Few slugs garner such attention as banana slugs. These large, often colorful slugs, are in the family Arionidae and the subfamily Ariolimacinae. This subfamily includes the following genera of banana slug, Ariolimax columbianus (Gould); A. dolichophallus; and A. californicus. Slugs in this subfamily have a keel along their back. They can often be found with a slime plug or caudal pore with a mucous plug.
Web Resources
Sexual conflict in banana slugs website. This website also contains video of one of the extremes of this conflict, apphallation.
Pacific banana slugs mating