• Generally applicable to North America.
• Great Lakes / Canadian Atlantic - All waters draining into the Atlantic through the St. Lawrence River and north.
• Northern Atlantic - All waters draining into the Atlantic from the Susquehanna River north to (but not including) the St. Lawrence River.
• Southern Atlantic - Waters draining into the Atlantic from the Suwannee River, through peninsular Florida, up to (but not including) the Susquehanna River.
• Eastern Gulf - Waters draining into the Gulf of Mexico between the Mississippi River and the Suwannee River.
• Western Gulf - Waters draining into the Gulf of Mexico from the Rio Grande (U.S. side only) west to (but not including) the Mississippi River.
• Eastern Mississippi - Waters draining into the Mississippi River from the East.
• Western Mississippi - Waters draining into the Mississippi River from the West.
• Pacific - American waters west of the continental divide, north of Mexico.

North America Generally

 Brown, K. (1991) Gastropoda. In Ecology and Classification of North American Freshwater Invertebrates, ed. J. Thorp & A. Covich, pp. 285-314. New York: Academic Press

 Burch, J. (1979) Genera and subgenera of Recent freshwater gastropods of North America (North of Mexico). Malacological Review, 12, 97-100

 Burch, J. (1982) North American freshwater snails: Identification keys, generic synonymy, supplemental notes, glossary, references, index. Walkerana, 4, 1-365

 Burch, J. (1988) North American freshwater snails: Introduction, systematics, nomenclature, identification, morphology, habitats, distribution. Walkerana, 2(6), 1-80

 Burch, J. (1989) North American Freshwater Snails. Hamburg, MI: Malacological Publications

 Burch, J. & Tottenham, J. (1980) North American freshwater snails: Species list, ranges, and illustrations. Walkerana, 3, 1-215

 Clench, W. (1959) Mollusca. In Fresh Water Biology, 2nd Edition, ed. W. Edmondson, pp. 1117-60. New York: John Wiley & Sons

 Henderson, J. (1935) Fossil non-marine Mollusca of North America. Geological Society of America Special Paper, 3, 1-313.

 Hershler, R. (2001) Systematics of the North and Central American aquatic snail genus Tryonia (Rissooidea: Hydrobiidae).  Smithsonian Contrib. Zool., 612, 1 - 53.

 Pennak, R. (1989) Fresh-Water Invertebrates of the United States, Third Edition. New York: John Wiley & Sons.

 Smith, D. G. (2001) Pennak's Freshwater Invertebrates of the United States: Porifera to Crustacea, Fourth Edition.  New York: John Wiley & Sons.

 Smith, D. G.  (2000)  Notes on the taxonomy of introduced Bellamya (Gastropoda: Viviparidae) species in northeastern North America. Nautilus, 114: 31-37.

 Taylor, D.W.  2003.  Introduction to Physidae (Gastropoda : Hygrophila); biogeography, classification, morphology.   Revista de Biología Tropical 51(suppl. 1):1-287.

 Turgeon, D., and 15 other authors. (1998) Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks. Special Publication No. 20, American Fisheries Society

 Walker, B. (1918) A Synopsis of the Classification of the Freshwater Mollusca of North America, North of Mexico. Misc. Pubs., no. 6. Ann Arbor: University of Michigan Press
 

Great Lakes / Canadian Atlantic

 Baker, F. (1902) The Mollusca of the Chicago area.  Part 2, The Gastropoda. Chicago Acad. Sci. Natl. Hist. Survey, 3, 131-410

 Baker, F. (1906) A catalogue of the Mollusca of Illinois. Bull. Ill. State Lab. Nat. Hist., 7, 53-136

 Baker, F. (1919) Fresh Water Mollusca from Colorado and Alberta. Bull. Am. Mus. Nat. Hist., 41, 527-39

 Baker, F. (1928) Freshwater Mollusca of Wisconsin, Part I, Gastropoda. Bull. Wisc. Geol. Natur. Hist. Survey, vol. 70. Madison: University of Wisconsin Press

 Baker, F. (1935) Land and freshwater Mollusca from North Star Lake and vicinity, Itasca County, Minnesota. Am. Midl. Natur., 16, 257-74

 Berry, E. (1943) The Amnicolidae of Michigan: Distribution, ecology, and taxonomy. Misc. Publ. Mus. Zool. Univ. Mich., 57, 1-68

