1914] Chandler: Feathers of Circus hudsonius 355 



traversing an arc of 90 degrees. The quill is inserted almost 

 perpendicularly to the body of the bird as in the upper back 

 feathers, so that the developed terminal portion of the feather 

 comes to lie flat on the contour of the body. 



The loosest and fluffiest of all the contour feathers of the 

 body are those of the flanks, lower belly, and legs. These feathers 

 are considerably elongated, frequently reaching a length of 

 eleven or twelve centimeters, and from half to two-thirds of 

 this is entirely downy in character. The aftershaft, which is 

 about half as long as the feather proper, and the basal third of 

 the latter are made up of barbs with long and numerous downy 

 barbules, the result being a dense, cottony structure. For some 

 distance proximad to the beginning of the differentiated barbules, 

 the feather has a very open and fragile appearance, due to the 

 fact that the barbs are widely separated on the shaft, there being 

 only eight or nine per centimeter, and the barbules, while still 

 filamentous and undifferentiated, are much shorter and less 

 numerous, those on the middle of the barb shortly proximad to 

 the loosely interlocking portion of the feather being from 0.8 

 to 1.8 millimeter long, and spaced about eleven or twelve per 

 millimeter on the barb. The barbs, which are loosely interlock- 

 ing, are not provided with specialized barbules all the way to 

 their tips, the more proximal of these barbs being held together 

 by only a few barbules at their bases. Near the tip of the feather 

 the barbs are not provided on their distal portion with typical 

 downy barbules nor with normal specialized ones. Those of the 

 distal series are very slender and tapering but not filamentous, 

 and are practically without modification except for two or three 

 weak booklets about half way to the end (pi. 19, fig. 13). The 

 proximal barbules (pi. 19, fig. 12) are slender and taper all the 

 way to the end. 



The more typical distal barbules of the brea.st feathers have 

 a narrow base about 0.23 millimeter long, followed by an ex- 

 tremely long, slender tip, possessing usually three booklets and 

 a single series of weak barbicels. The total length of the distal 

 barbules is about 1.25 millimeter, except near the base of the 

 barb, where they are shorter. The proximal barbules are not 

 highly specialized, having a very slender base and a threadlike 



