106 



Textfig. 14. Tceniorhynchus pupa, frontally. 



parts a very remarkable, highly specialised structure; in the part nearest to the 

 cephalothorax the structure resembles that of a trachea, being striped transversely; 

 where the tube attenuates, the transversal stripes cease and are succeeded by a more 



homogeneous structure with a very 

 fine irregular rhomboidal stripening, 

 resembling that of a common pupa 

 tube. A little before the spot where 

 the tube attenuates, passing into the 

 accuminated part, there is a weak 

 point, where the chitin is thin and 

 where the apical part breaks off very 

 easily. At the same spot a chitinous 

 ring runs round the tube, on the 

 inner side leaving a cleft open. Out- 

 side this ring the tube acuminates; 

 the inner half has almost the same 

 structure as that on the other side 

 of the ring, but the outer part is 

 formed quite differently. It has a 

 broad fringe of long hairy excrescences and the utmost part, which is commonly 

 corkscrew-shaped, and lying in another plane, has a hyaline transversally striped 

 membrane on each side, which has inconspicuous saw- 

 teeth along the edges. It is this extreme part which must 

 be used as a piercing organ. The tracheal tube, which 

 runs from the apical opening to the above-named chiti- 

 nous ring, has a rather narrow lumen, being only one- 

 third broader than the tube in this part; immediately 

 behind the ring it expands to almost the whole width 

 of the tube, but tapers again and now runs as a narrow 

 tube through the whole air-tube. 



The tubes, which in the case of all other mosquito 

 pupae are directed outward and divergent, are convergent 

 in the Tceniorhynchus pupae (Fig. 16); the acuminated parts 

 are laid against each other when pierced into the stem ; 

 it looks as if the two tubes only made one single hole 

 when piercing; perhaps it is not quite improbable that 

 the two acuminating parts act along each other when 

 piercing and in this way saw a hole in the plant-tissue. 

 At first I had the impression, that each tube is hollow 



only on its inner side, the two half pipes forming a common conduit when laid 

 against each other; without section it is difficult to decide this question, but I sup- 

 pose that the description, first given, is correct. 



Textfig. 15. Tceniorhynehus- 

 pupa, laterally. 



