CORESODON 127 
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 
Proadinotherium, 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. 
Fig. 83. Molars 1 to 3—natural size 
MEASUREMENTS 
Upper dentition, molar 1, length 19 mm. @ Ameghino. 
Upper dentition, molar 1, width 12 mm. @ Ameghino. 
Upper dentition, m. I to m. 3, length 52 mm. @ Ameghino. 
Lower dentition, premolar 2, length 13 mm. @ Ameghino. 
Lower dentition, premolar 3, length 13 mm. @ Ameghino. 
Lower dentition, premolar 4, length 17 mm. @ Ameghino. 
Lower dentition, molar 1, length 18 mm., width 7 mm. 
Lower dentition, molar 2, length 19 mm., width 7 mm. 
Lower dentition, molar 3, length 20 mm., width 7 mm. 
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 
