344 OLIGOCHAETA 



spermathecae are intermediate in their characters between those of the simpler forms 

 without any diverticulum and the more differentiated species ; the pouch swells out 

 at the base into three compartments, which are not constricted off from the main 

 chamber. 



(4) Fridericia bisetosa (LEVINSEN). 



Enchytraeus bisetosus, LEVINSEN, Vid. Med., 1883, p. 233. 



E. ( Mesenchytraeus i bisetosus, VAILLANT, Annele's, p. 268. 



E. (Neoenchytraeus, EISSN) Leydigii, MICHAELSEN, Ench. Mob., 1886, p. 47. 



E. tenuis, MICHAELSEN, Arch. Mikr. Anat., 1886, p. 294. 



Neoenchytraeus bisetosus, ROSA, Boll. Mus. Zool. Torino, 1887, No. 29. 



P. bisetosa, MICHAELSEN, Abh. Nat. Ver. Hamb., 1889, p. 43. 



Definition. Length, 20 mm.; number of segments, 60 ; setae, paired. Anteseptal region 

 of nephridium nearly equal to postseptal, with -undulating duct. Spermathecae with two 

 diverticula. Hal. Denmark; Germany; Italy. 



It does not appear to be quite certain whether MICHAELSEN'S 'Enchytraeus tennis' is really 

 identical with LEVINSEN'S ' Enchytraeus setosus'; MICHAELSEN himself, in a paper subsequent to that 

 in which the species was described, considered that the question of the identity of the species was not 

 settled ; the principal difficulty in the way of uniting them was the fact that in the supposed species 

 'tenuis' the anteseptal part of the nephridium was not equal in extent to the postseptal. UDE 

 commented upon differences in the form of the diverticula of the spermathecae, and the form of the 

 funnel of the efferent duct. In the meantime I retain here the view expressed in MICHAELSEN'S 

 paper, viz. the identity of the species. 



The species is characterized by the fact that there are, as a rule, but two setae to 

 each bundle ; this is, however, not invariably the case ; four were found by UDE 

 in immature individuals, one pair of which were, however, evidently just on the point 

 of falling out. The brain is about double as long as broad, with a nearly straight 

 or slightly concave hinder margin (convex in 'tenuis'). The dorsal vessel arises in 

 the eighteenth segment ; the salivary glands are slightly branched ; the funnel of 

 the male efferent duct is double as long as broad ; the ducts themselves are long and 

 coiled ; the spermiducal glands are large. 



(5) Fridericia leydigii (VEJDOVSKY). 



Enchytraeus Leydigii, VEJDOVSKY, SB. Bohm. Ges., 1877, p. 303. 

 E. (Neoenchytraeus) Leydigii, VAILLANT, Anneles, p. 255. 

 Neoenchytraeus Leydigii, ROSA, Boll. Mus. Zool. Torino, 1887, No. 29. 

 P. Leydigii, MICHAELSEN, Abh. Nat. Ver. Hamb., 1889, p. 43. 



