374 J. E. Durrpen—Jamaican Actiniaria: Part I.—Zoanthee. 
deeply staining nuclei are arranged in a middle zone; narrow nematocysts occur 
and large deeply staining granular gland-cells. The mesogloea is very narrow. 
The endoderm is thick and crowded with pigment spheres. A sulcar groove 
occurs, and here the mesoglcea is much thickened, but contains no cell-enclosures. 
Mesenteries (Pl. xx., fig. 6).—Twelve pairs of mesenteries, macrocnemic in their 
arrangement, are present. In the upper region each is a little narrow at its 
insertion in the column-wall, but the mesoglcea thickens rapidly ; only for a short 
distance in the cesophageal region, but more below. In the perfect mesenteries, 
the mesoglea beyond is very thin, and appears to alter in character so that it takes 
the stain better. There are no basal canals nor any cell-enclosures in the upper 
region; but lower two or three short canals, or there may be only cell-enclosures 
with pigment granules, appearing in the thickened part of the mesenteries. 
The endoderm is like that of the column-wall. Below the cesophagus it thickens 
enormously, and contains much pigment and granular matter; the mesenterial 
filaments are well developed and branched. In these, the zone of nuclei stains 
deeply, and occasional very deeply staining glandular cells are present along with 
nematocysts and much pigment matter. The parieto-basilar muscle is well marked 
on each side of the mesentery, extending a very little along the column-wall. In 
the imperfect mesenteries, the musculature extends the whole way round; in the 
perfect mesenteries, scarcely any distinction can be made in the musculature of 
each side, and the mesogleea is finely plaited. 
Gonads (PI. xx., fig. 6).—All the specimens examined from one colony con- 
tained abundant ova, present only on the perfect mesenteries, and associated with 
much pigment matter and enormously thickened endoderm. 
Coenenchyme and Base (Pl. xx., fig. 5)—The proximal surface of the base and 
ccenenchyme, in contact throughout with the sponge, has a thin ectoderm crowded 
with yellow pigment granules. The ectoderm of the upper surface of the coenen 
chyme is thick, and resembles that of the column-wall. 
The mesoglea is rather thick, and its inclosures are similar to those of the 
column-wall, but with a larger proportion of sponge spicules; cell-inclosures are 
numerous, and contain pigment granules. The endoderm of the base of the 
polyp is very thin, and contains pigment spheres and granules. 
This species was first described by Duchassaing and Michelotti from specimens 
obtained at St. Thomas. Of their figures (references to which are omitted from 
the ‘‘ Explication des Planches”), fig. 18 gives an approximate representation of 
the appearance of the colonies on the sponge; but fig. 17 is probably erroneous in 
the number and appearance of the capitular ridges and furrows indicated. 
Eight of these are shown, while in every case Ihave found twelve. In their later 
paper (1866, p. 138) they state the number of tentacles to be twenty-four, and 
arranged in two series; and it is generally found that the capitular radiations 
