3G4 



PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Mar. r. 



The sandstones, both in Ireland and in North Devon, which 

 are interstratified with the grej-slates, vary greatly in thickness. 

 Near Bantry the Coomhola Grits are 3000 feet in thickness; in 

 many places near Cork 20 or 30 feet is the maximnm that could be 

 assigned to them, and they have no greater thickness at Kenmare, 

 which is not more than ten or twelve miles from Bantry Bay. That 

 similar variations in the thickness of the sandstone beds, and their 

 mode of interstratification with the slates should occur in Devon is 

 only what is to be expected. I would also remark, that though 

 there is not a minute lithological identity between the beds of the 

 Baggy Point country and those of the Lj^nton district, there is after 

 all no very great difference between them ; alternations of greenish 

 and greyish grits, with grey slates, prevail in both cases ; and if the 

 *' lie of the beds," and their circumstances of exposure were alike, 

 I believe their similarity of aspect would appear greater. 



The objections, then, arising from variations in Kthological cha- 

 racter in different localities a few miles apart cannot be accepted as 

 valid against the siipposition that they belong to the same group of 

 beds. 



c. The palseontological resemble the lithological objections, and 

 allow of a similar answer. 



There are fossils in the Lynton and Combe-Martin district which 

 are not known in the Baggy Point and Barnstaple district, and vice 

 versa ; but there are also fossils which are common to the two dis- 

 tricts. If the lithological variations are admitted, some palaeonto- 

 logical difference may be expected to follow as a matter of course. 



In Ireland, where the Carboniferous Slate forms one physically con- 

 tinuous area, and where its lithological structure is simpler than in De- 

 vonshire, many fossils are peculiar to parts of that area, some species 

 only occurring in one or two localities. (See Mems. of Geol. Survey, 

 Explanations of sheets 187, &c., and 192, &c. of the Irish maps.) 



It may, then, be reasonably expected, even when all the species 

 are collected, that different species will occur in the same beds in 

 different parts of Devonshire. I refrain from entering into a discussion 

 respecting species of fossils in which my own knowledge would not 

 allow me to take any part except at second-hand, but I may be al- 

 lowed to mention the following list of species which I find given 

 by palaeontological authorities as common to the districts north and 

 south of the central band of Old Eed Sandstone in North Devon. 



Species. 



South. 



North. 



Authority. 



Cyatliopliyllum {Turbinolo;psis, 

 Petraia) pluriradiale 



Fenestella antiqua 



1 Brushford ... 

 rPilton 



Lynton 



Phillips. 



Lynton ] 



Lee I 



Woodabay ... J 

 Lynton 



" Croyde. 



Actinocrinus tenuistriatus 



Cyathocrinus variabilis 



Pleurotomaria aspera 



Brushford ... 

 Pilton 



Pilton 



Lynton 



Pilton. . 



Woodabay .... 







