340 University of California Puhlications in Zoology [Vol. 11 



the tenth primaries there is a gradual shortening of the feathers 

 to 182 millimeters in the tenth, together with an emphasized 

 curvature of the shaft, and an increasing .amount of poorly 

 developed vane at the base. 



The secondaries, of which there are fourteen, show a gradual 

 transition from the outermost to the innermost. The first one 

 is scarcely distinguishable from the last primary, the chief 

 differences being in the more slender shaft, and in the intensified 

 curve toward the inner vane. The tip of the feather is more 

 broadly rounded than is the case with any of the primaries. The 

 first eight or nine secondaries, though very similar to each other, 

 decrease in size to 160 millimeters in the eighth, and have 

 increa.singly slender shafts. Beyond the ninth secondary the 

 transition from primary to covert type of feather becomes more 

 rapid. The pronounced curve toward the inner vane is gradu- 

 ally lost entirely, the shaft becomes very slender and flexible and 

 the vanes become more and more equivalent in size, until in the 

 fourteenth they are practically equal. As is very frequent among 

 birds, the fifth secondary is absent, although its coverts are 

 present. 



Microscopic Structure 



Tlie minute structure of the barbs and barbules, as might be 

 expected, is at its highest development in the remiges. As an 

 example, let us study a barb from the wide portion of the inner 

 vane of the third primary. We find that in a superficial way 

 the barb resembles a complete feather in its structure. The 

 ramus is a thin lamella about 0.46 millimeter deep at the base 

 and gradually tapering toward the tip. The proximal "vane" 

 of barbules, if such it may be called, is 0.16 millimeter wide; 

 the distal vane, measuring to the tips of the barbules, 0.40 milli- 

 meter. While the distal vane springs from the dorsal line of the 

 ramus for its entire length, the proximal vane slopes down as 

 it approaches the base of the barb, so that at its junction with 

 the shaft it arises from a place about half way down on the 

 ramus. 



The number of barbules per unit of measure gradually 

 decreases from the base to the tip of the barb, very rapidly 



