STUDIES OX THE ECTOPARASITIC TREMATODES OF JAPAN. 57 



I have staclied, it is very short or ahnest entirely wanting. Its 

 internal surface presents just the same aspect as that of the intestine, 

 and tlierefjre will he described with that. In Monocotijle, Calicotijle, 

 and TrUtouium^ (and pro1)ahly also in Epibdella) numerous unicellular 

 glands open into the oesophagus at its very beginning (PI. XX, fig. 

 -S; n. XXI, fig. 1; ri. XXIV, %. 12 ; PI. XXV, fig. 7; ?1. 

 XXIir, fig. 4; PI. XVIII, fig. 5; PI. XIX, fig. 8), which have 

 been called the salivanj (jhimh. In Monocotijle and CaUcotyle, they are 

 situated close around the oesophagus, and in the former also a little 

 behind it (PI. XVIII, fig. 5 ; Pi. XIX, fig. 8). In Tristomum, how- 

 ever, they are situated cjuite in the lateral portion of the body on the 

 dorsal side, and are connected with the oesopliagus l)y long ducts (PI. 

 XX, fig. 8). The cells present somewhat different aspects (PI. 

 XX, fig. 9 ; PI. XVIII, fig. 5) ; they stain well, but in some the 

 cell-body is comparatively finely granular, and the oval, vesicular 

 nucleus encloses in its centre a single, well staining nucleolus, while 

 in others the cell-body is more coarsely granular and the large, round, 

 vesicular nucleus usually encloses a few small nucleoli besides the 

 large one, all <3f which stain more weakly than in the first class 

 of cells. Cells of the first class also stain more deeply than those 

 of the second. These differences are no doubt due to the different 

 stages of secretory activity ; for, intermediate forms of all degrees 

 ;ire also present. 



In Tristomum, the oesopliagus is separated from the intestine 

 by valve-like projections of the surrounding tissue into the cavity 

 of the alimentary canal in which sphincter muscular fibres are 

 present. (PL XXI, fig. 1 ; PI. XXIV, fig. \2 ; PI. XXV, fig. 7 ; 

 Pi. XXIII, fig. 4). 



In Microcotijlc, Axine, Octocofijle, Dld'uloplwra, Hexacotijle, and 

 Oncliocotijk, the salivary glands are absent. 



