Chap. XII. 
FISHES. 
15 
males, whilst immature, resembling the mature females ; 
— and, lastly, from the males, even of those species 
which at all other times of the year are identical in 
colour with the females, often acquiring brilliant tints 
during the spawning-season. We know that the males 
are ardent in their courtship and sometimes fight despe- 
rately together. If we may assume that the females 
have the power of exerting a choice and of selecting the 
more highly-ornamented males, all the above facts 
become intelligible through the principle of sexual 
selection. On the other hand, if the females habi- 
tually deposited and left their ova to be fertilised by 
the first male which chanced to approach, this fact 
would be fatal to the efficiency of sexual selection ; for 
there could be no choice of a partner. But, as fai- 
ns is known, the female never willingly spawns except 
in the close presence cf a male, and the male never 
fertilises the ova except in the close presence of 
n female. It is obviously difficult to obtain direct 
evidence with respect to female fishes selecting 
their partners. An excellent observer who carefully 
watched the spawning of minnows {Ctjprinus phoxinus), 
remarks that owing to the males, which were ten times 
as numerous as the females, crowding closely round 
them, he could speak only doubtfully on their opera- 
tions. When a female came among a number of 
males they immediately pursued her ; if she was not 
ready for shedding her spawn, she made a precipitate 
retreat ; but if she was ready, she came boldly in 
among them, and was immediately pressed closely by 
a male on each side ; and when they had been in that 
“ situation a short time, were superseded by other two, 
who wedged themselves in between them and the 
‘ Loudon’s ‘ Mag. of Nat. Flist.’ vol. v. 1832, p. 681. 
