190 1.] Gidley, The North American Species of Equiis. 139 



small horse with teeth scarcely as large as those of the Mexi- 

 can donkey and of very complex pattern. 

 E. COMPLICATUS. — West Southern and middle Western States; 

 embraces as synonyms, E. intcrmedius, E eons and probably 

 E. excelsus (which is now indeterminate). Now well charac- 

 terized, representing a species with teeth about the size of 

 those of the ordinary draught horse and of moderately com- 

 plex pattern, but with the bones of the skeleton about the size 

 of those of the smaller varieties of the western pony. The 

 species is especially characterized by its short muzzle, in this 

 respect resembling the ass. 

 E. excelsus. — Nebraska. Very imperfectly known from the teeth 

 only ; although now indeterminate, may prove to be a valid 

 species. 

 E. occiDENTALis. — California or Pacific slope. Other species 

 and specimens have been mistakenly referred to this type. 

 The characters other than those of the teeth are not now 

 known, but these indicate a horse about the size of E. coiii- 

 plicatus with uniformly simple patterned teeth. 

 E. PACiFicus. — A large Oregon species, although middle Cali- 

 fornia is the type locality. A well characterized species. 

 With the exception of E. gigcuitcus from southwestern Texas, 

 the largest American horse. The skeleton indicates a horse 

 about the size of the ordinary draught horse, but the skull is 

 proportionately larger. 

 E. CONVERSIDENS. Valley of Mexico. Apparently well estab- 

 lished; of medium size. 

 E. TAU. — Valley of New Mexico, the smallest true horse known 

 in America. This embraces the E. barcencei as a synonym. 

 E. crefiidens. — Valley of Mexico; indeterminate. 

 E. SEMiPLiCATUS. — Western Texas, from the Sheridan beds of 

 Paloduro Canon, probably a valid species. The great pos- 

 terior extension of the vomer over the presphenoid, together 

 with its size and the proportions of the teeth, seem to show 

 . a close relationship to E. asinus. 

 E. PECTiNATUS. — Port Kennedy Bone Cave of eastern Pennsyl- 

 vania. Probably a valid species. 

 E. scoTTi, — Staked Plains of Texas, Tule Canon. Intermediate 

 in size between E. complicatus and E. pacificus. A long-faced 

 type of horse. This species represents a horse about the 



