PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 969 
PAURORTHIS MACRODELTOIDEA Cooper, new species 
Plate 151, A, figures 1-6 
Shell of about average size for the genus; hinge equal to about three-quarters 
the width. Lateral margins well rounded, anterior margin broadly rounded. An- 
terior margin sulcate. Surface fascicostellate, fascicles numerous but not well 
defined. About 4 costellae in 1 mm. at the front margin. 
Pedicle valve strongly swollen longitudinally to form an indistinct median fold 
and giving the valve a subcarinate anterior profile. Slopes from the median fold 
to the margin steep. Fullness of pedicle valve extended to the front margin, al- 
though the convexity in the anterior portion is not so great as that in the umbo- 
nal region. Interarea only moderately curved. Delthyrium partially closed by 
lateral plates. 
Brachial valve most convex in the umbonal region and posterior half; anterior 
half somewhat depressed and anterior margin slightly extended at the sulcus to 
form a short tongue. Sulcus originating at the umbo, shallow but widening and 
deepening anteriorly. Flanks bounding sulcus gently swollen; slopes to cardinal 
extremities slightly concave, moderately steep. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Eiplotype 420......e28< 10.0 8.8 10.6 7O7 5.0 
Paratype (117284b).... 9.7? 8.6 10.4 78? 5.8 
ss (6007285) Bios eee 9.2? 8.4 10.4 8.0 5.4 
Types.—Holotype: 117284a; figured paratype: 117285; unfigured paratypes: 
117284b-g. 
Horizon and locality—Bromide formation (Pooleville member) in Murray 
County, Oklahoma: Zone 13, 241 feet below Viola, Spring Creek, east of Poole- 
ville, sec. 17, T. 2 S., R. 1 W.; West Spring Creek, sec. 6, T. 2 S., R. 1 W. 
Discussion.—The occurrence of this genus in the Simpson sequence is inter- 
esting because it is a link to the Southern Appalachians. The species is similar 
to P. catawbensis and P. fasciculata of the Southern Appalachians but differs in 
having stronger costellae than the former and less regular fasciculation than the 
latter. 
PAURORTHIS MAGNA Cooper, new species 
Plate 149, C, figures 10-25; plate 149, E, figures 30-33; plate 149, F, figures 34-43 
Shell large for the genus, slightly wider than long, valves strongly convex, 
and hinge equal to a little less than three-quarters the width at the middle. 
Cardinal extremities well rounded. Lateral and anterior margins broadly 
rounded. Anterior commissure broadly sulcate. Surface fascicostellate, fascicles 
consisting of 5 to 7 costellae. Fascicles not strongly elevated, a deep, narrow 
groove extending from the umbo of the brachial valve to the front margin. On 
the pedicle valve this groove represented by a costella stronger than those sur- 
rounding it. 
Pedicle valve moderately convex in lateral profile with the greatest convexity 
