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as 458. The evidence of the marine Mollusca, has been found in 
ae 
_ paleontology the most valuable, and from the large area occupied by the 
ocean, the most complete ofany. The able paleontologist who has devoted 
AGE OF THE LIGNITE FORMATION. 
his attention specially to the study of this line of life forms, in the area 
in question; though assenting to the classification of the disputed beds 
with the Cretaceous, registers his opinion as to the preponderance of 
forms of Tertiary facies. He admits in evidence against these a few 
scattered genera, which in other countries, where the Cretaceous and 
Tertiary are widely separated by physical conditions, have been found 
characteristic of the former. He candidly allows, however, the evidence— 
which, though negative, must be accepted as of some importance—afforded 
by the non-appearance of the Cretaceous Cephalopoda, even in those 
regions where marine conditions have prevailed most extensively. A 
disposition has been shown, to fortify the Cretaceous position of the beds, 
by using the change from marine to fresh, or brackish-water conditions, 
as aline. It has been said, in discussing the age of the rocks of certain 
localities, that no marine Tertiary beds are known. They can evidently 
never be known if all marine beds discovered are affixed to the 
Cretaceous. The non-occurrence of Jnocerami, and other such Cretaceous 
forms, in the base of the Tertiary of a region in which the change took 
place so gradually, would be a matter of surprise. Edward Forbes, and 
Sir Charles Lyell, have long ago pointed out the mingling of such types, 
and Barrande and others have shown it to occur extensively, without 
at all invalidating the general tenor of the record. A certain form, may 
be characteristic of a formation in a given locality, but may not be 
capable of use as a touchstone, in another and widely separated one. 
Prof. Lesquereux has, m>reover, lately shown that the really authentic 
cases of the discovery of Cretaceous molluscs in the Lignite formation, are 
much fewer than had formerly been supposed.* — 
459. To the evidence derived from the vertebrate remains, great 
weight, no doubt, attaches, as must always be the case with that from the 
highest forms of life of any period. The few relics of dinosaurians, and 
other reptiles of Cretaceous type, have really afforded the initial point 
and strongest retreat, of the arguments for the Cretaceous age of the 
formation. If no other facts were forthcoming, a paleontologist, would 
_ with every probability in favour of his classification, place the beds con- 
taining these in the Cretaceous, doing so, as would alone be possible, from 
analogy with other regions. It can hardly be admitted, however, that 


*U. 8. Geol. Surv. Territ., 1873. p. 367, et seq. 

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