422 



NEUROPTERA 



extremity of the body out of the water and so obtain a supply 

 of air. 



Oustalet and Palme n state that at the last ecdysis the 

 lamellae, or the papillae, do not disappear, but remain quite 

 empty, and are consequently ftmctionless, while on the tracheal 

 trunks there are developed air vesicles to fit the creature for its 

 aerial career. Hagen says that in JSpitheca the whole structure 

 of the gills is shed at the final moult. 



The subject of the rectal branchiae of Libellula has been dis- 

 cussed and illustrated by 

 Chun, 1 who states that Ley- 

 dig has made known that in 

 Phryganea grandis a structure 

 is found connecting the rectal 

 branchiae of Libellulavfiih the 

 rectal glands of some other 

 Insects. We have not been 

 able to find a confirmation of 

 this in the writings of Leydig 

 or elsewhere. 



In the nymphs of the 

 Zygopterides the highly -de- 

 veloped rectal branchiae found 

 in the Aeschninae and Libel- 

 lulinae do not exist, and the 

 respiration seems to be of a 

 complex character. In one 

 division of the Zygopterides 

 - Calepteryginae rectal 

 gills of an imperfect character 

 are said by Hagen and others 

 to exist. 2 The nymphs of the Zygopterides are provided with three 

 mobile processes at the extremity of the body (Fig. 270); these serve 

 the purposes of locomotion. They are believed to possess also a 

 respiratory function, but this must be of an accessory nature, for 

 the nymphs live after the removal of the processes, and indeed 

 reproduce them ; the skin of these processes is harder than is 

 usual in Insect gills. In the nymph of Euphaea a genus of 

 Calepteryginae found in tropical Asia there are also external 

 1 Abh. Senclcenb. Ges. x. 1875, p. 13, pi. iii. 2 Zool. Am. iii. 1880, p. 160. 



FIG. 270. Calepteryx virgo, mature nymph, 

 Britain. 



