...Giant Clams, Tridacnidae, on Helen Reef, a Western Pacift Atoll, Frank J. Hester and Everet C. Jones 23 Color Changes in the Ovaries of Penaeid Shrimp as a Determinant of Thei Maturity, Ausbon Brown, Jr. and Daniel Patlan 27 The Bay Scallop Makes Its Bed of Seagrass. Gordon...