Noctiluca — Chambers's Encyclopaedia

Noctiluca (lit., 'night-light'), a phosphorescent marine Infusorian, extremely abundant round British and other coasts, one of the chief causes of the 'phosphorescence' of the waves. It is a spherical animal—large for an Infusorian ( $\frac{1}{50}$ in. in diameter)—and moves by means of a long stout lash or flagellum, beside which there is a second, very much smaller, lying in the 'mouth' region. Its substance is remarkably spongy, and the phosphorescence is said by Allman to have its seat just underneath the rind. See INFUSORIA, PHOSPHORESCENCE.