NO. 30 



SMITHSONIAN EXPLORATIONS, [QI2 



59 



conditions in the narrow space between the main shore and the outer 

 beach of the off-lying keys, each of which is occupied by a peculiar 

 fauna! assemblage. 



On April 28, i<;i2, the party crossed the Gulf Stream and pro- 

 ceeded to Nassau. New Providence, where collections were made 

 of living mollusks, and a fine series of the fossil mollusk, Cerion agas- 

 sisi Dall, was obtained. 



The part\- then went to Andros Island. Mere the marine mollusks 

 proved rather disappointing, there being but few species and these, 



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l"n,. (15. — The laboratory. "White House," near Sharp Rock Point, 

 Andros Maud. Photograph by Bartsch. 



as a rule, were few in number. The land shells were far more 

 interesting, the genus Cerion in particular offering some most inter- 

 esting pri iblems. 



Andros Island is a collective term applied to a whole host of minor 

 keys that are separated by tortuous channels of varying width and 

 depth. Practically ever) key examined, no matter how small, pro- 

 vided it bore vegetation, was found to be inhabited by Cerions of the 

 C. glatis group. The shells on each key present differences sufficient 

 to enable one to distinguish them. For example, in size alone, 500 

 of those collected about Bastion Point filled a 3-pint measure, while 

 the same number fn »m the neighborho* >d of ( >ur temporary laboratory, 



