Each such complex of cells underlying the lenticle of a compound eye is called an " ommatidium "; the entire mass of cells underlying a monomeniscous eye is an " ommataeum."
Each such unit is termed an "ommatidium."
One single, complete eye, situated in a compound eye, is called an ommatidium.
The cells of tl ommatidium are a good deal larger than the neighbouring common cells of the epidermis.
The lateral eyes of Scorpio consist of groups of separate small lenses each with its ommatidium, but they do not form a continuous compound eye as in Limulus.
The ommataeum, as already stated, tends to segregate into retinulae which correspond potentially each to an ommatidium of the compound eye.
The ommatidium (soft structure beneath the lens-unit of a compound eye) is very simple in both Scorpio and Limulus.
The ommatidium is from the first segregate and consists of few cells.