116 THE AMERICAN NATURALIST. 
Manifestly the flora which occupies the coast region will have 
its habitat more and more restricted in area, and will be driven 
more and more towards the tension zone, where the struggle 
for existence will become fiercer and the weaker elements will 
succumb. Thus not only are the physical changes in the 
environment inimical, but also the trend of biologic evolution. 
The sequence of events in the evolution of the vegetable 
kingdom show conclusively that the gymnosperm type is a 
waning one, and that the more highly developed angiosperms 
have been slowly but inevitably crowding it out since early 
Cretaceous times, and at the present time, in any competition 
for the occupancy of a region at all favorable for the angio- 
sperms, these latter are sure to prevail, and the conclusion 
appears to be inevitable that the flora of the coniferous zone 
is destined to be ultimately obliterated or only to exist over 
limited areas, often for the negative reason that in such areas 
the conditions may not be favorable for the growth of other 
types. The influence of man may produce temporary changes 
and give temporary advantage one way or the other, as may 
often be seen in the occupation by cedars or pines of land 
which has been recently cleared of deciduous trees ; but such 
changes are artificial and sporadic and cannot prevail over 
the constant and inevitable progress of physical and organic 
evolution. 
Not only is the gradual extinction of the gymnosperm type 
thus indicated, but by the same method of reasoning the angio- 
sperms characteristic of the coniferous zone must of necessity 
be the first to die out in that class, not only because of the 
gradual restriction of the area which they occupy, but also 
because, as is well known, the genera represented are older and 
the flora as a whole is less modern in its characteristics than 
obtain in the angiosperm flora of the deciduous zone. The 
genera of the coniferous zone are largely confined to America, 
whereas those of the deciduous zone are largely common to 
both America and Europe. These latter are thus of wide and 
_ varied distribution ; they occupy a region practically unre- 
stricted in area, and represent more recently evolved types of 
vegetation. 
