24-2 PFRTCHAETA SIEBOLDl. 



number of setae in the spermatbecal region amounts to 60 '). 

 There is also a smaller number of bristles between the 

 spermatbecal pores, for Rosa states that they are situated 

 »in der neunten Horstenlinie", while in F. Sieholdi they lie 

 in the eighteenth, counting from the ventral median line, 

 thus showing 36 bristles in the space between the sper- 

 matbecal pores. In P. Ijimae the dorsal pores commence 

 behind the clitellum, while in P. Sieholdi the first of them 

 lies in front of it, in the intersegmental groove XII/XIII. 

 Rosa found the spermathecae of P. Ijimae without a diver- 

 ticulum, and instead of the lobed intestinal coecum of 

 P. Sieholdi that species only shows a single coecum extending 

 anteriorly over five segments. As it is rather diflBcult to 

 discriminate the continually increasing number of Perichaeta- 

 species, I hope the Japanese authors will give us a more 

 detailed account of the characters of the specimens they 

 examined *). For it is a strange fact that hitherto they 

 have not come across any of the nine species, described by 

 European authors. 



Leyden Museum, December 1898. 



1) Perhaps specimen ^ of P. Uilgendorfi Mich, also belongs to this species. 



2) Unfortunately there crept some errors in the table annexed to the paper, 

 npon which the attention may be fixed: P. fuscata is said to possess four pairs 

 of spermathecae in segments VI — IX, while on the table only three of them 

 are indicated in segments V — VII; P. campestris has two pairs of spermathecae 

 in segment VIII and IX, while on the table three of them are enumerated 

 in segments VI — VIII; the first dorsal pore lies in the intersegmental groove 

 XIII/XIV according to the text, on the table between segment XII and XIII. 

 P. heteropoda has no prostata, while on the table it is indicated in seg- 

 ment XVIII. 



Notes from tlie Lieyden JVIuseuizi, Vol, XX. 



