PLATE 43. 
Page 
248 
Figs.. 1-8. SpIRIFERA ALTA.. 
1-3. Casts of dorsal valves, showing the extent of area, dental cavities, and muscular impres¬ 
sion. 
4, 5. Two views of a cast of a ventral valve, showing the muscular impression and sinuate out¬ 
line of the valve in front. 
«, 8. Cardinal views of a ventral valve taken from gutta-percha casts, from natural moulds, 
showing a partial closing of the triangular foramen by shelly matter, which is not the 
true deltidial plate. 
7. Cardinal view of a cast of a ventral valve, showing the cavities left by the removal of the den¬ 
tal lamellae, and the concave impression of the inner surface of the shelly plate, which 
partially closed the foramen. 
