, cardinal prpcess, and the crenulated hinge line; enlarged to two diameters.

9, 10. Cardinal and ventral views of a cast of a ventral valve, showing the muscular impres¬

sions very distinctly; enlarged to two diameters.

Figs. 5, 11. Strophodonta parva . 85

5. Impression of a dorsal valve of this species.

11. Cast of a ventral valve, enlarged to two diameters, showing muscular impressions and the
crenulated hinge.

Figs. 12, 13, 18- 21. Strophodonta crebristriata . 86

12. Exterior of a small ventral valve.

13. Exterior of a smaller ventral valve, enlarged to two diameters.

18, 19. Exterior and profile of a larger ventral valve.

20. Enlargement of the surface striae.

21. Exterior of a very large ventral valve.

23. Interior of a dorsal valve, from an impression in the natural mould. Doubtfully referred
to this species.

«

Figs. 14-17. Strophodonta demissa . 81

14. View of a ventral valve taken from an impression left in the Schoharie grit by the decay of

the shell.

15. Internal cast of a ventral valve in the grit.

16. Interior of a dorsal valve, showing the muscular impressions and cardinal process.

17. Cast of the interior of a ventral valve, showing the muscular impressions in a very perfect

manner. From the soft shales of the Hamilton group.

Fig. 22. Strophodonta perpl ana . 92

22. An impression of a ventral valve of this species.

Figs. 24-31. Strophodonta inequiradiata . . . 87

24, 25. Profile, and vertical view of a ventral valve with distant coarse stria.

26. Yiew of a cast of a ventral valve showing a narrow muscular impression.

27, 28. Front and cardinal views of a cast of a. ventral valve, showing muscular and vascular

impressions in a very perfect manner.

29. Cast of a large ventral valve.

30, 31. Impressions of the exteriors of dorsal valves, showing sharp distant striae.

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PLATE 12.

Puge

Figs. 1-5. Strophodonta demissa . 81

1, 2. Dorsal and ventral views of a small individual.

3-5. Dorsal and ventral views and profile of a larger specimen. This individual is the largest
one observed in the Corniferous limestone.

Figs. 6-8. Strophodonta ineqtjistriata . 93

6, 7. Dorsal and ventral views" of a specimen of ordinary size.

8. Profile of a larger and very gibbous specimen.

Figs. 9-11. Strophodonta patersoni. ? . 89

9. A ventral valve of a specimen of ordinary size, but more convex than usual.

10. A profile of the preceding specimen.

11. An enlargement of the striae from the same shell.

Fig 12. Strophodonta inequiradiata . 87

12. The cast of a ventral valve which may belong to this species.

Figs. 13-15. Strophodonta perplana . ... 92

13. A young individual corresponding in size and character to the original of S. crenistria

as described in the Geol. Report of the 4th District.

14. A dorsal view of a large individual of the same species.

15 A cast of the ventral valve of the same species in chert, from Indiana.

Figs. 16-18. Strophomena rhomboid alis . 76

16. An individual with numerous regular undulations. This is of the type of S. undulata, of

Yanuxem’s Geol. Report of 3d District.

17. A specimen with few strong undulations.

18. A cast of the ventral valve showing few undulations.

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PLATE 13.

Figs. 1-5. Strophodonta patersoni . .

1. A ventral valve, of medium size, and depressed convex form.

2. A larger imperfect specimen, showing more distinctly the transverse wrinkles.

3. A large individual in which the striae are not so strongly marked as in the other specimens.

4. A cast of the ventral valve, showing the muscular impression, and preserving the marks of the

exterior striae.

5. A profile of fig. 3.

Page

89

Figs. 6 - 11. Strophodonta inequiradiata . . . . 87

6. A ventral valve of an individual of medium size.

7. A larger individual, having the cardinal extremities produced.

8. A cast of a large ventral valve.

9. A profile of fig. 8.

10. The cast of a ventral valve of this species.

11. An enlargement of the muscular impression of the same specimen.

Figs. 12, 18. Strophodonta hemispherica . 90

12. A ventral valve of extremely gibbous form, from Poit Colborne, Canada West.

13. A profile of the same. This specimen presents some variations from the usual form and

character of those from New York and Ohio, which have been referred to this species.

*

Pal aeon! N.Y.Vol.4

PL 13.

C or ni ferous Limestone.
( BRACHIOPOBA.)

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PLATE 14.

Page

Fig. 1. Strophodonta ampla . 98

1 a. A dorsal view of a young individual.

1 b. An impression of a dorsal valve of a specimen of medium size, showing the cavity left by
the cardinal process.

1 c. A ventral valve of a larger individual.

1 d. A profile of the specimen fig. 1 c.

1 e. A dorsal view of a large individual.

1 /. An enlargement of the surface, showing the transverse striae and the elongate, pustulose
elevations upon their surface.

1 g. The cardinal area of the ventral valve with a narrow, linear callosity closing the deltidium, and
a smooth triangular area which is continuous with the other portions of the same surface,
and "has apparently never been a foramen.

1 h. The interior of a ventral valve, showing the strong flabelliform muscular scar. The margin
of the area is broken (a usual condition) by the removal or the separation of the dorsal
valve.

1 i. A cast of the ventral valve from the Schoharie grit, showing the muscular scar and the

strongly punctate surface.

Fig. 2. Strophodonta concava . . 96

2 a. Yiew of a ventral valve which is constricted just below the cardinal extremities.

2 b. A profile of the same.

2 c. The interior of a dorsal valve, showing the muscular impressions and cardinal process.

2d. A cardinal view of a cast of the ventral valve, showing the muscular impressions.

Palaeont Y.Y.Vol.4

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PLATE 15.

Page

Figs. 1-5. Strophodonta concava .... . . 96

1. Interior of the dorsal valve of a young individual, showing the muscular impressions, cardi¬

nal process, socket plates and crenulated hinge ; enlarged to two diameters.

2. Interior of a deeply concave dorsal valve, showing very large socket plates.

3. Profile of specimen, fig. 2.

4. Enlargement to two diameters of the central part of an adult dorsal valve showing the mus¬

cular impression, cardinal process, socket plates and crenulated hinge.

5. Cardinal view of the specimen, fig. 4, showing the elevation of the cardinal process and

socket plates, crenulated hinge, and the absorption of the base of the cardinal process,
to accommodate the margin of the opposite valve ; enlarged to two diameters.

Fig. 6. Strophodonta patersoni . . . . 89

6. Interior of the dorsal valve of a specimen, referred with some doubt to this species.

Figs. 7, 8. Strophodonta perplana . . . . . . 98

7. Interior of a dorsal valve, showing the muscular impression, cardinal process and crenulated

hinge.

8. Cardinal view of specimen, fig. 7, showing the elevation of the cardinal process.

Figs. 9, 17. Strophodonta junia = S. textilis of text . 108

9. Exterior of a ventral valve, from the Tully limestone.

17. Cardinal view of a specimen, showing hinge area, deltidium, etc.

Figs. 10, 11. Strophodonta inequistriata . . . 106

10. Interior of a ventral valve, showing the arrangement of the muscular impressions; enlarged

to two diameters.

11. Enlargement of an imperfect dorsal valve, showing the highly elevated muscular impres¬

sions, cardinal process, etc.

Fig. 12. Strophodonta subdemissa . 414

12. Interior of a dorsal valve of this species, from the Hamilton group of Iowa.

Figs. 13, 14. Strophodonta mucronata . Ill

13. A ventral valve, showing mucronate extensions of the cardinal extremities.

14. A dorsal view of a specimen without mucronate extensions.

Figs. 15, 16. Strophomena rhomboidalis ? . 414

15. Exterior of a ventral valve, from the Waverly sandstone series of Ohio

16. Interior of a dorsal valve, showing the muscular impressions, cardinal process, etc., from
the Waverly sandstones of Ohio.

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PLATE 16.

Page

1. Strophodonta concava . 96

1 a. A ventral valve which is carinate along the centre.

1 6. A dorsal view showing the area of both valves, etc.

1 c. A profile of specimen fig. 1 b.

1 d. A large ventral valve which is less convex than the usual forms and somewhat undulated
or sub-plicated on the margin.

1 e. The exterior of a dorsal valve, showing the extension of the cardinal process above the
hinge line.

If. The interior of the specimen fig. 1 e, showing the muscular impressions, cardinal process,
crenulated hinge line, etc.

1 g. A profile of the same, showing the geniculation in front, and the muscular scar.

1 h. The interior of a ventral valve, showing the area and muscular impressions.

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PLATE 17.

Page

1. Strophodonta perplana . 98

1 a. A young individual.

1 b . An individual of medium size, having the cardinal angles extended.

1 c. A large ventral valve, having a cicatrix along the median line — a feature of not uncommon
occurrence in this species.

1 d. A dorsal valve which is somewhat contracted on the- hinge line.

1 e . An enlarged cardinal view, showing the areas of the two valves and a slight callosity on the
dorsal area. The area is much wider than usual.

1 f. The exterior of a ventral valve from the Hamilton group, at Rock Island, Illinois, show¬
ing the unequal or fasciculate striae.

1 g. The interior of the same, showing the muscular impression.

1 h. The interior of a ventral valve from the Hamilton group of New York.

1 i. The cast of a ventral valve, showing more distinctly the large flabelliform divaricator mus¬
cular impressions and the small occlusor muscular impressions.

1 k- An enlargement of the interior of a fragment of a dorsal valve, showing the peculiar form
of the cardinal process. The continuation of the process along the centre, forming the
median septum, is exfoliated.

1 l. A further enlargement of the hinge line, cardinal process, etc., from another individual.

The cordiform extremities of the process show the striated surface for the attachment of
the muscles.

1 m. A longitudinal section.

1 n. An enlargement of the surface striae of a New York specimen, showing the sub-equal striae.

1 o. An enlargement from a Rock Island specimen, (1 /,) showing the alternating or fascicular

arrangement of striae.

2. Strophodonta demissa . 101

2 a. A young individual.

2 b, c, d. Ventral valves of the ordinary form.

2 e. A dorsal valve having strong sharp striae.

2 /, g. Dorsal valves of the ordinary form, showing the area.

2 k, t, m. Ventral, dorsal and profile views of a large individual.

2 n. Profile of a moderately convex specimen.

2 o. A profile of the specimen fig. 2 c, which is more than usually gibbous.

2 p. An enlarged cardinal view, showing the areas of the two valves which are destitute of a
central callosity.

2 i. The interior of a ventral valve, showing the muscular impressions. The area has been
broken by the separation of the opposite valve.

2 s. The interior of a dorsal valve, showing the muscular impressions, the cardinal process and
crenulated cardinal margin.

Strophodonta subdemissa . 214

2 h, i. Dorsal and ventral views of a specimen from Rock Island, Illinois.

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PLATE 18.

Strophodonta NACREA. ..

Page

. 104

Fig. 1.

1 a, b, c. Ventral valves of this species, showing varieties of form.

1 d. A dorsal view of fig. 1 c.

1 e. A profile of the same.

1 /. A profile view of 1 a.

1 g. Interior of the ventral valve. The open deltidium is due to accident.

1 h' The interior of a dorsal valve.

Fig. 2. Strophodonta ineqdistriata . 106

2 a, b, c. Dorsal views of three individuals, showing the extremes of the ordinary forms.

2 d, e,f. Ventral views of the preceding specimens.

2 g. A profile of fig. 2 b-
2 h. The interior of a dorsal valve.

2 i. The interior of a ventral valve.

2 k. The interior of a ventral valve enlarged to two diameters, showing the peculiar dental

lamellae and the vascular impressions.

Fig. 8. Strophodonta textilis . 108

3 a. A ventral valve of this species.

3 b. A ventral valve which is more elongated than the usual form.

3 c. The dorsal side of a large individual, showing the cardinal area of the ventral valve and a
narrow callosity in the centre.

3 d. The interior of a portion of an imperfect dorsal valve, showing the small muscular area and
slender cardinal process.

3 e. An enlargement of the surface, showing the character of striae, etc.

4. A cast of a ventral valve which is apparently of the same species, much extended on the
hinge line.

Palasont X.Y.Vol.i.

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PLATE 19

Page

Figs. 1-5. Strophodonta cayuta . . 110

1. A cast of a small ventral valve.

2. The more common and prevailing form among specimens of larger dimensions.

3. A ventral cast, which is very gibbous and sub-plicate in the middle, with the cardinal extremi¬

ties greatly extended.

4. An enlargement of the surface striae, as shown in an impression in the stone.

5. An enlargement of the ventral muscular impression, and a part of the cardinal line, to show

the crenulations

Figs. 6, 7. Strophodonta ccelata . 112

6. An impression in a fine sandstone preserving the marks of muscular impressions, etc.

7. The impression of a convex dorsal valve supposed to he of the same species.

Figs. 8-12. Strophodonta demissa. . . . ; . 114

8. 9, 10. Casts of ventral valves, of variable and somewhat distorted forms.

11. The cast of a ventral valve of the ordinary form of the species.

12. The cardinal view of the same.

Figs. 13-16. Strophodonta perplana, var. nervosa . 113

13. The interior of a ventral valve having the form and general aspect of S. perplana, but with

the fine striae characteristic of S. nervosa.

14. A specimen having the cardinal extremities greatly produced. This specimen is the origi-
, nal of S. nervosa

15. A portion of a large ventral valve with sharp, strong, undulating striae, which are some¬

times elevated into pustules and again abruptly depressed. This character of surface
prevails in all the specimens in certain beds of the rock.

16. An enlargement of a part of the surface of the preceding specimen, showing the peculiar

features of the striae.

17, 18, 19. These specimens are casts of the ordinary forms of the S. perplana = S. delthyris
(Conrad), as it occurs in the Chemung group.

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PLATE 20.

Page

Fig. 1. Chonetes mtjcronata . , . . 124

1 a. Ventral valve of this species; being a small specimen enlarged to two diameters. From the

Corniferous limestone.

1 b. Ventral valve of the natural size. From the Corniforous limestone.

1 c. The specinien fig. 1 b, twice the natural size.

1 d. The profile of.fig. 1 c.

Fig. 2. Chonetes mucronata ? . 124

2. The figure is twice the natural size of the specimen; the plications strong and angular.

Fig. 8. Chonetes lineata . 121

3 a. A ventral valve natural size.

3 b. The interior of a ventral valve, with a piece of the dorsal valve attached.

3 c, d. Dorsal and ventral views of specimens twice the natural size.

3 e. An enlarged figure from the cast of a ventral valve.

3 /. A section of the two valves.

Fig. 4. Chonetes yandellana . 128

4 a, b. Dorsal views of specimens of the natural size.

4 c. A ventral view of the specimen 4 b.

4 d. A longitudinal section of the two valves.

4 e. The specimen fig. 4 a. enlarged to two diameters.

4/. An enlargement of the interior of a ventral valve.

