350 Professor Sedgwick and Mr. Murchison on the 



inations. Mr. Lonsdale, who has entered on a minute examination of the 

 NummuHtes found in the various localities above described, distinguishes (in 

 addition to several discoid bodies with a coralline structure, which have often 

 been mistaken for Nummulites) no less than eight species, all apparently new, 

 and only one of them common to all the ferriferous deposits. This shows 

 the risk we run in attempting to define the age of a formation from the mere 

 fact of its containing fossils of this genus. 



On reviewing the phenomena of the six preceding sections, we return to 

 our former conclusions — that along the north flank of the eastern Alps the 

 nummulitic series is very largely developed — that its lower portion graduates 

 into, and forms a part of, the upper green-sand and cretaceous system — that 

 its higher portions contain many fossils hitherto, we believe, unobserved in 

 secondary, but abounding in tertiary, formations — that it is surmounted by, 

 and appears to pass into, higher conformable strata with a large group of ter- 

 tiary shells — and that, considered as a whole, it may therefore be regarded as 

 a great, transition group between the secondary and tertiary systems of the 

 chain*. We think this statement in no respect hypothetical, and that it is 

 only a translation into intelligible language of the phenomena exhibited in a 

 series of actual sections. If, indeed, the higher strata described in this 

 chapter (for example, those at the northern end of the Untersberg section) 

 Avere overlaid by any known secondary deposit, we should then be entangled 

 in new difficulties, and might have to account for the peculiar succession and 

 distribution of organic forms in the Eastern Alps, We are not, however, 

 called upon to combat difficulties in the existence of which we do not believe. 



As the preceding conclusions are not only important in themselves, but are 

 connected with the general scope of this paper, it may be worth while to 

 fortify them by the following observations. 



1. All the previous sections prove that a part of the Alpine chain has under- 

 gone a movement of elevation at a very recent geological period ; but none 

 of them proves that any great or general movement took place between the 

 secondary and tertiary periods ; and, under such circumstances, have we not 

 a right to look for (what in point of fact we find) a continuous succession of 

 deposits between the newest secondary and the oldest tertiary groups } 



2. Between the secondary and tertiary formations, both of Prance and 



* Nummulites, though highly characteristic of certain groups of strata, are of course not equally 

 diti'used through them. There are several places in the Eastern Alps where, if we mistake not, 

 a transition is effected, from the secondary to the tertiary system, through the intervention of 

 strata in which Nummulites have not been observed. 



