250 FRANK E. BEDDAED. 



portion of the nephridium of the 13th segment (fig. 10) ; 

 its walls are made up of muscular fibrils^ and it has a coating as 

 well as a lining of peritoneal cells. Each sac is situated near 

 to the anterior wall of the 13th segment; traced backward by 

 means of a continuous series of transverse sections^ the sac 

 abruptly diminishes in calibre, and forms a narrow tube which 

 is continuous with the tube formed by the narrowing of the 

 ovarian sac of the opposite side of the body. A section which 

 illustrates these relations is illustrated in fig. 51. 



The bursa copulatrix, which is spherical in transverse 

 section, opens on to the exterior by the median pore of Segment 

 13. From the bursa copulatrix arises a single blind pouch, 

 which may be regarded as the spermatheca. This has alining 

 of tall epithelial cells of a glandular appearance, and very thick 

 muscular walls. The spermatheca directly it leaves the bursa 

 becomes enveloped in a coelomic sac_, as shown in fig. 11 ; this 

 coelomic sac is not the connecting tube between the two 

 ovarian sacs shown in fig. 51, but it is continuous with 

 the sac involving the ovary of its ov/n side; the sperma- 

 theca of each side runs up the side of the oesophagus for a 

 short way, terminating blindly at about the middle of the dorso- 

 ventral diameter. The sac in which the spermatheca is con- 

 tained passes right round the oesophagus, and, fusing with its 

 fellow of the opposite side of the body, is prolonged backwards as 

 an unpaired median sac lying above the oesophagus ; this struc- 

 ture is that which is illustrated in figs. 5, 11, and lettered sp' . 



It must be noted, therefore, that what appears on dissec- 

 tion to be an unpaired spermatheca, lying above the 

 oesophagus and connected with the bursa by a ring 

 round the oesophagus, is really a coelomic sac contain- 

 ing the true spermatheca, and does not communicate 

 directly with the exterior through the bursa copula- 

 trix. 



This coelomic space comes into close relations with the ovi- 

 ducal funnel which seems to open into the rcceptaculum 

 ovorum (figs. 1, 5, 8, 11 r. o.), but does not involve the rccep- 

 taculum or the oviduct. ' 



