Last year Professor Sachau, of Berlin, pointed out to me among the MSS. in the British Museum an important work of Arabic philology. The work bears the title “ Critical Observations on the Mistakes of Philologers by Abu’l-Qāsim ‘Ali ibn Ḥamza al-Baṣri ” (cf. Rieu, Supplement to Catalogue of Arabic MSS., No. 841). The British Museum MS. is a modern copy of an ancient codex in the Khedivial Library in Cairo, and is on the whole legible and accurate, though at points it is not quite reliable. Another similar copy exists at Strassburg (cf. Nöldeke, Z.D.M.G., 1886), and the Library of Count Landberg contains a third. The work includes ‘observations’ on the following eight ancient philological works:—(1) The Nawādir of Abu Ziyād al-Kilābi al-’A‘rābi; (2) the Nawādir of Abu ‘Amr ash-Shaibāni ; (3) the Kitāb an-Nabāt of Aḥmad ibn Da’ūd ad-Dīnawari; (4) the Kāmil of al-Mubarrad; (5) the Faṣīḥ of Tha‘lab ; (6) the Gharīb al-Muṣannaf of Abu Obaid Qāsim ibn Sallām; (7) the Iṣlāḥ al-Manṭiq of Ibn as-Sikkīt; (8) the Makṣur wa’1-Mamdūd of Ibn Wallād. The ‘ observations,’ though sometimes pedantic, are usually valuable from a lexicographical point of view. Abu’l-Qāsim gives many corrections of the statements of the authors on whose books he comments, and supports his contentions by quotations from the poets, which are in many instances not to be found in the lexicons or in similar works.