24 GILBERT C. BOURNE. 



pheral continuations of the mesenteries, as has been described 

 for other forms by von Koch, Fowler, and others. Fig. 4 

 shows that the " Randplatte " extends downwards considerably 

 farther than do the soft tissues within the calyx. There can 

 be no question that the " Randplatte " is a distinct structure 

 in these forms. 



As decalcification proceeds it becomes obvious that the 

 corallum lies wholly external to the polyp, being, as it were, 

 dovetailed into it from below ; or, to use another illustration, 

 the polyp appears to be drawn over the corallum much as a 

 glove is drawn over the hand. After decalcification, the intra- 

 calicular soft tissues appear to be divided up into wedges by 

 the spaces previously occupied by the septa. 



Examination of the internal structure shows that it is of the 

 normal Actinian type except in one important point, there are 

 no directive mesenteries, the longitudinal muscles of each pair 

 of mesenteries being placed vis a, vis. This character, which 

 has already been discovered by Fowler in Lophohelia, is also 

 characteristic of Euphyllia, as will be seen later on. The 

 arrangement of the mesenteries and their relations to the septa 

 are shown in fig. 5. Each pair of mesenteries embraces a 

 septum, all the septa are entocoelic, no septa occurring between 

 pairs of mesenteries. The mesenteries embracing the prin- 

 cipal septa are all inserted on the stomodseum, which is of 

 moderate length ; the mesenteries embracing the secondary 

 septa are free throughout their extent. All the mesenteries 

 bear well-developed filaments on their free edges, and below 

 the stomodseum their edges are drawn out in long, sinuous, 

 ribbon-shaped prolongations, around the whole edge of which 

 the filament is continued, the whole structure being coiled up 

 to one side of the mesentery in an exocoelic or entocoelic space. 

 To such coiled filaments I erroneously gave the name of 

 Acontia in my paper on Fungia, but I have since satisfied 

 myself that they differ essentially from Acontia as defined by 

 Gosse and the Hertwigs. Since the septa are all entocoelic 

 the number of pairs of mesenteries is the same as the number 

 of septa, and therefore not necessarily a multiple of six. 



