268 OLIGOCHAETA 



Genus BOTHRIONETJRON, STOLC. 



? Syn. Monopylephorus, LEVINSEN. 



DEFINITION. Setae only uncinate, ventral setae of segment XI sometimes modified. 

 Male pore single or paired. Spermiducal gland with a short diverticulum bearing 

 the prostate. No spermathecae ; spermatophores fixed to the integument near 

 to male pore. 



I believe that LEVINSEN'S genus Monopylephorus is identical with STOLC'S recently 

 (3) described Bothrioneuron. LEVINSEN gives but few details about his genus ; he 

 states, bowever, in the table of the generic characters of the Tubificidae (p. 223) that 

 there are no capilliform setae, that the male pore is unpaired, and that the penis is 

 without a chitinous sheath. In all these characters Monojnjlephorus agrees with 

 Bothrioneuron, except perhaps in the presence of a penis ; in Bothrioneuron, however, 

 STOLC has figured (Tav. iv, fig. 7) a short diverticulum of the spermiducal gland, near 

 to the external aperture of the latter, which may possibly be everted at times and 

 give the appearance of the penis of other Tubificidae. VAILLANT (6) considers not 

 only that Monopylephorus is synonymous with Clitellio, but that LEVINSEN'S species, 

 M. rubroniveus, is identical with C. arenarius. It is true that the latter identification 

 is prefaced by a query ; but I do not see any reason why VAILLANT should suggest that 

 LEVINSEN'S genus should be considered ' doubtful.' 



The most marked characters of this genus are the absence of the spermathecae 

 and the peculiar form of the spermiducal glands ; there is no other Tubificid in which 

 spermathecae have not been found. The absence of these organs is correlated by STOLC 

 with the remarkable form of the spermatophores ; these have an appearance in STOLC'S 

 figures which recall the corresponding organs in Lumbricidae ; they are stalked bodies 

 invariably found attached in the neighbourhood of the male pore. The free end is 

 wider and oval in form, and seems to contain the sperm. The two spermiducal glands 

 open by a common pore, which is in the middle line of the eleventh segment ; each 

 is divided into two regions, the two being separated by a constriction ; into the distal 

 region opens the short and slender sperm-duct ; STOLC considers it to be a dilated 

 part of the sperm-duct rather than a part of the spermiducal gland ; it differs from 

 the succeeding section by the thicker coating of peritoneum, the thickening being 

 due not to an increase in the number of cells, but in their greater depth ; the lumen, 

 too, is much narrower than in the section of the terminal gland which follows, though 

 the entire width of the tube is about the same ; the following section is lined by 

 a higher cylindrical epithelium and is covered by a lower layer of peritoneal cells ; 



