In Forbes’ words: The land slugs are elongated, semi-cyclindrical, soft or fleshy creatures, either unfurnished with shells, or provided with rudiments of them, imbedded in the cloak or disk, which covers the anterior of the body. This disk covers the respiratory cavity. All slugs have a retractile head, four retractile tentacles, the two upper ones provided with eyes. They are herbivorous by preference but carnivorous when taste or necessity prompts them. They are crepuscular or nocturnal in their habits.’ From ‘A History of British Mollusca and their Shells, by Forbes and Hanley (1853).
Slugs are unattractive to most people at the best of times. Forbes clearly found them otherwise. He regarded ‘Limax cinereus as the largest and most beautiful of all British slugs.’