438 ENTOMOLOGICAL NEWS. [Dec., '15 



based on an examination of the interior envelope of the rec- 

 tum in exuviae. Very recently Ris (1913, p. 95) has stated 

 that he is disposed to consider the "older statements of Dufour 

 and Hagen on the union in Calopteryx larvae of the zygop- 

 terous with a rudiment of the anisopterous organ as an error 

 of observation." 



The present writer has recently made some observations on 

 living larvae of Calopteryx maciilata from the neighborhood 

 of Philadelphia, as follows : 



A male larva (body-length, exclusive of ca tidal appendages 

 and of antennae, 17.5 mm., median caudal appendage 6 mm., 

 lateral caudal appendage 8.5 mm.) placed in a Syracuse watch 

 glass at 3.25 p. m. in barely enough water to cover the larva. 

 The larva remained very quiet and was watched under a Zeiss 

 binocular microscope with objectives a and oculars 2. Anal 

 expirations at the rate of 38 per minute were indicated by 

 movements of sediment attached to the hairs on the median 

 caudal gill. 



The same larva was turned on its back at 3.30 p. m., all the 

 other conditions remaining the same as before. The larva re- 

 mained very quiet ; 36 anal expirations per minute indicated 

 as before. Powdered carmine was sprinkled on the water and 

 floating on its surface showed very clearly the expulsions of 

 water from the anus at a rate of 33 per minute. The carmine 

 particles showed currents as indicated in the accompanying 

 diagram (Text-fig. 2). The expulsions from the anus were ac- 

 companied by alternate contractions and expansions of abdom- 

 inal segments 3-8, which were most marked near the lateral 

 edges of the segments at their articulation with the next fol- 

 lowing segment. Observations on the direction of movement 

 of carmine particles and particles of sediment in (not on the 

 surface of) the water made it seem likely that the water enter- 

 ed the rectum through an aperture (<?a) between the ventral 

 margins of the right and left subanal plates and the posterior 

 ventral margin of abdominal segment 10, and that it left the 

 rectum by an orifice (.va), less easily seen in 'ventral view, be- 

 tween the supra-anal plate and the dorsal margins of the right 



