484 EXTREMITIES OF LOWER ANIMALS. 
stances, we find the number of bones in the hand increased, 
but all of them enclosed in one envelope, so that the fingers 
are not separate. This is the case with many aquatic’animals 
Fig. 229.—SKELETON OF THE CAMEL, 
ve, cervical vertebre ; vd, dorsal vertebra ; vl, lumbar vertebra ; vs. sacral vertebrae 
og, caudal vertebre; s, scapula; h, humerus; ew, ulna; ea, carpus; me, meta 
carpus ; ph, phalanges; fe, femur; ro, patella; ti, tibia; ta, tarsus; mé, metatarsus 
—such as the Whale tribe among Mammals, Turtles among 
Reptiles, and Fishes in general,—in which the hand is mad 
to serve as a fin or paddle. In most of these, the bones o 
the arm are very short ; and the movements of the extremity 
are chiefly confined to the wrist-joint. 
645. The structure of the lower extremities has a very grea 
analogy to that of the upper; and the principal differences t 
be remarked between them, are such as are necessary to giv 
to the former more solidity at the expense of freedom o 
motion, and to make them organs of locomotion instead o 
organs of prehension. Here, too, we have a bony framework 
for the purpose of connecting the limb itself with the spine 
and as the weight of the body is constantly thrown upon th 
