318 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
NICOLELLA STRASBURGENSIS Butts 
Plate 30, B, figures 7-11 
Nicolella strasburgensis Butts, Virginia Geol. Surv. Bull. 52, pt. 2, p. 110, pl. 95, figs. 32, 33, 
1942. 
Fairly large for the genus, wider than long and with hinge narrower than the 
greatest shell width which is at or near the middle. Cardinal extremities 
rounded. Lateral margins gently rounded, anterior margin moderately rounded. 
Surface marked by strong angular costae that increase by intercalation: besides 
the primary costae, two sets of costae appearing, one near the middle and the 
other on the anterior and lateral margins. Strong, zigzag concentric growth 
lines over entire surface. 
Pedicle valve moderately convex in lateral profile and somewhat more strongly 
convex in anterior profile. Umbonal region swollen, the swollen part continued 
anteriorly nearly to the front margin to form a poorly defined fold. Slopes to 
cardinal extremities fairly steep in adults. Cardinal extremities deflected slightly. 
Interarea nearly othocline, slightly curved. Beak overhanging interarea slightly. 
Delthyrium open. Interior with short dental plates and short cordate muscle 
area. Diductor scars fairly large, adjustor scars small. Vascula media indistinct 
but typically orthoid. 
Brachial valve moderately concave with the deepest portion along the middle 
line. Umbonal region concave. Flanks bounding longitudinal concave area nearly 
flat. Interarea short hypercline. Chilidium small. 
Measurements in mm.—Lectotype, length 20.3, width 23.1, hinge width ? 
thickness 34+. 
Types.—Lectotype: 97549a; figured paratype: 97549c; figured hypotypes: 
109889a,b ; unfigured paratype: 97549b. 
Horizon and locality—Oranda formation in Virginia: Along the railroad 
tracks 4 mile east of Strasburg Junction, Strasburg (15’) Quadrangle ; 200 yards 
east of Hupp Hill, 1 mile north of Strasburg, Strasburg (15’) Quadrangle. 
Same formation in Pennsylvania: 1 mile northwest of Guilford Spring, Cham- 
bersburg (15’) Quadrangle. 
Discussion.—This species is characterized by its concavo-convex outline, the 
fine angular costae, and the strong fila and growth lamellae. It differs from 
members of the genus Cyrtonotella by its angular and coarser ornamentation and 
the less flaring dental plates. The species is rare. 
Genus CYRTONOTELLA Schuchert and Cooper, 1931 
Cyrtonotella ScHucHERT and Cooper, Amer. Journ. Sci., ser. 5, vol. 22, p. 243, 1931; Mem. 
Peabody Mus. Nat. Hist., vol. 4, pt. 1, p. 77, 1932. 
Planidorsa ScHucuHeERT and Cooper, Amer. Journ. Sci., vol. 22, p. 244, 1931; Mem. Peabody 
Mus. Nat. Hist., vol. 4, pt. 1, p. 100, 1932. 
Cyrtonotella is another of the Baltic types that appears in the lower part of 
the Middle Ordovician sequence of the Southern Appalachians. Specimens gen- 
erally are rare and scattered but the locality 4 mile southwest of Catawba, Va., 
