106 Mr. R. M‘Lachlan’s Monograph of the 
towards the apex. The pale apical fringes, paler legs, and the 
large upper penis-cover, &c., also distinguish it. 
6. Leptocerus cinereus, Curtis. 
(Pl. VI. fig. 3b, max. palp.; Pl. XII, figs. 16, 17, app.) 
Leptocerus cinereus, Curt. (*) Phil. Mag. p. 214, 11 (1834); 
L. aureus, Steph. (*) Ill. p. 197, 8 (1836), not of Pict. ; 
L. annulatus, Steph. (*) Ill. p. 197, 9 (1836); ZL. seminiger, 
Steph. (*) Ill. p. 199, 16 (1836); Mystacides bifasciatus, 
Kol. Gen. et Spec. Trichop. pt. 2, p. 253, 5, tab, 3, fig. 26 
(1859). 
Antenne black, annulated with white on the basal half; basal 
joint and head thickly clothed with cinereous hairs. Palpi 
fuscous. Mesothorax fuscous, with a few cinereous hairs in the 
middle. Anterior wings narrow, brownish-cinereous, with pale 
grey spots on the dorsal margin, and an indistinct pale grey fascia 
towards the apex, most conspicuous towards the costa and not 
reaching the inner margin; (these markings are scarcely visible in 
dry specimens, but are conspicuous during life, especially in the 
female); fringes cinereous, interrupted with grey at the termina- 
tions of the apical veins. Posterior wings smoky-grey; neuration 
dark fuscous, almost black. Legs silvery-grey, the anterior pair 
darker ; tarsi spotted with fuscous at the joints. Abdomen grey- 
ish-fuscous with pale lateral lines. In the male the divisions of 
the dorsal lobe are dark fuscous, subtriangular; app. sup. very 
long and thin, nearly straight and very hairy ; below these are 
two long and needle-shaped testaceous app. intermed. (or upper 
penis-covers ?) which appear to be united at the base, but divide 
into two curved points, the apices of which converge ; app. inf. 
proceeding from a large blackish basal piece, up-directed, elbowed 
in the middle, the apex acute and testaceous; the penis appears to 
be bent strongly downwards, the apex dilated into a knob. In the 
female there is also a bilobed superior plate, broader but some- 
what similar to that of the male; below these two lobes are two 
larger ones, whence proceed two short obtusely-rounded lateral 
valves. 
Expanse of fore-wings, ¢ 9—11 lines, 9 83—9 lines. 
A common species about slowly flowing rivers. Along the 
Thames it appears in the greatest abundance in summer and 
autumn. It flies in the evening just above the surface of the 
water, and if we proceed along the river in a boat at that time, 
the numbers appear so great, that as they diverge on either side 
