850 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
elliptical outline, and the flattened posterior half of the brachial valve. It is most 
like M. cancellata in general proportions and ornamentation but differs in having 
its greatest width nearer the middle, in being less concave anteriorly and in a 
generally flatter brachial valve. 
MURINELLA SPECIOSA Cooper, new species 
Plate 228, D, figures 20-26 
Shell large, transversely semielliptical ; widest part at about the middle; sides 
rounded; anterior margin broadly rounded; surface marked by fairly strong 
alternating costellae, the larger ones separated by 1 to 3 finer ones. 
Pedicle valve moderately convex in lateral profile and with the maximum con- 
vexity near the middle; anterior profile broadly and moderately convex; um- 
bonal region gently convex; median region moderately swollen ; anterior slopes 
shorter and steeper than the lateral ones; interarea moderately long; pseudo- 
deltidium somewhat narrow, convex. 
Brachial valve unevenly convex in lateral profile, the posterior half moder- 
ately convex but the anterior half moderately concave; umbo gently concave ; 
region immediately anterior to the umbo moderately swollen to about the middle 
of the valve; around the swollen area the valve is moderately concave but the 
marginal region is turned back toward the brachial valve. 
Measurements in mm.—Holotype, length 14.0, brachial length 12.5, midwidth 
18.0, hinge width 13.7, thickness 5.2. 
Type.—Holotype: 117646. 
Horizon and locality—Lincolnshire formation (Hogskin member—Oligo- 
rhynchia zone) in Tennessee: 0.4 mile east-northeast of Red Hill, 4 miles west- 
southwest of Thorn Hill, Avondale (T.V.A. 162-SW) Quadrangle. 
Discussion.—This species is suggestive of Murinella cancellata, but it is much 
smaller and the posterior half of the brachial valve is much more convex. Muri- 
nella biconvexa is similar in size but has a brachial valve of almost the same 
convexity as that of the pedicle valve. 
MURINELLA sp. 1 
Plate 226, B, figures 3, 4 
Species represented by a single impression of the interior showing the muscle 
field to perfection. The scars of the diductors are subflabellate; the small tear- 
shaped adjustor scars appear outside the diductors. The adductor scars are small 
and located on the sides of the narrow median ridge. The posterior ends of the 
vascula media, parallel and separated only by a thin ridge, appear at the anterior 
ends of the diductors. 
Figured specimen.—117647. 
Horizon and locality.—Murfreesboro formation in Tennessee: On the east 
edge of Murfreesboro, Murfreesboro (15’) Quadrangle. 
