REPORT ON CORALS—DEEP-SEA MADREPORARIA. 159 
Colour of the animal greenish-yellow, the mouth margin white, with twelve broad 
glistening white folds or bands, dise external to these emerald green. As far as I can 
determine from the mutilated specimen, I believe that this coral differs from others 
which I have examined in that in the contracted state all the tentacles are concealed, 
the dise contracting and closing in over them as in Actinia. In the contracted animal 
there is a sphincter-like opening in the centre of the disc, which leads to a cavity in 
which are the tentacles, out of which again opens the mouth which is surrounded by a 
prominent ridge. The entire outer surface of the corallum is invested by a thin lamina 
of living tissue. Johnston observed the living British species Sphenotrochus macandrew- 
anus, and has given some description of it." 
Extreme heights of three coralla 19 mm., 17 mm., and 17 mm., respectively. Extreme 
breadth of the calicles 20 mm. in all the specimens. Shorter diameters of the calicles 
16mm. to13 mm. Extreme breadth of the ale in one specimen 3 mm. Breadth 
at the base of the corallum between the outer edges of the als in the above specimen, 
16 mm. : 
One perfect fresh specimen was obtained, and another which had the soft parts 
present but had been badly crushed in the dredge, with these were two dead and partly 
broken specimens. 
Station 192, off the Ki Islands. 129 fathoms. 
Pleurocyathus, n. gen. 
Corallum conical, attached by its side. Entirely covered by a thin plicated coloured 
bark-like epitheca, which rises higher than the margin of the calicle. Wall of the calicle 
very thin, except near the margin, where a zone of stereoplasma is developed, soldering 
together the outer regions of the septa where they arise from the wall. The lower part 
of the calicle devoid of stereoplasma or other fillmg. The columella composed of several 
flattened pillars. 
The coral, for which this genus is formed, is evidently nearly allied to Duncana,’ 
but differs in its much thinner epitheca, in the restriction of the stereoplasma to the 
marginal region, in the absence of paliform lobes to the septa, and in the hexagonal 
arrangement of the septa being comparatively little obscured. Lindstrom found in a 
thin section of the apex of a Duncania six septa of the first order distinctly marked.’ 
Pleurocyathus brunneus, n. sp. (Pl. I. fig. 1, ¢-c). 
The corallum is in the form of a short straight cone. It is attached by a broad 
adherent surface situate on one side near the apex. The external surface is covered 
with a rough brown epitheca which is extremely thin and has a pellicular appearance. 
1 British Zoophytes, 2d ed., 1846, p. 196. 2 Pourtalés, Ill. Cat. Mus., Harvard, No. 8, p. 45. 
3 Actinology of the Atlantic, p. 13. 
