﻿180 
  

  

  E. 
  KAY 
  LANKESTER. 
  

  

  basal 
  support 
  of 
  the 
  scorpion's 
  lung-books 
  shown 
  in 
  the 
  

   figures 
  is 
  a 
  false 
  or 
  secondary 
  axis, 
  and 
  merely 
  a 
  part 
  of 
  the 
  

   infolded 
  surface 
  which 
  forms 
  the 
  air-chamber. 
  The 
  macera- 
  

   tion 
  of 
  the 
  soft 
  parts 
  of 
  a 
  scorpion 
  preserved 
  in 
  weak 
  spirit 
  

   and 
  the 
  cleaning 
  of 
  the 
  chitinised 
  ingrown 
  cuticle 
  give 
  rise 
  to 
  

   the 
  false 
  appearance 
  of 
  a 
  limb 
  axis 
  carrying 
  the 
  lamella). 
  The 
  

  

  Fig. 
  20. 
  

  

  Fig. 
  19. 
  

  

  pmsf 
  

  

  meti 
  

  

  Fig. 
  19. 
  — 
  Section 
  through 
  an 
  early 
  embryo 
  of 
  Limn 
  1 
  us 
  longi- 
  

   spina, 
  sliowing 
  seven 
  transverse 
  divisions 
  in 
  the 
  region 
  of 
  the 
  un- 
  

   segmented 
  anterior 
  carapace. 
  The 
  seventh, 
  VII, 
  is 
  anterior 
  to 
  the 
  

   genital 
  operculum, 
  op, 
  and 
  is 
  the 
  cavity 
  of 
  the 
  prsegenital 
  somite, 
  

   which 
  is 
  more 
  or 
  less 
  completely 
  suppressed 
  in 
  subsequent 
  develop- 
  

   ment, 
  possibly 
  indicated 
  by 
  the 
  great 
  entopophyses 
  of 
  the 
  proso- 
  

   matic 
  carapace. 
  (After 
  Kishinouye, 
  * 
  Jour. 
  Sci. 
  Coll. 
  Japan,' 
  vol. 
  v, 
  

   1892.) 
  

  

  Fig 
  20. 
  — 
  View 
  of 
  the 
  ventral 
  surface 
  of 
  the 
  mid-line 
  of 
  the 
  pro- 
  

   somatic 
  region 
  of 
  Limulus 
  polyphemus. 
  Tlie 
  coxae 
  of 
  the 
  five 
  

   pairs 
  of 
  limbs 
  following 
  tiie 
  chelicerae 
  were 
  arranged 
  in 
  a 
  series 
  on 
  

   each 
  side 
  between 
  the 
  mouth, 
  M, 
  and 
  tiie 
  nietasternites, 
  mets. 
  sf, 
  

   the 
  subfrontal 
  median 
  sclerite; 
  Ch, 
  the 
  chelicerae; 
  caw, 
  the 
  camero- 
  

   stome 
  or 
  upper 
  lip 
  ; 
  M, 
  the 
  mouth 
  ; 
  pmst, 
  the 
  promesosternal 
  

   sclerite 
  or 
  chitinous 
  plate, 
  unpaired 
  ; 
  mets, 
  the 
  right 
  and 
  left 
  meta- 
  

   sternites 
  (corresponding 
  to 
  the 
  similarly 
  placed 
  pentagonal 
  sternite 
  

   of 
  Scorpio. 
  Natural 
  size. 
  (After 
  Lankester.) 
  

  

  margins 
  of 
  the 
  lamellae 
  of 
  the 
  scorpion's 
  lung-book 
  which 
  are 
  

   lowermost 
  in 
  the 
  figures 
  (Fig. 
  15) 
  and 
  appear 
  to 
  be 
  free 
  are 
  

   really 
  those 
  which 
  are 
  attached 
  to 
  the 
  blood-holding 
  axis. 
  

   The 
  true 
  free 
  ends 
  are 
  those 
  nearest 
  the 
  stigma. 
  

  

  Passing 
  on 
  now 
  from 
  the 
  mesosoma 
  we 
  come 
  in 
  Scorpio 
  to 
  

   the 
  metasoma 
  of 
  six 
  segments;, 
  the 
  first 
  of 
  which 
  is 
  broad, 
  

  

  