PURPLE SHELL, a gastropod mollusk of the family Muricida and especially of one sec tion of it of which the genus Purpura is typical. A great many species are found in all seas. The true purples form the subfamily, Purpur inc. The Muricida. are carniverous marine snails very destructive to other mollusks, bar nacles, etc. Many of the tropical species of Murex and related genera are of large size and remarkable for the large spines borne upon the shells, but our representatives of the family are small and inconspicuous. (See Danl.). Our true purple shell (Purpura lapillus) is found in great abundance on rocky coasts on both sides of the north Atlantic, but is infrequent in the United States south of Long Island Sound, where it is replaced to some extent by related species. The shell is very thick and solid, short oval with a low spire and a large aperture, the outer lip of which is marked with revolving ridges. It is extremely variable in size, shape, color and markings. Like the drill it is carniv orous, but with us confines its attacks chiefly to the barnacles which encrust the rocks between tides, though in Europe it works great havoc on the mussel beds.
The name °purple shells applied to this group of mollusks is derived from the use to which certain species were put by the ancients in the preparation of their most valued dye huffs, for which the city of Tyre was especially famous, and upon which its prosperity about 1000 ac. was founded. The Tyrian purples
were of several shades, varying from blue to a dull crimson, dependent upon the particular variety of shell employed and the substances mixed with the extract. Among the most im portant species utilized were Murex trunculus, M. brandaris and PurPurea patula. These snails were gathered on both the African and European shores of the Mediterranean. The smaller ones were crushed in mortar-shaped holes in the rocks and mixed with soda, urine, sea-water and other substances; the larger ani mals were removed from their shells or the dye squeezed out. The desired colors were obtained by exposure to the sun and by various cotnbina lions and the cloth was steeped in a large ex cess of fluid until the proper effect had been produced. The fluid is contained in a saccular gland which opens into the mantle cavity and has at first the color and consistency- of cream and a disagreeable odor, but changes to purple upon exposure to light. Consult Simmonds, (Commercial Products of the Sea.'