(7, Fig. 15), with teeth in the roof of his mouth. But perhaps his tongue is the most curious of all, for instead of being fixed at the back, and free in the front, as in most other animals, the root of it is fastened to the front of his lower jaw, and the tip lies back in his mouth, so that when he wishes to catch an insect he throws his tongue quickly forward, captures his prey on the sticky point, and flings it back down his throat. So he hops about the summer long, if he can only escape from ducks and rats and other frog-eating animals. He often takes to the water, for he can fill his lungs with air and use it very slowly, and, moreover, his soft skin is of great use to him in still breathing in the water or in the moist air; and when winter comes he takes refuge with many others at the bottom of the pond, and sinks into a state of torpor, till the spring brings croaking and egg-laying time round again. [Illustration: Fig. 16. The Common Smooth Newt[56]--male and young in the water; female on the bank.] Our little frog, then, is truly an animal with a double life, a genuine amphibian,[57] meaning by this, not merely an animal that can swim in the water and move on land, for seals and water-rats, white bears and hippopotamuses, can do this, but one that in the early part of its life would die if taken out of the water, while afterwards it lives and breathes in the air. [Illustration: Fig. 17. Proteus of the Carniola caverns,[58] with its external breathing gills.--(_Adapted from Brehm._)]