NOTES ON CULICIDAE. 215 



The males and one female presented to the British Museum by the Imperial Bureau 

 of Entomology. 



The " forking "" of the clasper is due to the spine being placed far back, instead of 

 being terminal as usual ; it is an exaggeration of the structure found in 0. vexans, 

 Mg., and allied species, and may possibly indicate a connection between these species 

 and 0. adersi. The tuft of brownish yellow scales at the apex of the side-pieces is 

 almost as long as the side-pieces themselves, and is very conspicuous. 



Group Ochlerotatus, s. str. 



After the exclusion of the Finlaya and Diceromyki groups, the remainder of the 

 genus Ochlerotatus consists of a veiy heterogeneous mass of species, some more closely 

 allied than others. It does not appear to be possible to draw any hard and fast linos 

 within this group, since there are so many intermediate forms. The most natural 

 classification of the group is probably one based on the structure of the male genitalia, 

 but imfortunately there seem to be no tangible female characters which can be 

 associated with those of the male. The following main groups may be distinguished : 



(a) Group OcJilerotatus, in the most restricted sense. Side-pieces of genitalia with 

 well developed apical and basal lobes ; claspers with a long terminal spine ; har- 

 pagones well developed, with a more or less flattened articulated terminal process. 

 Species usually without any striking ornamentation, and with narrow scales on the 

 scutellum and vertex. This group roughly corresponds to Culkada as used by 

 Theobald, and includes the majority of the European, North American and Australian 

 species. Transitional forms to the next group are to be found in 0. onnuUferus 

 (Ludlow) and 0. fryer i (Theo.), in which the apical lobes of the side-pieces are absent, 

 the harpagones small and with their terminal process short and spine-like. 



(6) Group Ecxtdex. Side-pieces without apical lobes, but the basal lobes well 

 developed and haiiy ; claspers with the terminal spine inserted at some distance 

 before the tip, giving a forked appearance ; harpagones absent. In general aspect 

 the species resemble those of the preceding group. The following species may be 

 included : — 0. vexans (Mg.), 0. hirsutus (Theo.), 0. cummmsi (Theo.), 0. denlatus 

 (Theo.), 0. quasiunivittatus (Theo.), 0. caliginosiis (Grab.). 



(c) Group Aedimarphus. Side-pieces without either apical or basal lobes ; claspers 

 usually highly specialised, though often resembling those of the preceding group ; 

 harpagones absent. This group, though on the whole a natural one, seems to merge 

 on the one hand into the Ecculex group and on the other into Stegomyia. It includes 

 most of the species placed by Theobald in Aedimorphus and Reedomyia, with a few 

 other African and Oriental species. 



Ochlerotatus annulipes, Mg. 



This species occurs abundantly on Wood Walton Fen, Huntingdonshire, where it is 

 a severe daytime biter, like its ally 0. niaculaius (Mg.). A number of specimens from 

 this locality were presented to the British Museum in 1913 by the Hon. N. C. 

 llothschild, by whose kind permission I visited the fen in April 1914: with the object 

 oi searching for the larvae of this species and Aed^s siuerens, another species which 

 Mr. Rothschild had taken in numbers there. Although not successful in obtaining 

 larvae of the Aedes, I found large numbers of 0. aiuiidlpe.'i larvae in shallow temporary 



