Part I1.—Stichodactyline and Zoanthee. 205 
folded backwardly and outwardly, so that in transverse sections through this region 
its endoderm and ectoderm are cut through twice ; and, further, the ectoderm 
appears to be continued radially for some distance along the mesenteries. The 
mesenterial filaments are, however, simple throughout, that is, only the middle lobe 
is present, the lateral lobes with the Flimmerstreifen not being developed. 
Although numerous polyps have been sectionized, it has been found impossible 
to make out the complete arrangement of the mesenteries. In most ten mesenteries 
are perfect, being united with the stomodeeum at varying intervals. Nine perfect 
mesenteries occurred in one example. No certain indications of imperfect mesen- 
teries were afforded. The mesoglcea of the mesenteries is swollen at its origin in 
the column-wall and encloses cell-islets ; beyond the origin it thins rapidly. An 
extremely weak parieto-basilar musculature occurs. The retractor muscle fibres of 
the mesenteries are similarly very feeble, the mesoglcea being slightly plaited to 
give increased support; the fibres appear to be strongest about the middle of the 
width of the mesentery. The mesenterial endoderm is broad and crowded with 
zooxanthellz ; it is more swollen below, and contains an abundance of small, 
spherical, apparently non-nucleated bodies, which stain deeply. Pigment granules 
are practically absent, but about the middle of transverse sections of mesenteries a 
peculiar accumulation of fine, yellowish brown granules occurs on each face, very 
limited in its radial extent. The endoderm throughout the polyps occasionally 
contains large zooxanthellee-like bodies with a highly refractive cell-wall. No 
gonads were indicated in any of the polyps sectionized. 
The species was trawled on only one occasion, February 10, 1898, at a depth 
of 10—14 fathoms, on the Pedro Bank, Caribbean Sea, commensal with a silicious 
sponge. 
In a list of the Actiniaria around Jamaica (1898), I identified the form as 
the much debated Bergia catenularis, Duch. & Mich., its commensal habit and very 
decided catenulariform appearance suggesting this species most forcibly, I am 
now convinced, however, that the safest course is, for the present, to regard it asa 
new species and await the possibility of discovering others which may approach the 
older species more closely. Especially may this be the case in regard to the nature 
of the ccenenchyme connecting the individual polyp. From Duchassaing and 
Michelotti’s figure, B. catenularis appears to have this better developed than in the 
present species, and more in the form of stolons, but I do not attach much impor- 
tance to the statement that the connexions arise from the upper part of the polyps. 
This is probably merely a result of the colonies being partly embedded in the 
sponge, and P. monostichus affords indications of the same feature. There is little 
doubt that the two species of Bergia will, when rediscovered and sectionized, be 
found to belong to the genus Parazoanthus. 
TRANS. ROY. DUB. SOC., N.S. VOL, VII., PART VI, 2G 
