The two key characters --- a plain red belly and light spots at the back of head are usually present, but this snake is subject to great variation. Dorsum normally plain brown except for indications of 4 narrow dark stripes or a broad, fairly light middorsal stripe, or both. Many specimens are gray; a few are black, and in extreme cases the belly may be blue-black. The belly color, normally bright red, may vary through orange to pale yellow. The 3 light nape spots are usually well defined; moderate amount of black pigment on back and sides of head; a light mark on the 5th upper lip scale which is boardered below by black. Scales keeled and in 15 rows; anal divided.