The Nautilus. 



Vol. IV. DECEMBER, 1890. No. 8. 



A NEW AMERICAN PISIDIUM. 



BY EDWARu W. KOPER, REVERE, MASS. 



Pisidium Idahoense Roper. 



Shell large, sub-ovate, full, oblique, inequilateral, anterior end a 

 little longer, margin well rounded ; beaks scarcely raised, not promi- 

 nent, approximate at apex ; lines of growth delicate ; epidermis 

 glossy, light yellow, some specimens with brownish zones in center 

 of valves, not extending to the edges, leaving a broad marginal bor- 

 der ; interior bluish white ; hinge margin curved, narrow ; cardinal 

 teeth very small, lateral teeth long and slender. 



Length, 0-35 ; height, 0-31 ; breadth, 0-21 inches. 



This shell is quite different from Plsidinm Virgmieum, the only 

 American species of equal size. P. Virginicum has the beaks fuller, 

 more elevated and nearer the posterior end ; the hinge margin and 

 teeth broad and heavy ; the shell more elongated and in every way 

 more solid. 



About forty specimens of P. Idahoense were collected by ^Mr. 

 Henry Hemphill in a muddy slough near Old Mission, in northern 

 Idaho. He did not find it in other localities. 



NOTES ON FLORIDA BTJLIMULI. 



BY G. W. W'EBSTER, LAKE HELEN, FLA. 



In the Nov. Nautilus Mr Chas. T. Simpson gives some notes on 

 Bulimulus Dormant which I have read with interest. As to the 



