1914] Chandler: Feathers of Circus hudsoniiis 339 



superior umbilicus. The incision comes at a point slightly over 

 half way to the tip, and reduces the width of the vane from 

 26 millimeters to 16 millimeters. Beyond the incision there is 

 no tapering until the tip is approached. 



The outer vane, as a resistant surface, begins about 25 milli- 

 meters beyond the superior umbilicus, since the barbs proximal 

 to that point are downy in character, and do not adhere to 

 each other. The vane is 10 millimeters wide at its widest point, 

 from thence slowly tapering before the sudden narrowing at the 

 point of incision, beyond which it is only 3 millimeters wide. 

 Proximal to the incision the barbs are 16 to 18 millimeters long, 

 and set at an angle of 45 degrees ; distal to it they are 24 milli- 

 meters long, and set at an angle of 7 degrees, the transition 

 taking place in about one centimeter. 



All of the first five primaries are very similar to the one 

 described above, practically the only difference being in size, and 

 in extent of incision. The first, which is the smallest of the 

 five, 180 millimeters in total length, is most sharply curved 

 toward the inner vane, and has the most extensive incision, 

 especially the outer vane, which has barbs typical of the incised 

 portion fgr its entire length, except a very insignificant area of 

 normal barbs at its base. The inner vane is incised for approxi- 

 mately one half its length. As the shaft is not so stout as in 

 the third primary, the barbs of the outer vane are not so heavily 

 built, and are set somewhat closer together, there being six to 

 a centimeter, instead of four. The second primary is in every 

 way intermediate between the first and third. The fourth differs 

 from the third only in the less extent of its incisions. In this 

 feather the wide portion of the outer vane for the first time 

 exceeds the narrow portion, w'hile the inner vane, though nar- 

 rowed, has not so sharply demarcated a point of incision. The 

 fifth primary has these characteristics emphasized, the outer vane 

 being only about one-third narrow, and the inner vane beginning 

 to taper rapidly at the point where the incision would be 

 expected, instead of becoming abruptly narrowed. 



The remaining primaries, numbering six to ten, differ from 

 the others in their uniform width, and in the sharper angle of 

 the bend of the shaft toward the inner vane. From the sixth to 



