AND AVES OF NORTH AMERICA. 81 



rounded rib ; in front a narrow keel extends from the tip to the neural canal ; the lateral ake are curved backwards. 

 On a more posterior cervical, the lateral ate 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, dividing two 

 shallow anterior grooves ; breadth and length equal iu section. In a last cervical, length 2 in. 12 1., the longitudinal 

 section (equal about an inch) is longitudinal cuneiform, owing to the projection of the anterior ala. In an anterior 

 dorsal the section is longitudinal (1 in. 5 1.); the lateral ribs remain at the base only, and the posterior carina 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 Thoracosaurus 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 condyles are deeply divided, and project far before the coronoid fossa, which is little marked. The shaft is 

 nearly cylindric, strongly arched backwards. 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 coiacoid face. The 

 medullary cavity is very small. 



In. Lin. 

 Total length (restored), 10 



Length from condyles to deltoid crest, G 7. 



" across head (straight*, 3 2. 



" across condyles, 3 0.5 



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 into 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 antero- 

 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 an 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 Polyptychodons 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, 22. 5 



" crown, 9. 



Diameter antero-posterior at base, 4. 



These teeth are in 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. 



AMERI. PH1LOSO. SOC. — VOL. XJV. 21 



