﻿OLD 
  AND 
  NEW 
  WORLD 
  MELANLANS 
  — 
  MORRISON 
  363 
  

  

  name, 
  Lithasia 
  Haldeman 
  (1840), 
  which 
  has 
  the 
  species 
  geniculata 
  of 
  

   Haldeman 
  for 
  genotype. 
  

  

  The 
  smooth 
  species 
  from 
  the 
  Kentucky 
  River 
  named 
  Ellipstoma 
  

   zonalis 
  by 
  Rafinesque 
  in 
  1818 
  can 
  only 
  be 
  the 
  species 
  commonly 
  

   known 
  as 
  Lithasia 
  obovata 
  Say 
  1829. 
  With 
  over 
  10 
  years 
  priority, 
  the 
  

   specific 
  name 
  of 
  Rafinesque 
  must 
  be 
  used. 
  Animals 
  of 
  Pleurocera 
  

   zonalis 
  Rafinesque 
  personally 
  collected 
  from 
  the 
  Kentucky 
  River 
  

   have 
  been 
  examined 
  and 
  sketched. 
  The 
  female 
  egg-laying 
  characters 
  

   are 
  illustrated 
  in 
  figure 
  4 
  of 
  plate 
  11. 
  

  

  Subgenus 
  Ellipstoma 
  Rafinesque, 
  1818 
  

  

  In 
  spite 
  of 
  the 
  extreme 
  brevity 
  of 
  Rafinesque's 
  original 
  description 
  

   (1818b, 
  p. 
  42), 
  critical 
  reading 
  indicates 
  that 
  this 
  name 
  applies 
  only 
  

   to 
  the 
  gi'oup 
  afterward 
  named 
  Angitrema 
  by 
  Haldeman 
  (1841a). 
  

   Hannibal 
  (1912, 
  p. 
  168) 
  formally 
  designated 
  Rafinesque's 
  first 
  species, 
  

   Ellipstoma 
  gibbosa, 
  as 
  the 
  genotype, 
  although 
  he 
  misidentified 
  that 
  

   species. 
  When 
  one 
  approaches 
  the 
  identification 
  of 
  gibbosa 
  from 
  

   every 
  angle 
  it 
  is 
  evident 
  that 
  there 
  is 
  only 
  one 
  kind 
  of 
  snail 
  in 
  the 
  

   Ohio 
  and 
  Wabash 
  Rivers 
  with 
  "a 
  large 
  knob 
  behind 
  the 
  outward 
  lip." 
  

   This 
  is 
  the 
  same 
  species 
  namedj 
  almost^three 
  years 
  later 
  as 
  Melania 
  

   armigera 
  Say 
  (1821, 
  p. 
  178). 
  

  

  Critical 
  examination 
  of 
  the 
  animal 
  characters 
  of 
  the 
  genotype 
  

   Pleurocera 
  (Ellipstoma) 
  gibbosa 
  Rafinesque 
  is 
  needed 
  to 
  check 
  the 
  bio- 
  

   logical 
  distinction 
  of 
  Ellipstoma 
  as 
  a 
  subgenus, 
  a 
  separate 
  genus, 
  or 
  a 
  

   synonym 
  of 
  Pleurocera, 
  sensu 
  stricto. 
  

  

  Genus 
  Anaplocamus 
  Dall, 
  1895 
  

  

  Anaplocamus 
  of 
  Dall 
  (1895, 
  p. 
  8), 
  mistakenly 
  described 
  as 
  an 
  Alaskan 
  

   marine 
  shell 
  because 
  of 
  accidentally 
  transposed 
  locality 
  labels, 
  is 
  a 
  

   monotypic 
  genus 
  based 
  on 
  the 
  species 
  "Anculosa" 
  dilatata 
  Conrad 
  

   (Rehder, 
  1942, 
  p. 
  49). 
  This 
  species 
  of 
  the 
  Kanawha 
  River 
  drainage 
  

   and 
  the 
  upper 
  Cheat 
  River 
  of 
  the 
  Allegheny 
  drainage 
  is 
  the 
  northern 
  

   representative 
  of 
  the 
  lo 
  group. 
  It 
  has 
  the 
  columellar 
  shell 
  structure 
  

   of 
  lo, 
  not 
  that 
  of 
  Leptoxis. 
  From 
  a 
  broad 
  biological 
  viewpoint 
  it 
  

   may 
  be 
  considered 
  a 
  subgenus 
  of 
  lo, 
  or, 
  more 
  conveniently, 
  a 
  separate 
  

   genus 
  closely 
  related 
  thereto. 
  

  

  Genus 
  lo 
  Lea, 
  1831 
  

  

  The 
  genus 
  lo 
  of 
  Lea 
  is 
  well 
  known; 
  it 
  includes 
  the 
  largest 
  living 
  

   United 
  States 
  Pleuroceridae 
  known. 
  How 
  many 
  species 
  other 
  than 
  

   the 
  nomiual 
  genotype 
  fluvialis 
  (Say) 
  there 
  are 
  or 
  were 
  in 
  existence 
  

   must 
  await 
  studies 
  of 
  the 
  animals 
  to 
  check 
  the 
  magnificent 
  analyses 
  

   of 
  shells 
  by 
  Adams 
  (1915). 
  Haldeman, 
  in 
  the 
  American 
  edition 
  of 
  

  

  