444 ENTOMOLOGICAL NEWS. [Dec., '15 



These experimental researches on the permeability of the 

 spiracles to air may afford an explanation of the results ob- 

 tained by East (1900, p. 212), who kept nymphs of rv- 

 thromma najas and of Agrion puella alive, out of water, for 

 one month and for thirty-three days, respectively. They had 

 no food during this period and yet the nymph of H. najas 

 moulted in the midst of it. 



CONCLUSION. 



From the various data which have been brought together 

 here, it seems reasonable to suppose, at least until much more 

 exact experiments show the limitations of each mode of respi- 

 ration for different stages and for different species of Zygop- 

 terous larvae, that the general body-surface, the caudal pro- 

 cesses, the rectal epithelium, certain spiracles and, in a few 

 species, lateral external abdominal tracheal gills, all contribute 

 to satisfying the needs of the organism for oxygen. A classi- 

 fication which regards the larvae or nymphs of any one group 

 as exclusively or predominantly Caudobranchiate is not justi- 

 fied by our present knowledge. The fact that the larvae of 

 Thainnat one ura spend much of their lives moistened by, but 

 not submerged in. water, tempts one to refer the relatively 

 small surface of their caudal appendages ("gills") to this 

 mode of life. The similarity of their rectal tracheation to 

 that of the larva of Hetaerina americana and the existence 

 of rectal respiration in the latter lead one to expect that a 

 similar condition will be demonstrated by observations on liv- 

 ing Thaumatoneura larvae. 



BIBLIOGRAPHY ON THE RESPIRATORY ORGANS AND 

 THE PHYSIOLOGY OF RESPIRATION OF ZYGOPTEROUS 



ODONATE LARVAE. 

 BABAK, E. 1912-13. Die Mechanik und Innervation der Atmung. 



Handb. 1'crg!. Physiol. herausg. von H. Wintcrstcin, Bd. I, 2te. Halfte, 



pp. 389-410, 421-34- 



BABAK, E. u. FOUSTKA, O. 1907. Untersuchungen iiber den Aus- 



losungsreiz der Atembewegungen bei Libellulidenlarven (und Arthro- 



poden uberhaupt). P finger's Archiv gcs. Physiol., cxix, pp. 530-548, 



i text fig., 2 taf. 



