The fine structure of the sperm of a pulmonate land snail Cochlicella acuta (Cohlicellidae) was examined. The present results indicated that the morphology of the spermatozoon of the land snail C. acuta seems to be quite similar to that of the advanced stylommatophoran sperms. The acrosome is a conical-shaped structure, with lighter pedestal and a curved basal part extends posteriorly around the anterior tip of the nucleus. The nucleus is not helical but having a keel into which a nuclear fossa is invaginated. The neck region forming of the centriolar derivative represents the point of origin of coarse fibers. The axoneme exhibits a 9+2 pattern. The mid-piece is elongate and composed of paracrystalline and matrix materials (collectively, the mitochondrial derivative). It encloses a single glycogen helix and the axoneme. The mitochondrial derivative extends to the posterior end of the spermatozoon. Both annulus and a glycogen piece are absent.
Key words: Sperm ultrastructure, Cochlicella acuta, Gastropoda