Hanging on!

I had a great walk in the Arboretum today and came home with lots of keepers. This little critter was hanging on to the edge of a lily pad in the butterfly garden. Can someone tell me what he is called? Is it a pollywog? If you can tell me, I will add the correct information here. The other pictures from today are in my SmugMug gallery, starting here. Now I am headed for bed. It's way past my Cinderella time.