 Brooks, S. (1936) The land and freshwater Mollusca of Newfoundland. Ann. Carnegie Mus., 25, 83-108

 Brooks, S. & Brooks, B. (1940) Geographical distribution of the Recent Mollusca of Newfoundland. Ann. Carnegie Mus., 28, 53-75

 Burch, J. & Y. Jung (1992)  Freshwater snails of the University of Michigan Biological Station area.  Walkerana, 6, 1-218

 Clarke, A. (1973) The freshwater molluscs of the Canadian Interior Basin. Malacologia, 13, 1-509

 Clarke, A. (1981) The Freshwater Mollusks of Canada. Ottawa: The National Museums of Canada

 Dawley, C. (1947) Distribution of aquatic mollusks in Minnesota. Amer. Midl. Natur., 38, 671-97

 Emerson, W. & Jacobson, M. (1976) Guide to Shells, Land, Freshwater, and Marine, from Nova Scotia to Florida. New York: Alfred A. Knopf

 Goodrich, C. (1932) The Mollusca of Michigan. Handbook Series, no. 5. Ann Arbor: Univ. Mich. Mus. Zool.

 Goodrich, C. (1939a) Pleuroceridae of the St. Lawrence River Basin. Occas. Pprs. Mus. Zool. Univ. Mich., 404, 1-4

 Goodrich, C. & van der Schalie, H. (1939) Aquatic mollusks of the upper peninsula of Michigan. Misc. Publ. Mus. Zool. Univ. Mich., 43, 7-33

 Goodrich, C. & van der Schalie, H. (1944) A revision of the Mollusca of Indiana. Am. Midl. Natur., 32, 257-326.

Jass, J.P. 2004.  Distributions of gastropods in Wisconsin.  Milwaukee Public Museum Contributions in Biology and Geology 99:1-28.

Jokinen, E.H.  2005.  Pond molluscs of Indiana Dunes National Lakeshore: Then and now.  American Malacological Bulletin 20(1-2):1-9.

 LaRocque, A. (1953) Catalogue of the Recent Mollusca of Canada. Nat. Mus. Can. Bull., 129, 1-406

 LaRocque, A. (1959) Checklist of Ohio Pleistocene and living Mollusca. Sterkiana, 1, 23-49

 LaRocque, A. (1961a) Checklist of New Brunswick non-marine Mollusca. Sterkiana, 3, 40-2

 LaRocque, A. (1961b) Checklist of Newfoundland non-marine Mollusca. Sterkiana, 3, 43-8

 LaRocque, A. (1962) Checklist of the non-marine Mollusca of Quebec. Sterkiana, 7, 23-44

 LaRocque, A. (1968) Pleistocene mollusca of Ohio. Ohio Geol. Survey Bull., 62, 357-553

 Mackie, G., White, D. & Zdeba, T. (1980) A Guide to the Freshwater Mollusks of the Laurentian Great Lakes, with Special Emphasis on the Genus Pisidium. Duluth, MN: U.S. Environmental Protection Agency.

 Martin, S. M. (1999) Freshwater snails (Mollusca: Gastropoda) of Maine.  Northeastern Naturalist 6: 39-88.

 McKillop, B. (1996) Geographic and environmental distribution of freshwater gastropods in Manitoba, Canada. Manitoba Mus. Man & Nat. Occas. Series, 1, 1-37

 Robertson, I. & Blakeslee, C. (1948) The Mollusca of the Niagra Frontier region. Bull. Buffalo Soc. Nat. Sci., 19, 1-191

 Te, G. (1975) Michigan Physidae, with systematic notes on Physella and Physodon (Basommatophora: Pulmonata). Malac. Rev., 8, 7-30

 Winslow, M. (1926) A revised check list of Michigan Mollusca. Occas. Pprs. Mus. Zool. Univ. Mich., 181, 1-28
 

Northern Atlantic

 Clench, W. & Russell, H. (1940) Freshwater shells of New Hampshire. Nautilus, 54, 52-3

 Emerson, W. & Jacobson, M. (1976) Guide to Shells, Land, Freshwater, and Marine, from Nova Scotia to Florida. New York: Alfred A. Knopf

 Goodrich, C. (1942a) The Pleuroceridae of the Atlantic coastal plain. Occas. Pprs. Mus. Zool. Univ. Mich., 456, 1-6

Harman, W. (1982)  Pictorial keys to the aquatic mollusks of the upper Susquehanna.  Occas. Pprs. Biol. Field Sta. State Univ. New York at Oneonta  9, 1-13.

