CASSITERIDES, in ancient geography the name of islands regarded as being situated somewhere near the west coasts of Europe (from the Gr. Kaaaimpos, tin, i.e., "Tin-islands"). Herod otus (43o B.c.) had dimly heard of them. Later writers, Posi donius, Diodorus, Strabo and others, call them smallish islands off (Strabo says, some way off) the north-west coast of Spain, which contained tin mines, or, as Strabo says, tin and lead mines. A passage in Diodorus derives the name rather from their nearness to the tin districts of north-west Spain. While geographical knowl edge of the west was still scanty and the secrets of the tin-trade were successfully guarded, the idea of tin-producing islands easily arose. Later, when the west was better explored, it was found that tin actually came from two regions, north-west Spain and Corn wall. Neither of these could be called "small islands" or described as off the north-west coast of Spain, and so the Cassiterides were not identified with either by the Greek and Roman geographers. Instead, they became a third, ill-understood source of tin, con ceived of as distinct from Spain or Britain. Recent archaeological research has enlarged our knowledge of early sources of tin, appar ently obtained by "streaming," and islands off the coast of Brittany which have tin-bearing sands have been suggested as the original Cassiterides. It may well be however that the name represents merely early and vague knowledge of the Greeks that tin was found overseas somewhere in or off western Europe. BIBLIOGRAPHY.--Herodotus iii. 115; Diodorus v. 21, 22, 38 ; Strabo ii. 5, iii. 2, 5, v. II ; Pliny, Nat. Hist., iv. 119, vii. 197, xXX1V. 156-158, are the chief references in ancient literature. T. R. Holmes, Ancient Britain (1907), appendix, identifies the Cassiterides with the British Isles.