CALIFORNIA EUDRILID^. 47 



begins at tlie point of locnnence at Q, bnt ceases after the dnct has assumed its straight 

 course at 0; it begins again at (3, and is witli a certainty found Ix'tvveen @ and 

 @, and possibly between (n) and @, where, however, T am not quite certain of 

 its presence. The whole nephridial fold is imbedded in a wing-like cellular and 

 fibrous mass, which at either end becomes thicker, supporting large pellucid perito- 

 neal cells, such as found in the nephridia of many Oligochitta (fig. B4, /)er. c), and a 

 complex system of blood-vessels, which branch and form capillary loops partly on the 

 folds, but principally between the spongy tubes and the two central canals (figs. 59, 

 (io, 04, fi7, />/.). The blood-vessels originate from a branch of the ventral vessel as in 

 Lumbricus. 



Scattered over the jicritoneal cells are masses of free cells, generally agglom- 

 erated in separate heaps. Eacii cell is deeply crenate, as if it consisted of several in- 

 dividual cells, but in each such small agglomeration there is only one round nucleus 

 (fig. <S0). 



If we recapitulate, we lintl that the nephridum of Argilophilus consists of the 

 following distinct part from the nephridio-stome to the nepridio-pore: 



1. Nephridio-stome, engaged in the anterior sc])tum. 



2. Narrow duct, which connects the nephridio-stome with the body of the ue- 

 phridium proper, especially with the spongy tubules. 



3. Spongy tubules, which are at first irregular, but which soon fuse into one 

 main-tube with many branching tubules. 



4. Main nephridial canal, which, recurring on itself several times, forms two 

 distinct folds and one spur. The posterior fold contains besides the tube and tubules 

 two turns of the canal, one of which is recurring. The anterior fokl contains three 

 turns of the canal, two of which are recurring. Part of this anterior fold disengages 

 itself from the main nephridial mass and forms the ' 



5. Spur. This spur contains four canals, two of which are recurring, the 

 point of recurrence for all four being at the distal end. One of the recurring canals 

 of the spur is connected with the posterior fold by the 



0. Bridge, a part of the canal much narrower than the other, spanning the 

 distance between the two folds. 



7. The wide duct leading to the nephridio-pore, directly connected with the 

 recurring canal of the posterior fold. In different nephridia this wide duct is of 

 varying length. 



8; Nephridio-pore, apparently without urinary bladder or collar. 



9. A large wing-like, but rather thin, mass of peritoneal cells. 

 10. A complicated and extensive system of capillary blood vessels on the va- 

 rious parts of the nephridium. 



Compared to the neiihridium of Lumbricus as described by Benham we finti 

 a few more im|iortant iliflferences, especially in the post-septal part. Thus the post- 

 septal part of the narrow tube after reaching the first loop assumes the sliape of a 



