B 3 103

MONOGRAPH

OF THE

i

TRILOBITES OF NORTH AMERICA:

WITH

of .tte. Specter

THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

MONOGRAPH

TRILOBITES OF NORTH AMERICA

(Eoiouutr JHotrels of tHe

Multa rcnascentur qu£e jam cccidere. — Hon.

JACOB GREEN, M. D.

Profjssor of Chemistry in Jefferson Medical College.

PHILADELPHIA:

PUBLISHED BY JOSEPH BRAND, No. 12, CASTLE STREET.
Clark & Raser, Printers.

1832.

the Eastern District of Pennsyl*^™ *" Dlstrict Court <*

To JOHN GEORGE CHILDREN, ES^UIUE,

F. R. S. L. & E.

THE kindness which a traveller receives when in a
distant land, must ever be among his most pleasing
recollections — your attentions therefore to me, during
any short residence in London a few years since, can-
not easily be forgotten. Suffer me, then, to inscribe
this little work to you as a token of my gratitude.

Our pursuits in the Natural and Physical Sciences
have been congenial. Your interesting researches
with your original and magnificent Galvanic Battery,
first drew my attention to the calorific effects of that
mysterious agent; and your works on Natural His-
tory have stimulated my exertions in the same fasci-
nating pursuit.

A large portion of your time and fortune have been
•devoted to the patronage or the cultivation of Natu-
ral Science — so that the dedication of this work to
you, if it w-ere infinitely more worthy of your accept-
ance, would be due from me, both as a tribute of
liigh respect, as well as of grateful acknowledgment.

Philadelphia, October 1st, 1832,

ivi36194:l

EXPLANATION OF THE PLATE.

Figure 1. Trimerus Delphinocephalus.

2. Calymene Diops.

3. Asaphus Micrurus.

4. Cryptolithus Tessellatus.

5. Paradoxides Boltoni.

6. Triarthrus Beckii.

7. Isotelus Cyclops.

8. Dipleura Dekayi.

9. Head of D. Dekayi.

10. Ceraurus Pleurexanthemus.

The above figures represented on the Frontispiece to this
volume, were first published in the Monthly Journal of Geo-
logy, &c. for June, 1832, and I am indebted to C. A. Poulson?
Esq., for the use of them in this Monograph.

INTRODUCTION,

SOME geologists imagine that the order of creation
is registered in the rocks which compose the external
crust of the earth, and that they can there clearly read
a progressive development of organic life; in other
words, that a succession of more perfect animals may
be traced in ascending from the lower strata to the
upper or more recent formations; that there is a gra-
dual approach to the present system of things, and a
succession of destructions and creations; worlds of
living beings alternating with worlds of desolation
and death, antecedent to the existence of man.

Others, again, contend that there is often a wide
and palpable discrepancy between the nature of the
rock, and the fossils which it contains, and, therefore,
that such inquiries afford no clue, whatever, to the
order of creation.* We propose not to enter the field

* Nothing can be more opposed to true science, than to pro-
nounce on the priority of formation, or the comparative age of
rocks, from either their structure, or the organic remains they
present. M. Alexandre Brongniart thus propounds his opinion :
" In those cases where characters derived from the nature of the
rocks are opposed to those which we derive from organic re-
mains, I should give the preponderance to the latter." This
seems to us to imply an admission, that nothing definite can be
inferred from the nature of the rocks; moreover, that between
A 2

of controversy. Fossils are undoubtedly historic me-
dallions of remote periods in the natural history of
our earth, and our design is, merely to illustrate with
them a neglected department of ancient zoology, by
describing a few which have recently fallen under our
own observation.

In some varieties of rocks there is often found the
fossil remains of an animal which bears some resem-
blance to certain species of the crab. The back of
this organic relic is commonly divided by two deep
grooves or furrows, into three longitudinal lobes, and
from this circumstance, the term Trilobite has been
applied as a family name to distinguish this whole
race of beings. This general appellation, however,
though in most of the species, highly appropriate, is
by no means applicable to all.

The individuals which compose the family of the
trilobites resemble each other in many important par-

the nature of the rock, and the organic remains, there may be a
palpable discrepancy ; and that these may be even at complete
antipodes with each other. The event has proved, from what we
have already mentioned, that no evidence as to priority can be
obtained from the nature of the fossil remains displayed in parti-
cular strata. In addition to what has been said on this subject,
we may further state, that encrinites, entrochites, and pentacri-
nites are found in clay slate, grauwacke, transition limestone, al-
pine limestone, lias, muschelkalk, and chalk. It may be reasona-
bly asked how these three species of fossils could indicate any
particular formation, when they are found in so many types and
structures of rocks altogether different ? If they would go to
prove any thing at all, it would be that of a contemporaneous for-
mation ; but certainly not distinct epochas. — See Eclectic Review,
July, 1832.

ticulars, and form together an exceedingly natural
group. The body, with but few exceptions, is di-
vided transversely into three parts. The anterior
portion or head often resembles the buckler of the
horse foot or king crab (limulus polyphemus), so com-
mon on our sea coast. The middle portion is the abdo-
men, and is always separated transversely into a num-
ber of segments or articulations, generally diminish-
ing in breadth as they recede from the head. The
posterior end is the tail^ which, though in some spe-
cies, a mere prolongation of the abdomen, that can
scarcely be distinguished from it, yet in others it as-
sumes a genuine caudal appendage.

The head of the trilobite is also generally divided
into three parts: the middle is called the front, or fore-
head; and the lateral portions the cheeks. In most
cases, a projecting tubercle, or knob, is observable on
the anterior surface of each cheek, which has much
the appearance of an eye. Its reticulated structure
is in many instances so analogous to that of the eyes
of some crustaceous animals, and also of some spe-
cies of insects, that there can be but little doubt that
these tubercular projections, were true organs of vi-
sion.

Some of the genera which belong to this remarka-
ble race of fossil animals, possessed the power of
rolling or coiling themselves up into a kind of ball,
like certain species of insects, or like the armadillo;
and they are always found embedded in the rocks in
this attitude.

Such are the general characters by which these

8

petrifactions may be known, and they will be found
illustrated in a manner more or less striking, in most
of the species. The exceptions, which rarely oc-
cur, will be distinctly marked, when the species are
described.

The superior covering, or upper shell of the trilo-
bite is the only part of the animal, concerning which
we have any satisfactory knowledge. It is conjec-
tured that it was furnished with articulated feet, but
no traces of any organs of progressive motion have
hitherto been fairly discovered.* Hence, it may be
reasonably supposed, that the structure of the lower
portions of the animal were so soft and delicate, as to
render them incapable of sustaining the process of
mineralization, which the hard crustaceous covering
of the back so successfully undergoes.

That these petrifactions were once marine animals
there can be little doubt, for they are always found
associated in the same rocks with shells, and other
productions peculiar to the sea.

The Trilobite is supposed by many naturalists to

* Mr. Parkinson states, that in a trilobite which he possessed he
thought he perceived the points of the feet; but on endeavouring
to detach the piece of rock in which it was embedded, the speci-
men was entirely shivered, though he worked at it with the t\t-
most care. A portion of the underside of a trilobite (Isotelus
gigas) near the anterior edge of the head, was distinctly ascer-
tained, by Dr. Dekay, but only enough to convince him of its
analogy in this part with that of the limulus polyphemus — no or-
gans of locomotion could be seen. Mr. Stokes, the distinguished
fossilist of London, has confirmed the observation of Dr. Dekay,
by some dissections of his own.

9

be one of the first animated beings of our earth call-
ed into existence by the great Author of nature.* It
was first noticed more than two centuries ago, among
the petrifactions which abound in a calcareous rock,
at Dudley, in England, and was from this circum-
stance, called for a long time, the Dudley fossil.
Linne gave it the name of the Paradoxical insect; but
whether an insect, a crustaceous animal, or a shell, is
still considered by many as problematical.

Notwithstanding the high antiquity of the family
of the Trilobites, and the remarkable characters the
different individuals which compose it, sustain in the
animal kingdom; till within a very few years, the
whole race has been almost entirely neglected by
naturalists. The first attempt at any systematic ar-
rangement of the genera and species, was made in
1815, by Alexander Brongniart, Professor of Minera-
logy, 8cc. 8cc., in Paris. f Until. that period, the term

* It is obvious, that if most of the gelatinous animals which
now inhabit our seas, were to become extinct, few or no traces
of them could be found in any succeeding depositions of earthy
matter. Whatever kind of animal life, therefore, may have been
the first which appeared in our planet, must be entirely hypothe-
tical. All that we can with certainty say of it, is, that it was
best adapted to the circumstances, in which it was to exist, and
that it was consistent with the wisdom and design which we
see every where pervading the universe.

t I cannot let this opportunity pass, without acknowledging
my obligations to Professor Brongniart, for his civilities, when
on a late visit to Paris. Every one whose curiosity leads him
to examine the royal manufactory of porcelain, a Sevres, of

10

Entomolithus Paradoxus, proposed by Linne, was ap-
plied to all the fossil remains, which in their general
appearance bore any resemblance to that found at
Dudley, and which he first described under that
name. The confusion, therefore, which existed in
this department of natural science, may readily be
imagined; especially, as the species rapidly multi-
plied, when they were supposed to throw some rays
of light on certain obscure geological phenomena.
Soon after the appearance of Professor Brongniart's
excellent work, the attention of other naturalists was
directed to this neglected part of creation. The
most important memoir, on account of the number of
species, well figured and described in it, is one by
Dr. E. W. Dalmann, published in the Transactions of
the Swedish Academy, for 1826, There is also in
the Acts of the Royal Society, at Upsal, an excellent
paper on this subject by Professor Wahlenberg.
Our highly esteemed friend, Dr. James E. Dekay,
has also given in the first volume of the Annals of
the Lyceum of Natural History of New York, some
very interesting and ingenious observations on the
nature and the structure of the Trilobites, with a de-
scription of a new genus. These are the principal
authorities which have been consulted in arranging
the present work.

Our object in the present undertaking being mere-
ly to give a monograph of the species of Trilobites

which he is the director, will no doubt acknowledge that his
talents as a philosopher, are rivalled by his accomplishments as
ft gentleman.

11

found in the rocks of North America^ we leave to
other and abler hands the more difficult and interest-
ing task of determining with precision the connex-
ion which may exist between these organic reliques,
and the relative ages of the strata in which they are
found.

It is supposed, indeed, that a sufficient number of
well characterized species have not yet been collected
and accurately described, to throw any certain and
clear light on otherwise doubtful geological pheno-
mena. What has been remarked by De Candolle,
with regard to botanical geography, is perhaps true
of these fossils as to solving the difficult problems of
geology — u Let us not forget," says he, " that this
science can only be commenced when the study of
species has been sufficiently advanced to furnish us
with numerous and well authenticated facts."

We are well aware of the difficulty of settling the
line which ought to divide species. Individuals per-
fectly identical in all their parts, are rarely, if ever
seen; though a general resemblance may be easily
traced. Among fossils, just discriminations of this
kind are more delicate, than in recent specimens.
The hand of time, accidental causes, and the influ-
ence of atmospheric changes often produce such
characters as to render the determination of fossil
species an exceedingly difficult task. We have no
doubt, therefore, that a few of our Trilobites, which
are now considered as perfectly identical with some
found in Europe, will upon fuller examination, be
discovered to be dissimilar, and of course certain

12

geological speculations grounded on the first opinion,
be ultimately abandoned.

The geographical distribution of organic remains,
is an exceedingly curious inquiry. If accurately pur-
sued, without reference to any preconceived theory,
it will no doubt furnish much information as to the
comparative ages of the different strata which com-
pose the external crust of our planet — for that
these strata were deposited or formed at periods of
time more or less remote from each other, every one
knows, to be a generally admitted geological fact.
The occurrence of similar fossils in districts of coun-
try remotely situated from each other, certainly pre-
sents a phenomenon highly interesting to the specu-
lative naturalist, and apparently indicates that the
same powerful and general causes must have con-
curred to produce these isomorphous depositions.
No fossils have contributed more to this kind of in-
formation, than those of shells, and as the mineralized
species could not be satisfactorily studied, except by
accurately comparing them with those which now
inhabit our seas and continents; the search for shells,
has become, from a simple amusement, the study of
scientific men — or, as a writer remarks, " it was only
after the period when it was perceived that geology
and ancient zoology were destined to be enlightened
by their fossil remains, that this research passed from
the hands of amateurs into those of naturalists."*

* We have not unfrequently noticed, both in the writings and
conversation of some geologists, a disposition to sneer at the
subsidiary branches of natural history. Mineralogy and con-

13

Another curious geological fact appears to be esta-
blished more especially by fossil trilobitesj it is that
precisely the same species of animal relic, is the
most generally diffused over the globe, in proportion
to the*antiquity of the rock which contains it. Thus
the transition limestone of England, France, Ger-
many and Sweden, contains the species called the
Calymene of Blumenbach, in common with the same
formation which extends over so large a portion of
the United States.

Different genera and species of the trilobite are
now found in almost every part of the globe, and are
frequently exceedingly abundant in the rocks which
contain them. That they must have swarmed in
particular places, is abundantly evident from a num-
ber of localities in our own country, — millions, for
example, must have lived and died not far from
Trenton falls, in the State of New York. There are
very few of the numerous visiters to that romantic
cascade, whose curiosity is not awaked, by the multi-
tude of these petrified beings, seemingly of another
world, which are there entombed.

chology, are light and mean in their estimation, when compared
with the study of extensive strata and ponderous boulders. Like
Irving's testy governor of Manahatta, who settled the accounts of
his clients by placing their books in the opposite scales of a ba-
lance, they decide on the value of a science, by the absolute
weight of the objects embraced by it. Geology, as well as any
other branch of natural history, may degenerate into a mere love
for the curious, or have for its principal aim, the perfection or
improvement of some ideal system of classification, without ad-
vancing a single step further.

14

Although many parts of the trilobite are now found
distributed through the rocks which contain them,
in such a manner as to lead to the conclusion, that
they were separated by decomposition, after the
death of the animal; yet the perfect preservation of
others, and the rolled and disjointed attitudes which
we should expect such creatures to assume when
disturbed, lead to the conjecture, that they have been
often suddenly destroyed, and as suddenly enveloped
in that earthy matter, which afterwards became an
indurated rock; thus preventing the separation of
the harder parts, by the slow process of decom-
position.*

The fossil remains of the trilobite family, are sup-
posed by most naturalists to belong to a race of beings
now extinct; but from the strong analogy which ex-
ists between them and certain species of crustaceous
animals now living, it is highly probable that they
will yet be found alive. This opinion will not be
regarded as visionary, when it is recollected how
large a portion of the surface of the earth is still un-
explored by its enlightened and civilized inhabitants
—how small the number of animated beings are yet
known to the scientific world— and above all the fact,
that many animals as confidently declared to be pecu-
liar to a former world, are now found to be among
the creatures at present in existence. This opinion,
we think, is quite as plausible, and far more interest-
ing, than the blank and unsatisfactory hypothesis that

* Vide De la Beche's Geological Manual.

