298 
they are very long and forward directed. All these larvæ… have 
well developed eyes. 
With regard to the second group (Mansonia) we might think, 
that the hair-cover had been highly impressed by the sedentary 
life so strongly different from the free-swimming habits of the larvæ 
belonging to group 1. This, however, does not seem to be the 
case. It must be remembered, that in both groups the hair-cover 
is particularly used as a sensitive organ. The sedentary life and 
the incapability of escaping from a danger only involves some richer 
development of the whole hairy system and another direction of 
some of the bristles; special attention might be paid to the brist- 
les of the antennæ. Very peculiar kinds of hairs are the crooked 
bristles above the sipho, being the most important climbing appa- 
ratus of the larva. 
In opposition to the above-mentioned groups the pelagic group 
(Corethra, Mochlonyx) is almost whithout bristles. It is a well- 
known fact, that the plancton organisms are very often provided 
with complexes of long bristles which increase the cross-section 
resistance and, therefore, diminish the speed of falling through the 
water. The possibility of pelagic life of the Culicid-larvæ is almost 
wholly due to the hydrostatic apparatus; the combination of a hy- 
drostatic apparatus with long bristles, frequently . found in the 
plancton organisms to increase the cross-section resistance, is un- 
known in the case of the pelagic Culicid-larvæ, where the bundles 
of bristles have all been reduced. The body of water, which these 
larvæ demand according to the development of their sense of touch, 
is probably much smaller than that required by the other Culicid- 
larvæ; hyaline as are these pelagic larvæ, they are also much 
better protected against enemies; and the eyes being higher devel- 
oped than in any other Culicid-larva, the sight is probably of great 
importance. 
The fourth group, which possesses a sipho, but seldom rises 
to the surface, mainly consists of tropical species. Still it must 
be remembered that the mode of life under the ice of the hibern- 
ating larvæ of the temperate zones resembles, as far as their 
respiration is concerned, very much the mode of life of the trop” 
ical larvæ; they respire the dissolved gases through the skin and 
especially through the gills. H. D. K. state, that the tropical lar- 
væ lie on their back on the bottom of the water pools; many of 
