434 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Echinosphaerites, on Virginia Highway 74, 54 miles east of its junction with 
U. S. Highway 54 (Virginia 71) ; on Virginia Highway 71, 0.2 mile southwest 
of Bethel Church, 4 mile east of the junction with U. S. Highway 54, Hilton 
(T.V.A. 197-NW) Quadrangle; $ mile northeast of Speers Ferry; 14 miles 
southwest of Rye Cove, Clinchport (T.V.A. 188-NW) Quadrangle; 1.2 miles 
south of the middle fork of Moccasin Creek, 3 mile south of Hansonville, Han- 
sonville (T.V.A. 205-SW) Quadrangle; 0.67 mile south of Tumbez, Moll Creek 
(T.V.A. 196-SE) Quadrangle; north side of U. S. Highway 19, 13 miles south- 
east of Hansonville Post Office, Brumley (T.V.A. 205-SE) Quadrangle. 
Low in the Sevier formation in Tennessee: 4 mile northeast of Miser, Louis- 
ville (T.V.A. 138-SE) Quadrangle. 
Discussion.—This species is characterized by its very large size, its nearly flat 
pedicle valve, and brachial valve of low convexity. The species was based by 
Willard on two specimens which are immature forms. Furthermore, the speci- 
men assigned by Willard to Billings’ species Multicostella platys is actually a 
very fine large example of his C. brevis. This species is common in the Benholt 
formation in its shaly facies in southwestern Virginia and adjacent northern 
Tennessee. 
The species is similar to C. inaequistriata, but the largest specimens are larger 
than the largest of C. inaequistriata. It also differs from that species in having 
more even-sized costellae, a less strongly developed fold, and less alate cardinal 
extremities. 
CHAULISTOMELLA CRASSA Cooper, new species 
Plate 71, B, figures 5-9a 
Shell of about medium size for the genus, wider than long with the hinge 
slightly wider than the midwidth; cardinal extremities subalate; sides sloping 
medianly more or less strongly ; anterior margin broadly rounded ; anterior com- 
missure broadly uniplicate; surface multicostellate, costellae unequal in size, 
strong and wide but separated by spaces slightly narrower than the costellae; 
about 6 costellae in 5 mm. at the anterior margin. 
Pedicle valve with uneven lateral profile, the umbonal region moderately con- 
vex but the anterior two-thirds flattened to moderately concave; anterior profile 
very gently convex; umbonal region slightly swollen but without distinctly 
marked narrow fold; median region moderately concave; flanks bounding con- 
cavity moderately swollen into a broad plication separating the concave median 
region from the cardinal extremities which are deflected toward the brachial 
valve. Interarea long and strongly apsacline. Muscle field of moderate size. 
Brachial valve with uneven lateral profile, the posterior half fairly strongly 
convex but the anterior half flattened. Median region swollen; umbo gently 
swollen, slightly sulcate; sulcus indistinct or obsolete anterior to the middle; 
lateral slopes long and gentle; anterior slope long and gentle; umbonal slope 
steeper than the lateral slopes but fairly gentle. Interarea long and orthocline to 
gently apsacline. 
