PART I CHAZYAN AND RELATED BRACHIOPODS—-COOPER 857 
fine costellae undulating over interrupted wrinkles that give the surface a fine 
dictyate appearance. Pedicle valve slightly convex in lateral profile; broadly and 
gently convex in anterior profile; margin narrowly geniculated toward the 
brachial valve to produce a short trail. 
Brachial valve gently convex in both profiles; anterior and lateral margin 
marked by a narrow concave rim corresponding to the anterior geniculation. 
Interior with delicate cardinalia, the cardinal process small and stout, the median 
ridge narrow and extending for about one-third the length. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
Holotype (pedicle valve)..... 11.6 ? 18.0 19.7 1.5? 
Paratype (brachial valve).... ? 12.2 17.4 15.0 ? 
Types.—Holotype: 117652; figured paratype: 117651. 
Horizon and locality.—Lebanon formation in Tennessee: On U. S. Highway 
41, 9.6 miles southeast of Murfreesboro, Rutherford County; Columbia, Maury 
County. 
Discussion.—This species is known from two specimens only, but the charac- 
teristics are strong. It is similar to B. charlottae in the type of ornamentation, 
but the wrinkling is much finer, the visceral disk region somewhat longer, and 
the geniculation more modest and producing a short trail, less steep than that of 
the Minnesota species. 
BELLIMURINA SUBQUADRATA Cooper, new species 
Plate 222, H, figures 15-18 
Shell of about average size for the genus, with the hinge forming the greatest 
shell width and the cardinal extremities slightly alate. Sides nearly straight, 
oblique ; anterior margin broadly rounded. Entire surface marked by irregular 
and zigzag wrinkles except at the hinge where 4 or 5 subparallel oblique wrinkles 
appear. Fine costellae cover the entire surface. 
Pedicle valve slightly convex in lateral and anterior profiles; umbo slightly 
convex and without wrinkles; median region slightly swollen; valve sloping 
gently from the median region to the margins ; not geniculate at the front. Muscle 
field large and subcircular in outline. 
Brachial valve gently convex in profile with the most convex part slightly 
anterior to the middle. A slight median depression extended from the umbo 
to the anterior margin. On each side of this and in the front half the valve is 
slightly swollen. 
Measurements in mm.— 
Hing 
Length Width side Thickness 
Holotype (pedicle valve) ........... 6.7 7.8 9.6 ? 
Paratype (brachial valve 117655b)... 7.1 9.9 10.6 ? 
Types.—Holotype: 117655a; figured paratypes: 117655b-d; unfigured para- 
type: 117655¢e. 
