86 



OUR COMMON BRITISH FOSSILS. 



in limestone countries, so weathered that it stands out 

 in high reHef. This coral is not only abundant where- 

 ever the Carboniferous limestone occurs in Great 

 'Britain, but it is also distributed through the strata 



Fig. 64. — Fossil Coral {Dil>!e!ioJ>h'jniun). 



Fig. 65. — ZapJtT-eiitis. 



from the bottom to the top, although the smallest 

 specimens are usually found in the upper beds, and 

 the largest in the lower. The fact that it is plentifully 

 found where sJiale bands occur shows 

 that it affected shallow water, for shale 

 is a muddy deposit. At Swansea 

 Zaphrentis cylindacea occurs more than 

 one foot in length, and three and a half 

 inches in diameter. 



The genus Dibiinophylhim (Thomson) 

 differs from Zaphrentis in the structure 

 of its calycle or cup. This coral, and other genera 

 such as Rhodopkylhim, Koninckophyllnm.Aspidophylhim^ 

 Clisiophylluin, Histiophylliim, Cyclophylhtin, are found 

 most abundantly in the lower strata of the Scottish 



P'ig. 66. — Transverse 

 section of Zaphren- 

 tis, cut through 

 upper figure at the 

 point traversed by a 

 line. 



