Aut cum scuto aut in scuto
That could be a Stevens .22 rifle he's holding. Can anyone confirm?Stevens introduced the .22LR in 1888, so it would be possible. Somehow I never thought of a Chiricahua Apache with one of those rifles!
It appears to be a Frank Wesson carbine, probably in 32 rimfire caliber. I have one that is almost identical to the one in the photograph.