Baker — The MoUuscan Fauna of Western Neio York. 83 



Superfamily Holopoda. 



Family Helicidae. 

 Genus Vallonia Risso. 



71. Vallonia pulchella Miiller. 



Station 4. Pittsford (Walton) ; Cayuga (Banks). Common 

 everywhere. 



72. Vallonia costata Miiller. 



Station 21. Common and strongly ribbed. 



Genus PoLYGYRA (Say). 1818 ; Pilsbry. 1889. 

 Section Mesodon Eafinesque. 



73. POLYGYRA ALBOLABRIS Say. 



Stations 1, 5, 7, 13, 16 and 17. Rochester (Walton); 

 Cayuga (Banks). Very common. 



A form with a parietal tooth is found at Pittsford (var. 

 dentata of Walton's list). 



74. PoLYGYRA thyroides Say. 



Stations 4, 11 and 18. Rochester (Walton); Cayuga 

 (Banks). Common everywhere. 



The young of this and the preceding species are very diffi- 

 cult, if not well-nigh impossible, to separate. 



75. PoLYGYRA sayii Binney. 



Station 1. Pittsford (Walton); Cayuga (Banks). Ap- 

 parently quite rare. 



t76. PoLYGYRA dentiferum Binney. 



Section Stenotrema Rafinesque. 



77. POLYGYRA HIRSUTA Say. 



Station 7. Rochester (Walton) ; Cayuga (Banks). Com- 

 mon. 



78. PoLYGYRA MoNODON Rack. Plate X. fig. 6. 

 Stations 1, 5 and 13. Rochester (Walton); Cayuga 



(Banks). A single specimen, from the Pinnacle, has two 



