PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 117 
Auburn chert.—Residual chert in Lincoln County, Mo., contains numerous 
fossils listed by E. B. Branson (1909) and A. F. Foerste (1920). The brachio- 
pods in the fauna are: 
Dalmanella subaequata (Conrad) = Pionodema subaequata (Conrad) 
D. testudinaria (Dalman) = Paucicrura rogata (Sardeson) 
Hallina globularis Cooper 
Idiospira panderi (Billings) 
Lingula sp. 
Orthis tricenaria Conrad = Hesperorthis tricenaria (Conrad) 
Paucicrura rogata (Sardeson) 
Strophomena incurvata (Shepard) = S. auburnensis Fenton 
Rafinesquina minnesotensis (N. H. Winchell) = Opikina 
R. sinclairi Salmon 
Zygospira recurvirostris (Hall) 
Z. nicolleti Winchell and Schuchert = Protozyga superba Cooper 
Correlation of Auburn chert—lIt has been suggested that the Auburn chert 
should be included in the Plattin group (Bradley, 1925, p. 66), but the brachio- 
pods are not in accord with this suggestion from what is now known about the 
Auburn fauna. The presence of Rafinesquina indicates a higher correlation. It 
is here suggested that this formation may be chertified Decorah of Missouri= 
Barnhart formation, rather than Plattin and that the correlation should be with 
the Guttenberg member of the Decorah of the upper Mississippi Valley. 
NORTHERN ARKANSAS 
In the Eureka Springs, Harrison, and Yellville Quadrangles and adjacent 
areas to the east, the Buffalo River group is well exhibited. The section here 
from the bottom up is: Everton, Jasper, St. Peter, Joachim, and Plattin forma- 
tions. As in the Missouri section, fossils are rare and brachiopods are not known 
from the Buffalo River group except in the Everton-Jasper limestones. 
Everton-Jasper formation.—According to McKnight (1935, p. 40) the 
Jasper limestone has a maximum thickness of 50 feet and is indistinguishable 
from denser phases of the Everton limestone below. The Jasper was originally 
thought to be above the Joachim and St. Peter formations, but McKnight indi- 
cates that these formations were incorrectly identified in the Eureka Springs— 
Harrison Folio. The rocks so identified in reality are only parts of the Everton. 
McKnight further states that according to present evidence the Jasper limestone 
“interfingers with the dolomitic facies in the upper part of the Everton and 
should be considered a member of the Everton.” The following brachiopod was 
found in the Jasper at Pindall: 
Onychoplecia matutina Cooper 
Correlation of Everton-Jasper formation—The one species of brachiopod 
(Onychoplecia matutina Cooper) known from the Everton-Jasper does not per- 
mit a good correlation. However, the position below the St. Peter and the pres- 
ence of Onychoplecia is a possible link with the Lenoir of the Appalachians. 
Plattin formation.—This formation in the Yellville Quadrangle ranges from 
