1118 Dll. J. STEPHENSON ON THE OLIGOCHiETA OF THE 



in these subgeneiic distinctions ; but it is possible tliat a posterior 

 origin of the dorsal vessel will be a sufficient ground for removing 

 out of the genus altogether the forms in which it occurs. 



On THE Eelations of the Genera Zumbricillus and 

 Enchytrceus. 



I have previously (13) pointed out the close relationship 

 between the above two genera, and described several species with 

 intermediate characters ; Enchytrceus ditbius, which I then ]..ilaced 

 in the genus Enchytrceus, I should now assign to Luinhricilhis. 

 Welch also has some remarks that bear on the subject 

 (19, 23). 



The distinguishing cliaracters of the two genera naay be said to 

 be (1) tlie setae — the distal portion of the shait being straight in 

 Enchytrceus, curved, so that the setee have the usual double 

 (sigmoid) curve, in Luinbricillus ; (2) the copulatory glands — 

 usually absent in Enchytrceus, usually present in Limihricillus ; 

 (3) the testes, divided in Limihricillus, undivided in Enchytrceus ; 

 and (4) the penial bulb — single, compact, encapsuled, and 

 penetrated by the vas deferens in Lumbricillus, represented by 

 discrete groups of cells around the end of the duct in Enchytrceus. 

 In addition^ red blood would be in favour of Luonlricillus, colour- 

 less blood more in favour of Enchytrceus. 



Of the species described in the present paper, Luonhricillus 

 cegicdites has the straight set?e of Enchytrceus, and so has 

 L. necrophagus ; while Enchytrceus crymocles has a penia,! bulb of 

 the lumbricilline type, copulatory glands, and htemoglobin in the 

 blood. These species thus bear out what I have previously written 

 regarding transitional forms, and render a sharp separation 

 between the genera impossible. Still less is there such a sharp 

 distinction between the two as would justify their position as the 

 representatives of two subfamilies, the Enchytrteinae and Lum- 

 bricillinje, eatablished by Eisen (6). 



Pekiods of Sexual Maturity. 



Some of the worms in the collection were sexually mature, 

 others immature. But it is not possible to draw any general 

 conclusions from the data regarding the season of maturity in 

 high latitudes. Enchytrceus cdbidas was mature on Bear Island 

 in June and E. crymocles in early August in Spitsbergen; but an 

 immature Enchytrceus was also collected on August 6th. Henlea 

 h&leotrophus and H. hrucei were mature in early August — 

 H. heleotrophus also as early as July 10th ; but other species of 

 Henlea were still immature in early August. The two species of 

 LimibricillujS were mature towards the end of July and beginning 

 of August ; the Mesenchytrceus, however, was immature at any 

 rate up to the end of July. 



