AUGMENTATION OF THE REGULAR FORM .-- To this species belong those forms (small and large) which are provided with a separate Introduction, or Interludes, or an _independent_ Coda (in addition to, or instead of, the usual consistent coda).
For example, Beethoven, pianoforte sonata, op.

13, first movement; the first ten measures (_Grave_) are a wholly independent Introduction, in phrase-group form, with no other relation to the following than that of key, and no connection with the fundamental design excepting that of an extra, superfluous, member.

The principal theme of the movement (which is a sonata-allegro) begins with the _Allegro di molto_, in the 11th measure.

Similar superfluous sections, derived from this Introduction, reappear as Interlude between the Reposition and Development, and near the end, as independent sections of the coda.
In a manner closely analogous to that just seen, the fundamental design of any movement in a _concerto_ is usually expanded by the addition of periodically recurring sections, called the "_tutti_-passages," and by a "_cadenza_," occurring generally within the regular coda.

In some concerto-allegros (for instance, in the classic forms of Mozart, Beethoven and others), the first orchestral _tutti_ is a complete _introductory_ Exposition, in concise form, of the thematic material used in the body of the movement.