140 
SEXUAL SELECTION : BIKDS. 
par 11 
deeper indentation at the divergent than at the 
coP' 
vergent end. It is also manifest that if the conver 
rtreflO® 
let* 
V 
were strongly pronounced and the confluence coinp : 
the indentation at the convergent end would tend to 
quite obliterated. 
The tail-feathers in both species of peacock at® ‘'j 
tirely destitute of ocelli, and this apparently is rek^ 
to their being covered up and concealed by the 1° * 
tail-coverts. In this respect they differ remarkably ^ 
the tail-feathers of Pol vplectron, which in most of ^ 
species are ornamented with larger ocelli than those - 6 
the tail-coverts. Hence I was led carefully to exam 11 ' 
the tail-feathers of the several species of Polyple f ' tr ( 
iii order to discover whether the ocelli in any of o J<? > 
shewed any tendency to disappear, and, to mv g ie . 
satisfaction, I was successful. The central tail-feat^’' 
of P. Najtoleonis have the two ocelli on each side oi 
shaft perfectly developed ; but the inner ocellus be<5 oI °?, 
less and less conspicuous ou the more exterior ^ 
feathers, until a mere shadow or rudimentary vestig 6 
left on the inner side of the outermost feather. Ag 1 *' 
A 
i0^ 
in P. malaceense , the ocelli on the tail-coverts arc, a® 
have seen, confluent ; and these feathers are of uu" b , 
length, being two-thirds of the length of the ta 
\W 
thers, so that in both these respects they resemble ^ 
tail-coverts of the peacock. Now in this species th® ^ 
central tail-feathers alone are ornamented, each with 
brightly-coloured ocelli, the ocelli havii 
vmg compl e * e .j, 
disappeared from the inner sides of all the other ^ 
feathers. Consequently the tail-coverts and tail-feat 1 '^ 
of this species of Polyplectron make a near app r ° a< g 
in structure and ornamentation to the correspond 
feathers of the peacock. * 
As far, then, as the principle of gradation thr°'J 
light on the steps by which the magnificent train 
the peacock has been acquired, hardly anything lllL ' 
