The fourth book of the _Ex Ponto_ constitutes a work separate from the three books composed in AD 12. The earliest datable poem in the book is the fourth, written shortly before Sextus Pompeius' consulship in AD 14; the latest is the ninth, written in honour of Graecinus' becoming suffect consul in AD 16. Of the books of Ovid's verse which are collections of individual poems, the fourth book of the _Ex Ponto_ is the longest, being some 926 lines in length (excluding the probably spurious distichs xv 25-26 and xvi 51-52). The mean average length of such books is 764 lines; and the next longest after _Ex Ponto_ IV is _Am_ III, with 824 lines (excluding the spurious fifth poem). I take the length of the book as an indication that in its present form it is probably a posthumous collection: Ovid's editor either gathered the individual poems to form a single book that was unusually long, or added a few later poems to a book previously assembled by Ovid[3]. [Footnote 3: Professor Tarrant notes however that unlike I-III the fourth book was not written within a very short time; if Ovid had collected what he thought worth publishing of his output over several years, it would not be surprising to find it longer than the preceding collections.] Syme (_HO_ 156) argues that the order of the poems indicates that Ovid survived to publish or at least to arrange the book: the fact that the first and penultimate poems are addressed to Sextus Pompeius indicates that Ovid dedicated the book to him. Professor R. J. Tarrant points out to me correspondences of structure between _EP_ IV and some of Ovid's earlier books. If the sixteenth and final poem of _EP_ IV is considered a _sphragis_-poem, as is indicated by _Nasonis_ in the opening line, we are left with a fifteen-poem book of which the first and last poems are addressed to Sextus Pompeius, and in which the middle poem is addressed to Germanicus through his client Suillius[4]. The same structural outline of 1-8-15 appears in _Amores_ I and III--the opening and closing poems of both books are concerned with Ovid's verse, while the eighth poem of each book stands somewhat apart from the other poems: _Am_ I viii is about the procuress Dipsas, while III ix (the eighth poem in the book after the removal of the spurious fifth poem) is the elegy on the death of Tibullus. [Footnote 4: Professor E. Fantham notes as well the central placement of poem ix, with its _laudes Augusti_.] Ovid's addressees in _Ex Ponto_ IV Sextus Pompeius, _consul ordinarius_ in 14, and himself a relative of Augustus, is the recipient of no less than four letters in _EP_ IV[5]. It is significant that he is not the recipient of any of Ovid's earlier letters from exile; this is discussed in the next section. [Footnote 5: Full information on what is known of each of the addressees will be found in the introductions to the poems in the commentary.]