Wenn die Laubfrösche knarren, Magst du auf Regen harren. When the tree-frogs croak, you may wait for rain. Sometimes it does come true. Tree-frogs are not very intelligent, although they have a keen sense of locality; but they are nice pets, being easily kept, and have a pretty appearance. There is a record of one which lived for twenty-two years in confinement. The pairing begins soon after the frogs reappear from their hibernation in the ground; in Germany in the month of May. The congregating males make a great noise and take to the water before the females, which join them when ready to spawn. The male grasps his mate near the shoulders, and the pair swim about together, sometimes for days, until the eggs are expelled. These are laid in small clumps of 800 to 1000, which soon swell up and remain at the bottom of the pond. The larvae are hatched in ten days; two days later the adhesive sucker below the throat appears, and after another two days a pair of thread-like external gills are developed. The tadpoles, which reach a length of 2 inches, owing to the long tail, which is nearly three times as long as the body, metamorphose in about twelve weeks, and the baby tree-frogs, scarcely half an inch in length, hide in the grass for the next two years, until they are about half grown, not reaching maturity until the fourth year. {194}Since many pairs congregate in the same pool, and each produces up to one thousand eggs, most of which are hatched, the neighbouring meadows sometimes literally swarm with tiny tree-frogs. Nevertheless the adults are comparatively rare and are very local. _H. carolinensis_ s. _lateralis_ of the South-Eastern States of North America greatly resembles _H. arborea_ in general appearance, size, and habits. But the head is more pointed, and the vivid green of the upper parts is separated from the yellowish white under surface by a conspicuous, pure white line, giving the little creature a very smart and neat appearance. According to Holbrook, it ascends trees, but most commonly lies upon broad-leaved water-plants, like _Nymphaea_, and in fields of Indian corn. Motionless during the daytime, they emerge in the morning and evening from their hiding-places, and become very brisk and noisy, often repeating their single note, which is not unlike that of a small bell. When one begins, hundreds take it up from all parts of the corn-field. Among other tree-frogs of the South-Eastern States may be mentioned _H. squirella_, 1½ inch in length, which is very changeable in colour, generally olive above with darker spots and bars on the limbs, and with a white upper lip. It lives in trees, sheltering in the bark. _H. femoralis_ of the same size, without the white lip, lives high up in the trees of the dense forests of Georgia and Carolina.