196 ' WEST COAST SHELLS 



Sella assimilis, C. B. Adams, the Threaded Seik^ 

 has a slender shell, ten millimeters in length, con- 

 sisting of ten whorls,, round which run three strong 

 spiral ridges, winding from the apex to the aperture. 

 It lives from Monterey southward to Panama. 



