33 



bionomic series. The whole collection, accompanied by 

 admirable data, is a valuable accession to the European 

 species — at present rather weakly represented in the Depart- 

 ment. 



The material of their great Mendelian experiment in moth- 

 breeding has been generously presented to the Department 

 by L. B. Prout, Esq., F.E.S., and A. Bacot, Esq., F.E.S. The 

 special interest of this important accession has been pointed 

 out in a separate section of this Report (see p. 4). 



Additions to the British Collections in 1909. 



The collection of British Diptera has again received a 

 splendid series of accessions owing to the generous assistance 

 rendered by Col. J. W. Yerbury. The British Diptera — 

 amounting to considerably over 1,500 — which have been 

 catalogued and incorporated have been determined by G. H. 

 Verrall, Esq., J. E. Collin, Esq., or by Col. Yerbury himself, 

 and the written or printed name is affixed to every specimen. 



The numerous localities are distributed over the following 

 counties: — Caithness (1899), Elginshire (1899), Inverness- 

 shire (1904-5), Nairnshire (1904-5), Perthshire (1898), Suther- 

 landshire (1900, 1904), Glamorganshire, many localities (1907 

 -8), Herefordshire, many localities (1897-1906), Devonshire 

 (1896, 1903, 1909), Dorset (1894, 1906-7), Hampshire (1897, 

 1908-9), Oxfordshire (1907), Nottinghamshire (1906), Cam- 

 bridgeshire (1898, 1909), Norfolk (1906), Suffolk, many 

 localities (1907-9), Essex (1899, 1907-9), Surrey (1906), Kent 

 (1897, 1907-8), Co. Kerry (1901). The collection also in- 

 cluded specimens from the Scilly Islands, St. Mary's and 

 Tresco (1904). The data of' time and place are admirably 

 precise. In addition to this magnificent accession, Col. Yer- 

 bury presented 24 British insects belonging to various groups, 

 and 44 specimens for the parts of the bionomic series which 

 illustrate the struggle for existence in insects. They include 

 9 Asilid flies and their prey — Dipterous in 6 cases, a Ten- 

 thredinid in one, and an Acridian in one. Two male Asilus 

 crabroniformis were captured (Studland, Aug. 3, J 909) with 

 the Acridian, the probable interpretation being that while 



