REPORT OF LEO LESQUEREUX, 



EEMAEKS ON SPECIMENS OF CRETACEOUS AND TERTIARY 

 PLANTS SECURED BY THE SURVEY IN 1877: WITH A LIST 

 OF THE SPECIES HITHERTO DESCRIBED. 



By Leo Lesqueretjx. 



PART I.— REMARKS ON SPECIMENS SECURED IN 1877. 



Until the end of the season of exploration of the Geological Survey of 

 the Territories in 1877, few specimens of fossil plants had been received 

 for examination. Some were sent by Passed Assistant Engineer H. C. 

 Beckwith, United States Navy, from the Cretaceous strata at the foot 

 of the Rocky Mountains, near Morrison, Colo., and a few by Rev. Arthur 

 Lakes, from the Eocene of Golden. These have been examined and 

 figured, but they are too few in number for a separate report. 



Near the end of the past year I received from the Upper Tertiary of 

 Florissant an immense amount of specimens, mostly obtained by Prof. 

 Samuel H. Scudder. The examination of these materials is begun, but 

 the materials are so abundant that a careful determination and descrip- 

 tion of them will demand much time, and I can now give merely a gen- 

 eral and superficial account of what these specimens represent. With 

 those of the Cretaceous, they may be all together published in a future 

 report. 



CRETACEOUS. 



The Cretaceous species from Mr. Beckwith's specimens are interesting 

 on two points. They are the first Cretaceous plants found near the base 

 of the Rocky Mountains,* and by their relation and identity to some 

 species of the Dakota Group, they prove the continuity of this formation 

 from the point where it passes under the Upper Cretaceous and Tertiary 

 strata in Nebraska and Kansas to the base of the Rocky Mountains, 

 where it becomes exposed again by the upthrow of the hog-backs. And 

 then they are highly interesting by the species or types which they repre- 

 sent, some of them remarkably beautiful and new. 



The geological age of the formation, and its identity with that of the 

 Dakota Group, is positively indicated by the presence of Sassafras- 

 Cretaceum, Newb., Magnolia Capellini, Heer, Salix protewfoUa, Lesqx., 

 and of species of Aralia, — one, Aralia Toivneri, Lesqx.; another, similar 

 to Aralia concreta, Lesqx., differing merely by the division of the leaves 

 into three instead of five lobes. By this division, the leaves are interme- 

 diate in characters between Aralia tripartita, Lesqx., of the Annual 

 Report of 1874, p. 348, pi. i, fig. 1, and Aralia concreta, of the same report^ 

 p. 349, pi. iv, figs. 2-4. In the same genus we have also, from the same 

 locality, near Morrison, where the plant-bearing strata are somewhat 

 higher than those where the bones of great Saurians have been discov- 

 ered, leaves of an Aralia so closely allied to the one described by Pro- 

 fessor Heer as Aralia formosa, from the Cretaceous of Moletin, Ger- 



[* Compare, however, Ann. Eep. of this Survey for 1873, 1874, p. 196. — Ed.] 



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