136 



The order Alcyonaeia is represented in the Silurian rocks 

 by the singular family of Graptolites, which are special to 

 this period. 



Geaptolithid^ 

 Gh-aptolithus . Gladogra/psvs 



Rastrites Diclymograpsus 



Diprion Gladiolites 



Devonian Corals, 



The Devonian series of North Devon, as exposed in the coast 

 section on the Bristol Channel between Barnstaple and the 

 North Foreland, consists of the 



Upper or Pilton group. 

 Middle or Ilfraconibe group. 

 Lower or Linton group. 



The Pilton group is composed of (a) calcareous brown Slate, 

 with fossils resembhng those of the Carboniferous Limestone' 

 above ; and (b) brown and yellow Sandstone, with marine shells 

 and land plants. 



The Ilfracombe growp of hard, grey and reddish Sandstones, 

 and micaceous flaggy beds without fossils, resting on a 

 considerable thickness of soft, greenish Schists ; these overlie 

 calcareous Slates, with eight or nine courses of Limestone, full of 

 shells and Corals. We here find Favosites polymorpha, 

 Cyaihophyllwm coespitosum, and other species. 



The Linton group consists of hard red, green, and purple 

 Sandstones, with a few fossils, overlying soft chloritic Slates and 

 Sandstones, containing Brachiopoda and Corals. 



The Limestones of Newton Bushel, Torquay, Plymouth, and 

 Ilfracombe have yielded the most abundant supply of fossil 

 Corals; unfortunately, however, the structure of these organisms 

 is so entirely filled in with the calcareous matrix, and so 

 completely imbedded in it, that we can only study the species 

 in cnt and polished specimens. 



