PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 919 
field occupying about half the interior, extending from the delthyrial cavity to 
the place of geniculation. Thin median septum prominent. 
Brachial valve gently concave in the posterior three-fifths but with the lateral 
and anterior margins strongly bent in the direction of the brachial valve; greatest 
depth just anterior to the middle. Interior with septa subdued but well de- 
veloped ; cardinal process stout ; subperipheral rim thick and beaded. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness Height 
AMOUVE Az sce + oun ae be eae 23.1 20.9 26.6 30.0 5.6 0.9 
Paratype (117837a)..... 20.8 19.1 21.6 21.9 5.2 9.5 
si Crrz837b ee. 21-2 19.8 22.6 ? 4.0 7.8 
" C1i7836b) eas 4% Piet 10.7 24.1 24.8 3.0 6.3 
, (TIvSage)ii ee, 21.5 19.7 Baus 26.8 4.8 8.8 
% (Guiztee ei) Rar 20.2 19.0 22.9 24.4 3.0 7.9 
a CEr7Zojea) ess. 27 ? 23.5 23.1 ? ? 
re (117839d)..... 20.0 18.7 23.0 24.4 5.0? 77 
‘ (1178390b)..... 24.1 227, 26.2 27.0 4.9 10.3 ? 
Types.—Holotype: 117835a; figured paratypes: 117831b, 117833a,c-e, 
117834a,b,e, 117835b,d, 117836a, 117837a-c, 117838a, 117839b,e,f,h,i ; 123287b; 
unfigured paratypes: 117831a, 117832a-f, 117833b, 117834c,d, 117835¢c,e,f, 
117836b, 117838b, 117839a,c,d,g, 1232872. 
Horizon and locality.—Ridley formation in Tennessee: 0.6 mile south of Chap- 
pel Hill Methodist Church on Tennessee Highway 28, 1 mile south of its junc- 
tion with Tennessee Highway 8, Daus (T.V.A. 104-SW) Quadrangle. 
Wardell formation and Wardell part of Dryden formation in Tennessee: North 
of the canyon of Gap Creek, Powell Valley, military coordinates 790250N, 
2677730E, 14 miles west of Arthur, Cumberland Gap (T.V.A. 153-SW) Quad- 
rangle; Jacksboro, Jacksboro (T.V.A. 136-SW) Quadrangle; road at the base 
of Cedar Ridge 3 mile southeast of Litton, Sequatchie Valley, Pikeville Special 
(15’) Quadrangle; Lone Mountain, Tazewell (T.V.A. 154-NE) Quadrangle; 
U.S. Highway 25E, 4 mile north of Indian Creek, Evans Ferry section, Howard 
Quarter (T.V.A. 162-NW) Quadrangle; on old Tennessee Highway 33, 
0.3 mile southwest of Little Barren Church, Powder Springs (T.V.A. 154-SW) 
Quadrangle; Tennessee Highway 33, 5 mile west of the cemetery at the bend 
below Kecks Mill, Powder Springs (T.V.A. 154-SW) Quadrangle; 2 miles 
northeast and 1 mile west of old Tazewell, Tazewell (T.V.A. 154-NE) Quad- 
rangle; back of Camp Loyston, Maynardville (30’) Quadrangle. 
Same formation in Virginia: In the north quarry on Station Creek, 4 mile 
south of U. S. Highway 58, 2 miles east of Cumberland Gap, Wheeler (T.V.A. 
153-SE) Quadrangle. 
Ridley formation in Murfreesboro (15’) Quadrangle, Tennessee: In the 
lower third of the formation on the east side of Marshall Knobs, 5 miles south 
of Murfreesboro; Bradleys Creek 1 mile east of Murfreesboro. 
Pierce formation in Tennessee: Bradleys Creek, 1 mile east of Lascassas, 
Rutherford County. 
