504 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
to form a narrow but deep cruralium occupied by a slender, linear, ridgelike 
cardinal process. Median ridge reaching the middle of the valve. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
EATHGEVPIC sine nic's Clues teieeuas ose ce 17.8 15.8 19.5 12.6 9.6 
Paratype (1100074) «cere s. ceoee 18.0 15.6 19.5 15.4? 8.9 
“ CTIGOOZE HOI i. FE 15.8? 14.2 17.8 11.6 7.0 
Mf (pedicle valve 116906a). 16.9 4 18.5 12.7 4.5 
Types.—Holotype: 111787; figured paratypes: 116905, 116906a, 116907a,d; 
unfigured paratypes: 116906b-d, 116907b,c,e-i. 
Horizon and locality Shippensburg formation (Pinesburg member) in Penn- 
sylvania on the Chambersburg (15’) Quadrangle: 13 miles west of Kauffman; 
0 to 50 feet above the Lowville in a field just north of the railroad cut 2 miles 
southwest of Marion Station. 
Same formation in Maryland: In the shaly cobbly beds between the lower 
Echinosphaerites zone and the first Nidulites zone on U. S. Highway 40, just 
west of the bridge over Conococheague Creek, 7 miles west of Hagerstown, 
Williamsport (15’) Quadrangle. 
Edinburg formation (Cyrtonotella zone) in Virginia: 3 mile north-northeast 
of Glendale School, Winchester (15’) Quadrangle; 1.5 miles N. 61° E. of Edin- 
burg, Edinburg (15’) Quadrangle; 500 feet southeast of U. S. Highway 11, 
1 mile northeast of Toms Brook, Strasburg (15’) Quadrangle. 
Discussion.—This species is the largest member of the genus so far known. It 
is abundant in the lower part of the Edinburg and Shippensburg formations. It 
differs from the other two known species in size, in having a nearly rectimargi- 
nate anterior commissure, and in having somewhat stronger costellae. 
SCAPHORTHIS PERPLEXA Cooper, new species 
Plate 55, B, figures 12-26 
Dalmanella sp. Burrs, Virginia Geol. Surv. Bull. 52, pt. 2, p. 42, pl. 73, figs. 24, 25, 1942. 
Corineorthis sp. Cooper and Cooper, Bull. Geol. Soc. Amer., vol. 57, p. 113, pl. 3, fig. 14, 1946. 
Shell small, transversely subelliptical in outline. Hinge narrower than the 
maximum shell width which is located at the middle. Cardinal extremities ob- 
tuse. Sides narrowly rounded. Anterior margin broadly rounded. Surface cos- 
tellate, costellae appearing in 4 generations, about 4 costellae in I mm. at the front 
of a valve 74 mm. long. 
Pedicle valve evenly convex in lateral profile with the maximum convexity at 
about the middle. Anterior profile narrowly convex medially and with steep 
slopes. Beak incurved and extending posterior to the posterior margin. Umbo 
narrowly convex and merging with a longitudinal median elevation or fold, the 
narrow convexity of which decreases anteriorly. Flanks slightly concave and 
steep sided. Interarea moderately long, curved, nearly orthocline. 
Brachial valve strongly convex in lateral profile with the maximum convexity 
in the posterior half. Anterior profile a broad, slightly elevated arch depressed 
