J. E. Durrpen—Jamaican Actiniaria: Part I.—Zoanthee. 341 
marked zones, all of nearly equal breadth ; an outer non-staining ciliated portion ; 
a middle deeply-staining zone with oval-shaped nuclei, granular gland cells and 
narrow nematocysts; and an inner, slightly narrower, nervous layer, con- 
taining a few circular nuclei, and a little pigment matter. The mesogloea and 
endoderm are each narrow. In transverse section, the cesophageal groove is not 
very pronounced, and the ectoderm is thrown into folds in some cases, in others not. 
Mesenteries.—The mesenteries are brachyenemic in arrangement and very 
thin. In one specimen, twenty-four pairs were present; in another, twenty-one. 
The endoderm is well developed, made up almost entirely of zooxanthellae and 
medium-sized, oval-shaped nematocysts. The mesogloa is folded and plaited 
on one side for the support of the longitudinal retractor muscle. A basal canal 
is developed in some a little distance from the column-wall, but is not present 
in others. 
The reflected ectoderm, mesenterial filaments, and endoderm swollen in the 
lower region, are similar to those figured and described by M°Murrich (1889, 
p. 115, pl. vii, figs. 3, 4), and the endoderm has embedded in it what I take 
to be the delicate acicular siliceous spicules referred to by him. The digestive 
endoderm is not so thickly developed in the previous species. The Driisenwulst 
of von Heider (1895, p. 129) can be well studied. 
Gonads.—None of the numerous specimens examined were fertile. 
I identify this very common Jamaican form as the Zoanthus flos-marinus of 
Duchassaing and Michelotti, rather from the description by Prof. M°*Murrich of 
specimens from the Bermudas (1889). The diagnosis of the original authors is 
very incomplete for this variable genus. They state the tentacles to be thirty-six, 
while the later writer gives them as fifty to sixty in number, a number agreeing 
with the Jamaican examples. Andres places it amongst his Zoanthi dubia. 
It may readily be distinguished from Z. Solanderi by its smaller size, usually 
clavate form, and stolon-like coenenchyme; and from Z. pulehellus by never 
forming a broad lamellar coenenchyme. 
Zoanthus pulchellus (Ducuassainc and MIcHELOTT!). 
(Pl. XVII.4, fig. 3.) 
Mamiillifera pulchella, Duchassaing and Michelotti, 1866, p. 187, pl. vi., fig. 4. 
Polythoa (Mammothoa) nymphosa, Andres, 1883, p. 320. 
Form.—Polyps erect, cylindrical, short or elongated, smooth, usually closely 
grouped, rising from a thin, tough, lamellar, incrusting ccnenchyme. In re- 
traction, either a little enlarged above or of the same diameter throughout, 
terminating in a rounded or slightly conical manner, and showing a central 