4 g. An enlargement of the interior of a dorsal valve.

Fig. 5. Chonetes acutiradiata . 120

5 a, b. Ventral views of two individuals, one being much more convex than the other.

5 c. A profile of fig. 5 a.

Fig. 6. Chonetes hemispherica . 118

6 a, b. Ventral views of a small and a large individual.

6 c. A profile of 6 b.

6 d. A cardinal view showing the spines upon the margin.

Fig. 7. Chonetes arcttata . 119

7 a. A dorsal view of an individual.

7 b, c. Ventral views of different specimens.

7 d. A profile of 7 c.

7 e, f. Ventral and cardinal views of a cast of this species, showing the muscular impression and
apparently crenulated border caused by the spine -tubes.

Figs. 8, 9. Strophodonta callosa . 82

8. The interior of a dorsal valve, taken from a gutta-percha impression.

9 a. >A cast of the interior of the ventral valve, showing the muscular impression and the thick¬
ened border of the valve.

9 b. A cardinal view of the preceding individual. The figures are all enlarged to two diameter^.

Palaeont.X.Y.Vol .4

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PLATE 21

Page

Fig. 1. Chonetes mucronata . . 124

1 a. A ventral valve, natural size.

1 b. An enlargement of fig. 1 a, showing more distinctly the character of the spines,

1 c. A profile of the same. This form has few strong striae upon the surface.

1 d, e. A dorsal view, and an enlargement of the same, from another individual. The surface is
marked by more numerous striae than the specimens 1 a, 1 b.

1 f, g. A ventral view, and the same enlarged. This one is intermediate in number of striae
between figs. 1 a and 1 d. The above figures are from specimens from the Marcellus shale.

Fig. 2. Chonetes setigera . 129

2. a, b. The ventral valve, natural size and enlarged.

Fig. 3. Chonetes koninckiana (cited) . 136

3. This figure of a specimen of this species is given for comparison with the varieties of C.

coronata.

Fig. 4. Chonetes scitula . 130

4 a, b. Ventral and dorsal views of a specimen, natural size, of the ordinary proportions.

4 c. A ventral valve of a smaller individual.

4 d. A profile specimen of fig. 4, a, b.

4 e. An enlargement of the interior of the ventral valve.
if. An enlargement of the interior of the dorsal valve.

Fig. 5. Chonetes lepida . 132

5 a, b- Ventral and dorsal views of a large individual.

5 c. An enlargement of a ventral valve.

5 d. An enlargement of the dorsal side, showing the area and spines of the ventral valve.

5 e. An enlargement of the interior of a dorsal valve, from which the cardinal process has been

broken.

Fig. 6. Chonetes pusilla . 128

6 a, b. A ventral and- profile view of a specimen of the ordinary size.

6 c. A specimen of the same species, from the Corniferous limestone, showing an extension

of the cardinal extremities.

Figs. 7, 8. Chonetes deflecta . 126

7 a, b, c. Ventral, dorsal and profile views of an individual of the ordinary form and size.

7 d. A ventral view of an individual which is a little more transverse than the others.

7 e. An interior of the dorsal valve of the natural size.

If. An enlargement of the same, showing the muscular impressions, cardinal process, etc.

7 g. An enlargement of the interior of the ventral valve.

8 a. The dorsal valve of a specimen referred to C. gibbosa.

8 b, c. A ventral and profile view of the original of C. gibbosa, the specific distinction of which
is doubtful, as noticed under C. deflecta, pp. 126 and 128.

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PLATE 21 — Continued.

Figs. 10. (9, 11, 12.) Chonetes coronata . .

10 a, b. Dorsal and ventral views of a small individual of this species.

10 c, d. Yentral and profile views of a specimen of medium size and somewhat more than usual
gibbosity.

10 e, f. A ventral and profile view of a specimen which is more extended on the hinge line, and
a little less gibbous than the preceding.

10 g. A dorsal view, showing the area, etc., of a specimen which is unusually short on the
hinge line.

10 h, i. The exterior and interior of a large ventral valve.

10 fc. Interior of a dorsal valve of medium size, showing a quadruple germination to the cardinal
process.

10 l. Interior of a larger dorsal valve where the cardinal process has only two divisions. The
reniform muscular impression, characteristic of the genus,' is very distinctly shown. The
foregoing specimens are all from the soft shales of the formation in New York.

The following are introduced for comparison with authentic specimens of C ■ coronata .

9 a. b. Ventral and dorsal views of C. tuomeyi. These specimens and the two following
figures are from Bake-oven, Ill., the original locality of the species, labelled by Messrs.
Norwood & Pratten, and received from Dr. Norwood.

11. A ventral valve of C. maclurea.

12. Ventral valve of C. martini , partially denuded of its shell.

Page

133

Fig. 18.

Chonetes syrtalis (referred to) . . . 138 and 135

13 a, b. Exterior of shells of this species.

13 c. Casts of a ventral valve of the same.

13 d. A cast of the interior of a dorsal valve. The outline of the reniform impression is not
distinctly preserved, and in consequence presents a different expression from fig. 10 l.

PLATE 22.

Page

129 and 142

Figs. 1-5. Chonetes setigera,

1. A ventral valve enlarged to two diameters, showing two spines on each side of the apex.

2. A more transverse form of the same (natural size), the spines not being preserved. These

specimens are from the Chemung group near Meadville, Pa.

3. A specimen preserving three spines on each side of' the beak. This specimen is from Pen-

field, Ohio, and has the general features of C. setigera, but there may be some question
as to absolute identity.

4. A small individual (twice enlarged) from Painted Post, N. Y. This, and other specimens

from the same locality, are proportionally longer than the typical forms.

5. A portion of the surface striae of a specimen from the Marcellus shale, six times enlarged.

Figs. 6-11. Chonetes scitula . 130 and 141

6. A cast of the ventral valve of a very transverse specimen, twice enlarged; the spines are very

short.

7. A specimen having the base a little more rounded than is usual in this species; twice en¬

larged.

8. A specimen of the natural size; which is slightly distorted. From shales of the Chemung

group near Tioga, Pa.

9. An enlargement to two diameters from a cast, of this species, showing the muscular and vas¬

cular impressions. The specimen is. from the Hamilton group in Virginia, and has a
more rounded outline than the prevailing forms in New York.

10. A cast of this species, preserving strong marks of the surface: striae, and casts of the spine

tubes in the area. Chemung group, Cattaraugus county, N. Y. Enlarged.

1 1 . An enlargement of the area and upper portions of a specimen from the Hamilton group ; show¬

ing the area, foramen and cardinal process ; the spine tubes of the area in their inclinat ion
towards the apex of the valve, and the bases of some of the spines turning directly out¬
wards from the margin. (See pages 116 and 117.)

Figs. 12, 13. Chonetes lepida . 132 and 142

12. A specimen from the Marcellus shale, twice enlarged.

13. A specimen from the Chemung group at Forestville, six times enlarged. The specimens of

this species in the Chemung group are minute, with the striae coarser than those of
Hamilton group, but otherwise having similar features.

Figs. 14, 15. Chonetes illinoisensis (referred to) . 145

14. An individual from which the spines have been removed; natural size.

15. A specimen of somewhat different form, preserving the spines of the hinge line; twice en¬

larged. These specimens are from the shaly sandstones of Eastern Ohio, associated with
C. logani.

Figs. 16-28. Chonetes logani var. aurora . 137

16. A specimen of natural size.

17. A specimen enlarged to three diameters.

18. An enlargement to six diameters of the surface striae. The preceding figures are from

specimens in the Tully limestone of New York.

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P LATE 22 — Continued.

Page

19, 20. Specimens from tlie shales of Eastern Ohio, enlarged to three diameters to correspond
with the enlargement of the specimen from the Tully limestone.

21. A specimen of somewhat different, form from the si: rite locality as the last, enlarged to two

diameters.

22. A cast from the same locality as the last, enlarged to three diameters, showing the filling of

the spine tubes in the area.

24. A ventral view of another individual, showing the spines of the cardinal margin ; the curved

line by the side of the figure shows the convexity of the valve.

25. The interior of a dorsal valve enlarged to two diameters. These specimens usually pre¬

serve the surface marking but obscurely.

23. A dorsal view, natural size. This, with the two following figures, are from specimens

from the arenaceous beds below’ the Burlington limestone, at Burlington, Iowa.

26. A specimen from the oolitic limestone at Burlington, Iowa, in which the surface markings

are well presei-ved; natural size.

27. A portion of the surface striae of specimen fig. 26; enlarged to six diameters, for com¬

parison with fig. 18.

28. A portion of the surface enlarged t went}- -four times, showing the peculiar undulating rugae.

igs. 29-43. Chonetes mitricata . . ... 143

29,30. Impressions of the exterior of the dorsal valve of this species, one of them showing the
marks of a few surface spines.

31, 32. Impressions of the exterior of dorsal valves, with truncated apices, one of them show¬
ing the impression of the caidinal process. Both specimens show marks of numerous
surface spines.

33. A representation of the interior of the dorsal valve, obtained from an artificial cast of an

impression left in the stone.

34, 35. Ventral valves of two individuals, one of them having a truncated beak. Fig. 34 shows

a few cardinal spines, as usual in Chonetes, w'hile there are numerous smaller ones on the-
surface. Fig. 35 has a shorter hinge line, with wrinkled ears, which are studded with
spines as in Productus.

36, 37, 38. Specimens of the casts of the ventral valves having the features obscurely pre¬
served, showing three forms of the shell.

39. A cast of the ventral valve, with adhering stone, preserving impressions of the cardinal

spines.

40. A cast of the ventral valve, showing the marks of the muscular impressions very distinctly.

41. A cardinal view of the specimen fig. 35.

42. A cardinal view of the specimen fig. 38.

43. An enlargement of part of a ventral valve, combining the characters of muscular impres¬

sions, etc-, observed in several individuals.

ig. 44. Chonetes arcttata . 119

44. A cardinal view, showing the distant Slender spines. From the Corniferous limestone.

PLATE 23.

Page

Figs. 1-3, 9- 11. Productella navicella . 15(J

1, 2. Ventral views of two individuals, from the Corniferous limestone.

3. Profile view of specimen fig. 1.

9 - 11. Dorsal, ventral and profile views of a more elongated specimen, from the Hamilton
group.

Figs. 4, 5. Productella subaculeata? . 154

4. Ventral valve of a specimen, from the Falls of the Ohio, showing spine-bases and One long spine.

5. Interior of a dorsal valve of a similar character, from East Victor, New York.

Figs. 6-8. Productella spinulicosta ?=P. shumardiana . 160

6. 7, 8. Ventral, profile and cardinal views of a specimen from the Corniferous limestone near

Louisville, Ky.

Figs. 12-24. Productella truncata . 160

12. Interior of a dorsal valve, enlarged to two diameters, from the Marcellus shale.

13. An enlargement of a portion of the interior of a dorsal valve, showing the cardinal process.

14. An impression of the exterior of the dorsal valve, showing the area of both valves.

15. View of a ventral valve preserving several of the spines; from the Marcellus shale.

16. The exterior of a dorsal valve, from the limestones of the Marcellus shales.

17. A ventral valve, of small size, having the beak but slightly truncated.

18. 19, 20. Ventral, cardinal and profile views of a small individual, having a large truncation;

from the limestones of the Marcellus shales, enlarged to three diameters.

21, 22. Interiors of dorsal valves.

23. An impression of the dorsal valve, and the area and beak of the ventral valve, showing a

narrow deltidium.

24. A ventral view of a specimen which is somewhat largely truncate. Figs. 21 -24, are from

specimens from the Hamilton group. Figs. 12, 14 - 17, 21-23, are enlarged to two
diui/ieters; fig. 13 to six diameters, and fig. 24 to three diameters.

Figs. 25-34. (35-37). Productella spinulicosta . 160

(All the figures of natural size except fig. 26.)

2.5. The interior of a dorsal valve.

26. An enlargement of a portion of the above to three diameters to show the cardinal process.

27. A ventral valve of a small broad form.

28. Ventral view of an individual of larger size.

29. , Profile of the same.

30. Cardinal view of the same.

31. A smaller individual imbedded in the rock, and showing spines attached.

32. Protile view of a specimen from the Tully limestone ; probably of this species.

33. Caidinal view of the same.

34. A fragment of shale with crushed specimens of this species, preserving the slender spines.

_ 35. A ventral view of a specimen from the limestone of the Marcellus shale, which closely

resembles the P. shumardiana. from the calcareous bands below the Burlington limestone.

36.. Ventral view of a specimen of P. shumardiana , from Burlington, Iowa.

37. Profile of the same.

Figs. 38.^40. Productella bumosa . 162

38. Ventral view of a small specimen.

39. Profile of the same.

40. Ventral view of a larger specimen, showing the base of spines remaining, and the pustules

becoming elongated and assuming the form of costae. The specimen is a little crushed.

Figs. 41 -44. Productella tullia.. . 164

41. An impression of the exterior of a dorsal valve preserving the cardinal process; from the

Hamilton group.

42. A dorsal valve of larger size; from the shale of the Hamilton group..

43. A large dorsal valve from the Tully limestone.

44. An enlargement of the pustules and surface striae, as shown in. figs.. 41 & 42.

Figs. 45y 46. • Productella exanthemata . 163

45, 46. The interiors of the dorsal valves of two individuals, natural size.

Figs. 47, 48. Productella sp ? . 165

47. The interior of a dorsal valve, natural size. »

48. A profile of the same.

Fig. 49. Productella subalata . 165

49. Ventral view of an individual, from the calcareous shale at Hock Island, Illinois.

Palaeont 3T.Y.Vol.4

TDT. (E®?5®

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PLATE 24.

PRODUCTELLA RARISPINA.

Page

170

Pigs. 1-9.

1. The ventral valve of a young individual.

2, 3, 4. Three views of a,n adult individual, showing an irregular fold on the ventral valve.

5. A ventral valve, preserving two of the spines and the bases of several others.

6. A ventral valve, which is unusually symmetrical, and retains the marks of very few spines.

7. A cardinal view of a ventral valve.

8. The interior of a dorsal valve.

9. Profile of specimen fig. 8.

Figs. 10-16. PRODUCTELLA BOYDII . 169

10. The ventral valve of a young individual.

11. 12. The interior of dorsal valves, showing pustules from the indentations of the exterior.

13 - 15. Ventral valves of this species, preserving some of the spines.

16. A profile view of the specimen fig. 15.

Fig. 17-29. PRODUCTELLA HIRSUTA.. . 166

17. The ventral valve of a young individual.

18. 19. Ventral valves of large individuals.

20. An impression of a dorsal valve.

21, 22. Ventral valves preserving some of the submarginal spines.

