i;8 HISTORICAL PALAEONTOLOGY. 



and joints of Sea-lilies, whilst perfect "heads" may be exceed- 

 ingly rare and difficult to procure. In North America the re- 

 mains of Crinoids are even more abundant at this horizon than 



Fig. 116. Corals of the Carboniferous Limestone, a, Cyathophyllumparacida, show- 

 ing young corallites budded forth from the disc of the old one ; a', One of the corallites 

 of the same, seen in cross-section -, b, Fragment of a mass of Lithostrotion irregulare; 

 &', One of the corallites of the same, divided transversely ; c, Portion of the simple 

 cylindrical coral of Amplexus coralloides; c', Transverse section of the same species ; 

 d, Zaphrentis vermicularis, showing the depression or "fossula" on one side of the 

 cup ; e, Fragment of a mass of Syringopora ramulosa; /. Fragment of Chcetetes 

 tumidus ; f , Portion of the surf ace of the same, enlarged. From the Carboniferous 

 Limestone of Britain and Belgium. (After Thomson, De Koninck, Milne-Edwards 

 and Haime, and the Author.) 



in Britain, and the specimens found seem to be commonly 

 more perfect. The commonest of the Carboniferous Crinoids 

 belong to the genera Cyaihocrinus, Actinocrinus, Platycrinus, 



