140 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



oblique wrinkles extending upward about 2 mm. above the basal 

 margin. 



A fourth tooth, 28 mm. in length and lacking the external face of the 

 crown, possesses rugosities above the base on the anterior, internal, 

 and posterior faces. At least four or five vertical carinae extend from 

 these basal rugosities toward the apex of the crown. 



Measurements of teeth (in millimeters) 



TYMPANIC BULLA 



This left tympanic bulla is slightly larger than that of Kentriodon 

 pernix (Kellogg, 1927, p. 28, pl. 1, figs. 2, 5). It lacks most of the 

 outer lip, its processes, and the posterior apophysis. When viewed 

 from the ventral side, the posterior portion is seen to be characterized 

 by a deep groove, the anterior portion is depressed on the outer half, 

 and the profile of the inner surface is more convex than that of Ken- 

 triodon pernix. The conformation of the involucrum is similar to 

 that of K. pernix except that it is more attentuated anteriorly. The 

 greatest length of this bulla is 35 mm., and the greatest width of the 

 involucrum posteriorly is 13 mm. 



DORSAL VERTEBRAE 



The two dorsal vertebrae associated with the eleven teeth resemble 

 Tretosphys gabbii in the dorsoventral elongation of the neural canal. 

 One of them (pl. 15, fig. 1) is considered to be the fourth in the dorsal 

 series. This vertebra differs from the anterior dorsal of T. gabbii in 

 having a larger centrum, more closely approximated prezygapophysial 

 facets, more robust diapophyses, and a slightly narrower neural canal. 



The deeply concave lateral surface of the centrum (pl. 15, fig. 4) is 

 continuous with the depression on the outer surface of the pedicle 

 of the neural arch. As contrasted with the anterior face of the 

 centrum, the posterior face (pl. 15, fig. 7) is noticeably wider (39.5 



