hy Deciduous Plants in the Tertiary Floras. 299 



circumstances all of which would have concurred to limit the 

 quantity of organs fitted to pass into the fossil state. 



The difference of station can only be proved by means of in- 

 direct negative evidence. It appears to be certain, however, 

 that, as we have stated above, the plants nearest to the ancient 

 lacustrine shores were not forms with a European physiognomy, 

 but Palms, Coniferce, Proteacea, Zizyphi, Diospyri, &c. — genera 

 the impressions of which are met with in all the beds ; and next 

 to these, Laurinea, Ericacea, Leguminosce, &c., which usually 

 make their appearance after the former. If the Betulacece, 

 Salicinece, Ulmacece, and Acerinece, even in limited numbers, had 

 inhabited the immediate margin of the ancient waters, their 

 remains would have been buried annually, either at the period 

 of the fall of the leaf or at that of the maturity of the fruit. 

 Moreover it is the nature of plants inhabiting moist localities 

 to multiply in colonies, in consequence of the uniformity of con- 

 ditions, which uniformly favours the propagation of the same 

 organisms; there is therefore, we repeat, but little probability 

 (although nothing can be stated with absolute certainty) that 

 the group of species of which we are speaking inhabited the 

 zone immediately contiguous to the ancient shores ; it is more 

 natural to suppose that they were a little thrown back upon the 

 second plane ; but we remain of necessity in ignorance of their 

 true aptitudes, not knowing the exact configuration of the an- 

 cient land. From stratigraphical observations, it appears that 

 on one side (towards the north-east of the town) it was, if not 

 commanded by escarpments, at least considerably elevated and 

 broken. The repeated occurrence of ConifercB {Callitris, Juni- 

 perites, Widdringtinia, Pinus) and of trees which, like Cercis and 

 the Proteacea [Grevillea, Lomatia), haunted undulating ground 

 rather than low and moist spots, must lead us to this opinion. 

 On the other hand, the abundance of species of Andromeda and 

 Vaccinium appears to indicate turfy and inundated ground, occu- 

 pying probably a great extent. It is difficult to decide whether 

 the organisms with deciduous leaves of the flora of Aix inhabited 

 one or other of these two zones, and dwelt consequently upon 

 the broken slopes or in moist, low, and marshy ground ; the 

 nature of the sediment in which their impressions are observed, 

 and the kind of species with which they are associated in the 

 beds, are the only indications which can be consulted in a ques- 

 tion of this kind. The following are the notions which may be 

 obtained upon this point. 



There exist in the stratum of Aix two kinds of beds with 

 vegetable impressions, indicating two modes of sedimentation, 

 of different nature. The first includes schistose and especially 

 marly limestones, in very thin laminae, denoting a deposit formed 



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