THE ACTINIANS OF PORTO RICO. 
361 
The coloration is very complex in character, oftentimes somewhat brilliant, and varying much 
in different polyps. The base is dark gray. The column is occasionally bright orange, but more 
often brown and orange, tinged with purple. The cinclides are dark-brown elevated spots, often with 
yellow margins; two or three white, light yellow, or orange triangular bands extend to them from the 
margin of the base, or may go beyond. Narrower light bands of variable length occur in the inter- 
spaces all round, commencing at the base of the column; irregular light-colored patches may also 
occur toward the top of the column. When the cuticle is thick the column becomes dirty brown or 
purplish, due to adhering foreign particles. 
The tentacles are gray, usually with faint purplish brown transverse bands or patches on their 
oral aspect; five or six of these are present on the larger tentacles, but only two or three on the 
smaller. Often a row of small opaque white or yellow spots extends nearly the whole length of the 
inner face of each tentacle; larger opaque white patches may also be present. In one specimen 
the' tentacles throughout were a very delicate purple. The disk is yellowish gray. A wavy, discon- 
nected circle of opaque white radiating patches occurs near the base of the tentacles of the four inner 
cycles, and outside this an irregular dark purple or black cycle extends nearly to the outer margin of 
the disk. A circle of twelve, opaque white, V-shaped markings is also present about midway between 
the tentacles and the mouth, the markings corresponding with the third cycle of twelve tentacles, and 
another cycle of six may be present nearer the mouth, opposite the second cycle of six tentacles. The 
middle of the peristome is grayish, the lips bright orange, the stomodanmi yellowish brown. When 
fully extended, six dark purple areas within the tentacular and capitular region are seen to alternate 
with larger colorless patches. The acontia may he either opaque white or salmon colored.* 
The diameter of the base of an average-sized specimen is 3 cm.; the height of the column about 
2.8 cm. ; the diameter of the disk, 1.5 cm. The length of the inner tentacles when expanded is 0.9 cm. ; 
of the outer, 0.25 cm. A large specimen measured 4.5 cm. across the base and was 3.5 cm. in height. 
Anatomy and Histology . — The basal wall is very thin compared with that of the column, the 
difference being determined by the relative development of the mesogloea. The columnar cells of the 
ectoderm are long and narrow. Gland cells are numerous, the peripheral portion of which contains 
granular matter not staining with borax carmine; large clear gland cells are practically absent. The 
cuticular membrane secreted by the ectoderm of the base, and regarded by McMurrich (1893, p. 182) as 
characteristic of the genus, is present in some sections, but is readily separable from the ectoderm. 
The mesogloea, though moderately developed, is much thinner than in the column- wall; omall isolated 
cells are sparsely scattered throughout. The endoderm is a very narrow layer, and a Weak endodermal 
muscle is developed. 
The column-wall in the retracted condition is often very thick, mainly due to the increased 
development of the middle layer. A thick cuticle, with foreign particles attached, is present in speci- 
mens from which it has not recently been sloughed off. In sections the ectoderm is very narrow, and 
maybe much folded in preserved specimens. By contrast with the base, clear or slightly granular 
gland cells are conspicuous, and form an outer, non-staining zone; a nuclear zone is displayed about the 
middle of the layer, while scattered nuclei occur more internally. The mesogloea is greatly thickened 
and appears fibrous in character, containing many minute connective-tissue cells. Sometimes the 
fibrous character assumes a reticular appearance, and often the layer incloses minute pigment granules. 
Toward the apex it narrows abruptly, the capitulum being very thin-walled. Internally the mesogkea 
is finely plaited for the support of the endodermal muscle. This latter is best developed below and 
about the middle of the column, and at the insertion of the mesenteries becomes mesoglceal. The 
endoderm displays the nerve layer very distinctly. 
The sphincter muscle is a strong mesoglceal representative (fig. 45)* Above it is very broad, 
extending nearly across the thick mesogloea, while below it gradually tapers to its extremity, which is 
near the endodermal border. In the first part the mesogloeal muscle-containing cavities are so close 
that the sphincter region, as a whole, appears finely reticular in character, but the chambers soon 
become distinctly separated from one another. They are then arranged in regular rows, the different 
*The species of Calliactis and Adamsia are usually gaily and variously colored, even to the acontia. Prof. H. N. 
Moseley (Q. .1. M. Sc., vol. xvn, 1877, p. 4) has investigated the coloring matter of an Adamsia obtained off the Philip- 
pines. The polyp was a mottled yellow and brown color with pink stripes. The pink coloring matter in the fresh 
condition yielded a single well-marked absorption band. The acontia, as in C. tricolor, were of a light red color, which 
gave two absorption bands in the green. Carlgren (1900a, p. 55) also mentions that the acontia of Calliactis polypus (Forsk.) 
are rose colored, and Haddon (1898, p. 457) describes those of C. miriam (H. & S.) as salmon colored. 
