300 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
ORTHAMBONITES BUTTSI (Schuchert and Cooper) 
Plate 36, D, figures 21-31 
Orthis crasicosta Butts (not Pander 1830), Geol. Surv. Alabama, Special Rep. 14, p. 114, 
116, pl. 26, figs. 14-15, 1926. 
Orthis buttsi ScHUCHERT and Cooper, Mem. Peabody Mus. Nat Hist., vol. 4, pt. 1, p. 75, 
footnote, 1932. 
Shell of medium size, wider than long and with the hinge forming the great- 
est width or slightly narrower. Lateral margins gently curved and sloping medi- 
ally; anterior margin broadly curved. Anterior commissure very gently sulcate. 
Costae direct, strong, subangular, numbering 19 on the pedicle valve. Entire sur- 
face covered by fine radial threads. 
Pedicle valve moderately convex in both profiles. Greatest convexity located 
in the posterior half; the median costa a little elevated and forming the center of 
a low fold that extends from the beak to the anterior margin. Flanks flattened ; 
slopes to lateral margins gentle. Interarea curved, moderately apsacline; beak 
incurved. Interior with deep but short delthyrial cavity; nearly obsolete dental 
plates, short median thickening anterior to muscle area. 
Brachial valve slightly convex in lateral profile, nearly flat and slightly de- 
pressed in the middle in anterior profile. Sulcus shallow and narrow, occupied 
by 2 costae, occupying about one-quarter the width at the anterior margin. 
Interarea short; beak inconspicuous. Flanks bounding sulcus slightly swollen 
with concave slopes to the cardinal extremities. Interior with low median ridge 
not meeting the center, moderately stout brachiophores supported by shell de- 
posited in notothyrial cavity. Cardinal process a simple ridge. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Flolotypie Sends. os D0 eee ac ok 11.4 10.2 rey 12.4 5.4 
Hypotype (109808a) ....... 12.0 10.4 14.6 13.5 5.2 
Types.—Holotype: 71497 ; figured hypotypes: 10g808a, 116870a-c ; unfigured 
hypotypes: 109g808b,c, 116870d-f. 
Horizon and locality.—Little Oak formation in Alabama: 4 mile north of Pel- 
ham ; on west side of U. S. Highway 31, 4 mile N. 10° E. of Pelham Station, 
SW4iSW35 sec. 13, T. 20 S., R. 3 W., all on Bessemer Iron District (15’) Quad- 
rangle; cut on L. and N. RR., $ mile northwest of Mosteller, Columbiana (15’) 
Quadrangle: intersection Bailey Gap road with main road, SWiSW3 sec. 13, T. 
19 S., R. 2 W., 1 miles northeast of Newhope Church, Vandiver (15’) Quad- 
rangle. 
Discussion—The closest species to this one is O. angulatus from the Arline 
formation at Riverdale, near Knoxville, Tenn. This species differs from O. buttsi 
in its larger size, more numerous angular costae and stronger fold on the pedicle 
valve. 
