350 S. CALVIN AFTONIAN MAMMALIAN FAUNA 



meters in transverse diameter at the proximal end, 41 millimeters broad 

 at the narrowest part of the shaft, and 51 millimeters at the distal end. 

 A slenderer phalanx, that of an immature individual, is 87 millimeters 

 long and the narrow shaft is 33 millimeters wide. An examination of 

 the equine bones from the Aftonian gravels, entirely apart from the evi- 

 dence furnished by the teeth, suggests the possibility of at least two 

 Aftonian species, one somewhat smaller than the average horse of today, 

 the other fully equaling the modern horse in size. 



The teeth of the Gladwin horse, teeth 116 and 117, shown on plate 18, 

 figures 1 and 2, and the other teeth above referred to Equus scotti Gidley 

 are all notably larger than those of Equus cab alius, while the teeth re- 

 ferred to Equus complicatus are about the size of the teeth of the domestic 

 horse. According to Gidley, in the article from the American Museum 

 Bulletin, volume xiv, frequently quoted in this paper, the head and the 

 teeth of the Pleistocene horses were proportionately larger than in the 

 modern species. On page 139 of the bulletin Equus complicatus is de- 

 scribed as "a species with teeth about the size of those of the ordinary 

 draft horse and of moderately complex pattern, but with the bones of the 

 skeleton about the size of those of the smaller varieties of the western 

 pony." Notwithstanding the large size of the teeth in Equus scotti, it is 

 said that "this species represents a horse about the size of the largest 

 western pony." While in all probability the Aftonian horses represent 

 but two species, Equus complicatus and Equus scotti, the fact should not 

 be overlooked that some of the bones and teeth (figures 2 and 4, plate 18, 

 for example) agree with those of Equus pacificus, concerning which it is 

 stated that "the skeleton indicates a horse about the size of the ordinary 

 draft horse, but the skull is proportionately larger." Many of the fossil 

 bones are about the size of those of the ordinary draft horse. 



Other Ungulates 



Of the ungulates associated with the Aftonian horses, one of the more 

 significant is the camel. This is represented by a single first phalanx 

 which came from the Peyton pit at Pisgah. The bone is shown of nat- 

 ural size in plate 21, figure i, and plate 22, figure ~f. It is 127 milli- I 

 meters long, 36 millimeters /n transverse diameter at the proximal end, / 

 31 millimeters across at the distal end, and the smallest diameter of the 

 shaft is 20 millimeters. Other Artiodactyls are indicated by the antler 

 of a large stag from Denison, Iowa, related to Cervalces americanus, the 

 distal ends of two metapodials, one of which, lacking a part of the articu- 

 lation, is shown full size in plate 22, figure t ; and there are two unidenti- 



