Looks like a spiny to me. Only my opinion though. Spiny's have small projections on the upper lip of the carapace directly above the neck. Check and see, but from your picture it looks like a spiny.
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roomates:
anery corn "zepplin"
normal corn "little bub"
eastern garter "auspicious"
broad-banded watersnake "washington"
Australian Cattle Dog "Pounder"