GALLERY OF GET ACE A, 
47 
chiefly limited to tlieir skeletons, assisted by drawings of their 
external forms. The general appearance of many of the smaller 
kinds is, however, shown by stuffed specimens and coloured 
casts. A general account of the structure and classification of 
the Cetacea, with special reference to those exhibited in this 
gallery, will be found at the end of the Guide to the G-alleries 
of Mammalia.* 
On the left side of the door, on entering, near the windoAv, is a Fresh-water 
case containing a stuffed specimen, skeleton, and several skulls ^°^P^S' 
of the very curious fresh-water Dolphin of the rivers of India 
(Platanista gangctica), and in the next case the peculiar Dolphin 
of the river Amazon {Inia geoffrensis). Among the specimens 
on the same side of the room, one of the most interesting, on 
account of its remarkable dentition, is the Xarwhal or Sea- Narwhal. 
Unicorn. It has only two teeth, which lie horizontally in the 
upper jaw. In the female both remain permanently concealed 
within the bone of the jaw, so that this sex is practically 
toothless ; but in the male, while the right tooth remains 
similarly concealed and abortive (as shown in the specimen, by 
removal of part of the bone which covered it), the left is immensely 
developed, attaining a length equal to that of half the entire 
animal, projecting horizontally from the head in the form of 
a long, straight, tapering and pointed tusk, spirally grooved 
on the surface. In some very rare cases both teeth are fully 
developed, as in the fine skull exliibited near the skeletons. 
Most of the largest Cetacea belong to the group called Whalebone 
" Whalebone ^AHiales," in which a series of horny plates called Shales, 
"baleen," or more familiarly "whalebone,"' grow from the 
palate in place of teeth, and serve to strain the water taken into 
the mouth from the small marine animals on which the whales 
subsist. A fine representative of this group is the very perfect 
skeleton of the Common Eorqual or Fin-whale (Balseno-ptcva 
mitsculus) near the further end of the middle of the room. It is 
sixty-eight feet long, and was captured in 1882 in the Moray 
rirth, Scotland. The flukes of the tail and dorsal fin are pre- 
served with the skeleton and suspended in their natural position, 
and the small pelvic bones and a rudimentary nodule, represent- 
* * Guide to the Galleries of Mammalia (]\Iammalian, Osteological and 
Cetacean) in the Department of Zoology.' Price sixpence. 
