The musical scale formed by these eight notes consists of two _tetrachords_ or scales of four notes, and a major tone. The lower of the tetrachords consists of the notes from Hypatê to Mesê, the higher of those from Paramesê to Nêtê: the interval between Mesê and Paramesê being the so-called _Disjunctive Tone_ ([Greek: tonos diazeuktikos]). Within each tetrachord the intervals depend upon the _Genus_ ([Greek: genos]). Thus the four notes just mentioned--Hypatê, Mesê, Paramesê, Nêtê--are the same for every genus, and accordingly are called the 'standing' or 'immoveable' notes ([Greek: phthongoi hestôtes, akinêtoi]), while the others vary with the genus, and are therefore 'moveable' ([Greek: pheromenoi]). [Footnote 1: This is especially evident in the case of the Lichanos; as was observed by Aristides Quintilianus, who says (p. 10 Meib.): [Greek: hai kai tô genei lichanoi prosêgoreuthêsan, homônymôs tô plêttonti daktylô tên êchousan autas chordên onomastheisai]. But Tritê also is doubtless originally the 'third string' rather than the 'third note.'] In the ordinary Diatonic genus the intervals of the tetrachords are, in the ascending order, semitone + tone + tone: _i.e._ Parhypatê is a semitone above Hypatê, and Lichanos a tone above Parhypatê. In the Enharmonic genus the intervals are two successive quarter-tones ([Greek: diesis]) followed by a ditone or major Third: consequently Parhypatê is only a quarter of a tone above Hypatê, and Lichanos again a quarter of a tone above Parhypatê. The group of three notes separated in this way by small intervals (viz. two successive quarter-tones) is called a [Greek: pyknon]. If we use an asterisk to denote that a note is raised a quarter of a tone, these two scales may be represented in modern notation as follows: _Diatonic._ _Enharmonic._ e =Nêtê= \ e =Nêtê= \ d Paranêtê } ( c Paranêtê } c Tritê } +---( b* Tritê } b =Paramesê= / | ( b =Paramesê= / a =Mesê= \ | a =Mesê= \ g Lichanos } | ( f Lichanos } f Parhypatê } | +-( e* Parhypatê } e =Hypatê= / | | ( e =Hypatê= / | | [Greek: pyknon] [Greek: pyknon] In the Chromatic genus and its varieties the division is of an intermediate kind. The interval between Lichanos and Mesê is more than one tone, but less than two: and the two other intervals, as in the enharmonic, are equal.