127 



Land and Fresh Water Shells of the State of 

 New York 



BY JAMES LEWIS, MOHAWK, N. Y. 



[Bead before this Society, July 3, 1874.] 



So far as relates to the Molluscs found witliiu its borders, the 

 State of New York may be considered as embracing portions of 

 two distinct areas, each, in a measure, characterized by a fauna of 

 its own. This is more especially true of the Molluscs found in the 

 larger rivers, but less conspicuously apparent in the Terrestrial 

 Molluscs. 



In the attempts of early writers to classify the Molluscs of the 

 State of New York a considerable number of species then not 

 known to occur within the limits of the State were tabulated as 

 "Extra Limital." More recent investigations have shoAvn that 

 many species then regarded as extra limital really occur within the 

 borders of the State. Many of the species to which this remark 

 applies are such as are known to occur in the system of drainage of 

 which the Ohio Kiver is the grand trunk. Some of these species 

 are found in the streams flowing into the great lakes in the west- 

 ern part of the State. 



In more eastern and central portions of the State occur a few 

 species which apparently belong to tlic Ohio Basin, but which have 

 by some means been colonized where found. But the larger portion 

 of the species of the waters of the eastern part of the State arc 

 such as are classed in the fauna of the "Atlantic slope." 



There are among the land shells indications of two if not of three 

 distinct faunae. The minor aquatic species also offer similar indi- 

 cations. But in a paper, the principal purpose of which is to col- 

 late facts relative to geograpliical distribution, it may not be neces- 



