Four large mamilliform glands (1) in single row along ventral edge of penis. Filament (2) triangular, less than 5% of total length of penis.
Penis entirely translucent yellowish white apart from opaque white subepithelial tissue in glands (3) and around sperm groove distally (4) (visibility varies with lighting).
Both images are of the same individual when live (on right) and when dead. Killing caused the tentacles to contract and the penis generally to contract slightly but its glands to distend. Published drawings and photographs of mollusc penes are usually of dead dissected material. When live, a penis is motile and can change position and extension, so several views/photographs should be used when assessing its shape and proportions.