112 CETACEAN GALLERY. 



is Hyperoodon rostratus, of which are exhibited a complete skeleton 

 of an adult female, taken at Whitstable, Kent, in 1860, and the 

 skull of a very old male from the Orkneys, in which the bony 

 crests, rising on each side from the upper jaw, have attained such 

 an extraordinary development, that it was long supposed to be the 

 type of a distinct species, called H. latifrons. It has, however, 

 now been shown, that while in the young of both sexes the crests 

 are quite small, in the female they remain permanently of the size 

 shown in the skeleton, and in the male they gradually increase 

 as age advances. This animal is an inhabitant of the northern 

 parts of the Atlantic Ocean ; and as it yields both spermaceti and 

 oil, equal in value to that of the Sperm- Whale, it is now the object 

 of a regular " fishery." 



The southern representative of this species (H. planifrons] is as 

 yet only known from the water-worn and rolled skull from Western 

 Australia exhibited near the northern specimens, and the extent of 

 its range still remains to be discovered. 



Family PLATANISTID^E. 



On the left side of the door, near the first window, is a Case 

 containing a stuffed specimen, skeleton, and several skulls of the 

 very curious freshwater Dolphin of the rivers of India (Platanista 

 gangetica) . It has never been found in the open sea, but is exten- 

 sively distributed throughout nearly the whole of the river-systems, 

 not only of the Ganges, but of the Brahmaputra and Indus, 

 ascending as high as there is water enough to swim in. The eyes 

 are exceedingly small and imperfect in structure, and it appears to 

 be quite blind. It feeds on small fish and Crustacea, which it 

 gropes for with its long snout in the muddy water at the bottom 

 of the rivers. The blowhole, as may be seen in the stuffed spe- 

 cimen, is a single slit, placed lengthwise, and not transverse to the 

 head as in most Dolphins, and the dorsal fin is merely a low ridge. 

 The skull has a very remarkable form, having on the upper surface 

 a pair of large, compressed, bony crests, which overarch the aper- 

 ture of the nostrils and base of the rostrum, and nearly meet in 

 the middle line above. The upper and lower jaws are exceedingly 

 long and narrow, and armed with numerous slender, pointed teeth, 

 which undergo some curious changes of form as life advances. 



