﻿EXTERNAL ANATOMY. SCANSORIAL FEET. 13? 



and therefore we find a corresponding diminution in the 

 length of the hind toe, which is rather shorter than 

 that in the middle ; but addi- 

 tional strength is given to the 

 claws, all of which are stronger, 

 broader, and much more 

 curved, than in the genera we 

 first noticed : the toes, also, 

 are cleft to their base, and the 

 lateral ones are of the same 

 length. Few ornithologists, 

 indeed, would suspect these 

 birds to be climbers, seeing 

 that their feet are of the ordi- 

 nary size, and that there is no 

 very striking development of the scansorial structure in 

 any one part. Nevertheless, we may arrive at this con- 

 viction by the form and elongation of the hinder toe, 

 the strength, curvature, and compression of the claws 

 and the diminished flexibility of the tail feathers, when 

 compared with these parts in ordinary perchers. It is 

 at this point of the series that nature determines upon 

 a third and new modification of the scansorial faculties. 

 In the long-toed nuthatches, first described, she has con- 

 centrated this power solely in the feet. In the genera 

 ZenopSy Anabates, 8$c, it is divided between the toes 

 and the claws, some little aid being derived from the 

 tail. But in the third modification of these powers, 

 which we shall now describe, greater facilities for climb- 

 ing are given to all these members, so that we come to 

 the highest development of the scansorial faculty in 

 birds whose toes are not arranged in pairs. This change, 

 however, like all her other operations in the physical 

 world, is marked by harmoniou gradation. The gra- 

 dual diminution of the characters last enumerated among 

 the more slender clawed Synallaoci, would lead an orni- 

 thologist, who merely saw some two or three of the 

 species, to suppose they had no connection with this 

 family, whereas it is in this very genus that nature 



