Ah ha, thank you! Those hats just looked
so all over the place, seemed as if it couldn't be a unit of anything! Think the slouch hat to the left, man sitting bugged me because there's a ' Mounty ' shape, probably just got squished. Like
@lupaglupa said, swear there's a bowler in there- were regulations less by 1864 or were 100 day units not as well outfitted?
Thanks very much for the ID!