332 THE DESCENT OP MAN. 



not know of a single instance in which the male is actually 

 larger than the female. With some Cyprinodonts the male is 

 not, even half as large. As in many Mnds of fishes the males 

 habitually fight together, it is surprising that they have not gen- 

 erally become larger and stronger than the females through the 

 effects of sexual selection. The males suffer from their small 

 size, for according to M. Carbonnier, they are liable to be de- 

 voured by the females of their own species when carnivorous. 



Fig. 29. Callionymus lyra. Upper figure, male; lower figure, female. 

 N. B. The lower figpr© is more reduced than the upper. 



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 m^le alone is ornamented with bright 

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

 The male, also. Is sometimes provided with appendages whici ap- 

 pear 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. Giinther. 

 There is reason to suspect that many tropical fishes differ sexually 

 in color and structure; and there are some striking cases with 

 our British fishes. The male Callionymus lyra has been called 



