WHALES 



127 



(e) The finlike fore-limbs help to steer the body. The bones of the 

 upper and lower arm (humerus, radius and ulna) are, as in the seal, very 

 broad and much shortened, the hand only, the fingers of which are 

 united by strong webs, projecting into the water. All the parts of the 

 fore-limb are firmly united, there being no joints, with the exception of 

 the shoulder-joint, and therefore the limb works as one piece. The 

 action of the fore-limbs is, further, much assisted by the great pliancy of 

 the body. 



(/) The subcutaneous fat lightens the weight of the gigantic body in 

 the water, as does also 



(g) The oil, which permeates the porous bones, and 



(h) The lunij, which is of extraordinary size and extends further 

 backwards than in land mammals, whereby the centre of gravity of the 

 animal is shifted further forwards. The body during rest consequently 



Sketch of Body of Greenland Whale, with Skeleton marked in. 

 (One two-hundredth natural size.) 



Baleen; U., mandible; N. , nasal opening, showing expired jet of water vapour; 

 Bb,, thorax ; 1 E., first pair of ribs ; Sell., scapula ; 0., humerus ; Sp., radius ; E. , ulna ; 

 H., hand ; B.H. , bones of rudimentary pelvis and rudimentary hind -limb. 



assumes a horizontal position. (How does this position affect respira- 

 tion ? See Section 6.) 



{%) The smoothness of the shin has the effect of diminishing friction in 

 the water. (Compare the mucus of the skin in fish.) 



(k) External ears (pinna;), which would impede the forward motion 

 of the animal, are absent, nor are there any external auditory passages, 

 as in all other mammals. Nevertheless, below the water the sense of 

 hearing of the whale is so acute that it is said to perceive the strokes of 

 an oar. The eyes are situated not far from the angles of the mouth ; 

 they are about the size of those of the ox. 



(I) The extraordinary nimbleness of the animal is accounted for by 

 the structural peculiarities of the skeleton referred to in Section 2, and 



