PART... £ CHAZYAN AND RELATED BRACHIOPODS—COOPER 771 
Types.—Holotype: 117470a; figured paratypes: 117470d,e; unfigured para- 
types: 117470b,c,f. 
Horizon and locality.—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion—This species is suggestive of B. immatura and B. matutina in its 
small size and apparently immature characters. It differs from both of them, 
however, in the form and outline of the pedicle valve. The Quebec and Virginia 
species are strongly swollen medially and have somewhat depressed sides, par- 
ticularly B. matutina. The species from the Effna limestone is somewhat nasute 
and is much less transverse than the B. siphonata. 
Bimuria siphonata shows immature characters in its small size, lack of thicken- 
ing of the adductor muscle field, and the presence of a pedicle siphon. The 
Pratt Ferry limestone to date has not yielded a normal adult of Bimuria, but 
hundreds of valves of about the same size of B. siphonata have been obtained 
from it. These facts suggest that the species may actually be an adult which 
retains some of its juvenile characters. 
BIMURIA SUPERBA Ulrich and Cooper 
Plate 184, C, figure 5; plate 210, B, figure 5; plate 210, F, figures 15, 16; 
plate 210, I, figures 33, 34; plate 211, B, figures 14-25 
Bimuria superba Utricn and Cooper, Journ. Paleont., vol. 16, No. 5, p. 623, pl. 90, figs. 13-18, 
1942. 
Christiania cf. C. lamellosa Butts (not Bassler), Virginia Geol. Surv. Bull. 52, p. 42, pl. 73, 
figs. 34-36, 1942. 
Shell large, subcircular in outline, varying from slightly wider than long, to 
slightly longer than wide; cardinal extremities varying from a right angle to a 
slightly obtuse angle. Lateral margins nearly straight to gently convex; anterior 
margin broadly rounded. Profile concavo-convex with the pedicle valve strongly 
convex and its beak overhanging the brachial interarea. Surface generally nearly 
completely covered by fine, wrinkled, crowded, concentric lamellae. 
Pedicle valve strongly convex in lateral profile and with the greatest con- 
vexity at about the middle. Umbo strongly swollen. Anterior profile strongly 
convex. Lateral and anterior slopes abrupt and steep. Posterolateral slopes 
steep and slightly concave. Interarea strongly concave, anacline in position. 
Brachial valve deeply concave with the greatest concavity at about the median 
region. Interarea strongly hypercline. Umbonal and median regions deeply 
concave. 
Interiors as described for the genus. 
Measurements in mm.—Holotype, length 19.7, brachial length 14.8, width 
22.2, hinge width 18.4, thickness 5.4, height 8.5. 
Types.—Holotype: 108200a; figured paratypes: 108200b,c,f, 108201; un- 
figured paratypes: 108200d,e,g-j; figured hypotypes: 110964a, 110981, 117471, 
117472a. 
Horizon and locality—Arline formation in Tennessee: On both sides of old 
