724 Mr. Lonsdale on the Age of the 



Society in May and June, 1837. (Athenseum, 1836, p. 611, section, p. 612 ; Reports of British 

 Association, vol. v., p. 93 ; Geol. Proceedings, vol. ii., p. 560.) 



Mr. Phillips, in his work on Geology forming vols, xcvii. and cxi. of the Cabinet Cyclopedia, 

 describing the fossils of the primary class (including the transition or grey wacke series), states that 

 " the Plymouth and South Devon shells, supposed to be identical with species of the mountain- 

 limestone, are in general, excepting perhaps some from Newton Bushel, quite distinct, as I learn 

 from a sight of Mr. Hennah's and other specimens" (vol. i. (xcvii.) p. 140). 



In Mr. Austen's communication, read December 1837, the limestones were described as oc- 

 curring in the uppermost portion of the transition or greywacke series of South Devon ; but he 

 expressed verbally his belief that they were the equivalents of the mountain-limestone; and he 

 called attention to some fossils which he thought would bear him out. (Geol. Proc vol. ii. p. 584.) 

 It was immediately after the reading of that paper, and partly from an examination of Mr. Austen's 

 specimens, that I formed the opinion relative to the limestones of Devonshire being of the age of 

 the old red sandstone ; and which I afterwards suggested first to Mr. Murchison and then to 

 Prof. Sedgwick, and at a later period, in 1838, to Mr. De la Beche and other Fellows of the So- 

 ciety. 



Mr. Eakewell considers these calcareous formations as belonging to the lower transition lime- 

 stones. (Introduction to Geol., 3rd edit., p. 136, 1838.) 



Mr. De la Beche's valuable Report on Cornwall and Devonshire appeared early in 1839. In 

 this work, the limestones, with the associated clay-slates, are placed in the greywacke group (p. 64, 

 et seq.). With reference to the lists of fossils, given on the authority of Mr. James Sowerby, Mr. 

 De la Beche says, " Organic remains have been detected, more particularly near Newton Bushel 

 and Ogwell, among which many shells bear so great a resemblance to others detected in the true 

 carboniferous or mountain-limestone, that at a first glance they might be considered of the same 

 species. How far they may bear that careful scrutiny to which they will probably be subjected, 

 remains to be seen. In the mean time, however, the near approximation to form, supposing, 

 for the sake of argument, that it is merely a near approximation of those shells to species well 

 known in the true carboniferous limestone, is a subject of considerable interest " (p. 75). " There 

 is nothing in the shells found in the Plymouth limestones, which should prevent us from consider- 

 ing them a continuation of the beds of Newton Bushel and Torquay." * * * << On the contrary, 

 an approach to, if not an identity with, forms of shells discovered generally in the true carbonife- 

 rous limestone, seems characteristic of the two localities." " Now, whatever doubt may exist as 

 to the true age of the Newton Bushel and Torquay limestones, the position of the Plymouth lime- 

 stones is clearly amid the slates and sandstones of South Devon, and whatever geological age be 

 assigned to the latter would appear to be common also to the former " (p. 76). 



" Those," Mr. De la Beche adds, " who rely very exclusively on the character of organic re- 

 mains, would probably feel disposed to consider the Torbay and Plymouth beds as equivalent to 

 some such rock as the old red sandstone " (p. 150 ; see also note, p. 149). 



In March 1839, Prof. Sedgwick and Mr. Murchison adopted their present classification of the 

 older sedimentary rocks of Devonshire and Cornwall, partly on the suggestion respecting the age 

 of the South Devon limestones, partly from a re-survey of the country to the south of Dartmoor 

 by Professor Sedgwick, and partly in consequence of an examination of the fossil evidence then 

 determined by Mr. Phillips, Mr. James Sowerby, and the author of this notice. The change 

 in their views they announced in a paper in the Philosophical Magazine and in a memoir read to 

 this Society. In both these documents the most unequivocal testimony is borne to any claim of 



