jyi-iJ Chandler: Feathers of Circus hudsonius 



359 



eiitiated and are closely appressed to the barbs, the only ones 

 which stand out from each other being those which are attached 

 directly to the shaft and fill in the angle between the shaft and 

 the barbs. The only function of these barbules is to give an 

 uneven surface to the barbs, in order more effectually to catch 

 and hold particles of dust coming in contact with them. The 

 aftershaft is over half as long as the main shaft, and has a struc- 

 ture almost identical with it, the barbs being, possibly, farther 

 apart than on the main shaft. 



Post- and Supea-orbital Bristles 

 Just back of the eye, in a line where the feathers of the crown 

 curve down, but do not quite meet the upcurving ear-coverts, 

 there are a few very small feathers, having a structure similar 

 to that of the ear coverts, except that the shaft is elongated as 

 a bristle for several millimeters beyond the tip of the barbs. 

 Such feathers are described in the water rail by Bonhote (1911- 

 12). The barbs are a little more numerous than they are in the 

 ear coverts. The supraorbital feathers, between the crown 

 feathers and the eye, are very much like the last-named feathers, 

 the main shaft being continued naked and black for about four 

 millimeters (pi. 20, fig. 19). The barbs appear coarse and cylin- 

 drical, due to the close appression of the filiform barbules. The 

 aftershaft has only about half as many barbs as the main shaft 

 and is not continued as a bristle. These feathers are very 

 numerous in the narrow, supraorbital region of the head. 



Eyelashes 



The eyelashes (pi. 20, fig. 20), of which there is a single 

 row completely encircling the eye, are among the most highly 

 specialized, and at the same time the simplest feathers of the 

 body. The calamus is comparatively heavy and barrel-shaped, 

 about one millimeter long. Prom the hollow calamus the main 

 shaft continues stiff, straight, and unbranched, 5.5 millimeters 

 long, cylindrical in form, and very deeply pigmented with black. 



