INTESTINAL RESPIRATION IN ANNELIDS. 799 



Leptonereis vaillanti. 



So far as 1 have observed, ascending ciliary movement does not occur in this 

 species. 



In one specimen the anus was seen to open rhythmically at short intervals. Follow- 

 ing on each closure of the anus, after a very slight pause, an antiperistaltic wave began 

 at the anus and progressed up the intestine. The series ceased after a short time ; the 

 animal was under compression during the examination, in a small quantity of water. 



In another specimen, only irregular contractions of the posterior part of the intestine 

 were observed. In a third, nothing was seen. 



EUNICID^. 



Ophryotrocha puerilis. 



No ascending ciliary current was visible in the intestine. In one specimen very 

 large cilia were seen to be in violent motion around the anus, towards which their 

 action was directed. 



Antiperistaltic contractions were seen to take place regularly in about the posterior 

 third of the body ; starting at the anus, they occurred every few seconds, passing 

 slowly forwards through eight or nine segments. The waves were of considerable 

 amplitude, the lumen of the canal being narrowed by the contraction to about one-third 

 its usual width. The contractions did not seem to occur when the animal was com- 

 pletely quiescent, but appeared to be started by any slight movements. 



No connection was noted between intestinal and vascular contractions ; indeed, 

 contractions of the dorsal vessel were not observed. 



Hyalinoecia tuhicola. 



Neither phenomenon was observed ; this, however, is not conclusive, since the 

 specimens had to be chloretoned into quiescence before an examination could be under- 

 taken. Still the animals did not give one the idea that anything of the kind was to 

 be expected. 



Aricitd^. 



Examples of this family, probably belonging to the genus Scoloplos, were examined 

 at Millport. Reversed ciliary action was not observed. 



Antiperistalsis was present in all the specimens examined. In the three specimens 

 observed it was most marked in, or even confined to, the middle segments of the body. 



The vascular contractions, in each of the two cases where they were observed, were 

 independent of the antiperistalsis. Thus in the first specimen, where both series of 

 contractions were very well marked, the vascular series was about twice as frequent as 

 the intestinal, and the passage of the wave along the dorsal vessel was more rapid than 

 that of the antiperistaltic contraction along the gut. 



TRANS. HOY. SOC. EDI.NT., VOL. XLIX. PART IIL (NO. 14). 109 



