﻿STRUCTURE 
  AND 
  CLASSIFICATION 
  OF 
  THE 
  ARAOHNIDA. 
  213 
  

  

  spiders^ 
  the 
  book-scorpions, 
  the 
  harvestmeii, 
  and 
  the 
  water- 
  

   mites. 
  

  

  The 
  strange 
  Nobody-Crabs 
  or 
  Pycnogonids 
  occupy 
  a 
  place 
  

   on 
  the 
  ascending 
  half 
  of 
  the 
  arc 
  below 
  the 
  Eurypterines 
  and 
  

   Limnlus. 
  They 
  are 
  strangely 
  modified 
  and 
  degenerate, 
  but 
  

   seem 
  to 
  be 
  (as 
  explained 
  in 
  the 
  systematic 
  review) 
  the 
  

   remnant 
  of 
  an 
  Arachnidan 
  group 
  holding 
  the 
  same 
  relation 
  

   to 
  the 
  scorpions 
  which 
  the 
  Ltemodipoda 
  hold 
  to 
  the 
  Pod- 
  

   ophthalmate 
  Crustacea. 
  

  

  We 
  have 
  now 
  to 
  offer 
  a 
  classification 
  of 
  the 
  Arachnida, 
  and 
  

   to 
  pass 
  in 
  review 
  the 
  larger 
  groups, 
  with 
  a 
  brief 
  statement 
  of 
  

   their 
  structural 
  characteristics. 
  

  

  In 
  the 
  bibliography 
  at 
  the 
  close 
  of 
  this 
  article 
  (referred 
  to 
  

   by 
  leaded 
  Ai-abic 
  numerals 
  in 
  brackets 
  throughout 
  these 
  

   pages) 
  the 
  titles 
  of 
  works 
  are 
  given 
  which 
  contain 
  detailed 
  

   information 
  as 
  to 
  the 
  genera 
  and 
  species 
  of 
  each 
  order 
  or 
  sub- 
  

   order, 
  their 
  geographical 
  distribution, 
  and 
  their 
  habits 
  and 
  

   economy 
  so 
  far 
  as 
  they 
  have 
  been 
  ascertained. 
  The 
  limits 
  of 
  

   space 
  do 
  not 
  permit 
  of 
  a 
  fuller 
  treatment 
  of 
  those 
  matters 
  

   here. 
  

  

  Tabular 
  Classification 
  ^ 
  of 
  the 
  Aeachnida. 
  

  

  Class 
  AEACHNIDA. 
  

  

  Grade 
  A. 
  ANOMOMERISTIC 
  A. 
  

   Sub-class 
  TRILOBIT^. 
  

  

  Orders. 
  Not 
  satisfactorily 
  determined. 
  

  

  ^ 
  Tlie 
  writer 
  is 
  indebted 
  to 
  Mr. 
  R. 
  I. 
  Pocock, 
  assistant 
  in 
  the 
  Natural 
  

   History 
  departments 
  of 
  llie 
  British 
  Museum, 
  for 
  valuable 
  assistance 
  in 
  the 
  

   preparation 
  of 
  tiiis 
  article 
  and 
  for 
  the 
  classification 
  and 
  definition 
  of 
  tiie 
  

   groups 
  of 
  Eu-arachnida 
  here 
  given. 
  The 
  general 
  scheme 
  and 
  some 
  of 
  the 
  

   details 
  have 
  been 
  brought 
  by 
  the 
  writer 
  into 
  agreement 
  with 
  the 
  views 
  

   maintained 
  in 
  this 
  article. 
  Mr. 
  Pocock 
  accepts 
  those 
  views 
  in 
  all 
  essential 
  

   points, 
  and 
  has, 
  as 
  a 
  special 
  student 
  of 
  the 
  Arachnida, 
  given 
  to 
  them 
  valuable 
  

   expansion 
  and 
  confirmation. 
  

  

  VOL. 
  48, 
  PART 
  2. 
  NEW 
  SERIES. 
  15 
  

  

  