CRUSTU´MIUS a river of Umbria, flowing into the Adriatic Sea between Ariminum and Pisaurum. It is noticed by Pliny as in the vicinity of Ariminum, but in a manner that would have rather led to the supposition that it was on the N. side of that city. There can, however, be no doubt that it is the same river of which the name is corrupted in the Tabula into Rustunum,and which is there placed S. of Ariminum. It may therefore be pretty safely identified with the Conca, which enters the sea at La Cattolica, and is described as a mountain stream, liable to sudden and violent inundations when swollen by the melted snows. Hence the epithet given it by Lucan, of Crustumium rapax(Luc. 2.406; Plin. Nat. 3.15 s. 20; Tab. Peut.). Vibius Sequester (p. 8) asserts that there was a town of the same name at its mouth, but this is probably a mistake.
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