Mr. F. W. Edwards on British Limnobiidae. 203 
D. pseudomorio Alex. This has only very recently 
(Trans. Amer. Ent. Soc., xlvi, p. 3, March 1920) been 
described by Alexander from Saitama, Japan. The 
hypopygium agrees closely with Alexander’s description, 
and is very different from that of D. morio, so that I have 
no doubt, in spite of the wide geographical gap, that the 
species is correctly determined. The British Museum 
possesses three males and one female from Loch Assynt, 
Sutherland, vi. 1911 (Zt.-Col. Yerbury). 
RHIPIDIA. 
Two subgenera are represented among the British species. 
R. maculata is a true Rhipidia (the type of the genus) with 
the antennae bipectinate in the male and almost simple in 
the female. R. ctenophora Lw., and R. uniseriata Schin., 
belong to Alexander’s subgenus Monorhipidia, with 
unipectinate antennae in the male, subpectinate in the 
female. The last named has not hitherto been recorded 
as British, but there is a female in Stephens’ collection in 
the British Museum, and three females in the Cambridge 
Museum from Brockenhurst (Sharp). It differs slightly 
from R. ctenophora in the structure of the antennae, and 
in having no dark spot in the basal third of the wing. The 
British Monorhipidia both have the subcostal vein elongate, 
as in Limnobia. 
LIMNOBIA. 
L. dilutior sp. n. 
Similar to L. nubeculosa and L. flavipes, and very closely resembling 
L. hercegoviniae Strobl, from all of which it appears to be distinct. 
Head dark grey, the frons lighter. Antennae blackish; _ first 
flagellar joint with its basal half conspicuously yellow; second and 
third also narrowly yellowish at the base. Proboscis and palpi 
black. Thorax much darker than in L. flavipes ; the pleurae, 
scutellum and postnotum with a heavy grey dusting. Praescutum 
with an ill-defined, slightly shining dark brown median stripe ; 
remainder of mesonotum dull. A blackish spot just in front of the 
wing-base, much smaller than the similar spot in L. flavipes ; another 
small spot in the middle of the pleurae, which appears blackish 
when seen from above. Abdomen almost uniformly dark; the first 
three or four sternites yellowish towards base ; hypopygium lighter, 
in structure practically identical with that of L. flavipes. Legs 
darker than in L. flavipes, especially the femora, which have two 
darker rings (both rather indistinct, owing to the dark ground- 
