XXIV PROCEEDINGS OF TJIE GEOLOGICAL SOCIETY. 



lished * A Succinct Account of the Lime Rocks of Plymouth.' Pre^- 

 viously to his researches, doubts were entertained whether that lime- 

 stone was fossiliferous. Thus, in the above letter to Mr. Warburton, 

 Mr. Hennah says, '' It has hitherto been a point in dispute whether 

 the limestone at Plymouth does or does not contain organic remains." 

 He probably had not then read the 'Illustrations of the Huttonian 

 Theory,' for otherwise he would have seen that Mr. Playfair had, 

 twelve years before, discovered a shell in the limestone, at the very 

 spot from which he was then writing. In accordance with a funda- 

 mental principle of that theory, that all the strata, even the most 

 ancient, are composed of the detritus of pre-existing rocks, Dr. 

 Hutton maintained that organic bodies might be discovered in what 

 in those days w^ere called the primary strata ; and Mr. Playfair, in 

 his 'Illustrations,' announces ( and he appears to have considered it a 

 triumphant proof of the soundness of that principle) his discovery of 

 a shell in the limestone at Plymouth. He thus describes it: — " On 

 the sea-shore, on the east side of Plymouth Dock, opposite to Stone-p 

 house, I found a specimen of schistose micaceous limestone, con- 

 taining a shell of the bivalve kind : it was struck off from the solid 

 rock, and cannot possibly be considered as an adventitious fossil. 

 Now, no rocks can be more decidedly primary than those about Ply- 

 mouth, Though, therefore, the remains of marine animals are not 

 frequent among the primary rocks, they are not excluded from them; 

 and hence the existence of shell-fish and zoophytes is clearly proved 

 to be anterior to the formation even of those parts of the present 

 land which are justly accounted the most ancient*." M. De Luc 

 visiting Plymouth in ] 805, writes thus : — " There I saw the section 

 of the strata of a limestone much resembling the most ancient second- 

 ary limestones of the Alps, which contain but very few marine bodies ; 

 I observed none in this stone f." Dr. Berger and M. Louis Albert 

 Necker visited Plymouth in 1810, and Dr. Berger thus speaks of the 

 limsetone, in his paper published in the 1st volume of the First 

 Series of our Transactions, p. 103 : — "At Plymouth the cliffs on the 

 shore are of limestone, which I examined leisurely. I did not dis- 

 cover in it any impressions of organic bodies, and I did not hear that 

 they have ever been found in it; at least, if any do exist, they are 

 very scarce." Dr. Thomas Thomson sought carefully for them, but 

 without success ±. Yet these rocks belong to that series which, under 

 the division called " Plymouth Group," Mr. Phillips, in his work on 

 the Palaeozoic Fossils of the counties of Cornwall, Devon, and West 

 Somerset, describes as containing 28 species of Corals, 9 species of 

 Crinoidea, 120 species of Shells, and 9 species of Crustacea. No 

 doubt the far greater proportion of these bodies are from localities 

 where they are not only abundant, but could not be missed by even 

 a casual observer ; for in one quarry alone, at Newton, Mr. Austen 

 found 139 organic forms specifically distinct, which he has described 

 in a memoir in the 6th volume of our Transactions. It is true, that 



* Page 164. f Geological Travels, ii. 342. 



i Annals of Phil. vol. ii, p. 248, 1813. 



