OF WASHINGTON, VOLUME XI, 1909. 



of both* the new and old worlds. He does not, however, go into 

 the matter in sufficient detail and his presentation is not con- 

 vincing. We find in the male genitalia excellent characters of 

 specific definition. It is true that Theobald describes these 

 structures, but he has not illustrated with accuracy the basal 

 parts that show the specific distinctions to the best advantage, 

 having confined his attention chiefly to the appendages of the 

 side pieces, which are practically alike in all the species. 



The exact definition of Culex pipiens, therefore, still remains 

 in some obscurity, and we propose now to resolve it. We would 

 restrict Culex pipiens to that species with the basal clasps of 

 the male genitalia as shown in our figure 4, plate n. We omit 

 the side pieces in our figures as they are alike in all the species 

 referred to. Our specimens are from Copenhagen, Denmark, 

 (Dr. F. Meinert), St-Remy-la-Varenne, Maine et Loire, 

 France (R. du Buysson), and Buda-Pesth, Hungary (Dr. C. 

 Kertesz). We have bred specimens with similar genitalia in 

 America, and are able to confirm the occurrence of the species 

 here, no doubt as an importation. 



Our common rain-barrel and house mosquitoes comprise the 

 following, as defined by the male genitalia. The adults are 

 generally separable on minor characters of coloration, which 

 we shall describe fully elsewhere ; but the colorational char- 

 acters of these species are unstable and unreliable to a large 

 extent ; neither are the venational differences pointed out by 

 Theobald of any value. 



Culex pipiens Linnaeus. 



The harpes (Plate n, fig. 4, a) with a crown of spines as 

 in all the species here discussed, but with rudimentary basal 

 process (fig. 4, b}. Harpagones divided into four plates, the 

 upper one (fig. 4, r ) rather narrow, long, exceeding the tip of 

 the harpes, often bent nearly at right angles near the middle ; 

 second piece (fig. 4, a?) a rather broad plate narrowed at the 

 tip, with a rounded point : third piece a thin, often obscure 

 plate, similar to the second piece but smaller and weaker; 

 fourth piece (fig. 4, /) a broad, concave stout plate with a nar- 

 row rounded tip. 



The species is especially characterized by having the harpa- 

 gones divided into four plates, all the allied species having at 

 most three. In the lowest forms here shown the harpones are 

 divided into two separate plates, the outer one variously 

 toothed, as in pro.vinius (fig. 6), salinarius (fig. 7), similis 

 fig. 8 s ), and lachrimans (fig. 9) : next they become divided into 

 three plates, as in rest nans (fig. 5), the second division still 



