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10. CONCLUSIONS. 
1. The answer that the writer would give to the question at the head 
of this paper is that the Lance Creek beds belong to the Upper Cretaceous. 
2. In the Upper Cretaceous ought to be included also the Puerco and 
not improbably also the Torrejon and the Fort Union. 
3. In case of a conflict between the evidence furnished by the flora 
and the fauna of the Lance Creek beds and those of the Fort Union re- 
spectively, the evidence obtained from the faunas is to be preferred, as 
being part of a more complete and better understood history. Present 
knowledge regarding plants seems to indicate that they were precocious, 
having reached something like their present stage of development long 
before the mammals attained anything like their present stage of differ- 
entiation. There are also indications that the floras of the western world 
were, during the Cretaceous, considerably in advance of those of Europe. 
4. Even if it were conceded that the Fort Union belongs to the Ter- 
tiary, and that the fauna and flora of the Lance Creek epoch are more 
closely related to those of the Fort Union than they are to those of the 
Judith River, it does not follow that the Lance Creek epoch must be in- 
cluded in the Tertiary. A quarter before midnight on Monday is much 
nearer to Tuesday than it is to the previous six o’clock; nevertheless, it 
is not yet Tuesday. 
U.S. National Museum, 
Washington, D. C. 
