394 Dr. J. C. Ewart. Possible Ancestors of the [May 15, 



in; great part descended from a species closely allied to E. sivalensis, but that 

 horses with a broad flat forehead, and the face short and nearly in a line 

 with the cranium, are at the most only remotely related to E. sivalensis. 

 ■ Further inquiries will probably also show that some Indian breeds as well 

 as some of the unimproved races of Central Asia {e.g., certain long-faced 

 Kirghiz horses with a sloping forehead and long ears) in many of their points 

 agree with E. sivalensis of the Pliocene deposits of Northern India. 



The second possible ancestor mentioned is Equus stenonis of the Pliocene 

 deposits of Europe and North Africa. In a typical specimen of this species, 

 with the teeth in an intermediate state of wear, all the anterior pillars of the 

 premolars and molars are shorter than in E. sivalensis, while in a specimen 

 with the teeth well worn the longest pillar may be only one-third the length 

 of the grinding surface of the crown. At no age are the pillars of the 

 molars more than half the length of the crown. Whether the face was long 

 and tapering and strongly deflected in E. stenonis has not yet been 

 determined, but from the limb bones collected it is evident that the horse 

 with short-pillared molars, which in Pliocene times frequented the valley of 

 the Arno, sometimes reached a height of nearly 15 hands. 



It is generally supposed E. stenonis either became extinct towards the close 

 of the Pliocene age or was modified to form varieties with long-pillared 

 molars. It is conceivable that some of the descendants of E. stenonis 

 acquired long-pillared molars, but it by no means follows that all the 

 Pleistocene horses of Europe with the anterior pillars more than half the 

 length of the crown are related to or derived from E. stenonis — some of them 

 may have been the descendants of E. namadicus. Be this as it may, horses 

 with teeth of the E. stenonis type existed in the south of Scotland during the 

 first and second centuries, and horses with short-pillared cheek teeth are 

 still in existence. In some of the skulls from the Eoman fort at Newstead 

 the anterior pillar of the third and fourth premolars only measures 9 mm., 

 which is only about half the length of the pillar in E. namadicus and other 

 "fossil" Pleiostocene species. Further, in one of the first century Newstead 

 skulls the first premolar is as large as in E. stenonis, and the face (as broad 

 and long as in E. sivalensis) forms an angle of 18° 6' with the cranium. 

 ' -In all probability further inquiries will show that the short-pillared 

 species (with metacarpals as long but somewhat thicker than in E. sivalensis) 

 widely distributed over Europe and North Africa in Pliocene times played 

 an important part in the making of Shires and other heavy modern breeds. 



The only other possible ancestor dealt with in this contribution is the one to 

 which I have given the name Equus gracilis. Owen arrived at the conclusion 

 that Pleistocene horses " had a larger head than the domesticated races," and 



