I go I.] Gidley, The North Atnerican Species of Equus. 131 



transverse crest connects the paroccipital processes and the basisphenoid, bound- 

 ing the precondylar fossa in front, so as to convert it into a basin. 

 The E. interniedius is a shorter-nosed species than the E. caballus, the distance 

 from the anterior lower premolar forwards only equalling the corresponding 

 length in the quagga, while the parts are in other respects as large as those of 

 the domestic horse." 



Measurements given for the teeth. 



iro-posterior 



isverse 31 



T^. ^ c •> \ Antero-posterior 30 mm. 



Diameters of P"^ -j 



( Trans 



T-s. , c ^ (Antero-posterior 25 " 



Diameters or ml -! '^ •' 



\ Transverse 30 " 



T-,- ^ r ,( Antero-posterior 36 " 



Diameters of m- \ 



( Transverse 29 ' ' 



Length of mandible from pm^ to external border of in- 

 cisors.... 130 " 



Measttreinenls of occipital condyles. 



Transverse diameter g2 " 



Antero-posterior diameter above 50 " 



The specimens upon which Cope founded this species, as above 

 mentioned (see E. coinplicatus^ page no), were considered by him 

 identical with a certain other lot of specimens from the same 

 locality which had been referred by Leidy to E. major {E. com- 

 plicatus).,^ but which he thought could not be identified with that 

 species; separating them on the ground of the less complexity of 

 the enamel folding in these teeth than in those of E. complicatus. 



One of the specimens, at least, figured by Leidy in the work 

 above cited is more complicated in tooth pattern than is indi- 

 cated by the figure of his type specimen of E. complicatus, and 

 the specimens described by Cope seem not to differ at all in this 

 respect from the E. complicatus type. But even if this lot of teeth 

 described by Cope are somewhat simpler, a character so variable 

 as this one seems hardly sufficient grounds for founding a new 

 species. The specimen figured by Cope (see Cope's figure ^) shows 

 every indication of belonging to an old individual, which would 

 account for much of the simplicity of these teeth. Cope at- 

 tempted no other distinction, nor does there seem to be any. On 

 the other hand there seem to be good reasons for considering 

 the two species as identical. There seems to be no difference 

 in size and practically no difference in tooth pattern; the type 



' Trans. Wagner Free Inst, of Sci., 1889, p. 38. 

 2 Proc. Am. Phil. Soc, 1895, P'- ix, Fig. 8. 



