PROC. ACAD. NAT. SCI. PHILA. 191.'^. 



PLATE X. 



la 



lb 



(3 



Ic 



r^i 



\ 





2a 



Id 



2b 



1e 



7 



3a 



5a 



3b 



5b 



^ 



6a 



7a 



^i; 



4a 



4b 



6b 



7b 



PILSBRY AND FERRISS: MOLLUSCA OF THE SOUTHWESTERN STATES. 



