98 THE VOYAGE OF H.M.S. CHALLENGER. 



spirit specimen and appear thickly frilled at the margins, are probably capable of greater 

 expansion in the living animal. 



The central stomach in this Charybdea, as in most Charybdeidse, is joined to the 

 basal stomach, as the pyloric stricture between the two is not developed and only faintly 

 indicated by the slightly projecting pyloric valves. These two divisions of the stomach 

 therefore compose a wide, but very flat pouch, or a low chamber, quadratic in outline. 

 Its bottom or lower wall represents the thin quadrate plate, which at the same time forms 

 the fundus of the cubic umbrella cavity. This muscular plate is pierced in the middle of 

 the palatine opening, from whose four perradial corners the gastral grooves already men- 

 tioned (figs. 4, 6, gs), run to the middle of the four gastral openings. The horizontal cover 

 of the low gastral chamber or its upper wall is formed by the smooth endodermal surface 

 of the cap-shaped umbrella apex (figs. 2, 3, git). The four interradial corners are occupied 

 by the four pyloric valves, the narrow " bow-shaped fused lines " (Glaus), which are placed 

 perpendicularly at the proximal ends of the long septal selvages. On the other hand, the 

 four perradial side walls of the chamber between the selvages are represented by the four 

 gastral openings (fig. 6, go), four narrow horizontal clefts, which lead from the stomach 

 into the four radial pouches. We find here a complicated arrangement of valves, by 

 means of which the stomach can be completely shut off for a time from the radial pouches, 

 These four perradial " pouch- valves " alternate with the interradial pyloric valves (gy). 

 Above each pyloric valve the stomach forms a peculiar evagination in the form of a low 

 triangular pouch, and the phacelli or dendritic bunches of gastral filaments (b) are placed 

 in this pyloric pouch. 



The gastral filaments (fig. 7,f), are much more strongly developed in Charybdea 

 ■murrayana than in the closely-allied Charybdea marsupialis; in each of the four inter- 

 radial corners i if the stomach they form a visible phacellus or bush, composed of ten to 

 twelve larger and several smaller branches. The stems of these branches are connected 

 below at the root, where they rise from the aboral surface of the subumbral pyloric valve, 

 and so actually represent the principal branches of a single, very short, powerful stem, a 

 primary interradial primitive filament. The lower (distal) half of each branch consists of 

 a strong, simple, or bifurcate stem, the upper (proximal) half of a pencil-shaped bunch of 

 numerous branches, which are partly simple, partly dichotomised (figs. 9, 10). The solid 

 axis of the filaments is formed by a thick cylindrical or flat ribbon-like gelatinous filament 

 (a process of the supporting plate of the subumbrella) ; its endodermal epithelium is mostly 

 composed of gland cells, having many flagellate cells at the base and urtricating cells at 

 the point. 



The four broad quadrangular radial pouches (figs. 2-6, bp), occupy the greater 

 part of the subumbrella, and are only separated from each other by four narrow inter- 

 radial septal selvages (Jcs). These correspond to the septal nodes of the Tesseridae and 

 Peromedusae, and to the septal selvages of the Lucernaridse ; and, like the latter, have 



