200 
Kansas, Colorado, the western Black Hills, 
and presumably elsewhere in this region has 
been pretty well known for a number of years. 
Their exact age has been a matter of consider- 
able differences of opinion. 
The history of paleobotanic discovery of the 
so-called Dakota flora has been given in Les- 
quereux’s three memoirs and need not be re- 
counted here except to point out that the col- 
lections, a study of which resulted in the identi- 
fication of over 400 species of plants, were made 
at different times and places by a number of 
different collectors, who, as in so much of the 
early exploratory work in the West, paid little 
attention to stratigraphic position or locality. 
-Any yellowish or reddish sandstone with im- 
pressions of dicotyledonous leaves was Dakota 
in age, and for a large number of species ‘‘ Da- 
kota group of Kansas,” or at most the county 
from which the specimens were collected, is all 
we know of the whereabouts of the outcrop. 
Apparently the first to notice marine fossils 
at the base of the red Cretaceous (Dakota) 
sandstones was Ie Conte.* Cragin, while at 
Washburn College, Topeka, Kans., did much 
work upon the Cretaceous and published many 
short paleontologic papers. In 1890 he de- 
scribed a cross-bedded sandstone (the Chey- 
enne sandstone) which underlay marine beds 
in southern Kansas and which he considered 
to be related to the Potomac, Tuscaloosa, Trin- 
ity, and “Atlantosaurus beds,” and the next 
year he published the statement that the Chey- 
enne sandstone was probably of the same age 
as the Trinity of Texas, the Potomac of the 
Atlantic Coastal Plain, and the Wealden or 
Purbeck of Europe. Invariably in his discus- 
sions he used the term Comanche as the inter- 
changeable equivalent of the European Neo- 
comian. 
The first definite announcement of the flora 
contained in the Cheyenne sandstone was made 
by Hill,> who recorded the following species 
from collections made by Hill, Gould, and 
Shattuck in 1894: 
Rhus uddeni Lesquereux. 
Sterculia snowii Lesquereux. 
Sassafras mudgii Lesquereux. 
4 Le Conte, J. L., Notes on the geology of the survey for the extension 
of the Union Pacific Railway, Philadelphia, 1868. 
5 Hill, R. T., Discovery ofa dicotyledonous flora in the Cheyenne sand- 
stone: Am. Jour. Sci., 3d ser., vol. 49, p. 473, 1895; On outlying areas of 
the Comancheseriesin Kansas, Oklahoma, and New Mexico: Idem, vol. 
50, pp. 205-234, 1895. 
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1921, ! 
Sassafras cretaceum obtusum Lesquereux. 
Sassafras n. sp. 
Glyptostrobus gracillimus Lesquereux. 
Sequoia sp. (cones). 
Cragin’s conclusions were given in a paper 
published in 1895,° in which the section is given 
as follows: 
Kiowa shales. 
Champion shell bed. Si dkepanandeiunie: 
elk Oreck bedstranobier shale. 
Cheyenne sandstone 
Corral sandstone. 
From the “Elk Creek beds” he recorded 
Sterculia snowii, Sassafras mudget, Sassafras 
cretaceum, Sassafras sp., Rhus uddeni, Sequoia 
sp., and Glyptostrobus. gracillimus.? Only the 
first two of these are contained in the collections 
studied by me. 
Other contributors to ‘the subject prior to 
1900 were Mudge, Prosser, Jones, Stanton, and 
Gould. Their results are not pertinent to my 
present purpose beyond the fact that they show 
conclusively the presence of a sandstone, the 
Cheyenne, containing the remains of a land 
flora in southern Kansas beneath a marine 
series, the Kiowa shale, carrying a fauna that 
is correlated with that of the Washita group 
at the top of the supposed Lower Cretaceous 
section of Texas as elaborated by Hill. 
During his residence in Kansas Twenhofel 
studied the Cretaceous of the central part of the 
State, and in a brief paper * published in 1917 
he confirmed Cragin’s earlier results® that a 
situation identical with that of southern Kan- 
sas prevails in central Kansas. In a more 
recent article * he contends that the Dakota of 
Kansas and the Washita group of Texas are of 
the same age, and that both the Cheyenne- 
Kiowa-“ Medicine beds’’ sequence of southern 
Kansas and the Mentor-Dakota sequence of 
central Kansas should be referred to the 
Comanche series. 
The “ Dakota flora’’ of the Denver Basin has 
recently been revised by Knowlton. As a 
result of field work by Lee and Cannon during 
1916 it has been shown ™ that the formation 
from which Lieut. Beckwith collected the 
“Dakota” plants from Morrison, Colo., that 
6 Cragin, F. W., A study of the Belvidere beds: Am. Geologist, vol. 16, 
pp. 357-385, 1895. 
7 Idem, p. 367, quoted from Hill. : 
8 Twenhofel, W. H., Kansas Acad. Sci. Trans., vol. 28, pp. 213-223, 1917. 
9 Cragin, F. W., Am. Geologist, vol. 16, pp. 162-165, 1895. 
10 Twenhofel, Ww. H., Am. Jour. Sci., 4th ser., ¥ol. 49, pp. 281-297, 1920. 
1 Lee, W. T., Am. Jour. Sci., 4th ser., vol. 49, pp. 183-188, 1920 
