268 



DOUGLASS FOSSfL MAMMALIA 



M. 



Length of molar series about* 070 



Length of Pi 0105 



Width of Pi 00G 



Height of crown of Pi 009 



Length of P^ 015 



Width of P* 0103 



I [eight of crown of P* 0095 



Length of PA .' 015 



Width of P-'- 0.14 



Height of PA 0105 



Length of Pi 015 



Width of Pi 017 



Length of M 1 019 



Width of M-' 022 



Length of M* 0245 



Width of M* 027 



Height of Mi 008 



Width of MA 030 



Agriochasru8 minimus, sp. now 

 Type No. 59. 



As A. mazimus is the largest known Agriochoerus, if it is an Agriochoerus at all, so 

 this species is the smallest. It is represented by the molars, last two premolars, and the 

 zygomatic arch of the right side belonging to a mature individual. It was found in 

 the White River beds, northwest of Three Forks, with. Limnenetes anceps. 



Specific characters: Size small; P$ long antero-posteriorly ; outer crescents of 

 molars very low, their outer faces looking downward much more than outward. 



P 3 as seen from above is nearly a right-angled triangle, with the right angle placed 

 postero-externally. The outer surface of the protocone w concave with a faint ridge in 

 the median line of the tooth. The tritocone is distinguished from the protocone as 

 viewed from the inside, though it is not so apparent from, the outside ; but the protocone 

 is the larger, the groove being behind the apex. The deuterocone is well developed and 

 is opposite the tritocone. A. ridge extends from its apex and along the inner side of 

 the protocone to the anterior angle of the tooth. There are traces of a, cingulum in 

 the anterior and posterior faces of the deuterocone, and at the posterior outer base a 

 small hint of a tetartocone. 



P 4 is nearly an equilateral triangle in cross section with a rounded interior angle, 

 as the deuterocone is conical. The separation of the protocone and tritocone has pro- 

 gressed farther than in P 3 ; the two are more nearly equal. This is apparent from 



*The posterior half of M- 3 - is injured, and it is reckoned as the same length as the anterior part. 



