﻿88 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  mouth 
  and 
  for 
  a 
  short 
  distance 
  along 
  the 
  sides, 
  and 
  then 
  simple 
  and 
  

   gradually 
  increasing 
  in 
  the 
  width 
  of 
  the 
  expansion 
  towards 
  the 
  

   end, 
  where 
  it 
  is 
  very 
  wide 
  beneath 
  the 
  brauchia 
  ; 
  it 
  is 
  stained 
  with 
  

   black 
  on 
  the 
  inside 
  of 
  the 
  edge. 
  Branchial 
  plume 
  posterior, 
  concealed 
  

   between 
  the 
  foot 
  and 
  the 
  hinder 
  lobes 
  of 
  the 
  dorsal 
  disk. 
  Head 
  

   presenting 
  exteriorly 
  a 
  small 
  lobe 
  on 
  each 
  side 
  the 
  oral 
  opening. 
  

  

  Shell 
  internal, 
  situated 
  at 
  the 
  hinder 
  extremity 
  above 
  the 
  branchia, 
  

   white, 
  calcareous, 
  uncoiled, 
  consisting 
  of 
  one 
  or 
  two 
  volutions, 
  

   thickened 
  at 
  the 
  free 
  " 
  sutural 
  line," 
  convex 
  externally 
  and 
  concave 
  

   within, 
  cup-shaped 
  at 
  the 
  commencement, 
  with 
  the 
  outer 
  edge 
  

   extended 
  by 
  a 
  broadish 
  membranous 
  expansion. 
  

  

  Total 
  length 
  33 
  millim. 
  ; 
  cephalic 
  disk 
  18 
  long 
  and 
  16 
  wide 
  at 
  

   the 
  broadest 
  part 
  ; 
  shell 
  with 
  a 
  greatest 
  diameter 
  of 
  8 
  millim., 
  and 
  

   about 
  2 
  in 
  height. 
  

  

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

   bottom. 
  

  

  The 
  only 
  species 
  which 
  appears 
  to 
  have 
  been 
  recorded 
  from 
  the 
  

   Australian 
  coasts 
  is 
  Ar/laia 
  lineolata, 
  figured 
  by 
  H. 
  & 
  A. 
  Adams 
  in 
  

   the 
  ' 
  Genera 
  of 
  Eecent 
  Mollusca,' 
  vol. 
  iii. 
  pi. 
  58. 
  fig. 
  4. 
  This 
  differs, 
  

   however, 
  in 
  the 
  form 
  of 
  the 
  anterior 
  dorsal 
  disk 
  and 
  its 
  small 
  

   size 
  in 
  proportion 
  to 
  the 
  hind 
  part 
  of 
  the 
  animal, 
  in 
  addition 
  to 
  

   which 
  the 
  colour 
  and 
  markings 
  appear 
  to 
  be 
  quite 
  distinct. 
  Aglaia 
  

   giglioUi, 
  from 
  Japan, 
  described 
  by 
  Tapparone-Canefri 
  (Voj*. 
  Magenta, 
  

   p. 
  110, 
  pi. 
  l.fig. 
  18), 
  may 
  be 
  distinguished 
  by 
  the 
  posterior 
  lobation 
  

   of 
  the 
  cephalic 
  disk, 
  different 
  colour, 
  and 
  apparent 
  different 
  position 
  

   of 
  the 
  branchial 
  plume. 
  

  

  Doridium 
  ct/aneum, 
  D. 
  nir/riim, 
  and 
  D. 
  guttatum, 
  described 
  by 
  Dr. 
  

   Von 
  Martens 
  from 
  the 
  Indian 
  Ocean, 
  have 
  not 
  yet 
  been 
  figured. 
  

   Until 
  all 
  these 
  exotic 
  species 
  have 
  either 
  been 
  compared 
  or 
  much 
  

   more 
  amply 
  described 
  and 
  illustrated, 
  there 
  will 
  remain 
  much 
  un- 
  

   certainty 
  respecting 
  the 
  identification 
  of 
  all 
  or 
  any 
  one 
  of 
  them. 
  

  

  126. 
  Pleurohranchus 
  angasi. 
  (Plate 
  VI. 
  figs. 
  K, 
  K 
  1.) 
  

  

  Animal 
  (in 
  spirit) 
  uniformly 
  pale 
  buff, 
  elongate 
  ovate. 
  Mantle 
  

   probably 
  smooth 
  in 
  life, 
  wrinkled 
  by 
  contraction, 
  not 
  very 
  widely 
  

   produced 
  at 
  the 
  free 
  margin. 
  Foot 
  broad, 
  tapering 
  behind, 
  roundly 
  

   subtruncate 
  in 
  front, 
  where 
  there 
  is 
  a 
  thickening 
  forming 
  a 
  double 
  

   margin 
  beneath 
  the 
  proboscis. 
  The 
  frontal 
  veil 
  is 
  straight 
  in 
  front, 
  

   angular 
  at 
  the 
  sides, 
  which 
  are 
  grooved. 
  Tentacles 
  shortish, 
  slit 
  at 
  

   the 
  outer 
  side, 
  with 
  the 
  minute 
  eye-specks 
  at 
  their 
  base 
  behind. 
  

   Branchial 
  plume 
  consisting 
  of 
  about 
  sixteen 
  leaflets. 
  Penis 
  spine- 
  

   like, 
  very 
  acute, 
  and 
  slightly 
  curved 
  at 
  the 
  tip. 
  

  

  Shell 
  placed 
  well 
  forward, 
  the 
  pale 
  apex 
  being 
  posterior. 
  It 
  is 
  

   browii 
  in 
  front, 
  glossy, 
  and 
  beautifully 
  iridescent 
  on 
  the 
  exterior. 
  

   It 
  consists 
  of 
  about 
  a 
  whorl 
  and 
  a 
  half, 
  the 
  nucleus 
  being 
  spiral 
  and 
  

   hollow 
  within. 
  The 
  last 
  whorl 
  is 
  much 
  prolonged 
  by 
  additional 
  

   strongly 
  defined 
  concentric 
  layers, 
  and 
  also 
  ornamented 
  with 
  fine 
  

   yet 
  distinct 
  transverse 
  striae. 
  The 
  columella 
  is 
  arcuate, 
  and 
  has 
  an 
  

   umbilical 
  groove 
  parallel 
  with 
  it. 
  

  

  