PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 2II 
gins with nearly straight slopes from beak forming indistinct shoulder about 
one-third length of valves from beak; lateral margins rounded ; anterior margin 
gently rounded; anterolateral extremities narrowly rounded. Surface marked 
by irregular concentric undulations that are crossed by irregular interrupted 
radial lines which terminate in short, prone spines. Shell lamellae broad and 
regularly spaced when seen on exfoliated specimens. 
Pedicle valve very gently and evenly convex in lateral profile, broadly convex 
in anterior profile. Greatest convexity slightly posterior to the middle. Anterior 
slope gentle ; lateral slopes short, moderately steep. 
Brachial valve evenly and gently convex in lateral profile, flattened to gently 
convex in anterior profile. Umbonal region convex; anterior to umbo a broad, 
shallow sulcus extending to anterior margin. Outer slopes of folds bounding 
sulcus to lateral margins steep in posterior two-thirds but becoming gentle and 
obsolete toward the anterior. 
Measurements in mm.— 
Length Width 
Solotype. (bsachial, valve): 4: «xj. islam. | -caqulie. gett Be 3a 3.1 
Paratype” (pedicle. valve 116783) .2006 000.2 o see ce eens 4.2 3.0 
Types.—Holotype: 116784a; figured paratypes: 1og281a-e, 116784b-h; un- 
figured paratypes : 116782a-i, 116783. 
Horizon and locality—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—This species is characterized by its ornamentation and small size. 
The exfoliated shell shows regular concentric lamellae, distant and evenly spaced, 
but well-preserved specimens show that the lamellae are covered by a surface 
layer marked by concentric undulations and irregular radial lines terminating in 
short spines. These features will serve to distinguish S. intralamellata from any 
known linguloid from rocks herein treated. 
The appearance of radial ornamentation arises from the fact that the lamellae 
grow over the ends of the spines and therefore become wrinkled. This species 
is abundant at the Pratt Ferry locality but has not been seen elsewhere. It can 
be successfully etched from the limestone by acetic acid. Views of exfoliated 
shells as well as etched specimens have been included because of the frequent 
necessity of identifying specimens on fractured rock surfaces, which is the usual 
way fossils are encountered. 
Subfamily ACANTHAMBONIINAE Cooper, new subfamily 
Subcircular shells with interior apical structures of both like Lingulella. 
Exterior spiny. 
ACANTHAMBONIA Cooper, new genus 
(Greek acanthos, spine; ambon, umbo) 
Shell minute, subcircular to suboval in outline; subequally biconvex ; surface 
covered by minute, hairlike spines extending from the surface at a fairly high 
angle. 
