The euphonium/baritone/tenorhorn terminology can be maddening -- especially as used by people who don't play any of those. I once had an unreasonably intense (also somewhat irrational) conversation with a very experienced local brass repair technician who insisted that my 4-valve Amati oval euphonium was a TENORhorn, and became irate at the thought of referring to it as anything else.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)