352 OLIGOCHAETA 



near to 'nasuta'; upon this matter Michaelsen writes : 'Eisen's Angabe von der Verwandtschaft des 

 A. affinis mit seinem A. nasutus ware zu bestatigen, falls die oben angefuhrte Synonymie angenommen 

 werden musste.' 



Ude unites the two species on the following grounds : Miohaelsen admitted that the two species 

 stood very near to each other ; but he distinguished them by the fact that in H. nasuta the appendices 

 of the oesophagus were much more folded internally than in H. leptodera, and that in H. nasuta the 

 setae, instead of being about the same length, are of different sizes. Ude found in the same individual 

 of H. leptodera some bundles in which the setae were of the same length, and others in which the setae 

 were unequal, like the typical H. nasuta ; in one preparation it was found that the left oesophageal gland 

 had a much less folded lumen than the right gland, thus doing away with the second difference between 

 the supposed two species. 



This species differs from the last in having well-developed salivary glands. The 

 oesophageal glands are in the seventh segment, and open into the gut between 

 this and the following segment. The brain is stated by Ude to be broader than 

 long, but by Vejdovsky to be as long as broad — a difference, no doubt, to be accounted 

 for on the supposition that the brain varies in its proportions according to the 

 state of contraction of the muscles which are attached to it. There seems to be 

 a little confusion as to the precise segment in which the dorsal vessel arises, and 

 in which segments the dilatations are; Vejdovsky (3, p. ^z) says that the dorsal 

 vessel can be followed back as far as the seventh segment, and that the hearts are 

 in segments vii, viii — two statements which do not appear to be reconcileable ; in the 

 systematic part of the same work (on p. 56) he places the heart-like swellings in 

 segments vi, vii; the latter statement is followed by Vaillant (6, p. 266). Ude, 

 on the other hand, notes the commencement of the dorsal vessel in the same segment 

 as in the last species, i. e. the ninth. The spermatheca is much as in the last 

 species, but the duct is rather shorter than thfe pouch, and the latter is not dilated 

 before its external pore. 



(3) Henlea dicksonii (Eisen). 



Arehienchytraeus Dicksonii, Eisen, Ofv. Svensk. Akad., 1878, No. 3, p. 70. 

 Enehytraeus Dicksonii, Vejdovsky, Syst. u. Morph., 1884, p. 41. 

 Henlea Dicksonii, Michaelsen, Abh. Nat. Ver. Hamb., 1889, p. 33. 



Definition. Length, i^mm.j number of aegments, 52; ietae straight or a little bent to 

 one side, of different sizes, 6-8 per bundle. No oesophageal glands. Hah. — Nova Zemlla ; 

 Germany. 



Eisen's account of this species is not sufficient to place it accurately; it was subsequently 

 investigated by Michaelsen (5), who, however, had only a specimen minus the anterior end ; hence 

 he was unable to do more than state that the dorsal vessel, not being there visible, must originate 

 in front of the clitellum. A complete description of all the important facts in the structure of this 



