380 University of California Publications in Zoology (Vou. 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 barbules (pl. 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; hooklets 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 barbules 
(pl. 33, fig. 92b) 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 barbules (pl. 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, hooklets similar, ventral teeth better developed, larger 
distally on barbule, as in trogons and Pici. Proximal barbules 
