PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 5I1 
median costella on the pedicle valve, and the deep, narrow sulcus on the brachial 
valve. The only other species like it are those of Laticrura, but in that genus the 
shell is punctate, the median ridge is low, and the sulcus of the brachial valve is 
never so deep as that of Phragmorthis. 
This peculiar little shell occurs in abundance in the thin limestones above the 
large reef in the Porterfield Quarry, Va., and in the Pratt Ferry formation at 
Pratt Ferry, Ala. In both places the shells are silicified. 
PHRAGMORTHIS CRASSA Cooper, new species 
Plate 126, F, figures 30-35 
Shell large for the genus, subquadrate in outline, wider than long; hinge nar- 
row ; cardinal extremities narrowly rounded ; sides moderately rounded ; anterior 
margin broadly rounded; anterior commissure narrowly sulcate. Surface multi- 
costellate, costellae numbering about 45 and spaced about 2 to the millimeter at 
the front margin. 
Pedicle valve gently and unevenly convex, the maximum convexity just an- 
terior to the umbo and with the remainder of the valve flattened. Anterior profile 
subcarinate. Umbo narrowly convex, the convexity continued anteriorly as a 
low, narrow fold; flanks bounding fold flattened and descending fairly steeply 
to the lateral margins. Interarea long and steeply apsacline. 
Brachial valve moderately convex in lateral profile and with the maximum 
convexity in the posterior third, the anterior two-thirds somewhat flattened. An- 
terior profile broadly and moderately convex; sulcus originating at the umbo 
and forming a narrow, steep-sided gash, widening only slightly in its passage to 
the anterior margin. Flanks bounding sulcus moderately swollen and with short, 
moderately steep lateral slopes. Beak strongly incurved and overhanging the 
interarea of the pedicle valve. 
Measurements in mm.—Holotype, length 7.4, brachial length 7.2, midwidth 
8.9, hinge width 6.2, thickness 4.0. 
Type.—Holotype: 116963. 
Horizon and locality.—Base of Martinsburg formation (part with Brongniar- 
tella= Salona formation) in Virginia: On Virginia County Road 617=910, 0.15 
mile north of Green Mount Church, Broadway (15’) Quadrangle. 
Discussion—This species is characterized by the subcarinate pedicle valve 
and the deeply and narrowly sulcate brachial valve combined with the strong 
costellae. The latter are stronger than the costellae of P. buttsi. Furthermore, 
this species attains a larger size and is more deeply sulcate and carinate than the 
Pratt Ferry-Effna species. 
Suborder CLITAMBONITOIDEA Opik, 1934 
Superfamily CLIrAMBONITACEA Schuchert, 1929 
Family TRITOECHIIDAE Ulrich and Cooper, 1936 
Primitive Clitambonitacea with or without a spondylium but with perforate 
deltidium and chilidial plates; brachiophore supporting plates short, obscure. 
