﻿No.ll.'ie. 
  OBSEBVATIOXS 
  OX 
  THE 
  ASTACIDJ^—FAXOy. 
  645 
  

  

  not 
  obliterated 
  and 
  the 
  sides 
  of 
  tlie 
  rostrum 
  are 
  less 
  strongly 
  conver- 
  

   gent. 
  This 
  is 
  without 
  d(^ubt 
  to 
  be 
  considered 
  the 
  typical 
  form 
  of 
  

   C 
  clarh'i, 
  since 
  Girard's 
  specimens 
  were 
  collected 
  in 
  the 
  same 
  region, 
  

   somewhere 
  between 
  San 
  Antonio 
  and 
  El 
  Paso 
  del 
  ISTorte. 
  

  

  CAMBARUS 
  ACHERONTIS 
  Lonnberg. 
  

  

  (Plate 
  LXII, 
  figs. 
  1-5.) 
  

  

  CamharitR 
  acheronfis 
  Lonnberg, 
  Zoolog. 
  Anz., 
  XVII, 
  pp. 
  125-127, 
  1894; 
  Biliang 
  

   till 
  K. 
  Sveuska 
  Vet.-Akad. 
  Haadlingar, 
  XX, 
  Pt. 
  4, 
  p. 
  6., 
  figs. 
  1-6, 
  1894. 
  

  

  Female. 
  — 
  Rostrum 
  broad, 
  excavated, 
  superior 
  lateral 
  margius 
  raised 
  

   into 
  sharp 
  carinre 
  which 
  overhang 
  the 
  inferior 
  lateral 
  margins 
  and 
  con- 
  

   tinue 
  backward 
  inside 
  of 
  and 
  parallel 
  with 
  the 
  postorbital 
  ridges; 
  a 
  

   pair 
  of 
  sharp 
  projecting 
  angles 
  or 
  teeth 
  near 
  the 
  tip 
  at 
  base 
  of 
  the 
  acu- 
  

   men 
  ; 
  acumen 
  short, 
  acute. 
  Rostrum, 
  gastric 
  region, 
  and 
  areola 
  smooth 
  

   and 
  polished; 
  sides 
  of 
  carapace 
  thickly 
  studded 
  with 
  small 
  papilhie 
  or 
  

   tubercles; 
  postorbital 
  ridges 
  furnished 
  with 
  a 
  small 
  spine 
  at 
  the 
  ante- 
  

   rior 
  end; 
  areola 
  almost 
  obliterated 
  in 
  the 
  middle 
  by 
  the 
  api)ositiou 
  of 
  

   the 
  branchio 
  cardiac 
  lines; 
  posterior 
  section 
  of 
  carapace 
  equal 
  in 
  length 
  

   to 
  the 
  distance 
  between 
  the 
  cervical 
  groove 
  and 
  the 
  anterior 
  spines 
  of 
  

   the 
  jDostorbital 
  ridges. 
  

  

  Abdomen 
  a 
  little 
  longer 
  than 
  the 
  cephalo-thorax, 
  smooth 
  ; 
  telson 
  

   three 
  or 
  two 
  spined 
  on 
  each 
  side 
  of 
  tbe 
  anterior 
  segment, 
  posterior 
  

   segment 
  subtruncate. 
  

  

  Antenna^, 
  very 
  long, 
  much 
  longer 
  than 
  the 
  body; 
  a 
  small 
  external 
  

   spine 
  behind 
  the 
  base 
  of 
  the 
  antennal 
  scale; 
  anteunal 
  scale 
  very 
  broad, 
  

   broadest 
  at 
  the 
  middle, 
  apical 
  end 
  rounded 
  and 
  armed 
  with 
  a 
  small 
  

   external 
  spine. 
  Epistome 
  short, 
  broad, 
  anterior 
  border 
  convex. 
  

  

  Chelipeds 
  slender; 
  merus 
  furnished 
  with 
  the 
  customary 
  biserial 
  spines 
  

   below, 
  superior 
  margin 
  spinulose, 
  outer 
  and 
  inner 
  faces 
  sj^arsely 
  granu- 
  

   lated; 
  cari)us 
  with 
  a 
  longitudinal 
  furrow 
  above, 
  tuberculiferous, 
  the 
  

   tubercles 
  tending 
  to 
  assume 
  the 
  form 
  of 
  short 
  spines 
  on 
  the 
  inner 
  side; 
  

   chehe 
  subcyliudrical, 
  granulated, 
  the 
  granules 
  on 
  the 
  inner 
  or 
  upper 
  

   margin 
  of 
  the 
  hand 
  taking 
  on 
  the 
  form 
  of 
  blunt 
  spines; 
  fingers 
  long, 
  

   slender, 
  inner 
  and 
  outer 
  sides 
  costate, 
  upper 
  margin 
  of 
  the 
  dactylus 
  

   tuberculate, 
  cutting 
  edges 
  of 
  lingers 
  irregularly 
  denticulate 
  on 
  the 
  

   proximal 
  half 
  

  

  Length 
  75 
  mm.; 
  carapaee 
  39 
  mm.; 
  from 
  tip 
  of 
  rostrum 
  to 
  cervical 
  

   groove 
  23.5 
  mm. 
  ; 
  from 
  cervical 
  groove 
  to 
  posterior 
  border 
  of 
  carapace 
  

   16 
  mm. 
  ; 
  length 
  of 
  rostrum 
  from 
  tip 
  to 
  anterior 
  spines 
  of 
  postorbital 
  

   ridges 
  9 
  mm.; 
  width 
  of 
  rostrum 
  4.5 
  mm. 
  

  

  Annulus 
  ventralis 
  transverse, 
  with 
  a 
  prominent 
  posterior 
  tubercle 
  

   and 
  a 
  crescentic 
  anterior 
  fossa. 
  

  

  In 
  a 
  young 
  male 
  of 
  the 
  second 
  form, 
  43 
  mm. 
  in 
  length, 
  the 
  third 
  pair 
  

   of 
  legs 
  are 
  furnished 
  with 
  a 
  blunt 
  hook 
  on 
  the 
  third 
  segment, 
  while 
  

   the 
  corresponding 
  segment 
  of 
  the 
  fourth 
  pair 
  bears 
  a 
  small 
  tubercle, 
  

   the 
  vestige 
  of 
  the 
  hook 
  of 
  the 
  adult. 
  The 
  first 
  abdominal 
  appendages 
  

  

  