The expression "Musical Forms" is often used, somewhat carelessly and erroneously, with reference to Styles or Species of composition, instead of to the structural design upon which the music is based. The "Barcarolle," "Mazurka," "Étude," "Anthem," and so forth, are styles of composition, and not necessarily identified with any of the structural designs we have been examining. Read, again, our FOREWORD. The general conditions which enter into the distinctions of style are enumerated in my "Homophonic Forms," paragraph 97, which the student is earnestly advised to read. As to the manifold styles themselves, with which the present book is not directly concerned, the student is referred to Ernst Pauer's "Musical Forms," and to the music dictionaries of Grove, Baker, Riemann, and other standard writers, where a description of each style or species of composition may be found.