(Ἀλύπιος), the author of a Greek musical treatise entitled . There are no tolerably sure grounds for identifying him with any one of the various persons who bore the name in the times of the later emperors, and of whose history anything is known. According to the most plausible conjecture, he was that Alypius whom Eunapius, in his Life of Iamblichus, celebrates for his acute intellect (ὁ διαλεκτικώτατος Ἀλύπιος) and diminutive stature, and who, being a friend of Iamblichus, probably flourished under Julian and his immediate successors. This Alypius was a native of Alexandria, and died there at an advanced age, and therefore can hardly have been the person called by Ammianus Marcellinus Alypius Antiochensis, who was first prefect of Britain, and afterwards employed by Julian in his attempt to rebuild the Jewish temple. Julian addresses two epistles (29 and 30) to Alypius (Ἰουλιανὸς Ἀλυπίῳ ἀδελφῷ Καισαρίου), in one of which he thanks him for a geographical treatise or chart; it would seem more likely that this was the Antiochian than that he was the Alexandrian Alypius as Meursius supposes, if indeed he was either one or the other. Iamblichus wrote a life, not now extant, of the Alexandrian.

(Meursius, Not. ad Alyp. p. 186, &c. c.; Julian, Epist. xxix. xxx. and note, p. 297, ed. Heyler; Eunapius, Vit. Iamblich. and note, vol. ii. p. 63, ed. Wyttenbach; Amm. Marcell. xxiii . 1.2; De la Borde, Essai sur la Musique, vol. iii. p. 133.)

The work of Alypius consists wholly, with the exception of a short introduction, of lists of the symbols used (both for voice and instrument) to denote all the sounds in the forty-five scales produced by taking each of the fifteen modes in the three genera. (Diatonic, Chromatic, Enharmonic.) It treats, therefore, in fact, of only one (the fifth, namely) of the seven branches into which the subject is, as usual, divided in the introduction; and may possibly be merely a fragment of a larger work. It would have been most valuable if any considerable number of examples had been left us of the actual use of the system of notation described in it; unfortunately very few remain (see Burney, Hist. of Music, vol. i. p. 83), and they seem to belong to an earlier stage of the science. However, the work serves to throw some light on the obscure history of the modes. (See Böckh, de Metr. Pind. c. 8. p. 235, c. 9. 12.) The text, which seemed hopelessly corrupt to Meursius, its first editor, was restored, apparently with success, by the labours of the learned and indefatigable Meibomius. (Antiquae Musicae Auctores Septem, ed. Marc. Meibomius, Amstel. 1652; Aristoxenus, Nicomachus, Alypius, ed. Joh. Meursilus, Lugd. Bat. 1616.)