268 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Anterior two-thirds ornamented by lamellae bearing spines of 2 sizes, many small 
spines and a few large ones; last 3 lamellae at the front crowded together. 
Brachial valve strongly convex in anterior profile and moderately strongly 
convex in lateral profile. Sulcus deep but narrow in the umbonal region, widen- 
ing anteriorly for about one-third the length and then disappearing. Umbonal 
region for about one-third its length marked by distant elevated concentric 
threads and moderately crowded large spines. Lamellae of anterior two-thirds 
moderately distant, provided mainly with large spines. Small spines few. 
Measurements in mm.—Holotype, length 15.8, width 13.2, thickness 8.5. 
Types.—Holotype: 98204a; figured paratypes: 116928a-c. 
Horizon and locality—Wardell formation in Virginia: Lloyd Carter’s barn, 
3 mile by road northeast of Rye Cove, Clinchport (T.V.A. 188-NW) Quad- 
rangle; south of road, 4 mile east-northeast of Belfast Mill, Saltville (T.V.A. 
212-NE) Quadrangle; 4 mile northwest of Rockdell, Elk Garden (T.V.A. 
212-NW) Quadrangle; 13 miles west of Rye Cove, Clinchport (T.V.A. 
188-NW) Quadrangle. 
Benbolt formation in Virginia: Behind Brick Church west of Rye Cove, 
Clinchport (T.V.A. 188-NW) Quadrangle. 
Discussion.—This species in size and outline is very like S. cuneatum, but it 
differs in having an unusually large and wide foramen, the median sulcus of the 
brachial valve is faint and scarcely reaches the middle, while the ornamentation 
consists of strong, thick lamellae. 
SCHIZAMBON PERSPINOSUM Cooper, new species 
Plate 15, C, figures 7-17 
Shell of moderate size for the genus; oval in outline with the length slightly 
greater than the width. Lateral and front margins strongly rounded ; apical angle 
about 120°. 
Pedicle valve with posterior two-thirds slightly swollen and gently convex, 
anterior third flattened or depressed to produce a slight inward bend. Beak 
blunt, pedicle track extending for about one-third valve length. Foramen large 
and oval. The region about the beak is ornamented by evenly spaced, elevated 
concentric lines. Anterior to the beak the lamellose structure of the shell be- 
comes pronounced, and the concentric lines, though still present, become less and 
less numerous anteriorly. 
Brachial valve elongate ovate in outline with moderately rounded lateral mar- 
gins and narrowly rounded anterior margin. Lateral profile gently convex with 
a slight geniculation toward the pedicle valve in the anterior third to half. An- 
terior profile moderately but unevenly convex, the lateral portions incurving nar- 
rowly. Posterior half ornamented by elevated discontinuous and wavy concen- 
tric lines which are interrupted by scattered large spines. In the anterior half 
the valve becomes lamellose, the concentric lines become fewer and disappear. 
Each lamella bears on its edge long, hollow spines up to 6 mm. in length. 
