ZOOLOGY. 



animals, are attached to two peculiar bones articulated to the 

 anterior ])arts of the pelvis, and called by anatomist > th- 

 marsupial bones* (Fig. 183 in). 



Humerus of the Anteri.ir Linih and Hand. 



Mole. 



H6. 



In the arm and thigh in all mammals there is but one 

 bone, the humerus and the femur ; in the fore-arm and leg, 

 two bones the radiu* and ulna in the fore-arm, the tibia and 

 perone or fibula in the leg. In bats there is a rotula in the 

 arm as well as in the leg. Generally, these leg and arm bones 

 are short and strong, or long and slender, according to the 

 habits of the animal. The mole and chamois may serve as 

 the examples of this modification : strength characterizes the 

 actions of the mole, and swiftness those of the chamois. 

 When the hand no longer serves for prehension, but merely 

 for support, the radius loses its power of rotation on the 

 ulna, and ends by uniting with it so intimately as to be no 

 longer distinguished from it. In the solidungulous animals, 

 the same happens with the fibula and tibia. 



The foot and hand vary in mammals, according as they 

 are used for prehension, swimming, flight, or walking on 

 ground more or less firm. These circumstances have been 

 already alluded to. The fingers or toes are never more than 

 five, and their number diminishes according as the extremity 

 is more exclusively used for simple progression. 



398. Organs of the Senses. The perfection of the 

 fingers and toes as instruments of touch seems to depend on 

 the fineness of the integuments, the form of the nail, and the 

 flexibility of the instrument. In this respect man stands pre- 

 eminent, in accordance, no doubt, with his higher intelligence 

 (Fig. 85). 



* These bones are present whether the pouch be there or not. E. K. 



