EXPLANATION OF THE PLATES. 
NOTE. — Unless otherwise stated, the figures are of the natural size; they have been 
reversed in the process of reproduction. 
PLATE XII. 
Page. 
Palaaster giganteiis,^i\i. ?i\. 
A remarkably fine specimen, with the actinial surface exposed. 
Ravensfield Quarry, near Earley. 
