162 J. E. DuerpEn—Jamaican Actiniaria : 
(H. & 8.) [the type], and S. Haddoni (S.-Kent), and also D. Fuegiensis (Dana). 
The sphincter muscle is remarkably similar in all four. 
D. tuberculata, Kwiet., should also probably be transferred to Stoichactis, but 
not D. ambonensis, Kwiet., in which the tentacles are placed in radial groups, so 
that more than one row communicates with a mesenterial chamber. 
Whether, as in the form I identify as D. helianthus (Ellis), a single marginal 
cycle of exoccelic tentacles alternating with all the endoccelic radiating rows will be 
found in other representatives of the genus remains to be seen. Until this is 
ascertained it seems doubtful if the character should be assigned generic rank, and 
I have therefore omitted it. 
Stoichactis helianthus (Ellis). 
(VEIL 3Migg mee, 7/2 IPI, Sion 42; Ilo) 
Actima helianthus, . . . Ellis, 1767, p. 486, pl. xiii., figs. 6, 7; Ellis and 
Solander, 1786, p. 6. 
Hydra helianthus, . . . Gmelin, 1788, p. 3869. 
Discosoma helianthus, . . Milne-Edwards, 1857, p. 256; Duchassaing and 
Michelotti, 1866, p. 122; Andres, 1883, p. 493. 
Discosoma anemone, . . . M*Murrich, 1889, p. 37, pl. i, fig. 8; pl. u., 
figs. 15-16, pl. iv., fig. 1. 
The base is a little larger in diameter than the lower part of the column ; 
usually it is firmly adherent to the surface of rocks, or may be buried in the sand. 
It adapts itself to the irregularities of any object to which it is attached, and is 
generally deeply wrinkled in consequence; preserved examples show concentric 
and radiating ridges and furrows. 
The column is short and salver-shaped, narrowing a little above the base, 
and then expanding enormously in a crateriform manner, so as to completely 
overhang and hide the basal part. Usually the column is only partly embedded 
in sand, the overhanging distal region being free and resting on the surface. Its 
walls are somewhat thick, but slightly transparent; the surface is smooth, and 
grooved in correspondence with the attachment of the mesenteries. Distally 
vertical rows of oval green verruce occur, but they are evidently incapable of 
attaching foreign particles to the column. The apex of the column, corresponding 
with each mesenterial space, is slightly rounded, but is not modified to form an 
acrorhagus. A well-marked fossa occurs between the apex of the column and the 
base of the outermost row of tentacles. 
The disc is greatly expanded, but remains flat, never being thrown into folds 
as in the next species. By far the greater part of it is covered with radiating 
tentacular rows of various lengths; the central, naked area is smooth, and the 
