The primary purpose of this species is to get practice in rhythmic variety and its use in freeing the melodic line from the constraints of any metric pulse. With the addition of suspension dissonance (Species IV), all the elements of the style are complete. Since such variety is now possible, maximum control of the contour of the line may be achieved in the style.
Be aware that many editions of 16-century music are in reduced note values, which means that eight-note pairs appear as 16 notes. Here, the tactus would be the half-note positions, with eighth-note pairs as the smallest note values.
A. Linear organization and continuity (mainly rhythmic).
1. a. No more than two measures in succession may begin with the same pitch, and then only if the CF changes notes.
b. No two measures in succession may have the same rhythm, except if there are two successive measures of quarter notes.
2. a. Maximum of one measure of Species II (maximum of four halves, meaning that the first and last notes will be in the previous and succeeding measures).
b. Maximum of two measures in Species III (maximum of twelve quarters, meaning that the first two will be in the previous measure and the last two will follow the two measures of quarter notes).
3. a. A single measure of Species II may not have Species III on both sides. In other words, there must be at least one half note before or after a Species II measure. The purpose is sothat the Species II measure will not be rhythmically isolated.
b. A pair of Species III measures may not have half notes on both sides. The reason is exactly the same as above: no isolation of a rhythmic group within a measure.
4. a. Skips of s fourth within a measure should be approached an left from within the fourth.
b. 5-6 or 6-5 relationships within a measure which is not a Species II or Species III measure must be approached or left stepwise.
1. Two halves: as in Species II
2. Four quarters: as in Species III
a. Approach stepwise, as in Species III; may be left by step or skip.
b. The first quarter and half must be consonant. (In general, in this style, the half-note positons are consonant).
c. The second quarter may be a dissonant passing tone or a dissonant neighbor tone; the the latter case, the half should descend stepwise to the tone beginning the subsequent measure.
a. Leave stepwise, as in Species III; may be approached by skip or step.
b. The half must be consonant, since it is the accented (sounding) beat.
c. The first of the quarters must be consonant if it is approached by skip. If it is approached and left stepwise, it may be a dissonant passing tone, or a half-step neighbor tone (usually lower).
d. The final quarter may be a dissonant passing tone. If it is approached or left by skip, it must be consonant.
Note: Analogous relationships exist between: long note-values vs. short note-values; notes approached or left) by skip vs. notes in a stepwise line; high and low points in a line vs. notes in the middle; "strong" vs. "weak" positions within a measure. A quarter note, approached anbd left by step in a rising or falling line, in the middle of a phrase on the second or fourth quarter is completely neutral- so much so that any harmonic relationship that exists between it an another part in longer note values is irrelevant. Conversely, a half note, approached or left by skip at the highest point of a line otherwise made up of quarter notes, occurring at the same time as a change of pitch in another part (like the CF) in longer note-values is so overly contrasted as to be unusable, even if consonant.