_Pectens._--The Pectens are very widely distributed, and on account of their beauty of form and color have been in great favor with all peoples. They figure in the heraldic devices of the Middle Ages and in the symbolic paintings of the ancient Mexicans. They have been employed extensively by the ancient inhabitants of America as ornaments and rattles, and many examples exhumed from graves, mounds, and refuse heaps appear to have been used as utensils, cups for paint, and vessels for food and drink. They are especially plentiful in the cemeteries of the ancient Californians, from which Schumacher and Bowers have made excellent collections, and specimens may be found in the great museums of the country. A very good example of this shell (_Janira dentata_)[1] is shown in Fig. 3, Plate XXI, which represents a paint cup from Santa Barbara, Cal. This cup is still partially filled with dark, purplish, indurated paint. Some were receptacles for asphaltum, while others, which are quite empty, were employed probably for domestic purposes. The species chiefly used on the Atlantic coast are the _Pecten irradians_ and _P. concentricus_. On the Pacific coast the _Pecten caurinus_ and _P. hastatus_ are employed by the Makah and other Indians for rattles, and it is probable that some of the rudely perforated specimens found in our collections were intended for the same purpose. _Clams._--Clams formed a very important part of the food of the ancient seaboard tribes, and the emptied shells have been utilized in a great variety of ways. The valves of many species are large and deep, and are available for cups and dishes, and as such are not scorned even by the modern clam-baker, who, like the ancient inhabitant, makes periodical visits to the sea-shore to fish and feast. They were also used as knives, scrapers, and hoes, and in historic times have been extensively used in the manufacture of wampum. The hard-shell clam, _Venus mercenaria_, on account of the purplish color of portions of the valves, has been most extensively used for this purpose. A southern variety, the _Mercenaria præparca_, is much larger and furnishes excellent dishes. The soft-shell clam, _Mya arenaria_, has been an important article of food, but the valves are not serviceable in the arts. The hen clam, _Mactra ponderosa_, which has large handsome valves, has also been used to some extent for utensils. On the Pacific coast the large clam, _Pachydesma crassatelloides_, is known also to be similarly used. _Unios._--Shells of the great family of the _Unios_ have always held an important place in the domestic and mechanical arts of the savages of North America. Their chalky remains are among the most plentiful relics of the mounds and other ancient burial-places, and they come from kitchen middens and the more recent graves with all the pearly delicacy of the freshly emptied shell.