23. A profile of the specimen fig. 22.

24. A symmetrical ventral valve with short hinge line.

25. A profile view of the preceding.

26. A large and somewhat distorted ventral valve preserving some of the submarginal spines.

27. The interior of a dorsal valve with cardinal process.

28. An enlargement of the cardinal process from fig. 27.

29. An enlargement of a portion of the surface, from a well preserved specimen.

Figs. 80-37. PRODUCTELLA HIRSUTA var. RECTISPIN A . 168

30. The dorsal valve of a small individual.

31 . A convex ventral valve.

32. A large ventral valve.

33. An impiession of the exterior of a large dorsal valve.

34. A large and somewhat distorted ventral valve.

35. A profile view of the same.

36. The interior of a large ventral valve from which the shell has been mostly removed, pre¬

serving the submarginal spines.

37. The interior of a dorsal valve from an impression in the stone.

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PLATE 25.

Figs. 1-11. Productella speciosa . . . .

1 . An impression of the exterior of a dorsal valve, showing the marks of the cardinal process.

2. The interior of a dorsal valve.

3 A profile of specimen fig. 2.

4, 5. Views of ventral valves.

6, 7. Profiles of specimens figs. 5, 8.

8. A ventral valve which is broad and depressed and strongly pustulose.

9. 10, 11. Ventral, profile and cardinal views of a very gibbous individual — the specimen from
which the original description was given.

Page

175

Figs. 12, 13. Productella exanthemata . 168

12, 13. The interiors of dorsal valves.

Figs. 14-21. Productella striatula . 177

14, 15. The interiors of dorsal valves.

16. A profile of specimen fig. 15.

17, 18. Ventral view and profile of a specimen of symmetrical form, showing scattered spine-bases.
19, 20, 21 . Ventral and cardinal view's and profile of a specimen of broader form — fig. 20, showing

the muscular impressions.

Fig. 22. Productella arctirostrata . 182

22. An exfoliated interior of a dorsal valve, referred with doubt to this species.

Figs. 23-28. Productella lachrtmosa . 172

23, 24. Impressions of dorsal valves, one with numerous pustules, and the other nearly desti¬
tute of pustules.

25, 26, 27. Ventral valves of this species; the figures 25 and 27 show some remains of spines
and elongate pustules; 26 is a broader form with fewer pustules.

28. The ventral valve of a young individual of the same species, showing numerous elongate

pustules.

Figs. 29-32. Productella lachrtmosa var. lima . 174

29. A ventral valve which is regularly convex and showing short pustules.

30. A profile of the same.

31 . A shorter and more quadrate form with a mesial depression ; the pustules very symmetrically

arranged. The specimen corresponds to the original description of P. lima, Conrad.

32. A cardinal view of the same specimen, showing the muscular markings and cavities left by
the teeth.

-41. Productella lachrtmosa var. stigmata . 174

An impression of a very large dorsal valve.

An impression of a more concave dorsal valve, showing the form of cardinal process.

A, profile of the same.

An impression of a more symmetrical dorsal valve, showing regular and larger pustules, and
also an impression of the cardinal process.

A very convex ventral yalve, showing pits left by the spine-bases.

A cardinal view of the same.

A ventral valve preserving a greater number of spine-bases.

A profile of the same.

A cardinal view of the same, showing muscular impressions.

Figs. 33 -

33.

34.

35.

36.

37.

38.

39.

40.

41.

Palseont iST.Y.Yol.4

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PI. 25.

( BRACHIOPODA.)

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PLATE 26.

Productella hystricula

Page

178

Figs. 1-8.

I, 2. Impressions of dorsal valves, one of them showing the truncate apex, and both of them

showing the marks of the narrow linear area.

3. 4, 5. Casts of ventral valves, the curved lines showing the relative convexity of the speci¬
mens.

6. A restored specimen, showing the spines as preserved in impressions in the sandstone.

7. The interior of a dorsal valve enlarged to two diameters, showing the form of the cardinal

process and the small dental sockets.

8. A cardinal view of a cast of a ventral valve, showing the narrow area and bilobed apex; en¬

larged to two diameters.

Figs. 9-15. Productella costatula . 180

9. The interior of a dorsal valve, with an enlarged cardinal process from another individual.

10. A front view of the ventral valve of a narrow individual, showing elongate pustules at the
bases of the spines, but with no continuous costae.

II, 12. The front view, and profile of an older individual, showing continuous costae.

13 - 15. Front view, profile, and cardinal view of another individual, showing continuous costae.

Figs. 16-23. Productella arctirosTrata . 18^2

1G, 17. An impression of the exterior of a dorsal valve, with profile of the same.

18. the impression of a dorsal valve, showing strong concentric wrinkles, with an impression of
the cardinal process; having fewer pustules on the surface than fig. 16.

19-21. Front, profile and cardinal views of a ventral valve, of the same variety of form and •
surface marking, as fig. 16.

22,23. Two views of the typical specimen of this species; the ventral valve is distorted
to some extent, but the mesial depression is apparently a natural feature. .

Figs. 24-28. Productella bialyeata . 183

24. A small specimen of a ventral valve, showing numerous concentric wrinkles, with a greater

number of spines towards the front than usual in specimens of this species.

25. A young individual, with inconspicuous wrinkles, and a well defined mesial sinus.

26. A larger individual, which is nearly destitute of a sinus.

27. A larger individual, with distinct wrinkles and spine-bases on the cardinal margin, with a few

similar marks on one. side, in front; the mesial sinus is but faintly developed.

28. An imperfect specimen, with faint concentric wrinkles and numerous spiniferous tubercles

near the front; the sinus is strongly developed.

Figs. 29-42. Productella onusta . 184

29. The interior of the dorsal valve of a young individual, showing the cardinal process and

socket ridges.

30. The interior of a large dorsal valve, showing concentric wrinkles, the cardinal process and

median septum, with the muscular and vascular impressions.

31. The interior of a dorsal valve from which the shell is partially exfoliated ; the cardinal pro¬

cess is much stronger than in fig. 30.

32. A cardinal view of the specimen tig. 31, showing the convexity of the inner surface.

33. A fragment of a large dorsal valve, showing the termination of the reniform vascular impres¬

sion on one side, with an oblique vascular impression diverging on each side from the
termination of the mesial septum. The outline is restored to show the relation of the
parts preserved.

34. A dorsal valve which has been doubtfully referred to this species; it is nearly flat, with a

few obscure wrinkles, and a cardinal process similar to others of this species.

35. The ventral valve of a young individual.

36. 37, 38. Ventral and cardinal views, and profile of a large ventral valve of this species.

39, 40. Cardinal views of casts of two ventral valves, showing the muscular markings, and in
39, the deep pits on the sides of the beak left by the removal of the dental lamellae.

41 . An enlargement of the surface of the shell, showing round spine-bases, and irregular lines of

growth.

42. An enlargement of the surface of the cast of a ventral valve, showing the irregular striation

and distant puncta.

Pala-onl N .Y.Vol.4

l?1.26.

SSHWSf© ME!!..

( BHAC'HllH'ODA.)

S..P.mitfieli,3e:

Swiaton., lith. .

■

PLATE 27.

Figs. 1-4. CYRTINA, HAMILTONENSIS . .

1, 2. Views of casts of a dorsal and a ventral valve, from the Schoharie grit, the latter
showing the line of the medium septum.

3, 4. Front and cardinal views of a ventral valve from the Corniferous limestone, the latter
view showing the covered deltidium.

Page

Figs. 5 - 10. Cyrtina biplicata . 266

* 5, 6, 7. Dorsal, cardinal and front views of an individual of this species, from tlite Schoharie grit.

8. A ventral valve of a specimen from Michigan.

9, 10. Ventral and cardinal views of the original specimen of this species.

Figf. 11-12. Cyrtina crassa . . . . ? 267

11, 12. Dorsal and ventral views of a specimen of this species from the Corniferous limestone.

Figs. 13 - 16. Spirifera duodenaria . . . . . . 189

13. A young individual, which is a partial cast.

14. A ventral valve of this species.

15. The cast of a dorsal valve.

16. The cast of a ventral valve. These specimens are all from the Schoharie grit.

Figs. 17-28. Spirifera macra . 190

17. A young individual of this species.

18. A full grown specimen retaining the shell. The extremities are restored from other speci-

19, 20, 21. Dorsal, cardinal and profile views of a specimen retaining a portion of the shell.

22. A cast of a large dorsal valve.

23 . A cast of a ventral valve.

24. A cardinal view of a cast of the ventral valve.

25. The cast of a ventral valve of a small individual of this species. ?

26. 27. Dorsal and ventral views of an individual which is less extended on the hinge line than

the usual form. The specimen is somewhat weathered.

28. Profile of the above.

Fig. 29. Spirifera grieri..^ . . . 194

29. A dorsal view of a crushed specimen, from the Schoharie grit.

Figs. 30-34. Spirifera raricosta . 192

30. The ventral valve of an exfoliated shell.

31. The cast of a dorsal valve, showing the teeth sockets and median septum.

32. The cast of a ventral valve, showing the muscular impressions, central septum, and filling

of the rostral cavity.

33. 34. Ventral views of two young specimens, referred with doubt to this species.

Palaeont A' .Y.Yol .4

PL 2 1.

Schoharie Grit.a-nd. C ornil'exoirs Limestone.
( B'RACHIOPODA.)

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PLATE 28.

Page

Figs. 1-11. SPIRIFERA GREGARIA . 195

1. Dorsal view of a young individual.

2. A dorsal view of a specimen of the ordinary size and form.

3-6. Ventral, dorsal, profile and front views, of a large and gibbous form.

7, 8. Interiors of ventral valves. These specimens are from the Falls of the Ohio. -
9, 10. Dorsal and cardinal views, of a cast of this species in chert, from Indiana. This speci¬
men shows a distinct depression in the mesial fold which is not a usual feature.

11. The interior of a ventral valve and part of a dorsal, showing the crura and the last turns
of the spire. From the Falls of the Ohio.

Figs. 12-16. Spirifera Formosa . 220

12 - 16 Dorsal, cardinal, profile, front and ventral views of the typical specimen of the species.

Figs. 17 -23. Spirifera grieri . 194

17 - 20. Four views of a specimen of small or medium size.

21. A dorsal view of a large specimen, showing several plications on the mesial fold.

22. A ventral valve, where the hinge is much extended, and the plications are less defined in the

mesial depression.

23. A front view of the specimen fig. 21.

In the collections of the Canadian Geological Survey, there is a specimen of this species
of much larger size than those observed or figured among the New York collections.

Figs. 24-33. Spirifera duodenari a. . . . . 189

24. 26, 29, 30, 31. Dorsal, ventral, front, cardinal and profile views of a well formed and char¬

acteristic specimen of medium size.

25. 28, 32. Dorsal, ventral and profile views of a more gibbous form.

27. Ventral view of a large individual.

33. The interior of a small ventral valve.

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PLATE 29.

Figs. 1 - 8. Spirifera oweni . . .

1. Dorsal view of a young specimen.

2. Dorsal view of a larger individual.

3-7. Dorsal, ventral, cardinal, profile and front views of a specimen of ordinary size and char¬
acteristic form.

8. Interior of a part of a ventral valve.

Page

197

Fig. 9-18. Spirifera acuminata . 198

9. Front view of a young individual, from New York.

10 - 13. Dorsal, ventral, cardinal and profile views of a specimen of ordinary size and form,
from near Sandusky, Ohio.

14. Front view of a small hut extremely elevated specimen, from Williamsville, N. Y.

15. Cast of a ventral valve, showing the muscular impression of greater width than usual; from

Albany county, New York.

16. 17. Yentral and cardinal views of a cast in chert, from Camp Creek, Ind., showing muscu¬

lar impressions, dental cavities, etc. The mesial elevation has been injured by weather¬
ing, and the outline shows the probable extent of the elevation.

18. Dorsal view of a specimen from the same locality as the preceding, showing the peculiar
muscular markings of the dorsal valve.

PaUvoni x.Y.Voi.-k WIP 3P3E2E lESM 5E 3R3B3E Hi S> ©■jE'roS1, pi.2<.>.

C ornifertnrs limestone.

( BHACHtOPODA.)

B..P .'Whitfid.i ,3 el.

Smin-tcm., littu.

PLATE 30.

Page

Figs. 1-9. Spirifera raricosta . . 192

1. A dorsal view of a young specimen.

2. A dorsal view of a larger individual preserving a portion of the shell.

3-6. Dorsal, ventral, profile and front views of a specimen which is very short upon the hinge
line and of very gibbous form, with less than the usual number of plications.

7. A ventral valve which is very much extended on the hinge line, presenting much the appear¬

ance of S. perlamellosa.

8. A front view of a specimen, showing the elevation of the fold.

9. The interior of a ventral valve which is much rounded on the cardinal extremities.

Figs. 10-15. Spirifera disparilis . 204

Compare with S. pyxadatus, of the Oriskany sandstone.

10 - 12, 14. Dorsal, ventral, profile and front views of a specimen of ordinary character.

13. Cardinal view of another individual, showing the area and foramen.

15. Dorsal view of a larger specimen, showing stronger lateral plications. The figures are all

enlarged to two diameters.

Figs. 16-20. Spirifera macrothyris . 202

16. Dorsal view of a large specimen showing the area and foramen of the ventral valve. The shell

is almost entirely removed, leaving a partial cast on the dorsal side.

17. A large imperfect ventral valve.

18. A cardinal view of another specimen, showing the foramen and the striated cardinal area.

19. Cardinal view of a young individual, showing a more elevated and sharper mesial fold.

20. A partial cast of the ventral valve, showing the filling of the large muscular imprint.

Fig. 21. Spirifera unica . 208

21. An imperfect ventral valve. There is a strong probability that this is identical with S.

arenosa, of the Oriskany sandstone.

Palaeont X.Y.Vol.4

il.3 0.

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( BRACHIOPODA.J

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PLATE 31.

Page

Figs. 1-4 Spirifera varicosa . . . '. . 205

1, 3,4. Dorsal, ventral and cardinal views of a specimen of the ordinary size and form of those

from the Falls of the Ohio.

2. Dorsal view of another individual, showing a more strongly rugose surface. From the same

locality as the preceding.

Fig. 23. Spirifera varicosa var . 206

23. A ventral valve with the hinge line much extended, from Western New York.

Figs. 5-8. Spirifera segmenta . 207

5-8. Dorsal, ventral, cardinal and profile views of the original specimen of this species, from
the Falls of the Ohio.

Figs. 9, 10. Spirifera arctiseqmenta . ' . 208

9, 10. Dorsal and cardinal views of the original specimen.

Figs. 11-13. Spirifera euruteines var. fornacula . 211

11-13. Dorsal, ventral and cardinal views of a specimen from Bake-oven, Illinois.

Figs. 14-19. Spirifera euruteines . 209

14-17. Yentral, cardinal, profile and dorsal views of a specimen of ordinary size and form.

