1916] Chandler: Structure of Feathers 349 



umbilicus very high, much higher than wide, and egg-shaped in 

 cross-section. Rami moderately broad at junction with shaft, pith 

 more than one cell thick, the ventral ridge rather narrow, less than 

 one-seventh total width of ramus, its ventral edge smooth. 



Inner vane. — Distal barhules (pi. 26, fig. 50a) set about 28 per 

 millimeter. Base short and broad, about 0.24 mm. by 0.06 mm., 

 ventral teeth of moderate size, broad and lobate, their tips often 

 inconspicuously jagged, or very slightly bifurcated. Pennulum 

 considerably longer than base, rather broad, booklets 5 or 6, mod- 

 erately slender and progressively longer, but booklet cells so short, 

 and each successive booklet curved so much farther distal, that distal 

 ones reach no farther ventral than proximal ones; ventral cilia 

 slender, but slightly curved, all but first two or three appressed to 

 pennulum; more proximal dorsal barbules spinelike, especially first 

 two, more distal ones well developed, but slender, curving forward. 

 Proximal barhules (pi. 26, fig. 50c) relatively large, set about 17 

 per millimeter, base about 0.73 mm. long by 0.07 wide, with 5 or 6 

 rather narrow, pointed, conspicuous ventral teeth ; pennulum some- 

 what shorter than base but over half as long, fiattened and mod- 

 erately broad proximally, its tip slender, with rudimentary barbicels. 



Outer vane. — Distal barhules (pi. 26, fig. 506) differing from 

 those of inner vane only in loss of proximal dorsal cilia, other 

 details of both base and pennulum similar to ^those of inner vane. 

 Proximal barbules (pi. 26, fig. 50c), except at tip of barb, exactly 

 similar to those of inner vane. Towards tip of barb ventral teeth 

 become separated, and assume shape similar to those in Butorides 

 (pi. 20, fig. 216), i. e., short curved barbicels, intermediate in form 

 between typical ventral teeth, as exemplified in more basal proximal 

 barbules (pi. 26, fig. 50c), and typical hooked ventral cilia, as in the 

 terminal proximal barbules of the outer vane in Ballus (pi. 26, 



fig. 52c). 



(2) Other Feathers 



Back feathers have distal barbules with rather elongate, slender 

 base, the ventral teeth with bifurcation or jaggedness of tips more 

 pronounced. Pennulum very long, 0.05 mm. or over, giving velvety 

 effect to feathers. Both dorsal and ventral cilia similar to those of 

 distal barbules of inner vane of remex. Proximals (pi. 26, fig. 50d) 

 with slender base, about 0.65 mm. long by 0.05 wide, ventral teeth 

 reduced in size and number, and pennulum relatively shorter than 

 in remiges. 



Scapular feathers especially modified as ornamental plumes, a 

 large part of outer vane, and some of inner vane, with discrete, 

 i. e., non-adhering, barbs, which curve outward. This condition is 

 accomplished merely by the breaking off of distal barbules imme- 

 diately beyond base, thus destroying interlocking apparatus. Tips 

 of proximal barbules also usually imperfect. 



Breast feathers have structure of barbules on basal two-thirds 

 of middle barbs very similar to back feathers, except reduction of 

 all barbicels of distal barbules (pi. 26, fig. 50e) and shortening 

 of pennulum of proximals. On distal third a rather sudden transi- 

 tion occurs in both kinds of barbules to type shown in plate 26, 

 figure 50/. No differentiation between base and pennulum, the 



