Physical Structure and older stratified Deposits of Devonshire. 693 



verbal descriptions. In the subjoined plates (PI. LII. to LVIII.) we have 

 therefore figured some of our best fossils. The figures and determination of 

 the fossil shells are all by Mr. James Sowerby : any notice we may take of 

 the corals will be given on the authority of Mr. Lonsdale. 



We might perhaps now content ourselves by simply giving a list of the fos- 

 sils derived from the respective deposits, and then leave the reader to draw 

 the proper conclusion from the facts before him ; but we think it advisable, in 

 the first place, to put our evidence in a more general and popular form. In 

 our previous paper, the successive groups are described in the ascending- 

 order in which we first observed them, during our traverse from the north to 

 the south coast of Devon. But in noticing the fossils, it is almost necessary 

 (as our sections have no well-defined base) to take a reversed order, and com- 

 mence with the upper division of the culm-measures. 



1. Culm Measures. — In the first place, then, we have nothing to add to the 

 evidence given by the vegetable fossils of this upper division of the culm- 

 measures, or to the conclusions we drew from it. On this point, therefore, we 

 merely refer to our former communication (supra, p. 669, et seq.). The black 

 limestone of the lower division contains many shells of the genus Posidonia, 

 three or four species of Goniatites, and two or three other genera not yet well 

 ascertained. Now i\\e ^&\\n% Posidonia is found abundantly both in the upper 

 and lower limestone shales, of the true carboniferous series of England and 

 Ireland: for example, in the calp of Ireland, which is in the place of the lower 

 shales, and in the upper limestone shales of Northumberland, not far below 

 the millstone grit. There is a species in Northumberland, which makes a very 

 near approach to a species very abundant in the black culm limestone. Again, 

 of the Goniatiles of the culm limestone, there are three species very closely 

 related to those of the mountain limestone*. Among them is one which Pro- 

 fessor Phillips is unable to separate from the G. Henslowi, found in the great 

 scar limestone of the Isle of Man ; and it deserves remark that this species 

 occurs also in the Petherwin group, below the culm-measures, — a fact which 

 tends to prove the reality of a passage from the base of culm-measures into 

 the next inferior group. 



Where then shall we place the culm limestone, and carbonaceous shales 

 that form a part of it ? If we arrange them with the upper shales of the moun- 

 tain limestone, then nearly the whole culm-trough of Cornwall and Devon will 

 be the equivalent of the middle and upper divisions of our true carboniferous 

 series. This view was adopted by Prof. Phillips when he published his index 

 map of the British Isles. But if we identify the black, calcareous, culm shales 



* Ueport on the Geology of Coi-nwall, &c. p. 117. 



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