national Petroleum Company and now at Princeton University, was also 

 a member of this expedition. A second expedition to Ecuador was made in 

 1955 when the writer was accompanied by the late Ted Dranga and Mrs. 

 A. Dranga. Amongst Panama Canal Zone personnel, the author is especially 

 indebted to the late James Zetek, former Resident Manager of Barro 

 Colorado Island Wildlife Reservation and his assistant, Mrs. A. Gomez, for 

 many courtesies; and among local naturalists and collectors the following: 

 Captain W. S. Bitler, USN, Mr. and Mrs. Lee Beil, Mr. and Mrs. H. John- 

 son, Mr. and Mrs. H. B. Haskell and Mr. Stewart Jadis. Lastly, the author 

 wishes to thank Katherine V. W. Palmer, Director of the Paleontological 

 Research Institution for much help in the past, tracing literature references 

 and under whose editorial guidance this work was published. Myra Keen's 

 comprehensive work on Panamic mollusks appeared after the major part 

 of our study had been completed; hence only occasional reference to it 

 will be found in this memoir. 



DEPOSITION OF TYPES AND FIGURED SPECIMENS 



The holotypes of the new species described in this work have been 

 deposited at the Academy of Natural Sciences in Philadelphia, and where 

 additional material is available, the paratypes of the same species will be 

 placed in other museum collections. Unless otherwise indicated, the figured 

 specimens, largely from my own collection, have been deposited at the 

 Paleontological Research Institution at Ithaca, New York. 



Coral Gables, Florida 

 July 1st, 1958. 



