934 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Types—Holotype: 117714a; figured paratypes: 117708, 117712, 117713, 
117714b-d, 123278; unfigured paratypes: 117709, 117710a-c, 117711a,b. 
Horizon and locahty—Bromide formation (Pooleville member-O-roplecia 
gouldi zone and 20 feet above O. gouldi zone) in Carter County, Oklahoma: At 
Rock Crossing of Hickory Creek, about center sec. 35, T. 5 S., R. 1 E., Criner 
Hills; NW34 sec. 26, T. 5 S., R. 1 E., Criner Hills. 
Discussion.—This species is characterized by the general uniformity in size of 
the costellae, the elongate muscle area, the flat umbonal region, and the short 
median sulcus of the brachial valve. 
This species does not resemble any known Strophomena from the Appa- 
lachians but has its nearest relative in S. inconsueta C. L. Fenton. It is a wider 
shell relatively than S. inconsueta and differs further in the possession of a 
more elongate muscle area. 
STROPHOMENA CRINERENSIS Cooper, new species 
Plate 173, E, figures 25-30; plate 260, B, figures 11-25 
Shell small for the genus, outline varying from semicircular to semielliptical. 
Hinge generally forming the widest part, cardinal extremities acutely angular, 
tending to alate. Surface marked by costellae of unequal size, the larger costellae 
separated by 3 or 4 much finer ones. All costellae crossed by prominent fila that 
give a cancellated appearance to the surface. At the front margin very fine cos- 
tellae have increased sufficiently in size to reduce the inequality of the costellae. 
Pedicle valve gently to moderately concave with the maximum concavity lo- 
cated at about the center. Umbonal region slightly and narrowly swollen; pos- 
terior half gently concave to nearly flat. Cardinal extremities flattened to slightly 
concave and deflected toward the brachial valve, a slight oblique fold forming 
the divide between the deflected cardinal extremity and the concave portions. 
Anterior geniculation not great. Interarea strongly apsacline; moderately long. 
Pseudodeltidium narrow and strongly arched. Foramen minute. 
Brachial valve moderately to strongly convex in lateral profile, strongly convex 
in anterior profile. Greatest convexity of lateral profile at the middle or slightly 
anterior to the middle. Umbonal region gently concave, nearly flat to moderately 
deeply sulcate. Sulcus extending for about one-third the length. Oblique sulci 
just anterior to cardinal extremities deep. Lateral and anterior slopes moderately 
steep. 
Interior: Muscle area subelliptical, slightly wider than long, its posterior half 
surrounded by delicate extensions from the teeth. Median ridge low, scarcely 
extending anterior to the front margin of the muscle area. Subperipheral rim 
corrugated, not greatly thickened. Interior of brachial valve with cardinal process 
well elevated, the brachiophores and their supporting tissue delicate. Muscula- 
ture unknown. 
