93 



a symphyseal suture. Olfactory organ rudimentary or absent; the nasal 

 bones appressed on the frontals and overlapped distally by the meseth- 

 moid. 



DENTICETE. 



B. Teeth absorbed and disappearing before birth. Upper jaw provided 

 with plates of baleen. Supraniaxillary not expanded backwards over 

 the frontal bones, but produced outwards in front of the orbits. Kami 

 of lower jaw connected by fibrous tissue, and not by suture. Olfactory 

 organ distinctly developed; the nasal bones projecting forwards, and 

 not overlapped at their distal ends. 



MYSTICETE. 

 ZEUGLODONTIA. 



FAMILIES. 



I. Parietal, frontal, and especially nasal bones elongated. Anterior nares 



open forwards. (Cope.) 



BASILOSAUBIDAE. (LXIV.) 



II. Parietal, frontal, and especially nasal bones abbreviated. Anterior nares 



open far behind. (Cope.) 



CYNOKCLDAE. (LXV.) 



LXIV. BASILOSAURIDAE. 



Extinct genera. 



Basilosaurus Ha,T\.Zeuglodon Owen=Polyptychodon Emmons=Hydrarchos Koch. 

 Durodon Gibloes=Ponto genus Leidy. 



LXV. CYNOKCIDAE. 



Extinct genera. 



(Fide Copei.) 



Portheodon Cope. 



Sgualodon Gr3,t.=Colophonodon Leidy, Cope, 1867. 



Cynorca Cope. 



Delphinodon ~Leidy=Squalodon Cope, 1867. 



Genera? incertae sedis. 



Stenodon Van Ben. 

 Sanrocetus Gribbes. 



DENTICETE. 



FAMILIES. 



I. Rostrum of skull moderately prolonged, and terminating in a rounded or 

 subaugulated apex. 



A. Head (generally) rostrated and attenuated, or ledge-like around the 

 margin. Skull with the vertex produced forwards. Supraoccipital not 

 projecting forwards laterally above the temporal fossae. Frontals visible 



