OF DENISON UNIVERSITY. 
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the lamellae along the calyx are low, not reaching into the calyx, and 
instead of small transverse leaflets between the disseppiments as in 
Cyaihophyllum, there are only minute pits. They however belong to 
that class of fossils typified by Cyathophyllum and form a connecting link 
with Zaphrentis. The pits may be said to represent the spaces between 
the disseppiments in Cyathophyllum, and the denticulations in the last 
two species, the coarser denticulations of the sub-genus Heliophyllum. 
We think it convenient to establish another subgenus for these 
aberrant forms and as such suggest Palceocyathus. 
CYATHOPHYLLUM PATULA, Sp. n. 
{Plate 'Zlll, Figs. 9, 10, ii.) 
Polyp very much much broader than long. One at hand is 10 
mm. high, 35 mm. broad in one direction, and 29 mm. broad in a 
direction at right angles with the last. Another specimen was 8 mm. 
high, 42 mm. broad in one direction, and about 34 mm. at right 
angles with this. A third specimen was about 9 mm. high and 22 
mm. broad. So that the variation is evidently a matter of breadth 
more than that of length. The shape of the polyps would indicate as 
much. For a distance of about 8 mm. from the centre the base of 
the polyp shows its greater convexity, or rather, increase in hight, 
and this is also the thickest part of the polyp itself. Beyond this 
raclius it rapidly grows thinner, its thickness usually being 2 mm. or 
less, so that in a large sized polyp there may be a thickened centre of 
about 16 mm. diameter and a very fragile border of 12 mm. or more 
entirely around the margin. This border is always flattened on the 
side of the central gap. The entire coral is always curved very 
decidedly upwards on the side of the apertural gap. Sometimes this 
curvature is even and rounded, often it is more or less irregular and 
broken by striae of growth. This difference in growth between the 
side at the central gap and that at the apertural gap places the centre 
of the coral always considerably closer to the apertural gap. In the 
first specimen above noted the centre of the coral is 1 1 mm. from 
the apertural gap and 16 mm. from the central gap. It may be 
noted that in all corals of this group I have examined the side of 
greatest curvature was always on that of the apertural gap, and that if 