 Harman, W. (1998) The molluscan community of Oneida Lake, New York.  J. Freshw. Ecol. 13: 207 - 211.

 Harman, W. & Berg, C. (1971) The freshwater snails of central New York with illustrated keys to the genera and species. Search: Cornell Univ. Ag. Exp. Sta., 1, 1-68

 Jacobson, M. & Emerson, W. (1971) Shells from Cape Cod to Cape May. New York: Dover

 Jokinen, E. (1983) The Freshwater Snails of Connecticut. Hartford, Connecticut: State Geol. Nat. Hist. Survey Bull. 109. 83 p

 Jokinen, E. (1992) The freshwater snails (Mollusca: Gastropoda) of New York State. New York State Museum Bulletin, 482, 1-112

 Martin, S. M. (1999) Freshwater snails (Mollusca: Gastropoda) of Maine.  Northeastern Naturalist 6: 39-88.

Prezant, R.S., and E.J. Chapman. 2004.  Freshwater molluscs of the United States Military Academy drainages (West Point, NY) and comparative regional biodiversity of gastropods.  Northeastern Naturalist 11(3):273-294.

 Smith, D. (1987) Mollusca Mesogastropoda. Keys to the Freshwater Macroinvertebrates of Massachusetts, No. 2. Westborough: Mass. Div. Water Poll. Control

 Smith, G.  (1995) Keys to the freshwater macroinvertebrates of Massachusetts, Second Edition.  Privately published, available from D.G. Smith, 30 Montague Road, Sunderland, MA  01375

 Strayer, D. (1987) Ecology and zoogeography of the freshwater mollusks of the Hudson River basin. Malac. Rev., 20, 1-68

 Strayer, D. (1990) Freshwater Mollusca. In Freshwater Macroinvertebrates of Northeastern North America, ed. B. Peckarsky, P. Fraissinet, M. Penton & D. Conklin, pp. 333-372. Ithaca: Cornell University Press.
 

Southern Atlantic

 Beetle, D. (1973) A checklist of the land and freshwater mollusks of Virginia. Sterkiana, 49, 21-35

 Chambers, S. (1990) The genus Elimia (= Goniobasis) in Florida (Prosobranchia: Pleuroceridae). Walkerana, 4, 237-70.

Cowie, R.H., and S.C. Thiengo. 2003.  The apple snails of the Americas (Mollusca : Gastropoda : Ampullariidae : Asolene, Felipponea, Marisa, Pomacea, Pomella): A nomenclatural and type catalog.  Malacologia 45(1):41-100.

 Dawley, C. (1965) Checklist of freshwater mollusks of North Carolina. Sterkiana, 19, 35-9

 Dillon, R. T., Jr. & Davis, G. M. (1980) The Goniobasis of southern Virginia and northwestern North Carolina: Genetic and shell morphometric relationships. Malacologia, 20, 83-98.
 
 Dillon, R. & Keferl, E. (2000) A survey of the pleurocerid gastropods of South Carolina.  In Freshwater Mollusk Symposia Proceedings, Part II, eds. Tankersley, Warmolts, Watters, Armitage, Johnson & Butler, pp. 153 - 160.  Columbus: Ohio Biological Survey.

 Emerson, W. & Jacobson, M. (1976) Guide to Shells, Land, Freshwater, and Marine, from Nova Scotia to Florida. New York: Alfred A. Knopf

 Goodrich, C. (1942a) The Pleuroceridae of the Atlantic coastal plain. Occas. Pprs. Mus. Zool. Univ. Mich., 456, 1-6.

Mihalcik, E.L., and F.G. Thompson. 2003.  A taxonomic revision of the freshwater snails referred to as Elimia curvicostata, and related species. Walkerana 12(29-30):1-108.

 Pilsbry, H. (1934) Review of the Planorbidae of Florida, with notes on other members of the family.  Proc. Acad. Natl. Sci. Phila., 86, 29-66.

Stewart, T.W., and R.T. Dillon, Jr. 2004.  Species composition and geographic distribution of Virginia’s freshwater gastropod fauna: A review using historical records.  American Malacological Bulletin 19(1-2):79-91.

