THE BRITISH FOSSIL BRACHIOPODA. 



393 



Middle Oolite 

 Corallian 



Oxfordian .... 



Lower Oolite 



*Upper calcareous grit. 



* Coralline Oolite and Coral-rag. 



* Lower calcareous grit. 



* Oxford clay. 

 *Kelloway rock. 



f *Cornbrash. 



* Forest-marble and Bradford clay. 

 *Great or Bath Oolite and Stonesfield slate. 

 *Fuller's-earth Oolite. 

 *Inferior Oolite and sands. 



* Upper Lias clay and sand. 

 Lias \ *Marlstone and shale. 



*Lower Lias clay and limestone. 

 *Rha3tic or Penarth beds. 



Variegated Marls or Keuper (Muschelkalk absent in 

 En-gland). 



Red sandstone or Bunter. 



Pal (so zoic or Primary. 

 /- Red sandstone and marl. 

 \ *Magnesian limestone. 

 j *Marl-slate. 

 ^ Lower red sandstone. 

 /-*Coal-measures. 

 \ *Millstone-grit. 

 1 * Mountain-limestone. 



*Limestone-shales. 

 r *Upper Devonian. 

 < *Middle Devonian (limestone). 

 v *Lower Devonian. 

 ^*Ludlow and Aymestry rocks. 



*Wenlock limestone and shale. 



5 ,„ r ., . ( Denbigh grits. 



* VV oolhope series < m , , 

 C larannon shale. 



(^*Upper Llandovery (May Hill rocks). 



T ( Lower Llandovery. 



Lower \ J 



*Caradoc and Bala rocks. 



*Llandeilo rocks (Skiddaw and Arenig beds). 



r *Tremadoc beds and Lingula-flags. 



Cambrian J *Menevian. 



v *Longmynd and Harlech rocks. 



Rh^etic 



Triassic 



{New Bed Sandstone) 



Permian 



Carboniferous 



Devonian 



{Old Red Sandstone) . 



Silurian 



Upper 



