194 J. E. DugrpEN—Jamaican Actiniaria : 
To the naked eye the surface of the coenenchyme and column-wall is quite 
smooth, but with a lens minute white granulations—the foreign inclusions—are 
disclosed. The walls are thick and firm, but in some cases superficial wrinklings 
may be observed in preserved specimens. 
The polyps were examined only in their retracted or partly retracted state. 
They are capable of complete retraction, in which condition they are usually 
mammiform; or they may be slightly longer, and flattened or rounded above, a 
small aperture remaining in the middle. ‘Towards the base the column enlarges 
in diameter, especially in the most retracted individuals. 
The capitular ridges are small, and can be distinguished and counted only with 
the assistance of a lens; they are wedge-shaped and acute, and vary in number 
from 14 to 16. The ridges and furrows are most distinctly indicated during 
partial extension. 
The tentacles are short, apparently rounded at their apex, and dicyclic, 
fourteen to sixteen occurring in each cycle. The mouth is rounded or slit-lke, 
and the lips prominent. 
The colour of the ccenosare and column-wall is greyish, being determined by 
that of the included particles ; the tips of the capitular ridges are a little lighter ; 
the tentacles and disc are brown. 
The height of retracted polyps above the coenenchyme is about 2 mm., and the 
diameter the same. 
ANATOMY AND Hisrouoey. 
The ectoderm of the column-wall is a continuous layer, that is, it is not broken 
up by crossing strands of mesogloea, as is the case in many Zoanthez. Superficially, 
it is devoid of any recognizable cuticle or sub-cuticle, and the constituent cells are 
more rounded than columnar in outline. ‘The internal limitations of the layer are 
very irregular and indeterminate in places, most of the inclusions occurring 
around its boundary with the mesogloea, while cells pass from it into the 
mesogloea (Pl. xim., fig. 7; Pl. xv., fig. 4). 
Small colourless nematocysts occur, but are not very numerous. 
The mesogloea is moderately thick, and near its internal border contains a 
narrow, interrupted, encircling sinus filled with cells closely resembling those of 
the ectoderm; in the distal region, where the sinus becomes broader, it includes 
numerous nematocysts. 
Isolated cells and cell-islets are scattered throughout the mesoglcea; and a 
few siliceous sponge spicules are included, in addition to the predominating 
calcareous sand-grains. The latter are very small and practically limited to its 
peripheral border; they are dissolved out by acids leaving only irregularly-shaped 
lacune. In regard to the foreign inclusions, a decided selection is manifested in 
