320 OLIGOCHAETA 



referred to in the definition. It is also remarkable in having more setae than any 

 other Enchytraeid. Michaelsen does not mention the comparative lengths of the 

 sperm-duct and the funnel which is often, apparently, a useful specific character. The 

 clitellum is longer in extent than in any other Enchytraeid ; it reaches from the 

 eleventh to the fourteenth segment, occupying, however, but half of the first and the 

 last of these segments. The egg-sac is single and extends below the gut to the 

 eighteenth segment ; the sperm-sacs are paired and do not extend beyond the fourteenth 

 segment. The lymph corpuscles are flat and N'avicella-hk.e in form. 



(9) Mesenchytraeus armatus (Levinsen). 



Analycus armatus, Levinsen, Vid. Med. 1883, p. 232 ^ 



Mesenchytraeus armatus, Michaelsen, Abh. Nat. Ver. Hamb. 1889, p. 18. 



Definition. Setae, 1-6 in a lundle, those of segments IF — FI (one or two to each segment) 

 double the length of the rest. Hah. — Denmark. 



This species agrees with the last in the possession of large setae ; it is to be 

 distinguished from it by its smaller size, and also in the smaller number of setae 

 in some of the segments. 



Genus STEECUTITS, Michaelsen. 



DEFiisriTiow. Setae as in Pachydrilus. Head-pores present. Dorsal vessel ante- 

 clitellian in origin, with cardiac body; blood colourless. No salivary glands. 

 Spermathecae not opening into gut. • 



This genus, of which our knowledge is entirely due to Michaelsen, is in many 

 respects remarkable. It appears to connect the genera Mesenchytraeus and Buchholzia ; 

 it has the cardiac body of the former genus, and the ante-clitellian origin of the 

 dorsal vessel found in the latter. The other characters of the worm I shall regard 

 as specific, and describe under the species — 



Stercutus niveus, Michaelsen. 

 Stercutus niveus, Michaelsen, Arch. Mikr. Anat. 1888, p. 483. 

 Definition. Length 6 mm. ; number of segments a8 ; setae 3-4 per bundle. Funnel of 

 sperm-duct small; spermathecae oval, with no constriction between pouch and duet; 

 glands at base of latter. Hob. — GerrAany. 



' See footnote, p. 317, 