18. The interior of a ventral valve containing the spires, which are covered with chalcedony.

19. A cardinal view of a young individual.

Figs. 20 - 22, 24- 30. Spirifera manni . 211

20-22. Dorsal, cardinal, and front views of a characteristic specimen, from near Sandusky, Ohio.

24, 25. Dorsal and cardinal views of an imperfect specimen, from Williamsville, New York.

26 - 30. Dorsal, ventral, cardinal, front and profile views of a large imperfect specimen from N.

York, which is much more extended laterally than the usual form.

Palaeont X.Y.Vol .-l-.

JP1.31.

B..P.-WMtfmia-,ael.

SIC. . . . . . . . AT/.‘U;iA yxr /

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Figs. 1-9.

PLATE 32.

Spirieera diyaricata . .

Page

213

1. An imperfect dorsal valve of this species. From the Corniferous limestone.

2-6. Ventral, dorsal, profile, front and cardinal views of a large and very perfect specimen, from
the shales of the Hamilton group.

7. An enlargement of the surface, showing the bifurcating plications and the concentric striae.

8. Still further enlargement, showing the rugose character of the concentric striae.

9. The cast of a ventral valve, from the Corniferous limestone.

I’aleeont'KY. Vol.4.

PL. 32.

(BRACHIOPODA.I

. .is: - 1

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Hi ' ; ■

PLATE 33.

Spirifera eimbriata . .

Page

214

Figs. 1 - 21.

1. An imperfect dorsal valve of this species, from the Orisltany sandstone.

2. A view of an imperfect ventral valve of this species.

3. The cast of a ventral valve, showing the muscular impression.

4. A view of a cast of a dorsal valve. This, and the two preceding figures, are from speci¬

mens found in the Schoharie grit.

5. 6. Dorsal and ventral views of a small individual, from the Corniferous limestone.

7. A dorsal view of an individual of medium size, from the Corniferous limestone.

8-11. Profile, dorsal, ventral and front views of a full grown individual, from the Corniferous
limestone.

12, 13. Dorsal and ventral views of a small individual.

14. Cardinal view of a short individual of this species.

15. A ventral view of another specimen which preserves the fine setiform spires of the surface.

16 - 19. Profile, front, dorsal and ventral views of a large sized specimen. Figures 12 - 19

are from specimens from the soft shales of the Hamilton group.

20. A cardinal view of a cast of this species, from the Hamilton group, Hardy county, Ya.

21. Enlargement of the surface of specimen fig. 18, showing the pustulose markings.

Figs. 22 - 30. Spirifera sttbumbona . 234

22. 23. Dorsal and profile views of a specimen of this species.

24. Dorsal view of another individual.

25-29. Dorsal, ventral, profile, cardinal and front views of a large and rather gibbous specimen.

30. Enlargement of the surface, showing the small pits that result from a partial exfoliation of

the shell. These figures are from specimens occurring in the limestones of the Marcellus
shales.

Figs. 31-35. Spirifera prematura . 250

31. A ventral valve of a small individual.

32. A larger dorsal valve, showing the pustules of the surface. This, and the preceding figure

are from New York specimens.

33. Cast of another dorsal valve, showing the impression of the median septum.

34. Yiew of the cast of a ventral valve.

35. Cast of ventral valve of another individual, having a much larger rostral cavity. This, and

the two preceding figures, are from specimens occurring near Meadville, Pa.

Paleeont JSTTrVol.4.

W. MIS IL D ISSKiHB ISMOoIE JMnnLTP (DM © CHnBMWSf ©■ ©IB?S

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PLATE 34.

Figs. 1 - 23. Spirifera mucronata .

1, 2, 4. Dorsal valves, showing variations in the extension of the cardinal extremity.

3. Ventral valve of a specimen from the Marcellus shales, very much extended on the hinge line.
5, 6, 7. Dorsal, ventral and profile views of a specimen of medium size and ordinary form.

8. Dorsal view of a specimen in which the hinge line is not extended.

9. Dorsal view of a specimen which is extended on the hinge-line, so as to give a triangular form to

the shell.

10. Dorsal yiew of an individual, having a semicircular outline.

11. Ventral view of a large and well preserved individual of ordinary form, showing a

deeply impressed line on the mesial fold, with a corresponding plication in the sinus.

12. Dorsal view of the above.

13. Profile of the same.

14. Cardinal view of the same.

15. Ventral view of a specimen where the hinge-line is considerably extended.

16. Dorsal view of a specimen from the arenaceous shales, in which the cardinal extremities are

greatly extended.

17. Ventral view of another specimen of the same character.

18. Front view of a specimen of ordinary form.

19. Ventral view of a short gibbous form with an angular mesial fold and sinus. This form

approaches in character, S. ziczac.

20. Dorsal view of same.

21. Front view of same.

22. Interior of ventral valve.

23. Interior of dorsal valve.

Page

216

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PLATE 35.

Spirifera tullia .

Page

218

1-3. Views of dorsal valves, one of them showing rugose markings on the plications.

4. A ventral valve of the ordinary form.

5. Cardinal view of a ventral valve, showing area and foramen.

6. View of a ventral valve, having the cardinal extremities unusually extended.

7. 8, 9. Casts of ventral valves of this species, showing great variations in the rostral portions

of the shell.

Figs. 10 - 14. Spirifera sculptilis . 221

10. Dorsal valve of this species, from which the shell is partly exfoliated".

11. View of the ventral valve, showing the strong concentric ridges.

12. Cardinal view of the ventral valve, showing area and foramen.

13,14. Dorsal and ventral views of a specimen, which is with doubt, referred to this species — •
the concentric ridges being more closely arranged and finer than in the preceding figures.

Figs. 15-23. Spirifera ziczac . . . 222

15. Dorsal view of a small individual.

16, 17. Dorsal and ventral views of an individual of ordinary size.

18 - 22. Dorsal, ventral, profile, front and cardinal views of a large and well preserved individual.

23. Interior of ventral valve, showing the extension of the dental lamellae into the body of the

shell.

Figs. 24, 25. Spirifera acuminata . . ._ . * . 234

24. Dorsal valve of this species, showing the bifurcating plications and the angular mesial fold.

25. Cast of a ventral valve, showing the strongly marked muscular impression and the filling

of the rostral portions of the shell.

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PLATE 36.

Figs. 1-13. Spirifera granulifera .

1. Dorsal view of a small individual.

2. Cardinal view of the same, showing great height of area.

3. Profile of same.

4. Ventral view of another specimen, showing an angular mesial sinus.

5. Ventral view of a well preserved and perfect specimen of the ordinary size.

6. Dorsal view of the same.

7. Profile of same, for comparison with fig. 3.

8. Front view of same.

9. Ca/dinal view of the same.

10. Dorsal view of a larger and less gibbous specimen, showing more of the ventral area.

11. View of the interior of a dorsal valve, showing the muscular impressions, area and dental

sockets.

12. View of the interior of a ventral valve, showing the muscular impression, cardinal area,

and the callosity within the apex of the foramen.

13. Enlargement of a part of two plications, showing the granulose structure of the surface.

Page

223

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PLATE 37.

Figs. 1-4. SpiRIFBRA GRANIJLIFERA var. CLINTONI.

1. Dorsal view of a small individual.

2. Yentral view of the same.

3. Profile of the same.

4. Yentral view of a much larger specimen.

Fig. 9. Spirifera medialis ? .

9. Dorsal view of a young specimen, doubtfully referred to this species.

Page

228

Figs. 10-20. Spirifera marcyi . . 226

10. Dorsal view of a small individual of this species.

11. Yentral view of the same.

12. Cardinal view of the same.

13. Dorsal view of an unsymmetrical specimen of gibbous form, showing the area and foramen.

14. Yiew of a ventral valve of another individual.

15. Ventral view of a more extended form. The front of the shell is shortened by crushing.

16. Profile view of specimen fig. 13, showing the great rotundity of the dorsal valve.

17. Interior of a dorsal valve, showing the cardinal process and dental sockets.

18. Enlargement of surface, showing the elongated pustulose markings characteristic of this

species.

19. Cardinal view of'an individual, which is imperfect at the extremities. The valves are less

gibbous than in fig. 16.

20. Interior of an imperfect ventral valve, showing the broad muscular impression.

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PLATE 38.

. 1-25. Spirifera medialxs . . . .

1. Dorsal view of a small and very symmetrical specimen.

2, 3. Dorsal and cardinal views of a larger specimen, having the extremities of the hinge line

extended; fig. 3, shows the cardinal area and foramen.

4-6. Dorsal, cardinal and profile views of a more ventricose specimen, with a narrow incurved
area and strong concentric lines of growth.

7, 8. Dorsal and cardinal views of a specimen of medium size, having a higher area, which is
but slightly incurved.

9-11. Dorsal, profile and ventral views of a specimen having a high area and a semicircular
dorsal valve.

12, 13. Dorsal and cardinal views of a specimen of slightly Unsymmetrical form and rather
strong ribs.

14-16. Dorsal, front and ventral views of a large specimen., having a small area and
slightly projecting ventral beak.

17 - 20. Dorsal, ventral, front and profile views of another specimen corresponding in size with
the last, but having a higher area, more projecting ventral beak, and higher mesial fold,
presenting a strong contrast between figs. 17 and 14, and between 19 and 15.

21, 22. Cardinal views of two individuals with high areas, showing considerable variation
in the proportions of the deltidium; contrasting strongly in these respects with fig. 13.

23, 24. Interiors of dorsal valves, showing the muscular impressions, socket plates, etc.

25. Interior of a ventral valve, showing the muscular impression, cardinal area, teeth, and the
eallosity filling the apical portion of the deltidial opening.

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PLATE 38 a.

Page

Figs. 1-22. Spirifera macronota . 281

1-3. Dorsal, ventral and profile views of one of the smallest specimens which have been
satisfactorily recognized as belonging to this species.

4-6. Ventral, cardinal and profile views of a specimen of medium size, with a high area and
stronger plications than is usual in the species.

7 - 10. Dorsal, front, ventral and cardinal views of a somewhat characteristic specimen. The
dorsal valve has been slightly crushed, giving a little less rotundity to the shell than
natural.

11, 12. Ventral and cardinal views of a very characteristic ventral valve, showing the typically
fine plications, shallow sinus, and vertical area.

13. Cardinal view of a large individual, having a very high area, and preserving the covering of

the foramen in place. The specimen is somewhat crushed, giving an appearance of
greater rotundity to the dorsal valve than natural.

14. View of a large dorsal valve possessing the characteristic form, with the fine plications.

15. Cardinal view of specimen fig. 14, showing the high vertical area and narrow deltidium.

16. Profile of specimen figs. 7 -10, contrasting somewhat with fig. 6, in the height of area and

proportional depth of the valves.

17. 18. Views of two characteristic dorsal valves, showing considerable variation in outline.

19. Cardinal view of a ventral valve, showing a much lower area than figs. 5, 10, 12 and 15.

This, and figures 10 and 15, show the callus within the foramen extending to varying
distances from the apex in the different individuals.

20. Interior of a dorsal valve, showing the dental sockets, cardinal process, and muscular impres-

21. Interior of the ventral valve, fig. 19, showing the muscular impression and dental plates.

22. Interior of a smaller ventral valve, showing muscular impression, dental lamellse, etc.

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PLATE 38*.

Spirifera medialis . .

Page

227

Figs. 1 - 11.

1. Dorsal valve of a small specimen, with extended cardinal extremities and fine plications.

,2-4. Dorsal, ventral and cardinal views of an extended form, having a high, nearly vertical,
cardinal area and narrow deltidial opening.

5, 6. Dorsal and cardinal views of a specimen of medium size, having fine plications, a high
area, and extended cardinal extremities.

7 . Dorsal valve of a specimen having a triangular form, from the great extension of the hinge
line. This is a somewhat unusual form.

8-11. Dorsal, ventral, cardinal and profile views of a narrow ventricose form, having a semi¬
circular outline, and a high, almost vertical area. The surface is strongly marked with
concentric lines of growth.

Figs. 12-18. Spirifera medialis var. eatoni . 229

12-15. Dorsal, profile, cardinal and front views of a specimen of medium size and ventricose
form, characteristic of this variety.

16-18. Dorsal, cardinal and front views of a larger and somewhat unsymmetrical specimen.

"Figs. 19-22. Spirifera medialis var . 227

19. Cardinal view of a ventral valve with a high vertical area.

20. Cardinal view of a still narrower form which is somewhat distorted. The area is vertical

and the foramen very narrow.

21. 22. Ventral and cardinal views of an exfoliated specimen, having very fine plications and

high area, which is somewhat receding towards the apex; from limestone in the Hamil¬
ton shales, at Eighteen Mile Creek, shore of Lake Erie.

Figs. 23-32. Spirifera angusta . 230

23, 24. Dorsal and ventral views of a young individual of a short form.

25-27. Dorsal, ventral and cardinal views of a larger specimen, having the hinge line more
extended.

28-31. Dorsal, ventral, cardinal and profile views of a large specimen with extended cardinal
extremities and a high sloping area.

32. Ventral view of a cast of a specimen with a short hinge line and rounded front margin. The
mucronate extensions of the hinge are so nearly solid that the filling of these portions of
the shell is rarely preserved in casts, and owing to the loss of this part they appear to
have a shorter hinge line.

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PLATE 39.

1-12. Spirifera l^evis .

1. View of a cast of a dorsal valve of a small individual.

2. Cast of a ventral valve .of a small individual, showing the muscular impression.

3. Dorsal view of an imperfect specimen, showing the ventral area, and the deltidium in place.

4. Cast of a dorsal valve of a large individual.

5. Cardinal view of a ventral valve, showing the deltidium in place.

6. Interior of a ventral valve, showing the area, muscular impression, with the deltidial plate.

covering the upper part of the foramen.

7. Exterior of a large ventral valve preserving the shell and showing a remarkably wide suban-

gular sinus, with obscure plications on the sides of the shell.

8-11. Casts of ventral valves, showing considerable variation in the size and proportions of
the muscular impression.

12. Cardinal view of a cast of a ventral valve.

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Figs. 1 - 18.

PLATE 40.

Spirifera mesacostalis.

Page

240

1, 2. Dorsal and ventral valves of small individuals, from Ithaca, N. Y., which do not possess
the plication in the sinus. .

3. Dorsal valve having the cardinal extremities very much extended. This is the form origi¬

nally described in the Fourth District Rept., as Spiri/era acuminata.

4. Dorsal valve, showing the character of the species.

5. Ventral valve, having the general characters of Spirifera mucronata, but possessing the pli¬

cation in the mesial sinus.

6. View of the dorsal valve having the mesial fold composed of three equal plications.

7-9. Ventral valves presenting the ordinary characters of the species, but showing consider¬
able variations in the cardinal extremities.

10. 11. Casts of ventral valves of this species.

12, 13. Cardinal view of ventral valves, showing considerable variation in the height of area.

