^6 Appendix. 



Unio pressus, Lea, (rare). 

 Unio novi-eboraci, Lea, (abundant). 

 Margaritana marginata, Say, (abundant). 

 Margaritana deltoidea. Lea, (not abundant). 

 Anodonta edentula, Say, (common). 



(Section, Siphonida.) — Family, Corbiculadce. 



Sphceriura sulcatum. Lam., (common). 



Sphasrium occidentale, Prime, (Northeast swamp, common). 



Sphasrium partumeium. Say, (Huron River). 



Spliaerium striatinum. Lam., (Huron River, common). 



Sphferium secure, Prime, (Northeast swamp, on the River). 



Pisidium virginicum, Bourg., (River, common). 



Pisidium variabile, Prime, (Huron River). 



Pisidium compressum. Prime, (Huron River). 



Pisidium abditum, Hald., (Huron River). 



SUMMARY. 



Classes 2 



Orders ... 2 



Families 10 



Genera 26 



Species 85 



Gasteropoda 67 



Chonchifera 18 



BRYANT WALKER, 

 CHAS. E. BEECHER. 



Univeksitv of Michigan, Ann Arbok, June 3, 187.5. 



