650 OLIGOCHAETA 



is in segment xi. From the forwardly-directed apices of the calciferous glands arises 

 on each side of the body a lateral longitudinal vascular trunk. 



The sperm-sacs of this genus are very unusual in their arrangement, being quite 

 unique in this family and rare elsewhere. They lie in segments ix and xii, the 

 intervening segments being filled with sperm unenclosed in any membrane. The 

 anterior pair of sacs — both are racemose in character — are attached to the hinder 

 wall of their segment ; the posterior pair to the front wall of the twelfth segment. 

 The ovaries are joined across the middle line. Michaelsen (16) is of opinion that 

 this worm is really an Ocnerodrilus in which the spermiducal glands have disappeared. 



Ilyogenia africana, Beddard. 



I. africana, Beddakd, P. Z. S., 1892, p. 703. 



Definition. Length, about 1 in. Skin unpigmented. Septal glands in segments IF-VII. 

 Intestine begins in XII. Hab. — Durban, Natal. -^■ 



Genus Tykonus, Michaelsen. 



Syii. Anteus, Michaelsen (in part.). 



Definition. Setae on anterior segments defective. Clitellum, XIV (XV)-XXIV 

 (XXVl). Male pore on XIX/XX, or XX. Sperm-sacs, one pair only. 



As already stated, I include in the genus one species referred by Michaelsen 

 to the genus Anieus, as well as Tykonus grandis. The distinctive characters of the 

 genus appear to me to be two. In the first place, the setae are defective upon the 

 anterior segments, as in not a few other Geoscolicids ; the actual segment upon 

 which they commence difiers in the different species, and very possibly varies in 

 individuals. The spermiducal gland of T. grandis is peculiar to itself. These characters 

 are, perhaps, sufficient to distinguish the species in question generically from each other. 

 I admit that these American Geoscolicids cannot be considered yet to have found their 

 permanent position in the system. All these species have but a single pair of sperm- 

 sacs, which is the second distinctive character of the genus. 



(i) Tykonus grandis, Michaelsen. 



T. grandis, Michaelsen, Arch. f. Nat., 1892, p. ai2. 



Definition. Length, 300 mm. ; breadth, 10 mm. ; number of segments, 320. Setae paired, 

 ornamented ; ventral setae begin with segment XIII, dorsal with XXVL Nephridiopores, 



