PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 213 
ACANTHAMBONIA VIRGINIENSIS Cooper, new species 
Plate 9, A, figures 1-6 
Shell small, nearly circular in outline and with a small beak; surface marked 
by crowded hairlike spines. Pedicle valve moderately convex in lateral profile 
but with the greatest convexity located in the posterior third which is somewhat 
swollen. Anterior slope long and gently convex. Umbonal region faintly carinate. 
Anterior profile moderately convex, swollen in the middle with moderately steep 
lateral slopes. Greatest width at the middle. 
Brachial valve moderately convex in lateral profile but with the greatest depth 
at the middle; median region swollen; lateral and anterior slopes fairly steep. 
Measurements in mm.— 
Length Width Thickness 
Holotype (brachial valve) (05.10 ctt DUE 2.1 2.1 ? 
Paratype (pedicle valve 116797a) ............ 2.7 3.5 0.6 
Types.—Holotype: 116797e; figured paratypes: 116797a-d; unfigured para- 
types : 116797f-h. 
Horizon and locality.—Botetourt formation in Virginia: Field on the south 
side of the road 0.2 mile east of Strasburg Junction, Strasburg (15’) Quadrangle. 
Discussion.—This species was recovered in debris from the etching of lime- 
stone blocks by hydrochloric acid. The species is suggestive of A. minutissima, 
but it is a much larger shell with more numerous spines. The surface of A. vir- 
giniensis is densely crowded with minute, delicate, and long spines. Furthermore, 
the pedicle interior has more strongly developed propareas. 
Subfamily GLOSSELLINAE Cooper, new subfamily 
Elongate and narrowly oval oboloids with pedicle groove ; brachial valve with- 
out concave apical plate, posterior margin more or less thickened. 
Genus LEPTOBOLUS Hall, 1871 
Plate 12, A, figures 1-4; plate 12, B, figures 5. 6 
Shells small, oval in outline with subequally convex valves. Brachial valve 
generally more convex and rounder in outline than the pedicle valve. Beak of 
pedicle valve pointed. Surface of both valves ornamented by fine concentric 
lines and, in one species, fine radial lines. Pedicle interior characterized by a 
pedicle groove with narrow propareas on each side. Low median ridge anterior 
to pedicle groove extending nearly to the middle where it forks narrowly, each 
prong of the fork extending to about the middle of the valve and forming a shal- 
low V-shaped chamber. 
Brachial valve characterized by a complete posterior margin with small cal- 
losity at the apex. Interior surface marked by 1 or 3 low ridges. Median ridge 
the longer and extending nearly to the front margin where it is minutely forked. 
Lateral ridges shorter than the median ridge and not present in all species, 
diverging toward the anterolateral margin. 
