﻿CRXrSTACEA. 
  537 
  

  

  42. 
  Tetralia 
  cavimanus, 
  Heller. 
  

  

  Seychelles, 
  4-12 
  fms. 
  (No. 
  194), 
  nine 
  specimens 
  ; 
  Etoile 
  Island, 
  

   13 
  fms. 
  (No. 
  191), 
  five 
  specimens. 
  

  

  Specimens 
  are 
  in 
  the 
  British-Museum 
  collection 
  from 
  Rodriguez 
  

   {H. 
  H. 
  Slater) 
  ; 
  lied 
  Sea, 
  Gulf 
  of 
  Suez 
  {11. 
  Mac 
  Andrew) 
  ; 
  Daedalus 
  

   Shoal 
  {Lt.-Col. 
  Playfair) 
  ; 
  Tiji 
  Islands, 
  Ovalau, 
  Totoya 
  {H.M.8. 
  

   ^Herald''); 
  and 
  others 
  without 
  special 
  locality. 
  In 
  some 
  specimens 
  

   there 
  is 
  a 
  very 
  distinct 
  transverse 
  band 
  of 
  daiker 
  colour 
  on 
  the 
  front 
  ; 
  

   in 
  others 
  it 
  is 
  scarcely, 
  or 
  not 
  at 
  all, 
  discernible. 
  The 
  pit 
  on 
  the 
  

   outer 
  margin 
  of 
  the 
  hand 
  near 
  the 
  wrist, 
  whereby 
  Dr. 
  Heller 
  dis- 
  

   tinguishes 
  this 
  species 
  from 
  T. 
  glaherrima 
  (Herbst), 
  varies 
  greatly 
  

   in 
  depth 
  : 
  ordinarily, 
  in 
  well-grown 
  and 
  even 
  in 
  smaller 
  examples, 
  

   it 
  is 
  deep, 
  well 
  defined, 
  and 
  clothed 
  with 
  hair 
  ; 
  but 
  in 
  other 
  rather 
  

   small 
  specimens 
  it 
  is 
  so 
  shallow 
  as 
  scarcely 
  to 
  be 
  distinguishable 
  

   and 
  devoid 
  of 
  hairs. 
  Ordinarily, 
  in 
  adult 
  males, 
  the 
  lower 
  finger 
  of 
  

   the 
  larger 
  chelipede 
  is 
  more 
  or 
  less 
  strongly 
  dentated 
  on 
  its 
  inner 
  

   margin, 
  and 
  there 
  is 
  scarcely 
  any 
  interspace 
  between 
  the 
  fingers 
  

   when 
  closed 
  ; 
  but 
  in 
  two 
  very 
  dark-coloured 
  males 
  from 
  the 
  

   Seychelles, 
  in 
  the 
  ' 
  Alert 
  ' 
  collection, 
  the 
  fingers 
  are 
  scarcely 
  

   dentated 
  and 
  are 
  strongly 
  arcuated, 
  meeting 
  only 
  at 
  the 
  tips. 
  A 
  

   similar 
  variation 
  occurs 
  in 
  a 
  male 
  from 
  the 
  collection 
  of 
  H.M.S. 
  

   ' 
  Herald,' 
  which, 
  on 
  account 
  of 
  the 
  entire 
  absence 
  of 
  the 
  palmar 
  

   pit, 
  is 
  referred 
  to 
  T. 
  c/laberrima. 
  

  

  I 
  think 
  the 
  T. 
  heterodactyla 
  of 
  Heller 
  is 
  probably 
  a 
  mere 
  variety 
  

   of 
  T. 
  cavimanus, 
  to 
  which 
  species 
  (if, 
  indeed, 
  it 
  be 
  distinct 
  from 
  

   T. 
  glaherrima) 
  nearly 
  all 
  the 
  specimens 
  of 
  this 
  genus 
  in 
  the 
  Museum 
  

   collection 
  must 
  be 
  referred. 
  Although 
  several 
  species 
  of 
  this 
  genus 
  

   have 
  been 
  described, 
  of 
  earlier 
  date 
  than 
  T. 
  cavimanus, 
  by 
  l)ana, 
  

   ■Stimpson, 
  and 
  Lucas, 
  by 
  none 
  of 
  these 
  authors, 
  I 
  believe, 
  is 
  any 
  

   mention 
  made 
  of 
  the 
  subbasal 
  pit 
  on 
  the 
  palm 
  of 
  the 
  chelipede 
  

   which 
  is 
  so 
  characteristic 
  of 
  T. 
  cavimanus. 
  

