260 FOOT OF THE GOATSUCKER. 



the feet better adapted for perching on twigs or other 

 horizontal supports, than the swallows. They have a 

 short membrane, connecting all the anterior toes at 

 their bases, and the middle front toe is longer than 

 the others, and the claw pectinated. 



There have been various speculations about the 

 use of this pectinated claw, some of them more and 

 some less ingenious, but none of them very much to the 

 purpose. That it does not in any way assist the bird 

 in perching, is proved, not only by the fact that the 

 toe which has it does not close so completely in the 

 terminal phalanx as the other toes, but hj the general 

 principle in nature that animals never hold on firmly 

 by means of teeth or pectinations in one continuous 

 inflexible member, in maintaining the stability of their 

 own position. A single adhering point to each move- 

 able part of the organisation, is that which makes the 

 hold the most secure, because it is the one which 

 allows the greatest play in all directions. Accord- 

 ingly, in the articulation of animals, whenever we find 

 a joint upon which there are to be cross motions, we 

 always find, the socket, and the head which plays in 

 that socket, simple, while, in those which have motion 

 in one plane only, the head and socket are often both 

 double, and not unfrequently ridged in addition. 



The speculations which have been made with 

 regard to the use of this pectinated claw, are hardly 

 worthy of repeating. That of White is the most 

 sagacious, because most agreeable with the general 

 analogy of nature. He says merely, that it appears 

 to be to aid the bird "in taking its prey;" as the 

 heron holds its slijjpery prey with a pectinated toe, 

 and mergansers and several other birds hold theirs 

 by serrated mandibles. But it has been also said 

 that this toothed claw is used in trimmino: the vibrissae 



