PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 409 
VALCOUREA OBSCURA Cooper, new species 
Plate 76, A, figures 1-10 
Shell of about medium size for the genus, wider than long, with the hinge 
forming the widest part. Cardinal extremities generally acute to alate. Lateral 
margins gently convex; anterior margin broadly rounded. Surface marked by 
subangular costellae separated by interspaces wider than the costellae. About 
13 costellae in 5 mm. at the front margin of a shell 8 mm. long. 
Pedicle valve gently concave with the most concave part slightly anterior to 
the middle. Umbo carinate; carina short and narrow, indistinctly extending to 
the anterior margin as a slight elevated area. Posterolateral areas flattened. In- 
terarea strongly apsacline. 
Brachial valve strongly convex in lateral profile but broadly convex in an- 
terior profile. Umbo marked by a narrow and shallow sulcus that is extended 
anterior to the front margin where it has widened considerably but occupies only 
about 2 mm. Flanks bounding sulcus somewhat inflated. Anterior slope mod- 
erately steep. 
Pedicle interior with stout dental plates, the usual muscle field for the genus, 
but poorly defined pallial marks. Brachial interior with stout median ridge 
extending to about the middle. Brachiophores small but stout. 
Measurements in mm.— 
Hinge 
Length Width width Thickness 
FHolotypel Mek Ii ese 10.8 14.4 16.3-+ 3.0 
Paratype M(rla254d re cnt. oe 8.3 13.0 14.3 2.5 
i (GUO 2S) eae kis: 8&9 15.5 14.3-++ ans 
# (TITOZ5AA) sakes Stele 0.4 14.9 16.3-+ ? 
Types.—Holotype: 110254e; figured paratypes: 110254d, 116966; unfigured 
paratypes: I110254a-c. 
Horizon and locality Lenoir formation in Tennessee: 2 miles south of Phila- 
delphia ; small quarry between the Southern Railroad tracks and U. S. High- 
way I1, 14 miles southwest of Philadelphia, Philadelphia (T.V.A. 131-NW) 
Quadrangle. 
Discussion.—This species is suggestive of V. transversa but differs in being 
less wide and in possessing stronger costellae. Its smaller size and less deeply 
concave pedicle valves with poorly developed carina distinguish the species from 
V.ventrocarinata, The smaller size and stronger costellae distinguish this species 
from V. austrina, and the latter character serves to differentiate it from V. semi- 
carinata and V. brevicarinata. 
VALCOUREA PLANA Cooper, new species 
Plate 72, C, figures 14-21; plate 73, C, figures 15-22 
Outline semielliptical with the hinge forming the widest part, sides sloping 
medially and the anterior margin somewhat narrowly rounded. Costellae nar- 
rowly rounded and separated by interspaces wider than the costellae, about 15 
or 16 in the space of 5 mm. at the front margin of the holotype. 
