hy Deciduous Plants in the Tertiary Floras. 301 



the marly beds. It is true that we only advance this opinion as 

 a conjecture ; there exists, however, if we attend to the preceding 

 indications, a certain probability for the belief that the species 

 with deciduous leaves, at the epoch of the gypsum of Aix, in- 

 habited a station intermediate between the immediate margin of 

 the waters and the more distant parts of the interior of the 

 country. 



With regard to the mode of grouping, that is to say, the 

 manner in which the individuals of this series of plants was 

 distributed, the same reasons which have inclined us to think 

 that they were not situated on the margin of the waters, or in 

 the inundated and marshy parts, lead us equally to believe that 

 they did not form colonies of individuals or numerous and fre- 

 quently repeated associations ; the rarity of the impressions 

 must rather lead us to assume that these organisms were then 

 scattered here and there, and occurred only in certain situations 

 the precise nature of which it is impossible to indicate. In a 

 word, these organisms nowhere formed a wood, or even a group 

 of considerable extent, but we should have met with them from 

 time to time as isolated plants growing under the influence of 

 some particular exposure which protected and favoured their 

 development. 



There are not wanting examples of a similar mode of existence 

 for trees or shrubs which, not living in society, make their 

 ajjpearance here and there isolatedly or in very small groups, 

 without ever multiplying greatly. 



Another circumstance may have assisted in limiting the num- 

 ber of impressions of trees with deciduous leaves in the flora of 

 the Gypsum of Aix — namely, the small size of the species, which 

 were probably reduced to the proportions of mere bushes. 



It sometimes seems that the gigantic must necessarily have 

 been the appanage of the ancient creations : one is led to see it 

 everywhere, even in species really inferior in dimensions to their 

 living analogues. The large size of certain Cryptogamic plants 

 of the Palseozoic epoch, the enormous Saurians of the Secondary 

 strata, and the no less astonishing Pachydermata of the last 

 Tertiary epoch may have led to the notion that magnitude was, 

 as it were, a general character of extinct organisms ; but this is 

 by no means the case. On quitting animals for plants, we 

 quickly see that in these at least the proportions have varied 

 according to the age and classes. There are even times in 

 which the size of species seems to diminish in comparison to 

 that which now exists; and this phenomenon is particularly 

 distinct in the Gypsum of Aix. Nothing in the fragments of 

 stems and branches, nor in the aspect of the fruits and appendi- 

 cular organs, indicates anything but plants of middling size; 



