This looks a bit like an Olds Artist, but I can't be sure. I THINK the 3rd-valve trigger was an add-on - I don't recall any model like this in the catalogs. I think it is an Olds because of the nickel-siver (I assume) bell top. Bidding starts at 10 bucks, so this could be a fun hobby horn! The seller has a 100% positive rating.
SOLD FOR $100!
CORRECTED URL:
https://www.ebay.com/itm/Baritone-Euphonium-11-inch-bell-28-inches-overall/265118437956