182 J. EK. DuEerpEN—Jamaican Actiniaria : 
in outline, tough, and firmly adherent to various objects. Polyps are met with 
in groups, and are occasionally found connected, one with another, by a thin basal 
expansion or ceenosare. The column is short, mammiform or cylindrical in 
retraction, irregular in outline below, and circular or oval above. The surface is 
smooth, and the walls thin and translucent, the lines of attachment of the 
mesenteries showing through, and dividing the whole column into slight ridges 
and furrows. 
The tentacles are arranged in cycles and in radiating rows, each row com- 
municating with one mesenterial space. In one specimen in which the tentacles 
could be counted they numbered 48, arranged in four cycles in the formula 8, 8, 
16, 16. The innermost tentacles are very short, appearing as mere tubercles on 
the disc; the intermediate show a distinct stem and knob, while the outermost are 
still larger, and overhang in extension; the stems are conical, and the knobs 
rounded. ‘The disc is oval or circular, smooth, thin-walled, and nearly transparent, 
the mesenterial lines showing through; the oral cone may be very prominent. The 
mouth is oval; the walls of the stomodzum are deeply ridged and furrowed, and 
very protrusible ; no gonidial grooves are indicated. The disc and tentacles may 
be entirely hidden in retraction. 
The column is brown below, and almost colourless or crimson above; a circle 
of small, emerald green, capitular spots may or may not be present. The stems 
of the tentacles are translucent and colourless or yellowish; the knobs rose, red, 
or orange. ‘The disc is brown, with white radiating lines; the peristome bears a 
narrow circle of emerald green spots; the stomodzeal wall is white. 
When retracted, the polyps measure about 0:7 cm. in diameter, and are the 
same in height. 
ANATOMY AND HisTouoay. 
Examined histologically the ectoderm of the base and also of the column-wall 
is remarkable for the abundance of large unicellular mucous glands, mingled with 
the narrow supporting cells. They appear to constitute the greater part of the 
layer, becoming more swollen towards the free surface, where they give rise to an 
almost clear zone. ‘The contents are sometimes clear and homogeneous, and do 
not stain in borax carmine; in most cases, however, they are finely granular, and 
take up the colour slightly. The nuclei of the supporting cells are arranged in a 
zone a little within the middle of the layer, while the most internal region of the 
ectoderm exhibits nerve and muscle fibrils. The ectodermal musculature is 
discernible on the base, but becomes stronger on the column-wall, the cut ends of 
its fibrils appearing as a very distinct layer in transverse sections. 
Throughout the base and column-wall the ectoderm remains a high columnar 
