PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 981 
vex, the anterior half moderately bent toward the pedicle valve; beak well de- 
fined, protruding posterior to the posterior margin ; umbo swollen, sulcate ; sulcus 
deep and narrow; forming a short tongue at its anterior end. Flanks swollen 
with moderate slopes to the lateral margins and medianly to the sulcus. 
Measurements in mm.—Holotype, length 8.9, brachial length 7.6, width 10.2, 
hinge width 8.8, thickness 5.9. 
Types.—Holotype: 117263a; figured paratype: 117263d; unfigured paratypes: 
117263b,c,e. 
Horizon and locality.—Little Oak formation in Alabama: At the junction of 
the Bailey Gap and Cahaba Valley roads, SW4SW3 sec. 13, T. 19 S., R. 2 W., 
1? miles northeast of Newhope Church, Vandiver (15’) Quadrangle; cut on 
U. S. Highway 31, 4 mile north of Pelham, Bessemer Iron District (15’) 
Quadrangle. 
Discussion.—This species is distinguished from the others described herein 
by the great development of swollen and hollow costellae on the exterior. It has 
a deeper and more pronounced sulcus in the brachial valve than that of L. piono- 
dema. It is closest to L. latibrachiata but differs in ornamentation and in a more 
erect and incurved beak. 
LATICRURA LATIBRACHIATA Cooper, new species 
Plate 143, E, figures 19-24; plate 145, A, figures 1-13; plate 149, B, figures 4-9 
Shell subcircular in outline, with the length and width about equal. Hinge 
narrower than the greatest width which is near the middle. Lateral margins 
rounded; front margin broadly rounded to slightly emarginate at the middle. 
Anterior commissure sulcate. Surface multicostellate, with about 4 costellae in 
the space of I mm. at the front margin. 
Pedicle valve gently convex in lateral profile; somewhat carinate in anterior 
profile. Middle of valve from the beak to the anterior margin swollen a little 
to form a low and poorly defined fold which is also responsible for the slight 
emargination of the front. Lateral slopes from the fold to the margins steep. 
Interarea elongate, curved; beak strongly incurved, narrow and sharp. 
Brachial valve nearly equal to the pedicle valve in depth, moderately convex 
in lateral profile, lobate in anterior profile. Sulcus, shallow and narrow, origi- 
nating at the umbo and extending to the front margin where the valve is ex- 
tended slightly to form a short but inconspicuous tongue. Flanks swollen with 
fairly steep slopes to the sulcus and the lateral margins. Lateral slopes steepest 
toward the cardinal extremities ; slopes to the sulcus short and steep. Interarea 
long for this structure on a brachial valve. 
Interior of the pedicle valve characterized by good development of the apical 
plate, and the brachial valve by the ponderous development of the brachiophores. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
TPOIOLVDE wie siecle cnc s ts 8.9 8.1 9.6 8.0 6.6 
Paratype (117265p)..... 8.0 7.5 0.5 7 | 5.0 
