﻿232 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  LERNANTHROPUS 
  OBSCURUS, 
  new 
  species. 
  

   Plate 
  37. 
  

  

  Host 
  and 
  record 
  of 
  specimens. 
  — 
  Both 
  sexes 
  of 
  this 
  species 
  were 
  

   taken 
  from 
  the 
  gills 
  of 
  the 
  yellow 
  tail, 
  Ocyurus 
  cTirysurus, 
  July 
  23, 
  

   1910. 
  

  

  Type-specimen. 
  — 
  A 
  female, 
  Cat. 
  No. 
  43600, 
  U.S.N.M. 
  Paratypcs, 
  

   Cat. 
  No. 
  42332, 
  U.S.N.M. 
  

  

  Female. 
  — 
  General 
  body 
  form 
  short 
  and 
  fairly 
  plump; 
  cephalo- 
  

   thorax 
  elUptical, 
  a 
  little 
  longer 
  than 
  wide; 
  antennal 
  area 
  well 
  de- 
  

   fined, 
  second 
  antennae 
  not 
  visible 
  in 
  dorsal 
  view; 
  second 
  and 
  third 
  

   thorax 
  segments 
  about 
  the 
  same 
  length 
  and 
  width 
  as 
  the 
  cephalo- 
  

   thorax, 
  with 
  a 
  shallow 
  lateral 
  sinus 
  between 
  them; 
  siniis 
  between 
  

   the 
  third 
  and 
  fourth 
  segments 
  narrow 
  and 
  deep; 
  dorsal 
  plate 
  of 
  

   fourth 
  segment 
  as 
  long 
  as 
  the 
  cephalothorax 
  and 
  half 
  as 
  wide 
  again, 
  

   \vith 
  a 
  deep 
  sinus 
  in 
  the 
  center 
  of 
  the 
  posterior 
  margm; 
  fifth 
  and 
  

   genital 
  segments 
  and 
  abdomen 
  diminishing 
  regularly 
  in 
  length 
  and 
  

   width; 
  anal 
  laminae 
  broad 
  and 
  foliaceous 
  and 
  as 
  long 
  as 
  the 
  tliree 
  

   preceding 
  segments 
  combined. 
  

  

  First 
  antennae 
  of 
  the 
  usual 
  pattern 
  and 
  rather 
  plump, 
  ver}^ 
  indis- 
  

   tinctly 
  segmented 
  toward 
  the 
  base. 
  Second 
  antennae 
  with 
  swollen 
  

   basal 
  joints, 
  destitute 
  of 
  any 
  tooth 
  on 
  the 
  inner 
  margin, 
  and 
  a 
  short, 
  

   rather 
  slender, 
  and 
  strongly 
  curved 
  terminal 
  claw. 
  First 
  maxillae 
  

   with 
  a 
  long 
  terminal 
  joint, 
  tipped 
  with 
  two 
  short 
  and 
  equal 
  spines. 
  

   Basal 
  joints 
  of 
  second 
  maxillae 
  and 
  maxilUpeds 
  much 
  swollen; 
  ter- 
  

   minal 
  claws 
  slender, 
  but 
  nearly 
  as 
  long 
  as 
  the 
  basal 
  joints. 
  Rami 
  of 
  

   first 
  two 
  pairs 
  of 
  legs 
  of 
  the 
  usual 
  pattern, 
  but 
  stouter 
  than 
  m 
  most 
  

   species. 
  Thii'd 
  legs 
  uniramose, 
  longer 
  than 
  the 
  second 
  and 
  third 
  

   segments 
  together, 
  and 
  somewhat 
  widened 
  and 
  flattened 
  at 
  the 
  base 
  

   so 
  as 
  to 
  be 
  semifohaceous. 
  Fourth 
  legs 
  biramose, 
  rami 
  elongate- 
  

   conical, 
  exopods 
  shghtly 
  longer 
  than 
  the 
  endopods, 
  and 
  both 
  project- 
  

   ing 
  for 
  nearly 
  their 
  entire 
  length 
  behind 
  the 
  dorsal 
  plate 
  of 
  the 
  fourth 
  

   segment. 
  Fifth 
  legs 
  narrow 
  foHaceous, 
  well 
  flattened, 
  and 
  just 
  reach- 
  

   ing 
  the 
  posterior 
  margin 
  of 
  this 
  same 
  dorsal 
  plate. 
  

  

  Total 
  length, 
  6.5 
  mm., 
  with 
  the 
  fourth 
  legs; 
  4.35 
  mm. 
  without 
  

   them. 
  Cephalothorax, 
  1.5 
  mm. 
  long, 
  1.35 
  mm. 
  wide. 
  Second 
  and 
  

   third 
  segments, 
  1.5 
  mm. 
  long, 
  1.25 
  mm. 
  wide. 
  Dorsal 
  plate 
  of 
  fourth 
  

   segment, 
  1.5 
  mm. 
  long, 
  1.9 
  mm. 
  wide. 
  

  

  Male. 
  — 
  General 
  body 
  form 
  spindle-shaped; 
  cephalothorax 
  ovate, 
  

   nearly 
  half 
  the 
  entire 
  length 
  of 
  the 
  body 
  proper; 
  antennal 
  area 
  con- 
  

   siderably 
  narrowed 
  and 
  separated 
  by 
  a 
  well-defined 
  groove 
  ; 
  posterior 
  

   body 
  without 
  transverse 
  grooves, 
  but 
  with 
  the 
  segmentation 
  indi- 
  

   cated 
  by 
  marginal 
  sinuses, 
  widest 
  through 
  the 
  tliird 
  segment 
  and 
  

   thence 
  tapering 
  rapidly 
  backwards; 
  anal 
  laminae 
  linear, 
  divergent, 
  

   each 
  tipped 
  with 
  two 
  minute 
  spines. 
  

  

  Appendages 
  like 
  those 
  of 
  the 
  female, 
  with 
  a 
  few 
  exceptions. 
  

  

  