PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 543 
Oxoplecia planulata also has a compressed outline and thus suggests O. filosa, 
but the compression is more exaggerated and it has a wider and more elevated 
fold than the Oklahoma species. 
OXOPLECIA GIBBOSA Cooper, new species 
Plate 102, A, figures I-17 
Shell a little below medium size for the genus, roundly elliptical in outline, 
unequally biconvex in lateral profile. Lateral margins narrowly rounded; an- 
terior margin truncated. Sulcus occupied by 2 to 3 costellae and the fold by 3 
or 4. Flanks marked by about 6 costellae. Fila numbering 3 to 4 in a millimeter 
near the middle of the valve. 
Pedicle valve moderately convex in lateral profile and with prominent and 
erect beak; anterior profile broadly and gently convex; umbonal region convex ; 
sulcus originating slightly posterior to the middle, widening and deepening 
rapidly to occupy about half the valve width at the front margin. Tongue long 
and rounded. Flanks slightly convex to slightly concave in profile; lateral slopes 
moderate. Hinge width equal to about half the valve width. Interarea short; 
deltidial ridge low ; interarea gently to strongly apsacline. 
Brachial valve half again as deep as the pedicle valve, strongly convex in lateral 
profile with greatest convexity posterior to the middle. Beak prominent, over- 
hanging hinge margin. Umbo swollen. Fold originating at place of maximum 
curvature, low throughout its extent. Flanks gently convex with very steep 
lateral slopes. 
Measurements in mm,— 
Brachial Hinge 
Length length Width width Thickness 
PaO VANE S| cok eine «ie! sina ages p'sm 0.0. 12.5 11.4 14.9 6.5 9.6 
Pafatype (110655a) ......... 10.0 9.5 13.2 5.8 8.0 
% CETOS5§c Ph OTP, 9.3 8.6 II.1 5.1 7.0 
Types.—Holotype: 110860; figured paratypes: 110855a,c; unfigured paratype: 
T10855b. 
Horizon and locality—Ward Cove formation in Tennessee: At Inskip, E 2, 
604, 600-700/N-596, 350 (military coordinates), Fountain City (T.V.A. 
146-SW) Quadrangle; Hickey place, 2 miles southwest of Hall Crossroad, 
Fountain City (T.V.A. 146-SW) Quadrangle; Evans Ferry, Howard Quarter 
(T.V.A. 162-NW) Quadrangle; # mile southwest of Mount Eager Church, 
Hogskin Valley, Powder Springs (T.V.A. 154-SW) Quadrangle; $ mile north 
of Eidson, Kyles Ford (T.V.A. 170-SE) Quadrangle. 
Red Knobs formation in Tennessee: 1 mile north and 3 mile northwest of 
Meadow Station, Meadow (T.V.A. 139-NW) Quadrangle, 14 miles east of 
Friendsville, and 1 mile south of Louisville, Louisville (T.V.A. 138-SE) Quad- 
rangle. 
Base of “Ottosee’= Ward Cove horizon in Tennessee: At 1 mile southeast 
of Whitehorn, Bulls Gap (T.V.A. 171-SE) Quadrangle. 
Little Oak formation in Alabama: At Hebron Church, 6 miles southwest of 
