132 



types under climatic or any other influence. This is certainly an apparently 

 logical conclusion. But the same groups of floras mentioned above, viz, those 

 of the Paleocene of Europe, contradict by their characters a supposition of 

 this kind. With the flora of Gelinden that of the Dakota group is related 

 only by that species of Quercus primordialis, or of Dryophyllum, a type 

 present, as we have seen, in all the vegetable series of the Upper Cretaceous 

 and of the Lower Tertiary, and, with that of Sezane, it has scarcely any other 

 relation but that of the same Dryophyllum and of a Sassafras. Considering 

 the general characters of the floras, that of the Dakota group appears still 

 more different from that of Sezane than from that of the American Lignitic; 

 for the phaenogamous species of Sezane are mostly represented by dentate 

 or serrate leaves of Betula, Alnus, Myrica, Ulmus, Protoficus, Populus, Salir, 

 Juglanditcs, &c, genera either absent in the flora of the Dakota group or 

 represented in it by leaves with entire borders, as it has been explained 

 already. 



The European authors have remarked upon the little cohesion of the 

 constitutive elements of the Cretaceous groups of vegetables, which, even when 

 apparently synchronous, are so diversified that they appear as brought together 

 at random, and not to have belonged to the same epoch and the same country. 

 " Never has the contrast been as great as at that moment, either between the 

 floras of next succeeding stages or between those of separate localities, even 

 in synchronism, when compared to each other. To quote only the localities 

 which have been more carefully studied : what point of analytical connec- 

 tion can be established between Niedershoena, in Saxony; Moletin, in Moravia; 

 Quedlinburg and Blankenburg, in the Hartz; Halden, in Westphalia; the 

 sands of Aix; the Senonien of Bausset; the Sautonien of Fuveau, in France; 

 and the North American Cretaceous of Nebraska." * 



This remark of Messrs. Saporta and Marion, true as it is and to the point 

 in regard to the vegetable groups of the Cretaceous, might be farther extended, 

 as applicable to the succeeding Lower Tertiary floras, which as yet do not 

 present any marked degree of homogeneity as far up as the Lower Miocene. 

 Though it may be, it confirms our remarks on the disconnection of the 

 vegetable types of the Dakota group, and also explains the fact, as far as it 

 can be, by generalizing it as a correlative phenomenon observed in other 

 countries. The same remark amplifies in a degree the probability of truth of 



• Fossil Plants of Gelinden, p. 74. 



