I believe the young man at left is the same as the one between two women in white in the postcard I just listed, here a few years younger but wearing a relatively similar expression! At right I'd guess his younger brother, who I believe appears again with him many years later in the postcard of the pair on the bridge I am listing next. I really like the blur of the heads of the horses here, turning toward the dirt path that runs into the distance, while the boys turn their heads toward the camera the opposite way.
5 7/16" x 3 7/16", unused back. There is some surface creasing or scratching to the photo that are visible when viewed close up; not really detracting I don't think but worth noting.