WHITE-TAILED WATTLED PHEASANT 159 
additional tail-feathers are all more or less central and make their appearance anterior 
to the regular line of rectrices, sometimes forcing these out of alignment. In other 
words, the additional feathers are derived from the distal row of upper tail-coverts, 
lengthened and coloured to similate rectrices in the third annual moult. Indeed, as 
we have seen, even the remaining lesser and median coverts are all affected by the 
same tendency, and completely isolated by form and colour from the feathers of the 
rump. I shall speak further of this transformation when describing the second-year 
plumage. 
Specialization is not confined to the number of rectrices, but has very noticeably 
affected their structure. The vanes of all the feathers, while to a certain extent normally 
cohesive, yet show a downy character and softness of texture wholly incompatible with 
any great usefulness in flight. One can see at a glance that the tail is avowedly an 
ornament, with but slight power to perform its more normal function of a rudder. 
Beginning with the central pairs the feathers show splendid wide, symmetrical webs, 
and are similar in character for the inner nine or ten pairs, gradually, however, becoming 
less curved. The outer six, or almost invariably seven pairs become, quite abruptly, 
very different in character. They show almost no curvature, the outer five pairs being 
quite straight, the outer webs becoming exceedingly short, and although the feathers 
rapidly decrease in length toward the outer pairs, yet the shafts of all are much enlarged, 
stiff and spine-like. The most interesting character is the degeneration of the webbing 
on these outer seven pairs. This is faintly indicated on some of the more central 
feathers, whose tips may be rather worn and frayed for 20 mm. or more, but on the 
outer, stiff-shafted feathers it reaches an extreme. Long before I observed the courtship 
(p. 154) I suspected that some such manceuvring must take place to account for the 
worn and broken candition of the tips of the outer quills, but in the case of this 
pheasant (as I have shown in the racket tails of the motmot, “ Zoologica,” New York 
Zoological Society, No. 5, 1910, p. 141), environmental manipulation only goes hand 
in hand with congenital structure. There is great variation in this congenital weakness 
of the web or in its complete absence. In an unsheathed feather sprouting among these 
outer rectrices, the shaft may be wholly bare for 20 or 30 mm., followed by an equal 
area of strongly attached barbs. Or the web may be present for a third of the length 
of the feather and complete down even to the barbicels, and yet its point of attachment 
near the shaft so weak that the whole vane tears away with the removal of the enfolding 
sheath. 
In the full-grown outer tail-feathers of the pheasant, examined in the living bird 
or in a recently shot or trapped specimen, we find the inner web fully developed, while 
the outer is very greatly reduced, up to the very root of the rachis. This reduction 
occurs in two decided nodes or steps. Taking the average of a score of adult males, 
it is first especially noticeable on the fifth from the outer pair where (all measurements 
are 125 mm. from the tips of the feathers) the outer web is 12 mm. in width as compared 
with 25 mm. on the sixth pair of feathers. On the fourth pair, the outer web narrows 
suddenly to only 4 mm., and from this the narrowing is very gradual down to 2°5 mm. 
on the outer pair of rectrices. 
On the terminal portion of the outer feather a most dishevelled and imperfect 
condition of the vane is found. Usually, for the length of 80 to 100 mm. from the tip, 
