F. S. CONANT ON THE CUBOMEDUS^E. 31 



the two are not differentiated. In a section through the region of a per- 

 radius (Fig. 4 or 19) the horizontal lamella is of course not cut, since the 

 section passes through the gastric ostium, whose existence is conditional 

 upon fusion not having taken place between the endodermal surfaces. 



The first figure in each of the series of cross-sections (Figs. 6 and 21) 

 also shows the horizontal vascular lamella, cut across slantingly twice in 

 each quadrant as it passes between the gelatine of the ex- and of the sub- 

 umbrella to connect the epithelium of the stomach with that of the 

 stomach pocket. The fact that more of the lamella does not appear in 

 such a cross-section only shows that its course is not perfectly horizontal. 



The region in which the same lamella lies is indicated in the surface 

 view of the top of the bell of Charybdea (Fig. 2) by the bent line hvl in 

 each quadrant. The figure manifests the appropriateness of Claus's 

 name for the horizontal lamella " bogenformige Verwachsungs- 

 Streifen." Haeckel calls the same structures " Pylorus-Klappen," and in 

 his account of Charybdea Murrayana in the Challenger Report, speaking 

 of the three divisions of the stomach (buccal, central and basal) which he 

 traces upwards from the stalked forms of Scyphomedusae, he says: "The 

 central stomach in this Charybdea, as in most Charybdea, is joined to 

 the basal stomach, as the pyloric stricture between the two is not devel- 

 oped and only faintly indicated by the slightly projecting pyloric valves." 

 Again, in speaking of the valves of the gastric ostia, he says : " These 

 four perradial 'pouch valves' alternate with the interradial pyloric 

 valves." It is difficult to understand, however, how the " bogenformige 

 Verwachsungs-Streif en " of Glaus, which are undoubtedly the same struc- 

 tures as those which I have called the horizontal lamellae, and are only 

 strips of endodermal fusion, can be " projecting pyloric valves," or indeed 

 can properly be spoken of as valves at all. Possibly Haeckel was not 

 quite able to understand Claus's description, and in his desire to find 

 something in the stomach of Charybdea which would serve to set off a 

 central from a basal part, such as is found in the Lucernaridse, hit upon 

 Claus's " Verwachsungs-Streifen." I have elsewhere given it as my 

 opinion that in such of the Cubomedusse as I have studied there is no 

 structure in evidence that would properly serve to mark a limit between 

 a basal and a central portion of the stomach. 



We have next to describe the marginal system. The vascular 

 lamellae mentioned above in every case connected endoderm of one 

 cavity with endoderm of another ; those of the margin have the note- 

 worthy difference that they run from endoderms of some part of the 



