In 1861 Cavalier de Rossi published the first volume of his _Inscriptiones Christianae Urbis Romae seculo VII. antiquiores_. On to-day we announce the appearance of the first volume of his long expected work on Subterranean Rome. In the introduction the author passes in review all that has been done to explore the Catacombs, from the fourteenth century to our day. Pomponius Laetus, Pauvinius, Ciacconius, and especially Bosio and Bottari, claim his attention in turn. After a sketch of the results of the labours undertaken in the eighteenth and nineteenth centuries, Cav. de Rossi shows what yet remains to be done, and what part of this he himself proposes to accomplish. The second part of the volume is entitled “Remarks on ancient Christian Cemeteries in general, and on those of Rome in particular”: the whole is divided into three parts. Part I. on the Christian Cemeteries in general, treats of their antiquity, their divisions into subterranean and non-subterranean, and the respective marks of each class. The author here proves that even in the third century, when Christianity was persecuted to the death, the Christian Cemeteries had a legal existence recognized by the Emperors. Part II. is devoted to the documents which illustrate the history and topography of the Catacombs, and embraces contemporary documents, historical and liturgical treatises later than the fourth century, lives of Pontiffs, etc. Part III. contains a general history of the Roman Cemeteries, arranged in four periods: beginning respectively, with the apostolic times; the third century; the peace of Constantine (312); and the fifth century, A.D. 410. In the second century the catacombs were of slow growth; in the third, their extent became most remarkable; after Constantine, they began to be abandoned as places of sepulture; with the fifth century set in their decay, leading to the removal of the relics of the saints to the churches within the walls, whither the sacrilegious hands of Goths and Lombards, who periodically pillaged the Campagna, could not reach; finally, after the ninth century, they were almost forgotten. Part IV. contains the analytical description of the Christian Cemeteries. The Cemetery of Callixtus, the most ancient and most celebrated of all, is described at length. IV. _Vetera Monumenta Hibernorum et Scotorum Historiam Illustrantia; quae ex Vaticani, Neapolis, ac Florentiae Tabularis depromsit, et Ordine chronologico disposuit_ Augustinus Theiner, Presbyter Cong. Oratorii, Tabulariorum Vaticanorum Praefectus, etc. Folio, Romae, Typis Vaticanis, 1864. One Volume folio, pages 624.