PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 125 
Oranda is undoubtedly a derivative of the Arline whose black shale equivalent, 
if any existed, might conceivably have included a Nemagraptus derivative in the 
higher position. Possibly this is the case with Nemagraptus in the Viola—it is 
a holdover or recurrent Nemagraptus fauna equivalent to a middle Trenton 
brachiopod fauna. If this supposition should prove to be true, our views regard- 
ing the infallibility of graptolite correlation will be severely shaken. 
Womble (Stringtown) formation of Arkansas and Oklahoma.—A thick 
sequence of dark shales occurs in the Ouachita geosyncline in Arkansas and ad- 
jacent Oklahoma. This is the Womble (Stringtown in Oklahoma) shale which 
contains the Nemagraptus graptolite assemblage and is said (Decker 1952, pp. 
96-100) to be equivalent to the “Athens” of Virginia. Two brachiopods, Archae- 
orthis biconvexa Cooper, new species, and Paterula subcircularis Cooper, were 
taken from this shale in Oklahoma. 
g. THE BLACK HILLS, SOUTH DAKOTA 
Whitewood formation.—This formation as exposed just northeast of Dead- 
wood, S. Dak., consists of three members. The lowest member overlies the 
Scolithus sandstone of the Upper Cambrian Deadwood formation and consists of 
gray fissile shale containing scolecodonts and a few other fragmentary fossils. 
Above the shale occurs a coarse-grained, soft, light-gray siltstone which contains 
conodonts and remains of other types of fossils. The siltstone is transitional to 
the overlying dolomite member of the Whitewood formation which contains fos- 
sils of probable upper Devonian age. 
The shale and siltstone members are said by Furnish, Barragy, and Miller 
(1936) to be of medial Ordovician age. The scolecodont fauna of the shale indi- 
cates a correlation with the Spechts Ferry member of the Decorah formation. 
The siltstone contains the following brachiopods: 
Crania ? 
Dalmanella ? cf. D. hamburgensis (Winchell, not Walcott) = Dalmanella winchelli Cooper 
Lingula sp. 
Rafinesquina sp. 
Rhynchotrema cf. R. minnesotense (Sardeson) 
Sowerbyella sp. 
Strophomena sp. 
Zygospira 
This list of brachiopods and species of conodonts indicates a low Trenton 
(Rockland) age for the siltstone. 
I0. THE GREAT BASIN—NEVADA AND CALIFORNIA 
The Ordovician of the Great Basin region in Nevada and California has never 
been described in detail, and actually very little is known about it. In some areas 
rocks comprising the Pogonip group or formation have been assigned to the 
Chazy and some to the Black River and Trenton, but the faunas are nearly un- 
known. After two short visits to southern and central Nevada the writer is able 
