Sixth plate seated portrait of an unknown subject sporting aspects of Highland (Scottish) accoutrement, including what appears to be a Glengarry cap and a sporran. (Tarnishing to edges, significant scratching to plate, and oxidation to preserver; unsealed.) Housed in a half leatherette case (significant surface wear/loss). The subject wears a traditional sporran with metallic cantle visible near the bottom center of the image, beneath which are at least two white horsehair tassels, and holds a dirk in one hand. 

With only certain details discernable it is impossible to say whether this is simply a civilian clansman in some variation of traditional Highland garb or a soldier representing one of the half dozen or so Highland Regiments then serving on establishment in the British Army.