Poromya, 1, 1*, and the beautiful pearly Pandora, 2, 3, might be included in the family of Corbulidæ. Lyonsia, 4, and Thracia, 5-10, represent the Anatinidæ. 11-18 are Solenidæ, or "Razor-shells." Solens burrow in deep holes in the sand, where they remain in a perpendicular position at a great depth below the surface, where yet their presence may be traced by the opening left. Their large muscular foot enables them to take great leaps when out of the holes.
Psammobia, 1-4, and Tellina, 5-16, include some of our most beautiful shells. The animals have a large, fleshy, curved foot, and the mantle open and fringed. Their shells are provided with an external ligament, and teeth on the hinge. Donax, or "Wedge," 19, 20, has long, separated, fringed siphons. Besides the small external ligament, properly so called, the Mactridæ have a triangular pit in the hinge of their shell, containing an elastic substance or spring, designed to resist the action of the adductor muscles. Mactra, 21-26, ends the Plate.
Lutraria, 1-3, is another genus of Mactridæ. The Veneridæ, 4-16 and 23, or "Venus" tribe, differ from it in not having the spring-holding pit. Artemis, 10, 11, is known by a large angular bend in the pallial impression; and Cytherea, 23, is distinguished from Venus by one tooth on the hinge standing out a little way from the central ones. Astarte, 17-22, belongs to the Cyprinidæ.
Fig. 1-3 also represent genera of Cyprinidæ. They have no bend in the palleal impression. Cardium, or "Cockle," 4-13, presents a peculiarity in the foot, which is large and bent, and enables the animal to leap in a very lively manner. The family of Lucinidæ occupy the remaining figures. Lucina has a curious tongue-shaped doubling of the pallial impression.
The Kelliadæ, 1-15, are marine, while the Cycladidæ, completing the Plate, are fresh-water bivalves, and may be found in many ponds and rivers.