TAMPA BAY 



82 30 W. 



FiouBE 2. — Ecol(^cal zones in Hillsborough Bay, Fla., based on the comparative diversity of moUusks — healtliy 

 zone (uushaded) ; marginal zone ( hatching) ; unhealthy zone (cross hatching) — August and September 1963. 



MOLLUSKS AND BENTHIC ENVIRONMENTS IN HILLSBOROUGH BAT, FLA. 



199 



