GEOLOGY AND PALEONTOLOGY. 161 
same as that of the sandstone in which it is embedded, usually a yellowish brown. 
Not infrequently, however, especially in the quartz-like rocks, the impressions 
are almost jet black, and stand out in bold relief to the gray stone. It often 
happens, especially where the leaves have been enclosed in concretions, that the 
exposed surface has been polished by the action of the wind and rain until it 
presents a sleek, glossy appearance. Again, in the softer sandstones the impres- 
sions are so fragile that they crumble on exposure, and can be removed, if at all, 
only with the greatest difficulty. 
The history of the subject has been discussed under its proper heading, and 
only a brief résumé can be given here. The three men who, more than all 
others, have contributed to our knowledge of the paleobotany of the group are 
Oswald Heer, J. S. Newberry, and Leo Lesquereux. Professor Heer, of Zurich, 
Switzerland, was probably the most noted paleobotanist the world has ever 
known. His knowledge of fossil plants was profound and comprehensive. He 
described forms from many parts of the world, more especially from Europe and 
the arctic regions. His connection with the history of the Dakota group is con- 
fined to the identification of two collections of plants. The outline drawings of 
specimens sent him by Meek and Hayden in 1858 were referred by him to the 
Tertiary, and his position was afterward defended in a series of letters in the 
Heer-Newberry controversy. Professor Heer also described the collection made 
by Marcou and Capellini in 1863. The leaves were figured in the paper ‘‘ Phyl- 
lites Crétac¢ées du Nebraska,”’ which is the first printed description, with plates, 
of Dakota leaves. 
Dr. J. S. Newberry, the eminent American geologist, also did much good work 
in Dakota phytopaleontology. He first identified the leaves of which drawings 
had been sent to Professor Heer as Cretaceous forms, and enunciated the dic- 
tum, which has since been universally accepted, that the essential facies of the 
Dakota flora did not differ materially from that of the present time. Several 
papers of importance from the pen of Doctor Newberry were published during 
the ’50s, but owing to a misunderstanding with Doctor Hayden he ceased to 
interest himself in the subject. 
It was Leo Lesquereux, whom Doctor Knowlton justly styles the Nestor of 
American paleobotanists, who did more than any other man for the cause of the 
phytopaleontology of the Dakota group. Leo Lesquereux is perhaps the most 
pathetic figure in American science. Practically exiled with Agassiz and Guyot 
from his native land at the age of forty years; totally deaf, so that he never heard 
a word of spoken English; living alone among strangers in a strange land; his 
whole life filled with hardships and disappointments: nevertheless at his death 
America lost not only her most distinguished vegetable paleontologist, but also 
her foremost bryologist. The amount of work he performed was immense; and 
the record of his achievements will long stand as a monument worthy the emula- 
tion of future generations. Doctor Hayden, who made most of the early collec- 
tions of Dakota leaves, submitted a number of specimens to Doctor Lesquereux 
for identification; and in 1868 his first publication on the subject appeared. He 
was at this time sixty years of age. From this date until the time of his death, 
in 1889, scarcely a year passed that he did not present to the scientific world a 
contribution to the knowledge of this most interesting subject. The three most 
important of these publications are: Cretaceous Flora, published in 1874; Cre- 
taceous and Tertiary Floras, in 1883; and The Flora of the Dakota Group, in 1892. 
This last is Doctor Lesquereux’s masterpiece, and was incomplete at the time of 
hisdeath. The book was edited by Dr. F. H. Knowlton; and the careful manner 
in which the work was done testifies to the scholarly attainments of the editor. 
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