tan northern hemisphere plants and pointed out the 
marked resemblance between Kuropean and American 
fossil floras. He recognized as such the process of specia- 
tion in space and time. Furthermore it was he who dem- 
onstrated that the Miocene floras of California are iden- 
tical with those in Colorado and east of the Rocky 
Mountains, proving beyond doubt the recency of Rocky 
Mountain uplift. He demonstrated the differences as well 
as similarities between European and American floras and 
denied any former continental union between the two 
excepting northern land bridges. He used, with success, 
fossil plants as “‘horizon markers’’ to identity coal seams, 
even in such complicated strata as the Anthracite Coal 
Fields. 
In 1868 the collection contained 2500 specimens 
belonging to some 500 species. By 1885, the time of final 
donations from Lesquereux, it had grown to 10,000 
specimens of 2000 ‘‘varieties.”” This entire priceless as- 
sortment has passed through the hands of Lesquereux. 
Within the past fifty years by purchase and donation the 
collection has been trebled in specimens and doubled in 
species—truly aremarkable collection unequalled in Amer- 
ica! Its value scientifically has in no manner diminished, 
but rather increased proportionately with the years. Since 
many of the fossil plants possessed cosmopolitan distri- 
butions, or at least are believed to have, it is necessary 
that each of Lesquereux’s species be accurately known. 
The great majority of American fossil types published 
prior to 1890 are poorly described and inadequately fig- 
ured — if figured at all. Consequently neither American 
paleobotanists nor their European colleagues know the 
true nature of these long-used specific names of reputed 
validity. 
During the final period of his lite, Lesquereux suf- 
tered from the loss of his faculties more and more. Asa 
[118 ] 
