OF THE ATTITUDES AND OF LOCOMOTION. 



149 



projects the whole body forwards ; at the 

 same instant, the pelvis turns a little on 

 the femur of the opposite side, and the leg 

 which at first remained behind, bends, is 

 carried forward, and in its turn is placed 

 on the soil, to carry forward the whole 

 body by the extension of the foot. By the 

 aid of these alternate movements of flexion 

 and extension, each limb carries in its turn 

 the weight of the body, and at each step 

 the centre of gravity is pushed forwards. 

 For an instant the body is carried alter- 

 nately on one foot, and the centre of 

 gravity is carried flexuously from side to 

 side at each step, and this in proportion 

 to the width of the pelvis. 



289. As the functions of every appa- 

 ratus are always in relation with the 

 structures, so the limbs of various animals 

 show great variety in their disposition. 

 Thus, amongst mammals, some are des- 

 tined to move in water or on land that 

 is, to swim or walk, as suits them, or to 

 swim only ; others have the limbs formed 

 for speed ; others, as bats, fly like birds ; 

 some use their fore limbs only as instru- 

 ments of prehension or touch ; and yet the 

 limbs in all these animals are formed pre- 

 cisely on one plan. In the swimming 

 limbs of the seal, the wing of the bat, the 

 fore limbs of the squirrel or mole, we find 



* Skeleton of the right fore leg of the Asiatic 

 Elephant. In the construction of the legs of the 

 elephant, Nature seems to have done her utmost to 

 combine enormous strength with a remarkable de- 

 gree of agility. The ulna, which in other animals 

 falls off as it approaches the wrist, and is articulated 

 only indirectly with the carpal bones, in the ele- 

 phant, on the contrary, enlarges to a size even 

 greater than the radius, and is articulated directly 

 with the carpus. The other exception to the almost 

 universal law of the falling off of the ulna, I dis- 

 covered in the dugong, and pointed it out as one of Fig. 102."* 

 the characters separating the dugong from the 



Cetacea, in which I had placed it. Long afterwards, the illustrious De 

 Blainville accepted of my arrangement as the only correct one, and restored 

 the dugong to the elephant, to which it more nearly belongs. 



