Casiri, Michael a learned Maronite, was born in 1710 at Tripolis, in Syria. Being educated at Rome, in the college of St. Peter and St. Marcellinus, he entered the clerical order in 1734. In 1735 he accompanied Assemani into Syria, by order of the pope, to assist in a synod of the Maronites. Casiri made a report in 1738 at Rome on the religious opinions of that sect, after which he was appointed to teach in his convent Arabic, Syriac, and Chaldee, theology and philosophy. In 1748 he went to Madrid, and was employed there in the royal library, and in 1749 in the library of the Escurial, of which he was made director soon afterwards. He began in 1750 to collect the materials of the Bibliotheca Arabico-hispana, etc. (Madrid, 1760-70, 2 vols.). This famous work has a particular merit on account of its extracts from historical books in Arabic. The second volume, which treats of geographers and historians is very interesting, and contains numerous documents concerning the wars between the Moors and Christians upon the Spanish peninsula. Casiri died at Madrid, March 12,1791. See Hoefer, Nouv. Biog. Géneralé, s.v.