MOSQUITOS OF THE PALAEARCTIC REGIOX. 281 



down at some point or other. The character finally adopted by Howard, Dyar and 

 Knab, that of the head bristles, is not indicated in Erctmopodites, which is unquestion- 

 ably a Sabethine genus, while it is shown in some Culicine genera, notably Megarhimis. 

 There is, no doubt, a group of genera (or more probably two or three independent 

 groups) which are more closely related to one another than to other Culicines, but 

 in adult structure there is certainly no hard and fast line to be drawn. In regard 

 to the absence of the anal brush of the larva, which is the one common and out- 

 standing feature of all Sabethini, Colonel Alcock has suggested to me (I consider 

 with great plausibility) that this may be an adaptive character, and therefore not 

 necessarily indicative of relationship. As he points out, larvae living in small 

 confined spaces, as do almost all of the Sabethini, would not require the anal brush 

 for swimming ; and as it is absent in the first stage, there seems no reason whatever 

 why its development should be proceeded with in the later stages. In confirmation 

 of this view, it may be remembered that some of those species of Aedes [Stegomyia] 

 which live in small collections of water have the brush much less developed than in 

 the free-living forms. 



The ancestral form probably had pulvilli and spiracular bristles, narrow scales, 

 and a non-carnivorous larva ; partaking thus of some of the characters of Theohaldia 

 and Lutzia ; no such form is known, however. 



Table of Genera of Palaeayctic Culicine Mosquitos. 



Adults. 



1. Vein A„ (6th) ending below or a Httle before the level of the base of R., 



(2nd) ; no microtrichia on wing-membrane . . . . Uranotaenia 



Vein A„ ending well beyond the level of the base of R., ; wing mem- 

 brane with microtrichia 



2. Pulvilli absent 



Pulvilli present . . 



3. Spiracular bristles present 

 Spiracular bristles absent 



4. Proboscis slender, flexible, as long as the whole body ; one pro-epimeral 



bristle (or none) ; no sternopleural bristles. . . . . . Rachionotomyia. 



Proboscis otherwise ; sternopleural bristles present . . . . . . . . 5 



5. Proboscis rigid, hooked ; no pro-epimeral bristles ; cell R. extremely 



short ; a V-shaped thickening of the wing-membrane between 



veins Cuj and Cug (forks of 5th) . . . . . . . . Megarhinus. 



Proboscis flexible, straight in repose ; several pro-epimeral bristles ; cell 



R2 long; no V-shaped thickening of wing-membrane.. .. Theohaldia. 



6. Two pro-epimeral bristles . . . . . . . . . . Orthopodomyia. 



Several (about 5) pro-epimeral bristles . . . . . . . . . . 7 



7. No post-spiracular bristles ; female claws simple 



Taeniorhynchus (subgenus CoquilleUidia) . 

 At least a few small post-spiracular bristles present ; female claws nearly 

 always toothed . . . , . . . . . . . . . . . . 8 



8. Proboscis not very stout, straight or curved upwards in repose.. Aedes. 

 Proboscis stout, apparently (from dry specimens) curved downwards in 



repose . . . . . . . , . . . . . . . . . . Armigeres. 



9. Lower mesepimeral bristles numerous . . .. .. .. .. Lutzia. 



Normally one lower mesepimeral bristle ; often none, but very rarelv 



two or three . . . . . . . , . , . . , . . . Culex. 



