RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 271 
eastern Appalachians and to a small area in western Tennessee and 
Missouri (Kimmswick of Missouri), and do not occur in the usual 
‘ Ordovician fauna of the great interior basin. The eastern Appalachian 
belt extends from Gaspé to Alabama, and includes the “Trenton” at 
Percé, the Quebec City at Quebec, the “Trenton” of southeastern 
Quebec, the Chazy and Rysedorph of New York, the Chambersburg 
of Pennsylvania, the Liberty Hall and Murat of central Virginia, the 
Holston, Ottosee, Lenoir, and Athens of southwestern Virginia and 
eastern Tennessee, and the “Trenton” of Alabama. This series 
includes formations of various ages from Chazy to Upper Trenton. 
Russian genera which in America are restricted to the strata men- 
tioned above are Sphaerexochus, Lonchodomas, Christiania, Oxo- 
plecia, and Echinosphaerites. Genera prominent in this group, but 
only sparingly represented in the interior Ordovician are, Pseudo- 
sphaerexochus, Remopleurides, and Sphaerocoryphe. 
Of the other genera introduced during Wierland time, Ogygites does 
not appear in America till late Trenton (Collingwood), Cymbularia is 
unknown, as are also Cryptocrinites, Cystoblastus, Cyathocystis, 
Hemicosmites, and Protocrinites. The other genera are more or less 
common throughout the Middle Ordovician faunas of America. 
Some of the more striking of the Wierland guide fossils are absent 
from the Chazy, thus preventing what seems otherwise a very satis- 
factory direct correlation. These are Echinosphaerites, Christiania, 
and Oxoplecia. The fauna of the Chazy is, in fact, a curious mixture 
of native and immigrant ‘types. All its large molluscan fauna is 
probably derived directly from the Beekmantown fauna, and most of 
its brachiopods are also American in origin. There is certainly nothing 
in northern Europe like its great profusion of rhynchonelloids, and its 
Orthidae and Strophomenidae may as well be native types as invaders. 
Even Camarella, the Chazy representative of the Porambonitidae, is 
probably of American stock, and does not really represent the Russian 
Porambonites. In Clitambonites, however, we have a true immigrant, 
which did very well for a time. 
When we come to the trilobites, however, we begin to see the in- 
vaders. In the list we notice not only certain native genera, Bathyu- 
rellus, Isotelus, Isoteloides, Thaleops, and Glaphurus, but also many 
others, which are actually Russian or derived from Russian stocks. 
These are, Russian: — Eoharpes, Lonchodomas, Remopleurides, 
Nileus, *Ceraurus, Pseudosphaerexochus, Nieszkowskia, Sphaero- 
coryphe, Sphaerexochus, and Pterygometopus; derived from Russian 
stock: — Cybeloides, Pliomerops, Vogdesia, and Heliomera. 
PIM: | ae 
