ggo SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Pedicle valve unevenly convex in lateral profile and with the maximum con- 
vexity posterior to the middle; anterior profile broadly subcarinate, with long, 
steep sides and narrowly rounded median region; umbo narrowly convex, the 
convexity continued to the anterior margin as a narrowly rounded fold; flanks 
slightly concave. Interarea moderately long, apsacline. 
Brachial valve with gently convex lateral profile having the maximum curva- 
ture in the posterior part; anterior profile gently and broadly convex; sulcus 
shallow, originating at the umbo and expanding anteriorly to the front margin 
where it occupies about half the shell width. Flanks bounding sulcus gently 
swollen; posterolateral extremities flattened and deflected slightly toward the 
pedicle valve. Brachiophore plates widely divergent. 
Measurements in mm.—Holotype, length 6.7, brachial length 6.2, midwidth 9.1, 
hinge width 8.9, thickness 3.4. 
Type.—Holotype: 117326. 
Horizon and locality—Benbolt formation (base) in Virginia: 0.2 mile south 
of the middle fork of Moccasin Creek, 14 miles south of Hansonville, Hanson- 
ville (T.V.A. 205-SW) Quadrangle. 
Discussion —This species is characterized by its transverse form, rectangular 
outline, fine costellae, and the coarse punctae mostly radially arranged. This 
species is more transverse than any of the other known species. 
PIONODEMA MINNESOTENSIS Cooper 
Plate 154, D, figures 15-190 
Orthis (Dalmanella) subaequata WINCHELL and SCHUCHERT (not Conrad), Geol. Minnesota, 
vol. 3, pl. 33, figs. 33, 34, 1895. 
Pionodema minnesotensis Cooper, Journ. Paleont., vol. 4, No. 4, p. 379, pl. 36, fig. 14, 1930.— 
SCHUCHERT and Cooper, Mem. Peabody Mus. Nat. Hist., vol. 4, pt. 1, pl. 23, figs. 6, 10, 
14, 1932. 
This name was proposed for specimens having a wide hinge and distinctly 
formed shoulders. It is ornamented like P. subaequata. It is also a robust species 
attaining nearly as large a size as the largest known specimens of that species. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
ELOlOty Deh ons ocmis sire eres T72 15.3 20.0 16.0 10.0 
Hypotype (117327a)... 17.0 16.1 19.2 15.2 mes 
" (117327b)... 19.3 17.0 21.5 16.4 12.6 
Types——Holotype: Y.P.M. S-1356; figured hypotype: 1173272; measured 
hypotype: 117327b. 
Horizon and locality—Decorah formation (Ion member ?) in Minnesota: At 
Chatfield, Fillmore County; Minneapolis; St. Paul; and Fountain, Fillmore 
County. 
