294 IN LOWER FLORIDA WILDS 



Pleistocene deposits of this once very shallow sea. 

 Such forms as Codakia tigerina, Oliva reticularis, 

 Marginella carnea, and others are met. They 

 inhabited the near-by Gulf Stream waters coming 

 from the south and were carried for a short dis- 

 tance to the westward to meet the Atlantic species 

 on common ground. 



There are numbers of marine mollusks of the 

 Lower Florida and West Indian region so closely 

 resembling species of the Panamic area of the 

 Pacific that only an expert can distinguish one 

 from the other. Strombus pugilis, common along 

 our shores, is very close to S. gracilior of the west 

 coast of Mexico ; our giant Fasciolaria is much like 

 the smaller F. princeps of the Panamic region; 

 Vasum muricatum of the Lower Keys is almost 

 exactly like V. cestus from western Central Am- 

 erica. Purpura patula, P. floridana, Melongena 

 melongena, Cardium isocardia, Cytherea dione, 

 Venus listen, and V. cancellata of the Atlantic side 

 are replaced by strikingly analogous species on the 

 tropical Pacific coast, and the list might be greatly 

 extended. According to Zetek, who has recently 

 catalogued the Panamic mollusks, fifteen per cent, 

 are common to both coasts and it is probable that 



