THE SUSU, OS GANGETIC DOLPHIN. 



249 



anterior and the posterior teeth is exceedingly marked in size, the former being very long, the latter 

 very short, while as age advances quite the reverse is the case. The back teeth also wear down very 

 considerably in the crown, and increase in breadth in root-substance ; indeed, as Dr. J. Anderson 

 has shown, the true dental material is worn away, and finally nothing but bone is left. The head 

 of the male is about two-thirds the length of that of the female, and in both its point is slightly 

 upturned. The apparently rounded skull behind the snout has broad thick zygomatic arches, and 

 above and in front of these the cheek-bones (maxillae) each send forwards and inwards a great 

 roughened sheet of bone or crest, which forms a kind of open helmet. In the large hollow between 

 these bony plates, and somewhat behind, are situated the nasal orifices, which are slightly awry. 



The Susu frequents the deep reaches and creeks of the river, occasionally coming to the surface to 



GANGETIC UOLl'HIX. 



blow, and although often heard are but seldom captured. Ordinarily their movements are slow, but 

 at times they seem exceedingly active. Their food is chiefly fish, shrimps, &c., which they grovel for 

 among the mud, something like Pigs wallowing in the mire. Grass, rice, and shells have been, found in 

 their stomachs, but Dr. Anderson has clearly shown that they are not vegetable feeders, for in the rainy 

 season, when great tracts of land are under water, these animals pursue the fish 

 right into the submerged " paddy-fields," and the grass is thus most probably 

 swallowed with their prey. The Hindoos have religious superstitions concern- 

 ing the Susu. It certainly is one of the oldest known Cetaceans, since Pliny 

 and ^Elian both allude to it. It has been supposed that the kind which in- 

 habits the Indus was a separate species, but this error has doubtless arisen from 

 the great difference in size of the skulls of the two sexes. This animal must 

 be all but blind, the optic nerve being no thicker than a thread ; but the fact 

 of its living habitually in muddy water renders sight less necessary than it 

 otherwise might be. Its peculiar dentition, so like that of the ancient Squalodons in many respects, 

 is of exceeding interest. The following is the dental formula of one specimen, ^^=117. The broad 

 roots of the rearmost teeth are usually grooved, and this gives them a deceptive appearance of pos- 

 sessing more than one fang ; moreover, differing as the teeth do front and rearwards, still distinctions 

 as to incisors, canines, and molars can hardly be said to exist. 

 81 



FLIPPER OF GAXGETIC 

 DOLPHIN. 



