What is this fella?

[bagsmom]

Is that circle thing by the ear much larger on the male?

 

[addy1]

per the net

• Male frogs have vocal sacs
  When male frogs call, their throat region usually expands as their vocal sac fills with air, amplifying their call. Because of this, when not calling, males tend to have obviously thin, baggy skin on their throat. This skin is also usually a different colour to their belly (often yellow or black).

Female frogs are generally bigger than males

 

[BKHpondcritters]

Is that circle thing by the ear much larger on the male?

yes - My 'Reptiles & Amphibians' ID book tells me that the male's tympanum is about twice the diameter of their eye. The female's is about the same size as their eye, so... looking at my picture I can absolutely see that. I'm just foggier on the whole size-thing when I only see one of them.

But, looking at your pictures again, I'd agree -- female.