Common Snapping Turtle (Chelydra serpentina) fem.

5/28/12 PL DE - From the time I went out with the camera she never moved, except to roll one eye around at me from time to time.
http://en.wikipedia.org/wiki/Common_snapping_turtle
http://www.discoverlife.org/mp/20q?search=Chelydra
http://www.tortoisetrust.org/articles/snappers.htm