What is "doliolum"

Doliolum \Do*li"o*lum\, n. [L. doliolum a small cask.] (Zo["o]l.) A genus of freeswimming oceanic tunicates, allied to Salpa, and having alternate generations.

n. free-swimming oceanic tunicate with a barrel-shaped transparent body

Doliolum is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found at .