﻿362 
  PKOCKKDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIK'i'Y. 
  

  

  EUKYSTROPHE, 
  n.g.^ 
  

  

  Shell 
  dextral, 
  depressed, 
  covered 
  with 
  minute 
  elongated 
  tubercles, 
  

   arranged 
  in 
  quincunx 
  ; 
  whorls 
  few 
  (four 
  in 
  the 
  type), 
  last 
  rapidly 
  

   increasing, 
  equalling 
  the 
  earlier 
  three 
  in 
  width, 
  contracted 
  behind 
  

   the 
  peristome 
  ; 
  apex 
  sunken 
  below 
  the 
  level 
  of 
  the 
  later 
  whorls. 
  

  

  Type, 
  Helix 
  Filholi^ 
  Bourguignat.^ 
  

  

  I 
  would 
  take 
  the 
  opportunity 
  to 
  make 
  two 
  rectifications 
  of 
  generic 
  

   nomenclature 
  in 
  Professor 
  Pilsbry's 
  great 
  work 
  on 
  the 
  classification 
  of 
  

   the 
  Helicidae.^ 
  On 
  p. 
  277 
  Helix 
  xmidentata 
  is 
  indicated 
  as 
  the 
  type 
  

   of 
  the 
  section 
  Perforatella, 
  Schliiter, 
  of 
  the 
  genus 
  Hygromia. 
  Kow 
  

   Pilsbry 
  could 
  not 
  have 
  seen 
  Schliiter's 
  work, 
  since 
  that 
  author 
  cites 
  

   Helix 
  hidentata, 
  Gmelin 
  \_= 
  H. 
  lidens, 
  Chemn.], 
  as 
  the 
  only 
  species 
  

   under 
  his 
  Perforatella,^ 
  which 
  name 
  must, 
  therefore, 
  supersede 
  

   Dihothrion, 
  Pfeifi'er 
  (1855), 
  given 
  for 
  the 
  next 
  section 
  on 
  p. 
  278 
  of 
  

   the 
  Manual. 
  

  

  For 
  the 
  group 
  of 
  Helix 
  unidentata, 
  Pefasina, 
  Beck 
  (1847),® 
  must 
  be 
  

   adopted. 
  Beck 
  included 
  in 
  this 
  section 
  Helix 
  Cohresiana, 
  Alten, 
  

   H. 
  fiilva, 
  Miiller, 
  H. 
  troehiformis, 
  Mont., 
  and 
  H. 
  Fahricii, 
  Beck. 
  

   Eliminating 
  the 
  last 
  three, 
  which 
  are 
  now 
  referred 
  to 
  the 
  zonitoid 
  

   genus 
  Euconulus, 
  the 
  only 
  species 
  fixing 
  the 
  type 
  is 
  H. 
  Cohresiana, 
  

   which 
  is 
  synonymous 
  with 
  H. 
  edentula, 
  Drap., 
  an 
  earlier 
  name. 
  

   Pilsbry 
  indicates 
  Petasina, 
  Morch, 
  Catal. 
  Yoldi, 
  1852, 
  p. 
  6, 
  as 
  a 
  

   synonym 
  of 
  Perforatella. 
  On 
  turning 
  to 
  Morch's 
  work 
  it 
  will 
  be 
  

   found, 
  however, 
  that 
  he 
  quotes 
  Beck 
  as 
  the 
  authority 
  for 
  the 
  name 
  

   Petasina. 
  

  

  The 
  synonymy 
  of 
  these 
  two 
  sections 
  will 
  therefore 
  ' 
  stand 
  as 
  

   follows 
  : 
  — 
  

  

  Section 
  Petasina, 
  Beck, 
  1847. 
  

  

  Type, 
  H. 
  edentula, 
  Drap. 
  

  

  Section 
  Perforatella, 
  Schliiter, 
  1838. 
  

   Petasia^ 
  Beck, 
  1837 
  (preocc), 
  Trochiscus, 
  Held, 
  1837 
  (preocc), 
  

   Dihothrion, 
  Pfeiffer, 
  1855. 
  

   Type, 
  H 
  hidens, 
  Chemn. 
  

  

  ^ 
  evpv^ 
  wide 
  ; 
  a-rpocpT}, 
  turning, 
  whorl. 
  , 
  , 
  

  

  2 
  Bull. 
  Soe. 
  Sci. 
  Toulouse, 
  vol. 
  i, 
  p. 
  441, 
  1873 
  ; 
  Bibl. 
  Ecole 
  Hautes 
  Etudes, 
  

  

  Sei. 
  Nat., 
  vol. 
  xvi, 
  art. 
  i, 
  p. 
  278, 
  pi. 
  xxvii, 
  figs. 
  5-8, 
  1877 
  ; 
  Ann. 
  Sci. 
  G^ol. 
  

  

  (Hebert), 
  viii, 
  p. 
  278, 
  pi. 
  xxvii, 
  figs. 
  5-8, 
  1877. 
  

   ^ 
  Manual 
  of 
  Conchology, 
  ser. 
  II, 
  vol. 
  ix, 
  1894. 
  

   ■* 
  System. 
  Verz., 
  1838, 
  p. 
  4. 
  

   ® 
  Anitl. 
  Ber. 
  Versamml. 
  Deutseh. 
  Naturf. 
  Kiel, 
  1847, 
  p. 
  122. 
  

  

  