Two more diagrams, Figs. 33 and 34, are added in order to give a more complete understanding of a gastric ostium and its neighboring structures, the mesogonial pocket and the valve. Fig. 33 is a view of the gastric ostium and valve from the stomach side, and represents the appearance that would be given by a thick section through the arrow _x-y_ in Fig. 32, in a plane at right angles to the paper. The heavy lines outlining the gastric ostium (_enr_ and _enfl_) represent the place where the plane of the section has cut across the epithelium of the roof of the stomach above the ostium and the epithelium of the floor of the pocket-like depression internal to the valve. The continuation of the two heavy lines in either side of the ostium represents the region where the roof and floor of the stomach meet; _i. e._, the edge of the lens-shaped stomach. The semilunar outline of the valve (_vg_) is shown by a light line just above the epithelium of the depression. As is seen by the reference arrow in Fig. 32, the valve lies a little external to the immediate plane of the section, and hence it is that its inner surface is seen in Fig. 33 and not a section of it. The vertical part of the suspensorium (_su_) is seen in section below the epithelium of the depression. The reference numbers 1, 2, 3 and 4 denote the same points in Figs. 32 and 33. Fig. 32 referred to Fig. 33 would lie in a plane at right angles to the paper through the reference arrow _x-v_ of the latter figure. Fig. 34 represents a horizontal section through the gastric ostium at the level of the arrow _a-b_ in Fig. 32, or arrow _c-d_ in Fig. 33. The reference numbers 5, 6 and 7, 8 denote similar points in the two figures 33 and 34. Fig. 32 as referred to Fig. 34 is through the arrow _e-f_; Fig. 33 is through the arrow _c-d_. In the series of cross-sections, Fig. 9 is taken at a level a little below that of Fig. 34, and passes through the basal part of the valve (_vg_).