Page:British Reptiles, Amphibians, and Fresh-water Fishes.djvu/43

INTRODUCTION in the adult state, all the seven species of amphibians upon the British List visit water for the purpose of spawning, and their young are at first exclusive water-dwellers. When in the latter state they have gills, and later breathe by means of lungs. Some kinds, however, retain their gills during all their various stages, but none of these occur in Britain. When Frogs and Toads have become mature, and hence have developed lungs, they have the habit of immersing themselves in water with the head just protruding at the surface so as to take in a sufficient supply of air. Even so, they can and do remain well below the surface for quite a long time, and if a pond is frozen in early Spring, and they are imprisoned beneath the ice, they emerge after a thaw none the worse for their adventure. Newts, on the other hand, are much more reconciled to an aquatic life, and although our British species do not possess any gills in the adult state, they appear to experience no difficulty in remaining submerged in the same position under water for hours at a stretch. All the amphibians with which we are concerned have four legs when in the final stage of development, although limbless amphibians do exist, but not in our own country. There are several anatomical features of interest in Frogs, Toads, and Newts, but these need not detain us as, at best, they can only be described in dry-as-dust terms, and that is not the idea aimed at in these popular books, but rather succinct life-stories of the animals under review. Far be it for us to write, for example, that "the hind legs have an 27