1ESQUKBEUX.J EEVIEW OF CRETACEOUS FLORA. 365 



taceous plants and those of Europe have been remarked in the Cretaceous 

 Flora, and, since its publication, no other work has appeared on the same 

 subject but the third volume of the Arctic Flora, where, as remarked be- 

 fore, Professor Heer describes the species of fossil plants from two stages 

 of the Cretaceous ot Greenland ; a lower one, that of Come ; an upper one, 

 that of Atane, and an intermediate small group from Spitzberg. With 

 the species of the first division, the Dakota group flora has Gleichenia 

 nordensMoldi, identical and none related ; with those of the second, it 

 has two Conifers — Sequoia fast igiata and Pinus Quenstedti. This last has 

 been described also by the author, from Spitzberg, and formerly from 

 Moletin. In the monocotyledonous. our Phragmites cretaceous seems 

 identical with Arundo greenlandica, Heer, of the same upper stage, and 

 in the dicotyledonous, Myrica cretacea, Lesqx., is comparable to M. 

 zenkeri, Heer, which is represented by a iragment only. There is still 

 an evident relation of the leaves described by Heer as Ghondrophyllum 

 orbicula,tum aud C. nordenskioldi with those of Hedera ovaMs, ot the 

 Dakota group. We have also Andromeda Parlatorii, Magnolia CapelUni, 

 and M. alternans present in both floras. These three species are appa- 

 rently extensively distributed in the Cretaceous. 



Without taking into account the more or less acceptable modifications 

 of generic and specific forms proposed in this review, we have here an 

 addition to the North American Cretaceous flora of twenty-four species, 

 mostly clearly defined from very tine specimens. This contribution, the 

 result of the discoveries made during one year only, by two zealous 

 young naturalists who have explored merely an area of small extent in 

 the counties where they live, shows what abundant materials are still 

 left in the strata of the Dakota group to reward future researches. It 

 exposes, also, with more evidence the riches and the diversity of the 

 vegetation of the Cretaceous period, manifested as it is by the distribu- 

 tion of the dicotyledonous leaves in the three great divisions of this 

 class of plants; by the numerous, clearly-limited, generic groups which 

 they represent, as well as by the multiplicity of specific forms referable 

 to some of the genera. The species of Menispermites and of Protophyl- 

 lum 7 for example, are as distinctly separated by the characters of their 

 leaves, though preserving the unity of their generic type, as we see 

 them at the present time under analogous climatic circumstances. 



These facts tend to confirm the general conclusions briefly exposed in 

 the Cretaceous Flora concerning the origin and the distribution of the 

 dicotyledonous species, a question to which the history of our present 

 North American flora is interested in the highest degree. 



