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species of the same family, a Gleichenia, is allied to species recognized in the 

 middle Cretaceous of Europe, but far distant from either of tin; two species of 

 this genus described from the Olithe. Of the Cycadeee one species from Ne- 

 braska is allied to a Pterophyllum, described and figured also from the Qua- 

 der-sandstein of Germany, but this last species, like ours, has no known rela- 

 tion to any fossil or living plant of this genus, and therefore is not positively 

 referable to this family. In the Conifers the Cretaceous flora of Nebraska 

 has representatives of Sequoia, Glyptostrobus and Cunninghamites ? perhaps. 

 The first two have not been seen anywhere before the Cretaceous, and the 

 last only in the Miocene. The fragments considered by Dr. Newberry as 

 representing an Araucaria are closely related to a species of Conifer described 

 formerly by Dunker, under the name of Abietites curvifollus from theQuader- 

 sandstein of Blankenbourg. The relation of this form is rather with Abies 

 than with Araucaria. Admitting it, however, in the section Araucarim, which 

 after being recognized in the fossil wood of the Devonian, disappears entirely 

 as far up as the Jurassic, where it is represented by four species, it is still 

 impossible to find even a distant affinity between the supposed Cretaceous 

 Araucaria of ours and any of the forms of older formations. The relation of the 

 genus Phyttocadus is with that of Salisburia in the section Taxacccc. It is 

 represented in the flora of the Dakota group by one species, and has not been 

 seen before in a fossil state. All the Salisburia fossil species are as yet from 

 the Miocene of Europe, and from the Eocene of this continent. So far, this is 

 all that can be said of the relation of the flora of the Dakota group with any 

 of the vegetable remains recognized from precedent epochs, and it is indeed 

 very little. It is possible, of course, to suppose an intermediate and unknown 

 land formation, where, in an immense space of time, the plants of a lower 

 grade have developed those primitive types and multiplied them to the 

 Cretaceous epoch. But the Cretaceous flora does not preserve any traces of 

 ancient forms known of old ; of the ferns, large Calamites, Cycadeee, &c, not 

 even a predominance of ferns and Conifers, which were remarked in the Ju- 

 rassic as it is known until now. Among its 130 species, the Dakota group 

 flora has only five species of ferns or Cryptogamous plants; one single species 

 very doubtfully referable to the Cycadeee ; six species of Conifers, two Mon- 

 ocotyledons ; all the others represent Phcenogamous plants, distributable not 

 in a single one, but in all the essential groups of vegetables living at our time. 

 Of the Apetalous plants it has the lioldecc, Amcntacece, Alyricaceee, Platancce, 



