1903.] OLIGOCII^TA FKOM NEW ZEALAND. 229 



contractions of internal mnscles, but the margins were not promi- 

 nent nor specially glandular. 



Certain " tuhercula pubertatis " are present in the mature 

 worms, in the form of one or more median, oval, glandular pads, 

 with a definite, rather raised mai-gin and a central depression. 

 All my specimens present one such tubercle in segment xvii. ; 

 it is prechastal, but not intersegmental in position. In one case 

 (a) this alone is present. In other individuals a postchsetally- 

 situated tubercle also occurs in one or more of the segments 

 following the male pores, viz. in {h) it is on segment xix., in (c) 

 on xxii., in [d) on xix. and xx. Thus the maximum number, so 

 far as my material enables me to ascertain, is three median 

 tubercles. 



The ovidtLcal pores appear as small white spots just in front of 

 chseta a on each side of segment xiv., and this is confirmed by the 

 study of sections. 



The spermathecal pores are four pairs, in line with chseta «, at 

 the anterior margin of segments vi., vii., viii., and ix. respectively. 



The nephridiopores are in line with chfeta h. 



Tlie dcyrsal pores commence in the third (or j^erhaps the second) 

 segment. 



Internal Anatomy. 



The septa forming the hinder walls of segments viii., ix., x., xi. 

 are a good deal thicker than their immediate neighbours. 



The dorsal blood-vessel is single. I did not detect a supra- 

 intestinal vessel. 



There are three pairs of hearts, in segments x., xi., xii. Of these, 

 the last only has the usual form and arrangement as a semi- 

 circular, dilated commissural vessel passing freely from the dorsal 

 to the ventral vessel (PL XXYI. fig. 39). 



But the other two pairs present a condition which appears to 

 be unique : they are, for the greater part of their extent, adherent 

 to the oesophageal wall ; indeed, they appear in sections to be 

 rather dilated, circularly disposed channels of the general peri- 

 oesophageal plexus. Each becomes free only at its ventral end ; 

 at the same time it becomes gradually reduced in diameter, and 

 soon becomes very narrow where it joins the ventral vessel 

 (PI. XXYI. fig. 40). Anteriorly to the tenth segment I find 

 narrow commissural^ of the usual character. 



The alimentary canal is provided with a pharynx of the usual 

 form ; there is no gizzard nor cesophageal gland. 



The oesophagus and intestine contain abundance of food, 

 amongst which the valves of diatoms are present in considerable 

 numbers. The oesophagus is a good deal dilated segmentally, and 

 passes into the wider intestine in segment xviii., where the 

 character of the epithelium suddenly changes from a high to a 

 shorter type of cell. 



The worm is meganephiie, with large funnels ; but nephridia 

 are absent in the anterior segments ; the first one occurri'as: in 



