338 J. E. Durrpen—Jamaican Actiniaria: Part I.—Zoanthee. 
Gsophagus.x—The nematocyst- and nuclear zone in the ectoderm is very 
regular, and situated close to the outer surface, while a non-staining 
nervous tissue intervenes between it and the mesoglea. The latter is very 
thin, and the endoderm resembles that of the mesenteries. In transverse sections, 
the cesophagus is oval. In the upper region, the ectoderm is not thrown into 
folds, and the cesophageal groove is barely apparent. Lower, as many as twelve 
longitudinal folds may be present on each side, and a slight indication of a 
groove. The mesenteries are attached to the cesophagus at about equal dis- 
tances all the way round. The ectoderm is reflected on the mesenteries, and 
continued downwards as the mesenterial filaments. 
Mesenteries—The mesenteries are of the brachyenemic type ; generally about 
thirty pairs are present; one specimen had fifteen perfect mesenteries on one 
side, and only thirteen on the other. 
The endoderm contains abundant zooxanthelle, and medium-sized oval nemato- 
cysts. The digestive endoderm (1889, p. 116; 1891, p. 622) is not very thick. 
The basal canal is large in both the perfect and imperfect mesenteries. It 
is elongated in the former, and full of deeply-staining cells. 
The parieto-basilar muscles are clearly distinguishable, as also the retractor 
muscle of the mesenteries. The mesoglcea is folded to support the muscle. 
Gonads.—No reproductive elements were present in any of the examples studied. 
The following may be regarded as distinguishing anatomical characters: 
(a). Pigment limited to the inner portion of ectoderm ; 
(4). Mesogleeal lacune ; 
(c). Form of sphincter muscle. 
The Jamaican form above described appears to unite the two species Z. 
Solandri and Z. dubia, as originally described by Lesueur, and as known to 
Duchassaing and Michelotti from the same localities. Considering the variation 
in colour noted, it is evident that little importance can be attached to it. 
Referring to the first species, Duchassaing and Michelotti state: ‘Le couleur de 
cette esptce est sujet & varier, mais nous n’y avons jamais remarqué 4 l’état 
vivant la teinte qui lui donne M. Milne-Edwards dans l’atlas qui accompagne son 
ofivrage sur les coralliaires, la teinte verte se montre toujours dans une parti 
ou sur la totalité du corps de ces animaux.” Some account must be taken of 
the character given by Lesueur that, when the animal is contracted, the summit 
is marked with deep blue angular spots and white lines, a feature agreeing with 
the present specimens. The polyps are usually non-pedunculate, resembling the 
figure of Z. dubius given by Duchassaing and Michelotti; but pedunculate forms, 
agreeing with Lesueur’s original figure, also occur. 
