282 SUBANTARCTIC ISLANDS OF NEW ZEALAND. [Oligochaeta. 



Two spemiathecal pores, apparently at 7/8, 8/9, are seen in well-extended 

 specimens to be really on the hinder margins of segments 7, 8, in line with de. In 

 one case I note three pairs of these pores ; in another, three on one side and two on the 

 other side, the extra one being anterior. 



The nephridiopores are at the level of the 7th chaeta (g) or the 8th (A), 



Internal Anatomy. 



None of the septa are noticeably thickened. The dorsal vessel is single, and 

 the last heart is in the 12th segment. There are some rather interesting facts about 

 the relations of the hearts, but in the present communication I will confine myself 

 to those characters which are diagnostic. 



The gizzard is vestigial in the 6th segment ; it appears in sections as a short 

 muscular ring, whose length is about equal to half the length of the segment ; it does 

 not project beyond the outline of the oesophagus, and is about as thick as one of 

 the villi that Une this part of the tract. Behind the gizzard the oesophagus is a 

 narrow tube with the usual villous epithelium ; in the 12th and 13th it is dilated, 

 and the epithelium is raised into a series of lamellae ; in the 14th it again 

 narrows ; it is dilated once more in each of the segments 15 and 16, still being lamel- 

 late ; and the same structure is retained in the 17th-20th, when the epithelium 

 alters its character and puts on the ordinary appearance of intestinal epithelium. 

 In a dissection, one would say that the intestine commences in the 17th, judging 

 merely from the diameter, but the limitations of the regions of the enteron in these 

 and most worms, other than the European Lumbricids, deserve further study, 

 especially from the histological point of view. 



The nephridium is limited to the lower half of the body-wall, extending up to the 

 8th chaetae, where the large pyriform bladder is seen to penetrate the wall to open 

 to the exterior. The tubule of the organ is compactly coiled. 



The testes and ovaries are in the normal position. There are two sperm-sacs, 

 in the 9th and 12th, large and lobulate. 



The prostate is long, extending from the 18th segment to the 28th or 29th 

 segment ; the tip is recurved sharply, and runs forward, in the specimens dis- 

 sected, to the 26th. The narrow duct, limited to the 18th, is transversely directed 

 towards its pore ; as it passes through the body- wall it is excessively fine, so 

 that it is not easy to trace. The united sperm-ducts open into the prostate in the 

 19th segment, passing through the gland-cells obliquely to enter the lumen of the 

 gland. 



The lumen, which in section is wide, is lined by tall narrow cells, between which 

 the delicate necks of the gland-cells pass to open into the central canal. Outside 

 the epithelium is a finely granular region, which appears to be due to the sections 

 of the necks in all planes as they approach the canal. 



The spermatheca (two pairs, in the 8th and 9th) has a small diverticulum joining 

 the duct close to the ampulla (Plate XI, fig. 29). 



Locality. — Snares. Several specimens were collected both in February and in 

 November, so that it is a common worm. 



Remarks. — Hitherto five species of worms have been described from New Zealand 

 area as belonging to the genus Diporochaeta — indeed, the type of the genus is one 



