62 



THE SCYPHOMEDUSAE 



(Tessera), to which eight adradial (Tesserantha) or even more may 

 be added ; or else (2) is divided by incisions into eight hollow 

 adradial lappets ; on each lappet is seated a bunch of capitate 

 tentacles, and between the lappets lie perradial and interradial 

 marginal anchors or colletocystophores (Haliclystus, Fig. 3), which 

 are, however, absent in some genera (Lucernaria). The marginal 

 anchors are modified and shortened tentacles, at the base of each 



cc~ 



FIG. 2. 



Diagrams illustrating the structure of Lucernaria. 1, longitudinal section ; the right 

 half passes along an adradius, just missing a mesentery, which is shown in thin outline 

 and carries gastric filaments and generative organs ; the left half passes along an interradius 

 and shows the course of a subumbral pit deep into the substance of the mesentery. 2, transverse 

 section ; the right half at the level of the stqinodaeum, the left half a little below that level, 

 and through the upper part of the subumbral pits. 3, transverse section ; the right half through 

 the lower part of the subumbral pits, the left half through the base of the animal where the four 

 mesenteries fuse, centrally dividing the coelenteron into four pouches. In all three figures ecto- 

 derm is strongly hatched, endoderm lightly hatched, mesogloea black. C, coelenteron ; CC, 

 circular canal ; G, genital organ ; GF, gastric filament ; /, interradius ; LM, ectodermal longi- 

 tudinal muscle band, continued aborally into the mesogloea ; M, mesentery ; P, perradius ; JSP, 

 subumbral pit ; ST, stomodaeum. 



lies a pad of nematocysts and adhesive cells. No organs of 

 special sense are developed in this group. 



The mouth, which is often frilled, leads into a tube, which is 

 probably a stomodaeum, or invagination of ectoderm. At the bottom 

 of the stomodaeum lies the gastric cavity, which is imperfectly 

 divided into four perradial chambers, homologous with the perradial 

 canals of Hydromedusae, by four interradial mesenteries or partitions 



