﻿Watson: 
  notes 
  on 
  hygbomia 
  limbata 
  (dkap.). 
  123 
  

  

  (pi. 
  II, 
  fig. 
  2). 
  No 
  vertical 
  facial 
  grooves 
  are 
  present. 
  The 
  skin 
  

   of 
  the 
  tentacles 
  is 
  fairly 
  granular. 
  

  

  Like 
  the 
  shell, 
  tlie 
  animal 
  of 
  most 
  of 
  the 
  Devonsliire 
  examples 
  

   seems 
  usually 
  to 
  be 
  more 
  deeply 
  pigmented 
  than 
  in 
  the 
  case 
  of 
  the 
  

   majority 
  of 
  French 
  specimens. 
  The 
  foot, 
  head, 
  and 
  neck 
  are 
  grey 
  ; 
  

   only 
  the 
  centre 
  of 
  the 
  sole, 
  the 
  lips 
  of 
  the 
  genital 
  opening, 
  and 
  

   the 
  extremities 
  of 
  the 
  four 
  tentacles 
  being 
  slightly 
  lighter. 
  The 
  

   tentacular 
  retractors 
  form 
  nearly 
  black 
  bands 
  on 
  the 
  neck, 
  as 
  the 
  

   skin 
  is 
  semi-translucent, 
  not 
  with. 
  standing 
  its 
  dark 
  colour. 
  

  

  Mantle 
  and 
  Visceral 
  HuMP.-^The 
  mantle-edge 
  is 
  grey 
  round 
  

   the 
  respiratory 
  opening, 
  but 
  becomes 
  nearly 
  white 
  lower 
  down. 
  It 
  

   i.s 
  furnished 
  with 
  body-lobes, 
  but 
  no 
  shell-lobes 
  are 
  developed. 
  The 
  

   right 
  body-lobe 
  is 
  cleft 
  into 
  two 
  parts, 
  an 
  inner 
  portion 
  immediately 
  

   below 
  the 
  respiratory 
  opening 
  and 
  an 
  outer 
  portion 
  to 
  the 
  right 
  of 
  

   the 
  other. 
  The 
  anus 
  appears 
  to 
  be 
  situated 
  in 
  the 
  upper 
  part 
  of 
  the 
  

   groove 
  between 
  these 
  two 
  portion.'^. 
  Tl]e 
  two 
  left 
  body-lobes 
  are 
  

   widely 
  separated 
  from 
  each 
  other 
  : 
  one 
  is 
  close 
  to 
  the 
  respiratoiy 
  

   opening 
  and 
  arches 
  over 
  it 
  in 
  a 
  peculiar 
  manner 
  ; 
  the 
  other 
  is 
  situated 
  

   low 
  down 
  on 
  the 
  left 
  side 
  of 
  the 
  animal. 
  The 
  form 
  of 
  these 
  lobes 
  

   will 
  be 
  best 
  seen 
  from 
  the 
  illustration 
  (pi. 
  II, 
  fig. 
  4). 
  

  

  When 
  the 
  animal 
  is 
  extracted 
  from 
  the 
  shell, 
  the 
  skin 
  over 
  the 
  

   lung 
  is 
  seen 
  to 
  be 
  nearly 
  black, 
  except 
  for 
  some 
  small 
  whitish 
  spot.s 
  

   which 
  are 
  usually 
  scattered 
  over 
  it. 
  In 
  one 
  Devonshire 
  example 
  tlie 
  

   kidney 
  was 
  entirely 
  blackish, 
  but 
  it 
  is 
  more 
  often 
  merely 
  outlined 
  with 
  

   black, 
  the 
  centre 
  being 
  grey. 
  A 
  short 
  baud 
  without 
  pigment 
  occurs 
  

   over 
  the 
  pericardium. 
  The 
  skin 
  of 
  the 
  upper 
  wliorls 
  is 
  colourless 
  

   below 
  the 
  suture, 
  but 
  more 
  or 
  less 
  pigmented 
  above 
  it. 
  In 
  one 
  

   specimen 
  this 
  part 
  was 
  black, 
  in 
  another 
  grey, 
  and 
  in 
  a 
  third 
  greyish- 
  

   brown 
  mottled 
  with 
  white. 
  

  

  IIespieatory 
  System. 
  (PI. 
  II, 
  fig. 
  5.) 
  — 
  The 
  mantle-cavity 
  or 
  

   lung 
  is 
  rather 
  long. 
  Its 
  roof 
  shows 
  a 
  few 
  small 
  transverse 
  veins, 
  

   chiefly 
  of 
  an 
  afferent 
  nature; 
  but 
  the 
  only 
  conspicuous 
  blood-vessel 
  

   is 
  the 
  main 
  pulmonary 
  vein, 
  which 
  runs 
  foiward 
  from 
  the 
  heart 
  

   towards 
  the 
  respiiatory 
  opening, 
  and 
  is 
  almost 
  without 
  branches 
  

   except 
  close 
  to 
  its 
  front 
  end. 
  The 
  heart 
  is 
  situated 
  relatively 
  far 
  

   back, 
  and 
  in 
  the 
  specimens 
  examined 
  the 
  ventricle 
  was 
  much 
  larger 
  

   than 
  the 
  auricle. 
  The 
  aorta 
  which 
  aiises 
  from 
  the 
  ventricle 
  divides, 
  

   as 
  usual, 
  into 
  two 
  branches, 
  one 
  passing 
  backwards, 
  the 
  other 
  bending 
  

   round 
  the 
  anterior 
  loop 
  of 
  the 
  intestine 
  and 
  running 
  forwards 
  to 
  

   supply 
  the 
  cephalic 
  I'egion 
  with 
  oxygenated 
  blood. 
  

  

  Excretokt 
  System. 
  (PL 
  II, 
  fig. 
  5.) 
  — 
  The 
  kidney 
  is 
  narrow 
  and 
  

   extends 
  a 
  considerable 
  distance 
  in 
  front 
  of 
  the 
  heart. 
  It 
  is 
  between 
  

   6 
  and 
  7 
  ram. 
  in 
  length. 
  Dark 
  specks 
  are 
  sparsely 
  scattered 
  over 
  

   its 
  lower 
  surface, 
  which 
  is 
  otherwise 
  of 
  a 
  very 
  pale 
  colour. 
  

  

  The 
  ureter 
  arises 
  from 
  the 
  extreme 
  front 
  end 
  of 
  the 
  kidney, 
  passes 
  

   backwards 
  along 
  its 
  right 
  edge, 
  and 
  then 
  bends 
  round 
  aiul 
  runs 
  

   forwards 
  beside 
  the 
  rectum. 
  

  

  In 
  one 
  specimen 
  several 
  small 
  Trematodes 
  or 
  Cercarioe 
  were 
  found 
  

   in 
  the 
  cavity 
  of 
  the 
  kidney 
  (pi. 
  II, 
  fig. 
  6). 
  They 
  measured 
  on 
  an 
  

   average 
  about 
  1 
  by 
  -4 
  mm., 
  and 
  were 
  not 
  encysted, 
  although 
  none 
  of 
  

  

  