SUBCLASS I 



TETRACORALLA 



87 



(lumerous. An iiiterior wall is present ; tabulae are developed in the central 

 ;irea, while the peripheral zone is filled with vesicular tissue, Silurian (A. 

 (Dianas Linn. sp.) and Devonian. 



PhiUipsastrea d'Orbigny (Fig. 119). Astraeiform colonies, with indi- 

 vidual corallites united by confluent septa, which are produced beyond the 

 theca, and obscure the same. Interseptal loculi filled with vesicular endotheca. 

 Devonian and Carboniferous. Type, P. hennahi (Lonsd.). 



Stauria E. and H. (Fig. 120). Astraeiform or bushy composite coralla. 

 Septa well developed; the four principal septa characterised by larger size, and 

 forming a complete cross in the centre of each corallite. Silurian (Wenlock). 



Columnaria Goldf. (Favistella Hall). Astraeiform Stocks, composed of 

 long, polygonal, thick-walled corallites. Septa radially arranged in two cycles, 

 alternately long and short, barely reaching the centre. Tabulae horizontal, 

 disposed at regulär intervals apart, and stretching across the entire visceral 

 Chamber. Dissepiments imperfectly developed or absent. Ordovician to 

 Devonian. 



Ileterophyllia M'Coy. Carboniferous. Batiersbyia E. and H. Devonian. 



Family 5. Oystiphyllidae Milne Edwards and Hainie. 



Usually simple coralla. Septa very thin ; interseptal loculi filled with vesicular 

 endotheca or compact stereoplasma. Tabulae absent ; central area of visceral Chamber 

 either completely filled with vesi- 

 cular tissue or stereoplasma, or 

 containing the same only in the 

 lower portions of Chamber. Cal- 

 careous operculum sometim,es 

 present. 



Cystiphyllum Lonsd. (Figs. 

 121, 122). Simple, very rarely 

 forming bushy colonies. Calice 

 deep; the entire visceral Cham- 

 ber filled with vesicular tissue, 

 which, as a rule, wholly 

 obliterates the numerous radi- 

 ally directed septa. Silurian 

 and Devonian. 



Strephodes M'Coy (Fig. 

 123). Usually simple coralla. 

 Septa well developed, alter- 

 nately long and short, some- 

 times forming a pseudo- 

 columella. Silurian to Carbo- 

 niferous. 



Goniophyllum E. and H. 

 (Fig. 124). Corallum simple, in the form of a four-sided pyramid, and 

 covered with thick epithecal tissue. Calice deep ; septa numerous, thick 

 and very short. Entire visceral Chamber filled with vesicular and stereo- 

 plasmic endotheca. Operculum composed of four plates symmetrically 

 paired. Silurian. 



Fig. 121. 



Fig. 122. 



Cystiphyllum cylindricum 



Lonsd. Silurian ; Iron Bridge, 



Cystiphyllum vesiculosum England. A, B, Transverse 



Goldf. Devonian ; Eifel. and longitudinal sections (after 



Natural size. Nicholson). 



