948 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Genus DALMANELLA Hall and Clarke, 1892 
Dalmanella Haut and CrarkeE, Pal. New York, vol. 8, pt. 1, pp. 205, 223, 1892.—Or1xk, Acta et 
Comment. Univ. Tartu, ser. A, vol. 25, No. 1, p. 14, 1933. 
Wattsella BANcrort, Mem. Manchester Lit. Phil. Soc., vol. 72, p. 55, 1928—ScHUCHERT and 
Cooper, Mem. Peabody Mus. Nat. Hist., vol. 4, pt. 1, p. 125, 1932. 
DALMANELLA COSTELLATA Cooper, new species 
Plate 158, E, figures 17-33 
Shell small for the genus, oval in outline; sides and anterior margin strongly 
rounded; anterior commissure gently sulcate; valves unequally convex, the 
brachial valve having the lesser convexity. Costellae numbering 3 to the milli- 
meter at the anterior margin; spaces between costellae marked by strong, closely 
spaced fila. 
Pedicle valve strongly convex in lateral profile with the maximum convexity 
at the middle; anterior profile strongly convex. Beak bluntly rounded; umbo 
narrowly swollen and merging into the strongly swollen median region ; anterior 
and lateral slopes steep. Interarea long, curved, gently apsacline. 
Brachial valve gently convex in lateral profile; anterior profile gently con- 
cave, the median region a shallow concavity bounded by flattened flanks. Umbo 
sulcate, the sulcus widening anteriorly to the front margin where it is broad 
and shallow. Flanks gently swollen; lateral slopes short and gentle. 
Pedicle interior with short, stout dental plates, subcordate muscle field, stout 
teeth, and thick vascula media. Brachial valve with long, narrow, and deep 
notothyrial cavity ; fulcral plates stout, obsolete in old specimens. Cardinal proc- 
ess small. Anterior adductor pair iarger than the posterior pair. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Hleldtypes Ge) u22 is ROMs 8.7 7.9 8.8 5.6 4.5 
Paratype (117359a)..... 7.5 6.8 ay 4.0 4.3 
“ GiT7356b) wh ..2 7.8 6.8 7.8 3.6 4.0 
f° (@17350c).o. 18 7.2 6.6 aE 4.1 3.9 
t (1173590d)..... 8.8 7.0 8.8 6.0 4.6 
Types.—Holotype: 117359f; figured paratypes: 117359a,e, 117360b,c; un- 
figured paratypes: 117359b-d, 117360a,d. 
Horizon and locality—Oranda formation in Virginia: Just west of the junc- 
tion of Virginia County Highways 617=910, and 777, 4 mile north of Green 
“Mount Church, Broadway (15’) Quadrangle: 0.6 mile northwest of Linville 
Station, Broadway (15’) Quadrangle; on U. S. Highway 11, 1 mile southwest 
of Strasburg, Strasburg (15’) Quadrangle. 
Discussion.—This species is characterized by its narrow hinge, elongate-oval 
form, fine costellae, and gentle sulcus. It differs from D. sculpta in its oval form 
and finer costellae. The species is abundant in some exposures of the Oranda 
formation where it occurs as impressions of the interior and exterior. The in- 
terior impressions show the great variation of the brachial structures which 
range from typical Dalmanella, with well-marked brachiophore supports at- 
