Giacomo, a celebrated librarian of Venice, was born in that city on the 14th of April 1745. He was educated by the Dominicans, and was in due time admitted to the priesthood. The subject, however, which chiefly interested him was that of bibliography, in which he was destined to attain to great eminence and distinction. In 1774 he printed his *Dissertazione Storica della pubblica Libreria di S. Marco*. In 1785 he published his Latin version of the Oration of Aristides against Lepites, the Declamation of Libanius for Socrates, and fragments of the second book of the *Harmonic Elements of Aristoxenes*, all from Greek manuscripts. One of his most important publications is that of the *Fragments of Dion Cassius on Roman history*, with new readings, which appeared in 1798, and was followed by a great variety of other works and editions. In 1802 the Emperor Francis conferred on him the title of audic counsellor; in 1816 he received the decoration of a knight of the iron crown. He died in 1819, at the advanced age of seventy-four. A list of his dissertations on history, philology, literature, and the fine arts, will be found in the first volume of his *Opuscoli*, Venezia, 3 vols. 8vo., 1820, preceded by an interesting notice of the author by Moschini.