PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 407 
Pedicle interior with margin thickened slightly. Muscle area small and deli- 
cate with elongate diductor impressions. Pallial trunks not impressed. Brachial 
interior with short and narrow median ridge and small, delicate cardinalia. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Rate: bayeleh gies Wem. dees Ue 11.8 12.3 16.4 ? 2.4 
Paratype (pedicle valve 110248a)..... 12.3 ? 14.6 16.8-- ? 
es (brachial valve 110248b)....  ? 12.0 15.8 20.0 ? 3.0 
Types.—Holotype: 110248c; figured paratypes: 110248a,b; unfigured para- 
types ; 110248d,e. 
Horizon and locality—Upper part of the Arline formation in Tennessee: 
North side of wagon road in glade, 4 mile southeast of Friendsville; 100 yards 
southwest of Negro Cemetery, 4 mile northeast of Friendsville, Concord (T.V.A. 
138-SW ) Quadrangle; 1,500 feet south of the mouth of Burnett Creek, Shooks 
Gap (T.V.A. 147-NE) Quadrangle. 
Discussion—This species is characterized by the shortness of the median 
carina and corresponding sulcus. Both these features are confined chiefly to the 
umbonal region and do not extend past the middle of either valve. In this re- 
spect the species differs from V’. ventrocarinata which it otherwise resembles. 
It differs from V. austrina in having a more concave pedicle valve, a brachial 
valve with a somewhat more inflated median region, and with more prominent 
diversity of costellae in the ornamentation. V’. brevicarinata differs from V. ob- 
scura, from the Lenoir formation, in having a more pronounced carina, finer 
costellae, deeper pedicle valve, and more convex brachial valve. 
VALCOUREA DECKERI Cooper, new species 
Plate 74, A, figures I-14 
Shell moderately large, wider than long with the hinge usually forming the 
widest part. Cardinal extremities varying from an acute angle in the young to 
nearly a right angle in old adults. Lateral margins varying from nearly straight 
to strongly oblique. Anterior margin broadly rounded. Surface multicostellate, 
17 or 18 costellae in a distance of 5 mm. at the front margin of the holotype. 
Scattered costellae larger than those surrounding them often present. 
Pedicle valve only slightly convex in the posterior one-quarter to one-third ; 
gently concave in the front two-thirds to three-quarters. Fold narrow, moder- 
ately strong in the umbonal region, faint but perceptible from there to the front 
margin. Lateral regions slightly concave. Cardinal extremities slightly deflected 
toward the brachial valve. Interarea strongly apsacline to catacline. Pseudo- 
deltidium narrow, long. 
Brachial valve with the maximum convexity at about the middle. Umbo 
gently concave. Sulcus narrow at the umbo, widening anteriorly and reaching 
the anterior margin; very shallow in the anterior third. Flanks bounding sulcus 
moderately swollen. Slopes to cardinal extremities gentle. 
