bordered with fringes; the gills are unequal on both sides. The siphons are very much lengthened, separate, and diverging, returning into a fold of the mantle; their orifices but slightly fringed. Notwithstanding the gaiety of the shell, the animal in this family is always arrayed in white, "simplex munditiis;" differing in this respect from Donax, the inhabitant of which usually rivals its shell in gorgeousness of hues.
About seventy species are enumerated, which live at various depths, chiefly in the warmer seas; their habits closely agree with those of the preceding family. They are much preyed upon by the carnivorous Gasteropoda, as Strombus, Buccinum, &c., their thin shells exposing them with more than ordinary ease to the depredations of those boring Mollusks.
Genus Psammobia.
The shell in this lovely genus is more or less oval, the breadth commonly being double the length; the surface smooth, or delicately striated, and clothed with a thin epidermis. The hinge is composed of two cardinal teeth in one valve, receiving one from the other; the ligament is prominent.
The animal is white, with the mantle open, and slightly fringed; the very long siphons are marked along their length with lines of cilia, and fringed at their orifices. The foot is large and tongue-shaped.
These Mollusks have the habits common to all these allied families. They live, as their name
