In _Momus_ Langbaine has entries for two hundred and thirty-two authors, of whom twenty-six have "_discover_[ed] _themselves but by halves_" ([A3v]) and are listed only by initials. Langbaine claims to "_have been Master of above_ Nine Hundred _and_ Fourscore _English_ Plays _and_ Masques, _besides_ Drolls _and_ Interludes" (A2r), and _Momus_ lists approximately one thousand and forty plays, though the number may actually be slightly higher since a few of these entries represent collections ("Terence's plays," for example) and in footnotes many foreign plays are given as sources for the English ones. Of the total, thirty-five are given to supposed authors and one hundred and sixty-nine are listed alphabetically by title since their authors are unknown to Langbaine even by initial. Although the _Account_ represents a five-hundred page expansion (but in octavo), the enlargement is accomplished within the basic arrangement and largely with the lists of authors and plays established in _Momus_. Langbaine adds only ten new authors,[19] while he deletes two,[20] and adds about fifty-one new plays, while omitting three.[21] The expansion takes the form, mainly, of added biographical, critical and source material, including discussions of classical authors and of non-dramatic works. The corrections take the form of deletion and reassignment, change of dates and format, and, most interestingly, change of genre designation. There are over one hundred and fifteen genre changes, of which at least three-quarters involve tragi-comedy, and of these nearly one half (about forty) represent a shift in description from comedy to tragi-comedy. These changes suggest that Langbaine was reading or re-reading the plays carefully between the end of 1687 and 1691 and perhaps the critical commentary on genre by the Caroline dramatists as well since many of the conversions occur in describing the works of Beaumont and Fletcher, Massinger, and Shirley. For bibliographical detail _Momus_ is not entirely superseded by the _Account_ since over sixteen descriptions of format[22] and thirty of genre are not incorporated in the later catalogue. Furthermore, about thirty-eight plays are given sources in _Momus_ which are not carried over into the _Account_. A large number of the source references in _Momus_, especially those not transferred to the _Account_, are general in nature, to national histories or to the compilations of Eusebius and Heylin. * * * * *