1 9© I.] Gidley, The North Atnerican Species of Equics. I 25 



to indicate the close relationship of this species to the more primi- 

 tive genera of the Loup Fork. The little outward folding of the 

 enamel at the antero-external border of the protoconid, so gen- 

 erally observed in all the Loup Fork genera, is plainly indicated 

 in the two lower teeth by a well-marked groove. This peculiar 

 fold of enamel, which is entirely wanting in the genus Eqims^ seems 

 to be a primitive character and apparently was derived, in the 

 evolution of the tooth, from the anterior cingulum of the more 

 primitive brachydont tooth in passing to the hypsodont form. 

 Although these teeth are of an old individual and are pretty 

 well worn, they have the appearance of being of a very short- 

 crowned pattern. 



This species is about the size of Pliohippus viirabilis Leidy. 



(17) Hipparion eurystylus {Cope). 



Eqiius etirystylus Cope. 



Type Locality. — Paloduro Canon, Texas. 

 Horizon. — (?) Goodnight Beds. 

 Type. — Lower molar. 



Author s description. — " This species belongs with E. viimitiis Cope, to a 

 section of the genus characterized by the relatively great width of the metaconid- 

 metastylid column of the inferior molars, and its close appression to the proto- 

 conid and hypoconid, and hence by the relatively narrow molar crown ; and 

 also by the small size." (For further description see Report Geological Survey 

 of Texas, 1893, pp. 44, 45.) 



Mcasu rem ents given . 

 I Longitudinal diameter 55 mm. 



Specimen No. 2 (Cope) -I Antero-posterior 

 \ Transverse 

 I Longitudinal 



Specimen No. 5 (Cope) -, Antero-posterior 

 ' Transverse 



24 

 10 

 40 



None of the characters given in Cope's very minute descriptior» 

 of this species, or shown in his figures, prove any relationship to- 

 the genus Eqitus j but they all seemingly show its positive identity 

 with or at least its very close relationship to the three-toed horses 

 of the Loup Fork. 



An examination of the horse teeth from the true Loup Fork 

 Beds (in the American Museum collections) indicates that the 



