May, 1887.] 2G5 



14 (3) Petiole of upper vein from discal cell uot a quarter the length of the fork 



(radial vein strongly arched after the prsefurca) ochracea, Mg. 



15 (2) Prsefurca three or four times as long as the petiole of the first sub-marginal 



cell (base of prsefurca clouded). 



16 (17) Blackish-grey species licolor,M.g. 



17 (16) Ochreous species punctum,'^lg. 



18 (1) Subcostal vein continued a considerable distance after the cross vein con- 



necting it vFith the radial (praefurca always long). Petiole of upper vein 

 from discal cell (normally) from two to ten times as long as the fork 

 (fork sometimes absent). 



19 (26) Petiole of upper vein from discal cell scarcely longer than the fork, often 

 shorter ; marginal cross vein exceedingly near base of radial fork (except 

 in L. sepium), base of the discal cell not in a line with the base of the 

 two cells above, {conf. L. nemoralis, var.). 



20 (23) Great cross vein after middle of discal cell, antennae bearing bristly hairs 



three or four times as long as each joint. 



21 (22) Entirely ochreous, veins at end of wing approximating . fuscipennis, Mg. 



22 (21) Disc of thorax shining dark brown dtscicollis,'Mg. 



23 (30) Great cross vein before middle of discal cell, anteuuaj bearing bristly hairs 



about twice as long as each joint. 



24 (25) Pleurae grey lucorum, Mg. 



25 (24) Pleurce yellowish sepium, Yer. 



26 (19) Petiole of upper vein from discal cell (normally") from two to ten times as 



long as the fork (fork sometimes absent). 



27 (28) Light grey species, usually with stripes on thorax, medium sized .. 



nemoralis, Mg. 



28 (27) Thorax blackish, or brownish unstriped, small species. 



29 (30) Blackish, wings narrow, almost bare ^^a^a, Wlk. 



30 (29) Brown, wings broad and pilose, even on the disc near the tip... 



senilis, Hal. 



The above sixteen species form a very natural group, with the 

 ^possible exception of L. senilis, which, however, has all the essential 

 characters of the genus. Two or three more species may be expected 

 to occur in Britain, and a good deal remains to be done in synonymy, 

 as I certainly do not agree with the continental writers in all cases ; I 

 think, however, I have completely cleared up all the British synonyms, 

 many of which had previously been of considerable trouble to students. 



L. Meigenii: the Limnohia nigrina of Meig., Sys. Bes., vi, 277 

 (iS30) cannot retain its name against Limn, nigrina, Wied., Auss. 

 Zw. Ins., i, 37 (1828), even though they may some day be proved to 

 belong to very different genera (Osten-Sacken suspects Wiedemann's 

 species to be a Gnopliomyia, a genus near Trimicrd), so I have called 

 the European species L. Meigenii. It is a well-marked species, not 

 at all uncommon in Britain, though it seems to have been very much 

 overlooked on the continent. I have taken it at Lyndhurst, and in 

 several localities in North Scotland, and at Inchuadamph it occurred 

 very abundantly on a large flat moor. 



