I do believe that it is square cornered, no indices playing cards these two have tucked into the brims of their hats. And they look pretty wily, as though playing cards was a vocation rather than pastime..but who knows? There is a deep scratch running down the surface of the tintype just to the left of the arm of the man standing, which makes it looks as if there were the arm of a chair there, which the man in the top hat is caught behind/peeking out around, the effect of which I really like. (As if it were an ongoing struggle as to who would be in the foreground of the photo.) Unusual, and these two feel right there, close enough to sit down with and deal a hand. 

3 1/2" x 2 3/8". Heavy scratch running down left of standing man's arm, as described above. Otherwise some general light scratching as documented.