328 University of California Puhlications in Zoology [Vol. 13 



appressed. Dorsal cilia forming a well -developed series, basal ones 

 stouter and spinelike, but not as strongly contrasted with others 

 as in Ciconiae. Proximal barbules (pi. 21, fig. 28cZ) also thin and 

 filmlike, with little pigment; base unusually slender, about 0.65 

 by 0.04 mm. Proximal two ventral teeth broad, lobate, and blunt, 

 followed by two or three narrow and pointed ones; pennulum little 

 shorter than base, with rudimentary barbicels always showing. 



Outer vane. — Distal barbules (pi. 21, fig. 28e) with drawn-out 

 points of ventral teeth more prominent ; booklets even more slender, 

 and increased in number; dorsal barbicels absent. Proximal bar- 

 bules on outer portion of barb with ventral teeth proliferated and 

 transformed into straight ventral barbicels, resembling teeth of a 

 comb (pi. 21, fig. 28/). 



(2) Other Feathers 



As in nearly all ducks, greater wing coverts form a speculum 

 of different color from rest of wing, in this case deep bluish violet. 

 For production of this color, as of other metallic colors, e. g., blues 

 and greens of various species, the pennula are transformed into 

 flattened refrangent surfaces (pi. 21, fig. 28*) with constrictions 

 between cells, and fine, longitudinal striations on cells, which are 

 deeply pigmented with black. Base and booklet region considerably 

 reduced in these metamorphosed barbules. Barbules of inner vane 

 of speculum feathers, and proximals of outer vane also, unmodified. 

 As described at close of Part I (p. 279), modifications of distal 

 barbules are absent in albinos. 



Body feathers rather loose in texture, due largely to fact that 

 bases of barbules lie in vertical plane, leaving wide spaces between 

 them. Ventral teeth of distal barbules greatly reduced, but slender, 

 subequal cilia still numerous and well formed. Just distal to hook- 

 let region, pennulum twists so that ventral cilia come to project 

 dorsally. Proximals have slender, tapering bases, inconspicuous 

 ventral teeth and rudimentary prong-like cilia. The poorly de- 

 veloped tail feathers intermediate in form between remiges and body 

 feathers. Their form is shown by plate 21, figures 28gr and li. 



b) Other Types 



The minute structure of the feathers is remarkably constant in 

 all the members of the Anseres. Nettion caroUnense is perhaps 

 slightly more typical of the group in that the ventral teeth of the 

 distal barbules are greatly elongated and slender, as shown in plate 

 21, figure 29a. Marila, Mergus, Querquedula and other genera are 

 almost identical with Nettion. 



Branta, like Anas, has the ventral teeth of the distals somewhat 

 shorter, while some of the feathers have the pennula of the distals 

 of the outer vane elongated with long brushlike cilia to produce the 

 characteristic plush-like effect. Chen very closely resembles Branta, 



