11 



often seen the whole wheel suddenly thrown inwards or vice versa. The part of 

 the antenna from tuft to apex is almost always narrower .than that from tuft to 

 base; generally it is stiff, but in Tceniorhynchus it is modified into a very long, 

 extremely flexible flagellum, bearing a single bristle near the tuft, but ending 

 without any hairs at the apex. - The outer part of the antenna is almost always 

 (except F. geniculatd) of a much darker colour than the inner part. In C. morsi- 

 tans the inner part is of an elegant ivory-white shining colour, strongly contrasting 

 with the almost black outer part. At the apex the antenna carries a different number 

 of shorter or longer hairs, two of which are as a rule inserted a little from the apex, 

 the others at the apex itself; the latter further carries one or two digit- shaped soft 

 organs, undoubtedly of sensory function. 



When we remember that all our Culicin larvae are almost of the same size, 

 and only a few of them half as long as the largest, further, that the larva of F. 

 geniculata, almost of the same size as C. morsitans, has antennae which are only 

 about one-forth of the length of those of C. morsitans, it is evident that these organs 

 must play a very conspicuous role in the economy of the larva. As far as I can 

 see, they are commonly but slightly developed in those species which live in 

 extremely small water volumina (tree-holes, water reservoirs of plants etc.); they 

 are also small in those species which mainly find their food at the bottom of the 

 ponds or upon plants; with regard to .the large, beautiful, many-rayed tufts, which 

 occur in those species that find their food in the water layers, where they produce 

 a circulation in the water by means of the fan-shaped lateral hairtufts of the 

 labrum, I have got the impression, that these large wheels bound a little water area, 

 in which the water currents produced by the labrum come in; the large wheels act 

 as filters, preventing too large particles from entering the area immediately before 

 the mouth parts. I assume this, because I have seen the wheels, when too large a 

 particle has struck against them, turn suddenly round and jerk away the particles. It 

 may be added that the antennae, especially in the lower part, are spinose; antennae 

 without any spinosity we only find in F. geniculata. 



The Thorax, consisting of three fused body segments, is always broad and 

 flat; the integument is membraneous, often furnished with two deep, longitudinal 

 furrows. Along the anterior and lateral margin long hairs, single or in tufts, are in- 

 serted. The arrangement of the hairs, single or in tufts, of the anterior margin, is of 

 value as a means of classification. In the description of the larvae I have used this 

 character and by means of figures given the hairs their number and position. The 

 hair formula of C. morsitans 231124421132 is to be understood in the following way: 

 In the median line two hairtufts, consisting of four hairs; laterally two double; they 

 are followed by two single hairs; then follows a tuft with three hairs, and at the 

 extreme end a tuft with two hairs; twelve hairs or hair- tufts on the frontal margin may 

 probably be the original number, but now and then one or other of these tufts are 

 suppressed. The number is almost always largest in the median tuft, commonly three 

 or four; then follows almost always a series of three or four single or double hairs, 



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