15

all the trilobites are confined to an order of things
before the present glorious creation.*

There appears to have been known to naturalists,
when the improved edition of Prof. Brongniart's work
on the trilobites appeared in 1822, but 17 well mark-
ed species, and out of which he constructed the five
following genera, which he thus characterizes,

Genus First. CALYMENE.

Body capable of contraction into nearly a semi-
cylindrical sphere.

Buckler with many tubercles or folds. Two reticu-
lated eye-shaped tubercles.

Jlbdomen and Post-abdomen with entire edges. Ab-
domen divided by 12 or 14 articulations.

No elongated tail.

* The incorrectness of the inference that all the genera and
species of fossil animals found in the transition rocks must be
now extinct, will appear from the following extract from Bake-
well's Geology: — " The Madrcpora stylina, so common in transi-
tion lime-stone rock, is entirely wanting in the secondary and
tertiary strata, but a living animal of this species has been recent-
ly discovered in the South Seas. The Pentacrinus makes its first
distinct appearance in the lias; but is not frequently met with
in the upper strata, and disappears entirely in the uppermost for-
mations : hence it was long supposed that the species was ex-
tinct. A living Pentacrinus has recently been discovered in the
West Indies, and its stem and branches in a perfect state have
been sent to this country." (England.) In the Museum at Alba-
ny, N. Y., I have examined a recent Pentacrinus, which I con-
clude, came from the West Indies, from the proprietor's account
of the manner in which he obtained it. It has been a very
perfect specimen — but the branches are gradually dropping off."

16

Genus Second. ASAPHUS.

Body broad and rather flat. Middle lobe promi-
nent and very distinct.

Flanks or lateral lobes each double the size of the
middle lobe.

Submembranaceous expansions extending beyond the
lateral lobes.

Buckler semicircular, with two reticulated eye-
shaped tubercles.

Abdomen divided into 8 or 12 articulations.

Genus Third. OGYGIA.

Body much depressed into an oblong ellipsis — not
contractile into a sphere.

Buckler edged, a slight longitudinal furrow aris-
ing from its anterior extremity. Posterior angles
elongated into points.

Without any tubercles except the eyes, which are
neither prominent nor reticulated.

Longitudinal lobes slightly prominent.

Abdomen with 8 articulations.

Genus Fourth. PARADOXIDES.

Body depressed — not contractile.

Flanks much broader than the middle lobe.

Buckler nearly semicircular — three transverse fur-
rows on the middle lobe.

Eye-shaped tubercles none.

Abdomen with 12 articulations.

Arches of the lateral lobes, more or less prolonged
beyond the membrane which sustains them.

17

Genus Fifth. AGNOSTUS.

Body ellipsoidal — semicylindrical.

Buckler and flanks edged — the edges being slightly
elevated.

Middle lobe with two transverse divisions, each com-
posed of a single piece.

Two glandular tubercles on the anterior part of the
body.

In 1824, Dr. J. E. Bekay added a sixth genus to
the family of the trilobites, which he describes in the
following manner.

Genus Sixth. ISOTELUS,

Body oval oblong, often contracted, not unfrequent-
ly extended.

Head or buckler large and rounded, equalling the
tail in size, with but two oculiform tubercles.

Abdomen with 8 articulations.

Frontal process beneath, with two semilunar ter-
minations.

Post-abdomen or tail broad, expanded with indis-
tinct divisions, as large as the buckler.

Longitudinal lobes very distinct.

This genus, he remarks, will be sufficiently distin-
guished from the five genera proposed by M. Jllexan-
dre Brongniart in his valuable and truly philoso-
phical work on the trilobites by the following parti-
culars.

From Calymene. By the presence of but two tu-
B 2

18

bercles on the buckler not reticulated; by the abdo-
men with but 8 articulations.

From Jlsaphm. By the middle lobe, which is double
the size of the lateral ones; by the absence of a mem-
branaceous expansion on the sides; by the non-reticu-
lation of the eyes, Sec.

From Ogygia. By the rolled form, the rounded
posterior angles of the buckler, and the distinct arti-
culation of the longitudinal lobes.

From Paradoxide and tfgnoste by characters too
obvious to be enumerated. (See Annals of N. York
Lyceum, Sec. Vol. I. pp. 174-5.)

In 1826, J. W. Dalman published in the Transac-
tions of the Swedish Academy, and also in a separate
work, an account of the trilobites found in the North
of Europe, in which he has enriched the family by a
number of fine species, and with the following genera,
which he modestly proposes merely as subdivisions.

Genus Seventh. NILEUS.

Body short, capable of contraction into a sphere,
smooth, convex.

Mdomen with about 8 articulations, without any
dorsal longitudinal furrows.

Buckler sub-lunate, with large lateral eyes.

Tail expanded, not so large as the buckler, without
lobes.

Genus Eighth. ILLJENUS.
Body ovate oblong, contractile.

19

Head rounded in front, eyes small, in the temples,
very remote.

Abdomen with from 9 to 10 articulations, trilobate.
Tail expanded as large as the head.*

Genus Ninth. AMPYX.

Body very short, contractile.

J3uckler large, triangular, gibbous; eyes not re-
markable.

Jlbdomen short, articulations few (6 ?), trilobate.

Tail expanded, not so large as the head.

Professor Dalman has two other genera, which he
calls Olenus and Battus, the first is the Paradoxides,
and the second the Agnostus of Brongniart.

In the 8th Volume of Annales des Sciences Natu-
relles there is a highly valuable paper " Sur les Tri-
lobites et leurs gisemens," by the Count Rasoumow-
sky, in which he describes some new trilobites from
Russia; the one which he has figured and described
as a Calymenef from Tzarsko-Selo, undoubtedly be-
longs to a new genus, very near to the Isotelus. The
middle lobe is visible or naked through its whole ex-
tent, and the lateral lobes near the tail are covered
with a thick cuticular membrane. This genus we
propose to call Hemicrupturus, and may be thus cha-
racterized.

* Some of the species described by Professor Dalman as in-
cluded in this genus, we think ought to be referred to that of the
Isotelus.

t The editors of the Annales remark that this is not a Caly-
mene. but that it appears to belong to the genus Asaphus.

Genus Tenth. HEMICRUPTURUS.* — Grem.

Rody contractile.

Buckler oculiferous and not lobate.

Abdomen trilobate, with 8 articulations.

Tail, costal arches covered, middle lobe naked.

The asaphus expansus of Dal man, and several
other known species may be arranged under this
genus.

As Count Rasoumowsky has given no specific ap-
pellation to the fossil above alluded to, we propose to
call it after his own name, Hemicrupturus Rasoumow-
skiL We examined the fine specimen from which
our cast is taken in the cabinet of the Baltimore Col-
lege, and for this favour we are indebted to the kind-
ness of Dr. J. J. Cohen, one of the Professors in that
rising institution.

The following list includes all the genera and spe-
cies of the Trilobite Family, hitherto described as
far as known to the author. It is taken from De
La Beche's Manual of Geology.

NAMES.

Calymene Blumenbachii,
Macrophthalma,
Variolaris,
Tristani,
Bellatula,
Ornata,
Verrucosa,

AUTHORS.

LOCALITIES.

Al. Brong.

Europe — U. States.

do.

Europe— U. States.

do.

Europe.

do.

Europe— U. States.

Dalman.

Europe.

do.

Europe.

do.

Europe.

From three Greek words which signify half-concealed tail.

NAMES.

AUTHORS.

LOCALITIES.

Calymene Polytoma,

Dalman.

Europe.

Artinura,

do.

Europe.

Sclerops,

do.

Europe.

Schlotheirni,

Brown.

Europe.

Latiferus,

do.

Europe.

Asaphns Coi'nigerus,

Al. Brong.

Europe.

Caudatus,

do.

Europe — U.

States.

Hausmanni,

do.

Europe — U.

States.

De Buchii,

do.

Europe.

Brongniartii,

Deslongchamps.

Europe.

Extenuatus,

Wahlenberg.

Europe.

Granulatus,

do.

Europe.

Expansus,

do.

Europe.

. Crassicauda,

do.

Europe.

Angustifrons,

do.

Europe.

Heros,

Dalman,

Europe.

Platynotus,

do.

Europe.

Frontalis,

do.

Europe.

Lseviceps,

do.

Europe.

Palpebrosus,

do.

Europe.

Sluzeri,

Europe.

Ogygia Guettardii,

Al. Brong.

Europe.

Desrnaresti,

do.

Europe.

Wahlenbergii,

do.

Europe.

Sillimani,

do.

Europe — U.

States.

Paradoxides Tessini,

do.

Europe.

Spinulosus,

do.

Europe.

Gibbosus,

do.

Europe.

Scaraboides,

do.

Europe.

Hoffii,

Goldf'uss.

Europe.

Nilevis Armadillo,

Dalman.

Europe.

Glornerinus,

do.

Europe.

22

NAMES.

Illsenus Centaurus,
Centrotus,
Laticauda

Ampyx Nasutus,
Olenus Bucephalus,
Agnostus Pisciformis,
Isotelus Gigas,
Planus,

AUTHORS.

LOCALITIES.

D aim an.

Europe.

do.

Europe.

Wahlenberg.

Europe — U. States.

Dalman.

Europe.

Wahlenberg.

Europe.

Al. Brong.

Europe.

De Kay.

United States.

do.

United States.

Genera and Species not fully determined.

Trilobites Cephaleurya,
Simla,
Granulata,

Bilobites Lunulata,
Lobata,

Rafinesque,
do.
do.
do.
do.

United States.
United States.
United States.
United States.
United States.

From the short descriptions given by Professor
Rafinesque of the five last mentioned fossils, I con-
clude that they belong to the genus Calymene of
Brongniart.

The study of the trilobites naturally leads to the
consideration of those beings which appear to have
inhabited our earth previous to the creation of man.
Every one knows that the sceptical naturalist has
drawn from these vestiges of organic life, an argu-
ment contradictory to the Mosaic account of the his-
tory of the world, and though every cavil of the least
importance, urged against the truth of the sacred
historian, has been triumphantly confuted, still, the
geological sciolist boldly impugns his veracity, when-
ever any new facts in his science can be distorted to

23

his purpose. Such being the case, we cannot con-
clude this preface without briefly stating two or
three methods by which any seeming discrepancies
may be explained. First, those who imagine that
the six periods of creation, mentioned in the begin-
ning of the pentateuch, mean literally days of 24
hours each, believe that, as only a small part of the
earth was at first required for the abode of man and
the higher animals, the present continents might
have remained as long beneath the waters, and have
undergone every change necessary to solve this geo-
logical puzzle.

Again, others have thought that Moses, after re-
cording, in the first sentence of Genesis, the great
truth that all things were made by the will of an in-
telligent Creator — passed silently over some interme-
diate state of the earth, which had no direct relation
to the history, or to the duties of man — and proceed-
ed to describe the successive appearance of the pre-
sent order of things. On this supposition, the fossil
remains and peculiarities in the structure of the
earth may have belonged to that intermediate state.

A third method of explaining the difficulty, and
which we think highly satisfactory, is, by under-
standing the days of creation to mean, not ordinary
days, but periods of time, in which the recorded events
took place in the order described so briefly by the
sacred historian. It is acknowledged by every one
competent to judge, that among the Hebrews, days
and weeks were often used in this manner. The ac-
cordance between the order in which, according to

24

the account of Moses, the work of creation was ac-
complished, and the order in which the fossil re-
mains of plants and animals are deposited in the
earth, has surprised, and has been acknowledged by
learned sceptics themselves.*

It will be useless to push these arguments further.
The catastrophes which have produced the seconda-
ry strata, and the diluvian depositions, could not
have been local or partial phenomena; but rather
than call upon a comet, with the abstracted philoso-
pher, to deluge the earth for every new geological
epoch — -or to change the axis of motion of our planet
— or to resort to any of his wild, fanciful, and impious
theories, we should, with Sir Humphrey Davy, even
prefer the dream that all the secondary strata were
created^ filled with the remains, as it were, of animal
life, to confound the speculations of our geological
reasoners.

* The Baron Cuvier, on this subject, remarks, respecting the
Jewish legislator — "His books show us, that he had very perfect
ideas respecting several of the highest questions of natural philo-
sophy. His cosmogony, especially, considered purely in a scien-
tific point of view, is extremely remarkable, inasmuch as the
order which it assigns to the different epochs of creation, is pre-
cisely the same as that which has been deduced from geological
considerations."

25

ACKNOWLEDGMENTS.

Every author who attempts a Monograph of any
of the departments of Natural History, must neces-
sarily depend, in a greater or less degree, upon the
kindness and liberality of others. Rare and unique
specimens, particularly of fossil species, are often
scattered through different cabinets, and his work
would be rendered very imperfect, if they were not
intrusted to his care. In preparing the following
Monograph on the plan of giving exact models of
the species, instead of illustrating them by engrav-
ings in the usual manner, the specimens when used
by the artist are perhaps more liable to accident, and
it was at first supposed that this circumstance might
have prevented the original design. But in no in-
stance, where an application has been made, either to
a public institution or to a private cabinet, has the au-
thor met with a refusal; indeed the courtesy, kind-
ness, and liberality which he has experienced from
naturalists, who have every where aided him in the
prosecution of his work, form no inconsiderable
portion of the gratification which he has received.
Besides the acknowledgments to public museums,
and to individuals, which are made in the body of
the work, the author is desirous of recording in this
place, the following cabinets from which he has de-
rived much assistance.

IN PHILADELPHIA.

The Cabinet of JOHN P. WETHERILL.

The Cabinet of the ACADEMY OF NATURAL SCIENCES.

26

The Philadelphia Museum. — (PEALE'S.)

The Cabinet of P. A. BROWNE, Esq.

The Cabinet of DR. R. HARLAN.

The Cabinet of WILLIAM HYDE.

The Cabinet of J. PIERCE.

The Cabinet of the GEOLOGICAL SOCIETY.

LAMBDIN'S Museum, Pittsburgh, Pa.
The Cabinet of D. KEIM, Reading, Pa.

IN NEW YORK.

The Cabinet of the LYCEUM OF NATURAL HISTORY.
The Cabinet of DR. J. E. DEKAT.
The New York Museum. — (PEALE'S.)

IN ALBANY.

