PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 943 
Measurements in mm.— 
Brachial Hinge ; 
Length length Width width Thickness 
TIGIOL YE... RG: DI. Jat 13.5 13.4. 16.8 ? 2.9 
Paratype » (177392) scr «at 20s ? II.0 13.6 14.0 ? 
‘e GED77900'),. kes oe we 12.8 ? 16.6 17.3 ? 
Types—Holotype: 117738a; figured paratypes: 117739a,b; unfigured para- 
types: 117738b, 117739¢c. 
Horizon and locality.—Bromide formation (Pooleville member-just above zone 
with Multicostella convexa) in Oklahoma: At Rock Crossing of Hickory Creek, 
approximately center sec. 35, T. 5 S., R. 1 E., Criner Hills, Carter County; 
Spring Creek, sec. 17, T. 2 S., R. 1 W., Murray County. 
Discussion.—This species is small in size like S. crinerensis but differs in its 
more uniformly square outline, strong median fold and sulcus, less-cancellated 
surface ornamentation, less-developed cardinal extremities, and details of the 
musculature. 
STROPHOMENA OKULITCHI Cooper, new name 
Plate 265, B, figures 3, 4 
Strophomena corrugata Oxutitcu (not Conrad 1842), Canadian Field-Nat., vol. 49, No. 6, 
p. 90, pl. 1, fig. 7, 1935. 
This is a small, deeply concave species known only from the pedicle valve. 
The species is especially interesting because of the strong, coarse pseudopunctae 
arranged in rows as in Rafinesquina. 
The new name is proposed to replace Strophomena corrugata Conrad, Journ. 
Acad. Nat. Sci. Philadelphia, vol. 8, p. 256, pl. 14, fig. 8, 1842, which preoccupies 
the Okulitch name. 
Type——Holotype: Peter Redpath Mus., McGill Univ., Montreal (no 
number). 
Horizon and locality—Leray =Chaumont formation in Canada: At St. Vin- 
cent de Paul, Quebec. 
STROPHOMENA PLANOBESA Cooper, new species 
Plate 261, A, figures 1-13; plate 261, B, figures 14-17 
About average size for the genus, wider than long, hinge forming the widest 
part; sides straight or slightly oblique, indented anterior to the auriculate cardi- 
nal extremities. Anterior margin strongly rounded; costellae variable, alternat- 
ing in size, 13 to 17 in 5 mm. at the front margin of a large adult. 
Pedicle valve gently concave in lateral profile but with the posterior quarter 
slightly convex ; greatest concavity just anterior to the middle; umbo narrowly 
swollen to form a short fold; flanks on each side of fold gently concave ; median 
half gently concave ; front half and sides deflected toward the pedicle valve. In- 
terarea moderately long; pseudodeltidium wide and low, subcarinate. 
Brachial valve unevenly convex in lateral profile, with the posterior quarter 
flattened but the median region strongly convex; anterior profile narrowly con- 
