﻿FEOM 
  THE 
  EADIOLAEIAST 
  MAELS 
  OF 
  BAEBADOS. 
  645 
  

  

  the 
  tests 
  are 
  flexible, 
  composed 
  of 
  hexagonal 
  plates, 
  provided 
  with 
  

   apetaloid 
  ambulacra, 
  with 
  a 
  single 
  pore 
  in 
  each 
  plate 
  of 
  the 
  ambu- 
  

   lucra, 
  and 
  an 
  epistroma 
  of 
  minute 
  granulation 
  with 
  small 
  sparsely 
  

   scattered 
  tubercles 
  exactly 
  like 
  those 
  of 
  some 
  of 
  the 
  Pcrischoechinidae, 
  

   such 
  as 
  Palcecliinus. 
  This 
  is 
  not 
  the 
  time 
  to 
  discuss 
  the 
  meaning 
  of 
  

   these 
  resemblances, 
  but 
  they 
  are 
  too 
  striking 
  to 
  be 
  wholly 
  ignored. 
  

  

  As 
  Cystecliinus 
  crassus 
  adds 
  but 
  little 
  to 
  our 
  knowledge 
  of 
  the 
  

   morphology 
  of 
  the 
  genus, 
  the 
  chief 
  interest 
  of 
  the 
  specimen 
  depends 
  

   on 
  the 
  place 
  of 
  its 
  occurrence 
  and 
  on 
  the 
  light 
  it 
  throws 
  upon 
  the 
  

   age 
  and 
  origin 
  of 
  the 
  classical 
  Eadiolarian 
  deposits 
  of 
  Barbados 
  

   and 
  some 
  questions 
  connected 
  therewith. 
  

  

  The 
  Island 
  of 
  Barbados 
  is 
  composed 
  of 
  three 
  distinct 
  sets 
  of 
  beds 
  — 
  

   the 
  Scotland 
  formation 
  ; 
  the 
  Eadiolarian 
  deposits 
  ; 
  and 
  the 
  Coralline 
  

   limestone. 
  The 
  term 
  Scotland 
  formation 
  was 
  applied 
  by 
  Sir 
  E. 
  

   Schomburgk 
  * 
  to 
  the 
  beds 
  in 
  the 
  island 
  below 
  the 
  Coralline 
  lime- 
  

   stone, 
  and 
  including 
  the 
  Eadiolarian 
  deposits 
  ; 
  but 
  as 
  we 
  are 
  informed 
  

   by 
  Mr. 
  J 
  ukes-Browne 
  and 
  Prof. 
  Harrison 
  f 
  that 
  they 
  will 
  shortly 
  be 
  

   able 
  to 
  prove 
  that 
  the 
  latter 
  are 
  quite 
  distinct 
  and 
  overlie 
  the 
  other 
  

   un 
  conformably, 
  the 
  term 
  may 
  be 
  restricted 
  to 
  the 
  lower 
  beds. 
  As 
  

   such 
  it 
  would 
  include 
  a 
  group 
  of 
  strata 
  which 
  Sir 
  E. 
  Schomburgk 
  

   describes 
  J 
  as 
  composed 
  " 
  of 
  siliceous 
  sandstone, 
  intermixed 
  with 
  

   ferruginous 
  matter, 
  calcareous 
  sandstones, 
  siliceous 
  limestones, 
  dif- 
  

   ferent 
  kinds 
  of 
  clay, 
  selenite, 
  and 
  earthy 
  marls, 
  frequently 
  containing 
  

   fragments 
  of 
  pumice, 
  strata 
  of 
  volcanic 
  ashes, 
  seams 
  of 
  bitumen, 
  and 
  

   springs 
  of 
  petroleum 
  (Barbados 
  tar)." 
  The 
  rocks 
  of 
  this 
  formation 
  

   appear 
  to 
  form 
  the 
  whole 
  substructure 
  of 
  the 
  island, 
  though 
  they 
  

   only 
  appear 
  through 
  the 
  capping 
  of 
  coral 
  limestone 
  over 
  one 
  seventh 
  

   of 
  the 
  total 
  area. 
  Their 
  age 
  has, 
  unfortunately, 
  never 
  been 
  conclu- 
  

   sively 
  settled. 
  Three 
  new 
  species 
  were 
  found 
  in 
  these 
  beds 
  by 
  Sir 
  

   E. 
  Schomburgk 
  and 
  described 
  by 
  Porbes 
  § 
  ; 
  the 
  species 
  were 
  as 
  fol- 
  

   lows 
  : 
  — 
  

  

  (1) 
  Scalaria 
  Ehrenhergi, 
  Pbs., 
  found 
  in 
  the 
  siliceous 
  limestone 
  of 
  

   Bissex 
  hill. 
  Though 
  Porbes 
  remarked 
  the 
  close 
  resemblance 
  of 
  this 
  

   specimen 
  to 
  the 
  S. 
  crassilabrum, 
  Sow., 
  of 
  the 
  Philippines 
  and 
  Central 
  

   America, 
  he 
  considered 
  it 
  as 
  probably 
  of 
  Miocene 
  age. 
  

  

  (2) 
  Nucula 
  Packeri, 
  Pbs. 
  Allied 
  to 
  some 
  tropical, 
  subtropical, 
  

   and 
  Crag 
  forms. 
  

  

  (3) 
  Nucula 
  ScliomburgTci, 
  Pbs. 
  A 
  species 
  attributed 
  to 
  a 
  small 
  

   section 
  of 
  the 
  genus, 
  which 
  ranges 
  from 
  the 
  Cretaceous 
  upwards, 
  

   but 
  of 
  which 
  the 
  nearest 
  ally 
  is 
  probably 
  Nucula 
  Cobholdiaz 
  of 
  the 
  

   Crag. 
  

  

  So 
  far 
  as 
  I 
  am 
  aware 
  this 
  is 
  the 
  only 
  direct 
  palseontological 
  evidence, 
  

   except 
  for 
  the 
  Eadiolaria, 
  as 
  to 
  the 
  age 
  of 
  the 
  beds, 
  and 
  it 
  was 
  upon 
  

   this 
  that 
  Porbes 
  based 
  his 
  suggestion 
  that 
  they 
  were 
  Miocene 
  ||. 
  

  

  * 
  Sir 
  Kob. 
  H. 
  Schomburgk, 
  ' 
  The 
  History 
  of 
  Barbadoes 
  ' 
  (London, 
  1847), 
  

   p. 
  534. 
  

  

  t 
  J. 
  B. 
  Harrison 
  and 
  A. 
  J. 
  Jukes-Browne, 
  " 
  Origin 
  of 
  the 
  Eadiolarian 
  

   Earth 
  of 
  Barbadoes," 
  Nature, 
  vol. 
  xxxix. 
  14th 
  Feb. 
  1889.. 
  p. 
  367. 
  

  

  X 
  Schomburgk, 
  op. 
  cit. 
  p. 
  534. 
  § 
  Schomburgk, 
  op. 
  cit. 
  pp. 
  565-7. 
  

  

  ]| 
  Schomburgk, 
  op. 
  cit. 
  pp. 
  556-565, 
  566. 
  

  

  