DEVONIAN AND OLD RED PERIOD. 



141 



the enclosing rock in the boldest relief, exhibiting to the ob- 

 server the most minute details of their organisation. As before, 



Fig. Bi.ZaMrmfts comicula, of the 



natural size. Devonian, America, (Ori- 

 ginal.) 



Fig. Ho. Cystipkyttum vesiculosnm, 

 showing a succession of cups produced by 

 budding from the original coral. Of the 

 natural size. Devonian, America and 

 Europe. (Original.) 



Fig. te.Heliot>JiyIlnm exigimm, view- 

 ed from in front and behind. Of the natu 

 ral size. Devonian, Canada. (Original.) 



the principal representatives of the Corals are still referable to 

 the groups of the Rugosa and Tabulata. Amongst the Rugose 

 group we find a vast number of simple "cup-corals," generally 

 known by the quarrymen as " horns," from their shape. Of 



