NO. 8 INTERRELATIONSHIPS OF THE CETACEA WINGE II 



Platanistidae, 



Pontistes, Pontoporia, Lipotcs, Inia, 

 Saurodelphis, Platanista. 

 h. Temporal fossa relatively small, covered 

 anteriorly by the widened frontal and 

 maxillary; zygomatic process of the 

 squamosal reduced, losing its primitive 

 form, 

 a. Occipital wall not especially elevated. 

 Delphinidae. 



Delphinodon, Champsodelphis, 

 S chizodelphis , Heterodelphis, 

 Enrhinodclpliis, Argyrocetus, 

 Deiphinapterus, M o n o d o n, 

 Steno, Prodelphinus, Delphi- 

 nus, Tursiops, Tiirsio, Lageno- 

 rhynchus, Orca, O r c ella , 

 " Grampus," Pseudorca, Globi- 

 ccps, Phoccena, Neomeris. 

 p. Occipital wall highly elevated. 

 Physeteridae. 



XiPHiiNi: Argyrodelphis, Meso- 

 plodon, Xiphirostruni, Chonoxi- 

 phius, Xiphius, " Berard'ms," 

 Hyperoodon. 

 Physeterini : Hoplocetus, PJiy- 

 seterula, " Cogia," Physeter. 



In the form of a genealogical tree [see pp. 45-46] : 



Physeteridcc. 



1 . 

 Delphinidcc. 



I. . 

 PlatanistidcB. 



I 

 Squalodontid^. 



1 

 BalcBnidce. 



Zenglodontidcc. 



Zeuglodontidae [Basilosauridas]. — Of all known cetacea the 

 Eocene Egyptian Protocetus of the family Zeuglodontidce is the most 

 primitive. It is known from a rather complete skull without the 



