46 ^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, Corbiculada. 



Sphaerium sulcatum, Lam., (common). 



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



Sphaerium partumeium, Say, (Huron River). 



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



Sphaerium 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 i o 



Genera 26 



Species 85 



Gasteropoda 67 



Chonchifera 18 



BRYANT WALKER, 

 CHAS. E. BEECHER. 



UNIVERSITY OF MICHIGAN, ANN ARBOR, June 3, 1875. 



