﻿648 
  MK. 
  J. 
  W. 
  GREGORY 
  ON 
  CYSTECHINUS 
  CRASSUS 
  

  

  Its 
  occurrence 
  below 
  the 
  base 
  of 
  the 
  Coral 
  limestone 
  is, 
  moreover, 
  

   quite 
  in 
  harmony 
  with 
  this 
  view. 
  The 
  evidence 
  of 
  the 
  Mollusca 
  of 
  

   the 
  Coral 
  limestone 
  shows 
  that 
  this 
  rock 
  is 
  of 
  Pleistocene 
  age 
  : 
  if 
  

   therefore 
  we 
  accept 
  the 
  conclusion 
  * 
  of 
  Mr. 
  Jukes-Browne 
  and 
  Prof. 
  

   Harrison 
  that 
  the 
  deposit 
  is 
  part 
  of 
  a 
  raised 
  ocean-bed, 
  then 
  it 
  is 
  

   not 
  improbable 
  that 
  the 
  higher 
  beds 
  of 
  the 
  Radiolarian 
  series 
  did 
  not 
  

   much 
  precede 
  the 
  foundation 
  of 
  the 
  coral-reefs 
  that 
  grew 
  over 
  them 
  

   on 
  their 
  elevation 
  into 
  a 
  shallow 
  sea. 
  

  

  But 
  in 
  addition 
  to 
  the 
  question 
  of 
  age, 
  Cystechinus 
  crassus 
  throws 
  

   considerable 
  light 
  upon 
  the 
  origin 
  of 
  the 
  Radiolarian. 
  deposits 
  and 
  

   the 
  depth 
  at 
  which 
  they 
  were 
  formed. 
  Messrs. 
  Jukes-Browne 
  and 
  

   Harrison 
  have 
  recently 
  adduced 
  the 
  Radiolarian 
  beds 
  as 
  an 
  instance 
  

   of 
  the 
  elevation 
  of 
  deep-sea 
  deposits 
  above 
  the 
  sea, 
  in 
  reply 
  to 
  the 
  

   statement 
  of 
  the 
  advocates 
  of 
  the 
  permanence 
  of 
  oceans 
  and 
  conti- 
  

   nents 
  that 
  such 
  has 
  never 
  occurred. 
  This 
  Radiolarian 
  ooze, 
  according 
  

   to 
  the 
  authors 
  named 
  t, 
  gives 
  evidence 
  of 
  a 
  complete 
  interchange 
  of 
  

   continental 
  and 
  oceanic 
  conditions 
  in 
  Tertiary 
  times 
  ; 
  for 
  the 
  un- 
  

   derlying 
  sandstones 
  and 
  shales 
  imply 
  the 
  close 
  proximity 
  of 
  a 
  con- 
  

   tinent 
  during 
  their 
  formation, 
  while 
  the 
  chalky 
  series 
  proves 
  the 
  

   subsequent 
  conversion 
  of 
  this 
  sea 
  into 
  an 
  oceanic 
  area. 
  Hackel, 
  

   moreover, 
  says 
  $ 
  that 
  the 
  Barbadian 
  deposits 
  are 
  to 
  be 
  regarded 
  as 
  

   pure 
  Radiolarian 
  ooze 
  in 
  the 
  fossil 
  condition, 
  and 
  limits 
  the 
  term 
  

   Radiolarian 
  ooze 
  to 
  the 
  deposits 
  formed 
  at 
  great 
  depths 
  ; 
  and 
  he 
  

   further 
  points 
  out 
  § 
  that 
  the 
  fossil 
  Radiol 
  aria 
  of 
  Barbados 
  are 
  most 
  

   nearly 
  allied 
  to 
  those 
  of 
  the 
  most 
  abyssal 
  fauna, 
  in 
  which 
  conclu- 
  

   sion 
  he 
  is 
  supported 
  by 
  the 
  observations 
  of 
  Dr. 
  Teuscher 
  ||. 
  

