1916] Chandler: Structure of Feathers 287 
(pl. 18, fig. 2c) differ only in their shortness, reaching a length 
of considerably less than 1 mm., the width and flattened ribbon-like 
form remaining the same. In the nestling feathers many of the 
barbs bear barbules only near the base, the terminal portion being 
extended hairlike or expanded into a more or less curled, flattened 
plate (pl. 18, fig 2d). Duerden (1911) gives an interesting account 
of the sequence in the plumages of ostriches. 
b) Relationships 
As has been shown, the feather structure of ostriches seems to 
indicate a primitive rather than a degenerate condition. Their 
wings, which have no specialized pennaceous remiges, and could 
have no lifting function, are used for aiding the bird in running 
against the wind, as suggested by Beebe (1904). This use is highly 
suggestive of a possible course of evolution of flight. When once the 
remiges had become pennaceous, nothing further would stand in 
the way of their being used for true flight. Beebe (1904) looks 
upon this use of the wings as a half return to the lifting function 
of the wings in the flying ancestors which he assumes for the 
eroup, a view which seems to me to involve so complicated a path 
of evolution as to require very strong positive evidence to support it. 
‘ 
The same author remarks that ‘‘vestiges of barbicels’’ can easily 
be distinguished. He evidently considered the downy feathers of 
ostriches as being derived from pennaceous feathers, though nothing 
in their structure or arrangement, it seems to me, need be inter- 
preted as suggesting this. The barbules, while less specialized 
than typical pennaceous barbules and more specialized than simple 
down barbules, are not intermediate, and might be more easily 
looked upon as marking the end of a short path of evolution of 
their own, than as degenerate forms of either of the other types. 
If the contour feathers of ostriches are not derivatives of pennaceous 
feathers, then ostriches are not descendants of flight birds, and their 
striking primitive characters need not be looked upon as secondarily 
acquired. The absence of plumules, filoplumes, and aftershafts, the 
even distribution of feathers over the entire body, and the similarity 
of the neossoptiles to the teleoptiles, as well as the general form of 
the barbules, all suggest the possibility of the ostriches not being 
derived from birds with pennaceous feathers, and therefore not 
from flight birds. 
