1916] Chandler: Structure of Feathers 263 



merely vestigial or rudimentary structures. No suggestion of a pos- 

 sible use has yet been made. 



III. Contour Feathers 



Under contour feathers, in their various forms and modifications, 

 may be included practically all of the diverse kinds of plumage ordi- 

 narily displayed on the body of a bird. In this category come all 

 remiges, rectrices, coverts, and exposed body-feathers, except in a 

 few instances where filoplumes or plumules are exposed, as in cormor- 

 ants and on the neck of Pelecanus respectively; also ear-coverts, eye- 

 lashes, rictal and other bristles, and all sorts of ornamental crests 

 and plumes, and other modified feather structures, such as the brush 

 of a turkey, the "wires" of some birds of paradise, the lyre of 

 Menura, etc. Their variety of form is almost limitless, yet they are 

 all modifications of the same fundamental structure. A discussion 

 of the various important types of feathers in a typical bird of flight 

 has been made for Circus hudsonius by me, (1914) and it is only 

 necessary here to generalize on the conditions found there, and show 

 along what lines phylogenetic modifications of this type have taken 

 place in the whole series of birds. 



1. Remiges 



a) Shaft.— The most highly specialized feathers, those in which 

 the structure reaches its height of perfection, are the remiges, espe- 

 cially the primaries, of strong-flying birds. These feathers, in all 

 flying birds, have a well-developed quill, differentiated into a hollow 

 calamus and a stiff shaft which is more or less rectangular in cross- 

 section, and usually has a groove running along the ventral side, 

 generally quite pronounced at the superior umbilicus and becoming 

 obliterated towards the tip of the feather. The condition of the 

 groove varies to a considerable extent in different groups of birds, in 

 some being broad and shallow, in some narrow and deep, and with all 

 gradations between in others. In the remiges of ostriches the ventral 

 groove of the shaft reaches its maximum size, the shaft in this case 

 being in the form of a half-cylinder, convex above and concave below, 

 while in some of the higher birds, e. g., Coccyzus, there is no groove 

 whatever. These facts at first glance would indicate that a large, 

 wide-open ventral groove is a primitive character, that the absence 



