﻿182 
  

  

  E. 
  RAY 
  LANK 
  ESTER. 
  

  

  the 
  parapodia 
  (appendages, 
  limbs) 
  in 
  each 
  region, 
  of 
  the 
  posi- 
  

   tion 
  of 
  the 
  genital 
  aperture 
  and 
  operculum, 
  of 
  the 
  position 
  

   and 
  character 
  of 
  the 
  eyes, 
  and 
  of 
  the 
  powerful 
  post-anal 
  spines 
  

   not 
  seen 
  in 
  other 
  Arthropods, 
  is 
  very 
  convincing 
  as 
  to 
  the 
  

   affinity 
  of 
  Limulus 
  and 
  Scorpio. 
  Perhaps 
  the 
  most 
  important 
  

   general 
  agreement 
  of 
  Scorpio 
  compared 
  with 
  Limulus 
  and 
  the 
  

   Eurypterines 
  is 
  the 
  division 
  of 
  the 
  body 
  into 
  the 
  three 
  regions 
  

   (or 
  tagmata) 
  — 
  prosoma, 
  mesosoma, 
  and 
  metasoma, 
  — 
  each 
  con- 
  

   sisting 
  of 
  six 
  segments, 
  the 
  prosoma 
  having 
  leg-like 
  appen- 
  

  

  (ens 
  

  

  nervf 
  

  

  Fig. 
  22. 
  — 
  Section 
  througli 
  the 
  lateral 
  eye 
  of 
  Eiiscorpius 
  

   italicus. 
  lens, 
  cuticular 
  lens; 
  nerv.c, 
  retinal 
  cells 
  (nerve-end 
  

   cells) 
  ; 
  rhabd, 
  rliabdomes 
  ; 
  nerv.f, 
  nerve-fibres 
  of 
  the 
  optic 
  nerve 
  ; 
  

   vit, 
  intermediate 
  cells 
  (lying 
  between 
  the 
  bases 
  of 
  the 
  retinal 
  cells). 
  

   (After 
  Lankester 
  and 
  Bourne, 
  from 
  Parker 
  and 
  Haswell's 
  ' 
  Text- 
  

   book 
  of 
  Zoology,' 
  Macniillan 
  and 
  Co.) 
  

  

  dages, 
  the 
  mesosoma 
  having 
  foliaceous 
  appendages, 
  and 
  the 
  

   metasoma 
  being 
  destitute 
  of 
  appendages. 
  

  

  In 
  1893, 
  some 
  years 
  after 
  the 
  identification 
  of 
  the 
  somites 
  

   of 
  Limulus 
  with 
  those 
  of 
  Scorpio, 
  thus 
  indicated, 
  had 
  been 
  

   published, 
  zoologists 
  were 
  startled 
  by 
  the 
  discovery 
  by 
  a 
  

   Japanese 
  zoologist, 
  Mr. 
  Kishinouye 
  (8), 
  of 
  a 
  seventh 
  proso- 
  

   matic 
  somite 
  in 
  the 
  embryo 
  of 
  Limulus 
  lougispin 
  a. 
  This 
  

   was 
  seen 
  in 
  longitudinal 
  sections, 
  as 
  shown 
  in 
  Fig. 
  19. 
  The 
  

   simple 
  identification 
  of 
  somite 
  with 
  somite 
  in 
  Limulus 
  and 
  

   Scorpio 
  seemed 
  to 
  ba 
  threatened 
  by 
  this 
  discovery. 
  Bat 
  in 
  

   1896 
  Dr. 
  August 
  Brauei-, 
  of 
  Marburg 
  (9), 
  discovered 
  in 
  the 
  

  

  