170 
The POST-EMBRYONIC DEVELOPMENT of 
» CNA (CULES. 
By C. Hrerpert Hunrst, Pu.D., 
LECTURER ON ZOOLOGY IN VICTORIA UNIVERSITY. 
With Plate V. 
[Read January 10th, 1890.] 
THE eggs of the gnat are laid side by side, and cemented 
together forming a raft, and as the eges are thicker below 
than above this raft 1s convex below and concave above. 
It is to be found floating on the surface of still water, 
especially in early spring. Hach egg has at its lower end, 
7.e., under water, an aperture closed by a lid which opens 
to allow the escape of the larva. The larva is an active 
free-swimming worm-like creature with powerful jaws, by 
means of which it feeds chiefly upon minute alez and on 
decaying leaves. ‘The head has on each side a small com- 
pound eye, and behind this a simple eye. A very short 
thin neck attaches the head movably to the broad thorax, 
the latter consisting of three ill-defined segments. The 
abdomen is long and comparatively slender, and consists 
of nine obvious segments, the last one being bent down- 
wards at an angle and bearing a median row of setze below 
which serves as a propeller. At its extremity is the anus, 
surrounded by four small leaf-lke gills. From the dorsal 
surface of the abdomen, at the hinder end of its eighth seg- 
ment, a conspicuous respiratory siphon projects upwards 
and backwards. ‘This is about equal in length to three 
seements of the abdomen, and the aperture at its end is 
provided with a valvular apparatus, by means of which it 
