﻿CREPIDULA. 
  Panama 
  Shells. 
  455 
  

  

  Crepidula 
  unguiformis 
  Brod. 
  in 
  Trans. 
  Zool, 
  Soc. 
  Lond. 
  I. 
  pi. 
  29. 
  

  

  f. 
  4. 
  1835. 
  

  

  MiiH. 
  Syn. 
  Nov. 
  Test. 
  Viv. 
  p. 
  151. 
  May 
  183G. 
  

  

  Lam. 
  An. 
  sans 
  Vert. 
  VII. 
  643. 
  No. 
  4. 
  

  

  (Desh. 
  ed;) 
  - 
  - 
  - 
  - 
  1838. 
  

  

  Pot. 
  etMich. 
  Gal. 
  Moll. 
  Mus. 
  Douai.I. 
  514. 
  1838. 
  

  

  plana 
  Gould 
  Invert. 
  Mass. 
  p. 
  159. 
  f. 
  16. 
  1840. 
  

  

  unguiformis 
  Lam. 
  An. 
  sans 
  Vert. 
  III. 
  Pt. 
  1. 
  p. 
  236. 
  

  

  (Desh. 
  ed. 
  tert.) 
  - 
  - 
  - 
  1841. 
  

   Reeve 
  Concli. 
  Syst. 
  pi. 
  143. 
  f. 
  6. 
  1842. 
  

  

  dilatata 
  No. 
  4. 
  Orb.Voy. 
  Amer. 
  Merid. 
  Moll. 
  p. 
  467. 
  1843. 
  

  

  2}lana 
  Dekay 
  Zool. 
  of 
  N. 
  Y. 
  Moll. 
  p. 
  158. 
  pi. 
  7. 
  

  

  f. 
  153. 
  a.h. 
  - 
  - 
  - 
  - 
  1843. 
  

  

  This 
  sliell 
  is 
  well 
  calculated 
  to 
  confound 
  the 
  popular 
  notion 
  

   of 
  species. 
  We 
  have 
  now 
  before 
  us 
  many 
  perfect 
  specimens 
  

   from 
  Sicily, 
  from 
  Massachusetts, 
  from 
  Jamaica, 
  and 
  from 
  Panama, 
  

   all 
  of 
  which, 
  with 
  the 
  exception 
  of 
  the 
  Mediterranean 
  shells, 
  

   we 
  collected 
  in 
  person. 
  They 
  present 
  many 
  modifications 
  of 
  

   form 
  dependent 
  on 
  progress 
  of 
  growth, 
  and 
  the 
  positions 
  which 
  

   they 
  occupy 
  in 
  dead 
  shells. 
  But 
  we 
  have 
  in 
  vain 
  attempted 
  to 
  

   discover 
  any 
  characteristics 
  of 
  locality. 
  The 
  only 
  approach 
  to 
  a 
  

   local 
  character 
  is 
  to 
  be 
  found 
  in 
  a 
  few 
  of 
  the 
  Panama 
  shells, 
  which 
  

   have 
  longitudinal 
  rays 
  of 
  reddish 
  brown, 
  while 
  all 
  the 
  other 
  

   specimens 
  are 
  of 
  a 
  uniform 
  white. 
  So 
  far 
  at 
  least 
  as 
  the 
  shells 
  

   are 
  concerned, 
  it 
  seems 
  necessary 
  to 
  admit 
  that 
  they 
  all 
  may 
  be 
  

   comprised 
  in 
  one 
  species 
  ; 
  or 
  to 
  maintain 
  that 
  individuals, 
  which 
  

   cannot 
  be 
  distinguished 
  from 
  each 
  other, 
  belong 
  to 
  diJfferent 
  

   species, 
  because 
  it 
  is 
  probable 
  that 
  they 
  descended 
  from 
  distinct 
  

   original 
  stocks. 
  But 
  if 
  we 
  admit 
  that 
  each 
  species 
  in 
  the 
  animal 
  

   kingdom 
  was 
  introduced 
  by 
  the 
  creation 
  of 
  many 
  original 
  stpcks, 
  

   then 
  the 
  fact 
  before 
  us 
  becomes 
  intelligible 
  and 
  very 
  uncommon 
  

   in 
  only 
  one 
  particular, 
  viz 
  : 
  that 
  the 
  original 
  individuals 
  of 
  a 
  

   single 
  species 
  were 
  created 
  in 
  very 
  distant 
  zoological 
  provinces. 
  

  

  On 
  the 
  opinion 
  that 
  the 
  North 
  American 
  C. 
  plana 
  Say 
  is 
  

   identical 
  with 
  the 
  Mediterranean 
  C. 
  unguiformis 
  Lam., 
  Dr. 
  

   Gould 
  remarks 
  as 
  follows 
  : 
  — 
  

  

  "In 
  this 
  opinion 
  I 
  have 
  the 
  concurrence 
  of 
  Mr. 
  Sowerby. 
  

  

  