Geographic range: Nearctical - Neotropical: S. ravus is native to Mexico. It is found in temperate climates of the following Mexican states: Hidalgo, Mexico, Morelos, Oaxaca, Puebla, Tlaxcala, Veracruz and Federal District.

Physical characteristics: A small sized venomous snake (around 35 cm). Both sexes of similar size. Body color can range from olive brown to dark brown. The characteristic rectangular spots on the back are of much darker shade, usually dark gray to black and count around 30. The ventral part of the body is gray or dark gray in color.

Food habits: Principal food items are lizards of genus Sceloporus and mammals of genus Mus and Microtus. Insects are also consumed.

Reproduction: Very little is known about the reproduction. The species is considered viviparous.

Behavior: S. ravus is a diurnal species foraging usually near the base of bunch grass.

Habitat: Inhabits principally coniferous (especially pine -oak) forests of temperate zones, xeric shrubs and izotal. Also temperate grasslands, cloud forest, high altitude thornscrub and tropical deciduous forest. Prefers to hide in fallen leaves, bunch grass and under stones.

Biomes: temperate forest