40 S. GOTO. 



sucker, on the ventral side, where the basement membrane is some- 

 Avhat indistinct ; but they probably open also on the whole ventral 

 surface, although I can not make a positive statement to that effect 

 (Pi. XX, fig. 10). In Epibchlla, on the other hand, the glands open 

 on the whole ventral surface of the anterior sucker. Here, however, 

 it should be remarked that in most' cases I have not been able to 

 follow the neck of the gland-cells thrmigh the investing membrane of 

 the body to the external surface, but only up to the basement mem- 

 brane. In T. ovale, on the other hand, the opening of the glands are 

 distinctly seen at the top of most of the conical papillae already men- 

 tioned. This leads me to suppose that the ducts of the glands 

 through the investing membrane is usually entirely collapsed, being 

 open only during the actual passage of the secretion. It also leads 

 me to suspect whether Brandes'^ has not mistaken these glands for 

 his " subcuticular glands." 



In two species of Tristomum, viz. T. sinuatum and T. hiparasiticum, 

 there is, as before mentioned, a series of groups of peculiar unicellular 

 glands opening at intervals along the lateral margin of the body. 

 The series begins near the anterior end of the body, and terminates 

 quite near the posterior sucker (PI. XX, fig. 1 ; PL XXV, fig. 5). In 

 T. sinuatum I have counted as many as fifty-eight on one side of the 

 body, while in T. biparasiticum there were about sixty-two. I have 

 studied the histology of these glands mainly in the former species, so 

 that the following statements refer mainly to it alone ; but the es- 

 sential features are the same in both species, the difference lying only 

 in insignificant details. 



The cells that constitute these glands are of various sizes, but are 

 more or less polyhedral in form, owing to mutual pressure. Each cell 

 has a distinct wall, and in the specimens I have examined, the greater 



1). Brandies—?, c. 



