﻿G". 
  M. 
  Thomson. 
  — 
  On 
  the 
  New 
  Zealand 
  Entomostraca. 
  259 
  

  

  growths 
  as 
  to 
  be 
  briglit 
  green. 
  Eye 
  usually 
  red, 
  sometimes 
  brown 
  or 
  nearly 
  

   black. 
  Length, 
  exclusive 
  of 
  caudal 
  setse, 
  about 
  ^V 
  inch. 
  Occurs 
  all 
  the 
  year 
  

   round. 
  

  

  This 
  is 
  a 
  very 
  common 
  species, 
  occurring 
  in 
  every 
  little 
  pool, 
  and 
  even 
  

   in 
  brackish 
  water 
  affected 
  by 
  the 
  tide. 
  It 
  is 
  extremely 
  lively 
  in 
  its 
  move- 
  

   ments, 
  and 
  avoids 
  danger 
  with 
  much 
  more 
  alacrity 
  than 
  the 
  majority 
  of 
  the 
  

   Entomostraca, 
  darting 
  away 
  on 
  the 
  approach 
  of 
  a 
  dipj)ing-tube 
  or 
  other 
  

   large 
  object. 
  

  

  From 
  the 
  figure 
  in 
  Dana's 
  Atlas 
  of 
  Crustacea 
  (U.S. 
  Explor. 
  Exped.), 
  

   this 
  species 
  appears 
  to 
  be 
  very 
  near 
  C, 
  vitiensis, 
  Dana. 
  I 
  have 
  not 
  seen 
  

   any 
  description 
  however. 
  

  

  Genus 
  II. 
  Arpacticus, 
  Baird. 
  

   Foot-jaws 
  forming 
  strong 
  cheliform 
  hands 
  ; 
  inferior 
  antenna 
  simple. 
  

   Ovary 
  single. 
  

  

  1. 
  Arpacticus 
  bairdii, 
  nov. 
  sp. 
  Fig. 
  D.3, 
  and 
  Fig. 
  E.l. 
  

  

  Body 
  indistinctly 
  ten-jointed. 
  Cephalothorax 
  produced 
  downwards 
  into 
  

   a 
  beak. 
  Eye 
  usually 
  crimson. 
  Superior 
  antennae 
  stout, 
  composed 
  of 
  ten 
  

   articulations, 
  the 
  last 
  seven 
  subequal 
  in 
  length, 
  but 
  greatly 
  narrowing, 
  

   bearing 
  numerous 
  setse, 
  which 
  are 
  particularly 
  abundant 
  on 
  the 
  third, 
  

   fourth, 
  fifth, 
  and 
  sixth 
  joints 
  ; 
  one 
  very 
  long 
  and 
  stout 
  seta 
  from 
  the 
  fourth 
  

   joint 
  ; 
  last 
  joint 
  terminated 
  by 
  about 
  five 
  set® 
  of 
  different 
  lengths. 
  Lower 
  

   antennae 
  two-jointed; 
  basal 
  joint 
  with 
  a 
  two-jointed, 
  setiferous 
  appendage 
  ; 
  

   ultimate 
  joint 
  with 
  about 
  nine 
  long 
  setae. 
  Mandibles 
  strong. 
  Posterior 
  

   foot-jaws 
  three-jointed 
  ; 
  second 
  joint 
  ovate, 
  with 
  a 
  broad, 
  flat 
  margin 
  

   furnished 
  with 
  two 
  rows 
  of 
  small 
  teeth 
  ; 
  third 
  joint 
  in 
  form 
  of 
  a 
  strong 
  

   hook. 
  First 
  pair 
  of 
  feet 
  with 
  both 
  branches 
  three-jointed, 
  external 
  branch 
  

   having 
  the 
  first 
  joint 
  short, 
  bearing 
  one 
  strong 
  seta, 
  second 
  much 
  longer, 
  

   with 
  seta 
  on 
  each 
  side, 
  last 
  joint 
  very 
  short 
  and 
  terminated 
  by 
  about 
  five 
  

   somewhat 
  curved 
  setas, 
  the 
  largest 
  of 
  them 
  being 
  somewhat 
  serrated 
  on 
  its 
  

   inner 
  margin 
  ; 
  internal 
  branch 
  with 
  first 
  joint 
  very 
  long, 
  second 
  short, 
  and 
  

   third 
  in 
  the 
  form 
  of 
  a 
  long, 
  slender 
  hook. 
  Second, 
  thu-d, 
  and 
  fourth 
  pairs 
  of 
  

   legs 
  somewhat 
  similar 
  in 
  shape, 
  with 
  the 
  external 
  branch 
  in 
  each 
  longer 
  

   than 
  the 
  internal, 
  and 
  all 
  furnished 
  with 
  numerous 
  setae, 
  the 
  longer 
  of 
  which 
  

   are 
  beautifully 
  plumose. 
  Fifth 
  pair 
  with 
  both 
  branches 
  formed 
  of 
  a 
  single, 
  

   nearly 
  circular 
  joint, 
  bearing 
  five 
  setae 
  at 
  the 
  extremity. 
  All 
  the 
  legs 
  more 
  

   or 
  less 
  serrated 
  on 
  the 
  margins. 
  Abdomen 
  cylindrical, 
  tapering 
  posteriorly 
  ; 
  

   posterior 
  margins 
  of 
  segments 
  minutely 
  serrate. 
  Bilobed 
  extremity 
  bearing 
  

   on 
  each 
  side 
  one 
  seta, 
  which 
  exceeds 
  the 
  abdomen 
  in 
  length, 
  one 
  about 
  a 
  

   third 
  as 
  long, 
  and 
  four 
  short 
  ones. 
  Ovisac 
  large, 
  usually 
  exceeding 
  the 
  

   abdomen 
  in 
  diameter, 
  and 
  reaching 
  to 
  about 
  the 
  penultimate 
  segment. 
  

  

  Length 
  -^ 
  of 
  an 
  inch. 
  

  

  Occurs 
  abundantly 
  among 
  shore-algae 
  in 
  Otago 
  Harbour, 
  

  

  