  

  pedes, 
  I 
  am 
  not 
  even 
  sure 
  whethei" 
  it 
  should 
  be 
  referred 
  to 
  the 
  Cyclometopa 
  or 
  

   to 
  the 
  Catometopa. 
  In 
  most 
  of 
  its 
  clmracters, 
  however, 
  it 
  nearly 
  resembles 
  a 
  

   species 
  of 
  Jrapcsia, 
  differing 
  mainly 
  in 
  the 
  more 
  elongated 
  convex 
  and 
  regu- 
  

   larly 
  hexagonal 
  carapace 
  and 
  in 
  the 
  dactyli 
  of 
  the 
  ambulatory 
  legs. 
  The 
  cara- 
  

   pace 
  is 
  smooth 
  and 
  slightly 
  but 
  regularly 
  convex 
  ; 
  the 
  front 
  is 
  about 
  half 
  the 
  

   greatest 
  width 
  of 
  the 
  carapace, 
  and 
  is 
  divided 
  by 
  three 
  notches 
  into 
  four 
  promi- 
  

   nent 
  triangular 
  teeth, 
  the 
  median 
  notch 
  being 
  the 
  deepest 
  ; 
  there 
  is 
  also 
  a 
  small 
  

   spinule 
  or 
  tooth 
  at 
  the 
  inner 
  supraocular 
  angle, 
  and 
  a 
  short 
  spine 
  at 
  the 
  widest 
  

   part 
  of 
  the 
  carapace 
  at 
  the 
  angle 
  where 
  the 
  autero-lateral 
  and 
  postero-lateral 
  

   margins 
  unite. 
  The 
  endostonie 
  or 
  palate 
  has 
  faintly 
  indicated 
  longitudinal 
  

   ridges. 
  The 
  postabdonien 
  is 
  shaped 
  nearly 
  as 
  in 
  Ira^jf^/a. 
  As 
  in 
  7V«^er/«, 
  the 
  

   inner 
  and 
  inferior 
  margin 
  of 
  the 
  orbit 
  reaches 
  to 
  the 
  front 
  and 
  excludes 
  the 
  

   antennte, 
  and 
  bears 
  a 
  strong 
  spine; 
  the 
  basal 
  peduncular 
  joint 
  of 
  the 
  antenna? 
  

   is 
  rather 
  short, 
  and 
  the 
  penultimate 
  joint 
  reaches 
  to 
  the 
  frontal 
  margin. 
  The 
  

   outer 
  maxillipedes 
  present 
  nothing 
  remarkable, 
  having 
  a 
  truncated 
  merus-joint, 
  

   and 
  exognath 
  reaching 
  to 
  its 
  extero-distal 
  angle. 
  Of 
  the 
  legs 
  only 
  the 
  third 
  aud 
  

   fourth 
  are 
  present 
  on 
  each 
  side 
  ; 
  tliese 
  are 
  rather 
  longer 
  and 
  slenderer 
  than 
  in 
  

   Trapesia, 
  and 
  the 
  three 
  terminal 
  joints 
  are 
  somewhat 
  hairy 
  ; 
  the 
  dactyli 
  are 
  

   armed 
  on 
  their 
  inferior 
  margin 
  with 
  about 
  half-a-dozen 
  spinules, 
  which 
  increase 
  

   successively 
  in 
  length. 
  Colour 
  (in 
  spirit) 
  yellowish 
  white. 
  Length 
  of 
  carapace 
  

   nearly 
  4^ 
  lines 
  (9 
  iniilim.), 
  breadth 
  nearly 
  5 
  lines 
  (10 
  millim.). 
  

  

  