 Thompson, F. (1968) The Aquatic Snails of the Family Hydrobiidae of Peninsular Florida. Gainesville: University of Florida Press

 Thompson, F. (1969) Some hydrobiid snails from Georgia and Florida. Quart. J. Florida Acad. Sci., 32, 241-65

 Thompson, F. (1984) The Freshwater Snails of Florida, A Manual for Identification. Gainesville: University of Florida Press.

 Thompson, F. (1999) An identification manual for the freshwater snails of Florida.  Walkerana 10: 1 - 96.

 Thompson, F. & Hershler, R. (1991) Two new hydrobiid snails (Amnicolinae) from Florida and Georgia with a discussion of the biogeography of freshwater gastropods of south Georgia streams. Malac. Rev., 24, 55-72.

 Watson, C. (2000) Results of a survey for selected species of Hydrobiidae (Gastropoda) in Georgia and Florida.  In Freshwater Mollusk Symposia Proceedings, Part II, eds. Tankersley, Warmolts, Watters, Armitage, Johnson & Butler, pp. 233 - 244.  Columbus: Ohio Biological Survey.

 Wood, D. (1982) Aquatic Snails (Gastropoda) of the Savannah River Plant, Aiken, South Carolina. Athens, Ga.: Georgia University Research Foundation
 

Eastern Gulf

 Bickel, D. (1968) Checklist of the Mollusca of Tennessee. Sterkiana, 31, 15-39

 Chambers, S. (1990) The genus Elimia (= Goniobasis) in Florida (Prosobranchia: Pleuroceridae). Walkerana, 4, 237-70

 Clench, W. & Turner, R. (1956) Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum, 1, 94-239

 Dillon, R., Jr. & Lydeard, C. (1998) Divergence among Mobile Basin populations of the pleurocerid snail genus, Leptoxis, estimated by allozyme electrophoresis. Malacologia, 39, 113-21

 Goodrich, C. (1922) The Anculosae of the Alabama River drainage. Misc. Publ. Mus. Zool. Univ. Mich., 7, 1-57

 Goodrich, C. (1936) Goniobasis of the Coosa River, Alabama. Misc. Publ. Mus. Zool. Univ. Mich., 31, 1-60

 Goodrich, C. (1941a) Pleuroceridae of the small streams of the Alabama River system. Occas. Pprs. Mus. Zool. Univ. Mich., 427, 1-10

 Goodrich, C. (1941b) Distribution of the gastropods of the Cahaba River, Alabama. Occas. Pprs. Mus. Zool. Univ. Mich., 428, 1-30

 Goodrich, C. (1944b) Certain operculates of the Coosa River. Nautilus, 58, 1-10

 Goodrich, C. (1944c) Pleuroceridae of the Coosa River basin. Nautilus, 58, 40-8

 Lydeard, C., Holznagel, W.E., Garner, J., Hartfield, P., & Pierson, J.M. (1997)  A molecular phylogeny of Mobile River drainage basin pleurocerid snails (Caenogastropoda: Cerithioiidea).  Molecular Phylogenetics and Evolution 7: 117-128.

 McGregor, S., Shepard, T., Richardson, T.,  & Fitzpatrick, J. (1999) A survey of the primary tributaries of the Alabama and lower Tombigbee rivers for freshwater mussels, snails, and crayfish.  Geological Survey of Alabama Circular 196: 1 - 29.

 Pilsbry, H. (1934) Review of the Planorbidae of Florida, with notes on other members of the family. Proc. Acad. Natl. Sci. Phila., 86, 29-66

 Thompson, F. (1968) The Aquatic Snails of the Family Hydrobiidae of Peninsular Florida. Gainesville: University of Florida Press

 Thompson, F. (1969) Some hydrobiid snails from Georgia and Florida. Quart. J. Florida Acad. Sci., 32, 241-65

 Thompson, F. (1984) The Freshwater Snails of Florida, A Manual for Identification. Gainesville: University of Florida Press.

 Thompson, F. (1999) An identification manual for the freshwater snails of Florida.  Walkerana 10: 1 - 96.

 Thompson, F. (2000) Freshwater snails of the genus Elimia from the Coosa River system, Alabama.  Walkerana 11: 1 - 54.

