﻿138 ON THE CLASSIFICATION OF BIRDS. 



marks out and effects the change we have just intimated, 

 and all this is accomplished within the limits of a single 

 genus.* We have already had occasion to illustrate 

 this very beautiful transission, as shown by the gradual 

 change exhibited by the structure of the tail (101.), and 

 it is equally so if we merely looked to the foot : that of 

 Synallaocis cinnamomeus is of the same robust form as its 

 congeners, but the toes, both before and behind, are 

 longer, and their claws more slender, especially the 

 hinder one. The tail preserves the broadness peculiar 

 to' Synallaocis, but then it assumes the pointed and 

 almost naked ends of Certhia familiaris : a more beau- 

 tiful union of the characters of two genera cannot, per- 

 haps, be exhibited in the whole circle .of ornithology ; 

 and so much may be taught by frequent examination of 

 these two species, in conjunction with a typical example 

 of Synallaocis t, that they are the first birds which every 

 ornithologist should possess, who wishes to study, not the 

 bare and technical nomenclature, but the true philosophy 

 of our charming science. We thus arrive at a group 

 (forming our sub-family of Certhiance) which answers 

 to the description already given, that is, where nature 

 gives a higher development than she has hitherto done, 

 to every organ employed in climbing, so as to constitute 

 the Certhiance the pre-eminent type of the scansorial 

 creepers. We regret our space will not permit us to 

 trace this development in any other member than the 

 foot. Commencing, then, with that of the common 

 creeper, we obseive all the indications exhibited by 

 Synallaocis cinnamomeus, brought, as it were, to perfec- 

 tion : the toes are very slender, the inner one consider- 

 ably the shortest, and the hinder one again so lengthened 

 that it equals that of the middle : all the claws are 

 large, very slender, and acute, but while those in front 

 are greatly curved, that behind is much less so ; its 

 great length, however, added to the general character of 



* The genera of the Scansores, Tenuirostres, and Fissirostres are equi- 

 valent to the sub-genera of the Jnsessores. 

 f The typical species are Sy. Caniceps and Ruficeps. See Appendix. 



