21 



mental foi'anien a. little iu advance of premolar 2. From lu trout of this 

 forameu a depression extends backward nearly parallel with the infer- 

 ior and superiors borders of the ramus, to where the ramus is broken 

 off beneath molar 3. This depression is nearer the inferior margin, 

 being about one-third the distance from the inferior to the superior 

 liorders. In front of premolar 2 the upper margin of the jaw slopes 

 downward to whei-e it is broken. Looking from above the ramus is 

 slightly sigmoid. 



Premolar 2 is mucli likt' the corresponding tooth in P. sansanieiisis 

 On the anterior-interior face of the tooth is a concavity looking inward 

 and upward. The protocoue on the inner face is nearly conical. It is 

 joined on the anterior-external side by a sharp ridge forming the outer 

 boundary of the anterior depression. Opposite this on the posterior- 

 internal side of the protocone a short ridge joins the two posterior 

 lobes, or connects with the anterior horn of the crescent. The valley 

 between the limbs of this crescent looks more backward than in P. 

 sajisaniensis. This is also true of premolar 3. In the latter tooth the 

 two anterior lobes are more separated, that is, form a greater angle, 

 than in the specimen figured by Filhol, in this respect being more like 

 premolar 4 than in Filhol's specimen. In the American specimen in- 

 stead of there being an enclosed depression on the posterior part of 

 the tooth there is a gully opening inward. In premolai* 2 the middle 

 lobe is directed obliquely backward as in P. sansaniensis. This lobe 

 in premolar 3 is directed forward. Premolar 4 is little different from 

 Filhol's specimen except that there is a naiTow gully opening inward 

 which would be obliterated on further wear. Premolar 2 is slightly, 

 premolar 3 more, and premolar 4 consideral)ly worn; while molar 1 is 

 much woi'u. molar 2 less and molar 3 only slightly so. 



The enamel is smooth on the interior and somewhat rugose on the 

 outside, but more especially so on the outside of the true molai'S. 



MEASUREMENTS. 



Premolar 1. Premolar 2. Premolar 3. 



M. M. M. 



Length 0(»S8 .011 ^ .011 



Width 0042 .000 .007 



Height 005 . 007 .007 



On account of its worn condition the anterior enamel lake in molar 

 1 is partly olilitci-atcd, mnkiiig two small oih's. The enamel of the 

 small median external lobe is continuous with the posterior outer 

 crescent. This crescent is still entirely sei)arated on the grinding sur- 

 face from the rest of th(» tootli. but a little moi"e wear would make it 

 confluent witli the posterior internal crescent on the posterior internal 



