﻿Crustacea 
  of 
  Dominica. 
  11 
  

  

  A 
  single 
  specimen 
  of 
  a 
  prawn 
  taken 
  at 
  Laiou 
  I 
  refer 
  with 
  

   hesitation 
  to 
  the 
  species 
  described 
  by 
  Dr. 
  von 
  Martens 
  from 
  

   Porto 
  Cabello, 
  Venezuela. 
  

  

  In 
  the 
  Dominica 
  individual 
  the 
  rostrum 
  appears 
  to 
  be 
  

   somewhat 
  longer, 
  inasmuch 
  as 
  it 
  projects 
  beyond 
  the 
  peduncle 
  

   of 
  the 
  antennae, 
  and 
  it 
  is 
  armed 
  with 
  thirteen 
  teeth 
  above, 
  six 
  

   of 
  which 
  are 
  situated 
  behind 
  the 
  orbit, 
  and 
  four 
  beneath. 
  

   Furthermore, 
  the 
  second 
  pair 
  of 
  legs 
  are 
  considerably 
  shorter 
  ; 
  

   but 
  although 
  the 
  segments 
  are 
  somewhat 
  thicker, 
  their 
  rela- 
  

   tive 
  length 
  is 
  almost 
  the 
  same 
  as 
  in 
  P. 
  appuni. 
  

  

  Atyidse. 
  

  

  Atya 
  occidentalis 
  (Newport). 
  

  

  Atya 
  occidentalis 
  (Newport), 
  Ann, 
  & 
  Mag. 
  Nat. 
  Hist. 
  xix. 
  p. 
  158 
  

   (1847). 
  

  

  Mr. 
  Ram 
  age 
  sent 
  home 
  no 
  less 
  than 
  thirty-two 
  specimens 
  

   of 
  a 
  species 
  of 
  Atya, 
  all 
  of 
  which 
  I 
  believe 
  to 
  be 
  referable 
  to 
  

   A. 
  occidentalis 
  (Newport). 
  Twelve 
  of 
  these 
  are 
  from 
  Laiou 
  

   (freshwater) 
  and 
  the 
  rest 
  from 
  Laudat, 
  at 
  an 
  altitude 
  of 
  about 
  

   1000 
  feet. 
  I 
  take 
  the 
  opportunity 
  afforded 
  by 
  the 
  possession 
  

   of 
  a 
  number 
  of 
  specimens 
  to 
  recharacterize 
  a 
  species 
  which 
  

   appears 
  to 
  be 
  but 
  little 
  known, 
  and 
  I 
  do 
  this 
  the 
  more 
  gladly 
  

   since 
  the 
  specimens 
  in 
  question 
  exemplify 
  in 
  a 
  marked 
  degree 
  

   the 
  value 
  for 
  the 
  determination 
  of 
  species 
  of 
  the 
  examination 
  

   of 
  a 
  long 
  series 
  of 
  forms, 
  and 
  show 
  no 
  less 
  clearly 
  how 
  unsafe 
  

   is 
  the 
  application 
  of 
  new 
  names 
  to 
  isolated 
  individuals 
  which 
  

   are 
  obviously 
  closely 
  allied 
  to 
  species 
  that 
  have 
  been 
  pre- 
  

   viously 
  described, 
  when 
  in 
  the 
  case 
  of 
  these 
  species 
  nothing, 
  

   or 
  next 
  to 
  nothing, 
  is 
  known 
  respecting 
  the 
  variation 
  which 
  

   accompanies 
  individuality 
  or 
  age. 
  For 
  it 
  is 
  certainly 
  the 
  

   case 
  that 
  from 
  this 
  series, 
  by 
  the 
  careful 
  selection 
  of 
  specimens 
  

   exhibiting 
  extremes 
  of 
  structural 
  modifications 
  and 
  by 
  the 
  

   judicious 
  elimination 
  of 
  those 
  presenting 
  features 
  which 
  fill 
  

   up 
  the 
  interval 
  between 
  the 
  extremes, 
  material 
  might 
  be 
  

   obtained 
  amply 
  sufficient 
  to 
  justify 
  the 
  establishment 
  of 
  no 
  

   less 
  than 
  four 
  species. 
  But 
  inasmuch 
  as 
  I 
  can 
  in 
  no 
  case 
  

   detect 
  a 
  character 
  which, 
  owing 
  to 
  its 
  constancy 
  in 
  some 
  indi- 
  

   viduals 
  and 
  to 
  its 
  total 
  absence 
  in 
  others, 
  falls 
  outside 
  the 
  

   probable 
  limits 
  of 
  individual 
  variation, 
  I 
  am 
  compelled 
  to 
  

   consider 
  the 
  whole 
  series 
  to 
  belong 
  to 
  one 
  species. 
  That 
  this 
  

   should 
  be 
  named 
  occidentalis 
  is 
  shown 
  by 
  the 
  close 
  similarity 
  

   between 
  the 
  medium-sized 
  specimens 
  obtained 
  and 
  the 
  type 
  

   of 
  occidentalis 
  which 
  is 
  preserved 
  in 
  the 
  British 
  Museum. 
  

  

  