OF DENISON UNIVERSITY. 1 29 



the lamellc^ along the calyx are low, not reaching into the calyx, and 

 instead of small transverse leaflets between the disseppiments as in 

 Cyathophyllum, there are only minute pits. They however belong to 

 that class of fossils typified by CyatJwphyllum and form a connecting link 

 with Zaphrcntis. 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. 



CVATHOPHVLLUM PATULA, Sp. fl. 



(Plate y.l\l, Figs. 9, 10, 11.) 



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 

 radius 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 

 entirelv 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 tins 

 curvature is even and rounded, often it is more or less irregular and 

 broken by stri^ 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 11 mm. from 

 the apertural gap and 16 mm. from the central gap. It may b. 

 noted that in all corals of this group I have examined the side ol 

 greatest curvature was always on that of the apertural gap, and that if 



