102 Mr. R. M‘Lachlan’s Monograph of the 
male, though at the same time these are difficult to discriminate. 
I find in the app. sup. the most easily seizable characters. The 
genus is here restricted to those species presenting the sexual 
differences in the neuration noticed in the generic description; a 
reference to the outline figures of the neuration in this and the 
succeeding genera will convey a better idea than could be expressed 
by words. 
The perfect insects are diurnal or crepuscular in their habits ; 
some species dancing over the surface of the water by swarms in 
the bright sunshine. Where a species occurs, it is usually seen 
in great abundance. 
1. Leptocerus nervosus, Fabricius. (PI. VI. fig. 3, neuration.) 
Phryganea nervosa, Fab. Ent. Syst. Suppl. p. 201, 16, 17 
(1798); Coquebert, Icon. Ins. Fab. 14, t. 3, fig. 1; Ceraclea 
nervosa, Steph. «*) Ill. p. 194, 1; Kol. Gen. et Spec. Tri- 
chop. pt. 2, p. 242, 2, pl. 4, fig. 453; Leptocerus nervosus, 
Hag. (*) Ent. Ann. 1860, p. 68, 57; Phryganea barbata, 
Zett. Ins. Lapp. col. 1071, 47 (1840); Mystacida venosa, 
Ramb. Hist. Nat. Névrop. p. 508, 1 (1842); Mystacides 
venusus, Brauer, Neurop. Aust. p. 41, 5. 
Antenne blackish, beneath annulated with white to beyond the 
middle, basal joint deep black. Head and palpi deep black, the 
former sometimes with a few greyish hairs. Mesothorax dcep 
coal-black. Anterior wings yellowish-cinereous, with the veins 
deep fuscous and very strongly marked ; a somewhat paler yel- 
lowish anal spot. Posterior wings smoky, with the veins scarcely 
darker. Legs fuscescent, the tibize and tarsi somewhat paler ; the 
thighs with short greyish hairs. Abdomen black. In the male 
there is a short triangular plate projecting from the middle of the 
upper margin of the last segment; app. sup. broad and short, 
the apices very obtuse and directed inwards ; app. intermed. two 
fine needle-shaped points; app. inf. rather small, directed up- 
wards and apparently with a small apical joint; penis short, the 
sheaths strongly incurved, with the tips thickened. 
Expanse of fore-wings 12—14 lines. 
Not an uncommon species by rivers in various parts of the 
country. Near London it is found on the Thames about Kew, 
&e., and also on the Lea. It has been reported from Killarney, 
Ireland. Occurs at the end of May and in June, and flies very 
rapidly over the surface of the water in the bright sunshine in 
calm weather, It is easily recognizable, having a somewhat dif- 
