﻿EXTERNAL ANATOMY. SCANSORIAL FEET. 135 



the scansorial tribe, we pass to that tribe itself. We 

 have already described the various constructions of foot 

 in four of the families (111 the toucans, parrots, wood- 

 peckers, and cuckows, all of which have the feet dis- 

 posed in pairs. The Certhiadce, or creepers, which 

 form the fifth or Rasorial family of this circle, have 

 proportionably larger feet * than any of the others, and 

 the toes are differently disposed. It would scarcely be 

 imagined that much further variation could be found, 

 where all had three toes forward and one backward, 

 and yet there are greater diversities in this group than 

 in all the other families of the Scansores put together. 

 We shall commence with the wrens, as the most aber- 

 rant of all the creepers, in which we consequently find 

 the faintest indication of the typical characters. So little, 

 indeed, do the majority of these birds climb, in the true 

 sense of the word, that it is only by tracing their close and 

 unquestionable relation to others, in which both the 

 scansorial structure and the faculty of exercising it is 

 more apparent, that we arrive at the positive certainty 

 of their belonging to this family. The length and form 

 of the bill, and the brown cast of the plumage of our 

 common species accords with the rest of the family, but 

 it is the peculiar length of 

 the hind claw (fig. 71 

 which shows that this genus 

 occupies a station in the 

 same circle with Lochmia, 

 Tichodroma, Platyurus, and 

 Thryothurus, each of which 

 have additional scansorial 

 characters. The hind claw in Troglodytes (b) is hardly 

 as long as that in the middle, and the tarsus exceeds 

 both ; but in the nuthatch (Sitta, fig. 72.). the length 

 of all the toes is greatly increased, yet the hinder and 

 the middle are of the same length, and both of them 



* Thus preserving their analogy to the Cracidce, Rasores, Rallida:, Me- 

 gapodia, &c. } all of which they represent in the circle of the Scansores. 

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