A. Ventral view of whole animal. B: Midsaggital section through body. D: spermatozoon. D: Scheme of epidermis.,= E,F: Epidermal cilia. tip (E) and bases showing rootlets (F); anterior=or toward right. (A-C after Ax, 1963 after Westblad, 1949; D after Reisinger, 1960; E and F after Franzen ad Afzelius, 1987). bm, basement membrane; cg, ciliated groove; e, egg; gc, gland cell; m, mouth; n, nerve plexus; sc sensory cell; st statocyst; tw, terminal web.