Genus (music) the other hand, also has twelve pitches to the octave, but the semitones are all of the same size. In contrast, the ancient Greek chromatic scale had seven tones to the octave (assuming alternating conjunct and disjunct tetrachords), and had incomposite minor thirds as well as semitones and whole tones. The (Dorian) scale generated from the chromatic genus is composed of two chromatic tetrachords: whereas in modern music theory, a chromatic scale is: The number and nature of the shades of the chromatic genus vary amongst the Greek theorists. The major division is between the Aristoxenians and the Pythagoreans. Aristoxenus
Short octave "C/E", meaning that the lowest note is a C, played on a key that normally would sound E. A second type of short octave used the keys to play the G major scale Here, the exotic bass notes C and D are sacrificed to obtain the more essential A and B. The notation for the pitch range of such an instrument is "G/B". The following diagram illustrates this kind of short octave: In stringed instruments like the harpsichord, the short octave system created a defect: the strings which were tuned to mismatch their keyboard notes were in general too short