110 



we agree with regard to the morphology of the air-tube, the mode of affixion, and 

 the large airsacks in the thorax. 



With regard to the peculiar Tceniorhynchus pupa this is mainly known from 

 American authors I. B. SMITH (1908 p. 22) and GROSSBECK (1908 p. 473), further 

 HOWARD, DYAR and KNAB (1917 p. 519) have especially studied that of T. titil- 

 lans, THEOBALD (1903 p. 270) has figured that of T. uniformis. The pupa of the 

 European species has not hitherto been thoroughly studied. 



Additional biological remarks. With regard to the biology and anatomy 

 I refer to my above-named paper; some new observations may now be added and 

 compared w r ith others derived from authors from last year. 



In June 1918 my assistant mag. sci. L. PEDERSEN found the larva of Tcenio- 

 rhynchus Richardi in a sheltered little creek in Funkedam near Hillerod. The loca- 

 lity was often visited, but also here the larva was rare, and I did not venture to 

 disturb it too often. A more thorough examination was made on an area only a few 

 square yards large. This spot was covered with submerged plants of Sparganium 

 and Scirpus; the bottom round this was covered with Fontinalis and a few Potamo- 

 geton natans. Among the Sparganium I could get about twenty larvae in one single 

 catch, outside it only one or two. Taking the plants out with my hand I more 

 than once got plants, on the roots of which I found the larvae fastened. These 

 plants were always Sparganium. Most of the larvae were fullgrown, but curiously 

 enough I got four minute larvae, of not more than three to four mm. With the 

 new living material in my laboratory I mainly tried to study the pupa and its life 

 conditions. 



In accordance with the above-given description of the pupa it may now be 

 maintained that the most characteristic features in the anatomy of the hitherto 

 known T&niorhynchus-pupaz are that the trumpets do not diverge but converge, and 

 that the trumpets are provided with a long, strong chitinized hook for insertion 

 into the roots of the water plants. The two hooks meet each other, so that the two 

 trumpets form a half-circle over the cephalothorax. Another remarkable structure is 

 that the stellate hair tufts on the hinder part of the first abdominal segment are 

 wanting. The paddles are cleft at apex. 



From the structure of the trumpets we must suppose that the pupae like the 

 larvae are fastened to the plants and for their respiration use the air in the inter- 

 cellular spaces. As far as I know, no one has hitherto seen the pupa sitting with 

 the trumpets pierced into the plant tissues. Further if it is right that the pupa, 

 too, is attached to plants, the question arises how. it is possible that the pupa can 

 pierce the siphoes into the tissues. Finally we do not know if the pupa, when the 

 last metamorphosis is going to take place, really leaves the plant and, like other 

 mosquito pupae, metamorphoses on the surface or finishes its metamorphosis fasten- 

 ed to the plant roots. 



For two consecutive years (June, 1918 and 1919) I had about twenty full- 

 grown larvae of T. Richardi in my aquaria; during both years five or six specimens 



