﻿74 ON THE CLASSIFICATION OF BIRDS. 



catchers and warblers must be widely separated ; the 

 crows and the tom-tits be classed together, and the avosets 

 joined to the recurved-bill humming-birds. These are 

 only a few of the ridiculous combinations which would 

 result from such a principle of classification, which, 

 however simple and inviting it may appear in theory, 

 becomes utterly impracticable when we attempt to work 

 out its details. 



(68.) The nuchal bristles of birds are certain setaceous 

 hairs, more or less developed, but always simple, which 

 arise from the nape, or back part of the neck of several 

 birds, and are concealed among the feathers. They are 



most developed in the bristle-necked thrushes, forming 

 the genus Trichophorus (fig. 38.), where they are so much 

 prolonged as to be three times the length of the surround- 

 ing feathers ; and it is generally supposed that they are 

 altogether peculiar to this group. We believe, how- 

 ever, that a great many of the perching genera are 

 furnished with these appendages, for we have detected 

 them in our common thrushes, and even in the robin 

 redbreast. It is only, however, in the circle of the 

 short- legged thrushes, or the Brachypodince* , that these 

 bristles are lengthened ; in all other birds that we have 

 yet seen, they are merely the length of the ordinary 

 feathers of the nape, from which they are to be dis- 

 tinguished by being destitute of any webs, excepting a 

 few at their extreme point. Their use is not accurately 

 known, but they are probably connected with the sexual 

 intercourse. 



* First defined and characterised in North. Zool. vol. ii. Appendix i. 



