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The Desert Night Snake is a slender, small to medium-sized snake with adult length typically 25 – 53 cm (COSEWIC 2001). Larger individuals, up to about just over 60 cm long, are occasionally encountered (St. John 2002) and appear to be more common within the northern portion of the species’ range, including British Columbia (COSEWIC 2001, Matsuda et al. 2006). The head is flat and somewhat triangular, and the pupils of the eyes are vertical, indicative of night vision. The body scales lack keels, giving the snake a smooth appearance. The ground colour of the back and sides is tan, grey, or light brown with a distinct pattern of dark brown, almost square-shaped blotches. There is a row of larger blotches along the mid-back and rows of smaller blotches along the sides. The underside is glossy white or yellowish. A dark stripe from the nostril extends across the eye to the neck, forming a facial mask. A dark brown “collar” around the neck, consisting of two or three blotches, is diagnostic (St. John 2002, Matsuda et al. 1986). The Desert Night Snake superficially resembles other sympatric snakes with a blotchy colour pattern. Unlike small Gopher Snakes and juveniles of the much larger Racer with which it may be confused, the Night Snake has vertical rather than rounded pupils; the Western Rattlesnake also has vertical pupils, but the Night Snake has smooth rather than keeled body scales and lacks a rattle at the end of the tail.