And truly, if all these monuments had been preserved and gathered together into one place, or, better still, had all been left in their original places, they would have formed an invaluable and inexhaustible library for the Christian archæologist. This, however, has not been their lot. Hundreds and thousands of them have been destroyed by those who have broken into the Catacombs from time to time during the last thousand years, and drawn from them materials for building. Others, again, and amongst them some of the most valuable, have been given to learned antiquarians or devout ecclesiastics, who coveted them for their own private possession, and carried them off to their own distant homes, without reflecting upon the grievous injury which they were thus inflicting upon those that should come after them. A much larger number have been most injudiciously placed, even by persons who knew their value, and were anxious for their preservation, in the pavements of Roman churches, where they have been either gradually effaced by the constant tread of worshippers, or thoughtlessly removed and lost sight of on occasion of some subsequent restoration of this portion of the church. A few have been more securely placed in the museums of the Capitol and of the Roman College, in the porticoes of some of the Roman churches, or in the cloisters of convents. Lastly, twelve or thirteen hundred were brought together, some eighty or ninety years ago, in the Library and Lapidarian Gallery at the Vatican—a number sufficiently great to enable us to appreciate their value, and to increase our regret that so many more should have been dispersed and lost.