188-1 ] 1^ [Cope. 



The internal anterior column of the superior molars is longer and flatter 

 than in the specimens of the North American horse, but I do not feel at 

 liberty to propose a new specific name for the Mexican animal. The 

 absence of facial fossa and short diastemata throw it into the series of the 

 asses. From all these the large flat internal column distinguishes it. The 

 presence of the loop at the notch of the internal border in the Mexican 

 specimens distinguish them from Leidy's type and from one of Condon's 

 specimens. A second one of the latter has a small loop at the point in 

 question. The absence of this loop is given by Leidy as characteristic of 

 the E. occidentalis, but only a small proportion of my specimens of that 

 species are without it. 



The Mexican specimens are from Tequixquiac. 



Eqtrus barcen^i Cope, sp. nov. 



Two superior molars represent this species in the Museum iSTacional, and 

 two superior molars in theEscuelades Minas. A skull lacking all in front 

 of the orbits inclusive, in the latter museum, probably belongs to the same 

 species. 



This horse is distinguished from all the others here mentioned or des- 

 cribed by its small size. In the characters of its superior molars it is like 

 the Equus 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 pos- 

 terior 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. 



3Ieasurements. M. 



Diameters of molar No. I \ anteroposterior 0215 



c transverse 0230 



Diameters of molar No. II 



anteroposterior 022 



transverse 022 



From Tequixquiac. 



I have dedicated this species to my distinguished friend ]\Iariano de la 

 Barcena, Professor of Geology in the National Museum and Director of 

 the Meteorological Observatory of the City of Mexico. 



PLATYGONUS Leconte. 

 Platygonus ? coMPRESstrs Leconte. 



A portion of the mandibular ramus of a species of peccary, apparently 

 the above, was found at Tequixquiac, and is preserved in the museum of 

 the College of Guanajuato. Dr. Alfredo Duges, the distinguished pro- 

 fessor in the college, called my attention to the specimen, and gave me' a 

 cast of it. Its dimensions are similar to those of North American indi- 

 viduals, as follows ; 



Measure?nents. M. 



Diameters of M. i | anteroposterior 0145 



t- transverse 012 



