190 1.] Gidley, The North American Species of Equus. I 23 



a species much larger than the Mexican specimen which Cope 

 called E. crenidens, or even the large E. pacificus. 



(15) Eg ims bar ce/icBi Co\>t. 



Type Locality. — Valley of Mexico. 



Type. — Two superior molars. 



Author s descriptioji. — "This horse is distinguished from all the others here 

 mentioned or described by its small size. In the characters of its superior 

 molars it is like the Eqiius excelsus. The anterior internal column is flat, and 

 its antero-posterior diameter is five-eighths that of the crown of the tooth. The 

 prism is straight. The lakes have the margin but little looped ; the posterior 

 notch of the anterior lake is trebled or triplex. The grinding face of the crown 

 of the third superior molar is a little longer than the others." 



Measuretnen ts . 



„. ^ r 1 T^T ( Antero-posterior 21.5 mm. 



Diameters of molar No. i. -( ^ 



( Transverse 23 



„. ^ r 1 TvT ( Antero-posterior 22 " 



Diameters of molar JSo. 2. - ^ 



( Transverse 22 " 



In 1893 ' Cope made this species a synonym of E. tait. It is 

 difficult to make out whether, in doing so, he referred to E. tan 

 Cope (not of Owen),^ which has been shown to be the equivalent 

 of E. cofiversidens, or whether he now regarded E. tait in the light 

 of the original description given by Owen. It seems probable, 

 however, that the latter view is the correct one, as in this connec- 

 tion he referred to Owen's description of E. tau and not to his 

 own. Taking into account the fact that the transverse diameters 

 of the teeth of E. barcencei given by Cope probably include the 

 cement, there seems to be no distinction between this species and 

 E. tau Owen, and therefore it may be considered, as Cope has 

 already placed it, a synonym of this species. 



(16) Pliohippus simplicidens Cope. 



Equus simplicidens Cope. 



Type Locality. — Mt. Blanco, Texas. 



Horizon. — Blanco Beds (Upper Pliocene). 



Type. — Superior molar. 



AuiJwr's description. — " The size of the teeth is about that of the E. occiden- 

 talis and E. caballus. The internal column is of moderate antero-posterior ex- 

 tent, its posterior border marking the anterior third of the posterior lake. Its 



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

 - Proc. Am. Phil. Soc, 1884, p. 12. 



