REPORTS ON THE COLLECTIONS OBTAINED BY ALLAN HANCOCK PACIFIC EXPEDITIONS OF 

 VELERO III OFF THE COAST OF MEXICO, CENTRAL AMERICA, SOUTH AMERICA, AND GALA- 

 PAGOS ISLANDS IN 1932, IN 1933, IN 1934, IN 1935, in 1936, in 1937, and in 1938. 



LAND AND BRACKISH WATER MOLLUSCA 



OF COCOS ISLAND 



By G. DALLAS HANNA and LEO GEORGE HERTLEIN 