The Cabinet of the ALBANY INSTITUTE.
The Cabinet of PROFESSOR T. R. BECK.
Albany Museum.
The Cabinet of DR. JAMES EIGHTS.

The Cabinet of the RENSSELAER SCHOOL.

IN BALTIMORE.

The Cabinet of DR. JOSHUA J. COHEN.
The Cabinet of the BALTIMORE COLLEGE.
The Cabinet of the ATHENEUM.
The Baltimore Museum.

The Cabinet of PROFESSOR HALL, MOUNT HOPK.

TRILOBITES, dze.

GENUS CALYMENE. Brongniart.

THE name of this genus is derived from a Greek
word which signifies obscure or concealed. The fossil
animals included by it are characterized as having
contractile bodies; the buckler as bearing many tu-
bercles or folds — the cheeks as being oculiferous,
and the abdomen and tail as being composed of from
twelve to fourteen articulations or joints, without
any membranaceous expansion. The Calymenes in
thickness are nearly semicylindrical, and the buck-
ler in front presents a chaperon or upper lip more or
Jess raised. In perfect specimens, there is a small
furrow which seems to indicate a separation between
the upper and under parts of this kind of lip. The
eyes are always raised, and frequently present the re-
markable structure observable in many of the Crusta-
cea; but as this part is generally very prominent, the
reticulations of the eye are commonly worn off or in-
jured.

Professor Brongniart places but little confidence
in any of the generic characters above enumerated,
except the number of articulations of the abdomen:

28

these, however, in our opinion, are more vague and
uncertain than most of the others. The genus, how-
ever, we think may be readily identified, after becom-
ing- familiar with one well characterized species.
The general aspect of the buckler is peculiar — the
body is not so depressed as in most other genera, and
the lateral lobes are destitute of all membranaceous
expansion.

To the genus Calymene, belongs the celebrated
Dudley fossil, called Entomolithus paradoxus by Blu-
menbach, but which is not the same organic relic,
to which Linne applied that name.

This genus includes a great number of species, and
though some of them are said to be found in different
and distant parts of the globe, they are according to
our limited observation, for the most part confined,
like recent species of animals, to particular districts.
The C. polytoma, C. pulchella, C. bellatula, C. con-
cinna, C. sclerops, and the C. punctata, all finely
figured by Professor Dalman, and which are found
in Sweden, have not yet been noticed in any part of
North America.*

CALYMENE BLUMENBACHII. Brongniart. Cast No. 1.

Clypeo rotundato, tuberculis sex distinctis in
ironte; oculis in genis emintissimis; corpore tuber-
culato.

* See the valuable and extensive communication of J. W.
Dalman, M. D , on the Trilobites, in the Transactions of the-
Swedish Academy for 1820, part 2d. -

29

In this species the upper lip presents a furrow pa-
rallel to its edges. The lip is straight. The cheeks are
a little projecting. There are six rounded tubercles
on the front, and fourteen articulations on the back;
the tail is small, and the shell is covered with small
rounded tubercles of unequal sizes.

The above is Professor Brongniart's description of
this trilobite, which is the famous Dudley fossil de-
scribed and figured by Littleton, in the Philosophical
Transactions, (London) in 1750. According to Dai-
man, several distinct European species have been
published under this name. The true C. Blumen-
bachii, he says, has thirteen articulations to the abdo-
men, and about eight to the tail. In -he cabinet of
G. W. Featherstonhaugh, Esq., we have examined a
fine perfect specimen from Dudley,* in which there
is fourteen abdominal joints. There can be no doubt,
however, that several species have been confounded
under the name of C. Blumenbachii; Dalman's C,
Tuberculata and C. Pulchella are, we think, distinct
from it, though he has marked them only as varieties.

The true C. Blumenbachii, no doubt, abounds in
North America, and is one of the few examples of the
occurrence of an identical species on both continents.
The late Abbe Correa sent a perfect specimen to
Brongniart, from the vicinity of Lebanon, in the state

> This famous trilobite, once formed a part of the cabinet of
Mr. Parkinson, the distinguished author of the " Organic Re-
mains," and is accurately figured on one of the plates of that
splendid work. At the sale of the late Mr. Parkinson's fossils,
it was purchased by Mr. Featherstonhaugh,

30

of Ohio. We have also seen a number of specimens
from that state, which could not be distinguished
from the Dudley trilobite. Our model was taken
from a specimen found at Trenton Falls, in the state
of New York.

The three following species found in the United
States, will no doubt be considered by many as mere
varieties of the C. Blumenbachii; we have ventured,
however, to call them by distinct names.

CALYMENE CALLICEPHALA.* Green. Cast No. 2.

Clypeo antice attenuato, figura liliiformi in fronte
depictaj oculis minimis; abdomine quatuordecim ar-
ticulis; corpore piano.

The buckler is subtriangular; on the front there is
a figure in high relief, somewhat resembling a fleur
de liSj or perhaps more, the capital of a Corinthian
column. The oculiferous tubercles are rather lower
down on the cheeks than usual. The articulations
of the abdomen and the tail cannot well be distin-
guished from each, other; fourteen in all may be
easily counted. The middle lobe of the abdomen is
nearly equal in breadth throughout. The ribs, or
costal arches, are not grooved or bifurcated at their
extremities. Length nearly two inches and a half.

This beautiful species is in the Philadelphia Mu-
seum, where it is labelled as being found in " Hamp-
shire, Virginia." It is mineralized by a dark yellow-

From two Greek words, which signify " beautiful head."

31

ish limestone. It differs from the C. Blumenbachil,
in the form and number of its articulations; in the
shape of the head; in having only two flat tubercu-
lous elevations on the front; and in other particulars.
In the cabinet of the New York Lyceum, and in
that of J. P. Wetherill, Esq. there are some examples
of this species from the Miami river, near Cincinna-
ti, Ohio. I have also seen it from Indiana, in a dark
coloured limestone, very much distorted. It has
never been found at Trenton falls, or at any other lo-
cality, as far as my knowledge extends, which yields
the true C. Blumenbachii.

CALYMENE SELENECEPHALA.* Green. Cast No. 3,

Clypeo antice rotundato, margine omni valde in-
crassato; prominentia frontal! utrinque trituberosa;
corpore tuberculato.

The buckler is regularly lunate; the margin is
slightly reflected or raised anteriorly, the posterior
edge forms a continuous rim, running nearly parallel
with the articulations of the abdomen. The front on
each side has one large and two small tubercles, near
its superior edge. The oculiferous tubercles on the
cheeks are on a line with the lowest frontal tubercle.
There are fourteen distinct articulations; but as the
tail is mutilated and distorted, the total number of
joints cannot, from this specimen, be ascertained.
The body appears to have been covered with small

* From the Greek for " lunate head."

32

pustules, These are very evident on the front. Cos*
tal arches simple, or not grooved. Length, one inch
and three-fourths, breadth of the buckler one inch
and one-fourth.

This species resembles a little the C. Pulchella of
Dalman. The specimen from which the model was
taken, is in the possession of Mr. R. Peale, of New
York, who willingly lent it for this monograph. He
informed me that it was found in the state of New
York, but he was unable to name its precise locality.
It occurs in a soft ash coloured limestone. No other
petrifaction is observable in the fragment of rock
which contains it.

CALYMENE PLATYS.* Green. Casts No. 4 and 5.

Clypeo antice rotundatoj prominentia frontal!
utrinque quatuor tuberculis.

The buckler is probably semilunatej but as the an-
terior portion is lost, this cannot be determined with
precision. The posterior raised rim is not continu-
ous, as in the C. Selenecephala> but is separated by
the longitudinal dorsal furrows. The front is distinct*
ly divided from the cheeks, and has four tubercular
prominences on each side. Three of them are near-
ly on a line with the lateral edge of the cheeks, and
gradually diminish in size, as they descend to the
anterior part of the buckler. The other is smaller,
and is between, and a little to the side, of the upper

* From a Greek work which signifies Flat,

33

two. The cheeks form spherical triangles. The ocu-
liferous prominences are close to the second large
tubercle on the front. The cheeks are, however,
quite imperfect. The articulations of the back can-
not be distinguished from those of the tail. In our
specimen they are all beautifully distinct, and are
twenty-two in number. The posterior raised rim of
the buckler seems to form an articulation; its ex-
tremities on each side are a good deal thickened and
expanded. The costal arches suddenly curve down-
wards and backwards, near their middle, so as to di-
vide the abdomen and tail into five unequal sections.
The whole length is nearly three inches. The
breadth of the buckler nearly two inches.

This fine large Calymene was accidentally disco-
vered on the Helderberg mountain, by my friend,
Professor T. R. Beck. One of the loose pieces of
sandstone rolling over, near his feet, presented him
the fine natural mould, from which he has kindly per-
mitted our cast to be taken. The animal relic once
enclosed in this matrix, must still be near that locali-
ty, and yet remains undiscovered, to reward the en-
terprise of some more fortunate naturalist.

One of our models represents the natural mould
found by Dr. Beck. The other is a cast taken from
it and exhibits, more satisfactorily, the various parts
of the animal.

34

CALYMENE MICROPS.* Green. Cast No. 6.

Clypeo antice subattenuato;' occulis minimis in
lateribus capitisj abdominis articulis a 14 ad 18$ cor-
pore depresso.

The buckler is semielliptical, slightly punctate, and
much depressed anteriorly \ the front and cheeks are
not very distinctly marked. The eyes are very re-
mote from each other, being situated near the poste-
rior lateral angles of the head. They are not very
prominent, and exhibit no marks of being reticulated.
Before the eye on each side, there is a slight trans-
verse indentation. It is difficult to distinguish the
articulations of the abdomen from those of the tail.
They are from fourteen to eighteen in number. Where
the lateral lobes remain perfect, two narrow raised
lines appear between each of the ribs; these are most
evident on the caudal extremities of the animal. The
middle lobe is in the form of a long, slender, and
acute cone. The whole animal is an inch and a quar-
ter long, and is much more depressed than any other
Calymene which we have seen.

I am indebted to Mr. Titian R. Peale for the use of
the original from which our model was taken, his li-
berality to those who cultivate Natural History is
proverbial, and needs no encomium from me. The
C. Microps is said to have been found near Ripley,
Ohio. It occurs in black limestone.

The eyes of this Calymene are small in compari-

* From the Greek for " small eyes."

35

son with those of some other species — particularly
the C. Bufo, C. Macrophthaima, and C. Anthiops.

CALYMENE ANCHIOPS.* Green. Cast No. 7.

Clypeo antice, caudaque postice rotundatis; oculis
approximis, magnis, excertisj articulis vigenti$ cor-
pore piano.

The buckler of this species is irregularly hemis-
pherical $ the front pyriform and without pustula-
tions. The cheeks are almost entirely occupied by
the eyes, which are placed very near each other on
the upper part of the forehead ; are very large and
trilobate, the side lobes being elongated and at-
tenuated in front. The articulations of the back are
twenty in number, those of the abdomen not being
distinguishable from those of the tail. The costal
arches of the side lobes are round near their extremi-
ties, and are intersected with two or three raised
lines. Length nearly four inches. Breadth about
two inches.

It gives me great satisfaction in being able to de-
scribe, and to present to naturalists a good cast of
this Calymene, which has excited for a long time so
much interest and perplexity. The original fossil
from which our plaster model was made is now de-
posited in the cabinet of the Albany Institute, and is
the identical specimen from which a cast was long
since made, by Dr. Hosack of New York, a specimen

* From two Greek words which signify " eyes approximate."

36

of which he sent in July, 1819, to the Royal Acade-
my of Science, in France. Professor Brongniart re-
ferred the animal from which this model was taken,
though with much hesitation and doubt, to the spe-
cies, Calymene Macrophthalma. He remarks con-
cerning it, " II est beaucoup plus gros que les autres
indiviclus, et a pres de neuf centimetres de longueur.
C'est avec doute que je rapporte cette empreinte
tres-peu nette a Pespece actuelle; mais malgre ses
formes obtuses, et 1'absence de tout detail, elle est si
remarquable par la grosseur de ces yeux et par le
prolongement de son bouclier qu'on peut presumer
qu'elle appartient an calymene macrophthalme, et
avec d'autant plus de probabilite qu'elle vient aussi
des Etats Unis d'Amerique. Elle a etc trouvee,
suivant M. Hosack, dans un schiste." We have seen
the cast alluded to in the above note, and are not at
all surprised at the uncertainty which it has occa-
sioned. The apparent prolongation of the buckler is
entirely occasioned by the loss of a small fragment
from that portion of the head. The form and posi-
tion of the eyes, further distinguish it from any of
the numerous specimens of C. Macrophthalma, that
we have examined. The raised lines which we have
noticed as intersecting the costal arches of the lateral
lobes are remarkable, though they may have been
produced by accidental fissures in the epidermal
covering of the animal. The head of the C. Ma-
crophthalma is always marked by minute and promi-
nent granulations, like shagreen — nothing of this kind
appears on the buckler of the C. Anchiops.

37

I am informed by my friend, Dr. T. R. Beck, to
whose liberality I owe this interesting species, that it
was found in Ulster county, New York. It was sup-
posed by Dr. Hosack) to have been discovered in the
vicinity of Albany. Respecting the locality and geo-
logical relations of this trilobite, Professor Brong-
niart remarks, " un modele en platre de trilobite en-
voye a I'Acaclemie des Sciences, en Juillet, 1819,
par M. Hosack, et que j'ai rapporte, autant que la
chose etait possible, et toujours avec doute, au
calymene macrophthalme, a etc trouve dans le terri-
toire d'Albany, etat de New York. Or, les environs
de cette ville sont indiques, sur la carte geologique de
M. Maclure, comme formes de terrains de transition.
M. Hosack dit qu'il a etc trouve au milieu d'un
rocher ardoise, c'est a dire, dans un schiste proba-
blement analogue a celui des environs d'Angers, qui
renferme les Ogygies, et ce trilobite ce rapproche un
peu de ce genre par la grosseur des tubercules qui
recouvrent les yeux on en tiennent la place." The
rock in which the Calymene Anchiops is found, ap-
pears to be a clay slate.

CALYMENE DIOPS.* Green. Cast No. 8, and fig. 2.

Clypeo lobato piano; rugis tribus in lateribus
frontis; tuberculis oculiformibus, eminentissimis et
duplicibus; articulis octodecim; cauda rotunda.

This species is very distinct from every other Caly-
mene that we have seen. The outline of the buckler is

* From the Greek for " Double Eyes."

