﻿206 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol. 
  44. 
  

  

  TiENIACANTHUS 
  FLAGELLANS. 
  new 
  species. 
  

   Plate 
  25, 
  figs. 
  54-61. 
  

  

  Host 
  and 
  record 
  of 
  specimens. 
  — 
  Six 
  females 
  with 
  egg-strings 
  were 
  

   obtained 
  from 
  the 
  gill 
  cavity 
  of 
  the 
  hammer-head 
  shark, 
  Sphyrna 
  

   zygsena, 
  at 
  different 
  times, 
  two 
  being 
  the 
  largest 
  number 
  from 
  any 
  

   single 
  shark. 
  

  

  Type-specimen. 
  — 
  Cat. 
  No. 
  43517, 
  U.S.N.M. 
  Paratypes, 
  Cat. 
  No. 
  

   42261, 
  U.S.N.M. 
  

  

  Female. 
  — 
  General 
  body 
  form 
  elongate 
  and 
  narrow, 
  especially 
  

   posteriorly; 
  cephalo 
  thorax 
  turned 
  over 
  ventrally 
  so 
  as 
  to 
  stand 
  at 
  

   right 
  angles 
  to 
  the 
  rest 
  of 
  the 
  body 
  axis; 
  ventral 
  surface 
  of 
  this 
  

   cephalothorax 
  prolonged 
  into 
  a 
  sucking 
  disk 
  which 
  protrudes 
  beyond 
  

   all 
  the 
  mouth 
  parts 
  and 
  is 
  surrounded 
  by 
  a 
  membranous 
  edge, 
  

   similar 
  to 
  that 
  on 
  the 
  sucking 
  disks 
  of 
  Argulus. 
  

  

  The 
  first 
  antennae 
  lie 
  along 
  the 
  anterior 
  portion 
  of 
  this 
  edge 
  while 
  

   the 
  first 
  legs 
  curve 
  around 
  the 
  posterior 
  portion 
  and 
  both 
  no 
  doubt 
  

   aid 
  in 
  attaching 
  and 
  releasing 
  the 
  disk. 
  

  

  Cephalothorax 
  triangular 
  in 
  dorsal 
  outline, 
  ^vith 
  rounded 
  corners, 
  

   considerably 
  wider 
  than 
  the 
  second 
  (first 
  free) 
  segment, 
  and 
  entirely 
  

   covering 
  the 
  antennae, 
  mouth 
  parts, 
  and 
  first 
  legs. 
  Second 
  to 
  fifth 
  

   segments 
  about 
  the 
  same 
  length 
  but 
  diminisliing 
  regularly 
  in 
  width, 
  

   and 
  showing 
  successively 
  larger 
  portions 
  of 
  the 
  swimming 
  legs, 
  until 
  

   the 
  whole 
  of 
  the 
  fifth 
  pair 
  appears 
  in 
  dorsal 
  view. 
  Genital 
  segment 
  

   the 
  same 
  width 
  as 
  the 
  fifth 
  segment 
  and 
  nearly 
  twice 
  as 
  long, 
  tapering 
  

   posteriorly. 
  

  

  Abdomen 
  composed 
  of 
  four 
  segments, 
  diminishing 
  regularly 
  in 
  

   size, 
  except 
  that 
  the 
  third 
  one 
  is 
  a 
  little 
  shorter 
  than 
  the 
  last. 
  Anal 
  

   laminae 
  narrow, 
  two-thirds 
  the 
  length 
  of 
  the 
  last 
  segment, 
  each 
  tipped 
  

   with 
  two 
  setae 
  of 
  which 
  the 
  inner 
  one 
  is 
  half 
  as 
  long 
  again 
  as 
  the 
  outer. 
  

   Egg-cases 
  attached 
  to 
  the 
  anterior 
  end 
  of 
  the 
  genital 
  segment 
  on 
  the 
  

   dorsal 
  surface, 
  their 
  bases 
  covered 
  by 
  the 
  rudimentary 
  sixth 
  legs. 
  

   Each 
  case 
  is 
  about 
  the 
  same 
  diameter 
  as 
  the 
  abdomen 
  and 
  reaches 
  

   to 
  the 
  center 
  or 
  even 
  the 
  tips 
  of 
  the 
  longest 
  anal 
  setae; 
  eggs 
  numerous, 
  

   arranged 
  in 
  six 
  or 
  seven 
  longitudinal 
  rows, 
  18 
  or 
  20 
  eggs 
  in 
  a 
  row. 
  

  

  Basal 
  portion 
  of 
  first 
  antennae 
  not 
  much 
  enlarged, 
  indistinctly 
  

   divided 
  into 
  three 
  parts, 
  with 
  a 
  fringe 
  of 
  large 
  flattened 
  setae 
  along 
  

   the 
  anterior 
  margin; 
  terminal 
  portion 
  made 
  up 
  of 
  three 
  distinct 
  

   segments, 
  heavily 
  armed 
  with 
  setae. 
  

  

  Second 
  antennae 
  three-jointed 
  and 
  tipped 
  with 
  three 
  long 
  curved 
  

   claws, 
  the 
  ventral 
  surface 
  of 
  the 
  terminal 
  joint 
  being 
  corrugated. 
  

  

  Mouth 
  parts 
  close 
  to 
  the 
  second 
  antennae; 
  upper 
  lip 
  two 
  and 
  a 
  

   half 
  times 
  as 
  wide 
  as 
  long, 
  the 
  two 
  anterior 
  margins 
  shghtly 
  concave, 
  

   the 
  posterior 
  one 
  convex. 
  Mandibles 
  three-jointed, 
  the 
  two 
  distal 
  

   joints 
  bent 
  backward 
  at 
  an 
  angle 
  with 
  the 
  basal 
  joint; 
  the 
  terminal 
  

   joint 
  a 
  simple 
  straight 
  spine. 
  First 
  maxilla 
  armed 
  with 
  three 
  setae 
  

  

  