ANATOMY OF NEOHELIA PORCELLANA (mOSELEY). 595 



The species is probably monoecious, our specimen being a male colony. 



Polyp. On measuring several polyps after the hard parts had been removed by 

 decalciticatiou, they were found to be 1*75 — IS mm. from top to bottom, and 1 — Vo mm. 

 in diameter. The polyps are closed at the base, and their coelentera are connected 

 by the system of canals which lie in the coeuosarc. There are no zooxanthellae 

 present in the tissues of this coral ; in this respect Neohelia resembles Coenop- 

 sammia (24). 



Tentacles. The tentacles, twenty in number, are arranged in a single ring round the 

 periphery of the mouth disc, and correspond in position with the septa (Fig. 3). There 

 are five primary, five secondary and ten tertiary tentacles. They are all simple, short 

 and thick, many of them are bent over towards the mouth, while some of them are 

 partially invaginated, it is possible that they can be wholly invaginated. The nemato- 

 cysts, "02 mm. in length when unexploded, are of the common Actinian tj'pe, and are 

 more or less uniformly distributed over the surface of the tentacles in a manner 

 similai- to that described by Fowler in Turhinaria (12); they are perhaps more numerous 

 at the tip, but they are not arranged in knobs or batteries as in Lophohelia, 

 Amphihelia, Madracis, etc. Gland cells are numerous between the ncmatocysts and 

 interstitial cells which compose the free edge of a tentacle. 



The Mouth Disc contains numerous large nucleated gland cells (Fig. 10). On 

 staining witii iron haematoxylin, some of the cells are seen to be filled with a deeply- 

 staining, hduiogeneous substance resembling mucous. In others the deeply-staining 

 substance forms a reticulum, while in a few cases the cells seem to be tilled with 

 a granular substance (Fig. 10 Gl). Nematocysts like those in the tentacles are numerous 

 on the mouth disc. 



The Mouth is oval in cross section, with one large siphonoglyph and one small 

 one. 



The walls of the Stomodaeum are nmch convoluted, probably due to contraction, 

 the Ectoderm, the histology of which could not be made out, is separated by a con- 

 siderable space from the Endoderm and Mesogloea ; this is probably due to the same 

 cause. 



Mesenteries. There are twenty mesenteries arranged in three cycles, five 

 primary, tive secondary, and ten tertiary mesenteries. Only the primary and secondary 

 mesenteries support the stomodaeum, the tertiary mesenteries extend only for a very 

 short distance into the body cavity. There are two pairs of directive mesenteries. The 

 ten principal mesenteries bear mesenterial filaments and acontia. Any of these mesen- 

 teries may bear generative organs, in one case they are borne on the directives. In 

 most of the polyps I have examined only one or two of the mesenteries bear gene- 

 rative organs, but in a few cases they occur in five or six of the principal mesenteries 

 in a polyp. The tertiary mesenteries have no mesenterial filaments or acontia, and 

 they do not bear generative organs. 



Upon examination with iiigh powers of .sections staimcl with burax carniiin' I have 

 seen at th(! insertion of the mesenteries certain structures similar to those described 



w. V. 79 



