ETHEEIDGE — DEVONIAN ROCKS AND FOSSILS. 639 



ticulars physically resemble those of Lynton ; but their identity 

 stratigraphically (or by position in time) is impossible; and the 

 second assertion, as to complete identity of species or organic 

 contents, is an error ; the only species out of the 18 known in 

 the Lower or Lynton series (in the Lynton area) and common to 

 it and the Carboniferous Slate to the south, or in any area, are 

 two — FenesteUa antiqua* and CJwnetes sordida or Hardrensis, a 

 species still doubted by Mr. Davidson — and this admitting that the 

 Barnstaple fossils are Carboniferous. No other forms pass up from 

 the Lower Devonian to the Carboniferous, and no others are common 

 in the IN'orth Devon area ; and we must in this case, when absolute 

 identity of rock-masses is stated to exist, compare the species that 

 occur in each. Succeeding Tables will show their relation, when all 

 the known Carboniferous species of North Devon will be compared 

 with the three groups of the Devonian in the same area. It was 

 necessary to show the palceontological relations of the species in 

 these Lower Devonian rocks to the Silurian below on the one hand, 

 and to the Carboniferous above on the other, as one amongst other 

 proofs or e\ddence of their intermediate position and distinct charac- 

 ter, and of their having, as I have stated, only one species com- 

 mon to the two systems. The gradual addition to the known number 

 of species in the Middle and Upper Devonian rocks will show a 

 marked relation to the succeeding Carboniferous ; for of the 495 

 known species in the Old Eed and whole Devonian, 57 are also 

 found in the Carboniferous ; these 57 species will also be com- 

 pared in their proper place when I treat of the relation of the two 

 groups to each other. 



I have thus endeavoured to draw some comparison between the 

 community of species in the Lower Devonian and Silurian rocks, also 

 of those in the Lower Devonian of the North Devon area with the fos- 

 sils of the Lower or Spirifer-sandstones &c. of the Rhine ; and also, 

 preparatory to further analysis, I have stated the relation which the 

 Lynton Group bears to those rocks above the Pickwell-Down and 

 Baggy series, which have been asserted to be of the same age. I 

 now pui-pose analyzing the species that occur in the Middle Devonian 

 or Ilfracombe Group. 



3. Middle Devonian or Tlfracombe Group. — In the slates and lime- 

 stones, and occasionally the gritty beds, chiefly (in North Devon) at 

 and near Combe Martin, Watermouth, Widmouth, Hagginton, and 

 Ilfracombe, a large assemblage of Middle-Devonian species occurs ; 

 73 known forms are distributed through the slaty and calcareous 

 rocks of this group ; and 35 of these occur in one or other of the 

 three European areas selected for comparison. Thus nearly 46| 

 per cent, are common to the Middle Devonian strata of Britain and 

 Europe. Doubtless a still closer relation will be found to exist when 

 other groups of fossils have been as extensively studied and accu- 

 rately worked out as the Brachiopoda and Coelenterata ; for of the 



* One of the most doubtful species in the Devonian Eocks ; in nine cases out of 

 ten it occurs only in the form of moulds and casts ; and the I'olyzoa are, of all 

 other groups, when required for the identification of beds, the most deceptive. 



