﻿75 
  

  

  NOTES 
  ON 
  MAOILUS 
  AND 
  ITS 
  ALLIES, 
  SUBSTITUTING 
  THE 
  

   GENERIC 
  NAME 
  MAOILOPSIS 
  FOR 
  LEPTOCONCHUS 
  LA- 
  

   MARCKI, 
  DESHAYES. 
  

  

  By 
  G. 
  B. 
  SowKEBY, 
  F.L.S.' 
  

  

  Read 
  14th 
  June, 
  1918. 
  

  

  A 
  CAREFUL 
  study 
  of 
  a 
  considerable 
  number 
  of 
  shells 
  of 
  this 
  family 
  

   has 
  convinced 
  me 
  that 
  the 
  genus 
  Magilns 
  is 
  restricted 
  to 
  the 
  one 
  

   tube-forming 
  species, 
  M. 
  antiquns, 
  Montfort. 
  

  

  The 
  shell 
  of 
  Magihis 
  is 
  so 
  well 
  known 
  that 
  it 
  would 
  seem 
  scarcely 
  

   needful 
  for 
  me 
  to 
  describe 
  it 
  here; 
  but 
  in 
  order 
  to 
  justify 
  the 
  

   conclusion 
  at 
  which 
  I 
  have 
  arrived 
  concerning 
  the 
  undeveloped 
  

   shells, 
  etc., 
  and 
  the 
  variation 
  in 
  the 
  adults, 
  being 
  the 
  results 
  of 
  

   circumstances 
  in 
  tlieir 
  position 
  and 
  development, 
  it 
  is 
  needful 
  to 
  

   recapitulate 
  some 
  facts 
  concerning 
  this 
  remarkable 
  mollusc. 
  The 
  

   young 
  shell, 
  varying 
  much 
  in 
  form, 
  lodges 
  in 
  a 
  crypt 
  in 
  the 
  coral 
  

   {Meandrina), 
  \n 
  which 
  it 
  is 
  quite 
  free 
  from 
  any 
  attachment; 
  

   subsequently 
  developing 
  with 
  the 
  growtli 
  of 
  the 
  coral, 
  quitting, 
  the 
  

   spiral, 
  and 
  forming 
  a 
  long 
  tube, 
  bringing 
  the 
  aperture 
  near 
  the 
  

   surface 
  of 
  the 
  coral 
  ; 
  the 
  spiral 
  whorls 
  (and 
  in 
  some 
  cases 
  several 
  

   inches 
  of 
  the 
  tube) 
  are 
  filled 
  with 
  a 
  solid 
  heavy 
  mass 
  of 
  shell, 
  

   Avhereas 
  the 
  young 
  shell, 
  before 
  forming 
  the 
  tube, 
  is 
  quite 
  thin 
  and 
  

   fragile. 
  

  

  Magihis 
  antiquus, 
  Montfort, 
  Conch. 
  Syst., 
  tom. 
  ii, 
  1810, 
  p. 
  43 
  ; 
  

  

  Lamarck, 
  Animaux 
  sans 
  Yertebres, 
  vol. 
  v, 
  1818, 
  p. 
  374; 
  

  

  Sowerby, 
  Conch. 
  Icon., 
  vol. 
  xviii, 
  1872 
  {Magihis), 
  fig. 
  2. 
  

   One 
  specimen 
  in 
  my 
  collection 
  is 
  wortliy 
  of 
  notice, 
  showing 
  that 
  

   in 
  some 
  cases 
  the 
  shell 
  grows 
  faster 
  than 
  the 
  coral. 
  After 
  proceeding 
  

   vertically 
  for 
  a 
  couple 
  of 
  inches, 
  it 
  suddenly 
  turns 
  off 
  to 
  the 
  right 
  

   (partly 
  covering 
  the 
  shell 
  of 
  another 
  in 
  the 
  same 
  direction), 
  it 
  then 
  

   takes 
  a 
  semicircular 
  sweep, 
  bringing 
  its 
  aperture 
  within 
  a 
  quarter 
  of 
  

   an 
  inch 
  of 
  the 
  top 
  of 
  the 
  coral. 
  

  

  Synonyms, 
  

   Magihis 
  microcephahis, 
  Sowerby, 
  lleeve, 
  Conch. 
  Icon., 
  vol. 
  xviii, 
  1872 
  

  

  {Magihis), 
  pi. 
  ii, 
  fig. 
  3. 
  

   I 
  must 
  take 
  upon 
  myself 
  the 
  onus 
  of 
  having 
  introduced 
  this 
  spurious 
  

   species, 
  described 
  and 
  figured 
  by 
  my 
  revered 
  father. 
  The 
  specimen 
  

   came 
  from 
  the 
  collection 
  of 
  a 
  great 
  collector 
  in 
  Holland 
  (Mr. 
  van 
  

   Lennep). 
  I 
  then 
  thought 
  it 
  a 
  distinct 
  species, 
  and 
  suggested 
  the 
  

   name, 
  I 
  am 
  now, 
  however, 
  convinced 
  that 
  the 
  extreme 
  smallness 
  of 
  

   the 
  spiral 
  portion 
  is 
  to 
  be 
  accounted 
  for 
  by 
  the 
  early 
  and 
  probably 
  

   rapid 
  growth 
  of 
  the 
  coral, 
  causing 
  the 
  animal 
  to 
  quit, 
  in 
  veiy 
  early 
  

   life, 
  its 
  spiral 
  form 
  to 
  avoid 
  being 
  entombed. 
  I 
  have 
  in 
  my 
  

   collection 
  a 
  specimen 
  which 
  might, 
  with 
  equal 
  propriety, 
  bear 
  the 
  

   name 
  " 
  macrocephalus^\ 
  It 
  has 
  five 
  whorls, 
  and 
  measures, 
  from 
  apex 
  

  

  ' 
  Most 
  of 
  the 
  specimens 
  mentioned 
  were 
  exhibited 
  on 
  the 
  reading 
  of 
  this 
  paper. 
  

  

  