782 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
tellae are not arranged in groups of several fine ones alternating with coarser 
ones as in the Wolfe Island species. 
SOWERBYELLA INDISTINCTA Cooper, new species 
Plate 202, D, figures 24-26 
The specimens on which this species is based are smaller than Sowerbyella 
compacta from the Benbolt formation in Virginia and Tennessee and have nearly 
the same shape but differ in ornamentation and size. These two species are 
very close, but despite their similarity constant differences between the two 
occur that are sufficient to distinguish them. In external form the Oklahoma 
shell has more oblique or sloping lateral margins and somewhat more acute 
cardinal extremities. The Appalachian species attains a greater size. The con- 
tours of the two species differ slightly, the Oklahoma form having in general a 
somewhat more concave brachial valve. In ornamentation the eastern species 
has less numerous costellae, about 120 as compared with about 140 in the Okla- 
homa form. Furthermore, no crescentic spines were observed on the latter, 
although concentric fila are easy to see. 
Inside the valves the Oklahoma shell seems to be less thickened in both valves 
when compared with specimens of similar size from the Appalachians. The 
brachial valve of S. compacta has a much wider and more greatly thickened 
periphery. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Holotype (pedicle valve) ........... 6.7 ? 9.4 11.4 ? 
Paratype ( “ sage LIGAOSD) 5. «wag gee ‘3 10.1 10.4 ? 
oy es Siw’ It74Osa)N.. 6H ? 10.0 11.7 (4 
‘ (Oa% caw gegaggae) 2. 7G ? 10.9 II.0 ? 
4 (brachial valve 117493c)... ? 6.7 10.3 12.0 r 
+4 (a Raho ok BAO D5 wor AP 6.4 9.8 ? ? 
Types.—Holotype: 117493a; figured paratypes: 117493b,c, unfigured para- 
types: 117493a’, a”, a”. 
Horizon and locality—Bromide formation (Mountain Lake member) in Car- 
ter County, Okla.: About the middle of sec. 33, T. 2 S., R. 2 E., 2 miles north- 
east of Springer; SE1 sec. 32, T. 2 S., R. 2 E., 3 miles north-northeast of 
Springer. 
SOWERBYELLA LEBANONENSIS Bassler 
Plate 201, B, figures 14-25 
Sowerbyella lebanonensis BASSLER, Tennessee Div. Geol., Bull. 38, p. 192, pl. 5, figs. 7, 8, 
1932 (nomen nudum) ; Journ. Washington Acad. Sci., vol. 25, No. 9, p. 406, 1935. 
About medium size for the genus, wider than long with the length slightly 
less than two-thirds the width. Outline subrectangular; lateral margins nearly 
straight, sloping gently toward the middle; anterior margin very broadly rounded 
to truncate or, in some specimens, slightly emarginate. Cardinal extremities 
