Ark Shells

Genus PECTUNCULUS, Lam.

Shells orbicular in outline, with hinge teeth in a semicircle; ribs radiate, margins scalloped inside; animal with large, crescent-shaped foot, wavy-margined; mantle open, margins plain, with small ocelli; lips continuous with gills. About sixty living, eighty fossil species.

The Feathered Pectunculus (P. pennaceus, Lam.) white, mottled with brown, has its beaks meeting at one end of the ligament. It has the characteristic semi-circle of fine teeth locking the hinge. As in all ark shells, the number of teeth increases with the growth of the shell. Diameter, 2 inches,

Habitat.--North Carolina to West Indies.

The Giant Pectunculus (P. giganteus, Rve.) was used by western Indian tribes of tropical America for personal adornment. Their graves contain armlets, a favourite ornament, made by grinding away all but the rim of the shell. The beaks were cut into pendents, rings and beads perforated for necklaces. Bits were inlaid in mosaic work. In Arizona graves of prehistoric tribes are found clay images of the Pectunculus. The sea shells are evidently known, but rare, in a region far from their native sea.