PE^GELLY — rOSSTLS Of DEYO^^ AT^D COKNWALL. 31 



fore, that the Barnstaple beds are somewhat more modern tlian those 

 of Petherwin. 



TABLE XII. 



GrENEEA. 



J: • 





C. 





1 





5 



Cyathocriuiis 



1 



"3 



10 



Pentretnites 





1 



11 



Glauconome 





1 



5 



Fenestella 



i 





19 



Chonetes . 





2 



16 



Productus 



"i 



3 



48 



Modiola 



1 





16 



Axiiius 



1 





9 







"1 



9 







4 



14 







2 



15 





B 



1 



14 







1 



16 



Nautilus 



1 





40 





10 



19 



247 



We are prepared, by even a slight acquaintance with the geogra- 

 phical distribution of existing organisms, to find that deposits strictly 

 contemporary, lithologically similar, and closely connected geographi- 

 cally, have certain fossils peculiar to each ; but, unless we recognize 

 time as a factor, it will be difficult to explain the following striking 

 results in Petherwin and Barnstaple. Together they have yielded as 

 many as one hundred and thirty-one species of fossils, yet have no 

 more than seventeen in common ; the fossils belong to forty-six 

 genera, of which twenty-five are confined to one or other of the two 

 areas, having amongst them the rich genus CJymenia, with its eleven 

 species all closely restricted, in Britain, to Petherwin, yet occurring 

 in continental Europe. The remaining twenty-one genera are re- 

 presented by eighty-six species, but tlie representatives are rarely 

 identical in the two areas, the peculiar being to the common as 

 69 to 17, that is, as 4 to 1. Contend that these beds are strictly 

 contemporary, and the facts remain to puzzle ; grant but the lapse 

 of time, and, at least, part of the difficulty disappears, and thereby 

 furnishes another argument in favour of the opinion now advocated. 



Returning for a moment to Tables X. and XI., it will be seen that 

 the Barnstaple have a smaller number of fossils in common with the 

 Lower Devonian, and even the Petherwin beds, than with the Carbo- 

 niferous ; hence they may be considered as belonging rather to the 

 last than to the Devonian series, or, possibly, may have to be re- 

 garded as " passage beds " between them. 



