With the discovery of the Morgan fragment, a new criterion of Aldus is offered. I believe that it is the surest starting-point from which to investigate Aldus’s relation to his ancient manuscript. I admit that for Book X, Avantius and the Bodleian volume in its added parts are better authorities for the Parisinus than is Aldus. I admit that Aldus resorted throughout the text of the _Letters_--in some cases unhappily--to the customary editorial privilege of emendation. But I nevertheless maintain that for the entire text he is a much better authority than the Bodleian volume as a whole, and that he should be given, not absolute confidence, but far more confidence than editors have thus far allowed him. Nor is the section of text preserved in the fragment of small significance for our purpose. Indeed, both for Aldus and in general, I think it even more valuable than a corresponding amount of Book X would be. We could wish that it were longer, but at least it includes a number of crucial readings and above all vouches for the existence of the indices some two hundred years before the date previously assigned for their compilation. It also supplies a final confirmation of the value of Class I; indeed, _B_ and _F_, the manuscripts of this class, appear to have descended from the very manuscript of which _Π_ was a part. We see still more clearly than before that _BF_ can be used elsewhere in the _Letters_ as a test of Aldus, and we also note that these manuscripts contain errors not in the Parisinus. This is a highly important factor for forming a true estimate of Aldus and one that we could not deduce from a fragment of Book X, which _BF_ do not contain. [Sidenote: _Conclusion_] I conclude, then, that the Morgan fragment is a piece of the Parisinus, and that we may compare with Aldus’s text the very words which he studied out, carefully collated, and treated with a decent respect. On the basis of the new information furnished us by the fragment, I shall endeavor, at some future time, to confirm my present judgement of Aldus by testing him in the entire text of Pliny’s _Letters_. Further, despite Merrill’s researches and his brilliant analysis, I am not convinced that the last word has been spoken on the nature of the transcript made for Budaeus and incorporated in the Bodleian volume. I will not, however, venture on this broad field until Professor Merrill, who has the first right to speak, is enabled to give to the world his long-expected edition. Meanwhile, if my view is right, we owe to the acquisition of the ancient fragment by the Pierpont Morgan Library a new confidence in the integrity of Aldus, a clearer understanding of the history of the _Letters_ in the early Middle Ages, and a surer method of editing their text. DESCRIPTION OF PLATES.