The rest of the _Crotalidæ_ are American, and consist of the famous Rattlesnakes and their immediate kindred. In the genus _Cenchris_ the tail ends with a spine, and the tip of the tail has several rows of scales beneath. The well-known "Copperhead" (_C. contortrix_) belongs to this genus, and the black "Water Viper" (_C. piscivorus_). The last has bred repeatedly in the London Zoological Gardens, and is rather a large species, of very aquatic propensities. "The Copperhead," according to Dekay, "is a vicious reptile, and its venom is justly dreaded, being considered as deadly as that of the Rattlesnake; and an instance is recorded in which a Horse, struck by one of these reptiles, died in a few hours. Its motions are sluggish, and when approached it assumes a threatening aspect, raising its head and darting out its tongue. It chiefly occurs in pastures and low meadow grounds, feeding on Field-mice, Frogs, and the smaller disabled birds." The poison of the black Water Viper is equally to be dreaded. The true Rattlesnakes have the tail furnished with the extraordinary appendages at its tip which will be described presently. According to differences in the shields and scales covering the head, Dr. Gray arranged them into three genera--_Crotalophorus_, with three species; _Uropsophus_, with one; and _Crotalus_ also with one, _C. horridus_, which appears to be the only one known in South America. Of the common Northern Rattlesnake (_Uropsophus durissus_), Dekay remarks that, "although furnished with such deadly weapons, the Rattlesnake can scarcely be termed a vicious animal, for he rarely strikes unless almost trodden upon. When suddenly disturbed, he throws himself into a coil, and warns the aggressor by rapidly vibrating his rattles, which, however, can scarcely be heard beyond the distance of a few yards. This is most usually the case, but they occasionally strike without the slightest warning. At the moment the Snake strikes, he ejects the venom forcibly into the wound. In an instance of a very large Rattlesnake from Florida (_C. horridus_), which was irritated, he struck violently against the iron wire on the side of the cage, and spurted the venom to the distance of three feet."[16] The fibulæ, or rattles, seldom exceed fifteen in number, and are rarely so many.] [16] We have seen a Cobra thus spurt its venom against the plate-glass cover of the box in which it was kept.--ED.