998 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
DIORTHELASMA PARVUM Cooper, new species 
Plate 146, B, figures 5-23 
Small, transversely elliptical in outline with rounded sides but a nearly straight 
anterior margin. Hinge wide, but not equal to the greatest shell width which is 
at the middle. Valves strongly unequal, the pedicle valve having the greater 
depth. Anterior commissure sulcate; surface costellate, costellae separated by 
spaces wider than the width of the costellae, about 6 costellae in I mm. at the 
front margin. 
Pedicle valve moderately convex in the anterior half but strongly convex in 
the umbonal region. Interarea apsacline; beak low, incurved. Anterior profile 
broadly convex, most convex in the median region and with long lateral slopes. 
Umbonal and median regions swollen. 
Brachial valve very gently convex in lateral profile, broadly and gently con- 
vex in anterior profile but deeply concave in the middle. Beak not prominent ; 
sulcus originating at beak, wide and deep. Flanks gently swollen. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
EPOIGEY DE’ vec et eee es e's 2.1 1.9 eH! 2.2 1.2 
Paratype (117322c)..... 22 BT 3.4 2.9 1.4 
Types—Holotype: 117322a; figured paratypes: 117322b-h. 
Horizon and locality—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—The small size, transverse outline and pionodemoid interior iden- 
tify this species, but no other species of the genus is yet known to which this 
one can be compared. 
Genus FASCIFERA Ulrich and Cooper, 1942 
Fascifera ULrtcu and Cooper, Journ. Paleont., vol. 16, No. 5, p. 620, 1942. 
Shell usually small, subcircular in outline, nearly planoconvex to unequally 
biconvex, the pedicle valve always having the greater depth. Hinge narrower 
than the greatest shell width; cardinal extremities obtuse. Anterior commissure 
sulcate to rectimarginate. Exterior costellate to fascicostellate. 
Interior like Pionodema with flaring dental plates in the pedicle valve and a 
small plate at the apex of the delthyrium. Median ridge of pedicle valve only 
slightly developed. Brachial valve with brachiophores long and thin with dis- 
crete supporting plates converging slightly and uniting with the floor of the valve 
on each side of the median ridge. Cardinal process long and thin with a nar- 
row lobate crenulated myophore. Shell substance endopunctate. 
Genotype.—Fascifera subcarinata Ulrich and Cooper, Journ. Paleont., vol. 16, 
No. 5, p. 620, pl. go, figs. 1-5, 1942. 
Discussion.—The general dalmanelloid outline and profile combined with the 
internal features of Pionodema distinguish the species of this genus from other 
punctate shells. Most species show a fair degree of fasciculation of the costellae, 
