308 The American Geologist. November, 1893 
Cardinal area less than tin- width of the shell, triangular and 
high, like Cyrtina. Foramen high, triangular. Beak of the 
ventral valve slightly incurved. The outline of the shell is 
semicircular, the lateral extremities being rounded. Entire 
surface covered by the bases of small needle-like spines. 
Length of shell .."•.,. width ..;.. hight .,'., of an inch. 
One of the rarest fossils in the Louisiana (Lithographic i limestone 
at Louisiana, Mo. The collection contains two specimens. 
Cyrtina iHirlingioiiensis (nov. sp.). 
(Plate xiv, tig. 15. Cardinal view, natural size. Fig. 16. Dorsal 
valve, natural size. Fig. 17. Profile of a larger individual, natural 
6ize.) 
The length and width of this shell about equal. Either 
side of the mesial fold on the dorsal valve there are two pli- 
cations, the first being little less strong than the mesial fold 
itself. Either side of the sinus on the ventral valve are two 
strong and one almost obsolete plications. Sinus of moder- 
ate depth and well defined. Cardinal area less than the 
width of the shell, giving a rounded shape to the extremities 
of the dorsal valve. Area triangular, hight a little less than 
the width. Foramen long, triangular, uncovered in the half 
dozen specimens examined. Beak of ventral valve slightly 
incurved in all the specimens. A few distinct lines of growth 
cross the plications of both valves. The few strong cos tee, 
rounded lateral extremities and incurved beak will serve to 
identify this handsome little shell. The type specimen has a 
length and width of ^ and thickness of j 5 6 of an inch. 
From the lower Burlington limestone. Louisiana, Mo. The collec- 
tion contains six specimens. 
Stroplialosia beecheri (nov. sp.). 
(Plate xiv, fig. 18. Ventral valve, natural size. Fig. 10. Cardinal 
area, natural size.) 
Shell subcircular. Ventral valve convex and highest about 
the middle. Without striations or plications. Distinct lines 
of growth cross the valve. Irregularly distributed spine 
bases. Spines moderately strong and apparently long. Car- 
dinal area less t ha n the width of the shell. Deltidium distinct 
but small, triangular, twisted to conform to the twisted beak 
of the ventral valve. Beak not incurved. To a small flat- 
tened area for attachment, on the ventral valve near the beak, 
is due probably the twisted character of the latter. Qnfortu- 
