252 DOUGLASS — FOSSIL MAMMALIA 



M. 



Thickness of ramus at M, 004 



Length of P, ° 03 



Width of P, r ; 0021 



Length of M, 0OJ1 



Width of M, 0022 



Length of M 5 0021 



Width of M 2 0022 



Length of M, 0014 



Widtli of M s 0015 



Sciurua jeffersoni, sp. nov. 



Type No. 40. 



This species is larger than S. relictm (('ope, 1883, p. 817, PL LXV, Fig. 35). 

 The teeth do not increase regularly in size backward. The mental foramen is higher 

 and nearer to the incisor. The diastema was shorter. 



In this species the anterior cheek tooth is the smallest and the posterior one the 

 largest, but the two between are nearly equal in size. In all of the teeth the anterior 

 inner tubercle is the higher and larger and the posterior inner one the smaller. The 

 latter does not appear as a separate tubercle on M ¥ , as a continuous wall extends from the 

 anterior inner to the posterior outer one, enclosing the basin internally and posteriorly. 

 A small ridge, which may represent the posterior inner tubercle, extends from the wall 

 backward and inward in the posterior part of the basin. On the anterior three teeth 

 there are minute tubercles between the two internal ones. There arc also minute median 

 tubercles on the outer margins of all the teeth. 



From White River beds, Pipestone creek. 



Measurements. 



M. 



Length of lower molar premolar scries 012 



Length of P ? , ° 036 



Width of Pj 0029 



Width of molars, each 003 



Length of M r 0020 



Length of Mj 003 



Length of Mj 004 



Jiumys minor, sp. nov. 

 The type of this species, No. 37, is part of a right ramus of a mandible from the 

 Pipestone beds on Pipestone creek, in Jefferson county. The anterior part of the incisor 

 is gone and all of the mandible back of the second molar. The two anterior molars are 

 perfect. 



