55 



tans very much, but the two or three last thorns in the pecten are said to be de- 

 tached from the other thorns. It may be added that the larvae from the little pond 

 in which my supposed 0. uexans was hatched, had no detached thorns in pecten; 

 apart from their small size and remarkably late occurrence' (July) they were in 

 full accordance with the larvae of 0. cantans. As pointed out by EDWARDS (1912 

 p. 195) and stated by HOWARD, DYAR and KNAR (1917 p. 699) the species is identi- 

 fied with the American species Aedes sylvestris (Theobald) (Dyar and Knab). 



Geographical distribution: It seems widely spread over the whole of 

 Europe, but has as far as I can see a more southerly range. It also appears over 

 the greater part of Asia. 



6. O. excrucians (Wlk.). 



A. abfitchii (Felt) Dyar and Knab. 



Tab. V. 



Description. Female: Proboscis moderate; vestiture of brown-black scales. 

 Palpi rather stout, short, about one-fourth as long as the proboscis clothed with 

 black scales, tips and bases of joints with yellowish-white scales. Antenna? with 

 tori subspherical, with a cup-shaped apical excavation, luteous, brown, and with a 

 patch of small white scales on the inner side. Occiput blackish, broadly clothed 

 with narrow, curved creamy-white scales in the middle, a diffused patch of brow r n 

 ones laterally, and many slender erect forked black scales on the vertex. Bristles 

 bordering the eyes black. 



Prothoracic lobes elliptical, remote dorsally, blackish, clothed with pale yellow 

 scales and black bristles. Mesonotum dark brown, clothed with narrow curved 

 scales, a broad median stripe of golden brown ones, anterior margin narrowly and 

 the whole of sides of disk as well as the antescutellar area with pale yellow ones; 

 bristles moderate, black. Scutellum trilobate, luteous each lobe with a group of 

 black bristles and clothed with narrow, curved, pale yellow scales. 



Abdomen subcylindrical, flattened, posterior segments tapering; dorsal vestiture 

 of black scales with a few pale ones intermixed, each segment with a broad basal 

 band of creamy-white scales and a narrow row of pale scales at tip; on the sides 

 the basal bands widen into large triangular spots, particularly on the , sixth and 

 seventh segments; first segment w r ith a large patch of white scales and many pale 

 cilise; venter clothed with creamy-white scales and with median segmental spots of 

 black ones, tending to form a longitudinal stripe. Cerci black. 



Wings moderate, hyaline; petiole of the second marginal cell somewhat shorter 

 than its cell, that of second posterior cell about as long as its cell; basal cross-vein 

 less than its own length distant from anterior cross-vein; outstanding scales long, 

 broadly linear, with blunt tips. Halteres entirely pale. 



Legs moderately slender; femora clothed with creamy scales below r , black and 

 whitish ones about evenly intermixed above, the tips narrow r ly white; tibiae \vith 

 black and whitish scales intermixed, the black ones predominating at the apex, the 



