Zool. [mod.L., a. Gr. κτενἰδιον, dim. of κτεν-(κτείς) a comb.] Each of the respiratory organs or gills of Mollusca, consisting of an axis with a series of processes on each side like the teeth of a comb.
1883. Ray Lankester, in Encycl. Brit., XVI. 636/1. (Mollusca) These are the ctenidia or gill-combs. Usually … they play the part of gills, but since in many Molluscs (Lamellibranchs) their function is not mainly respiratory … it is well … to give them a non-physiological name such as that here proposed.
1888. Rolleston & Jackson, Anim. Life, 450. In the majority of Gastropoda the primitive left ctenidium is aborted.
