FRESI-WATER DOLPHINS. 39 
o 
belonging to the cat-fish group (Silwridw). These are doubtless captured by the 
dolphin probing for them in the mud with its long snout. The captive specimen 
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 Hughli at Calcutta, in search of their favourite 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 Amazonian The fresh-water dolphin of the Amazons (Inia geoffroyensis) 
Dolphin. more resembles a porpoise in general appearance than the last species. 
The 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 characterised by having a distinct 
tubercle on the inner side of the base of their crowns; and the back-fin is repre- 
sented merely by a low ridge. The males attain a length of about 7 feet, while 
the females are little more than half the 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 characterising those of the Gangetic dolphin. In the 
skeleton, the breast-bone 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. 
Distribution. The inia, or bouto, as the animal is called in various parts of 
and Habits. South America, is entirely fluviatile, and inhabits the upper portions 
of the Amazons and its affluents; ranging over the area of country included 
between the 10th and 17th parallels of south latitude. In addition to the bouto, 
there are the other species of dolphins, belonging to the family Delphinide, found 
in certain parts of the Amazons. 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, head-foremost, down. On the other hand, when the bouto 
rises, “the top of the head is the part first seen; it then blows, and immediately 
afterwards dips head downwards, its back curving over, exposing successively the 
whole dorsal ridge. It thus seems to pitch heels-over-head, but does not show the 
tail-fin. Besides this peculiar motion [which seems to be very similar to that of 
the Gangetic dolphin], it is distinguished from the tucuxi by its habit of generally 
going in pairs. Both species are exceedingly numerous throughout the Amazon 
and its larger tributaries, but they are nowhere more plentiful than in the shoaly 
water at the mouth of the Tocantins, especially in the dry season. In the upper 
Amazon, a third pale flesh-coloured species is also abundant. In the broader 
Young. 
1 Sotalia pallida, p. 62. 
