DESCRIPTIONS OF GENERA AND SPECIES 317 



per bundle. Spermathecae conical, with 4-5 globular diverticula; sperm-duct generally 

 much longer than funnel. Hab. — Siberia. 



This species, like the last, has been investigated by Eisen (13), and Michaelsen 

 (2, 5). The last-mentioned author deals with a few points not referred to by Eisen. 

 He figures and describes the cardiac organ, stating that it agrees with that of the 

 last species in being larger than that of M. heumen, and in being composed of 

 a considerable number of cells. There is (according to Michaelsen) a single sperm- 

 sac, which extends as far back as the twenty-sixth segment ; the median egg-sac 

 reaches further back still, to the twenty-ninth segment. Both sacs are constricted 

 where they pass through the septa; this constriction is shown in one of Eisbn's 

 figures (13, PI. xv, fig. 44); these figures indicate gaps between the anterior and 

 posterior parts of the sperm-sacs. 



(3) Mesenchytraeus falciformis, Eisen. 



Mesenchytraeus falciformis, EiSEN, Ofv. Svensk. Akad. 1878, No. 3, p. 68. 

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

 Enohytraeus (Mesenchytraeus) falciformis, Vaillant, Annel^s, p. 272. 



Definition. Length, 4-5 mm. ; breadth, 3 mm. ; number of segments, 50 ; setae, ^-6 per 

 bundle. Spermathecae, long 'and narrow, without diverticula; sperm- duct six times as 

 long as funnel. Hab. — Nova Zembla. 



The cardiac body is, according to Michaelsen (2), smooth and thin and com- 

 posed of but few cells. The median egg-sac extends back as far as the nineteenth 

 segment in the specimens examined by Michaelsen ; Eisen figures the egg-sacs as 

 paired structures reaching back to the sixteenth segment only. 



(4) Mesenchytraeus fenestratus, Eisen. 



Neoenchytraeus fenestratus, Eisen, Ofv. Svensk. Akad. 1878, No. 3, p. 74. 

 Enohytraeus fenestratus, Vejdoysky, Syst. u. Morph. 1884, p. 41. 

 Analycus glandulosus, Levinsen, Vid. Med. 1883, p. 23a ^ 

 Mesenchytraeus fenestratus, Michaelsen, Abh. Nat. Ver. Hamb. 1889, p. 17. 

 Enohytraeus (ifeoenchytraeus) fenestratus, Vaillant, Annel^s, p. 266. 



Definition. Length, 15-26 mm.. ; breadth, i mrn.^; number of segments, 60 ; setae, 5-7 jier 



bundle. Spermathecae elongated without any diverticula ; sperm ducts very short, not longer 



than funnel. Hab. — Siberia ; Denmark. 



' Levinsen considers that his species = Enehytraeus albidus of Taueek in part, the latter also including his 

 (Levinseh's) 'Analycus armatus.' 



