﻿656 
  PBOCEEDlNdS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  

  

  CAMBARUS 
  DIFFICILIS, 
  new 
  species. 
  

   (Plate 
  LXV, 
  figs. 
  1-4.) 
  

  

  Ceplialo-tliorax 
  oval, 
  tlatteued 
  above, 
  of 
  equal 
  length 
  with 
  the 
  abdo- 
  

   men. 
  Carapace 
  obscurely 
  punctate 
  above, 
  lightly 
  granulate 
  on 
  the 
  

   sides; 
  lateral 
  spines 
  of 
  moderate 
  size, 
  branchiostegian 
  spines 
  obsolete, 
  

   anterolateral 
  margins 
  but 
  slightly 
  and 
  bluntly 
  angulatcd, 
  unarmed 
  

   with 
  spines. 
  Kostrum 
  of 
  moderate 
  length, 
  reaching 
  a 
  trifle 
  beyond 
  the 
  

   proximal 
  end 
  of 
  the 
  third 
  antennular 
  segment; 
  upper 
  surface 
  excavate, 
  

   margins 
  convergent 
  and 
  slightly 
  convex 
  from 
  the 
  base 
  to 
  the 
  single 
  

   pair 
  of 
  lateral 
  teeth, 
  which 
  are 
  small 
  and 
  acute, 
  with 
  horny 
  tips; 
  

   acumen 
  of 
  moderate 
  length, 
  acute, 
  horny 
  at 
  the 
  slightly 
  ui)turned 
  tip. 
  

   Postorbital 
  ridges 
  ending 
  anteriorly 
  in 
  a 
  sharp 
  tooth 
  or 
  short 
  sjnne. 
  

   Areola 
  obliterated 
  throughout 
  a 
  considerable 
  part 
  of 
  its 
  length 
  by 
  the 
  

   contiguity 
  of 
  the 
  branchio-cardiac 
  lines. 
  Abdominal 
  pleura^ 
  rounded, 
  

   telson 
  bispinose 
  on 
  each 
  side. 
  Anterior 
  process 
  of 
  epistome 
  squarely 
  

   truncate 
  at 
  the 
  front 
  end. 
  

  

  Antenn;e 
  longer 
  than 
  the 
  body, 
  basal 
  segment 
  unarmed, 
  second 
  seg- 
  

   ment 
  furnished 
  with 
  a 
  spine 
  on 
  the 
  outer 
  side, 
  at 
  the 
  base 
  of 
  the 
  scale; 
  

   scale 
  of 
  moderate 
  width, 
  widest 
  near 
  the 
  middle. 
  

  

  The 
  merus 
  of 
  the 
  chelipeds 
  shows 
  the 
  usual 
  biserially 
  arranged 
  spines 
  

   upon 
  its 
  lower 
  side, 
  and 
  the 
  two 
  obliquely 
  placed 
  spines 
  near 
  the 
  distal 
  

   end 
  of 
  the 
  upper 
  margin 
  ; 
  the 
  carpus 
  is 
  marked 
  by 
  a 
  deep, 
  curved 
  

   longitudinal 
  farrow 
  on 
  the 
  upper 
  side. 
  Just 
  inside 
  of 
  which 
  lies 
  a 
  series 
  

   of 
  about 
  seven 
  small 
  tubercles, 
  the 
  anterior 
  one 
  sharp 
  pointed 
  and 
  (juite 
  

   near 
  to 
  the 
  upper 
  point 
  of 
  articulation 
  with 
  the 
  i^ropodite 
  ; 
  the 
  inner 
  

   border 
  of 
  the 
  carpus 
  is 
  armed 
  with 
  a 
  stout 
  median 
  spine 
  and 
  a 
  smaller 
  

   one 
  near 
  the 
  hinder 
  end 
  of 
  the 
  segment; 
  on 
  the 
  lower 
  face 
  of 
  the 
  seg- 
  

   ment 
  one 
  sees 
  a 
  minute 
  spine 
  at 
  the 
  lower 
  articular 
  surface 
  with 
  the 
  

   propodite, 
  a 
  i)rominent 
  median 
  spine, 
  and 
  a 
  much 
  smaller 
  one 
  between 
  

   the 
  inferior 
  median 
  and 
  the 
  larger 
  spine 
  of 
  the 
  inner 
  border; 
  the 
  chehe 
  

   are 
  very 
  large, 
  a 
  little 
  longer 
  than 
  the 
  cephalo-thorax 
  including 
  the 
  

   rostrum; 
  the 
  palm 
  or 
  basal 
  part 
  is 
  short, 
  its 
  inner 
  border 
  ornamented 
  

   Avith 
  a 
  double 
  row 
  of 
  dentiform 
  tubercles, 
  outside 
  of 
  which, 
  on 
  the 
  

   upper 
  face, 
  appears 
  a 
  row 
  of 
  obsolescent 
  tubercles 
  in 
  line 
  with 
  the 
  

   axis 
  of 
  the 
  movable 
  finger; 
  the 
  fingers 
  are 
  very 
  long 
  (the 
  movable 
  one 
  

   being 
  from 
  two 
  and 
  a 
  half 
  to 
  a 
  little 
  over 
  three 
  times 
  the 
  length 
  of 
  the 
  

   inner 
  border 
  of 
  the 
  palm), 
  pitted 
  and 
  furrowed, 
  armed 
  with 
  blunt 
  teeth 
  

   along 
  their 
  prehensile 
  edges; 
  the 
  inner 
  border 
  of 
  the 
  dactylus 
  is 
  fur- 
  

   nished 
  with 
  dentiform 
  tubercles 
  which 
  show 
  a 
  tendency 
  to 
  an 
  arrange- 
  

   ment 
  in 
  two 
  rows, 
  and 
  Avhich 
  decrease 
  in 
  size 
  from 
  the 
  proximal 
  to 
  the 
  

   distal 
  end 
  of 
  the 
  segment; 
  it 
  is 
  further 
  to 
  be 
  observed 
  that 
  the 
  dactylus 
  

   is 
  bowed 
  inward 
  in 
  such 
  a 
  fashion 
  that 
  the 
  prehensile 
  edge 
  comes 
  into 
  

   contact 
  with 
  the 
  immovable 
  finger 
  throughout 
  the 
  distal 
  two-thirds 
  of 
  

   its 
  length 
  when 
  the 
  fingers 
  are 
  closed, 
  leaving 
  a 
  gape 
  at 
  the 
  base. 
  

  

  The 
  upper 
  surface 
  of 
  the 
  hand 
  and 
  wrist 
  is 
  mottled 
  with 
  dark 
  spots, 
  

  

  