406 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
IOLOtYpe Wore escent 13.5 12.9 17.9 19.6 3.9 
Paratype (110195a).. 14.5 14.4 20.5 23.6-++ 4.2 
‘4 (116965b) .. 17.3 16.9 22.2 22.7 7.9 
Types.—Holotype: 98177a ; figured paratypes: 98177b,d,e, 110195a, 116965a, 
b; unfigured paratypes: 98177c,f-h, 110195b. 
Horizon and locality—Whistle Creek formation in Virginia: 14 miles north- 
west of Lexington; Brushy Hills, on the road to Lexington; on U. S. High- 
way 60, 100 yards southeast of Whistle Creek, 2 miles northwest of Lexington, 
Lexington (15’) Quadrangle. 
Ellett formation in Virginia: Ellett, Lusters Gate, Blacksburg (15’) Quad- 
rangle. 
Discussion.—Valcourea austrina is characterized by a moderately strong 
median fold on the pedicle and a shallow but well-defined sulcus in the brachial 
valve, but both of these features are generally obsolete at the front of the adult 
shell. This species attains a fairly large size, almost the largest at present known. 
In this respect it resembles V. deckeri from the Tulip Creek formation in Okla- 
homa but differs in the more pronounced development of the fold and sulcus, 
the greater depth to the concave portions of the pedicle valve, and a less evenly 
convex brachial valve. The pedicle muscle area of the Whistle Creek species is 
squarer across the front than that of V. deckeri in which the diductor impressions 
are somewhat elongated. This species resembles ’. ventrocarinata in the gen- 
eral form of the valves but differs in having a less concave pedicle valve and in 
having a less well developed fold and sulcus. 
VALCOUREA BREVICARINATA Cooper, new species 
Plate 75, A, figures 1-5 
Shell of about medium size for the genus, wider than long with the hinge form- 
ing the widest part. Cardinal extremities acutely alate; sides sloping medially ; 
anterior margin somewhat narrowly rounded. Costellae narrowly rounded, of 
unequal size, about 15 in 5 mm. at the front of a valve 12 mm. long. 
Pedicle valve gently concave in lateral profile. Umbonal region marked by 
a narrow but short carina that extends indistinctly to the middle of the valve 
where it is lost in the general concavity. Median and lateral regions moderately 
concave; cardinal extremities somewhat flattened, large specimens tending to 
develop a narrowly rounded, sulcate front. Interarea short, strongly apsacline. 
Brachial valve fairly strongly convex in lateral profile with the greatest con- 
vexity in the median region; anterior profile broadly convex but somewhat nar- 
rowly rounded in the median region. Umbonal region sulcate, the sulcus short 
and narrow. Sulcus disappearing on the somewhat inflated median area and not 
extending anterior to the middle. Flanks bounding sulcus slightly convex, and 
slopes to cardinal extremities gentle. Anterior slope moderately steep but becom- 
ing less inclined posterolaterally toward the cardinal extremities. 
