I9I0.] SINCLAIR— SKELETON OF LEPTAUCHENIA. 199 



latter from their comparatively small size. In the cervical series, 

 the atlas is characterized by a slender inferior arch and broad 

 superior arch with strong backward slope to its dorsal profile. The 

 canal for the vertebral artery perforates the base of the transverse 

 process at the margin of the posterior cotylar surface, where it is 

 inclosed by but a narrow bridge of bone, soon emerging on the 

 lower surface of the process. Some distance anterior to the point 

 of emergence, it again perforates the transverse process, joining 

 the neuro-arterial canal near its point of emergence. The margin 

 of the transverse process is broken in all the specimens examined, 

 but seems to have been circular. The axis carries a large neural 

 spine, of which the dorsal border slopes strongly backward and 

 upward. All the transverse processes of the cervicals are perfor- 

 ated by the vertebral artery. 



Girdles. — The scapula is a triangular element of which the outer 

 surface is divided unequally into large post- and small pre-spinous 

 fossae by the prominent scapular spine, of which the acromion 

 process is directed forward. Of the pelvic girdle, the ilium is 

 broadly expanded in the transverse plane, rather more so than the 

 figure would indicate. The gluteal fossa is shallow and the ante- 

 rior superior spine quite prominent. The ilio-pectineal eminence 

 varies in prominence in diflferent specimens. Both ischial and 

 pubic rami are stout. Their distal expansions are lacking in all 

 the Princeton specimens. 



Limbs . — The strong forward curvature of the radius and heavy 

 olecranon process of the ulna are perhaps the most striking fea- 

 tures of the fore limb. Apart from this, there are no peculiarities 

 which call for special comment. It is possible that the lateral 

 digits in both fore and hind foot have not been given sufficient 

 length, the error, if such it be, arising from an attempt to scale the 

 drawing from a few dissociated phalanges. But one terminal 

 phalanx is represented in the Princeton collection, and of this the 

 tip is broken off and the margins somewhat damaged. It seems to 

 have been a small pointed hoof. 



Princeton University, 

 April, 1910. 



