PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 505 
medially. Median sulcus originating at the beak and deepening anteriorly, shal- 
low and very broadly U-shaped in section. Flanks bounding sulcus slightly swol- 
len and with gentle slopes to the margins. Posterolateral slopes to the cardinal 
extremities are the steepest slopes. Anteriorly the sulcus produces a short, 
bluntly pointed tongue. Interarea short. 
Pedicle valve interior with small teeth having small but deep fossettes. Dental 
plates short and flaring. Delthyrium wide but usually more or less narrowed 
by the growth of lateral (deltidial?) plates. Delthyrial cavity deep; muscle area 
somewhat heart shaped and extending a short distance anterior to the ends of 
the dental plates; a slight callosity at the anterior margin of the muscle field. 
Vascula media diverging widely from the diductor scars. 
Brachial valve interior with a short, narrow but deep notothyrial cavity formed 
by the sides of the brachiophores and their supporting plates. Cardinal process 
a more or less well developed simple ridge. Brachiophores long and slender, 
bounding deep sockets defined by small fulcral plates. Brachiophores supported 
by short plates uniting with the floor of the notothyrial cavity and the median 
ridge. Anterior adductor impressions larger than the posterior pair and sepa- 
rated by a low median ridge that extends to the middle of the valve. 
Measurements in mm.— 
Hinge 
Length Width width Thickness 
RAGUSA eh aac act mcihaue sce cathe 7.6 8.5 5.6 4.5 
PatAyDe: (LDEGOLE) oes sae ac es ce sles 6.4 7.5 5.5 3.7 
it (pedicle valve 111802m)... 8.5 0.4 6.7 3.6 
7 (brachial valve 111802s)... 8.0 10.9 7.5 1.5 
Types.—Holotype: 111802c; figured paratypes: 111802d,k,l,r-u; unfigured 
paratypes: 111802a,b,e-j,m-q. 
Horizon and locality—Effna-Rich Valley formations in Virginia: At the Por- 
terfield Quarry, 5 miles east of Saltville, Maccrady (T.V.A. 218-NW) Quad- 
rangle; Botetourt formation in Virginia: 2 miles northwest of Brownsburg, 
Lexington (15’) Quadrangle. 
Discussion.—This is the smallest of the three species herein described. It 
is totally unlike S. kayi in size, ornamentation, and the moderately strong sulca- 
tion of the anterior commissure. It differs from S. virginiensis in being smaller 
and less robust, in having a more convex and subcarinate pedicle valve and finer 
costellae. 
SCAPHORTHIS VIRGINIENSIS Cooper, new species 
Plate 55, A, figures I-11 
Corineorthis sp. Cooper and Cooper, Bull. Geol. Soc. Amer., vol. 57, p. 113, pl. 3, fig. 15, 1946. 
Shell fairly large, intermediate in size between S. kayi and S. perplexa; sub- 
circular in outline with well-rounded sides and anterior margin; anterior com- 
missure rectimarginate ; surface multicostellate, 2 to 3 narrowly rounded costellae 
in I mm at the front margin of a large adult. 
Pedicle valve moderately convex in lateral profile with the greatest convexity 
