The paper nautilus has more than its little sail to assist its progression; it is able to eject water against the waves, and so move onward. They are timid and cautious creatures, live in families, and are almost always found far out at sea: they never approach the shore. CHAPTER XIII. THE OCEAN AND ITS LIVING WONDERS (_continued_). The Crustaceans, a Crusty Set—Young Crabs and their Peculiarities—Shells and no Shells—Powers of Renewal—The Biter Bit—Cocoa‐nut eating Crabs—Do Crabs like Boiling?—The Land Crab and his Migrations—Nigger Excitement—The King Crab—The Hut Crab—A True Yarn—The Hermit or Soldier Crab—Pugnaciousness—Crab War and Human War—Prolific Crustaceans—Raising Lobster‐pots—Technical Differences—How do Lobsters shed their Shells?—Fishermen’s Ideas—Habits of the Lobster—Its Fecundity—The Supply for Billingsgate—The Season‐“Lobster Frolics” in British North America—Eel‐grass—Cray‐fish, Prawns, and Shrimps. In the Crustacea we find the lowest form of articulate animals. They possess feet, breathe through gills, and derive their name from their hard crusty covering, which is mainly carbonate of lime with colouring matter. They have nearly all of them claws, which most of them know well how to employ offensively. “They have been compared,” says Figuier, “to the heavily‐armed knights of the middle ages—at once audacious and cruel; barbed in steel from head to foot, with visor and corselet, arm‐pieces and thigh‐pieces—scarcely anything, in fact, is wanting to complete the resemblance.” They possess the power of throwing off their calcareous covering, when they become, for the nonce, as vulnerable as they had been before formidable.(41)