The River Snails 



the Mississippi, but well represented (as is no other genus) on 

 the Pacific slope of the Rocky Mountains. 



The collector must search for these snails in the clear water 

 of creeks that flow down mountain slopes. The green algae are 

 their accustomed food. 



The Virginian Goniobasis (G. Virginica, Gmel.) is slender 

 and long, with about six whorls, rounded a little, and banded 

 with red near the middle and base of each. Some forms are 

 finely ridged throughout, with ten or twenty lines on the body 

 whorl. The tip is always worn off. The colour is dark brown or 

 olivaceous. Length, i to ij inches. 



Habitat. — Delaware and Schuylkill rivers. 



The Plaited River Shell (G. plicifera, Lea) has keen- 

 edged folds crossing the whorls to the very apex of its horn-like 

 spire. But for its dark complexion this river shell might be 

 mistaken for one of the ladder shells, though the latter are marine 

 mollusks and decidedly pale. Length, i inch. 



Habitat. — Oregon. 



The Sharp-Lined River Shell (G. acutifilosa, Strns.) bears 

 a double row of sharp tubercles winding up its tall spire, and 

 below these, on the body whorl are four or five plain, sharp keels 

 that very prettily crimp the thin outer lip. The tip is usually 

 missing, else the shell would be over an inch long. 



Habitat. — Eagle Lake, Cal. 



G. rubiginosa, Lea, is rusty, with spiral keels on all but 

 the smooth body whorl. 



Habitat. — Oregon. 



G. nigrina, Lea, is black, has smooth, rounded whorls, and 

 is slender. Length, about f inch. 



Habitat. — Tributaries of the Sacramento River. 



G. bulbosa, Gld., smooth, and swollen, lives in streams that 

 feed the Columbia River. 



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