Tetracoralla

Tetracoralla, a name originally applied to all corals in which the septa are arranged in 4 or multiples of 4, instead of in 6 or multiples of 6, as in most recent corals. this arrangement has now been abandoned, and the term is used as a synonym of the group of corals known as Rugosa. These corals all have a tetrameral arrangement, but many others with the same character are assigned elsewhere, Thus, the recent Guynia of the West Indies and Holocystis elegans of the Lower Greensand are assigned to the Turbindidae and Astraeidae respectively; while the Silurian family of the Stauridae are now included in the Aporosa. Quelch, indeed, proposed to divide all the Tetracorolla among this order; but this seems to be too radical, and the corals seem worthy of retention in a separate group.