R. cornuta, or the horned toad, is dis tinguished by two sharp horns on its head, or rather by so peculiar a structure of the upper lids of its eyes, as to produce the resemblance of horns. Its mouth is of a most extravagant width, and in the whole list of amphibious animals it is difficult perhaps to point out one equally calcu lated by deformity and ugliness to excite disgust. It is found only in South Ame rica.
R. pipa, or the Surinam toad, is much larger than the common toad, being some times seven inches in length. This ani mal is almost equally loathsome with the last, and is distinguished particularly by that curious deviation from the general course of nature, the exclusion of its young from its back, which contains a va riety of cells for their residence, and a certain degree of maturation. It appears however, that the ova are first deposited on the margin of some stagnant water, and afterwards, with great care, collect ed on the back of the female, and pressed into the cells, which are at particular sea sons opened for their reception, and im mediately on receiving them close over them. Here the young, from the egg state to that of the tadpole, and from the lat ter to the form of the perfect animal, and after the expiration of three months from their inclosure, are dislodged in this ma tured state. In the space of five day* one female has been seen to exclude in this manner seventrfive young ones. R. temporania, or frog, is met with almost' every were throughout Europe, in low and wet situations, where it can pro cure that food on which it principally subsists, worms and insects. During the' heat of summer it generally resides in wa ter, and is able to swim with great dex terity, its hind feet being ffirnished with strong webs, admirably adapted for this • exercise, and in winter it remains imbed ded in the muddy bottoms of pools, or lodges in deep recesses in their banks, in a state of torpor, from which it is revived by the influence of spring. In March it deposits an accumulation of transparent ova, from which, within about a month are hatched tadpoles, every egg in the mean time advancing daily in size, so that before the expiration of this period, these tadpoles may be clearly seen struggling in the viscous fluid which surrounds them. When first hatched they subsist on the remainder of this glutinous fluid. These animals appear to possess little more than head and tail, and exhibit a singular con trast to the form of the animal which they are destined perfectly to resemble. The internal structure of the old and young is little less different, than their external ap pearance. These animals live to the age
of twelve or fifteen years, and do not at tain their maturity before their fifth year. They will survive the amputation of sever. al of their organs, and of consequence must possess a strong principle of vitality. They are fond of basking in the sun, can not well dispense with water for any con siderable time, and are incapable of sus taining rigorous cold. See Amphibia, Plate II. fig. 1.
R. esculenta, or green frog, is much larger than the last species, and abounds in many countries of Europe, though but rarely to be found in England. These ani mals croak so loudly as to be heard at a very great distance, and to produce great annoyance. They are extremely voraci ous, and will occasionally seize small birds, and chickens and docks when very young, swallowing them entire. They are in some places much used for food, par ticularly in France, and thought fittest for the table in the month of June.
It. catesbeiana, or the bull-frog, is found in North America, and grows tothe length of eighteen inches from the nose to the hind feet. Its sounds resemble the low ing of a bull. In Virginia these frogs are supposed to be great purifiers of the water. On being surprised by the travel ler, they make two or three leaps, and plunge into the water, where they are se cure from molestation. They are highly rapacious, often committing great depre dations on the poultry.
R. paradoxa, or the paradoxical frog, is of the size of the frog of Europe, and is found chiefly in America, and particu larly in Surinam. It is remarkable for the circumstance, of the tadpole bearing a greater proportion to the size of the pa.
rent animal than in any other species_ This proportion, indeed, is truly extraor dinary and curious.
R. zebra, or the zebra frog, is a native of Carolina and Virginia, and is by far the largest of the slender bodied frogs. It is of a pale reddish brown, and beauti fully marked, transversely, on the back and limbs, with bars of a chesnut colour. R. arborea, or tree frog, is not found in Great Britain, but is met with in vari ous other parts of Europe, and in ele gance and activity is superior to every other European species. In summer it resides in the woods, and haunts the trees in quest of insects, which it approaches on its belly, in the same manner as a cat to a mouse, and at length seizes with an elastic and instantaneous spring. It is par ticularly noisy on the approach of rain. In winter it takes up its abode in the bot toms of the waters, remaining till the sprinein a state of torpor.