103 



following segments on the sides narrowly reddish yellow ; and -indistinct 

 /ellowish grey middle line extends from the base of the second seg- 

 ment to near the apex, and an inconspicuous roundish yellowish grey 

 spot on each side of the dorsal line rather above the middle of each 

 segment excepting on the two basal segment and becoming much more 

 indistinct on the sixth segment, while on the seventh segment it is, 

 almost always wanted but the segment covered all over with a yellow- 

 ish dust; the grey dorsal line usually tends to widen into the triangles 

 at the middle of the hind margin of each segment, especially from the 

 fourth segment onwards; pubescence suberect, long but not at all 

 dense, mainly black on the disc but with shorter more sloping pale 

 yellow hairs on the hind margins ; side-marginal pubscence long at;d 

 outstanding and usually all yellowish along the pale margin. , Ventre 

 ashy grey with the sides at the basal segments (from the basal seg- 

 ment to the third) yellowish brown, and very often the middle parts of 

 these segments usually slightly brownish ; pubescence rather shortand sloping 

 on most of the disc but longer about the sides, and longer and more 

 tangled on the two basal segments, and all pale greyish yellow except 

 for the rather numerous erect but curved bristly black hairs on the., 

 disc of the seventh segment and more or less on the sixth segment. 

 Genitalia pale ferruginous with a two-jointed lamellae on each side, of 

 which the basal joint is subquadrate and the apical joint half ovate, 

 and these lamellae furnished with a short and fine pale yellowish grey 

 pubescence. 



Length : about 10.7 mm. 



This species is very closely allied to H. pluvialis L., but may 

 be distinguished from the latter by its comparatively long and much 

 more dusted third joint of the antennae in the female, by its more 

 muddy coloured wings, by its large sized body, by its more simple 

 hyaline markings of the wings, and by its much less greyish spots on 

 the abdomen. H. tristis is apparently distinguished from the other 

 two species of this genus from Japan by its narrow sinuated hyaline 



