PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER I23 
Schizambon dodgei= S. perspinosum Cooper 
Sowerbyella variabilis Cooper 
Sowerbyites hami Cooper 
S. lamellosus Cooper 
Strophomena incurvata = S. costellata Cooper 
S. oklahomensis Cooper 
S. cf. planumbona = S. crinerensis Cooper 
*S. trentonensis 
Zygospira nicolleti = Protozyga loeblichi Cooper 
Correlation of Bromide formation.—The Bromide has been variously placed 
from the Chazyan to the Trenton (Loeblich, 1942, p. 413-416). Decker’s (1952) 
final pronouncement was correlation with the lower Trenton. Loeblich (1942, 
p. 417) states that “The evidence presented by the bryozoa suggests a lower 
Trenton age, and the fauna is closely allied to the Decorah of Minnesota.” The 
brachiopod evidence does not support this conclusion. This is, however, not the 
first instance in which age determination of the same formation based on differ- 
ent types of fossils is not in agreement. In considering the age of the Bromide 
from the brachiopod evidence, it is desirable to evaluate the brachiopods from 
the two divisions of the Bromide described above. 
The brachiopods occurring in the lower Mountain Lake member with its reefy 
beds include Atelelasma, Multicostella, Mimella, Sowerbyites, and Valcourea. 
These are genera that occur together in the Appalachian sequences in formations 
underlying the Benbolt formation. They are common particularly in the Lincoln- 
shire and Hogskin formations. The presence of Fascifera and Opikina suggest 
somewhat higher beds because the former has not been taken in the two Appa- 
lachian formations referred to below the Ward Cove. Conspicuously absent from 
the lower part of the Mountain Lake member is Strophomena, which becomes 
abundant in the Appalachians in beds above the Benbolt formation, particularly 
in the Wardell formation. The best correlation of the lower Mountain Lake is 
with the Lincolnshire. 
Upper Mountain Lake abounds in cystids, Platycystites and Cheirocrinus, with 
abundance of Sowerbyella, Chaulistomella, and Glyptorthis. Also present are 
Fascifera and Doleroides. Correlation with the Benbolt is suggested. 
Significant brachiopods occurring in the upper or light-colored Pooleville 
member are: Strophomena, Doleroides, Craniops, Campylorthis, and Ancistro- 
rhyncha. These genera characterize beds in the Appalachians and the Central 
Basin that overlie the Benbolt. The association, except for Craniops, appears 
first in the Wardell formation of the Appalachians and in the Ridley limestone of 
the Central Basin of Tennessee. The correlations thus suggested indicate that 
Bromide sediments spanned a time similar to the sediments of the Appalachians 
between, but including the Lincolnshire and the Wardell. 
Viola formation.—Information on this formation is now relevant to the dis- 
cussion of brachiopods forming the subject of this monograph because of Decker’s 
(1952) recent correlations of the Athens shale of Virginia with part of the Viola 
limestone of Oklahoma. The report of Nemagraptus in the Viola is quite dis- 
