752 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
gently rounded; anterior margin broadly rounded. Costellae of several sizes, 
about 2 of the larger ones in a millimeter at the front margin. 
Pedicle valve with lateral profile gently convex and with the maximum con- 
vexity slightly anterior to the middle; anterior profile broadly and moderately 
convex and with long, gentle lateral slopes ; umbo gently convex; median region 
gently swollen ; interarea long, apsacline. 
Brachial valve gently concave and with the maximum concavity at about the 
middle; umbo concave; posterior slope descending moderately toward the mid- 
dle; cardinal extremities somewhat flatly concave; interarea short, hypercline. 
Measurements in mm.—Holotype, length 10.0, brachial length 8.8, surface 
length 11.5, midwidth 14.2, hinge width 15.6, thickness 2.3, height 3.4. 
Type.—Holotype: 117439. 
Horizon and locality—Benbolt formation in Virginia: + mile east of Speers 
Ferry, Clinchport (T.V.A. 188-NW) Quadrangle. 
Discussion.—This species is characterized by its low convexity and is there- 
fore directly comparable to only two other species: L. occidentals and L. pri- 
maria. From the former L. platys differs in size and ornamentation; from the 
latter it differs in being somewhat more convex and having stronger ornamen- 
tation. 
LEPTELLINA PRIMARIA Cooper, new species 
Plate 187, A, figures 1-7 
Shell large for the genus, concavo-convex but not strongly convex; cardinal 
extremities rectangular to acute; lateral margins sloping inward; anterior mar- 
gin broadly rounded. Surface marked by narrowly rounded, distant costellae, 
about 5 in the space of I mm. at the front of a valve about 7 mm. long. In ad- 
dition to costellae most of the anterior three-quarters is covered by fine con- 
centric lamellae. 
Brachial valve moderately concave and agreeing well with the convexity of 
the pedicle valve; umbo concave, extended forward as a narrow but moderately 
deep sulcus for at least half the length of the valve, not well defined in the an- 
terior portion. Posterolateral areas bounding posterior part of sulcus flattened ; 
lateral areas gently concave. Interarea short, hypercline. 
Interior: Interior of pedicle valve unknown. Brachial interior with a low 
visceral disk occupying slightly more than the posterior half; median ridge low 
and wide. Cardinalia with short, thick, divergent brachial processes. Cardinal 
process simple, intimately grown to the chilidial plates, the anchylosed struc- 
tures forming a narrow plate. Musculature not preserved. 
Measurements in mm.— 
Brachial Surface Mid- Hinge Thick- 
Length length length width width ness Height 
Eoloty pel isi See ee 10.7 9.4 12.0 14.8 16:06:27) io 3.5 
Paratype (117441b)... 69 ? 7.0 8.9 10.9 5 ? 
Types.—Holotype: 117441d; figured paratypes: 117441a-c. 
Horizon and locality —Crown Point formation in New York: Valcour Island, 
Lake Champlain, Plattsburg (15’) Quadrangle. 
