Melody “C”... Interesting reference on the 21 ad, particularly with the Sousa band pictured. I wonder if this was to distance it from the c tenor intended by Sax for classical orchestra use? Most of the Cmels I find are in the 1924-26 range, but you may well be right. The really old ones may not have survived in as great of numbers. As horns kept improving, they may have bit the dust as trade ins etc.