TWO AQUATIC OLIGOCH^TES. 



43 



wall of the duct portion of the atrium. The chitinous sheath is 

 nearly straight and is expanded like a trumpet at its distal end. 



The penial chamber opens externally 

 on each side of the ventral median line at 

 about the middle of segment XI. The 

 muscle fibres of the outermost layer of the 

 wall of the penial chamber run parallel to 

 the axis of the penis and not spirally as 

 in L. gotoi. 



4). Spermathecao. One pair of sig- 

 moidal spermathecœ open at the anterior 

 part of segment X in front of the ventral 

 seta-bundles. The saccular portion is sepa- 

 rated from the duct by a constriction and 

 lies generally in its own side of the body, 

 but sometimes the spermathecge are decus- 

 sated (fig. 34). The minute structure is 



L. willeyi 

 sheath. 



Fig. 32. 



Chitinous penis 



i — ct 



il — 



pch 



Fig. 33. 



L. willeyi. Penis and penial 

 chamber in longitudinal sec- 

 tion, cm— circular muscle of 

 the duct-portion of the atrium, 

 ct — peritoneal connective tis- 

 sue, m — longitudinal muscle 

 fibre of the penis, ol — lining 

 epithelium of the penial 

 chamber, il — inner wall of the 

 penis, cs — chitinous sheath, 

 pch — penial chamber. 



■*P- 



-/Sprf 



Fig. 34. 



L. willeyi. Spermathecœ and neighbouring organs, from 

 a slightly compressed living specimen, os— spermathecal 

 pores, spt — septa, s — setre, spp — spermatophores, int — in- 

 testine, IX, X, XI— numbers of segments. The anterior 

 end of the clitellum is shown by a broken line at the 

 middle of segment X. 



the same as in L. gotoi. Spermatophores, which are mostly 

 spindle shaped, are always present in the saccular portion. 



