WHALEBONE WHALES. 
95 
horn'’^) is not known. Three tusks are exhibited on the wall 
to the right o£ the entrance. 
Although the Whalebone Whales (Mystacoceti) have rudi- 
mentary teeth developed at an early period of life, these soon 
disappear, and their place is occupied in the upper jaw by the 
whalebone,” which consists of a series of flattened horny 
plates, between three and four hundred in number on each side 
of the mouth, placed transversely to the long axis of the latter, 
with very small interspaces. Each plate or blade is somewhat 
triangular in form with the base attached to the palate, and the 
point hanging downwards. The outer edge of the blade is hard 
and smooth, but the inner edge and tip fray out into long- 
bristly fibres, so that the roof of the Whale’s mouth looks as if 
covered with hair. The blades are longest near the middle of 
the series, and gradually diminish towards the front and back 
of the mouth. Whalebone (as seen in various specimens in the 
skulls and on the wiills) varies much in colour in different 
species of Whales. In some it is almost jet-black, in others 
slate-colour, horn-colour, yellow, or even creamy white. In 
some the blades are variegated with longitudinal stripes of 
different hues. It differs also greatly in other respects, being- 
short, thick, coarse, and stiff in some, and greatly elongated 
and highly elastic in those species (as the Greenland Eight- 
Whale, Balcma mysticetus) in which it attains its fullest 
development. Its use is to strain the water from the small 
marine molluscs, crustaceans, or fishes upon which these 
Whales subsist. In feeding, they fill the immense mouth with 
water containing shoals of these small creatures, and then, on 
closing the jaws and raising the tongue so as to diminish the 
cavity of the mouth, the water streams out through the narrow 
intervals between the hairy fringe of the whalebone-blades, and 
escapes through the lips, leaving the living prey to be 
swallowed. 
Among other characters distinguishing Whalebone Whales 
from Toothed Whales is the distinctness of the external 
openings of the nostrils, which consist of a pair of longi- 
tudinal slits on the top of the head. The two sides of the 
upper part of the skull are also symmetrically developed, and 