  

  The 
  discovery 
  of 
  a 
  species 
  of 
  Cystechinus 
  in 
  these 
  deposits 
  is 
  

   therefore 
  of 
  interest 
  as 
  confirmatory 
  of 
  these 
  opinions 
  : 
  Cystechinus 
  

   is 
  one 
  of 
  the 
  most 
  tj-pical 
  of 
  deep-sea 
  Echinoids 
  ; 
  thus, 
  for 
  example, 
  

   ISTeumayr 
  quotes 
  it 
  with 
  a 
  few 
  other 
  genera 
  as 
  never 
  found 
  above 
  the 
  

   1000-fathom 
  line. 
  The 
  case 
  would 
  have 
  been 
  quite 
  as 
  strong 
  had 
  the 
  

   species 
  belonged 
  to 
  Calymne, 
  as 
  at 
  first 
  thought, 
  rather 
  than 
  Cyst- 
  

   echinus, 
  as 
  the 
  former 
  genus 
  has 
  only 
  been 
  found 
  at 
  a 
  depth 
  of 
  2650 
  

   fathoms. 
  Prof. 
  A. 
  Agassiz 
  attributes 
  ^1 
  to 
  Calymne 
  a 
  range 
  of 
  620- 
  

   2650 
  fathoms 
  ; 
  but 
  this 
  is 
  probably 
  a 
  misprint, 
  as 
  it 
  was 
  only 
  once 
  

   met 
  with, 
  and 
  the 
  locality, 
  it 
  may 
  be 
  mentioned, 
  was 
  not 
  Payal 
  in 
  

   the 
  Azores, 
  as 
  stated 
  throughout 
  the 
  ' 
  Challenger 
  ' 
  Echinoid 
  Report, 
  

   but 
  at 
  Station 
  53, 
  on 
  the 
  voyage 
  between 
  Halifax 
  and 
  Bermuda. 
  

   Sir 
  "Wyville 
  Thomson, 
  who 
  founded 
  the 
  genus 
  and 
  species, 
  has 
  fully 
  

   described 
  the 
  discovery 
  of 
  the 
  specimens 
  **, 
  and 
  his 
  account 
  is 
  con- 
  

   firmed 
  in 
  the 
  official 
  narrative 
  of 
  the 
  expedition 
  tt- 
  

  

  * 
  Jukes-Browne 
  and 
  Harrison, 
  op. 
  cit. 
  p. 
  367. 
  

  

  t 
  Jukes-Browne 
  and 
  Harrison, 
  op. 
  cit. 
  p. 
  607. 
  

  

  \ 
  E. 
  Hackel, 
  op. 
  cit. 
  pp. 
  clvi, 
  clvii. 
  

  

  § 
  E. 
  Hackel, 
  " 
  Entwurf 
  eines 
  Eadiolarien-Systems 
  auf 
  Grund 
  von 
  Studien 
  

   der 
  Challenger-Radiolarien," 
  Jena. 
  Zeitschr. 
  f. 
  Naturwiss. 
  xv. 
  1881, 
  p. 
  422. 
  

  

  || 
  E. 
  Hackel, 
  Chall. 
  Rep. 
  vol. 
  xviii. 
  pt. 
  1, 
  p. 
  clxxv. 
  

  

  "H 
  A. 
  Agassiz, 
  op. 
  cit. 
  p. 
  218. 
  

  

  *# 
  Wyv. 
  Thomson, 
  op. 
  cit. 
  p. 
  206. 
  

  

  ft 
  "Report 
  on 
  the 
  Scientific 
  Results 
  of 
  the 
  Voyage 
  of 
  H.M.S. 
  ' 
  Challenger' 
  

   during 
  the 
  years 
  1873-6." 
  Narrative, 
  vol. 
  i. 
  pt. 
  i. 
  (London, 
  1885), 
  p. 
  161. 
  

  

  