PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 687 
PROTOZYGA TUMIDA Cooper, new species 
Plate 140, G, figures 43-47; plate 141, I, figures 46-50 
Shell of about medium size for the genus, length and width nearly equal ; sub- 
pentagonal in outline; apical angle about 120°. Surface paucicostate, 4 or 5 
obscure costae on the flanks. 
Pedicle valve fairly strongly convex in lateral profile, and with the maximum 
convexity at about the middle; anterior profile narrowly convex in the median 
region and with steeply sloping sides. Umbonal region narrowly convex and 
continued anteriorly as an indistinct fold; fold prominent in the anterior third 
and marked by a deep and wide sulcus originating at about one-third the length 
from the anterior margin; flanks flat to gently concave and with steep slopes. 
Brachial valve shallow, gently convex in lateral profile and with the maximum 
curvature slightly posterior to the middle; anterior profile gently convex to 
nearly flat; umbonal and median regions swollen; sulcus originating just an- 
terior to the middle, broad and shallow; sulcus occupied by a narrow, rounded 
fold equal in length to about one-third the valve length. Sulci bounding fold 
fairly wide and moderately deep. Flanks gently inflated and with gentle slopes. 
Measurements in mm.— 
Length Width Thickness 
LOG VMe a cist ecrs crete <Gienoisrast= cheat Sielelstevend seokpereters 3.5 3:2 1.9 
ESIC TAT OUT eee CE ORE Meee sore. 3.0 2.9 1.6 
Types—Holotype: 111440; figured paratype: 111400. 
Horizon and locality.—Effna formation in Virginia: At McNutt Quarry, 12 
miles southwest of Bland, Burkes Garden (15’) Quadrangle; equivalent of Effna 
formation 4 and 6 miles southwest of Bland, Bland County. 
Discussion.—This species is characterized by its strongly pentagonal form and 
the broad, shallow brachial valve. The low convexity of this valve distinguishes 
the species from all the others herein described. 
PROTOZYGA UNIPLICATA Cooper, new species 
Plate 140, D, figures 22-26; plate 141, H, figures 42-45; plate 141, K, figures 58-62 
Shell small, longer than wide, heptagonal in outline; sides broadly rounded ; 
apical angle 100° ; surface smooth except for 1 or 2 obscure costae on the flanks. 
Pedicle valve fairly strongly convex in lateral profile and with the maximum 
convexity at about the middle; anterior profile narrowly convex but with long, 
steep, flat slopes. Umbonal region narrowly inflated; median region narrowly 
rounded, the rounding forming a fairly prominent but low fold at the anterior ; 
fold fairly deeply but narrowly sulcate in its anterior quarter to third. Sides 
steep and flat. Beak erect. 
Brachial valve gently convex in lateral profile and with the greatest convexity 
at the middle; anterior profile moderately rounded ; umbonal and median regions 
somewhat inflated; sulcus originating at about the anterior third and occupied 
by a prominent fold separated from the flanks by 2 narrow and moderately deep 
depressions. Flanks swollen and steep. 
