﻿A 
  STUDY 
  IN 
  CARCINOLOGT. 
  29 
  

  

  des 
  Macroures 
  pour 
  se 
  nipprocher 
  des 
  Brachyures 
  et 
  la 
  reduction 
  qu'il 
  presente 
  

   dans 
  le 
  sens 
  de 
  la 
  longueur, 
  est 
  un 
  indice, 
  non 
  pas 
  des 
  affinity 
  precises 
  de 
  

   l'animal, 
  mais 
  du 
  degre 
  devolution 
  cancerienne 
  auquel 
  il 
  est 
  arrive." 
  IF 
  we 
  

   accept 
  this 
  proposition, 
  and 
  for 
  my 
  own 
  part 
  I 
  accept 
  it 
  without 
  reserve, 
  

   it 
  must 
  follow 
  that 
  a 
  crab 
  with 
  a 
  nervous 
  system 
  of 
  which 
  the 
  ganglia 
  are 
  

   more 
  concentrated 
  in 
  the 
  longitudinal 
  direction 
  is 
  farther 
  removed 
  from 
  its 
  

   Macruran 
  ancestry 
  than 
  one 
  in 
  which 
  the 
  ganglia 
  are 
  far 
  less 
  concentrated, 
  

   and, 
  that 
  the 
  former 
  cannot 
  he 
  a 
  progenitor 
  of 
  the 
  latter. 
  

  

  Of 
  the 
  Raninidse 
  I 
  have 
  been 
  able, 
  thanks 
  to 
  the 
  excellent 
  state 
  of 
  preser- 
  

   vation 
  of 
  the 
  example 
  sent 
  me 
  by 
  Prof. 
  Kishinoye, 
  to 
  make 
  a 
  thorough 
  study 
  

   of 
  the 
  nervous 
  system 
  of 
  Ranina 
  dentata 
  and 
  a 
  sufficient 
  study 
  of 
  that 
  of 
  

   Lyreidus 
  tridentatus, 
  of 
  which 
  I 
  possessed 
  two 
  well-preserved 
  examples. 
  

   I 
  have 
  also 
  dissected 
  the 
  nervous 
  systems 
  of 
  Notopus 
  dorsipes 
  and 
  Notosceles 
  

   cliimmonis, 
  and 
  was 
  able 
  to 
  ascertain 
  that 
  they 
  are 
  of 
  the 
  same 
  character 
  and 
  

   the 
  ganglia 
  fully 
  as 
  much 
  extended 
  in 
  the 
  longitudinal 
  line 
  as 
  in 
  Ranina 
  

   and 
  Lyreidus, 
  but 
  their 
  state 
  of 
  preservation 
  did 
  not 
  admit 
  of 
  great 
  accuracy 
  

   in 
  making 
  out 
  details. 
  

  

  PI. 
  4. 
  tig. 
  8 
  is 
  a 
  drawing 
  of 
  the 
  nerve-ganglion 
  chain 
  of 
  Ranina 
  dentata, 
  

   as 
  seen 
  from 
  above, 
  the 
  whole 
  series 
  being 
  represented 
  as 
  flattened 
  out 
  in 
  one 
  

   plane. 
  PI. 
  4. 
  fig. 
  9 
  shows 
  the 
  actual 
  position 
  of 
  the 
  nerve 
  chain 
  as 
  seen 
  

   from 
  the 
  side, 
  and 
  its 
  relation 
  to 
  the 
  endophragin;il 
  skeleton. 
  Owing 
  to 
  the 
  

   deep 
  infolding 
  of 
  the 
  sternal 
  apodemes 
  of 
  the 
  posterior 
  thoracic 
  somites, 
  

   the 
  posterior 
  thoracic 
  ganglia 
  and 
  the 
  abdominal 
  ganglia 
  closely 
  applied 
  to 
  

   them 
  are 
  directed 
  nearly 
  vertically 
  upwards. 
  

  

  The 
  cerebral 
  ganglion 
  is 
  relatively 
  large 
  and 
  quadrangular 
  in 
  outline, 
  and 
  

   the 
  ocular, 
  antennulary, 
  and 
  antennary 
  nerves 
  are 
  of 
  large 
  size 
  ; 
  otherwise 
  it 
  

   does 
  not 
  present 
  any 
  special 
  features. 
  A 
  small 
  pair 
  of 
  nerves 
  passes 
  forward 
  

   to 
  the 
  rostrum. 
  The 
  circum-cesophageal 
  connectives 
  are 
  long 
  and 
  stout. 
  

   The 
  small 
  ganglia 
  on 
  either 
  side 
  of 
  the 
  oesophagus 
  give 
  off 
  a 
  fairly 
  stout 
  

   nerve 
  to 
  dilator 
  muscles 
  of 
  the 
  oesophagus 
  as 
  well 
  as 
  the 
  more 
  slender 
  

   connectives 
  of 
  the 
  stomatogastric 
  system. 
  The 
  post-cesopbageal 
  commissure 
  

   is 
  well 
  marked. 
  The 
  subcesophageal 
  ganglion 
  mass 
  is 
  large 
  and 
  goblet- 
  

   shaped 
  in 
  outline, 
  as 
  seen 
  from 
  above, 
  and 
  gives 
  off 
  five 
  stout 
  nerves 
  on 
  eilher 
  

   side. 
  These 
  nerves 
  are 
  somewhat 
  swollen 
  at 
  their 
  origins, 
  and 
  the 
  last 
  two 
  

   come 
  off 
  rather 
  apart 
  from 
  the 
  rest 
  and 
  give 
  the 
  appearance 
  of 
  originating 
  

   from 
  a 
  separate 
  ganglionic 
  centre. 
  Otherwise 
  the 
  six 
  ganglia 
  supplying 
  the 
  

   mandibles, 
  first 
  and 
  second 
  maxillae, 
  and 
  three 
  pairs 
  of 
  maxillipeds 
  are 
  

   indistinguishably 
  fused 
  in 
  the 
  subcesophageal 
  mass. 
  It 
  will 
  be 
  noticed 
  that 
  

   the 
  mandibular 
  nerve 
  does 
  not 
  spring 
  from 
  the 
  subcesophageal 
  ganglion 
  but 
  

   from 
  the 
  circum-cesophageal 
  connectives, 
  some 
  way 
  in 
  advance 
  of 
  the 
  ganglion. 
  

   The 
  ganglion 
  pair 
  of 
  the 
  chelipeds 
  is 
  distinct, 
  hut 
  so 
  closely 
  fused 
  to 
  the 
  

   subcefbphageal 
  mass 
  that 
  the 
  connectives 
  uniting 
  the 
  two 
  are 
  indistinguishable. 
  

  

  