﻿272 
  COLLECTIONS 
  FEOM 
  MELANESIA. 
  

  

  defined 
  by 
  very 
  distinct 
  sulci, 
  and 
  the 
  whole 
  of 
  its 
  upper 
  surface, 
  

   except 
  near 
  the 
  posterior 
  margin, 
  very 
  uneven 
  ; 
  the 
  front 
  is 
  deeply 
  

   concave 
  in 
  the 
  middle 
  line, 
  and 
  its 
  median 
  interautennulary 
  portion 
  

   much 
  deflexed, 
  spiuulose, 
  the 
  spinules 
  of 
  unequal 
  length 
  ; 
  its 
  lateral 
  

   margin 
  armed 
  with 
  about 
  seven 
  spinules, 
  and 
  the 
  protogastric 
  lobes 
  

   also 
  spiuulose 
  ; 
  the 
  peduncles 
  of 
  the 
  antenna) 
  are 
  without 
  spinules. 
  

   The 
  merus-joint 
  of 
  the 
  outer 
  maxillipedes 
  fits 
  into 
  a 
  deep 
  notch 
  in 
  

   the 
  anterior 
  margin 
  of 
  the 
  preceding 
  joint, 
  and 
  is 
  itself 
  excavated 
  

   at 
  its 
  distal 
  end. 
  The 
  single 
  chelipede 
  present 
  in 
  the 
  unique 
  ex- 
  

   ample 
  before 
  me 
  has 
  a 
  spiuulose 
  lobe 
  or 
  tooth 
  at 
  the 
  distal 
  end 
  of 
  

   the 
  inner 
  margin 
  of 
  the 
  arm 
  ; 
  the 
  wrist 
  and 
  palm 
  are 
  flattened 
  on 
  

   the 
  upper 
  surfece, 
  which 
  is 
  armed 
  with 
  tubercles 
  arranged 
  in 
  longi- 
  

   tudinal 
  series, 
  the 
  tubercles 
  themselves 
  for 
  the 
  most 
  part 
  minutely 
  

   spiuulose 
  ; 
  the 
  inner 
  margin 
  of 
  the 
  wrist 
  is 
  armed 
  with 
  three 
  or 
  

   four 
  spines 
  at 
  its 
  base, 
  and 
  beyond 
  with 
  smaller 
  spinules 
  ; 
  the 
  

   posterior 
  margin 
  is 
  armed 
  with 
  about 
  seven 
  spines 
  ; 
  there 
  are 
  two 
  

   spines 
  at 
  the 
  distal 
  end 
  of 
  the 
  inner 
  margin 
  of 
  the 
  palm, 
  and 
  its 
  

   outer 
  margin 
  is 
  spiuulose 
  and 
  pubescent 
  ; 
  the 
  fingers 
  meet 
  closely 
  

   along 
  their 
  inner 
  margins, 
  which 
  are 
  entire, 
  and 
  their 
  outer 
  mar- 
  

   gins 
  are 
  spiuulose. 
  The 
  first 
  pair 
  of 
  ambulatory 
  legs 
  have 
  the 
  ante- 
  

   rior 
  margins 
  of 
  the 
  merus, 
  carpus, 
  and 
  propus 
  armed 
  with 
  a 
  few 
  

   distant 
  spinules, 
  which 
  are 
  almost 
  wholly 
  absent 
  from 
  the 
  same 
  

   joints 
  in 
  the 
  following 
  legs. 
  Colour 
  whitish. 
  The 
  single 
  specimen 
  

   examined 
  is 
  a 
  female 
  : 
  the 
  carapace 
  measures 
  nearly 
  3 
  lines 
  (6 
  mil- 
  

   lim.) 
  in 
  length 
  and 
  2| 
  (5 
  millim.) 
  in 
  breadth 
  ; 
  the 
  chelipede, 
  when 
  

   extended 
  as 
  far 
  as 
  its 
  conformation 
  will 
  aUow, 
  about 
  5 
  lines 
  (11 
  

   millim.). 
  

  

  The 
  single 
  specimen 
  was 
  obtained 
  at 
  Port 
  Molle, 
  between 
  tide- 
  

   marks 
  (No. 
  103), 
  with 
  Fetrolisthcfi 
  japonicus. 
  The 
  description 
  given 
  

   above 
  will 
  show 
  that 
  our 
  specimen 
  differs 
  from 
  Mr. 
  Haswell's 
  type 
  

   in 
  the 
  more 
  uneven 
  carapace 
  with 
  more 
  numerous 
  lateral 
  marginal 
  

   spinules, 
  non-pubescent 
  posterior 
  margin 
  of 
  the 
  wrist 
  of 
  the 
  cheli- 
  

   pede, 
  and 
  in 
  having 
  two 
  spines 
  (not 
  mentioned 
  by 
  Mr. 
  Haswell) 
  at 
  

   the 
  distal 
  end 
  of 
  the 
  anterior 
  margin 
  of 
  the 
  palm 
  (see 
  fig. 
  c). 
  

   If 
  distinct, 
  I 
  would 
  propose 
  to 
  designate 
  this 
  species 
  P. 
  dorsalis. 
  

   It 
  seems, 
  upon 
  the 
  whole, 
  to 
  have 
  more 
  aflSnity 
  with 
  the 
  genus 
  

   PetroUsthes 
  than 
  with 
  Porcellaiia, 
  on 
  which 
  account 
  I 
  refer 
  it, 
  

   although 
  with 
  some 
  hesitation, 
  to 
  that 
  genus. 
  

  

  16. 
  Polyonyx 
  obesulus. 
  (Plate 
  XXIX. 
  fig. 
  D.) 
  

  

  Porcellana 
  obesula, 
  White, 
  List 
  Crust. 
  Brit. 
  Mus. 
  p. 
  130 
  (1847), 
  de- 
  

   script. 
  nulla. 
  

  

  I 
  refer 
  to 
  this 
  species, 
  though 
  somewhat 
  doubtfully, 
  a 
  female 
  

   obtained 
  from 
  Port 
  Denison, 
  4 
  fms. 
  (No. 
  122), 
  also 
  one 
  from 
  Prince 
  

   of 
  Wales 
  Channel, 
  7 
  fms. 
  (No. 
  1(59), 
  one 
  from 
  West 
  Island, 
  7 
  fms., 
  

   and 
  one 
  from 
  Port 
  Darwin, 
  12 
  fms. 
  These 
  examples 
  resemble 
  the 
  

   three 
  specimens 
  in 
  the 
  British-Museum 
  collection, 
  and 
  diff'er 
  from 
  

  

  