PARTI CHAZYAN AND RELATED BRACHIOPODS—COOPER 937 
studied, but a specimen in the National Collection from the Hull at Kirkfield, 
Ontario, is similar to the illustrated specimen. 
STROPHOMENA FILITEXTA OBESA Wilson 
Strophomena filitexta obesa Witson, Trans. Roy. Soc. Canada, ser. 3, vol. 39, sec. 4, p. 133, 
pl. 1, figs. 20-21, 1945; Geol. Surv. Canada, Bull. 8, p. 103, pl. 9, figs. 17a, b, 18, 1046. 
Types.—Holotype: G.S.C. 7651; paratype: G.S.C. 7570. 
Horizon and locality—Leray = Rockland formation, in Ontario, Canada: Pa- 
quette Rapids, Ottawa River; southeast of Cumberland. 
STROPHOMENA GRANDIMUSCULOSA Cooper, new species 
Plate 256, C, figures 8-17 
Shell of about medium size for the genus, wider than long and with the hinge 
forming the widest part; well-preserved specimens auriculate; sides somewhat 
oblique and indented just anterior to the cardinal extremities ; anterior margin 
gently rounded. Costellae variable in size, fine and crowded, about 17 to 20 in 
5 mm. at the anterior margin of an adult. Entire surface covered by fine con- 
centric fila. 
Pedicle valve moderately concave in lateral profile and with the maximum 
concavity at about the middle or slightly anterior to it. Umbo narrowly con- 
vex for a short distance only ; median region concave; posterolateral extremities 
flattened. Interior with narrow, thin teeth and dental ridges ; muscle area large, 
usually rhomboidal in outline, the anterior end reaching the middle of the valve 
or extending slightly anterior to it. Median ridge stout. Anterior ends of diduc- 
tor scars usually elongate and making the anterior angle of the rhomb. Inter- 
area moderately long, strongly apsacline ; pseudodeltidium subcarinate. Foramen 
minute. Subperipheral rim moderately strongly developed. 
Brachial valve moderately and fairly evenly convex in lateral profile; broadly 
and evenly convex in anterior profile; maximum convexity at about the middle 
or just anterior to it. Umbo forming a small, shallow concavity ; median region 
swollen and with steep anterolateral and anterior slopes. Posterolateral slopes 
less steep than the others; cardinal extremities set out by a broad, oblique 
groove. Interior with small cardinalia, a short and low median ridge; adductor 
scars striated. Subperipheral rim moderately developed. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
Holotype Heres Ppeisc hee J 21st 19.1 25.3 20.2 3.5 
Paratype (117721D) 2. oss. oe 23.2 ? 30.2 36.8 ? 
es (LIZ 7BAD OPA 21.4 ? 27.1 32.8 ? ? 
s (ETZ72AD i sheers anche a ? 24.5 35.3 39.8 ? ? 
(LDF 22 Nai token sien 21.8 19.5 25.2 26.7 4.2 
Types—Holotype: 1177214; figured paratypes: 117720a, 11772I1b, 117722, 
117724a,b; unfigured paratypes: 117720b, 11772Ic, 117723, 117724c. 
Horizon and locality—Lebanon formation (Doleroides zone) in Rutherford 
