THE FRESH-WATER DOLPHINS 1209 



with the vertebrae in a manner very similar to that we have seen in ordinary Mam- 

 mals, and the whole of the vertebras of the neck remain separate from one another. 

 In some respects these Cetaceans are less specialized than the other living rep- 

 resentatives of the order, and are, therefore, probably more nearly allied to the 

 ancestral stock. This leads Sir W. H. Flower to suggest that Cetaceans originated 

 in fresh water, from land animals; but Mr. Blanford considers it more probable that 

 the existing fresh-water dolphins may have been derived from a family which was 

 originally widely distributed and marine, and that they have managed to survive 

 solely by having taken to a fresh-water life. The isolated distribution of the three 

 living species is somewhat in favor of the latter view. 



The Gangetic dolphin, or susu (Platanista gangetica] is the typical 

 e _ *" representative of the family, and inhabits the Indus, Ganges, and 



Brahmaputra rivers, with their larger tributaries, from the regions 

 where they leave the mountains to the sea. It is characterized by its long and com- 

 pressed beak, which is slightly enlarged at the extremity; by the back fin being 

 rudimentary and replaced by a low ridge; by the flippers being triangular and fan 

 shaped; by the eye being very minute and rudimentary; and by the blowhole form- 

 ing a longitudinal slit. The conical and cylindrical teeth are rather large, and 

 while they are sharply pointed in the young, in the adult they become much 

 worn down by use. Toward the extremities of the jaws they are so closely placed 

 as to be almost in contact with one another. The skull is characterized by the 

 development of enormous crests at the root- of the beak , which almost meet in the 

 middle line above the latter. In the males the beak is much shorter than in 

 the females; and there are generally about thirty teeth on each side of the jaws. 

 The color of the animal is blackish throughout. Females are larger than males; the 

 usual length of adults varies from seven to eight feet, but a specimen from the 

 Jumna is said to measure upw r ard of twelve feet. 



The Gangetic dolphin is totally blind; and, indeed, as Mr. Blan- 

 ford observes, sight would be perfectly useless to it in the turbid 

 waters of the Indus at all seasons, and in the Ganges and Brahmaputra at most 

 periods of the year. It is never seen out at sea; but appears to be to a certain extent 

 migratory in the rivers, since none are observed in the Hugli at Calcutta during 

 the hot season from March to June, although they are commonly visible in the cold 

 months from October to March. That they also remain in the tidal waters of the 

 river during the rainy season from June to October is proved by the circumstance 

 that they are then frequently caught in fishing nets, although the animals rarely 

 show themselves above water. " This fact," writes Dr. Anderson, to whom we are 

 indeoted for a full account of the habits of this interesting Cetacean, "may be 

 accounted for on the supposition that the strength of the current is so great when 

 the Hugli is full that the dolphin is prevented from rising to the surface in the 

 marked manner it does during the cold weather, when the current has slackened and 

 there are comparatively-quiet reaches in which it can disport. The disturbed state 

 of the river when it is swollen doubtless renders the presence of the dolphin very 

 difficult of detection, for at such times it will simply expose its blowhole too 

 restricted a surface to be noticed on the troubled waters. In the cold weather 



