Species III: Four Notes Against One
A. Melodic line is continuous quarter-note motion. A quarter sounded simultaneously with a tone of the CF is called the "accented quarter." The penultimate tone of the CF may be set to two quarters and a half, or two halves.
1. Great care must be observed with respect, not only to linear motion and melodic gravity , but also to continuity, both in immediate context and in general.
a. No tones are to be repeated in immediate succession; and the third and fourth quarters must not have the same pair of tones as the first and second quarters.
b. The same pitch must not occur on more than two successive accented quarters, and that only if the CF changes
c. Accented (first) quarters are normally approached stepwise, and always when preceded by a measure containing no skips. In the case of an accented quarter being approached by skip, the skip must be in the opposite direction to that in which the line has been moving. In short, skip within the measure, approach and leave it stepwise.
d. Do no use more than two skips in succession in any direction (measures of quarter notes).
e. 1. Do not skip twice in succession in the same direction.
2. An exception to the above rule is: successive skips of a third or fifth plus a fourth (or fourth plus third or fifth) in one direction may be used, with immediate stepwise recovery of the line to the extent of two steps.
3. Skips of a fourth within the measure are treated as in species II: ascending, approach or leave from within the fourth; descending, both must be within the fourth.
f. 1. Stepwise recovery (filling in) of single or double skips is normal.
2. Stepwise recovery may be omitted in the case of a downward skip from a first or third quarter, followed immediately by a return upward skip to the same pitch; usually it is a minor third skip and continues upward stepwise to a tone a perfect fifth above the low point of the skip.
2. Where the CF has a half note, CP will have two quarters or a quarter and two eighths. The eighth-note pair is always on a weak quarter. If two quarters are used, they are in Species II relationship to the half note.
3. A pair of eighth notes (second or fourth quarter) may be used to decorate a step. The first eighth is always a step below the preceding quarter, while the second eighth is a step below the subsequent quarter. The eighth-note pair is always a step.
1. The first (accented) quarters must always be consonant with the CF. Likewise, the third quarters must always be consonant with the CF tone, except in certain special figures (see below). Second and fourth quarters may also be consonant.
2. If the second and/or fourth quarters are dissonant, they may be passing tones, as in Species II, or one of them may be a neighbor tone. That is, it must be both approached and left by step, but it may return to the (consonant) pitch from which it started. The principal tone after a dissonant upper neighbor must be followed by a descending passing or neighbor tone, unless the neighbor and principal tones are a half-step-apart.
3. The interval of a diminished fifth (e.g. B-F), reading upwards is allowed in Species III, but it must not fall on an accented quarter.
4. There are four special formulae treated exceptionally in Species III, involving either dissonant second or fourth quarters left by leap, or a dissonant third quarter:
a. The cambiata group. In this group the first and third quarters are consonant, and the third quarter is a fourth below the first. The second quarter is a step below the first, and the fourth quarter is a step above the third, and continues upward by step (e.g. D-C-A-B-C) The second quarter may be dissonant in this figure, as well as the fourth quarter.
b. The double passing-tone group. If the first and fourth quarters are a fourth apart, and both consonant with the CF, the second and third quarters may fill in the fourth with stepwise motion, and either or both may be dissonant.
c. The double neighbor group. If the first and fourth quarters are at the same pitch, and both are consonant, and the fourth quarter moves up by step to the first quarter of the next measure, then the second and third quarters may sound, in immediate succession, the upper and lower neighbor tones of the consonant pitch (in that order) and either or both may be dissonant (e.g. C#-D-B-C#-D).
d. The displaced passing-tone group. If the second and fourth quarters are a third apart, and both are consonant with the CF, the third quarter may be a dissonant passing tone (e.g. C-E-D-C).
e. Dissonant third quarters allowed in Species III are called accented passing-tones. In many polyphonic styles, accented passing-tones do not occur.
5. The neighbor-tone dissonance is harmonically much more intrusive than the passing-tone, and hence should be used rarely, and only when necessary for purely linear considerations. The rules below are intended to keep dissonant neighbors as discreet as possible. Half-step neighbors are easier to deal with than whole-step neighbors, because they tend to support principal tones more strongly.
a. Neighbors whose principals are approached or left by a skip of more than a third (M or m) should be half-step neighbors.
b. Neighbor tones forming a diminished fifth or augmented fourth with the CF must be half-step neighbors, and their principals should be approached and left stepwise.
c. The principal tone for a neighbor forming a major seventh or minor ninth with the CF must form an octave with the CF tone, or must be followed by a CP tone (in the same measure) forming an octave with the CF.
d. The principal tone of a double-neighbor group must form an imperfect consonance with the CF tone. The double-neighbor group is particularly useful at cadences.
1. Unisons only at the beginning and ends of phrases, or on a second and fourth quarter anywhere.
2. Parallel octaves or fifths are prohibited between third or fourth quarters and the first quarter of the next measure.
3. Parallel octaves or fifths may be used between successive first quarters or successive third quarters, but the second perfect consonance must be appraoched stepwise in contrary motion and continued stepwise in the same direction in which it was approached. Parallel octaves between a consonant second quarter and the succeeding first quarter are subject to the same restriction.
4. The consonance or dissonance of an eighth-note pair is irrelevant, except that it must not cause parallel octaves or fifths.
5. A 5-6 or 6-5 relationship is treated as in Species II, unless the stepk in the CP is descending, in which case the line may skip up to a perfect fourth. 6-5 or 5-6 must be approached
Note: The number of tones accompanying each tone of the CF in Species III makes it very possible that more than one consonance with the CF will occur in any measure, and all of the stepwise measures moving in one direction. The relation between the first quarter and a subsequent consonant third and/or fourth quarter consonance is of some significance. If the first-quarter consonance occurs again before the CF changes, the effect is of one consonance; if, however, two or more more different consonant tones occur with one CF tone, the effect is of a change in the accompanying consonance from the first to the last sounded, very much like that of a Species II measure with two consonant tones (5-6 or 6-5 step, or a consonant skip).
1. All beginning and final intervals are as in Species I. Phrases may begin with a quarter rest or half rest (as in Species II) in the CP, in which case the opening sonority is treated as if it came on the accented (first) quarter.
2. Cadences in Species III may include one or two half-notes; the half-notes are, of course, treated as Species II. However, keep in mind that in the real music, the half-note position is always consonant if half notes are present in the measure.
3. In cadences in Species III if the CP has four quarter notes (which may include a pair of eighths on second or fourth quarters), the tone, altered or otherwise, which forms the prescribed interval with the penultimate tone of the CF may appear as follows:
a. On the fourth quarter only.
b. On the first and fourth quarters.
c. On the third quarter only in the lower CP (setting below the CF).
4. The scale degree of the CF in the penultimate measure should not be doubled with any notes of the CP.
5. In cadences involving G#, F must be altered to F# where necessary. In cadences involving C#, Bb must be altered to B where necessary.
Note: many of the descriptions above are shown in the accompanying sheet of figures.
examples, page 1. examples, page 2.