MOSQUITOS OF THE PALAEARCTIC REGION. 267 



I have studied also the mesonotal bristles, but although these vary greatly in 

 number and development, I have not succeeded in discovering any differences which 

 are of more than specific value. The same applies to the bristles of the legs, but those 

 of the head sometimes offer useful generic characters. There are two great advantages 

 which bristle characters have over scale characters. Firstly, they are obviously 

 of much greater phylogenetic importance. Secondly, even when they are rubbed 

 off they always leave a recognisable scar. A denuded specimen may even be more 

 easy to examine than a perfect one, as the scales are sometimes liable to obscure the 

 bases of the bristles. 



In this paper I believe I have mentioned every name proposed for a mosquito 

 taken within the region dealt with, but I have not as a rule given additional synonyms, 

 nor have I attempted to unravel all the confusion caused by mis-identification, but 

 have tried merely to give clear definitions of the specific concepts. A large number 

 of the old descriptions are unrecognisable, and the types of many (some of Mei gen's 

 and all of Robineau-Desvoidy's) have apparently ceased to exist. Since, however, 

 it is highly probable that the old names all apply to species which are known at the 

 present day, I have endeavoured to form an opinion as to which species was most 

 likely intended by the describer, rather than give a separate list of indeterminable 

 species. I have not included Robineau-Desvoidy's Culex flavovirens and C. viridis 

 in the synonymy, because I consider it obvious that they were Chironomidae. 

 Linnaeus' Culex vulgaris may very likely have been a species of Aedes, but has 

 been considered byDyar and Knab to be a Shmilium ; it is therefore omitted. 

 Anopheles sacharovii, A. pseudopictus var. fleroivi, Portch., and A. siiperpictus var. 

 vassilievi, Portch., referred to by Russian writers (see Review of x^pplied Entomology, 

 B, ii, p. 108, and iii, p. 196), do not appear to have been described ; at any rate 

 I have been unable to trace the descriptions. For references to the original 

 publications of Culex annulatiis, de Fourcroy, C. niveus, Eichwald, and C. palUpes, 

 Waltl, I am indebted to Mr. C. Davies Sherborn, who has kindly allowed me access 

 to his manuscript. 



Tribe Anophei.ini. 

 Genus Anopheles, Mg. 



As the careful and detailed researches of Christophers have shown, there are 

 two main sections of the genus Anopheles, differing in small but quite easily definable 

 characters, both in the adult and in the larva, and undoubtedly to be regarded as 

 representing a very early separation of the genus into two distinct stocks. This 

 separation, according to Christophers, probably took place at least as early as the 

 Cretaceous. It is both desirable and convenient to recognise this important conclusion 

 in our nomenclature, and I therefore accept the divisions proposed by Christophers 

 (Ind. Journ. Med. Res. iii, p. 38v3, 1915) as subgenera. I do not consider thaf the 

 differences are sufficiently important or sharply defined to warrant the full generic 

 separation of the two old-world groups, nor do I consider it possible to subdivide 

 either of these groups in a satisfactory manner, since the connections between their 

 component species are so intricate and the intergradations so complete. As 

 Christophers has pointed out, the subgenus Anopheles shows much more real diversity 

 among its members than the subgenus Myzomyia, but when the species of the whole 

 world are taken into consideration it is impossible to recognise clearly-defined 

 divisions. 



The eggs of different species of Anopheles show remarkable variations in the 

 structure of the air-floats, while these appear to be constant for each species ; in 

 some instances, indeed, this is so markedly the case that the egg-structure (when 

 known) affords the readiest means of distinguishing closely allied forms. I have 

 therefore considered it worth while to collect into one block all the published figures 

 of the eggs of Palaearctic Anopheles. These, with the two or three new ones which 



