J. E. Duekden — Jamaican Actiniaria : Part I. — Zoanthece. 351 



columns elongate sufficiently to bring all the individuals, with the disc looking 

 upwards, to about the same level. A living colony when fully expanded thus 

 presents the appearance of a mosaic work of brown or green depressed discs, with 

 margins of a dark-brown colour. 



When alive, polpys are found under three conditions : — 



(1) Retraction, where the disc and tentacles are entirely withdrawn, leaving 

 only a very small central opening. 



(2) Partial expansion, with a small portion of the disc visible. This is consi- 

 derably depressed, and the tips of the tentacles protrude from between the thick 

 capitulum and the disc. 



(3) Full expansion, in which the disc is completely exposed and only slightly 

 below the capitular margin, and the tentacles are quite free. In this state the 

 capitula are in contact with one another. 



Coenenchyrne present around the base of each polyp, but otherwise not very 

 freely developed, appearing rather as a consequence of the origin of the polyps 

 from one another by basal gemmation, and connecting them only as a flattened 

 band or ribbon ; the band may become constricted, and finally the individuals 

 sever their connexion with one another. 



Colour. — Lower part of column light buff, upper dark brown. Tentacles 

 usually dark brown, but may be olive or green. Disc in some is dark brown, with 

 green radiating lines, and the peristome a bright green ; or the disk may be green 

 and the peristome brown ; in others the disc and peristome are both bright green. 

 (Esophagus colourless. The ectoderm containing the brown pigment readily rubs 

 off when handled, the colourless mesoglcea, with the enclosed sand grains, 

 being exposed. In alcohol, the brown colour is first extracted, leaving the colony 

 a uniformly dark green ; later this gives place to a dirty buff colour. 



Dimensions. — The dimensions of the individual polyps vary considerably even 

 in the same colony, being largely dependent upon the position of the polyp in the 

 colony. In the large masses spreading over an even surface, the individuals 

 are all of the same thick-set type and approximately of uniform size. When the 

 colonies are smaller, and the incrusted surface irregular, the specimens in the 

 depressions become elongated in order to attain the same level as the majority. 

 The length of the column of one of the longest is 5 cm., the diameter 1*2 cm. ; an 

 average height is 1*5 cm., and diameter 0*7 cm.; diameter of expanded disk 

 2*3 cm. ; tentacles about - 3 cm. in length. Owing to the rigidity of the column- 

 wall there is not much contraction in preserved specimens. 



Locality. — Found growing very abundantly upon rocks and stones in shallow 

 water at Port Henderson, Kingston Harbour. Numerous irregular colonies are 

 to be met with, sometimes one or two feet across; one was over two yards in 



