Chapter III: Part 3

_Abdomen_, with thirteen distinct, double articulations divided into three lobes by a slight longitudinal 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 genus resembles in some respects both the Calymene and Dipleura. The form of the buckler, the position and structure of the oculiferous tubercles, and the scarcely lobate divisions of the abdomen, will readily distinguish it from the Calymenes. The articulations of the tail, not being covered with a shelly crust, is a character too obvious to confound it with the genus Dipleura. There is, we think, a beautiful chain of gradations of resemblances, between the Isotelus, Dipleura, Hemicrypturus 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 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 minimis, enimentissimis; articulis duplicibus vix lobatis; 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 anteriorly, 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 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 flattened 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 specimen 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 and a half long, entirely perfect. Both of these fossils were brought from Williamsville, Niagara county, New York. They occur in a dark shelly limestone, filled with other petrifactions. The calcareous 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.

The name of this genus is derived from the remarkable spinous projections from the caudal end; this peculiar organization separates it widely from the other genera. The _Paradoxides Spinulosus_ of Wahlenberg, which is supposed to be the old _Entomolithus Paradoxus_ of Linné, the fossil, with which all the trilobites 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 fragment of a very curious relic, which seems to be an intermediate link between our genus and paradoxides; in addition to a number of filamentous elongations of the costal arches, a curved spine seems to project from the end of the tail, as in the _A. 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 animal remain, as we have only met with it, in the unrivalled cabinet of trilobites belonging to the Albany Institute.

Ceraurus Pleurexanthemus. _Green._ Cast No. 33. Fig. 10.

Clypeo postice arcuato, angulo externo in mucronem valde producto;
oculis minimis remotis, postabdomine in spinam arcuatam acutam
utrinque extenso.

The exact contour of this species cannot be perfectly ascertained from our specimen; it seems, however, 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 tubercles 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 depressed is this animal, that a very thin lamen of the slate removed from the surface would destroy every vestige of its appearance. I am indebted to my early friend, Professor T. R. Beck, for the use of this valuable petrifaction, which now belongs to the cabinet of the Albany Institute.

Genus Triarthrus. _Green._

_Body_, slightly convex; contractile?

_Buckler?_

_Abdomen_, with three articulations, side lobes longitudinal, narrow, and wedge-shaped.

_Tail_, broad, rounded, without any membranaceous expansion.

The name of this genus is derived from the circumstance, that the abdomen has but _three_ articulations; 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 minute examination, be discovered. Whether these animals, during their petrifaction, were so contorted or rolled up, as to bring the extremities of the body together, 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, that we perhaps ought to regard them as forming another race of beings. They are, however, more nearly allied to this family than the Agnosti of Professor Brongniart.

Triarthrus Beckii. _Green._ Cast No. 34. Fig. 6.

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

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 obliquely 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 Isotelus 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 cuneiform 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 appear 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 fragment 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 learned author of the work on Medical Jurisprudence. Some time after commencing this little Monograph, I communicated my plan to Dr. Beck, and was surprised 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. Without the smallest hesitation, he placed all his specimens 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 generic relation to each other. The first species which he calls N. Concentrica, belongs to the genus Cryptolythus, 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, or sub-quadrantal; the whole head bordered anteriorly 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 ridges; head compressed, covered 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 parallelogram.

Found in third grauwacke,[47] or grit slate in Coeymans, 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.

[Footnote 47: In a manuscript note, Professor Eaton states that the third grauwacke, or grit slate of Coeymans, "_alternates_ with the underlaying cherty lime rock." This opinion some of our geological friends, familiar with the formation at Coeymans, and with the Professor's nomenclature of rocks, have called in question.]

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 apply to this fragment. Nothing but the head of this 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 commencement 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 Brongniatia (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 Beckii_, forms the species B. carcinodea--and the trilobite which is supposed to be the Asaphus platycephalus of Stokes, is the only other species mentioned. The A. platycephalus,[48] 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."

[Footnote 48: For a figure and description of the Asaphus Platycephalus, by Mr. Stokes, see Transactions of the Geological Society. Second Series, vol. i.]

Genus Brongniatia--Fore abdomen always, and post abdomen in some cases, longitudinally divided into three lobes, by regular series of undulations traversing the joints, without grooves; articulations of the side lobes being manifest continuations of those of the middle lobe, and consequently, agreeing in number.

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 fifteen joints curved backwards at the undulations; the three lobes of the tail more distinctly separated; divisions between the joints of the abdomen double.

The representation of B. platycephala, figure 20, plate 2, of the Geological Text Book, if it be accurately 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 Journal, Volume 21st, page 136, Professor Eaton proposed 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, &c. Dr Smith, of Lockport, (N. Y.) sent me two specimens, taken from a continuation of the Chitteningo lias rock, immediately beneath the geodiferous lime rock on which the cherty (cornitiferous) reposes." The whole animal is six inches long, and three broad.

Nature of the Trilobite.

Every one familiar with the history of the Trilobites, is aware that a good deal of controversy has existed among naturalists, respecting the precise link in the grand chain of organized beings, these singular fossil animals, should occupy. Professor Brongniart, Dr. Dekay, Audoúin, and several other acute observers, have placed them in the vicinity of the Limuli, 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 Chitones; 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 Glomeris.[49] 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 appearance of the Paradoxides Boltoni, as represented on our frontispiece; the species cannot, however, belong 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 under the shell--but I do not feel at liberty to notice the interesting animal more minutely. It will probably 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 belonging to the Entomostraca.

[Footnote 49: See Cuvier's Animal Kingdom, vol. iii. pp. 135-6.]

FINIS.

Index to the Species.
————

CALYMENE Blumenbachii, page 28
Callicephala, 30
Selenecephala, 31
Platys, 32
Microps, 34
Anchiops, 35
Diops, 37
Macrophthalma, 39
Bufo, 41
Rana, 42
ASAPHUS Laticostatus, 45
Selenurus, 46
Limulurus, 48
Caudatus, 50
Hausmanni, 52
Pleuroptyx, 55
Micrurus, 56
Wetherilli, 57
PARADOXIDES Boltoni, 60
OGYGIA Sillimani, 63
ISOTELUS Gigas, 67
Planus, 68
Cyclops, 69
Megalops, 70
Stegops, 71
CRYPTOLITHUS Tessellatus, 73
Bigsbii, 76
DIPLEURA Dekayi, 79
TRIMERUS Delphinocephalus, 82
CERAURUS Pleurexanthemus, 84
TRIARTHRUS Beckii, 87
NUTTAINIA Sparsa, 89
BRONGNIATIA Platycephala, 91

JOSEPH BRANO,

No. 12, CASTLE STREET, PHILADELPHIA,

_Teacher of the Art of Preparing Birds, Quadrupeds,
Reptiles, &c. &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 Trilobites, he has also a few fine casts of the bones of the Megalonix Laqueatus, _Harlan_.--Scaphites Cuvieri, _Morton_.--Mosasaurus 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 objects, 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 originals.

·—▸⏵►●◓●◄⏴◂—·

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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Transcriber Note

Minor typos corrected. The quotation on page 91 has been corrected based on the original article found at The Internet Archive.