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BULLETIN OF THE LABORATORIES 
anywhere a concave curvature took place it appeared strongest near- 
est the base of the coral on the side of the central gap. Exteriorly 
the coral is marked by the radiating costse, by lines of growth, which 
usually are not very prominent nor closely set, and by much finer con- 
centric striae, best seen by aid of the magnifier. Interiorly the polyp 
is seen to be composed of a large number of lamellae, among which 
there is very little increase by intercalation, this usually taking place 
through successive implantations at the various gaps. As might be 
judged from the thinness of the coral, the lamellae are not very much 
raised above the epithecal covering. Excepting near the center they 
are little more than low ridges. At the center they seem to be slighlly 
twisted together and to be slightly depressed, forming a narrow shallow 
cup ; our specimens do not show this part well. The number of the 
lamellae of course varies with the breadth of the specimen. In the 
first specimen mentioned there were about 130; the average is 12 or 
13 along the margin in a distance of 10 mm. A cross section near 
the center of the coral shows that at this point the lamellae are thin 
and are crossed by vesicular tissue. The lamellae along the sides 
are much indented in a manner similar to that characteristic of the 
subdivision of this genus known as Heliophyllum. I however know of 
no form of this genus which has any resemblance to this species. 
Like the species last described it forms an interesting aberrant varation 
of the genus. 
It will be noticed that S. G. De Koninck quoted Ptycophyllum 
patellatiun, Schlosheim from Dangelong. This is a species very 
similar in form, may however be ever be superficially distinguished by 
the fact that it has conspicuous elevations of long and short lamellae, 
and that these begin to be twisted already at a short distance from 
the centre. 
CYATHOPHYLLUM BOLONIENSE, Blainvilk} 
{Plate Fig. 15 .) 
Corallum composed of numerous polygonal polyps. Polyps 
typically five or six sided, but often with four, seven, or eight sides 
