62 



D'Orbigny, serving 

 Delphinina. 



to connect the Platanistina with the 



A. Maxillary 

 bones sub-hori- 

 zontal and plane 



B. Maxillary 

 bones at their 

 base rising ver- 

 tically on their 

 edge. 



Delphinina. 



monocerotina. 

 Hyperoodontina. 



Catodontina. 



Platanistina. 



Teeth in both jaws. 



No teeth in under jaw. 



Noteeth in upper jaw. Under 

 jaw with short symphysis. 



No teeth in upper jaw. Under 

 jaw with long symphysis. Nos- 

 trils very unequal in size. 



Teeth in both jaws. Under 

 jaw with long symphysis. 



Of the many characters which I have before given as 

 separating the sperm whale tribe from other dolphins, it is 

 rather singular that Mr. Gray should not have noticed one. 

 The definition given by him of his family of Caiodontidce or 

 toothed whales, is as follows : — "Head large, upper jaw 

 toothless, lower jaw with conical teeth fitting into cavities 

 in the edge of upper jaw. Blowers united together by a 

 lunate opening." 



Now in the first place no sperm whales have cavities in the 

 edge of upper jaw, while there are dolphins in possession of 

 every one of Mr. Gray's other characters. The assertion of 

 Mr. Bennet that rudiments of teeth are to be found in the 

 upper jaw of young sperm whales, may be doubted; but Mr. 

 Gray himself has stated that the genus Physeter or blaclc-fish, 

 which he makes to belong to the group, has the blowholes 

 separated The least objectionable part of the above 

 definition consists perhaps in the vague words " head 

 large," and yet Mr. Gray assigns his genus Kogia to 

 the family Avith the contrary character of "head moderate." 

 No doubt the large size of the head in proportion 

 to the body is a very striking characteristic of the genera Ca- 

 todon and Phijseter ; but this is not particularly remarkable in 

 EupJiysetes, which has a head in external form very like to that 

 of some dolphins, and not in proportion larger. 



* Is this correct ? 



