PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 251 
CONOTRETA DEPRESSA Cooper, new species 
Plate 17, C, figures 29-57 
Shell large for the genus, elliptical in outline, pedicle valve depressed, conical, 
with the posterior surface flattened; valves marked by fine concentric lines. 
Color shiny light brown often with alternating bands of light and darker color. 
Pedicle valve depressed, circular in outline except for the posterior margin ; 
lateral profile gently convex; anterior slope long and swollen; posterior slope 
short, flat; foramen small, apical; apical angle varying from about go° to 110°. 
Anterior and lateral profiles showing strong, convex sides. Pseudointerarea 
wide, measuring somewhat more than half the width; intertrough not visible or 
showing a slight wave of the posterior margin or a faint longitudinal color band. 
Brachial valve wider than long, fairly strongly convex in lateral profile, with 
the greatest convexity in the umbonal region ; beak marginal, small and incurved ; 
anterior quarter flattened ; posterolateral slopes gently concave. Anterior profile 
broadly convex with the median region flattened slightly and with moderately 
long and gentle lateral slopes. 
Pedicle interior with a small callosity excavated anteriorly; pedicle chamber 
moderately deep and narrow; pallial trunks deeply impressed at the rear, the 
outside one the deepest and bifurcating near its point of origin; outside trunk 
also bifurcating near the anterior edge of the callosity. Muscle scars well de- 
veloped and located on the inner curved surface just outside the flattened inner 
surface of the palintrope. 
Brachial interior with a long median septum extending for about two-thirds 
the valve length; septum rising to a point about one-third the length from the 
posterior margin; posterior triangular depression short, small, inconspicuous ; 
propareas attenuated. Two sets of muscles well developed, the larger ones lo- 
cated just anterior to and outside the propareas, the smaller set located on each 
side of the median septum opposite its highest point. 
Measurements in mm.— 
Length Width Thickness 
Holotype) (Cpedicle: valve) wes «aid snd nia tin ospepehageiaeis 5.4 6.5 2.6 
Paratype (brachial valve 116815c) ........... 4.9 5.9 ca. 0.5 
Types.—Holotype: 116815e; figured paratypes: 116815a-d,f-m; unfigured 
paratypes: 116815n; figured specimen: 117967. 
Horizon and locality.—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—This is a large species approaching C. magna and C. gigantea, 
but the pedicle valve forms a much wider cone and the shell never attains the 
great thickness of the other two species. 
CONOTRETA GIGANTEA Cooper, new species 
Plate 16, E, figures 18-23; plate 17, D, figure 58; plate 17, EF, figures 59, 60 
Shell exceptionally large for the genus, circular in outline, forming a slightly 
curved and elongate cone. Base of cone slightly wider than long. Apical angle 
