322 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Types.—Figured hypotypes : 99262a, 109846a, 109854a; unfigured hypotypes: 
99262b, 109846b, 109854b-e, 109857. 
Horizon and locality.—Effna formation in Virginia: At Tilson Mill, 16 miles 
northeast of Marion; McNutt Quarry, 12 miles southwest of Bland, Burkes 
Garden (15’) Quadrangle; Porterfield Quarry, 5 miles east of Saltville, Mac- 
crady (T.V.A. 218-NW) Quadrangle. 
Botetourt formation in Virginia: Opposite road intersection with Hays Creek, 
2 miles northwest of Brownsburg, Lexington (15’) Quadrangle. 
Discussion.—The ornamentation and strong convexity of this species preclude 
its assignment to Rafinesquina. Although the specimens available for study are 
not good, as they are preserved in a crystalline limestone, details of the interior 
obtained from the limestone specimens and a good silicified brachial valve indi- 
cate affinites with Cyrtonotella. The species differs from C. virginiensis and 
C. subplana in the stronger fasciculation of the costellae. 
CYRTONOTELLA MAGNA Cooper, new species 
Plate 41, C, figures 8-16; plate 41, D, figures 17-19; plate 50, A, figures 1-6 
Shell large for the genus, wider than long with the hinge forming the widest 
part; cardinal extremities acute in the young, obtuse in the adult; profile with 
gently concave brachial valve and strongly convex pedicle valve; surface multi- 
costellate, costellae elevated, narrowly rounded and separated by striae slightly 
less than the width of the costellae; 7 to 8 costellae in 5 mm. at the front margin. 
Pedicle valve strongly convex in lateral profile but with the greatest convexity 
in the posterior half; anterior profile with median region somewhat strongly 
humped and with long, moderately steep slopes to the sides; umbo and median 
region swollen, the swelling continuing to the anterior margin indistinctly ; pos- 
terolateral areas broad, flattened; umbonal slopes long and gently concave. In- 
terarea short, narrowly curved ; beak strongly incurved ; umbo protruding slightly 
posterior to the posterior margin. 
Brachial valve very slightly concave in lateral profile; umbo depressed by a 
broad sulcus which forms a prominent cavity in the median region of the valve 
but disappears toward the anterior margin; flanks bounding sulcus flattened ; 
posterolateral areas flat. Interarea short, anacline. Chilidial plates small; cardi- 
nal process a short ridge; median ridge short, extending for about one-fourth 
the length ; adductor field small ; brachiophores short and thin. 
Measurements in mm.—Holotype, length 22.4, brachial length 21.2, width 28.9, 
hinge width 27.7, thickness 6.9. 
Types.—Holotype: 116897b; figured paratypes: 116897a,c, 116898, 1168992 ; 
unfigured paratypes: 116897d; 1168g9b-e; figured specimen: 110353a. 
Horizon and locality—lLower Sevier formation in Tennessee: On the east 
side of the road 0.2 mile north-northwest of Gooseneck, Louisville (T.V.A. 
138-SE) Quadrangle; 4 mile northeast of Miser, Louisville (T.V.A. 138-SE) 
Quadrangle ; 1 mile by road northwest of Big Springs, Binfield (T.V.A. 139-NE) 
Quadrangle ; 2 miles southeast of Friendsville, Binfield (T.V.A. 139-NE) Quad- 
rangle; 1 mile south of Athens, Athens (T.V.A. 125-NE) Quadrangle. 
