﻿Crustacea 
  of 
  Dominica. 
  19 
  

  

  furnished 
  with 
  one 
  mastigobranch, 
  one 
  arthrobranch, 
  and 
  one 
  

   pleurobranch, 
  and, 
  in 
  addition, 
  there 
  is 
  one 
  pleurobranch 
  

   corresponding 
  with 
  the 
  last 
  pereiopod. 
  

  

  Pleon 
  hairy 
  at 
  the 
  margins, 
  compressed, 
  rounded 
  and 
  smooth, 
  

   and 
  neither 
  carinate 
  nor 
  spiny 
  above 
  ; 
  sides 
  of 
  the 
  three 
  

   anterior 
  somites 
  evenly 
  rounded 
  ; 
  lateral 
  portion 
  of 
  the 
  fourth 
  

   somite 
  angularly 
  produced 
  behind, 
  of 
  the 
  fifth 
  likewise 
  pro- 
  

   duced, 
  but 
  more 
  angularly 
  and 
  more 
  sharply 
  ; 
  the 
  sixth 
  

   somite 
  long, 
  narrower 
  behind, 
  furnished 
  beneath, 
  behind, 
  with 
  

   a 
  minute 
  median 
  spine; 
  telson 
  shorter 
  than 
  sixth 
  somite, 
  

   with 
  smooth 
  converging 
  sides 
  and 
  a 
  truncate 
  bifid 
  apex. 
  

  

  Appendages 
  of 
  the 
  pleon 
  hairy, 
  exopodite 
  longer 
  than 
  

   endopodite, 
  both 
  foliaceous 
  ; 
  the 
  exopodites 
  of 
  the 
  first 
  pair 
  

   long 
  and 
  slender; 
  in 
  the 
  male 
  the 
  endopodite 
  is 
  large 
  and 
  

   foliaceous, 
  in 
  the 
  female 
  it 
  is 
  small 
  ; 
  in 
  the 
  sixth 
  somite 
  the 
  

   appendages 
  are 
  ovate, 
  large, 
  and 
  foliaceous 
  ; 
  the 
  exopodite 
  

   considerably 
  longer 
  than 
  the 
  endopodite, 
  armed 
  externally 
  

   with 
  a 
  spine, 
  fringed 
  with 
  hair 
  internally 
  and 
  externally 
  at 
  

   the 
  distal 
  end 
  ; 
  endopodite 
  like 
  the 
  exopodite, 
  but 
  smaller 
  and 
  

   without 
  a 
  spine. 
  

  

  Three 
  specimens 
  (two 
  females, 
  one 
  with 
  ova, 
  one 
  male) 
  

   from 
  Laiou. 
  

  

  Measurement 
  in 
  millimetres 
  of 
  largest 
  female 
  specimen: 
  — 
  

   Length 
  from 
  base 
  of 
  ophthalmopod 
  to 
  apex 
  of 
  telson 
  45, 
  of 
  

   carapace 
  (above) 
  12; 
  width 
  of 
  carapace 
  7; 
  length 
  of 
  rostrum 
  

   6i, 
  of 
  eye 
  3|, 
  of 
  peduncle 
  of 
  antennula 
  6f, 
  of 
  peduncle 
  of 
  

   antenna 
  6^, 
  of 
  antennal 
  scale 
  9, 
  of 
  external 
  maxillipede 
  12, 
  

   of 
  first 
  pereiopod 
  11^, 
  of 
  second 
  17, 
  of 
  third 
  and 
  fourth 
  18, 
  of 
  

   fifth 
  19, 
  of 
  pleon 
  (including 
  telson) 
  33 
  ; 
  width 
  of 
  pleon 
  (il£; 
  

   length 
  of 
  sixth 
  somite 
  7^, 
  width 
  3j, 
  height 
  4| 
  ; 
  length 
  of 
  

   telson 
  6£, 
  of 
  exopodite 
  of 
  tail-fin 
  9^, 
  of 
  endopodite 
  2£. 
  

  

  This 
  species 
  may 
  be 
  distinguished 
  from 
  X. 
  elongata 
  by 
  its 
  

   stouter 
  build, 
  smaller 
  eyes, 
  and 
  shorter 
  rostrum. 
  

  

  Var. 
  intermedia 
  } 
  n. 
  var. 
  

  

  Taken 
  with 
  the 
  above 
  was 
  one 
  female 
  specimen 
  which 
  is 
  like 
  

   them 
  in 
  every 
  respect 
  except 
  as 
  regards 
  the 
  rostrum. 
  This 
  

   organ 
  is 
  considerably 
  longer, 
  being 
  almost 
  as 
  long 
  as 
  the 
  

   upper 
  surface 
  of 
  the 
  carapace, 
  projecting 
  upwards 
  at 
  the 
  apex 
  

   above 
  the 
  plane 
  of 
  the 
  carapace 
  and 
  forwards 
  beyond 
  the 
  

   anterior 
  margin 
  of 
  the 
  antennal 
  scale. 
  So 
  far 
  as 
  the 
  rostrum 
  

   is 
  concerned 
  this 
  variety 
  is 
  intermediate 
  between 
  gladiator 
  

   and 
  elongata. 
  

  

  