PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 285 
slope of the hill 4 mile east of Cedar Point School, Hilton (T.V.A. 197-NW) 
Quadrangle. 
Discussion—This species is characterized by its large size, unsymmetrical 
form in lateral view, and densely matted spines. In these respects it differs from 
all other species described herein. 
ACANTHOCRANIA GRANULOSA (N. H. Winchell) 
Crania granulosa N. H. WincuHELL, 8th Ann. Rep. Geol. Nat. Hist. Surv. Minnesota, p. 63, 
1880.—SARDESON, Minnesota Acad. Nat. Sci., Bull. 3, p. 343, 1892—-WINCHELL and 
ScuucHERrt, Geol. Minnesota, vol. 3, p. 373, pl. 29, figs. 34, 35, 1893. 
Horizon and locality——Decorah formation, Minneapolis, Minn. 
ACANTHOCRANIA OKLAHOMENSIS Cooper, new species 
Plate 27,H, figures 18-20 
Shell fairly large for the genus, subcircular in outline, conical in both profiles ; 
apex very slightly posterior to the center; lateral profile with steep, nearly flat 
anterior slope; posterior slope steeper than the preceding, fairly deeply concave 
just posterior to the beak but nearly flat posteriorly. Anterior profile with flat 
and only moderately steep slopes. Surface marked by very fine spines. 
Measurements in mm.—Holotype, length 9.7, width 10.2, height 3.7. 
Types—Holotype ; 1168374; figured paratypes: 116837b-d. 
Horizon and locality—Bromide formation (Pooleville member—bed 2) in 
Oklahoma: West of Nebo store in sec. 22, T. 2 S., R. 3 E., Murray County. 
Discussion.—This species is unlike A. subquadrata from the Bromide forma- 
tion in having a more symmetrical cone and in lacking the well-marked, triangu- 
lar posterior slope. It also appears to be a larger shell. 
ACANTHOCRANIA SETIGERA (Hall) 
Plate 25, A, figures 1-5 
Crania setigera HAtt, Descr. new species Crinoidea and other fossils, p. 12, 1866; 24th Rep. 
New York State Cab. Nat. Hist., p. 220, pl. 7, fig. 15, 1872-—-Hatt and CLarkKE, Pal. 
New York, vol. 8, pt. 1, pl. 4, H, figs. 14-16, 1892—WINCHELL and ScHuCcHERT, Geol. 
Minnesota, vol. 3, p. 372, pl. 20, figs. 32, 33, 1893.—GraBau and Suime_r, N. Amer. index 
fossils, vol. 1, p. 207, figs. 241e-f, 1907. 
Figured specimens.—24739, 247438. 
Horizon and locality.—Platteville and Decorah formations, Wisconsin and 
Minnesota. 
ACANTHOCRANIA SPINOSA Cooper, new species 
Plate 26, H, figures 18, 19 
Shell small for the genus, irregular in form, but crudely circular in outline. 
Greatest height at the middle. Apex smooth, small, located above the posterior 
margin and behind the middle of the valve, depressed below the highest point. 
Posterior slope short and steep. Surface covered by spines, which are about 
4mm. in length near the margin. 
