Thamnophis butleri

It is a small slender snake, averaging 38-51 cm long, with three yellow to orange stripes along the length of the body. The background color can range from olive-brown to black and it may also be possible to discern two rows of dark spots between the side and back stripes. These features do little to distinguish them from most other garter snakes species, but what is unique to this species is the placement of the lateral, or side, stripes. In Butler's Garter Snakes, the lateral stripes are centered on the third scale row up from the ventral scales, and they also overlap the adjacent second and fourth scale rows. This contrasts with the lateral stripe placement of other garter snake species. (Wikipedia.org)