﻿98 
  Descriptiotis 
  of 
  New 
  Species 
  and 
  Varieties 
  of 
  Shells, 
  

  

  represented 
  by 
  a 
  variety 
  which 
  is 
  more 
  variable 
  in 
  size, 
  and 
  

   the 
  small 
  mature 
  specimens 
  are 
  nearly 
  intermediate 
  between 
  

   var. 
  minor 
  and 
  the 
  common 
  large 
  type, 
  which 
  inhabits 
  Man- 
  

   chester 
  and 
  other 
  middle 
  parts 
  of 
  the 
  island. 
  At 
  Easington 
  

   in 
  St. 
  David's, 
  is 
  another 
  variety, 
  distinguishable 
  from 
  the 
  

   small 
  specimens, 
  which 
  occur 
  in 
  the 
  neighboring 
  district 
  of 
  

   Portland, 
  by 
  the 
  entire 
  absence 
  of 
  any 
  internal 
  lamina 
  or 
  

   teeth. 
  It 
  may 
  be 
  called 
  delaminata. 
  

  

  The 
  same 
  name, 
  delaminata, 
  may 
  be 
  given 
  to 
  a 
  variety 
  of 
  

   H. 
  osculans 
  which 
  wants 
  the 
  internal 
  lamina. 
  

  

  Proserpina 
  niticla 
  var. 
  planulata 
  is 
  distinguished 
  by 
  be- 
  

   ing 
  much 
  flattened 
  above. 
  

  

  Descriptiotis 
  of 
  Neiv 
  fresh-water 
  Shells 
  which 
  inhabit 
  Ja- 
  

   maica. 
  By 
  C. 
  B. 
  Adams. 
  April, 
  1851. 
  

  

  Physa 
  Jamaicensis. 
  Shell 
  long 
  ovate, 
  acuminate 
  : 
  brown- 
  

   ish 
  horn 
  color 
  : 
  with 
  microscopic 
  striae 
  of 
  growth, 
  and 
  some 
  

   lightly 
  impressed 
  microscopic 
  spiral 
  strife 
  : 
  apex 
  acute 
  : 
  spire 
  

   well 
  lengthened, 
  with 
  the 
  outlines 
  slightly 
  curvilinear, 
  with 
  a 
  

   well 
  impressed 
  suture 
  : 
  aperture 
  long 
  ovate 
  : 
  lip 
  thin. 
  

  

  Length 
  of 
  aperture 
  .32 
  inch 
  ; 
  total 
  length 
  .48 
  inch 
  ; 
  breadth 
  

   .25 
  inch. 
  

  

  This 
  species 
  was 
  found 
  plentifully 
  in 
  a 
  tank 
  at 
  Malvern, 
  

   more 
  than 
  1000 
  feet 
  high, 
  in 
  the 
  isolated 
  group 
  of 
  the 
  St. 
  

   Cruz 
  Mountains 
  in 
  St. 
  Elizabeth. 
  The 
  structure 
  of 
  the 
  coun- 
  

   try 
  for 
  many 
  miles 
  in 
  every 
  direction 
  is 
  such 
  that 
  no 
  water 
  is 
  

   ever 
  seen 
  standing 
  on 
  the 
  surface. 
  Through 
  innumerable 
  sub- 
  

   terranean 
  fissures 
  rain 
  immediately 
  percolates 
  to 
  unseen 
  depths. 
  

   Artificial 
  tanks 
  are 
  therefore 
  the 
  only 
  places 
  where 
  fresh 
  water 
  

  

  