oliasaurus, the supposed caucdals of the latter proving to be its cervicals. Characters distinguishing it from Plesiosaurus have never been pointed out, and it is here retained apart from it on the supposition that its scapular arch is constructed on the same principle as that of Elasmosaurus, a point, however, which has not been ascertained.
This genus is not as well known as Elasmosaurus, owing to the fragmentary condition in which it is usually found. Its marked character is its short depressed cervical region, as compared with the excessively long and compressed one of Elasmosaurus. It also differs from it in the apparent continuity of the series of diapophyses from the dorsal to the cervical series. In Elasmosaurus these processes are wanting on the anterior dorsals. They are very elongate on the other hand, on the posterior dorsals of Elasmosaurus ; in Cimoliasaurus we have as yet no evidence as to their length, as they are broken in our specimens.
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The rapid diminution in dimensions of the cervical series in Cimoliasaurus indicates a short neck, and far less slender general form. Leidy suggests from the absence of sacral characters, that posterior limbs have been probably wanting in this genus: the same vertebral characters are seen in Elasmosaurus, but it has a large pelvic and scapular arches ; the presence of limbs in it cannot be doubted. The femur of Cimoliasaurus is described below, and is the only limb bone yet assignable to a species of this genus. It resembles that of Plesiosaurus. It is thicker and shorter however than in any species of the latter genus, and is quite short. The distal extremity is thick, and presents pits for the attachment of the articular cartilage ; the faces for both ulna and radius are extensive, and indicate a large manus and elongate limb. The rotundity of the head indicates extensive rotation ; and we may be satisfied that the animals of this genus were furnished
AMERI. PHILOS. SOC.-VOL. XIV. ]]
