70 



THE QUARTERLY REVIEW OF BIOLOGY 



•rn\ 



iS". or. pr^ 



^■Zyg* 



Pontistes rectifrons 



S.cc. 



Stenodelphis blainvillei 



Fig. ii. Dorsal Views of Skulls 

 Pontistes rectifrons, Lower Pliocene, Parana, Argentine Republic. Stenodelphis blainvillei, Mar de la Plata, 

 Argentine Republic. 