 Thompson, F. & Hershler, R. (1991) Two new hydrobiid snails (Amnicolinae) from Florida and Georgia with a discussion of the biogeography of freshwater gastropods of south Georgia streams. Malac. Rev., 24, 55-72
 

Western Gulf

Cheatum, E. P. & Fullington, R. W. (1971) The aquatic and land Mollusca of Texas.  Bulletin 1, Supp: Keys to the families of the recent land and freshwater snails of Texas.  Dallas Mus. of Natur. His. 1, 1-18

Fullington, R. (1982) The recent and fossil freshwater gastropod fauna of Texas. In Proceedings of the Symposium on Recent Benthological Investigations in Texas and Adjacent States, ed. J. Davis, pp. 61-7. Dallas: Dallas Mus. Nat. Hist.

 Henderson, J. (1924) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming. University of Colorado Studies, Boulder, 13, 65-223

 Henderson, J. (1936a) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming, Supplement. University of Colorado Studies, Boulder, 23, 81-145

 Henderson, J. (1939) The mollusca of New Mexico and Arizona. In So Live the Works of Men, ed. D. Brand & F. Harvey, pp. 187-94. Albuquerque: University of New Mexico Press

 Hershler, R. & Longley, G. (1986) Phreatic hydrobiids (Gastropoda: Prosobranchia) from the Edwards (Balcones Fault Zone) Aquifer region, south-central Texas. Malacologia, 27, 127-72

 Murray, H. & Roy, E. (1968) Checklist of fresh-water and land mollusks of Texas. Sterkiana, 30, 25-42

 Neck, R. (1990) Ecological analysis of the living molluscs of the Texas panhandle. Am. Malac. Bull., 8, 9-18

 Strecker, J. (1935) Land and freshwater snails of Texas. Trans. Texas Acad. Sci., 17, 1-50

 Taylor, D. (1987) Fresh-water molluscs from New Mexico and vicinity. Bull. New Mexico Bur. Mines & Mineral Resources, 116, 1-50

 Wu, S.-K. (1989) Colorado Freshwater Mollusks. Natural History Inventory of Colorado, No. 11. Boulder: Univ. Colorado Museum
 

Eastern Mississippi

 Baker, F. (1902) The Mollusca of the Chicago area.  Part 2, The Gastropoda. Chicago Acad. Sci. Natl. Hist. Survey, 3, 131-410

 Baker, F. (1906) A catalogue of the Mollusca of Illinois. Bull. Ill. State Lab. Nat. Hist., 7, 53-136

 Baker, F. (1928) Freshwater Mollusca of Wisconsin, Part I, Gastropoda. Bull. Wisc. Geol. Natur. Hist. Survey, No. 70. Madison: University of Wisconsin Press

 Baker, F. (1935) Land and freshwater Mollusca from North Star Lake and vicinity, Itasca County, Minnesota. Am. Midl. Natur., 16, 257-74

 Bickel, D. (1967) Preliminary checklist of Recent and Pleistocene Mollusca of Kentucky. Sterkiana, 28, 7-20

 Bickel, D. (1968) Checklist of the Mollusca of Tennessee. Sterkiana, 31, 15-39

 Branson, B. (1987) Keys to the aquatic Gastropoda known from Kentucky. Trans. Kentucky Acad. Sci., 48, 11-9

 Branson, B. & Batch, D. (1971) Annotated distribution records for Kentucky Mollusca. Sterkiana, 43, 1-9

 Branson, B. & Batch, D. (1987) Distribution of aquatic snails (Mollusca: Gastropoda) in Kentucky with notes on fingernail clams. Trans. Kentucky Acad. Sci., 48, 62-70

 Dawley, C. (1947) Distribution of aquatic mollusks in Minnesota. Amer. Midl. Natur., 38, 671-97

 Goodrich, C. (1930) Goniobases of the vicinity of Muscle Shoals. Occas. Pprs. Mus. Zool. Univ. Mich., 209, 1-25

 Goodrich, C. (1939b) Pleuroceridae of the Mississippi River basin exclusive of the Ohio River system. Occas. Pprs. Mus. Zool. Univ. Mich., 406, 1-4

 Goodrich, C. (1940) The Pleuroceridae of the Ohio River system. Occas. Pprs. Mus. Zool. Univ. Mich., 417, 1-21

 Goodrich, C. & van der Schalie, H. (1944) A revision of the Mollusca of Indiana. Am. Midl. Natur., 32, 257-326.

