PLATE 46, 47, 48, 49. 
rata semidrculari : nate incurvata, altera pyramidita; 
nate verticiformi subreflex^, foramine maxima. S. p. 
A petrified shell. The original an Anomia. Perforate. 
Valves convex. Hinge straight, extended, patulous, trian- 
gular, divided down the middle by a very large, perpendi- 
cular foramen, in form of an acute isosceles. The surface 
of the shell longitudinally furrowed : The furrows strong, 
their number about 28 or 30, crossed by a few distant 
wrinkles, marking, apparently, the growth of the shell. A 
deep, rounded sinus, destitute of furrows, in the larger 
valve ; answered by a convex wave on the other valve, and 
terminated by a strong curvature at the margin : Perforated 
valve pyramidal, perpendicular, gradually tapering froni 
the margin to the beak, which is somewhat reflected and 
cuspidate, and constitutes, as it were, the apex or summit 
of the pyramid : the back, or that part of the valve pro- 
ceeding from the margins, rounded : the opposite side flat, 
consisting of the hinge and foramen described above. The 
other valve semicircular, moderately convex, broad ; its 
beak prominent, pointed, and incurved over the base of 
the foramen. 
Very rare. Limestone. Casllcton. 
The structure of this Anomite is truly remarkable ; dif- 
fering from that of every other shell of the same tribe I 
have yet seen, except the next described species, and ano- 
