W. H. Leigh-Sharpe 
209 
genus. According to Johannson the clear yellow pigment cells which 
are present in C. nodulifera (the only other species which he has examined) 
are entirely absent. They are, however, replaced by similar cells with 
brownish contents, for in section can be seen, in the inner connective 
tissues at least, large cells which in position and form are somewhat 
like the pigment cells of C. nodulifera but have a very pale grey-brown 
colour. 
Digestive system. The mouth is situated at or near the centre of 
the anterior hood-like sucker, and the anus opens on the dorsal side 
between the last and last but one of the annuli immediately preceding 
the posterior sucker. The oesophageal bulb or pharynx is very thick, 
its opening being furnished with denticulations or folds destined to 
favour contraction. The mouth can be shut so as to form a longitudinal 
slit, and its wall is the anterior sucker. The pharyngeal sheath opens 
with a fine opening at the bottom of the mouth cavity, and consists 
of a narrow tube whose lumen is either wholly or partly filled by the 
pharynx, and when the pharynx is retracted it stretches to the end of 
the first clitellar segment. Without the mouth cavity the pharyngeal 
sheath for the whole of its length is in the body cavity. Salivary glands 
are present. The stomach is the longest part of the alimentary canal; 
it is wide in the testis region and divided into chambers, the front part 
of each segment being constricted by dorsiventrally placed muscular 
septa which occur in all. These chambers increase in width backwards. 
As is usual in leeches a large caecum is present, which has in C. lophii 
always been found very empty. Very wide in other species, in this 
species on the contrary it is strongly flattened. Apparently it represents 
two caeca fused, the point of division of two original caeca being repre¬ 
sented merely by two fine tubes of which one is often obliterated. The 
whole caecum exhibits thus a shrunken aspect. The part I have called 
the intestine (Fig. 4) is the only tract in my specimens that shows any 
trace of contents. This is another argument in addition to the two 
points I have mentioned under the heading of “ Suckers ” in favour of 
the view that C. lophii is a stationary parasite, as it does not seem to 
gorge itself with food, which would be necessary for a leech which 
detaches itself, during the period of time while it was searching" for 
a new host. 
Coelom. The body cavity is divided into the five following parts ; 
a ventral sinus, a dorsal sinus, two lateral sinuses, and an intestinal 
sinus. 
The ventral sinus is the best developed. It commences at about 
