﻿NO. 
  1136. 
  OBSERVATIONS 
  ON 
  THE 
  ASTACIDJE— 
  FAXON. 
  685 
  

  

  PARASTACUS 
  VARICOSUS, 
  new 
  species. 
  

   (Plate 
  LXIX.) 
  

  

  Similar 
  to 
  P. 
  saffordl, 
  but 
  different 
  in 
  the 
  folloAviug 
  particulars 
  : 
  The 
  

   braiichio-cardiac 
  lines 
  bounding 
  the 
  areola 
  are 
  elevated 
  so 
  as 
  to 
  form 
  

   very 
  prominent, 
  rounded 
  ridges, 
  serrated 
  externally 
  ; 
  these 
  ridges 
  run 
  

   a 
  short 
  distance 
  down 
  the 
  cervical 
  groove 
  in 
  front, 
  but 
  cease 
  before 
  

   reaching 
  the 
  hind 
  bordei- 
  of 
  the 
  carapace. 
  The 
  cheliped 
  is 
  very 
  much 
  

   longer 
  than 
  ini*. 
  saffordi; 
  the 
  distal 
  end 
  of 
  the 
  merus, 
  which 
  in 
  the 
  lat- 
  

   ter 
  species 
  only 
  reaches 
  to 
  the 
  subocular 
  angle, 
  in 
  P. 
  varicosus 
  attains 
  

   to 
  the 
  level 
  of 
  the 
  rostrum; 
  the 
  hand, 
  too, 
  is 
  very 
  much 
  longer, 
  and 
  

   dift'erent 
  in 
  outline, 
  the 
  superior 
  and 
  inferior 
  margins 
  being 
  straio-ht 
  

   instead 
  of 
  convex, 
  while 
  the 
  external 
  face 
  is 
  beveled 
  off 
  so 
  as 
  to 
  form 
  

   a 
  nearly 
  flat 
  field, 
  oblique 
  to 
  the 
  vertical 
  plane 
  of 
  the 
  hand, 
  on 
  each 
  

   side 
  of 
  a 
  low, 
  blunt, 
  longitudinal 
  keel, 
  which 
  runs 
  from 
  the 
  carpal 
  

   joint 
  to 
  the 
  base 
  of 
  the 
  thumb. 
  In 
  P. 
  saffordi 
  the 
  su])erior 
  and 
  inferior 
  

   margins 
  of 
  the 
  hand 
  are 
  distinctly 
  convex, 
  the 
  external 
  face 
  swollen 
  

   and 
  roundish. 
  The 
  dorsal 
  surface 
  of 
  the 
  rostrum 
  is 
  conspicuously 
  

   pitted 
  in 
  i'. 
  varicosus, 
  obscurely 
  or 
  not 
  at 
  all 
  pitted 
  in 
  P. 
  saffordi. 
  

   The 
  anterior 
  ventral 
  margin 
  of 
  the 
  proximal 
  antennal 
  segment 
  is 
  armed 
  

   with 
  two 
  spines 
  in 
  the 
  former 
  species; 
  one 
  of 
  these 
  spines 
  lies 
  in 
  front 
  

   of 
  the 
  orifice 
  of 
  the 
  green 
  gland, 
  the 
  other 
  at 
  the 
  external 
  angle 
  of 
  the 
  

   segment. 
  In 
  P. 
  saffordi 
  only 
  one 
  of 
  these 
  spines 
  exists 
  — 
  the 
  one 
  at 
  

   the 
  external 
  angle 
  of 
  the 
  segment. 
  The 
  i^osterior 
  border 
  of 
  both 
  

   branches 
  of 
  the 
  swimmerets 
  has 
  a 
  more 
  truncate 
  outline 
  in 
  P. 
  varico- 
  

   sus 
  than 
  in 
  P. 
  saffordi. 
  

  

  Length 
  100 
  mm.; 
  cara])ace 
  40 
  mm.; 
  from 
  tip 
  of 
  rostrum 
  to 
  cervical 
  

   groove 
  31 
  mm.; 
  from 
  cervical 
  groove 
  to 
  posterior 
  border 
  of 
  carapace 
  

   15 
  mm.; 
  abdomen 
  52 
  mm.; 
  width 
  of 
  areola 
  5 
  mm.; 
  cheliped 
  91 
  mm.; 
  

   merus 
  21 
  mm.; 
  length 
  of 
  chela 
  40 
  mm.; 
  breadth 
  of 
  chela 
  13 
  mm.; 
  

   length 
  of 
  dactylus 
  22 
  mm. 
  

  

  The 
  number 
  and 
  arrangement 
  of 
  the 
  branchial 
  organs 
  are 
  exhibited 
  

   in 
  the 
  subjoined 
  table: 
  

  

  AKTHROBKANCHI.?i. 
  

  

  Somite. 
  Podobbanchije. 
  . 
  . 
  PLEUROBEANCHi.Ti. 
  

  

  Anterior. 
  Po.sterior. 
  

  

  VII. 
  . 
  . 
  . 
  0(ei.?-) 
  ..0....0....0 
  = 
  0(ep/-) 
  

  

  VIII. 
  ...1.. 
  ..!.... 
  0....0 
  ^2 
  

  

  IX. 
  ... 
  1 
  .... 
  1 
  .... 
  1 
  .... 
  =3 
  

  

  X. 
  ... 
  1 
  .... 
  1 
  .... 
  1 
  .... 
  =3 
  

  

  XI. 
  ... 
  1 
  .... 
  1 
  .... 
  1 
  .... 
  1 
  =4 
  

  

  XII. 
  ...1....1....1....1 
  =4 
  

  

  XIII. 
  ... 
  1 
  .... 
  1 
  .... 
  r 
  .... 
  I 
  = 
  3 
  + 
  1- 
  

  

  XIV. 
  ...0....0....0....1 
  =.1 
  

  

  6 
  + 
  ep;- 
  + 
  6 
  + 
  4 
  + 
  /' 
  -f 
  4 
  =: 
  20 
  + 
  r 
  + 
  epr 
  

  

  The 
  epipod 
  of 
  the 
  first 
  maxillipeds 
  bears 
  about 
  twenty 
  gill 
  filaments 
  

   on 
  the 
  upper 
  half 
  of 
  its 
  external 
  face. 
  The 
  posterior 
  arthrobranchia 
  

  

  p. 
  771 
  ; 
  The 
  Crayfish, 
  p. 
  250, 
  fig. 
  64, 
  1880.— 
  Oktmann, 
  Zoolog. 
  Jahrb,, 
  Abth. 
  f. 
  Sy8t.,VI', 
  

   p. 
  9, 
  1891. 
  Habitat. 
  — 
  Southern 
  Brazil: 
  Porto 
  Alegre 
  and 
  near 
  R(idersberg 
  (von 
  

   Martens), 
  Rio 
  Grande 
  do 
  Sul, 
  Sao 
  Lonrenzo 
  (Ortmann). 
  Types 
  in 
  Berlin 
  Zoolog. 
  

   Mus., 
  Nos. 
  3322, 
  3448 
  (von 
  Martens). 
  

  

  