the Earth at different Epoclis, ^c. S65 



In tiie third period, the vegetation assumed a more peculiar 

 character. The cycadeae, together with the ferns and some coni- 

 feroB, almost entirely composed it. This vegetation, although dif- 

 ferent from that of any part of our globe, yet comes nearer to 

 that of the coasts and large islands of the equatorial zone, for the 

 cycadeae grow chiefly in the West India Islands, on the coasts of 

 Brazil, at the Cape of Good Hope, in the Moluccas and Japan, 

 and on the coasts of New Holland. They are, consequently, 

 plants of warm climates placed near the tropics, and countries 

 subjected to the influence of the sea air and temperature. The 

 ferns, as we have already said, are still more peculiarly of this 

 character. It might therefore be concluded from these facts, that 

 the vegetation of the epoch in question must have grown upon 

 islands of small extent ; but I do not pretend to attach a very 

 great importance to this conclusion, the botany of this period 

 being as yet very imperfectly known. The only consideration to 

 which I attach some probability is, that the flora which leads us 

 to this result, corresponds to an epoch intermediate between the 

 insular flora of the first period, and the continental flora of the 

 fourth. 



The vegetation of the fourth period, in fact, presents all the 

 characters of the vegetation of great continents and of temperate 

 climates, or of climates a little warmer than those of the middle 

 parts of Europe. It is generally similar to that of Europe and 

 North America, and presents but a small number of vegetables 

 like those of somewhat warmer regions, that is to say, some palms 

 or other arborescent monocotyledonous plants. But, at this epoch, 

 the local influences dependent upon slight differences of latitude, 

 or of elevation or exposure, already appear to determine very sen- 

 sible differences in the local floras, whose remains we find in dif- 

 ferent places. Thus, sometimes the mass of these vegetables 

 seems to indicate a flora similar to that of the forests of the north 

 of Europe or America ; and sometimes, on the contrary, vege- 

 tables resembling those of warmer regions, not covered with woods, 

 occur together in the same place. 



The details, relative to the distribution of vegetables in the 

 different beds and localities of the tertiary formations, remain 

 yet to be discussed ; but the aggregate of these vegetables pre- 

 sents a flora, in almost all respects similar to that of the present 



JANUARY— MAECH 1829. • ■ b 



