﻿CRUSTACEA. 
  291 
  

  

  or 
  lobe 
  on 
  its 
  inner 
  margin, 
  which 
  fits 
  into 
  a 
  cavity 
  between 
  two 
  

   smaller 
  teeth 
  on 
  the 
  inner 
  margin 
  of 
  the 
  lower 
  finger. 
  These 
  cha- 
  

   racters 
  are, 
  however, 
  less 
  marked 
  in 
  specimens 
  in 
  which 
  the 
  second 
  

   legs 
  are 
  less 
  developed, 
  and 
  there 
  are 
  one 
  or 
  two 
  examples 
  in 
  which 
  

   the 
  chelae 
  scarcely 
  difterin 
  form 
  and 
  proportions 
  from 
  Dana's 
  figure 
  ; 
  

   hence 
  I 
  have 
  not 
  ventured 
  to 
  regard 
  the 
  species 
  as 
  distinct. 
  

  

  A 
  specimen, 
  dried 
  and 
  very 
  imperfect, 
  which 
  probably 
  belongs 
  to 
  

   this 
  species, 
  is 
  in 
  the 
  British-Museum 
  collection 
  from 
  Keppel 
  Island, 
  

   Port 
  Curtis, 
  obtained 
  within 
  the 
  shell 
  of 
  a 
  live 
  Pinna 
  (j. 
  MacgiUi- 
  

   vrmj, 
  H.M.S. 
  'Rattlesnake'), 
  others 
  from 
  the 
  collection 
  of 
  H.M.S. 
  

   ' 
  Herald,' 
  from 
  the 
  interior 
  of 
  Trklacna 
  (without 
  indication 
  of 
  

   locality), 
  and 
  others 
  from 
  Matuka 
  and 
  Ngau 
  (IT. 
  M.S. 
  '■Herald'). 
  

   In 
  all 
  the 
  specimens 
  from 
  the 
  ' 
  Herald 
  ' 
  collection 
  the 
  second 
  pair 
  

   of 
  chelipedes 
  are 
  less 
  developed, 
  as 
  in 
  Dana's 
  figure 
  of 
  this 
  species, 
  

   which 
  was 
  based 
  on 
  a 
  specimen 
  from 
  Tutuila, 
  in 
  the 
  Samoan 
  or 
  

   Navigator 
  group 
  (Crust. 
  U.S. 
  Expl. 
  Exp. 
  xiii. 
  p. 
  571, 
  pi. 
  xxxvii. 
  

   fig. 
  1, 
  1852). 
  

  

  It 
  appears 
  very 
  doubtful 
  whether 
  the 
  P. 
  maculata, 
  Stimpson*, 
  

   from 
  Tridacno' 
  obtained 
  at 
  Bonin, 
  can 
  be 
  regarded 
  as 
  distinct 
  from 
  

   P. 
  tridacncp, 
  from 
  which 
  it 
  is 
  only 
  distinguished 
  by 
  Stimpson 
  by 
  

   its 
  elongated 
  form 
  and 
  slenderer 
  rostrum 
  ; 
  the 
  rostrum 
  is, 
  how- 
  

   ever, 
  described 
  as 
  reaching 
  only 
  to 
  the 
  penultimate 
  joint 
  of 
  the 
  

   antennulary 
  peduncles 
  (and 
  hence 
  shorter 
  than 
  is 
  usiial 
  in 
  P. 
  tri- 
  

   dacna') 
  and 
  truncated 
  at 
  apex. 
  

  

  The 
  genus 
  ConcJiod.yfes, 
  established 
  for 
  this 
  species 
  by 
  Dr. 
  Peters, 
  

   can, 
  I 
  think, 
  scarcely 
  be 
  regarded 
  as 
  generically 
  distinct 
  from 
  

   Pontonia 
  ; 
  but 
  the 
  name 
  may 
  perhaps 
  be 
  conveniently 
  retained 
  as 
  a 
  

   subgeneric 
  designation 
  for 
  P. 
  trklacna' 
  and 
  the 
  allied 
  species. 
  Dr. 
  

   Hilgendorf, 
  who 
  had 
  the 
  opportunity 
  of 
  examining 
  Dr. 
  Peters's 
  

   type, 
  distinguishes 
  it 
  from 
  Pontonia 
  merely 
  by 
  the 
  shorter 
  antennal 
  

   flagellum 
  t 
  ; 
  but 
  the 
  flagellum 
  in 
  P. 
  macrophtJialma 
  (which 
  Dr. 
  Peters 
  

   himself 
  supposes 
  to 
  belong 
  to 
  Conchodytes) 
  is 
  represented 
  as 
  being 
  

   much 
  longer. 
  (See 
  M.-Edwards, 
  Atlas 
  in 
  Cuvier's 
  ' 
  Regno 
  Animal,' 
  

   Crustaces, 
  pi. 
  lii. 
  fig. 
  3.) 
  

  

  12. 
  Harpilius 
  inermis. 
  (Plate 
  XXXII. 
  fig. 
  B.) 
  

  

  Body 
  not 
  compressed, 
  smooth, 
  and 
  dorsally 
  rounded, 
  and 
  without 
  

   spines 
  either 
  on 
  the 
  carapace 
  or 
  postabdomen. 
  Rostrum 
  spiniform, 
  

   rounded 
  and 
  smooth 
  above, 
  longer 
  than 
  the 
  eye-peduncles, 
  rather 
  

   broad 
  at 
  base, 
  appearing 
  acute 
  at 
  apex 
  in 
  a 
  dorsal 
  view, 
  without 
  

   spinules 
  or 
  teeth 
  on 
  its 
  upper 
  or 
  lower 
  margins 
  ; 
  it 
  is 
  laterally 
  

   somewhat 
  compressed, 
  and 
  in 
  a 
  lateral 
  view 
  its 
  apex 
  is 
  rounded. 
  

   The 
  terminal 
  postabdominal 
  segment 
  is 
  rounded 
  above, 
  but 
  narrows 
  

   considerably 
  towards 
  its 
  distal 
  end, 
  which 
  boars 
  several 
  set;e 
  ; 
  the 
  

   lateral 
  margins 
  are 
  unarmed. 
  The 
  eye-peduncles 
  project 
  laterally 
  

   and 
  are 
  of 
  moderate 
  size 
  ; 
  the 
  antennulary 
  peduncles 
  project 
  slightly 
  

  

  * 
  Proc. 
  Acad. 
  Nat. 
  Sci. 
  Philad. 
  p. 
  .38 
  (1800). 
  

   t 
  Sitzungsb. 
  der 
  Akad. 
  Wiseensch. 
  Berlin, 
  p. 
  835 
  (1878). 
  

  

  V2 
  

  

  