222 WHALES, PAST AND PRESENT xv 



baleen provides an efficient strainer or hair sieve by which the 

 water can be drained off. If the baleen were, as in the 

 rorquals, short and rigid, and only of the length of the 

 aperture between the upper and lower jaws when the mouth 

 was shut, when the jaws were separated a space would be left 

 beneath it through which the water and the minute particles 

 of food would escape together. But instead of this, the long, 

 slender, brush-like ends of the whalebone blades, when the 

 mouth is closed, fold back, the front ones passing below the 

 hinder ones in a channel lying between the tongue and the 

 bone of the lower jaw. When the mouth is opened their 

 elasticity causes them to straighten out like a bow that is 

 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 jawbone, and prevents the long, slender, 

 flexible ends of the baleen 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. The 

 interest and admiration excited by the contemplation of such a 

 beautifully adjusted piece of mechanism is certainly heightened 

 by the knowledge that it has been brought about by the 

 gradual adaptation and perfection of structures common to the 

 whole class of animals to which the whale belongs. 



Few points of the structure of whales offer so great a 

 departure from the ordinary mammalian type as the limbs. 

 The fore-limbs are reduced to the condition of simple paddles 

 or oars, variously shaped, but always flattened and more or less 

 oval in outline. They are freely movable at the shoulder- 

 joint, where the humerus or upper-arm bone articulates with 

 the shoulder-blade in the usual manner, but beyond this point, 

 except a slight flexibility and elasticity, there is no motion 

 between the different segments. The bones are all there, 

 corresponding in number and general relations with those of 

 the human or any other mammalian arm, but they are 

 flattened out, and their contiguous ends, instead of presenting 

 hinge -like joints, come in contact by flat surfaces, united 

 together by strong ligamentous bands, and all wrapped up in an 



