﻿CRUSTACEA. 
  273 
  

  

  Dana's 
  description 
  of 
  his 
  P. 
  hiunguiculutus 
  *, 
  iu 
  having 
  a 
  distinctly 
  

   trilobate 
  front, 
  the 
  middle 
  lobe 
  of 
  which 
  is 
  broad, 
  subacute, 
  or 
  

   rounded, 
  and 
  not 
  much 
  more 
  prominent 
  than 
  the 
  lateral 
  lobes 
  ; 
  

   whereas 
  in 
  P. 
  biuiu/uieulatus, 
  to 
  which 
  species 
  specimens 
  from 
  the 
  

   Gulf 
  of 
  Suez 
  (R. 
  MacAndreiv) 
  appear 
  to 
  belong, 
  the 
  median 
  lobe 
  is 
  

   very 
  prominent 
  and 
  acute 
  and 
  the 
  lateral 
  lobes 
  obsolete. 
  The 
  spe- 
  

   cimens 
  referred 
  to 
  P. 
  hiungtiicidatus 
  also 
  differ 
  from 
  P. 
  obesulus 
  in 
  

   having 
  the 
  outer 
  surface 
  of 
  the 
  palms 
  of 
  the 
  chelipedes 
  much 
  more 
  

   closely 
  punctulated. 
  The 
  cephalothorax 
  is 
  narrowest 
  in 
  the 
  smallest- 
  

   sized 
  specimens 
  ; 
  and 
  in 
  the 
  female 
  from 
  Port 
  Denison 
  (which 
  is 
  

   one 
  of 
  the 
  largest 
  examples 
  I 
  have 
  seen) 
  is 
  much 
  broader 
  than 
  in 
  

   the 
  others 
  ; 
  but 
  I 
  cannot 
  regard 
  this 
  character 
  by 
  itself 
  as 
  of 
  specific 
  

   importance. 
  

  

  I 
  am 
  inclined 
  to 
  doubt 
  whether 
  the 
  genus 
  Polyonyx 
  is 
  distinct 
  

   from 
  Merjahhrachium. 
  Stimpson 
  merely 
  distinguishes 
  the 
  latter 
  

   on 
  account 
  of 
  the 
  absence 
  of 
  the 
  prominent 
  accessory 
  claw, 
  which 
  

   gives 
  to 
  the 
  dactjli 
  of 
  the 
  species 
  of 
  Polyonyx 
  a 
  biunguiculate 
  

   appearance. 
  The 
  type 
  of 
  MeyaJohrucMum 
  (31, 
  yranuliferum, 
  Stm.) 
  

   is 
  from 
  the 
  West 
  Indies 
  ; 
  but 
  Stimpson 
  refers 
  the 
  P. 
  macrochelii, 
  

   Gibbes, 
  from 
  Carolina, 
  to 
  the 
  genus 
  Polyonyx. 
  The 
  other 
  species 
  of 
  

   the 
  latter 
  genus 
  are 
  Oriental 
  in 
  habitat. 
  

  

  Specimens 
  are 
  referred 
  to 
  P. 
  hiunguiculatus 
  by 
  Mr. 
  Haswell 
  from 
  

   Holborn 
  Island, 
  Port 
  Denison, 
  by 
  whom 
  also 
  this 
  species 
  is 
  retained 
  

   in 
  the 
  genus 
  Porcellana 
  (vide 
  Cat. 
  p. 
  147). 
  

  

  17. 
  Pachycheles 
  pulchellus 
  (Haswell). 
  (Plate 
  XXX. 
  fig. 
  A.) 
  

  

  Porcellana 
  nulchella, 
  Haswell. 
  Proc. 
  Linn. 
  Sac. 
  N. 
  S. 
  Wales, 
  vi. 
  p. 
  768 
  

   (1881) 
  ; 
  Cat. 
  Austr. 
  Crust, 
  p. 
  148 
  (1882). 
  

  

  As 
  Mr. 
  Haswell's 
  description 
  is 
  very 
  brief, 
  I 
  append 
  the 
  following 
  

   from 
  specimens 
  received 
  from 
  Dr. 
  Coppinger 
  : 
  — 
  

  

  The 
  carapace 
  is 
  smooth, 
  rather 
  convex, 
  rounded 
  on 
  the 
  sides, 
  and 
  

   hence 
  somewhat 
  orbiculate 
  in 
  outline, 
  faintly 
  striated 
  on 
  the 
  sides 
  

   at 
  the 
  back 
  of 
  the 
  branchial 
  regions. 
  The 
  front 
  is 
  rather 
  broad, 
  and 
  

   in 
  a 
  dorsal 
  view 
  its 
  margin 
  appears 
  straight 
  ; 
  in 
  an 
  anterior 
  view 
  it 
  

   is 
  seen 
  to 
  be 
  bisinuated, 
  with 
  a 
  broadly 
  rounded 
  but 
  verj' 
  slightly 
  

   prominent 
  median 
  lobe. 
  The 
  orbital 
  and 
  lateral 
  margins 
  of 
  the 
  

   carapace 
  are 
  entire. 
  The 
  first 
  exposed 
  joint 
  of 
  the 
  peduncle 
  of 
  the 
  

   antennae 
  is 
  shorter 
  than 
  the 
  following 
  joint, 
  and 
  has 
  sometimes 
  a 
  

   small 
  blunt 
  prominence 
  on 
  its 
  inner 
  margin 
  ; 
  the 
  third 
  joint 
  is 
  

   short; 
  the 
  flagellum 
  somewhat 
  elongated, 
  with 
  the 
  joints 
  almost 
  

   naked. 
  The 
  ischium 
  of 
  the 
  outer 
  maxillipedes 
  has 
  a 
  spine 
  at 
  its 
  

   outer 
  distal 
  angle 
  ; 
  the 
  next 
  joint 
  has 
  a 
  prominent 
  lobe 
  on 
  its 
  

   inner 
  margin 
  ; 
  the 
  three 
  following 
  joints 
  are 
  robust. 
  The 
  chelipedes 
  

   are 
  robust, 
  but 
  not 
  so 
  broadly 
  dilated 
  as 
  in 
  most 
  species 
  of 
  this 
  

   genus 
  ; 
  the 
  merus 
  or 
  arm 
  is 
  verj' 
  short 
  ; 
  wrist 
  with 
  broad 
  low 
  pro- 
  

   miuences 
  disposed 
  in 
  longitudinal 
  series 
  on 
  its 
  upper 
  surface, 
  and 
  

  

  * 
  Vide 
  U.S. 
  Explor. 
  Exped. 
  xiii., 
  Ci-ust. 
  i. 
  p. 
  411, 
  pi. 
  xxvi. 
  fig. 
  1 
  (1852). 
  

  

  X 
  

  

  