AQUATIC INSECTS IN NEW YORK STATE 375 
treme base of the tibiae yellowish, with a single short spur on 
the fore tibiae, and a pair of longer ones on middle and hind 
tibiae [pl.38, fig.8]. Fore and middle tarsi slender, hind ones 
widened, all claws trifid [pl.388, fig.8, 17]. Wings hyaline or 
Slightly tinged; the anterior veins thickened, the remainder 
slender [pl.36, fig.7]. Knob of halteres orange yellow. The 
male genital organs are short though rather complex, consisting 
of a pair of outer sheaths, then a pair of elongate blunt pro- 
cesses, within which are two pairs of hooks; the outer, shorter 
pair are incurved and clawlike; the longer, inner pair are 
slender, with some outwardly projecting hooks. Length 3.5 to 
4mm. 7 
Female. Eyes with a small deep sinus on each side, just about 
the base of the antennae, above which the front is a little longer 
than wide, and a little wider above than below. Face a little 
wider than the narrow part of the front, the sides parallel, its 
surface. gently and evenly convex, clothed with white hairs; 
antennae tapering more than in the males, the first two joints 
yellowish. Basal joints of palpi stouter. Facets of eyes uni- 
formly small, the eyes much smaller and the posterior orbits 
conspicuous. Thorax lke the head, opaque gray pruinose. 
Metanotum with three slender, deep brown or black stripes, the 
lateral ones gently incurved back of the anterior knoblike dila- 
tion. Abdomen velvet-black, the second segment (or the part 
beneath the leaflike margins of the first) and the posterior 
'margins of three following segments (except at the center), 
opaque gray or grayish white; the remaining segments, and leaf- 
like sides of the first, lightly pruinose; venter gray; in some 
specimens with a small black or grayish triangular spot on cen- . 
ter of the dorsum of segments 3, 4 and 5. The legs grayish, in 
- gome specimens quite pale; the tips of some or all the tibiae 
usually, and the tarsi nearly always, black, except the bases of 
hind metatarsi and sometimes the middle also, which are yellow. 
The tibial spurs and hind metatarsi as with the male. Tarsal 
claws simple [pl.38, fig.20]. Wings as with the male. Knob 
of halteres yellowish white. Length 5 to 4mm. | 
I have compared this species with Hagen’s type, (larvae, pupae 
and adults) and find that they agree perfectly. The apparent 
discrepancy in comparing Hagen’s description’ with the one 
given above is due to the fact that Hagen described his from 
bottled material. His description agrees very well with al- 
coholic material of this very common Ithaca species. Hagen 
was in error in regard to the number of respiratory filaments of 
— 
1Bost. Soe. Nat. Hist. Proc. 20:305. 
