Dr. Rob Dillon, Coordinator

Monday, April 5, 2021

Bill and Ruth and Jack and Virginia, and Campeloma

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  Bill and Ruth and Jack and Virginia, and Campeloma.  Pp 85 – 95 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other EssaysFWGNA Project, Charleston, SC.

Bill Clench was already well into the mascot phase of his career when I first met him at the 1976 AMU meeting in Columbus, Ohio.  Colleagues, students, and friends ushered him front-row-center for the annual society photo, Joe Morrison [1] and Leslie Hubricht [2] trailing in his wake.  I found Dr. Clench to be a warm and outgoing gentleman, still alert at age 78.  Please Lord, take me home before anybody calls me “alert.”

William J. Clench was born in New York in 1897 and grew up in the Boston area, collecting bugs, snails and shells around the Fenway, the Blue Hills and the local beaches [3].  Charles W. Johnson, the noted marine malacologist at the Boston Society of Natural History, was an early influence.  Clench graduated from Michigan State University in 1921, earned his MS at Harvard in 1923, then moved on to the University of Michigan to work on his doctorate [4], where Bryant Walker, quoting Tucker Abbott’s remembrance [5], “lit the malacological fires within Bill and was largely responsible for his first love, the freshwater mollusks.”

American Malacological Union 1976 [6]

From Michigan Clench accepted the mollusk curatorship at Harvard’s Museum of Comparative Zoology, where he served for 40 years, 1926 – 1966, mentoring many students who would become quite influential themselves.  Clench’s most famous student was R. Tucker Abbott, who succeeded Henry Pilsbry as curator at the ANSP and editor of The Nautilus, but we should not fail to mention the unionid guys Dick Johnson and Sam Fuller, or Arthur Clarke, whose landmark work on the Canadian freshwater molluscan fauna [7] sits handy by my desk, here 40 years after its publication.

Clench’s bibliography lists 420 scientific papers, covering the breadth of malacology: marine, terrestrial, freshwater and fossil, focused on North America but ultimately worldwide [8].  Most of his better papers were coauthored by Ruth Turner, another former student, with whom Clench’s life was “entwined,” to borrow Dick Johnson’s carefully-chosen verb.  We have previously featured on this blog the 1956 Clench and Turner monograph on the freshwater mollusks of Florida/Georgia Gulf drainages [9], which was an important contribution.

Clench’s malacology was early-modern, rooted in the old typology but with a growing appreciation of genetic variation within and among populations.  Looking down from my 2021 freshwater-gastropod-centric perspective, his greatest contribution was his two-part series on the North American Viviparidae, published in 1962 [10] and (with Sam Fuller) in 1965 [11].

The taxonomic history of the North American Viviparidae is identical to the taxonomic history of the North American Pleuroceridae, minus one order of magnitude coming into the 20th century, and two going out [12].  Digging through the musty tomes on the shelves and the dusty shells in the cabinets of the MCZ in the early 1960s, Clench was able to uncover 49 Latin nomina assigned to the genus Campeloma, Isaac Lea [14] tying C.S. Rafinesque for the lead with six each.  Of those 49 nomina, 35 he discarded for cause or synonymized, little rationale given or expected, at the close of the era when such good works were still possible.  Clench did not preface his work with an exhaustive study of shell morphological variation, as did my hero Calvin Goodrich for the North American pleurocerids in the 1940s [15].  But I don’t think he missed any viviparid nomina either, as Goodrich simply skipped hundreds of pleurocerids.  I think Clench got them all.  Thank you, Bill.

Alas, Clench did not explain why he spared the 14 specific Campeloma nomina that survived his 1962 monograph, any more than he explained why he cut the other 35.  That burden was shouldered 20 years later by Dr. John B. Burch [16], with an obscure contribution from Dr. Virginia A. Vail.

From the Burch/Vail key [16]

The “Family Viviparidae” header in Burch’s dichotomous key, way back on page 227, carries an asterisk.  And at the bottom of page 227 is printed, “*From Burch & Vail (1982).”  But no work by Burch & Vail is listed among the references, nor was one ever published subsequently, to my knowledge [17].

Burch’s bibliography does, however, list six papers published by Virginia Vail at that point in her career, all solo, and they are good ones.  She was an excellent scientist, about whom I have been able to discover little.  She was born in Schenectady, NY, in 1945, earned her B.A. at Hartwick College (NY) and her M.S. and Ph.D. at Florida State University, graduating in 1975 [18].  From thence Vail went directly to the Tall Timbers Research Station north of Tallahassee, where she spent the rest of her career.

