Chap. XII. . FISHES. 7 



strong and voracious fishes, we may suspect that the 

 males require their sharp teeth for fighting with their 

 rivals ; but as they possess many parts modified and 

 adapted for the prehension of the female, it is possible 

 that their teeth may be used for this purpose. 



In regard to size, M. Carbonnier ^"^ maintains that 

 with almost all fishes the female is larger than the male ; 

 and Dr. G anther does 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 the female. As with many kinds of fishes the 

 males habitually fight together; it is surprising that 

 they have not generally become through tlie effects of 

 sexual selection larger and stronger than the females. 

 The males suffer from their small size, for according 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 fiohtins^ with 

 other males ; and this perhaps is to allow of the pro- 

 duction of a vast number of ova. 



In many species the male alone is ornamented witli 

 bright colours ; or these are much brighter in the male 

 than the female. The male, also, is sometimes provided 

 with appendages 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 great kiiidness of Dr. Giinther. 

 There is reason to suspect that many tropical fishes 

 differ sexually in colour and structure ; and there are 

 some striking cases with our British fishes. The male 

 Callionymus lyra has been called the gemmeou^ drdgonet\ /"^ 



10 As quoted in ' The Farmer,' 1868, p. 3S^.C^ o < 



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