Davidson — Earliest British Brachiopoda. 



305 



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Llandeilo 

 Flags. 



Lower. Upper 





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Arenig or 

 Skiddaw 

 Group. 



Lower 

 Llandeilo. 



Lower. Upper 



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Tremadoc 

 Group. 



(Salter.) 



Tremadoc 



Slates. 

 (Murchi- 

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11 



Dolgelly 

 Group. 

 (Belt.) 

 Upper 



Lingula 

 Flags. 



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Maentwrog 

 Group. 

 (Belt). 

 Middle 

 Lingula 

 Flags. 







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Menevian 



Group. 



(Salter and 



Hicks.) 



Lower 



Lingula 



Flags. 























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: 



Harlech 

 Group. 



(Sedgwick). 



Upper 

 Longmynd. 

 (Murchison) 























• : : 







































Llanberis 

 Slates. 



Lower 

 Longmynd. 

 (Murchison) 





















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The black lines indicate the 



range of the species at 



present known. 



Species. 



Lingulella ferruginea, Salter. 



,, Davisii, M'Coy ... 



Icevis, Salter 



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1 





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1 





1 



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Discina pileolus. H icks 



Obolella Sagiitalis, Salter ... 



„ Belli, Dav 



,, maculata, Uicks 



? Salteri, Holl 



Kutorgina ciugulata, Billings 



„ =G. Phillipsii, Holl. 



Obolus } vhimbea. Salter 



„ y&x.plicata, Hicks.... 

 Acrotreta } Nicholsoni, Dav.. 

 Siphonotreta micula, M'Coy.. 

 Crania divaricata, M'Coy ... 

 Orthis lUcJcsii. Salter 



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 1 



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,, calligramma, Dal 



Leptcena sericea, Sow 



Strophomena compressa^ Sow. 



Meristella crassa, Sow 



Orthisina 



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