RUG OS A. 



215 



corallite possesses a central circular space, invested by a 

 secondary and interior wall. Strombodes (figs. 108 and 109), 

 of the Silurian, is very like 

 Acermdaria, but the walls of 

 the corallites are imperfectly 

 developed, and the tabulae are 

 funnel-shaped and invaginated 

 in one another. Phillipsastrcea, 

 again, approaches Strombodes in 

 appearance, but the calices are 

 not distinctly circumscribed (fig. 

 101); the walls of the coral- 

 lites are deficient ; and the cor- 

 allites are united by the fusion 

 of their septa. The genus is 

 Devonian and Carboniferous. 



As the type of another group 

 of the Cyathophyllinoe, we may 

 select the great genus Liiho- 

 strotion (fig. 110), so highly 

 characteristic of the Carbonifer- 

 ous deposits in almost all parts 



of the world. The corallum in this genus is compound and 

 fasciculate or massive, composed of cylindrical or prismatic 

 corallites, which may or may not be in close contact with 

 one another. The corallites possess a central tabulate area, 

 which is traversed by a well-developed styliform coluniella. 

 The genus Diphyphyllum, ranging from the Silurian to the 

 Carboniferous, closely resembles the fasciculate forms of 

 Lithostrotion, but the corallites have no coluniella. The 

 Devonian genus Eridophyllum, again, differs from Diphy- 

 phyllum, principally in the fact that the corallites are united 

 by horizontal connecting-processes. Lastly, the genus Lons- 

 daleia (figs. 74 and 111 A), of the Carboniferous rocks, 

 presents some resemblance to the massive and astraeiform 

 species of Lithostrotion, but the corallites have a secondary 

 or inner wall, enclosing a central area, and the columella is 

 formed of twisted lamellae. 



Lastly, we must mention here a great group of Cyatho- 



Fig 110. Fragment of a mass of Litlin- 

 strotion irregulare, of the natural size. 

 Carboniferous. (After De Koninck.) 



