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 manoeuvring must take place to account for the 

 worn and broken condition 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, 19 10, 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. 



