PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER I9I 
or umbonal region. Anterior profile slightly less convex than that of pedicle valve 
and not so noticeably elevated in the median region. Beak marginal and small. 
Umbo and posterior third slightly swollen. Posterolateral margins and anterior 
two-thirds somewhat flattened. Umbonal slopes short but moderately steep. 
Measurements in mm.— 
Length Width 
Holotype :(brachialy valve): .iic.is A. «ssi deo entiona. eek 8.2 7.6 
Paratype, (pedicle valve \100329e), 0.3 scas}eyoo ne sind + ve amdas 6.8 6.4 
. (brachial valye Too320DN (os. swe o. eae aes 6.2 6.0 
Types.—Holotype: 109329a; figured paratypes: 109329b,d; unfigured para- 
types: 109329c,e-g. 
Horizon and locality—Lower Rich Valley formation, Porterfield Quarry in 
Virginia: 5 miles east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Discussion.—This species is characterized by its small size, slightly oval out- 
line, low convexity and depth of the valves. It differs from O. virginiensis in its 
smaller size, even, concentric ornamentation without radial elements, and broader 
beak angle. Specimens are fairly common in the thin-bedded Rich Valley 
formation. 
OBOLUS ? VIRGINIENSIS Cooper, new species 
Plate 7, E, figures 20-22 
Palaeoglossa belli Wittarp (not Billings), Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, 
No. 6, p. 255, 1928. 
Shell large, moderately thick, oval in outline and with the greatest width lo- 
cated just anterior to the middle; valves unequal in depth, the brachial being the 
deeper. Surface marked by uneven and interrupted undulations. Umbonal region 
and posterolateral areas marked by transverse rows of short, elongated pustules 
or elevated dashes separated by short gashes. Rows of pustules extending 
medianly to form a low chevron. 
Pedicle valve oval in outline with the greatest width located at about three- 
fifths the length from the beak ; lateral profile slightly convex and with the maxi- 
mum depth near the middle; anterior third flattened; anterior profile fullest in 
the median region and with short, moderately steep lateral slopes. Beak 
angle 95°. 
Brachial valve subcircular in outline and with all margins rounded. Beak 
marginal; umbo and central portion of valve swollen. Lateral profile more 
strongly convex than that of the pedicle valve; greatest convexity in the posterior 
third. Posterolateral slopes moderately steep. 
Measurements in mm.— 
Length Width 
Polerype (pemicle Valve). Fee vec crc nnmaeare shes 23.8-+ 20 + 
Patatype ‘(brachial valve’ 1009395) 622 P29 0EH) GFP 18.7-+ 18.5-+- 
Types.—Holotype: 109334; paratype: 109335. 
Horizon and locality.—Effna limestone in Virginia: Lower part of McNutt 
Quarry, 5 to 6 miles northeast of Ceres, Burkes Garden (15’) Quadrangle; on 
