WHALES, PAST AND PRESENT. 



203 



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 outward by 

 the rush of water from the mouth. 





Pig. 6. Korqual. 



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, correspond- 

 ing 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, iinited together by strong ligamentous bands, and all wrapped 

 up in an undivided covering of skin, which allows externally of no sign 

 of the separate and many-jointed fingers seen in the skeleton. 



The changes that have taken place in the hind-limbs are even more 

 remarkable. In all known Cetacea (unless Platanista be really an 

 exception) a pair of slender bones are found suspended a short dis- 

 tance below the vertebral column, but not attached to it, about the 

 part where the body and the tail join. In museum skeletons these 

 bones are often not seen, as, unless special care has been taken in the 

 preparation, they are apt to get lost. They are, however, of much 

 importance and interest, as their relations to surrounding parts show 

 that they are the rudimentary representatives of the pelvic or hip 

 bones, which in other mammals play such an important part in con- 



