Limestones of South Devon. 727 



the Newton Bushel and other limestones would prove to be of the age of the 

 old red sandstone. 



It has been already mentioned, that the suggestion was first proposed in 

 December 183r. I had previously examined in part, the corals of the Silurian 

 system and of South Devonshire, and satisfied myself that some of the species 

 are common to both. I had also examined with Mr. James Sowerby, on its 

 first arrival in London, Mr. Hennah's valuable collection of fossils, and had 

 become aware, by the remarks of Mr. Sowerby, that certain of the shells, 

 found near Plymouth, could with difficulty, if at all, be distinguished from 

 mountain-limestone species, and that some were distinct. Immediately after the 

 reading of Mr. Austen's paper in December 1837, I had the pleasure of exa- 

 mining with that gentleman a part of his collection ; and though 1 ventured 

 to dissent from some of the identifications with mountain-limestone shells, 

 pointed out to me (Fkurorhi/nchus minax, Terebratula acuminata), yet the 

 fossils agreed so much in aspect with Testaceaof the carboniferous Fauna, that 

 it was impossible to doubt, that the beds from which the specimens had been 

 obtained, had some connexion with the mountain-limestone system. From an 

 examination of the collection, I also ascertained that in the same limestones 

 with these shells, occur corals common in the Silurian system. Through the 

 kind communications of Mr. Austen, I had likewise become aware that the 

 CalceoLa sandalina, a shell previously obtained only from districts on the 

 Rhine, and considered to be transition, existed in Devonshire in beds asso- 

 ciated with the limestones; and that he had obtained many new cephalopods 

 and other fossils from the same districts. 



It was therefore by combining together this evidence — the presence, in 

 the same series of beds, of shells resembling or identical with mountain-lime- 

 stone species, of Silurian corals, the CalceoLa sandalina, and various distinct 

 Testacea, — that I was induced to suggest that the South Devon limestones are 

 of an intermediate age between the carboniferous and Silurian systems, and 

 consequently of the age of the old red sandstone. It is necessary to add that 

 Mr. Murchison had shown that there is a regular passage from the old red sand- 

 stone upwards into the carboniferous system, and downwards into the Silu- 

 rian, and that the suites of fossils of the two systems are perfectly distinct. 



This amount of evidence would most probably have been insufficient for 

 minds disciplined to draw conclusions only from long-continued and rigidly 

 conducted researches, and have deterred their possessors from hazarding an 

 opinion on a disputed point ; but it is hoped, that, for once, a less commend- 

 able method of deducing a conclusion has not led to error. 



Appended to this notice is a list of fossils, somewhat hastily prepared and 



