Chap. XIII. 
DECORATION. 
73 
elongation would impede the act of flight. Yet the 
beautifully ocellated secondary wing-feathers of the 
male Argus pheasant are nearly three feet in length ; 
and in a small African night-jar {Cosmetornis vexilla- 
rius) one of the primary wing-feathers, during the 
breeding-season, attains a length of twenty-six inches, 
Avhilst the bird itself is only ten inches in length. 
In another closely-allied genus of night-jars, the shafts 
of the elongated wing-feathers are naked, except at 
the extremity, where there is a disc.^^ Again, in 
another genus of nightjars, the tail-feathers are even 
still more prodigiously developed ; so that we see the 
same kind of ornament gained by the males of closely- 
allied birds, through the development of widely different 
feathers. 
It is a curious fact that the feathers of birds belonging 
to distinct groups have been modified in almost exactly 
the same peculiar manner. Thus the wing-feathers 
in one of the above-mentioned night-jars are bare 
along the shaft and terminate in a disc ; or are, as 
they are sometimes called, spoon or racket-shaped. 
Feathers of this kind occur in the tail of a motmot 
(Eumomota super ciliar is) ^ of a king-fisher, finch, hum- 
ming-bird, parrot, several Indian drongos (Dicrurus 
and EdoUus, in one of which the disc stands vertically), 
and in the tail of certain Birds of Paradise. In these 
latter birds, similar feathers, beautifully ocellated^ 
ornament the head, as is likewise the case with some 
gallinaceous birds. In an Indian bustard (SypJieotides 
auritus) the feathers forming the ear-tufts, which are 
about four inches in length, also terminate in discs.^^ 
Sclater, in the ‘ Ibis/ vol. vi. 1864, p. 114. Livingstone, ‘ Expedi-^ 
tion to the Zambesi,* 1865, p. 66. 
Jerdon, ‘Birds of India/ vol. iii. p. 620. 
