UPPER PALEOZOIC FLORAS 323 
Place of origin.—Though eastern America has contributed most to 
our knowledge of this flora, it is probable that either the estuaries of 
northwestern Europe or the Arctic regions offered the conditions 
most favorable for its development. It extended both east and west 
in a high degree of unity. For example, the flora which occurs in 
the “Chapman” sandstone in Maine, and which is present in the 
gulf region of Canada, is largely the same as that of Scotland, at 
Burnot in Belgium, or in the Lenne shales of the Rhine Provinces. 
The flora from Barrande’s H-h, stage at Hostim in Bohemia is nearly 
counterfeited in the upper Middle Devonian of New York. The 
route of migration between Europe and America was presumably 
by Arctic lands beyond the North Atlantic. Nothing that can be 
called a land flora is yet known from the Middle Devonian of the 
Southern Hemisphere. 
UPPER DEVONIAN 
Floral characters.—Evolution of forms and the advent of new 
types mark the Upper Devonian flora, which bears no evidence of 
any great climatic separation from the preceding. Pseudobornia, 
perhaps first of the Protocalamariales, Dimeripteris, Leptophleum, 
Barrandeina, and Barinophyton are characteristic. It is pre-emi- 
nently the stage of Archaeopteris. The Protolepidodendreae are 
developing along divergent lines to Cyclostigma and to the Carbonif- 
erous Lepidodendron, while Archaeosigillaria makes its rare appear- 
ance. 
Place oj origin and migration.—\ am strongly inclined to believe 
that this flora received its greatest contribution from eastern America, 
or, perhaps, from the Arctic regions; in either event its migration 
was probably over boreal land; for it extends with remarkable 
identity from Pennsylvania to southern Europe and is partially 
present even in Australia. Archaeopteris obtusa and A. sphenophyl- 
lijolia of Pennsylvania and New York are A. archetypus and A. 
fissilis of Ellsmere Land, Spitzbergen, and the Don; while Barino- 
phyton, a unique type from New York, Maine, and Canada, extends 
to the British Isles, Belgium, Queensland, and Victoria, where also 
is found Leptophloeum rhombicum, another American plant. 
The Devonian woods present no annual rings to bear evidence of 
seasonal changes in temperature or intervals of prolonged drought. 
