W, A. E. Ussher — Deronian Rocks of Cornwall. 587 



over 1,600 feet below beds with a Vise fauna, and Prodiictus cora — 

 P. semireticulatus, and P. gigantens occur with it. So that whatever 

 may be the case at Bristol, it is abundantly plain that none of the 

 Brachiopoda quoted in Dr. Vaujiihan's paper run true over the Pennine 

 area in England, and on this account I consider them to be equivocal 

 as evidence for the correlation of the two areas ; and to repeat it, is 

 the fact that from Vise and Clavier in the east to co. Clare in the 

 west, the strata that immediately overlie the Carboniferous Lime- 

 stone are characterised by beds containing : — 



Posidonomya Becheri. Orthoceras Morrisianum. 



,, membranacea. Glyphioeeras cliaclema. 



Fosidoniella Icevis. ,, reticulatnm. 



,, ■ minor. ,, spirale. 



,, Kirlcmani. Prolecanites compress as. 



Pterinopeeten papyraceus. ,, mixolobus. 



Aviculopecten Losscni. Nomismoceras spirorbis. 



Pseudamtisimnfibrillosum. Bimorphoceras Gilbertsoni. 



Ghcenocardiola Footii. Gastrioceras carbonarium, 

 Orthoceras Kon'mckianum. 



and many others, none of which, as far as I know, occur in beds 

 below the Visean limestone. 



I think that Dr. Vaughan has greatly strengthened my case that 

 the Lower Culm beds of Devonshire and Cornwall are the homotaxial 

 equivalents of the Pendleside series, having emphasised evidence 

 which I neglected, and I think he will now admit that the Brachiopod 

 and Coral faunas of the Coddon Hill and Bishopton Beds and part of 

 the Pendleside series are identical. 



IV. — The Devonian Eocks of Cornwall. 



By W. A. E. UssHER. 



[By permission of the Director of H.M. Geological Survey.] 



SEDGWICK and Murchison, the Kev. D. Williams, and Dr. Holl, 

 taking the Plymouth limestones as a middle division, placed 

 them below the rocks to the south and above those to the north. 

 The prevalent southerly dips of schistosity were regarded as ample 

 evidence of a downward succession proceeding northward. 



The Staddon grits and other Lower Devonian rocks were thus 

 placed above the Middle Devonian, and the slates in wrhich I have 

 at various times since 1892 found Upper Devonian fossils (between 

 Menheniot and St. Budeaux) were relegated to a position below the 

 Middle Devonian. 



Turning from these more general readings of the geology to the 

 detailed work of De la Beche, as presented in Chapter iii of his 

 Eepoi't, we find that this comparatively simple rendering, though 

 fundamentally wrong, cannot be applied to Cornwall. 



As regards South-East Cornwall (see p. 79), the fossiliferous Looe 

 beds were said to be prolonged toward St. Germans and to become 

 merged in the trappean rocks, etc., of St. Stephens and Saltash, both 

 being considered as below the Plymouth (Middle Devonian) rocks. 

 The calcareous strata of the Tregantle coast (the same series as the 



