PART, 0 CHAZYAN AND RELATED BRACHIOPODS—COOPER 983 
LATICRURA PIONODEMA Cooper, new species 
Plate 144, A, figures 1-25; plate 144, C, figures 30-33; plate 145, B, figures 14-19; 
plate 146, A, figures 1-4 
Shell of about the same size as L. latibrachiata, about as wide as long; cardi- 
nal extremities well rounded; lateral margins very slightly curved; anterior 
margin narrowly rounded. Anterior commissure moderately sulcate. Surface 
finely multicostellate, with 5 costellae in 1 mm. at the front margin of the 
holotype. } 
Pedicle valve moderately convex in lateral profile, with the umbo forming the 
most convex part. Anterior margin narrowly rounded. Fold low and inconspicu- 
ous; slopes to the lateral margins steep. Interarea long, strongly curved; beak 
sharp and strongly incurved. Delthyrium narrow. 
Brachial valve moderately convex in lateral profile, slightly shallower than the 
pedicle valve. Anterior third subgeniculate and protruding slightly to form a 
short tongue. Sulcus broad and shallow, originating at the umbo. Flanks slightly 
swollen. Slopes to cardinal extremities fairly steep; lateral slopes moderately 
inclined. Interarea moderately long, beak incurved. 
Measurements in mm.—Holotype, length 11.4, dorsal length 10.3, width 11.0, 
hinge width 8.0, thickness 6.0. 
Types.—Holotype: 1172721; figured paratypes: 117269¢,g,i,k,l, 117270a,b,d, 
117271b,g, 117272e¢,g, 117273, 117274a,b; unfigured paratypes: 11726g9a-d,f,h, 
j,m,n, 117270¢,e-g, 117271a,c-f, 117272a-d,f,h, 117274¢,d. 
Horizon and locality —Effna-Rich Valley formations in Virginia: At Porter- 
field Quarry, 5 miles east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Edinburg formation (base of Liberty Hall facies) in Virginia: 1.8 miles S. 4° 
W. of Bethel Church, 5.9 miles east of Harrisonburg, Harrisonburg (15’) 
Quadrangle. 
Edinburg formation (Cyrtonotella zone) in Virginia: Just above quarry § mile 
northeast of Strasburg Junction, Strasburg (15’) Quadrangle. 
Pratt Ferry formation in Alabama: 0.2 miles southeast of Pratt Ferry, Blocton 
(15’) Quadrangle. 
Discussion.—This species is characterized by its rotund form, its fine, even 
costellae, lack of an apical plate, and broad, shallow sulcus on the brachial valve. 
It is most like L. latibrachiata but differs in having a broader and shallower sul- 
cus and in lacking a deltidial plate. It also possesses a more erect beak than the 
Friendsville species. 
ELASMOTHYRIS Cooper, new genus 
(Greek elasmo, plate; thyris, opening) 
Shell small, biconvex with deep valves, the pedicle valve being the deeper ; out- 
line subrectangular ; sides and anterior rounded; hinge wide but less than the 
midwidth ; anterior commissure sulcate. Pedicle interarea long, delthyrium open ; 
surface multicostellate. Shell interarea long, delthyrium open; surface multicos- 
tellate. Shell substance punctate. 
