468 
THE STUD V OF INSECTS. 
remembered, however, that these flics are long-legged in 
comparison with the allied families, and not in comparison 
with crane-flies and midges. 
The members of this family are easily distinguished as 
such by the peculiar venation of the wings, the most char¬ 
acteristic features of which are the following (Fig. 571): 
cells V and 1st V a are not separated by a vein, the basal 
part of vein V 3 being undeveloped; veins III 3+3 and III 4+6 
separate near the base of the wing, and the two veins form 
hi. 
Fig. 571.—Wingf of Psilophm ciltatus. 
at the point of separation a more or less knot-shaped swell- 
ing; the cross-vein III—V is at or close by this swelling, so 
that cell III is very short. A somewhat similar venation 
occurs in some of the Muscidas; but there the knot-shaped 
swelling on vein III is often wanting, and the cross-vein 
III-V is usually more remote from the base of the wing; 
and too the flies belonging to the Muscidas possess the 
suture above the antennae characteristic of the suborder Cy- 
clorrhapha. 
The members of this family have three ocelli; the an¬ 
tennae are three-jointed ; the second segment of the antenna 
is sometimes rudimentary; and the third segment bears a 
two-jointed arista. 
The adults are predaceous and hunt for smaller flies and 
