370 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
vex. Posterior third somewhat swollen; sulcus originating almost at the pos- 
terior margin defined chiefly by the median depression corresponding to the 
median costa of the pedicle valve, extending to the anterior margin. Flanks mod- 
erately convex with gentle slopes to the posterolateral areas. Interarea anacline, 
fairly long. Median ridge extending slightly anterior to the middle; brachio- 
phores short, cardinal process moderately stout. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
PAQIOEV PE) ag has beee ceems ? 6.8 8.6 7.5 2.5 
Paratype (110067f) ..... 5.8 ? 7.8 5.9 2.6 
Types.—Holotype: 110067c; figured paratypes: 110067d-f, 116935a-c; un- 
figured paratypes: 110067a,b, 116935d-f. 
Horizon and locality.—Effna formation, Effna-Rich Valley formations in Vir- 
ginia: At Porterfield Quarry, 5 miles east of Saltville, Maccrady (T.V.A. 
218-NW) Quadrangle; opposite junction of highway with Hays Creek, 2 miles 
northwest of Brownsburg, Lexington (15’) Quadrangle; McNutt Quarry, 12 
miles southwest of Bland, Burkes Garden (15’) Quadrangle. 
Pratt Ferry formation in Alabama: 0.2 mile southeast of Pratt Ferry, Blocton 
(15’) Quadrangle. 
Discussion.—This species can be recognized by its small size and the distant 
broad costae on the exterior. It differs from all other species herein described 
in the character of its ornamentation. 
GLYPTORTHIS IRREGULARIS Cooper, new species 
Plate 45, A, figures 1-6 
Shell of about medium size for the genus, wider than long; unequally bicon- 
vex, the pedicle valve having the greater convexity; hinge narrower than the 
greatest shell width which is at the middle; anterior commissure rectimarginate ; 
side gently rounded, anterior margin broadly rounded; surface multicostellate, 
costellae about 32 in number, crossed by strong imbricating lamellae about 2 to 
the millimeter. 
Pedicle valve unevenly convex in lateral profile with the most convex part at 
the umbo; anterior profile fairly strongly convex, the convexity greatest in the 
median region with the sides sloping steeply to the margins. Umbo somewhat 
narrowly swollen; anterior portion somewhat flattened; lateral slopes to the 
cardinal extremities steep. Interarea slightly curved, strongly apsacline. Teeth 
small, delthyrial cavity deep ; muscle field long, extending to the middle ; anterior 
ends of diductor scars extended anterior to adductor track. 
Brachial valve gently convex in lateral profile, broadly and gently convex in 
anterior profile, umbo sulcate ; sulcus broad and shallow, scarcely defined at the 
anterior margin ; flanks bounding sulcus gently swollen and with gentle slopes to 
the posterolateral areas. Brachiophores widely divergent, stout ; notothyrial plat- 
form somewhat thickened; cardinal process a thin ridge. 