Figs. 14 - 22. Spirifera mesastrialis. . . . 242

14, 15. Dorsal valves of small individuals.

16, 17. Dorsal valves of larger individuals, having the cardinal extremities rounded or but little
extended.

18. Dorsal valve of a specimen of this species, having the cardinal extremities greatly extended.

19-21. Ventral valves, showing some variation in the extent of the cardinal extremities.

22. Enlargement of surface, showing the striated plications, and in one part the fine concentric
striae which cancellate them. The latter feature is only seen on the most perfectly pre-
served specimens.

(Figs. 16, 18, 19, 21, were intended to show fine striations on the sinus, but these unfor¬
tunately are only shown upon the early impressions.

Faleeont XT. Vol t.

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PLATE 41.

Page

'igs. 1-19. Spirifera disjijncta . 24 %

(The references to this plate on page 246, should be to plate 42.)

1-3. Views of small individuals with short or rounded extremities.

4. An individual with the cardinal extremities much extended.

5-9. Specimens showing some variations in the extent of the cardinal line, but all possessing
a simple mesial fold.

10 - 16. Specimens showing variations in the form of the valves having a double mesial fold-

17. Cast of an individual preserving both valves, with cardinal extremities extended, the

mesial fold being narrow and angular.

18. Profile view of specimen, fig. 17, showing the gibbosity of the valves.

19. An individual with extended cardinal extremities, and a broad rounded mesial fold.

(The figures on this plate are all dorsal views.)

Palaeonl JT.T.Vol.4

P141.

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( BRACHIOPODA.)

E..P .'Whitfield. ,3 el

Page

243

(The references to this plate, on page 240. should be to plate 41.)

1. A small narrow form retaining the shell.

2. A cast of a young individual.

3. Cast of a valve of usual form.

4. 5. Valves of small forms, having the cardinal extremities short and rounded? the latter

figure showing the extension of the dental lamellae nearly to the front of the valve.

6. Cardinal vievv of a specimen having a very high area and wide foramen..

7, 8. Forms in which the cardinal area and foramen are proportionally narrow.

9. 11. Individuals of the prevailing form retaining the shell.

10. Cast of a broader form.

12, 14, 15. Specimens showing extreme variation of muscular impressioto.

13,19,20. Individuals showing great extension of the cardinal extremities. Spirifera {Del-
thyris ) perlata, Conrad. D. cuspidata, Hall.

16. Cardinal view of the specimen, fig. 15, showing short thickened dental lamella?.

17. ' Cast of a small individual, showing dental lamella? extending to the front of the valve.

18. Interior of a specimen preserving a portion of the shell and showing the form of the mus¬

cular impression.

(The figures on this plate are all ventral valves.)

PLATE 42.

Spirifera disjuncta . . . .

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PLATE 43.

Page

248

Figs.. 1-8. SpIRIFERA ALTA . .

1-3. Casts of dorsal valves, showing the extent of area, dental cavities, and muscular impres¬
sion.

4, 5. Two views of a cast of a ventral valve, showing the muscular impression and sinuate out¬
line of the valve in front.

«, 8. Cardinal views of a ventral valve taken from gutta-percha casts, from natural moulds,
showing a partial closing of the triangular foramen by shelly matter, which is not the
true deltidial plate.

7. Cardinal view of a cast of a ventral valve, showing the cavities left by the removal of the den¬
tal lamellae, and the concave impression of the inner surface of the shelly plate, which
partially closed the foramen.

Pala-ont ITT.Vol.4i

©>m®wipa

PE 43'

.

PLATE 44.

Page

Figs. 1-6. Amboocelia prahumbona . . 262

I, 2. Dorsal valves of specimens of the ordinary size and form.

3. 4. Ventral and profile views of the ordinary form.

5. Ventral view of a narrow elongated individual, which is notan uncommon form in some

localities.

6. View of a cast of a ventral valve, showing muscular impression and pustulose markings of

the central portions of the shell; enlarged to two diameters.

Figs. 7-18. Amboocelia umbonata . J... . . . . 259

7 -10. Dorsal, ventral, profile and cardinal views of a large and well preserved individual, pos-
sessingall the ordinary features of the species.

II, 12. Interiors of dorsal valves.

13. Interior of a well preserved ventral valve.

14, 15. Enlarged to three diameters from figs. 11 and 12, to show the variations in the cardinal

processes, dental sockets and muscular impressions.

16. An enlargement to three diameters, of specimen fig. 13, showing the cardinal area, trian¬

gular foramen and teeth.

17. Ventral view of a specimen, showing the internal spires; enlarged to two diameters.

18. View of a specimen, from the Marcellus shales. This is the form originally des¬

cribed as Amboocelia (Orthis) nucleus ; enlarged to two diameters.

Figs. 19-25. Amboocelia umbonAta var. gregaria, . 261

19. Dorsal valve; enlarged to two diameters.

20. 21. Ventral and profile views of a specimen preserving the shell.

• 22. Cast of a dorsal valve.

23. Cast of a dorsal valve of another individual, enlarged to two diameters to show muscular

impressions and cavities left by the removal of the cardinal process.

24. Cast of a ventral valve.

. 25. Cardinal view of the cast of a ventral valve.

Figs. 26-33, 88-52. Cyrtina hamiltonensis . . 268

26-30. Dorsal, ventral, cardinal, profile and front views of a large individual as it occurs iii
the State of New York.

31, 32. Dorsal views of two individuals, which show a variation in the number of plications.

• 33. Dorsal view of a specimen which has the beak of the ventral valve strongly curved laterally.

38-40. Dorsal, ventral and profile views of a large specimen, from Canada West, showing a
strongly curved beak, the foramen covered by the pseudo -deltidial- plate which is perfo¬
rated in the upper part.

41, 42. Dorsal and ventral views of a still larger specimen, from the same locality with the
last. This specimen also shows the perforated pseudo-deftidial plate.

43. Interior of a dorsal valve; enlarged to two diameters.

44. A still further enlargement of the hinge portions of specimen, fig. 43, to show the cardinal .

process, dental sockets, etc.

45-47. Dorsal, ventral and cardinal views Of an internal cast, showing the muscular impression
and cavity left by removal of the mesial septum and dental lamellae; figures enlarged to
two diameters.

48. Longitudinal section, showing the dental lamellae of one side and the form and extent of

the mesial septum of the ventral valve.

49. A transverse section through the middle of the ventral valve, showing a section of the

spiral cones, and of the dental lamellae .and their junction with the mesial septum.

50. Enlargement of an individual, from the Corniferous limestone at the Falls of the Ohio,

showing the mesial septum extending from the beak to the centre of the valve, and also
the spiral cones with their apices directed into the rostral cavity of the ventral valve.

51. Dorsal view of a specimen of this species, from Independence, Iowa.

52. Enlargement, showing the pustulose character of the surface.

Figs. 34-37. Cyrtina hamiltonensis var. recta . . 270

34 -36. Dorsal, ventral and cardinal views of a specimen of this variety, from the Hamilton
group.

37. A ventral view of a specimen of this form, . from the Chemung group.

Figs. 53-55. • Cyrtina curvilineata?. . . . . . 270

53-55. Dorsal, ventral and profile views of the specimens described.

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276

1. A ventral view, natural size.

2-4. Dorsal, ventral and profile views of a specimen of the prevailing form; enlarged to two
diameters.

5. Dorsal view of an individual of an elongate form, in which the sinus of the dorsal valve

is more strongly marked than usual (enlarged).

6. A still further enlargement of the rostral portion of fig. 2, for the purpose of showing delti-

dial plates, foramen, etc. (The lithographer has unfortunately omitted the lines marking
the limits of the deltidial plates.)

PLATE 45.
Rhynchospira lepida..

Figs. 7-15. Trematospira gibbosa . 272

7, 8. Dorsal and ventral views of a small specimen.

9. Dorsal view of a specimen of medium size.

10-14. Dorsal, ventral, cardinal, profile and front views of a full grown individual.

15. Enlargement of the cardinal portion of a dorsal valve of this species, showing the peculiar

cardinal process and slender mesial septum.

Figs. 16-32. Trematospira hirsuta . 274

16. A dorsal view of an individual,' from the Corniferous limestone of Louisville, Ky.

17 - 19. Dorsal views of specimens, showing variations in size and development of the mesial
fold and sinus; fig. 19 being essentially destitute of these features.

20. Ventral views of a large individual.

21, 22. Dorsal and profile views of a round and gibbous specimen.

23-27. Dorsal, ventral, profile, cardinal and front views of a full grown individual.

28. Interior of a dorsal valve.

29. An enlargement of the upper part of fig. 28, showing cardinal process, dental sockets, and

bases of the crura.

30. Interior of a ventral valve.

31. Enlargement of the beak of fig. 30, showing the teeth, false area and foramen.

32. An individual having the greater part of the dorsal valve removed, showing the internal

spires and bases of the crura.

Figs. 33-57. Ntjcleospira concinna . . 279

33. Cast of a ventral valve, from the Schoharie grit.

34. 35. Dorsal and profile views of a specimen, from the Upper Helderberg limestone.

36, 37. Dorsal views of small individuals, from the Hamilton group; the latter preserving the
fine hair-like setae on a part of the shell.

38, 39. Dorsal and profile views of a specimen where the valves are of nearly equal depth.

40.41. Dorsal views of flattened specimens which preserve the fine setae very beautifully.

42-46. Dorsal, ventral, profile, cardinal and front views of a large and well preserved speci¬
men where the valves are of unequal depth.'

47, 48. Interior and profile views of a dorsal valve, showing the size and form of the cardinal

process. *

49.. Enlargement of the cardinal process, showing the small elevated pad for the attachment of
the cardinal muscles, the dental sockets, and the points for the attachment of the crura.

50. Interior of a ventral valve.

51. Enlargement of the beak of the ventral valve, showing the teeth and false area.

52. View of a specimen showing the spires.

53. 57. The internal cast of a dorsal and a ventral valve; enlarged to two diameters.

54. The cast of a ventral valve of the natural size.

55. 56. The casts of dorsal valves, of the natural size, showing some variation in the form and

markings.

58. Enlargement of the surface, showing the fine set®, and the bases of others which have
been broken away, giying a minutely pustulose surface. It is this feature which
gives the apparent punctate texture to the surface of these shells.

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( BRACHIOPODA.)

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PLATE 46.

Athyris yittata .

Page

289

Figs. 1-4.

1-4. Dorsal, ventral, profile and front views of a specimen from the Falls of the Ohio, pre¬
senting the ordinary characters of the species.

In the description of the internal spires of this species, page 290. the letter h is used to indi¬
cate the junction of the intercalated lamellae, but was accidently omitted from the
figure on page 289. The corrected figure is therefore inserted in this place.

Athyris Vittate.

Figs. 5-31. Athyris spiriferoides . .

5. A small individual without mesial fold or sinus.

6, 7. Yiews of small specimens, of ordinary form, in which the fold and sinus are partially

developed.

8 A larger specimen, showing a strongly lamellose surface.

9. Dorsal view of a laterally expanded specimen.

10, 11. Dorsal views of rounded gibbous forms.

12. Dorsal view of a specimen of the ordinary form and of medium size.

13. Dorsal view of an extremely broad individual.

14. Front view of specimen, fig. 13, showing extreme elevation in front.

15-19. Dorsal, ventral, cardinal, front and profile views of a well defined and moderately
gibbous form.

20-24. Dorsal, ventral, cardinal, front and profile views, of a rounded, gibbous and thickened
shell.

25. Dorsal view of a large specimen, showing a strongly lamellose surface.

26, 27. Interiors of a dorsal and a ventral valve, showing hinge structure and muscular im¬

pressions.

28, 29. Dorsal and ventral views of an internal cast of this species, from the Hamilton group,
Hardy county, Ya., showing very distinctly the impressions of the muscular markings.

30. Yentral view of a cast from the same formation in Hew York, showing the muscular and

vascular markings in a still more perfect state.

31. A specimen, which has been cut to show the spires. The intercalated lamellfe are not seen

in this view. (See page 284 and plate 47, fig. 8.)

285

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PLATE 47.

Page

Figs. 1-7. Athyris cora . . 291

1, 2. Dorsal and ventral views of a small and well preserved specimen.

3-7. Dorsal, ventral, profile, cardinal and front view's of a full grown and perfectly formed
specimen ; the shell is somewhat exfoliated, and does not show the exterior surface char¬
acters.

Athyris spiriferoides. . . . . . .. . ... 285

The ventral side of the specimen fig. 31, pi. 46, showing the intercolated lamellae of the
spires near the upper part between the cones.

Figs. 9-20. Athyris angelica . 292

9-13. These figures are from specimens which preserve the external shell and surface charac¬
ters, and illustrate the great variety of form presented by this species. Fig. 9, is of a
dorsal valve; the others are of ventral valves.

14. A cast of the ventral valve of a young individual.

15. The ventral side of a large and rather elongated specimen, showing the muscular markings

and filling of the rostral cavity.

16-19. Dorsal, ventral, profile and front views of the internal cast of a short ventricose indi¬
vidual.

20. Enlargement of the surface to show the lamellose concentric striae and the finer radiating
lines.

Fig. 8.
8.

Figs. 21-33. Athyris polita . . . 293

21, 22. Dorsal and ventral views of a small individual. •

23-26. Dorsal, ventral, profile and front views of a specimen of the ordinary size and propor¬
tions. The shell has been almost entirely exfoliated from the specimen.

27 - 29. Dorsal, ventral and cardinal views of a more gibbous and more perfect cast of the
species, showing the muscular impressions and filling of the rostral cavity.

30. The exterior of a nearly perfect specimen, showing the surface strim.

31. Dorsal view' of a cast of the species, showing the muscular impressions.

32. 33. Ventral views of casts, showing the muscular impressions and filling of the dorsal cav¬

ity. The species not verified.

Figs. 34-38, Meristella scitula . . . ......... 302

34, 35. Dorsal and ventral views of a specimen of medium size.

36-38. Dorsal, ventral and profile views of a larger individual.

Paleeont N Y Vol 4.

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PLATE 48.

Figs. 1-25. Meristella nasuta .

1. The cast of a large dorsal valve.

2. The cast of an imperfect specimen of the dorsal valve, showing more distinctly the muscular

impressions.

3. 4. Cast of ventral valves of an elongated form, with deep muscular impressions.

5, 6. Casts of ventral valves of larger individuals, showing somewhat different forms of muscu¬
lar impressions. The above are from the Schoharie grit.

7-9. Dorsal, ventral and profile views of a young individual of a lenticular form, which is not
produced in front.

10. A small elliptical form which is produced in front.

11, 12. Dorsal and profile views of a larger and proportionally shorter form than fig. 10.

13. A front view of a specimen, showing an extreme elevation of the ventral valve.

14. Dorsal view of a broad form of the species.

15. 16. Dorsal and ventral views of a large individual of a broadly oval and somewhat quadri¬

lateral form.

