328 DAVID WHITE 
senting filicoid types of fructification. One-half of these genera 
scarcely, if at all, survive the Pottsville. Three or four only outlive 
the Allegheny. The Westphalian witnessed the maximum develop- 
ment in Sphenopteris, Neuropteris, and Alethopteris, and of the great 
Lycopod group. It is pre-eminently the stage of the Cycadifilices. 
Remarkable distribution of identical species—The intercontinental 
distribution of the Westphalian plants is probably less remarkably 
uniform than is generally stated. The examination of the floras shows 
minor differences between the floras of different basins, as, for 
example, freshwater or marine basins in the same country, though 
many of these differences disappear as additional material is collected. 
Also different areas in the same basin, and, similarly, different hori- 
zons in the same basin may show predominances of Lycopods, or 
ferns, etc., or the apparent absence of certain genera. But as between 
the larger provinces, and taking the flora as a whole, from continent 
to continent, the number of genera not common, for example, to 
Europe and America, is so small as to excite special interest. The 
proportion of identical species is so large as to necessitate an extra- 
ordinary lack of barriers to the freest migration. ‘The flora of the 
basin of Heraclea in Asia Minor’ lends itself to ready correlation, 
stage by stage, with three corresponding formations of the Pottsville 
in the Appalachian trough; also, of the 33 species reported by Zeil- 
ler in a collection from the Westphalian of the Djebel-Bechar region 
of Persia, 25 are present in the Pottsville of the Appalachian trough. 
The uniformity of distribution of the Westphalian flora complicates 
the geographical question of its origin. Taking therefore as most 
reliable the evidence of first appearances, we may note that Cheilan- 
thites (including portions of Pseudopecopteris and Sphenopteris), 
Mariopteris, Eremopteris, Neuropteris, Alethopteris, and perhaps 
Pecopteris, were more highly differentiated in America, though 
Sphenopteris experienced a perhaps greater development in Austria 
and Bohemia. In Europe the Lycopods appear to have had greater 
advancement. Also, Cingularia, unknown outside of the freshwater 
basins of Germany, and Lonchopteris, largely confined thereto, have 
not yet been found in North America; while the unique genus 
Neriopteris is still unknown in Europe. On the other hand, the rare 
t Jour. Geol., Vol. IX (1901), p. 192. 
