Although completely lacking in distinctive field marks, the Green Water Snake is unique among our Natrix in having a row of scales between the eye and lip scales (upper labials). This makes indentification positive and final, but it means catching the snake for close up examination. general dorsal coloration may be greenish or brownish, but usually with at least some faint suggestion of a dark pattern on a lighter ground. belly marked with light spots or half moons on a ground color or gray or brown. Scales keeled; anal divided. Similar species: Virtually all other large water snakes usually have a strong indication of pattern,; stripes, spots or blotches; but these may not show well in a basking serpent unless it is wet. Cottonmouth usually moves sluggishly, not dropping or diving into water with alacrity of Water Snakes.