PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 515 
broadly unisulcate. Surface multicostellate, with about 3 costellae occupying 
I mm. 
Pedicle valve gently convex in lateral profile, with the strongest convexity in 
the posterior half; front half flattened. Anterior profile with the strongest con- 
vexity at the center and the lateral slopes flattened and gently inclined. Umbonal 
region somewhat swollen. Sulcus originating at the middle of the valve deepen- 
ing and widening to the front margin, the sulcus producing a short, narrowly 
rounded tongue. Anterolateral flanks bounding the sulcus flat; slopes to cardinal 
extremities moderately steep, flat in profile. 
Brachial valve evenly convex in lateral profile with the greatest convexity at 
the umbo; moderately strongly convex in anterior profile. Umbo swollen, pro- 
truding beyond the posterior hinge margin. Umbo depressed medially by a faint 
and narrow sulcus which disappears at the middle where a low but distinct fold 
originates and extends to the front margin. Flanks of shell steeply inclined. 
Slopes to cardinal extremities steep; cardinal extremities deflected. Interarea 
short, curved. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Fioletypeirysjaits dasa 19.0 18.5 22.4 16.6 12.5 
Paratype (117062).. 20.3 17.5 23.0 16.0 11.8 
Types.——Holotype: 117061a; figured paratypes: 117061b, 117062. 
Horizon and locality—Arline formation in Tennessee: 4 mile southeast of 
Friendsville, Concord (T.V.A. 138-SW) Quadrangle; 1 mile southeast of Fow- 
lers Mill, 10 miles southeast of Loudon, Loudon (30’) Quadrangle. 
Discussion.—This, like all known species of Eremotoechia, is a very rare one. 
At the present writing only four specimens are known. These four specimens 
indicate this to be the largest species in size and the one with the strongest orna- 
mentation. The species is further characterized by the disproportionate depth 
of the two valves, the brachial valve having the greater depth. The pedicle valve 
is characterized by its generally gentle convexity; the brachial valve is distin- 
guished by its rounded contours and the inconspicuous sulcus and the indefinite 
anterior fold. This species differs from the other two known ones in its superior 
size, lack of pedicle folding, and modest development of the brachial sulcus. 
EREMOTOECHIA SILICICA Cooper, new species 
Plate 50, B, figure 7; plate 99, H, figures 47-52; plate 186, F, figures 20-25 
Smaller than the preceding species ; wider than long and having a subquadrate 
to subrectangular outline. Valves subequal in depth, the brachial valve having a 
slightly greater depth. Sides and anterior margin rounded; anterior commissure 
broadly and gently uniplicate. Surface multicostellate ; costellae narrow and sepa- 
rated by spaces greater than the width of the costellae ; about 3 costellae in 1 mm. 
at the front margin. 
Pedicle valve unevenly convex in lateral profile, the median portion somewhat 