17. The interior of a dorsal valve, showing the hinge plate and muscular impression.

18. The interior of an imperfect ventral valve.

19. Dorsal view of a specimen, showing the internal spires and median septum.

20. 21. Dorsal and profile views of a cast in chert, from the Corniferous -limestone.

22. The cardinal view of another cast, showing the muscular impressions, the filling of the ros¬
tral and teeth cavities, and the spaces left by the removal of the dental lamella;, hinge
plate and median septum. Figs. 7-22 are of specimons from the Upper Helderberg
limestones.

23 - 25 Dorsal, profile and ventral views of a large individual, which is much produced in front
and having a comparatively shallow dorsal valve; from the Schoharie grit. This is the
form originally described as Meristella elissa.

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PLATE 49.

Figs. 1-4. Meristella meta .

1-4. Dorsal, ventral, profile and front views of a specimen of the ordinary size.

Page

308

Figs. 5-22. Meristella barrisi . 304

5 Dorsal view of a small individual.

6, 7. Dorsal and profile views of a very gibbous form.

8, 9, 11. 12. Dorsal views of specimens illustrating the prevailing size and forms of the species.

10. A ventral view of the specimen, fig. 9.

13-15. Dorsal, profile and front views of an unusually elongated and gibbous form.

16 - 19. Dorsal, ventral, profile and front views of large forms, the front view offering a Strong
contrast with fig. 15.

20. A ventral view of a broad form of the species.

21, 22. Dorsal and ventral views of casts of this species.

Figs. 23 -35.* Meristella haskinsi . 306

23-25. Dorsal, profile and front views of a small lenticular form which shows little gibbosity.

27, 26, 30. Profile, dorsal and front views of a more gibbous form.

28, 31. Dorsal and ventral views of a larger form, showing a greater extension of beak.

29, 32, 33. Profile, dorsal, and ventral views of a specimen of the ordinary size and form.

34. Dorsal view of a large individual, showing the foramen and deltidial plates.

35. Cast of a ventral valve.

36. A dorsal view of a partial cast. The specimen is referred with doubt to this species.

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Figs. 1 - 12.

PLATE 50.

MERISTELLA DORIS .

Pago

BUB

1. A dorsal view of a small specimen, from the Schoharie grit.

2. A dorsal view of a small individual. This, and the following figures, are of specimens from

the Corniferous limestone.

3. 4. Dorsal and ventral views of an unsymmetrical specimen, of medium size.

5, 6. Dorsal and profile views of a specimen of medium size and perfect form.

7. "Ventral view of a large individual, which is somewhat imperfect at the beak.

8-10. Dorsal, profile and front views of a large individual.

11. The dorsal valve of a large individual.

12. Cardinal view of a cast, showing the muscular impressions and the cavities made by the
* removal of the dental lamellae and median septum.

Figs. 13-17. Meristella rostrata . . 307

13-16. Dorsal, ventral, profile and front views of a specimen.

17. Dorsal view of a specimen, having a somewhat different form from the above.

Figs. 18-35. Meristella (Pentagonia) unisulcata . 309

18-20. Dorsal, ventral and cardinal views of a small specimen, presenting the ordinary charac¬
ters of the species.

21. Dorsal view of a small individual, having a less extended hinge line, giving the shell a more

triangular form.

22, 23. Dorsal and ventral views of a specimen of medium size.

24. A cardinal view of a somewhat larger individual, showing a deep sinus in the mesial fold.

25-29. Dorsal, ventral, front, cardinal and profile views of a large but not very gibbous specimen.

30-32 Ventral, front and cardinal views of a narrow gibbous form, from the Falls of the Ohio.

33, 34. Interiors of the dorsal and ventral valves, showing the hinge structure and muscular im¬
pressions. From the Falls of the Ohio, communicated by Major S. S. Lypn.

35. A cardinal view of a specimen, from the Hamilton shales of New York, showing a second
fold on the cardinal margin of the dorsal valve.

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PLATE 51.

Page

Figs. 1-9. Atrypa impressa . . . . 315

1-3. Dorsal, ventral and front views of a specimen of the ordinary form.

4, 5. Profile and front views of a very gibbous form, having the mesial portion of the dorsal
•valve more than usually impressed.

6. A cast of a dorsal valve, showing the muscular impressions and the imprint of the crenulated

socket plates.

7. An enlargement from the upper portion of a specimen similar to that of figure 6, showing

more distinctly the crenulations left by the removal of the socket plates.

8. A cast of an extremely gibbous dorsal valve, with a very prominent muscular scar, showing

vascular lines and papillose ovarian markings.

9. Cast of a ventral valve, showing muscular impression and dental cavities.

Figs. 10-24. Atrypa reticularis . . . 816

10. A dorsal valve of a broad form, with coarse plications, showing the marginal extension of

the lamellae; from New York.

11. A ventral valve without sinus, of the ordinary form of this species, as it occurs in the Cor-

niferous limestone.

12-13. Profile and front views of a specimen from Cayuga, C. W., having a sinus in the ven¬
tral valve ; of the ordinary size and form, as it occurs in the Corniferous limestone of
New York and Canada.

14-16. Dorsal, profile and ventral views of a large individual of this form, from New
York, the ventral side having the shell removed, showing the muscular markings and
the papillose surface of the interior. The specimen fig. 10, this and the following ones,
present some characters which might be regarded as of specific importance. The external
features, general form, striae, elevation of beak, etc., are distinctive, and may be found
useful in characterizing a form intermediate between those with fine strife, like repre¬
sentations in figs. 11 - 13, and the A. aspera or A. spinosa.

17. Dorsal view of a small specimen, from the hydraulic beds at the Falls of the Ohio.

18 - 22. Dorsal, ventral, profile, cardinal and front views of a specimen illustrating the prevail¬
ing form in the hydraulic beds at the Falls of the Ohio.

23. Interior of a ventral valve, showing the muscular impressions and papillose surface.

24. The hinge portion of the dorsal valve of the preceding specimen, showing the bases of

crura and crenulate sockets; from the Falls of the Ohio.

PalaeontINXYolA

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PLATE 52.

Figs. 1-12. Atrypa reticularis . . . . .

1-3. Dorsal, profile and cardinal views of an extremely gibbous form of this species, from the
Falls of the Ohio.

4-6. A. very gibbous form with the ventral valve extremely elevated in front, and the surface
with somewhat strong lamellose lines. Specimens from the Bake-oven, Illinois.

7-10. Dorsal, ventral and profile views of large gibbous forms, in the Corniferous limestone of
Albany and Schoharie counties. These specimens present many features in common
with the A. desquamata . of Sowerby, but the shells are more gibbous and the beaks less
elevated. The foramen and deltidial area are not preserved in our species except in the
young individuals. It is probable that they will eventually prove to be specifically dis¬
tinct from the smaller forms referred to A. reticularis.

11. The interior of the ventral valve, showing muscular impressions and teeth.

12. A cast of the ventral valve of a smaller specimen, showing the muscular and vascular

markings.

Figs. 13 - 19. CCELOSPIR A CAMILLA (CONCAVA of text) . .

13. 14. Dorsal and ventral views of a specimen having the ordinary size and characters of those

from the Lower Helderberg group; enlarged to two diameters.

15-17. Dorsal, ventral and profile views of a larger and more coarsely plicated form; enlarged
to two diameters.

18. Interior of the dorsal valve, showing the cardinal process and dental sockets.

19. Interior of the ventral valve, showing muscular^ impressions and teeth; enlarged to four

diameters.

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PLATE 53.

Figs. 1, 2. Atrypa pseudomarginalis . . 3

I, 2. Dorsal and ventral views of an individual of the species.

Figs. 8-19. Atrypa reticularis.. . . .

3. Dorsal view of a young individual which preserves the deltidial plates.

4. Enlargement of the beak of specimen, fig. 3, showing the deltidial plates and perforation

of the beak.

5-7. Yentral, dorsal and profile views of a specimen of medium size, of the ordinary form of
those from the shales of the Hamilton group of New York.

8. Ventral view of a larger individual, showing the extension of the lamellae on the sides of

the shell.

9. The interior of the dorsal valve, showing muscular impressions, hinge-plate, and crenulated

socket plates.

10. An enlargement of the cardinal portions of specimen fig. 9, more clearly showing the

characters of the hinge and points for the attachment of the crura.

II. The interior of a ventral valve, showing muscular impressions, teeth, etc

The specimens, figs. 3-11, are all from the shales of the Hamilton group, of New York.

12, 13. Dorsal and ventral views of a specimen, from Lime Creek, Iowa, supposed to be of the
age of the Chemung group.

14, 15. Dorsal and profile views of a large form, common to the Hamilton group, at Independ¬
ence, Iowa.

16. View of a large individual from Waverly, Iowa. The dorsal valve has been broken away,

revealing parts of the spiral band and the loop connecting the cones.

17. Dorsal view of a well formed individual, from the Chemung group, of New York.

18. An impression of the ventral valve of a more coarsely ribbed specimen, from the Chemung

group, of New York.

19. A cast of the ventral valve, of a very finely ribbed specimen, from the Chemung group. The

form of the valve and the great extension of the cardinal border, presents considerable
resemblance to those from Independence, Iowa; figs. 14, 15.

Palaepnt W.Y.Yol.4..

m. 53.

.R.P.-WHtfieli,ael.

PLATE 53 a.

Page

Figs. 1 - 14, 18, 24, 25. Atrypa spinosa . . 822

1. Dorsal view of a young individual, from the Corniferous limestone, showing the perforated
beak, and the extended lamellae near the margin of the shell.

2-4. Dorsal, ventral and profile views of a specimen, of the ordinary form and size of those
from the Upper Helderberg limestones of New York.

5. Dorsal view of a large specimen from the Upper Helderberg limestone of New York.

6. The interior of a ventral valve, from the Falls of the Ohio.

7. The interior of an imperfect dorsal valve, from the Falls of the Ohio, showing the socket

plates and muscular impressions; enlarged.

8. 9. Views of a small and medium sized specimen, from the Hamilton shales, showing the

spines.

10, 12. Dorsal, ventral and profile views of a specimen of ordinary size, showing the surface
denuded of the spines; from the Hamilton shales.

13. Dorsal view of a large specimen without spines, from the Hamilton group.

14. The interior of a ventral valve, showing muscular impressions, teeth, etc.

18. Dox*sal view of a specimen, from the Chemung group, of New York.

24. Dorsal side of a specimen, showing the spires, crura and loop.

25. Ventral side of the same specimen showing the position of the spires, loop and attach¬

ment of the crura to the hinge-plate. From the collection of Mr. R. P. Whitfield.

Figs. 15-17. Atrypa hystrix . 826

15. Ventral view of a small specimen which preserves the marginal spines.

16. View of an individual preserving several spines to a length of nearly three-fourths of an inch.

17. View of an individual having very strong symmetrical plications.

Figs. 19-21. Atrypa aspera var. occidentalis .

19-21. Ventral, profile and dorsal view of a specimen, showing the prevailing form of this spe¬
cies as it occurs at Independence, Iowa.

Figs. 22, 23* Atrypa reticularis . 316

22. The vential side of a specimen, showing the position of the spiral cones, with their attach¬

ment to the hinge-plate, and the loop connecting the spires.

23. Dorsal side of the same specimen. From the collection of Mr. R. P. Whitfield.

False ont N Y. Vo 1.4

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PLATE 54.

Page

Figs. 1-8. Rhynchonella (Stenocisma) tethys . 835

1-3. Dorsal, ventral and profile views of a small specimen of the species.

4-8. Dorsal, ventral, profile, cardinal and front views of a large individual of the species.

Figs. 9-13. Rhynchonella (Stenocisma) billingsi . . 336

9. An enlarged dorsal view of a young individual, specimen, fig. 11.

10. Enlarged dorsal view of another specimen.

11-13. Ventral, profile and front views of a specimen of this species.

Figs. 14-19. Rhynchonella (Stenocisma) Carolina . 337

14-18. Dorsal, ventral, profile, cardinal and front views of a cast, showing the general features

of the spedes.

19. Front view of a less gibbous specimen.

Figs. 20-23. Rhynchonella (Stenocisma) royana . 838

20-23. Dorsal, ventral, profile and front views of the specimen described.

Figs. 24-32. Rynchonella (Stenocisma) iiorseordi . . . . 339

24. Dorsal view of a specimen of medium size, which is somewhat thickened on the margin.

25. Front view of a smaller individual.

2(^ 27. Dorsal and profile views of a more globose specimen.

28-32. Dorsal, ventral, profile, cardinal and front views of a large, well formed, and charac¬
teristic specimen of the species.

Figs. 33-43. Rhynchonella (Stenocisma) sappho . 340

33.. Ventral valve of a specimen, referred with some doubt to this species. From the Upper
Helderberg limestones.

34, 35. Dorsal and ventral views of a medium sized individual of the species.

36. 37. Dorsal views .of two individuals of a larger size, showing some variation in the general-
outline of the shell

38-42. Dorsal, ventral, profile, cardinal and front views of a large and characteristic specimen
of the species.

43. Front view of a still larger individual, showing a greater gibbosity.

Figs. 44-59. Rhynchonella (Stenocisma) congregata . 341

44, 45. .Dorsal and front views of a small globose form of the species.

46-50. Dorsal, ventral, profile, cardinal and front views of a full grown and characteristic
specimen. /

51, 52. Ventral views of casts of the species, showing considerable variation in the form of the
muscular impressious.

53, 54. Ventral and cardinal views of a more elongated form, showing the cavities left by the
removal of the dental lamellae and hinge-plate; also the median septum and the filling of
the small triangular fissure in the beak of the dorsal valve.

55. Dorsal view of a cast of this species.

56, 57. Enlargements of the cardinal parts of the casts of dorsal valves, showing the filling

of the rostral cavities and fissure.

58, 59. Enlarged views of artificial casts made in the natural moulds of the dorsal valves, show¬
ing the hinge-plate, dental sockets, median septum and triangular fissures in different
stages of development.

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PLATE 54 a.

Page

Figs. 1-10. Rhync honell a (Stenocisma) prolific a . 343

1-3. Dorsal views, showing gradation in size and form.

4-6. Ventral, profile and front views of specimen, fig. 3.

7 . Front view of a small specimen, in which the mesial elevation is not distinctly marked.

8- 10. Dorsal, ventral and profile views of an unusually large specimen.

Figs. 11-20. Rhynchonella (Stenocisma) dotis . . 344

11 - 14. Dorsal, ventral, profile and front views of an individual of medium size, having sharply
angular plications.

15 - 18. Dorsal, ventral, profile and front views of a broad form where the plications are
rounded.

19, 20. Dorsal and front views of a more elongate form, showing a greater mesial elevation.

Figs. 21-23. Rhynchonella (Stenocisma) carica . 344

21-23. Dorsal, ventral and front views of the specimen described.

