60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
specimen S. rostrata. The latter has a considerably narrower and 
more elevated beak than the one from Oregon. Nevertheless, the 
specimen figured by Tschernyschew (1902, pl. 20, fig. 17), which 
comes from the “Schwagerina’ zone, is very close to the Oregon 
species. This Russian specimen has not the strongly elevated beak 
of Kutorga’s type and may ultimately prove to be distinct. The mat- 
ter, however, cannot be settled on the single Oregon specimen, which 
is slightly crushed. 
Type.—Hypotype, U.S.N.M. 125396. 
Localities —633?, 638; L8; Pio, P11, P12; S41, S43, S46, S56, 
S103, S106; U.O. 2201-1, 2202-4, 2204-1, 2204-3. 
Superfamily RostrosprracEA Schuchert and LeVene, 1929 
Family ATHYRIDAE Davidson, 1884 
CLEIOTHYRIDINA ATTENUATA Cooper, new species 
Plate 11D, figures 21-27 
Small, suboval in outline, length and width nearly equal; maximum 
width at middle; posterolateral margins nearly straight and forming 
an angle of go° at the beak; sides strongly rounded; anterior margin 
strongly rounded; anterior commissure rectimarginate. Surface de- 
tails indistinct but marked by closely spaced concentric lamellae bear- 
ing spines. 
Pedicle valve gently convex in lateral profile, strongly convex in 
anterior profile; beak and umbo narrow; umbo narrowly swollen; 
median region swollen; flanks flattened but steep. Beak incurved and 
extending posterior to the margin of the brachial valve. 
Brachial valve shallower than the pedicle valve, gently convex in 
lateral profile but strongly convex in anterior profile; umbonal region 
somewhat narrowed; median region strongly swollen and forming 
the most convex part. All slopes to the margins steep. 
Measurements in mm.—Holotype, length 12.3, brachial length 11.2, 
maximum width 11.9, thickness 7.2. 
Types.—Holotype, U.S.N.M. 125394a; unfigured paratype, U.S. 
N.M. 125394b. 
Localities —S45, S87; U.O. 2205-5. 
Discussion.—This species is characterized by small size and small 
attenuate beak. This genus is at present not described from the 
American Permian, although it occurs in the Wolfcamp of west and 
north-central Texas. The Wolfcamp species is a small one but does 
