﻿20 
  Mr. 
  R. 
  I. 
  Pocock 
  on 
  the 
  

  

  Xiphocaris 
  brevirostris, 
  sp. 
  n. 
  

  

  Kostrum 
  bent 
  slightly 
  downwards, 
  projecting 
  anteriorly 
  

   only 
  as 
  far 
  as 
  the 
  middle 
  of 
  the 
  second 
  segment 
  of 
  the 
  pe- 
  

   duncle 
  of 
  the 
  antennula 
  ; 
  armed 
  above 
  with 
  nineteen 
  teeth, 
  

   three 
  of 
  which 
  are 
  just 
  above 
  the 
  apex, 
  and 
  below 
  in 
  its 
  

   proximal 
  half 
  with 
  sixteen 
  teeth. 
  

  

  Length 
  from 
  base 
  of 
  ophthalmopod 
  to 
  apex 
  of 
  telson 
  49 
  

   millim. 
  

  

  In 
  other 
  respects 
  this 
  species 
  is 
  very 
  like 
  X. 
  gladiator, 
  

   differing 
  from 
  it, 
  however, 
  in 
  being 
  stouter 
  and 
  in 
  possessing 
  

   relatively 
  smaller 
  eyes 
  ; 
  in 
  fact, 
  in 
  exactly 
  the 
  characters 
  

   which 
  serve 
  to 
  separate 
  X. 
  gladiator 
  from 
  X. 
  elongata. 
  

  

  Two 
  specimens 
  (one 
  male, 
  one 
  female 
  with 
  ova). 
  

  

  Synopsis 
  of 
  the 
  Species. 
  

  

  a. 
  Rostrum 
  longer 
  than 
  the 
  cephalothorax 
  elongata 
  (GuSrin). 
  

  

  b. 
  Rostrum 
  shorter 
  than 
  the 
  cephalothorax. 
  

  

  , 
  t, 
  . 
  • 
  , 
  . 
  , 
  , 
  , 
  , 
  I 
  aladiator, 
  var. 
  in- 
  

  

  a\ 
  Rostrum 
  projecting 
  beyond 
  antenna! 
  scale 
  . 
  . 
  j 
  y 
  termedia, 
  var. 
  n. 
  

  

  b 
  x 
  . 
  Rostrum 
  not 
  projecting 
  beyond 
  antennal 
  scale. 
  

  

  a 
  2 
  . 
  Rostrum 
  projecting 
  beyond 
  the 
  proximal 
  

   end 
  of 
  the 
  distal 
  segment 
  of 
  antennular 
  

   peduncle 
  gladiator, 
  sp. 
  n. 
  

  

  b 
  2 
  , 
  Rostrum 
  projecting 
  as 
  far 
  as 
  the 
  middle 
  of 
  

  

  the 
  second 
  segment 
  of 
  antennular 
  peduncle, 
  brevirostris, 
  sp. 
  n. 
  

  

  Whilst 
  examining 
  the 
  above-mentioned 
  specimens 
  of 
  

   Xiphocaris 
  it 
  occurred 
  to 
  me 
  as 
  possible 
  that 
  those 
  that 
  I 
  

   have 
  regarded 
  as 
  distinct 
  may 
  in 
  reality 
  merely 
  represent 
  

   stages 
  in 
  the 
  growth 
  of 
  one 
  species. 
  

  

  Apart 
  from 
  the 
  characters 
  presented 
  by 
  the 
  rostrum 
  I 
  think 
  

   that 
  the 
  differences 
  between 
  the 
  so-called 
  species 
  might 
  be 
  

   easily 
  explained 
  on 
  the 
  hypothesis 
  of 
  variation 
  with 
  age 
  ; 
  for 
  

   gladiator, 
  which 
  is 
  intermediate 
  in 
  size 
  between 
  brevirostris 
  

   and 
  elongata, 
  is 
  also 
  intermediate 
  between 
  them 
  in 
  the 
  other 
  

   respects 
  pointed 
  out, 
  namely 
  the 
  stoutness 
  of 
  the 
  body 
  and 
  

   the 
  size 
  of 
  ophthalmopods 
  ; 
  further, 
  the 
  assumption 
  that 
  the 
  

   specimens 
  of 
  elongata 
  may 
  be 
  young 
  is 
  rendered 
  justifiable 
  

   by 
  the 
  fact 
  that 
  none 
  of 
  the 
  females 
  are 
  with 
  spawn, 
  whilst 
  

   some 
  of 
  those 
  of 
  brevirostris 
  and 
  gladiator, 
  which 
  inhabit 
  

   the 
  same 
  fresh 
  waters, 
  are 
  laden 
  with 
  it. 
  

  

  I 
  should 
  therefore, 
  were 
  it 
  not 
  for 
  the 
  difference 
  in 
  the 
  

  

  