SEXUAL SELECTION 437 



the male is actually larger than the female. With some 

 Cjprinodonts the male is not even half as large. As in 

 many kinds of fishes the males habitually fight together, 

 it is surprising that they have not generally become larger 

 and stronger than the females through the efEects of sexual 

 selection. The males suffer from their small size, for, ac- 

 cording to M. Carbonnier, they are liable to be devoured 

 by the females of their own species when carnivorous, and 

 no doubt by other species. Increased size must be in some 

 manner of more importance to the females than strength 

 and size are to the males for fighting with other males; 

 and this perhaps is to allow of the production of a 

 vast number of ova. 



In many species the male alone is ornamented with bright 

 colors; or these are much brighter in the male than in the 

 female. The male, also, is sometimes provided with ap- 

 pendages which appear to be of no more use to him for 

 the ordinary purposes of life than are the tail feathers to 

 the peacock. I am indebted for most of the following facts 

 to the kindness of Dr. Griinther. There is reason to suspect 

 that many tropical fishes differ sexually in color and struc- 

 ture; and there are some striking cases with our British 

 fishes. The male Callionymus lyra has been called the 

 gemmeous dragonet "from its brilliant, gem-like colors." 

 "When fresh caught from the sea the body is yellow of 

 various shades, striped and spotted with vivid blue on the 

 head; the dorsal fins are pale brown with dark longitudinal 

 bands; the ventral, caudal and anal fins being bluish black. 

 The female, or sordid dragonet, was considered by Linnseus, 

 and by many subsequent naturalists, as a distinct species; it 

 is of a dingy reddish brown, with the dorsal fin brown and 

 the other fins white. The sexes differ also in the propor- 

 tional size of the head and mouth, and in the position of the 

 eye;" but the most striking difference is the extraordinary 

 elongation in the male (Fig. 29) of the dorsal fin. Mr. W. 



'* I have drawn up tUs description from Tarrell's "British Fishes," vol. 1., 

 1836, pp. 261 and 266. 



