SHELL-MONEY, a medium of exchange common to many primitive races, consisting of sea shells or pieces of them worked into beads or artificially shaped. Shell-money has not been restricted to one quarter of the globe, but in some form or other appears to have been almost universal. It has been found in America, Asia, Africa and Australia. The shell used by the Indians of Alaska and California was the Dentalium pretiosum, a species of tusk-shell found along the north-west coast. It received its name from its tusk-like appearance, and was valued by length and not by the number of shells. The usual method of measuring was by the finger-joints, and the ligua, the highest denomination of their coinage, consisted of twenty-five shells strung together, which from end to end made a total measurement of a fathom (6 ft.) or thereabouts, equalling in English coinage about £50. Farther south on the shore of California the Indians used the Saxidomus gracilis or Tapis gracilis, while in the islands close to the littoral the Litornia obesa was in commonest use.

But the shell most used by primitive peoples has always been the Cypraea moneta, or money-cowry (see Cowry). It is most abundant in the Indian Ocean, and is collected more particularly in the Maldive Islands, in Ceylon, along the Malabar coast, in Borneo and other East Indian islands, and in various parts of the African coast from Ras Hafun to Mozambique. It was formerly in familiar use in Bengal, where, though it required 3840 to make a rupee, the annual importation was valued at about £30,000. In western Africa it was, until past the middle of the 19th century, the usual tender, and before the abolition of the slave trade there were large shipments of cowry shells to some of the English ports for reshipment to the slave coast. As the value of the cowry was very much greater in West Africa than in the regions from which the supply was obtained, the trade was extremely lucrative, and in some cases the gains are said to have been 500%. The use of the cowry currency gradually spread inland in Africa, and about 1850 Heinrich Barth found it fairly recognized in Kano, Kuka, Gando, and even Timbuktu. Barth relates that in Muniyoma, one of the ancient divisions of Bornu, the king's revenue was estimated at 30,000,000 shells, every full-grown man being required to pay annually 1000 shells for himself, 1000 for every pack-ox, and 2000 for every slave in his possession. In the countries on the coast the shells were fastened together in strings of 40 or 100 each, so that fifty or twenty strings represented a dollar; but in the interior they were laboriously counted one by one, or, if the trader were expert, five by five. The districts mentioned above received their supply of kurdi, as they were called, from the west coast; but the regions to the north of Unyamwezi, where they were in use under the name of simbi, were dependent on Moslem traders from Zanzibar. The shells are still used in the remoter parts of Africa, but are yearly tending to give way to ordinary currency. The shell of the land-snail, Achatina monetaria, cut into circles with an open centre has been long used as coin in Benguella, Portuguese West Africa. In parts of Asia Cyproea annulus, the ring cowry, so-called from the bright orange-coloured ring on the back or upper side of the shell, was commonly used. Many specimens were found by Sir Henry Layard in his excavations at Nimrud in 1845–1851.

In north Australia different shells were used, one tribe's shell being often absolutely valueless in the eyes of another tribe. In the islands north of New Guinea the shells are broken into flakes. Holes are bored through these flakes, which are then valued by length, as in the case of the American tusk shell, the measuring, however, being done between the nipples of the breasts instead of by the finger-joints. Two shells are used by these Pacific islanders, one a cowry found on the New Guinea coast, and the other the common pearl shell broken into flakes. As late as 1882 local trade in the Solomon Islands was carried on by means of a coinage of shell beads, small shells laboriously ground down to the required size by the women. No more than were actually needed were made, and as the process was difficult, the value of the coinage was satisfactorily maintained. The custom of breaking or flaking shells was common among some of the American Indian tribes, but the shells so manipulated were of the ponderous Pachyderma crassatelloides species, while in the South Pacific Islands the Oliva carneola was used.

Authorities.—Robert E. C. Stearns, “ Ethno-conchology: a Study of Primitive Money," in Smithsonian Report, part ii. (Bureau of Ethnology, Washington), for 1887; “ Shell-money,” in The American Naturalist, vol. iii. (Salem, 1869); " Aboriginal Shell-money," in The American Naturalist (1877), vol. xi.; “ On the Shell-money of New Britain,” in Jour. Anthrop. Institute (1888), vol. xvii.; “ Aboriginal Shell-money," Proc. California Acad. of Science (San Francisco, 1875), vol. v.; E. Ingersoll in Country Cousins (New York, 1884); S. Powers, Contributions to North American Ethnology (Washington, 1877), vol. iii.