SEXUAL SELECTION 453 



season: and at this season in the male Triton palmipes the 

 hind feet are provided with a swimming-web, which is 

 almost completely absorbed during the winter; so that their 

 feet then resemble those of the female." This structure 

 no doubt aids the male in his eager search and pursuit of the 

 female. While 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, which disappears during the winter. Mr. St. George 

 Mivart informs me that it is not furnished with muscles, 

 and therefore cannot be used for locomotion. As during 

 the season of courtship it becomes edged with 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 common 

 little newt {Triton punctatus) is "brownish gray above, pass- 

 ing into yellow beneath, which in the spring becomes a rich 

 bright orange, marked everywhere with round dark spots." 

 The edge of the crest also is then tipped with bright red or 

 violet. The female is usually of a yellowish brown color 

 with scattered brown dots, and the lower surface is often 

 quite plain." The young are obscurely tinted.' The ova 

 are fertilized during the act of deposition, and are not 

 subsequently tended by either parent. We may therefore 

 conclude that the males have acquired their strongly 

 marked colors and ornamental appendages through sexual 

 selection; these being transmitted either to the male oflE- 

 spring alone, or , to both sexes. 



Anv/ra or Batrachia. — With many frogs and toads the 

 colors evidently serve as a protection, such as the bright 

 green tints of tree frogs and the obscure mottled shades of 

 many terrestrial species. The most conspicuously colored 



«» BeU, "ffistoiT of British Reptiles," 2d edit., 184S, pp. 166-169. 

 « IWcL, pp. 146, 151. 



Descent— Vol. 11.-2 



