932 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Pedicle valve very gently concave in lateral profile, with the maximum con- 
cavity near the valve middle; umbo narrowly and gently swollen to form a dis- 
tinct but low fold extending anteriorly for a distance of about 8 mm. Median 
region very gently concave; lateral and anterior regions gently and broadly bent 
toward the pedicle valve. Interarea short, pseudodeltidium moderately convex; 
interior with elongate to subcircular muscle field ; rim surrounding muscles mod- 
erately thickened. Old specimens with a moderately thick subperipheral rim. 
Brachial valve fairly evenly but gently convex in lateral profile; anterior pro- 
file broadly convex ; umbo concave, the concavity continued anteriorly as a short, 
narrow sulcus for about 8 mm. Median region gently swollen; lateral areas with 
long and gentle slopes. Cardinalia delicate for such a large shell; cardinal process 
small; median ridge low and short; sockets formed by narrow cuplike plates. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
Holotype (pedicle valve) ............ 33.5 ? 43.3 51.6? ? 
Paratype (brachial valve 117707b).... ? 27.0 35.7 389.2 cw Pawe 
- (ee ft PARSE Vs stirs ? 35.0 46.8 46.8 ? 
Types.—Holotype: 1177074; figured paratypes: 117707b,c, 123283; unfigured 
paratypes: 117707d-f. 
Horizon and locality—Oranda formation in Broadway (15’) Quadrangle in 
Virginia: 0.6 mile west of Linville Station; on Virginia Highway 777 just west 
of its junction with Highway 617, 4 mile north of Green Mount Church. 
Martinsburg formation (part with Brongniartella=Salona) in Virginia: On 
Virginia Highway 617=910, 0.15 mile north of Green Mount Church, Broadway 
(15’) Quadrangle. 
Discussion—This species is characterized by its large size and strongly differ- 
entiated ornamentation. It has about the size of large specimens of S. auburnen- 
sis but is readily distinguished from that species by the concavity of the pedicle 
valve and the low convexity of the brachial valve. 
STROPHOMENA BILLINGSI Winchell and Schuchert 
Strophomena recta Bitttncs (not Conrad), Geol. Surv. Canada, Paleozoic fossils, vol. 1, 
p. 130, fig. 108 (adv. sheets, 1862), 1865. 
S. billingsi WINCHELL and ScHuCHERT, Geol. Minnesota, vol. 3, fig. 32, 1895.—WHILSON, 
Geol. Surv. Canada, Bull. 8, p. ror, pl. 11, figs. 14a, b, 1946. 
The type specimen is lost. 
Horizon and locality—Leray (Chaumont)—Rockland in Ontario, Canada. 
STROPHOMENA CANADENSIS Wilson 
Plate 248, A, figure 1 
Strophomena canadensis Witson, Geol. Surv. Canada, Bull. 33, p. 50, pl. 3, fig. 7, 1921. 
Type.—Holotype: G.S.C. 6220. 
Horizon and locality—Pamelia formation, 22 miles west of Ottawa, Ontario, 
at MacLaren Landing. 
