PARTE CHAZYAN AND RELATED BRACHIOPODS—COOPER 703 
primary costellae on each side of the median one. Costellae of intermediate size 
intercalated in 2 generations as the shell grows so that an adult has about 8 
of the primary and intermediate costellae in a space of 5 mm. at the front margin. 
Spaces between larger costellae occupied by about 4 very fine costellae that are 
cancellated by crowded concentric fila. Oblique wrinkles, often of considerable 
length, mark the shell just anterior to the posterior margin. 
Pedicle valve nearly flat in lateral profile ; very slightly convex in the posterior 
half but flattened in the anterior portion. Umbo narrow, slightly swollen; beak 
small and protruding slightly posterior to the posterior margin. Anterolateral 
region flanking depressed anterior part thrown into a slight broad fold. Cardinal 
extremities somewhat flattened. Interarea short and flat; apsacline to nearly 
procline ; pseudodeltidium narrow and strongly convex. 
Brachial valve only partially known from the exterior. Umbonal region con- 
cave. In order to fit the interior of the pedicle valve the brachial valve must be 
slightly convex in the anterior region. 
Interior of pedicle valve with a moderately deep delthyrial cavity well filled 
at the posterior by callus. Valve well thickened just inside the periphery, this 
thickened portion of the interior giving the resupinate profile to the species. 
Muscle field large, occupying most of the visceral region. Adjustors located at 
the base of the dental plates as usual; diductor scars long and slender, generally 
with a low ridge running the length of the middle of the scar. Adductor impres- 
sions large. Pallial sinuses deeply impressed. Teeth double; dental plates stout, 
giving off ridges that bound the exterior of the muscle field. 
Brachial valve with cardinal process typical of the genus. 
Measurements in mm.— 
Hinge 
Length Midwidth width Thickness 
Holotype Hi PO, ROU 8.1 11.0 15.4 ? 
Paratype. (111080b) fais. ; dese ceeites 8.5 12.8 15.8 ? 
7 CRP HOROET «flier aiers, «esis 8.0 11.6 13.9 ? 
; (Cac 2 a ree eee 7.9 10.8 12.1 ? 
Types.—Holotype : 111080a ; figured paratypes: 111080b-f, 111084, 111085a,b; 
unfigured paratype: 111080g. 
Horizon and locality.—Botetourt formation in Virginia: 4 mile southwest of 
Catawba at the junction of Virginia Highways 311 and 114, Salem (15’) Quad- 
rangle. 
Discussion —This species may be recognized by its great width, well-developed 
cardinal angles, beautiful surface ornamentation, and short interarea on the 
pedicle valve. The species can be distinguished from P. subtransversa which it 
most nearly resembles by its smaller size, less numerous large costellae, and 
nearly flat pedicle valve. The greater proportional length of P. superba will dis- 
tinguish that species. 
Palaeostrophomena angulata occurs in countless numbers at its type locality, 
yet not a single good brachial valve was obtained. By far the majority of speci- 
mens are isolated pedicle valves, but specimens with both valves in contact do 
