341 



system was not then published, and thus only one of the two terms 

 necessary for comparison was known." 



Such was the state of the question Avith regard to the South 

 Devon limestones when Lonsdale turned his attention to it. At p. 

 726 he says — " I will now state briefly the Zoological evidence on 

 which I assumed that the Newton Bushel and other limestones 

 would prove to be of the age of the old red sandstone. He mentions 

 certain collections of fossils which he had inspected, and then says 

 — " It was, therefore, by combining together this evidence, the 

 presence in the same series of beds, of shells resembling or identical 

 with mountain limestone 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 intei-mediate age 

 between the Carboniferous and Silurian systems, and consequently 

 of the old red sandstone." Murchison and Sedgwick supported 

 this suggestion, and the independence of the Devonian system was 

 recognised. How the Devonian rocks have continued to be subjects 

 of controversy all geologists know. 



