62 



A. Maxillary bones sub- 

 horizontal and plane. 



B. Maxillary bones at 

 their base rising ver- -! 

 tically on their edge. 



Delphinixa. 



MONOCEROTINA. 



Hyperoodontina. 



Catodontixa. 



Plataxistixa. 



Teeth in both jaws. 



No teeth in iinder jaw. 



No teeth in upper jaw. 

 Under jaw with short 

 symphysis. 



No teeth in upper jaw. 

 Under jaw with long 

 symphysis. Nostrils 



very unequal in size. 



Teeth in both jaws. Under 

 jaw withlong symphysis. 



0£ the many cliaracters wliicli I liave 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 Gatodontidce 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 

 eclje 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 blackfish, which he makes 

 to belong to the group, has the blow-holes separate* 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 with the contrary character of "head 

 moderate." No doubt the large size of the head in propoi'tion 

 to the body is a very striking characteristic of the genera 

 Catoclon and Physeter ; but this is not particularly remarkable in 

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

 of some dolphins, and not in jiroportion larger. 



Premising that I am in Mr. Gray's and M. Cuvier's case of 

 never having seen a blackfish or even any part of one, I shall 

 now venture to offer my own definition of the group of Gato- 

 dontina as more accurate than that given by my predecessors as 

 the character of the 



* Is this correct ? 