Figs. 24-43. Rhynchonella venustula . . . . 346

24, 25. Dorsal and front views of a small ventricose specimen.

26, 27. Dorsal and front views of a larger but less ventricose, and more finely plicated specimen.

28, 29. Ventral and front views of a specimen not fully grown, showing eight plications in the
mesial sinus.

30 - 32. Dorsal, ventral and front views of an immature individual, with a slight elevation in
front and only four plications in the sinus.

33. Front view of an immature specimen, showing six plications in the sinus.

34, 35, 37-39. Dorsal, ventral, profile, front and cardinal views of a full grown and gibbous

specimen, having only five plications in the sinus. The ventral side is denuded of the
shell and shows the vascular markings.

36. Enlargement of the specimen, fig. 35, to show the ramifications of the vascular lines, and
their origin in the border of the muscular impressions.

40, 41. Dorsal and front views of an unusually broad individual.

42, 43. Front views of specimens which are extremely elevated in this part, with a maximum
number of plications in the sinus.

Figs. 44-49. Rhynchonella (Stenocisma) contracta? var. (see addenda) . 351
44-48. Dorsal, ventral, profile, cardinal and front views of a characteristic specimen of this
form.

49. Enlarged ventral view of a smaller specimen, showing a greater number of plications.

50, 5K Dorsal and ventral views of a specimen, with finer plications, resembling the R. (S'.)

eximia.

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PLA.TE 55.

Page

Figs. 1- 8. Rhynchonella (Stenocisma) eximia . . 848

1. Dorsal view of a small individual of the species, showing no mesial elevation.

2, 3. Dorsal and ventral views of a larger specimen.

4-8. Dorsal, ventral, profile, cardinal and front views of a cast.

Figs. 9-16. Rhynchonella (Stenocisma) stephani . 349

9. Ventral valve of a young individual.

10. Ventral view of a cast of a larger specimen.

11, 12. Profile and front views of the cast of a dorsal valve, having narrow angular plications.

13-15. Dorsal, cardinal, and profile views of a cast, showing the characters of the dorsal

portion of the hinge.

16. Ventral view of a cast, showing the muscular impressions..

Figs. 17-25. Rhynchonella (Stenocisma) duplicata . 350

17-20. Dorsal, ventral, profile and front views of a characteristic specimen of ordinary size.

21, 22 Casts of dorsal valves, showing muscular impressions, etc.

23. Cast of a ventral valve, showing muscular impressions.

24. An enlarged figure of a gutta-percha impression taken from specimen, fig. 22, showing the

median septum, hinge-plate and crura, and a thickening of the cardinal portion of the
interior.

25. An enlarged figure of a gutta-percha impression of specimen, fig. 23, showing muscular

impression, teeth, etc.

Figs. 26-39. Rhynchonella (Stenocisma) contr acta . 351

26. Ventral valve of a small specimen with fine plications.

27. Dorsal valve of a specimen having stronger plications.

28. Ventral valve of a specimen, showing only two plications in the mesial sinus.

29-33. Dorsal, ventral, profile, front and cardinal views of a characteristic specimen of the
prevailing size.

34, 35. Dorsal and cardinal views of a cast, showing the cavities left by the removal of the
hinge-plate, teeth, septum, etc.

36. Ventral valve, showing four plications in the sinus.

37. Cast of a ventral valve of unusually large size.

38. Enlarged view of the cast of a ventral valve, showing muscular impression and filling of the

rostral cavity. From the Hamilton group, four miles south of Cardiff, Onondaga Co.,

N. Y.

39. Ventral valve of a specimen of this species, from the Waverly sandstones of Ohio.

Figs. 40-46. Rhynchonella (Stenocisma) orbicularis . 353

40. Cast of a dorsal valve, showing the triangular filling of the fissure in the hinge-plate.

41. Cast of a dorsal valve of a broader form, which approaches very closely to R. contracta.'

42. Cardinal view of the cast of a dorsal valve.

43. Cardinal view of a cast, showing the cavities left by the removal of the hinge-plate, teeth, etc.

44. Ventral view of a cast, showing muscular impressions.

45. Dorsal view of the cast of a large specimen from Chautauque Co., N. Y. The other figures

of the species are all from specimens collected near Meadville, Pa.

46. Enlargement from the cast of a ventral valve, showing muscular impressions and dental

cavities.

Figs. 47-52. Rhynchonella (Stenocisma) sappho var . . 354

47. 48. Views of dorsal valves, showing some variation in fo'rm and number of plications.

49-51. Ventral valves of this species.

52. Front view of a crushed specimen.

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Figs. 1-5.

PLATE 56.

Leiorhynchus MYSIA . . .

Page

857

(The figures of this species are all enlarged to two diameters.)

1-3. Dorsal, ventral and profile views of a specimen of the ordinary size and characters of
the species.

4. Dorsal view of another individual, having a less prominent beak and duplicate plications.

5. Dorsal view of an unusually large specimen, with sloping cardinal line.

Figs. 6-21. Leiorhynchus limitaris . 856

6-8. Dorsal and ventral views, and profile of a specimen of the usual form and size of those
from the limestones in the Marcellus shale of Schoharie Co., N. Y.

9. Ventral view of another specimen, with fewer plications in the sinus.

10-12. Dorsal, profile, and front views of a somewhat larger specimen.

13, 14. Profile and front views of a very gibbous form, having numerous plications.

15-19. Dorsal ventral, profile, cardinal and front views of an unusually large and broad
individual.

20. Front view of a very gibbous form, which is abruptly elevated in front and having only

three plications in tiie sinus.

21. Dorsal view of a flattened specimen, from the thinly laminated black shales.

Figs. 22-25. Leiorhynchus dubius . . . 364

22. Dorsal view of a specimen, with a slightly elevated mesial fold.

23-25. Dorsal, ventral and profile ❖iews of a specimen, with a more distinctly elevated
mesial fold, and stronger plications.

Figs. 26-40. Leiorhynchus multicosta . . . 358

26. Dorsal valve of a young individual.

27. Dorsal valve of a larger individual.

28. Dorsal valve of a specimen of medium size.

29. Cardinal view of a gibbous specimen.

30. Dorsal view of a crushed individual of ordinary size.

31. 32. Yentral valves of elongated specimens, showing considerable variation in the plications.

33. Cast of a dorsal valve of unusually large size.

34, 35. Dorsal and ventral views of a young and much elongated specimen, from Widder, C. W.

36 - 40. Dorsal, ventral, profile, cardinal and front views of a full grown and well preserved

individual, from the Hamilton shales of Canada.

Figs. 41-43. Leiorhynchus iris . 360

41 - 43. Dorsal, ventral and profile views of the specimen described.

Figs. 44-49. Leiorhynchus quadricostata . . . 357

44. Dorsal valve of a crushed and flattened individual of small size.

45-48. Views of dorsal valves of this species, showing gradations in size.
49. Ventral valve of a large individual.

Palaeonl .Y.Y.Vol A.

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PLATE 57.

Figs. 1- 12. Leiorhynchus kelloggi .

1 -3. Dorsal, ventral and profile views of a small individual.

4. 5. Dorsal and front views of an attenuated form.

6. Front view of a gibbous form, contrasting strongly with fig. 5.

7-11. Dorsal, ventral, profile, front and cardinal views of a full grown and characteristic
specimen of the species.

12. Cardinal view of a cast, showing the cavities left by the removal of the dental lamellae,
hinge-plate and septum.

Page

861

Figs. 18-17. Leiorhynchus sinuatus.... . . 362

13. Ventral valve of a small individual.

14-16. Dorsal ventral and front views of a small attenuated individual.

17. Front view of a more gibbous form.

Figs. 18-25. Leiorhynchus mesacostalis . 362

18. Ventral valve of a small individual.

19. Ventral view of a larger individual.

20. Cardinal view of a large individual.

21-23. Casts of dorsal valves, showing variations in form, and number of plications in the
mesial fold.

24. Ventral valve of a perfect and characteristic specimen.

25. Cast of a ventral valve, showing the muscular impression and a narrow mesial sinus.

Figs. 26-29. Leiorhynchus globuliformis . 364

26-29. Views of dorsal valves of this species, showing the rotundity of the shell and the form
of the muscular impressions.

Figs. 30-39. Leptocoelia acutiplicata . 365

30, 31. Dorsal and ventral views of a small individual, having a slightly concave dorsal valve.

32, 33. Dorsal and ventral views of a specimen of medium size.

34-37. Dorsal, ventral, profile and front views of a large and characteristic specimen of the
species.

38. Interior of a dorsal valve, showing a slender median septum, cardinal process and dental

sockets.

39. Enlargement of the interior of a ventral valve, showing the teeth and muscular impression.

Figs. 40-45. Camarophoria euc haris . 368

40-44. Dorsal, ventral, cardinal, front and profile views of a characteristic specimen of the
species.

45. Ventral view of a specimen, showing the triangular or spoon-shaped cavity of the ventral
valve.

7JaJ spout X.Y.Vol.4

PI 51.

( BttACHrOPODA.)

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PLATE 58.

Page

Figs. 1 - 21. Pentamerella arata . 375

1. Dorsal view of a young individual.

2-4. Ventral, dorsal and profile views of a small well formed individual.

5.-8. Dorsal, ventral, profile and front views of a characteristic specimen of the ordinary size.

9. Cast of a large dorsal valve having peculiarly flexuose plications.

10. Cardinal view of a large cast, showing the cavities left by the removal of the parts of the

hinge.

11, 12. Profile and front views of an unusually large and arcuate ventral valve. This and the

foregoing specimens are all from the Schoharie grit of Albany and Schoharie counties,

.New York.

13-16. Dorsal, ventral, profile and front views of a specimen from the Upper Helderberg lime¬
stones of New York.

17, 18. Interior of dorsal and ventral valves, showing the hinge structure, from the Upper Hel¬
derberg limestones of New York.

19. Dorsal view of a specimen from the limestones at the Falls of the Ohio.

■ 20, 21. Dorsal and ventral views of a specimen from the limestones at Waterloo, Iowa.

Figs. 22, 23. GtYpidula LjEviuscula . . . 381

22, 23. Dorsal and ventral views of a specimen of this species.

Figs. 24, 25. Pentamerella obsolescens . 379

24, 25. Exterior and interior of a dorsal valve of this species, showing the small triangular pit
and the flattened space or area on each side of it.

Figs. 26, 27. Pentamerella micula . 378

26. Exterior of a dorsal valve of the species.

27. Interior of a dorsal valve, showing the triangular pit.

Figs. 28-37. Pentamerella papilionensis . 377

28. 29. Dorsal views of small individuals of the usual form.

30. Yiew of a dorsal valve where the plications are somewhat angular, as in many examples of
P. arata.

31-34. Dorsal, ventral, profile and front views of a full grown and characteristic individual.

35. Yentral valve of a crushed specimen, showing irregular plications and strong concentric

lines of growth.

36. Yiew of a specimen where the beak of the dorsal valve has been cut away to show the

extent of the spoon-shaped process of that valve.

37. Interior of the ventral valve, showing its spoon-shaped process.

Figs. 38-43. Pentamerella dubia . 379

38. 39. Dorsal and ventral valves of a small individual.

40-43. Dorsal, profile, cardinal and front views of a large and characteristic specimen of the
species.

Pal seonl N.Y.Vol.4

Pl.aS

( BRACmOPOBAl

E..P .'Whitfield. ,3 el .

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PLATE 58 a.

Page

Pigs. 1-8. GrYPIDTJLA OCCIDENTALIS . . 880

1-5. Dorsal, ventral, profile, front and cardinal views of a very characteristic specimen, show¬
ing plications extending some distance from the margin of the shell.

G, 7. Profile and front views of another individual which is entirely destitute of plications.

8. An enlargement of the upper half of the shell, showing the area and foramen.

Pigs. 9-20. Rensselaeria (?) johanni . 385

9. A dorsal valve of a young and moderately convex specimen.

10. 11. Dorsal and profile views of a larger and very ventricose specimen.

12. Ventral view of a specimen of medium size.

13-15. Dorsal, ventral and profile views of a crushed and somewhat distorted specimen.

16, 17. Dorsal and ventral views of a characteristic specimen, somewhat larger than the
ordinary size.

18. Ventral valve of a very broad and unusual form.

19. Dorsal view of a cast, showing muscular impressions, dental cavities, etc.

20. Ventral view of a cast, showing the muscular and hinge-plate impressions.

Figs. 21-24. Amphigenia elongata . . . 383

21 - 24. Views of specimens, showing gradations in size and varieties of form in young indi¬
viduals of the species.

Pigs. 25-^27. Amphigenia elongata var. undulata . 384

25. Ventral view of a specimen from Mackinac, Michigan.

26. Interior of an imperfect ventral valve from the drift of Michigan, from Dr. C. Rominger.

27. Cast of a large ventral valve from the same source.

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PLATE 59.

.1-11. AMPHIGENIA ELONGATA .

1. Dorsal valve of a specimen of medium size.

2. Dorsal view of another individual of a more regularly elliptical form, showing a strongly

striated surface.

3. Ventral' side of a much elongated specimen preserving the shell on the upper part.

4-6. Profile, dorsal and cardinal views of a specimen of medium size and form.

7 . Interior of an imperfect dorsal valve, showing the hinge-plate, dental sockets, vascular lines, etc.

c c, points for the attachment of the crura; /, foramen which passes beneath the hinge
plate and opens between the septa; s s, the double septum bordering the adductor mus¬
cular scar.

8. Dorsal view of a partial cast, showing muscular impressions and vascular lines, the cavity

left by the removal of the hinge plate and at /, the filling of the foramen which passes
from the beak beneath the hinge plate.

9 Cast of a large dorsal valve, showing the muscular impressions and the cavity left by the
removal of the hinge plate, the filling of the foramen, etc.

10. Longitudinal section of a specimen, showing the septa and processes of both valves : a, the

thickened shell of the dorsal valve ; c, the crura with its expansion to form the loop ; d s,
dorsal septum; s, ventral septum; x, one of the dental lamellae which unite on the sep¬
tum to form the spoon-shaped process of the ventral valve.

11. Cardinal view of a large cast of both valves ;/, the filling of the foramen of the dorsal

valve, showing its connection with the interior; s, the cavity left by the removal of the
septum; x, the filling of the inside of the spoon-shaped process.

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PLATE 60.

Page

Figs. 1-4. Terebratula lens . 386

1-3. Dorsal, ventral and prolile views of a specimen of the ordinary size and form.

4. Dorsal view of a larger but somewhat distorted specimen.

Figs. 5-10, 68. Terebratula sullivanti . 387

5-7. Dorsal, ventral and profile views of a small specimen of the species, from Columbus, Ohio.

8. Dorsal view of an imperfect specimen, from Cayuga, Canada West.

9, 10. Dorsal and ventral views of a large imperfect specimen, from the same locality as the last.

