[Illustration: FIG. 105.--Cypræa.] On the Florida Reef the great conchs (Fig. 103) are very common. They live on the sandy floor of the lagoons, hitching themselves slowly along by their long-pointed, saberlike operculums. This is the conch of commerce, in which appears the most delicate of all pink colors, and which is the source of the rare pink pearls. In the same locality, but in deeper water, is found the Queen conch (Fig. 104), which is cut into medallions and cameos. The beautiful Cypræa (Fig. 105), of which many varieties are known, are called micramocks in Florida, and cowries elsewhere. Their luster and natural polish often excite wonder, for they commonly live concealed in the rough portions of dead coral branches, where they would easily become scratched. The cowry, however, is protected by a remarkable mantle which covers the entire shell, thus keeping its pianolike surface as smooth as a mirror. Many cowries are beautifully striped; some are spotted with dark spots on a white background; some are yellow; others are red or old gold, every tint and color seemingly being employed by nature in painting these gems of the sea. Few other shells have been so universally esteemed by all nations. Among certain African tribes they are used as money, and not many years ago collections of cowries were made with all the ardor that actuated the tulip collectors, thousands of dollars being paid for single shells, as the orange cowry. [Illustration: FIG. 106.--Cone shell (_Conus_).] The cone shells (Fig. 106) represent a beautiful group, spotted like leopards, striped like the tiger, black, red, yellow. Some shells are very pointed, like the augur shell (Fig. 107). Some have an extraordinarily long projection for the siphon, as the spindle shell (Fig. 108). In some the opening is very small, as the cone shells, while in others it is immense, and protected by a large, doorlike operculum. The Bulimas is a famous nest builder. Bulla is interesting from the lightness and delicacy of the shell and its rich neutral browns. [Illustration: FIG. 107.--Augur shell (_Terebra_).] [Illustration: FIG. 108.--Spindle shell (_Fusus_).] Among the very familiar shells are the land snails (Fig. 109), common in every garden and raised and sold in France and Italy as table delicacies. Closely allied to them are the slugs, which bear upon their backs, beneath the skin, a delicate, scale-like shell. On the island of San Clemente, fifty miles off the coast of California, I found an extensive sandy plain which was so thickly strewn with the white, bleached snail shells that I could hardly step without crushing several. The verdure had died, and the snails were doubtless killed by the direct rays of the sun. These interesting animals are called pulmonates because they breathe air directly.