SUMMARY OF'PHILOSOPHIE ZOOLOGIQUE: 35 



[This is taken, I believe, from Dr. Darwin or Buffon, 

 but I have lost the passage, if, indeed, I ever found it. 

 It had been met by Paley some years earlier (1802) 

 in the following : 



"There is nothing in the action of swimming as 

 carried on by a bird upon the surface of the water that 

 should generate a membrane between the toes. As to 

 that membrane it is an action of constant resistance. . . 

 The web feet of amphibious quadrupeds, seals, otters, 

 &c., fall under the same observation." *] 



" On the other hand those birds whose habits lead 

 them to perch on trees, and which have sprung from 

 parents that have long contracted this habit, have their 

 toes shaped in a perfectly different manner. Their claws 

 become lengthened, sharpened, and curved, so as to 

 enable the creature to lay hold of the boughs on which 

 it so often rests. The shore bird again, which does 

 not like to swim, is nevertheless continually obliged 

 to enter the water when searching after its prey. Not 

 liking to plunge its body in the water, it makes every 

 endeavour to extend and lengthen its lower limbs. In 

 the course of long time these birds have come to be 

 elevated, as it were, on stilts, and have got long legs 

 bare of feathers as far as their thighs, and often still 

 higher. The same bird is continually trying to extend 

 its neck in order to fish without wetting its body, and 

 in the course of time its neck has become modified 

 accordingly, t 



" Swans, indeed, and geese have short legs and very 



* < Nat. Theol.,' vol. xii., end of viii. 

 t ' Phil. Zool.,' torn. i. p. 249 



