PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 265 
to show any details of the musculature or pallial impressions. One brachial valve, 
plate 15, C, figure 7, gives indications of a median ridge, but the structure is 
badly crushed and it is impossible to make sure of its details. 
A few specimens show the posterior margin fairly well. This margin on the 
pedicle valve swells slightly in an anterobrachial direction and fits into a slight 
reentrant anterior to the beak on the margin of the brachial valve. 
Schizambon, even though locally fairly common, ranges too high vertically and 
is generally too rare to be of great value in stratigraphy. It occurs in all types 
of matrix from the calcarenite marbles to the black limestones and shales of the 
Liberty Hall facies. 
SCHIZAMBON CUNEATUM Willard 
Plate 15, E, figures 20-22 
Schizambon cuneatus WILLARD, Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, No. 6, p. 257, 
pl. 1, fig. 4, 1928. 
Shell large for the genus, suboval in outline, and with the valves unequal in 
depth and outline. Lateral margins gently rounded; anterior margin narrowly 
rounded. Greatest width at about the anterior third. 
Pedicle valve slightly convex in lateral profile, broadly convex in anterior pro- 
file. Track of foramen widening gradually, in length equal to about one-third 
the valve length. Median region from foramen nearly to front margin slightly 
swollen. Lateral slopes short and moderately steep. Area surrounding pedicle 
groove marked by closely spaced, elevated concentric lines. Anterior two-thirds 
marked by pairs of concentric bands. Spines slender, about 2 mm. or less in 
length. 
Brachial valve nearly circular in outline, gently convex in both profiles. Sulcus 
originating at beak, shallow, widening gradually anteriorly to the front margin. 
Sulcus defined by 2 distinct but narrow costae. Flanks gently convex. Umbonal 
region marked by small spines arranged alternately, the space between each spine 
marked by a fine elevated line, the radial and concentric elements producing a 
very fine cancellation. Anterior to the umbonal region valve marked by paired 
concentric bands. 
Measurements in mm.— 
Length Width Thickness 
Hetorype ‘(pedicte valve) °2. 00. FP ee aes 14.2 12.8 ? 
Hypotype (brachial valve 109668) ........... 12.4 13.5 ? 
Type.—Holotype: M.C.Z. 8588; hypotype: U.S.N.M. 109668. 
Horizon and locality—Effna formation in Virginia: McNutt’s Quarry, 12 
miles southwest of Bland, Burkes Garden (15’) Quadrangle; Porterfield Quarry, 
5 miles east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Botetourt formation in Virginia: Hays Creek, 2 miles northwest of Browns- 
burg, Lexington (15’) Quadrangle. 
Discussion—This species is most like S. macrothyris but differs in having a 
smaller and more symmetrical pedicle groove, not having radial elements in the 
