Hypsiglena

Hypsiglena is a genus of small, rear-fanged, colubrid snakes commonly referred to as night snakes. The genus consists of nine species, and subspecies have been maintained pending further investigation.
Species and subspecies.
The following species and subspecies are recognized as being valid.
"Nota bene": A binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than "Hypsiglena".
Geographic range.
"Hypsiglena" are found throughout the southwestern and western United States, from Texas and Kansas, west to California, north to Washington, and south into Mexico, as well as on islands off the coasts of Mexico.
Habitat.
The preferred habitat of night snakes is semiarid desert regions with rocky and sandy soils.
Description.
Night snakes typically do not exceed a total length (including tail) of . They are slender-bodied with a flattened head, and have small eyes with vertical pupils. Their color varies depending on their locality, often matching the soil color of their native habitat. They occur in various shades of gray, and brown, with dark brown, gray or black blotches on the back and the sides. Many also have distinctive black markings on the neck region.
Behavior.
"Hypsiglena" are nocturnal and terrestrial.
Diet.
The diet of night snakes consists primarily of lizards, but they will also consume smaller snakes, and amphibians.
Venom.
The venom of "Hypsiglena" is not considered to be dangerous to humans.