302 L. F. Ward—Mesozoic Dicotyledons. 
The following table exhibits the number of dicotyledonous 
species thus far recognized in each of the groups of the Creta- 
ceous for the four principal geographical areas within which 
they have been collected : 
Cretaceous Dicotyledons. 
British United 
Geological Position. Europe. Greenland. America. States. Total. 
Upper Senonian -- 81 74 24 is 179 
Lower Senonian __..- 67 = 14 be 81 
Turonian. ey shal es os ee 
Cenomanian ) ..... §3° 114 
85] 
Dakota Group Sood s ‘ ae ay 184 
ault. ve mie =e ge se 
Cirgani kee om 1 we AB 1 
Neocomian eu ‘ce oe . -- 
Total 201 189 38 184 | 612 
As all the plants with which we are here concerned are found 
in the Cretaceous some may be surprised that this paper should 
have been entitled Mesozoic rather than Cretaceous Dicotyledons. 
The reason for the title chosen is simply that it may tend some- 
what 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 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 survives, we cannot if 
we would, repress the thought that the ancestors of these forms 
must have come down through older periods of the Mesozotc. 
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 
h w and secular — 
have had parents. Moreover, such is the slo 
lants as were the Dicotyledons in the Cenomanian age bat 
attained that condition in anything short of a vast geologic 
d eo 
It is to be hoped that we are at last approaching the begin: — 
ning, at least, of a solution of this truly great problem of ke 
specimens co 
fessor Wm. 
