Rattlesnakes belong to the group known as the pit vipers, which includes the cottonmouths and the copperheads. The latter do not occur in the desert, so they do not come within the province of this publication. Snakes of the pit viper group are characterized by a noticeable depression, or pit, found almost halfway between the eye and the nostril, but slightly lower, on each side of the head. Of the several species found in the desert, some, such as the western diamondback rattlesnake have a wide range, while others are restricted to limited areas. Some species attain large size, while others are quite small; some are inclined to be pugnacious, while others are more or less docile. All are dangerous! It is not within the scope of this publication to enter into a discussion of the many species, so the reader who wishes to pursue that subject further is referred to Klauber’s publication on the rattlesnakes[10]. _The Sidewinder_ There is one rattlesnake of the desert that should be especially mentioned: the sidewinder, or the little horned rattlesnake. It is called sidewinder because of the peculiar method of locomotion that enables it to progress in the sandy habitat which it frequents. Unable to get sufficient traction in loose sand by moving as other snakes do, it throws a portion of its body ahead as a loop, thus serving to anchor or pull the rest of the body ahead. Thus it progresses sideways in a looping, or winding, motion most interesting to observe. [Illustration: _Sidewinder or “horned” rattlesnake_] Although the term sidewinder is often used loosely in referring to other species of rattlesnakes, it actually applies only to this particular species—_Crotalus cerastes_. _Helpful precautions_ In snake country, it is important to take a flashlight along whenever there is occasion to go outside at night in summer to be sure that there are no rattlesnakes lying across your path. If you sleep out of doors. keep your bed off the ground if possible. The widely believed statement that, “a rattlesnake will not crawl across a hair rope” is not true, although such a statement will often precipitate an argument. Persons much in the field should provide themselves with a suction-type snakebite kit, and should know how to use it. Although you stand 200 chances of being killed by an automobile to one of dying from snakebite, the price of a suction-type kit is cheap insurance against that possibility. _First aid for rattlesnake bite_ _If, in spite of all precautions, you or some companion should be bitten by a rattlesnake, first-aid should be rendered at once. This is not_ _difficult if you have a snakebite kit, and it is possible even if you do not._ _The following steps are quite universally accepted:_