DESCRIPTION OF THE FOSSILS. 
105 
also from the “formation of the Llano Estacado,” contains casts of small shells, too obscure 
and imperfect to decide the specific characters, or determine the age of the formation to which 
they belong. They are imbedded in a compact ferruginous rock. 
No. 128. -? This specimen has no label; it is a gray or ash-colored carbonate 
of lime, evidently of organic origin. It consists of innumerable closely arranged fibres or 
small hexagonal prisms, having a direction transverse to the surface of the slab, and more or 
less irregularly curved and radiating. The specimen is from one quarter to three quarters of 
an inch in thickness, and five inches long, somewhat abruptly curved in a transverse direction. 
The concave side is unequally striated and grooved, evidently from the surface of some body to 
which it has adhered. The exterior is concentrically undulated, like the surface of a shell, the 
undulations converging in one direction. 
The general structure is similar to that of Chaetetes, and like the coarser fibrous portions of 
the outer shell of Inoceramus. Professor Tuomey, to whom the specimen has been subsequently 
shown, pronounces it to be the shell of a large species of Inoceramus, having found similar 
specimens in Alabama with the hinge attached. The specimen under consideration has all the 
characters of having these relations ; but it is not so easy to account for the occurrence of simi¬ 
lar fibrous laminee of many inches square, having but little thickness, and extending for many 
inches, and covered with valves of the Ostrea congesta. 
No. 126.—“Three miles north of Galisteo.” The smaller specimens with this label are 
similar to the preceding, consisting of thinner lamime, with broad undulations upon the exterior 
surface, and coarse striae, or what appear to be impressions of imbricating lamellae upon the 
under or concave surface. The fibrous material exhibits lines of successive growth, and is 
sometimes separable into thinner laminae. These specimens do not exceed a quarter of an inch 
in thickness. 
No. 126.—“Three miles north of Galisteo.” These specimens contain numerous fragments 
of shells and impressions of the surface of Ammonites, and Inoceramus, but all of them too 
imperfect to be specifically recognized. Notwithstanding the fine specimens of the fibrous outer 
shell of Inoceramus described above, no specimens of entire individuals have yet been brought 
in among these collections.* 
Nos. 122 and 129.—“ Carboniferous fossils west of San Francisco mountain.” These speci¬ 
mens include fragments of two species of Productus of large size. One of these is probably 
allied to or identical with Productus semireticulatus , having the same kind of superficial marking 
in its longitudinal stria3, crossed by concentric lines near the beak, and not on the body of the 
shell. Two other specimens, in addition to these characters, have also the broad mesial sinus 
of that species. Among the specimens from this locality are two of hornstone, containing frag¬ 
ments of coral too obscure to be determined. 
With the Productus and Spirifer of the carboniferous formation, we find also several frag¬ 
ments of crinoidal columns belonging to two different species, but too imperfect to be identified ; 
also some fragments of Cyatbophyllum in the same condition. They are all from the carboni¬ 
ferous limestone at the Pecos villages. 
No. 130.—“ Orthoceras pres d’Agua Fria, Sierra Madre.” This is a portion of the outer 
chamber of an Orthoceras, too obscure for determination. It is in a greenish argillaceous 
limestone. 
° In the specimens from the Missouri, above the mouth of l’Eau qui Court, already referred to, the Ostrea congesta is 
attached to fibrous laminae, precisely similar to those described above, except that they are rarely more than a quarter of 
an inch, and often not more than an eighth of an inch in thickness. These laminae appear to have been flexible, as they 
are often bent and folded among the shells ; and they exhibit abrupt inequalities, filling the irregular spaces between the 
shells, and radiating in somewhat hemispheric elevations upon the surface. These laminae extend in broken pieces often 
for many yards, and are attached and cemented together by calcareous matter, and covered with almost continuous layers 
of the Ostrea. Mr. Meek informs me that he has seen similar fragments or laminae scattered at intervals through the beds 
of clay succeeding that containing the Ostrea, but without any shells attached. What appears most remarkable in this 
instance is that no species of Inoceramus is known in the bed which contains the Ostrea congesta, at least in the locality 
where this shell is so abundant, and where the fibrous laminae occupy so conspicuous a place. 
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