18S6.J 159 



I mean a slightly larger darker species than chorea, but with the wing 

 markings consisting of a distinct stigma only ; I have numerous 

 females, but only one unsatisfactory male. I believe the D. stigmatica 

 of the continent is a good distinct species, and I have no doubt it 

 occurs here ; my so-called specimens extend from the New Forest to 

 Tongue, but are most abundant northwards. My D. lutea may always 

 be known from D. mitis by the yellowish base of the antennae, and the 

 basal lamella of the male genitalia has a process beneath which is not 

 present in D. chorea, it is common in Sussex and Hampshire ; very 

 close to this, only with very different genitalia, comes another yellowish 

 species of which I possess no good specimens ; then comes what I 

 may consider D. mitis, Mg. (rather than give it a new name), it has 

 the antennae all blackish-brown, and the basal lamella of the genitalia 

 with a long process beneath ; it was common in the New Forest and 

 at Lymington in June, 1885, but I have not met with it this year. 



Under this group of species come Walker's L. albifrons, glohata, 

 sera, inusta, disjuncta, stigma, and excisa ; I hope at some future date 

 to dispose of these with greater certainty, when I thoroughly under- 

 stand those in my own collection. 



D. sericata, Mg., is a perfectly distinct and not uncommon species ; 

 it is much darker than the others, and has almost blackish legs, while 

 the wings are entirely without even a stigma ; Walker described it as 

 a new species, which he called L. glabrata (Ins. Brit. Dipt., iii, 299), 

 that name was, however, pre-occupied by Meigen (1818), and I see no 

 reason to doubt its being Meigen's L. sericata. I have taken it in 

 Sussex, Kent, in my own house, and once in abundance in a grass 

 field near here ; I think it is a May species only just extending into 

 June. 



D. dumetorum, Mg. : Walker has mixed up D. diimetorum and 

 didyma in his descriptions in Ins. Brit. Dipt., iii, 296 & 297, because 

 D. dumetorum is the species with two spots on the costa, and D. didyma 

 the one with three spots, in other respects he is right, and all speci- 

 mens named by him which I have seen were correct. I have seen the 

 type of L. transversalis,W\k., which is certainly D. dumetorum ; while 

 all the specimens I have ever seen called L. osciUans, Hal., were cer- 

 tainly D. didyma, and Haliday's description (Ent. Mag., i, 154), 

 perfectly agrees with D. didyma. The habits of the two species are 

 very distinct, D. didyma occurring almost everywhere that water runs 

 down an almost perpendicular surface, such as sluice gates or overflow 



