Chap. XII. AMPHIBIANS. 25 



with muscles, and tlierefore cannot be used for loco- 

 motion. As during the season of courtship it becomes 

 edged with bright colours, it serves, there can hardly 

 be a doubt, as 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 com- 

 mon little newt {Triton jpunctatus) is *' brownish-grey 

 " above, passing into yellow beneath, which in the 

 " spring becomes a rich bright orange, marked every- 

 " where 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 colour with 

 scattered brown dots; and the lower surface is often 

 quite plain.^^ The young are obscurely tinted. The 

 ova are fertilised during the act of deposition and 

 are not subsequently tended by either parent. We 

 may therefore conclude that the males acquired their 

 strongly-marked colours and ornamental appendages 

 throuirh sexual selection ; these beino- transmitted either 

 to the male offspring alone or to both sexes. 



Anura or Batrachia. — With many frogs and toads 

 the colours 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 coloured toad which I ever saw, namely 

 the Phryniscus nigricans,'^^ had the whole upper surface 

 of the bodv as black as ink, with the soles of the feet 

 and parts of the abdomen spotted -with the brightest 

 vermilion. It crawled about the bare sandy or open 

 grassy })lains of La Plata under a scorching sun, and 



39 Bell, ibid. p. 146, 151. 



^0 ' Zoology of the Voyage of the " Beagle," ' 1843. " Eeptiles," by 

 Mr. Bel], p. 49. 



