Common Map Turtle (Graptemys geographica)
Description: Females 7 - 10¾ inches, males 3½ - 6¼ inches. Common Map Turtles have a dark olive or brown upper shell (carapace). Young Common Map Turtles have a map-like pattern of light colored lines on the shell, and a row of saw-toothed knobs down the center of the back. As they age, the "map" will fade, and the knobs will wear down. Adult male Common Map Turtles usually keep pronounced knobs, but they may be very hard to detect in large females. The bottom shell (plastron) is light colored, but may have a dark irregular pattern on it. The head is dark colored, with a pattern of light colored lines, and a small spot behind each eye.
Similar Species: False Map Turtles have a thin line behind each eye that extends to the top of the head, and then turns and runs down the neck. Ouachita Map Turtles have a large spot behind the eye, under the eye, and on the lower jaw.