﻿324 
  J. 
  E. 
  MAKE 
  ON 
  THE 
  CAMBRIAN 
  AND 
  

  

  forms 
  which 
  do 
  not 
  occur 
  in 
  the 
  intermediate 
  beds 
  ; 
  secondly, 
  by 
  

   tracing 
  the 
  lateral 
  movements 
  of 
  the 
  forms 
  of 
  life, 
  and 
  discovering 
  

   them 
  in 
  earlier 
  beds 
  in 
  one 
  locality 
  than 
  in 
  another. 
  The 
  first 
  

   method 
  is 
  particularly 
  applicable 
  to 
  beds 
  deposited 
  in 
  deep 
  water, 
  the 
  

   second 
  to 
  those 
  deposited 
  in 
  water 
  nearer 
  the 
  sea-margin. 
  

  

  In 
  the 
  first 
  place, 
  which 
  beds 
  were 
  deposited 
  in 
  deep 
  water, 
  and 
  

   which 
  near 
  the 
  sea-margin 
  ? 
  I 
  have 
  previously 
  given 
  reasons 
  for 
  

   supposing 
  that 
  the 
  black 
  shales 
  of 
  the 
  Cambrian 
  and 
  Silurian 
  systems 
  

   were 
  deposited 
  in 
  comparatively 
  deep 
  water, 
  from 
  the 
  evidence 
  

   derived 
  from 
  the 
  eyes 
  of 
  the 
  Trilobites 
  contained 
  in 
  them. 
  Uemo- 
  

   pleurides 
  is 
  usually 
  characterized 
  by 
  very 
  large 
  eyes. 
  In 
  Jemtland, 
  

   however, 
  Dr. 
  Linnarsson 
  has 
  found 
  one 
  in 
  calcareous 
  beds, 
  but 
  

   it 
  has 
  small 
  eyes, 
  R. 
  micropJitJialmus, 
  Linnars. 
  (Geol. 
  Foren. 
  i 
  

   Stockh. 
  Porh. 
  1879, 
  p. 
  24:6). 
  These 
  black 
  sediments 
  are 
  found 
  also 
  

   over 
  a 
  very 
  large 
  area 
  ; 
  so 
  that 
  they 
  must 
  in 
  some 
  cases 
  at 
  least 
  have 
  

   been 
  deposited 
  several 
  hundred 
  miles 
  from 
  land. 
  How 
  are 
  we 
  to 
  

   account 
  for 
  the 
  fact 
  that 
  the 
  open 
  oceans 
  of 
  Cambrian 
  and 
  Silurian 
  

   times 
  received 
  these 
  mechanical 
  deposits, 
  whilst 
  the 
  open 
  seas 
  of 
  our 
  

   own 
  times 
  have 
  deposits 
  of 
  ooze 
  being 
  formed 
  in 
  them 
  ? 
  

  

  On 
  examining 
  the 
  list 
  of 
  stations 
  of 
  the 
  ' 
  Challenger' 
  voyage 
  given 
  

   by 
  Sir 
  \Yyville 
  Thomson 
  (Atlantic, 
  vol. 
  i. 
  p. 
  93), 
  it 
  will 
  be 
  remarked 
  

   at 
  once 
  that 
  in 
  very 
  few 
  places 
  is 
  mechanical 
  deposit 
  formed 
  at 
  a 
  

   greater 
  distance 
  than 
  100 
  miles 
  from 
  land, 
  nearly 
  all 
  the 
  deposits 
  

   at 
  this 
  distance 
  being 
  grey 
  or 
  red 
  ooze, 
  excerpt 
  volcanic 
  deposits, 
  such 
  

   as 
  may 
  be 
  formed 
  b} 
  T 
  submarine 
  volcanoes. 
  Off 
  Cape 
  San 
  Antonio, 
  

   however, 
  near 
  Bahia, 
  mud 
  is 
  found 
  at 
  considerable 
  distances 
  over 
  

   100 
  miles 
  from 
  land 
  : 
  thus 
  at 
  station 
  127 
  mud 
  occurs 
  at 
  a 
  distance 
  

   of 
  120 
  miles, 
  at 
  station 
  12-1 
  at 
  251 
  miles, 
  and 
  at 
  station 
  120 
  at 
  

   360 
  miles 
  from 
  this 
  cape 
  ; 
  so 
  that 
  there 
  is 
  a 
  continuous 
  deposit 
  of 
  

   mud 
  being 
  formed 
  here 
  to 
  a 
  distance 
  of 
  between 
  three 
  and 
  four 
  

   hundred 
  miles 
  from 
  land. 
  The 
  rock 
  along 
  this 
  coast 
  is 
  gneiss 
  (cf. 
  

   Darwin, 
  Geol. 
  Obs. 
  p. 
  422) 
  ; 
  so 
  that 
  the 
  great 
  distance 
  to 
  which 
  

   mud 
  is 
  carried 
  here, 
  seems 
  to 
  be 
  due 
  to 
  the 
  fact 
  that 
  this 
  mud 
  is 
  

   directly 
  derived 
  from 
  the 
  decomposition 
  of 
  felspar 
  of 
  metamorpJiic 
  

   roclcs, 
  and 
  not 
  indirectly 
  by 
  the 
  denudation 
  of 
  other 
  unaltered 
  sedi- 
  

   mentary 
  rocks 
  ; 
  and 
  it 
  is 
  therefore 
  in 
  an 
  extremely 
  fine 
  state 
  of 
  divi- 
  

   sion. 
  But 
  the 
  land 
  which 
  bounded 
  the 
  Cambrian 
  and 
  Silurian 
  oceans 
  

   must 
  have 
  been 
  made 
  up 
  of 
  such 
  felspathic 
  rocks 
  ; 
  for 
  we 
  find 
  that 
  

   the 
  greater 
  part 
  of 
  the 
  Precambrian 
  rocks 
  had 
  undergone 
  extensive 
  

   regional 
  metamorphism 
  before 
  the 
  deposition 
  of 
  the 
  earliest 
  Cambrian 
  

   rocks, 
  and 
  this 
  seems 
  to 
  account 
  for 
  the 
  presence 
  of 
  fine 
  deposits 
  of 
  

   mechanical 
  origin 
  over 
  a 
  very 
  large 
  area 
  in 
  Cambrian 
  and 
  Silurian 
  

   times. 
  

  

  In 
  a 
  former 
  paper 
  (Q. 
  J. 
  G. 
  S. 
  Nov. 
  1880, 
  p. 
  606) 
  I 
  referred 
  to 
  

   the 
  occurrence 
  of 
  migrations 
  in 
  Bohemia, 
  treated 
  of 
  by 
  M 
  Barrande 
  

   (DeX 
  des 
  Colonies, 
  pt. 
  iii.), 
  as 
  evidenced 
  by 
  the 
  occurrence 
  of 
  deep- 
  

   water 
  forms 
  in 
  D. 
  d. 
  1, 
  d. 
  3, 
  and 
  d. 
  5, 
  which 
  do 
  not 
  occur 
  in 
  D. 
  d* 
  

   2 
  and 
  d. 
  4. 
  A 
  precisely 
  analogous 
  case 
  is 
  found 
  in 
  Sweden. 
  The 
  

   red 
  shale 
  band 
  in 
  the 
  Orthoceras-limestonc 
  of 
  Skaltungbyn 
  (Dale- 
  

   carlia), 
  the 
  grey 
  calcareous 
  shales 
  of 
  Fjecka 
  and 
  Kargarde, 
  and 
  the 
  

  

  