_True Rattlesnakes._--There are twelve species of these reptiles in the United States, all of which, with but two exceptions, live west of the Mississippi. They vary very greatly in color, but the common eastern forms generally have alternate transverse yellow and brownish-black marks over their bodies. All possess rattles. The body of the snake is thick in proportion to its length, and the head, which is more or less diamond-shaped, is much larger than, and is quite distinct from the neck. The pupils of the eye are elliptical--a peculiarity which the pit-vipers alone possess of all the North American snakes. Between the eye and nose there is a comparatively deep depression or pit which gives to this group of snakes their name. There are two large, exceedingly sharp fangs in the front of the mouth, in the position of a dog's canine teeth, that are folded up against the roof of the mouth when the snake is in repose;--being brought forward in a position for stabbing as the serpent strikes. The scales on the under surface of the body back of the anus do not divide along the middle line into two rows, as in harmless snakes. _Ground Rattlesnakes._--There are two species of the pygmy or ground-rattlesnakes. They attain to a length of only about twenty inches, and present the general characteristics of the true rattlesnakes, with the exception that the rattle is small, consisting of but one single button at the end of the tail. These serpents are exceedingly vicious, and usually bite without warning. Contrary to the general opinion, however, the wounds they inflict are rarely, or never, followed by serious consequences in man. One species is southern. The other occurs from Ohio to Nebraska, where it is called massasauga. _Cotton-Mouth Moccasin._--The largest specimens of the cotton-mouth moccasin attain to a length of about six feet. The full grown reptile is of a dingy brownish-black color, but the young are pinkish, with coppery bands running transversely across the body. With the exception that this reptile has no rattles, it answers in its general peculiarities to the description already given of its near relatives the rattlesnakes. The cotton-mouth moccasin is semi-aquatic, being found around the edges of streams and other bodies of water. _The Copper-head, or Highland Moccasin._--This serpent is found from Florida and Illinois to southern Massachusetts; also in parts of Texas. The largest specimens have a length of about three feet. They resemble the cotton-mouth moccasin in their general peculiarities, being, however, somewhat lighter in color. The head has a coppery tinge, from which the snake gets its name, while the body is of a brownish color, with transverse Y-shaped bands of reddish-brown. Its favorite habitat is rocky hill-sides and the banks of mountain water-courses.