UPPER CARBONIFEROUS 313 
Europe, especially Russia, than with those much nearer geographic- 
ally, in eastern North America. Indeed, the correspondence of our 
western faunas with those of Russia is truly remarkable. The Russian 
series consists, in ascending order, of the Mountain limestone, or 
Productus giganteus zone; the Moscovian, or ‘“‘ Lower Carboniferous;”’ 
the Gschelian or “Upper Carboniferous;’’ the Artinskian or ‘“‘ Permo- 
Carboniferous” and the Permian. One school of Russian geologists 
includes the Artinskian or Permo-Carboniferous beds in the Permian, 
and some Americans have followed them, but this seems to be of 
doubtful propriety. Murchison, DeVerneuil, and Keyserling mistook 
the Artinsk sandstone for the Millstone grit and distinctly excluded it 
from the Permian. If the faunal relations demand this extension of 
the term Permian to the Artinsk it would be justifiable, but such 
isnot the case. At least, this appears to be the judgment of Tscherny- 
schew, the chief of the Russian Survey, and other distinguished 
paleontologists at all events. In this recital the term Permian is used 
in exclusion of the Artinsk beds. 
The Productus giganteus zone seems to be represented on this 
continent by the Baird shale of California whose fauna likewise con- 
tains P. giganteus. 
The Moscovian, which has a facies very like our common Pennsyl- 
vanian faunas, may be compared with the earliest Pennsylvanian of 
Arizona and Utah, the term ‘Lower Carboniferous,’ as used by the 
Russians, having no relation to our own Lower Carboniferous or Mis- 
sissippian. ‘The Gschelian is clearly related to our Hueco formation, 
but with this zone the closeness of the analogy ceases. One is tempted 
to place in alignment the Artinsk and Permian which succeed the 
Gschelian in the Russian section, with the Delaware Mountain 
formation and Capitan limestone which succeed the Hueco formation 
in the American section, but such a correlation is neither sharply 
contradicted nor substantially supported by the faunal evidence. 
In fact, as exhibited in the literature, the faunas of the Artinsk and 
Permian are much less varied and individualized than those of the 
Guadalupian. The following suggestions are made with the diff- 
dence of second-hand and imperfect knowledge, but it would appear 
that after the Gschelian stage there was in the Russian area a gradual 
progression from marine to at least near-shore conditions. This 
