1 18 HERTLEIN AND STRONG 



from the Galapagos Islands and 29, at the present time, are not known 

 to occur elsewhere. Forty-five species in this collection are recorded in 

 the Recent fauna of the Galapagos Islands for the first time in this paper 

 or in other publications by the present authors. 



Five of the 164 species are wide-ranging cosmopolitan forms occurring 

 in warm marine waters in widely separated regions. The species in 

 the present collection represent only a portion of the total molluscan 

 fauna of the Galapagos Islands, but the predominantly Panamic charac- 

 ter is revealed by the occurrence of 130 of these species in the waters of 

 the Panamic province, with 100 occurring as far north as the Gulf of 

 California. In contrast to this, only ten species occur in the waters of 

 southern California, and an equal number have been recorded as oc- 

 curring in the cooler Peruvian waters south of Punta Aguja. Omitting 

 the cosmopolitan forms, we have only eight species ranging north or 

 south of tropical or subtropical west American waters. Many of the 

 species in the present collection are known to occur also as fossils of 

 Pleistocene age in the archipelago. The comparatively short and shal- 

 low expanses of waters separating the islands, as well as the strong local 

 currents, furnish favorable conditions for the distribution of marine 

 species of mollusks. No definite conclusions concerning distribution of 

 species among the various islands are drawn from a study of the present 

 limited collection. 



