PART \I CHAZYAN AND RELATED BRACHIOPODS—COOPER 4II 
slightly toward the brachial valve. Beak slightly protruding beyond posterior 
margin. Interarea strongly apsacline; pseudodeltidium narrowly convex and 
short. Muscle area with the usual form for the genus, about as long as wide; 
the diductor impressions often bounded on both sides and at the front by low 
thickenings of callus. Ovarian impressions small. 
Brachial valve flattened or gently concave in lateral profile in the posterior 
third but gently convex in the anterior two-thirds; in anterior profile broadly 
convex with the sides descending in long gentle slopes and the median region 
slightly sulcate. Umbo sulcate, the sulcus extending to about the middle as a 
narrow and fairly deep depression, but anterior to the middle it may be lost nearly 
completely or continued as a shallow but wider depression nearly to the front 
margin, although rarely attaining that end. Anterolateral areas bounding the 
sulcate region gently swollen; posterolateral slopes gentle with the region just 
anterior to the cardinal extremities slightly concave. Median elevation of the 
brachial interior extending to the middle but not strongly elevated. Cardinal 
process small, with a strong median carina. Brachial processes short. 
Measurements in mm.— 
Hinge 
Length Width width Thickness 
FTOMOE VE arate akete crelal nie eave oy steers |s) 3/8 shes 9.3 13.0 15.5 2.5 
Paratype (pedicle valve 110228e)...... 10.6 14.0 17.5 ? 
& (uOz2Ga iinet oo ess FES 12.6 15.3 2.2 
Types.—Holotype: 110228d; figured paratypes: 98179, 110228e,g; unfigured 
paratypes: 110228a-c,f. 
Horizon and locality —Upper part of the Arline formation in Virginia: Porter- 
field Quarry, 5 miles east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Discussion—This species is most similar to V. brevicarinata but differs in 
having finer costellae, a different outline, and stronger fold. Furthermore, 
V.. semicarinata is a flatter shell and has the posterior of the brachial valve con- 
cave or somewhat flattened. 
VALCOUREA STROPHOMENOIDES (Raymond) 
Plate 74, B, figures 15-25 
Plaesiomys strophomenoides RayMonp, Amer, Journ. Sci., ser. 4, vol. 20, p. 370, 1905. 
Valcourea strophomenoides RAyMonD, Ann. Carnegie Mus., vol. 7, No. 2, p. 240, pl. 35, 
figs. 15, 17, 19 (not figs. 16, 18) ; pl. 36, fig. 1, text fig. 12, rort. 
The young of Valcourea strophomenoides generally possess a wide hinge and 
acute cardinal extremities. As the shell increases in age and additions are made 
to the margins, these tend to elongate the shell and give it a more quadrate form. 
The adult is thus one in which the width slightly exceeds the length and the 
cardinal extremities are approximately a right angle or are slightly obtuse. 
The umbo of the pedicle valve is strongly carinate, but the carina is continued 
as a fold for about one-half to three-quarters the length of the valve. As a 
rule the fold is lost in the front quarter which often is bent noticeably in an an- 
teropedicad direction. The sulcus of the brachial valve is deepest at the umbo 
