1 12 HERTLEIN AND STRONG 



author dealing with the marine mollusks taken at Malpelo and Cocos 

 Islands was published in 1932, and a report by Hanna & Hertlein on the 

 non-marine mollusks of Cocos Island appeared in 1938. Pliocene fossils 

 collected at Port San Bartolome (Turtle Bay), Lower California, during 

 a brief stop there by the expedition, were discussed in a paper by the senior 

 author in 1933. A paper by the present authors dealing with mollusks 

 collected in Panamanian waters was published in 1938, and one con- 

 cerned with fossil mollusks of Pleistocene age taken at the Galapagos 

 Islands during this expedition appeared in 1939. References to these 

 papers can be found in the bibliography accompanying the present work. 



ACKNOWLEDGMENTS 



The senior author wishes to express his appreciation to Captain G. 

 Allan Hancock for the privilege of accompanying the expedition which 

 afforded opportunity to assemble the present collection. This voyage and 

 the assembling of collections were made under most pleasant circum- 

 stances, further enhanced by the hearty cooperation of the entire crew 

 of the Velero III. Special thanks are due Dr. John S. Garth of the 

 Allan Hancock Foundation, Mr. Karl Koch and Mr. C. B. Perkins of 

 the San Diego Zoological Society, and Mr. George Stone, photographer 

 with the expedition, for their aid at various times in collecting speci- 

 mens. Dr. A. Myra Keen, Department of Geology, Stanford University, 

 aided in the identification of the species of Vermetidae and some of the 

 species of small pelecypods cited in this paper. Special acknowledgment 

 is due Dr. G. D. Hanna, Curator of the Department of Geology, Cali- 

 fornia Academy of Sciences, who prepared the photographs used to illus- 

 trate the species represented on the plate, and who also aided in the 

 identification of the species of Terebra. 



BRIEF REVIEW OF EARLIER LITERATURE 



The early mariners who reached the Galapagos Islands apparently 

 gave but little attention to the interesting mollusks which occur there. 

 Colnett (1798, p. 57), who arrived at the islands in 1793, mentioned 

 the occurrence of "... a few small wilks and winkles. A large quantity 

 of dead shells, of various kinds, were washed upon the beach; all of 

 which were familiar to me." 



Hugh Cuming, on his boat "Discoverer," collected extensively along 

 the west coast of South America and north to the Gulf of Fonseca in 

 Central America. During this work, he visited the Galapagos Islands, 



