ADAPTATION OP ORGANISMS 



317 



land of their ancestors of the geological past and to-day 

 approach, in adaptations to a marine life, the general contour 

 of the primitively 

 adapted aquatic Ver- 

 tebrates, the Fishes. 

 (Fig. 166.) 



Thus the various 

 lines of adaptive ra- 

 diation of the Mam- 

 mals from a general- 

 ized terrestrial type, 

 such as Gymnura, 

 have provided Mam- 

 mals fitted for all sorts and conditions of the environment 

 representatives are competing with members of other 



FIG. 164. A Sloth, Choloepus, walking suspended 

 from a branch. (After Allen.) 



FIG. 165. Skeleton of a Mole, Talpa europaea. 

 Pander and D'Alton.) 



(After 



FIG. 166. Skeleton of a Porpoise. The vestigial pelvic bones are shown 

 imbedded in the flesh. (After Pander and D'Alton.) 



groups beneath, on, and above the earth and in the water. 

 Somewhat similar adaptative radiations are traceable in other 

 animal and plant groups, though there seems no doubt that 



