Part I1.—Stichodactyline and Zoanthew. 157 
column. The column-wall is smooth and delicate, and the insertion of the 
mesenteries shows through. The wall is finely ridged in the living condition ; 
while, in preserved specimens, it is thrown into rather deep, close, zigzag, 
vertical strize, but no verrucee occur. 
The tentacles are short, knobbed or rounded at the apex, and arranged in two 
series: a marginal cyclic group, and an inner radiating group. The former 
are dicyclic and entacmeeous; the latter extend for various distances from near 
the margin towards the centre, diminishing slightly in size centripetally. In 
places, a distinct serial arrangement of the radial tentacles is exhibited, those of 
the first order reaching as far as the peristome, the second and alternating order 
a little shorter, and a third and fourth still more so. The shortest series con- 
tains only two or three tentacles in each row. This regular and evidently 
normal arrangement is departed from in other parts of the disc. About 60 rows 
were counted in one specimen, but the number varies with the size of the polyp. 
Each marginal tentacle consists of a short stalk narrowing a little above, and 
terminating bluntly or im a slight knob. Professor M‘Murrich describes and 
figures the marginal tentacles of the Bahaman specimens as conical. 
The inner tentacles are on the same radii as the outer cycle of marginal 
tentacles, thus alternating with the members of the first marginal cycle. They 
vary in length from 0:2 cm. to mere tuberculiform processes, the outer being the 
larger. Like those of the margin they terminate in a rounded or slightly knobbed 
manner, and the members of each radial row are in close contiguity peripherally, 
but become more distant one from the other centrally. Only a few of the 
radiating rows reach the peristome, and the tentacles here are a little larger than 
those for some distance behind (Pl. x., fig. 7; Pl. x1., fig. 5). 
The disc is sinuous, and usually elongated or irregular in outline. It is often 
reflexed at the margin, and so thin-walled that in some the movements of the 
internal larvee could be distinguished. The peristome is round and considerably 
elevated, ending sharply at the oval mouth. The stomodeal walls show about 
twelve very deep, flattened folds, but no gonidial grooves are indicated. 
The number of oral apertures is inconstant. Probably the majority of 
Jamaican examples have more than one. A specimen was come upon which 
possessed seven mouths of different sizes. Duchassaing and Michelotti regarded 
five as normal when the development is complete. An example bearing three 
apertures was met with in the act of vertical fission, the elongated columnar 
constriction being nearly broken down; others were collected, joined only by a 
thin basal membrane. The dise and tentacles can be completely infolded, so that 
no part of them is visible. 
The base is white, the proximal region of the column is flesh-coloured, the 
distal a very dark brown or may be bluish towards the margin. ‘The marginal 
TRANS. ROY. DUB. SOC., N.S. VOL. VII., PART VI. 2A 
