An exposure of Pleistocene sand at Gay Head, on Marthas Vineyard, has yielded a small molluscan fauna. The 11 forms which may be positively identified are conspecific with mollusks living at the present time in the Marthas Vineyard area. The ecology of the modern species is used in an attempt to interpret the paleoecology of the Pleistocene assemblage. The situation is unusually favorable for this type of analysis and the study is used therefore, as a testing ground for the basic method of using species distribution as a paleoecological tool. Few tangible results are produced by the study, however. The failure of the analysis is due principally to the complexity of the relationships which control the environmental distribution of an organism and to the impossibility of justifying several assumptions required by the method.