260 GNATS OR MOSQUITOES— CHAPTER X 



of those genera which have been separated on account of 

 differences of this kind. In examining the wing for these 

 characters, it is best to choose the middle portion, as they 

 are often less well marked in other parts, and it may be 

 added that occasionally, as in Panoplites uniformis, the 

 characters are not equally well marked in both sexes, so 

 that it is well, if possible, to examine both sexes. 



IE we examine the wing-veins of a typical Culex, it will 

 be found that they carry two sorts of scales, which alternate 

 with each other. On each side of the vein, placed close 

 against the membrane, is a row of short, racquet-shaped 

 scales ; while between each of these, but springing more 

 from the free convexity of the vein, are rows of long narrow 

 linear scales, which give to the wing its characteristic 

 shaggy appearance. In all but four genera the veins, though 

 differing sometimes in the density of their armature, and in 

 various other details, conform generally to this type, but in 

 Panoplites, the short lateral rows of scales of the veins of 

 Culex, in place of being small and of symmetrical outline, 

 are so large that, when one is accustomed to their appear- 

 ance, the genus can be recognised by means of a simple 

 lens. These peculiar scales are bracket-shaped, forming 

 a nearly right-angled, round-cornered triangle, whose base 

 is formed by the free end of the scale, a much magnified 

 figure of which is given on the right of the figure of the 

 Culex vein, while to its left is represented the arrangement 

 along a vein of the two sorts of scales, the linear scales 

 being in shape and length much as in Culex, but owing to 

 the comparatively larger size of the lateral rows of scales, 

 do not show so much beyond them ; so that the wing, 

 viewed with a hand lens, looks characteristicallj' scaly 

 instead of woolly. The only other genus that has scales at 

 all like these is ^dovujia, which has been separated from 

 the other Mdomina on this account. 



Another type of leptotaxis is exhibited by the wing-veins 

 of the genus Tcvniorhynchus (as modified), illustrated by the 

 figure on the extreme right. Here the distinction between 

 lateral and linear scales is hardly to be made out, as the 

 ranks of scales are disposed in half spirals, along and across 



