﻿78 ON THE CLASSIFICATION OF BIRDS. 



are called the external and the internal webs. To 

 outward appearance the form of the laminae which com- 

 pose these webs, appears to be much the same as that 

 of down, which has been just described, with this differ- 

 ence only, that the laminae are stronger and elastic, and 

 seem to stick together, and form a parallel series, which 

 the downy laminae do not. Now, this singular adhe- 

 siveness is seen by the microscope to be occasioned 

 by the filaments on each side of these laminae being 

 hooked into those of the next lamina, so that one sup- 

 ports the other in the same position ; while their elasti- 

 city makes them return to their proper place in the 

 series, if by any accident they are discomposed. This 

 will be sufficient to give the reader a correct idea of the 

 general construction of a feather, without going into 

 further details on the microscopic appearance of the 

 parts. In all such feathers that part only is coloured 

 which is exposed to the air. It is usual to state that 

 the feathers on the body of a bird are disposed or set in 

 a quincunx form, thus * • " — This, however, does not 

 appear to us a correct statement of the fact, the points 

 of their insertion forming, in reality, only a series of 

 triangles over the whole body, thus ' . * ; in other words, 

 they are imbricated, the termination of one forming the 

 basis, as it were, of the sides of two others. It is only 

 in those birds whose feathers are remarkably rigid (like 

 those of the shining crests and throats of the humming- 

 birds, or Trochilidce), that this disposition can be distin- 

 guished externally ; but it may be readily detected in a 

 recent bird, by examining the feathers where they are 

 inserted in the skin. It is an error also to assert that 

 these feathers are equally spread over the whole body, 

 because there are few or none on the sides of the neck, 

 or upon the front of the belly — in the latter case they 

 would obviously be in the way of imparting the full 

 animal warmth of the parent to the eggs in the process 

 of incubation ; and they are accordingly deficient. 



(72.) The wing feathers, and those of the tail, are 

 those which we have placed in the third class of the last 



