It was a delightful animal whose discovery, according to the ancients, is a sign of good luck. Aristotle, Athenaeus, Pliny, and Oppian studied its habits and lavished on its behalf all the scientific poetry of Greece and Italy. They called it "nautilus" and "pompilius." But modern science has not endorsed these designations, and this mollusk is now known by the name argonaut. Anyone consulting Conseil would soon learn from the gallant lad that the branch Mollusca is divided into five classes; that the first class features the Cephalopoda (whose members are sometimes naked, sometimes covered with a shell), which consists of two families, the Dibranchiata and the Tetrabranchiata, which are distinguished by their number of gills; that the family Dibranchiata includes three genera, the argona