D

38

lobate lunate; the front is very convex, and a good
deal elevated above the cheeks or sides, from which
it is divided by a deep furrow; on the posterior mar-
gin of the front on each side, close to the groove there
is a prominent circular tubercle, before which there
are three small transverse wrinkles. The cheeks are
subtriangular; the oculiform tubercle is near the pos-
terior superior angle, and is only separated from the
tubercle on the front, by the furrow or groove, so that
the animal seems to have had double eyes on each
side; there are two curved lines on each side below
the eyes, crossed near the front by a deep short canal.
The middle lobe of the abdomen and tail is rather
longer than the lateral lobes, and is rounded and very
prominent throughout. It is composed of 18 articu-
lations, seven of which appear to belong to the tail;
it is, however, somewhat difficult to define the length
of the tail with precision. The costal arches of the
lateral lobes, particularly those near the tail, are
bifurcate. Length almost three inches.

The original fossil, from which the cast was taken,
is in the New York Museum. I am indebted to Mr.
Rubens Peale, the liberal proprietor of that flourish-
ing and important institution, not only for the use of
it in this Monograph, but also for some valuable in-
formation relating to other species. The precise
locality of Mr. Peale's specimen is not known, but
in the cabinet of J. P. Wetherill, Esq., there is a fine
head of the C. diops which was found in the State of
Ohio. Both specimens are mineralized by the same
kind of soft grey coloured limestone — and I have

39

but little doubt that they were derived from the same
place.

CALYMENE MACROPHTHALMA.* Brongniart. Cast No. 9.

Clypeo antice, caudaque postice attenuatis, oculis
magnis exsertis.

This species, according to Al. Brongniart, who first
described it, is remarkable for the magnitude and
protuberance of its eye-shaped tubercles, and by the
prolongation of the anterior portion of the buckler,
in the form of a snout.

The back is marked by .12 or 13 articulations,
which are thicker than those of the tail. The tail is
short, pointed, and without expansion.

The middle lobe, or front of the buckler, in this
calymene, is said by Brongniart to be marked on
its sides by three oblique plicae or wrinkles, but we
have not been able to discover this character in any
of the specimens to which we have access; neither
do they exhibit any remarkable prolongation in the
anterior portion of the buckler, as stated in his spe-
cific character. The specimens which we have exa-
mined, agree pretty well with the representation he
has given of the C. Macrophthalma, Plate I. fig. 5. A.
B. Sc C. made from a drawing by Mr. Stokes, from
a fossil found in Coalbrookdale, (Eng.)

This trilobite is common in several parts of the

* From the Greek for " Great eyes."

40

United States. According to Dr. J. E. Dckay,* the C.
Macrophthalma is found on the Helderbergmountains,
near Albany, and at Coshung creek, not far from
Seneca lake, in the State of New York. It occurs
also at Leheighton, in Pennsylvania — at the Falls of
the Ohio, and at several other localities. We have
examined a number of specimens of the C. Macroph-
thalma, contained in the rich cabinet of fossils, in
the Academy of Natural Sciences, and have never
seen any individual which resembles the fig. 4, Plate
I. of Brongniart; and in no instance is the front of
the buckler marked by three oblique folds, a charac-
ter stated as peculiar to this species. The C. Macroph-
thalma, (variety) occurs in large quantities in Le-
heighton in Pennsylvania, and we arc indebted to
Mr. D. Keim, for some fine specimens from that lo-
cality.

The authority of Professor Brongniart is sufficient
to place the C. Macrophthalma among the species of
the United States, though we have been unable fully
to identify it with his description.! He received a

* See Annals of Lyceum, Vol. I. p. 188.

t We have seen in the Cabinet of Mr. Featherstonhaugh, a fine
group of trilobites, in the transition limestone, from Dudley,
(Eng.) Among them there is a perfect head, which agrees ex-
actly with the description given by Mr. Brongniart of the head
of his Calymene Macrophthalma. If this belongs to the true
macrophthalma, our species under that name is entirely distinct.
Since our work had been prepared for the press, Dr. J. J. Cohen,
of the Baltimore College, has shown us the fragment of a caly-
mene from Berkley, Virginia, which agrees with Bvongniart's de-

41

specimen, transformed into red jasper, from Prof.
Ducatel, said to be found in the United States — no
precise locality is given. Our model represents the
animal which is supposed to be the one intended by
Brongniart as the C. Macrophthalma of North Ame-
rica. It is, in our opinion, a variety gf the C. Bufo.
There can be no doubt that several species have been
confounded under the name of C. Macrophthalma.

The following extract of a letter from Professor
Ducatel to the author, referring to the locality of this
species, will be read with interest.

" I cannot be positive as to my recollection of the
locality of the fossil referred to by Brongniart and
yourself, but believe it is one of several found by my
friend Dr. M'Culloh, in the neighbourhood of Berk-
ley Springs, Virginia. I regret that I have not in
my possession another specimen to present to you."

CALYMENE BUFO. Green. Cast No. 10.

Clypeo rotundato, convexo, punctato; abdominis
articulis sexdecimj cauda attenuata; corpore piano.

Buckler semilunate, front very large, rounded be-
fore and arcuated at the insertion of the middle lobe;
surface convex, and marked with numerous depressed
pimples. Mouth large, lunate, resembling that of a

scription of the macrophthalma, and with the above fossil from
Dudley. We regret that the imperfection of the fossil prevents
our giving a satisfactory cast of it.

D 2

42

toad or frog, with a narrow raised rim on the upper
and under lip. Below the chin there are no pustula-
tions. Cheeks small, triangular, and separated from
the front by a deep, rectilinear furrow; the eyes in
our specimen are much injured, but they are large,
and near the upper angle of the cheeks. Middle lobe
with a series of distinct double articulations. Lateral
lobes wider than the middle lobe, ribs deeply grooved
near their insertion; articulations of the abdomen
twelve; of the tail ten. Length four inches and a
half; breadth of the buckler nearly two inches.

This fossil was presented to me some time since
by Thomas P. Johnson, Esq., who mentioned that it
was found in New Jersey, but that he could not learn
its precise locality. Near Patterson, in that State,
some trilobites have been discovered — perhaps the
C. Bufo may have been derived from that locality. It
is composed of a dark greyish limestone, easily cut
with a knife.

CALYMENE BUFO. Variety, RANA. Cast Nos. 1 1 & 12.

This fine specimen differs from the one above de-
scribed, in having the front of the buckler rather
smaller, and of a different contour. The whole of
the shell is also covered with granulations, which
only appear on the head of the other; this, however,
may be only an imperfection in the specimens in our
cabinet.

I am indebted to the Albany Institute for the origi-
nals of the models Nos. 11 & 12. They were found at

43

Seneca, Ontario County, New York, in dark, slaty
limestone, which also contains cubical crystals of
iron pyrites. A fortunate blow of the hammer has
fractured the rock which contains this trilobite, so
neatly, as to present us at the same time with the
petrified animal in an almost perfect state, and also
with the mould or matrix in which it was imbedded.
This arrangement is beautifully illustrated by our

models.

%

GENUS ASAPHUS. Brongniart.

This genus derives its name from the Greek word
Arctpvs — obscure. It embraces perhaps more species
than any other genus of the family of trilobites.
About twenty have already been discovered. Most
of them are very characteristic and can easily be de-
termined, but as the genus Asaphus, is intermediate
between Calymene and Ogygia, it is sometimes a
little difficult to decide the genus to which the inos-
culating species on each side, belongs.

In general, the Asaphs may be known by the body
being very much depressed, and by the membranaceous
development, which extends beyond the lateral lobes.
The middle lobe of the abdomen, is rarely more
than one-fifth the width of the body. As the abdo-
men and tail of the Asaph are the only portions of
the animal commonly found entire, the distinctive
characters of the genus above given, may generally
be ascertained.

Professor Brongniart remarks, that the ribs of the
which correspond in number and position to

44

the articulations of the middle lobe, " are sometimes
simple or undivided, at least in the post abdomen,
but that they are always bifurcated in the Calymene"
As far as our observations have extended, these re-
marks do not apply either in the one case or the
other.

The head or buckler of the rfsaph, is not so deeply
divided into three lobes as the Calymene; they are,
however, quite distinct. The oculiferous tubercles
are in some species exceedingly well marked by a re-
ticulated structure.

This genus often occurs at the same localities with
the Calymene, though in some instances it seems to
occupy rocks peculiar to itself. Dr. John Bigsby, in
his list of organic remains occurring in the Caiiadas,
states, that he never found a single species of the
genus Calymene, on the north side of the River St.
Lawrence, although the Asaphs were very abundant.*
In his Sketch of the Geology of the Island of Mon-
treal, he however observes: " Of Trilobites, the
Asaph genus is the most abundant, they approach
nearest the species caudatus, of Brongniart. I have
found no entire Calymene, but many bucklers or heads
of the Blumenbach species, some of them an inch
and a half in diameter. They are found whole in
considerable numbers in the vicinity of Quebec. "f

* Silliman's Journal, vol. viii. p. 83.

t Annals New York Lyceum, vol. i. p. 214.

45

ASAFHUS L ATI co STATUS.* Green. Cast No. 13.

Cauda praelonga, pars ad marginem vix membra-
nacea; cute coriacea, tuberculis minimis; costis lads,
convexis et valde clistinctis.

The fragments of this species, which we have exa-
mined, comprise ten articulations of the middle lobe,
and the corresponding ribs of the sides, all in a very
good state of preservation; the extent to which the
membranaceous expansion reached beyond the tail and
the lateral lobes is very apparent, but it has been un-
fortunately broken off all round. Our specimen ap-
pears to be a natural cast of the internal part of the
shell, or the coriaceous covering of the animal.

The portion of this specimen of trilobite which
still remains perfect, is two inches long, and three
inches and a quarter broad. The middle lobe exhi-
bits the appearance of a very exact and gradually ta-
pering cone, its articulations being rounded and
slightly flattened on the top. The ribs of the lateral
lobes are nearly straight, slightly arched, broad,
rounded, and gradually increase in width from the
point of their insertion; they are simple or not bifur-
cated throughout, and are covered with very minute
granulations, which are probably produced by the
sandstone in which the animal is mineralized. The
membranaceous expansion near the caudal termina-
tion, is a good deal prolonged.

The A. Laticostatus occurs in a light coloured fer-

* From the Latin for " broad ribbed."

46

rugenious sandstone, which contains a multitude of
other fossil remains, particularly a large species of
Productus and of Terebratula. It is said to have
been found in Ulster county, in the State of New
York, by the late Charles Wilson Peale, Esq., the
distinguished founder of the Philadelphia Museum.
During the memorable search after the bones of the
Mastodon Giganteum, in the marl pits of that county,
this enterprising naturalist procured our Asaph with
many other remarkable petrifactions. The rocks
which contain them were probably found not in situ^
but were masses rolled from the neighbouring Shaw-
angunk mountains,* which by some geologists are
supposed to be a link in the grand chain of the Alle-
ghanies. Mr. R. Peale, of New York, lately visited the
rich repository of fossils in Ulster County, and pro-
cured a number of specimens of the A. Laticostatus,
all of which he has kindly permitted me to examine.
These are much smaller than our cast, but in many
instances the caudal elongation is perfectly de-
veloped. The A. Laticostatus also occurs in the
Helderberg mountains, specimens of which are in the
Albany Institute.

ASAPHUS SELENURUS.! Eaton. Casts Nos. 14 & 15.

Cauda semilunarij costis angustis, valde distinctis;
abdominis articulis duodecim; corpore convexo.

* The Lenape tribe of Indians, who formerly inhabited this
district of country, gave the name of Shawangunk to this stu-
pendous ridge of hills — a name which has been very properly pre-
served.

t Derived from Selene, moon, and ouros, tail.

47

I am indebted to Professor Eaton, for two speci-
mens of this very interesting species. In his Geolo-
gical Text Book, he thus describes it: " Tail cres-
cent-form, or concavo-convex, with the convex side
forward, upon which the post abdomen terminates:
abdomen contains about 1 2 articulatious, with an ab-
rupt termination equal in breadth to one-fourth of
the length of the transverse lunate tail; the articula-
tions of the side lobes gradually incline towards the
axis of the body, until the last pair terminate at the
tail. Found in transition limestone at Glenn's Falls,
and Becroft's mountain, near Hudson. I have a spe-
cimen from Becroft's mountain, with part of the
original covering of the animal remaining."

When we first noticed the remarkable lunate ap-
pearance of the tail of this Asaph, we supposed that
it was occasioned by some accident, but there seems
no doubt that this conformation is natural. In our
specimens of this species, which are not however per-
fect, the articulations of the abdomen do not exceed
8 in number. The representation of this animal re-
main given by Mr. Eaton, plate 1, figure 1, is exceed-
ingly inaccurate; it will confuse rather than illustrate
the subject. Our cast and the drawing, we believe,
are taken from the same specimen, which was kindly
loaned by Mr. Eaton for this work. It is but jus-
tice to the amiable, industrious, and indefatigable au-
thor of the Geological Text Book to remark, that he
regrets as much as any one, the insufficiency of his
figures of the trilobites, to give any correct idea of
the fossils they are intended to represent.

48

In the cabinet of the Albany Institute there are a
number of specimens of the A. Selenurus. One of
our models represents the natural mould made by
the animal in the rock; the other is an impression
taken from it, in order to exhibit the animal in a
more satisfactory manner.

ASAPHUS LIMULURUS.* Green. Cast No. 16.

Cauda longa, spina munita sicut in Limulo; costis
abdominis in spinis retrorsum flexis, desinentibus.

It is very much to be regretted that the abdomen
and caudal end only of this remarkable Asaph have
hitherto been discovered; it is, however, exceedingly
gratifying that the fragment still remains in so per-
fect a state. It forms a part of the magnificent cabi-
net of organic remains belonging to J. P. Wetherill,
Esq., now deposited in the Academy of Natural
Sciences, of Philadelphia.

Dr. J. J. Cohen discovered a small specimen of
this species at Lockport, New York, which he has
presented to the Athenaeum, in Baltimore.

Eight articulations of the abdomen, and ten of the
tail, are all of this fine species that we have seen.
The ribs, or costal arches of the abdomen have a
deep furrow on their upper surface, commencing at
the middle lobe, and terminating near their free ex-
tremities; these extremities appear all detatched from
each other, and end in reflected points or spines, so as

* From two Greek words, which signify " Limulus tailed."

49

to give the side of ^the animal a serrate appearance.
The costal arches of the tail are grooved through
their whole extent, and present no spinous termina-
tions. Beyond the membranaceous expansion of the
tail, which is somewhat similar to that of the Asa-
phus Caudatus, there projects a single spine, like
that from the tail of the Limulus polyphemus; this
spine may be traced under the caudal membrane to its
insertion into the middle lobe. A portion of the
crustaceous shell is still entire, and it seems to have
been covered with very minute granulations. A
row of large granulations may easily be traced on
each side of the middle lobe. Length of the frag-
ment, one inch and a half. Breadth one inch and a
fourth.

