vi. Pre for I 



their places any new species that might have been described 

 in the interval ; but, on reaching England, I found that, in 

 this portion, practically none of the old material could be 

 utilised. By the timely energy of the authorities of the 

 British Museum, and of the Royal Society, an enormous 

 collection of mosquitoes had been brought together; and 

 the work of preparing a monograph of the family, based 

 on the material so collected, had been entrusted to my 

 friend, Mr. Theobald, who met me with the news that, 

 to say nothing of some 160 new species, almost all the 

 old descriptions were hopelessly inadequate, even where 

 they were not positively misleading, and that he had found 

 it necessary to revise the entire classification of the family. 

 To adhere to the original plan of quoting original descrip- 

 tions in extenao was obviously out of the question, as the 

 text of Mr. Theobald's descriptions of new species would 

 alone have filled more tlian the entire space of my first 

 edition, and the only alternative was to redescribe, as 

 concisely as possible, every member of the family, as 

 illustrated in the splendid collection now at our disposal. 



In the case of the genus Anopheles, and of some other 

 important genera, and generic types, the course adopted has 

 been to prepare a new description from the actual speci- 

 mens, but for the rank and file of the still enormous genus 

 Culex, it proved more convenient, though I have seen and 

 handled most of the species enumerated, to epitomise the 

 descriptions of the monograph. In both cases the plan 

 followed has been to carefully describe the same structures 

 in all, and to append to each description, in smaller type, 

 a few detailed characters ; emphasising those that separate 

 the species from its neighbours ; but to save space, the 

 conventional plan of repeating, in the detailed notes on a 

 species, the characters already given in the short descrip- 

 tion, has been deliberately avoided. With this object, too, 

 certain numbers and signs have been employed in the 

 descriptions, the explanation of which will be found in 

 the introductory remarks to the systematic portion and 

 in those on the genus Anopheles. 



From what has already been said, it follows that many 



