H. S. Pratt 
231 
They are all of approximately the same length and are strikingly regular 
in form and outline. They have thus the appearance of large cilia, 
and might easily be taken for such. 
In other portions of the intestine of this worm, especially toward 
the hinder end of the body, and throughout the entire gut of the other 
two worms examined, the intestinal epithelial cells lack the regular 
form of those just described, although they also possess similar long 
protoplasmic filaments. Their free surfaces show a tendency to throw 
large blunt extensions into the lumen of the intestine, which have the 
appearance of the pseudopodia of rhizopods and give these surfaces a 
most irregular contour. From these extensions as well as from the 
free surface of the cells generally the cilia-like structures project still 
further into the lumen of the intestine. They are however relatively 
much shorter than the corresponding structures shown in Figure 4, 
being not more than a third or half the length of the cells from which 
they spring. 
The structure of the intestinal epithelial cells here described has 
been observed by other authors in a variety of trematodes. It was 
first described by Sommer (1880) in Fasciola hepatica. The explanations 
given by him of the cause of this formation is that the free ends of these 
cells become amoeboid in order to more quickly and easily digest the 
blood which has been ingested and forms the food of the parasite. 
A similar explanation may also serve for the same structures in Stephano- 
chasmus, as the capacious intestinal trunks are usually filled with blood. 
I could not, however, find a correlation, as Sommer does in the intestine 
of Fasciola, between the amount of blood in the intestine and the 
actual form and conditions of its epithelial cells. Sommer finds that 
where the intestine is empty its epithelial cells are relatively low and 
simple in contour; and only in those parts of the intestine which are 
well filled with blood are the epithelial cells high and irregular in 
contour. In Stephanochasmus casus the intestine as observed always 
contained blood whatever the condition of the epithelium. 
The musculature of the long prepharynx is a powerful one, con¬ 
sisting of regular circular and longitudinal fibres. On the intestinal 
trunks, on the other hand, the musculature is apparently absent, or 
at least is exceedingly delicate: it could not be demonstrated with 
certainty. 
The excretory pore (Fig. 1, 15) is at the hinder end of the broad 
papilla which forms the posterior end of the body. The excretory 
vesicle (16) consists of a long median trunk and two long paired trunks 
15—2 
