I04 Bulletin American Museum of Natural History. [Vol. XIV, 



hand shows: (i) that the fully developed cup is usually present in 

 E. caballus, though not always, the writer having examined three 

 specimens in which it is entirely wanting (Fig. 6, C)\ (2) in the two 



Fig. 6. Mandibular symphyses. A, E. asiuus .- B, E. scotti : C, E. cahallus. 



jaws of ^. asimis in the Museum collection there is no indication of 

 even a tendency toward cupping of the external incisors; and (3) 

 the fossil species of Equns in which this character can be made out 



