F. B. Loomis — New Horse from the Lower Miocene. 163 



Art. XX. — A Netv Horse from the Lower Miocene; by 



F. B. Loomis. 



Weile the series of fossils, which show us the development 

 and radial adaptations of the horse family, is already a large 

 one, there still remain breaks and places where more material 

 is desired. Such an unfilled gap exists between the rich Oligo- 

 cene Mesohippus fauna and the upper Miocene Protohippus 

 group, just where the transition from the brachydont unce- 

 ruented teeth to the hypsodont cemented ones occurs. The 

 finding by Peterson* of the excellent type of Parahippus 

 nebraskensis in the Upper Harrison beds of Nebraska, closed 

 in a part of this gap, and for two or three seasons fragments 



Fig. 1. — Crown views of the upper and lower dentition of the type of 

 Parahippus tyleri. One-half natural size. 



have raised the expectation of a Lower Harrison horse. Dur- 

 ing the season of 1907, under the guidance of Mr. Harold 

 Cook, the Amherst '96 expedition found a prospect, which 

 proved to be the major part- of the skull of this much desired 

 type. While the brain case is wanting, a nearly perfect upper 

 and lower dentition of an adult individual is preserved, show- 

 ing an animal closely related to P. nebraskensis, but about 

 a fourth smaller. The following specific description will point 

 out the affinities and characters of the new species. 



Parahippus tyleri sp. no v. 



Type, a skull numbered 1079 in the Amherst College 

 Museum, which while lacking the brain case preserves all the 

 dentition except the upper canine and the first premolar of the 

 * Ann. Carnegie Museum, vol. iv, p. 57, 1906. 



