46 



town. It was shown that 0. caspius was often' to be found in cellars etc. till the 

 last part of November and even the beginning of December. In the last part of the 

 winter it seemed as if the material had everywhere died out; only C. pipiens and 

 T. annulata were left. 



Regarding it as almost certain that egglaying processes have taken place in 

 the last part of July and most probably also in September, there can be no doubt 

 upon the point that 0. caspius and most probably also 0. curriei, if this species 

 can be separated from 0. caspius, both have two broods, the one hatched in the 

 first half of June, the other in the last part of August. In summer and winter there 

 is a resting period which is passed as eggs. 



Having elucidated the life history of the Valby mosquito the question was, whether 

 0. caspius was really restricted only to the brackish water pools near Copenhagen. 

 This was of course very improbable. In the two years 1919 and 1920 Mr. KRYGER 

 and I explored different parts of the Danish coasts. It can now be stated that 

 it has been found near the coasts of Roskildefiord; on the southern coast of Lol- 

 land, on the coast of the straits of Guldborgsund, which separates Lolland from 

 Falster; along the eastern coast of Jutland, more especially in the deeper parts of the 

 fjords. Most probably it may be found everywhere in brackish water pools, along 

 the shores of Kattegat and the Baltic; I could not find it in the brackish water 

 pools along the North Sea. It has never been found away from the coast. It is al- 

 . ways accompanied by 0. curriei but in spring rarely by any other mosquito. In 

 autumn, at Guldborgsund and upon Amager and at Roskildefjord, I found it as- 

 sociated with 0. detritus, which also otherwise has often been found with it. 

 (England: EDWARDS, LANG). The localities are always the same: tidal brackish 

 water pools, which are often exposed to complete desiccation. According to the more 

 casual observations it seems as if two generations are typical for our country. At 

 Roskildefjord I have found the two generations in the last part of June and in the 

 last part of August; the last generation was found at Guldborgsund. 



Geographical distribution: Found in almost all European countries, Asia 

 and Northern Africa. With regard to the peculiar biology of the Saltmarsh mos- 

 quitoes I further refer to the papers of BUTTRICH (1913 p. 352), SCHMIDT (1913), 

 HEADLEE (1916 p. 339 and 1917 p. 211) and CHIDESTER (1917 p. 299). 



2. O. curriei (Coquillet). 



This species is in my opinion indistinguishable in the imago-stage from 0. cas- 

 pius. It especially represents variety 4 on pag. 40. As I however possess almost all 

 intermediate stages in the above-named four varieties, it is with the greatest hesitation 

 and upon the authority of Mr. EDWARDS that I maintain the species. It has hitherto 

 been regarded as species, differing from 0. caspius, partly because of the larva, partly 

 because of a different habitat. HOWARD, DYAR and KNAB firstly indicated (p. 637), that 

 in the larva of 0. curriei both pairs of dorsal head-hairs are multiple, and that the 

 lateral comb of the eighth segment has about twenty-five scales in an irregular patch, 



