NEW SPECIES OF OCNERODRILUS. 243 



towards the caudal end, the largest nephridia being found 

 a comparatively short distance from the tail end (figs. 5, 

 10, 14). The size and quality of these peritoneal cells 

 vary considerably in different specimens; sometimes they 

 are perfectly transparent with no dark cell contents, at 

 other times they are so filled with a granulated mass or 

 sections that the nuclei are not visible. Quite frequently 

 the anterior nephridia show some peritoneal cells, the an- 

 terior ones always less than those in somite vii'i which 

 nearly always possesses a few of them. As has been 

 already stated the nephridia in somite ix show a large 

 mass of peritoneal opaque cells as many as any of the 

 largest nephridia behind the clitellum. This is not the 

 case in all species. For instance, in Ocnerodrihis Roscb 

 the nephridium in somite ix is entirely destitute of peri- 

 toneal cells. Still this nephridium is larger than any of 

 the nephridia anterior to the clitellum (fig. 23, //. ^/^.). 



The upper part of each nephridium contains the great- 

 est quantity of peritoneal cells. In the middle part the 

 number diminishes, again increasing in the part nearest 

 the nephridio pore. These pores open between the setse 

 and the anterior septum in line with the inner row of setae. 

 In the lower part of the nephridium the peritoneal cells 

 cover the canal on one side, while in the upper part the 

 canal is entirely hidden by the cells. From the outside 

 the nephridia appear like very large whitish masses al- 

 most entirely filling the somites. The quantity of perito- 

 neal cells vary in different species. In some, as in 

 Ocnerodrilus occidentalts, the peritoneal cells even in the 

 posterior nephridia are comparatively few. 



Testes. There are two pair of testes, one in somite 

 X and one in xi. This being the rule in most species. 

 They are attached to the ventral side of the anterior 

 septum against which they are generally pressed flat. 



