The subject of this study is, perhaps, the most commonly known of the manuscript sources of early church history. Beginners in the subject, who are apt to take for granted the text of their sources, nevertheless presently learn that they owe the beginning of the story of the Meletian schism in Egypt and much of the later history of Athanasius to their discovery, early in the eighteenth century, by the Marchése Maffei, in a volume belonging to the Chapter library of Verona. But the fact is that this codex as a whole possesses great interest and presents the student with many fascinating problems. These have been attacked, and in part solved, by a succession of scholars, beginning with Maffei himself and two other Veronese savants, the Ballerini brothers, continuing later with Maassen and Batiffol, and in our own times with Professors C. H. Turner and E. Schwartz. The work of these and others, on this subject, is scattered through many books and periodicals, and the time is ripe for a résumé in English of the whole story. It is even possible to carry the work forward in one or two respects.