BALENIDE 237 
Mr. Robert Gray. In this species all the peculiarities which 
distinguish the head and mouth of the Whales from those of other 
mammals have attained their greatest development. The head is 
of enormous size, exceeding one-third of the whole length’ of the 
creature. The cavity of the mouth is actually larger than that of 
the body, thorax and abdomen together. The upper jaw is very 
narrow, but greatly arched from before backwards, to increase the 
height of the cavity and allow for the great length of the baleen 
blades ; the rami of the mandible are widely separated posteriorly, 
and have a still further outward sweep before they meet at 
the symphysis in front, giving the floor of the mouth the shape 
of an immense spoon. The baleen blades attain the number 
of 380 or more on each side, those in the middle of the series 
having a length of 10 or sometimes 12 feet. They are black in 
colour, fine and highly elastic in texture, and fray out at the inner - 
edge and ends into long, delicate, soft, almost silky, but very tough, 
hairs. The remarkable development of the mouth and the structures 
in connection with it, which distinguishes the Right Whale among 
all its allies, is entirely in relation to the nature of its food. It 
is by this apparatus that the animal is enabled to avail itself of 
the minute but highly nutritious crustaceans and pteropods which 
swarm in immense shoals in the seas it frequents. The large mouth 
enables it to take in at one time a sufficient quantity of water filled 
with these small organisms, and the length and delicate structure 
of the baleen provide an efficient strainer or hair-sieve by which the 
water can be drained off. If the baleen were rigid, and only as 
long as is the aperture between the upper and lower jaws when the 
mouth is shut, a space would be left beneath it when the jaws were 
separated, through which the water and the minute particles of food 
would escape together. But instead of this the long, slender, 
brush-like, elastic ends of the whalebone blades fold back when 
the mouth is closed, the front ones passing below the hinder 
ones in a channel lying between the tongue and the lower jaw. 
When the mouth is opened, their elasticity causes them to 
straighten out like a bow unbent, so that at whatever distance 
the jaws are separated the strainer remains in perfect action, 
filling the whole of the interval. The mechanical perfection of 
the arrangement is completed by the great development of the 
lower lip, which rises stiffly above the jaw-bone and prevents the 
long, slender, flexible ends of the baleen from being carried 
outwards by the rush of water from the mouth, when its cavity 
is being diminished by the closure of the jaws and raising of the 
tongue. 
If, as appears highly probable, the “bowhead” of the Okhotsk 
Sea and Behring Strait belongs to this species, its range is cireum- 
polar. Though found in the seas on both sides of Greenland, and 
