﻿DEVELOPMENT 
  OF 
  CALOPTENUS 
  SPRETUS. 
  279 
  

  

  to 
  the 
  procephalic 
  lobe, 
  which 
  is 
  plainly 
  seen 
  to 
  form 
  the 
  pleura 
  of 
  the 
  

   first 
  or 
  antennal 
  segment 
  (arthromere), 
  the 
  antenna 
  being 
  developed 
  

   from 
  the 
  sternal 
  side, 
  and 
  the 
  eye 
  developed 
  on 
  the 
  tergal 
  side. 
  This 
  

   preparation 
  shows 
  clearly 
  (1) 
  that 
  the 
  procephalic 
  lobes 
  are 
  the 
  pleural 
  

   portion 
  of 
  the 
  first 
  cephalic 
  or 
  antennal 
  segment; 
  (2) 
  that 
  the 
  antenna 
  

   is 
  an 
  appendage 
  or 
  outgrowth 
  of 
  the 
  procephalic 
  lobes 
  ; 
  (3) 
  that 
  the 
  eyes 
  

   are 
  a 
  specialized 
  group 
  of 
  epidermal 
  cells 
  of 
  the 
  upper 
  part 
  of 
  the 
  pro- 
  

   cephalic 
  lobes, 
  and 
  are 
  not 
  homologues 
  of 
  the 
  antennae 
  or 
  of 
  the 
  append- 
  

   ages 
  in 
  general 
  ; 
  and 
  (4) 
  it 
  seems 
  to 
  follow 
  from 
  a 
  study 
  of 
  the 
  relations 
  

   and 
  mode 
  of 
  development 
  of 
  the 
  clypeus 
  and 
  labrum, 
  that 
  they 
  arise 
  

   between 
  the 
  procephalic 
  lobes, 
  and 
  probably 
  represent 
  the 
  tergal 
  part 
  of 
  

   the 
  antennal 
  or 
  first 
  cephalic 
  segment, 
  forming 
  the 
  roof 
  of 
  the 
  mouth, 
  

   i, 
  e.j 
  closing 
  in 
  from 
  above 
  the 
  pharynx. 
  

  

  The 
  form 
  of 
  the 
  brain 
  and 
  ganglionic 
  chain 
  is 
  well 
  seen 
  in 
  an 
  embryo 
  

   observed 
  February 
  22 
  (PL 
  XYI, 
  Fig. 
  1). 
  All 
  the 
  ganglia, 
  from 
  the 
  brain 
  

   to 
  the 
  last 
  pair, 
  are 
  seen 
  to 
  have 
  a 
  group 
  of 
  ganglion-cells 
  in 
  the 
  center, 
  

   the 
  periphery 
  being 
  free 
  from 
  them; 
  the 
  origin 
  of 
  the 
  main 
  nerves 
  for 
  

   each 
  ganglion, 
  and 
  also 
  the 
  relations 
  of 
  the 
  ganglia 
  to 
  the 
  body-seg- 
  

   ments, 
  were 
  clearly 
  seen 
  in 
  this 
  embryo 
  in 
  life. 
  It 
  appears 
  that 
  there 
  

   are 
  15 
  pairs 
  of 
  ganglia, 
  including 
  the 
  brain; 
  i. 
  e.j 
  two 
  pairs 
  for 
  the 
  head, 
  

   one 
  for 
  each 
  thoracic 
  and 
  abdominal 
  segment. 
  

  

  PI. 
  XVIII, 
  Fig. 
  1, 
  drawn 
  from 
  an 
  embryo 
  observed 
  February 
  23, 
  shows 
  

   the 
  relations 
  of 
  the 
  mandibles, 
  first 
  maxillae, 
  and 
  second 
  maxillae 
  or 
  

   labium. 
  The 
  mandibles 
  remain 
  single-lobed; 
  but 
  in 
  the 
  maxillae, 
  which 
  

   were, 
  as 
  seen 
  in 
  PI. 
  XYII, 
  Fig. 
  1, 
  la, 
  single-lobed, 
  two 
  if 
  not 
  three 
  lobes 
  

   appear, 
  the 
  outer 
  being 
  considerably 
  the 
  larger. 
  The 
  second 
  maxillae 
  

   also 
  have 
  subdivided 
  into 
  two 
  lobes, 
  the 
  outer 
  or 
  labial 
  palpi 
  also 
  the 
  

   larger. 
  It 
  thus 
  appears 
  that 
  the 
  peripheral 
  or 
  terminal 
  parts, 
  ligula, 
  

   palpiger, 
  and 
  palpus, 
  are 
  formed 
  before 
  the 
  submentum 
  and 
  mentum 
  ; 
  

   these 
  being 
  the 
  result 
  of 
  the 
  consolidation 
  of 
  the 
  second 
  maxillae; 
  this 
  

   takes 
  place 
  only 
  shortly 
  before 
  hatching. 
  

  

  The 
  relations 
  of 
  the 
  ceplialic 
  appendages 
  were 
  best 
  seen 
  in 
  the 
  em- 
  

   bryo 
  represented 
  on 
  PI. 
  XVII, 
  Fig. 
  3, 
  and 
  drawn 
  February 
  15. 
  In 
  this 
  

   specimen 
  the 
  first 
  maxilla 
  is 
  seen 
  to 
  be 
  divided 
  into 
  three 
  equal 
  lobes, 
  and 
  

   situated 
  on 
  the 
  outer 
  side 
  of 
  the 
  mandible, 
  while 
  the 
  unequally 
  bilobed 
  

   second 
  maxilla 
  is 
  situated 
  just 
  external 
  to 
  the 
  end 
  of 
  the 
  antenna. 
  

  

  At 
  this 
  time 
  also 
  the 
  hind 
  limbs 
  are 
  decidedly 
  larger 
  than 
  the 
  two 
  

   anterior 
  pairs, 
  and 
  the 
  hind 
  femora 
  are 
  now 
  large 
  and 
  thick, 
  while 
  the 
  

   three 
  main 
  divisions 
  of 
  the 
  legs 
  are 
  clearly 
  indicated. 
  

  

  In 
  the 
  oldest 
  embryo, 
  observed 
  March 
  12, 
  the 
  limbs 
  are 
  in 
  about 
  the 
  

   same 
  state 
  of 
  development, 
  and 
  the 
  tracheae 
  are 
  but 
  slightly 
  more 
  de- 
  

   veloped 
  than 
  when 
  first 
  observed. 
  

  

  Sections 
  of 
  embryo 
  about 
  ready 
  to 
  hatch.-— 
  P\. 
  XIX, 
  Figs. 
  1-4, 
  represents 
  

   sections 
  of 
  the 
  same 
  embryo 
  as 
  in 
  part 
  figured 
  in 
  our 
  Second 
  Report, 
  

   Plate 
  XII, 
  the 
  sections 
  of 
  the 
  head 
  only 
  being 
  there 
  represented. 
  

  

  