Dissected penis. The substantial genital duct (1) runs a long circuitous route before entering the base of the penis. It emerges as a flagellum (2) about a quarter of the way from the distal end of the penis. The distal quarter of the penis has a deep groove (3) which accommodates much of the flagellum to give it support during copulation. The flagellum tapers to a fine point from which sperm emerge. The male passes its penis through the pallial oviduct (see image 17) so that the slender flagellum can insert sperm into ducts at its posterior.

Llŷn Peninsula, Wales, March 2016.