epresented half the value of the _semibrevis_.

Now that music began taking a more definite rhythmic form
than before, a more regular dividing off of the phrases
became necessary. This was accomplished by the use of a
dot, and another form, the perpendicular line, which we
have noticed in the song of the King of Navarre (1250). At
first a means to indicate triple time was invented, and the
measure corresponding to our [9/8] was indicated by placing
the sign [O.] at the beginning of the line. This was called
perfect. Then, for plain triple time the dot was omitted [O];
for [6/8] time the sign [C.] was adopted, and for ordinary
common time [C] was taken. Consequently, when these signs
were placed at the beginning of the line they changed the
value of the notes to correspond to the time marked. Thus in
[O.] (_tempus perfectum_, _prolatio major_) or [9/8], the
_brevis_ was reckoned worth three _semibrevi_ [B = S S S]
([1. = 4. 4. 4.]); the _semibrevis_ three _minimi_ [S = M M M]
([4. = 8 8 8]). In [O] or [3/4] time [B = S S S] ([2. = 4 4 4]);
but the _semibrevis_ was only as long as two _minimi_ [S = M M]
([4 = 8 8]). In [C.] or [6/8] time [B = S S] ([2. = 4. 4.]),
but [S = M M M] ([4. = 8 8 8]). In [C] or [2/2] time [B = S S]
([1 = 2 2]), and [S = M M] ([2 = 4 4]).

In the beginning of the fifteenth century the notes began to
be written in an open form

[Illustration] _Maxima_.
[Illustration] _Longa_.
[Illustration] _Brevis_.
[Illustration] _Semibrevis_.
[Illustration] _Minima_.
[Illustration] _Semiminima_, which was added later.

As still smaller units of value were added, the _semiminima_
was replaced by [filled minima], and the half _semiminima_
thus became [minima with tail], and the next smaller values,
[two tails] and [three tails]. The rest to correspond to
the _semiminima_ was [illustration]; for the _semibrevis_
[illustration], and _minima_ [illustration].

Thus we have the following values and their corresponding rests:

_Maxima_ [Illustration]
_Longa_ [Illustration]
_Brevis_ [Illustration]
_Semibrevis_ [Illustration]
_Minima_ [Illustration]
_Semiminima_ or _crocheta_ [Illustration]
_Fusa_ or _crocheta_ [Illustration]
_Semifusa_ [Illustration]

The rests for the _fusa_ and _semifusa_ were turned to the left
in order to avoid the confus