248 THE ORIGIN- OF SPECIES 



an auk or a grebe; nevertheless it is essentially a petrel, 

 but with many parts of its organization profoundly mod- 

 ified in relation to its new habits of life; 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 famil}'^, 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 ex- 

 hibits 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 swim- 

 ming ? 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 mem- 

 brane. 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 



