740 PROFESSOR J. STEPHENSON ON 



Chietogaster with which I am acquainted, C. punjahensis (45) and C. orientalis 

 (described at first (46) under the name C. pellucidus, which, however, was preoccupied). 

 Though cilia may be seen working in the stomach and intestine of C. punjahensis, 

 their motion is by no means so obvious as in other Naididse, and the direction is either 

 antero-posterior or indefinite. 



TUBIFICID^. 



Limnodrilus socialis Stephenson. 



This worm was first described by me from specimens found near Lahore (51); 

 I have since received examples from Calcutta and Ceylon. 



In these animals antiperistalsis is not invariably to be seen, and at the coldest time 

 of the year, in January, with the temperature of the laboratory about 52° F., the 

 phenomenon was frequently absent ; the worms at this period were very sluggish, and, 

 as will be mentioned, often showed no ciliary motion in the intestine. 



The antiperistaltic movements, when present, are more limited in extent than 

 amongst the Naididse ; the most posterior portion of the gut may exhibit them, or they 

 may be confined to a length of intestine in the middle of the body. The contractions 

 progress slowly ; thus in one case, in an animal of about sixty-five segments, where 

 the antiperistalsis was occurring between the fortieth and twenty-first segments, each 

 wave took about seven seconds to traverse one segment ; contractions took place at 

 the rate of eight in forty seconds, or twelve per minute ; so that each segment of 

 intestine often exhibited two distinct contractions, one in its anterior and one in its 

 posterior part. The constrictions in all cases affect the whole circumference of the gut, 

 i.e. are ring-like, and not confined to one side of the intestinal wall. The amplitude 

 of the movements, or the actual amount of narrowing of the lumen, is not very great, 

 but the force may be sutficient to move the fsecal masses in an anterior direction 

 through several segments. 



Ascending ciliary action is also not constant ; especially it seems to fail at the 

 coldest season of the year. It occurs, when present, in the posterior portion of the 

 gut, and may extend for a considerable distance, or be limited to a portion of the tube 

 immediately in front of the anus. It may be violent, and easily visible with the low 

 power of the microscope ; it may even take place during a period when the anus is 

 closed, though, on the other hand, it may suddenly cease on the closure of the anus. 



There is no necessary relation between the antiperistalsis and the ascending ciliary 

 action ; they may both occur at the same time, or either may be present without 

 the other. 



Clitellio arenarius (Miill.). 



Reversed ciliary action is usually, but not invariably, to be observed in examples 

 of this species. It may be absent in specimens in which the anus is closed ; but, on 



