418 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 127 
MULTICOSTELLA CONVEXA Cooper, new species 
Plate 60, A, figures 1-19; plate 61, A, figures 1-6 
Shell large, semielliptical in outline, a little wider than long, with the hinge 
slightly greater than the width at the middle. Cardinal extremities approximately 
a right angle, auriculate in the young. Lateral margins nearly straight in the 
adult ; anterior margin broadly rounded. Anterior commissure faintly uniplicate 
in the adult. Surface multicostellate, costellae low, rounded, with interspaces 
equal in width to the width of the costellae; 4 to 5 costellae occupy a space of 
5 mm. at the front of a large specimen. 
Pedicle valve unevenly convex in lateral profile, the umbo moderately convex, 
the midregion flattened and the anterior third subgeniculate. Anterior profile 
broadly and gently convex. Beak and umbo narrowly swollen, but this folding 
extends only for a short distance. Umbonal slopes to the cardinal extremities 
gentle. Lateral, anterior, and midregions slightly swollen. Interarea slightly 
longer than the brachial interarea, slightly apsacline; beak pointed, incurved. 
Brachial valve unevenly convex in lateral profile, the greatest convexity located 
in the midregion. Anterior profile broadly and moderately strongly arched. Sul- 
cus shallow, narrow, poorly defined, located in the posterior half. Anteromedial 
and anterolateral portions moderately swollen. Slopes to cardinal extremities 
gentle, long. Cardinal extremities slightly deflected in direction of brachial valve. 
Interarea long, anacline. 
Pedicle interior with the muscle field confined to the posterior third; dental 
plates nearly obsolete; ovarian impressions small. Brachial valve having cardi- 
nal process with a long, slender shaft, narrow myophore; lateral or secondary 
processes strongly developed in some specimens. Median ridge short. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
ETOLGtY PO etevictas« cis sneer aus 24.4 23.7 30.8 B13 9.9 
Paratype; (110380a)) sas laers ers 22.5 21.9 27.0 28.0 9.5 
¥ CTIGOREE Ls cect © 23.0 22.0 28.3 28.5 10.4 
Types.—Holotype: 110389a; figured paratypes: 110380a,b, 110385b-d, 
110386a,b, 116986a,b; unfigured paratypes: 110380c, 110385a,e, 110386c, 
110389b-j. 
Horizon and locality—Lower Bromide formation (Mountain Lake member) 
in Oklahoma: At Rock Crossing of Hickory Creek, about center sec. 35, T. 5 S., 
R. 1 E.; Mountain Lake, east half sec. 22, T. 2 S., R. 1 W.; Carter County. 
Dam in sec. 17, T. 2 S., R. 1 W, Murray County. 
MULTICOSTELLA FASCICULATA (Butts) 
Plate 56, C, figures 26-28; plate 71, D, figures 15-20 
Dalmanella fasiculata (sic) Butts, Alabama Geol. Surv. Special Rep. 14, p. 116, pl. 26, 
figs. 3, 4, 1926. 
Nine specimens additional to the type permit a fuller description of the species 
and correct generic assignment. 
