Casual photo of man - in U.S.?

Casual photo in the collection of the family of Henry Barnes (born 1843 in London U.K.) and Deborah Connell (born about 1846 in London or Ireland). The couple were married in London in 1867. The man in the picture bears a family resemblance to photos of their sons, and seems to be the same man as the subject of a studio portrait photo we have which was taken by Allen & Rowell in Boston, Mass. His surname might be Barnes or Connell.

It is thought the photo is of a family member who emigrated to the U.S. from England (London) or possibly Ireland. We would love to know his identity...