Happon anp Durrpen—Some Actiniaria from Australia and other Districts. 141 
Locality —Pamban, Ramesvaram Island. Adam’s Bridge (between India and 
Yeylon), several colonies growing on nullipores, and associated with numerous 
small delicate sandy worm-tubes, which, along with other calcareous particles, 
adhere strongly to the stolons. 
We have associated with this species the name of our friend and colleague Miss 
Alice M. Shackleton. 
Body-wall (Pl. vu, fig. 1).—Very thin throughout, thickening a little in the 
region of the proximal sphincter muscle. The wall of the column is bounded 
externally by a distinct brownish cuticle, with a thick deposit of brownish 
granular material with foreign particles, including frustules of diatoms. 
Beneath this cuticle, and between it and the ectoderm, is a thin layer of 
mesoglceal substance, ‘ sub-cuticula,”* connected by strands of mesogloea through 
the ectoderm to the mesoglea proper. Below the upper portion of the column 
the cuticle and sub-cuticula present a somewhat dendriform appearance, best seen 
in longitudinal sections. In some cases the brownish cuticular substance is 
almost entirely enclosed. This dendriform appearance may be due to the 
unequal contraction of the cuticle and * sub-cuticula.” In the ectoderm, the cells 
have become so vacuolated that only nuclei and strands of protoplasm remain. 
The mesoglea is thin, and contains cell-islets. A canal system extends 
transversely and longitudinally ; and in the lower part of the column these 
canals are found to communicate with the basal canals in the mesoglea of the 
mesenteries. The contents of the canals stain very deeply, and zooxanthelle 
occur, especially in the lower part of the column and in the stolon. The 
endoderm is well developed, and crowded with zooxanthelle. The endodermal 
muscle is only slightly developed. 
Capitulum.—tIn the capitulum, the ectoderm becomes continuous, non-vacuo- 
lated, and without the cuticle and sub-cuticula. The mesogloea is very thin, and 
the endoderm crowded with zooxanthellee. 
Sphincter muscle (Pl. vi, fig. 2).—The sphincter muscle is double and 
mesogleal. The proximal, or lower, portion is well developed. The cavities in 
the mesoglea are hollow, with only a very thin lining of muscular fibres; they 
are transversely elongated above, but rounded and more numerous below. The 
distal, or upper portion of the muscle is much smaller. In contracted specimens, 
there is a deep fold of the body-wall between the two parts of the sphincter. 
Tentacles, Disc, and Csophagus.—The ectoderm is without the cuticle and 
the “sub-cuticula,” and is non-vacuolated. The mesoglea is thin; the 
endoderm is thick, crowded with zooxanthelle, and almost fills up the lumen of 
the tentacles. 
* Of. the remarks on this structure by Prof. A. R. von Heider, “‘ Zoanthus chierchia, n.sp.”: Arbeit. 
Zool. Inst. Graz., v. 1895, p. 118. 
Z2 
