﻿196 
  P. 
  E. 
  Raymond 
  — 
  Beecher's 
  Classification 
  of 
  Trilobites. 
  

  

  Art. 
  XVIII. 
  — 
  Beecher's 
  Classification 
  of 
  Trilobites, 
  after 
  

   Twenty 
  Years 
  ; 
  by 
  Percy 
  E. 
  Raymond. 
  

  

  In 
  the 
  February 
  and 
  March 
  numbers 
  of 
  this 
  Journal 
  for 
  

   1897 
  appeared 
  the 
  two 
  parts 
  of 
  Professor 
  C. 
  E. 
  Beecher's 
  short 
  

   paper, 
  on 
  an 
  iL 
  Outline 
  of 
  a 
  Natural 
  Classification 
  of 
  the 
  Trilo- 
  

   bites." 
  The 
  classification 
  there 
  proposed, 
  modified 
  rather 
  by 
  

   curtailment 
  than 
  expansion, 
  appeared 
  again 
  in 
  the 
  Eastman 
  

   edition 
  of 
  Zittel's 
  Textbook 
  of 
  Paleontology 
  in 
  1900. 
  On 
  this 
  

   occasion, 
  just 
  twenty 
  years 
  later, 
  it 
  seems 
  fitting 
  to 
  inquire 
  how 
  

   Beecher's 
  work 
  has 
  stood 
  the 
  test 
  of 
  actual 
  use 
  and 
  I 
  wish 
  also 
  

   to 
  present 
  what 
  follows 
  as 
  a 
  slight 
  tribute 
  to 
  the 
  memory 
  of 
  

   my 
  revered 
  teacher. 
  Beecher 
  himself 
  regarded 
  this 
  classifica- 
  

   tion 
  only 
  as 
  an 
  outline, 
  and 
  often 
  expressed 
  the 
  wish 
  that 
  he 
  

   himself 
  or 
  some 
  other 
  person 
  could 
  find 
  the 
  time 
  to 
  elaborate 
  

   the 
  classification 
  in 
  the 
  same 
  manner 
  that 
  Professor 
  Schuchert 
  

   had 
  elaborated 
  his 
  earlier 
  outline 
  scheme 
  for 
  the 
  Brachiopoda. 
  

  

  Professor 
  Beecher's 
  untimely 
  death 
  just 
  seven 
  years 
  after 
  

   the 
  first 
  part 
  of 
  his 
  " 
  classification 
  " 
  was 
  printed 
  prevented 
  his 
  

   own 
  return 
  to 
  the 
  subject, 
  and 
  the 
  studies 
  and 
  contributions 
  

   of 
  other 
  writers 
  on 
  trilobites 
  during 
  these 
  twenty 
  years 
  have 
  

   dealt 
  usually 
  rather 
  with 
  single 
  species, 
  genera 
  or 
  families 
  than 
  

   with 
  the 
  subject 
  as 
  a 
  whole. 
  Numerous 
  objections 
  to 
  the 
  

   scheme 
  proposed 
  by 
  Beecher 
  have 
  appeared, 
  from 
  Pompeckj 
  

   in 
  1898 
  to 
  Swinnerton 
  in 
  1915, 
  the 
  objections 
  varying 
  in 
  

   strength 
  from 
  Wood's* 
  sweeping 
  remark 
  that 
  " 
  the 
  only 
  

   classification 
  of 
  Trilobites 
  which 
  can 
  be 
  adopted 
  is 
  a 
  division 
  

   into 
  families 
  " 
  to 
  Swinnerton's 
  statement 
  that 
  the 
  majority 
  of 
  

   new 
  trilobites 
  found 
  since 
  the 
  publication 
  of 
  the 
  classification 
  

   " 
  tit 
  into 
  it 
  without 
  difficulty 
  and 
  prove 
  that 
  to 
  a 
  large 
  extent 
  

   it 
  is 
  conceived 
  on 
  a 
  sound 
  basis. 
  A 
  few, 
  however, 
  do 
  not 
  fit 
  

   in, 
  and 
  have 
  therefore 
  revealed 
  its 
  weakness."f 
  

  

  The 
  most 
  grave 
  criticisms 
  of 
  the 
  classification 
  have 
  been 
  

   directed 
  against 
  the 
  first 
  of 
  the 
  three 
  orders, 
  the 
  Hypoparia. 
  

   It 
  will 
  be 
  remembered 
  that 
  Beecher's 
  classification 
  was 
  based 
  

   upon 
  observations 
  drawn 
  from 
  a 
  review 
  of 
  all 
  that 
  was 
  known 
  

   of 
  the 
  ontogeny 
  of 
  trilobites. 
  Since 
  the 
  young 
  of 
  practically 
  

   all 
  primitive 
  trilobites 
  lack 
  eyes 
  on 
  the 
  dorsal 
  side, 
  Beecher 
  

   grouped 
  all 
  trilobites 
  in 
  which 
  absence 
  of 
  eyes 
  was 
  a 
  primary 
  

   characteristic, 
  in 
  his 
  first 
  order, 
  Hypoparia. 
  Recent 
  studies 
  

   and 
  discoveries 
  have 
  led 
  a 
  number 
  of 
  investigators 
  to 
  the 
  con- 
  

   clusion 
  that 
  blindness 
  in 
  the 
  Agnostidae, 
  Eodiscidse, 
  Trinucleidse, 
  

   Raphiophoridse 
  and 
  Harpedidse 
  is 
  secondary 
  and 
  a 
  degenera- 
  

   tive, 
  not 
  primitive 
  characteristic. 
  If 
  their 
  position 
  is 
  well 
  

   taken, 
  then 
  the 
  order 
  should 
  disappear, 
  and 
  the 
  families 
  be 
  dis- 
  

   tributed 
  in 
  the 
  two 
  orders 
  which 
  remain. 
  A 
  second 
  change 
  

  

  * 
  The 
  Cambridge 
  Natural 
  History, 
  iv, 
  p. 
  244, 
  1909. 
  

   f 
  Geol. 
  Magazine, 
  Dec. 
  6, 
  ii, 
  p. 
  487, 
  1915. 
  

  

  