ON THE ANAL RESPIRATION OF THE COPEPODA. 83 



oxygen lines, which only appeared at very high tempera- 

 tures. The capillary portion of the tubes we used was 

 much shorter than that in the ordinary Pliicker's tubes, 

 and this accounts for the temperature of the incandescence 

 being higher than usual. As one of the lines is near 

 the unknown aurora line, its wave-length was determined 

 and found to be 5591, showing it to be decidedly less 

 refrangible than the aurora line. 



The experiment was repeated in four different tubes 

 and many times in each tube; but whether graphite or 

 diamond was employed, no line Avas seen which was not 

 also obtained in a tube of the same dimensions containing 

 carbonic oxide. 



XI. On the Anal Respiration of the Copepoda. 

 By Marcus M. Hartog, M.A., B.Sc, F.L.S. 



Read December i6, 1879. 



In a note on Cyclops read at the British Association I 

 pointed out that its respiration was exclusively anal. I 

 have now made out the same in Canthocamptus (fam. 

 Ilarpacticidse) and Diaptomus (fam. Calanidae). In all 

 three the mechanism is the same; at regular intervals, 

 after the backward sway of the intestine, the anal valves 

 open for an instant and then close, giving just time for 

 a slight indraught of water after the opening, a slight 

 expulsion at the close. The necessary pressure to confine 

 the animal seems to interfere somewhat with these move- 



g2 



