The white on this small crescent caught my eye as unusual. Consulting the field guide in the trunk of my car, I thought it might be a Painted Crescent. Now that I'm home, I think it looks more like a Phaon Crescent. It is outside the normal range for either species. And naturally I was unable to relocate it for collection purposes (although I am the master of tearing off the wingtips of small butterflies while trying to pin them).

Anyway, can anybody make a diagnosis? Sorry for the poor quality of the ventral shot - it didn't give me many opportunities and the wind was blowing...