244 culicida:. 



small. Wings narrow, elongated, lanceolate, incumbent, as long as the 

 abdomen; veins fringed with scales; mediastinal ^ein ending beyond 

 two-thirds of the length of the wing ; subcostal ending at a little in 

 front of the tip ; radial emerging from the subcostal at before half the 

 length of the wing, forked beyond half its length, its hind fork ending 

 at the tip of the wing ; cubital proceeding from the prsebrachial trans- 

 verse veinlet ; subapical forked towards its tip ; prsebrachial, subanal, 

 and anal complete ;' subaxillary not reaching the border. Areolets 

 fourteen, — the subcostal, the mediastinal, two radial, the cubital, two 

 subapical, the prsebrachial, the pobrachial, two externo-medial, the anal, 

 the axillary, and the subaxillary. Posterior margin much excavated, 

 and forming an acute angle at the base. Halteres rather small. Ab- 

 domen with eight segments, rather narrow, about twice the length of 

 the thorax. Legs long, slender, unarmed, nearly bare ; coxte short ; 

 tibiae minutely spinulose ; tarsi very long, especially the hind pair ; 

 ungues small. Male. Palpi a little longer than the proboscis. Anten- 

 nse verticiUate-plumose. Fern. Palpi very short. Antennae verticillate- 

 pilose ; hairs short. Eggs elongated, oval, with a small and narrow 

 knot at the top, deposited side by side in small masses. Larva aquatic. 

 Head distinct, rounded, with two inarticulate antennae and some cili- 

 ated appendages. Thorax furnished with bundles of hairs. Abdomen 

 long, nearly cylindrical, much narrower than the thorax, with ten seg- 

 ments ; on the eighth a long respiratory organ, which is radiated at the 

 tip ; the tenth terminated by setae, and by five slender conical plates. 

 Pupa active, much curved, swimming by means of the tail and of two 

 terminal natatorial organs ; its organs of respiration consisting of two 

 tubular horns on the thorax. Abdomen terminated by two slender 

 oval plates. 



" The pupa usually remains suspended with the posterior end of 

 the body turned downwards ; but when the period for its change is 

 arrived^ it stretches it out upon the surface above which its thorax 

 is elevated. Scarcely has it been a moineut in this position than, 

 swelling out the interior and anterior parts of the thoi'ax, it causes 

 it to split between the two respiratory horns. Through tliis open- 

 ing the anterior part of the gnat then emerges. As soon as the 

 head and trunk are disengaged, it proceeds with its labour, and 

 gets out more and more, elevating itself by means of its abdo- 

 minal segments. Numbers now perish, their boats being upset 

 by the wind ; but the gnat that escapes, having fixed itself thus 

 perpendicularly, draws first its two anterior legs out of tlieii- case 

 and moves them forward, and next the middle pair ; then inclining 

 itself towards the water, it rests its legs upon it. As soon as it 

 is thus upon the water, it is in safety ; its wings unfold themselves 

 and are dried, and it flies away. The lancets are finer than a hair, 

 very sharp, and barbed occasionally on one side. It is furnished 



