Part II. — Stichodactylince 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 stria?, but no verrucse 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 entacmseous ; 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 in 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 - 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 (PI. x., fig. 7; PI. xi., 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 larvae could be distinguished. The peristome is round and considerably 

 elevated, ending sharply at the oval mouth. The stomodseal 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 disc 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 



TKANS. BOY. DUB. SOC, N.S. VOL. VII., PABT VI. 2 A 



