514 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



additional lower categories, which is considerable where large num- 

 bers of species are involved, they have a real value in delineating re- 

 lationships. 



As is to be expected some of the groups and subgroups are more 

 natural than others. For example. Groups A and E show so little 

 divergence as to suggest that they have not developed far beyond the 

 superspecies stage. On the other hand, Groups F and H are suffi- 

 ciently heterogeneous to suggest that they probably include even un- 

 related species. No effort has been made to make the groups more 

 natural by increasing their number, because of the impairment this 

 effects on their value as taxonomic aids. Iii contrast to this, every 

 effort has been made to keep the subgroups as natural as possible, 

 regardless of how many separate units this would make necessary. 

 As a result, it is in this category that polytypic species and super- 

 species may best be looked for. 



Although grou}) names have no true nomenclatorial standing, it is 

 felt wise for the sake of simplicity to utilize previously published 

 names where available. Consequently, except for certain necessary 

 minor modifications, Edwards' (1932) system of group nomenclature 

 has been employed here. The subgroup nomenclature is new with us. 



Although it is felt that the term "variety"' has little desirability 

 for use in the Culicidae, varietal status has been maintained for those 

 names designed as such in the original citations, except in the few 

 cases where additional work has been done and they have been shown 

 to be either full species or valid subspecies. 



The keys given in the following pages are all to the adult stage 

 only. Although many of the subgroups are distinct on larval char- 

 acters, it has not been found possible as yet to write subgroup keys 

 based on the larvae. 



"Where satisfactory group and subgroup revisions or treatments 

 exist, a reference is made to them only in the discussion of the division 

 in question and is not repeated under each involved species. "Where 

 such are not available or where additional life-history stages have 

 since been described, the reference is listed under the individual 

 species. 



We wish to acknowledge gratefully the cooperation of the follow- 

 ing people who made it possible for us to see the types of many of the 

 species treated in this paper: P. F. Mattingly, British Museum; 

 Alan Stone, Bureau of Entomology and Plant Quarantine, United 

 States Department of Agriculture; Mrs. J. Bonne-"^Vepster, Insti- 

 tute of Tropical Hygiene, Amsterdam ; D. J. Lee, "University of 

 Sydney; and H. "W. Kumm. Rockefeller Foundation, Rio de Janeiro. 

 Many others confirmed b}^ letters the presence or absence of types in 

 their collections and to them we are most grateful. 



