1916] Chandler: Structure of Feathers 373 



tip than near base of pennulum. No dorsal cilia, even on inner 

 vane, and booklets moderately long, only 3 in number (pi. 31, 

 figs. 80a, 80h). Proximal barbules of outer vane, on terminal por- 

 tion of barbs, have ventral teeth increased in number, but remaining 

 blunt, and appressed to barb (pi. 31, fig. 80c), well-developed 

 ventral barbicels never being formed. Body feathers, where not 

 modified for color, with barbules similar to those of remiges, but 

 simpler. 



Cypselidae.— In Cypseloides niger, on inner vane of remiges, 

 distal barbules have base of typical coraciiform shape, but the 

 ventral tooth, usually single and relatively large, with its tip bent 

 sharply down, giving it a blunt appearance distally. Pennulum 

 with more proximal dorsal cilia developed and stout in form on 

 barbules on outer portion of barbs, on the inner portion only the 

 ventral ones present; these moderate in size and curved as in 

 Coracias, pennulum usually breaking off a little distal to booklets. 

 Proximal barbules with short, broad, tapering bases, the ventral 

 edge more or less scalloped, and pennulum rather heavy, about as 

 long as bases. Body feathers have distal barbules with ventral tooth 

 larger at tip than at base as in some passerine birds. Chaetura 

 differs in having broader bases of the distal barbules and rather 

 reduced booklets. 



Trochilidae. — In remex of Selasphorus rufus, distal barbules are 

 characterized by disproportionate size of base and relatively large 

 ventral teeth. Proportionate to the size of the base, the booklet 

 region of the pennulum and booklets are exceedingly small (pi. 32, 

 figs. 88a and &). In all feathers examined of this species and of 

 several other species the pennulum was broken off one or two cells 

 beyond the booklets as shown in the figures. The base measures 

 about 0.18 by 0.025 mm., while the pennulum, up to the point 

 where usually broken off, is only one-fifth as long. The proximal 

 barbules have short, broad, tapering bases, with the ventral edge 

 scalloped, ventral teeth inconspicuous and pennulum stout, about 

 as long as base (pi. 32, fig. 88c). 



Body feathers have barbs with approximately equal vanules, the 

 barbules very numerous, about 45 per mm. on each side, with their 

 broad surface exposed, but not in contact on feathers without color 

 modifications. Pennula of barbules of both vanules broad and thin, 

 lying in a vertical plane and turned at such an angle with the base 

 as to be parallel with the ramus (see Beebe, 1906, fig. 27). This 



