286 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Measurements in mm.—Holotype, length 4, width 5, height 2. 
Types.—Holotype: 109795; paratype: 1097096. 
Horizon and locality.—Edinburg formation (Liberty Hall facies) in Virginia: 
1.8 miles S. 4° W. of Bethel Church, 5.9 miles east of Harrisonburg, Harrison- 
burg (15’) Quadrangle ; Effna formation: Lower part McNutt Quarry, 12 miles 
southwest of Bland, Burkes Garden (15’) Quadrangle. 
Discussion.—One specimen of this species is a silicified brachial valve show- 
ing the spines well. The species can be recognized and differentiated from other 
known species by the peculiar profile in which the greatest height of the valve is 
at the middle with the apex posterior, approximately marginal and depressed 
below the highest point. 
ACANTHOCRANIA SUBQUADRATA Cooper, new species 
Plate 26,1, figures 20-25; plate 27, B, figures 4-7 
Shell small, conical in profile, subquadrate in outline. Apex about one-third 
the length anterior to the posterior margin. Lateral and anterior margins broadly 
rounded ; posterior margin nearly straight. Lateral profile with strongly convex 
anterior slope and slightly concave and steep posterior slope. Surface marked 
by very fine spines. Interior with large posterior muscle scars elongate-elliptical 
in outline. Central scars smaller and more circular. Pedicle valve unknown. 
Measurements in mm.—The holotype (109759b) is 9.7 long, 8.8. wide, and 
2.7 high. The apex is located 3.7 anterior to the posterior margin. 
Types.—Holotype: 109759b; figured paratypes: 109759¢,d, 109793, 116836; 
unfigured paratypes: 1097592, e. 
Horizon and locality—Bromide formation (upper Mountain Lake member) in 
Oklahoma: On Oklahoma Highway 18, 1.8 miles south of Sulphur, Murray 
County. Bromide formation (Pooleville member—Lonchodomas zone) in Okla- 
homa: Rock Crossing of Hickory Creek, about center sec. 35, T. 5 S., R. 1 E, 
Criner Hills, Carter County. 
Discussion.—This species differs from A. setigera in its smaller size, much 
finer spines, and subquadrate form. It differs from A. erecta in its lower valve 
and finer spines. 
ACANTHOCRANIA sp. t 
Plate 27, F, figures 12-14 
Shell forming a low cone with apex slightly posterior to the middle; lateral 
profile with moderately long, convex anterior slope; posterior slope shorter, 
steeper, and nearly flat except for a short concave area just posterior to the beak ; 
anterior profile with nearly flat, moderately steep slopes. Surface marked by very 
fine spines. 
Measurements in mm.—116839, length 13.0, width 13.2, height 4.8. 
Figured specimen.—1 16839. 
Horizon and locality—Lebanon formation (Doleroides zone) in Tennessee: 
On U. S. Highway 70N opposite Fairview Service Station, 4 mile west of Rome, 
Smith County. 
