PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 279 
line; another brachial valve (paratype 116804a) is 19.7 long, 20.0 wide; the 
apex is 3 anterior to the posterior margin. 
Types—Holotype: 109640; figured paratypes: 97547a-c, 116803a, 1168042; 
unfigured paratype: 116803b. 
Horizon and locality—Oranda formation in Virginia: Along the railroad 4 
to 4 mile east of Strasburg Junction; on U. S. Highway 11, 1 and 2 miles south- 
west of Strasburg; Virginia Highway 55, 0.4 mile west of U. S. Highway 11 on 
the north edge of Strasburg, Strasburg (15’) Quadrangle. 4 mile below the 
dam on the Shenandoah River, 1 to 14 miles north of Edinburg, Edinburg (15’) 
Quadrangle. 
Oranda formation in Pennsylvania: 1 mile northwest of Guilford Springs, 
Chambersburg (15’) Quadrangle. 
Discussion.—This species is characterized by its large size and the short, ellip- 
tical pedicle groove of the pedicle valve. It is unlike any other species yet known 
in the Appalachian Valley, differing from S. subconica in larger size and circular 
outline. 
Some specimens show obscure details of the interior, but the valves are usually 
so badly exfoliated that considerable uncertainty attends their interpretation. 
Two specimens show the position of the pedicle groove on the interior but its 
shape is not determinable. 
SCHIZOTRETA PANNEA (Willard) 
Acrosaccus panneus WitvLarD, Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, No. 6, p. 250, 
pi 3. HE..3, 1028. 
This is a large species based on a single pedicle valve which is distinguished 
from S. shulert (Willard) by its much wider apical angle. A single specimen 
(109657) in the National Museum collections is referred somewhat doubtfully to 
this species. 
Type.—Holotype: M.C.Z. 8592. 
Horizon and locality.—Effna formation in Virginia: McNutt Quarry, 12 miles 
southwest of Bland, near Sharon Springs, Burkes Garden (15’) Quadrangle. 
SCHIZOTRETA PAPILLIFORMIS Ruedemann 
Schizotreta papilliformis RUEDEMANN, New York State Mus., Bull. 42, p. 570, pl. 1, figs. 3-5, 
1901. 
Horizon and locality—Normanskill formation in New York: At Mount 
Merino, near Hudson. 
SCHIZOTRETA POSTEROCONVEXA Cooper, new species 
Plate 28, B, figures 5, 6 
Specimen represented by two pedicle valves only ; subcircular to slightly longi- 
tudinally elliptical in outline; conical in profile with the apex located at about 
the center. Posterior slope long and fairly strongly convex; anterior slope long, 
