﻿which 
  inhabit 
  Jamaica. 
  99 
  

  

  shells 
  can 
  exist 
  in 
  this 
  region. 
  "We 
  are 
  quite 
  ignorant 
  of 
  the 
  

   manner 
  in 
  which 
  this 
  species 
  was 
  introduced 
  to 
  its 
  habitat. 
  

  

  Neritina 
  Jamaicensis. 
  Shell 
  obliquely 
  ellipsoidal, 
  rather 
  

   thin 
  : 
  white 
  near 
  the 
  apex 
  : 
  otherwise 
  covered 
  with 
  violet, 
  

   which 
  is 
  sometimes 
  tinged 
  with 
  dark 
  gray, 
  with 
  lighter 
  and 
  

   darker 
  shades 
  in 
  spiral 
  bands, 
  and 
  is 
  more 
  or 
  less 
  interrupted 
  

   by 
  lines 
  of 
  growth 
  and 
  irregular 
  white 
  spots 
  : 
  surface 
  smooth 
  

   and 
  shining: 
  apex 
  rather 
  prominent: 
  spire 
  convex: 
  whorls 
  

   nearly 
  three, 
  with 
  a 
  fine 
  but 
  well 
  impressed 
  sutural 
  line 
  : 
  la- 
  

   bium 
  smooth, 
  moderately 
  thickened. 
  

  

  Length 
  of 
  spire 
  .07 
  inch 
  ; 
  height 
  .3 
  inch 
  ; 
  breadth 
  .32 
  inch. 
  

  

  Neritina 
  tenebricosa. 
  Shell 
  obliquely 
  ellipsoidal, 
  rather 
  

   thin: 
  black, 
  with 
  numerous 
  angular 
  translucent 
  spots 
  of 
  horn 
  

   color 
  : 
  white 
  on 
  the 
  labium, 
  blue 
  within 
  the 
  aperture 
  : 
  with 
  

   numerous 
  excessively 
  fine 
  spiral 
  and 
  incremental 
  striae 
  : 
  apex 
  

   quite 
  prominent: 
  spire 
  convex 
  : 
  whorls 
  two 
  and 
  one-half, 
  with 
  

   a 
  very 
  fine 
  but 
  well 
  impressed 
  sutural 
  line 
  : 
  labium 
  smooth, 
  

   moderately 
  thickened. 
  Inhabits 
  Black 
  River. 
  

  

  Length 
  of 
  spire 
  .06 
  inch 
  ; 
  height 
  .36 
  inch 
  ; 
  breadth 
  ,41, 
  

  

  It 
  affords 
  us 
  much 
  pleasure 
  to 
  find 
  two 
  new 
  fluviatile 
  spe- 
  

   cies 
  of 
  this 
  genus 
  in 
  the 
  Jamaica 
  Fauna. 
  With 
  the 
  excep- 
  

   tion 
  of 
  N. 
  punctulata, 
  all 
  the 
  other 
  species 
  are 
  strictly 
  marine, 
  

   living 
  upon 
  the 
  open 
  sea-shore. 
  If 
  authors 
  are 
  correct 
  in 
  

   stating 
  that 
  St. 
  Domingo 
  is 
  the 
  habitat 
  of 
  N. 
  punctulata, 
  that 
  

   species 
  is 
  the 
  only 
  fluviatile 
  shell 
  in 
  Jamaica, 
  belonging 
  to 
  a 
  

   genus 
  of 
  well 
  characterized 
  species, 
  which 
  is 
  not 
  peculiar 
  to 
  

   the 
  island. 
  Possibly 
  Lamarck's 
  statement 
  of 
  habitat 
  is 
  erro- 
  

   neous, 
  arising 
  from 
  the 
  shells 
  having 
  gone 
  to 
  France 
  by 
  way 
  

   of 
  St. 
  Domingo. 
  

  

  