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  COLLECTIONS 
  FEOM 
  THE 
  WESTEEK 
  INDIAN 
  OCEAN. 
  

  

  margin 
  of 
  the 
  rostrum, 
  whereas 
  in 
  P. 
  canaliculatus 
  there 
  is 
  commonly 
  

   but 
  one 
  ; 
  and 
  it 
  is 
  not 
  stated 
  in 
  the 
  author's 
  description 
  whether 
  the 
  

   terminal 
  segment 
  of 
  P. 
  hrevirostris 
  bears 
  lateral 
  marginal 
  spinules. 
  

   As 
  the 
  type 
  was 
  from 
  Eealejo, 
  on 
  the 
  west 
  coast 
  of 
  Nicaragua, 
  the 
  

   range 
  of 
  P. 
  canaliculatus 
  (if 
  it 
  be 
  identical 
  with 
  that 
  species) 
  seems 
  

   to 
  extend 
  eastward 
  to 
  the 
  American 
  coast. 
  

  

  I 
  may 
  add 
  here, 
  that 
  P. 
  occidentalism 
  Streets*, 
  from 
  the 
  Isthmus 
  

   of 
  Panama, 
  to 
  which 
  reference 
  is 
  not 
  made 
  in 
  my 
  paper 
  above 
  re- 
  

   ferred 
  to, 
  seems 
  to 
  be 
  identical 
  with 
  P. 
  sti/lirostris, 
  Stimpson, 
  which 
  

   I 
  supposed 
  (in 
  1878) 
  to 
  be 
  synonymous 
  with 
  P. 
  indicus 
  ; 
  but 
  accord- 
  

   ing 
  to 
  Mr. 
  Spence 
  Bate, 
  who 
  has 
  since 
  examined 
  the 
  types 
  in 
  the 
  

   Paris 
  collection, 
  not 
  only 
  P. 
  indicus 
  but 
  also 
  P. 
  semisulcatus, 
  De 
  Haan, 
  

   P. 
  carinatus, 
  Dana, 
  P. 
  tuhiteyisis, 
  Heller, 
  and 
  P. 
  escidentKS, 
  Haswell, 
  

   are 
  varieties 
  of 
  P. 
  monodon, 
  Fabricius 
  (vide 
  Ann. 
  & 
  Mag. 
  Nat. 
  Hist, 
  

   ser. 
  5, 
  vol. 
  viii. 
  p. 
  177. 
  pi. 
  xii. 
  fig. 
  5, 
  and 
  p. 
  178, 
  1881). 
  The 
  designa- 
  

   tion 
  P. 
  stijlirostris 
  has 
  precedence 
  by 
  a 
  few 
  weeks 
  only 
  over 
  P. 
  

   occidentalis. 
  

  

  8. 
  PensDUS 
  richtersii. 
  (Plate 
  LII. 
  fig. 
  A.) 
  

  

  Carapace 
  with 
  the 
  cervical 
  region 
  scantily 
  clothed 
  with 
  a 
  short 
  

   pubescence. 
  Kostrum 
  very 
  short, 
  reaching 
  about 
  halfway 
  to 
  the 
  

   end 
  of 
  the 
  eye-peduncles, 
  ascending 
  slightly, 
  and 
  laterally 
  com- 
  

   pressed 
  ; 
  armed 
  above 
  with 
  six 
  teeth, 
  of 
  which 
  the 
  two 
  posterior 
  are 
  

   situated 
  on 
  the 
  dorsal 
  surface 
  of 
  the 
  carapace, 
  and 
  behind 
  these, 
  

   but 
  at 
  no 
  great 
  distance, 
  on 
  the 
  gastric 
  region 
  is 
  another 
  tooth 
  ; 
  the 
  

   lower 
  margin, 
  iinder 
  a 
  low 
  magnifying-power, 
  appears 
  entire, 
  but 
  is 
  

   very 
  minutely 
  denticulated 
  ; 
  the 
  distal 
  end 
  is 
  subacute, 
  but 
  not 
  pro- 
  

   longed 
  into 
  a 
  spine. 
  On 
  the 
  carapace 
  is 
  an 
  antennal 
  and 
  hepatic 
  

   spine, 
  and 
  also 
  a 
  small 
  supraocular 
  spine 
  or 
  tooth 
  ; 
  its 
  dorsal 
  sur- 
  

   face, 
  behind 
  the 
  gastric 
  spine, 
  is 
  not 
  distinctly 
  carinated. 
  The 
  post- 
  

   abdomen 
  is 
  smooth 
  and 
  nearly 
  glabrous 
  ; 
  its 
  fifth 
  and 
  sixth 
  seg- 
  

   ments 
  are 
  slightly 
  dorsally 
  carinated, 
  but 
  the 
  carina 
  does 
  not 
  

   terminate 
  in 
  a 
  spine 
  ; 
  there 
  is 
  a 
  very 
  small 
  spiniform 
  tooth 
  at 
  the 
  

   postero-lateral 
  angles 
  of 
  the 
  sixth 
  segment; 
  the 
  terminal 
  segment 
  

   is 
  narrow 
  and 
  acuminate 
  at 
  its 
  distal 
  extremity, 
  dorsally 
  caualicu- 
  

   lated 
  in 
  its 
  proximal 
  half, 
  with 
  three 
  pairs 
  of 
  lateral 
  mobile 
  spines, 
  

   of 
  which 
  the 
  posterior 
  pair 
  are 
  much 
  longer 
  and 
  jointed 
  in 
  the 
  

   middle. 
  The 
  cyc-peduncles 
  are 
  shaped 
  nearly 
  as 
  in 
  P. 
  velutinus, 
  

   and 
  scarcely 
  reach 
  to 
  the 
  distal 
  end 
  of 
  the 
  antepenultimate 
  joint 
  of 
  

   the 
  antennulary 
  peduncles, 
  the 
  longer 
  of 
  whose 
  flagella 
  is 
  shorter 
  

   than 
  the 
  carapace. 
  The 
  peduncle 
  of 
  the 
  antennee 
  is 
  concealed, 
  in 
  a 
  

   dorsal 
  view, 
  by 
  the 
  much 
  longer 
  antennal 
  scale, 
  which 
  reaches 
  

   nearly 
  to 
  the 
  distal 
  end 
  of 
  the 
  peduncle 
  of 
  the 
  antennules 
  ; 
  the 
  an- 
  

   tennal 
  flagellum 
  is 
  slender 
  and 
  nearly 
  naked 
  (broken 
  in 
  the 
  speci- 
  

   men 
  described) 
  ; 
  the 
  outer 
  maxillipedes 
  are 
  short, 
  scarcely 
  reaching 
  

   to 
  the 
  end 
  of 
  the 
  eyes. 
  The 
  legs 
  present 
  nothing 
  remarkable 
  ; 
  

   there 
  is 
  a 
  small 
  spine 
  on 
  the 
  second 
  and, 
  I 
  think, 
  the 
  third 
  joint 
  

  

  * 
  Proc. 
  Acad. 
  Nat. 
  Sci. 
  Philad. 
  p. 
  242 
  (1871). 
  

  

  