PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 681 
PROTOZYGA MICROSCOPICA Cooper, new species 
Plate 141, D, figures 22-24; plate 141, F, figures 33-37 
Shell minute, subpentagonal in outline; sides gently rounded ; anterior margin 
truncated; posterolateral margins straight, forming an apical angle of about 
100°. Surface smooth, except for a short fold on the brachial valve and 2 obscure 
costae on the pedicle valve. 
Pedicle valve fairly strongly convex in lateral profile and with the maximum 
convexity slightly posterior to the middle; anterior profile narrowly convex in 
the median region but with concave lateral slopes. Umbo narrowly rounded; 
median region swollen narrowly to form an indistinct fold which is marked 
medially by a deep sulcus originating about one-third the length from the anterior 
margin. Sulcus bounded by short, narrow costae. Flanks gently concave. 
Brachial valve gently convex in lateral and anterior profiles; umbonal and 
posteromedian areas swollen ; sulcus broad and shallow, originating at about one- 
third the length from the anterior margin, occupied almost completely by a low, 
rounded fold corresponding to the sulcus of the pedicle valve; fold separated 
from the flanks by short, narrow grooves. Flanks gently inflated. 
Measurements in num.— Length Width Thickness 
VOLS Eyed hye a: Saini rcs «5 erste cheiaed + siaeretawn sys 3.3 2.9 2.0 
PEA O Es the teh Riots oars Pens tomate eae canes ae 22 1.9 1.3 
Types.—Holotype: 117243 ; figured paratype: 117244. 
Horizon and locality.—Lincolnshire formation (Hogskin member) in Tennes- 
see: 3 mile east-northeast of Red Hill, about 4 miles west-southwest of Thorn 
Hill, Avondale (T.V.A. 162-SW) Quadrangle ; 3 miles west-southwest of Thorn 
Hill, same quadrangle; Luttrell, Luttrell (T.V.A. 155-NW) Quadrangle. 
Ward Cove formation in Tennessee: At Evans Ferry; in Mulberry Gap 4 
miles north-northwest of Sneedville, Back Valley (T.V.A. 161-SE) Quadrangle. 
Ward Cove formation in Virginia: On Virginia Highway 82, 14 miles north- 
west of Lebanon, Lebanon (T.V.A. 205-NE) Quadrangle. 
Elway formation in Tennessee: At Marble Bluff, 8 miles west-northwest of 
Loudon, Loudon (30’) Quadrangle. 
Discussion.—This species is characterized by its convex valves and the sub- 
dued nature of the folding of both valves and the margins. Protozyga micro- 
scopica has a less prominent beak than P. nasuta, which it resembles in contour, 
and is also more prominently sulcate in the pedicle valve than that species. 
Protozyga loeblichi has a less prominent fold than P. microscopica and lacks 
costae on the margins. Protozyga rotunda is a larger and more robust shell which 
is more strongly costate than P. microscopica. 
PROTOZYGA NASUTA Cooper, new species 
Plate 141, G, figures 38-41 
Small for the genus, subpentagonal in outline ; lateral margins gently rounded ; 
anterior margin gently rounded; anterior commissure nearly rectimarginate ; 
surface smooth and without visible costae. 
