93 



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

 bones appressed on the froutals and overlapped distally by the tneseth- 

 moid. 



DENTICETE. 



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

 with plates of baleen. Suprarnaxillary not expanded backwards over 

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

 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.) 



BASILOSATTRIDAE. (LXIV.) 



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



open far behind. (Cope.) 



CYNOBCIDAE. (LXV.) 



LXIV. BASILOSATTRIDAE. 



Extinct genera. 



Basilosaurus Ha,T\.=iZeuglodon Oweu=Polyptychodon Emmou&=nydrarchos Koch. 

 Durodon Gibbes=Pono genus Leidy. 



LXV. CYNORCIDAE. 



Extinct genera. 

 (Fide Copei.) 



Portheodon Cope. 



Squalodon Gra.t.=^Colophonodon Leidy, Cope, 1867. 



Cynorca Cope. 



Delphinodon Le.id.y=Squalodon Cope, 1867. 



Genera? incertae sedis. 

 Stenodon Van Ben. 

 Saurocetus Gibbes. 



DENTICETE. 

 FAMILIES. 



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

 subaugulaled apex. 



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

 margin. Skull with the vertex produced forwards. Supraoecipital not 

 projecting forwards laterally above the temporal fossse. Frontals visible 



