660 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Measurements in mm.— 
Brachial 
Length length Width Thickness 
Pitatyper ss.) suite gacaoieeei. 5.1 4.7 6.0 ? 1.7 
Paratype, (98205) 5)0'.)s ube Peaakh os 5.0 4.8 37 2.5 
Types.—Holotype: 117197a; figured paratypes: 98205, 117197b,c, 117198a,b, 
118025 ; measured paratype: 98205. 
Horizon and locality—Benbolt formation in Virginia: In the road cut on 
U. S. Highway 19, 14 miles southeast of Hansonville, Brumley (T.V.A. 205-SE) 
Quadrangle; Miller Farm on northwest slope of Wallen Ridge, about 2 miles 
southeast of Ollinger, Ollinger (T.V.A. 178-SE) Quadrangle; 4 mile north- 
west of Rye Cove, Clinchport (T.V.A. 188-NW) Quadrangle. 
Benbolt? formation in Virginia: 44 miles southwest of Bland, Bland County. 
Edinburg formation (St. Luke facies) in Virginia: On Swover Creek, 4.6 
miles N. 69° W. of Edinburg, near Lantz Mills, Edinburg (15’) Quadrangle. 
Witten formation in Virginia: On Virginia Highway 81, 14 miles southwest 
of Tazewell, Tazewell (15’) Quadrangle; at turn of the road southwest of Jeff 
Gillespie’s on Virginia Highway 88, 14.4 miles west-southwest of Tazewell. 
Surgener formation (red beds) in Tennessee: On the roadside 0.3 miles north 
of the Church at Rose Hill, Maynardville (T.V.A. 145-SE) Quadrangle. 
Wardell-Witten (=Dryden) formation in Tennessee: On the east side of 
Long Branch 1.3 miles northeast of Lone Mountain Station, Tazewell (T.V.A. 
154-NE) Quadrangle; Eidson, Kyles Ford (T.V.A. 170-SE) Quadrangle; 
bed 41, opposite Thorn Hill store on U. S. Highway 25E, Avondale (T.V.A. 
162-SW) Quadrangle ; above old marble quarry, $ mile southeast of Hambright 
Mine, 8 miles south of Cleveland. 
Ward Cove formation ? in Tennessee: Mulberry Gap, 4 miles north-north- 
west of Sneedville, Back Valley (161-SE) Quadrangle. 
Benbolt formation in Virginia: 4 mile southeast of Richpatch, Eagle Rock 
(15’) Quadrangle; on Virginia County Highway 616, 0.6 mile northwest of the 
junction with County Highway 621, Richpatch, Eagle Rock (15’) Quadrangle. 
Discussion.—This species is characterized by a short plication in the front part 
of the sulcus of the pedicle valve and a bifurcation of the median fold of the op- 
posite valve to produce a sulcus in the fold for the accommodation of the median 
plication. The only other species like this one is O. elongata, but that species 
differs in other respects. It is long and slender and scarcely expanded anteriorly, 
whereas O. bifurcata is fairly broadly triangular and fairly wide anteriorly. 
OLIGORHYNCHIA ELONGATA Cooper, new species 
Plate 126, A, figures 1-5 
Shell small, elongate triangular in outline, compressed in lateral profile ; widest 
at the front; sides nearly straight; apical angle about 40°. Sides flattened. 
Brachial valve slightly deeper than the pedicle valve. Widest at the front. 
Pedicle valve gently convex in lateral profile, marked by 2 strong elevated and 
subangular costae that bound a deep but narrow sulcus; sulcus occupied by a 
