24 SEXUAL SELECTION. [Part IL 



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 color with scattered brown 

 dots ; and the lower surface is often quite plain. 39 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 

 acquired their strongly-marked colors and ornamental ap- 

 pendages through sexual selection; these being trans- 

 mitted either to the male offspring alone or to both sexes. 

 Anura or JBatrachia. — With many frogs and toads 

 the colors evidently serve as a protection, such as the 

 bright-green tints of tree-frogs and the obscure mot- 

 tled shades of many terrestrial species. The most con- 

 spicuously-colored toad which I ever saw, namely, the 

 Phryniscus 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 could not fail to catch 

 the eye of every passing creature. These colors may be 

 beneficial by making this toad known to all birds of prey 

 as a nauseous mouthful ; for it is familiar to every one 

 that these animals emit a poisonous secretion, which 

 causes the mouth of a dog to froth, as if attacked by hy- 

 drophobia. I was the more struck with the conspicuous 

 colors of this toad, as close by I found a lizard (Proctotre- 

 tus multimaculatus) which, when frightened, flattened its 

 body, closed its eyes, and then from its mottled tints 

 could hardly be distinguishable from the surrounding 

 Band. 



39 Bell, ibid. pp. 146, 151. 



40 ' Zoology of the Voyage of the " Beagle," ' 1843. " Reptiles," bv 

 Mr. Bell, p. 49. 



