Smith. — Notes on Neiv Zealand Earthworms. 137 



This is frequently met with among terrestrial Oligochceta, 

 where it appears to have an obvious relation to the density of 

 the medium in which they live. Increased muscular power in 

 the anterior segments is not so much needed by worms which 

 swim in water, and is not developed. Pelodrilus, however, 

 does not live in water, like most of its allies, but in marshy 

 land ; and its structure bears evidence of its mode of hfe, not 

 only in the thick longitudinal muscular coat of the anterior 

 segments, but also in the greatly-increased thickness of some 

 of the anterior intersegmental septa. The epidermis consists 

 of the usual glandular cells, between which lie tall interstitial 

 cells. The circular muscular layer is not more than two fibres 

 thick in the anterior thickened region of the body. In con- 

 nection with the epidermis I may mention the presence of two 

 sucker-like structures, which lie, one behind the other, in the 

 middle ventral line of segment x. These bodies seem to be 

 possibly organs of sense connected with the generative func- 

 tions. 



"Alimentary Canal. — This presents the characters that are 

 usually met with in the lower Oligocholia — that is, there is no 

 gizzard, and no glands appended to the canal. The buccal 

 cavity occupies the first segment of the body. Its walls con- 

 sist of little else than a layer of somewhat flattened cells. 

 The pharynx also occupies a single segment — the second. It is 

 chiefly distinguished by the thickened epithelium, developed 

 only on the dorsal side ; which begins and ends abruptly. A 

 few muscles attached to the pharynx connect it with the 

 body-wall. The oesophagus is narrow 7 , but the commence- 

 ment of the intestine is hardly wider. The latter is distin- 

 guished by its epithelium being ciliated. The chloragogen cells 

 commence in the fifth segment. It was Claperede who first 

 noticed that the chloragogen layer covering the intestine was 

 a fixed point often characteristic of the species. 



" Nephridia. — The nephridia, instead of being, as is the rule 

 in the aquatic Annelids, absent in the genital segments, are 

 present in all the segments of the body commencing with the 

 seventh, and excepting the eleventh and twelfth. There is 

 hardly any development of peritoneal cells round the ne- 

 phridia ; certainly the large vesicular cells, which are so often 

 found in the aquatic Oligochceta, are absent. 



" Body -cavity. — The septa which separate the ccelom into 

 a series of cavities corresponding to the external segments 

 are replaced in the four anterior segments by irregularly- 

 placed fibres and bundles of fibres passing between the 

 alimentary tract and the parietes ; after the fifth segment the 

 regular septa begin. It is interesting to find that the first five 

 of these are very thick, and consist of two distinct muscular 

 coats, whose fibres run in opposite directions. The septa are 



