PART I CHAZYAN AND RELATED BRACHIOPODS—-COOPER 195 
Brachial valve more strongly convex than the pedicle valve and with the great- 
est convexity slightly posterior to the middle. Beak narrow and prominent ; 
umbo swollen. Anteriorly the convexity becomes less. 
Measurements in mm.—Hypotype 109422a, length 13.3, width 9.3, greatest 
width 10.5, thickness 5; hypotype 109422b, length 23.9, greatest width 22.1. 
The proportions of the larger specimens agree with those of Dr. Willard’s 
type specimen. 
Types.—Holotype: M.C.Z. 8587; figured hypotypes: 109422a,b; unfigured 
hypotypes: 109422c,d. 
Horizon and locality—Murat formation in Virginia: 2 miles northwest of 
Lexington, Lexington (15’) Quadrangle. 
PSEUDOBOLUS sp. 1 
A single valve of another species occurs in the collection. The specimen is 
subtriangular in outline, chalky grayish white in color. The surface is smooth 
except for 4 deep concentric grooves representing resting stages of growth. 
Greatest width in anterior third. The lateral profile is moderately convex with 
the greatest curvature at the umbo. Anterior profile is broadly convex with a 
flattened median region and short but steep lateral slopes. 
Measurements in mm.—Length 15.6, midwidth 12.5, greatest width 16. 
Described specimen.—109421. 
Horizon and locality —Effna formation in Virginia: In the lower part of the 
McNutt Quarry, 12 miles south of Bland, Burkes Garden (15’) Quadrangle. 
Discussion.—This species differs from adult P. gibbosus by its plaited exterior 
and more attenuate form. 
Subfamily LINGULELLINAE Schuchert, 1893 
Elongate and narrowly oval oboloids with pedicle groove; brachial valve with 
concave, transversely striated apical plate. 
Until recently it has not been possible to distinguish the true generic charac- 
ters of most of the early and middle Ordovician linguloids. The etched material 
from Pratt Ferry has permitted a good look at the hinge structures, but the 
muscle arrangements are still to be worked out. The type species of Lingulella 
comes from the Ordovician. Most of the species referred here to Lingulella have 
not revealed their hinge structures. It is believed to be sounder to refer all these 
to Lingulella, which is an Ordovician genus, rather than to call them Lingula, 
which is a recent genus. 
Genus LINGULELLA Salter, 1866 
LINGULELLA ALABAMENSIS Cooper, new species 
Plate 8, E, figures 12, 13 
Shell small for the genus, brown to yellow-brown in color, widely oval in out- 
line and with the greatest shell width anterior to the middle. Pedicle valve with 
