PROC. ACAD. NAT. SCI. PHILA. 1910. 



PLATE I 



;~ 



•J 



l S 



I 



5 



\ 



9 M 8 



II 



* 



(5£V 4 



15 



16 



J7 



• J| ' l8 





19 



PILSBRY AND FERRISS: MOLLUSCA OF SOUTHWESTERN STATES. 



