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



lower boundary surface of the basal stomach, whose upper surface is formed by the 

 horizontal, almost level, endodermal surface of the central gelatinous disc of the umbrella 

 (fig. 14, ng). 



The four septal nodes ("nodi cathammales," fig. 3, kn; fig. 14, kn) are four 

 interradial, small but firm nodules, hard as cartilage, in which the suburnbral gastral 

 wall is firmly fused with the umbral. Four broad horizontal clefts remain between 

 the nodes, the four perradial gastral openings, by which the central stomach 

 communicates with the peripheric coronal intestine. These important conditions of 

 organisation correspond clearly to those of the Tesseroniae. The four important 

 interradial cathammal nodes especially, as well as the ring sinus lying beneath them, 

 are homologous with those of the Peromedusae ; whilst on the other hand the condition 

 of the four interradial tongue-shaped pyloric valves shows a special homology with 

 many Cubomedusas. In most other Disconiedusse (certainly in all Semostomce and 

 Rhizostomce) these Tesseronia-like formations have disappeared, as the septal nodes 

 and the pyloric valves have undergone retrograde formation. 



The gastral filaments (PI. XXVIII. fig. 18) are not very numerous, but com- 

 paratively large and thick. They are four arched interradial phacellae, whose convex 

 margin corresponds to the free margin of the tongue-shaped pyloric valve (gi). Each 

 crescentic phacella consists of a single row of from twenty to twenty -four gastral 

 filaments, placed closely near each other. They are cylindrical, and decrease in length 

 from the middle of the phacella towards the two ends, the longest one nearly one- 

 third as long as the radius of the umbrella. 



The peripheric coronal intestine (" gaster coronaris ") extends from the horizontal 

 cathammal plane of the four septal nodes (which lies a little above the exumbral 

 coronal furrow), to the umbrella margin and consists of the following three coronal or 

 horizontal sections : A, a proximal or upper corona of four perradial gastral pouches ; 

 B, a middle corona of sixteen coronal pouches ; and C, a distant or lower corona of 

 thirty-two marginal lobe pouches. On closer examination we can even distinguish 

 five different sections of the coronal intestine, as there is also a special coronal sinus 

 (cs) between the four perradial principal pouches and the sixteen coronal pouches, and 

 below it an intercalary corona of eight pouches (fig. 4). Compare the transverse section 

 (figs. 2-10) and the longitudinal section (figs. 14, 15). 



The four broad radial pouches, or perradial gastral pouches (fig. 4), which belong 

 to all Tesseronia, are undeniably also present here, or are at least represented by the 

 four gastral openings or broad cleft spaces between the four interradial septal nodes 

 (kn). We may also include with these the circular hollow space below the septal nodes, 

 between them and the proximal margin of the coronal pouches, unless we prefer to 

 compare this hollow space to a special coronal sinus (cs, fig. 14), Hke that of 

 the Peromedusaj ("sinus coronaris," p. 79, PL XXL, cs). In fact the conditions here 



