124 BiiUeiin American Museum of Natural History. [Vol. XlV, 



long diameter is considerably less than half that of the crown. A peculiarity 

 found in two of the superior molars, but not in two others, is that the median 

 dental connection between the external and median crescents is interrupted by 

 the continuity of the enamel plates bordering the lakes from the one to the 

 other. This arrangement is frequently seen in the large pm^, in the species of 

 Equus, but does not occur in the other premolars and molars. It is a reversion 

 to the condition seen in Anchitheriiim. A principal character of the species is 

 seen in the extreme simplicity of the enamel borders of the lakes." 

 Measurements not given. 



This species was founded upon exceedingly doubtful characters, 

 all the characters given in the above description being apparently 

 due to the little-worn condition of the tooth. (See Fig. 2, 

 C, Z), and discussed p. 95.) However, the validity of the spe- 

 cies is somewhat strengthened by Cope's description and figures 

 of additional specimens from the same locality,^ and from the fact 

 that it seems to be the only large horse so far discovered in this 

 geological horizon. 



It seems exceedingly doubtful, however, whether this species 

 can be properly placed in the genus Equus. Cope did not point 



out or suggest any characters that 

 mark it as belonging to this genus, 

 nor are there any such characters 

 shown in any of his figures. On the 

 contrary, there are in his descriptions 

 and figures, and also in three teeth 

 collected by the writer from the same 

 locality (No. 10624, Am. Mus. Nat. 

 ^:^k^!^^Snci^n:c^. Hist. Collec.) and probably belong- 



Supenor premolar. (After Cope.) J^^g ^^ ^i^^ g^j^g specicS, SCVCral 



indications of primitive characters 

 linking this species much more closely with Fliohippus, as this 

 genus is understood, than with Equus. The character of the 

 very small protocone and the tendency to a sharp entrant- 

 angular groove between the metaconid and metastylid columns, 

 a distinguishing character given by Cope ' for the lower teeth, are 

 both like the Loup Fork genera and unlike any of the Pleistocene 

 or recent species of Equus. Besides these characters the x\meri- 

 can Museum specimens show other characters which seem 



' Report Geol. Surv. Texas, 1893, p. 66. 



