What is a subclass of gastropod mollusks in which the sexes are separate. It includes most of the large marine species, like the conchs, cones, and cowries called?

dioecia — (Zoöl.) A subclass of gastropod mollusks in which the sexes are separate. It includes most of the large marine species, like the conchs, cones, and cowries. (Webster's 1913.)

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