44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 72 



XiPHII. 



a. Intermaxillaries not or scarcely forming a 



cup-shaped depression around nares. 

 a. Intermaxillaries not covering mes- 

 ethmoid in front. 

 Mesoplodon. 

 (B. Intermaxillaries mutually in contact, 

 covering mesethmoid in front, 

 (i) No pit formation around nares. 



Xiphirostrum. 

 (2) Indication of pit formation 

 around nares. 

 Chonoxiphius. 



b. Intermaxillaries with an elevated outer 



margin forming a deep cup around 

 nares. 

 Xiphius. 

 2. Longitudinal crest on maxillary above and in 

 front of orbit well developed, swollen. 



HyPEROODO NTES . 



a. Longitudinal crest on maxillary relatively 

 weak. 

 " Berardius." 

 p. Longitudinal crest on maxillary huge. 

 Hypcroodon. 

 II. Occipital wall spreading itself, highly elevated, across entire 

 braincase, and pushed far back behind nares. 

 Physeterini. 



A. Upper toothrow well developed. 



HOPLOCETI. 



1 . Teeth with enamel. 



Hoplocetus. 



2. Teeth without enamel. 



Physcterida. 



B. Upper toothrow atrophied. 



Physeteres. 



1. Distinct remains of the longitudinal crest 



that originally extended from the nares 

 to the occipital crest. 

 " Cogia." 



2. Longitudinal crest behind nares wholly 



flattened out, obliterated. 

 Physeter. 



