﻿164 
  Prof. 
  Mcintosh's 
  Notes 
  from 
  the 
  

  

  A 
  Heterocirrus 
  {Heterocirrus 
  gravieri, 
  sp. 
  n.) 
  dredged 
  at 
  

   Station 
  29 
  oft' 
  Cadiz, 
  to 
  the 
  west 
  of 
  the 
  Straits 
  of 
  Gibraltar, 
  

   in 
  227 
  fathoms, 
  in 
  the 
  ' 
  Porcupine 
  ' 
  Expedition 
  of 
  1870, 
  

   appears 
  to 
  differ 
  from 
  any 
  described. 
  At 
  this 
  station, 
  ac- 
  

   cording 
  to 
  Dr. 
  Gwyn 
  Jeffreys, 
  there 
  was 
  an 
  admixture 
  of 
  

   northern 
  and 
  southern 
  forms. 
  The 
  head 
  is 
  pointed 
  in 
  front 
  

   and 
  constricted 
  posteriorly, 
  so 
  that 
  from 
  the 
  dorsum 
  it 
  is 
  

   almost 
  cordate 
  in 
  outline. 
  The 
  mouth, 
  as 
  in 
  allied 
  forms, 
  

   opens 
  a 
  little 
  behind 
  the 
  tip 
  of 
  the 
  snout. 
  The 
  body 
  is 
  

   about 
  an 
  inch 
  in 
  length, 
  somewhat 
  narrow 
  and 
  elongate, 
  and 
  

   slightly 
  flattened 
  from 
  above 
  downward 
  throughout, 
  the 
  tail 
  

   not 
  being 
  wider 
  than 
  the 
  preceding 
  region, 
  and 
  terminating 
  

   in 
  a 
  pointed 
  extremity 
  with 
  the 
  anus 
  above 
  it. 
  The 
  colour 
  

   in 
  spirit 
  is 
  pale 
  brown, 
  darker 
  at 
  the 
  tip 
  of 
  the 
  tail. 
  Ante- 
  

   riorly 
  the 
  dorsal 
  bristles 
  (PI. 
  VI. 
  fig. 
  3) 
  are 
  longer 
  than 
  in 
  

   allied 
  forms 
  with 
  the 
  exception 
  of 
  Chatozone, 
  but 
  they 
  

   become 
  shorter 
  posteriorly. 
  A 
  pair 
  of 
  tentacles 
  occurs 
  in 
  

   front 
  and 
  a 
  pair 
  of 
  branchiae 
  on 
  each 
  side 
  behind 
  it. 
  The 
  

   tentacle 
  is 
  darker, 
  longer, 
  and 
  thicker 
  than 
  the 
  others, 
  

   though 
  apparently 
  not 
  differing 
  in 
  external 
  structure. 
  It 
  

   arises 
  immediately 
  behind 
  the 
  head 
  and 
  may 
  be 
  the 
  homo- 
  

   logue 
  of 
  the 
  grooved 
  tentacle, 
  e. 
  g., 
  of 
  Dodecaceria 
  ater. 
  A 
  

   branchia 
  springs 
  just 
  above 
  it. 
  

  

  The 
  first 
  foot 
  has 
  a 
  distinct 
  dorsal 
  setigerous 
  papilla 
  and 
  

   a 
  long 
  tuft 
  of 
  simple 
  tapering 
  bristles 
  which 
  nearly 
  equal 
  

   the 
  diameter 
  of 
  the 
  body. 
  The 
  ventral 
  division 
  has 
  a 
  similar 
  

   though 
  shorter 
  tuft. 
  This 
  arrangement 
  continues 
  for 
  some 
  

   distance 
  and 
  then 
  the 
  characteristic 
  hooks 
  appear 
  in 
  the 
  

   ventral 
  division. 
  These 
  (PI. 
  V. 
  fig. 
  3 
  a) 
  are 
  comparatively 
  

   long 
  and 
  slender, 
  with 
  a 
  slight 
  forward 
  curve. 
  The 
  shaft 
  

   dilates 
  a 
  little 
  from 
  the 
  base 
  to 
  the 
  distal 
  third, 
  where 
  a 
  

   slight 
  backward 
  curve 
  and 
  a 
  diminution 
  take 
  place 
  to 
  the 
  

   neck. 
  The 
  tip 
  has 
  an 
  enlargement 
  beyond 
  the 
  neck, 
  then 
  

   the 
  posterior 
  curve, 
  in 
  lateral 
  view, 
  forms 
  a 
  segment 
  of 
  a 
  

   large 
  circle 
  and 
  again 
  points 
  forward 
  at 
  the 
  hooked 
  tip. 
  

   The 
  anterior 
  curve 
  again 
  is 
  chiefly 
  backward 
  and 
  then 
  for- 
  

   ward 
  at 
  the 
  terminal 
  hook. 
  The 
  length 
  of 
  the 
  distal 
  region 
  

   in 
  this 
  hook 
  is 
  characteristic. 
  A 
  few 
  bristles 
  accompany 
  

   the 
  ventral 
  hooks 
  to 
  the 
  posterior 
  end. 
  By-and-by 
  between 
  

   the 
  twentieth 
  and 
  thirtieth 
  foot 
  the 
  hooks 
  appear 
  also 
  in 
  the 
  

   dorsal 
  division, 
  one 
  or 
  two 
  of 
  these 
  organs 
  accompanying 
  

   the 
  bristles, 
  which 
  continue 
  to 
  the 
  posterior 
  end 
  of 
  the 
  

   annelid. 
  

  

  This 
  species 
  inhabits 
  a 
  firm 
  though 
  thin 
  calcareous 
  tube 
  

   strengthened 
  externally 
  by 
  grains 
  of 
  sand, 
  foraminifera, 
  and 
  

   fragments 
  of 
  shells. 
  The 
  interior 
  of 
  the 
  tube 
  is 
  perfectly 
  

  

  