﻿A 
  STUDY 
  IN 
  CARCINOLOGY. 
  ()1 
  

  

  animals, 
  the 
  exact 
  course 
  of 
  the 
  anterior 
  inhalant 
  respiratory 
  current 
  in 
  the 
  

   Raninidge 
  must 
  remain 
  largely 
  a 
  matter 
  of 
  conjecture. 
  Nevertheless 
  T 
  have 
  

   not 
  hesitated 
  to 
  put 
  forward 
  the 
  following 
  interpretation 
  based 
  upon 
  a 
  

   detailed 
  study 
  of 
  anatomical 
  facts 
  in 
  the 
  hope 
  that, 
  whilst 
  my 
  conclusions 
  must 
  

   necessarily 
  he 
  subject 
  to 
  revision 
  and 
  correction, 
  naturalists 
  who 
  have 
  oppor- 
  

   tunities 
  of 
  studying 
  the 
  live 
  animals 
  may 
  be 
  so 
  far 
  interested 
  as 
  to 
  devote 
  

   some 
  time 
  and 
  trouble 
  to 
  the 
  elucidation 
  of 
  the 
  workings 
  of 
  their 
  respiratory 
  

   mechanisms. 
  The 
  anatomical 
  characters 
  are 
  most 
  easily 
  studied 
  in 
  Notojms 
  

   dorsipes, 
  and 
  it 
  is 
  probable 
  that 
  what 
  is 
  true 
  of 
  this 
  species 
  is 
  also 
  true 
  of 
  

   Ranilia 
  muricata, 
  M. 
  Edw 
  , 
  but 
  as 
  I 
  have 
  onlv 
  been 
  able 
  to 
  examine 
  a 
  single 
  

   dried 
  example 
  of 
  the 
  latter 
  in 
  the 
  British 
  Museum 
  of 
  Natural 
  History, 
  

   I 
  cannot 
  say 
  anything 
  certain 
  about 
  it. 
  I 
  have 
  stated 
  elsewhere 
  (p. 
  2G) 
  

   that, 
  in 
  my 
  opinion, 
  RaniLia, 
  M. 
  Edw. 
  = 
  iYot 
  opus, 
  de 
  Haan. 
  In 
  Notopus 
  the 
  

   antennas 
  are 
  more 
  primitive, 
  that 
  is 
  to 
  say, 
  they 
  depart 
  less 
  from 
  the 
  

   Macruran 
  pattern, 
  than 
  in 
  any 
  other 
  Raninidoe. 
  The 
  peduncle 
  (figs. 
  29 
  & 
  29a) 
  

   is 
  made 
  up 
  of 
  five 
  distinct 
  segments 
  of 
  which 
  the 
  proximal 
  is 
  admedian 
  in 
  

   position, 
  small, 
  largely 
  concealed 
  by 
  the 
  sub-antennary 
  lobe 
  of 
  the 
  pterygo- 
  

   stome 
  and 
  bears 
  at 
  its 
  inner 
  angle 
  the 
  aperture 
  of 
  the 
  excretory 
  o-land. 
  The 
  

   second 
  segment 
  is 
  also 
  small 
  and 
  largely 
  concealed 
  by 
  the 
  sub-antennary 
  

   lobe 
  : 
  it 
  lies 
  on 
  the 
  same 
  level 
  as 
  the 
  first 
  and 
  is 
  external 
  to 
  it. 
  The 
  third 
  

   segment 
  is 
  large, 
  sub-quadrangular 
  in 
  outline, 
  its 
  extero-ventral 
  surface 
  

   slightly 
  convex 
  and 
  tuberculated, 
  its 
  intero-dorsal 
  surface 
  smooth 
  and 
  slightly 
  

   concave. 
  Its 
  admedian 
  margin 
  is 
  prominent 
  and 
  curved, 
  forming 
  a 
  pro- 
  

   jection 
  which 
  meets 
  its 
  fellow 
  in 
  the 
  middle 
  line. 
  It 
  bears 
  a 
  conspicuous 
  

   tuft 
  of 
  long 
  forwardly 
  directed 
  seta?. 
  Its 
  extero-anterior 
  angle 
  is 
  produced 
  

   into 
  a 
  process 
  which 
  embraces 
  the 
  proximal 
  part 
  of 
  the 
  fourth 
  peduncular 
  

   segment; 
  this 
  process 
  is 
  largely 
  developed 
  in 
  other 
  Raninidee 
  but 
  remains 
  

   small 
  in 
  JS 
  T 
  otopus. 
  The 
  fourth 
  and 
  fifth 
  segments 
  are 
  fairly 
  long, 
  their 
  

   external 
  and 
  ventral 
  surfaces 
  granular 
  and 
  convex, 
  their 
  admedian 
  surfaces 
  

   smooth 
  and 
  flat 
  or 
  slightly 
  concave. 
  The 
  dorsal 
  and 
  ventral 
  edges 
  of 
  these 
  

   smooth 
  admedian 
  surfaces 
  are 
  fringed 
  with 
  long 
  closely 
  set 
  plumose 
  setas 
  

   which, 
  when 
  the 
  two 
  antennas 
  are 
  approximated, 
  interlock 
  with 
  the 
  corre- 
  

   sponding 
  setas 
  of 
  the 
  antenna 
  of 
  the 
  other 
  side. 
  The 
  antennary 
  flagellum 
  

   comprises 
  twenty 
  -six 
  joints, 
  is 
  relatively 
  longer 
  than 
  in 
  any 
  other 
  Raninidse 
  

   (except 
  Ranilia, 
  M.-Edw. 
  and 
  Cosmonotus) 
  and 
  bears 
  a 
  dorsal 
  and 
  a 
  ventral 
  

   row 
  of 
  strong 
  setee 
  which 
  are 
  directed 
  obliquely 
  inwards 
  so 
  as 
  to 
  interlock 
  

   with 
  those 
  of 
  the 
  opposite 
  side 
  when 
  the 
  antennary 
  flagella 
  are 
  approximated. 
  

   Thus 
  there 
  is 
  formed 
  an 
  antennary 
  water-tube 
  (figs. 
  1 
  & 
  56), 
  shorter 
  indeed 
  

   but 
  otherwise 
  similar 
  to 
  and 
  fully 
  efficient 
  as 
  that 
  of 
  Corystes. 
  Water 
  sucked 
  

   down 
  the 
  antennary 
  tube 
  passes 
  into 
  a 
  shallow 
  chamber 
  lying 
  behind 
  the 
  bases 
  

   of 
  the 
  antennas, 
  the 
  floor 
  of 
  which 
  is 
  formed 
  by 
  the 
  meri 
  of 
  the 
  third 
  maxilli- 
  

   peds, 
  its 
  roof 
  by 
  the 
  spoon-shaped 
  expanded 
  anterior 
  ends 
  of 
  the 
  exopods 
  of 
  

  

  