380 University of California Publications in Zoology TVor,. 13 



Pici ; bases of down barbules with villi on ventral edge in Trochili- 

 dae and Pici (except Galbulidae). 



13. Order PASSERIFORMES 



Although containing nearly one-half of all known birds, this 

 order forms a very compact group, all the members of which are 

 so closely related that the entire order is hardly more diverse in 

 its forms than is a single suborder in other groups, and although 

 they are divided into numerous families, these have hardly more 

 than generic or supergeneric value as compared with families in 

 most other groups. As would be expected, the feather structure 

 varies but little in the different forms, in this regard the Passi- 

 formes being in sharp contrast to the Coraciiformes. 



In all of the Passeriformes the plumules are very sparse in the 

 apteria, or are absent entirely. The aftershaft, though sometimes 

 rudimentary or absent, is usually present, being composed of a few 

 long, straggly barbs, and a very short shaft. 



a) Cyanocitta stelleri 

 (1) Remex 



Shaft about as broad as deep, the median groove small and 

 inconspicuous, striations on sides at junction of barbs inconspicuous 

 or absent. Pith of rami only a single cell thick, the vanules set 

 low, ventral ridge well developed, with smooth ventral edge. 

 Vanules each with about same number of barbules, about 28 in each. 



Inner vane. — Distal tarhules (pi. 33, fig. 92a) of same type as in 

 Melanerpes formicivorus (compare plate 33, figure 89a with plate 

 33, figure 92a). Base very large and elongate, about 0.35 by 0.035 

 mm., the broad, filmlike, subnuclear area curving in just proximal to 

 ventral teeth, so that at this point the base is very narrow; ventral 

 teeth small and slender. Pennulum relatively very small, less than 

 half length of base; booklets 3 or 4 in number, small, subequal, 

 and never with prongs; ventral cilia small, more or less appressed 

 to pennulum, and inconspicuous; dorsal cilia short and spinelike, 

 the basal two somewhat enlarged, but not lobate. Proximal barhules 

 (pi. 33, fig. 926) with base relatively small compared with that of 

 distals, about 0.37 mm. by 0.035 mm., the ventral edge scalloped 

 more or less, ventral teeth short, pointed, and inconspicuous; pen- 

 nulum moderately flattened, about two-thirds as long as base. 



Outer vane. — Distal harhules (pi. 33, fig. 92c) with much shorter 

 and broader base than in inner vane, about 0.22 mm. by 0.04 mm., 

 the broad subnuclear area as in the inner vane but curved more 

 conspicuously towards next succeeding barbule. Pennulum rela- 

 tively longer, booklets similar, ventral teeth better developed, larger 

 distally on barbule, as in trogons and Pici. Proximal harhules 



