46 GUSTAF EISEN, ON THE AHCTIC OLIGOCH^TA. 



c = the receptacle, showing the numerous glands surrounding the tube. 



d = the efferent duct and penis. 



e = one of the testes with verv much elongated lobes. 



/ = one of the lobes,' still further magnified, containing spermatozoa in different stages of development. 



g = another lobe containing encysted spermatozoa. 



h = a testicle with very small lobes. 



k = a part of an ovary with a ripe egg. 



I = another ovary with two ripe eggs. 



Fig. 13. Lumbriculus variegatus Grdbe. 

 a — the supra-oesophagial ganglion seen from above. 

 b = the receptacle. 



c = peculiar glands iu the segments 8, 9, 10 and 11. 

 d = one of the spines highly magnified. 



e = a part of the segments 8 and 9 showing the relative position of the segmental organs and of the 

 above glands. 



PLATE VIII. 



Fig. 14. Allolobophora Nordenskiöldi n. sp. 

 The front part of one of the spines showing its wavelike engravings. 



Fig. 15. Allolobophora foetida Sav. 

 The front part of one of the spines, showing the minute concavities of its top. 



Fig. 16. Archienchytrceus nervosus n. sp. 

 a = the front part of the worm, seen from above. 



b = the supra-oesophagial ganglion seen from above, in optical section. 



c = a part of the ventral nerve-cord from the 3 d and 4th segments showing the characteristic enlarge- 

 ment of the nerve-ganglia. 



d = a part of the ventral nerve-cord from the llth, 12th and 13th segments 



e = the receptacle in optical section. 



f = the efferent duct and penis. 



g = one of the ovaries with ripe eggs at the top. 



PLATE IX. 



Fig. 17. Neoenchytrceus fenestratus n. sp. 

 a = the worm, nat. size. 

 b = the Lind part of the worm. 



c = the front part of the worm, seen from the side. 



d = a bundle of spines showing their number and relative size, and form. 

 e = a single spine still more magnified. 

 f = the front part of the nervous system seen from above. 

 g = the receptacle. 

 Ii = some of the perigastric cells. 



Fig. 18. Neoenchytrams Stuxbergi n. sp. 

 a = the worm nat. size. 



b = the front part of the worm, seen from above. 

 c = the same part seen from the side. 

 d = hind part of same. 



d = a bundle of spines showing their relative size. form and number. 



e = the front part of the nervous system seen from above; m. m. = muscles. n. u. = nerves from the 

 supra-oesophagial ganglion. sn = side-nerves in the fourth segment. 



/ = the receptacle surrounded at the base and along the tube with numerous glands. 

 g = the efferent duct and penis. 

 h = one of the testidés. 

 k = one of the ovaries. 