In 1977 and 1978 Virginia Vail published a two-part series comparing the reproductive anatomy and life history of Campeloma, Lioplax, and Viviparus in Florida.  Her first paper [19] was anatomical, featuring very nice drawings of male and female reproductive systems for all three taxa, and her second paper [20] ecological, detailing seasonal reproductive cycles.  The viviparids are quite conservative anatomically; Virginia was able to document only negligible difference in the plumbing of the three genera [21].  But here 40 years later, we still await a finer contribution to the comparative biology of the North American Viviparidae.

Virginia Vail identified the Campeloma population she selected for her study as C. geniculum (Conrad).  Interestingly, that particular population, inhabiting the Chipola River about 60 miles NW of Tallahassee, seems to have been entirely sexual, males and females (apparently) in roughly equal proportion.  She made only passing reference to asexual reproduction in her 1977-78 papers, noting that Mattox [23] had documented parthenogenesis in Campeloma rufum [24] as early as 1937.

Vail [19] figs. 5 & 10 [25]

The next year, Vail described Campeloma parthenum from Lake Talquin, an impoundment of the Ochlockonee River west of Tallahassee.  She distinguished that population both by its apparent absence of males and by the contour of the outer lip of the shell [26].  But she seems to have been struggling with species concepts, even as she was describing new ones.  Here is the title and abstract of the talk she gave at the August 1979 meeting of the American Malacological Union in Corpus Christie, TX:


A poor understanding of environmentally induced shell variation, anatomical characteristics and the animal’s biology makes species identification difficult.  The occurrence of both dioecious and parthenogenetic populations (races? species?) and their peculiar geographic distributions further complicate the problem.  Observations on southeastern populations are offered to illustrate the problem and suggest solutions.”

I could not have said that better myself.  Fascinatingly, this was neither the title nor the abstract ultimately published in the Bulletin of the American Malacological Union for 1979, page 67.  The version that saw print was much more tamely entitled, “The Species Problem in Campeloma,” and featured a relatively measured critique of reliance on shell character, noting “the fact that reproduction can occur either parthenogenetically or sexually.”  As of the publication of her 1979 abstract, Virginia Vail was only counting two Campeloma species in Florida and Georgia combined, C. geniculum and “C. limum (includes C. floridense).”

I seem to remember [27], here 40 years later, that the solution Virginia Vail suggested on that August morning at La Quinta Royale Hotel in Corpus Christie, TX, recognized just those two species, a heavily-shelled C. geniculum (sexual) and more lightly-shelled C. limum (parthenogenetic).  That was certainly the direction Fred Thompson was tending by the 1990s with his “Identification Manual for The Freshwater Snails of Florida [30].”  Thompson listed four Campeloma species for The Sunshine State (geniculum, limum, floridense and parthenum), but observed, “in view of the inconsistency of shell characters, these last three forms may represent only a single species, Campeloma limum.”

American Malacological Union 1979

But returning to the thread of our story.  It was sometime during the late 1970s that Jack Burch signed a contract with the EPA to deliver his illustrated key to the North American Freshwater Snails [16].  And somehow [31] he linked up with Virginia Vail, during the full flower of her career.

The Burch/Vail key to the North American Viviparidae that ultimately saw publication in 1982 proceeds unremarkably through its first ten couplets, guiding us to the genus Campeloma on page 228, where we are referred to supplemental note (4).  That endnote – on page 268 now – begins with a brief review of Clench’s signal (1962) contributions to our understanding of the genus Campeloma [10].  Then four more nomina are subtracted from Clench’s list of 14 species on the authority of Arthur Clarke [32]: leptum Mattox 1940, tannum Mattox 1940, integra (Say 1821) and milesi (Lea 1863).  That brought our continental fauna down to 10.

Returning to the main key, on page 229, we find an earnest effort to distinguish, by shell morphology alone, eight species of Campeloma.  Three of the ten species surviving Burch’s endnote (4) did not survive the perilous transfer forward from page 268 to page 229.  The specific nomina brevispirum (Baker 1928), exilis (Anthony 1860), and gibba (Currier 1867) seem to have vanished [33].  But one brand new species of Campeloma was added, Vail’s [26] parthenum, bringing our total continental Campeloma fauna to N = 8 canonical species, as of 1982.  In the order of their description:

  • Limnaea decisa Say 1817.  Clench speculated “Delaware River?”
  • Campeloma crassula Rafinesque 1819.  The Ohio.
  • Paludina genicula Conrad 1834.  Flint River, GA.
  • Paludina regularis Lea 1841. Coosa R, AL.
  • Paludina lima Anthony 1860. South Carolina.
  • Melantho decampi Binney 1865. Decatur, AL. [34]
  • Campeloma floridense Call 1886.  Wekiva River, FL.
  • Campeloma parthenum Vail 1979.  Lake Talquin, FL.

The Burch/Vail key to the Campeloma begins with aperture color (white vs brown), then moves on to shell shoulders (angled vs rounded) then moves on to shell profile (broadly ovate vs narrowly ovate), and so forth.  It is a valiant effort, and I do not mean to diminish the contribution of its authors.  Just the opposite.

