SUBCLASS III 



TABULATA— FAVOSITIDAE 



115 



or elliptical in contour, lower surface covered with concentrically striated 

 epitheca, and frequently a foreign vermiform body occupying the ceiitre of the 

 base. Corallites small, polygonal, contracted inferiorly so as to become 

 funnel-shaped. Septa represented by faint marginal ridges, or obsolete. 



Fig. 179. 



A, Alveolites suborhicukiris L&m. Middle Devonian ; Gerolstein, Eifel. 

 Natural size. B and (', Alveolites lahechei E. and H. Silurian (Wenlock) ; 

 Ironbridge, England. Tangential and vertical sections, lo/j (after Nicholson). 



Fig. 180. 



Pleurodicty u m prohlemaiicum, 

 Goldf. Lower Devonian ; Co- 

 blenz. Natural size. Vermiform 

 foreign body in the centre. 



Walls pierced by irregularly distributed mural pores ; tabulae sparse. 

 Devonian. P. prohlematicum Goldfuss, is rather abundant in the Lower 

 Devonian " Spirifera sandstone " of the Eifel, but is known only in the form 

 of casts. In these the walls of the corallites are represented by narrow 

 fissures which are bridged across by transverse rods, while the visceral Chamber 

 is filled up with sandstone, P. stylopora Eaton, from the Hamilton Group of 

 North America, is a closely related species and also possesses the vermiform 

 body. 



Ä B C 



Fig. 181. 

 Michelinia fuvosa de Kon. Carboniferous Limestone ; Tournay, Belgium. A, Corallum fronl above. B, 

 Lower surface with radiciform epithecal processes. C, Vertical section (after Gaudry). 



Michelinia de Kon. (Fig. 181). Discoidal or hemispherical coralla, often 

 of considerable size, and covered on the under surface with concentrically 

 striated epitheca, which frequently develops hollow radiciform processes. 

 Corallites polygonal, rather large. Septa represented by numerous longi- 



