Page:Natural History, Reptiles.djvu/135

Rh "Although I have alluded to the sun's influence as being the means of hastening the evolution of the embryo in the oviparous reptiles, it is not to be concluded that the same source of warmth is unnecessary in the present and similar instances. The only difference is, that in the ovo-viviparous species the solar heat is communicated to the embryo through the medium of the mother; and hence we often see the pregnant female, about the month of June, constantly basking in the sun, and lying in such a position as to expose the body most fully to his influence. Every one who has watched the habits of our native reptiles must have seen the same circumstance in the gravid female of the Common Viper, and may have observed how much more reluctantly and tardily she leaves the genial spot than the male."

Mr. W. C. L. Martin also thus speaks of the agile movements of this pretty and familiar little reptile:—"It is astonishing to see how rapidly, when alarmed, these agile little creatures gain their burrows, or disappear from view, diving beneath the intertangled vegetation: they seem gone in the twinkling of an eye. Not less prompt and rapid are they in catching their prey; the moment an insect comes near them, or settles on a leaf within due distance, their bright eyes mark it; the next instant it is seized and swallowed: the act is wonderfully quick and instantaneous. The sight of these animals is indeed very acute, and their hearing appears also to be by no means deficient; we have seen them on the slightest noise, on the snapping of a branch, or a rustle made among the leaves, dart off to their burrows,