PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 563 
maximum convexity at about the middle; anterior profile strongly domed but 
crest of dome somewhat flattened ; umbonal and median region strongly inflated ; 
fold short and low. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Slee.” ieee aS 8 ae arn 8.2 8.0 8.5 1.5 5.6 
Picured specimen ©. 5/..0s.%.... 7.0 6.9 7.0 1.6 4.7+ 
Types.—Holotype: 117129; figured specimen: 111341. 
Horizon and locality.—Bromide formation (Pooleville member-Oxoplecia 
gouldi zone) in Oklahoma: At Rock Crossing, about center sec. 35, T. 5 S., 
R. 1 E., Criner Hills, Carter County. 
Discussion.—This species is characterized by its smooth posterior three-quar- 
ters or more and the strong anterior costation. The brachial valve is swollen, and 
the umbo is elevated almost flush with the beak of the pedicle valve. This species 
is very similar to Camerella sp. 3 from the Benbolt limestone in general appear- 
ance, but the latter is a somewhat wider shell with a less convex brachial valve 
and less produced umbo. The apical angle of the Oklahoma species is less than 
that of the Benbolt form, and the sulcus of the latter is deeper and originates 
nearer the middle. 
CAMERELLA BELLA Fenton 
Plate 112, C, figures 8-15 
Camerella bella Fenton, Amer. Midland Nat., vol. 11, p. 136, pl. 3, figs. 1-12, 1928. 
Shell of medium size for the genus, subpentagonal to suboval in outline, slightly 
longer than wide. Greatest width in the anterior third. Beak angle about 87°, 
defined by nearly straight posterolateral margins; lateral margins narrowly 
rounded. Anterior margin truncated. Surface costate; 2 or 3 costae occupy the 
sulcus, while 3 or 4 occur on the brachial fold. Flanks marked by 4 costae. 
Lateral profile of pedicle valve with maximum curvature in the posterior third, 
the anterior two-thirds somewhat flattened. Anterior profile a depressed arch. 
Sulcus originating abruptly at 74 mm. anterior to the beak, shallow and widen- 
ing slightly anteriorly to occupy a little more than half the width at the front 
margin. Tongue moderately long, truncated. Umbo somewhat swollen pos- 
teriorly but flattening anteriorly to the place of origin of the sulcus. Flanks mod- 
erately elevated above the sulcus anteriorly, slightly convex and with gentle slopes 
to the margins. 
Brachial valve fairly strongly convex in lateral profile with the greatest curva- 
ture at the umbo; somewhat narrowly rounded in anterior profile. Umbonal and 
central region somewhat inflated. Fold originating about 6 mm. anterior to the 
beak, low and only slightly elevated above the flanks. Fold gently convex in 
profile. Flanks gently rounded but with very steep slopes to the margins. An- 
terior reentrant to receive tongue short. 
Interior with a deep and fairly wide spondylium supported by a short septum 
