18 SEXUAL SELECTION. [Part IL 



doubt that color lias been acquired by many fishes as a 

 protection : no one can behold the speckled upper surface 

 of a flounder, and overlook its resemblance to the sandy 

 bed of the sea on wliich it lives. One of the most striking 

 instances ever recorded of an animal gaining protection 

 by its color (as far as can be judged in preserved speci- 

 mens) and by its form, is that given by Dr. Gilnther" of 

 a pipe-iish, which, Avith its reddish streaming filaments, is 

 hardly distinguishable from tlie sea-weed to which it 

 clings with its prehensile tail. But the question now 

 under consideration is, whether the females alone have 

 been modified for this object. Fishes ofier valuable evi- 

 dence on this head. We can see that one sex will not be 

 modified through natural selection for the sake of protec- 

 tion more than the other, supposing both to vary, unles^s 

 one sex is exposed for a longer period to danger, or has 

 less power of escaping from such danger than the other 

 sex ; and it docs not appear that with fishes the sexes 

 difler in these respects. As far as there is any difference, 

 the males, from being generally of smaller size, and from 

 wandering more about, are exposed to greater danger 

 than the females ; and yet, when the sexes differ, the 

 males are almost always the most conspicuously colored. 

 The ova are fertilized immediately after being deposited, 

 and when this process lasts for several days, as in the case 

 of the salmoUj^" the female, during the whole time, is at- 

 tended by the male. After the ova are fertilized they are, 

 in most cases, left unprotected by both parents, so that 

 the males and females, as far as oviposition is concerned, 

 are equally exposed to danger, and both are equally im- 

 portant for the jjroduction of fertile ova ; consequently 

 the more or less brightly-colored individuals of either sex 

 would be equally liable to be destroyed or preserved, and 



S9 'Proc. Zoolog. Soc' 1865, p. 327, pis. xiv., xv. 

 *" Yarrcll, 'British Fishes,' vol. il. p. 11. 



