ON July 15, 1928, the writer received from Mrs. Elinor Robson of Des Moines, Iowa, a living female specimen of Graham's watersnake, Natrix grahamii (Baird and Girard). The snake was taken by Mrs. Robson at a pond in one of the city parks. In all available keys the determining of this species depends ultimately upon color characters. This specimen was unusual in that it lacked the expected white of the ventral surface and also the characteristic dark zigzag stripes where the ventral plates meet the lower row of dorsal scales. It was also without the narrow dark longitudinal lines higher up on the sides, and the midventral line or row of spots which the species usually exhibits over at least part of the body length. Following is the description: Length, 675 mm., tail, 130 mm., body width, 20 mm., head width, 10 mm., neck width, 9 mm., tip of head to rear end of parietals, 15 mm.; eyes, brown, prominent, 2.5 mm. in diameter. Scales, 19-17, gastrosteges, 158, urosteges, 54; anal plate, divided. Head, small and rather pointed; rostral, of medium height, dark. Loreal present. Internasals, 2. Supralabials, 7 (4th and 5th on left side incompletely divided, 5th and 6th largest, all dark); infralabials, 9, yellowish white. General color uniform dark brown above, with a barely perceptible, slightly lighter median stripe about three scales wide bordered on each side by a slightly darker line about two scales wide. Ventral plates grayish, each with a transversely placed black border spot partly covered by the rear edge of the preceding plate, best marked toward the anterior end of the body. Spots continued back less noticeably on the urosteges. Median line of belly narrowly light yellowish; tail tip, acute. Very quiet and docile. On September 12 this snake bore ten young, averaging about 216 mm. but ranging from 205 mm. to 230 mm. Of the ten young, four had the exact coloration of the mother, while the remaining six conformed to the color and pattern of typical Natrix grahamii. Of the dark ones, two were the shortest of the brood, measuring 205 mm. and 207 mm., respectively; while one measured 230 mm., making it the longest of all. Are there other records of this color dimorphism in Graham's watersnake? Logier in COPEIA (No. 172, and 1930, No. 1) reports similar data on the color dimorphism of Thamnophis s. sirtalis.