1: pink prostate visible through translucent mantle.
2: mantle edge.
3: head.
4*: filament of penis 10% to 30% of total length of penis (less than 5% on L. compressa).
5: mamilliform glands of penis. Usually 3 to 25, extreme range 0 to 43 (Reid, 1996)
6: base of penis.
7: mucronate tip on broad rounded distal end of penis of L. saxatilis s.s.. But not all L. saxatilis penes have a mucronate tip, and sometimes L. compressa has a similar tip.