C. violacea.
C. Bengalensis.
C. Ceylanico.
C. fluminea. The river Cyrena. Pl. [6], fig. 7.
Species sub-trigonal or elongated oval; summits decorticated, more anterior; three cardinal teeth, of which the two posterior are forked; exterior greenish brown, interior variegated with white and violet; sulcated transversely.
3. Galathea. One species.
This beautiful shell is found in fresh waters, and is distinguished from the Cyrena by the divergent form of the primary tooth.
G. radiata. The radiated Galathea. Pl. [6], fig. 8.
Shell equivalve, sub-trigonal, covered with a greenish epidermis, beneath which the surface is of a milky white, highly polished, with several violet or pale chestnut rays diverging from the apex to the margin; primary teeth furrowed, two on the right valve joined at the base, three on the other valve placed triangularly, the intermediate one being advanced, separate, thick, and callous; the muscular impressions are lateral, and appear double on each side.
C. Marinæ. Four genera.