216 THE MAMMALIA. 



out that the races from the Quaternary period of 

 Upper Italy, classed together as Equus stenonis, 

 include all the required intermediate stages between 

 Hipparion and our present Equus caballus. It is 

 of the utmost interest to be able to prove that in 

 Equus stenonis the reduction of the side meta- 

 tarsals preceded that of the tarsals : for while the 

 metatarsals do not differ from those of our present 

 horse, the tarsals show all the intermediate stages 

 between Hipparion and Equus caballus ; they have 

 not yet had a sufficient length of time to accom- 

 plish the complete change which renders the foot 

 of our horse so eminently more suited to the 

 activity of the one-hoofed animal than was the 

 Equus stenonis. In fact, it may be affirmed that 

 in the case of the Diluvial horses, the splint bone 

 (i.e. the rudiments of the metatarsals n and iv) 

 had not yet coalesced with the mid-foot, which 

 coalescing of the bones occurs in our present horse 

 with its seventh or eighth year. 1 



1 Nehring remarks, on the other hand, that in our present 

 horse, the splint bones do not coalesce nearly as often as is sup- 

 posed, and that, for instance, among the skeletons in the Berlin 

 collection, the coalescing is the exception, the non-coalescing the 

 rule. That, therefore, the supposed difference between the Dilu- 

 vial and the present horse is not an essential one, and that it 

 need only be admitted that the coalescing of the splint bones 

 occurs more frequently in the domestic horses of the present 



