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TEXT-BOOK OF ENTOMOLOGY 



FIG. 483. Larva of a mosq \iito (Culex rtemornsm~} of 

 middle age, seen from above, the trachea! system omitted : 

 at, antennae; <tl>, their middle joint ; ey, elastic artionkir 

 membrane ; afm, antenna! muscle ; atn, antennal nerve ; 



ganglion cell ; th, tactile hair of the siphon valve. 



sternal arches of the 

 abdomen than by the 

 contractions of the rec- 

 tum, since the walls of 

 this organ are less mus- 

 cular than is supposed. 



The nymph of Calop- 

 teryx (and probably of all 

 the group Calopteryginse) 

 possesses rectal gills be- 

 sides external caudal tra- 

 cheal gills. There are 

 three double rectal longi- 

 tudinal folds or ridges, 

 interpenetrated by tracheal 

 twigs. (Dufour, denied by 

 Poletaiew, but confirmed 

 by Hagen.) 



Dewitz claims that the 

 caudal gills of the Agrio- 

 nidse are not their sole 

 means of respiration, since 

 he cut off the caudal tra- 

 cheal gills of an Agrionid 

 nymph, which continued 

 to live for a week. Hence 

 he thinks that there may be 

 a rectal respiration, since 

 under the microscope he 

 saw a stream of water pass 

 in and out of the end of the 

 intestine. 



Dewitz' experiments 

 prove that in young 

 Ephemerids there may be 

 besides branchial, both rec- 

 tal and skin respiration. 

 He saw under the micro- 

 scope the anus for a while 

 opened and then closed, 

 causing the rectum to 

 move ; powdered carmine 

 mixed with water was 

 drawn into and then ex- 

 pelled from the rectum. 

 There was, however, no 

 enlargement and contrac- 

 tion of the abdomen as in 

 the rectal respiration of 

 JEschna. (Zool. Anz. 1890, 

 p. 500.) 



