When I was photographing this butterfly, I noticed that it was smaller than other Monarchs I had photographed. When I got home I checked one of my butterfly books and quickly looked at the Monarch and the Queen which is similiar. It definitely wasn't a Queen and I didn't look any further. Today (8/19) I was reading a birding blog and they mentioned the difference between the Viceroy and the Monarch. Viceroys usually (emphasis usually) have a black line across the hind (or lower) wing. This one has a hint of one, but everywhere I have read, they do say usually. Looking at pictures around the net, I have seen faint and very distinctive. The markings on the fore (upper) wing are definitely consistent with a Viceroy, as are the white dots around the eyes.