194 Bulletin A)iier{can Miiseiint of A^atural History. [Vol. X, 



Fig. i8. Comparative view of Crania <if .*J , Paiitolambda bathmodon, 

 small, of B, Coryphodon ivoriiiiani, intermediate, of C, Coryf>hodnn testis, 

 large, showing flattening of the upper surface of the cranium, and appear- 

 ance of parietal horns, Pa.H. All one-fifth natural size. 



Disregarding synonyms and partially known 

 types, these characters, together with the form of 

 the canines, indicate three series, or lines of spe- 

 cies, typified as follows : 



