^S. multistriata.^ The transverse ribs are much smaller but very numerous; the small spaces between them are marked with many fine revolving lines. Found from Cape Cod southward. [Illustration: /Scala multistriata./] ^S. groenlandica.^ Essentially an arctic species, which has found its way down to the New England coast. It is readily distinguished by the flattened, coarsely rounded, revolving ribs, which follow the volutions of the spire. Over them are the usual transverse heavy ribs peculiar to this genus. [Illustration: /Scala groenlandica./] ^S. angulata.^ The whorls touch one another only by the ribs, of which there are nine to each volution. This species has a remarkably wide range, occurring from Cape Cod to southern Florida. (Plate LXVIII.) These four species vary from one half of an inch to one inch in length. All of them are found on the beach after storms or may be dredged in shallow water near the shore. FAMILY ~NATICIDÆ~ This large and interesting family is well represented in the Atlantic waters of the United States, but its more beautiful members live in the tropics. The New England and New Jersey species are dull in color, but offer much of interest to the collector and student. The foot is enormously large, and carries in front a great shield-like fleshy process, which curves back over the head of the animal and serves as a plow in pushing its way through the heavy wet sand of the beach. When the creature is thus seen extended in the act of crawling, one wonders how it is possible for it to withdraw so great an amount of body into its shell; but if it is suddenly seized or irritated, it will quickly [pg367] demonstrate its ability to hide itself completely within its house and to close the door very effectively by means of its operculum. The eyes seem to be wanting, or they are concealed under the skin of the head. The shell is usually quite large, with a depressed spire and well-rounded whorls—especially the body-whorl, which appears to be greatly swollen. The umbilicus is usually open and moderately large, the lip simple. [Illustration: PLATE LXVIII. Janthina fragilis. Sigaretus perspectivus, upper side. Scala angulata, enlarged. Sigaretus perspectivus, under side. Natica canrena. Crepidula aculeata.] GENUS ^Polynices^ (^Lunatia^, ^Natica^).