The A. Limulurus was found in the dark brown,
shaly limestone, at Lockport, in the State of New
York; it is associated in the same rock with the
terebratula. and several other fossils.

The singular spinous projection from the tail of
this Asaph, furnishes another analogy, between the
trilobite and the limulus; an affinity which was sug-
gested by Dr. Dekayj and which has been argued
with great ingenuity both by himself and Professor
Wahlenberg.*

'* See Nova Acta Regise Societatis Upsalensis: 1821. Also,
Annals of the Lyceum of Natural History. New York. Vol. i.
pages 179—185,

50

ASAPHUS CAUDATXJS.* Briinnich. Brongn, Cast
No, 17.

Clypeo antice subrotundato, postice valde emargi-
nato, angulo externo in mucronem productoj oculis
exsertis, conicis, truncatis, distincte reliculatisj post
abdomine in caudam membranaceam,acutam extenso.
(Vide Brongniart.)

The middle lobe of the buckler is marked by three
transverse plicae or folds on its posterior part, and
its cheeks or lateral portions are triangular^ the pos-
terior exterior angles of which, are acute, and con-
siderably elongated. The cheeks are furnished with
conical, truncated, semilunar and externally convex
tubercles, which were beyond all doubt the eyes of the
animal, being reticulated as in those of the Limulus.
The middle lobe of the back is narrow, and has twelve
articulations. The lateral lobes are composed of
double ribbed costal arches. Beyond the lateral lobes
and the caudal termination, there is a smooth, thick
membranaceous expansion, which forms an acute
projection below the central portion of the tail.

The specimen in the Philadelphia Museum, by
which I have identified this species, is marked as
coming from Ripley, Ohio. It reposes on a frag-
ment of ash coloured limestone — which contains also
a mutilated specimen of what seems to be a calymene,
and a few small terebratulse, Sec.

* From the Latin word for " tailed,"

51

Dr. John Bigsby, in his " List of Organic Re-
mains, occurring in the Canadas," states that the
A. caudatus is frequently met with, thrown up by the
water on the north shore of Lake Superior — on the
bank of Rainy river—at the Lake of the Woods, and
at several other places. In some localities they are
astonishingly numerous, and so small as to be almost
microscopic. They occupy indiscriminately lime-
stone of every colour, but are most numerous in that
which is brown or crystallized. They are composed
of the kind of limestone in which they happen to be
embedded.

We have seen a number of specimens of this species
in the Albany Institute, in Mr. Wetherill's cabinet,
and in the Baltimore Athenseum; but in all of them,
the abdomen and caudal extremity only remain per-
fect: from their exact resemblance, however, to the
same parts of the A. caudatus, figured by Brongniart,
(plate 2, fig. 4, D.) we have no hesitation with regard
to their identity. The description which we have
given of the buckler^ supposed to belong to our Asaph,
is therefore taken from Brongniart, whose specimens
were found at Dudley, the celebrated locality of the
C. Blumenbachii.* The coriaceous membrane, which
extends beyond the lateral lobes and forms the caudal

* In the first volume, 2d series, of the Transactions of the
Geological Society of London, Mr. Weaver has published some
highly interesting observations on the fossils found in Glouces-
tershire, England. The A. caudatus, he states, is there found
in the transition limestone, though very much mutilated. (Vide
p. 326.)

52

termination of our species, is not covered with ini-
nute dots, as in the European fossil; and if a new
name is to be applied to it on that account, it may be
called A. glabratus* M. Wahlenberg, has given
the figure of a trilobite which he calls caudatus, but
ours cannot be mistaken for that species, to which
Brongniart has very judiciously applied the name of
A. meucronatus.

The conical eye-like protuberances on the head of
this species, are very remarkable, and so much re-
semble the reticulated eyes of the limulus, as to
leave no doubt that they once contained the organs
of vision.

ASAPHUS HAUSMANNI. Brongniart.

Cauda rotundata; cute coriacea tuberculis mini-
mis spinulosis tectu.

In De la Beche's Geological Manual, there is a
list, of the trilobites which have been discovered in
the grawacke group of rocks. This list we have
given in our introduction. Among the trilobites he
states that the Asaphus Hausmanni has been found
in the United States; as we have not seen the species,
and presuming the author to be correct in his locali-
ty, we give the following description from Professor
Brongniart.

* In the cabinet of G. W. Featherstonhaugh, Esq., I have ex-
amined a fine specimen of the A. caudatus, from Dudley, Eng-
land, but could not perceive the minute dots on the tail, as men-
tiojned by Brongniart.

53

I know, he observes, only the tail of this Asaph,
but it is so different from that of other trilobites, that
I do not hesitate to establish a particular species,
upon the consideration of this part alone. Its gene-
ral form is that of a semi-ellipsis; the middle lobe re-
presents a very slender cone. The arched ribs of the
lateral lobes are perfectly distinct and simple. I can-
not perceive in them the slightest appearance of bi-
furcation. This sufficiently characterizes the species.
But that which further distinguishes it from the
others, are the small, elevated points, scattered, and
of course rough (serres), with which the skin or epi-
dermis is covered, resembling, in this respect, the
tail of the Jipus canceriformis.

This fragment of an Asaph is in a homogeneous,
compact, blackish limestone, which contains no
other kind of petrifaction. I know not where it was
found. It is in the cabinet of M. de Dree.

On plate 2 of Professor Brongniart's work, he has
given figures to illustrate this species; fig. 3 A. re-
presents the whole fragment, and 3 B. two of the ribs
of the lateral lobes, magnified to show the arrange-
ment of the tubercles, which are very peculiar.

From the above description it will be readily per-
ceived, that the A. Hausmanni comes very near to
the A. Laticostatus. There are, however, many
striking differences, which will be obvious to those
who compare our cast with the figures of Brong-
niart. The shape of the ribs, and the tubercles upon
them; the form of the middle lobe and of the inter-
stices between the articulations, are all peculiar to
E 2

54

each. The elongation of the tail in our species is
alone sufficient to distinguish it. We have always-
been doubtful whether the minute granulations on
our species were not produced by the sandstone in
which it is petrified.

Upon what authority the A. Hausmanni has been
considered as a species belonging to the United
States we cannot determine. In the valuable and ex-
tensive cabinet of trilobites belonging to the Albany
Institute., there are a number of specimens labelled
with this name by Professor A. Eaton. If we mis-
take not, he mentioned to us that similar fragments
of this fossil were sent by him to Brongniart, who,
we understand, is the author of the list of trilobites
found in the manual of De la Beche. The specimens
which have been examined, both in the cabinet of
Professor Eaton, and in that of the Albany Institute.,
are certainly not identical with the figures or de-
scriptions published of the A. Hausmanni. Profes-
sor Eaton, in his Geological Text Book, at page 3K
thus describes his A. Hausmanni: — " Tail rounded,
and forming the middle of a circular arc whose cen-
tre is in the fore abdomen, near the head; covering
tubercled or spined. Found in coral rag on the
south shore of Lake Erie. Also, in its underlaying
grit slate on the Helderberg." Some other trilobites
mentioned in De la Beche's list as occurring in the
United States, we have not been so fortunate as to
meet.

55

ASAPHUS PLEUROPTYX.* Cast No. IS.

Corpore depresso; cute coriacea tuberculis mini-
mis; costis striatis; cauda acuta, brevi.

This species like most other specimens of this
genus, in our cabinets, is decapitated — every other
part, however, appears to be in a good state of pre-
servation.

The articulations of the abdomen and tail, which
cannot readily be distinguished from each other, are
seventeen in number. The middle lobe is flat, and
regularly tapers to an obtuse lip; it is marked on
each side with longitudinal impressed lines or little
grooves. The costal arches on their upper side have
a deep and narrow channel, running through their
whole course. The costal arches of the abdomen
have no membranaceous expansion beyond their ter-
minations; this organization is only visible immedi-
ately below the end of the middle lobe, where it quick-
ly finishes in an acute point. A large portion of the
crustaceous shell remains, and is covered with dis-
tinct granulations; those on the tail are the least
obvious.

This species approaches very near the A.caudatus,
but the grooves on the middle lobe, the smallness of
the costal arches, and the limited extent of the mem-
branaceous expansion round the lower portions of
the shell, will sufficiently distinguish it.

* From the Greek word for " grooved ribs."

56

Two specimens of this Asaph are in the cabinet of
the Albany Institute, The one from which our cast
is taken, was found on the Helclerberg mountains; it
is embedded in a light grey coloured limestone shale*
The other specimen, which is much smaller, was dis-
covered near the Genessee river, in the State of New
York. The rock in which it occurs is identical in
its constitution with the other. It contains other
species of trilobites, and a number of shells.

ASAPHUS MICRURUS.* Cast No. 19. Fig. 3.

Cauda attenuata, acuta; corpore valde convexoj
costis striatisj parte marginal! vix membranacea.

This fine, large caudal termination of an Asaph is
in the cabinet of the Albany Institute — and it is a
subject of great regret, that all that has yet been dis-
covered relating to this highly interesting trilobite,
is to be seen in this fragment.

There are eighteen articulations of the tail and
abdomen, which cannot be distinguished from each
other. The middle lobe is composed of a series of
straight, distinct, parallel articulations, very convex
about the middle, so as to form a kind of longitudinal
ridge down the back. The costal arches of the
lateral lobes are very distinct, and are longitudinally
striated or grooved on their upper surface, particular-
ly those near the upper part of the animal. The
membranaceous expansion is very narrow along the

* From the Greek, for " minute tail."

57

sides of the body, and forms a sort of hem; below
the central portion of the tail it makes a short acute
projection, which seems to be supported by a short
costal elongation of the middle lobe. Length two
inches and a half.

The A. Micrurus was found in the black foetid
limestone of Trenton Falls, by M. H. Webster, Esq.,
and by him placed in the rich collection of trilobites
in the Albany Institute. The limestone in which
this Asaph is embedded, is almost one entire mass of
petrifactions. The general aspect of the A. Micru-
rus is very similar to that of a calymene — but judg-
ing from its structure, it could never contract its
shell into a spherical figure. Its minute tail, and
narrow membranaceous expansion round the terminal
edges of the lateral lobes are quite peculiar, and de-
termine it to be an Asaph.

ASAPHUS WETHERILLI.* Green. Cast No. 20.

Clypeo postice arcuato, sulcato; abdominis articu-
lis duodecim; cauda vix membranacea; cute corea-
cea vix punctata.

The contour of this beautiful Asaph is very regu-
larly ovate; unlike most of the remains of this genus,
the buckler is still attached to the abdomen, though

* I have named this species in compliment to my friend, John
P. Wetherill, Esq., whose magnificent cabinet of fossils in the
Academy of Natural Sciences of Philadelphia, will ever remain
as a monument of his discrimination, enterprise, and liberality.

58

one of the cheeks, and a portion of the front are ob-
scured by the rock in which the animal is imbedded.
The cheeks form spherical triangles. The oculife-
rous tubercles, though a good deal defaced, seem to
have been circular and not lunate, as in the A. Cau-
datus. A raised, curved line passes from and over the
eye, between it and the lateral lobe of the abdomen.
The central lobe of the back is composed of twelve
double joints, and that of the tail of six single articula-
tions; where the epidermis or shell is perfect, all the
articulations appear single. The last joint of the tail
is longer than in any other of our species. The ribs
of the abdomen are rather broad, and have a deep
furrow scooped out along their upper surface; their
extremities, where they can be discovered, are de-
tached from each other, and terminate in reflected
points, like those of the A. Limulurus. The costal
arches of the tail are delicately grooved, and termi-
nate in the membrane. The membranaceous expan-
sion round the edge of the tail is very narrow, and
appears to form no projection beyond its central
part. The whole epidermis is finely marked with
granulations. Length one inch and three-fourths—
breadth one inch and one-fourth.

This interesting species was found in limestone
shale, near Rochester, in Munroe County, N. Y.j and
is now in the valuable cabinet of the Albany Institute.
An accidental fissure of the rock disclosed not only a
fine specimen of both the mould and the cast of this
animal, but also another individual of the same spe-
cies in contact with it. From the peculiar attitude

59

which these fossilized animals maintain towards each
other, they appear to have been combatants at the
very moment when the catastrophe occurred which
produced their mineralization* In the Museum of
the Garden of Plants at Paris, there is a large speci-
men of two fossil fish, which are supposed by many
to have been destroyed and covered with mineral
matter, when one of them was in the very act of
swallowing the other. Mr. Bake well, however, who
accurately examined this specimen, is of opinion,
that the two heads of the fish had been pressed to-
gether by the superincumbent weight.

GENUS PARADOXIDES. Brongniart.

The animals arranged under this generic name, in-
clude the organic remains described by Linne as En-
tomolithus paradoxus, and Brongniart has given the
specific appellation which the great Swedish natural-
istappliedto thesesingular animals, out of compliment
to him, though he considers it quite inappropriate.
The late Professor Dalman calls this genus Olenus,
and quotes Paradoxides as a synonyme, but the term
of Brongniart seems to have the priority, and there-
fore must be preferred.

The animals belonging to the Paradoxides have the
body very much depressed, and the lateral much
wider than the middle lobe.

The buckler is nearly semicircular, the cheeks are
destitute of eyes, and the front is marked with three

60

transverse furrows. This last character is probably
not a permanent one.

But the most distinguishing character, is the pro-
longation of the costal arches, particularly those of
the tail, beyond the membrane which they are sup-
posed to support; the termination of these arches is
in teeth or spines. Some species of the Asaph have
prolongated extremities to the ribs of the abdomen,
but we have never seen them on the arches of the tail*

This genus is said to comprise a great number of
species, but the only one found in North America, as
far as our knowledge extends, is that described by
J. J. Bigsby, in the fourth volume of the Journal of
the Academy of Natural Sciences of Philadelphia.
As we have not seen the specimen, we add the de-
scription of it in the author's own words.

PARADOXIDES BOLTONI. Bigsby. Figure 5.

Oval, blind; surface with small tubercles and
striae; clypeus rounded before; exterior angle ex-
tending in a broad spine; abdomen fourteen jointed;
segments recurved, falcate; tail membranaceous and
serrate.

