300 WHALES AND DOLPHINS 



not be equal to that on the other, and Anderson states that 

 fewer teeth are to be found in upper than in lower jaws. They 

 are small and sharply conical in young animals, but become 

 worn flat as the animal ages. The tooth diameter is about 

 \ inch. 



The body length is from 7 to y\ feet. 



Anderson recognized two species of Orcella, the form just 

 described, 0. brevirostris, and 0. fluminalis , which, he states, 

 " differs from 0. brevirostris in its rather smaller, lower and 

 more falcate dorsal fin, its more pointed and less anteriorly 

 bulging head and rather shorter and broader pectoral fins : 

 the colour in both is much alike being pale slaty above and 

 whitish on the under parts, but the skin of 0. faiminalis is 

 streaked somewhat as in Risso's Dolphin." 



Whether two distinct species do in fact exist is questionable, 

 and as far as our present purpose is concerned the differences 

 between them are so slight that they may be considered 

 together. 



0. flaminalis is said to be restricted in its distribution to the 

 Irawadi River from above the limit of tidal effects 300 miles 

 from the open sea to 900 miles up the river. 0. brevirostris is 

 known from the Bay of Bengal, Vizagapatam, Singapore and 

 the Chantabun coast of Siam. The genus has never been found 

 away from this south-east corner of Asia. 



Orcella, according to Anderson, is generally seen in small 

 schools which frequently accompany the river steamers. The 

 habits of marine and fluviatile forms do not differ. They 

 breathe at intervals of from 70 to 150 seconds, although at 

 times the interval may be greater. "The blowhole < is first 

 seen, then at the end of inspiration the head disappears and 

 the back comes into view and is gradually exposed as far as 

 the dorsal fin but the tail flippers are rarely visible. The act 

 of breathing is rapid. . . ." 



The food of this animal is exclusively fish. " The fishermen," 

 writes Anderson with reference to 0. fluminalis, " believe that 

 the dolphin purposely draws fish to their nets, and each fishing 

 village has its particular guardian dolphin which receives a 

 name common to all the fellows of his school ; and it is this 

 superstition which makes it so difficult to obtain specimens of 

 this Cetacean. Colonel Sladen has told me that suits are not 



