Chap. XII. 
AMPHIBIANS. 
25 
Avitli muscles, and therefore 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 briglit 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 
through sexual selection ; these being transmitted either 
to the male offspring alone or to both sexes. 
Anura or Batracliia , — 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 Pliryniscus nigricans , had the whole upper surface 
of the body 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 plains of La Plata under a scorching sun, and 
39 Bel], ibid. p. 146, 151. 
^0 ‘ Zoology of the Voyage of the “ Beagle,” ^ 1813. Eeptiles by 
Mr. Bell, p. 49. 
