u 
SEXUAL SELECTION. 
Part II. 
orange-coloured stripes, which give it the appearance 
of a Labrus, and the body partakes of a golden-orange 
tinge. The females are dark in colour, and are com- 
monly called black-fish.” An analogous and even 
greater change takes place with the Salmo eriox or bull- 
trout ; the males of the char (8. iimhla) are likewise at 
this season rather brighter in colour than the females.^^ 
The colours of the pike (Esox reticulatus) of the United 
States, especially of the male, become, during the 
breeding-season, exceedingly intense, brilliant, and iri- 
descent.^^ Another striking instance out of many is 
-afforded by the male stickleback (Gasierosteus leiurus), 
which is described by Mr. Warington,^^ as being then 
beautiful beyond description.” The back and eyes of 
the female are simply brown, and the belly white. The 
eyes of the male, on the other hand, are ‘^of the most 
splendid green, having a metallic lustre like the 
green feathers of some humming-birds. The throat 
and belly are of a bright crimson, the back of an 
ashy-green, and the whole fish appears as though it 
were somewhat translucent and glowed with an in- 
ternal incandescence.” After the breeding-season 
these colours all change, the throat and belly become 
of a paler red, the back more green, and the glowing 
tints subside. 
That with fishes there exists some close relation 
between their colours and their sexual functions we can 
■clearly see ; — firstly, from the adult males of certain 
species being differently coloured from the females, and 
often much more brilliantly ; — secondly, from these same 
Yarrell, ‘ British Fishes,’ vol. ii. 1836, p. 10, 12, 35. 
2^ W. Thompson, in ‘ Annals and Mag. of Nat. History,’ vol. vi. 1841, 
p. 440. 
22 ‘ The American AgTicuIturist,’ 1868, p. 100, 
23 ‘ Annals and Mag. of Nat. Hist.’ Oct. 1852. 
