108 
Aug. F. Foerste 
Strophomena sulcata is most abundant in the Liberty and White- 
water, especially near the top of the Whitewater. 
Owing to the absence of Strophomena sulcata from the Rich- 
mond of the Mississippi Valley, with the possible exception of a 
limited area in southern Illinois, it is another species, suggesting 
perhaps an indigenous origin in some basin including Ohio and 
Indiana. 
Strophomena cardinalis, Whitfield 
The chief characteristics of Strophomena cardinalis it shares 
with Strophomena wisconsinensis, described from the same hori- 
zon and locality. These characteristics are the high hinge-area, 
nearly parallel with the flattened posterior part of the brachial 
valve, the relatively large convex area anterior to the beak, and 
the rather strong downward deflection of the brachial valve 
anterior to the flattened area. The reversal in the curvature of 
the pedicel valve from convex to concave is only slight, and takes 
place so near the anterior margin as to suggest that the types of 
this species were immature shells. Opposed to this view is the 
great height of the hinge-area in specimens of comparatively small 
size. In the figured specimen, the width of the shell is 22 mm.; 
the length 17 mm. ; and the height of the hinge-area, nearly 4 mm. 
In general, the height of the hinge-area is nearly one-fifth of the 
length of the shell. In form, the area is conspicuously triangular. 
Richmond group, at Delafield, Wisconsin. 
It is a suspicious circumstance that Strophomena cardinalis 
does not reappear in the collections made, since this species was 
described, at Delafield, and at other localities containing strata 
belonging to the same horizon. 
Strophomena wisconsinensis, Whitfield 
{Plate VII, Figs. 1 A, B, C; Plate IX, Figs. 5 A, B, C) 
The types were obtained from the Richmond beds at Dela- 
field, Wisconsin. Their most characteristic feature is their 
great convexity. The brachial valve is highly arcuate and gib- 
bous near the middle, the greatest convexity being at the middle 
Geology of Wisconsm, vol. iv, 1882, p. 261, Plate XII, Figs. 9, 10. 
Geology of Wisconsin, vol, iv, p. 263, 1880. 
