OF DENISON UNIVERSITY. 
67 
Sanguirbolites inarshallensis , Win. ? 
(Plate V, Fig. ii ; Plate VII, Fig. 10.) 
This shell bears some resemblance to S. transversus, Dk. (= Cypri- 
cardia rigida), but differs in the posterior margin. Shell sub-quadrate 
or sub-ellipsoidal, transversely elongate, with greatest convexity above 
the middle; hinge nearly straight and somewhat shorter than the shell, 
at its posterior termination being the greatest height of the shell ; ven- 
tral margin shorter, somewhat concave or nearly straight, rapidly 
curving anteriorly to a point above the middle of the height, where it 
intersects the short, concave antero-dorsal margin ; posterior margin 
doubly truncate, first below for two-thirds the height by a line inclined 
with the ventral about 130°, above by a shorter line making nearly the 
same angle with the cardinal line, giving the shell a nasute appearance 
behind. A prominent ridge passes from this projection toward the 
beaks and a similar one from the lower posterior angle, between which 
a decided sulcus is frequently observed, especially in large specimens. 
A less distinct sulcus extends from the middle of the lower margin to- 
wards the somewhat flattened, incurved beaks. 
The following measurements illustrate the proportions : Length 
22 mm, height ii mm, convexity of single valve 3-4 mm; L. 33 mm, 
H. 15 mm; L. 28 miu, H. 14; L. 24 mm, H, 12.5 mm; L. 40 mm; 
H. 18 mm. 
The identification as above was made at the suggestion of Prof. 
Winchell, as we were unable to harmonize the description with our 
specimens. This may be accounted for by the fact that the descrip- 
tion was drawn from rather young forms, while ours have the peculi- 
arities strongly marked. 
Free-stone of middle Waverly, Granville, O. 
San^iiinolites unioniforinis , Win, 
(Plate IX, Figs. 5, 7-9. ) 
Quitfe a number of very small shells, with rather constant charac- 
ters from the basis of this description. The interior has in no case 
