274 



ZOANTHARIA. 



vularia are of a different structure to A. ananas, and are referable to 



the Cyathophylloid group of the Rugosa. 



There does not, further, seem to be any sufficient reason for excluding 



the Ordovician genus Columnaria ( = Favistel Id) from the Astrceida. In 



this genus the corallum (fig. 153) is massive, and is composed of pris- 

 matic or polygonal coral- 

 lites, which are usually 

 more or less completely 

 united by their walls. 

 The septa (fig. 154, a) 

 are well developed, and 

 are lamellar in form, 

 each corallite contain- 

 ing about thirty of these 

 structures, disposed in 

 two cycles, and alter- 

 nately long and short. 

 The long septa are not 

 of equal length, one 

 being often much longer 

 than the others ; and 

 they fall short of the 

 centre of the visceral 



chamber, no columella being present. Endothecal tissue in the form of 



dissepiments is very imperfectly developed, but numerous tabulae (fig. 



154, b) are present. 



Finally, the remarkable recent genus Mosehya must be noticed 

 here. In this genus, as described by Mr Quelch, the corallum is 



Fig. 153. — A colony of Columnaria calicina, Nich., from 

 the Hudson River Group of Canada, of the natural size. 

 (Original.) 



Fig. 154. — Sections of a corallite of Columnaria calicina, from the Ordovician of North 

 America, enlarged ten times, a, Cross-section ; b, Longitudinal section, v, Primordial wall ; 

 s, Secondary layer of stereoplasma, the corresponding layer in the interior of the corallite being 

 shaded ; t, Tabulae ; r, Cut edges of septa. (Original.) 



composite, the only known specimen consisting of a single large coral- 

 lite, round which smaller corallites are produced by calicinal marginal 

 budding. The wall is very thin, with a slight epitheca ; and the septa 



