344 
Entozoa oj Fishes 
The alimentary system is of a unique type. There is a distinct 
though short prepharynx. Its length is usually about a third of the 
length of the pharynx. Frequently it is less and occasionally it is 
nearly as long as the pharynx. I have never observed a specimen in 
which it was three times as long as the pharynx, as noted by Miss Lebour. 
This could only occur when the animal was alive and the anterior end 
in a state of hyper-extension. In this respect Stossich’s figure shows 
the normal state. The pharynx is rather small but very muscular. It 
measures 0445 x 0405 mm. and is usually thickest at its posterior end. 
The oesophagus, though apparently of great length, is in reality very 
short. What has hitherto been described as the oesophagus, is, as first 
noted by Odhner (1901, p. 338), not a true oesophagus, but is actually 
the initial parts of the intestinal diverticula fused together. It is lined 
with ciliated epithelium continuous with that of the gut. The intestinal 
bifurcation, therefore, takes place actually in the intestine and not at 
the junction of the oesophagus with the diverticula. The whole of the 
tract between the pharynx and the bifurcation, however, is not of the 
same nature for there is a short oesophagus with the usual structure 
and not lined with intestinal epithelium. This comprises about 4-th of 
the total length from the pharynx to the bifurcation, which is 0 - 39 mm. 
The oesophagus therefore measures on an average 0'055 mm. and is 
thus about the same length as the prepharynx. The pseudo-oesophagus, 
as it has been termed by Odhner, is capable of considerable dilatation. 
The diverticula are of normal structure and extend quite to the 
posterior end of the body. 
A converse type has already been described (Nicoll, 1909 a, p. 407) 
in the case of Stephanophiala laureata (Zed.) and some allied species, 
in which the intestinal bifurcation takes place actually in the oesophagus, 
so that the initial parts of the diverticula are morphologically portions 
of the oesophagus. 
The excretory vesicle, described by Miss Lebour as extremely small, 
is on the contrary of great size. It is a long narrow sac stretching from 
the posterior end to well in front of the intestinal bifurcation. As far 
as can be made out, however, it is not invariably as large as this and it 
appears to be capable of a certain amount of contraction. An even 
larger excretory vesicle is met with in the allied genus Lepocreadmvi. 
In living specimens the main excretory tubules are very conspicuous 
especially in the neck. They are highly convoluted. 
The testes are situated in the posterior third of the body, always 
directly behind each other. They are frequently contiguous, but never 
