344 



THE DESCENT OF MAN. 



many insects and spiders, sound-producing instruments have, at 

 least in some cases, been developed through sexual selection, as a 

 means for bringing the sexes together. 



AMPHIBIANS. 



XJrodela. — I will begin with the tailed amphibians. The sexes 

 of salamanders or newts often differ much both in color and 

 structure. In some species prehensile claws are developed on 

 the fore-legs of the males during the breeding-season: and at 

 this season in the male Triton palmipes the hind-feet are pro- 

 vided with a swimming-web, wbich is almost completely absorbed 

 during the winter; so that their feet then resemble those of the 





m 



Fig. 33. Triton cristatus (half natural size, from Bell's 'British Rep- 

 tiles'). Upper figure, male during tlie breeding-season; lower fig- 

 ure, female. 



female." This structure no doubt aids che male in his eager 

 search and pursuit of the female. Whilst courting her he rapidly 

 vibrates the end of his tail. With our common newts (Triton 

 punctatus and cristatus) a deep, much Indented crest is developed 

 along the back and tail of the male during the breeding-season, 

 virhich disappears during the winter. Mr. St. George ilivart in- 

 forms me that it is not furnished with muscles, and theretore can- 

 not be used for locomotion. As during the season of courtship it 

 becomes edged wifn bright colors, there can hardly be a doubt 

 that it is a masculine ornament. In many species the body presents 

 strongly contrasted, though lurid tints, and these become more 

 vivid during the breeding-season. The male, for instance, of our 



'Bell, 'History of British Reptiles,' 2nd edit. 1849, pp. 156-159. 



