366 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Pelham, and 2 miles north of Pelham, Bessemer Iron District (15’) Quadrangle. 
Intersection of the Bailey Gap road with the main Cahaba Valley road, SW4SW4 
sec. 13, T. 19 S., R. 2 W., 1} miles northeast of Newhope Church, Vandiver 
(15’) Quadrangle. 
Basal Athens formation in Tennessee: Along the road 24 miles south-south- 
east of Riceville, Calhoun (T.V.A. 125-SW) Quadrangle ; 600 feet S. 40° E. of 
the railroad and highway crossing I mile northeast of the courthouse in Athens, 
Athens (T.V.A. 125-NE) Quadrangle. 
Arline formation in Tennessee: Knoxville; southeast edge of Friendsville, 
Concord (T.V.A. 138-SW) Quadrangle. 
Arline formation in Virginia: Porterfield Quarry, 5 miles east of Saltville, 
Maccrady (T.V.A. 218-NW) Quadrangle. 
Discussion—This is a small variable species but the majority of specimens 
are wider than long with moderately convex valves, a pedicle valve with con- 
siderable fullness longitudinally in the median area and a fairly wide and deep 
sulcus in the brachial valve. It is not quite like any other species described but 
approaches G. sulcata from which it differs in its more rectangular outline, 
smaller size, less elongated palintrope of the pedicle valve, and shallower brachial 
valve. 
GLYPTORTHIS COSTELLATA Cooper, new species 
Plate 43, C, figure 8; plate 44, D, figures 20-37 
Glyptorthis cf. bellarugosa SCHUCHERT and Cooper, Mem. Peabody Mus. Nat. Hist., vol. 4, 
pt. I, pl. 6, fig. 12, 1932. 
Shell of about medium size for the genus, subquadrate in outline, and with the 
width slightly greater than the length. Cardinal extremities forming a right 
angle. Lateral margin straight to gently curved; anterolateral margins rounded ; 
anterior margin slightly rounded to straight. Valves nearly equal in convexity. 
Anterior commissure rectimarginate to slightly sulcate. Surface covered by about 
47 thin, angular to narrowly rounded costellae, of which about 9 or 10 occupy 5 
mm. at the front. Imbrications distant at the posterior but becoming crowded 
toward the front of the valves, 2 to 3 in I mm. 
Pedicle valve only moderately convex in both profiles, having the greater con- 
vexity a little posterior to the middle. Midregion inflated ; lateral slopes moder- 
ately steep; anterior slope gentle. Interarea moderately long; slightly curved; 
apsacline. 
Brachial valve gently and evenly convex with the greatest convexity at about 
the middle. Sulcus prominent, widening from the umbo to occupy more than 
half the width at the front margin where as many as 13 costellae may occupy it. 
Flanks bounding sulcus moderately swollen. Slopes to cardinal extremities gently 
concave and moderately steep. Interarea moderately long; slightly apsacline. 
Beak slightly incurved. 
