other specimens, some fossil leaves taken from a red sandstone at about the 

 same locality which I had formerly visited. From my impression in regard to 

 the geological distribution of the rocks which I had seen in place, and from 

 the preseuce of two species of leaves recognizable among these specimens — 

 one Salix, one Laurus, with apparently a Comus, I then considered them as 

 pertaining to a Tertiary formation. By the kindness of Professor Hall I have 

 now these specimens for examination, and, comparing them with those of the 

 Dakota group ofNebraska, recognize them easily as from the same Cretaceous 

 formation. Some of the species are identical with those of the Blackbird 

 Hills, and the compound of the stone is of exactly the same kind. It is 

 coarser, however, forming a rough-grained sandstone, which renders some- 

 what difficult the study of the specimens, on account of the obliteration of the 

 veins. Some of these leaves are described and figured in this paper. 



In 1863 another geological exploration in the same field of research 

 had also contributed new and interesting materials for the study of our Creta- 

 ceous flora. As has been stated already, the reference of the Nebraska 

 fossil leaves to a Cretaceous formation caused a difference of opinion between 

 some American and European geologists concerning the true age of the 

 Dakota group. The details of the discussion on this subject are given at 

 length in Dr. Newberry's Extinct Floras, (Joe. cit.) Professors Marcou and 

 Capellini, two European geologists of celebrity, wishing to obtain for them- 

 selves full evidence on the conclusions of Doctor Hayden, undertook an 

 exploration in Nebraska to visit the localities where the fossil plants had 

 been discovered and to review the stratigraphical records on which these 

 conclusions had been based. They obtained in their tour, especially in the 

 vicinity of Tekamah, as also from the Indian reservation in the Blackbird 

 Hills, a number of specimens, which were delivered to Professor Heer for 

 examination. From these materials the Phyttites du Nebraska were pre- 

 pared and published — a very interesting paper, 22 pages quarto, describing 

 seventeen species, all new ones, with four plates of illustrations. This memoir 

 gives us the first authentic and reliable record of our North American Cre- 

 taceous fossil plants, and is the more valuable on account of the high scientific 

 attainments of the author, of the accuracy of his descriptions of the leaves, 

 and of the figures by which they are exemplified. 1 Of course the explora- 



1 Three leaves from the Dakota group are figured in Journal of Sciences and Arts, vol. xxvii, No. 80, 

 pp. 222 and 223, 1869. They are, however, without description. The first has been considered a leaf of 

 Liriodendron, the second a Crcditcria, the third a Sassafras. 



