144 Happon anp Durrpen—Some Actiniaria from Australia and other Districts. 
The larger cell-islets contain zooxanthellae. There is not much tendency to the 
formation of lacunz. Single cells with elongated fibrils stretch across the mesogleea. 
The endodermal muscular layer is well developed, but less so in the lower 
part of the column, The endoderm is uniformly developed, of medium height, 
and crowded with zooxanthelle. 
Sphincter muscle (Pl. vut., fig. 5).—The sphincter muscle is single, mesoglceal, 
and elongated. The hollow cavities are arranged in a continuous row close to the 
endoderm; the upper are larger and more irregular in shape. 
Dise and Tentacles.—The ectoderm and endoderm of the dise and tentacles are 
both crowded with zooxanthelle. The mesogloea of the latter is very thin, and 
the ectodermal muscular layer is well developed, in marked contrast to the 
endodermal. Cell-inclosures are found in the mesoglea of the disc. The surface 
of the mesogloea adjacent to the endodermal aspect is much plaited. 
(sophagus.—The cesophagus is oval in section, with a well-marked rectangular 
cesophageal groove. ‘The ectoderm is very deeply folded into eight ridges along 
each side, the mesoglea passing into each. The nuclei of the ectodermal cells 
form a well-defined and continuous central row. The mesoglea is very thin, 
except at the groove, where it becomes somewhat thickened. As in G. ‘solata and 
G. rusei the mesogloea has enclosures of granular cells placed more particularly at 
the insertion of the mesenteries, and at the bases of the outgrowths into the 
cesophageal folds. 
Mesenteries.—The mesenteries show the brachyenemic arrangement in a very 
clear manner. There are twelve pairs of perfect mesenteries. The mesoglcea is very 
thin in the lower part. The musculature is relatively well shown on both perfect 
and imperfect mesenteries. The basal canals are large and rounded, especially 
in the region below the cesophagus ; in the cesophageal region they become oval 
in section, and soon divide into two or more branches. ‘Towards the top of the 
mesenteries the canals are more irregular. ‘The mesoglcea in this region becomes 
very much and deeply plaited, and the endoderm is crowded with zooxanthelle. 
Ceenosare (Pl. vut., fig. 6).—The ectoderm and incrustations have the same 
character as in the body-wall. The mesoglea is crowded with cell-islets, and 
contains numerous ccelenteric canals. 
Gonads.—Both of the specimens examined contain ova. 
Gemmaria Canariensis differs from the four previously described species of the 
genus in the following characters:—1. In having the capitular region swollen 
when contracted. 2. In the presence of a thick ccenosare. M*Murrich (1889, 
p. 65) is inclined to believe that the polyps of @. ésolata may be connected by a 
thin continuous ccenosare, but owing to the fact of the polyps being buried up to 
the tentacles in sand, he was not able to decide this. 3. In the incrustations 
being limited to the ectoderm and the outermost part of the mesogloea, 
