Mr. L. F. Ward on Mesozoic Dicotyledons. 395 
ceous Dicotyledons. ‘The reason for the title chosen is simply 
that it may tend somewhat to enlarge the view of the true 
history and age of this great type of vegetation. When we 
see that more than three hundred and fifty species of fully 
developed Dicotyledons, implying the existence of many more, 
were flourishing in all their present luxuriance in the Middle 
Cretaceous, and that even in the Lower Cretaceous one species 
is known to have existed belonging to a genus that still sur- 
vives, we cannot, if we would, repress the thought that the 
ancestors of these forms must have come down through older 
periods of the Mesozoic. 
That we shall ever discover the true progenitors of the 
known Dicotyledons it is, of course, impossible to say ; but 
that they had progenitors science no more hesitates to assume 
than any one would hesitate to assume that a foundling child 
must have had parents. Moreover, such is the slow and 
secular character of the development of living forms on the 
globe, that no one would suppose it possible for so prominent 
a group of plants as were the Dicotyledons in the Cenomanian 
age to have attained that condition in any thing short of a 
vast geologic period. 
It is to be hoped that we are at last approaching the be- 
ginning at least of a solution of this truly great problem of 
the origin of the Dicctyledons. I have myself seen at least 
one slight, it may be, but very interesting sign of possible 
progress in this direction. Certain very defective, but very 
instructive, specimens collected in the Upper Jurassic of Vir- 
ginia by Professor Wm. M. Fontaine, and which he kindly 
brought to Washington for my inspection, certainly possess 
all the essential elements of dicotyledonous leaves, although 
at the same time bearing a certain recognizable stamp of the 
cryptogamic and gymnospermous vegetation that characterizes 
that earlier age. What is to be the final verdict of science 
upon these forms cannot now be told; but it is to be hoped 
that the Mesozoic strata, not only in Virginia, but in all parts 
of the world, may be diligently searched and the materials 
carefully studied, with a view to discovering these certainly 
merely ‘missing links” of a chain that can but have been 
once complete. 
It is iemarkable that in both its flora and its fauna the life 
of this continent has been thus abruptly truncated. The 
sudden irruption of a perfectly developed mammalian fauna 
at the beginning of the Tertiary is not less astonishing than 
the appearance unannounced of many hundreds of species 
of highly organized dicotyledonous plants in the Middle 
Cretaceous. ‘I'he advocates of special creation, and likewise 
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