168 J. E. DuERDEN — Jamaican Actiniaria : 



nearl}^ similar rows ; in a good-sized specimen over 300 radiating rows were 

 counted. The apex may be shortly and bluntly conical. All the tentacles are 

 of about the same size, but may vary a little with the amount of distension, 

 sometimes becoming quite flaccid on the withdrawal of water. 



The tentaculate area of the disc is divisible into two very distinct regions — 

 an outer, in which the tentacles form about twelve cycles, each containing the same 

 number ; and an inner, in which the rows begin to terminate at differant distances 

 from the mouth. Only thirty or forty rows are continued the full length of both 

 regions, but all extend across the first. In large specimens no serial order is 

 obvious in regard to the lengths of the inner rows, but three or four orders can 

 be made out in young specimens (PL xii., fig. 4). Peripherally, the tentacles are so 

 closely arranged that on a slight contraction of the polyp the apices press one against 

 the other and assume a polygonal outline, and sometimes more than one row 

 appears to communicate with a mesenterial chamber. Small developing examples 

 may occur among the others, especially at the margin which apjDears to be a 

 region of continuous active growth. Occasionally a bifurcated tentacle is come 

 upon, and omissions may occur here and there, especially in the inner series. 

 Only one row communicates with each mesenterial space. The organs possess 

 considerable adhesive power when alive, though not so marked as in the former 

 species, and can move about independently of one another. 



The gonidial grooves are very distinct, the two enclosing lips being thick and 

 protuberant. The walls of the stomodseum are slightly ridged, and so delicate 

 that the mesenterial lines show through. In a state of repose the mouth is com- 

 paratively small and oval, but in preserved specimens it is widely open and nearly 

 circular. 



A small specimen, only about two centimetres in diameter, which I regard as 

 an immature form, was found at Port Antonio adhering to a Thalassia leaf. It 

 differed from the ordinary condition in having several tentacles distended to two 

 or three times the size of the others, giving the disc quite a ])eculiar ajipearance. 



The colour of the base may be faint scarlet, the intensity varying in different 

 examples; or, it may be cream-white with only minute flecks of scarlet. In most 

 the lower region of the column is a very bright scarlet or orange-red, sometimes 

 in small patches on a cream ground. Distally the column is dark brown or steel 

 grey. Occasionally the column-wall may be almost devoid of colour, except in the 

 distal region, which always passes gradually into a very dark brown. The brown 

 coloration is evidently determined by the presence of zooxanthellte in the endo- 

 derm. Histologically it is shown that these occur only in the upper part of the 

 column. 



The disc varies much in colour in its different regions. Peripherally, where 

 the tentacles are closely aggregated, it is usually a uniform light or dark yellowish- 



