3o6 SCOTT. [Vol. XI. 



The upper premolars as a whole are very much like those of 

 Leptomeiyx, but more elongate and of somewhat simpler con- 

 struction. In Hypertragulus they are still simpler and more 

 trenchant, as they are in existing tragulines. 



The molars are of the extreme brachyodont type, short 

 antero-posteriorly and broad transversely, so as to present a 

 nearly square outline ; ^ is slightly the largest of the series. 

 The external buttresses (proto- and mesostyles) and the median 

 ribs on the outer faces are very prominent and sharply defined ; 

 the internal pillar varies considerably in the different specimens, 

 — in some being quite absent and in others strongly developed ; 

 the inner cingulum also varies much in strength and would 

 appear to be more prominently marked in the males than in 

 the females. The valleys are narrow and shallow and rapidly 

 wear down to mere lines. The shape and proportions of these 

 molars are closely like those of Leptomeiyx, the principal differ- 

 ence between the two genera being that in Protoceras the inner 

 crescents are rather more complete. Doixatherium has molars 

 of which the outer crescents are extremely like those of 

 Protoceras, but the inner ones are thicker and more sloping. 

 In Hypertragidiis the molars are like those of Leptomeryx. 



B. Lozver Jaw (PI. XXI, Figs, i and 4). — None of the 

 specimens in the Princeton collection have the lower incisors or 

 canines in position. Osborn and Wortman give the following 

 description of them. " The inferior incisors present delicate 

 spatulate crowns ; the median [and] second incisors are slightly 

 larger than the lateral incisor, which is very delicate. The 

 canine has precisely the same delicate structure as the lateral 

 incisor " (No. 8, p. 359). In the female pi resembles the cor- 

 responding tooth in the upper jaw, but is rather smaller and is 

 implanted by a single fang. I have seen no example of this 

 tooth in the male, but as has already been mentioned, the abra- 

 sion on Xhe. posterior i2iCQ of the upper canine renders it prob- 

 able that in that sex pi was caniniform. Even in the female 

 it is considerably in advance of Pj_ and nearly far enough for- 

 ward to abrade the upper canine, being separated by a diastema 

 from the lower canine and by a longer one from p^. In Gelocus 

 ^ is very small and simple and stands close to p2. 



