442 EXPLANATION OF PLATES OF VOL. III. 



XXV. Patula alternata. 

 XXVI. Cumberlandiana. 



XXVI. a. strigosa. 



XXVII. Triodopsis tridentata. 



XLL Stenotrema monodon. The upper transverse line represents th<j variety 

 FRA.TERNA, the two central transverse lines the var. Leah. 



