The varied erudition of Catullus and of later Roman poets is wellknown. Among themselves doctus became a term of praise. So the modern reader has to spend some time acquiring the knack of appreciating this showy learning, and a student consults commentaries for instruction in myth and metre, star-lore, and place-names. My concern is with place-names, because they are not, speaking generally, given adequate treatment in the commentaries on Catullus, the Eclogues, or the Odes, which are designed for sixth-form and undergraduate use. An aspect of the learning of the poets goes largely unremarked, or if noticed, too often receives inadequate comment. The main purpose of this article is to restore to proper prominence the innovations made in the use of local names and adjectives by the Latin poets. Complete originality is not claimed; much of this knowledge, it will become clear, is to be found in the professional commentaries, for example, Pfeiffer on Callimachus, Nisbet-Hubbard on Horace, Gow-Page on the epigrammatists, Kroll on Catullus. But the information is scattered or patchy and needs to be brought together and fleshed out so that it impresses by its concentration. Only then will serious attention be paid to the poets' practice.