116 R. 8. Lull — Primitive Pecora in Yale Museum. 



This form is distinguished from L. evansi of the Oreo- 

 don beds, aside from its geological level, by being about 

 one fourth larger, and by the great obliquity of the 

 molars. The bullae in all specimens of L. evansi before 

 me are more inflated. The type is an aged animal, hence 

 in their present state of wear there is little that is dis- 

 tinctive about the teeth. The general shape of the man- 

 dible and the position of the mental foramina, of which 

 there are two, are about the same in both species. 

 Cingula are absent and the external basal pillars are 

 feebly developed, as in evansi. 



Measurements are as follows: 



L. evansi 

 L. obliquidens Cat. No. 10542 



Holotype Eatio Y. P. M. 

 mm. mm. 



Length, tooth-row, P 2 to M 3 (left) . . 48 1.23 39 



Length, M 1 to M 3 26 1.24 21 



Length, M 3 9 1.20 7.5 



Width, M 3 12 1.54 7.7 



Width, P 2 5 1.25 4 



Length, tooth-row, P, to M 3 51.7 1.21 42.5 



Length, M ± to M 3 31 1.26 23.7 



Length, M 3 14 1.29 10.8 



Width, M 3 - 7 1.40 5 



Nanotragulus loomisi, gen. et sp. nov. 



(Fig. 1.) 



Holotype, Cat. No. 10330, Y. P. M. Collected by E. S. Lull in 1908 at 

 Castle Butte, Big Muddy Eiver, near Spanish Mines, Wyo. Miocene (lower 

 Harrison). Palate with upper cheek teeth complete, right lower jaw fairly 

 complete, with six teeth, left with series of four teeth. Detached premolar. 

 Imperfect petrosal? 



Distinguishing characters: Upper dentition. — Teeth 

 subhypsodont ; P 2 -M 3 a compact series withont diaste- 

 mata; mesostyle lacking on molars; no trace of molar 

 cingula nor of internal basal pillars ; molars simple, of 

 f our crescents each ; M 3 with four external pillars ; meta- 

 style enlarged toward base of tooth. Premolars three 

 only, preserved in situ ; P 2 trenchant, single-cusped, two- 

 rooted, slightly grooved on outer face. P 3 also trenchant, 

 of greater antero-posterior diameter than P 2 , apparently 

 three-rooted, with postero-internal cingulum but no 

 internal cusp (deuterocone), and with two faint external 



