﻿CEUSTACEA. 
  255 
  

  

  exists 
  on 
  the 
  fifth 
  segment 
  ; 
  the 
  terminal 
  segment 
  is 
  much 
  narrower 
  

   than 
  the 
  preceding, 
  acute 
  and 
  constricted 
  at 
  base. 
  The 
  eyes 
  are 
  

   placed 
  in 
  very 
  small 
  orbits 
  ; 
  the 
  antennules 
  lie 
  in 
  oblique 
  fossettes 
  ; 
  

   the 
  bases 
  of 
  the 
  antennas 
  are 
  almost 
  completely 
  fused 
  with 
  the 
  sur- 
  

   rounding 
  parts 
  of 
  the 
  carapace 
  (in 
  the 
  single 
  specimen 
  examined), 
  

   and 
  scarcely 
  any 
  trace 
  remains 
  of 
  a 
  flagellum. 
  The 
  merus-joint 
  of 
  

   the 
  outer 
  maxillipedes 
  is 
  triangulate, 
  and 
  shorter 
  than 
  the 
  preceding 
  ; 
  

   the 
  exognath 
  has 
  its 
  outer 
  margin 
  straight, 
  and, 
  although 
  robust, 
  is 
  

   narrower 
  than 
  the 
  ischium 
  of 
  the 
  endognath, 
  it 
  does 
  not 
  reach 
  to 
  

   the 
  extremity 
  of 
  the 
  merus-joint. 
  The 
  chelipedes 
  are 
  subequal 
  and 
  

   of 
  moderate 
  length, 
  with 
  the 
  joints 
  granulated, 
  but 
  otherwise 
  un- 
  

   armed 
  ; 
  merus 
  trigonous 
  ; 
  carpus 
  very 
  short 
  ; 
  palm 
  externally 
  rather 
  

   convex, 
  with 
  an 
  angulated 
  prominence 
  on 
  its 
  inner 
  surface, 
  shorter 
  

   than 
  the 
  fingers, 
  which 
  externally 
  are 
  longitudinally 
  sulcated, 
  meet 
  

   along 
  their 
  inner 
  margins 
  when 
  closed 
  (these 
  margins 
  being 
  minutely 
  

   denticulated), 
  and 
  are 
  concave 
  internally 
  toward 
  and 
  somewhat 
  

   incurved 
  at 
  the 
  tips. 
  The 
  ambulatory 
  legs 
  (which 
  are 
  partially 
  

   concealed 
  beneath 
  the 
  carapace) 
  have 
  all 
  the 
  joints 
  strongly 
  gra- 
  

   nulated 
  ; 
  the 
  dactyle 
  slender, 
  and 
  longer 
  than 
  the 
  preceding 
  joints. 
  

   The 
  colour 
  (in 
  spirit) 
  of 
  the 
  single 
  specimen 
  is 
  nearly 
  white. 
  Length 
  

   not 
  quite 
  3 
  lines 
  (6 
  millim.), 
  breadth 
  nearly 
  4 
  lines 
  (8 
  millim.). 
  

  

  The 
  single 
  specimen 
  was 
  collected 
  at 
  Port 
  Molle, 
  5-12 
  fms. 
  

   (No. 
  118), 
  and 
  is 
  a 
  male, 
  the 
  first, 
  I 
  believe, 
  recorded 
  of 
  this 
  genus. 
  

  

  The 
  very 
  prominent 
  front 
  seems 
  to 
  distinguish 
  this 
  species 
  from 
  

   all 
  hitherto 
  recorded, 
  except 
  Oreopliorus 
  jp^tneus*, 
  from 
  New 
  

   Caledonia, 
  which 
  is 
  only 
  distinguished 
  by 
  the 
  much 
  shorter, 
  

   more 
  dilated 
  immobile 
  fingers 
  of 
  the 
  chelipedes, 
  and 
  by 
  having 
  the 
  

   lateral 
  margins 
  of 
  the 
  carapace 
  marked 
  by 
  three 
  closed 
  fissures, 
  

   whereas 
  in 
  0. 
  frontalis 
  there 
  are 
  but 
  two, 
  which 
  meet 
  behind 
  and 
  

   circumscribe 
  the 
  hepatic 
  region. 
  There 
  are 
  two 
  specimens 
  that 
  

   probably 
  belong 
  to 
  0. 
  petneus 
  in 
  the 
  collection 
  of 
  the 
  Museum, 
  froni 
  

   Shark 
  Bay, 
  W. 
  Australia 
  {F. 
  M. 
  Ecn/ner, 
  H.M.S. 
  ' 
  Herald 
  '). 
  These 
  

   forms 
  are 
  certainly 
  intermediate 
  between 
  Oreophorus 
  and 
  Tlos, 
  but 
  

   seem 
  to 
  me 
  to 
  have 
  more 
  affinity 
  with 
  the 
  former 
  gejius, 
  since 
  in 
  

   Tlos 
  muriger, 
  Ad. 
  & 
  White 
  (the 
  typical 
  species), 
  the 
  front 
  is 
  not 
  at 
  

   all 
  prominent, 
  and 
  its 
  margin, 
  with 
  the 
  antero-lateral 
  margins 
  of 
  

   the 
  carapace, 
  is 
  dorsally 
  reflexed. 
  

  

  In 
  the 
  elongated 
  fingers 
  it 
  resembles 
  0. 
  rugosus, 
  Stimpson, 
  as 
  

   figured 
  by 
  A. 
  Milne-Edwards 
  t, 
  from 
  the 
  Loochoo 
  Islands 
  and 
  Cochin 
  

   China, 
  which, 
  however, 
  has 
  a 
  much 
  less 
  prominent 
  front 
  and 
  the 
  

   carapace 
  more 
  coarsely 
  punctulated, 
  and 
  is 
  without 
  the 
  hepatic 
  

   sulcus. 
  Mr. 
  Haswell 
  (Cat. 
  p. 
  130) 
  records 
  0. 
  ru'gosus 
  from 
  Port 
  

   Denison 
  ; 
  but 
  as 
  his 
  description 
  is 
  merely 
  abbreviated 
  from 
  that 
  of 
  

   Milne-Edwards, 
  I 
  am 
  unable 
  to 
  say 
  Avhether 
  the 
  specimens 
  there" 
  

   coUected 
  afford 
  any 
  basis 
  for 
  uniting 
  0. 
  rngosus 
  and 
  0. 
  frontalis. 
  

  

  * 
  Tlos 
  petrceus, 
  A. 
  M.-Edwards, 
  ISouv. 
  Arcli. 
  Mus. 
  Hist. 
  Nat. 
  x. 
  p. 
  51, 
  pi. 
  iii. 
  

   fig. 
  1 
  (1874). 
  

  

  t 
  Ann. 
  Soc. 
  Entom. 
  France, 
  ser. 
  4, 
  r. 
  p. 
  lo2, 
  pi. 
  ti. 
  fig. 
  3 
  (1865). 
  

  

  