CHAPTER III. 



CONCLUDING REMARKS. 



In this short chapter I propose to discuss, first, the osteolo- 

 gical affinities of the Catodontidce , or family of sperm whales ; 

 secondly, the true characters which distinguish that family, — 

 and thirdly, the causes of their rarity. 



The first of these questions regards the animals to which 

 the sperm whale family, in the structure of their skeleton, 

 come the nearest. I have already, in a multitude of points, 

 shown their close affinity to the dolphin family, and the fol- 

 lowing series of DelpMnidxB is arranged very nearly in the 

 manner that Mr. Gray has, in his late work on Cetacean con- 

 sidered to be the natural disposition of these animals. 



DELPHINID^. 

 Normal Group^ 



FLUYIATILE. 



Symphysis of , a. Iniina, Gray. 

 under jaw more 

 than half length 

 of jaw, and 

 much com- 



pressed. 



Aberrant Group. 



MARINE. 



b. Platanistina, Gray. 



'c. Hyperoodontina, Gray. 



Symphysis of 



Tit'i J'T^. ""^^^ d. MoNOCEBATiNA, Gray. 

 halt length of ^ 



jaw. 



e. Delphinina, Gray. 



Maxillary bones 

 horizontal. 



Maxillary bones 

 rising vertically on 

 edge, so as to form a 

 crest over the nos- 

 trils. 



Upper jaw tooth- 

 less, ilaxillary 

 bones raised verti- 

 cally on edge, so as 

 to form a crest over 

 the nostrils. 



Upper jaw with 

 few teeth. Maxil- 

 lary bones sub-hori- 

 zontal, and rather 

 plane. 



Upper jaw with 

 many teeth. Max- 

 illary bones sub -ho- 

 rizontal and plane. 



