J. E. Duerden — Jamaican Actiniaria : Part I. — Zoant/iece. 353 



mesoglcea ; 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 mesoglcea 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 mesoglceal plaitings. 



Mesenteries (PI. xviii.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 zooxanthellae 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 zooxanthellae. 

 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 xviii.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 Zoanthidae from the Antilles, viz. : — G. Rusei, Duch. and 

 Michel. ; G. clavata, Duch. ; G. Swiftii, Duch. and Michel. ; and G. brevis, Duch. 

 The first has been recovered in the Bermudas by M c Murrich (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 



1EANS. BOY, DTJBL. SOC, N.S. VOL. VI., PAUT XIV. 3 H 



