56 



THE QUARTERLY REVIEW OF BIOLOGY 



Max. 

 hchyrorhynchus vanbenedeni 



S.oc. £ 



Inia gtoffrensis 



Fig. 7. Dorsal Views of Skulls 

 hchyrorhynchus vanbenedeni, Lower Pliocene, Parana, Argentine Republic. Inia gcoffrensis, Santarem, Brazil 



marking the position of the apices of the closely approximated, with acute conical 

 upper teeth when the jaws are shut. The crowns covered with rugose enamel, 

 teeth are large, compressed, and not Between the base of the crown and the 



