ICO´SIUM(Ἰκόσιον: Algier), a city on the coast of Mauretania Caesariensis, E. of Caesarea, a colony under the Roman empire, and presented by Vespasian with the jus Latinum. ( Itin. Ant. p. 15; Mela, 1.6.1; Plin. Nat. 5.2. s. 1; Ptol. 4.2.6.) Its site, already well indicated by the numbers of Ptolemy, who places it 30′ W. of the mouth of the Savus, has been identified with certainty by inscriptions discovered by the French. (Pellissier, in the Exploration Scientfique de l'Algérie, vol. 6. p. 350.) Many modern geographers, following Mannert, who was misled by a confusion in the numbers of the Itinerary, put this and all the neighbouring places too far west. [Comp. IOL]
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