332 GEOLOGICAL SURVEY OF THE TERRITORIES. 



the whole explored area of the Dakota group, as also in the lower stage 

 of the Cretaceous of Slew Jersey, and in the Upper Cretaceous of Green- 

 land. Two other species have been described from the Dakota group : 

 one, M. obovata, by Dr. Newberry, in his Ancient Floras ; another, M. 

 tenuifolia, in Cret. Mora. In Europe the leaves referable to this 

 genus are of a different type than ours, larger and more beautiful. Two 

 species — M. amplifolia and M. speciosa — are described by Heer in the 

 Flora of Moletiu, there represented by leaves and fruits. Count Sa- 

 porta considers also as a Magnolia Phyllites plagiaus, Ung., of the flora of 

 Gosau. 



To the same order belong Liriodendron, so easily recognized in the 

 peculiar form of its leaves. Its Cretaceous origin, or rather existence, is 

 marked in the Dakota group by a Dumber of specific representatives 

 locally and distantly distributed. At least, though the first lot of Cre- 

 taceous specimens sent from Nebraska and Kansas for examination had 

 many fragments of the species described in Cretaceous Flora, I have 

 since received only a small leaf found in Kansas by Dr. Mudge, refera- 

 ble to L. Meekii. This genus is not as yet represented in the Cretaceous 

 floras of Europe, nor in that of Greenland. 



To the class of the Golumniferece, taking altogether the three orders, 

 Sterculice, Buttneriacece, and Pterospermce, are apparently referable the 

 forms described under the generic name of Protophyllum, as well as the 

 true Gredneria. The Sterculiacece are more distinctly represented by a 

 leaf described in this memoir as Sterculia cretacea. Though the nerva- 

 tion is obsolete, the mode of division of the leaf in equal linear diverg- 

 ing lobes is like that of species of this genus, which has also a well-de- 

 fined species in both stages of the Cretaceous of New Jersey. To the 

 Tiliacew, the leaves described as Greviopsis Haydenii have an evident 

 affinity of characters. 



The relation of Cretaceous species to the following and last classes of 

 the vegetable reign is not very clearly defined. To the Acerece is refera- 

 ble Negundoides acutifolius of the Cretaceous Flora. The leaf, however, as 

 seen from the figure and description, is too fragmentary for a satisfactory 

 determination of its characters. Acer antiquum is described by Etting- 

 hausen in his Cretaceous Flora of Niedershoena. But even from the 

 opinion of the author the reference is uncertain. The leaf rather resem- 

 bles a deformed form of Quercus or of Liriodendron. Heer has from 

 the Upper Cretaceous of Greenland a Sapindus prodromus, represented 

 by one leaf only, which, however, has evidently the character of the 

 genus. To the Rhamni, the leaf described as Rhamnus tenax, in 

 Cretaceous Flora, is probably related, and this relation seems con- 

 firmed by the presence of Celastrophyllum and Ilex species in the 

 same formation. Count Saporta, however, considers this leaf as show- 

 ing more affinity of form and nervation to Salix. To the Anacardics, 

 we have probably to refer as Rhus debeyana, that species described as 

 Populus and as Juglans, as seen in Cretaceous Flora, p. 110. I have not 

 obtained from the Dakota group any new materials comparable to this 

 form, especially common in Nebraska. But I have seen a very fine 

 specimen got out of a deep tunnel in Oregon, presenting upon its sur- 

 face, with the details of nervation and areolation, some punctiform small 

 protuberances, apparently oily glands, like those remarked upon leaves 

 of the living Rhus aromatica and other species of this genus. A 

 species of Rhus is described from the Cretaceous of Greenland by 

 Heer, while considering historical authority, we have the same evidence 

 in favor of Juglans, by a species of this genus in the Cretaceous flora of 

 Moletin. Of the Rosiflorece, we have from the Dakota group one leaf and 