The shape of this individual is oval, approaching
ovate; it is moderately flat; the whole length is five
inches and four-fifths; its breadth across the middle
is four inches and nine-tenths; wherever the cutis is
not removed, it is covered profusely and irregularly
with small tubercles. The denuded portions in this
specimen, for the space of three quarters of an inch

61

from the external margin, is, in a very small degree,
depressed, and displays a number of broken and con-
tinuous strise, parallel to that margin. There are no
traces of organs of vision. The buckler is nearly the
segment of a circle; anterior edge, in the present
case, imperfect; it is four inches and three-fifths
broad, and one inch and one-ninth long at the centre;
it joins the abdomen by a somewhat sinuous trans-
verse line; cheeks and front of equal breadth; the
former are flat, but rise at the sharp ridge by which
they unite with the front; they are triangular in
shape; their outer angles terminating by an acute
tip. The striae mentioned above are here not quite
parallel to the external border; the front is a shallow
depression; rounded but tapering anteriorly; it is in-
tersected from above on each side obliquely towards
the mesial line, by a ridge bifurcating downwards;
another smaller ridge nearly bisects the front perpen-
dicularly.

The abdomen and post abdomen are not distinct.
The abdomen exclusive of the cauda is three inches
and a half long; it exhibits fourteen costae varying
indiscriminately from one-fifth to one-fourth" of an
inch in breadth, except the three inferior ones, which
are rather broader; they occupy the -whole abdomen
without nnembranaceous interspaces, and are sepa-
rated by a black sulcus, not always well defined, and
sometimes a line in diameter. Each costa is canali-
culated from the upper and under angle to the tip.

The middle lobe is separated from the lateral by a
shallow, rude sulcus, which however, does not al-

62

ways destroy the continuity of the costse, as they cross
it; this lobe is slightly convex, one inch and a half
broad at the top, and so continues to the sixth costa,
after which it gradually contracts, until at the bot-
tom it is one-fifth of an inch broad, subsiding insensi-
bly into a flat membrane-like surface; its longitudi-
nal sulci pass one inch farther downwards, and ex-
panding a little, unite with the costas on each side the
posterior edge of the space included by them, being
dentated.

The lateral lobes are quite flat, one inch and a half
broad anteriorly, and, by gradual prolongation, be-
come at the fourth costa one inch and four-fifths in
breadth; this dimension is maintained to the ninth
articulation, when it slowly decreases to one inch at
the bottom; the recurvature of the costae is gentle in
the upper eight, but then decreases rapidly. Their
extremities, advancing two-fifths and four-fifths of an
inch into the embedding rock, are falcate with their
raised black edges, and clearly marked points.

This trilobite was found' by Lieut. Bolton, at Lock-
port, in the state of New York, in the black, shaly,
horizontal limestone forming the lower part of the
ravine by which the Erie canal ascends the parallel
ridge of Lake Ontario. Dr. Bigsby remarks on this
locality, " I am not prepared to assign to this lime-
stone its exact place in the series of geological for-
mations; it is above the saliferous sandstone, and
therefore more recent than the rocks best known as
abounding in trilobites." We have, therefore, in this
instance, another fact, which demonstrates that blind

63

trilobites are not Confined , to a geological period
more remote than That which has produced the ani-
mals with oculiferous tubercles.

GENUS OGYGIA. Brongniart.

In the vast quarries of slate at Angers, in France,
there is frequently noticed two very remarkable or-
ganic remains, which have for a loic^ time excited the
attention of naturalists. To receive these curious
relics, Professor Brongniart established the genus,
Ogygia, which he thus characterizes. Body much
depressed — elongated into an ellipse, terminated in
points — nearly equal at its extremities, and not capa-
ble of contracting itself into a spherical form. The
buckler is bordered by a slight longitudinal furrow,
rising from its anterior extremity, and its posterior
angles terminating in elongated points. The abdo-
men has eight articulations, and its longitudinal lobes
are not very prominent. The eyes are neither promi-
nent nor reticulated and there are no other protube-
rances on the buckler.

In Professor Brongniart's original work on theTri-
lobites, he has described the two specimens from
Angers, under the specific names of Guettardi, and
Desmarestii, in compliment to M. M. Guettard and
Desmarest; and in De La Beche's Manual of Geolo-
gy, we are informed that he has since identified two
other species; one of which is supposed to be found
in North America; this he calls Ogygia Sillimani;
the banks of the Mohawk River, near Schenectady,

64

is the locality from which it is said to have been de-
rived. *

As we have not been able to find any detailed ac-
count of this species, we have admitted both it and
the genus to which it is said to belong into our Mo-
nograph exclusively on the high authority of Profes-
sor Brongniart, as quoted in the Manual of Geology.
We are not ignorant of the species of Trilobites found
near Schenectady, and if permitted to offer a sugges-
tion on this subject, it would be, that the description
of the American ogygia, was made out by its distin-
guished author from the fragment of an Isotelus.
The Isotelus is not uncommon in that vicinity, and
one of its extremities might, even by a very close
observer, be mistaken for that of an Ogygia — espe-
cially by those who are not perfectly familiar with
the Isotelus.

GENUS ISOTELUS. Dekay.

This fine genus of trilobites was established No-
vember, 1824, by my friend James E. Dekay, M. D.
It embraces a considerable number of species so
analogous to each other, that except in a very few
cases, it is exceedingly difficult to point out their dis-
tinctive characters. Some of the species of Isotelus,
appear to have reached a greater size than any other
trilobite. In the cabinet of P. A. Browne, Esq., there
is the fragment of one, which must have been four-
teen or fifteen inches long.

The Isotelus is found in several parts of North

65

America, but most abundantly in the black transition
limestone, in the northern section of the country.
The richest locality, not only of this genus, but also
of the Calymene and the Asaph, is Trenton Falls,
on West Canada Creek, about 1 3 miles to the north
of Utica, in the state of New York. The following
extracts from the notes of Professor Renwick, which
accompany Dr. Dekay's account of the Isotelus, will
give some idea of this vast depository of the medals
of ancient zoology. West Canada Creek, is one of
the principal branches of the Mohawk River. At
Trenton Falls it has worn itself a passage through
the rock for the distance of nearly two miles, forming
a series of water falls; and has thus laid open to view
the strata to the depth of probably 300 feet. The
layers of the rock thus disclosed are nearly hori-
zontal, and of various thicknesses: they are composed
of limestone, with the exception of numerous thin
veins of argillaceous matter. The higher strata are
composed of carbonate of lime nearly pure, of a light
grey colour and crystalline structure. At greater
depths it is more compact and darker in colour, and
finally it appears quite black and highly foetid.*

Animal remains are contained in every part of the
rock; besides several genera of trilpbites, we have
several species of orthocera. Encrinites and Fun-
gites — Nautili — Terebratulse and Producti, are quite
common. The favosites here are sometimes six
inches in diameter, and in such numerous columns,

* See Annab of N. Y. Lyceum, vol. i. page 185.
F 2

66

as to have induced the late worthy proprietor of this
interesting spot, Mr. J. Sherman, to consider them
as analogous in structure to the basaltic columns of
Staffa and the Giant's Causeway; he therefore main-
tains the extravagant theory that these columns are
nothing more than gigantic favosites.* We visited
this famous locality of trilobites not long since, and
were almost as much delighted with the sublimity
and grandeur of the cataract, and the picturesque
and romantic character of the glen, as with the re-
liques of olden times, which are scattered here in
such profusion.

The genus Isotelus, derived from /V<j$, equal, and
TgAo$, extremity, is thus characterized by Dr. Dekay.

Body oval — often contracted, not unfrequently ex-
tended.

Head or buckler large and rounded, equalling the
tail in size, but with two oculiform tubercles.

Jlbdomen with eight articulations.

Frontal process beneath, with two semilunar termi-
nations.

Post abdomen or tail, broad, expanded with indis-
tinct divisions, as large as the buckler.

Longitudinal lobes very distinct.

Other distinguishing marks by which this genus
may be known, have been given in our introduction.

* See a Description of Trenton Falls, by John Sherman, p. 17.

67

ISOTELUS GIGAS. Defray. Casts Nos. 21 and 22.

Head representing a spherical triangle, surface
punctate, convex, descending from between the eyes
to the anterior border, which has a narrow raised
rim; posterior extremity concave and corresponding
to the articulation of the abdomen. Eyes elevated,
prominent, sub-pedunculated; cornea oblong, lunated,
highly polished $ abdomen with eight distinct arti-
culations, the middle lobe double the size of the late-
ral one : these latter are continuous with the middle
lobe, have a deep furrow impressed on their upper
surfaces, which becomes gradually effaced towards
their narrow free extremities. These lateral lobes
are rounded at their extremities, and flattened in such
a manner as to allow each lobe to slide easily under
the lobe immediately preceding. Tail subtriangular,
convex, equalling the head in size, with the posterior
termination rounded. On the centre of its surface,
when accidentally decorticated, a slight elevation
may be traced, if the specimen be held in a certain
light, which appears to be a continuation of the mid-
dle lobe; this extends to within a short distance of
the posterior angle of the tail, when it is either en-
tirely effaced or terminates in an abrupt truncation.
Another elevation runs parallel to and at a short dis-
tance from the edge of the tail. These elevations
are connected by obscure parallel lines, imitating
the spaces between the lateral lobes. When the tail is
fractured on the borders, a semilunar depression is

68

visible, exhibiting concentric stria*. The 'whole Sur-
face of the animal has a jet black polish. Length
from 6 to 12 inches.

The original of our cast is in the cabinet of J. P.
Wetherill, and was found near Cincinnati, Ohio. It is
of a yellowish colour, and occurs in argillaceous slate.
Specimens are common in most cabinets of Ameri-
can fossils. The Lyceum in New York, possesses a
fragment of an individual of this species, which must
have been at least 17 inches long. Our cast, No. 22,
is from the gigantic tail in the cabinet of P. A. Brown,
Esq. Mr. Stokes describes the I. gigas as a new
species under the name of Asaphus Platycephalus, in
Geolog. Trans, vol. i. N. Scries. His specimen was
found in the limestone of. St. Joseph's, Canada.

ISOTELUS PLANUS.* Dekay. Cast No. 23.

Head more rounded than the preceding, and less
elevated. Tail flat, rounded. Total length two inch-
es and one-tenth. Breadth one inch and one-tenth.
Length of the head, six-tenths — of the abdomen,
eight-tenths, and of the tail seven-tenths.

Dr. Dekay is of opinion that this species may pos-
sibly prove to be the young of the preceding. The
relative proportions of its buckler and tail vary

* The general usage of naturalists is to prefix a short Latin
caption to the species which they discover — but as some authors
do not follow this fashion, we are satisfied to suffer their descrip-
tions to stand without it. We believe, indeed, that the time is
not very distant, when every author will be expected to publish
his discoveries in his vernacular tongue.

69

considerably from those of the I. gigas; and the
depth of the lateral lobes, which exceeds three-tenths
of an inch, would almost of itself determine it to be
a new species. The original, from which our cast
was taken, is in the cabinet of J. P. Wetherill. It
was found near Newport, Kentucky, and occurs in
argillaceous slate. The fossil is of a dirty yellow
colour.

ISOTELUS CYCLOPS.* Green. Cast No. 24. Fig. 7.

Clypeo antice attenuate, piano; oculis rotundis,
proximis; cauda ovata, acuminata.

The head of this species is much more elongated
than it is in the two preceding species. The anterior
portion of the buckler is much prolonged. The eyes
are approximate, rounded, and near the posterior
edge of the head. The abdomen is furnished with
eight distinct articulations; the middle lobe is scarce-
ly broader than the lateral lobes; tail rather broader
than the head, and ovate; posterior termination more
rounded than the buckler. Length nearly three inches.

The specimen from which our model was taken
belongs to the Albany Museum. No label is attach-
ed to it, but I was informed by Mr. Meach, one of
the proprietors, that it was found in the western part
of the State of New York. It is embedded in an ash-
coloured limestone. The specimen is a good deal
worn — but the peculiar form of the eyes, and the nar-

* From the Greek for " round eyes,"

70

rowness of the middle abdominal lobe, clearly distin-
guish it from either of Dr. Dekay's species.

ISOTELUS MEGALOPS.* Green. Cast No. 25.

Clypeo antice subrotundato, postice arcuato; oculis
magnis, rotundis, eminentissimis; caucla suborbicu-
lari, limbo latoj articulis abdominis octo.

The buckler in its contour resembles very much
the head of the I. gigasj it is, however, rather more
rounded before, and arcuated behind. The oculi-
ferous tubercles, are very peculiar, being very large,
round, and exceedingly prominent. They have a
good deal the appearance of solid hemispheres
placed on the forehead of the animal. They are ex-
actly on a line with the two abdominal furrows. The
abdomen is composed of eight distinct articulations;
the middle lobe is rather larger than the lateral
lobes. The tail is suborbicular, convex, and rather
less than the head. Length nearly five inches.
Breadth almost three inches.

This magnificent Isotelus was obtained near Tren-
ton falls, in New York, by P. A. Browne, Esq., and
now forms a part of his fine collection of fossils, in
this city. It occurs in black transition limestone.
It differs essentially from the I. gigas of Dekay, in
the magnitude, collocation, and contour of the eyes.
Those of the I. gigas are oblong and lunate, and
nearly half the distance between the anterior and the

* From the Greek for " great eyes."

71

posterior edges of the buckler; those of the I. Me-
galops are not only much larger, but they are round,
and very near the posterior border of the head.

ISOTELUS STEGOPS.* Green. Casts Nos. 26 and 27.

Clypeo antice, caudaque postice attenuatis; cute
coreacea punctis minimis.

The head of this species is nearly in the form of a
spherical triangle; its anterior edge is vertically flat-
tened all round, but does not produce a narrow raised
rim, such as is described by Dr. Dekay, to belong to
the I. gigas. The eyes are prominent, and rather
nearer the lateral edge of the buckler, than to its pos-
terior border. The shell of the buckler forms a re-
markable projection over the top of each oculiferous
tubercle, something like an eye-lid. Continuous
with the edge of this cuticular projection, there is a
curved linear depression, which terminates on both
sides, at the edge of the buckler. This kind of
suture, though remarkably developed in this species,
is not peculiar to it, being more or less distinct in
most of the Isoteli. The articulations of the abdo-
men are lost; there can be little doubt, however, that
they were eight in number. The tail is subtriangu-
lar, and less in magnitude than the buckler.

This fossil is among the number of fine specimens
in the cabinet of J. P. Wetherill. It is in a rolled or

* From two Greek words, which signify " covered eyes."

72

contracted attitude, and is somewhat distorted. We
have given, however, models of the head and the tail,
in two distinct pieces. The external shell, or calca-
reous covering, is more perfect in this specimen
than in any other we have ever seen. A considera-
ble portion of the under side of the anterior part of
the buckler, is also well preserved, and perfectly co-
incides with the figure and description given of it by
Dr. Dekay and Mr. Stokes. There is another frag-
ment of an Isotelus in the cabinet of Mr. Wetherill,
showing eight articulations of the abdomen, which
probably belongs to another individual of this spe-
cies. The dorsal shell is in a high state of preser-
vation. This species is embedded in clay slate, and
was found in Newport, Kentucky.

