150 J. K. Duserpen—Jamaican Actiniaria : 
parent membrane, and all the marginal tentacles come together in the centre and 
close up the aperture. 
The peristome is considerably elevated and usually elongated; like the rest of 
the disc it bears tuberculate bodies, which are here usually a little smaller. The 
mouth is circular in small forms, elongated in larger. The stomodzeal wall is 
thrown into numerous, deep, much flattened folds, and is capable of considerable 
eversion. It is very sharply marked off from the disc. Twenty folds were 
counted in avery small specimen, and over thirty occurred in another; true 
gonidial grooves do not occur (aglyphic). 
Polyps are occasionally come upon in which the disc bears two or more distinct 
mouths, without any indication of longitudinal fission. 
The coloration varies much in detail in different polyps. The column-wall 
is light or dark brown, usually darker above, but lighter again towards the apex, 
the latter often showing an iridescent green tinge. ‘The disc is an iridescent green, 
with brown, radiating lines separating it into narrow, radial areas; or, the general 
surface of the disc may be brown, and the radiating lines iridescent green. 
Some of the radial bands may be nearly opaque white. ‘The larger marginal 
tentacles are a faint blue below, brownish or rose-coloured distally; the smaller 
tentacles are brown. ‘The disc tentacles are brown and iridescent green, or may 
be a deep blue purple. The stomodeeal-walls are white. 
The dimensions are very variable. ‘The base may be 2°5 cm. across; the 
column 1:4 cm. in diameter, and 1 to 2 em. high. The length of the larger 
marginal tentacles is 0°2 em. One specimen was obtained with a disc 5-4 em. in 
length, and length of mouth, 1:3 cm. 
ANATOMY AND HisToLoey. 
The ectoderm of the base is formed of high supporting cells, along with a few 
mucous cells. In sections the nuclei of the former give rise to a distinct narrow 
zone, situated a little nearer the mesogloea. A very thick, brown, cuticular mem- 
brane, which readily strips off, is still present in some examples, and is continued 
for a short distance up the column. ‘The mesogleea, as is the case throughout the 
whole polyp, is very thin, and rather large ovate cells are sparsely scattered 
through if; a very weak musculature appears both on its ectodermal and endo- 
dermal borders. ‘The endoderm is much narrower than the ectoderm, and is 
well supplied with gland cells, but devoid of zooxanthelle. 
The ectoderm of the column-wall is a high layer, and crowded with clear, 
unicellular, mucous glands, so that an outer zone appears colourless, the contents 
of the glands not staining. ‘The cells are extremely delicate, and in sections are 
nearly always collapsed or shrunk ; indeed the tissues as a whole are less resistant 
