PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 239 
Edinburg formation (Liberty Hall facies) in Virginia: 14 miles south of 
Wadesville, Winchester (15’) Quadrangle; opposite the bridge at Riverton, 
Front Royal (15’) Quadrangle. 
Oranda formation in Virginia: 4 miles northwest of Linville Station, Broad- 
way (15’) Quadrangle. 
Discussion.—This species is common in the Liberty Hall facies of the Edin- 
burg formation and in limestones associated with the black shale in Alabama, 
especially at the base. The most nearly comparable species is the small P. polita 
from the Viola formation of Oklahoma. The latter is smaller and somewhat more 
oval and with less convexity to both valves. 
PATERULA POLITA Cooper, new species 
Plate 24, A, figures 1, 2 
The known specimens of this species are somewhat smaller than those of 
P. perfecta, but there are a number of more important differences between the 
two species. The pedicle valve of P. polita is more narrowly rounded at the pos- 
terior and with a much smaller pedicle opening than in P. perfecta. The brachial 
valve of P. polita is much less convex than the same valve of P. perfecta. 
Measurements in mm.— 
Length Width Thickness 
Holotype (pedicle valve) .............-...06- 1.9 1.6 ? 
Paratype. (brachial valve) vi... 6... 6c capes Be 1.5 0.3 
Types.—Holotype: 109411b; paratype: 10941 Ia. 
Horizon and locality.—Viola formation (lower), in Oklahoma: SE4 sec. 32, 
T.2S., R. 2 E., 3 miles north-northeast of Springer, Murray County. 
Discussion.—For differences from P. perfecta see p. 238. 
PATERULA SUBCIRCULARIS Cooper, new species 
Plate 24, C, figures 7-10 
Shell fairly large for the genus, nearly circular in outline, the anterior margin 
somewhat more narrowly rounded than the posterior margins and producing 
a slightly oval outline. Surface marked by concentric undulations. The pedicle 
valve is gently convex in profile with the maximum convexity at about the middle 
where the valve is slightly swollen. Pedicle notch narrow and deep. Lateral 
border narrow on all margins, but widest on the posterolateral extremities. 
Brachial valve much like the pedicle valve and having nearly the same con- 
vexity. All borders narrow but the posterior one wider than the others. 
Measurements in mm.—Brachial valve (paratype 109414c), length 4.1, width 
3.6. 
Types.—Holotype: 109414b; paratypes: 10941 4a,c. 
Horizon and locality.—Stringtown shale= Womble shale (Big Fork chert) in 
Oklahoma: Near the center of sec. 29, T. 1 S., R. 12 E., on south bank of north 
Boggy Creek, near base of exposure, southwest of Stringtown, Atoka County ; 
