240 GXATS OR MOSQUITOES — CHAPTER IX 



cribed. During the year that has elapsed since the appear- 

 ance of the first edition, the attention that has been drawn 

 to the famil}' by the estabHshment of their instrumentahty 

 in the transmission of at least three of the most serious of 

 the maladies peculiar to tropical regions has drawn minute 

 attention to the group in all parts of the world, and the 

 timely activity of the authorities of the British Museum 

 and of our Royal Society, has resulted in the acquisition by 

 the Museum of perhaps the largest collection of insects of 

 any one family that has ever been brought together, and 

 this has been further increased by the loan of collections 

 sent for comparison by naturalists from all parts of the 

 world. The examination of this enormous mass of material 

 has been entrusted to Mr. F. V. Theobald, whose reputation 

 as one of our most thorough dipterologists cannot fail to 

 be enhanced by the encyclopaedic Monograph, now in the 

 press, which has resulted from his labours. 



As the result of his examination of the family, Mr. 

 Theobald summarises the outcome of his labours as 

 follows : — 



" Total previously described good species, 164. 



" Species recognised and redescribed, 116. 



" Other descriptions, probably invalid owing to their 

 shortness and the apparent absence of types, 25. 



" Described as distinct, but found to be synonymous 

 with other species, 80. 



" New species described, 186. 



" Therefore the number identified and redescribed and 

 the new species described in these volumes number 252. If 

 to this we add the 48 species not yet identified, we get the 

 total known number of CiiUcidce, 300." 



It must not, however, be supposed that this represents 

 more than the total of species examined at the time of the 

 earlier sheets of his monograph going to press, nor must the 

 reader expect to find it correspond exactly to the number 

 given in the present edition, as the simultaneous passage of 

 both our tasks through the press has been continually 

 retarded by the receipt of fresh material, which not unfre- 

 quentiy has necessitated the reconsideration of the position 



