SPÆR 
on water. The egg-shell of this: species presents no special structure; 
it resembles that of most other Culicidæ. 
In the same paper Dyar and Knab describe another egg also 
forwarded to them by Moore. The egg is furnished with a small 
neck from the upper edge of which four pairs of horns project 
upon very short stalks; these horns appear to consist of solid 
chitin and taper into a sharp point. Later on, Moore found the 
species which laid these eggs; it was described as a new species,” 
M. humeralis Dyar and Knab. These eggs are of interest, because 
they resemble the eggs of Nepa and Ranatra; as well known, 
these water-bugs pierce their eggs into half decaying plant material, 
and the crown of spines round the tip of the eggs are commonly 
regarded as a respiratory organ. Dyar and Knab also regarded 
the spines of the egg of Mansonia as in some way connected with 
the problem of air-supply. 
We must here finish our remarks relating to the biology of 
these very interesting mosquito-larvæ. As a matter of fact, their 
biology is still very incompletely known. From the material in 
hand we are unable to trace the ways of this peculiar genus 
enabling the larva to emancipate itself from the atmospherical air 
above the surface of the water and seek the air stored within the 
air-chambers of submersed water-plants. It seems as if the grade 
of adaptation is not exactly the same in the different species. The 
peculiar fact, that at least one species does not construct egg-boats 
but lime the eggs to the plants, and that the egg-shells of another 
Species are constructed similarly to those of animals the eggs of 
which are pierced into plant-tissues, let us presume, that further 
Studies will also let us know larvæ in which the modus of respir- 
ation as well as the shape of the sipho represent the "missing - 
link", transmissions to the normal facts in the common mosquito 
larvæ. Undoubtedly we must search in the tropics if we want to 
Solve these questions. It would be unreasonable to expect, that it 
Should be possible to find the solution of the problems in a little 
Pond in North Seeland far away from the center of the geograph- 
ical distribution of the genus. 
Finally I have to bring the Carlsbergfond my heartiest thanks 
for a dotation for which the figures have been reproduced. 
The Danish Freshwater Biological Laboratory, Hillerød, January 1918. 
