PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 649 
ing gradually anteriorly, gently convex in profile; flanks moderately convex and 
with moderately steep slopes to the margins. 
Interior: Teeth small, supported by short dental plates separated from the 
outside wall of the shell by narrow umbonal cavities ; pedicle callist slightly thick- 
ened. Brachial valve with a high and thin median septum supporting a short, 
shallow, and narrow cruralium which in turn supports a divided hinge plate. 
Crura long, slender and curved. 
Measurements in mm.— 
Brachial 
Length length Width Thickness 
FAGIOUY PEM Macuser aaientes sat sk oes 14.3 12.7 14.4 8.6 
Paratype, GlOSZ056)s i... ne ane a es 15.3 13.8 15.3 9.3 
Types.—Holotype: 108205a; figured paratypes: 108205b-d,h ; unfigured para- 
types: 108205¢,f,g ; figured hypotypes: 111531a,b, 111535, I11541a-c, 117226a,b, 
117227. 
Horizon and locality—Wardell formation in Tennessee: 7 miles southwest of 
Clinton, Clinton (T.V.A. 137-SW) Quadrangle; 14 to 2 miles northeast of 
Loyston, Maynardville (30’) Quadrangle. 
Dryden formation in Tennessee: On the road to Tazewell, 14 miles northeast 
of Lone Mountain, Tazewell (T.V.A. 154-NE) Quadrangle. 
Ridley formation in Tennessee: 1 mile west of the courthouse in Murfrees- 
boro, Murfreesboro (15’) Quadrangle. 
Pierce formation in Tennessee: At Murfreesboro, Murfreesboro (15’) Quad- 
rangle. 
Wardell part of Dryden formation in Virginia: In a quarry just east of Vir- 
ginia Highway 70, northeast of the Powell River, 1.6 miles south of Jonesville, 
Ben Hur (T.V.A. 170-NE) Quadrangle ; quarry on Station Creek, $ mile south 
of U. S. Highway 58, 2 miles east of Cumberland Gap, Wheeler (T.V.A. 
153-SE) Quadrangle. 
Discussion—This is a fairly large species with somewhat distant costae, a 
moderately wide fold and sulcus, and triangular outline. It differs from R. plena 
in its lesser convexity and more distant costae. It is suggestive of R. truncata, 
but that species is much more strongly costate and is truncated anteriorly. 
Rostricellula tumidula is a strongly costate Appalachian form, but its large size 
and somewhat swollen valves are not likely to be confused with R. rostrata. 
Rostricellula rostrata as here described and figured may be a composite species. 
Specimens from the Benbolt-Wardell=Dryden shale with Dinorthis transversa 
on the Tazewell road 14 miles northeast of Lone Mountain are not quite char- 
acteristic in profile and are somewhat less wide anteriorly. These features may 
be old age characters. 
ROSTRICELLULA ROTUNDATA Cooper, new species 
Plate 130, B, figures 12-22 
Shell fairly large, somewhat elliptical in outline with the width greater than 
the length; sides narrowly rounded; anterior margin nearly straight to slightly 
