﻿NO. 
  1950. 
  CRUSTACEAN 
  PARASITES 
  OF 
  FISH 
  AND 
  CRABS— 
  WILSON. 
  203 
  

  

  Total 
  length, 
  1.3 
  mm. 
  Cephalo 
  thorax, 
  0.35 
  mm. 
  long, 
  0.4 
  mm. 
  

   wide. 
  Free 
  thorax, 
  0.37 
  mm, 
  long. 
  iVnal 
  setse, 
  0.5 
  mm. 
  long. 
  

  

  Color 
  as 
  in 
  the 
  female, 
  the 
  testes, 
  sperm 
  ducts, 
  and 
  sperm 
  recep- 
  

   tacles 
  showing 
  snow-white 
  through 
  the 
  body 
  walls. 
  

  

  (tzcDJ^S'jkoc, 
  Tide 
  and 
  XeuKoc, 
  all 
  wliite.) 
  

  

  This 
  species 
  is 
  a 
  very 
  common 
  one 
  on 
  the 
  gills 
  of 
  the 
  scorpion 
  fish, 
  

   nearly 
  every 
  fish 
  examined 
  being 
  infested. 
  The 
  females 
  were 
  found 
  

   fastened 
  to 
  the 
  skin 
  on 
  the 
  inside 
  of 
  the 
  gill 
  arches 
  and 
  occasionally 
  

   on 
  the 
  filaments. 
  The 
  males 
  were 
  always 
  fastened 
  to 
  the 
  filaments. 
  

  

  The 
  hold 
  of 
  both 
  sexes 
  is 
  rather 
  a 
  loose 
  one 
  and 
  is 
  easily 
  broken, 
  

   and 
  they 
  seem 
  to 
  move 
  about 
  freely 
  over 
  the 
  gills. 
  When 
  removed 
  

   to 
  an 
  aquarium 
  they 
  fasten 
  readily 
  to 
  the 
  glass 
  and 
  hold 
  on 
  as 
  well 
  

   as 
  to 
  the 
  gills. 
  They 
  also 
  swim 
  about 
  easily 
  and 
  quite 
  rapidly 
  and 
  

   may 
  be 
  kept 
  alive 
  for 
  several 
  days. 
  They 
  can 
  not, 
  however, 
  crawl 
  

   up 
  out 
  of 
  the 
  water 
  like 
  the 
  Caligidae, 
  but 
  always 
  remain 
  beneath 
  

   the 
  surface. 
  

  

  This 
  is 
  the 
  first 
  male 
  to 
  be 
  described 
  for 
  the 
  new 
  genus 
  Artacolax, 
  

   and 
  it 
  is 
  interesting 
  to 
  note 
  some 
  differences 
  between 
  it 
  and 
  a 
  typical 
  

   Bomoloclius 
  male. 
  These 
  consist 
  chiefly 
  in 
  the 
  anterior 
  marginal 
  

   furca, 
  the 
  huge 
  claws 
  at 
  the 
  tips 
  of 
  the 
  second 
  antennae, 
  and 
  in 
  the 
  

   peculiar 
  shape 
  of 
  the 
  second 
  joint 
  and 
  terminal 
  claws 
  of 
  the 
  maxil- 
  

   lipeds. 
  

  

  PSEUDOEUCANTHUS 
  UNISERIATUS, 
  new 
  species. 
  

   Plate 
  24. 
  

  

  Host 
  and 
  record 
  of 
  specimens. 
  — 
  ^A 
  single 
  lot 
  consisting 
  of 
  three 
  

   females 
  with 
  egg-strings 
  was 
  obtained 
  from 
  the 
  mouth 
  of 
  the 
  yellow 
  

   jack, 
  Caranx 
  crysos, 
  August 
  1, 
  1910. 
  

  

  Type-specimen. 
  — 
  Cat. 
  No. 
  43510, 
  U.S.N.M. 
  Paratypes, 
  Cat. 
  No. 
  

   42256, 
  U.S.N.M. 
  

  

  Female. 
  — 
  General 
  body 
  form 
  long 
  and 
  narrow; 
  cephalothorax 
  

   transversely 
  elliptical, 
  one-sixth 
  wider 
  than 
  long; 
  frontal 
  margin 
  pro- 
  

   jecting 
  as 
  a 
  rounded 
  knob 
  between 
  the 
  bases 
  of 
  the 
  antenna. 
  

  

  Carapace 
  not 
  reaching 
  the 
  lateral 
  margins, 
  its 
  posterior 
  corners 
  

   prominent 
  and 
  rounded, 
  overlapping 
  the 
  second 
  thorax 
  segment; 
  no 
  

   dorsal 
  grooves; 
  eye 
  small 
  and 
  situated 
  very 
  far 
  forward, 
  almost 
  

   between 
  the 
  bases 
  of 
  the 
  antennae. 
  Second 
  segment 
  half 
  the 
  width 
  

   of 
  the 
  cephalothorax 
  and 
  very 
  short; 
  third 
  segment 
  a 
  little 
  wider 
  

   and 
  considerably 
  longer, 
  with 
  projecting 
  posterior 
  corners; 
  fourth 
  

   segment 
  the 
  same 
  width 
  as 
  the 
  second 
  and 
  as 
  long 
  as 
  the 
  third, 
  

   strongly 
  contracted 
  posteriorly; 
  fifth 
  segment 
  a 
  little 
  narrower 
  than 
  

   the 
  fourth 
  and 
  about 
  half 
  as 
  long, 
  its 
  lateral 
  margins 
  projecting 
  

   angularly 
  over 
  the 
  bases 
  of 
  the 
  fifth 
  legs; 
  sixth 
  or 
  genital 
  segment 
  

   the 
  same 
  width 
  as 
  the 
  fifth 
  and 
  two-thirds 
  as 
  long, 
  its 
  lateral 
  margins 
  

   strongly 
  convex. 
  

  

  