Page:Natural History, Mollusca.djvu/210
keeping its body contracted within the shell. Though I have kept many specimens, I have never seen one crawl.
An immense assemblage of species, some of which are of large size and great beauty, is comprised in this family. The animal is spiral, with the sides occasionally ornamented with tentacular appendages differing in number and form; the head is protruded somewhat in the form of a proboscis, furnished with slender thread-like tentacles; the latter carry at their bases a pair of eyes, usually raised on footstalks; the mouth has no tooth on the lip, but is provided with a ribbon-shaped tongue of great length, rolled up spirally when not in use, and carried in the cavity of the body. A furrow passes across the foot near its front border; the gills consist of two fringes.
The shell is thick and solid, often more or less pearly on the inside, forming a spiral cone, with the opening round or slightly depressed. There is an operculum, which is calcareous (shelly) in some species, horny in others; in the latter the spiral formation is visible on the outside, in the former on the inside.
All the members of this family are believed to be vegetable feeders, subsisting on the sea-weeds, the substance of which they rasp down by the action of their rough tongue. Yet the large and beautiful Phasianella bulimoides, an Australian species assigned to this family, is said by MM. Quoy and Gaimard to be taken in nets baited with flesh, and let down into the sea.