BIHANG TILL K. SV. VET.-AKAD. HANDLE. BAND. 56 N:0O 16. 21 
with the atrium at all, but ends somewhere above the penis- 
sheath, and forms here a funnel-shaped interior opening, 
through which the eggs must enter. 
Referrimg agaim to Tubifex Bonneti Pl. 2. 1. ce. we find 
this species much more correctly drawn, and in perfect ana- 
logy with L. Udekemianus and L. Hoffmeisteri. 
The atrium is here seen not to coalesce with the copula- 
tive sheaths, but entering the penis-sheath, fig. 4 f., the 
upper end of which is not figured. The oviduct seems to 
be double, the interior one having its opening at 1., and the 
exterior one somewhere above b. on the same figure. The 
exterior openings of both are plainly visible in the figure. 
The interior opening of the interior oviduct is seen at b' fig. 
3, but the interior opening of the exterior oviduct a is not 
figured here. We have here however the sheaths repre- 
sented and figured very much as I think they must be. 
It is most likely that CLAPAREDE first studied the spe- 
cies of Limnodrilus and afterwards in studying Tubifex dis- 
covered the true nature of the copulative organs. In his 
descriptions however he states as his opinion that the ova 
enter somewhere in the neighbourhood of the insertion of 
the prostata gland. But if they should enter here they cer- 
tainly would arrive directly into the penis sheath, and not in 
the oviduct. 
Camptodrilus n. gen. 
The cephalic ganglion is emargimated both in front and 
behind. The copulative organs are much elongated and 
entirely surrounded by numerous spiral muscles, one end of 
which are attached to the exterior oviduct, the other to the 
interior surface of the body-wall, near to the genital porus. 
In other respects the genus resembles Limnodrilus; but 
as a general rule it can be said that the copulative organs 
of this genus are longer and narrower than those of the 
preceding or any other genus of the family. Only forked 
spines are presents. 
From all other genera Camptodrilus is well distinguished, 
from most of them in having only forked spines, and from 
Limnodrilus by the peculiar spiral muscles round the copula- 
tive organs. In most species the said muscles are very strong 
