178 
elsewhere. We note with some amusement that the author's 
rigid conscientiousness has caused him to take up Rafinesque’s 
misprint name “ Scoria,’ instead of “A/icoria,’ as he originally 
wrote it. The limitations of many genera and families are cur- 
tailed or extended, as the case may be, and several old genera are 
revived. 
The bibliography and synonomy cover families, genera and 
species and evince an immense amount of careful and conscien- 
tious research, which will save many hours of labor to future 
workers in metaspermic botany for which they owe the author a 
heavy debt of gratitude. An innovation which will be welcomed 
by many is the citation, under the genus, of any fossil form which 
may have been identified. In this connection the geological 
horizon, locality and authority are given. 
Following the list is a general description of the region, which in- 
cludes its geographical location, physiography, distribution of forest 
and prairie, soil, climate and geological history. The palzobotanist 
will find in the chapter entitled, “ Relationships of the Metaspermic 
Flora of the Minnesota Valley,” much of interest and more or less 
food for thought. The old problems in regard to plant dissemina- 
tion and distribution are again brought forward. “How did the 
present plant inhabitants enter the Minnesota Valley?” ‘What 
relation does this modern plant-population bear to the more ancient 
one which was overwhelmed by the glacial detritus, piled 250 feet 
thick over the old level of the country?” “Under what laws did 
the repopulation of the Valley progress?” “Along what routes 
did the incoming plants travel?” etc. The author begins this 
discussion by calling attention to the constant condition of strain 
or tension that exists between plants or groups of plants in the 
struggle for existence—in other words their “ dynamic inter-rela- 
tion.” Such a condition he thinks should be recognized more fully 
in terminology and suggests that instead of speaking ofa ‘‘ northern” 
group of plants we should designate it as the “ south-bound” 
group, and similarly a southern group might be called a “ zorth- 
bound” group, as these plants, already established in the north or 
south, as the case may be, have probably reached their limits of 
extension to the north and south respectively, and whatever 
further extension is to be accomplished must be southward for the 
