Octave species

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In the musical system of ancient Greece, an octave species (εἶδος τοῦ διὰ πασῶν, or σχῆμα τοῦ διὰ πασῶν) is a specific sequence of intervals within an octave.^[1] In Elementa harmonica, Aristoxenus classifies the species as three different genera, distinguished from each other by the largest intervals in each sequence: the diatonic, chromatic, and enharmonic genera, whose largest intervals are, respectively, a whole tone, a minor third, and a ditone; quarter tones and semitones complete the tetrachords.

The concept of octave species is very close to tonoi and akin to musical scale and mode, and was invoked in Medieval and Renaissance theory of Gregorian mode and Byzantine Octoechos.