NO. 8 INTERRELATIONSHIPS OF THE CETACEA WINGE II 



Platanistidae. 



Pontistes, Pontoporia, Lipotcs, Inia, 

 Saurodelphis, Platanista. 

 b. 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, 

 Schisodelphis, Hetcrodelphis, 

 Enrhinodelphis, Argyrocctus, 

 Delphinapterus, M o n o d o n, 

 Steno, Prodelphinus, Delphi- 

 nus, Tursiops, Tnrsio, Lagcno- 

 rhynchus, Orca, O r c ell a , 

 " Grampus," Pscndorca, Globi- 

 ceps, Phoccena, N comer is. 

 p. Occipital wall highly elevated. 

 Physeteridae. 



XiPHiiNi : Argyrodelphis, Meso- 

 plodon, Xiphirostrum, Chonoxi- 

 phiiis, Xiphkis, " Berardius," 

 Hyperoodon. 

 Physeterini : Hoplocetus, Phy- 

 seterula, " Cogia," Physeter. 



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



Physeteridcc. 



1 . 

 DelpJiinidcc. 



Platanistidce. 



Squalodontidce. 



BalcBnidce. 



ZeuglodontidcB. 



Zeuglodontidae [Basilosauridse]. — Of all known cetacea the 

 Eocene Egyptian Protocetus of the family Zeiiglodontidm is the most 

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



