570 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Discussion—This is the largest known species of Camerella, exceeding even 
C. volborthi in size. It is also characterized by having numerous costae on the 
fold and in the sulcus. These vary from 5 to 6 in the sulcus and 6 to 7 on the 
fold. The species is thus unlike any other described form. 
CAMERELLA IMMATURA Cooper, new species 
Plate 110, A, figures 1-5 
Shell small, subpentagonal in outline, slightly wider than long; apical angle 
slightly greater than a right angle; sides narrowly rounded ; anterior somewhat 
produced and truncated. Anterior commissure narrowly uniplicate; surface 
smooth except for 2 costae on the flanks. 
Pedicle valve gently convex in lateral profile and with the maximum convexity 
at about the middle; anterior profile broadly and gently convex; median region 
inflated; sulcus originating in the anterior third and anterior to the inflated 
region; sulcus smooth, concave; tongue moderately long and narrow. Flanks 
gently convex and with moderate slopes. 
Brachial valve deeper than the pedicle valve and gently convex in lateral pro- 
file with the umbo swollen. Anterior profile broadly and gently convex but with 
precipitous sides. Median region and flanks inflated. Fold short, narrow, slightly 
elevated, marked by a slight depression medianly. 
Measurements in mm.—Holotype, length 5.5, brachial length 5.6, width 6.1, 
hinge width 1.7?, thickness 4.0. 
Type.—Holotype: 117137. 
Horizon and locality—Chatham Hill formation in Virginia: On Grayson 
Farm, 4 to 5 miles southeast of Bland, Bland County. 
Discussion.—This species is characterized by its nude exterior and the lack of 
costae in the sulcus and on the fold. No comparable species is available. 
CAMERELLA INDEFINITA Cooper, new species 
Plate 112, D, figures 16-22 
Shell moderately large for the genus, slightly longer than wide with the great- 
est width slightly anterior to the middle. Beak forming an acute angle of about 
80°; sides narrowly rounded and anterior margin gently rounded. Surface 
marked by 19 low, rounded costae separated by spaces narrower than the costae. 
Six costae occupy the sulcus, and 7 occur on the fold. 
Pedicle valve gently convex in lateral profile with the most convex part slightly 
posterior to the middle. Sulcus poorly defined, originating at about the middle 
and occupying about two-thirds the valve width at the anterior. Flanks narrow, 
slightly convex but with steep slopes to the margins. 
Brachial valve moderately convex with the greatest convexity slightly posterior 
to the middle. Umbonal region moderately convex, fold poorly defined, wide, 
originating slightly posterior to the middle. Flanks convex and with steep slopes. 
Measurements in mm.—Holotype, length 13.7, brachial length 12.5, width 12.8, 
hinge width 3.2, thickness 8.9. 
