SHUMARD AND SWALLOW—NEW FOSSILS. 221 
Discixna Missourtensis, Shumard. 
dinal a beak rounded at tip, not curved, dtuacod. at about 
one-third the diameter from i Pig 3 edge, its elevation 
equal to about one-third the length of the. rigs ace 
ked with fine, close strix, hich are din centric, 
nearly parabolic cu . oh Ha are aphdied 
to the front. Lower valve circular, flat, or slightly concave, 
haying a large, deep, elliptical depression, at the bottom 4 
which is an elliptical a aperture. The srligskg is marked wi 
rather strong, concentric lines of incre 
grrerins —Length of an average Spee ae 33; height, 
Found by Prof. Swallow in dark limestone of the Middle 
Coal Measures, a 
t Lexington, Missouri, along with Goniatites 
gto. 
Me Te occurs also at Charbonniere, St. Louis 
Count, Mi 
nee CONVERS, Shumard. 
y circular, ‘convex, ata 
halls 8 oy 
