. 
; 
{ 
culiciformis, De Geer. 385 
torm, with the supports of the blades from two to three times 
their thickness in length ; but towards the apex of the wing 
the lanceolate form disappears more and more, and on the 
anterior margin of the wing they become sete of the ordinary 
form. 'The second and fourth longitudinal nervures are bi- 
furcated; the fifth longitudinal nervure emits, a little before 
the transverse nervure, a nervure towards the margin of the 
wing, which, however, does not reach the latter, but runs for 
some space parallel to it. Both marginal cells are entire; 
the discoidal cell is wanting. 
The development, so far as Mochlony« culiciformis is con- 
cerned, is described by De Geer. The larve live in water, 
and travel in the same way as the larve of Corethra. They 
live by rapine, and when pressed by hunger devour each 
other. 
With regard to the generic characters of Corethra, the 
following points may be indicated in contradistinction to 
Mochlonyx :— 
Of the mouth-parts the cwltel/i (in the female) are smaller 
and attain only a fourth part of the length of the third joint 
of the palpi. 
The eyes are more strongly sinuated than in Mochlonyz. 
The external genitalia of the male are somewhat slighter, 
and the styles are destitute of the cultriform spine at their 
apex. The prehensile hooks are further much shorter, with a 
short inner lamella, and do not reach beyond the posterior 
margin of the last abdominal segment. 
The legs present the essential generic distinction from 
Mochlonyx ; but while in the latter genus they are exceed- 
ingly different according to the sexes, especially as regards 
the claw-joint and the claws, they are here pretty nearly alike 
in both sexes. In Corethra the proportion between the lengths 
of the tarsal joints is a pretty regular decrease from the first 
to the last joint, and the last joint, in both sexes, is normally 
constructed. The claws are rather long and slender, finely 
haired from the base to beyond the middle. The lateral pro- 
cesses are flat, broad, and cut at the edge into many teeth as 
fine as hairs. ‘The onychium is much shorter than in Moch- 
lonyx, and cleft at the apex into four long hair-like teeth. 
The wings are a little broader and more acute, and the 
fourth longitudinal nervure divides rather higher up; the 
side-nervure emitted by the fifth longitudinal nervure is algo 
much shorter and terminates a little before reaching the margin 
of the wing, but without following it. In the fringes the 
setee of the lower short series are comparatively shorter ; but in 
