PROC. ACAD. NAT. SCI. PHlLA. 1911. 



PLATE XII. 



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« 





"v y 



9 



K» 



11 



12 



/ 



13 



14 



15 



18 



19 



20 



21 



1C> 



99 



■ 



23 



24 



* 



25 



4fe,J^ 



17 



26 



' 



fgpr ^3» 



27 



28 



29 



30 



PILSBRY AND FERRISS: MOLLUSCA OF GRAND CANYON AND 



NORTHERN ARIZONA. 



