﻿38 
  Prof. 
  C. 
  W. 
  Thomson 
  on 
  the 
  [Nov. 
  26, 
  

  

  some 
  cases 
  to 
  about 
  twenty 
  percent.) 
  of 
  fine 
  granular 
  matter, 
  which 
  fills 
  

   the 
  shells 
  and 
  the 
  interstices 
  between 
  them, 
  and 
  forms 
  a 
  kind 
  of 
  matrix 
  

   or 
  cement. 
  This 
  granular 
  substance 
  is, 
  like 
  the 
  shells, 
  calcareous, 
  dis- 
  

   appears 
  g 
  in 
  weak 
  acid 
  to 
  a 
  small 
  insoluble 
  residue 
  ; 
  with 
  a 
  low 
  micro- 
  

   scopic 
  power 
  it 
  appears 
  amorphous, 
  aud 
  it 
  is 
  likely 
  to 
  be 
  regarded, 
  at 
  first 
  

   sight, 
  as 
  a 
  paste 
  made 
  up 
  of 
  the 
  ultimate 
  calcareous 
  particles 
  of 
  the 
  dis- 
  

   integrated 
  shells 
  ; 
  but 
  under 
  a 
  higher 
  power 
  it 
  is 
  found 
  to 
  consist 
  almost 
  

   entirely 
  of 
  " 
  coccoliths 
  " 
  and 
  " 
  rhabdoliths." 
  I 
  need 
  scarcely 
  enter 
  here 
  

   into 
  a 
  detailed 
  descriptiou 
  of 
  these 
  singular 
  bodies, 
  which 
  have 
  already 
  been 
  

   carefully 
  studied 
  by 
  Huxley, 
  Sorby, 
  Griimbel, 
  Haeckel, 
  Carter, 
  Oscar 
  Schmidt, 
  

   TVallich, 
  and 
  others. 
  1 
  need 
  only 
  state 
  that 
  I 
  believe 
  our 
  observations 
  

   have 
  placed 
  it 
  beyond 
  a 
  doubt 
  that 
  the 
  " 
  coccoliths 
  " 
  are 
  the 
  separated 
  ele- 
  

   ments 
  of 
  a 
  peculiar 
  calcareous 
  armature 
  which 
  covers 
  certain 
  spherical 
  

   bodies 
  (the 
  " 
  coccospheres 
  " 
  of 
  Dr. 
  WalMch). 
  The 
  rhabdoliths 
  are 
  the 
  like 
  

   elements 
  of 
  the 
  armature 
  of 
  extremely 
  beautiful 
  little 
  bodies, 
  of 
  which 
  

   two 
  forms 
  are 
  represented 
  in 
  PI. 
  III. 
  figs. 
  3 
  & 
  4, 
  which 
  have 
  been 
  first 
  

   observed 
  by 
  Mr. 
  Murray 
  and 
  naturally 
  called 
  by 
  him 
  " 
  rhabdospheres." 
  

   Coccospheres 
  and 
  rhabdospheres 
  live 
  abundantly 
  on 
  the 
  surface, 
  especially 
  

   in 
  warmer 
  seas. 
  If 
  a 
  bucket 
  of 
  water 
  be 
  allowed 
  to 
  stand 
  over 
  night 
  

   with 
  a 
  few 
  pieces 
  of 
  thread 
  in 
  it, 
  on 
  examining 
  the 
  threads 
  carefully 
  

   many 
  examples 
  may 
  usually 
  be 
  found 
  attached 
  to 
  them 
  ; 
  but 
  Mr. 
  Murray 
  

   has 
  found 
  an 
  unfailing 
  supply 
  of 
  all 
  forms 
  in 
  the 
  stomachs 
  of 
  Salpce. 
  

  

  What 
  these 
  coccospheres 
  and 
  rhabdospheres 
  are, 
  we 
  are 
  not 
  yet 
  in 
  a 
  

   position 
  to 
  say 
  with 
  certainty 
  ; 
  but 
  our 
  strong 
  impression 
  is 
  that 
  they 
  are 
  

   either 
  Algae 
  of 
  a 
  peculiar 
  form, 
  or 
  the 
  reproductive 
  gemmules 
  or 
  the 
  

   sporangia 
  of 
  some 
  minute 
  organism, 
  probably 
  an 
  Alga 
  ; 
  in 
  which 
  latter 
  

   case 
  the 
  coccoliths 
  and 
  rhabdoliths 
  might 
  be 
  regarded 
  as 
  representing 
  in 
  

   position 
  and 
  functiou 
  the 
  " 
  amphidisci 
  " 
  on 
  the 
  surface 
  of 
  the 
  gemmules 
  

   of 
  Spongilla, 
  or 
  the 
  spiny 
  facets 
  on 
  the 
  zygospores 
  of 
  many 
  of 
  the 
  Des- 
  

   mideee. 
  There 
  are 
  many 
  forms 
  of 
  coccoliths 
  and 
  rhabdoliths, 
  and 
  many 
  

   of 
  these 
  are 
  so 
  distinct 
  that 
  they 
  evidently 
  indicate 
  different 
  species. 
  Mr. 
  

   Murray 
  believes, 
  however, 
  that 
  only 
  one 
  form 
  is 
  met 
  with 
  on 
  one 
  sphere 
  ; 
  

   and 
  that, 
  in 
  order 
  to 
  produce 
  the 
  numerous 
  forms 
  figured 
  by 
  Haeckel 
  and 
  

   Oscar 
  Schmidt, 
  all 
  of 
  which, 
  and 
  many 
  additional 
  varieties, 
  he 
  has 
  

   observed, 
  the 
  spheres 
  must 
  vary 
  in 
  age 
  and 
  development, 
  or 
  in 
  kind. 
  

   Their 
  constant 
  presence 
  in 
  the 
  surface-net, 
  in 
  surface-water 
  drawn 
  in 
  a 
  

   bucket, 
  and 
  in 
  the 
  stomachs 
  of 
  surface-animals, 
  sufficiently 
  proves 
  that, 
  

   like 
  the 
  ooze-forming 
  Foraminif 
  era, 
  the 
  coccoliths 
  and 
  rhabdoliths, 
  which 
  

   enter 
  so 
  largely 
  into 
  the 
  composition 
  of 
  the 
  recent 
  deep-sea 
  calcareous 
  

   formations,, 
  live 
  on 
  the 
  surface 
  and 
  at 
  intermediate 
  depths, 
  and 
  sink 
  to 
  

   the 
  bottom 
  after 
  death. 
  Coccospheres 
  and 
  rhabdospheres 
  have 
  a 
  very 
  wide, 
  

   but 
  not 
  an 
  unlimited, 
  distribution. 
  From 
  the 
  Cape 
  of 
  G-ood 
  Hope 
  they 
  

   rapidly 
  decreased 
  in 
  number 
  on 
  the 
  surface 
  and 
  at 
  the 
  bottom, 
  as 
  we 
  

   progressed 
  southwards. 
  The 
  proportion 
  of 
  their 
  remains 
  in 
  the 
  Glo- 
  

   bigerina-ooze 
  near 
  the 
  Crbzets 
  and 
  Prince 
  Edward 
  Island 
  was 
  com- 
  

  

  