The thinnest and usually the longest portion of male duct, connecting male funnel with atrium or penial bulb, seldom immediately opening with male pore. Pl. vasa deferentia.

The term "sperm duct" is used particularly by the experts in Enchytraeidae.

Genus Cernosvitoviella .
C. pal sph , some specific characters of C. palustris and C. sphaerotheca.

Alternative forms for vas deferens : sperm duct, vasa deferentia.