634 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
ROSTRICELLULA COLEI Cooper, new species 
Plate 138, C, figures 10-24 
Shell large for the genus, wider than long with the greatest width at or near 
the middle; sides rounded; anterior margin gently convex. Apical angle 105°. 
Sulcus marked by 3 to 5 costae, fold by 4 to 6, and the flanks by g to Io. 
Pedicle valve moderately convex in lateral profile with the most curvature at 
the umbo; anterior profile gently concave in the median region. Sulcus originat- 
ing about 7 mm. anterior to the beak. Sulcus narrow and moderately deep, form- 
ing somewhat less than half the width. Tongue moderately long and narrow, 
somewhat pointed. Flanks flattened, moderately steep. 
Brachial valve deeper than the pedicle valve, fairly strongly convex in lateral 
profile ; anterior profile varying from moderately to strongly arched. Fold origi- 
nating just posterior to the middle, low posteriorly but fairly strongly elevated 
anteriorly ; fold generally narrow and composed of a varying number of costae; 
median costae of fold often more prominent than lateral ones which may be 
located on sides of fold. Flanks inflated and rounded, steep. 
Measurements in mm.— 
Brachial 
Length length Width Thickness 
Flolotype urns eae. Gide ete 14.4 12.7 15.9 12.6 
Paratype - i( TE72IOA) «50 tya'nd ey 13.6 12.3 16.0 10.0 
CTEZATODS soe se alias 15.0 13.8 16.4 11.7 
os CUE 7 ZEON). cl oc hale 16.2 14.4 17.9 13.5 
s (iE7arGeE) 14). 7.94 16.7 15.1 18.8 15.1 
‘ (1EG2EGE) ed cece efit 14.0 Tay 15.0 117, 
Types.—Holotype: 117216d; figured paratypes: 117216a,e; unfigured para- 
types: 117216b,c,f. 
Horizon and locality—Decorah formation (upper part of Ion member) in 
Goodhue County, Minn.: From a road cut on the county road 1.1 miles east of 
U. S. Highway 52 in the south edge of Cannon Falls; Kenyon. On U. S. High- 
way 52, I mile south of Fountain, Fillmore County. 
Same formation in Iowa: West of Decorah, Winneshiek County. 
Discussion.—Rostricellula colei can be recognized by its large size and swollen 
valves. It thus contrasts strongly with Rhynchotrema wisconsinense with which 
it occurs. It is further distinguished by a fairly narrow and moderately well ele- 
vated fold for such a large shell. It resembles R. minnesotensis in its robust form 
but has a narrow fold and more tumid valves besides being a much larger species. 
ROSTRICELLULA COMPRESSA Cooper, new species 
Plate 133, B, figure 12; plate 134, A, figures 1-18 
Shell of about medium size for the genus, triangular in outline with the great- 
est width located near the anterior margin. Beak acute, sides nearly straight to 
the anterolateral extremities where they are narrowly rounded; anterior margin 
abruptly truncated. Costae numbering 15 to 17, 3 or 4 on the fold, 2 on the 
flanks and 4 or 5 on the flattened slope between the flanks and the margins; 2 
