Introduction. 



Vll. 



subject of the dissemination of disease has been kept prominently 

 in view, and the statements of investigators and observers who have 

 devoted themselves to this question will be found summarised under 

 special headings. In the records of specimens in the possession of 

 the Museum, the names of collectors and donors are printed in 

 italics, in parentheses. 



Within the last few years many Colonial Medical Officers in 

 Africa, acting under official encouragement in compliance with 

 instructions from His Majesty's Secretary of State for the Colonies, 

 have made and forwarded to the Museum collections of blood- 

 sucking flies occurring within their districts. Had it not been for 

 the efforts of these and other gentlemen, which have resulted in a 

 welcome increase in the amount of the material in the possession 

 of the Museum, the production of this book would have been well- 

 nigh impossible, and grateful acknowledgment of assistance rendered 

 is accordingly due. While the names of all who have thus assisted 

 cannot here be enumerated, special mention must be made of 

 Colonel Sir David Bruce, C.B., A.M.S., F.R.S. ; the late Dr. W. A. 

 Densham, of Uganda ; the late Captain Hallam Hardy, R.A.M.C., 

 of the Nyasaland Protectorate ; Dr. W. M. Graham, W.A.M.S. ; 

 Dr. A. Yale Massey, late of the Tanganyika Concessions, Limited ; 

 Dr. J. E. S. Old, of the Nyasaland Protectorate; and Dr. F. 

 Creighton Wellman, late of Benguella, Angola. To the authorities 

 of the Museum National d'Histoire Naturelle, Paris, the British 

 Museum (Natural History) is indebted for the loan of a number of 

 types in their possession, which has rendered it possible to include 

 figures of several species of Tabanus recently described by Mr. 

 J. R. M. Surcouf. The author desires to express his acknowledg- 

 ments to Mr. C. 0. Waterhouse, Assistant Keeper in charge of the 

 Insect Section, Zoological Department, British Museum (Natural 

 History), with whom it is but just to state that the idea of this 

 book originated. 



In conclusion it is perhaps permissible to point out that in the 

 matter of practical investigation by means of experiments on the 

 spot, in order to determine the conveyance or non-conveyance of 



