ACTINIARIA 



contains numerous mucus- and gland-cells, and nematocysts, 34 — 46 X 3,6 ft in size. The longitudinal muscles 

 are very weak and here and there absent? The ectoderm and especially the endoderm of the siphonoglyphe 

 are thickened, the gland-cells and the nematocysts of the ectoderm very sparse, the longitudinal muscles 

 very weak. The nerve-layer of the actinopharynx is rather distinct. 



The mesenteries are 20 ^ in number, namely 6 pairs of the first order and 4 pairs of the second, the 

 latter placed in the lateral and ventrolateral primary exocoels as in Pcachia and Eloactis. The four couples 

 of the first order arising after the " Edwardsia-stage" , viz. the fifth and sixth couples, are weaker than the 

 outer couples of the first cycle. All mesenteries are perfect, those of the first cycle coalesced with the actino- 

 pharynx in its whole length, the mesenteries of the second cycle are inserted upon one half of the actino- 

 pharynx. The ventral directive mesenteries are the stronger, the mesenteries of the second order the weaker. 

 The longitudinal muscle-pennons are kidney-shaped in transverse-sections through the reproductive region 

 and well Hmited from the parietal muscle, in contradistinction to what occurs in Peachia. The folds of the 

 muscles are high but few, about 10, richly ramificated even from the basis (textfig. 139 transverse-section 

 through a mesentery in the reproductive region) and all of about equal height. The figures of the mesente- 

 ries reproduced by Mc. Murrich (1892, figs. 2, 3) are of a young specimen. The lamellar part of the mesen- 

 teries issues near the outside of the pennons. The parietal muscles are well developed with low, but nume- 

 rous and ramificated folds spread over a comparatively large area of the mesenteries, whereby the folds 

 become narrow and high. The parietal muscles are not expanded upon the body-wall. The mesenterial fila- 

 ments are of the usual appearance; the ciliated streaks are narrow, the intermediate streaks provided with 

 extraordinarily numerous gland-cells. The mesogloea of the filaments contains sparse cells. Oral stomata 

 are probably absent, but marginal stomata present. They are large and irregular, and arranged with one 

 in each mesentery in about the middle line of the mesenteries, a little below the tentacles. The animal is dioe- 

 cious. The more closely examined specimen was provided with ovaria on all mesenteries. The egg-cells show 

 a fine-grained ectoplasma and a coarse-grained endoplasma. As in Pcachia and certain other Actiniaria the 

 eggs are provided with a spinous covering. A "nutrition"-apparatus is developed by distinct invaginations 

 of the endoderm extending towards the egg-cells. 



Genus Eloactis Andr. 



Diagnosis: Halcampoididae with a well developed, rounded aboral body-end, physa, perforated 

 by numerous apertures in 20 longitudinal rows. Column cylindrical; with numerous low, not anipullaceous 

 but sohd papillae, scattered over the whole surface; not distinctly divided into regions; without spirocysts 

 and sphincter. CincHdes in the uppermost part of the column. Tentacles as in Haloclava. Actinopharynx 

 as in Haloclava with longer or shorter aboral prolongation. No conchula. Pairs of mesenteries as well as their 

 muscles as in Haloclava. Tentacles and oral disc without spirocysts. 



^ Hargitt (1914) points out that the mesenteries are hexamerous in j-oiing specimens, decamerous in older ones, and from 

 this he concludes that the arrangement of the mesenteries "can hardly be of great significance as a toxonomic feature". As the ani- 

 mal during its development passes through a hexamerous stage with 6 pairs of mesenteries of the first cycle, it is evident that this 

 „variation" in the arrangement of the mesenteries is of no importance to the diagnosis. The adult specimens are namely decamerous. 



