242 Mr. E. Saiuiders' Synopsis of 



black, with the exception of the apex of the abdomen, 

 which is whitish ; in others the thorax has a wide yellow 

 band in front, the 2nd segment of the abdomen, and 

 sometimes also the 1st, is yellow, the 3rd black ; the 

 4th and following segments white, or white with a 

 narrow red line between the black and white, or red ; in 

 the (? the apex of the abdomen is often clothed with 

 almost pink hairs, which gives a most characteristic 

 appearance. I will give here the structural and other 

 characters by which this species can be known from its 

 allies. 



(J . This sex may be known from any other species by the shape 

 of the genital armature, the sagittae of which are curved outwards 

 at the apes and thickened, with their apical margin truncate ; they 

 are also bluntly tootJied beneath near the middle ; the squama is 

 long, sinuate on its inner margin ; the lacinia bidentate at the apex, 

 the inner tooth longer and more curved (see PI. XII., fig. 14). 

 Besides these characters the white-tailed ^ may be known from 

 terrestris by having the 2nd joint of the flagellum shorter, it only 

 being of the same length as the 3rd, whereas in terrestris it is 

 nearly once and a half as long, by the longer cheeks and face, and 

 by the longer more erect pubescence, and by the narrower more 

 convex posterior tibiae, which are destitute of any longitudinal im- 

 pression ; from i^ratoritm and DerJiameUus the red-tailed ^ may 

 be known by the form of the genital armature, the larger size and 

 more erect pubescence, and the shape of the posterior metatarsi, 

 which are much more narrowed at the base, and the more arcuate 

 joint of the antennae. 



^ and 5 . May be known fi'om terrestris by the longer face and 

 cheeks, the latter being nearly as long as their apical width, by the 

 less defined yellow abdominal band, which is of a less bright colour 

 than in terrestris var. lucoruin, and generally extends on to the 

 basal segment, and also by the less compressed apical ventral seg- 

 ment ; the red-tailed varieties differ from j^t'citoriwi, which they so 

 much resemble, in the broader rather more squarely-shaped face, 

 the shorter tongue and palpi, these latter hardly so long as the 

 head, and the narrower black abdominal band, which occupies the 

 3rd segment only. Length, ^ and j 12— 17 mm., ^ 10—12 mm. 



Hah. Eare. Croydon ; Southend ; Brighton Downs ; 

 Bristol ; Carlisle ; Yorkshire ; Scotland. 



