102 A. OKA. 



of the body-wall when tlie polypide is retracted. Thus the ahmen - 

 tary canal is attached to the body- wall at four points, viz. the mouth, 

 the anus, the fnniculus nnd tlie above mentioned mesentery. 



At the entrance of the stomach there is as already mentioned 

 a funnel shaped valve, with the free end pointing into the cavity of 

 the stomach (tig. 11, PI. XVIIL). It consists of a fnnnol-like pro- 

 longation of the basement memljrane, on the oesophageal side of 

 which are arranged the characteristic cells of the œsopliagus, and 

 on the gastric side, the pyramidal cells of the stomach. This valve, 

 whose length is about 0.2 mm., prevents the passage of food from the 

 stomach back into the œsophagus. 



The stomach is a spacious saccular orgnn whose long axis is 

 bent in the sha[)e of V. bi'inging the pyloric opening nenr the cardiac. 

 It measures 2 mm. in length, and 0.6 mm. in breadth at the widest 

 part. The inequality of the length of the arms of Y brings the 

 cardiac opening about 0.5 mm. nearer the free end of the polypide 

 than the pyloric. 



The inner layer of the stomach has two kinds of cells ; the long 

 club-like cells (fig. 13, I'l. XVIII. cL c.) and the short pyramidal 

 cells (pill'. ('.). As they are arranged in gr(3Ups forming alternate 

 longitudinal rows, the lumen of tlie stomnch is stellate in cross- 

 section. The number of the rows of each kind is generally twelve 

 or more (hg. 12, PI. XVIIL). In both, the nuclei lie at the base and 

 the nncK'oli are distinctly visible. The l<:>ng club-like cells do not 

 shiin well, while the short pyramidal cells freely take up the coloring- 

 matter. In the fresh state, the longer cells contain a yellowish brown 

 fluid and the shorter cells are of a light yellowish color, so tliat the 

 stomach appears longitudinally striped with yellow and brown 

 bands. As the alimentary canal has no distinct glandular appendage, 

 the brown fluid contained in the longer cells probably performs the 



