Modern knowledge of the grammarian Consentius’ De barbarismis et metaplasmis, a work valuable for the study of the Latin language, dates back to a relatively recent past: it was only in 1817 that its editio princeps was published by Ph.C. Buttmann, just a few years after the legal scholar A.W. Cramer came across a mention of the then unknown treatise in a ninth-century MS in the Bayerische Staatsbibliothek of Munich, numbered Clm 14666. Based on this solitary manuscript, H. Keil published the short treatise in the fifth volume of his Grammatici Latini. With no little enthusiasm did W.M. Lindsay announce his unearthing of what, in his own words, had ‘long been a “desideratum”, a second authority’ for this text, in the MS F 15 III d at the Universitätsbibliothek Basel; this was followed by E.O. Winstedt's complete collation and M. Niedermann's critical edition. After about a century now there comes to light a third authority, surprisingly enough in a codex which has enjoyed such fame in the past decades that one might wonder how Consentius could have gone unnoticed in it for so long: this is the eleventh-century MS of Venice, Biblioteca Nazionale Marciana Lat. Z. 497 (= 1811), in which the De barbarismis et metaplasmis is contained on fols. 84vb 39 - 90va 39; moreover, a so-far-unnoticed quotation from it (32.9-14), together with one from Consentius’ De nomine et uerbo (Consent. gramm. V 353.6-7), is found on fol. 41vb 16–21 of the same manuscript in a famous grammatical florilegium. The codex, written in Romanesque minuscule and probably originating in Rome, is regarded as a handbook of liberal arts designed by Lawrence Archbishop of Amalfi, formerly a monk at Montecassino, thereafter a teacher in Florence and Rome, where he died in about 1049. Based on palaeographical evidence, F.L. Newton rightfully assumed as an exemplar for this codex a MS in Beneventan script, as some features can be detected that betray the scribal imitation of that typical South Italian script, namely the use of the distinctive abbreviation for eius as ‘ei in ligature with stroke through the descender of the i’, the Beneventan ti ligature for the assibilated sound, and the 2-shaped Beneventan interrogation sign, to which I would add the typical abbreviation for in as a long i cut by a horizontal stroke and the confusion of a and t. Interestingly enough, none of these features is found on fols. 66–95, those containing the new Consentius: from a codicological point of view, this is an autonomous section, written by a different scribe from the rest of the MS and preserving some grammatical texts generally attributed to insular authors, such as Smaragdus’ Liber in partibus Donati (fols. 66–81vb) and part of the compilation entitled Pauca de barbarismo (fols. 81vb - 84vb), which precedes the De barbarismis et metaplasmis; not surprisingly, the new text of Consentius displays numerous features of the Insular script, such as the symbols for enim, autem, eius, est, nihil and et. On this basis it is most likely that this whole section was never included in the Beneventan exemplar, but was added at the time and place of copying of our MS in order to enrich the grammatical content.