ZooL.— Vol. II.] RISEN— OLIGOCHMTA. 235 



The oviducts open separately, each one on a papilla 

 occupying the whole width of the somite. The cells of 

 this papilla are very thin and stain less deeply than the 

 clitellar cells. 



Ne^hridia. — (fig. 90.) The nephridia are strikingly like 

 those of -diBenhamia. There are only micronephridia arranged 

 in four rows on each side, extending from the ventral to the 

 dorsal side, almost uniting with each other at the dorsal line 

 of the body. Each one of the four micronephridia consists 

 of a coelomic rounded mantle, with ducts along its anterior 

 margin. Nephridium i consists of one larger and two 

 smaller mantles, the latter covering part of the ducts nearest 

 the nephrostome. I could only find nephrostome belonging 

 to nephridia i; they are in line with set« ab. There is a 

 pair of peptonephridia in somite IV. In the specimens 

 from Hawaii the nephridia are arranged as in fig. 90. In 

 the specimen from Del Monte the fourth and most dorsal 

 nephridium is situated much nearer the dorsal line, there 

 being a space between the third and fourth nephridium as 

 wide or wider than the largest micronephridium. 



Vascular System. — The last hearts or connecting vessels 

 are in XII, Commencing with XIV the dorsal vessel is 

 greatly enlarged, forming out of the main median trunk a 

 large median heart separated from the one in somite XIII 

 by valves. The corresponding enlargement in XIII is 

 almost as large, but the one in XII is several times smaller, 

 and hardly larger than the normal size of the vessel. A 

 similar enlargement of the dorsal vessel has been described 

 by Beddard in Milhonia ruhens. 



Dichogaster Ribaucourti, sp. nov. 



Plate XIV, Fig. 181. 



Definition. — Length 80 to 100 mm., width 3 mm. Somites 150. Prosto- 

 mium very narrow, divides somite I completely. No dorsal pores anterior 

 to clitellum. Genital zone consists of two elevated crescent ridges, with the 

 concavity ventral, in somites XVII to XIX. Setae strictly paired. No penial 



