204 ON PERICHAETIDAE. 



limited to the number of papillae; they also show remark- 

 able differences in the number of spermathecae. Only 

 in a single specimen two pairs of spermathecae were 

 observed in segments VI and VII; they agree rather well 

 with Michaelsen's description , though I found the main 

 pouch more pear-shaped than globular and the diverticulum 

 only extending till the half of its length in stead of two 

 thirds. Considering however that the shape and size of 

 this pouch depends somewhat on the state of being more 

 or less filled, I think no much value can be ascribed to 

 those differences. Of the seven remaining worms one spe- 

 cimen (with 4 pairs of papillae) only shows a single 

 spermathecal pore at the left side in the intersegmental 

 groove V/VI, corresponding with a spermatheca without 

 diverticulum in segment VI ; another specimen (also with 4 

 pairs of papillae) has three spermathecal pores in a row 

 in the same situation. Comparing the spermathecae of the 

 last individual with those of the first one , the main pouch 

 proves to be somewhat more slender and the diverticulum 

 does not extend quite till the half of its length. In the 

 fourth specimen also at one side (the right) spermathecal 

 pores are visible, 4 in the intersegmental groove V/VI and 

 3 in that between segments VI and VII. On the contrary 

 in four other specimens no trace whatever of spermathecal 

 pores or spermathecae could be found; they agree in this 

 character with both individuals examined by Beddard , and 

 represent , I think , his species P. acystis. 



As Benham already suggested , that in this species the 

 spermathecae might perhaps be not yet functional and 

 therefore extremely minute like in some specimens of 

 Lumbricus herculeus with fully-developed sperm-sacs and 

 clitellum, I made transverse sections of one of our worms , 

 but no trace of spermathecae was visible. 



Also the arrangement of the setae showed some irregu- 

 larity in a couple of worms. Ordinarily the distance between 

 both enlarged ventral bristles measures four times the 

 usual distance; on some segments, however, it can amount 



Notes from the Leyden ]VIuseu.ni, Vol. X.X. 



