﻿236 
  Dr. 
  W. 
  B. 
  Carpenter 
  on 
  the 
  Nature 
  of 
  the 
  [Feb. 
  4, 
  

  

  the 
  surface 
  or 
  sub-surface 
  stratum, 
  and 
  was 
  merely 
  preparatory 
  to 
  the 
  

   deposit 
  of 
  the 
  shells 
  on 
  the 
  sea-bed, 
  there 
  should 
  have 
  been 
  a 
  corre- 
  

   spondence 
  in 
  size 
  and 
  condition 
  between 
  the 
  floating 
  shells 
  and 
  those 
  

   lying 
  on 
  the 
  bottom 
  immediately 
  beneath 
  them 
  ; 
  whereas 
  no 
  contrast 
  

   could 
  be 
  more 
  complete, 
  the 
  impression 
  given 
  by 
  the 
  superficial 
  aspects 
  

   they 
  respectively 
  presented 
  having 
  been 
  fully 
  confirmed 
  by 
  subsequent 
  

   careful 
  investigation. 
  

  

  Prof. 
  Wyville 
  Thomson 
  and 
  Mr. 
  Murray, 
  who 
  notice 
  this 
  contrast, 
  

   attribute 
  it 
  to 
  the 
  death 
  of 
  the 
  shells 
  which 
  have 
  subsided 
  to 
  the 
  bottom 
  — 
  

   being 
  apparently 
  unaware 
  that 
  the 
  observations 
  of 
  Dr. 
  Wallich, 
  with 
  

   which 
  my 
  own 
  are 
  in 
  entire 
  accordance, 
  leave 
  no 
  reasonable 
  ground 
  for 
  

   doubt 
  that 
  it 
  is 
  a 
  consequence 
  of 
  their 
  continued 
  life. 
  Tor 
  it 
  is 
  clearly 
  

   shown, 
  by 
  making 
  thin 
  transparent 
  sections 
  of 
  the 
  thick-shelled 
  Globi- 
  

   gerince 
  (an 
  operation 
  which 
  needs 
  a 
  dexterity 
  only 
  to 
  be 
  acquired 
  by 
  long 
  

   practice, 
  and 
  which 
  is 
  much 
  facilitated 
  by 
  an 
  ingenious 
  device 
  invented 
  

   by 
  Dr. 
  Wallich*), 
  that 
  the 
  change 
  of 
  external 
  aspect 
  is 
  due 
  to 
  the 
  

   remarkable 
  exogenous 
  deposit 
  (a, 
  rudiment 
  of 
  the 
  "intermediate 
  skeleton" 
  

   of 
  higher 
  Foraminifera) 
  which 
  is 
  formed, 
  after 
  the 
  full 
  growth 
  of 
  the 
  

   Globigerina 
  has 
  been 
  attained, 
  upon 
  the 
  outside 
  of 
  the 
  proper 
  chamber- 
  

   wall 
  — 
  so 
  completely 
  masking 
  its 
  pseudopodial 
  orifices, 
  that 
  Prof. 
  Huxley 
  at 
  

   one 
  time 
  denied 
  their 
  existence. 
  This 
  deposit 
  is 
  not 
  only 
  many 
  times 
  

   thicker 
  than 
  the 
  original 
  chamber-wall, 
  but 
  it 
  often 
  contains 
  flask-shaped 
  

   cavities 
  opening 
  from 
  the 
  exterior, 
  and 
  containing 
  sarcode 
  prolonged 
  into 
  

   it 
  from 
  the 
  sarcodic 
  investment 
  of 
  the 
  shell. 
  Illustrations 
  of 
  this 
  curious 
  

   structure 
  are 
  given 
  by 
  Dr. 
  "Wallich 
  in 
  figs. 
  17 
  and 
  18 
  of 
  Plate 
  vi. 
  of 
  his 
  

   4 
  North- 
  Atlantic 
  Sea-bed;' 
  and 
  I 
  here 
  subjoin 
  a 
  representation 
  of 
  it, 
  

   kindly 
  given 
  me 
  by 
  Dr. 
  Wallich 
  twelve 
  years 
  ago, 
  which 
  further 
  shows 
  

  

  Section 
  of 
  Shell 
  of 
  Globigerina, 
  showing 
  

   the 
  distinction 
  between 
  the 
  original 
  proper 
  

   wall 
  of 
  the 
  chambers 
  and 
  the 
  secondary 
  

   exogenous 
  deposit, 
  with 
  the 
  flask-shaped 
  

   cavities 
  in 
  the 
  latter 
  opening 
  externally 
  

   and 
  containing 
  sarcode 
  like 
  that 
  which 
  fills 
  

   the 
  chambers. 
  

  

  that 
  the 
  specimen 
  from 
  which 
  it 
  was 
  taken 
  had 
  both 
  its 
  chambers 
  and 
  

   the 
  flask-shaped 
  cavities 
  of 
  the 
  exogenous 
  deposit 
  filled 
  with 
  sarcode 
  not 
  

   distinguishable 
  in 
  any 
  respect 
  from 
  that 
  of 
  the 
  floating 
  specimens. 
  Prom 
  

   these 
  important 
  observations 
  (which 
  had 
  not 
  been 
  made 
  public 
  when 
  the 
  

   * 
  Ann. 
  & 
  Mag. 
  of 
  Natural 
  History, 
  1861, 
  viii. 
  p. 
  58. 
  

  

  