Dictionary.net

• A vesicle or organ found in Molluscs, Medusae, Crustacea, Worms, with the function of perception of the position of the body in space.

1920 - A dictionary of scientific terms.
By Henderson, I. F.; Henderson, W. D.

• [Greek] A vesicle or organ found in Molluscs, Medusae, Crustacea, Worms, with the function of perception of the position of the body in space (zool.).

1920 - A dictionary of scientific terms (6th edition)
By J.H. Kenneth