PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 281 
valve preserves its shape fairly well, but details of the pedicle opening and slit are 
absent. The brachial valve which is here selected as lectotype shows the outline, 
profile, and details of the ornamentation. Schizotreta shuleri is similar to S. 
posteroconvexa but does not have as strongly a convex posterior slope. The 
species is also suggestive of S. corrugata but is not so coarsely ornamented. 
SCHIZOTRETA SUBCONICA Cooper, new species 
Plate 20, C, figures 6-10; plate 21, E, figures 23-32 
Shell of medium size for the genus, longitudinally elliptical in outline; surface 
marked by fine, even slightly elevated concentric lines. 
Pedicle valve forming an eccentric cone with the apex about one-sixth the 
length anterior to the posterior margin. Posterior slope flat, short and steep, 
slightly less than 2 mm. long in the holotype ; anterior slope long and flat, measur- 
ing about 5 mm. in the holotype. Lateral slopes steep, forming an angle of about 
115°. Pedicle slit small, about 1 mm. long, narrow; foramen small. 
Brachial valve longer than wide, gently convex in lateral profile, with the 
greatest convexity in the umbonal region; beak submarginal, smooth; lateral 
slopes gentle. 
Measurements in mm.— 
Length Width Thickness 
Eloletype: beeetients.. O72). 0 leoargaiabeartee, 6.2 5.6 ? 
Paratype (pedicle valve 109646b) ............. 7.8 Th 0.90 
‘i mee Ms (EOOGAGA): cra. abaisinins ole 6.8 6.3 1.5 
He (brachial valve 1096461) |... 02505 0s 8.6 7.6 aS 
Types.—Holotype: 116805a; figured paratypes: 109646b,d,e,f,g, 116805b-e ; 
unfigured paratypes: 109646a,c,h-j. 
Horizon and locality—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—This species is characterized by its fairly high conical profile, 
elliptical form, and the fine, uniformly even character of the ornamentation. In 
the latter respect it suggests S. posteroconvexa but differs in having a flat pos- 
terior slope and smaller pedicle slit. This species is more finely ornamented than 
S. shuleri and is quite unlike S. willardi in profile, outline, and ornamentation. 
SCHIZOTRETA WILLARDI Cooper, new species 
Plate 11, C, figure 5; plate 19, A, figures 1-6; plate 21, F, figures 33-41 
Shell fairly large for the genus, depressed conical in profile, circular in outline ; 
brachial valve gently concave ; surface marked by fairly even, elevated concentric 
lines, often crowded in the posterolateral region. 
Pedicle valve with the apex slightly posterior to the center; posterior slope 
long and gently convex; anterior slope long and gently concave, the greatest 
concavity located at the umbo just anterior to the beak; lateral slopes long and 
gently concave. Pedicle slit short and fairly wide, tear-shaped in outline with 
the acute apex anterior in position; floor of slit marked by a deep groove; fora- 
