W. H. Leigh-Sharpe 
7 
for the primitive condition of a pair of widely divergent caeca obtains, 
instead of the specialized reduction to one caecum found in the other 
genus. The retention of this primitive character in so specialized a leech 
as Ganymedes may be correlated with the fact that it is a faecal feeder; 
the ingested matter having to be retained in the digestive tract for a 
longer period in order that it may be better assimilated. The caeca 
leave the stomach at the boundary of the 4th and 5th segments of the 
testis region and extend to the boundary of the 3rd and 4th segments 
of the caecum region. They appear crenated, and both caeca were full 
of contents in my specimen. The intestine is relatively long and is in 
straight continuation with the stomach, the caeca being disposed 
laterally with regard to it. 
Fig. 4. Ganymedes cratere. Digestive system in dorsal aspect; the reproductive system 
being shown on the left side only. m. mouth; ph. pharynx; st. stomach; c. caeca; 
Int. intestine; a. anus; the first and last testes of that side respectively. 
Coelom. The divisions of the body cavity are best seen from Fig. 5. 
The condition is precisely the same as in Calliobdella. There is a ventral 
sinus, a dorsal sinus, two lateral sinuses, and an intestinal sinus. The 
ventral nerve cord is within the ventral sinus. 
Reproductive system. The generative organs are situated at the base 
of the neck. The position of the genital openings on the clitellum has 
already been stated. 
The male reproductive organs consist of six pairs of metameric testes, 
situated respectively in the middle of the first six segments of the 
