76 Douglass — New Species of Merycochwrus in Montana. 



same size and shape, but is farther back. The jaw is much 

 deeper and not straight on the lower border back of the chin. 

 It is broken in the region of the incisors, canine and second 

 premolar, but the nearness of the first and third premolars and 

 the position of the lower part of the alveolus of the outside 

 root between these two teeth show that pm2 was probably 

 small and closely crowded between them as in M. compres- 

 sidens, to be described later. 



On account of the thickness of the ramus and the narrow- 

 ness laterally of the incisive region there is little curving 

 inward of the inner part posterior to the symphysis. 



Merycochoerus madisonius, n. sp. x -J. 



A low ridge or broad convexity begins just back of pm l r 

 sweeps downward and backward just above the foramen men- 

 tale to near the lower border of the ramus under m 1, then 

 becoming a broad convexity sloping gently laterally it sweeps 

 upward and backward towards the position formerly occupied 

 by the last lobe of m 3. It was evidently continuous with the 

 ridge forming the outer anterior border of the ascending 

 ramus. 



A cross-section of pm 1 a little below the alveolar border is 

 rather irregular. Its transverse is much greater than its antero- 

 posterior diameter, the measurements being about 1*5 and -95 cm 

 respectively. The enamel lakes have entirely disappeared in 

 ms 1 and 2. In m 1 the enamel is nearly worn away on the 

 outside. There is only *4 cm left. On m 8, l*25 cm of the crown 

 remains, and on the anterior lobe of m 3, 2 cm . The outer lobes of 

 m% are united as if by a swelling, from each growing together, 

 thus filling up the low T er part of the space between them. On 

 the last lobe of m 2 and the first of m 1, the anterior and pos- 

 terior faces are concave, making the outer lobes contracted in 

 the middle. 



