992 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
PIONODEMA SINUATA Okulitch 
Pionodema sinuata OKuLItTcH, Canadian Field-Nat., vol. 49, No. 6, p. 97, pl. 1, fig. 8, 1935. 
Type.—Peter Redpath Mus., McGill Univ., Montreal. 
Horizon and locality—Leray limestone=Chaumont in Quebec, Canada: At 
St. Vincent de Paul and Pointe Claire. 
PIONODEMA SUBAEQUATA (Conrad) 
Plate 154, E, figures 20-24; plate 155, C, figures 14-18; plate 156, A, figures 1-13; 
plate 157, D, figures 7-14 
Orthis subaequata Conran, Proc. Acad. Nat. Sci. Philadelphia, vol. 1, p. 333, 1843—HALL, 
Pal. New York, vol. 1, p. 118, pl. 32, figs. 2a-d (not e-f), 1847; Geol. Wisconsin, vol. 1, 
p. 42, figs. 1-3, 1862—Em™ons, Amer. Geology, vol. 1, pt. 2, p. 194, pl. 9, fig. 2, 1855.— 
Lestey, Geol. Surv. Pennsylvania, Rep. P4, p. 533, 1880. 
Dalmanella subaequata (Conrad) Hatt and CLARKE, Pal. New York, vol. 8, pt. 1, pp. 1094, 
207, 224, pl. 5C, figs. 6-11, 1892.—? WELLER, Geol. Surv. New Jersey, Paleont., vol. 3, 
p. 156, pl. 10, figs. 3, 4, 1903. 
Dalmanella perveta Hatt and CLARKE (not Conrad), Pal. New York, vol. 8, pt. 1, p. 224, 
pl. 5C, figs. 13, 14, 1892. 
Orthis minneapolis N. H. WINcHELL, 8th Ann. Rep. Geol. Nat. Hist. Surv. Minnesota, p. 63, 
1880.—WINCHELL and ScHUCHERT, Geol. Minnesota, vol. 3, p. 448, pl. 33, figs. 30-32, 1895. 
Pionodema subaequata (Conrad) ScCHUCHERT and Cooper, Mem. Peabody Mus. Nat. Hist., 
vol. 4, pt. I, p. 141, pl. 23, figs. 1, 5, 1932.—Coorer, Journ. Paleont., vol. 4, No. 4, p. 378, 
pl. 36, figs. 1, 3, 1930. 
Shell variable in outline and profile, large for the genus, subrectangular to 
subcircular in outline; valves subequal in depth; hinge usually narrower than 
the greatest width which is at the middle; cardinal extremities varying from 
strongly obtuse to nearly a right angle; sides varying from moderately curved 
to nearly straight ; anterior margin broadly convex; anterior commissure vary- 
ing from nearly rectimarginate to broadly but gently uniplicate. Surface costel- 
late, costellae generally crowded, unequal in size, the coarser ones concentrated 
in the median region of both valves; strongly swollen and hollow costellae nu- 
merous, scattered over the surface and concentrated in the median regions of 
both valves. 
Pedicle valve unevenly convex in lateral profile but with the maximum con- 
vexity between the beak and the middle; anterior quarter to half of the profile 
flattened ; anterior profile broadly convex with the median region elevated and 
with long lateral slopes. Beak moderately long, slightly incurved; umbo some- 
what narrowly swollen; median region full; flanks flattened to gently convex, 
moderately steep; anterior slope convex, fairly steep. Anterior portion some- 
what flattened to produce a poorly defined sulcus. 
Brachial valve with fairly evenly convex lateral profile having the deepest 
part at or near the middle; anterior profile broadly convex; umbo sulcate ; sulcus 
shallow, disappearing near the middle; median region swollen, the swelling in- 
cluding the anterior portion which forms an ill-defined fold. Lateral slopes mod- 
erately steep. 
Pedicle valve with small teeth, receding dental plates, and subflabellate muscle 
