338 THE DESCENT OP MAN. 



the females; and, in the act of courtship, expand their fins, 

 which are spotted and ornamented with brightly colored rays, 

 in the same manner, according to M. Carbonnier, as the peacock. 

 They then also bound about the females with much vivacity, and 

 appear by "I'etalage de leurs vives couleurs chercher a attirer 

 "I'attention des femelles, lesquelles ne paraissaient indiffgrentes 

 "a ce manSge, elles nageaient avec une molle lenteur vers les 

 "males et semblaient se complaire dans leur voisinage." After 

 the male has won his bride, he makes a little disc of froth by 

 blowing air and mucus out of his mouth. He then collects the 

 fertilized ova, dropped by the female, in his mouth; and this 

 caused M. Carbonnier much alarm, as he thought that they were 

 going to be devoured. But the male soon deposits them in the 

 disc of froth, afterwards guarding them, repairing the froth, and 

 taking care of the young when hatched. I mention these par- 

 ticulars because, as we shall presently see, there are fishes, the 

 males of which hatch their eggs in their mouths; and those who 

 do not believe in the principle of gradual evolution might ask 

 how could such a habit have originated; but the difficulty is 

 much diminished when we know that there are fishes which thus 

 collect and carry the eggs; for if delayed by any cause in de- 

 positing them, the habit of hatching them in their mouths might 

 have been acquired. 



To return to our more immediate subject. The case stands 

 thus: female fishes, as far as I can learn, never willingly spawn 

 except in the presence of the males; and the males never fertilize 

 the ova except in the presence of the females. The males fight 

 for the possession of the females. In many species, the males 

 whilst young resemble the females in color; but when adult 

 become much more brilliant, and retain their colors throughout 

 life. In other species the males become brighter than the females 

 and otherwise more highly ornamented, only during the season 

 of love. The males sedulously court the females, and in one 

 case, as we have seen, take pains in displaying their beauty 

 before them. Can it be believed that they would thus act to no 

 purpose during their courtship? And this vrould be the case, 

 unless the females exert some choice and select those males which 

 please or excite them most. If the female exerts such choice, all 

 the above facts on the ornamentation of the males become at once 

 intelligible by the aid of sexual selection. 



"We have next to inquire whether this view of the bright colors 

 of certain male fishes having been acquired through sexual selec- 

 tion can, through the law of the equal transmission of characters 

 to both sexes, be extended to those groups in which the males and 

 females are brilliant in the same, or nearly the same degree and 

 manner. In such a genus as Labrus, which includes some of the 

 most splendid fishes in the world— for instance, the Peacock 



