1 90 1.] Gidley, The North American Species of Equiis. I 2 I 



This species is much the smallest of any described from 

 America. Owen considered it about the size of the common 

 Ass, but it is much smaller than that 

 species, E. cotiversidens and E. asinus 

 being much more nearly of a size 

 (see Table I, p. 98). 



In his paper on ' The Extinct 

 Mammalia of the Valley of Mexico ' * 

 Cope united E. conversidens with E. 

 tau, retaining the latter name. Why 

 he did so, he does not explain, ex- 

 cept that he says, " I could detect 

 no specific differences between the 

 seven or eight specimens I examined." 

 As Cope expressed considerable 

 doubt as to the identity of the type 

 specimens, especially of E. tau, it 

 seems quite probable that the true 

 type of this species was never in his 

 hands, and his description of E. tau 

 was probably based upon specimens 

 that properly belonged to E. conver- 

 sidens. 



There is a superior molar tooth, 

 m-^- (No. 921 1 ), in the collection of 

 the American Museum from Peace 

 River, Florida, which is much too 

 small to be referred to any species 

 reported from the United States. A 

 second tooth from Lookout Moun- 

 tain, Tennessee, recently presented 

 to the American Museum by Mr. E. 

 S. Hallock, agrees almost exactly in 



Fig. 12. Eqittis tau Owen. 



Upper molar-premolar series, lacking 

 size and character with the Florida second premolar, p^. (After Owen.) 



tooth. These two teeth represent a 



very small horse once inhabiting the south-eastern part of the 

 United States, which in point of size did not differ materially from 

 E. tau of the Mexican Valley. Hence as there are no characters 



1 Proc. Am. Phil. Soc, Vol. XXII, 1884, pp. 12, 13. 



