Bull. U. S. F. C. 1897. (To face page 240.) 
Plate 22. 
YELLOW SPONGE. (Locally called “ Hardhead.”) From Florida Keys. Diameter, inches. 
YELLOW SPONGE. From Biscayne Bay. Diameter, 8 inches; weight, 3 ounces. 
This form is known as a " roller," or " rolling John,” having been detached from the bottom and moved about by the currents. 
