. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. 343 The Descent of Man. Part II. Amphibians. Urodela.—I will begin with the tailed amphibians. The sexes of salamanders or newts often diifer much both in colour and structure. In some species prehensile claws are develoiDed 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, which is almost completely absorbed during the winter; so that their feet then resemble. Fig. 32. Triton cris
. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. 343 The Descent of Man. Part II. Amphibians. Urodela.—I will begin with the tailed amphibians. The sexes of salamanders or newts often diifer much both in colour and structure. In some species prehensile claws are develoiDed 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, which is almost completely absorbed during the winter; so that their feet then resemble. Fig. 32. Triton cristatus (half natural size, from Bell's ' British Reptiles '). Upper figure, male during the breeding-season; lower figure, female. those of the female.^^ This structure no doubt aids the 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 (Trito7i pur/ctntus and cristntus) 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 colours, 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-grey above, passing into yellow " Bell, 'History of British Reptiles,' 2nd edit. 1849, pp. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York : D. Appleton and Company
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