W. H. Leigpi-Sharpe 
211 
from it by a cavity which stands in communication with the ventral 
sinus. It stretches to the posterior sucker situated on the ventral side 
of the stomach and caecum. It includes the ventral ganglion chain 
in all its length. The hinder ganglia are surrounded by a separate part 
of the body cavity separated from the ventral sinus by a septum. In this 
genus it includes the ventral blood vessel. In the clitellum it is narrow, 
but in open communication with a cavity which includes the male and 
female ducts, and which is constricted between the ganglia. 
Reproductive System. The generative organs are situated at the base 
of the neck in the middle of which the opening of the oviduct is situated 
between the 2nd and 3rd clitellar segments or towards the anterior 
border of the 3rd, while the male genital aperture is between the 1st and 
2nd clitellar segments, or towards the anterior border of the 2nd. 
The male reproductive organs consist of metameric testes and efferent 
ducts, situated in the first six segments of the abdomen. Van Beneden 
and Hesse were uncertain in another species as to whether there were 
seven or eight pairs of testes, but apparently they counted the ovaries 
in their reckoning, for in common with all the Ichthyobdellida (with the 
exception of Abranchus) there are but six pairs of testes. 
From each testis, as is usual, proceeds a small duct, the vas efferens ; 
there being as many vasa efferentia as there are testes. From the 
posterior testis on each side the vas efierens passes immediately into 
the vas deferens which in its course receives the remaining vasa efferentia. 
The vasa deferentia are in the testis region very fine tubes little or no 
larger than the vasa efferentia, but have a larger lumen. Only after 
taking up the most anterior vas efferens each vas deferens becomes 
a little larger. In the posterior part of the clitellum it takes on many 
curves and sinuosities, as it does also slightly to some extent in Piscicola, 
while in most genera it is perfectly straight. It gradually gets a covering 
of more and more powerful circular muscles. The borders of the 
epithelial cells are always very obscure, while the nuclei are very con¬ 
spicuous. About the male genital aperture the vasa deferentia suddenly 
widen out and open into the ductus ejaculatorii. 
The ductus ejaculatorii stretch forward to the anterior border of 
the clitellum, after which they bend towards the ventral side and 
posteriorly in order to unite with one another in the middle line in 
front of the female genital opening. The common terminal portion 
turns a considerable way backwards and opens only a little anterior to 
the female opening into the bursa ; in the other genera this common 
terminal portion does not stretch so far backwards but opens very 
