A naturalist combines aquarium observations, dissections, and literature to explain the biology and behavior of octopuses and related cephalopods. The text describes anatomy—suckers, beak, tongue—modes of locomotion and life out of water, limb regeneration, and reproductive habits including egg care and spawning. It distinguishes popular myth from recorded observation, compares octopuses with cuttlefish, squids, and the paper nautilus, and examines economic uses and accounts of exceptionally large specimens. Field notes and illustrations support the empirical descriptions throughout.