Titular bp. of Apamea , Scriptor in the Vatican Library, Rome; nephew of J. S. Assemani , and cousin of J. A. Assemani . Among his numerous works the most important is the two-volume Acta Sanctorum Martyrum orientalium et occidentalium(1748; FT by F. Lagrange, 1852). Besides assisting his uncle in the catalogue of the Vatican mss. he was also the compiler of a number of other catalogues of oriental mss. (notably that of the Medicean-Laurentian Library in Florence, 1742); he was also responsible for the third Syriac volume (1743) of the six-volume edition of Ephrem .