1916] Chandler: Structure of Feathers 381 
(pl. 33, fig. 92d) similar to those of inner vane, the bases becoming 
shorter on distal third of barbs. At extreme tip, base reduced and 
almost lost, the pennulum weak, with small barbicels on both dorsal 
and ventral sides. 
(2) Other Feathers 
Plumage of back and breast rather hairlike, due to non-coherence 
of barbs on their outer portions, on account of very loose inter- 
locking of barbules. Vanules open, i. e., with wide spaces between 
barbules, due to vertical position of latter and to their wide spacing, 
there being only about 18 or 20 per millimeter on each side. Distal 
barbules (pl. 33, fig. 92e) with narrow tapering bases which have 
ventral part curved slightly toward next succeeding barbule, as in 
remiges; barbicels all greatly reduced or missing, except 2 slender 
but persistent hooklets. Proximal barbules (pl. 33, fig. 92f) with 
no sharp demarcation of base and pennulum, except a bend; form 
narrow, and tapering from slightly expanded proximal portion of 
base all the way to tip; total length about 0.8 mm. 
b) Other Types 
Throughout the group, except in case of color modifications, 
there is very little divergence from this type. In Corvus corax 
the ventral teeth of the distal barbules are more highly developed 
than usual, being rather broad and triangular, and sometimes 
bifureated at the tip; in this species, also, the two basal dorsal cilia 
reach an unusually high degree of development, as in the case of 
Hydrocorax among the Coraciiformes. Proximal barbules of outer 
vane develop ventral cilia only at extreme tip, the ventral teeth in 
these barbules becoming separated from one another, and assuming 
a short spinelike form. 
In the Frigillidae, Bombycillidae, Icteridae, and other families 
more or less closely related to the finches, the distal barbules are 
characterized by the peculiar form of the ventral teeth, which are 
relatively very long and large, being broader at the middle of their 
length than at their base. This character is shown in plate 33, 
figure 94a, representing a distal barbule from the inner vane of a 
remex of Pipilo maculatus. In some genera of the Turdidae, e. g., 
Planesticus, there is a tendency for the distal barbules to adhere to 
each other by means of the greatly elongated ventral teeth which 
behave as if weakly fused with each other into a longitudinal bar, 
not unlike the bar formed by the pennula of the proximal barbules 
in Tinamous. 
In the Tyrannidae, and to a greater or less extent in the 
Mniotiltidae, Vireonidae, Turdidae, and many other allied families, 
