﻿4 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  67 
  

  

  cuticle. 
  The 
  first 
  and 
  second 
  maxillipeds 
  (figs. 
  23 
  and 
  27) 
  are 
  well 
  

   developed. 
  The 
  endopodite 
  of 
  the 
  first 
  shows 
  five 
  segments 
  and 
  

   that 
  of 
  the 
  second 
  three. 
  All 
  of 
  the 
  hairs 
  are 
  invaginated. 
  The 
  

   third 
  maxillipeds 
  and 
  the 
  chelipeds 
  appear 
  as 
  buds. 
  

  

  Abdomen, 
  — 
  The 
  five 
  segments 
  and 
  telson 
  are 
  clearly 
  defined. 
  The 
  

   segments 
  are 
  closely 
  invested 
  by 
  the 
  embryonic 
  cuticle, 
  which 
  is, 
  

   however, 
  not 
  segmented. 
  The 
  cuticle 
  covering 
  the 
  telson 
  (fig. 
  31) 
  

   is 
  bifurcated. 
  Each 
  ramus 
  bears 
  seven 
  large 
  spines. 
  Of 
  these, 
  the 
  

   median 
  three 
  are 
  sparsely 
  hairy, 
  elongated, 
  and 
  tapering. 
  The 
  

   middle 
  spine 
  is 
  short, 
  blunt, 
  and 
  smooth. 
  Two 
  of 
  the 
  lateral 
  group 
  

   are 
  sparsely 
  hairy 
  and 
  tapering, 
  while 
  the 
  most 
  lateral 
  spine 
  again 
  

   is 
  short 
  and 
  smooth. 
  The 
  zoeal 
  telson 
  nearly 
  fills 
  the 
  cuticle. 
  The 
  

   tips 
  of 
  its 
  cornua 
  are 
  invaginated. 
  They 
  extend 
  out 
  into 
  the 
  middle 
  

   blunt 
  spine. 
  The 
  hairs 
  of 
  the 
  telson 
  are 
  only 
  slightly 
  invaginated. 
  

   They 
  extend 
  out 
  into 
  the 
  remaining 
  spines. 
  

  

  first 
  zoea 
  (figs.. 
  35 
  and 
  36) 
  

  

  After 
  a 
  few 
  hours 
  the 
  embryonic 
  cuticle 
  is 
  shed 
  and 
  the 
  striking 
  

   first 
  zoea 
  emerges. 
  The 
  elongated 
  spines 
  and 
  antennae 
  give 
  the 
  

   larva 
  an 
  awkward 
  appearance, 
  but 
  it 
  is 
  quite 
  active 
  and 
  swims 
  well. 
  

  

  Cephalothorax. 
  — 
  Among 
  the 
  most 
  striking 
  features 
  of 
  the 
  zoea 
  

   are 
  the 
  dorsal 
  and 
  rostral 
  spines. 
  The 
  dorsal 
  spine 
  rises 
  from 
  a 
  

   slightly 
  swollen 
  base 
  and 
  sweeps 
  upward 
  and 
  backward 
  as 
  a 
  long, 
  

   tapering 
  process. 
  It 
  is 
  almost 
  straight. 
  The 
  rostral 
  spine 
  is 
  longer 
  

   and 
  more 
  slender 
  than 
  the 
  dorsal. 
  It 
  extends 
  ventrally 
  and 
  slightly 
  

   anteriorly. 
  The 
  lateral 
  spines 
  are 
  short 
  and 
  slender. 
  

  

  Cephalic 
  appendages. 
  — 
  The 
  antennae 
  (fig. 
  59) 
  are 
  noteworthy. 
  

   The 
  spine 
  is 
  tremendously 
  elongated, 
  extending 
  even 
  beyond 
  the 
  

   rostral 
  spine 
  of 
  the 
  carapace. 
  It 
  is 
  smooth 
  to 
  its 
  tip. 
  The 
  minute 
  

   exopodite 
  is 
  scarcely 
  discernible 
  where 
  it 
  is 
  attached 
  to 
  the 
  spine 
  

   near 
  its 
  base. 
  The 
  other 
  cephalic 
  appendages 
  are 
  typical. 
  

  

  Thoracic 
  appendages. 
  — 
  The 
  first 
  and 
  second 
  maxillipeds 
  (figs. 
  63 
  

   and 
  67) 
  show 
  the 
  usual 
  four 
  swimming 
  hairs 
  on 
  the 
  exopodites. 
  

   The 
  proximal 
  segments 
  of 
  the 
  endopodites 
  are 
  developed 
  as 
  masti- 
  

   cating 
  organs 
  while 
  the 
  distal 
  segments 
  bear 
  sensory 
  hairs. 
  The 
  

   remaining 
  thoracic 
  appendages 
  are 
  discernible 
  as 
  minute 
  buds. 
  

  

  Abdomen. 
  — 
  It 
  is 
  characteristic 
  that 
  the 
  posterior 
  lateral 
  border 
  of 
  

   each 
  segment 
  is 
  produced 
  posteriorly 
  as 
  a 
  spinous 
  process. 
  These 
  

   are 
  not 
  very 
  pronounced 
  in 
  this 
  early 
  stage. 
  The 
  corniua 
  of 
  the 
  

   telson 
  (fig. 
  72) 
  are 
  slender 
  and 
  greatly 
  elongated. 
  In 
  addition 
  to 
  

   the 
  usual 
  three 
  hairs 
  on 
  the 
  median 
  margin 
  of 
  each 
  cornu, 
  there 
  are 
  

   three 
  minute 
  spines 
  placed 
  laterally 
  and 
  dorsally. 
  

  

  