Peterson : Miocene Beds of Nebraska and Wyoming. 67 



No. 1337. No. 1411. 



mm. mm. 



Transverse diameter of P ¥ 10 11 



Antero-posterior diameter of M T 13 15 



Transverse diameter of M T 12 12 



Antero-posterior diameter of M2 17 20 



Transverse diameter of M^ 13 15 



Antero-posterior diameter of M3 29 34 



Transverse diameter of Mg 14 15 



Merychyus minimus subsp. nov. 



This subspecies is based on a series of fifteen individuals from the 

 Upper Harrison beds in Sioux County, Nebraska, now in the collection 

 of the Carnegie Museum. Of this series No. 1466 is selected as the type. 

 It consists of the skull, lower jaws, fragments of vertebrae, limbs, and 

 a fore foot. The remains are all smaller than the type of M. lepto- 

 rhynchus Cope which is the next largest variety, or subspecies. Besides 

 the smaller size there are other slight differences which are quite con- 

 stant and which distinguish it from the larger species, viz. : the 

 slightly more advanced position of the infraorbital foramen, the rela- 

 tively shorter sagittal crest, the shorter symphysis and the shallower 



Fig. 16. Merychyus minimus Peterson. View of right side of skull, 

 Type, No. 1466. 



nat. size. 



horizontal ramus of the lower jaw. The second and third upper pre- 

 molars are more complicated than in Merychyus leptorhynchus, but this 