GENUS CRYPTOLITHUS. Green.

Among the numerous organic relics embedded
in black limestone at Trenton Falls, in the State of
New York, there is often found the fragment of a tri-
lobite which cannot properly be referred to any of
the genera already mentioned. Dr. J. Bigsby, in his
Sketch of the Geology of the Island of Montreal, has
figured and described a fossil which occurs at that
place, which approaches in its specific characters to
the fragments found at Trenton — but he does not
suggest for his relic any name. Professor Brong-
niart has also represented, plate 4, figs. 5 and 7 A.
B. C., the fragments of trilobites from Russia and
from Llandillo, in Wales, which seem to differ but

73

little from those above noticed, these are also with-
out names. Under such circumstances, we have
thought it expedient to group these relics under
the generic term of Cryptolithus, a name analogous
to Calymene, Asaphus, Ogygia, and Agnostus, and
which may with propriety be applied to the animal,
should it ever be discovered entire.*

Body, contractile.

Buckler, lunate, convex, outer edge surrounded by
a semicircular, reticulated, or tessellated border.

Front or middle lobe of the buckler very protube-
rant.

Oculiferous protuberances, none.

Abdomen, much compressed, trilobate.

CRYPTOLITHUS TESSELLATUS. Green. Cast No. 28,
and Fig. 4.

Clypeo rotundato, fronte valde convexo, capite an-
tice semicircular! margine tessellato ornato.

Outline of the buckler hemispherical, the edge sur-
rounded by a semicircular border of tessellated or
rounded punctures, in three concentric rows in front
— on each side near the posterior angle of the buck-
ler, these rows of punctures are more numerous^
the front is highly convex; is rounded before, and

* Since the above was written, and the C. Tessellatus pub-
lished, I have received a fine specimen of this trilobite from Pro-
fessor Eaton, in an almost perfect state, so that the entire ani-
mal can now be described.

G

74

gradually tapers towards the abdomen. The cheeks
form spherical triangles, and are entirely destitute of
oculiferous tubercles or any other markings; their
posterior angles project beyond the sides of the ab-
domen. Abdomen and tail very much compressed,
and composed of about ten articulations; costal arches
of the lateral lobes grooved^ tail attenuated. Whole
length half an inch.

The Cryptolithus Tessellatus, resembles a good
deal the Entomostracites Granulatus of Wahlenberg,
and which Dr. D aim an calls Asaphus Granulatus.
The figure of this animal given by Brongniart, table
3, fig. 7, appears to be quite imperfect, and is very un-
like, except in the buckler, the representation of
Wahlenberg's fossil, given by Dalman, table 2, fig.
6. Though the angles of the buckler in the Asaphus
Granulatus are much more elongated than those of
the C. Tessellatus, it may perhaps be another species
of the same genus.*

* The following, is Dr. Dalman's description of the Asaphus
Granulatus : —

A. trunco sexarticulato pygidioque laevibus, capite antice se-
micirculari margine granuloso, angulis posticis extensis corpore
longioribus.

Animalculum singulare, inversum si inspicitur, lyram forma
fere similans. Caput antice semicirculare, margine distincto,
serie submoniliformi e granulis approximatis ornato, discus capitis
laevis, sed ambitus intra marginem punctis elevatis obsitus. Hie
ambitus, una cum margine, truncum quoque amplecti videtur, ad
pygidii basin usque, ubi in cornua Icevia, trunco multo longiora,
abit. Glabella antice fere clavaRformis, ad basin utrinque emit-
tens lobi rudimentum. Truncus brevis Icevis segmentis constaris

75

The animal described and figured by Dr. J. Bigsby,
to which we have already referred, seems rather
different from our species. His specimens were
found at Montmorenci, near Quebec, (Canada) more
than an inch and a half in diameter. The following
are his remarks on this trilobite.* " The front of
the buckler is remarkably convex, and has on each
side near the base, three very small transverse lines,
scarcely to be called depressions, corresponding to
the sulci so strongly marked in the genus Calymene.
There is frequently, but not universally, a very minute
pisiform process on the centre of the front. The
whole upper edge of the buckler is always surround-
ed by a very ornamental semicircular border, some-
times semi-elliptical, of punctures placed in the
meshes of a net-work in high relief and arranged
close together, in rays, passing perpendicularly from
the buckler and forming at the same time when ob-
served transversely, curved lines parallel to its upper
rim or edge, excepting at the sides, where they di-
verge, leaving a space occupied by other lines of dot-
tings, parallel to the former, but speedily terminat-
ing on the cheeks of the buckler. The lines which

tantummodo sex, rhachide angusta. Pygidium breve, rotun-
datum, Iffive ; adeo parvum ut ne quidem capitis disco respondeat.

Obs. — Oculos atque suturam facialem ex autopsia describere
licet.

Vide Om. Palseaderna eller de sa kallade Trilobiterna af.
J. W. Dalman, pages 50 — 4.

* See Geology of the Island of Montreal, in Lyceum of Nat.
History, N. Y. p. 214.

76

are complete from side so side, are four in number.
The imperfect additional ones, vary from two to
four; the smallest and inner, consisting only of two
or three punctures. A plain edging includes the se-
micircle of punctures. In the beds of these casts,
the places of the punctures are shown by small coni-
cal elevations, and those of the ridges of the net-work,
by corresponding depressions."

Should this prove to be a distinct species, we pro-
pose to call it Cryptolithus Bigsbii.

The Nuttainia Concentrica of Professor Eaton seems
also very nearly allied to this species; he describes
it as having " four or five concentric arcs of punc-
tures in front of the buckler, separated by alternating
arc1fc>f fine elevated ridges." The genus Nuttainia,
to •vpiich he refers this species, cannot include it,
and the N. Sparsa; for these two relics have scarce-
ly a single essential character in common; we have,
therefore, confined the genus Nuttainia, to the spe-
cies which he calls Sparsa.

The Cryptolithus Tessellatus is very common at
Trenton falls. In the transition limestone at Glenn's
falls, in the state of New York, during a very short
visit to this place, Dr. R. Harlan procured a large
number of this fossil, but only the buckler, the
projecting front of which exhibited a pisiform pro-
tuberance above the level of the strata. Mr.
Eaton says that the N. Concentrica " occurs in the
wacke variety of transition of argillite, on the Cham-
plain canal," between the town of Waterford and the

77

Mohawk river. The specimen in my cabinet, from
which our cast was made, is from that place.

The Cryptolithus Tessellatus occurs also in the
limestone which, according to Dr. Bigsby, overlays
the sandstone in the island of Montreal. At most of
its localities, it is associated with the Isotelus, the
Calymene, and with several species of Asaphus. The
Cryptolithus, which is entirely destitute of eyes, being
thus found with the oculiferous species, is an inte-
resting fact, and controverts the opinion of Professor
Wahlenberg, that the trilobites, which are without
eyes belong to a geological epoch more ancient than
those which are furnished with oculiform tubercles.
That organic remains furnish us with the most satis-
factory evidence of the identity or dissimilarity of
certain formations, is a disputed point with some
geologists* It cannot reasonably be doubted, that
new and isolated facts have been made the basis of a
too hasty generalization. On this subject Count
Rasoumowsky makes the following remarks: — " Les
divers gisemens des Trilobites ne me semblent pas
non plus pouvoir etre determines avec quelque pre-
cision. M. Brongniart parait admettre que les trilo-
bites aveugles ne se trouvent que dans de tres an-
ciennes formations dans des schistes et des calcaires
de transitions; mais nous avons clonne la descrip-
tion d'un trilobite [without eyes] des bords de la
Yaousa pres de Moscow, qui n'appartient certaine-
ment pas aux . formations de transition, ce qui me

* See Eclectic Review, for July, 1832.
G 2

78

donne lieu de croire que cle nouvelles recherches et
cle nouvelles observations, prouveront qu'il n'est pas
strictement vrai qu'en France, en Angleterre, en
Russie, il n'existe point de trilobites entierement prives
d'yeux, comme le dit le savant auteur que je viens
de citer." See Annales des Sciences Naturelles,
Vol. 8. page 195*

GENUS DIPLEURA. Green.

Body, contractile, not much depressed, and slightly
tapering.

Buckler, pustulous, trilobate, cheeks protuberant,
with oblique, annular, oculiferous tubercles.

Abdomen, with fourteen arliculations, not lobate,
the ribs double.

Tail) suborbicular, not so large as the buckler, co-
vered with an epidermis.

This genus derives its name from two Greek words,
which signify double ribsj many of the trilobites are
thus characterized; but in no species, is this organi-
zation so remarkable as in those which belong to the
Genus Dipleura. The expansion of the tail resem-
bles, in some degree, that of the Isotelus, but other
obvious characters sufficiently distinguish it from
that interesting genus. The fossils arranged under
this section are larger than most other trilobites.

79

DIPLEURA DEKAYI. Green. Casts No. 30, 31, and
Figs. 8 & 9.

Clypeo lunato punctate; abdomine quatuordecim
articulis duplicibus vix lobatis; cauda suborbiculari;
limbo lato convexo integerrimo; oculis oblique de-
flexis.

The buckler is subtriangular, and covered with
granulations; the anterior portion of our specimen
being mutilated, we cannot determine its form exactly.
The cheeks are very prominent, and swell up gradually
towards the oculiferous protuberances, which are ob-
lique, and marked at their apex with a depression,
so as to give them an annular appearance. The abdo-
men is crossed by fourteen double distinct articula-
tions, not interrupted in their course, by the two
longitudinal furrows, so common in most of the tri-
lobites; but owing to certain curves or irregularities
in the ribs near their lateral termination, a trilobate
appearance may in some specimens be detected.
Tail suborbicular, convex, and covered with a thick
epidermis.

The specific name of this species was given in com-
pliment to Dr. James E. Qekay, of New York, whose
valuable paper on the genus Isotelus, first directed
my attention to the American trilobites.

The D. Dekayi has been found in several districts
of the United States; at Lockport in the State of
New York, it is not uncommon. The small speci-
men from which our cast of the abdomen and caudal

80

end was taken, is in the fine cabinet of Mr. William
Hyde, who permitted me to use it with his wonted
liberality and kindness. It is said to have been found
in Northumberland, Pennsylvania, and occurs in grey
carbonate of lime. In the Philadelphia Museum,
there is a fine fragment of this species, in which there
is embedded some crystals of iron pyrites; it was ob-
tained in Ulster County, New York. In the cabinet
of the Academy of Natural Sciences, there is a longi-
tudinal and hollow fragment, filled with ochre, and
the oxide of iron; it is labelled from Lockport, New
York. At Mount Hope Institution, near Baltimore,
there is also a good specimen from the same locality.
In the Clinton collection, owned by the Albany Insti-
tute, there is a large extended fragment, nearly five
inches long. It is embedded in brown limestone,
and was found in Madison County, N. Y. There are
twelve articulations of the abdomen remaining, and
the epidermal covering of the tail is distinctly marked
with numerous dots. In the same collection there is
another large fragment of this species, consisting of
the tail and fourteen articulations, It was found in
Steuben County, New York; and occurs in grey
limestone. It is slightly contracted and very much
depressed laterally. There js also a head in the same
kind of limestone, from Cazenovia, Madison County,
New York. In the cabinet of the Institute there is
another specimen of this species, about six inches
in length, and nearly perfect; it is also embedded in a
similar rock, and was brought from Rochester, Mun-
roe County, New York.

81

The original of the head from which our cast was
made, is in the cabinet of P. A. Browne, Esq., and
was found by that enterprising geologist near Le-
highton, Pa.

GENIJS TRIMERUS.* Green.

Body, contractile, tapering, compressed.

Buckler, pustulous, indistinctly lobate, with only
two small elevated oculiferous tubercles.

•Abdomen, with thirteen distinct, double articula-
tions— divided into three lobes by a slight longitudi-
nal furrow.

Flanks, or lateral lobes, not so broad as the middle
lobe.

Tail, tapering to an obtuse point, pustulous, and
marked with ten articulations.

This genu$ resembles in some respects both the
Calymene and Dipleura. The form of the buckler,
the position a'nd structure of the oculiferous tuber-
cles, and the scarcely lobate divisions of the ab-
domen, will readily distinguish it from the Caly-
menes. The articulations of the tail, not being
covered with a shelly crust, is a character too ob-
vious to confound it with the genus Dipleura. There
is, we think, a beautiful chain of gradations of resem-
blances, between the Isotelus, Dipleura, Hemicryp-
turus and Trimerus. The lobes of the abdomen of
the Isotelus are very distinct, and the articulations
of the tail are hid by a broad thick shelly crust. The

From the Greek for " three divisions."

82

lobes in the Dipleura are scarcely apparent, the
ribs more numerous; and the covering of the tail
much smaller. The lobes of the Hemicrypturus are
like those of the Isotelus; but the lateral ones only
of the tail are covered. In the genus Trimerus the
lobes are like those of Dipleura, but the articulations
of the tail are exposed.

TRIMERUS DELPHINOCEPHALUS. Green. Cast No. 32,
and Fig. 1.

Clypeo semilunari, antice compresso; oculis mi-
nimis, enimentissimis; articulis duplicibus vix lo-
batis; cauda attenuata; corpore tuberculata.

In the rich cabinet of American fossils in the
Albany Institute, there are two fine specimens of this
species, and I am indebted to that rising and liberal
institution, for the use of them in the present work.
Our cast is made from the smaller and more perfect
specimen of the two. The outline of the buckler
forms an irregular semi-ellipse. The front is convex
between the eyes, and very much depressed anterior-
ly, so as to form a sharp edge. The posterior part
of the buckler is marked with a transverse groove
parallel with the articulations of the back. The
cheeks are small and triangular; the small elevated
eye-shaped tubercles being placed in the middle,
nearly equidistant from each of the angles. The
eyes are not reticulated, the summit of each tubercle
only presenting a plain oval foramen. The middle

83

lobe of the abdomen is much broader than the lateral
lobes, and has 13 distinct, double articulations. The
side lobes are curved, and each costal arch is flatten-
ed anteriorly near their lower extremities, no doubt
for the purpose of enabling the animal to roll itself
into a ball. The tail is tapering, and is composed of
ten articulations. The crustaceous covering is here
more thickly deposited than on any other part. The
entire shell seems to have been covered with minute
elevated dots; these are beautifully distinct on the
buckler and on the tail. Whole length of the speci-
men described, not quite two inches.

The other specimen of this species in the cabinet
of the Albany Institute, is a large caudal end, three
inches arid a half long, entirely perfect. Both of
these fossils were brought from Williamsville, Nia-
gara county, New York. They occur in a dark shelly
limestone, filled with other petrifactions. The cal-
careous matter which has mineralized the trilobite,
in this instance, as in most others, is of a much darker
hue than the surrounding rock.

