Other instruments

There are a great variety of other instruments that have been made that are no longer around. Here are some examples:

Racket: a double-reed instrument that sends the sound through a series of waves to deepen the sound
Basset Horn: a single reed instrument that was often bent in a variety of shapes then sent through a soundbox
Saxhorns: Adolphe Sax developed both the woodwind saxophones, and an odd variety of brass instruments called "Saxhorns"
Wagner Tuba: a tuba-like instrument that is played and built like a horn
Ocarina: This is a little-known instrument that has the sound flow through the entirety of its body
Erhu: a bowed instrument which has the bow resting between two strings
Theremin: an odd instrument that is played by moving ones hands around
Valve trombone: apparently these instruments exist, but I've never seen one
Natural horn: an older version of the horn which uses a series of tubing extensions which attach at the mouthpiece hole

There are a great many others, but this is a start.