PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 531 
Brachial valve nearly circular in outline; lateral profile strongly convex and 
with the greatest convexity at about the middle; anterior profile strongly con- 
vex ; fold formed by a broad wave of the anterior commissure toward the brachial 
valve; fold only slightly visible at the anterior third as a narrow, short 
subcarinate elevation. Brachial interior with forked cardinal process. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
LOLOL VIDE. ait. state cietels ol Heelt so sieves 6.6 5.5 6.1 2.6 3.3 
Paratype «(r7oSge)....-8hh.s.... 5.4 4.7 4.8 1.9 1.8 
Types.—Holotype : 117089a ; figured paratypes : 117089b-e ; figured specimens : 
118009a,b. 
Horizon and locality —Lenoir formation in Tennessee: From the calcarenites 
under the Mosheim calcilutite of the southwest side of the cemetery at Friends 
Church, north corner of Friendsville, Concord (T.V.A. 138-SW) Quadrangle. 
Also, 3 feet above the Mosheim limestone south of the Friends Church, same 
locality. 
Discussion—This species is characterized by its fairly short beak, the wide 
apical angle, which is almost a right angle, the modest convexity of the valves, 
and the moderate folding of the anterior commissure. It thus differs from 
O. longirostris and O. gracilis which have more attenuate pedicle valves. Ony- 
choplecia obesa attains a much greater swelling of the brachial valve, and its 
pedicle beak is more slender than that of the Friendsville species. 
This little species is uncommon and hard to find. It occurs above and below 
the “Mosheim” calcilutite. In the higher occurrences it appears in a coarse cal- 
carenite and the valves are generally separated. The specimens from below the 
“Mosheim” band were taken from a shale patch in the calcarenites. 
ONYCHOPLECIA GRACILIS (Raymond) 
Plate 100, C, figures 11-14 
Triplecia gracilis RAYMOND, Bull. Amer. Paleont., vol. 3, p. 303, pl. 18, fig. 1, 1902. 
Camerella longirostra RAYMoND (not Billings), Ann. Carnegie Mus., vol. 7, No. 2, p. 249, 
pl. 36, figs. 29, 30, TOIT. 
Fairly large for the genus, elongate tear-shaped in outline; sides rounded; 
pedicle beak elongate with concave lateral margins ; anterior commissure strongly 
uniplicate. Surface marked by strong, regular concentric lines. 
Pedicle valve with elongated beak forming an apical angle of about 50°. Lat- 
eral profile gently concave to flat in posterior part, moderately convex on body 
of shell; anterior profile broadly and moderately convex. Median region swollen. 
Sulcus short, narrow, deep, originating slightly anterior to the middle and oc- 
cupying slightly less than half the width at the front margin. Posterolateral 
slopes moderately steep; anterolateral slopes gentle. Interior with divergent 
dental lamellae. 
Brachial valve broadly oval in outline with the maximum width anterior to 
