﻿the 
  Species 
  of 
  Limnoi 
  ia. 
  383 
  

  

  been 
  drawn 
  from 
  tlie 
  sliape 
  of 
  the 
  body, 
  the 
  proportions 
  of 
  

   its 
  different 
  segments, 
  and 
  tlie 
  presence 
  or 
  absence 
  of 
  tubercles 
  

   on 
  the 
  dorsal 
  surface 
  of 
  tlie 
  pleon. 
  

  

  himnoria 
  Ugnorum 
  has 
  been 
  fully 
  described 
  by 
  Harger, 
  

   Sars 
  (1897, 
  p. 
  76), 
  and 
  others, 
  and 
  its 
  characters 
  are 
  pretty 
  

   well 
  known. 
  L. 
  antarctica 
  was 
  described 
  in 
  great 
  detail 
  by 
  

   Pfeffer 
  in 
  18<S7, 
  and 
  in 
  the 
  descriptions 
  of 
  L. 
  pfefferi 
  and 
  

   L. 
  andrewsi 
  special 
  notice 
  has 
  been 
  taken 
  of 
  the 
  characters 
  

   distinguishing 
  the 
  species. 
  Of 
  L. 
  segnis 
  only 
  the 
  short 
  

   original 
  description 
  has 
  been 
  published, 
  and 
  it 
  will 
  be 
  con- 
  

   venient 
  to 
  consider 
  its 
  characters 
  here 
  somewhat 
  more 
  fully 
  

   and 
  with 
  special 
  reference 
  to 
  the 
  points 
  mentioned 
  above. 
  

  

  Limnoria 
  segnis, 
  Chilton. 
  

  

  Limnoria 
  segnis, 
  Chilton, 
  1883, 
  p. 
  76, 
  pi. 
  ii. 
  fi^. 
  1; 
  Stebbing, 
  1904, 
  

   p. 
  714. 
  

  

  General 
  Description 
  and 
  Comparison 
  with 
  other 
  Species. 
  — 
  

   The 
  general 
  appearance 
  is 
  in 
  close 
  agreement 
  with 
  L. 
  Ug- 
  

   norum, 
  though 
  the 
  body 
  is 
  usually 
  slightly 
  broader 
  and 
  

   more 
  convex 
  and 
  looks 
  rather 
  more 
  compact. 
  The 
  whole 
  

   surface 
  is 
  thickly 
  covered 
  with 
  short 
  seta?, 
  with 
  some 
  longer 
  

   ones, 
  especially 
  on 
  the 
  margins 
  of 
  the 
  segments. 
  The 
  body 
  

   is 
  generally 
  of 
  a 
  dull 
  white 
  or 
  cream 
  colour, 
  and 
  does 
  not 
  

   show 
  the 
  grey 
  markings 
  usually 
  present 
  on 
  L. 
  Ugnorum. 
  

   As 
  in 
  that 
  species 
  and 
  in 
  L. 
  pfefferi 
  the 
  head 
  is 
  almost 
  

   globular 
  and 
  is 
  narrower 
  than 
  the 
  rest 
  of 
  the 
  body 
  ; 
  the 
  first 
  

   segment 
  of 
  the 
  perseon 
  is 
  longer 
  than 
  any 
  of 
  the 
  succeeding, 
  

   but 
  1 
  have 
  not 
  noticed 
  on 
  it 
  tlie 
  conspicuous 
  dorsal 
  V-shaped 
  

   grooving 
  described 
  by 
  Stebbing 
  for 
  L. 
  pfefferi] 
  the 
  side- 
  

   plates 
  agree 
  generally 
  with 
  those 
  of 
  L. 
  Ugnorum, 
  and 
  the 
  

   same 
  is 
  true 
  of 
  the 
  pleon 
  and 
  the 
  terminal 
  segment. 
  

  

  The 
  fifth 
  segment 
  of 
  the 
  pleon 
  is 
  much 
  longer 
  than 
  any 
  of 
  

   the 
  four 
  preceding, 
  especially 
  in 
  the 
  median 
  line, 
  and 
  in 
  

   dorsal 
  view 
  it 
  shows 
  tlie 
  shape 
  as 
  drawn 
  by 
  PfefFer 
  for 
  

   L. 
  antarctica 
  ; 
  it 
  bears 
  a 
  faint 
  median 
  ridge. 
  Oa 
  the 
  last 
  

   segment, 
  near 
  its 
  anterior 
  margin, 
  there 
  is 
  a 
  slight 
  median 
  

   elevation 
  or 
  tubercle, 
  from 
  which 
  extend 
  posteriorly 
  two 
  faint 
  

   parallel 
  ridges. 
  These 
  markings 
  are 
  visible 
  only 
  in 
  speci- 
  

   mens 
  that 
  have 
  been 
  dried, 
  and 
  even 
  then, 
  owing 
  to 
  the 
  short 
  

   setse 
  covering 
  the 
  general 
  surface 
  of 
  the 
  body 
  and 
  the 
  

   extraneous 
  matter 
  entangled 
  in 
  them, 
  they 
  are 
  not 
  always 
  

   very 
  distinct, 
  especially 
  in 
  smaller 
  specimens; 
  they 
  are, 
  

   however, 
  interesting 
  as 
  showing 
  some 
  approach 
  to 
  the 
  

   tubercles 
  and 
  ridges 
  described 
  by 
  Miss 
  Richardson 
  in 
  

  

  