Crotalus lepidus is a venomous pitviper species found in the southwestern United States and northern central Mexico. Four subspecies are currently recognized, including the nominate subspecies described here. This is a small species that rarely exceeding 32" in length. They have a large, rounded head, and fairly heavy body for their size, with eyes that have vertical pupils. Like other rattlesnakes, their tail has a rattle on it, which is composed of keratin. Each time the snake sheds its skin, a new segment is added to the rattle, but the rattle is fragile and may break off, and the frequency of shedding can vary, so the snake's age cannot be determined by its length or number of segments.