PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 549 
OXOPLECIA MULTICOSTELLATA Cooper, new species 
Plate 105, A, figures 1-27; plate 106, E, figures 25, 26 
Shell large, roundly elliptical in outline; sides broadly rounded; anterior mar- 
gin trilobate; valves unequally convex, the brachial valve having the greater 
depth; hinge narrow; uniplicate; multicostellate ; flanks with 14 to 19 costellae ; 
fold with 8 to 11 and sulcus with 7 to 10 costellae. Surface strongly filose, fila 
distant on body of shell, closely crowded at the margins. 
Pedicle valve with unevenly convex lateral profile, the posterior half having 
the greater convexity and the anterior half somewhat flattened. Anterior profile 
broadly and moderately convex. Umbo strongly convex; sulcus originating 5 
to 6 mm. anterior to the beak, shallow and poorly defined in the median region 
but deepening toward the front to attain about half the shell width. Sulcus 
bounded by a narrow plica in its anterior third; flanks bounding sulcus flat to 
gently concave and with gentle slopes. Interarea curved, apsacline. 
Brachial valve with greatest curvature in the umbonal region which is strongly 
arched and is almost level with the pedicle beak ; anterior profile strongly arched, 
but with only moderately steep slopes. Umbo swollen; median region swollen. 
Fold originating 6 to 7 mm. anterior to the beak, low and inconspicuous on 
the median part but fairly strongly elevated in the anterior region where it forms 
a lobate projection. Flanks somewhat swollen and steep posterolateral slopes. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Holtotypiess catiic: byes oa sesiae 19.9 19.2 23.0 12.4 12.9 
Paratype) (1iG IAA). cui 3.d sane 18.9 18.5 24.7 11.6 14.1 
Me GRETPDTC D2 shane 18.5 177 21.3 12.8 11.9 
Types.—Holotype: 111790; figured paratypes : 111791a,d-f, 117112, 117113a-c, 
e,h,j, II7I14a, 123334; unfigured paratypes: 111791Ib-c,g-i, 117113d,f,g,i,k-p, 
117114b. 
Horizon and locality.—Benbolt formation in Virginia: 0.2 mile south of the 
middle fork of Moccasin Creek, 14 miles south of Hansonville, Hansonville 
(T.V.A. 205-SW) Quadrangle ; west slope of the hill $ mile east of Cedar Point 
School, Hilton (T.V.A. 197-NW) Quadrangle; on Virginia Highway 74, 0.2 
mile southwest of New Bethel Church, 4 mile east of the junction with U. S. 
Highway 54, Hilton (T.V.A. 197-NW) Quadrangle; 4 mile southeast of Rich- 
patch, Eagle Rock (15’) Quadrangle; just east of meridian 17°30’ east of Moc- 
casin Creek, north edge of Mendota (T.V.A. 197-NE) Quadrangle; Virginia 
State Highway 80, 4 mile south of Rockdell, Elk Garden (T.V.A. 212-NW) 
Quadrangle; Fugates Hill, 2 miles N. 45° W. of Mendota, Bristol (30’) Quad- 
rangle ; 4 mile northeast of Speers Ferry, Clinchport (T.V.A. 188-NW) Quad- 
rangle; Green Valley, 3 miles south-southwest of Lebanon, Brumley (T.V.A. 
205-SE) Quadrangle; north side of U. S. Highway 19, 12 miles southeast of 
Hansonville Post Office, Brumley (T.V.A. 205-SE) Quadrangle. 
Benbolt formation in Tennessee: On the north side of the road 1.1 miles 
northeast of Lee Valley, Lee Valley (T.V.A. 171-NW) Quadrangle. 
