338 DAVID WHITE 
t. The tremendous size and great height of the types, and their 
rank foliar development, indicating favorable conditions of environ- 
ment and vigorous nutrition. 
2. The succulent nature of many of the forms, the large size of the 
vessels and cells and the relatively great proportion of soft tissue, all 
indicating rapidity of growth in a moist, mild climate. 
3. Spongy leaves suggestive of a moist atmosphere, and abundant 
and large intercellular spaces, as in the Lycopods, pointing to rapid 
moisture loss; also water pores for disposal of excess of moisture. 
4. Stomata placed in grooves, as in the Lycopods, as if to prevent 
obstruction by falling rain. 
5. Absence of annual rings in the woods; hence absence of marked 
seasonal changes. 
6. The analogies of the present day show that aérial roots, so 
prominent in many of the Carboniferous types are characteristic of 
moist and tropical climates; that the nutrition—i.e., the decom 
position of CO,—is most rapid and the consequent growth also 
greatest and most rapid where the light is not too strong; that the 
ferns and Lycopods, so abundant in the Paleozoic, usually avoid 
bright glare. The same types are able to withstand larger amounts 
of CO, with benefit to themselves. 
7. The nearest living relatives of the Paleozoic vascular Crypto- 
gams reach their greatest size in humid and mild or warm climates. 
The successors of the marratiaceous, and gymnospermous types are 
now mostly confined to tropical or subtropical regions. ‘The cycada- 
lean stock, now characteristic of the same zones, was actually present 
in the upper coal-measures. 
8. The formation of great amounts of coal indicates a rank growth, 
but in a temperature not so warm as to promote decay beyond the 
limit of rainfall protection. 
g. Living nearest representatives of Paleozoic fishes now inhabit 
the estuaries of warm countries; while the nearest relatives of the 
Carboniferous insects are now found in mild and moist habitats. 
ro. The most forcible argument, after all, for an equable and 
uniform climate lies in the extraordinary geographical distribution 
of the floras in relative unity over the face of the earth. Humidity 
must naturally have attended such equability, extending, without 
