61 8 Troxell — Vertebrate Fossils of Rock Creek, Texas. 



The cephalic index is : 



E. scotti 38*4 per cent 



Horse 40* to 44 per cent 



Ass 46* to 49 per cent 



An average of the palatocranial angle for nine horses was 

 *22'5°, for two asses it was *20'9°, and for live zebras *2P75°. 

 This angle as found in E. scotti is 20°, considerably less than 

 that of the average zebra or ass and even less than that of the 

 average horse. Due to a slight crushing of the horizontal part 

 of the palate the angle is made even greater than it should be. 



Fig. 4. 





Fig. 4. Limb bones. 1, Equus calobatus, n. sp., hind limb ; 2, E. calo- 

 batus, n. sp., fore limb ; 3, E. scotti, hind limb ; 4, E. scotti. fore limb. 

 One-sixteenth nat. size. 



This angle in E. scotti seems to contradict the statement by 

 Professor Osborn (loc. cit.) that : " In Neohipparion of the 

 Miocene, Hijpparion of the Pliocene and E scotti of the 

 Pleistocene the face is strongly bent down on the cranium." 

 for E. scotti shows less tendency than E. cabalhts toward 

 cytocephaly. 



In the form of the orbits, E. scotti departs widely from the 

 ass and even goes beyond the horse in the horizontal elonga- 

 tion. The orbital indices are : 



E. scotti 69-7 per cent 



Horse *84'2 to 93*5 per cent 



Ass *96-0 to 104-2 per cent 



The horizontal diameter is slightly increased in E scotti because 

 of fracture. 



Note : All measurements indicated thus * are taken from Osborn (15 "85). 



