Centriole, [25], [27]

Centripetal canals, [289]

Centro-dorsal ossicle, of Crinoidea, [580];

of Antedon rosacea, [582];

of Actinometra, [588], [594];

of Atelecrinus, [594]

Centrogenous (used of spicules = meeting in a common centre and growing outwards), [76]

Centropyxis, [51];

test of, [55];

C. aculeata, reproduction of, [57]