234 Dr. F. E. Beddaid on the Genus Trichodrilus. 



would appear, therefore, that the presence of a muscular 

 layer is of some systematic imj)ortance in Trichodrilus. There 

 is, however, undoubtedly, in the latter at least, no such thick 

 layer of longitudinal fibres as Hesse has figured * in Lum- 

 bricuhis. I have been unable to see any longitudinal layer at 

 all, nor is it shown in Ditlevsen's figure ; but if there be 

 one present, it can hardly consist of more than a single layer 

 of fibres. The figures of Hesse are borne out by those of 

 Mrazek f. 



The oviducts were not seen by Clapar^de, who located 

 them as probably lying in segment IX. , by reason of the fact 

 that this segment contained (as he thought) no nephridium, 

 its place, on the older theory of the correspondence between 

 nephridia and gonad ducts, being taken by the oviduct. As 

 a matter of fact, the ninth segment in the species described 

 here does contain a part of the anterior complex nephridium. 

 The oviduct, as might be expected, opens into segment XI., 

 and opens on to the exterior between this segment and the 

 following one. Its outline is not that of a funnel with a very 

 short stalk, as this organ is apt to be depicted ; in longitudinal 

 section it has the outline of a lyre, the edges above being 

 recurved and the cavity widest some way below this edge, 

 which is the actual funnel. The duct narrows. 



The above account of this worm may be summed up as 

 follows: — Length 25 mm. and upwards ; diameter '5 mm. or 

 less. A thin, slender, and active worm. Prostomium 

 conical, with no special tentacle-like prolongation at apex, in 

 length rather greater than breadth of first segment. Colour 

 golden-yellow. Setae slender and simply pointed ; closely 

 paired, rarely with reserve setae. No vascular appendages of 

 dorsal vessel ; intestine surrounded by sinus, and not network 

 of blood-vessels. Chloragogen layer of intestine begins in VI. 

 First pair of nepliridia lie in segments VII.-X. iiiclusive, open 

 on to VII. with funnel in VI. ; no nephridia in XI., but occur 

 in XII. and onwards. Nephridia forming coils several tubules 

 wide. Testes in IX., X. ; funnels of vasa deferentia in IX. and 

 X. ; atrium with tliick muscular walls of circularly running 

 fibres, lined by an epithelium of small cells and covered by large 

 pear-shaped cells externally; narrows into a muscular duct 

 which projects into external depression at orifice on X. Sperm- 

 sacs in VIII.-XII., those of first pair rising from septum Vili./lX., 

 and thus directed forwards. Ovaries in XI. Oviducts with 

 long dilated tube opening on to xi./xil. Egg-sacs from XIII. 

 or XIV. to third segment or more (?) from this. 



* Loc. cit. Taf. xxii. fig. 4. 



t Loc. cit., several woodcuts on pp. 431, 432, 433, 435, &c. 



