122 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 17, 



Of this list I shall only here remark upon the Cephalopods and 

 Conchifers, reserving a more complete list of the whole of the Corn- 

 brash species for a future paper. 



Of these, the former are at present of great interest, as some have 

 endeavoured to maintain that the Cephalopoda, of all shells, may 

 be confidently appealed to as marking the stratum in which they 

 occur in a more complete manner than any other shells ; but, if we 

 apply this to our Cornbrash specimens, we shall see that such an 

 opinion is not founded on extensive observation ; and indeed, as we 

 expect, the Cephalopoda of all other molluscous animals, being more 

 migratory, and being inhabitants of deep seas, could more readily 

 travel than other families : and, though 6 out of 8 in the follow- 

 ing list are not found intermediate between the Inferior Oolite and 

 the Cornbrash in British geology, we have still no evidence that 

 they are not so in the Continental Jurassique. At the same time 

 I would again urge the fact, that English geologists have been too 

 much in the habit of giving distinct names to fossils from distinct 

 rocks, upon the assumption of a change which did not alwavs exist 

 in nature ; and thus much ingenuity has been expended on species- 

 making by local observers and theoretical geologists, each of whom 

 has too often but a localized theory to support. 



The Cephalopoda are as follows : — 



Inf. Oolite. Cornbrash. 



Ammonites Herveyi, M. C. * * 



Brocchii, M, C. * * 



subradiatus, M. C * * 



Humphresianus, M. C. * * 



■ Jurensis?, VOrb * * 



discus, M. C * 



Nautilus truncatus, M. C. * * 



inflatus, D'Orb * 



Here then the evidence is just the opposite to that advanced in 

 favour of the new Liasic theory (see p. 103) : the 6 are common to 

 lower beds, whilst only one, A. discus, would appear to be peculiar to 

 the Cornbrash ; were this rock therefore only about 100 feet from the 

 Inferior Oolite, it must upon this new theory be considered as of 

 Inferior Oolite age. 



As regards the Conchifers, I have appended the following, most of 

 which have been considered peculiarly to mark the Inferior Oolite*. 



Terebratula obovata. Terebratula ornithocephala. 



digona. intermedia. 



lagenalis. maxillata. 



sublagenalis. 



I would here record my personal obligations to Mr. Davidson for his excellent 

 monographs on the Braehiopoda, as, however we may differ as regards species, all 

 must agree that the forms of this puzzling family are depicted and described with 

 the greatest accuracy. 



* See note at p. 120. 



