Tryon, G. W., Jr. 1873. Land and Fresh-water Shells of North America. 

 Part 4. Smithsonian Miscellaneous Collections, No. 253. 



Tryon, G. W., Jr. 18864900. Manual of Conchology. Many vols. (Con- 

 tinued by H. A. Pilsbry) . 



Utterback, W. I. 1915-16. The Naiades of Missouri. American Midland 

 Naturalist, Vol. 4, Nos. 1-10. Notre Dame, Indiana. 



Walker, B. 1918. A Synopsis of the Classification of the Fresh -water Mol- 

 lusca of North America, etc. Univ. of Mich., Museum of Zoology, Misc. 

 Pub. No. 6. Ann Arbor, Mich. 



Walker, B. 1928. The Terrestrial Shell-bearing Mollusca of Alabama. Univ. 

 of Mich., Museum of Zoology, Misc. Pub. No. 18. Ann Arbor, Mich. 



Woodward, S. P. 1880. A Manual of the Mollusca. London. 



The names of genera and species used as first choice in the section of the 

 snail key devoted to land snails coincide with the classification in Pilsbry 's 

 Monograph (1939-41). The names used as first choice in the clam key are 

 those given in Frierson's Chec\ List. The unbracketed names given as second 

 choice are accepted by many conchologists and are found in much of the litera* 

 ture. 



166 



