FOSSIL SEA-MATS. 



219 



species in superabundance is the " Coralline " Crag, 

 which took its geological name from their numerical 

 abundance, in the early zoological days when sea- 

 mats and sea-firs (Hydrozoa and Polyzoa) were 

 grouped together as " corallines." 



Fig. 185. Dlastopora ventricosa; NS (natural size). 



The "re-deposited" Coralline or White Crag is 

 best seen in the neighbourhood of Aldborough and 

 Orford, in Suffolk, where it is about eighty feet thick, 

 and of a pretty cream-colour. The fossils in this 

 bed are abundant, but every one is encrusted with a 



