Vol XX vi] ENTOMOLOGICAL NEWS. 435 



Studies on G>sta Rican Odonata. 



VII. The Waterfall-Dwellers: The Internal Organs of Thaum- 

 atoneura larva and the Respiration and Rectal Tracheation of Zy 

 gopterous Larvae in general 



(CoMisMd tnm |»(c W) 



Rv. pHii.fp p. Calvert, Ph.D., University of Pennsylvania, 



Philadelphia. 

 Our knowledge of the whole subject of the respiration of 

 Zypopterous larvae is still very indefinite, and it seems worth 

 while to tummarize it such as it is. 



Classification of the Tracheal Gills of Odonate Larvae. 



Dufour (1852). grouping all the Odonate larvae known to 

 him under the four genera, Aeshna, LibcUuia, Cahptcrix and 

 Agrion, gave as generic characters for the first three "Branch- 

 ics interieures ou rectales," and for the last "Branchics ex- 

 terieures ou caudales . . . et servant aussi de nage- 

 oires." He added "Comme on voit, la nature et la position des 

 branchies ^blissent entre le Calopterix et VAgrxon une dis- 

 tance anatomique enorme** (p. 72). Hagen (1853), recogniz- 

 ii ' milies, gave for Ubellulidrn, Gomphiden and Aesch- 



ww.. .. . .irnikiemcn," for Calo|Hcrygidcn "Darm und Schwanz- 



kiemen," for Agrionidcn "Schwanzkiemen" (pp. 261-9, 3")- 

 Rousseau ( 1909, pp. 2. 43. 45) has accepted the same distinc- 

 tions so far as "branchies" are concerned. 



Roster (1885, p. 259), on the other hand, grouped Agricn, 

 testes and CaJopteryx as Caudobranchiati, Anax, Libellula and 

 Aesckma as Rectobranchiati. although Dufour (1852, p. 83) 

 had employed the same words, in the form of French adjec- 

 tives, in the different sense implied by his classification quoted 

 above. Roster's terms were synonymous, as group names, 

 with the earlier Zygoptera and Anisoptera and were so recog- 

 nized by systematic writers.* 



Functions of the Three Caudal Appendages of Zygop- 



TEROUS Larvae. 



Reaumur (1742, p. 405), who regarded these appendages as 



•nageoires" (fins), and Roesel von Rosenhof (1749, pp. 4^ ^ 



~ili, g„ .Ic ScIys-U.iiKcliainps. .Ann. Soc. Ent. Rclg. xxxi, pp. 75. 



80, in a *"U$te dcs Odonatcs d'Europc en i887." 



