This is a mellophone. It is left belled, with pistons instead of rotors. It is a bit smaller than a french horn also. It has long been my understanding that no manufacturer still offered these for sale new, but in the early 1900's you could get them from all the big companies like Conn, Wurlitzer, King, Olds. Today, you can buy them used, a dime a dozen, on EBAY.COM.
6/8/2000- Just got an email from somebody telling me that the AMATI insturment complany still makes mellophone NEW!!! Check out the second picture below to see one. Visit the AMATI web site if you want to buy one at http://www.amati.cz/english/production/instruments/catalogue.htm
I have a mint Conn, 1927, with all the crooks and original accessories. Here is the text from the from the 1934 Conn Catalog--
CONN MODEL 62-E
Mellophone in F, Eb, D, C
Because it has a brilliant, colorful tone, because it is one of the easiest of all wind instrument to master, and because of its very moderate price,
the Mellophone is widely used in school and beginning bands in place of the French Horn whose place however it cannot take effectively in advanced work.
* Built in F with a complete set of slides in Eb, D and C which makes transposing unnecessary. Gracefully designed with an 11 inch bell... Weight about 4 pounds. Supplied complete but less case.
finish 2- $79 finish 3- $74 finish 4- $64
This first picture is not a Conn, but is a fine exampe of a mellophone.
This is the AMATI mellphone that you can still buy new.
Saw this one on Ebay. It was called a Hatbox mellophone. Another odd one!
How about a FIVE valve/Rotor mellophone. This is a King model. Who needs all those crooks when you can turn a rotor to change the key.