CORESODON 



127 



Fig. 83. Molars i to 3 natural size 



enamel. All these features seem to me to be the results 

 of wear. 



While the pattern of the upper molars is the same as in 

 Proadinothcritim, these teeth are about as wide as they are 



long. The lower molars, 

 however, are more com- 

 pressed, with the ante- 

 rior crescent occupying 

 about a third of the tooth, and having in the early stages a 

 deep pit, which disappears when the tooth is worn down. 

 In the middle of the basin of the posterior crescent is a 

 large pillar, and between this and the median horn of the 

 crescent is a tiny septum, which early unites with the pillar, 

 leaving a tiny pit (3) which soon disappears entirely. In 

 fact, in an old tooth, the second and fourth bays, having 

 become pits, may even be lost also. 



MEASUREMENTS 



Upper dentition, molar I, length 



Upper dentition, molar i, width 



Upper dentition, m. i to m. 3, length 



Lower dentition, premolar 2, length 



Lower dentition, premolar 3, length 



Lower dentition, premolar 4, length 



Lower dentition, molar I, length 18 mm., width 



Lower dentition, molar 2, length 19 mm., width 



Lower dentition, molar 3, length 20 mm., width 



Interhippus Ameghino 



Interhippus Amegh., 1904, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 3, p. 183. 

 Interhippus Amegh., 1904, Anal. Soc. Cienc. Argen., t. 56, p. 34 of reprint. 



This genus was established on isolated teeth which closely 

 resemble those of this family, though the genus was placed 

 among the Rhynchippidae by Ameghino. The teeth de- 

 scribed as molars are much elongated and have the cristae 

 greatly developed, and in one species there is a style rising 

 about the middle of the inner side of the molar. Another 

 feature emphasized as characteristic of this and the next 



