have successively occupied the surface of the Earth. 369 



Thus, there are in this flora only twenty plants arranged in the 

 families of that division ; all these belong to the group of hypo- 

 gynous ganiopetala3 which I have called isogynous, which in the 

 general organization of their flowers approach nearest to the; 

 dialypetalae. 



Is this absence of anisogynous gamopetalse, or gamopetalse with 

 irregular ovaries, the result of chance ? or of the fact that most of 

 these plants, especially among the species of temperate regions, 

 are herbaceous, these herbaceous plants being generally in condi- 

 tions less favourable for passing into the fossil condition ? Or 

 lastly, were not these families, which some botanists have been 

 led to consider as the most elevated in the scale of vegetable or- 

 ganization, at that time yet created ? This cannot now be esta- 

 blished positively. 



But it should be observed that in the miocene epoch these 

 plants were still less numerous, yet belonged to other families, 

 and that in the eocene epoch none have been cited by the authors 

 who have made out the relations between the fossil and living 

 plants, without having at the same time preconceived ideas on the 

 subject. 



Another fact to be noted, but which also probably depends on 

 the herbaceous nature of these plants and their leaves not being 

 caducous, is the almost complete absence of Monocotyledons, 

 Ferns and Mosses, which establishes, in reference to these fami- 

 lies, a very great difference between the pliocene flora and the 

 existing one of Europe. A no less important difference distin- 

 guishes this flora from those of older epochs, viz. the absence 

 throughout these beds of the family of Palms, which formed, on 

 the contrary, the prominent character of the miocene epoch. No 

 trace of them is known in Europe in the pliocene formations I 

 have enumerated, while the woods of this family are very abun- 

 dant in the formations of the Antilles, which are regarded as be- 

 longing to an epoch at least as recent as the pliocene formations, 

 — which appears to indicate that the zones of vegetation were 

 distributed at that epoch almost in the same manner as at the 

 present time. 



Indeed, in these modern formations of the Antilles, among 

 the fossil woods, the only parts of vegetables hitherto collected, 

 are found specimens which indicate the existence not only of 

 numerous and varied Palms, but of several other families of the 

 equatorial zone, such as Lianes allied to the Bauhinias, Meni- 

 spermese, Pisonias, &c. Thus the vegetation of the Antilles had 

 the characters of the equatorial zone at that epoch, as the flora 

 of Europe had at the same time those of the temperate zone. 



Finally, to conclude our observations on this flora of the last 

 geological epoch, preceding the existing one, we will direct atten- 