GENUS CERAURUS. Green.

Body, very much depressed, and slightly tapering.

Buckler, scarcely trilobate; cheeks large, flat, with
small remote oculiform tubercles; posterior angle of
the buckler spinous.

Abdomen, with twelve articulations.

Tail, rounded at the end, but terminating on each
side with two slightly curved spines.

84

The name of this genus is derived from the remark-
able spinous projections from the caudal end; this
peculiar organization separates it widely from the
other genera. The Paradoxides Spinulosus of Wah-
lenberg, which is supposed to be the old Entomolithus
Pamdoxus of Linne, the fossil, with which all the tri-
lobites were for a long time confounded, has not
only projecting spines from the tail, but from all the
costal arches of the lateral lobes. The presence of
eyes or of oculiferous tubercles in the Ceraurus, would
alone be sufficient to separate .it from the genus to
which that interesting fossil belongs. In the eighth
volume of Annales des Sciences Naturelles, Count
Rasoumowsky has figured and described the frag-
ment of a very curious relic, which seems to be an
intermediate link between our genus and paradox-
ides; in addition to a number of filamentous elonga-
tions of the costal arches, a curved spine seems to
project from the end of the tail, as in the «#. limulurus.
No name is given to this trilobite, which appears to
have been found on the banks of the Yaousa, near
Moscow, where it occurs in black, coarse, argillaceous
schistus. The Ceraurus is probably a very rare ani-
mal remain, as we have only met with it, in the unri-
valled cabinet of trilobites belonging to the Albany
Institute.

CERAURUS PLEUREXANTHEMUS. Green. Cast No. 33.
Fig. 10.

Clypeo postice arcuato, angulo externo in mucro-
nem valde producto; oculis minimis remotis, post-

85

abdomine in spinam arcuatam acutam utrinque ex-
tenso.

The exact contour of this species cannot be per-
fectly ascertained from our specimen; it seems, how-
ever, to have been lunate. The horns of the crescent
which form the posterior angles, are very distinct,
and they project like curved spines, some distance on
each side of the head. The middle lobe or front is
faintly scalloped on each side along the cheeks. The
cheeks are rather large, and are furnished with two
small oculiform tubercles, very remote from each other,
and quite near to the anterior portion of the buckler.
The abdomen is composed of twelve articulations.
The lateral lobes of the abdomen are flat, and each of
the ribs, at about half their extent, is marked on the
upper surface, with an elevated pimple. These little
pustules are nearly on a line with the oculiferous tu-
bercles of the buckler, and present two parallel ranges
down the body, one on each side of the middle lobe,
and are terminated by a curved spine, which projects
to some distance beyond the tail of the animal.
Length one inch and a fourth.

This remarkable organic relic was found near
Newport, in the State of New York. It is embedded
in black limestone shale, and so exceedingly depress-
ed is this animal, that a very thin lamen of the slate
removed from the surface would destroy every ves-
tige of its appearance. I am indebted to my early
friend, Professor T. R. Beck, for the use of this valu-
able petrifaction, which now belongs to the cabinet
of the Albany Institute.

86

GENUS TRIARTHRUS. Green.

Body, slightly convex; contractile?

Buckler?

Abdomen, with three articulations, side lobes longi-
tudinal, narrow, and wedge-shaped.

Tail, broad, rounded, without any membranaceous
expansion.

The name of this genus is derived from the cir-
cumstance, that the abdomen has but three articula-
tions; an organization which is very peculiar. These
curious fossil animals are very abundant in the rocks
in which they are found; but though I have examined
a multitude of specimens from different localities, no
vestige of the head or buckler could, on the most mi-
nute examination, be discovered. Whether these ani-
mals, during their petrifaction, were so contorted or
rolled up, as to bring the extremities of the body to-
gether, in such a manner as to present the posterior
folded part only to the view; or whether the buckler
has been destroyed by the process of mineralization,
as appears frequently to happen with the asaphs, we
are at a loss to determine.

The animal remains which belong to the genus
Triarthrus, differ so much in their' form and general
characters from all the other trilobites,thatwe perhaps
ought to regard them as forming another race of be-
ings. They are, however, more nearly allied to this
family than the Agnosti of Professor Brongniart.

87

TRIARTHRUS BECKII. Green. Cast No. 34. Fig. 6.

Cauda subrotunda, bipunctata; articulis abdominis
tribus, absque lobis lateralibus consuetis, sed lobo
arcuato utrinque apposite.

The only portions of this fossil which have yet been
found, are the abdomen and tail. The abdomen is
composed of three joints; the first passes from the
side lobes completely over the body, and on its upper
surface, near the middle of the back, there is often a
minute elevated pimple. The other two, pass ob-
liquely from the lateral lobes, and are interrupted in
their course over the body. The tail, or posterior
portion, is expanded, something like that of the Iso-
telus or Dipleura, and has a deep puncture on each
side, about half the distance between its terminal
border and the last articulation of the abdomen. The
lateral lobes are unlike those of any other genus.
They form narrow cuniform appendages to the sides;
near the first joint of the abdomen they are crossed
transversely by an elevated ridge, from which they
gradually taper along the sides of the body, and ap-
pear to inosculate in a delicate point at the central
border of the tail. The abdominal articulations do
not pass over these lobes, but just below the last
joint, a little transverse furrow, in perfect specimens,
may be noticed. The largest specimen of this frag-
ment I have seen is exactly half an inch in length.
This fossil occurs in black shaly limestone, on the

canal near Cahooes Falls, in the State of New York,
and at a number of other places in that State.

I have named this species in compliment to my
early friend, Professor Theodore Romeyn Beck, M. D.
well known both at home and abroad, as the learn-
ed author of the work on Medical Jurisprudence.
Some time after commencing this little Monograph,
I communicated my plan to Dr. Beck, and was sur-
prised and gratified to find that he was also engaged
with the same inquiries, and that he was then busy
in arranging and examining the unique collection of
trilobites belonging to the Albany Institute. With-
out the smallest hesitation, he placed all his speci-
mens at my disposal, and has facilitated otherwise
my undertaking, by every means in his power.
•

GENUS NUTTAINIA. Eaton.

Professor A. Eaton, in his Geological Text Book,
has proposed the Genus Nuttainia, to include two
remarkable trilobites which could not properly be
arranged in any of the previously established genera.
The two fossils here grouped together, bear no gene-
ric relation to each other. The first species which
he calls N. Concentrica, belongs to the genus Crypto-
lythus, which was proposed before the appearance of
his work, and has therefore been noticed in another
place.

The genus Nuttainia is thus characterized by its
author: " Head in three lobes, the middle one most
prominent ; the two lateral lobes sub-hemispherical,

89

or sub-quadrantalj the whole head bordered anterior-
ly with a punctured fillet: body distinctly three lobed,
middle lobe sub-cylindric, and not so broad as the

side lobes."

*

NUTTAINIA SPARSA. Eaton. Cast No. 35.

Fillet nearly straight in front of the middle lobe of
the head, punctures of the fillet scattered irregularly,
without any alternating ridgesj head compressed, co-
vered with scattered punctures, having its side lobes
much smaller than the middle one; middle lobe with
straight sides, giving it somewhat the form of a pa-
rallelogram.

Found in third grauwacke,* or grit slate in Coey-
mans, sixteen miles south-west of Albany. I have
the head of one before me two and a half inches
broad, and one and a half long. The whole of the
animal must have been six or seven inches in length.

The above account is copied from the " Text
Book." Mr. Eaton was kind enough to lend me the
only specimen of this curious fossil remain, which
has yet been found; from which his description was
taken, and of which our cast is an exact copy. His
generic characters do not in our opinion at all ap-
ply to this fragment. Nothing but the head of this

* In a manuscript note, Professor Eaton states that the third
grauwacke, or grit slate of Coeymans, " alternates with the un-
derlaying cherty lime rock." This opinion some of our geologi-
cal friends, familiar with the formation at Coeymans, and with
the Professor's nomenclature of rocks, have called in question.
H 2

90

singular trilobite remains, and it is doubtful whether
what is said to be the punctured fillet, " nearly
straight in front of the middle lobe," be not the com-
mencement of the articulations of the abdomen. The
whole fragment looks very much like the head of
some large Asaph or Ogygia.

GENUS BRONGNIATIA. Eaton.

Professor Eaton has proposed the name Brongnia-
tia (Brongniartia?) for a genus of trilobites, which
we think he has not defined with sufficient accuracy
to be of any practical use. The Isotelus gigas of
Dr. Dekay, which has been for a long time so well
established, is here ranked merely as a species under
the name of B. isotela. The relic which we described
before the Geological Text Book appeared as the
Triarthrus JBeckii, forms the species B. carcinoclea —
and the trilobite which is supposed to be the Asaphus
platycephalus of Stokes, is the only other species
mentioned. The A. platycephalus,* we know to be
identical with the I. gigas, and as the animal remain
described by Mr. Eaton is entirely different from Dr.
Dekay's fine species, we subjoin the account given in
the " Text Book."

Genus Brongniatia — Fore abdomen always, and
post abdomen in some cases, longitudinally divided
into three lobes, by regular series of undulations tra-

* For a figure and description of the Asaphus Platycephalus,
by Mr. Stokes, see Transactions of the Geological Society. Se-
cond Series, vol. i.

91

versing the joints, without grooves; articulations of
the side lobes being manifest continuations of those of
the middle lobe, and consequently, agreeing in num-
ber.

BRONGNIATIA PLATYCEPHALA. Eaton.

Head and fore abdomen very broad and depressed,
the abdomen with ten joints curved forwards at the
undulations; post abdomen and tail with about fif-
teen joints curved backwards at the undulations; the
three lobes of the tail more distinctly separated; divi-
sions between the joints of the abdomen double.

The representation of B. platicephala, figure 20,
plate 2, of the Geological Text Book, if it be accu-
rately drawn, is certainly of a trilobite never before
described. On the buckler, which is without eyes,
there is delineated a figure, not unlike some of the
leaves of the mulberry tree.

The tail is also very peculiar. In Silliman's Jour-
nal, Volume 21st, page 136, Professor Eaton pro-
posed for this curious fossil the temporary name of
Ogygies latissimus. "It is found, he observes, in the
upper soft slaty variety of the rock which has been
so successfully used for the lias cement at Chitteningo,
Sec. Dr Smith, of Lockport, (N. Y.) sent me two
specimens, taken from a continuation of the Chitten-
ingo lias rock, immediately beneath the geodiferous
lime rock on which the cherty (cornitiferous) re-
poses." The whole animal is six inches long, and
three broad.

92

NATURE OF THE TRILOBITE.

Every one familiar with the history of the Trilo-
bites, is aware that a good deal of controversy has
existed among naturalists, respecting the precise
link in the grand chain of organized beings, these sin-
gular fossil animals, should occupy. Professor Brong-
niart, Dr. Dekay, Audouin, and several other acute
observers, have placed them in the vicinity of the Li-
muli, and other Entomostraca with numerous feet;
while P. A. Latreille and others, presuming that these
animals were destitute of locomotive organs, as no
vestige of them has ever been discovered, fix their
natural position in the neighbourhood of the Chi-
tonesj or rather that they constituted the original
stock of the Articulata, being connected on the one
hand with these latter Mollusca, and on the other
with those first mentioned, and even with the Glome-
ris.* It was our original intention to have closed
this Monograph with a short history of these theories
— and of the notion advanced by Latreille and others,
that the Trilobites have been annihilated by some
ancient revolution of our planet, All these matters,
we think, are now put to rest by the late discovery
of some living Trilobites in the southern seas, near
the Falkland Islands. In the cabinet of the Albany
Institute, we have examined some of these recent
animals, which have very nearly the size and general

* See Cuvier's Animal Kingdom, vol. iii. pp. 135—6.

93

appearance of the Paradoxides Boltoni, as represented
on our frontispiece^ the species cannot, however, be-
long to that genus, as the buckler is furnished with eyes
very similar to those of the Calymene Bufo; its organs
of locomotion are short, numerous, and concealed un-
der the shell — but I do not feel at liberty to notice
the interesting animal more minutely. It will pro-
bably be described and figured shortly, in a perfectly
full and satisfactory manner, by Dr. James Eights,
the enterprising discoverer, together with several
other new and remarkable genera and species belong-
ing to the Entomostraca.

FINIS.

to tfie &pec(r&

CALYMENE Blumenbachii, -

Callicephala,

Selenecephala,

Platys,

Microps

Anehiops,

Diops,

Macrophthalma -

Bufo,

Rana,
ASAPHUS, Laticostatus,

Selenurus,

Limulurus,

Caudatus,

Hausmanni

Pleuroptyx,

Micrurus,

Wetherilli, r

PARADOXIDES Boltoni,
OGYGIA Sillimani,
ISOTELUS Gigas,

Planus,

Cyclops,

Megalops,

Stegops,
CRYPTOLITHUS Tessellatus,

Bigssbii,

DIPLEURA Dekayi,
TRIMERUS Delphinocephalus,
CERAURUS Pleurexanthemus,
TRIARTHRUS Beckii,
NUTTAINIA Sparsa,
BRONGNIATIA PJatycephala,

JOSEPH BRAND,

No. 12, CASTLE STREET, PHILADELPHIA,

Teacher of the Art of Preparing Birds, Quadrupeds,
Reptiles, $c. 4»c.

AND OF THE

Art of making Moulds and Casts in Wax, Plaster,
and Compositions.

In addition to the casts taken from the originals of the Trilo-
bites, he has also a few fine casts of the bones of the Megalonix
Laqueatus, Harlan. — Scaphites Cuvieri, Morton. — Mosasauru3
tooth, and of several rare fossil American Plants; — all taken from
the original fossils, in the Cabinet of the Academy of Natural
Sciences, &c. &c. These models are fac similes of the real ob-
jects, coloured according to nature.

As the originals of the above are in the possession of different
public and private cabinets throughout the United States, I have
at great trouble and expense, taken from them exact patterns,
so as to accommodate museums and scientific gentlemen with
them on very reasonable terms. This practice is now used in
several parts of Europe ; and thus the curious are able to supply
their cabinets with rare specimens, often superior to the origi-
nals.

JOSEPH BRANO having finished for us a number of models
of different objects in Natural History, we have no hesitation in
recommending him as an exceedingly skilful artist.

JACOB GREEN, M. D.

RICH'D. HARLAN, M. D.

P. A. BROWNE, ESQ.

CHAS. A. POULSON.

ISAAC PARRISH, M. D.

S. G. MORTON, M. D.
Philadelphia, October 3d, 1832.

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