Science is the construction of testable hypotheses about the natural world.  It is not about being right, it is about being testable.  The Burch/Vail dichotomous key to distinguish the eight canonical species of North American Campeloma is science.

Next month, we test it.


[1] For my remembrance of J.P.E. Morrison, see:

  • Joe Morrison and the Great Pleurocera Controversy [10Nov10]

[2] For a bit more about Leslie Hubricht, see:

  • The Most Cryptic Freshwater Gastropod in the World [6Aug17]

[3] Most of the biographical details relayed above were gleaned from: Turner, R. D. (1985)  William J. Clench October 24, 1897 – February 22, 1984.  Malacological Review 18: 123-124.

[4] Surprisingly, Clench did not finish.  He was ultimately awarded honorary doctorates from both Michigan and MSU in 1953.

[5] Abbott RT (1984). "A Farewell to Bill Clench". The Nautilus 98 (2): 55–58.

[6] This is a detail from a scan of the original 8x10 glossy in my files.  The back is stamped, “Dept. of Photography & Cinema, The Ohio State University,  No. 191231-1, Please Give Credit”  Done.

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

[8] Johnson, R.I. (2003)  Molluscan taxa and bibliographies of William James Clench and Ruth Dixon Turner.  Bulletin of the Museum of Comparative Zoology at Harvard College 158: 1- 46.

[9] Clench, W.J. & R.D. Turner (1956)  Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwannee River. Bull. Fla. State Mus. (Biol. Sci.), 1: 97-239.   For more, see:

  • Fred Thompson, Steve Chambers, and the pleurocerids of Florida [15Feb17]

[10] Clench, W.J. (1962) A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occasional Papers on Mollusks 2(27): 261-287.

[11] Clench, W.J. & S.L.H. Fuller (1965) The genus Viviparus (Viviparidae) in North America. Occasional Papers on Mollusks 2(32): 385-412.

[12] Graf [13] has catalogued “nearly 1,000” specific nomina historically applied to North American freshwater gastropods of the family Pleuroceridae.  Between 1934 – 1944 my hero Cavin Goodrich was able to pare these down to approximately 150.  For more, see:

  • The Legacy of Calvin Goodrich [23Jan07]

[13] Graf, D. L. (2001) The cleansing of the Augean Stables, or a lexicon of the nominal species of the Pleuroceridae (Gastropoda: Prosobranchia) of recent North America, north of Mexico. Walkerana 12 (27) 1 - 124.

[14] For more about the “Nestor of American Naturalists,” see:

  • Isaac Lea Drives Me Nuts [5Nov19]

[15] For the further exploits of my hero, see:

  • Goodrichian Taxon Shift [20Feb07]
  • Mobile Basin II: Leptoxis Lessons [15Sept09]
  • CPP Diary: The Spurious Lithasia of Caney Fork [4Sept19]

[16] This is a difficult work to cite.  J. B. Burch's North American Freshwater Snails was published in three different ways.  It was initially commissioned as an identification manual by the US EPA and published by the agency in 1982.  It was also serially published in the journal Walkerana (1980, 1982, 1988) and finally as stand-alone volume in 1989 (Malacological Publications, Hamburg, MI).

[17] The parallel between the careers of Virginia Vail and George Te is inescapable here.  George Te was a Burch student in the late 1970s and seems to have ghost-written Burch’s entire treatment of the Physidae, as Virginia Vail ghost-wrote the Viviparidae.  For more on George Te, see:

  • To Identify a Physa, 1975 [6May14]
  • To Identify a Physa, 1978 [12June14]

[18] Abbott, R.T. (1975)  American Malacologists, Supplement.  American Malacologists, Greenville, Delaware. 

[19] Vail, V.A. (1977)  Comparative reproductive anatomy of 3 viviparid gastropods.  Malacologia 5: 519 – 540.

[20] Vail, V.A. (1978)  Seasonal reproductive patterns in 3 viviparid gastropods.  Malacologia 6: 73 – 97.

[21]  The viviparids have evolved [22] quite a few unique adaptations that separate them from all other living gastropods, including a weird operculum and even weirder radula.  The right tentacle of the male has been modified into a simple, external penis and the pallial gonoduct of the female modified into a marsupium, capable of nursing fertilized eggs until their hatch into impressively large crawl-away juveniles.  But within the family, their anatomy is as boringly uniform as the pleurocerids.  You crack a Viviparus shell, or a Lioplax shell, or a Campeloma shell, and look inside, and it’s basically viviparid guts.  Every time.

