156 DELPIIINIDiE. 



is developed (MonopKyodont). The Btomach has several distinct pouches, 

 usually five. They have several distinct spleens. Many of them have a 

 dorsal fin, which however is only a simple prolongation of skin devoid 

 of any independent movement, and not connected in any way with the 

 vertebrae. 



The spiracle, or blowhole, is single or double. This does not serve 

 as an organ of smell, but is used as a respii-atory aperture. It has 

 generally been believed that the water taken into the mouth along with 

 their prey is expelled through this aperture in a jet, forming the 

 so-called spouting of whales ; but of late it is confidently asserted that 

 water is never expelled this way, and that it is simply the moisture of 

 the lungs and aii'-passages expelled along with the expired air which 

 causes the jet or spouting. 



The Cetacea are divided into the families Delphinidce, or Porpoises, 



and BalcenidcB, or Whales, both of which have representatives in the 



Indian seas. 



Fam. Delphinidce. 



Teeth numerous, conical ; nostrils open by a single transverse aperture ; 

 head of moderate size ; caudal fin notched. 



The cranium is broad and high ; the nasal passages nearly vertical. 

 The maxillaries are prolonged anteriorly, and also much developed pos- 

 teriorly, rising anterior to the frontals, over which they are expanded, 

 extending as far as the level of the nasals, wliich form the summit of the 

 cranium. They have in genet al no cajcum. 



The Dolphins, or Porpoises, as they are popularly called (the word 

 dolphin being usually restricted to the fish, Coryphcena, celebrated for 

 its changeable tints when dying), are found all over the world, in- 

 habiting seas, and many asceu ding large rivers. They generally associate 

 in flocks or shoals, are very active, swimming and playing near the 

 surface of the sea, and feeding on fishes, Crustacea, cuttle-fish, &c. They 

 often accompany ships for miles. There are several genera recognized, 

 one of which is peculiar to the rivers of India.* 



Gen. Delphinus, Linn. 



Char. — Rostrum narrow, of moderate length, continued abruptly from 



* Materials for the elucidation of thia family as represented in India are very- 

 deficient, and I am only able to indicate the names of some. Professor Owen has 

 recently read a paper on those collected by Walter Elliot, on the east coast, de- 

 scribing several new species, but the paper is not yet published. I will introduce, 

 in an Appendix to this volume, the species there described, if published before the 

 work is completed. 



