The common Northern Rattlesnake sometimes attains to six feet in length, the middle being about the size of a man's leg; the colour of the back is grey, mixed with yellow. Upon this foundation extends a longitudinal row of black spots, bordered with white; towards the muzzle the flat head is covered with six scales larger than the others, and disposed in three transverse rows, each formed of two scales. The males are smaller, much more brightly and less darkly coloured than the other sex. The very long and visible fangs are situated in front of the upper jaw. The scales on the back are oval, and raised in the middle by a bone which extends in the direction of their greatest diameter. The underpart of the body is furnished with a single row of large plates. The Rattlesnake owes its name to a remarkable peculiarity in its structure; the extremity of the tail is furnished with small horny cells, articulated one into the other. When the animal advances these little capsules resound slightly, like the dry husks of beans which still retain their seeds, thus giving notice of the approach of this terrible enemy. The sibilant rattle of these appendages is not very loud, but it may be heard about thirty paces off, and announces the approach of the reptile while it is still at that distance. [Illustration: Fig. 20.--Northern Rattlesnake (_Uropsophus durissus_).] Rattlesnakes feed on small mammals and upon other reptiles, waiting patiently for their approach; when close to them, the Rattlesnake throws itself upon them. They are oviparous; and for some time after they are hatched, the young are said to seek a refuge in the mouth of their mother. During summer Rattlesnakes remain in the midst of stony mountains, uncultivated places, or places covered with wild wood; they generally choose those parts most exposed to the heat,--the sunny shores of a fountain or stream where small animals come to drink. They like also to place themselves under the shadow of an old fallen tree. Audubon, the celebrated ornithologist, says that he has often met with Rattlesnakes rolled up in a state of torpor when the temperature was low. Rattlesnakes are revered by some of the American natives, who know how to lure them from their houses without killing them; for it is a singular fact that this terrible animal is not insensible to the sound of music. Chateaubriand's remarks will be read with interest: "In the month of July, 1791," says this celebrated writer, "we were travelling in Upper Canada with some savage families of the Ounoutagnes. One day, when we had stopped in a plain on the banks of the river Genedie, a Rattlesnake entered our camp. We had a Canadian amongst us who played on the flute; wishing to amuse us, he approached the animal with this new kind of weapon. At the approach of his enemy, the splendid reptile at once coiled itself up spirally, flattened its head, puffed out its cheeks, contracted its ears, and showed its envenomed fangs, while its