MUSEUM OF COMPARATIVE ZOOLOGY. 

 Fig. 1.* Fig. 2.t 



57 



head in the younger (Figs. 1 and 4), there is left a radical difference in 

 the general form of the two skulls, which must have increased as the 

 younger animal advanced in years. In length the two skulls vary only about 

 a tenth of an inch; the younger, however, is considerably the narrower and 

 much deeper, especially posteriorly, while its facial angle is much less. 

 The direction of the latero-occipital crests, the form and projection of 

 the occipital condyles, and especially their situation relative to the par- 

 occipital processes, are exceedingly different in the two skulls, as clearly 

 shown in Figs. 3 and 4, — as different as might be expected to occur in 



Fig. 3.J 



* Fig. 1, anterior portion of trie skull of No. 2920 (left side), showing the form of tho 

 nasals the zygomatic and postorbital processes, and the posterior outline of the inter- 

 maxillaries, soon from above. 



t Fig. 2, same of No. 2921. t Fig. 3, skull of No. 2921, seen in profile. 



