For their information concerning the _Tractatus_, the modern bibliographers evidently rely entirely on entries in the catalogues of the respective libraries. The 1739 Catalogue of Arabic and Hebrew MSS. in the Bibliothèque Nationale contains the following entry:[347] ‘Codex bombycinus, Aleppo in bibliothecam Colbertinam anno 1673 illatus, quo continetur R. Mosis Maemonidae de morborum causis et illorum curatione tractatus, Arabice, charactere Hebraico.’ Careful examination of the manuscript disclosed the fact that it contained no fewer than four works of Maimonides, viz. on Poisons,[348] on Asthma,[349] the _Tractatus de Regimine Sanitatis_,[350] and the _Tractatus de Morbo Regis Aegypti_,[351] all bound together in confusion.[352] All these are known to be by Maimonides, and there is nothing besides them in the volume. There has always been a good deal of confusion about the works _de Regimine Sanitatis_ and _de Morbo Regis Aegypti_. The former is variously known as _de Regimine Sanitatis, de Cibo et Alimento, de Dietetica_, ‘the letter to the Sultan’, or as ‘the Consultation concerning (the Sultan) Al Afḍal’.[353] The latter also has a number of titles, such as _de Causis Accidentium,[354] de Morborum Causis et Curatione_, and _Responsum ad Regem Raqqa_, in addition to its title of _de Morbo Regis Aegypti_. In 1514, in Venice the two treatises were printed together in Latin as one work.[355] Leclerc[356] has made confusion worse confounded by saying that ‘ce que l’on a désigné sous les titres, _De Morbo Regis Aegypti, De Causis Accidentium, De Causis et Indiciis Morborum, De Cibo et Alimento_, ne sont autre chose que tout ou partie du même ouvrage’.[357] No doubt he was led into making this statement partly by the fact that Wüstenfeld[358] gives the title of _de Causis et Indiciis Morborum_ both to the Bibliothèque Nationale MS. (which Leclerc knew as _de Causis Accidentium_) and to the Bodley MS. The entry concerning the latter in Uri’s Bodleian Catalogue of 1787[359] reads as follows: ‘Codex bombycinus, anno Hegirae 765, Christi 1363 exaratus, folia 116 implens. Comprehendit succinctum de omnium corporis humani morborum causis, signis et remediis tractatum ab Ibn Hobaish Hierosolymitano ex Hebraica lingua in Arabicam conversum, cui sectiones sex supra centum sunt. Initium fit a morbis capitis; finis in elephantiasi. Composuit Musa Ben Maimun Alcortubi, Israelita. [Marsh 379.]’ The MS. bears upon one of its pages the title هذا كتاب الاسباب والعلامات الحكيم ’موسى بن ميمون القرطبي الاسرايلي ‘This is the book of the causes and symptoms, by the Doctor Mûsa ibn Maimûn the Cordovan, the Israelite.’ (Plate XLI.)