EXPLANATION OF PLATES OF VOL. V. 



449 



Fig. E. Triodopsis Rugeli. 

 Fij;. F. inflecta. 



Fig. G. Mcsodon rennsylvanica. 



Fig. K. Macrocyclis sportella. 

 Fig. L. Polygyra avara. 



Fig. 0. 



Genitalia of 

 Arionta ruficincta. 



Fig. H. Polygyra septcmvolva. 

 Fig. I. Polygyra Troostiana. 

 Fig. J. Bulimulus Dorraani. 



Dentition of 



Fig. M. Turricula terrestris. 

 Fig. N. Arionta ptychophora. 



Dentition of 

 Fig. P. A. Mormonum. 



Plate XVI. 



Central, lateral^ transition, and marginal teeth of 



Polygyra oppilata. 

 Mesodon Christyi. 

 Succinea Nuttaliana. 



H. Vitrina limpida. 



Lingual membrane greatly enlarged, with a line to show transverse row of teeth; the upper 

 margin in the figure corresponding with the posterior margin of the membrane of 



