PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 205 
LINGULELLA SUBPARALLELA Cooper, new species 
Plate 4, B, figures 5-8 
Shell small, longitudinally narrowly elliptical ; lateral margins faintly rounded, 
nearly parallel; anterior margin narrowly rounded. Beak of pedicle valve form- 
ing approximately a right angle. Posterior margin of brachial valve narrowly 
rounded. Surface marked by strong and irregular concentric undulations and 
covered by very fine concentric, wavy lines. 
Valves of unequal depth, the brachial valve having a slightly greater depth 
than the pedicle valve. Valves deepest at the posterior but becoming shallower 
toward the front. Lateral slopes moderately steep at the posterior and median 
part of both valves but merging into the flattened anterior part. 
Measurements in mm.—Holotype, length 7.5, width 2.8, thickness 1.5. 
Type.—Holotype: 109295. 
Horizon and locality —Effna formation in Virginia: 1 mile east of Tilson 
Mill, 16 miles northeast of Marion, Nebo (T.V.A. 223-NW) Quadrangle. 
Discussion.—This interesting little species suggests Lingula clathrata Win- 
chell and Schuchert from the Decorah shale of Minnesota, but the Virginia shell 
differs in its larger size and more elongate form, and in not possessing the pecu- 
liar ornamentation of the Minnesota species which is referred to as Westonia. 
LINGULELLA TENUITESTA Cooper, new species 
Plate 1, F, figures 19, 20 
Shell small, dark brown in color, oval in outline, biconvex, with thin shell. 
Posterolateral margins nearly straight ; lateral margins convex ; widest at middle; 
anterior margin gently convex. Beak of pedicle valve pointed, forming an angle 
of 80°. Ornamentation consisting of very fine, closely crowded, elevated con- 
centric lines, often irregular and discontinuous. 
Pedicle valve gently convex in anterior and lateral profiles. Lateral profile 
uneven with the greatest elevation slightly posterior to the middle; anterior 
profile broadly and somewhat depressed convex. Beak bluntly pointed ; umbonal 
region somewhat narrowly swollen. Posterolateral slopes moderately steep, 
median slopes gentler than the posterolateral ones. Anterior slope long and 
gentle. 
Brachial valve with anterior and lateral profiles depressed convex. Lateral 
slopes narrow and moderately steep; anterior slope long and gentle. Maximum 
convexity of valve at about the middle which is somewhat flattened. 
Measurements in mm.— 
Length Width Thickness 
Holotype, (pedicle valve): ais ois ssc a ssinys de ee 8.1 6.3 ? 
Paratype (pedicle valve 109299c) ............. 9.8 6.6 ty 
Ch (brachial valve 109299b) ........... 6.2+ 5.5 ? 
Types.—Holotype: 109299a; figured paratype: 109299b; unfigured paratypes: 
109299c, 109300a-}. 
