The genus /Janthina/ has an exceedingly thin and semi-transparent shell, deep violet in color on the base and lighter blue on the spire. An interesting feature of this genus is the mode of depositing the ova. The female exudes from a gland in the foot a [pg365] glutinous secretion which hardens in water, and, being filled with air-bubbles, constitutes a float. On the under side of this are deposited the eggs in rows of little capsules. While attached to this float it is impossible for a /Janthina/ to sink, and hence it is that so many of these creatures are sacrificed in onshore gales of wind. ^J. fragilis.^ The shell of this species is so brittle and fragile that it is very clearly not adapted to a life near shore. It is in reality a pelagic species which is occasionally blown ashore during easterly gales along the Atlantic coast of the United States. Vast numbers of these pretty creatures are sometimes encountered far out at sea, floating quietly on the surface. When storms drive them upon the beach, they become utterly helpless; since their foot is not adapted for crawling upon the sand, they soon perish, and their brittle shells are demolished by the surf. In Florida the beaches are sometimes fairly lined with /Janthina/ shells, which make a band of purple along the high-tide mark as far as the eye can reach; then it may be years before they again appear. (Plate LXVIII.) [Illustration: /Janthina fragilis/: /FL/, float; /O/, ova; /Pr/, proboscis; /Br/, branchiæ; /F/, foot.] FAMILY ~SCALIDÆ~ GENUS ^Scala^ The shells of /Scala/ have such a peculiar scheme of decoration that once seen they can never be mistaken. They are generally pure white, with well-rounded whorls, all of which are crossed at even distances by greatly elevated and smooth ribs. Each rib represents a rest-period, when the creature thickened the rim of the shell-aperture. The aperture is generally round, with a continuous lip. The animal has a retractile proboscis and long, slender tentacles with eyes at the outer bases, and is a predaceous, [pg366] carnivorous creature. Some Asiatic species of this genus, remarkable for their beauty and rarity, have been greatly prized by collectors. A single specimen of the now well-known ^S. pretiosa^ of China has been sold for two hundred dollars—a fancy price, indeed, for a shell which can now be bought for a dollar! There are over fifty species of /Scala/ on the Atlantic coast, but most of them are either rare or belong to a zone of deeper water; there are, however, four or five species which are exceedingly common. ^S. lineata.^ A species which ranges from Hatteras to New England. It has about eight whorls, and is slightly brownish in color. The ribs are robust and not greatly elevated; there are from seventeen to nineteen on the body-whorl. The shell is sometimes painted with a few revolving brownish lines. [Illustration: /Scala lineata./]