107 



Systematical and faunistic remarks. As my specimens have not pale 

 rings in the middle of the metatarsi, these being quite black, it is only with great 

 hesitation that I refer my specimens to this species. As how- 

 ever I have never seen the male, I suppose that provisionally 

 we had better refer them to the old well-known species. 



On an excursion in September 1914, to one of the 

 little ponds near Donse in the north-eastern part of See- 

 land, a locality well known to botanists and zoologists, I 

 was sitting in my boat near a sunlit, prominent point of 

 the shore. Some plants were laid upon a tray, half fdled 

 with water. While searching for larvae of Coleoplera my 

 attention was now and again attracted by some large 

 mosquito larvae which crept over the bottom in a ser- 

 pent-like manner, when the tray was shaken. It struck 

 me that it was really a peculiar season to find fullgrown Textfig.16. Tceniorhynchuspupa. 

 Ca/ex-larvae. I caught one of them and placed it in a Cephalothorax with the two 



r trumpets. 



high cylinder-jar. To my astonishment I saw that the 



animal was undoubtedly heavier than the water and that it sank slowly downwards 

 and settled itself horizontally on the bottom. Moreover I saw that the animal did 



not at all swim like a common Cz//e.r-larva, but always 

 swam horizontally; it was extremely sluggish and had 

 a milky-white colour, very different from the brown 

 colour characteristic of most of our Danish Culex- 

 larva?. I observed that the sipho was of a peculiar 

 structure, but on using a lens with high power I 

 immediately understood that I had made one of the 

 most remarkable discoveries made in our freshwaters 

 for a long time past. 



Some weeks before, I had received a separate copy 

 from Dyar and Knab (Entom. News 1910 p. 259) re- 

 lating to a peculiar mosquito larva, Mansonia pertar- 

 bans; the paper was cited in my work on Aquatic 

 Insects (1915), then just in press. The larva is re- 

 cognizable at a first glance on account of its very 

 characteristic sipho which has been converted into a 

 piercing organ by means of which the animal perfo- 

 rates living plant-tissues; the air in the air-spaces is 

 used for respiration. The mode of life of the larva is 

 therefore quite different from that of the other mos- 

 quito larvae; it does not swim, but must really be re- 

 garded almost as a sedentary animal, sitting with the sipho bored into'the plant-tissue, 

 near the bottom, often at a depth of one-third of a meter (Texttigs. 12, Tab. 16 fig. 10). 



14* 



Textfig. 17. Tceniorhynchus pupa. 



Apex of one of the trumpets; 



highly magnified. 



