37 
length-direction of the body. Thus a kind of invagination is the 
result and two long lateral diverticula project forwards. The entrance 
of the duet into the vesicle is consequently at a short distance 
from the posterior wall of the vesicle. 
In Discosiylochus one may expect the proximal end of the vagina 
to retain a greater distance from the posterior margin of the body, 
as the ductus genito-intestinalis has brought about a connection 
with the digestive system. 
In Idioplanoides, where the genital pores lie nearer the posterior 
margin than in Idioplana, we also find that Lang’s glandular vesicle 
has the same horse-shoe-shape as Ihat in Limnostylochus. 
The backward move of the female apparatus in Cryptophallus 
has already been mentioned; moreover the development of a ductus 
vaginalis does not present any obstacles to it. The most marked 
caudal location of the female genital pore within Group II was, as 
mentioned, in Limnostylochus, and this has been brought about 
solely through considerable extension of the vevitral limb of the 
vagina, an extension similar to that in Meixneria in Group I. The 
mile genital apparatus in Limnostylochus has also approached the 
posterior margin of the body. 
Thus we have also in Group II several representatives for a 
noticeable move of the female genital pore in a caudal direction 
even if it is not so strongly accentuated as in Group I. inereased 
knowledge of Stylochidae will certainly furnish additional examples. 
The genital organs of Discostylochus. 
The ovaries and testes have their normal location, dorsal and 
ventral respectively. The large seminal canals do not fuse caudally 
to the female genital apparatus. Each seminal canal, filled with large 
masses of sperma, runs its usual winding course to a very muscu- 
lar „false vesicula seminalis“, which it enters on its lateral side. 
Both pear-shaped vesicles (text-fig. 12) are in the zone immediately 
back of the pharyngeal pocket, at a distance of about twice the 
diameter of the vesicula seminalis from each other. The muscular 
Wall consists of a maze of interlaced muscular fibres (Plate II, Fig. 3). 
These are not, as is usually the case, gathered in bunches, but each 
fibre runs separately. To compensate for this the muscular fibre 
becomes quite thick, even as mueh as 6 and contains numerous 
