Page:Notice of Gigantic Horned Dinosauria from the Cretaceous.pdf/3

Rh characters with the remains of cavicorn mammals from that formation, they were referred to the genus Bison, under the name B. alticornis. The writer has since learned that they were found in the Denver beds, which, although regarded as Tertiary, are probably Cretaceous. Under these circumstances, this well-marked species may be known as Ceratops alticornis, until additional remains make certain its true nature.

Another new member of the Stegosauria, from a lower horizon in the Cretaceous, was discovered several years since, in Wyoming, and is now in the Yale Museum. The skull is not known, but various portions of the skeleton were secured. One characteristic feature in this genus is the dermal armor, which appears to have been more complete than in any of the American forms hitherto found. This armor covered the sides closely, and was supported by the ribs, which were especially strengthened to maintain it. In the present specimen, portions of it were found in position. It was regularly arranged in a series of rounded knobs in rows, and these protuberances have suggested the generic name.

Near the head, the dermal ossifications were quite small, and those preserved are quadrangular in form, and arranged in rows. The external surface is peculiarly marked by a texture that appears interwoven, like a coarse cloth. This has suggested the specific name, and is well shown in the cut below.

The fore limbs are especially massive and powerful, and are much like those of the Jurassic Stegosaurus. There were five well-developed digits in the manus, and their terminal phalanges are more narrow than usual in this group. The ribs are T-shaped in transverse section, and thus especially adapted to support the armor over them. The caudal vertebræ are more elongate than those of Stegosaurus, and the middle caudal have a median groove on the lower surface of the centrum.

The animal when alive was about thirty feet in length. The known remains are from the middle Cretaceous of Wyoming.

New Haven, Conn., July 24th, 1889.