Well, whatever he is, he is definately a boy! See those long nails? That is a characteristic of males.
It is kind of hard to say but I'd lean towards either a Midland painted turtle or an Eastern. Easterns are one of the most readily identifiable species of turtle in North America because they are the only species who has aligned carapace scutes. For all the non-turtle geeks
this means that the sections on the dome of the shell line up perfectly across the dome horizontally.
It is sometimes one of the only ways to differentiate between Eastern and Midland.
As you can see, the turtle Dena caught doesn't have aligned scutes.
Here is a picture of a Midland Painted from chelonia.org:
And here is an Eastern: As you can see, the scutes are aligned. Easterns also have characteristic yellow dots on the side of their heads -- I couldn't tell from the pictures if yours had this spot, Dena. But maybe if you remember you could clear things up once and for all.
I have Southern and Western Painteds so together we'd almost have a complete set, Dena!!