Hapvpon—The Actiniaria of Torres Straits. 417 
Colour.——Column uniform pale lemon-yellow; oral disk and_ tentacles 
uniform burnt amber brown, sometimes lighter, sometimes darker; basal 
portion of tentacles grey or white, this giving an ill-defined greyish margin 
to the disk. 
Dimensions ——Height of column 30-40 mm. (1} — 14 inch); expanse of 
corona of largest specimen 50 mm. (2 inches); tentacles 15 mm. in length 
($ inch). 
Habitat.—Between tides on the seaward side of a mangrove swamp, Mabuiag. 
In one of the two largest specimens, there were 200 tentacles and about 80 mar- 
ginal spherules ; and in one of the smallest specimens 80 tentacles and 30 marginal 
spherules. 
The spherules are often very unequal in size, and when so there is no regular 
arrangement, but several may occur closely packed together in one portion of 
the circle, while they are widely separate from each other in another part. The 
angle between the body-wall and the oral disk is very acute; and it is on the summit 
of the rim thus formed that the marginal spherules are placed. In none of the 
specimens do the marginal spherules appear to be withdrawn into a circular invagi- 
nation such as occurs in Actinia equina. Internally the spherules are separated 
from the outer circle of tentacles by a well-marked zone which, in well-expanded 
specimens, is inclined as much downwards as inwards. The tentacles in large 
specimens appear to be in two or three rows; they are fairly long, not sharply 
pointed, and apparently imperforate at the tip. 
Inside the tentacles the oral disk is smooth, and horizontal in position. The 
mouth is central, very small, and usually quite circular. There are no gonidial 
tubercles. The body-wall, in well-preserved specimens, is quite smooth; in 
height it is equal to the diameter of the animal. The pedal disk is smooth, 
and sometimes shows radii corresponding to larger mesenteries. 
When a specimen is cut in two vertically, the cesophagus is seen to 
expand very rapidly, so that the first part of its wall seems to be more 
horizontal than vertical. (Pl. xx, fig. 1.) [This is of course due to the 
small size of the mouth.] The cesophageal wall is marked by grooves and 
ridges which seem all about equal in size. No marked cesophageal grooves 
are present. 
On further examining a specimen cut vertically one is struck by the entire 
absence of any sphincter muscle visible to the naked eye. The body-wall thicker 
in its lower part is seen to become thinner when traced upwards, and to be thinnest 
of all where it forms the marginal spherules. The upper part of each mesentery, 
or that part stretched between body-wall and oral disk, is very delicate, and is 
pierced by a well-marked stoma. (PI. xxi, fig. 38.) The rest of the mesentery is 
thicker, but not very muscular. 
TRANS, ROY. DUB. SOC., N.S. * VOL. VI., PART XVI, 
3Q 
