EXPLANATION OF PLATE XXI. 



Trochomorpha helicinoides, H. & J., mapfnified. 



Fig. 1. Dead animal extruding from the shell. 



„ 2. Genital system. 



„ .3. Portion of radnla, showing (^entral, transitional and margina. 

 teeth. 



,, t. .Taw. 



[From drawings by the Author.] 



