﻿240 
  E. 
  UAY 
  LANKESTER. 
  

  

  the 
  Solifugae 
  ai-e 
  connected 
  in 
  origin 
  with 
  the 
  Pedipalpi. 
  

   The 
  appearance 
  of 
  trachea 
  in 
  place 
  of 
  lung-sacs 
  cannot 
  be 
  

   regarded 
  as 
  a 
  starting-point 
  for 
  a 
  new 
  line 
  of 
  descent 
  com- 
  

   prising 
  all 
  the 
  tracheate 
  forms; 
  trachese 
  seem 
  to 
  have 
  de- 
  

   veloped 
  independently 
  in 
  different 
  lines 
  of 
  descent. 
  On 
  the 
  

   whole, 
  the 
  Epectinata 
  are 
  highly 
  specialised 
  and 
  degenerate 
  

   forms, 
  though 
  there 
  are 
  few, 
  if 
  any, 
  animals 
  which 
  surpass 
  

   the 
  spiders 
  in 
  rapidity 
  of 
  movement, 
  deadliness 
  of 
  attack, 
  and 
  

   constructive 
  instincts. 
  

  

  Order 
  2. 
  Pepipalpi 
  (Figs. 
  54 
  to 
  59). 
  — 
  Appendages 
  of 
  first 
  

   pair 
  bisegmented, 
  without 
  poison 
  gland; 
  of 
  second 
  pair 
  

   prehensile, 
  their 
  basal 
  segments 
  underlying 
  the 
  proboscis, 
  

   and 
  furnished 
  witli 
  steruo-coxal 
  (maxillary) 
  process, 
  the 
  

   apical 
  segment 
  tipped 
  with 
  a 
  single 
  movable 
  or 
  immovable 
  

   claw; 
  appendages 
  of 
  third 
  pair 
  different 
  from 
  the 
  remainder, 
  

   tactile 
  in 
  function, 
  with 
  at 
  least 
  the 
  apical 
  segment 
  many- 
  

   jointed 
  and 
  clawless. 
  The 
  ventral 
  surface 
  of 
  the 
  prosoma 
  

   bears 
  prosternal, 
  metasternal, 
  and 
  usually 
  mesosternal 
  chitin 
  

   plates 
  (Fig. 
  55). 
  A 
  narrow 
  prtegenital 
  somite 
  is 
  present 
  

   between 
  opisthosoma 
  and 
  prosoma 
  (Figs. 
  55, 
  57). 
  Opistho- 
  

   soma 
  consisting 
  of 
  eleven 
  somites, 
  almost 
  wholly 
  without 
  

   visible 
  appendages. 
  Intromittent 
  organ 
  of 
  male 
  beneath 
  the 
  

   genital 
  operculum 
  (= 
  sternum 
  of 
  the 
  first 
  somite 
  of 
  opistho- 
  

   soma). 
  

  

  Note. 
  — 
  The 
  possibility 
  of 
  another 
  interpretation 
  of 
  the 
  

   anterior 
  somites 
  of 
  the 
  mesosoma 
  and 
  the 
  prsegenital 
  somite 
  

   must 
  be 
  borne 
  in 
  mind. 
  Possibly, 
  though 
  not 
  probably, 
  the 
  

   somites 
  carrying 
  the 
  two 
  lung-sacs 
  correspond 
  to 
  the 
  first 
  two 
  

   lung-bearing 
  somites 
  of 
  Scorpio, 
  and 
  it 
  is 
  the 
  genital 
  opening 
  

   which 
  has 
  shifted. 
  The 
  same 
  caution 
  applies 
  in 
  the 
  case 
  of 
  

   the 
  Aranese. 
  Excalation 
  of 
  one 
  or 
  of 
  two 
  anterior 
  mesoso- 
  

   matic 
  somites, 
  besides 
  the 
  prsegenital 
  somite, 
  would 
  then 
  

   have 
  to 
  be 
  supposed 
  to 
  have 
  occurred 
  also. 
  

  

  Sub-order 
  a. 
  Uropygi. 
  — 
  Prosoma 
  longer 
  than 
  wide, 
  its 
  

   sternal 
  area 
  very 
  narrow, 
  furnished 
  with 
  a 
  large 
  prosternal 
  

   and 
  metasternal 
  plate, 
  and 
  often 
  with 
  a 
  small 
  mesosternal 
  

   sclerite. 
  Appendages 
  of 
  second 
  pair 
  with 
  their 
  basal 
  segments 
  

  

  