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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 16, 



ment of these rocks more nearly resembles that of Westmoreland than 

 that of the typical country of Siluria. I believe also that the distri- 

 bution of the fossils, through the subordinate divisions of these rocks 

 in South Wales, agrees more exactly with their distribution in West- 

 moreland than it does with their distribution in Siluria — proving 

 that (within the narrow limits of our island) the distribution of 

 fossils through subordinate groups depends far more on physical 

 conditions than on geographical latitude. The highest group (or 

 " Tilestone") contains, in South Wales, a very fine series of fossils, 

 the greatest part of which occur also among the grits, slates and 

 flags of Kirkby Lonsdale, and in the ridges between Kendal and the 

 lower valley of the Lune. 2ndly, With many points of most intimate 

 resemblance between the Upper Silurian groups of Westmoreland and 

 South Wales, there are points of specific diflference worth notice. 

 Thus the Cardiola interrupta has a much greater vertical range in 

 this part of South Wales than it has in Westmoreland. Again, in 

 these two widely-separated localities, the Terehratula Navicula com- 

 mences nearly on the same horizon. In Westmoreland it does not 

 ascend into the Upper Ludlow series south of Kendal ; but in this 

 part of South Wales the species ascends through the whole Upper 

 Ludlow series, and abounds even among the red flags of the " Tile- 

 stone," close to the base of the Old red sandstone. My limits forbid 

 me to follow these points of diiFerence and resemblance any farther. 



Groups of the whole Cambrian Series^ including both North and 

 South Wales. 



Westmoreland. 



Carboniferous. 

 Old Red 



Upper Silurian 



Lower Silurian J 



Upper Cambrian 

 Slates 



Snowdonian Group 



Tremadoc Group. . 

 Crystalline Slates. . 



Carboniferous. 



Upper Silurian. 



Coniston Limestone. 



Lower Silurian. 



Cumbrian Slates. 



Skiddaw Slate. 