[22] “Retained” might be a better verb here.  The worldwide family Viviparidae seems to be ancient.  They share their peculiar concentric operculum with the Ampullaridae, which suggests that the two families are sisters.  But the viviparids have absolutely no living marine antecedents.  I take this as evidence of an hypothesis I advanced back in 2009, that evolution is slower in fresh waters than in the marine environments from which all life originated.  Like the pleurocerids, the viviparids are “living fossils.”  For more, see:

  • The snails the dinosaurs saw [16Mar09]

[23] Mattox, N.T. (1937) Oogenesis of Campeloma rufum, a partheogenetic snail.  Zeitschrift fur Zellforschung und Mikroskopische Anatomie 27: 455 – 464.

Mattox, N.T. (1938)  Morphology of Campeloma rufum, a parthenogenetic snail.  Journal of Morphology 62: 243-261.

[24] Mattox sampled his study population from a tributary of the Wabash River in eastern Illinois.  Clench [10] subsequently synonymized Campeloma rufum under C. crassulum (Raf.) 

[25] Abbreviations from Vail [19] figures 5 and 10: AG = albumin gland, CM = columellar muscle, DG = digestive gland, M = mantle, O = ovary, OD = oviduct, PMC = posterior end mantle cavity, PO = pallial oviduct, PR = prostate gland, RT = right tentacle, SR = seminal receptacle, SV = seminal vesicle, T = testis, V = vagina, VD = vas deferens,  VD’ = pallial vas deferens.

[26] Vail, V.A. (1979) Campeloma parthenum (Gastropoda: Viviparidae), a new species from north Florida.  Malac. Rev. 12:85-86. 

[27]  Isn’t it interesting the way we can remember small vignettes from 40 years ago, but cannot remember what we had for supper last night [28]?  Virginia Vail gave her talk in the freshwater session of the Corpus Christie AMU meeting at 11:00 Thursday morning, August 9, 1979.  Young Rob Dillon, then listed as a graduate student at the University of Pennsylvania, gave his talk at 11:15, “The Goniobasis of southern Virginia and northwestern North Carolina: Electrophoretic and shell morphological relationships [29].”  At approximately 11:31, Old Joe Morrison jumped up and lectured me with great passion about obscure details of pleurocerid taxonomy and systematics.  At about 11:35, I said, “Easy, big fella.”  For more, see:

  • Joe Morrison and The Great Pleurocera controversy [10Nov10]

[28] It was a chicken casserole, with cashews sprinkled on top.  I just looked in the refrigerator.

[29] That was just the second presentation I had ever made at a national meeting.  The research was ultimately published as: Dillon, R.T., Jr and G.M. Davis (1980) The Goniobasis of southern Virginia and northwestern North Carolina: Genetic and shell morphometric relationships. Malacologia 20: 83-98. [PDF]

[30] Thompson, F.G. (2000)  An identification manual for the freshwater snails of Florida.  Walkerana 10(23): 1 -96.  Also available online [html].

[31] No, it was not at an AMU meeting.  Jack Burch was never a member of the AMU/AMS during his entire professional career, as far as I know, until being elected an honorary life member in 2009.  His election was not unanimous.

[32] Clarke, A.H. (1973) The freshwater mollusks of the Canadian Interior Basin.  Malacologia 13: 1 – 509.

[33] The nomina brevispirum (Baker 1928), exilis (Anthony 1860), and gibba (Currier 1867) were not actually forgotten.  If you look forward into Burch’s “Species List, Ranges, and Illustrations” on page 92, you will find them synonymized under Campeloma decisum.

[34] “Huntsville or Stevenson, Alabama.”  This was corrected to Decatur, AL by: Clench, W. J. and R.D. Turner (1955) The North American genus Lioplax in the Family Viviparidae.  Occasional Papers on Mollusks, Museum of Comparative Zoology, Harvard. 2(19): 1 -  20. 


  1. Still laughing over the chicken . . .

    I notice Norman Mattox in here. He also worked on clam shrimp. I met him once, long, long ago.

    Thanks, Rob! Keep these great essays coming!

    1. And thank you for your kind words! I agree with you that it is surprising to see how long some scientific careers can extend, even as science churns forward at ever-dizzying rates. You met Mattox, who published in 1937. I met Clench, who published even earlier. I suppose you and I should watch our steps, as child-scientists now in their early 20s may recall our memories in the year 2100.

  2. While the publication history of William Nicholson's The American Edition of the British Encyclopedia, or Dictionary of Arts and Sciences is complicated the article "Conchology"is generally accepted to be attributed to Say, 1817 not Say 1816/17 whatever that is. Also, he described the taxon as Lymnaea Decisa and the parens are not needed or desired as they imply that it was described in a different genus. Words and Parens have meaning. LOL

    1. Corrected, with a stipulation. When I use a paren, it means just what I choose it to mean - neither more nor less.

    2. Which makes it wrong and confusing but you be you.