ORGANIC RESPONSE 



263 



nently of this class, and of the vertebrates, the birds, 

 although the bats, among the mammals, share with 

 the birds the conquest of the air. But in some other 

 groups as well, special types of aerial or semi- 

 aerial forms are thus endowed. In the flying-fishes 

 the pectoral fins are long and expanded, so that the 



FIG. 90. Two kinds of Flying Fishes. These fishes escape from 

 their enemies by leaping into the air and sailing long distances. (From 

 Jordan and Kellogg.) 



fish, after attaining headway in the water, can shoot 

 above the surface and, spreading the fins, soar like an 

 aeroplane for long distances. 



Subterranean Adaptations. In the keen com- 

 petition that exists among the various types of 

 anima]s for a foothold and a chance to propagate 

 their kind, not only the surface of the earth, the air, 

 and the water have become filled with life, but, in the 



