students of the Coelenterata have found them very puzzling. McCoyÿ£¢15, their first discoverer, pronounced these corals to be ãtotally unlikeã any other group, recent or fossil; and Professor Martin Duncan, writing a memoir on Heterophyllia and its allies16, described them as ãparadoxical in their anatomy.ã
The simplest or youngest Heterophylliae known have six septa (as in Fig. 174, a); in the case figured, four of these septa are conjoined two and two, thus forming the usual triple junctions together with their intermediate partition-walls: and in the {389} case of the other two we may fairly assume that their proper and original arrangement was that of our type 6b (Fig. 158), though the central intermediate partition has been crowded out by partial coalescence. When with increasing age the septa become more numerous, their arrangement becomes exceedingly variable; for the simple reason that, from the mathôÙeôÙmatôÙiôÙcal point of view, the number of possible arrangements, of 10, 12 or