ANEMONES 



389 



the gland cells in the oesophagus of Harenactis^ but shows no trace of 

 granules ; the contents are quite homogeneous. 



The tentacles exhibit no special features. They possess ectodermic 

 longitudinal muscles and endodermic circular muscles, neither very 

 strong. 



There are twenty-four pairs of mesenteries biradially arranged. 



(«) Six pairs, forming the first cycle, are perfect, and bear the 

 gonads and the trilobed mesenterial filaments. Two of these pairs are 

 directives. The muscles of each mesentery are concentrated into a 

 stout retractor and a parieto-basilar (fig. 18). The shape and distance 

 of the latter from the body wall differs according to the levels at which 

 sections are taken. The endoderm of the mesenteries is conspicuously 

 high in comparison with that of Harenactis. Gland cells are scat- 

 tered throvigh it, though quite absent from the parietal endoderm. 



Fig. 18. Chart'sea saxicola. Cross- 

 section of primary mesentery, in oeso- 

 phageal region. 



Fig. 19. Charisea saxicola. 

 Mesenteries of the second and third 

 cycles between contiguous pairs of 

 primaries. 



(^) Eighteen pairs are imperfect, all lacking both gonads and mes- 

 enterial filaments. Six pairs belong to the second cycle, and occupy 

 the center of the spaces between adjacent pairs of primaries. At their 

 bases their muscles are distributed equally on both faces, but near the 

 free edge they are localized in folds on the face of each mesentery 

 which is turned toward its mate (fig. 19). The remaining twelve 



Proc. Wash. Acad. Sci., August, 1902. 



