GENERAL DISCUSSION 5 



TABLE I. DISTRIBUTION OF FRESH WATER SHELLS NORTH 

 OF LATITUDE 49, ACCORDING TO THE DRAINAGE 



SYSTEMS NOW EXISTING. Continued. 



Name of Species. 



a 

 < 



u 



(C 



rt 

 M 



O 



T3 

 M 

 C 



X 



u 



o 



a 



I 

 J 



Physa ampullacea , 



Physa hordacea 



Aplexa hypnorum 



Ancylusrivularis 



Ancylus parallelus 



Ancylus fragilis 



A ncylus kootaniensis 



Goniobasis plicifera 



Amnicola litnosa 



Amnicola pallida 



Amnicola emarginata 



Amnicola cincinnatiensis 



Lyogyrus granum 



Pomatiopsis lapidaria 



Fluminicola nuttalliana 



Fluminicola virens 



Valvata tricarinata 



Valvata sincera 



Valvata lewisi 



Valvata var. helicoidea 



Valvata mergella 



Valvata virens 



Campelorna decisum 



Lampsilis ventricosus 



Lampsilis luteolus 



Lampsilis borealis 



Lampsilis radiatus 



Lampsilis ligamentinus 



Lampsilis rectus 



Lampsilis ellipsiformis 



Lampsilis alatus 



Lam psil is graci lis 



Strophitus rugosus 



Anodonta beringiana 



Anodonta oregonensis 



Anodonta nuttalliana 



Anodonta wahlamatensis 



Anodonta marginata 



Anodonta impl icata 



Anodonta grandis 



Anodonta kennicotti 



Anodonta pepiniana 



Anodonta kennerleyi 



Gonidea angulata 



Anodontoides ferussacianus 



Symphynota costata 



Symphynota complanata 



Margaritana margaritifera o 



O 

 O 



o 



o 



o 



o 



o 

 o 

 o 



o 



o 

 o 



o 

 o 



o 

 o 







o 

 o 



o 

 o 



o 

 o 



o 

 o 

 o 



o 

 o 

 o 

 o 

 o 

 o 



o 



o 

 o 



o 



o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 



o 

 o 

 o 



o 

 o 



o 



o 

 o 

 o 



o 

 o 

 o 



o 

 o 

 o 

 o 

 o 

 o 



o 

 o 







o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 



o 

 o 

 o 

 o 

 o 



o 

 o 

 o 

 o 