Jass, J.P. 2004.  Distributions of gastropods in Wisconsin.  Milwaukee Public Museum Contributions in Biology and Geology 99:1-28.

 LaRocque, A. (1959) Checklist of Ohio Pleistocene and living Mollusca. Sterkiana, 1, 23-49

 LaRocque, A. (1968) Pleistocene mollusca of Ohio. Ohio Geol. Survey Bull., 62, 357-553

 Laursen, J., Averbeck, G., Conboy, G. & Stromberg, B. (1992) Survey of pulmonate snails of central Minnesota. J. Freshw. Ecol., 7, 25-33.

Minton, R.L., and C. Lydeard. 2003.  Phylogeny, taxonomy, genetics and global heritage ranks of an imperilled, freshwater snail genus Lithasia (Pleuroceridae). Molecular Ecology 12(1):75-87.

 Morrison, J. P. E. (1932) A report on the mollusca of the northeastern Wisconsin Lake district.  Trans. Wisconsin Acad. Sci. Arts Lett. 27, 359-396

 Rosewater, J. (1959) Mollusca of the Salt River, Kentucky.  Nautilus 73, 57-63
 
 

Western Mississippi

 Angelo, R., Cringan, M. & Fry, J. (2002) Distributional revisions and new and amended occurrence records for prosobranch snails in Kansas.  Trans. Kansas Acad. Sci. 105: 246 - 257.

 Baker, F. (1919) Fresh Water Mollusca from Colorado and Alberta. Bull. Am. Mus. Nat. Hist., 41, 527-39

 Baker, F. (1935) Land and freshwater Mollusca from North Star Lake and vicinity, Itasca County, Minnesota. Am. Midl. Natur., 16, 257-74

 Beetle, D. (1961) A checklist of Wyoming Recent Mollusca. Sterkiana, 3, 1-9

 Beetle, D. (1989) Checklist of recent Mollusca of Wyoming, USA. Great Basin Natur., 49, 637-45

 Branson, B. (1961) Recent Gastropoda of Oklahoma.  Part II. Distribution, ecology and taxonomy of freshwater species, with description of Helisoma travertina sp. nov. Okla. State Univ. Pub., Biol. Stud. Series 6, 58, 1-72

 Cvancara, A. (1975) Aquatic malacogeography of North Dakota. Proc. North Dakota Acad. Sci., 27, 68-82

 Cvancara, A. (1983) Aquatic Mollusks of North Dakota. Report of Investigation, vol. 78. North Dakota Geol. Survey

 Dawley, C. (1947) Distribution of aquatic mollusks in Minnesota. Amer. Midl. Natur., 38, 671-97

 Goodrich, C. (1939b) Pleuroceridae of the Mississippi River basin exclusive of the Ohio River system. Occas. Pprs. Mus. Zool. Univ. Mich., 406, 1-4

 Henderson, J. (1924) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming. University of Colorado Studies, Boulder, 13, 65-223

 Henderson, J. (1936a) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming, Supplement. University of Colorado Studies, Boulder, 23, 81-145.

 Hershler, R. (1998) A systematic review of the hydrobiid snails (Gastropoda: Rissooidea) of the Great Basin, western United States.  Part I, Genus Pyrgulopsis.  Veliger 41: 1 - 132.  

 Laursen, J., Averbeck, G., Conboy, G. & Stromberg, B. (1992) Survey of pulmonate snails of central Minnesota. J. Freshw. Ecol., 7, 25-33

 Leonard, A. (1959) Handbook of Gastropods in Kansas. Misc. Publ., no. 20. Lawrence: Univ. Kansas Mus. Natl. Hist.

 Liu, H.-P., and R. Hershler. 2005.  Molecular systematics and radiation of western North American nymphophiline gastropods.  Molecular Phylogenetics and Evolution 34(2):284-298.

 Stewart, T.  (2006)   The freshwater gastropods of Iowa (1821-1998): Species composition, geographic distributions, and conservation concerns. Amer. Malac. Bull., 21: 59 - 75.

 Tuthill, S. (1962) A checklist of North Dakota Pleistocene and Recent Mollusca. Sterkiana, 8, 12-8

 Tuthill, S. (1963) Corrections and additions to the checklist of North Dakota Pleistocene and Recent Mollusca. Sterkiana, 10, 29-30

 Winslow, M. (1921) Mollusca of North Dakota. Occas. Pprs. Mus. Zool. Univ. Mich., 98, 1-18.

