Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/87

 AND AYES OF NORTH AMERICA. 81 rounded rib ; in front a narrow keel extends from the tip to the neural canal ; the lateral ahe are curved backwards. Ou a more posterior cervical, the lateral ala; are very heavy, short and rounded, and enclose no groove with the slightly projecting posterior vertical rib, while the anterior keel has become a strong compressed wing, killing two shallow anterior grooves ; breadth and length equal in section. In a last cervical, length 2 in. 12 1., the longitudinal section (equal about an inch) is longitudinal cuneiform, owing to the mujeetion of the anterior ala. In au anterior dorsal the section is longitudinal (1 in. 5 1.); the lateral ribs remain at the base only, and the posterior earina is strong and sharp ; it is acuminate. and was probably subacute, but is broken at tip ; if restored would measure 4 in. 6 1. at least. Humerus-This element is relatively much shorter than in Thora.cosaurus or modern Crocodilia ; it is also stouter and more curved than these, and furnished with very largely developed deltoid crest and condyles. One specimen accompanying femur from the same—the right side, and many other elements from near Birmingham, Burlington County, N. J., have been submitted to me by Prof. Cook. The coudyles are deeply divided. and project far before the coronoid fossa, which is little marked. The shaft is nearly cylindric, strongly arched backwaids. The groove bounded by the deltoid crest is very deep. A portion between the head and the crest is lost. The former is truncate above, with a very oblique coracoid face. The medullary cavity is very small. Total length (restored), Iii. 10 Lin. Length from condyles to deltoid crest, ic across bead (straight', across condyles, 6 3 3 7. 2. 0.3 Least circumference of shaft, 4 2. Femur.-The shaft of the femur is a most characteristic piece from the greensand of the Eastern States. It is rather more than usually flattened intero-externally, and at the point of insertion of the adductor muscle is trilateral in section from the elevation of the ridge of insertion, and the depression of the antro-inferior face iuto a shallow, longitudinal concavity. The ridge and the surface behind it are rugose. The shaft below and up to the head is longitudinally concave on the inner side, plane on the outer. The articular face of the head has a remarkable autero-posterior extent, and is more obliquely produced upwards and forwards, in relation to the longitudinal axis of the shaft than in the other species. To support it the end of the shaft is turned forwards and strengthened by thickness, having a flat anterior face not seen in other species, and the articular face is bent downwards at right angles to it, and to the course of the longer posterior portion. It is here widest also. This form gives au unusual anteroposterior range of motion, and is appropriate to a powerful swimmer. The insertions for powerful muscles would indicate the same. - The condyles of this femur are lost. The teeth have some resemblance to the Polyptychodous in their strong ridges, but they have distinct anterior and posterior cutting edges, dividing a larger external from a smaller internal surface, the anterior turning in towards the latter, near the base of the crown. The section of the base of the crown is a broad oval, tip more compressed and worn obliquely outwards by use. Internally eight, externally eleven strong, but fine ridges extending over the usual half or two-thirds, alternating with shorter ones ; all obsolete at base anteriorly. The color of the two teeth is black at base, ochre at tip ; between, lined by both colors. Lines. Total length tooth, crown, 22.5 9. Diameter autcro-posterior at base, 4. These teeth are iu the alveolae of a distal portion of the maxillary bone, 4 in. long. Three in. one line includes three alveolae, measuring between margins. The muzzle has been here very slender, as the measurements show. made at the posterior tooth.; the anterior teeth issue successively higher up, and above the palatine plane. AMER!. PHILOSO. SOC. N'OL. XIN'. 21