NO. 12 PERMIAN BRACHIOPODS FROM OREGON—COOPER 23 
shape of the two is different, the Texas form having a more elongated 
and attenuated beak of the pedicle valve. In M. skenoides the in- 
clination of the interarea is like that of the Oregon species but the 
ribbing of the Texas species is stronger and broader. Actually the 
American species most like the Oregon one is from the early Permian 
of Kansas and now called M. striatocostata (Cox). The latter spe- 
cies, which is identified in Pennsylvanian as well as Permian rocks, 
is in serious need of revision. 
Suborder CHONETOIDEA Muir-Wood, 1955 
Superfamily CuHonetacea Shrock and Twenhofel, 1953 
Family CHONETIDAE Hall and Clarke, 1895 
CHONETES sp. 1 
Plate 11, figures 27-35 
Shell of about medium size for the genus, transversely subrec- 
tangular in outline; hinge narrower than the widest part which is 
just posterior to the middle; sides gently rounded; anterior margin 
broadly rounded. Surface marked by fine costellae about 4 in I mm. 
at the front margin. 
Pedicle valve moderately convex in lateral profile, broadly convex 
in anterior profile; beak small, incurved; umbo low and only gently 
swollen; sulcus varying from shallow to moderately deep, extending 
from the umbo to the front margin; flanks moderately swollen; slopes 
to cardinal extremities flattened and steep. 
Brachial valve gently concave; umbo deeply concave, the concavity 
widening anteriorly but flattening and becoming imperceptible in the 
anterior half. Posterolateral extremities flattened. 
Measurements in mm.—Figured specimen, U.S.N.M. 125470, 
length 14.6, brachial valve length 13.2, maximum width 20.9, hinge 
width 18.3, thickness 3.7 (this is the actual measure but the valve 
is exfoliated on the dorsal side; the true thickness must have been 
about 4.0), height 5.3; figured specimen, U.S.N.M. 125318, length 
15.5, maximum width 23.1, hinge width 19.0, height 4.4?. 
Types.—Figured specimens, U.S.N.M. 125318, 125319, 125470a,b. 
Localities —P12; S31, $47, S68, S111; U.O. 2201-3, 2202-2. 
Discussion—This is a large species but the specimens in the col- 
lection are few and poorly preserved. Of North American described 
chonetids the Oregon specimens are most like C. deliciasensis King 
(1930) in the flatness of the brachial valve and the shallowness of 
the median sulcus of the pedicle valve, but the latter feature may be 
