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XL VI. Notes on the Age of the Limestones of South Devonshire. 

 By WILLIAM LONSDALE, F.G.S. 



[Read March 25, 1840.]* 



XHE reasons which induced me to assume on zoological evidence, that the 

 limestones of Southern Devon, between Dartmoor and the coast, would prove 

 to be of the age of the old red sandstone, not having- been placed on record 

 in a separate form, Mr. Murchison has begged me to lay before the Society 

 a distinct notice of my claim to having been the first to propose the classifi- 

 cation recently put forth by Professor Sedgwick and himself; and in conse- 

 quence of an extension of those views to Belgium and the Boulonnais, Dr. 

 Fitton has urged me to comply with the request. In the memoirsf in which 

 Professor Sedgwick and Mr. Murchison announced the change in their classi- 

 fication of the older sedimentary strata of Devonshire and Cornwall, the 

 clearest and amplest acknowledgements are made of my share in promoting 

 the alteration; but as it is possible that some mistake may hereafter arise, re- 

 lative to the nature and limits of my suggestion, I conceive it is a duty to 

 others as well as to myself to comply with the above request. I regret, how- 

 ever, that I cannot make this notice as satisfactory as I could wish, from the 

 whole of the data not being accessible ; and I regret that my official duties 

 have prevented me from bestowing upon it that time and thought and re- 

 search which ought to be evident in the shortest communications read to this 

 Society. 



Before I state the nature of my claim, I consider myself called upon to give, 

 as far as I am able, a brief summary of the opinions previously entertained 

 by geologists respecting the age of the South Devon limestones, that the pro- 

 portionate amount of priority of claim may be duly estimated. 



Woodward (1729) and Da Costa (1757) notice the Plymouth marbles, but only as mineral sub- 

 stances ; (Woodward's Catalogue, vol. i. p. 20, xb. 4 ; vol. ii. p. 66, b. 18-21. Da Costa, History 

 of Fossils, p. 206.) 



* This communication is printed out of its regular order by direction of the Council, in conse- 

 quence of the subject to which it refers being connected with the Memoir of Professor Sedgwick 

 and Mr. Murchison on Devonshire. 



{- Lond. and Edin. Phil. Mag., April 1839 ; ante, p. 688, et seq. 



