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 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 colour with scattered brown dots, and the lower surface
is often quite plain. (44. Bell, History of British Reptiles, 2nd
ed., 1849, pp. 146, 151.) 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 have
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 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, the Phryniscus nigricans (45. Zoology of the
Voyage of the Beagle, 1843. Bell, ibid. p. 49.), 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 colours are probably beneficial by making this animal
known to all birds of prey as a nauseous mouthful.
In Nicaragua there is a little frog dressed in a bright livery of red
and blue which does not conceal itself like most other species, but
hops about during the daytime, and Mr. Belt says (46. The Naturalist
in Nicaragua, 1874, p. 321.) that as soon as he saw its happy sense of
security, he felt sure that it was uneatable. After several trials he
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