ipoi.] Gidley, The North American Species of Equus. 133 



of its size from the Niobrara locality. It shows the comparatively 

 short muzzle and the characters in general pointed out by Cope 

 in his description of E. i?itermedii/s. This specimen represents 

 a young animal with the last molar only just coming into full use, 

 hence the differences in this region compared with Cope's 

 figures. Several symphyses mandibuli containing the incisors, 

 as well as the lower jaw belonging with the specimen above 

 figured show the absence or extensive interruption of the internal 

 wall of the external incisor. Three occiputs in this collection also 

 show the characters pointed out by Cope for his E. intermedins, 

 and agree very well with the measurements given. A series 

 of teeth in a portion of the maxillary (Fig. 22) and two fragments 

 of lower jaws (Nos. 10600, 10601, Coll. Am, Mus.), besides 

 a few single teeth, represent this species from the Tule Canon 

 and Rock Creek, Texas, locality. Leidy reported and figured 

 some teeth from Hardin Co., Texas, which he referred to this 

 species. These teeth, now in the American Museum (Nos. 8617- 

 8618), do not differ in any way from the corresponding teeth 

 in the specimens from the Staked Plains and Nebraska. 



(22) Equus pectinatus {^Cope). 



Type Locality. — Port Kennedy, Penn. 

 Horizon. — Megalonyx Beds. (Cave deposits). 



Type. — Nine superior molars and premolars probably belonging to one in- 

 dividual. 



Author's description. — In describing some Equus teeth from Port Kennedy, 

 which he considered as represending two varieties of E. fratermis, Cope gave 

 the following as distinguishing characters : " The superior molar teeth all agree 

 in the fact that the antero-posterior diameter of the protocone enters the same 

 diameter of the entire crown from two and a third to nearly three times. . . . 

 In other Plistocene horses of North America, the antero-posterior diameter of 

 the protocone is from one-half to three-fifths that of the entire crown, excepting 

 in the premolars of Equus occidentalis Leidy, and in the large E. crenidens 

 Cope. . . . One of the individuals differs from the other in the greater 

 complexity of the enamel plates, especially on the opposed faces of the external 

 lakes, agreeing in this respect with Equus coiiiplicatus of Leidy. . . . The 

 superior molars displaying moderate complexity are of smaller size than the 

 complex ones. . . . Under the circumstances it is necessary to distinguish 

 two races of Equus fratemus as already indicated : E. p. fratcriius and E. p. 

 pectinatus, which may prove to be distinct species." 



