According to the Internet source given below, Lorenzo Masi, known as Lorenzo da Firenze (Magister Laurentius de Florentia) (d. December 1372 or January 1373), was an Italian composer and music teacher of the Trecento. He was closely associated with Francesco Landini in Florence, and was one of the composers of the period known as the Italian ars nova.
Lorenzo is represented in the Squarcialupi Codex, the illuminated manuscript which is the most comprehensive source of Italian music of the 14th century, with 16 pieces of music, 10 madrigals, 6 ballate and one caccia. In addition to his contribution to that collection, he wrote two mass movements which have survived (one of which is of doubtful attribution) and a pedagogical piece (the Antefana), the text of which shows that he was a teacher.