222 TRANSITIONS OF ORGANIC BEINGS. [Chap. VI. 



whereas the woodpecker of La Plata has had its structure 

 only slightly modified. In the case of the water-ouzel, 

 the acutest observer by examining its dead body would 

 never have suspected its sub-aquatic habits ; yet this 

 bird, which is allied to the thrush family, subsists by 

 diving — using its wings under water, and grasping 

 stones with its feet. All the members of the great 

 order of Hymenopterous insects are terrestrial, excepting 

 the genus Proctotrupes, which Sir John Lubbock has 

 discovered to be aquatic in its habits ; it often enters 

 the water and dives about by the use not of its legs but 

 of its wings, and remains as long as four hours beneath 

 the surface ; yet it exhibits no modification in structure 

 in accordance with its abnormal habits. 



He who believes that each being has Been created as 

 we now see it, must occasionally have felt surprise 

 when he has met with an animal having habits and 

 structure not in agreement. What can be plainer than 

 that the webbed feet of ducks and geese are formed for 

 swimming ? Yet there are upland geese with webbed 

 feet which rarely go near the water ; and no one except 

 Audubon has seen the frigate-bird, which has all its 

 four toes webbed, alight on the surface of the ocean. 

 On the other hand, grebes and coots are eminently 

 aquatic, although their toes are only bordered by 

 membrane. "What seems plainer than that the long 

 toes, not furnished with membrane of the Grallatores 

 are formed for walking over swamps and floating 

 plants ? — the water-hen and landrail are members of 

 this order, yet the first is nearly as aquatic as the coot, 

 and the second nearly as terrestrial as the quail or 

 partridge. In such cases, and many others could be 

 given, habits have changed without a corresponding 



