PART I CHAZYAN AND RELATED BRACHIOPODS-——-COOPER 321 
multicostellate, costellae high and narrowly rounded, primary costellae strong and 
standing above the others ; 3 generations of costellae are intercalated, the last gen- 
eration appearing near the margin and tending, with the major costellae, to form 
prominent fascicles. About 10 costellae including all sizes may be counted at the 
median part of the front margin. 
Pedicle valve moderately convex in lateral profile, gently convex and humped 
slightly in the middle in anterior view. Median region slightly swollen; slopes to 
cardinal extremities concave, gentle. Interarea short, curved, anacline. 
Brachial valve slightly concave in lateral profile; sulcus originating almost at 
the posterior margin, widening rapidly anteriorly and extending to the anterior 
margin. Flanks flattened ; cardinal extremities flat and deflected slightly toward 
the pedicle valve. 
Measurements in mm.—Holotype, length 9.8, brachial length 9.2, width 13.0, 
hinge width 17.1, thickness 2.3. 
Type.—Holotype: 110356. 
Horizon and locality.—Benbolt formation in Virginia: 4 miles east-northeast 
of Gate City, Gate City (T.V.A. 188-NE) Quadrangle. 
Discussion.—This species differs from P. bella in possession of more strongly 
differentiated and more pronounced fasciculation of the costellae. 
CYRTONOTELLA GRANDISTRIATA (Willard) 
Plate 39, D, figures 16-19 
Rafinesquina grandistriata WILLARD, Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, No. 6, 
p. 282, pl. 2, fig. 11, 1928. 
Dinorthis ? sp Butts, Virginia Geol. Surv. Bull. 52, pt. 2, pl. 80, figs. 18, 19, 1942. 
Shell large for the genus, wider than long and with the hinge forming the 
greatest width. Cardinal extremities acute, alate. Lateral margins sloping medi- 
ally; anterior margin broadly rounded. Surface multicostellate, costellae high 
and narrowly rounded, appearing in 4 generations by implantation and bifurca- 
tion. Primary and secondary costellae the stronger and tending to group the 
ternary and quaternary costellae into fairly well marked fascicles. 
Pedicle valve strongly convex in lateral profile in the posterior half, gently 
convex in the anterior half. Anterior profile broadly convex with the median 
part the most convex. Umbonal region moderately convex, but the region just 
anterior to the umbo swollen and the valve somewhat inflated nearly to the front 
margin along the median line. Slopes to cardinal extremities steep, those to the 
anterior and anterolateral margins less steep. 
Brachial valve moderately concave in lateral profile; umbonal region slightly 
convex. Posterior to the middle the valve becomes moderately concave, and this 
portion is the most concave part. Flanks slightly convex and cardinal extremi- 
ties flattened. 
Pedicle interior with widely flaring dental plates; brachial interior with short 
and small brachiophores, small cardinal process. 
Measurements in mm.—Hypotype (pedicle valve 109857), length 22.7, width 
28.2, hinge width 35.2?, thickness 4.8. 
