8 



in the pupa stage I do not think that they are so. I first intended in two exten- 

 sive chapters to give biological sketches of each of the forty ponds, and of the 

 neighbourhood where some of the more peculiar species are found; further to print 

 the large schemes of each of the forty ponds, carried on for almost four years; the 

 schemes show how each of the species appears and disappears in the course of the 

 year. Especially these schemes were extremely expensive to print, and I suppose 

 that their real scientific value is but slight; they may be regarded as rough draughts, 

 and will not be printed owing to the great expense. — With regard to the synonyms 

 I have only given the most necessary information; 1 refer to the work of Lang 

 (1920) and to others which I know are under preparation. 



As it will be understood from the foregoing pages, this work stands in the 

 greatest debt to Mr. Edwards of the British Museum ; I hereby express my most 

 cordial thanks for all the help he has furnished me with; further to Prof. Simon 

 Bengtson and, last but not least, to Mr. Kryger who with great skill and warm 

 interest has solved the tasks, I have given him. A few months before this work 

 was sent to press, Mr. Lang's valuable work, relating to the British mosquitoes, 

 appeared; more than any other it has shown that my paper, now published, issuing 

 from quite different stand-points, and worked out on other principles, is by no 

 means superfluous. Also the Caresbergfund I bring my heartiest thanks for two 

 sums, by means of which I was able to explore the southern islands, mainly with 

 regard to the Anophilines. For the study of the living larvae the excellent bino- 

 culary aquarium microscope, also presented to me by the Carlsbergfund, has been 

 of the greatest value. All the tables are drawn by myself and all figures of the same 

 kind are drawn with the same power and all with camera. 



Key to the tables: 1 head (Leitz Ob. 3 Oc. 1) 2 antenna (Leitz Ob. 3 Oc. 6) 3 

 mandible (Leitz Ob. 3 Oc. 6) 4 maxilla (Leitz Ob. 3 Oc. fi) 5 mentum (Leitz Ob. 6 

 Oc. 1) (i the last segments (Leitz Ob. 3 Oc. 1) 7 scales in comb (Zeiss horn. im. Oc. 6) 

 8 pecten (Zeiss Ob. B Oc. 6) 9 single thorns in pecten (Leitz (5 Oc. 6). 



The Freshwater Biological Laboratory. 



Hillerad. '%> 1920. 



