672 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Measurements in mm.—Holotype, length 4.5, brachial length 4.1, width 4.5, 
thickness 2.5. 
Types.—Holotype: 111377a; unfigured paratypes: 111377b-f. 
Horizon and locality—Lebanon formation in Tennessee: At Shelbyville, Bed- 
ford County ; Columbia, Maury County; 3 miles east of Murfreesboro; on U. S. 
Highway 70S, # mile east of Readyville, Cannon County. 
Moccasin formation in Tennessee: 3 mile east of Fleanor Mill, Powell Station 
(T.V.A. 137-SE) Quadrangle. 
Camp Nelson formation in Kentucky: At High Bridge, Harrodsburg (30’) 
Quadrangle. 
Barnhart formation in Missouri: # mile north of Riverside, Jefferson County. 
ZYGOSPIRA ? MATUTINA Cooper, new species 
Plate 141, B, figures 13-17 
Shell small, subrhomboidal in outline; greatest width at the middle where 
prominent shoulders are formed by the union of the posterolateral and antero- 
lateral margins; apical angle about 80°. Anterior commissure strongly and 
broadly sulcate ; surface costellate, costellae subdued and delicate, extending from 
beak to anterior margin. 
Pedicle valve gently convex in lateral profile; narrowly convex in the median 
region in anterior profile and with long, flat, only moderately steep slopes. Beak 
long; umbo narrowly convex; median region narrowly convex; anterior region 
somewhat narrowly folded, and fold moderately elevated and with moderately 
steep slopes. 
Brachial valve gently convex in lateral profile, just perceptibly convex in an- 
terior profile and with a slight depression in the median region. Umbo narrowly 
sulcate, the sulcus deepening and widening to the anterior margin where it occu- 
pies more than half the width. Flanks gently convex. Interior unknown. 
Measurements in mm.—Holotype, length 2.4, brachial length 2.2, width 2.3, 
thickness 0.9. 
Type.—Holotype: 117261. 
Horizon and locality.—Little Oak formation in Alabama: In the hill east of 
Leeds, Leeds (15’) Quadrangle. 
Discussion—The interior of this interesting little shell is unknown; it was 
placed in Zygospira because its external form and folding are the same as in 
that genus and its costellae cover the entire surface. In this latter respect it is 
unlike Protozyga. The fine and indistinct costellae differentiate this species from 
any known Zygospira. 
ZYGOSPIRA MEDIOCOSTELLATA Cooper, new species 
Plate 143, D, figures 13-18 
Sheil of about usual size for the genus, slightly longer than wide; longitudi- 
nally oval in outline; sides rounded; beak forming an angle of 90°. Anterior 
margin emarginate. Maximum width slightly anterior to the middle. Anterior 
