ee 
ANATINIDZ. 155 
CuneAMYA, Hall and Whitfield, 1875. 
Distr.—C. Miamiensis, H. and W. (exx, 6). Silurian; Ohio. 
Thin, fragile, bivalve shells, with ventricose valves, and strong, 
prominent, incurved beaks; cardinal line straight or gently 
eurved; hinge edentulous ; valves united by an external liga- 
ment of greater or less extent, posterior to which the margins 
of the valves overlap each other to the extent of the cardinal 
line; margins of the valves inflected along the cardinal border, 
forming a narrow escutcheon posterior to the beaks, and ante- 
riorly a well-defined lunule is situated below the beaks ; adductor 
muscles, at least two, are anterior and posterior; pallial line 
simple. 
OrtTHODESMA, Hall and Whitfield, 1875. 
Disir.—O. recta, H. and W. (cxx,7).. Hudson Riv. Gr.; Ohio. 
More or less elongate, bivalve shells, having the hinge-line 
straight and generally extended posterior to the beaks, but con- 
tracted or bent beneath or anterior to them; hinge-plate appar- 
ently edentulous; valves united by an external ligament extending 
to a greater or less distauce along the posterior cardinal margin. 
Posterior muscular scar elongate-ovate, anterior scar smaller, 
both faintly marked ; pallial line simple. Shells thin, marked 
externally with irregular concentric plice. 
IniontA, Billings, 1874. 
Distr.—3 sp. Sil., Devon.; U.S. JL. sinuata, Hall. 
Shell (cast) irregularly ovate, compressed or sublenticular, one 
extremity larger than the other; beaks turned towards the larger 
end, which is therefore supposed to be anterior; a concave 
depression contmences on the umbones and extends downwards 
to the posterior ventral margin; a large subovate muscular 
impression in the upper half of the posterior extremity; close 
under the beaks in front there appears to have been a short 
escutcheon ; no teeth. 
CriarkiA, Koninck, 1878. 
Distr.— C. Myiformis, Dana. Carb.; N.S. Wales. 
Shell elongated , equivalve, gaping at its anal extr emity, rather 
thick, with orowth- lines ; ligament external; hinge thick, callous, 
with a small tooth in each valve immediately under the beak ; 
interior surface smooth; adductor and pedal impressions sep- 
arate, the first large, oval, but slightly marked, the last stronger 
and small; pallial line nearly simple, slight. 
[ Rrperrta, Sharpe, 1853. 
Distr.—Fossil, 4 sp. L. Silurian; Portugal, Canada, England. 
Shell gaping at both ends ; subovate, rounded in front, elon- 
