Musicology Annotation << Back Theory of species of fourth and fi fth, forming modes, of Marchetto of Padua (or an explanation of the «musical dishes») Natalia S. Storchak The article is devoted to one of the most notable treatises of the Middle Ages – «Lucidarium in arte musice plane» – outstanding Italian music theorist of the XIV century Marchetto of Padua. A signifi cant impact on the development of music theory had а Marchetto`s modal theory, poorly studied in domestic musicology. The article deals with the so-called Marchetto`s «theory of species» (species of fourths and fi fths), underlying in his doctrine of modes, and particularly with the Marchetto`s classifi cation of species of fourths and fi fths in terms of their implementation in the melodies of chants. Apparent effect on the Marchetto`s classifi cation had a theory by Guido of Arezzo (intersections with the terminology of Guido`s treatise «Micrology» were marked in the article). Marchetto develops the doctrine of species of fourths and fi fths, which are forming modes, in the proper direction. It is particularly evident in the fi nal part of the classifi cation, linked with the problem of modal attribution of chants. Keywords: Marchetto, Lucidarium, mode, species, commixtus. Contacts: E-mail: storchaknatalya@yandex.ru Pp. 62-70.