544 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Leeds, Leeds (15’) Quadrangle; Ragland Cement Company Quarry, 3 miles 
southeast of Ragland, St. Clair County. 
Ward Cove formation in Virginia: At Rye Cove, Clinchport (T.V.A. 
188-NW) Quadrangle. 
Effna formation in Virginia: At McNutt Quarry 12 miles southwest of Bland, 
Burkes Garden (15’) Quadrangle. 
Discussion—O-xoplecia gibbosa as described herein is a variable species. The 
variation may be due in part to preservation because some of the specimens are 
loose silicified shells while others are enclosed in a limestone matrix. The costae 
on the flanks vary from strong to almost obsolete ; consequently, some specimens 
have a quite different appearance from others and the species is difficult to iden- 
tify and distinguish from nearly related forms. Generally O. gibbosa is fairly 
round in outline but has deep valves. It resembles O. holstonensis in outline but 
is more strongly and less numerously costellated than that species. It is also a 
more robust species than O. parva, a rare shell from the Benbolt formation. 
Oxoplecia gibbosa differs from O. eidsonensis in having less numerous and 
strong costellae and a rounder form. It differs from O. planiventra in its much 
more robust and deep pedicle valve. 
OXOPLECIA GLOBULARIS Cooper, new species 
Plate 106, B, figures 6-11 
Shell of about medium size for the genus, subcircular in outline with sides 
broadly rounded and anterior margin nearly straight. Strongly inequivalve, the 
brachial valve having the greater depth. Strongly uniplicate. Sulcus with 3 to 
5 costellae; fold with 4 to 6 costellae. Flanks with about 9 costellae. Costellae 
broad, separated by interspaces about equal to the costellae in width. Fila closely 
crowded, 7 or 8 to the millimeter. 
Pedicle valve moderately convex in lateral profile and broadly but gently con- 
vex in anterior profile. Sulcus originating about 3 mm. anterior to the beak, 
widening to the front margin where it occupies about two-thirds the width; 
pedicle tongue long and subtruncate anteriorly ; flanks bounding sulcus narrow, 
convex, and with steep slopes. Beak and interarea short, strongly curved. 
Brachial valve strongly convex in lateral profile with the most convex part in 
the umbonal region; anterior profile strongly arched and with precipitous sides. 
Umbonal region smooth ; fold moderately elevated above the flanks ; flanks some- 
what inflated. 
Measurements in mm.—Holotype, length 13.9, brachial length 13.4, width 15.7, 
hinge width 6.8, thickness 12.2. 
Types.—Holotype: 117098b; figured paratype: 117098c; unfigured paratype: 
117098. 
Horizon and locality—Base of Martinsburg formation (part with Brogniar- 
tella=Salona) in Virginia: On Virginia County Highway 617=910, 0.15 mile 
north of Green Mount Church, Broadway (15’) Quadrangle. 
Discussion—This species is characterized by its round outline and the great 
