﻿G. 
  M. 
  Thomson, 
  — 
  On 
  the 
  Xew 
  Zealand 
  Eatomostraca. 
  261 
  

  

  It 
  is 
  with 
  considerable 
  liesitation 
  that 
  I 
  advance 
  the 
  above 
  as 
  distinct 
  

   species. 
  As 
  Sir 
  Jolm 
  Lubbock 
  states 
  (Linn. 
  Soc. 
  Trans. 
  Vol. 
  XXIV., 
  p. 
  206), 
  

   the 
  relative 
  length 
  of 
  the 
  carapace 
  and 
  the 
  form 
  of 
  the 
  caudal 
  lamella 
  vary 
  

   so 
  much 
  in 
  different 
  individuals, 
  even 
  when 
  taken 
  from 
  the 
  same 
  pool, 
  that 
  

   they 
  do 
  not 
  constitute 
  good 
  characters 
  on 
  which 
  to 
  found 
  new 
  species. 
  

   Though 
  the 
  specimens 
  examined 
  by 
  me 
  were 
  sufficiently 
  distinct 
  to 
  be 
  

   readily 
  recognised 
  and 
  separated 
  into 
  two 
  lots 
  without 
  any 
  close 
  investiga- 
  

   tion, 
  yet 
  I 
  am 
  inclined 
  to 
  think 
  that 
  both 
  constitute 
  only 
  varieties 
  of 
  a 
  

   wide-spread 
  species. 
  In 
  fact, 
  I 
  should 
  be 
  inclined 
  to 
  include 
  under 
  one 
  

   species, 
  L. 
  productus, 
  Bosc, 
  from 
  Europe, 
  L. 
  viridis, 
  Baird, 
  from 
  Tasmania, 
  

   L, 
  awjasli, 
  Baird, 
  from 
  South 
  Australia, 
  and 
  perhaps 
  even 
  L. 
  (.jlacialis, 
  

   Kroyer, 
  from 
  North 
  America. 
  

  

  Order 
  II. 
  Cladocera. 
  

   Legs 
  four 
  to 
  six 
  pairs, 
  chiefly 
  branchial 
  ; 
  eye 
  single 
  and 
  very 
  large 
  ; 
  

   antennae 
  two 
  pairs, 
  inferior 
  large, 
  branched, 
  and 
  adapted 
  for 
  swimming. 
  

  

  Fam. 
  I. 
  Daphniadae. 
  

   Superior 
  antennae 
  small; 
  inferior 
  large, 
  two-branched; 
  legs 
  five 
  (or 
  six) 
  

   pairs, 
  all 
  enclosed 
  within 
  the 
  carapace. 
  

  

  Genus 
  I. 
  Daphnia, 
  Mi'dler. 
  

   Head 
  produced 
  downwards 
  into 
  a 
  more 
  or 
  less 
  prominent 
  beak. 
  Superior 
  

   antennas 
  exceedingly 
  small, 
  one-jointed, 
  and 
  situated 
  under 
  the 
  beak 
  ; 
  

   inferior 
  large 
  and 
  powerful. 
  

  

  1. 
  Daphnia 
  obtusaLa, 
  nov. 
  sp. 
  Fig. 
  E.2 
  a-e. 
  

  

  Carapace 
  (viewed 
  laterally) 
  oval, 
  broadest 
  below 
  the 
  middle, 
  obtusely 
  

   pointed 
  below, 
  infero-anterior 
  margin 
  oblique 
  ; 
  anterior 
  margin 
  rounded, 
  

   finely 
  ciliated. 
  When 
  viewed 
  dorsally, 
  the 
  valves 
  are 
  n 
  arrow- 
  obovate 
  in 
  

   shape, 
  tapering 
  downwards. 
  Head 
  small, 
  produced 
  into 
  a 
  very 
  obtuse 
  

   beak. 
  Inferior 
  antenna 
  comparatively 
  small 
  as 
  compared 
  with 
  European 
  

   species, 
  not 
  more 
  than 
  one-fourth 
  the 
  length 
  of 
  the 
  carapace. 
  Superior 
  

   antennae 
  very 
  minute, 
  thick 
  and 
  slightly 
  curved, 
  with 
  a 
  few 
  very 
  dehcate 
  

   cilia 
  at 
  the 
  extremity. 
  Eye 
  moderately 
  large. 
  Abdominal 
  segment 
  bearing 
  

   two 
  slender 
  filaments. 
  Caudal 
  claw^s 
  long, 
  slender 
  and 
  curved, 
  serrated 
  

   below. 
  Lower 
  edge 
  of 
  abdomen 
  with 
  numerous 
  curved 
  teeth. 
  

  

  The 
  whole 
  carapace 
  is 
  semi-transparent 
  and 
  closely 
  striated. 
  

  

  Length 
  ^^ 
  inch. 
  Occurs 
  in 
  great 
  abundance 
  in 
  still 
  water 
  in 
  neigh- 
  

   bourhood 
  of 
  Dunedin 
  from 
  October 
  to 
  May. 
  

  

  The 
  young 
  are 
  very 
  abundantly 
  produced, 
  over 
  thirty 
  sometimes 
  occur- 
  

   ring 
  within 
  the 
  valves 
  of 
  the 
  parent. 
  Before 
  leavuig 
  this 
  shelter 
  they 
  are 
  

   remarkably 
  well-developed 
  and 
  able 
  to 
  swim 
  about 
  freely. 
  At 
  this 
  early 
  

   stage 
  the 
  carapace 
  is 
  subquadrate 
  in 
  shape, 
  and 
  both 
  pairs 
  of 
  antennae 
  are 
  

   relatively 
  large, 
  the 
  inferior 
  being 
  nearly 
  as 
  long 
  as 
  the 
  animal. 
  

  

  