INSECTS DIPTERA Flies Out of the three thousand odd species of Diptera at present known to be British the following list contains the names of some three hundred and sixty a result which is solely due to the paucity of collectors of this order of insects. For owing to its natural features, and especially to its richness in heath-land, Surrey is peculiarly adapted to the needs of the sunshine-loving, flower-haunting Diptera ; so that if properly studied during a series of years the actual total of species would probably not fall short of those of Hampshire or Devon. An asterisk (*) signifies that the specimen referred to is in the collection of the British Museum, and that the present writer is respon- sible for the determination. Collectors whose names frequently recur are indicated by their initials, as follows : Y. = Lt.-Col. Yerbury. O. G. = W. R. Ogilvie Grant. A. B. = A. Beaumont. [Such of Mr. Beaumont's species as are preserved in his own collection, and have not been presented by him to the British Museum, were determined either by the late Dr. Meade or by Mr. Billups.] F. W. T. = F. W. Terry. G. H. V. = G. H. Verrall. E. E. A. = E. E. Austen. F. B. J. = F. B. Jennings. T. R. B. = T. R. Billups. [According to a note by Mr. Billups in Entomologist, vol. xxiv, (1891), p. 236, some at least of his captures were determined by the late Dr. Meade, and others by Mr. Brunetti.] Br. Fl. = Verrall, British Flies, vol. viii. C. = Curtis' British Entomology, vol. viii. In the case of species recorded in entomological journals the refer- ence to the original record is given : Ent. Mo. Mag. = Entomologist's Monthly Magazine ; Ent. = Entomologist. Species recorded in Curtis' British Entomology and elsewhere have only been included when there seemed reasonable probability of their having been correctly determined, while the nomenclature has been revised in all cases. ORTHORRHAPHA NEMATOCERA CECIDOMYIDJE Cecidomyia pteridis, Mi'ill. Shirley ; larvas in rolled leaflets of fronds of Pteris aquilina ; Sept. 1871 ; A. Mtiller, Ent. Mo. Mag. vol. viii. (1871), p. 99 salicina, Schrk. South Norwood ; larvae infesting the shoots of Salix alba ; Aug. 1869; A. Mtiller, ibid. vol. vi. (1869), p. 109 taxi, Inchb. Godalming ; bred from galls on branches of Taxus baccata ; CECIDOMYID.S (continued) June, 1869; A. Mtiller, loc. cit. p. 61 Cecidomyia ulmariae, Bremi. Godalming ; bred from galls on Spiraea ulmaria, found July 25, 1865 ; first ima- gines emerged Aug. 29, 1865 ; also bred from galls on same plant, found Aug. i, 1865 ; imagines emerged Aug. 10, 13, 1 6, 1865 ; galls also found Oct. 13 ; H. W. Kidd, Ent. Mo. Mag. vol. iv. (1868), p. 233 urticas, Perris. Merton Abbey ; bred from galls on Urtica dioica, found 151