24 
Proceedings of the Royal Society of Edinburgh. [Sess. 
I do not believe that either of these two statements is literally true as 
regards Stylodrilus. Here the nuclei of the cells immediately surrounding 
a growing ovum have a peculiarly shrunken appearance, and structures 
(PL IY. fig. 7) may sometimes be found within the plasma of the egg cells 
which seem very like the degenerate nuclei such as are figured by Obst 
in the developing egg of Helix Pomatia. 
The egg sac is single and dorsal. It begins in segment XII, and may 
extend back between the paired vesicula seminales into segment XVII. 
The oviducts are short tubes, commencing by wide funnels in segment 
XI and opening to the exterior on segment XII. 
The cocoon is a common and quite characteristic product of a deep- 
water haul in a Scottish loch. It is roughly spherical, but the two poles are 
prolonged into long tubes, through which the young worm escapes (PI. IV. 
fig. 6). 
The cocoon itself is composed of a yellow chitinous substance which is 
very resistant to chemical reagents, and can probably remain for years 
practically unchanged in the soft mud of a lake. 
The spermathecce are large globular bodies lying dorsal to the 
gut, close up against the dissepiment 8/9, and opening to the exterior 
on segment IX by thick- walled ducts. I have never been able to find 
in these forms the cystal which Claparede found in Stylodrilus 
Heringianus. 
Forel, in his description of Lake Geneva (tome iii.), observes that the 
most common oligochset from deep water is Bathynomus Lemani (Grube), 
with its cocoons. 
This genus has had a somewhat chequered history, and has always been 
a complete puzzle to the monographers of this group (Vejdovsky, Vaillant, 
Beddard). It was first described (without figures) by Grube in the 
Jahresbericht der Schlesischen Gesellschaft fur Vaterlandische Gultur 
(1878). 
In this paper Grube remarks that of the six genera given by Forel as 
characteristic inhabitants of the deep water of Lake Geneva, he could only 
distinguish three, viz. a Tubifex, Ssenuris, and a third, Bathynomus Lemani. 
It is rather interesting to note that the two former genera are constantly 
found in association with Stylodrilus in the deep water of all the Scotch 
lochs I have examined. The chief points in Grube’s genus are the four 
bundles of chsetrn in each segment, which can only be recognised as bifur- 
cate under a high power. The length was about 20 mm. in immature 
spirit specimens, possessing 40-60 segments, of which the anterior 2-8 were 
very short. 
