UPPER PALAEOZOIC FAUNAS 159 



(D) COELENTERATA 



The Devonian and Carboniferous periods included 

 reef-building episodes in Britain, but the Permian 

 deposits are unsuited for development or preservation of 

 Coelenterates. Tetracoralla and Tabulata were still the 

 predominant " Corals," but the former series tended to 

 outweigh the latter in importance, particularly in the 

 Carboniferous. The well-known Devonian u marbles " 

 of South Devonshire are largely built of Favositids, 

 Cyathophyllids and Heliolites. 



The most abundant genera of Devonian Tetracorals 

 are Cyathophylluni, Acervularia, Phillipsastraea and 

 Calceola (PI. xi. fig. i). Their facies is perhaps more 

 reminiscent of the Silurian than predicative of the 

 Carboniferous. The latter period is, as regards the 

 lower (marine) portions, zoned by evidence based 

 chiefly on Tetracorals. Relatively simple Zaphrentids 

 characterize the lower horizons of the Carboniferous 

 Limestone, while more elaborate Cyathophyllids, such 

 as Lonsdaleia and Lithostrotion (PL xi. fig. 2), prevail 

 at higher levels. Apart from a few possible Mesozoic 

 and Recent members of the group, the Carboniferous 

 Tetracoralla were the last of their kind. 



The "Perforate" section of the Hexacoralla is 

 sparingly represented in the Upper Palaeozoic by the 

 family Eupsammiidae (which arose in the Silurian and 

 persists at the present day). 



The Alcyonarian genus Heliolites ', which attained 

 considerable importance in Silurian reefs, maintained its 

 position in the Devonian, but is unknown from the 

 Carboniferous. 



Devonian Tabulata are familiar objects in polished 

 slabs of limestone, the Favositid genera Pachypora and 

 Alveolites predominating. The small and peculiar form 



