1916] Chandler: Structure of Feathers 381 



(pi. 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 hack 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 (pi. 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 booklets. Proximal barbules (pi. 33, fig. 92/) 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. 



h) 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 

 bifurcated 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 Coracii formes. 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, 



