While the devilfish is the type of all that is hideous and repulsive in nature, it has a near relative, the paper nautilus, which is a very dainty and beautiful creature. It appears to be an octopus which lives in a shell. The argonaut, as it is called, has eight short arms, the upper pair being largely developed at their tips, forming fanlike or saillike organs. It was formerly believed that these were really sails, held aloft to catch the breeze to blow the fairy argonaut along. So fixed in the public mind was this erroneous belief that illustrations in various works otherwise correct, display the argonaut in this incorrect position. The animal is the female, which, to protect and carry its eggs, is provided with a dainty shell which it secretes, but is not attached to, and would lose were it not for the two large-ended tentacles with which it grasps the beak of the shell (Fig. 124). These arms also bear the shell-making and repairing glands. The argonaut can crawl upon the rocks at the bottom, swim through the water, forced along by its siphon stream, or float calmly at the surface. About nine species are known; generally in some tropical waters. Every year a few are found stranded upon Santa Catalina Island, California. [Illustration: FIG. 124.--Argonaut in natural position, arms holding the shell.] [Illustration: FIGS. 125, 126.--Sections of an ammonite.] In many of the fossil deposits are found gigantic shells resembling the wheels of a cart, and enormously heavy. These are ammonites (Figs. 125, 126), and ancestors of the nautilus (Fig. 127), another member of this wonderful family of animals, with feet attached to their heads. It has a shell of radiant pearl, divided, like the little Spirula, by pearly septa or partitions, into rooms or chambers (_C_) all of which surround a small tube (_s_) called the siphuncle. This contains a long, fleshy pedicel, hence the nautilus is attached to its shell and can not leave it. The shell chambers are filled with gas, and the animal has the power to change its specific gravity, to float or rise. The nautilus forces itself along by a current from its siphon, and in a general way resembles others of the group. It has no ink bag, and its eye is not the striking object seen in the other forms. It is merely an elevation bearing a minute hole which leads into the globe of the eye, which during the life of the nautilus is filled with water. According to Doctor Hensen, in place of a refracting lens and a cornea, the animal has an arrangement for forming an image on the principle of a pin-hole camera. We might imagine the nautilus easy to capture; but it is very timid and rarely caught. Instead of eight or ten arms the nautilus has ninety-four. The shell is a beautiful object when cleaned and polished, being a vase of pearl of a chaste and elegant design, often copied, and in great demand by native artisans who carve and engrave it, and mount it in gold and silver. The nautilus, aside from its beauty, is