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Show 84 " The similarity of this species to U. Hay den i is another evidence of the fact ( to which I have often called attention) that fresh- water shells, as a rule, are fur less reliable guides than marine types in identifying formations, since they often closely resemble each other from widely different horizons. " Along with the foregoing there are fragments of several other species, too imperfect to be well characterized. One of these has more prominent and curved beaks, with small, radiated costre. I have not usually attempted to name species from such imperfect specimens; but as Professor Cope desires to have some names by which these inter-esting types may be designated, I wonld propose for this form with the more gibbous beaks and small radiating costre the name U. Gallinensis. " Still another species is also represented in the collection by fragments. This evidently differs from the last by having much more depressed, more obi ique, and less gibbous beaks, and stronger radiating cost ® , only seen on the posterior dorsal region, at least in the specimen examined. This might be called U. terrce- rubrcB. " There is also another more compressed form, with depressed beaks and flattened or concave flanks, resembling the first- described species ( U. Cristoncnsis,) but showing fine radiating costse, in one example on the beaks only, and in another apparently over most of the valve. 14 Supposing that these shells really come from the horizon of the Trias, they are the oldest Unios yet found, so far as I am informed, in this country. 17 The remains of Veriebrata obtained from the latter formation are those of fishes and reptiles. The former are rhomboganoid scales of small species, which are numerous in the coprolites of the reptiles; the latter represent the three orders of Orocodilia, Dino-sauria, and apparently of Sauropterygia. The dinosaurian order is represented by a part of the crown of a tooth of a species of large size of the general character of Lollops.. Both faces are convex, the one more so than the other, and the long axis of the crown is curved toward the less convex side. Both cutting- edges are sharply and closely crenate-denticulate, as in Lwlaps, Anblysodon, & c; otherwise, the enamel is perfectly smooth. There was not enough of this animal discovered to enable me to identify it. The suspected Bauropterygian species is represented by a single vertebra, with the centrum slightly depressed, circular section, and about as long as wide. The neurapophysis appears to have been united by suture, although this point is not so clear as is desirable, and the bases of the diapophysis are very stout, extending the entire length of the upper half of the lateral surface of the centrum. Of the articular faces, one is much more concave than the other. Length of centrum, 0m. 05; width, 0m. 057; depth, 0m. 055. The crocodilian remains consist of a portion of a jaw- bone, with alveoli for four teeth, of a broken vertebra, and a number of dermal scuta and fragments of other bones; at another locality not far distant, numerous remains of saurian bones, embraciug dermal and cranial pieces, coprolites, a fragmentary tooth, & c, which may have some affinity to these. The species indicated by the former may be named and described as follows: TYPOTHORAX COCCIXARUM, Cope, genus et species nova. Character genericus.- The fragment of jaw belonging to this genus is probably maxillary in position, for the following reasons: The interior face of the bone is sutural. and for the most part solid. This would refer it to the position of the symphyseal portion of the dentary bone of a gavial- like form, but for other considerations. Supposing the piece to be dentary, and the suture therefore vertical, the incongruity follows that the alveolar face becomes very steep, so much so as to prevent the interlocking of the teeth, which become lateral in position. If, however, the jaw- fragment be reversed in position, and the alveolar face placed in a horizontal position, the suture of the inner side forms a sharp angle with the vertical plane, as it should on the supposition of its being the maxillary bone; the wedge- shaped section necessary to fill the space between it and the median plane, being that of the prolonged posterior spine of the premaxil-lary bone. The solidity of this portion of the muzzle is inconsistent with the gavial genera of the Jura and later times, but not with the structure of the Triassic Belodons. The posterior part of the inner face is, however, strongly excavated, and the sutnral margin exhibits an outward deflection, which is either the boundary of the nostril or the suture for the apex of the prefrontal or nasal bone. In either case, the nareal cavity and the nostril are posterior in position, in conformity with the structure of the " meco-dontn Crocodilia. The alveoli are large and arranged in a curved line; one of them somewhat exterior in position and isolated by short diastemata, like a canine. Surface of the bone pitted. The dermal scuta found close to the jaw- fragment have flat upper surface marked with shallow pits, rather closely placed, having resemblance to an obsolete Trionyx sculpture. Near one of the margins of the bone, the pits run out in shallow grooves. A portion of a vertebral centrum found with the jaw exhibits one articular face; this is shallow concave, of the type of the amphicoelian division of Crocodilia. The body of the centrum is much compressed. The other remains include a portion of a dermal t> one like those described, and the crown of a tooth, among other fragments. This crown, which has lost most of its en- |
