of the Older Stratified RocJcs of Devonshire and Cornwall. 247 



induced to suggest to us (now more than a year ago), that 

 the South Devon rocks would be found to occupy an inter- 

 mediate place between the carboniferous and the Silurian sy- 

 stems. The collection of Mr. Hennah was unfortunately mis- 

 sent to Cambridge, and was only unpncked very recently : 

 but upon its examination (within these few weeks) by one 

 of the authors, in company with Professor Phillips and Mr. 

 James Sowerby, the same general results were arrived at; 

 namely, the existence of some fossils undistinguishable from 

 certain forms of the carboniferous limestone, and others from 

 those of the upper Silurian rocks, while many were entirely 

 new. Again, the corals of this limestone being examined by 

 Mr. Lonsdale, gave nearly the same results as those of Mr. 

 Austen. 



After again examining our own collections, and looking to 

 the fossils of North Devon, South Devon and Cornwall as a 

 whole, we distinctly perceived that Mr. Lonsdale was right, 

 and that they must all belong to a system intermediate between 

 the two great systems (Silurian and Carbonifei'ous) which had 

 so recently been shown to be entirely separated from each 

 other, both by their order of superposition and their imbedded 

 organic remains. 



The publication, indeed, of the Silurian system and its nu- 

 merous fossils affords us a fixed term in the series of the older 

 rocks; and the previous labours of Professor Phillips and 

 others having made us acquainted with the organic remains 

 of the carboniferous system, we have now, for tlie first 

 time, the means of placing the Devonian groups in their true 

 order. 



Without entering, on this occasion, into specific details, we 

 may state that the zoological groups of the Devonian rocks 

 are all of characters intermediate between those which mark 

 the Carboniferous and Silurian epochs. Thus, for example, 

 among the Cephalopoda, Goniatites have hitherto been con- 

 sidered as typical of the carboniferous system, while the re- 

 searches of one of the authors have shown that they never oc- 

 cur in the Silurian system. They do, however, appear in 

 some of the older Devonian rocks ; and, just as we should 

 expect, they are associated with analogues of an entirely new 

 type, the Endosiphonitcs^. 



Again, there are many large and broad Spirifers in these 

 Devonian rocks, which closely a}iproach to the forms of that 

 genus, so abundant in the carboniferous system. But this ge- 

 nus is feebly developed in the Silurian system, and the few spe- 

 cies that do occur are entirely unlike the large typical Spirifers 

 of the carboniferous a^ra ; while the Orthis, or real Silurian 

 * Sec Trans, of the Cambridge Phil. Soc, vol. vi. 



