﻿MOLLUSC 
  A. 
  85 
  

  

  lessening 
  in 
  diameter 
  towards 
  the 
  tips 
  ; 
  about 
  one 
  hundred 
  in 
  

   number 
  on 
  the 
  longest 
  arms, 
  rather 
  prominent, 
  especially 
  the 
  largest, 
  

   alternating 
  in 
  two 
  series, 
  almost, 
  if 
  not 
  quite, 
  from 
  the 
  commence- 
  

   ment. 
  Length 
  from 
  end 
  of 
  the 
  body 
  to 
  angle 
  between 
  the 
  upper 
  

   arms 
  20 
  millim., 
  width 
  of 
  body 
  13, 
  length 
  from 
  subsiphonal 
  open- 
  

   ing 
  to 
  the 
  extremity 
  only 
  10 
  ; 
  largest 
  arm, 
  from 
  mouth 
  to 
  tip, 
  40 
  

   millim. 
  

  

  Hah. 
  Thursday 
  Island, 
  Torres 
  Straits, 
  4-5 
  fathoms, 
  sandy 
  bottom 
  

   {'Alert'); 
  Port 
  Essington 
  {B. 
  Mus.). 
  

  

  This 
  species 
  (in 
  spirit) 
  is 
  of 
  a 
  pale 
  dirty 
  olive 
  tint 
  on 
  the 
  ventral 
  

   surface 
  and 
  very 
  much 
  darker 
  above. 
  The 
  inner 
  surface 
  of 
  the 
  

   arms 
  is 
  also 
  light 
  olive, 
  the 
  suckers 
  having 
  a 
  brown 
  hue. 
  At 
  first 
  

   I 
  was 
  inclined 
  to 
  consider 
  that 
  this 
  olive 
  colour 
  might 
  be 
  the 
  result 
  

   of 
  staining 
  by 
  the 
  juices 
  of 
  an 
  Aplysia 
  which 
  was 
  contained 
  in 
  the 
  

   same 
  bottle. 
  On 
  examining 
  the 
  type 
  from 
  Port 
  Essington, 
  which 
  I 
  

   had 
  not 
  an 
  opportunity 
  of 
  doing 
  when 
  drawing 
  up 
  the 
  above 
  

   description, 
  I 
  find 
  that 
  the 
  same 
  colour 
  prevails. 
  

  

  2. 
  Octopus 
  tenebricus. 
  (Plate 
  IV. 
  figs. 
  B-B 
  3.) 
  

  

  Animal 
  of 
  a 
  uniform 
  dark 
  purplish 
  chocolate-colour. 
  Body 
  (in 
  

   spirit) 
  longer 
  than 
  wide, 
  smooth, 
  bearing 
  upon 
  the 
  back 
  and 
  sides 
  

   scattered 
  cirri. 
  Head 
  as 
  broad 
  as 
  the 
  body, 
  very 
  prominent 
  at 
  the 
  

   eyes, 
  much 
  constricted 
  in 
  front 
  and 
  behind 
  in 
  the 
  cervical 
  region 
  ; 
  

   also 
  ornamented 
  with 
  a 
  few 
  tufts, 
  the 
  largest 
  one 
  being 
  placed 
  above 
  

   but 
  slightly 
  behind 
  each 
  eye, 
  A 
  small 
  one 
  in 
  front 
  of 
  each 
  eye 
  and 
  

   a 
  similar 
  one 
  just 
  behind 
  them 
  appear 
  to 
  be 
  constant 
  in 
  position 
  ; 
  

   these 
  are 
  simple 
  elongate 
  papillae, 
  whilst 
  the 
  larger 
  ones 
  are 
  branched. 
  

   The 
  web 
  between 
  the 
  arms 
  is 
  rather 
  small, 
  externally 
  papillose, 
  and 
  

   extends 
  in 
  a 
  narrow 
  strip 
  up 
  tlie 
  back 
  of 
  the 
  arms, 
  forming 
  a 
  sort 
  of 
  

   acute 
  carina. 
  Upper 
  or 
  dorsal 
  pair 
  of 
  arms 
  smallest 
  and 
  shortest, 
  

   the 
  two 
  lateral 
  pairs 
  about 
  equal 
  and 
  the 
  ventral 
  only 
  a 
  trifle 
  

   shorter, 
  all 
  gradually 
  tapering 
  to 
  very 
  fine 
  points. 
  Lower 
  surfaces 
  

   narrower, 
  bearing 
  two 
  rows 
  of 
  very 
  prominent 
  suckers, 
  of 
  which 
  the 
  

   first 
  four 
  form 
  a 
  single 
  series, 
  the 
  rest 
  (about 
  120 
  on 
  the 
  longest 
  

   arms) 
  alternating 
  in 
  position. 
  The 
  first 
  cup 
  is 
  very 
  small, 
  the 
  next 
  

   a 
  trifle 
  larger, 
  and 
  so 
  on 
  until 
  about 
  the 
  tenth 
  is 
  reached, 
  when 
  they 
  

   attain 
  their 
  greatest 
  diameter, 
  namely 
  Ij 
  millim. 
  ; 
  this 
  size 
  is 
  

   maintained 
  a 
  short 
  distance 
  up 
  the 
  arm, 
  when 
  the 
  cups 
  gradually 
  

   diminish 
  as 
  the 
  extremity 
  is 
  approached. 
  

  

  Dimensions. 
  Body, 
  from 
  base 
  of 
  funnel 
  to 
  extremity, 
  13 
  millim., 
  

   width 
  11 
  ; 
  longest 
  arm 
  72 
  milhm., 
  shortest 
  50 
  in 
  length. 
  

  

  llah. 
  Port 
  Ucnison, 
  N.E. 
  Australia, 
  3-4 
  fathoms, 
  sand 
  and 
  rock 
  

   bottom. 
  

  

  This 
  species 
  bears 
  considerable 
  resemblance 
  to 
  0. 
  aculeatus 
  of 
  

   d'Orbigny, 
  but 
  may 
  be 
  distinguished 
  by 
  the 
  difl^eronce 
  of 
  colour, 
  the 
  

   different 
  relative 
  length 
  of 
  the 
  arms, 
  the 
  narrowness 
  of 
  their 
  lower 
  

   surface, 
  the 
  greater 
  prominence 
  of 
  the 
  suckers, 
  the 
  regularity 
  of 
  the 
  

   uuiserial 
  four 
  at 
  the 
  base, 
  and 
  the 
  smaller 
  number 
  of 
  the 
  external 
  

   cirri 
  or 
  papillae. 
  

  

  d2 
  

  

  