 Wu, S.-K. (1989) Colorado Freshwater Mollusks. Natural History Inventory of Colorado, no. 11. Boulder: Univ. Colorado Museum

 Wu, S.-K., Oesch, R. & Gordon, M. (1997) Missouri Aquatic Snails. Jefferson City: Missouri Department of Conservation
 

Pacific

 Baker, F. (1919) Fresh Water Mollusca from Colorado and Alberta. Bull. Am. Mus. Nat. Hist., 41, 527-39

 Baxter, R. (1987) Mollusks of Alaska.  Shells and Sea Life, Bayside, Calif.  163 pp.

 Beetle, D. (1961) A checklist of Wyoming Recent Mollusca. Sterkiana, 3, 1-9

 Beetle, D. (1989) Checklist of recent Mollusca of Wyoming, USA. Great Basin Natur., 49, 637-45

 Bequaert, J. & Miller, W. (1973) The Mollusks of the Arid Southwest, with an Arizona Check List. Tucson: University of Arizona Press

 Chamberlain, R. & Jones, D. (1929) A descriptive catalogue of the Mollusca of Utah. Bull. Univ. Utah, 19, 1-203

 Chamberlain, R. & Roscoe, E. (1948) Check list of the Recent Utah Mollusca. Bull. Univ. Utah, 39, 1-16

 Clarke, A. (1981) The Freshwater Mollusks of Canada. Ottawa: The National Museums of Canada

 Dall, W. (1905) Land and Fresh Water Mollusks of Alaska and Adjoining Regions. Harriman Alaska Expeditions 1899, no. 13. Washington, D.C.: Smithsonian Inst.

 Frest, T., & Johannes, E. (2000) An annotated checklist of Idaho land and freshwater mollusks.  J. Idaho Acad. Sci., 36(2): 1-51.

 Frest, T., Johannes, E., Clark, W., Stephens, G., & Plew, M. (2001)  A bibliography of Idaho freshwater and terrestrial mollusks.  J. Idaho Acad. Sci. 37(2): 9 - 120.

 Goodrich, C. (1942b) Pleuroceridae of the Pacific Coastal Drainage, including the western interior basin. Occas. Pprs. Mus. Zool. Univ. Mich., 469, 1-4

 Goodrich, C. (1944a) Pleuroceridae of the Great Basin. Occas. Pprs. Mus. Zool. Univ. Mich., 485, 1-11.

 Hanna, G. (1956) Land and freshwater mollusks of the Arctic slope, Alaska. Nautilus, 70, 4-10

 Hannibal, H. (1912) A synopsis of the Recent and Tertiary freshwater Mollusca of the California Province, based upon an ontogenetic classification. Proc. Malacol. Soc. Lond., 10, 112-211

 Henderson, J. (1924) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming. University of Colorado Studies, Boulder, 13, 65-223

 Henderson, J. (1929) Non-marine mollusca of Oregon and Washington. University of Colorado Studies, Boulder, 17, 47-190

 Henderson, J. (1936a) Mollusca of Colorado, Utah, Montana, Idaho and Wyoming, Supplement. University of Colorado Studies, Boulder, 23, 81-145

 Henderson, J. (1936b) The non-marine Mollusca of Oregon and Washington, Supplement. University of Colorado Studies, Boulder, 23, 251-80

 Henderson, J. (1939) The mollusca of New Mexico and Arizona. In So Live the Works of Men, ed. D. Brand & F. Harvey, pp. 187-94. Albuquerque: University of New Mexico Press.

 Hershler, R., T. Frest, E. Johannes, P. Bowler, & F. Thompson.  1994.  Two new genera of hydrobiid snails (Prosobranchia: Rissooidea) from the northwestern United States. Veliger, 37: 221-243.

 Hershler, R., T. Frest, H.-P. Liu, & E. Johannes.  2003.  Rissooidean snails from the Pit River Basin, California. Veliger, 46: 275-304.

 Hershler, R. & Landye, J. (1988) Arizona Hydrobiidae (Prosobranchia: Rissoacea). Smithsonian Contrib. Zool., 459, 1-63.

 Hershler, R., and H.-P. Liu. 2004.  Taxonomic reappraisal of species assigned to the North American freshwater gastropod subgenus Natricola (Rissooidea: Hydrobiidae).  Veliger 47(1):88-81.

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