440 ENTOMOLOGICAL NEWS. [Dec., '15 



both entrance and exit of the water into and from the rectum 

 seemed to be by the aperture ca between the ventral margins 

 of the subanal plates and the hind ventral margin of abdominal 

 segment 10. 



In both larvae the expulsions were much more evident than 

 the inhalations, the latter causing very much less movement of 

 suspended or floating particles. From time to time, for inter- 

 vals of one minute or longer, both inhalations and exhalations 

 ceased. 



In a transparent living larva of Hetaerina americana (di- 

 mensions corresponding to those of Caloptery.v larva quoted : 

 8.5, 3, 4 mm.), examined under a Zeiss compound microscope, 

 objective A, ocular 2, the rectal tracheal supply was clearly 

 seen to be very similar to that figured for Thaumatoneura 

 (PI. XVI) in the present paper. Rhythmic pulsations in the 

 rectum were distinctly visible at a rate of 45-53 "sets" per 

 minute, each "set" consisting of 3-4 successive contractions of 

 the rectal wall, followed by a longer pause of varying dura- 

 tion. Currents of water corresponding to the rectal pulsa- 

 tions were demonstrated by the use of carmine particles as de- 

 scribed for Caloptery.v. Water was expelled caudad from the 

 vicinity of the anus 45 times per minute jerkwise, each jerk 

 apparently synchronous with the pause following each "set" 

 of rectal contractions. The ileum moved rhythmically, ce- 

 phalad from the sixth to the fifth abdominal segment while the 

 rectum was contracting, and caudad into the sixth segment 

 again synchronously with the pause following each "set" of 

 rectal contractions. 



In the larva of Cora, the condition of the material did not 

 permit of an exact statement as to the existence of rectal tra- 

 cheal gills, but it was noted that the rectal walls appeared much 

 less richly tracheated than those of the stomach. (Calvert, 

 191 1 a, p. 55; cf. pi. ii, ff. 17, 19)- 



RECTAL RESPIRATION. AGRIONINAE. 



Schmidt- Schwedt (1891, p. 104) stated that larvae of 

 Agrion and of Lestes do not possess respiratory movements 

 through the anus and Tiimpel (1908, p. 66) asserted that all 



