The Money Cowrie: Cypraea moneta
The earliest use of the word Cypraea did not refer to the genus but related to one particular species—the Money Cowry (Cypraea moneta), a small yellow shell from the Maldive Islands in the Indian Ocean. Small and light, with little variation in size and form and a pronounced bump suggestive of pregnancy and fertility, it was used primarily in West Africa and Bengal in the eighteenth and nineteenth centuries as an alternative to legal tender. Hundreds of millions of the glossy little shells were exchanged, both by Europeans for the purchase of slaves and locally for smaller daily transactions. Even after the introduction of specie (coinage) and banknotes, they continued to be used, (The larger Ring Cowrie, Cypraea annulus from the coast of East Africa and Zanzibar also was used as a medium of exchange—and both species were imported, as it would hardly do to collect one's currency on the beach.)
The cowries could be strung (forty shells to a "string" and fifty strings to a "head") or bagged, ten such heads comprising 20,000 shells—about 50 pounds, the weight that a man could be expected to carry over some distance (and with a value in the late nineteenth century of 1shilling, 3 pence). Such a load also was known as a captif (captive or slave). Prior to the mid-ineteenth century, when inflation began to reduce the cowries' value, as little as two such loads could have purchased the man who carried them. Too, the cost of transporting hundreds of pounds of shells by porter could be more than the value of the item being acquired.
In the first half of the eighteenth century, approximately 16,000 cowries were equivalent to one ounce of gold (£4) on the fabled Gold Coast of Guinea which, coincidentally, gave its name to the English guinea (£1.1s). By 1820, as values fluctuated, the number of shells had doubled to 32,000, after which the cowrie was valued against the silver dollar, which was one-sixteenth of a gold ounce or 2,000 shells, a number that could purchase as many as ten live domestic fowl (Guinea hen). It was an exchange rate that extended from the early-eighteenth to the mid-nineteenth century, the lack of depreciation due to the expanding slave trade and a concomitant demand for cowries. Throughout the eighteenth century, 150 tons of shells were imported every year, counting some 800,000 shells to the ton. These were used in partial payment for slaves and usually comprised one-third of the purchase price. In about 1720, this would have been 180 pounds of cowries (there were about 400 shells to the pound).
Inflation and the introduction of European currency eventually rendered the cowrie an untenable medium of exchange.
References: "The Cowrie Currencies of West Africa, Part 1" (1970) by Marion Johnson, The Journal of African History, 11(1), 17-49; Part II, 11(3), 331-353.
