﻿250 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  Genital 
  segment 
  fused 
  with 
  the 
  others 
  and 
  produced 
  posteriorly 
  into 
  

   a 
  short 
  and 
  blunt 
  lobe 
  on 
  either 
  side. 
  

  

  Abdomen 
  one-jointed, 
  one-third 
  the 
  width 
  of 
  the 
  fused 
  thorax^ 
  

   and 
  enlarged 
  a 
  little 
  posteriorly; 
  anal 
  laminae 
  large, 
  three 
  times 
  as 
  

   long 
  as 
  wide, 
  one-half 
  longer 
  than 
  the 
  abdomen, 
  each 
  tipped 
  with 
  

   two 
  large 
  and 
  stout 
  spines, 
  the 
  inner 
  of 
  which 
  is 
  as 
  long 
  as 
  the 
  lamina 
  

   itself. 
  Appendages 
  like 
  those 
  of 
  the 
  female, 
  but 
  longer 
  and 
  more 
  

   slender. 
  First 
  antennae 
  carried 
  at 
  right 
  angles 
  to 
  the 
  body 
  axis, 
  and 
  

   projecting 
  more 
  than 
  half 
  their 
  length 
  beyond 
  the 
  lateral 
  margins 
  

   of 
  the 
  carapace. 
  Maxillipeds 
  also 
  projecting 
  obliquely 
  backward, 
  

   with 
  their 
  entire 
  length 
  visible 
  in 
  dorsal 
  view. 
  First 
  two 
  pairs 
  of 
  

   swimming 
  legs 
  with 
  two-jointed 
  exopods 
  and 
  one-jointed 
  endopods; 
  

   there 
  is 
  also 
  a 
  rudimentary 
  third 
  pair 
  of 
  legs 
  behind 
  the 
  second 
  pair 
  

   on 
  the 
  lateral 
  margins; 
  each 
  consists 
  of 
  a 
  single 
  short 
  joint 
  tipped 
  

   with 
  two 
  spines. 
  

  

  Total 
  length, 
  1 
  mm. 
  Carapace, 
  0.3 
  mm. 
  long 
  and 
  wide. 
  Fused 
  

   thorax, 
  0.6 
  mm. 
  long, 
  0.22 
  mm. 
  wide. 
  

  

  Color 
  like 
  that 
  of 
  the 
  female 
  except 
  that 
  the 
  brown 
  oviducts 
  are 
  

   replaced 
  by 
  yellow 
  sperm 
  receptacles. 
  

  

  Nauplius. 
  — 
  Body 
  elliptical, 
  one-half 
  longer 
  than 
  wide, 
  with 
  a 
  

   regular 
  curve; 
  a 
  narrow 
  papilla-like 
  protuberance 
  at 
  the 
  center 
  of 
  

   the 
  anterior 
  margin, 
  and 
  a 
  much 
  wider 
  one 
  between 
  the 
  balancers, 
  

   posteriorly. 
  There 
  are 
  the 
  usual 
  nauplius 
  appendages, 
  the 
  exopods 
  

   of 
  the 
  second 
  antennae 
  and 
  mandibles 
  carrying 
  only 
  four 
  rowing 
  

   setae. 
  Balancers 
  slender 
  and 
  cylindrical, 
  carried 
  straight 
  back- 
  

   ward 
  parallel 
  with 
  the 
  body 
  axis, 
  each 
  of 
  them 
  slightly 
  convex 
  inward. 
  

   Body 
  with 
  three 
  large 
  masses 
  of 
  brown 
  pigment, 
  one 
  triangular 
  in 
  

   shape, 
  in 
  the 
  center 
  of 
  the 
  anterior 
  portion, 
  the 
  other 
  two 
  along 
  each 
  

   lateral 
  margin, 
  meeting 
  posteriorly. 
  Between 
  and 
  in 
  front 
  of 
  these 
  

   pigment 
  masses 
  the 
  body 
  is 
  translucent 
  and 
  shows 
  the 
  usual 
  diagonal 
  

   muscles 
  (see 
  fig. 
  216). 
  

  

  Total 
  length, 
  0.2 
  mm.; 
  width, 
  0.11 
  mm. 
  

  

  (iridescens, 
  iridescent, 
  alluding 
  particularly 
  to 
  the 
  fully 
  developed 
  

   egg-strings.) 
  

  

  The 
  burial 
  of 
  the 
  large 
  second 
  antennae 
  of 
  this 
  species 
  in 
  the 
  tissue 
  

   of 
  the 
  gill 
  filament 
  of 
  its 
  host 
  produces 
  a 
  sort 
  of 
  tumor 
  or 
  swelling, 
  

   similar 
  to 
  that 
  produced 
  on 
  the 
  fins 
  by 
  the 
  maxillipeds 
  of 
  Tucca 
  

   impressus. 
  But 
  these 
  parasites 
  are 
  not 
  thereby 
  anchored 
  to 
  one 
  

   spot 
  as 
  is 
  the 
  case 
  with 
  Tucca; 
  they 
  are 
  able 
  to 
  loosen 
  their 
  hold 
  and 
  

   move 
  up 
  and 
  down 
  the 
  filaments 
  by 
  a 
  walking 
  motion 
  of 
  the 
  second 
  

   antennae. 
  Some 
  of 
  them 
  free 
  themselves 
  entirely 
  and 
  wriggle 
  off 
  

   the 
  gills 
  on 
  to 
  the 
  bottom 
  of 
  the 
  aquarium, 
  when 
  the 
  gills 
  are 
  removed 
  

   from 
  the 
  fish 
  and 
  put 
  in 
  water. 
  The 
  females 
  live 
  a 
  long 
  time, 
  lying 
  

   on 
  their 
  backs 
  and 
  wriggling 
  about 
  violently, 
  but 
  they 
  are 
  unable 
  to 
  

  

  