336 The American Naturalist. [April, > 
THE PROBABLE PHYSIOGNOMY OF THE CRETA- 
CEOUS PLANT POPULATION. 
By Conway MAcMILLAN. 
The sudden appearance of metaspermic plants in the rocks 
of the Cretaceous period has occasioned much discussion, and 
has always proved to be a crux to the writers on evolutional 
philosophy. Even in the latest work of authority on general 
evolutionary topies—Darwin, and after Darwin, by Romanes, the 
„old and vague statements—concerning “probable breaks in 
the records,” and possible remarkable accelerations of what 
are usually very slow processes—may be found again, and 
have the air of being all that can yet be said with much show 
of reason from the evolutional point of view. The various 
opponents of Darwinism, and of evolution in its broader sense, 
have ever appealed to the sudden emergence of Cretaceous 
metaspermic plants as an unanswerable argument against the 
different development-hypotheses. There is not space here — 
even to cite the numerous works in which the unexplained 
and sudden appearance of Cretaceous metaspermic plants has 
been adduced in condemnation of the various evolutionary 
hypotheses. All students who have kept pace with the con- 
troversial biological literature of the last thirty years, will 
readily recall the important part that the Cretaceous plants 
have played in the anti-evolution polemic. 
In view of what has been stated above, the intent of this 
paper will be recognized as a sufficiently ambitious one, when 
it is stated to be an effort to show two facts, as developed by 
the study of modern plant-formations and the evidence of the 
fossils ; first, that the appearance of Cretaceous metaspermic 
plants is proved, by the fossils, not to have been sudden, but 
ual, and consequently, in Cretaceous time, the general 
preponderance of plant-population was strongly coniferous, 
fern and cycadean; and second, that the conditions of Creta~ 
ann eee ee 
ee E aes ae = Mem E EAEE tomate 
I Cee cre: ae Oe eT rs 
ceous time were such that the new and scattered metaspermi¢ a 
plants were placed under circumstances similar to those in 
