98 



basalen sehr kleinen ohne vermittelnde Bindeglieder sehr grosze stehen. Alle haben 

 kleine Zahnchen; meist sind 4 kleine und 9 12 grosse Dornen vorhanden. Das 

 Haarbuschel des Atemrohres steht etwa in seiner Mitte. Am 8 Segment befinden sich 

 etwa 25 in zwei Reihen stehende lange lanzetformige in einer Spitze auslaufende 

 Striegelborsten". There are some discrepancies between these two descriptions. Eckstein 

 says that the hair-tuft on the sipho "steht etwa in seiner Mitte"; this is in accor- 

 dance with my description, but his own figure (Fig. 10) shows it at the base. Further 

 his statement: "dasz die Dornen nicht allmahlich an Grosse zunehmen, sondern 

 dasz neben den basalen sehr kleinen ohne vermittelnde Bindeglieder sehr grosse 

 stehen" is not in accordance with those of my Finlaya geniculata larva. Further my 

 larvae have in the comb only 12 scales arranged in one series. 



The mosquito which ECKSTEIN has described as 0. lateralis (Meigen) has, as 

 far as I can see, not hitherto been found in Denmark. The descriptions of the fe- 

 male and more especially of the larva are so insufficient, that it will be very diffi- 

 cult to determine them; in the description of the male genitalia he has pointed out 

 some characters, by means of which it seems that his 0. lateralis (Meigen) can real- 

 ly be separated from his 0. ornata (Meigen) (1920 p. 237). Most probably he is 

 therefore right, when he says (1918 p. 67) that: "lateralis ist eine Art fur sich, und 

 ebenso ornata und nemorosa". 



Biology. More than twenty years ago, when on an excursion to Jsegers- 

 pris, near the fjord of Roskilde, I found some mosquito larvae in a little hole of an 

 old oak; I supposed that the locality for these larvae was rather peculiar, the quan- 

 tity of water not being V* Ltr., black, brown and of an extremely nasty odour. Yet 

 I did not then thoroughly study the larva. Later on, when I read the work of 

 HOWARD, DYAR and KNAB, with the description of all the remarkable mosquito 

 larvae found in tree-holes, in the small volumina of water, among the leaves of 

 Bromeliaceae and other tropical plants, I remembered my observation of more than 

 twenty years ago. Having mentioned it to Dr. TH. MORTENSEN, he told me that he, 

 too, had found mosquito larvae in the holes of old trees in North Seeland. Dr. MOR- 

 TENSEN, w r ho at that time was my guest at the Freshwater Biological Laboratory 

 at Tjustruplake, explored the forest near the laboratory with me. In the course of 

 July we then found about thirty holes with mosquito larvae. On the meadow be- 

 fore the laboratory more than hundreds of plants of Angelica siluestris were grow- 

 ing. As this plant is provided with the greatest sheaths found in our flora, and more 

 than any other Danish plant is able to hold the rainwater in the sheaths for about 

 a week, I supposed that mosquito larvae might also be found here. The plants 

 were regularly observed; in the collections of water were found great quantities of 

 Infusoria and some Rotifers, but never mosquito larvae. It must be supposed that 

 our flora of herbaceous plants is unable to retain rainwater long enough for mos- 

 quito larvae to live in. 



The tree-holes are mostly to be found near the ground where the roots branch 

 off from the trunks, but I have also found them some meters from the ground, 



