﻿198 
  

  

  E. 
  RAY 
  LANKESTER. 
  

  

  Fig. 
  29. 
  

  

  Tig. 
  30. 
  

  

  Fig. 
  29. 
  — 
  Diaj^ram 
  of 
  the 
  arterial 
  system 
  of 
  A, 
  Scorpio, 
  and 
  B, 
  

   Limulus. 
  The 
  llomau 
  numerals 
  indicate 
  the 
  body 
  somites 
  and 
  the 
  

   two 
  figures 
  are 
  adjusted 
  for 
  comparison, 
  ce, 
  cerebral 
  arteries 
  ; 
  sp, 
  

   supra-spinal 
  or 
  medullary 
  artery 
  ; 
  c, 
  caudal 
  artery; 
  /, 
  lateral 
  anasto- 
  

   motic 
  artery 
  of 
  Limulus. 
  Tlie 
  Roman 
  numerals 
  indicate 
  the 
  body 
  

   somites, 
  and 
  the 
  two 
  figures 
  are 
  adjusted 
  for 
  comparison, 
  ce, 
  

   cerebral 
  arteries 
  ; 
  sp, 
  supra-spinal 
  or 
  medullary 
  artery 
  ; 
  c, 
  caudal 
  

   artery 
  ; 
  /, 
  lateral 
  anastomotic 
  artery 
  of 
  Limulus. 
  The 
  figure 
  B 
  also 
  

   shows 
  the 
  peculiar 
  neural 
  investiture 
  formed 
  by 
  the 
  cerebral 
  arteries 
  

   in 
  Limulus 
  and 
  the 
  derivation 
  from 
  this 
  of 
  the 
  arteries 
  to 
  the 
  

   limbs, 
  III, 
  IV, 
  VI, 
  whereas 
  in 
  Scorpio 
  the 
  latter 
  have 
  a 
  separate 
  

   oritrin 
  from 
  the 
  anterior 
  aorta. 
  (From 
  Lankester, 
  "Limulus 
  an 
  

   Arachnid.") 
  

  

  Fig. 
  30. 
  — 
  View 
  from 
  below 
  of 
  a 
  Scorpion 
  (B. 
  occitanus) 
  opened 
  

   and 
  dissected 
  so 
  as 
  to 
  show 
  the 
  pericardium 
  with 
  its 
  muscles, 
  the 
  

   lateral 
  arteries, 
  and 
  the 
  tergo-sternal 
  muscles. 
  PRO, 
  prosoma 
  ; 
  

   <?pw, 
  dorso-plastral 
  muscle; 
  art, 
  lateral 
  artery; 
  tsni^, 
  tergo-sternal 
  

   muscle 
  (labelled 
  dv 
  in 
  Fig. 
  31) 
  of 
  the 
  second 
  (pectiniferous) 
  meso- 
  

   somatic 
  somite 
  : 
  this 
  is 
  the 
  most 
  anterior 
  pair 
  of 
  the 
  series 
  of 
  six 
  — 
  

   none 
  are 
  present 
  in 
  the 
  genital 
  somite 
  ; 
  tsm'^, 
  tergo-sternal 
  muscle 
  

   of 
  the 
  fifth 
  mesosomatic 
  somite; 
  ^««^, 
  tergo-sternal 
  muscle 
  of 
  the 
  

   enlarsed 
  first 
  mesosomatic 
  somite; 
  Per, 
  pericardium; 
  FP3I^ 
  to 
  

   VPAP 
  , 
  the 
  series 
  of 
  seven 
  pairs 
  of 
  veno-pericardiac 
  muscles 
  (labelled 
  

   pv 
  in 
  Fig. 
  31). 
  Tiiere 
  is 
  some 
  reason 
  to 
  admit 
  the 
  existence 
  

   of 
  another 
  more 
  anterior 
  pair 
  of 
  these 
  muscles 
  in 
  Scorpio; 
  this 
  

   would 
  make 
  the 
  number 
  exactly 
  correspond 
  with 
  the 
  number 
  in 
  

   Limulus. 
  (After 
  Lankester, 
  ' 
  Trans. 
  Zool. 
  Soc.,' 
  vol. 
  xi, 
  1883.) 
  

  

  