28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J2 



opposite side. On the other hand the posterior margin of the depres- 

 sion is not particularly highly elevated. The eye is atrophied ; touch 

 more than vision probably guides in the capture of prey. The hand's 

 unusually broad, rounded-ofif outline, with the especially short, uni- 

 form, well-developed and wide apart fingers, might appear more 

 primitive than in other members of the family ; but possibly it may 

 be the story of a partial reversal from an earlier more flipper-like 

 condition. 



Platanistidae," 



I. Upper toothrows well separated throughout. Maxillary with 

 longitudinal crest not excessively large. 



A. All the teeth with terete or scarcely compressed root. 



1. Longitudinal crest on maxillary relatively low. Frontal 



behind nasal only a little elevated. 



a. Palate relatively broad. About 40 teeth in each 



jaw. 

 Pontistes. 



b. Palate relatively narrow. About 55 teeth in each 



jaw. 

 Pontoporia [Stcnodclphis] . 



2. Longitudinal crest on maxillary relatively high. 



Frontal behind nasal rather strongly elevated, 

 a. Teeth relatively slender. 



Lipotes. 

 h. Teeth relatively robust. 



Inia. 



B. Teeth with compressed root ; in some of the anterior teeth 



the cross-section of the root is almost 8-shaped. 

 Saurodelphis. 

 n. Upper toothrows placed close together, especially behind, so 

 that teeth from the right and left sides may be pushed in 

 among each other. Maxillary with longitudinal crest 

 excessively large, completely covering over the face. 

 Platanista. 



Delphinidae. — The most important character — perhaps in the 

 beginning the only one— which has separated the Delphinids from 

 the most primitive Platanistids from which they sprang is the widen- 

 ing out of the facial depression. This broadens posteriorly to such 

 an extent that its floor wholly covers over the temporal fossa like a 

 roof formed by the frontal and maxillary together. A second 



