382 



ESSENTIALS OF ZOOLOGY 



b/mnoeQ 



buUmoides 



techella 



Physa 

 humeroso 



Tropicorbis 

 liebmanni 



Lymnaea . 

 stagnalis 



[Lymnaeidae) 



Physa 

 , anatina 

 ( Physidae) 



Menebus 

 dllatatus 



Lymnaea 

 palusbris 



/""^ 



Ferrissia 

 excentrica 

 (Ancylidao) 



Helisomo 



trivolvis 



lentum 



(Planorbidae) 



Fig. 148. — Some common fresh watei- pulmonate snails. 



humboldUona 

 chisosensis 



Potyqyra 

 roemen 



Bulimulus 

 dealbatus 

 li^Qbilis 



Fig. 149. — Common terrestrial snails. 



,Ruwlna 

 decollata 



