Bog Turtle

From the U.S. Fish and Wildlife Service:

The bog turtle is North America's smallest turtle (~4 in). Biologists recently spent several days visiting southern Appalachian bogs in western North Carolina, searching for these rare turtles. Measurements were taken and recorded for each turtle found and then each individual was marked so they could be recognized. This is helpful for scientific purposes or if the turtle is found in the possession of poachers. 
http://1.usa.gov/1IWnaiv

Photo: Gary Peeples, FWS.GOV