RULES FOR SPECIES COUNTERPOINT
Third Species (3:1, 4:1)
Third Species (3:1, 4:1) - Third species introduces the ratios of 3:1 and 4:1. In traditional (16th-Century) Species Counterpoint, Third Species introduces the neighbor note, double neighbor, and cambiata. However, in the actual music of the 18th-century, neighbor notes are found in 2:1 ratios, so that the only real challenge here is how to embellish a single note in a given voice with 3 or 4 notes in the counterpoint. Note that many of the rules for 3:1 are the same as those for 2:1.
Rules for Counterpoint in Third Species:
1. Embellishments should never obscure the prevailing harmony.
2. Although accented embellishments are allowed, the counterpoint should emphasize consonances in the places where the two voices are aligned.
3. Embellishments in 3:1 and 4:1 include:
Passing tones (see 2:1)
Neighbor tones (see 2:1)
Incomplete neighbor tones (see 2:1)
Double neighbor tones - a consonance that is embellished by both upper and lower neighbors. The neighbors may appear in either order.
Cambiata - a kind of incomplete double neighbor.
4. Leaps must be treated very carefully in these ratios. In particular, leaps into the beat after stepwise motion are poor.
5. Avoid repeated notes.
6. Parallel fifths and octaves that occur from beat to beat are forbidden.
7. Parallel fifths and octaves that occur from any weak part of the beat to the beat are forbidden. However, parallels from the second to the first part of the beat (in 4:1 only) are allowed occasionally, as long as they are not emphasized by leaps.
8. Parallel fifths and octaves on afterbeats may occur.