no. 2086. SOME MAMMALS OF THE PLEISTOCENE— HAY. 529 



On comparing the above measurements it is seen that the horse 

 here called Equus hatcheri had a longer skull than that of E. nio- 

 brarensis, one of the same length as that of the larger domestic 

 horses. In Nehring's list of 60 specimens of equines measured there 

 are only 7 which had longer skulls than that here described. It 

 belongs, then, among the very large horses. 



The width of the skull at the rear of the orbits is 236 mm. This 

 does not appear to have been exaggerated in repairing the specimen. 

 This width is equal to 42.6 per cent of the basilar length, so that this 

 quantity represents the cephalic index. Nehring obtains this index 

 in the reverse way, following which the cephalic index would be 

 234.9. This horse would then fall into Nehring's group of broad- 

 faced horses, but, in Tscherski's classification, in the group with faces 

 of medium breadth. As will be seen by referring to a table on a more 

 advanced page, the skull of E. hatcheri has nearly the same cephalic 

 index as the Przevalsky horse. The latter is, however, a smaller 

 animal. E. niobrarensis, as indicated by the type, had a relatively 

 broader skull, the index being 45.3 ; or, after Nehring's method, 220.8. 

 It belongs, then, among those with the very broadest faces, resembling 

 in this respect the kiang. Whether or not additional specimens of 

 both E. hatcheri and E. niobrarensis would sustain our conclusions 

 only future investigations will decide. 



The cranial length is 195 mm. ; that is, the distance from the middle 

 of the occipital crest to the middle of the line joining the rear of the 

 orbits. The cranio-cephalic index is determined, then, to be equal 

 to 35.3, being, therefore, more nearly equal to that of the broad-faced 

 domestic horses than to that of the narrow-faced ones. In E. nio- 

 brarensis the index is 34.3. 



The facial length (distance from incisive border to the middle of 

 the line joining the rear of the orbits) is 413 mm. This multiplied 

 by 100 and divided by the basilar length gives as the f acio-cephalic 

 index 74.8. That of the type of E. niobrarensis has been determined 

 to be 75.3. The horse which is here described is therefore relatively 

 short-faced, as well as broad-faced. 



The length of the nose is relatively greater than in the domestic 

 horse No. 843, but nearly the same as in the type of E. niobrarensis. 



There appears to be a considerable difference between the horse 

 here described and the type of E. niobrarensis in the width of tKe 

 face on the maxillary ridge. There is a possibility of some distortion 

 in the specimens, but the differences appear to have existed in life. 

 In E. hatcheri this width equals 38 per cent of the basilar length ; in 

 E. niobrarensis, 35.3 per cent ; in the E. caballus measured only 34.2 

 per cent. 



59758°— Proc.N.M.vol.48— 14 34 



