242 ANIMAL LIFE PAST AND PRESENT. 



their limbs, but no one can suggest any improvement 

 in the general structure of the horse, which is in every 

 way adapted for the attainment of the highest speed, 

 coupled with endurance and power. 



Of perhaps still greater interest are the rudiments 

 of hind limbs found deeply imbedded in the bodies 

 of purely aquatic mammals, such as Whales and 

 Dugongs, in which, as is well known, there is not the 

 slightest external trace of such limbs, although the 

 fore limbs are large, and modified into powerful 

 paddles. The woodcut, Fig. 81, shows these structures. 



FIJ. 81. Side view of the bones of the rudimentary hind limb of the Whale. 

 i, pelvis ; /, thigh-bone ; f, leg-bone. 



as found in the Greenland Whale. The long horizontal 

 bone represents the pelvis of ordinary mammals ; while 

 the nearly vertical bone (/), which is about eight inches 

 long, appears to correspond to the thigh-bone, and 

 the little nodule t is the sole remnant of the bones 

 of the lower leg. In the Sperm Whale even these 

 useless remnants of a hind limb have completely 

 vanished, although parts of the pelvis still remain: 

 Many considerations have led to the conclusion that 

 Whales have originated from land mammals, and 