68. Enlarged dorsal view of a specimen from Cayuga, C. W-, showing the reversed loop. This
feature, so far as yet ascertained, is peculiar to this species, and may possibly be due to
accident in the specimen examined.

Figs. 11-16. Terebratula harmonia . . 388

11. Dorsal view of a young individual.

12. Ventral view of a larger and broader form, from Cayuga, C. W.

13. The dorsal side of the same specimen cut down to show the loop.

14-16. Dorsal, ventral and profile views of a more elongated specimen. This, and specimen
fig. 11, are from the Falls of the Ohio.

Figs. 17 -25, 66,67. Terebratula rcemingeri . 389

17 -19. Dorsal, ventral and profile view of a large rotund form, from Hamburgh, N. Y., on the
shore of Lake Erie.

20, 21. Dorsal views of two specimens from New York, one of them showing an emargination
in front, and the other rounded; enlarged to two diameters.

22 - 24. Dorsal, ventral and profile views of a specimen from Michigan, showing a distinct emar¬
gination in front and a sinus on the ventral side ; enlarged to two diameters.

25. Dorsal view of another individual from Michigan, which is destitute of sinus or emargina¬
tion; enlarged to two diameters.

66, 67. Ventral and profile views of the loop of this species; enlarged from a specimen, from

Michigan.

Figs. 26-28. Terebratula elia . 390

26-28. Dorsal, ventral and profile views of the specimen described.

Figs. 29-31. Terebratula jucunda . 390

29-31. Dorsal, ventral and profile views of the specimen described.

Figs. 32 - 37, 71. Terebratula linckl^seni var . ^418

32. Dorsal view of a young shell of this species.

33-35. Dorsal, ventral and profile views of a full grown shell.

36, 37. Dorsal and profile views of a more gibbous form.

71. Ventral view of the loop, showing the disconnection at the anterior extremities..

Figs. 38-44. Terebratula navicella . 391

38-40. Dorsal, ventral and profile views of a large specimen of the species.

41. Dorsal view of a smaller individual.

42 -44. Dorsal ventral and profile views of a more slender specimen of the species.

Figs. 45-48. Terebratula Ontario . 418

45. Dorsal view of a round symmetrical specimen.

46-48. Dorsal, ventral and profile views of a larger and slightly longer specimen.

Figs. 49-65. Terebratula LiNCKLiENi . 397

(This species referred with doubt to the Genus Cryptonella on page 397, has proved to be a
Terebratula.)

49. Dorsal view of a young specimen.

50 - 52. Dorsal, ventral and profile views of a larger specimen.

53 - 55. Dorsal, ventral and profile views of a more gibbous specimen, which is much thickened .
on the front margin.

56, 57. Ventral and profile views of a small and very gibbous individual with strong varices of
growth.

58, 59. Dorsal and ventral views of a young individual having a much broader or less elongated
form than usual.

60. Dorsal view of a larger specimen of the same form with the last.

61-63. Dorsal, ventral and profile views of a full grown specimen of the broad form.

64, 65. Dorsal and ventral views of a cast of this species, showing the muscular lines and also
the cavities near the beak left by the removal of the dental lamellae.

Figs. 69, 70. Terebratula simulator . 39J

69. Dorsal view of a specimen which has been cut to show the loop; enlarged to two diameters.

70. Profile view of the loop, showing the long crural processes; enlarged. The connexion at

the anterior end is theoretically restored, but may have been connected during life by a
ligament only.

Palae ont . NY.Yo 1 4.

( BKACHIOPODA.)

Swiaton. litlL.

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PLATE 61.

Cryptonblea rectirostra

Page

894

Figs. 1-8.

1. Dorsal view of a small elongated specimen,

2-4. Dorsal, ventral and profile views of a larger and somewhat broader form.

5. Ventral view of a specimen of large size.

6-8. Ventral, dorsal and profile views of a broad unsymmetrical form of the ordinary size.

Figs. 9-27. Cryptonella planirostra . 89a

9-11. Dorsal, ventral and profile views of a young individual.

12, 13. Dorsal and ventral views of a larger specimen.

14-16. Dorsal, ventral and profile views of a specimen of the ordinary size and form of the
species.

17. Enlargement of the rostral portion of a ventral valve, showing the foramen, deltidial plates

and teeth.

18, 19. Dorsal and profile views of a much thickened and gibbous specimen.

20-22. Dorsal, ventral and profile views of an unusually large specimen, which is much thick¬
ened, giving great gibbosity of form. This form is much less common than that of figs.
14-16.

23, 24., Dorsal and ventral views of a cast of this species, from the Hamilton group of Hardy
county, Va., showing the form of muscular impressions.

25. An enlarged ventral view of the loop of this species, showing its form and the existence of

a, band across the dorsal side near the base of the crura.

26. Dorsal view of a very large specimen referred with some doubt to this species. The specimen

in this figure, is represented with the beak broken off', for the purpose of showing more
clearly the filling of the rostral parts of the dorsal valve. The muscular impressions
and groove left by the slender septum is faintly shown.

27. Ventral side of the same individual, retaining the beak and showing the muscular impres¬

sions of this valve.

Figs. 28-80. Cryptonella iphis . 896

28-30. Ventral, dorsal and profile views of the specimen described.

Figs. 31-41. Cryptonella (Terbbratula) eudora . 39S

31, 32. Dorsal and ventral views of a small, thin specimen of the species.

33. Dorsal view of a small individual, from the Waverly sandstones of Licking Co., Ohio, pre¬

senting all the specific characters of those from the Chemung group, of Hew York.

34, 35. Casts of dorsal valves, showing the muscular impressions.

36. Dorsal view of a cast, showing the cavities left by the removal of the teeth and dental
lamellae.

37-39. Ventral valves, showing a variety of form and proportions, resulting in some cases from
distortion.

40. Ventral view of a specimen from which the shell is removed in the upper part, and partially

preserved below.

41. Ventral view of an individual of the ordinary size, from the Waverly sandstones of Licking

county, Ohio.

(In the progress of this volume it has often been necessary to print the descriptions in advance of
making up the plates, and in the present instance the descriptions were printed in ad¬
vance of the drawings of Terebratula and Cryptonella, and all the figures were
referred to Plate 61. In consequence of a greater number of figures than antici¬
pated, it has become necessary to designate an additional Plate as 61 a.)

Palaeorrt.NTY^'ol. 4-.

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PLATE 61 a.

Page

Figs. 1 - 21, 25, 26. Centronella glans-fagea . . . 399

1, 2. Dorsal and venfral views of a large specimen of broader form than usual.

3-5. Dorsal, ventral and profile views; enlarged to three diameters, from a specimen of ordi¬
nary form. This, and the preceding specimen, are from the Schoharie grit.

6. Dorsal view of a large individual, from the Upper Helderberg limestone.

7. Dorsal view of a specimen from a drift pebble of limestone near Ann Arbor, Michigan,

which has the dorsal valve entirely flat; enlarged to two diameters.

8-10. Dorsal, ventral and profile views of a large specimen from the Onondaga limestone of
Erie county, N. Y.; enlarged to two diameters.

11 - 13. Dorsal, ventral and profile views of a very gibbous form, which shows the foramen and
deltidium, enlarged to two diameters. The specimen is from the drift of Michigan.

14, 18. Dorsal and ventral views of a small specimen of somewhat different form, from the
same locality as the preceding; enlarged to two diameters.

16. The interior of a dorsal valve, showing the muscular impressions, cardinal processes, the

points for the attachment of the loop, and the dental sockets ; enlarged to three diameters.

17. Dorsal view of a cast of a large specimen from the Schoharie grit, showing the muscular

impressions, etc. ; enlarged to two diameters.

18. The cast of a ventral valve from the Schoharie grit; enlarged to two diameters.

19. Dorsal view of a cast in chert from the drift of Michigan, showing the muscular imprints,

the filling of the rostral cavity of the ventral valve retaining the imprints of the delti-
dial plates.

20. Enlargement of the loop of this species, taken from the ventral side showing its

attachment to the hinge-plate of the dorsal valve.

21. Profile of the same.

25, 26. Dorsal and profile views of a very ventricose specimen having the character of C.
tuviida. Billings, but of smaller size. The specimen is from the Upper Helderberg

limestone of Cayuga, C. W., and the figures are enlarged to two diameters.

Figs. 22-24. Centronella alveata . 401

22 - 24. Dorsal, ventral and profile views of the specimen described.

Figs. 27-29. Centronella hecate... . 420

27-29. Dorsal, ventral and profile views of a specimen of this species from Cayuga, C. W.;
enlarged to two diameters.

Figs. 30-38. Centronella impressa . • . 402

30-32. Dorsal, ventral and profile views of a young and somewhat circular form.

33-35. Dorsal, ventral and profile views of a full grown specimen of the ordinary size.

36. Interior of a dorsal valve, showing the cardinal process and the strong callosities to which the

crura are attached.

37. Interior of a dorsal valve of circular form, showing muscular and vascular markings; en¬

larged to two diameters.

38. Interior of a ventral valve, showing the teeth and deltidial plates.

Figs. 39,40. Centronella glatjcia . . . 403

39. Partial cast of a large dorsal valve.

40. Cast of a ventral valve, showing the muscular impression and filling of the rostral cavity.

Figs. 41-45. • Centronella julia . 419

41, 42, 43. Dorsal, ventral and profile views of a specimen of this species; enlarged to two
diameters.

44. Yentral view of a large broad form; enlarged to two diameters

45, 46. Yentral and profile views of the loop of this species, made from specimens which have

been broken, so as to show parts of the structure in different individuals from which this

has been restored. Specimens loaned by Prof. A. Winchell.

Figs. 47 - 49. Centronella ovata . 419

47 - 49. Dorsal, ventral and profile views of the specimen described.

Figs. 50-52 Tropidoleptus occidens . 408

50-52. Dorsal, ventral and profile views of a specimen of ordinary size.

PalaeoJit NTT.Vol. 4.

(BRACHIOI'C

A.)

PI. 61. A.

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PLATE 62:

Fig. 1. VlTULINA PUSTVLOSA . .

1 a. Ventral valve of a large individual.

1 b- Dorsal valve of a specimen of corresponding size.

1 c-f. Ventral, dorsal, profile and cardinal views of an individual; enlarged to three
diameters, showing the pustules of the surface. Fig. 1 /, shows the area of each
valve, and the cardinal process and socket plates of the dorsal valve as seen through the
broad open deltidium of the ventral valve.

1 g. Interior of a dorsal valve, showing the cardinal process, dental sockets, and median septum ;
enlarged to two diameters.

1 h ■ Interior of a ventral valve, showing the teeth, cardinal area, and the thickening of the
shell in the rostral cavity; enlarged to two diameters.

1 i. Cast of a ventral valve, showing the muscular impression and filling of the rostral cavity;
enlarged to two diameters.

Page

410

Figs. 2, 3. Tropidoleptus carinatus . 407

2 a. Dorsal view of a young specimen of an elongated form; from Eighteen Mile Creek, shore
of Lake Erie.

2 b. c. Enlarged dorsal and ventral views of the same.

3 a. Ventral view of a young specimen of the ordinary form.

3 b, c. Dorsal and ventral views of young specimens of larger size than the preceding.

3 d. Ventral view of an individual, showing finer plications than usual (erroneously printed
fig. 4, in the text on page 408) .

3 e . Dorsal view of an individual of medium size.

8 f. g, h. Ventral, dorsal and profile views of a specimen of the usual form and size.

3 i, j, k. Cardinal, ventral and dorsal views of a somewhat larger and thickened shell.

3 l. Dorsal view of an unusually large individual, showing the plications bifurcating beyond
the usual size of the shell and becoming obsolete near the thickened margin.

3»i. An enlargement of the rostral portions of a specimen, showing the area, with the broad
triangular open foramen filled by the callus of the dorsal valve.

3 n, o. Interior of a ventral valve and an enlargement of the same, showing the strongly crenu-
lated teeth. The point of the beak and margins of the foramen, have been broken away
or absorbed.

3 p. r. Interior of a dorsal valve and an enlargement of the same, showing the cardinal process,
crenulated dental sockets, the projecting processes for the attachment of the loop, and
the median septum which supports the outer end of the loop. (See wood cut page 406,
of text.)

3 s. Enlargement of a portion of the surface, showing the strong punctse.

3 t, u. Cast of a ventral valve and an enlargement of the same.

3 w. x. Cast of a dorsal valve and an enlargement of the same, showing the impression of the
cardinal process and the cavities left by the removal of the crenulated socket plates.

Palaeont -RT.Y.Vol.4

PI l)J

(BBLACIHOBODA,)

TLP.mitfieli,3el.

. i . i : : l. •

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PLATE 63.

( Supplementary. )

Page

Figs. 1-5. Orthis idoneus . 52

1. Dorsal view of a small and somewhat distorted individual.

2-5. Ventral, dorsal, profile and cardinal views of a large and characteristic individual.

Figs. 6-13. Spirifera maia . . . 416

6, 7. Dorsal and ventral views of a young specimen.

8-11. Dorsal, ventral, profile and front views of an elongate specimen.

12. Dorsal view of a broadly oval form, where the cardinal line is short and gradually rounded.

13. Dorsal view of a partially exfoliated specimen, showing a large area.

Fig. 14. Spirifera disjuncta . 243

14. Cast of a ventral valve, showing the impressions of the dental lamellae reaching to the

front of the valve.

Figs. 15-18. Meristella rostrata. . . . 307

15 - 18. Dorsal, ventral, profile and front views of the specimen described.

Figs. 19-22. Meristella lenta.. . 420

19-22. Dorsal, ventral, profile and front views of a specimen of the ordinary size and form.

Figs. 23-25 Rhynchospira subglobosa . 421

23, 24. Dorsal and ventral views of the cast of a specimen of medium size.

25. Dorsal view of the cast of a larger specimen which has been slightly distorted by pressure. .

Figs. 26-29. Leiorhynchus, multicosta . 358

26 - 29. Dorsal, ventral, profile and front views of a cast of this species, from Richmondville,
Schoharie Co., N. Y.

Figs. 30-32. Strophodonta plioata . 114

30 - 32. Dorsal, profile and ventral views of the specimen described.

Figs. 33-36. Trematospira (?) nobilis . 412

33. Dorsal view of a crushed and distorted specimen retaining both valves, and showing the

surface marking in a very perfect manner.

34. View of a dorsal valve, showing the beak and part of the crura.

35. Fragment of another dorsal valve, showing the impression of the crura and their attachment

to the hinge-plate.

36. Interior of a ventral valve, showing the teeth and the elevated plate bearing the muscular

impressions.

PalaeontKYA'ol.4. 1 I^MLIW MRiWI^ PI. 63.

( liKACHlOPODA.)

(Suppl em en la.ry )

fiwrn-toXL, del. el iith.

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