﻿abt. 
  3 
  STUDIES 
  ON 
  LARVAE 
  OF 
  CRABS 
  HYMAN 
  15 
  

  

  of 
  the 
  prezoeal 
  antennule 
  (fig. 
  164) 
  shows 
  two 
  broad 
  spines 
  of 
  un- 
  

   equal 
  lengths. 
  The 
  antenna 
  (fig. 
  165) 
  terminates 
  in 
  a 
  blunt 
  point. 
  

   It 
  bears 
  a 
  lateral 
  ramus 
  near 
  its 
  tip 
  that 
  is 
  prolonged 
  into 
  four 
  sub- 
  

   equal 
  hairy 
  digitations. 
  The 
  telson 
  (fig. 
  166) 
  carries 
  seven 
  spines 
  on 
  

   each 
  cornu. 
  The 
  middle 
  spine 
  is 
  short 
  and 
  smooth, 
  the 
  others 
  long 
  

   and 
  hairy. 
  

  

  first 
  zoea 
  (figs. 
  167 
  and 
  168) 
  

  

  The 
  zoea 
  of 
  Menippe 
  differs 
  strikingly 
  from 
  that 
  of 
  Panopeus 
  and 
  

   Xantho, 
  but 
  resembles 
  that 
  of 
  Eriphia 
  closely. 
  The 
  carapace 
  spines 
  

   are 
  all 
  robust. 
  The 
  antenna 
  is 
  scarcely 
  as 
  long 
  as 
  the 
  rostral 
  spine 
  

   and 
  its 
  exopodite 
  is 
  as 
  long 
  as 
  the 
  antennal 
  spine. 
  The 
  pigmentation 
  

   along 
  the 
  anterior 
  surface 
  of 
  the 
  dorsal 
  carapace 
  spine 
  is 
  helpful 
  in 
  

   identifying 
  this 
  zoea. 
  

  

  Cephalic 
  appendages. 
  — 
  The 
  antennule 
  (fig. 
  169) 
  is 
  simple 
  and 
  

   conical 
  but 
  it 
  is 
  longer 
  than 
  usual. 
  The 
  antenna 
  (fig. 
  170) 
  is 
  com- 
  

   paratively 
  small 
  for 
  a 
  Xanthid. 
  Its 
  spine 
  is 
  slender 
  and 
  hairy 
  along 
  

   its 
  distal 
  portion. 
  The 
  exopodite 
  is 
  quite 
  long 
  and, 
  with 
  its 
  terminal 
  

   hairs, 
  equals 
  or 
  exceeds 
  the 
  spine 
  in 
  length. 
  The 
  remaining 
  cephalic 
  

   appendages 
  (figs. 
  171 
  and 
  172 
  and 
  173) 
  have 
  the 
  typical 
  brachyuran 
  

   form. 
  

  

  Thorax 
  and 
  abdomen. 
  — 
  The 
  thoracic 
  appendages 
  are 
  typical 
  

   (figs. 
  171 
  and 
  175). 
  The 
  fourth 
  and 
  fifth 
  abdominal 
  segments 
  are 
  

   characterized 
  by 
  short 
  lateral 
  spines 
  that 
  spring 
  from 
  their 
  posterior 
  

   borders. 
  The 
  telson 
  (fig. 
  176) 
  has 
  the 
  three 
  pairs 
  of 
  median 
  spines. 
  

   In 
  addition 
  each 
  cornu 
  has 
  a 
  minute 
  lateral 
  spine 
  and 
  a 
  minute 
  

   dorsal 
  spine. 
  

  

  Genus 
  TRAPEZIA 
  

  

  Plate 
  12, 
  fig. 
  162 
  

  

  Spence 
  Bate 
  has 
  described 
  the 
  first 
  zoea 
  of 
  Trapezia 
  very 
  briefly 
  

   and 
  given 
  one 
  figure. 
  The 
  description 
  is 
  confined 
  to 
  the 
  enumeration 
  

   of 
  the 
  appendages 
  present 
  but 
  other 
  details 
  may 
  be 
  learned 
  from 
  the 
  

   figure. 
  

  

  The 
  dorsal 
  spine 
  of 
  the 
  carapace 
  is 
  slender 
  and 
  is 
  curved 
  posteri- 
  

   orly. 
  The 
  rostral 
  spine 
  is 
  short 
  and 
  covered 
  with 
  spines 
  near 
  its 
  tip. 
  

   The 
  antenna 
  is 
  nearly 
  as 
  long 
  as 
  the 
  rostral 
  spine. 
  The 
  antennal 
  

   spine 
  is 
  hairy 
  near 
  its 
  tip. 
  Its 
  exopodite 
  is 
  nearly 
  as 
  long 
  as 
  its 
  

   spine. 
  The 
  posterior 
  borders 
  of 
  the 
  third, 
  fourth, 
  and 
  fifth 
  abdomi- 
  

   nal 
  segments 
  are 
  produced 
  laterally 
  into 
  long, 
  spinous 
  processes. 
  

  

  Genus 
  PILUMNUS 
  

  

  Plate 
  14 
  

  

  Cano 
  studied 
  Pilumnus 
  hirtellus, 
  P. 
  villosus, 
  and 
  P. 
  spinifer 
  but 
  

   he 
  did 
  not 
  distinguish 
  between 
  the 
  species 
  in 
  his 
  descriptions. 
  Gour- 
  

   ret 
  states 
  that 
  the 
  larvae 
  of 
  P. 
  spinifer 
  hatch 
  at 
  night 
  but 
  he 
  does 
  not 
  

  

  