Vol. XXvi] ENTOMOLOGICAL NEWS. 44! 



other Agrionidae [than Caluf>lcry.v] lack gut-gills (Darm- 

 kiemen), but breathe only by the caudal gills. On the other 

 hand, Dewitz (1890, p. 504) saw in transparent Agrionid 

 nymphs under the microscope a stream of water taken into 

 and expelled from the rectum. Tillyard (1906, p. 415) re- 

 corded the larva of Lestcs Icda as suddenly projecting "itself 

 forward by expelling the water from its body anally," which 

 certainly suggests two functions, locomotion and respiration, 

 associated in the rectum as they are in Anisopterous larvae. 

 Babak and Foustka (1907, p. 538), studying the respiratory 

 movements of the abdomen of Odonate larvae by means of the 

 graphic method, obtained from "a small species of the 

 Agrionid group'' results entirely similar to those from experi- 

 ments on two larger Libellulid species. Their figures show the 

 differences in the height and frequency of the respiration 

 curves, due to the absence or presence in varying quantities of 

 oxygen in the water in which the larva was placed. Balfour- 

 Browne (1909, p. 279) working on larvae of Agrion pulchcl- 

 linn, Ischnnra clcgans, Pyrrhosoma nymphula and Ervtlirom- 

 ma najas, after citing Dewitz's observation quoted above, says 

 of the stream of water passing in and out through the anus : 



from my observation it is a very weak one, nor is there any special 

 apparatus surrounding the anus in this group to prevent ingress of 

 foreign particles such as is found in the Anisopterids. If rectal res- 

 piration exists at all, it seems to me that it must be very slight and of 

 but little importance, as I could not observe any increased number 

 of contractions of the rectum in specimens of Agrion which had been 

 deprived of their lamellae. In the absence of the lamellae, I think 

 the whole of the respiration must be carried on through the skin. 



It is remarkable that, as in the case of Caloptcr\.v, no ana- 

 tomical-histological studies have been made on the rectum of 

 Agrionine larvae of Kuropc or of North America. All that 

 exists hitherto appears to be the brief account of the rectum of 

 the Costa Rican Mecistogaster modcstus (Calvert, 191 ib, pp. 

 452-3, pi. xvii, ff. 7, 10). The first part of the present paper 

 gives a fuller description, of the rectal tracheal distribution at 

 least, than any that has yet appeared. 



( )bservation and experiment with carmine particles on living 



