THE FRESH-WATER DOLPHIN 1211 



water, the characteristic expiratory sound was produced, and so rapid was inspira- 

 tion that the blowhole seemed to close immediately after the expiratory act, and 

 then the animal slowly subsided. The respirations were tolerably frequent, occur- 

 ring at intervals of about one-half or three-fourths of a minute, and the whole act 

 did not take more than a few seconds for its fulfilment. ' ' 



The food of the Gangetic dolphin consists principally of fish and 

 prawns; many of the fish consumed by it being mud-haunting 

 species, belonging to the catfish group {Siluridce} . These are doubtless captured 

 by the dolphin probing for them in the mud with its long snout. The captive speci- 

 men above mentioned fed on the fish with which it was supplied only during 

 the night, but careful observations made on these dolphins in their native state 

 prove that they feed by day as well as by night. Sometimes they may be seen 

 among the shipping in the Hugli at Calcutta, in search of their favorite prawns, 

 during the daytime. The grain which is sometimes found in the stomachs of these 

 animals appears to be swallowed unintentionally. 



The young are born from April to July, and it is but very rarely 



that there is more than one at a birth. The period of gestation is 



believed to be from eight to nine months. It is said that the young will hold on by 



its mouth to the base of one of the flippers of its parent; but such a remarkable habit 



requires confirmation. 



The fresh-water dolphin of the Amazons (Inia geoffroyensis) more 



n & n T resem bles a porpoise in general appearance than the last species. The 



ph j n long, cylindrical beak, which carries from twenty-six to thirty-three 



teeth on each side of the jaws, is peculiar in being furnished with a 



number of sparsely-distributed, bristle-like hairs. The teeth are characterized by 



having a distinct tubercle on the inner side of the base of their crowns, and the 



back fin is represented merely by a low ridge. The males attain a length of about 



seven feet, while the females are little more than half that size. In general, the 



upper parts are blackish, and the under parts reddish; but individuals are found 



which are either entirely blackish or wholly reddish. The eye is well developed, 



and the flippers have not the fan-like shape characterizing those of the Gangetic 



dolphin. In the skeleton, the breastbone is short and broad, and composed only of 



a single piece; while the horizontal transverse processes of the vertebrae of the hinder 



portion of the trunk are remarkable for their great width. 



The inia, or bouto, as the animal is called in various parts of South 

 Distribution . . . ,. , .. . ., , . , , . . . . ,, 



d H b't America, 1S entirely fluviatile, and inhabits the upper portions of the 



Amazon and its affluents; ranging over the area of country included 

 between the tenth and seventeenth parallels of south latitude. In addition to the 

 bouto, there are the other species of dolphins, belonging to the family Delphinidce, 

 found in certain parts of the Amazon. One of these, called the tucuxi (a species of 

 the genus Sotalia), when it comes to the surface to breathe, rises, according to Bates, 

 horizontally, showing first its long, low, back fin. It then draws an inspiration, and 

 finally dives gently. On the other hand, when the bouto rises, "the top of the 

 head is the part first seen; it then blows, and immediately afterward dips head 

 downward, its back curving over, exposing successfully the whole dorsal ridge. 



