root in I_6).

[Illustration: Fig. 63.]

When writing three notes to one in the fourth species, the suspension may
resolve on the second beat (_a_), or the third (_b_). In the latter case,
the suspension skips (_c_) to some other chord-tone, before resolving. The
resolution to the leading-tone (_d_) forms an important exception to this
rule. [Fig. 64.]

[Illustration: Fig. 64.]

The fifth may be used in the lower part if it becomes the preparation of a
suspension (Fig. 65_a_). It may also be used in the lower part, as in Fig.
65_b_, provided it resolves by skipping to the third of the chord.

In skipping from the fifth to the root, or the reverse, in the lower part,
do so in an upward direction. The fifth, when treated as an harmonic
passing-tone, may, however, be approached either ascending or descending.

[Illustration: Fig. 65.]

The retardation should be used only when prepared by the leading-tone. It
rises a semitone in resolving. [Fig. 66.]

[Illustration: Fig. 66.]

The following dissonant intervals may be used on the first half of the
measure:--When the counterpoint is above, the fourth and seventh in
suspension, and second and fifth in retardation; and when below, the second
in suspension, and the fourth and seventh in retardation. [Fig. 67.]

[Illustration: Fig. 67.]

Consecutive fifths on consecutive strong beats of the measure are good when
one of the tones of the second fifth is prepared, as in Fig. 68.

[Illustration: Fig. 68.]

The following cadences are good:

[Illustration: Fig. 69.]

EXERCISES

Write one eight-measure phrase with two notes to the measure in one part
and six in the other; one with three notes in one and six in the other; and
one with two notes in one part and four in the other. (Fig. 59.) In
combining the species in this and succeeding lessons the student may place
any species in any part.

To the cantus firmus write two counterpoints above and two below, in the
fourth species.

CANTUS FIRMUS

[Illustration: Fig. 70.]

LESSON VII

FOURTH SPECIES (Continued)

The first and fourth species may be mixed as in Fig. 71. Rules for writing
other than the first species in both parts are to be regarded.

[Illustration: Fig. 71.]

EXERCISES

To cantus firmus _a_ write two counterpoints above and two below, in the
fourth species.

To cantus firmus _b_ write two above and two below, three half-notes to the
measure, with syncopations.

Write two eig