The two excerpta examined show the ‘school’ work that was carried out on the text of the Onomasticon of Pollux in the Byzantine age. The excerptum Vaticanum is closer to the Onomasticon of Pollux, except for some cases in which it inserts glosses that are absent in the reference text. From the study of the manuscript tradition some cases have resulted in which our excerptum shows affinity with the codices B and C (IV) thanks to some common variants. The excerptum Vallicellianum offers greater interest in the numerous citations of ancient and late antique texts without indication of author and work. From the comparison with the Onomasticon it is possible to schematically outline the compiler’s way of proceeding; he sometimes isolates glosses present in the Onomasticon, but proceeds without depending on the reference lexicon; other times, instead, even when starting from Pollux’s text, he inserts glosses absent in the reference lexicon.