mud turtle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various small turtles of the genus Kinosternon of the Americas, having two transverse hinges on the ventral shell and found in slow-moving fresh waters.

from The Century Dictionary.

• noun A name given in the United States to various turtles which live in the mud or muddy water, as species of Trionychidæ and Emydidæ.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun bottom-dwelling freshwater turtle inhabiting muddy rivers of North America and Central America