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Mr. F. W. Edwards on British Limnobidae. 217 
(Mg.) by the dark line down the middle of the thorax; and. 
O. uncinata (Meij.) by the whitish pubescence on the hind 
metatarsus, contrasting with the dark tibia, which is very 
noticeable in life. The remaining three species are only 
distinguishable with certainty by the male hypopygium, 
but the differences in this organ are very striking. 
O. uncinata (Meij.). This is a common and widespread 
species, probably the one which Verrall regarded as O. 
nodulosa. The character of the hind metatarsus seems to 
be diagnostic (but compare the two new species); it was 
not mentioned by Macquart, and therefore de Meijere may 
be justified in restricting Macquart’s name to the next 
species, though O. wncinata is the species which has the 
male antennae most distinctly nodose. 
O. nodulosa (Mcq.) Meij. This is the other common 
species noted by Verrall and Carter as occurring in this 
country. 
O. hederae (Curt.) Meij. Curtis’ description and figures 
would apply about equally well to O. nodulosa, but de 
Meijere’s selection will fix this name definitely. All the 
specimens I have seen are from Scotland : Nairn and Loch 
Assynt (Yerbury); Kinlochewe, Ross (Grant); Arran 
(F.W.E.). 
O. albitibia sp. n. (Pl. IT. fig. 15). 
With the characters of O. nodulosa (Mcq.), but the male antennae 
a little longer, the joints slightly more swollen in the middle, the 
verticils somewhat longer; mesonotum ochreous-tinged at the sides 
in front; hind tibiae and tarsi (in the one perfect specimen) with 
the pubescence almost entirely pale, but that on the metatarsus 
not strikingly paler than that on the tip of the tibia. Hypopygium 
very similar to that of O. nodulosa (as figured by de Meijere), but 
the long yellow hair on the ninth tergite (sternite of de Meijere) 
is in a larger and broader patch; the bifid tenth tergite (or terminal 
portion of the ninth) is shorter, and the upper claspers (fig. 15) are 
very long, curved backwards (caudally) and end in long sharp points. 
Two males are before me, one (damaged) from Braemar, 
27 vii. 76 (Verrall), and one (the type) from Church Stretton, 
Salop, 24 vi. 1920 (F.W.E.). 
O. aciculata sp. n. (PI. II. fig. 14). 
Closely resembles O. uncinata Meij.; perhaps distinguishable by 
the colour of the pubescence on the hind leg, that on the hind tarsi 
being almost entirely whitish, not whitish on the metatarsus only ; 
