J. E. Duerpen—Jamaican Actiniaria: Part I.—Zoanthee. 3538 
mesoglea; twelve occur on each side in one specimen, but there may be as many 
as 15 or 18. The large colourless nematocysts and pigment granules are present, 
and a weak nerve layer. 
The cells are longer at the groove. The mesoglea is thin, but thickens 
towards the same place, and contains cells. The endoderm is low, and shows an 
outer zone of nuclei and an inner non-staining zone; the endodermal muscle 
is supported on mesogleeal plaitings. 
Mesenteries (Pl. xvut. a, fig. 9).—The usual brachycnemic condition is present 
in most; but in two specimens the mesenteries are brachycnemic on one side, 
and macrocnemic on the other. In most, fifteen perfect mesenteries occur on 
each side, and the same number of imperfect. In one, twenty-seven pairs in all 
were present, and in another twenty-eight pairs. Each has an irregularly shaped 
basal canal a little beyond the origin, and, in the upper part of the column, others 
extend almost across the mesentery. The basal canal is continued the whole 
length of the mesentery, and contains zooxanthellz and large oval nematocysts ; 
it may be divided in the upper part into two or more closely approximated canals. 
The parieto-basilar muscles are well developed. Beyond the basal portion the 
mesenteries are very thin, and the endoderm is crowded with large zooxanthelle. 
The imperfect mesenteries are very short proximally, appearing in transverse 
sections as goblet-shaped projections of the body-wall; the muscle extends all 
round, while the basal canal is more circular than in the others. The reflected 
ectoderm and mesenterial filaments are well developed. 
Gonads (Pl. xvut.a, fig. 8).—In one specimen examined, both male and female 
gonads were found in abundance; sometimes both kinds would occur on one 
mesentery, while others bore either ova or spermaria. The ova, which evidently 
were nearly ripe, were scarcely stained with borax carmine, while the spermaria 
readily took up the pigment. 
Coenenchyme.—In its outer part, the ccenenchyme has numerous inclosures 
similar to those of the body-wall. Many large cell inclosures and ccelenteric 
canals are met with, the latter with a very regular epithelial lining and a weak 
musculature. 
Under their genus Gemmaria, MM. Duchassaing and Michelotti describe 
(1860) four species of Zoanthidz from the Antilles, viz. :—@. Ruse’, Duch. and 
Michel. ; G. clavata, Duch.; G. Swiftii, Duch. and Michel. ; and G. brevis, Duch. 
The first has been recovered in-the Bermudas by MeMurrich (1889), while 
G. Swiftii is shown in the present Paper to belong to the genus Parazoanthus. 
I have hesitated considerably as to the identity of the present form with 
G. clavata, but have finally decided that the characters given in the two descrip- 
tions of it will not admit of this. The original diagnosis (1850, p. 11) gives the 
TRANS. ROY. DUBL. SOC., N.S. VOL. VI., PART XIV. 38H 
