184 J. E. Durrpen—Jamaican Actiniaria : 
is delicately plaited for additional support to the endodermal and ectodermal 
musculature. 
The stomodeeum is oval in transverse sections, and the ectoderm is thrown into 
about twenty very deep and regular longitudinal folds, the mesoglcea also 
following. In position the folds bear a rough approximation to the points of 
attachment of the complete mesenteries. No indication of gonidial grooves is 
presented. Haddon (1898, p. 468), on the other hand, found three gonidial 
grooves in one example of C. hoplites, and one in another. 
The stomodeal ectoderm is uniformly ciliated, and the supporting cells 
give rise to the usual zone of brightly-staining nuclei; several varieties of 
nematocysts are represented, and various kinds of elongated, granular gland cells. 
Following the folds of the ectoderm the mesoglea is very thick and triangular 
in transverse section, but between the folds it becomes extremely narrow; a weak 
musculature occurs on both its ectodermal and endodermal surfaces. The endo- 
derm is a broad layer, constituted largely of gland cells, some with clear contents, 
and others which are granular and stain readily. 
The mesenteries are tetramerous and arranged in three cycles; eight perfect 
pairs, of which two pairs are directives, represent the first and second cycles, and 
are about equally developed, while eight, incomplete, alternating pairs represent 
the third. In the upper region of the stomodzum an odd member of the free 
series may be connected with the stomodeal-wall for some distance, and, in one 
or two cases, remains attached for practically the whole stomodeal extent. 
This is especially noticeable in the region of one of the pairs of directives, as 
compared with the lateral pairs. In one instance an odd member of two pairs 
of the third cycle is connected with the stomodzeum throughout its length, but on 
one side it is the mesentery next the directives, while in the other it is the next 
but one which is perfect. ‘This latter condition is shown in PI. xu, fig. 4, where 
the second mesentery from the left, belonging to the third order, has just ceased its 
connexion at the termination of the stomodzeum. Otherwise the regularity of 
the mesenteries in this species is in striking contrast with the lack of symmetry 
met with in other representatives of the genus. 
The mesoglcea of the mesenteries is thick for some distance from its origin in 
the column-wall, and on one side it then forms plaits of greater or less complication 
(Pl. xv., fig. 3). These are of the same character as in Corynactis australis. 
The folds support the vertical retractor muscle, which also extends along the 
whole face of the mesentery. In no case does the muscle give rise to a thickened 
band, as in most members of the Actiniz. 
Beyond the region of greatest plaiting the mesoglcea narrows considerably ; 
and here, in the proximal part of the polyps, the surface of the mesogleea of the 
opposite face also becomes delicately plaited for the support of the oblique 
